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Introduction In the personal care industry, developing products that target or affect the skin, scalp, vaginal, and oral microbiome requires robust scientific validation that meets both biological and regulatory standards. While in vitro  (laboratory) testing provides valuable preliminary data, they cannot fully replicate the complex interactions occurring in the human body. Clinical testing in human subjects on the other hand captures the dynamic interactions between microbial communities and the host in their natural environment. Increasingly, multi-omic approaches, which combine genomic, transcriptomic, proteomic, and metabolomic data, are being used in these human studies to deliver a far more comprehensive understanding of how products influence both microbes and host biology simultaneously. Complexity of the Human Skin Human skin is a highly complex, multi-layered organ whose structure is essential for both barrier function and supporting a balanced microbiome. The epidermis, dermis, and hypodermis create distinct microenvironments with varying oxygen levels, nutrients, and physicochemical properties, while specialized structures, such as, hair follicles, sebaceous and sweat glands, and apocrine glands, provide unique habitats that shape microbial communities (Kolarsick et al ., 2011). Host-microbe interactions are dynamic, with keratinocytes and immune cells continuously communicating with microbes to maintain equilibrium. This means that product effects cannot be separated from host responses, because microbial behavior depends on this three-dimensional architecture. Simplified in vitro systems often fail to predict real-world outcomes.  To further complicate this interaction, skin biology and the microbiome influence each other at multiple molecular layers. Multi-omic analysis enables researchers to capture these layered responses by examining not only changes in microbial composition, but also shifts in gene expression, protein activity, and metabolite production in both the host and the microbiome. This depth of information is only achievable in vivo , where the full biological context, and environmental exposure remains intact. Understanding in vitro  testing  In vitro  testing involves experiments conducted in controlled laboratory environments. Common methods include, Co-culture systems: Culturing multiple microbial species together to study a product's impact on interspecies interactions and community dynamics (Rose et al ., 2024). However this comes with several limitations including, the inability to include the complete microbial ecosystem, as it is difficult to control the ratios between bacterial strains (Shishkov et al ., 2024). Another limitation is that standard liquid media do not accurately mimic the structured, biofilm-rich environment of the skin. Non-adherent bacteria can be lost during media changes, and competitive dynamics among strains can lead to overgrowth of certain species, reducing the physiological relevance of the model (Shishkov et al ., 2024). 2D and Scaffold-Based 3D Skin Models: 2D skin models consist of keratinocytes grown as monolayers, sometimes co-cultured with fibroblasts, and are widely used for rapid, inexpensive screening of cytotoxicity, cellular uptake, and basic responses to ingredients, however, they lack the 3D architecture and barrier function of real skin. Scaffold-based 3D skin models, such as reconstructed human epidermis (RHE) and full-thickness human skin equivalents (FTHSE), use natural, synthetic, or decellularized scaffolds to mimic the extracellular matrix and support multilayered cell growth, differentiation, and fibroblast-keratinocyte interactions. These models better replicate the stratum corneum, barrier function, and cellular crosstalk, allowing testing of product effects on toxicity, irritation, penetration, and even disease-like conditions, nonetheless, they still lack appendages, full vascularization, and all native cell populations, limiting their ability to fully predict skin responses, particularly for microbiome interactions (Galvan, Pellicciari & Calderan, 2024). While these methods offer controlled conditions for initial screening, and are continuously evolving, they cannot still replicate the complex microenvironment of human tissues that personal care products actually encounter during use. Limitations of in vitro  testing While 3D skin models improve physiological relevance compared with 2D cultures, they still have important limitations for studying the human skin microbiome. Most models lack skin appendages such as hair follicles and sebaceous glands, making it difficult to culture anaerobic bacteria like Cutibacterium  or maintain a complete microbial community. Simple synthetic membranes or 2D models cannot support symbiotic host-microbe interactions and are limited to very short-term experiments. Even simplified 3D models that recreate only the stratum corneum can maintain microbial populations for about a week but do not replicate the full tissue complexity needed for barrier function or product testing (Galvan, Pellicciari & Calderan, 2024). Additionally, environmental factors such as moisture, pH, sebum production, and exposure to cosmetic or hygiene products vary widely among individuals and are challenging to model in vitro . So while in vitro  testing is essential for initial screening and mechanistic studies, its predictive value for real-world human outcomes is limited.  What do the regulatory bodies say According to the Cosmetic Supervision and Administration Regulation (CSAR) and the Standards for Cosmetic Efficacy Claim Evaluation, “claims of cosmetics need to be supported by scientific evidence”, and in vitro  data alone may no longer be sufficient for substantiating personal care product claims (Ferreira et al ., 2022).  Similarly, the UK Advertising Standards Authority (ASA) acknowledges that while in vitro proof-of-concept studies are valuable in research, they should generally be supported by relevant human data, ideally reflecting the target population (CAP News, 2021). For “new” or “breakthrough” objective claims, the ASA and the Committee of Advertising Practice (CAP) require more stringent evidence, typically including at least one well-controlled experimental human study, often complemented by observational data (AdviceOnline, 2025). Consistent with these standards, QVC also mandates that all product claims regarding safety and efficacy, whether made on-air or off-air, must be substantiated with adequate documentation, which may include third-party clinical testing where appropriate (Quality Assurance Overview, 2018). Together these regulatory bodies highlight a clear expectation across markets, that claims must be grounded with credible, scientifically validated evidence. Through robust human studies and transparent documentation, brands are expected to demonstrate that their products perform safely and effectively as advertised. Understanding Clinical testing Clinical testing for personal care products involves evaluating formulations directly on human volunteers under conditions that simulate real-world use. Standard methodologies include, Randomized Controlled Trials (RCTs): Gold-standard studies where participants are randomly assigned to treatment or control groups to minimize bias (Braga et al ., 2024). Skin Sampling Techniques: Methods such as skin swabs, tape strips, and punch biopsies are employed to collect microbial samples from various skin sites (Santiago-Rodriguez et al ., 2023).  Microbiome Analysis: 16S rRNA gene sequencing, whole-genome shotgun metagenomics, and transcriptomic profiling to characterize microbial community changes (Santiago-Rodriguez et al ., 2023). Biophysical Measurements: Non-invasive instrumentation to assess skin barrier function, hydration, sebum production, pH, and desquamation (Hwang et al ., 2021). Perception Questionnaires: Standardized questionnaires capturing subjective experiences of relief, comfort, and product acceptability. They bridge the gap between biological data and user perception, ensuring that the observed microbial or biophysical data translate into meaningful benefits for consumers. Clinical testing in humans captures the dynamic interactions between microbial communities and the host in their natural environment. By studying human participants, researchers can assess the full diversity of microbiomes that are absent in artificial culture systems. Moreover, clinical testing supports the development of personalized treatments by accounting for inter-individual variability in microbial composition, genetics, and lifestyle factors, which can significantly influence outcomes. Without clinical testing, laboratory findings, even those that appear promising  in vitro , may fail to translate into real benefits for patients or consumers.  In vitro models provide mechanistic understanding and cost-effective early screening, however, only well-designed clinical trials can deliver the comprehensive evidence necessary to substantiate product claims, ensure consumer safety, and demonstrate meaningful benefits reflective of the complex interactions in living humans.  Moreover, human skin exhibits remarkable diversity across ethnicities, ages, genders, and body sites. Clinical testing captures this variability by enrolling participants representative of the target population, providing insights into how products perform across different skin types and conditions. This population-level understanding is essential for developing inclusive products that deliver consistent benefits to diverse consumer groups.  Furthermore, clinical testing provides the foundation for consumer confidence and commercial success. Products supported by robust clinical evidence convey scientific credibility and a commitment to consumer well-being, setting them apart in an increasingly competitive marketplace. As consumers become more informed about skincare and microbiome science, there is a growing expectation for transparency and data-driven validation. Incorporating multi-omic analysis into clinical studies strengthens this further by demonstrating not only visible outcomes but also the underlying biological mechanisms, offering a deeper level of scientific clarity that resonates with both regulators and consumers. Therefore, it is essential that products are substantiated by rigorous scientific research and evaluated on real human skin to ensure both efficacy and trustworthiness. About Sequential Sequential helps simplify the entire process of generating strong scientific evidence for personal care products, by handling recruitment, sampling, analysis, and data reporting in one place, so that it runs faster and smoother. Our clinical testing approach shows how products perform in real-world conditions, across skin, scalp, vaginal, and oral sites, so brands can make confident decisions backed by high-quality microbial and molecular data (multi-omics).  A proprietary non-invasive sampling method ensures consistent, rich biological material with minimal irritation for participants, supporting smoother studies and stronger datasets. Each study is tailored to match the intended consumer population, supported by biophysical measurements and perception data to capture both measurable effects and user experience. This provides a complete dataset that demonstrates efficacy, and strengthens claim substantiation. All data and results are presented in clear, detailed, easy-to-interpret reports, making it simple for anyone to understand the science, and translate the insights directly into formulation improvements, claims, and product strategy. By handling all these processes under one roof, Sequential reduces complexity, shortens timelines, and provides brands with clear, actionable insights, making it easier to deliver products that are credible, effective, and trusted. References  AdviceOnline, 2025 June 23; Substantiation for health, beauty, and slimming claims. https://www.asa.org.uk/advice-online/substantiation-for-health-beauty-and-slimming-claims.html Braga LH, Farrokhyar F, Dönmez Mİ, Nelson CP, Haid B, Herbst K, Garriboli M, Cascio S, Nieuwhof-Leppink A, Kaefer M, Bägli DJ, Kalfa N, Ching C, Fossum M, Harper L. Randomized controlled trials - The what, when, how and why. J Pediatr Urol. 2025 Apr;21(2):397-404. doi: 10.1016/j.jpurol.2024.11.021. Epub 2024 Dec 3. PMID: 39701869. CAP News, 2021 Jan 28; Skin in the game - an update on microbiome claims for cosmetics. https://www.asa.org.uk/news/skin-in-the-game-an-update-on-microbiome-claims-for-cosmetics.html Ferreira M, Matos A, Couras A, Marto J, Ribeiro H. Overview of Cosmetic Regulatory Frameworks around the World. Cosmetics . 2022; 9(4):72. https://doi.org/10.3390/cosmetics9040072 Galvan A, Pellicciari C, Calderan L. Recreating Human Skin In Vitro: Should the Microbiota Be Taken into Account? Int J Mol Sci. 2024 Jan 18;25(2):1165. doi: 10.3390/ijms25021165. PMID: 38256238; PMCID: PMC10816982. Hwang BK, Lee S, Myoung J, Hwang SJ, Lim JM, Jeong ET, Park SG, Youn SH. Effect of the skincare product on facial skin microbial structure and biophysical parameters: A pilot study. Microbiologyopen. 2021 Oct;10(5):e1236. doi: 10.1002/mbo3.1236. PMID: 34713611; PMCID: PMC8494714. Kolarsick, Paul A. J. BS; Kolarsick, Maria Ann MSN, ARHP-C; Goodwin, Carolyn APRN-BC, FNP. Anatomy and Physiology of the Skin. Journal of the Dermatology Nurses' Association 3(4):p 203-213, July 2011. | DOI: 10.1097/JDN.0b013e3182274a98 Quality Assurance Overview, 2018 July. https://www.qvcuk.com/content/dam/qvc_uk/pdf/vendor-relations/QVC%20UK%20Beauty%20Overview.pdf?srsltid=AfmBOor499tO1ighEImeZfonX-1M6ohWHkfnKQh_RC7k1buX5A91mI3- Roso, A., Pecastaings, S., Cambos, S., Martin, R., Bauchet, L., Roubinet, B., ... & Garcia, C. (2024). An Innovative Model Based on Wild Type Bacteria Co-Culture to Identify Cosmetic Ingredients That Respect the Skin Microbiota. Journal of Cosmetic Science , 75 (6). Santiago-Rodriguez TM, Le François B, Macklaim JM, Doukhanine E, Hollister EB. The Skin Microbiome: Current Techniques, Challenges, and Future Directions. Microorganisms. 2023 May 6;11(5):1222. doi: 10.3390/microorganisms11051222. PMID: 37317196; PMCID: PMC10223452. Shishkov, Vsevolod & Bikmulina, Polina & Kardosh, Anna & Tsibulnikov, Sergey & Grekova, Ekaterina & Kolesova, Yulia & Zakharova, Polina & Nesterova, Anastasiia & Pereira, Frederico & Kotova, Svetlana & Olisova, Olga & Vosough, Massoud & Shpichka, Anastasia & Timashev, Peter. (2024). Advancing the in vitro drug screening models: Microbiome as a component of tissue-engineered skin. Bioprinting. 45. e00379. 10.1016/j.bprint.2024.e00379.

