Zhaoying Han

BACKGROUND: The human skin microbiome and lipidome are essential for skin homeostasis and barrier function, and have become a focus in both dermatological and cosmetic fields. However, the influence of surfactants commonly used in cosmetic products on the skin resident microbiome and lipidome remains poorly characterized. METHODS: We conducted self-control experiments to systematically study the effects of surfactant (sodium lauroyl sarcosinate [SLS]) on facial skin. Wrinkles, pores, porphyrins, and superficial lipids were examined to evaluate the biophysical state of skin. Quantitative real-time PCR was used to detect the numbers of bacteria and fungi. The diversity and structure of prokaryotic and eukaryotic microbiomes were assessed using 16S rDNA and ITS amplicon sequencing, respectively. Moreover, 22 lipids were identified to evaluate lipidome variations. SPSS software was used for statistical analysis. RESULTS: SLS in facial cleanser did not extensively influence skin biophysical parameters, but caused a decrease in porphyrin. After using the SLS-added facial cleanser for 3 weeks, the alpha diversity of the prokaryotic microbial community decreased significantly, while the eukaryotic microbial community showed a continuous downward trend but no statistically significant. A shift in the structure of prokaryotic microbiome was observed as a result of SLS exposure, mainly reflected by the increase in Acinetobacter, Escherichia-Shigella, Streptococcus, and Ralstonia, while the SLS had little effect on the structure of the eukaryotic microbiome. Furthermore, SLS exposure had a great impact on skin lipidome, mainly manifested by the increase of phosphatidylglycerol (PG) and phosphatidylcholine (PC), and the decrease of ceramides. Spearman's correlations analysis showed that Escherichia-Shigella, Pseudomonas, and Acinetobacter are positively correlated with PG and PC; however, the correlation is not statistically significant. CONCLUSION: In this study, we found the SLS in facial cleanser primarily affected lipidome and the prokaryotic microbiome of facial skin. These findings are useful for reminding us to be vigilant about the ingredients in personal care products, even the common ingredients, and designing effective formulations for repairing ecological balance of skin.

Hair loss is a complex multifactorial process. The mechanisms by which caffeine and adenosine act against hair loss have been extensively researched, but little is known about their effects on the microbiome and lipidome of the scalp. Hair loss may be associated with the status of scalp microbiota and lipids. Further investigation is warranted to determine whether caffeine and adenosine can regulate scalp microbiota and lipids and thus help to prevent hair loss. The objective of this study was to assess the effect of shampoo containing caffeine and adenosine on the scalp microbiome and lipidome in subjects experiencing hair loss who were aged between 18 and 60 years. The study was a randomized, single-blind and parallel comparison trial involving full scalp treatment, which was conducted among 30 subjects experiencing hair loss. Samples were collected from subjects at baseline and at 12 weeks (±3 days). Microbiomes were analysed via 16S rDNA and ITS1 sequencing. Lipidome analysis was carried out using ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). At 12 weeks, significant clinical characteristics indicating an anti-hair loss effect were evident. Abundances of Pseudomonas, Escherichia-Shigella and Malassezia all decreased in the experimental group, whereas those of Talaromyces and Cutibacterium increased. In addition, levels of triglyceride (TG), diglyceride (DG), ceramide (Cer) and ceramide-1-phosphate (CerP) were all significantly impacted in the experimental group. Furthermore, abundances of lipid metabolites were tightly correlated with those of Escherichia-Shigella and Talaromyces. Caffeine and adenosine may enhance the anti-hair loss process through their effects on the lipidome and microbiome of the scalp.

Acne vulgaris is a prevalent chronic inflammatory dermatosis primarily affecting the pilosebaceous units. Current therapeutic approaches often exhibit limited efficacy and high recurrence rates. To investigate the microbiome-related mechanisms of acne vulgaris, facial skin samples from 19 patients with moderate acne and 20 healthy individuals were analyzed using an integrated metagenomic and lipidomic profiling strategy. Metagenomic analysis revealed a significant reduction in microbial diversity (Chao index) in acne-affected skin compared to healthy controls (p < 0.001). The relative abundance of Staphylococcus, particularly Staphylococcus epidermidis, was significantly elevated in acne group (p < 0.05), while Cutibacterium acnes levels remained unchanged. Carbon metabolism pathways were enriched in the acne group (p < 0.05), predominantly driven by Cutibacterium, whereas other enriched metabolic pathways, such as ABC transporters and glycine, serine, and threonine metabolism (p < 0.05), showed a greater contribution from Staphylococcus. Virulence factors enriched in acne samples were primarily offensive in nature and largely attributed to Staphylococcus. Moreover, acne-associated microbiome exhibited a significantly higher prevalence of resistance genes against fluoroquinolones, fosfomycin, and triclosan (p < 0.05). Untargeted lipidomic analysis demonstrated significantly elevated total serum and triglyceride levels, along with a reduction in fatty acid chain length and a higher degree of saturation compared to the healthy group (p < 0.01). Specific triglycerides significantly enriched in the acne group, such as TG (15:0_14:0_16:0) + NH4, exhibited a significant positive correlation with Staphylococcus. This correlation is associated with elevated clinical erythema and melanin indices, suggesting that Staphylococcus is implicated in the development of acne-related inflammation. Additionally, Thermus exhibits negative correlations with acne-associated lipids and inflammatory parameters, potentially exerting a protective role. These findings suggest that Cutibacterium and Staphylococcus play differential yet synergistic roles in acne pathogenesis. The observed skin microbiome dysbiosis and lipid metabolic alterations provide novel insights into the pathophysiology of acne vulgaris, which may inform the development of targeted therapeutic strategies.

The skin serves as a vital barrier, largely influenced by the commensal microbiota. Lawsonella clevelandensis, the currently recognized sole species in the genus Lawsonella, has gained increased attention as a cause of abscesses but is often overlooked due to its fastidious nature, which make its isolation and culture in the lab particularly challenging. Here, a comprehensive genomic investigation of Lawsonella was conducted using a cultivation-free metagenomic approach, focusing on 39 newly generated and 12 publicly available genomes. A novel species represented by 43 metagenome-assembled genomes (MAGs) was proposed based on mono-clade formation, 16S rDNA sequence similarity and genome-wide average nucleotide identity (ANI) values. All these MAGs were initially identified as L. clevelandensis A by GTDB-tk. Here, we designed them as 'Candidatus Lawsonella tjsk' sp. nov.. Distinct genomic characteristics between this newly proposed species and L. clevelandensis were observed. Significant fundamental functional differences between the two species were revealed by species-specific genes.