Ultraviolet radiation, both UVA and UVB, influences the composition of the skin microbiome

Inhabiting each square centimeter of skin are approximately 1 million bacteria from hundreds of distinct species. Recent studies have begun to investigate the complex relationship between host and microorganisms leading to non-infectious pathologies such as acne, atopic dermatitis, and psoriasis. Though the skin is continuously exposed to external environmental stressors such as ultraviolet (UV) radiation, there have been no studies examining the effects of UV on the skin microbiome. To test our hypothesis that UV will alter the cutaneous microbiome, 22 participants were exposed to various doses of UVA (22-47 J/cm2) or UVB (100-350 mJ/cm2) and skin was swabbed before, immediately after, and 24h after UV exposure. DNA was isolated from the swabs and sequenced to identify the microbial composition for each sample. There was vast intra- and inter-subject variation in the skin microbiome at all time points, and phylum- and species-level differences were identified. Specifically, within the Proteobacteria phyla, an increase of the order Burkholderiales was observed after UV compared to pre-UV (59% vs 24%, p=0.0172). There was no clear difference in microbial composition between UVA- and UVB-irradiated skin; however, the sensitivity of various microbes to UV as well as their re-colonization potential following exposure differed. Taken together, the results demonstrate that UV radiation, both UVA and UVB, has profound qualitative and quantitative influences on the composition of the skin microbiome, which may affect skin diseases in which UV radiation is a factor, and may contribute to the efficacy of phototherapy and photochemotherapy

Ultraviolet radiation, both UVA and UVB, influences the composition of the skin microbiome

BACKGROUND: Studies have begun to investigate the complex relationship between host and microorganisms in non-infectious pathologies such as acne, atopic dermatitis and psoriasis. Though the skin is exposed to environmental stressors such as ultraviolet radiation (UVR), no studies exist examining the effects of both UVA and UVB on the skin microbiome. OBJECTIVE: To test the effect of UVA and UVB on human skin microbiome. METHODS: To test whether UV will alter the cutaneous microbiome, participants were exposed to doses of UVA (22-47 J/cm(2) ) or UVB (100-350 mJ/cm(2) ) and samples were collected. DNA was isolated and sequenced to identify the microbial composition of each sample. RESULTS: There was vast intra- and inter-subject variation at all time points, and phylum and species-level differences were identified. These included an increase in the phylum Cyanobacteria and a decrease in the family Lactobacillaceae and Pseudomonadaceae. The sensitivity of microbes to UVR and their re-colonization potential following exposure differed in UVA vs UVB samples. LIMITATIONS: The sample size was small, and the study was limited to males. CONCLUSION: The results demonstrate that UVR has profound qualitative and quantitative influences on the composition of the skin microbiome, possibly effecting skin pathology in which UVR is a factor