The lips may be a small part of the face, but biologically, they behave in entirely unique ways. As temperatures drop and humidity shifts, your lips feel the change immediately; a reminder of how delicate they are and how much care they truly need. What we know Despite their importance, lips remain one of the least researched skin sites, especially regarding the microbiome. Current scientific knowledge highlights that: Lip skin has significantly higher transepidermal water loss (TEWL) and lower water content compared to other facial regions, such as the cheeks. (Kim et al, 2021). Lip skin is less equipped to defend against external stressors due to having no oil glands and a thin stratum corneum.  (Lee et al, 2022). The structural differences make the lip microbiome highly responsive and more easily disrupted by environmental impactors including cold weather, UV exposure, and airflow. These contribute to irritation, chapping, and inflammation (Gfeller et al, 2019). Industry Impact and Potential The unique biology of lip skin creates both a challenge and an opportunity for product innovation. Potential areas of innovation include: Advanced moisturizing systems: Next-generation blends of oils, waxes, and occlusives that work together to reduce water loss, restore suppleness, and reinforce the lip barrier. Barrier and anti-inflammatory formulations: Formulations including ceramides and panthenol can help stabilise barrier function, calm irritation, and support recovery from environmental stressors.   Age related support: Gentle, microbiome-supportive formulations that address thinning, dryness, and fine lines offer a growing opportunity for targeted, non-irritating lip renewal. Our Solution At Sequential, our customisable services can help brands formulate products that are effective for looking after lips with our extensive microbiome testing. With a database of over 50,000 microbiome samples, 4,000 ingredients, and 10,000+ testing participants, we provide the scientific clarity needed to develop high-performing, microbiome-supportive lip care. Winter may be tough on lips, but with the right science, solutions can be both protective and powerful.   References : Gfeller, C. et al. (2019). Novel lip cream protecting against triggers of recurrent herpes labialis. Clin. Cosmet. Investig. Dermatol. , 12, 193–208.   https://doi.org/10.2147/ccid.s179430 Kim, J. et al. (2021). Relationship between lip skin characteristics and corneocyte unevenness ratio in assessing lip scaling. Int. J. Cosmetic Sci. , 43, 275–282.   https://doi.org/10.1111/ics.12692 Lee, H. & Kim, M. (2022). Skin barrier function and the microbiome. Int. J. Mol. Sci. , 23.   https://doi.org/10.3390/ijms232113071

Introduction Multiomics (i.e., multiple omics; hereafter referred to as omics) is an emerging interdisciplinary approach to studying complex systems that involves integration of biological data from multiple "omics" fields. Typically including a combination (or all) of the following: genomics, epigenomics, transcriptomics, metabolomics, and proteomics. This provides a comprehensive understanding of how these systems operate at multiple scales from the molecular to whole-organism level, including the study of individual hosts and their associated microbial communities (Ning and Li, 2023).  While current approaches to microbiome data analysis mostly involve shotgun metagenomic or 16S rRNA amplicon sequencing, which can provide detailed information on the compositional diversity of these host-associated communities, they fail to provide much depth on their functional role or the complex network of interactions by which they communicate with the host (Chetty and Blekhman, 2024). Omics approaches are able to provide a much more holistic model of these traits by capturing and integrating these multiple omics layers to give a better understanding of the mechanisms underlying these host-microbe interactions, as well as their influence on host health and physiology (Chetty and Blekhman, 2024). This makes them an incredibly ideal technology for use in characterising host microbiomes by providing a comprehensive analysis of these complex systems and their dynamic interplay. Some examples of the types of omics data can be obtained on these host-microbe systems for integrative omics analysis can be viewed in the table below: Such approaches are increasingly being implemented in the context of product development for skin care, where they can provide a holistic perspective on the overall impact of personal care products on both skin health and the microbiome, as well as assessing the interplay between the two. Study 1: Multi-omics analysis to evaluate the effects of solar exposure and a broad-spectrum SPF50+ sunscreen on markers of skin barrier function in a skin ecosystem model (Jacques et al. , 2025) Using an original reconstructed human epidermis (RHE) model colonised with human microbiota and supplemented with human sebum, this study aimed to analyse the effects of simulated solar radiation (SSR) on skin metabolites and lipids. It also assessed the effectiveness of an ultraviolet/blue light (UV/BL) broad-spectrum sunscreen with a high sun protection factor (SPF50+) in protecting the skin using skin biomarkers. This was a follow-up to a previous study conducted by the same authors looking at the effects of SSR on the skin microbiome (Jacques et al. , 2025). Results Comparative metabolomic analyses of the RHE skin model post-irradiation revealed changes in the levels of several natural moisturising factors (NMFs). This included a reduction in the relative amounts of alanine, N-acetyl putrescin, histidine, and glutamine 24 hours after exposure, while lactate, ornithine, trans-UCA and PCA (both on the skin surface and in the epidermis) were found to be higher. The decrease in some of these NMFs could promote skin dehydration following irradiation. Furthermore, the increased abundance of filaggrin byproducts like UCA and PCA may be attributed to the enhanced breakdown of filaggrin (a skin structural protein) upon SSR radiation, with the degradation of this protein contributing to impairment of the physical and biochemical barrier functions of the stratum corneum. Glycerophospholipid metabolism was also affected following SSR exposure in this RHE model, with an increase in the levels of glycerol and reduction in epidermal choline, glycerophosphocholine and phosphorylcholine observed in the treatment group. Such an increase in glycerol could be linked to either enhanced glycerophosphocholine degradation or an impairment in the glycerophospholipid biosynthesis pathway, and may be secreted in response to skin irradiation following irradiation as a way to maintain skin health owing to its hygroscopic nature. Although, this benefit may be offset by the simultaneous decrease in epidermal choline, which may disrupt skin barrier function and promote skin dehydration. Lipidomic analysis found a lower level of free fatty acids (FFAs) in the RHE following SSR exposure, which could be the result of SSR-induced inhibition of enzymes involved in lipid synthesis pathways. These changes may result in an imbalance in skin lipid composition that destabilises skin barrier organisation and integrity. Elevated levels of skin cholesterol were also observed following treatment, where it may work to activate inflammatory pathways associated with sun exposure and cause skin barrier disruption. Furthermore, SSR-exposure was shown to disrupt ceramide biosynthesis and composition in the skin in a manner that might trigger inflammation and disrupt skin barrier function. Following these omics analyses, the group then assessed the effectiveness of a broad-spectrum SPF50+ sunscreen in preventing SSR-induced changes to the skin. They found application of this broad-spectrum SPF50+ sunscreen was able to prevent many of the previously observed changes to NMF, metabolite and ceramide levels following SSR exposure in the RHE model, allowing it to protect the skin and its components against irradiation-induced disruption and consequences like dehydration, inflammation and damage (Jacques et al. , 2025). Conclusion Using a reconstructed skin ecosystem model, this study was able to provide information on the impact of single-dose SSR on the skin metabolome and lipidome, with effects observed in the levels of various skin components like natural moisturising factors, metabolites, and lipids that are predicted to cause irradiation-associated effects such as dehydration, reduced barrier function, and inflammation. They also used similar omics approaches to validate the effectiveness of an innovative UV/BL broad-spectrum SPF50+ sunscreen in preventing these SSR-induced changes to skin components levels, as well as predicting how this might mitigate against any associated negative physical effects (Jacques et al. , 2025). Study 2: Multi-omics approach to understand the impact of sun exposure on an in vitro skin ecosystem and evaluate a new broad-spectrum sunscreen (Jacques et al. , 2024) Using an original reconstructed human epidermis (RHE) model colonised with human microbiota and supplemented with human sebum, this precursor study aimed to analyse the effects of simulated solar radiation (SSR) on skin metabolites and microbiome composition as a way to understand the underlying interactions between the skin and its associated microbiota. It also assessed the effect of a broad-spectrum sunscreen on skin ecosystem metabolites and pathways during SSR exposure (Jacques et al. , 2024). Results Analysis of the skin metabolome following SSR exposure revealed a change in the composition of the whole RHE metabolome, with 51 significantly altered metabolites identified. These included molecules such as uric acid, glutamine/glutamate, and L-pyroglutamic acid/5-oxoproline, which are predicted to play a role in inducing generation of reactive oxygen species (ROS) and oxidative stress pathways in the skin. Lactate production was also elevated following exposure, which can result in skin acidosis to suppress immune function. Furthermore, three distinct metabolic pathways (glycerophospholipid, starch and sucrose, and tetrahydrobiopterin pathways) were also found be significantly affected post-SSR exposure, with the latter possibly having some involvement in mediating host-microbiome interactions following SSR-exposure.  Compositional microbiome analysis was then used to examine the crosstalk between skin components and cutaneous communities following SSR exposure. Following irradiation treatment, Burkholderia and Cutibacterium  became significantly enriched in the skin microbiota, with the latter genus possibly influencing tyrosine metabolism both in and on the surface of the skin via propionate production, a major Cutibacterium  metabolites known to inhibit UVB-induced melanogenesis by inhibiting cellular tyrosinase activity. Further analysis of the skin mycobiome found a reduced abundance of the genus Malassezia , with such a depletion likely influencing the composition of skin metabolites like tryptophan and indole. The lipophilic nature of these yeasts mean they are normally able to convert this tryptophan into indole compounds for immune activation, however, under such conditions their metabolisms might be altered in a way that differentially modules the host immune system and prioritises synthesis of melanin and photoprotective indolic compounds. Like the previous study, after conducting these -omics analyses, the group then assessed the effectiveness of a broad-spectrum SPF50+ sunscreen in preventing SSR-induced changes to the skin and its microbiome. Once again they found application of this broad-spectrum SPF50+ sunscreen to prevent many of the previously observed changes to metabolite and microbiome profiles following SSR exposure in the RHE model, further demonstrating its ability to buffer irradiation-induced disruption and consequences like dysbiosis or inflammation (Jacques et al. , 2024). Conclusion This study is the first to explore the underlying mechanisms of sun exposure on skin host–microbiota interactions and their biological consequences using an in vitro model to represent the skin ecosystem (skin surface lipids and microbiota) and an integrated omics approach combining metabolomic and microbiomic data. Doing so allowed for accurate characterisation of the skin’s metabolomic signature following irradiation-exposure, with changes in the metabolite profile associated with reactive oxygen species (ROS) generation, inflammation and oxidative stress pathways in the skin being observed. They also explored how interactions between the skin and cutaneous microbiota can be influenced under such conditions, including reduced microbial diversity and possible altered function. The SPF50+ sunscreen was also shown to protect against the negative effects of SSR exposure, including disruption to host–microbial interactions and microbial diversity (Jacques et al. , 2024). Study 3: Multi-omic approach to decipher the impact of skincare products with pre/postbiotics on skin microbiome and metabolome (Li et al. , 2023) This clinical study aimed to decipher the impact of pre- and postbiotic skincare products using an integrated omics approach involving 16S rRNA gene sequencing, shotgun metagenomics and untargeted mass spectrometry-based metabolomics to explore the mechanism-of-action of a triple-biotic complex containing a combination of a prebiotic (inulin), a “smart biotic” (butyloctanol) and postbiotics (lactic acid and pyruvic acid) on skin health through modulation of the skin microbiome and metabolome over a 6-week treatment course (Li et al. , 2023). Results The researchers found application of the triple-biotic treatment significantly reduced the abundance of opportunistic pathogens, such as Pseudomonas stutzeri and Sphingomonas anadarae , while also increasing the amount of commensals like Halomonas desiderata  and Streptococcus mitis  that are positively correlated with skin hydration. Further microbiome metagenomic analysis revealed enrichment of bacterial sugar degradation pathways in the prebiotic treatment group compared with baseline controls. This could serve to generate more lactic acid through active degradation of the inulin prebiotic, promoting skin hydration and maintaining its pH. Metabolomic analysis revealed enrichment of several clinically relevant metabolites in the prebiotic group, such as long-chain/medium-chain fatty acids, Fatty acid esters, Fatty Acyls, Dicarboxylic acids and derivatives that are known to have positive effects on skin health. For example, fatty acids and esters, and fatty acyls contribute to skin barrier functions, while dicarboxylic acids have antimicrobial and anti-inflammatory properties. Correlation analysis between microbiome and discriminant clinically relevant metabolites revealed a negative correlation between the reduction of S. anadarae and P. stutzeri  with fatty acids and dicarboxylic acids, while the increase of H. desiderata  was positively correlated to certain metabolites associated with the increase of skin hydration (Li et al. , 2023). Conclusion This study demonstrated a significant positive effect of a triple-biotic complex consisting of a prebiotic, biotic, and postbiotic on the physical and microbial parameters of skin following 6-weeks of topical application, with enhanced skin hydration and a more favourable shift in microbiome composition towards favourable commensals and away for opportunistic pathogens. Some of these commensal species were also found to positively correlate with skin hydration following analysis of the microbiome metagenome and metabolome, presenting potential bacterial targets for the development of future therapeutics (Li et al. , 2023). Strengths and Limitations of Research (integrated omics to skincare) Strengths: The implementation of such integrated omics approaches examining data from various omics datasets has allowed for the successful identification of clinically relevant strains and metabolites of interest that could act as targets for the development of future personal care products addressing a diverse set of issues surrounding skin health, for example, by enriching topical formulations with the desired microbial strains and their metabolites (Li et al. , 2023). Omics can also provide a holistic assessment of product efficacy during testing by accurately modelling how different environmental conditions can affect product performance on a range of parameters such as skin physiology and components by examining the molecular cross-talk that occurs between the three, as well as elucidating the specific mechanism of action by which it is able to do so (Jacques et al. , 2025). The combined analysis of multiple streams of omics data also open up avenues to better understand host-microbiome interactions by linking host physiology to microbiome function, allowing for a more comprehensive analysis of how this dynamic relationship can be altered in response to intrinsic and extrinsic factors, as well as how these interactions can change (or be maintained) by personal product use. This information can be used to improve formulations so that they avoid pushing the microbiome towards unfavourable dysbiosis, or promote a more balanced microbiome in the case of treating dysbiotic disorders (Jacques et al. , 2024). Limitations: Many existing omics studies rely on the use of in vitro  models to gather data on skin physiology and product performance, making it difficult to fully reproduce the complex interplay that exists between host metabolism and the cutaneous microbiota in such a static system (Jacques et al. , 2024). While many omics studies have succeeded in promoting a deeper understanding of host-microbiome interactions, there is still a lacking standardised approach for the integration of these multiomics layers, which can make it difficult to both draw accurate comparisons between studies, and determine whether observations are real or pipeline-related artifacts (Chetty and Blekhman, 2024). Many of the computational tools and bioinformatics infrastructure currently available are significantly limited in their ability to support analysis, integration, and interpretation of these large omics datasets, making it difficult to obtain meaningful insights from the data. Those tools that are able to support these processes are usually inaccessible to smaller research groups and labs owing to cost, further restricting this field of research (Shi et al. , 2025). Future Directions and Research Integrated multigenomics technologies could allow for the development of personalised care products via identification and tracking of differential skin biomarkers combining multiple omics signatures. Altered biomarker profiles can be used as indicators of particular conditions, and returned to baseline using specific ingredients that modulate the expression of these altered components, allowing for more individualised and targeted treatment for various disorders and skin types. Furthermore, understanding individual skin biomarkers can be used to predict the suitability of products for specific individuals, permitting more precise and refined product formulation (Dessì et al. , 2024). They can also provide added dimensionality to deciphering host-microbiome interactions by elucidating the functional role of these microbes and their mechanism of action in influencing skin condition by analysing the products they produce, how these are synthesised, and their overall effects on skin health, as well as offering deeper insight into skin disorders and how this host-microbe crosstalk influences progression (Fernández-Carro et al. , 2025). The growing availability of these omics datasets may facilitate the development of in silico  models that use machine learning to accurately predict the effects of cosmetic ingredients on the skin using existing omics data, acting as a more ethical alternative to existing animal models. Such “infotechnomics” approaches may pave the way for more rapid and accessible ingredient testing for factors like safety (toxicity) and efficacy, streamlining the product formulation process and allowing for greater standardisation (Kalicińska et al. , 2023). Lastly, integrated omics skin biomarkers can be used to monitor the progression of specific skin conditions, as well as predicting susceptibility to disease. This can further promote the development of predictive and preventative therapeutics via biomarker screening approaches for the identification of early diagnostic markers in order to develop effective, personalised treatments to mitigate or reduce the effects of various skin disorders that might emerge later in life (Wei et al. , 2024). Conclusion Omics provides an interdisciplinary approach to studying skin health and the microbiome, with research increasingly focusing on the application of these technologies for the development of personal care products and their effects on this dynamic host-microbial system. This allows for a holistic assessment of skin biomarkers and how these components can be altered by various products and external conditions, with many positive implications for product formulations and skin monitoring. However, despite providing an increased understanding of these complex biological systems, much work remains to be done to improve the accuracy and standardisation of such omics models. Improving these limitations can pave the way for the development of personalised products and treatments for various skin conditions, product testing, and preventative diagnostic therapeutics. References Bastonini, E. et al. (2025) ‘Lipidome Complexity in Physiological and Pathological Skin Pigmentation’, International Journal of Molecular Sciences, 26(14), p. 6785. Available at:   https://doi.org/10.3390/ijms26146785 . Chetty, A. and Blekhman, R. (2024) ‘Multi-omic approaches for host-microbiome data integration’, Gut Microbes, 16(1), p. 2297860. Available at:   https://doi.org/10.1080/19490976.2023.2297860 . Dessì, A. et al. (2024) ‘Integrative Multiomics Approach to Skin: The Sinergy between Individualised Medicine and Futuristic Precision Skin Care?’, Metabolites, 14(3), p. 157. Available at:   https://doi.org/10.3390/metabo14030157 . Fernández-Carro, E. et al. (2025) ‘Alternatives Integrating Omics Approaches for the Advancement of Human Skin Models: A Focus on Metagenomics, Metatranscriptomics, and Metaproteomics’, Microorganisms, 13(8), p. 1771. Available at:   https://doi.org/10.3390/microorganisms13081771 . Fukushima-Nomura, A., Kawasaki, H. and Amagai, M. (2025) ‘Integrative omics redefining allergy mechanisms and precision medicine’, Allergology International, 74(4), pp. 514–524. Available at:   https://doi.org/10.1016/j.alit.2025.08.007 . Jacques, C. et al. (2024) ‘Multi-omics approach to understand the impact of sun exposure on an in vitro skin ecosystem and evaluate a new broad-spectrum sunscreen’, Photochemistry and Photobiology, 100(2), pp. 477–490. Available at:   https://doi.org/10.1111/php.13841 . Jacques, C. et al. (2025) ‘Multi-omics analysis to evaluate the effects of solar exposure and a broad-spectrum SPF50+ sunscreen on markers of skin barrier function in a skin ecosystem model’, Photochemistry and Photobiology, 101(2), pp. 373–385. Available at:   https://doi.org/10.1111/php.14001 . Kalicińska, J. et al. (2023) ‘Artificial Intelligence That Predicts Sensitizing Potential of Cosmetic Ingredients with Accuracy Comparable to Animal and In Vitro Tests—How Does the Infotechnomics Compare to Other “Omics” in the Cosmetics Safety Assessment?’, International Journal of Molecular Sciences, 24(7), p. 6801. Available at:   https://doi.org/10.3390/ijms24076801 . Li, M. et al. (2023) ‘Multi-omic approach to decipher the impact of skincare products with pre/postbiotics on skin microbiome and metabolome’, Frontiers in Medicine, 10. Available at:   https://doi.org/10.3389/fmed.2023.1165980 . Liu, Yang et al. (2023) ‘Proteomics and transcriptomics explore the effect of mixture of herbal extract on diabetic wound healing process’, Phytomedicine, 116, p. 154892. Available at:   https://doi.org/10.1016/j.phymed.2023.154892 . Ning, K. and Li, Y. (2023) ‘Introduction to Multi-Omics’, in K. Ning (ed.) Methodologies of Multi-Omics Data Integration and Data Mining: Techniques and Applications. Singapore: Springer Nature, pp. 1–10. Available at:   https://doi.org/10.1007/978-981-19-8210-1_1 . Shi, S. et al. (2025) ‘The role of multiomics in revealing the mechanism of skin repair and regeneration’, Frontiers in Pharmacology, 16. Available at:   https://doi.org/10.3389/fphar.2025.1497988 . Wei, S. et al. (2024) ‘Multiomics insights into the female reproductive aging’, Ageing Research Reviews, 95, p. 102245. Available at:   https://doi.org/10.1016/j.arr.2024.102245 .

Within the skincare sector, Vitamin C has been hailed as an all-round skincare essential product with capabilities of for brightening, antioxidant protection, and collagen support however, its specific effects on the skin microbiome are only beginning to be understood.  What we know: Emerging research suggests that Vitamin C, whether taken as a supplement or applied topically, can support microbial diversity, modulate immune responses, and aid in wound healing. Topical Vitamin C, especially in low-pH formulations, increases microbial diversity without disrupting key bacteria such as Staphylococcus epidermidis  and Cutibacterium acnes (Janssens-Böcker et al,  2024). Vitamin C also has anti-inflammatory and antimicrobial properties, helping manage acne by inhibiting pathogens such as C. acnes , with effects enhanced when combined with zinc or clarithromycin (Sun et al , 2024). Vitamin C also supports the skin barrier and immune function, benefiting skin conditions such as acne, psoriasis, and dermatitis. While mechanisms in disease contexts are still being studied, evidence highlights its microbiome-friendly potential (Joshi et al,  2023). Industry Impact and Potential As microbiome-conscious skincare grows, Vitamin C offers brands opportunities to innovate responsibly. Its dual role as a skin health booster and microbiome-friendly ingredient enables effective, gentle formulations that meet demand for science-backed, sustainable products. Emerging research points to key innovation areas: Combination therapies:  Pairing Vitamin C with actives like zinc or light treatments targets pathogens, reduces inflammation, and supports repair. Personalized skincare:  Understanding Vitamin C’s interaction with individual microbiomes enables tailored products that enhance efficacy while preserving balance. Barrier and wound support:  Vitamin C-based dressings and delivery systems promote healing and antimicrobial protection without cytotoxicity. Our Solution: At Sequential, we specialise in supporting business to innovate confidently by providing comprehensive microbiome product testing. With a database of 50,000+ microbiome samples, 4,000 ingredients, and 10,000+ testing participants, we deliver science-driven, actionable insights that can help guide product formulation. With our expertise and customisable services, we can support the creation of products that not only deliver visible results but also support a healthy and balanced microbiome for long term skin viability. References: Janssens-Böcker, C., Doberenz, C., Monteiro, M., & De Oliveira Ferreira, M., 2024. Influence of Cosmetic Skincare Products with pH < 5 on the Skin Microbiome: A Randomized Clinical Evaluation.  Dermatology and Therapy , 15, pp. 141 - 159. https://doi.org/10.1007/s13555-024-01321-x . Joshi, M., Hiremath, P., John, J., Ranadive, N., Nandakumar, K., & Mudgal, J., 2023. Modulatory role of vitamins A, B3, C, D, and E on skin health, immunity, microbiome, and diseases.  Pharmacological Reports , 75, pp. 1096 - 1114. https://doi.org/10.1007/s43440-023-00520-1 . Sun, C., Na, Y., Wang, Z., Zhu, T., & Liu, X., 2024. Phytochemicals, promising strategies combating Cutibacterium acnes.  Frontiers in Pharmacology , 15. https://doi.org/10.3389/fphar.2024.1476670 .

Teeth whitening, or dental bleaching, is a popular cosmetic procedure aimed at lightening teeth colour. Despite its widespread use, the impact of these treatments on the oral microbiome remains underexplored.  What We Know: Most in-office teeth whitening treatments rely on hydrogen peroxide (HP) or its precursor, carbamide peroxide (CP). As products containing > 0.1% peroxide are typically restricted to dentist-prescribed use, over-the-counter alternatives have emerged, including agents such as phthalimidoperoxycaproic acid, sodium chlorite and sodium bicarbonate. Additionally, natural enzymes like bromelain, papain and cysteine proteases have also been tested as whitening agents in vitro (Müller-Heupt et al., 2023). Peroxides, especially HP, are considered the gold standard for teeth whitening. They generate reactive free radicals that oxidise organic chromophores, like those from coffee, red wine or tea. This oxidation breaks down the chromophores into smaller molecules that absorb fewer wavelengths of visible light, making the teeth appear lighter (Müller-Heupt et al., 2023). Although peroxide-based treatments are safe and effective, they cause temporary tooth sensitivity in 43-80% of patients. This sensitivity is likely due to microscopic damage to the enamel, which allows oxygen radicals to reach the dental nerve, causing inflammation and temporary discomfort (Müller-Heupt et al., 2023). Industry Impact and Potential: Some oral microbes, including viridans streptococci , exhibit resistance to peroxide. These bacteria can survive in HP environments and may even metabolise it. Salivary enzymes like lactoperoxidase further help reduce the toxicity of HP, protecting bacteria from its effects. While in vitro  studies have shown that CP can inhibit certain bacteria, these findings have not been consistently observed in vivo . Overall, dental bleaching does not significantly disrupt the oral microbiome, as the overall population of microorganisms remains stable (Franz-Montan et al., 2009).  HP whitening agents can temporarily reduce Streptococcus mutans populations. However, these reductions are short-lived, with S. mutans  levels returning to baseline within 30 days. In contrast, CP whitening shows no significant effect on S. mutans . The antimicrobial action of HP is localised to the treatment area and works by damaging bacterial DNA and disrupting metabolic processes. Whitening agents have minimal effects on areas like saliva and buccal mucosa due to limited gel contact and protective enzymes (Briso et al., 2018). Our Solution: Sequential specialises in microbiome analysis and product development across oral, skin, scalp and vulvar areas. By pioneering innovative solutions, we support and preserve the microbiome. With our expertise, we are equipped to collaborate with your company in developing teeth-whitening products that promote both a healthy oral microbiome and overall oral health. References: Briso, A., Silva, Ú., Souza, M., Rahal, V., Jardim Júnior, E.G. & Cintra, L. (2018) A clinical, randomized study on the influence of dental whitening on Streptococcus mutans population. Australian Dental Journal. 63 (1), 94–98. doi:10.1111/adj.12569. Franz-Montan, M., Ramacciato, J.C., Rodrigues, J.A., Marchi, G.M., Rosalen, P.L. & Groppo, F.C. (2009) The effect of combined bleaching techniques on oral microbiota. Indian Journal of Dental Research: Official Publication of Indian Society for Dental Research. 20 (3), 304–307. doi:10.4103/0970-9290.57367. Müller-Heupt, L.K., Wiesmann-Imilowski, N., Kaya, S., Schumann, S., Steiger, M., Bjelopavlovic, M., Deschner, J., Al-Nawas, B. & Lehmann, K.M. (2023) Effectiveness and Safety of Over-the-Counter Tooth-Whitening Agents Compared to Hydrogen Peroxide In Vitro. International Journal of Molecular Sciences. 24 (3), 1956. doi:10.3390/ijms24031956.

Excess scalp sebum production - which causes greasy or oily hair roots - is closely linked to microbiome dysbiosis, sensitivity of the scalp and other scalp conditions, such as hair loss (alopecia). Emerging research suggests that optimising the balance and diversity of this microbiome through targeted cosmetic products may treat and prevent sebum buildup, leading to improved overall hair health. What We Know: The scalp microbiome refers to the diverse community of microorganisms that inhabit the scalp. It is shaped by both intrinsic factors (age, sex, genetics and diet) as well as extrinsic factors (pollution, UV radiation and cosmetic use). Its unique environment - characterised by sebum, as well as oxygen levels, moisture, pH and a high density of hair follicles - fosters the growth of microorganisms, including Malassezia  yeasts and bacteria such as  Staphylococcus capitis , Staphylococcus epidermidis  and Cutibacterium acnes  (Townsend, Hazan & Dell’Acqua, 2023). Excess scalp sebum can lead to a sensitive, flaky scalp, as well as dandruff and seborrheic dermatitis, which are linked to inflammation, impaired scalp barrier function and increased growth of lipophilic microbes like Malassezia  (Townsend, Hazan & Dell’Acqua, 2023). Industry Impact and Potential: Products designed to address scalp dysbiosis, excess sebum, irritation and flakiness can help rebalance oil levels, increase hydration and reduce irritation, without disrupting the scalp's pH or microbiome. Gentle formulations using appropriate ingredients are key to improving overall scalp health and reducing oily hair. For example, ingredients like sarcosine and jojoba ester beads help reduce sebum without disrupting the microbiome, promoting a healthier environment for hair growth (Townsend, Hazan & Dell’Acqua, 2023). Patchoul’Up™ by Givaudan takes a microbiome-focused approach to scalp care. Formulated with Phenethyl Alcohol and Pogostemon Cablin (Patchouli) Leaf/Stem Extract, it was tested in a 0.5% shampoo over 28 days in a double-blind, placebo-controlled study. The results showed a 22% increase in beneficial Cutibacterium, a 34% boost in sebum, and up to a 31% reduction in white flakes, indicating better scalp hydration and balance. With its plant-based composition, the ingredient helps restore a healthy scalp and reduce dryness, flakiness, and microbial imbalance. Moreover, balancing the scalp microbiome can help regulate sebum production, indicating that microbiome-targeted care may also offer a solution for managing greasy hair. Our Solution: With a vast database of over 20,000 microbiome samples and 4,000 ingredients, and a global network of more than 10,000 testing participants, Sequential offers comprehensive services for evaluating product impacts and formulations. Our customisable microbiome studies provide real-world testing environments, while our formulation support ensures products maintain microbiome integrity, making us your ideal partner to investigate microbiome-targeting products. References: Townsend, N., Hazan, A. & Dell’Acqua, G. (2023) New Topicals to Support a Healthy Scalp While Preserving the Microbiome: A Report of Clinical and in Vitro Studies. The Journal of Clinical and Aesthetic Dermatology. 16 (10 Suppl 1), S4–S11.

The female reproductive tract (FRT) and gut share bidirectional communication. These systems exchange not only microbes, but also metabolites, hormones, and immune signals that shape the vaginal microbiome. What We Know: The FRT includes two regions: the lower tract (vulva, vagina, ectocervix) and the upper tract (endocervix, uterus, fallopian tubes, and ovaries). Recent studies support the existence of axes connecting the vagina to other organs, including the gut–vagina axis and bladder–vagina axis (Takada et al, 2023). Microbial overlap between the gut and vagina is common. Genetic comparisons of Lactobacillus crispatus  and L. rhamnosus  from both sites suggest they undergo site-specific adaptation. Strains show different gene expression profiles and traits—like stress tolerance, growth rate, adhesion, and fermentation—depending on their body location (Pan et al, 2020). Short-chain fatty acids (SCFAs) produced by microbiota may influence vaginal health. In the gut, SCFAs support barrier integrity and have anti-inflammatory roles. In contrast, in the vagina, elevated SCFAs are linked to inflammation and microbiome imbalance (Amabebe et al, 2020). Host immune factors also play a role. Antimicrobial peptides (AMPs) secreted by epithelial and immune cells help regulate which microbes thrive in the vaginal environment—and microbial communities can influence immune responses in return. Advances in IgA-sequencing have shown that vaginal communities dominated by L. crispatus  have a higher proportion of IgA-coated bacteria, which are thought to promote microbial stability (Breedveld et al, 2022). Research suggests that IgA-producing immune cells in the vagina originate from the gut (Kobayashi et al, 2024). These cells become activated in the intestine, migrate to the reproductive tract, and secrete Lactobacillus-specific IgA, which enhances colonization of beneficial strains. This points to a potential mechanism by which gut immunity shapes the vaginal microbiome (Takada et al, 2025).   Industry Impact and Potential: There’s growing interest in using oral probiotics to support vaginal health, especially through the gut–vagina axis. This route may offer a convenient and non-invasive way to influence the vaginal microbiome by modulating gut microbes and immune responses (Romeo et al., 2024). New tools like IgA-sequencing and multi-site microbiome profiling are making it possible to track how bacteria and immune cells interact across the gut and reproductive tract. These methods could help researchers and product developers identify which strains are most effective for long-term colonisation and immune support. At the same time, many vaginal probiotic products on the market lack solid clinical evidence or regulatory backing. This highlights the need for better-designed studies and validated products that can actually deliver on their health claims.   Our Solution:   At Sequential, we support microbiome product development and testing from our global hubs in Cambridge, New York, and Singapore. Our flexible services help businesses innovate with confidence—ensuring their products maintain microbiome integrity while meeting efficacy and sustainability targets. We collaborate on studies exploring the FRT–gut microbiome axis and work with partners to develop impactful, science-backed solutions that improve health outcomes.   References: Amabebe, E. and Anumba, D.O.C., 2020. Female gut and genital tract microbiota-induced crosstalk and differential effects of short-chain fatty acids on immune sequelae. Frontiers in Immunology , 11, p.2184. https://doi.org/10.3389/fimmu.2020.02184 Breedveld, A.C., Schuster, H.J., van Houdt, R., Painter, R.C., Mebius, R.E., van der Veer, C. and van Egmond, M., 2022. Enhanced IgA coating of bacteria in women with Lactobacillus crispatus -dominated vaginal microbiota. Microbiome , 10, p.15. https://doi.org/10.1186/s40168-021-01198-4 Breedveld, A. and van Egmond, M., 2019. IgA and FcαRI: Pathological roles and therapeutic opportunities. Frontiers in Immunology , 10, p.553. https://doi.org/10.3389/fimmu.2019.00553 Kobayashi, O., Taguchi, A., Nakajima, T., Ikeda, Y., Saito, K. and Kawana, K., 2024. Immunotherapy that leverages HPV-specific immune responses for precancer lesions of cervical cancer. Taiwanese Journal of Obstetrics and Gynecology , 63, pp.22–28. https://doi.org/10.1016/j.tjog.2023.10.002 Pan, M., Hidalgo-Cantabrana, C. and Barrangou, R., 2020. Host and body site-specific adaptation of Lactobacillus crispatus  genomes. NAR Genomics and Bioinformatics , 2(1), lqaa001. https://doi.org/10.1093/nargab/lqaa001 Romeo, M., D’Urso, F., Ciccarese, G., Di Gaudio, F. & Broccolo, F., 2024. Exploring oral and vaginal probiotic solutions for women’s health from puberty to menopause: a narrative review. Microorganisms , 12(8), p.1614.  https://doi.org/10.3390/microorganisms12081614 Takada, K., et al., 2023. Female reproductive tract–organ axes. Frontiers in Immunology .  https://pmc.ncbi.nlm.nih.gov/articles/PMC9927230/ Takada, K., et al., 2025. IgA and the gut–vagina axis. Frontiers in Immunology .  https://www.frontiersin.org/journals/immunology/articles/10.3389/fimmu.2025.1547303/full

Hypochlorous acid (HOCl) has gained significant attention in the skincare world, celebrated for its powerful antibacterial properties and its role in preventing breakouts. While widely acknowledged for its acne-fighting benefits, its broader effects on the facial skin microbiome are less well understood. What We Know: HOCl is a naturally occurring compound produced by the immune system during the "oxidative burst:" a key immune response in which white blood cells generate highly reactive molecules to fight off pathogens. As an oxidant, HOCl kills bacteria by disrupting their proteins and lipids through peroxidation or halogenation. This broad-spectrum activity makes it effective against a wide range of pathogens (Stroman et al., 2017) . Research has shown that 0.01% HOCl is highly effective at killing harmful bacteria and fungi on the skin, including those associated with acne. It performs as well, or better, than traditional antiseptics, making it a powerful yet gentle skincare ingredient. Crucially, HOCl targets harmful microbes while leaving the skin’s beneficial bacteria largely unaffected. This makes it especially promising for use in sensitive areas like around the eyes, though more research is needed to fully explore its effects on delicate skin (Anagnostopoulos et al., 2018) . HOCl has demonstrated an ability to reduce bacterial load by over 99%, particularly staphylococcal  species like Staphylococcus epidermidis , which, although generally harmless and part of the skin's natural microbiome, can contribute to conditions like blepharitis and meibomian gland dysfunction under certain circumstances (Anagnostopoulos et al., 2018) . Industry Impact and Potential: As awareness of HOCl's benefits continues to grow, several skincare brands have introduced HOCl-based products.  These products tap into the increasing demand for microbiome-friendly skincare, offering an alternative to harsher chemicals that can disrupt the skin's natural balance. With its ability to fight harmful bacteria without damaging the skin microbiome, HOCl is well-positioned to become a key ingredient in the future of skincare. Our Solution: At Sequential, we are at the forefront of microbiome research, backed by a vast database of over 20,000 microbiome samples, 4,000 ingredients and a global network of 10,000 testing participants. Our customisable solutions span microbiome studies and product formulation, with a strong emphasis on biome integrity. Whether we are researching the skin, scalp, oral, or vulvar microbiomes, we are your ideal partner for advancing research and developing microbiome-focused products. By studying the effects of ingredients like HOCl on the skin microbiome, we help ensure that skincare products are both effective and gentle, promoting long-term skin health. References: Anagnostopoulos, A.G., Rong, A., Miller, D., Tran, A.Q., Head, T., Lee, M.C. & Lee, W.W. (2018) 0.01% Hypochlorous Acid as an Alternative Skin Antiseptic: An In Vitro Comparison. Dermatologic Surgery . 44 (12), 1489. doi:10.1097/DSS.0000000000001594. Stroman, D.W., Mintun, K., Epstein, A.B., Brimer, C.M., Patel, C.R., Branch, J.D. & Najafi-Tagol, K. (2017) Reduction in bacterial load using hypochlorous acid hygiene solution on ocular skin. Clinical Ophthalmology . 11, 707–714. doi:10.2147/OPTH.S132851.

Silver is widely recognised for its antimicrobial properties, but its precise effects on the skin microbiome remain an emerging area of research. Recent studies suggest that silver could offer both opportunities and challenges in treating skin-related conditions. What We Know: Silver is commonly incorporated into products such as gels, dressings and textiles in forms like nanoparticles, silver oxynitrate and colloidal silver (Silva, Teixeira & Reis, 2023). Silver nanoparticles exhibit strong antibacterial activity, particularly against Staphylococcus epidermidis  and Staphylococcus aureus  - key skin microbiome components that can form biofilms. These biofilms make bacterial infections harder to treat and more resistant to antibiotics, positioning silver as a promising alternative (Swolana & Wojtyczka, 2022). The antimicrobial mechanism of silver nanoparticles involves disrupting bacterial cell membranes, generating reactive oxygen species (ROS) and interfering with bacterial DNA and proteins. Their effectiveness depends on factors like particle size, shape and concentration (Swolana & Wojtyczka, 2022). Additionally, silver-based gels show increased antimicrobial action with higher concentrations. They are particularly effective against Gram-negative bacteria and have the potential to alter microbial composition while maintaining physicochemical stability, making them viable options for skin infection treatments (Silva, Teixeira & Reis, 2023). Industry Impact and Potential: Recent research into silver-threaded clothing revealed that while silver increased microbial diversity and enriched certain low-abundance bacterial taxa, it did not reduce overall microbial biomass. Instead, it altered the skin’s chemical profile, notably increasing monounsaturated fatty acids (MUFAs) and driving site- and gender-specific changes in the microbial composition (Melnik et al., 2023). This indicates silver’s potential to modulate the skin microbiome in targeted ways. However, questions remain about its long-term effects, particularly its impact on microbiome stability and beneficial microbes. Future research could optimise concentrations and delivery mechanisms to maximize therapeutic benefits while minimizing unintended consequences (Melnik et al., 2023). While silver’s antimicrobial properties are promising, its broader effects on skin health require deeper investigation​ (Swolana & Wojtyczka, 2022). Our Solution: Sequential is leading the way in microbiome research, leveraging a database of 20,000 microbiome samples, 4,000 ingredients and a global network of 10,000 testing participants. Our customisable solutions span microbiome studies and product formulation, with a strong emphasis on preserving biome integrity. Whether exploring the skin, scalp, oral or vulvar microbiome, we are your trusted partner in advancing science and innovation. References: Melnik, A.V., Callewaert, C., Dorrestein, K., Broadhead, R., Minich, J.J., Ernst, M., Humphrey, G., Ackermann, G., Gathercole, R., Aksenov, A.A., Knight, R. & Dorrestein, P.C. (2023) The Molecular Effect of Wearing Silver-Threaded Clothing on the Human Skin. mSystems. 8 (1), e0092222. doi:10.1128/msystems.00922-22. Silva, J.M., Teixeira, A.B. & Reis, A.C. (2023) Silver-based gels for oral and skin infections: antimicrobial effect and physicochemical stability. Future Microbiology. 18, 985–996. doi:10.2217/fmb-2023-0034. Swolana, D. & Wojtyczka, R.D. (2022) Activity of Silver Nanoparticles against Staphylococcus spp. International Journal of Molecular Sciences. 23 (8), 4298. doi:10.3390/ijms23084298.

An imbalanced oral microbiome is a key contributor to the development of dental caries, periodontitis, and halitosis. Probiotics offer promising solutions to help restore microbial equilibrium and support sustained oral health. What We Know: Research increasingly shows that oral diseases are influenced not only by individual pathogens or opportunistic bacteria, but by the overall structure and function of the microbial community. It is therefore essential to study the oral microbiome as an integrated ecosystem rather than focusing solely on single species (Yu et al., 2024). Several species have been investigated for their probiotic potential in oral care, including Lactobacillus plantarum  and Weissella cibaria . A recent review on L. plantarum  highlights its capacity to suppress opportunistic species such as Streptococcus mutans  and Candida albicans , as well as reduce oral inflammation. These properties suggest its potential use in caries and periodontitis prevention (Huang et al., 2024). Clinical studies of W. cibaria  have demonstrated reductions in volatile sulfur compounds (VSCs), improved halitosis scores, and better gingival health. One trial observed changes in microbiota composition and a reduction in bleeding on probing following 8 weeks of supplementation (Han et al., 2023). These probiotics appear to act through a combination of mechanisms: competitive exclusion of opportunistic species, production of antimicrobial compounds like bacteriocins, modulation of pH, and immune system interactions. Common delivery formats include lozenges, chewable tablets, mouth rinses, and functional chewing gums—formulations that promote direct contact with oral surfaces and support colonisation (Kang et al., 2020).   Industry Impact and Potential:   While short-term benefits of oral probiotics are well supported, long-term colonisation and sustained effects remain a key focus. Studies show that microbiome changes can reverse once probiotic intake stops, highlighting the need for well-designed longitudinal studies to assess durability and safety over time (Yu et al., 2024).   Our Solution:   Sequential provides a comprehensive end-to-end Microbiome Product Testing Solution coupled with expert guidance in product development and formulation. Drawing on our extensive expertise, we collaborate with businesses to pioneer innovative strategies for creating topical treatments that, for example, may harness the power of probiotics.   References: Huang, X., Bao, J., Yang, M., Li, Y., Liu, Y., & Zhai, Y. (2024). The role of Lactobacillus plantarum  in oral health: a review of current studies. Journal of Oral Microbiology , 16 (1). https://doi.org/10.1080/20002297.2024.2411815 Han HS, Yum H, Cho YD, Kim S. Improvement of halitosis by probiotic bacterium Weissella cibaria  CMU: A randomized controlled trial. Front Microbiol. 2023 Jan 17;14:1108762. doi: 10.3389/fmicb.2023.1108762. PMID: 36733919; PMCID: PMC9886871. Kang, MS., Lee, DS., Lee, SA. et al.  Effects of probiotic bacterium Weissella cibaria  CMU on periodontal health and microbiota: a randomised, double-blind, placebo-controlled trial. BMC Oral Health  20, 243 (2020). https://doi.org/10.1186/s12903-020-01231-2 Yu X, Devine DA, Vernon JJ. Manipulating the diseased oral microbiome: the power of probiotics and prebiotics. J Oral Microbiol. 2024 Jan 31;16(1):2307416. doi: 10.1080/20002297.2024.2307416. PMID: 38304119; PMCID: PMC10833113.

Introduction Hyperpigmentation is a common and usually harmless dermatological condition characterised by patches of skin that are darker than the surrounding skin. It can occur as a result of excessive production of the pigment melanin by skin cells, and appears in various forms ranging from melasma to age spots (solar lentigines), or post-inflammatory hyperpigmentation (Plensdorf, Livieratos and Dada, 2017). Melanin-over production and hyperpigmentation has been linked to a range of diverse triggers, including but not limited to, skin injury or inflammation, sun damage, hormonal changes, and pregnancy. Some medicines such as birth control pills and hormone replacement (British Skin Foundation) might also induce hyperpigmentation as a side-effect (National Cancer Institute, 2025).  Certain skin types are more likely to be affected by different types of hyperpigmentation based on physiology and response to risk factors, with lighter skin (Fitzpatrick types I to III) more prone to age spots or ephelides (freckles) (Plensdorf, Livieratos and Dada, 2017), and melasma or post-inflammatory hyperpigmentation occurring more frequently in darker skinned populations (Fitzpatrick types IV to VI) (Lawrence, Syed and Al Aboud, 2025). The role of the skin microbiome in regulating the development of hyperpigmentation conditions is an emerging area of interest in medical dermatology. The skin microbiome is a specialised community of microorganisms (bacteria, fungi, viruses, and more) that live and grow on the skin, where they play an essential role in multiple processes that maintain skin health like preventing growth of pathogens, priming the immune system (Lunjani et al. , 2021), and regulating skin growth and development (Meisel et al. , 2018). Environmental and host-associated factors that affect microbial community structure have been found to correlate with the onset of hyperpigmentation in some cases.  For example, the growth of certain groups of bacteria, such as Corynebacteria , has been found to positively correlate with the emergence of hyperpigmented spots (Dimitriu et al. , 2019). Furthermore, Staphylococcus, Cutibacterium, and Lactobacillus  abundance on the skin might have some protective properties against photoaging and skin injury following UV exposure (Li et al. , 2020). However, very few studies have been conducted looking into the direct relationship between the skin microbiome and hyperpigmentation, with several knowledge gaps remaining surrounding the contribution of resident microbes to maintaining skin homeostasis and emergence of hyperpigmented spots. Understanding this relationship will be key to facilitating the development of skin microbiome-based therapeutics for the treatment of these conditions. Study No. 1: Bacterial taxa predictive of hyperpigmented skins (Zanchetta et al. , 2022) This clinical study, conducted on 38 European women grouped by facial hyperpigmentation level, aimed to directly characterise the role of the skin microbiota in the emergence of hyperpigmented spots (HPS) by identifying bacterial populations present on skin with dark spots (Zanchetta et al. , 2022). Results: Alpha‐diversity between high HPS and low HPS skin types were found to be similar. However, the significant differences were identified for minor taxa such as Bergeyella, Micrococcus, Paracoccus, Kocuria, Alloiococcus, and Exiguobacterium , which were present in significantly higher proportions in the low HPS skin group, while in the high HPS group Eikenella, Xanthomonas, Brevibacterium, Aerococcus, Turicella, Paucibacter , and Klebsiella were more abundant. Further analysis revealed the bacteria Kocuria and Aerococcus  as being the two taxa best at predicting the HPS level of the skin.  Kocuria  are capable of producing the thiazolyl peptide kocurin, which inhibits the growth of some Staphylococcus aureus  strains associated with chronic skin inflammation and infection, two triggers for the emergence of brown spots. Furthermore, the genus Micrococcus  was found to be present in significantly higher proportions on skins with less HPS (0.95%) compared to those with more HPS (0.21%), where it might play a role in promoting antioxidant and UV-protective properties. Cross‐domain association networks to characterise bacterial interactions associated with different levels of HPS found relationships between dominant skin residents Cutibacterium and Staphylococcus , and Peptoniphilus and Finegoldia  in the group with a low level of HPS. Skin with a higher HPS level instead showed a disappearance of this connection between Cutibacterium and Staphylococcus , while other more fragmented networks emerged like between Streptococcus and Veillonella , or those involving other minor taxa. The overall stability of these associations was higher on skin with a low HPS level (Zanchetta et al. , 2022). Conclusions: These results reveal specific microbiota composition and networks on skins based on level of skin hyperpigmentation, with changes to this capable of possibly altering overall skin physiology, immune regulation and emergence of HPS. They also present an opportunity for the development of cosmetic therapies for hyperpigmentation that target the skin microbiome and its dynamic interactions for skincare applications (Zanchetta et al. , 2022). Study No. 2: Clinical effect of Pediococcus acidilactici PMC48 on hyperpigmented skin (Park et al. , 2024) This clinical study sought to investigate the potential role of the melanin-decomposing probiotic strain Pediococcus acidilactici  PMC48 in skin medicine and cosmetics by looking at its whitening effect when topically applied to artificially UV-induced tanned skin in a cohort of 22 Korean participants (Park et al., 2024). Results: Topical application of PMC48 to UV‑induced hyperpigmented skin led to several significant improvements in physical skin parameters compared to the control group, with a 47.65% reduction in colour intensity, an 8.10% increase in skin brightness, and an 11.82% drop in melanin index reported, demonstrating PMC48’s tyrosinase (an enzyme involved in the melanin-production pathway) inhibition, and melanin degrading capabilities. Skin moisture content of pigmented sites after PMC48 application were also found to improve by 20.94%. Analysis of the microbiomes of the participants revealed skin treated with PMC48 experienced an increase in Lactobacillaceae abundance by up to 11.2% without disturbing other microbial populations or affecting overall community diversity, showing its capacity as an effective skin microbiome modulator.  Furthermore, no symptoms of irritation or allergy were found to occur based on the results of a skin patch test containing the PMC48 culture, which presents this probiotic as a potential skin-friendly therapeutic that can be used for the treatment of hyperpigmentation conditions (Park et al., 2024). Conclusions: P. acidilactici PMC48 shows promise as a potential probiotic for the treatment of hyperpigmentation through the active inhibition of the melanogenesis pathway and degradation of melanin. It also shows evidence of being a safe treatment option that does not compromise skin health or microbiome stability in patients (Park et al., 2024). Study No. 3: A novel professional-use synergistic peel technology to reduce visible hyperpigmentation on face: Clinical evidence and mechanistic understanding by computational biology and optical biopsy (Bhardwaj et al. , 2024) The aim of this study was to investigate and clinically test a novel trichloroacetic acid (TCA) and hydroquinone (HQ)-free multi-acid synergistic technology (MAST) for the reduction of visible hyperpigmentation on the face as a safer alternative to traditional treatments that can often be damaging to people of colour (Bhardwaj  et al., 2024). Results: Using enzyme assays and computational biology, the researchers were able to identify a synergistic mixture of four different acids possessing either peeling (lactic, mandelic, and pyruvic acids or depigmentation (tranexamic) functions for the effective treatment of facial hyperpigmentation in all Fitzpatrick skin types.  The MAST peel was found to demonstrate superior melanin-inhibitive qualities after single application compared to a commercial HQ-KA peel, with 17% reduction in melanin intensity compared to only 1% after the HQ-KA peel, and a significant reduction (50 - 58%) in the expression of genes involved in melanin production. No adverse events were reported by participants receiving the MAST peel treatment, with no frosting or downtime required for recovery. Furthermore, a clear decrease in brown patches and redness was observed in most cases, and global improvement in most subjects for parameters such as uneven pigmentation/skin tone, skin texture, redness (Erythema) and fine lines/wrinkles was also reported. Use of the peel did not induce skin microbiome dysbiosis. However, the researchers did note a noticeable increase in species diversity after chemical peeling accompanied by a decrease in C. acnes  abundance, although these did not induce any harmful effects overall in participants (Bhardwaj  et al., 2024). Conclusion: The multi-acid MAST peel demonstrates high potential as an inclusive treatment for the treatment of hyperpigmentation disorders through its superior anti-pigmentation activity on human skin compared to a commercial peel, as well as clinical efficacy with minimum downtime. Its lack of dysbiotic side-effects also show this technology to be a microbiome-friendly alternative to current conventional hyperpigmentation treatments (Bhardwaj  et al., 2024). Strengths & Limitations of Research Strengths Existing studies have demonstrated a possible relationship between microbiome composition and hyperpigmentation strength, with such findings supporting the development of microbiome-based therapies as well as laying important groundwork for future mechanistic exploration The association between microbiome composition and hyperpigmentation might pave the way for the development of personalised treatments or non-invasive diagnostics to identify microbial biomarkers of hyperpigmentation that can be used to inform precision therapies or prevention strategies for this condition Limitations There exists a very limited number of studies investigating hyperpigmentation and the skin microbiome, meaning research and information regarding the interplay between the two remains limited. More research needs to be conducted before any concrete conclusions can be drawn regarding the microbiome's effect on the development of hyperpigmentation conditions. This gap also restricts the development of microbiome-targeted therapeutics for hyperpigmentation. Further longitudinal studies are also needed to capture the dynamic nature of the skin microbiome in hyperpigmentation over time, including during flare-ups, treatment, or with seasonal/life changes. Interventional studies using prebiotics, probiotics, or even postbiotics, also remain sparse, which contributes to the limitation in therapeutic development. Many microbiome-hyperpigmentation studies focus on specific ethnic groups or skin types, which may not be generalisable due to ethnic variations in both microbiome composition or pigmentation biology. More inclusive studies are necessary to improve reproducibility of results, and overall efficacy of treatment applications. Related Research & Future Directions   Further studies seeking to distinguish between photoaging and chronological aging effects on hyperpigmentation development can focus on comparing the microbiomes of sun-exposed and unexposed skin as a way to elucidate differences between environmental and host intrinsic effects on skin microbiomes (Shibagaki et al. , 2017) Conducting in-depth analyses focusing on the specific action of probiotics such as PMC48 will provide a more detailed understanding of the mechanism by which these probiotics are able to degrade melanin pigments, as a way to engineer the development of more efficient probiotic strains, or identify other potential probiotic drug candidates for hyperpigmented skin (Park et al. , 2024) Similar research assessing the efficacy of MAST technology can be used for the treatment of other microbiome-associated disorders in patients with acne ( Cutibacterium acnes  phylotypes) and atopic dermatitis ( Staphylococcus aureus ) for a similar non-invasive, skin microbiome-friendly therapeutic approach (Bhardwaj et al. , 2024) Conclusion Research into the role of the skin microbiome in hyperpigmentation is still in its early stages, but emerging evidence highlights a promising link between microbial composition, skin physiology, and pigmentation outcomes. Recent studies exploring probiotic strains, such as Pediococcus acidilactici MC48 and microbiome-friendly chemical peels like MAST, demonstrate the therapeutic potential of modulating the skin microbiome to reduce hyperpigmentation safely and effectively. Meanwhile, observational studies have revealed distinct microbial patterns associated with different pigmentation levels, pointing to new avenues for diagnostics and targeted interventions. While current limitations, including a lack of longitudinal studies and population diversity, must be addressed, this growing body of research paves the way for more inclusive, microbiome-informed treatments that support both skin health and pigmentation balance. References Bhardwaj, V. et al.  (2024) ‘A novel professional-use synergistic peel technology to reduce visible hyperpigmentation on face: Clinical evidence and mechanistic understanding by computational biology and optical biopsy’, Experimental Dermatology , 33(4), p. e15069. Available at:   https://doi.org/10.1111/exd.15069 . Definition of hyperpigmentation - NCI Dictionary of Cancer Terms - NCI  (2011). Available at:   https://www.cancer.gov/publications/dictionaries/cancer-terms/def/hyperpigmentation  (Accessed: 24 July 2025). Dimitriu, P.A. et al.  (2019) ‘New Insights into the Intrinsic and Extrinsic Factors That Shape the Human Skin Microbiome’, mBio , 10(4), p. 10.1128/mbio.00839-19. Available at:   https://doi.org/10.1128/mbio.00839-19 . Foundation, B.S. (no date) Melasma – British Skin Foundation . Available at:   https://knowyourskin.britishskinfoundation.org.uk/condition/melasma/  (Accessed: 24 July 2025). Lawrence, E., Syed, H.A. and Al Aboud, K.M. (2025) ‘Postinflammatory Hyperpigmentation’, in StatPearls . Treasure Island (FL): StatPearls Publishing. Available at:   http://www.ncbi.nlm.nih.gov/books/NBK559150/  (Accessed: 24 July 2025). Li, Z. et al.  (2020) ‘New Insights Into the Skin Microbial Communities and Skin Aging’, Frontiers in Microbiology , 11. Available at:   https://doi.org/10.3389/fmicb.2020.565549 . Lunjani, N. et al.  (2021) ‘Mechanisms of microbe-immune system dialogue within the skin’, Genes & Immunity , 22(5), pp. 276–288. Available at:   https://doi.org/10.1038/s41435-021-00133-9 . Meisel, J.S. et al.  (2018) ‘Commensal microbiota modulate gene expression in the skin’, Microbiome , 6(1), p. 20. Available at:   https://doi.org/10.1186/s40168-018-0404-9 . Park, H.-A. et al.  (2024) ‘Clinical effect of Pediococcus acidilactici PMC48 on hyperpigmented skin’, Journal of Cosmetic Dermatology , 23(1), pp. 215–226. Available at:   https://doi.org/10.1111/jocd.15891 . Plensdorf, S., Livieratos, M. and Dada, N. (2017) ‘Pigmentation Disorders: Diagnosis and Management’, American Family Physician , 96(12), pp. 797–804. Shibagaki, N. et al.  (2017) ‘Aging-related changes in the diversity of women’s skin microbiomes associated with oral bacteria’, Scientific Reports , 7(1), p. 10567. Available at:   https://doi.org/10.1038/s41598-017-10834-9 . Zanchetta, C. et al.  (2022) ‘Bacterial taxa predictive of hyperpigmented skins’, Health Science Reports , 5(3), p. e609. Available at:   https://doi.org/10.1002/hsr2.609 .

Acne vulgaris is a prevalent condition impacting seborrheic (oily) areas of the body such as the face, chest, and back. Its onset has been linked to a myriad of factors from excess sebum production, follicular hyperkeratinization (i.e., abnormally rapid production and shedding of skin cells causing blockage of sebaceous hair follicles), and host inflammatory responses (Niedźwiedzka et al. , 2024). The skin resident bacterium Cutibacterium acnes  (formerly known as Propionibacterium acnes ) is another factor of interest; its involvement in various infections of the skin has led to its discovery as an opportunistic pathogen that likely plays a role in acne pathogenesis. The pathogenicity of these particular acne-causing strains is likely related to their ability to form biofilms and produce pro-inflammatory enzymes that worsen acne symptoms, as not all C. acnes  strains produce these effects and many actively contribute to maintaining skin microbiome balance and homeostasis (Niedźwiedzka et al. , 2024). Similar disruptions to skin microbiome balance have also been noted to be caused by conventional acne treatments like oral antibiotics, benzoyl peroxide, and topical retinoids targeting C. acnes  for removal. This has produced a demand for alternative, microbiome-friendly therapeutic approaches that reduce severity of acne symptoms while maintaining and restoring microbiome balance (Niedźwiedzka et al. , 2024). This review sought to provide a comprehensive overview of the current state of research in traditional and emerging treatments to combat acne, including the potential of microbiome-targeted therapies such as probiotics and phage treatment as an alternative to conventional antibiotic-based approaches. It also explored the dynamic between different skin pathogen populations, and how they might be able to influence one another’s susceptibility to treatment (Niedźwiedzka et al.,  2024). Results Among affecting C. acnes  bacteria, use of antibiotics has also increased rates of resistance in other resident skin microbiome species such as S. epidermidis , another common group found on the skin, with one study reporting high resistance rates of S. epidermidis  acne isolates to an array of antibiotics like tetracycline (31%), doxycycline (27%), clindamycin (33%), and erythromycin (58%) (Moon et al. , 2012).  Other studies on C. acnes  biofilm formation report the ability of these microbial structures to enhance susceptibility to antibiotics for other groups of bacteria, with reduced size and restricted formation of Staphylococcus aureus  (another skin pathogen) biofilms being observed upon exposure to these bacteria. These S. aureus biofilms exhibited increased susceptibility to multiple antibiotics such as ciprofloxacin and rifampicin upon C. acnes  exposure, presenting interesting implications for the efficacy of antibiotic treatments during skin pathobiont coinfection (Abbott et al. , 2022). Some of the global effects of antibiotic use beyond treating skin may extend to influencing gut microbiome composition, with previous studies reporting significant disruptions to gut microbiome structure during antibiotic use. Sarecycline had the most minimal impact, allowing bacterial populations to recover after treatment, while minocycline depleted multiple beneficial groups such as Lactobacillus, Ruminococcaceae  and Clostridiaceae that managed to only partially recover post-treatment (Moura et al. , 2022). Similar disruptions have been linked to the onset of gastrointestinal disorders like irritable bowel disease, demonstrating the importance of considering whole body effects when administering antibiotic acne treatments. Probiotics represent an alternative emerging therapy area for the treatment of acne without antibiotics. Topical probiotic formulations consisting of beneficial bacterial species such as Lactobacillus and Bifidobacterium are capable of increasing skin ceramide production, reducing inflammation, and improving skin barrier function against pathogens to improve acne symptoms and promote microbiome health and skin immunity. They have also demonstrated significant efficacy in reducing the growth of acne-associated bacteria like C. acnes , showing potential as a treatment for symptoms of acne. Topical probiotic formulations like SkinDuo™ containing the strain Lactiplantibacillus plantarum  LP01 have shown significant efficacy in reducing the growth of acne associated bacteria like C. acnes  and S. epidermidis , as well as a reduction in the production of inflammatory markers such as IL-1α, IL-6, and IL-8 that worsen the appearance of acne lesions, as well as significantly reducing lipid production (Podrini et al.,  2023). Oral probiotics containing Lacticaseibacillus rhamnosus  and Arthrospira platensis  were capable of reducing the number of lesions on the skin of patients in one clinical trial, with a greater proportion of patients receiving probiotic treatment demonstrating a reduction in both total and non-inflammatory acne lesions compared to the placebo group. The probiotic treatment also reduced the overall severity of acne in patients (Eguren et al., 2024).  Phage therapy is another emergent treatment that seeks to reduce the severity of acne by harnessing the power of viruses known as bacteriophages (or, phages) that specifically infect bacterial cells. This makes them an ideal candidate for acne therapy, as they offer the option of targeting only acne-associated pathogenic C. acnes  strains without disrupting the overall balance of the skin microbiome, unlike many broad-spectrum antibiotics that indiscriminately target both harmful and beneficial bacteria. A recent preclinical study investigating the effectiveness of this treatment found that topical application of C. acnes -targeting phages resulted in a marked reduction of bacterial load and inflammation in C. acnes -induced acne-like lesions (Rimon et al. , 2023), demonstrating the potential for this type of phage therapy to act as either adjunct or alternative to existing antibiotic approaches combating symptoms of acne (Niedźwiedzka et al.,  2024). Table summarising the effects of various acne treatments on the skin microbiome Future Directions Another bioactive approach that is currently emerging as a potential therapy for acne treatment is the use of prebiotic compounds that selectively promote the growth of certain beneficial strains or species of bacteria on the skin by providing key nutrients. Current prebiotics of interest include fructooligosaccharides (FOS) and galactooligosaccharides (GOS) (Niedźwiedzka et al.,  2024). Synbiotics (the combination of probiotics and prebiotics) also present an emerging area of research. These work by boosting the activity of beneficial microbes while providing essential nutrients for their growth, indicating a potential synergistic approach to managing acne symptoms (Niedźwiedzka et al.,  2024). Therapeutic formulations containing beneficial CRISPR-possessing bacteria may be used to restore balance to the skin microbiome by competing with pathogenic strains of C. acnes  to reduce their abundance, as well as inhibiting any bacteriophage-induced inflammation on the skin that could worsen acne symptoms or further disbalance the skin microbial community (Maguire and McGee, 2024). Conclusion Beyond traditional antibiotic treatments combating acne, several emergent bioactive approaches are currently being developed with promising results for reducing both the severity of acne, as well as targeting the dysbiotic mechanisms potentially underlying its pathogenesis. These offer more personalised and sustainable solutions for both acne therapy, and also the growing concern of antibiotic resistance within skin-associated microbiomes (Niedźwiedzka et al.,  2024). More research is still needed to better understand the influence and interactions of different microbial communities beyond bacteria on the skin such as fungi and viruses, and how this might impact upon traditional and alternative acne therapies in the long term as a way to facilitate the development of more effective microbiome-based treatments for acne (Niedźwiedzka et al. , 2024). Continued research into clinical trials for probiotics and phage therapies will also be necessary to help determine the most effective formulations, dosages, and methods of application for their integration into conventional acne treatment procedures (Niedźwiedzka et al. , 2024). References Abbott, C. et al.  (2022) ‘ Cutibacterium acnes  biofilm forming clinical isolates modify the formation and structure of Staphylococcus aureus  biofilms, increasing their susceptibility to antibiotics’, Anaerobe , 76, p. 102580. Available at:   https://doi.org/10.1016/j.anaerobe.2022.102580 . Eguren, C., Navarro-Blasco, A., Corral-Forteza, M., Reolid-Pérez, A., Setó-Torrent, N., García-Navarro, A., Prieto-Merino, D., Núñez-Delegido, E., Sánchez-Pellicer, P. and Navarro-López, V. (2024). A Randomized Clinical Trial to Evaluate the Efficacy of an Oral Probiotic in Acne Vulgaris. Acta Dermato-Venereologica, [online] 104, pp.adv33206–adv33206. doi: https://doi.org/10.2340/actadv.v104.33206 . Maguire, G. and McGee, S.T. (2024). NeoGenesis MB-1 with CRISPR Technology Reduces the Effects of the Viruses (Phages) Associated with Acne - Case Report. Integrative medicine (Encinitas, Calif.), [online] 23(4), pp.34–38. Available at: https://pubmed.ncbi.nlm.nih.gov/39355416/ . Moon, S.H. et al.  (2012) ‘Antibiotic resistance of microbial strains isolated from Korean acne patients’, The Journal of Dermatology , 39(10), pp. 833–837. Available at:   https://doi.org/10.1111/j.1346-8138.2012.01626.x . Moura, I.B. et al.  (2022) ‘Profiling the Effects of Systemic Antibiotics for Acne, Including the Narrow-Spectrum Antibiotic Sarecycline, on the Human Gut Microbiota’, Frontiers in Microbiology , 13. Available at:   https://doi.org/10.3389/fmicb.2022.901911 . Niedźwiedzka, A. et al.  (2024) ‘The Role of the Skin Microbiome in Acne: Challenges and Future Therapeutic Opportunities’, International Journal of Molecular Sciences , 25(21), p. 11422. Available at:   https://doi.org/10.3390/ijms252111422 . Podrini, C., Schramm, L., Marianantoni, G., Apolinarska, J., McGuckin, C., Forraz, N., Milet, C., Desroches, A.-L., Payen, P., D’Aguanno, M. and Biazzo, M. (2023). Topical Administration of Lactiplantibacillus plantarum (SkinDuoTM) Serum Improves Anti-Acne Properties. Microorganisms, [online] 11(2), p.417. doi: https://doi.org/10.3390/microorganisms11020417 . Rimon, A. et al.  (2023) ‘Topical phage therapy in a mouse model of Cutibacterium acnes-induced acne-like lesions’, Nature Communications , 14(1), p. 1005. Available at:   https://doi.org/10.1038/s41467-023-36694-8 .