Psoriasis may be influenced by the gut microbiota due to its impact on the regulation of systemic immunity and phototherapy may modify the skin microbiota through its antimicrobial activity. The aims were:to relate intestinal and cutaneous bacterial and fungal abundance in patients with psoriasis,and to determine the impact of UVB-NB.
M&M:Patients with psoriasis provided faecal samples and samples of healthy and affected skin collected with a swab before and after treatment with phototherapy. Bacterial and fungal composition was determined by mass sequencing on the MiSeq platform (Illumina). Taxonomic assignment was performed with the databases Silva 138 and UNITE. In addition,colourimetry, blood pressure,quality of life and psoriasis severity scales and analyses with IL-6,lipid profile,vitamin B12 and folic acid, were performed before and after phototherapy.
RESULTS:8 patients were included, mean age of 48.8[30-60],5 women and 3 men, 75% with phototype 3 and 25% with phototype 2. Statistically significant differences were found in PASI,BSA and IGA scales(p=0.01).In colourimetry, there was a significant increase in erythema.There was a statistically significant reduction in IL6 levels.A positive correlation was detected between increased erythema and improved PASI(0.762, p=0.02).Alpha diversity values were significantly higher in healthy skin, with a marked reduction in the number of species in affected skin. No relevant results were observed in faeces. In healthy skin,Malasseziaceae,Cladosporiaceae and Herpotrichiellaceae were the most abundant fungal families, whereas taxa with no clear taxonomic assignment were predominant in affected skin. In terms of bacteria, the beta diversity of psoriasis-affected skin after phototherapy was very similar to that of healthy skin before phototherapy.
CONCLUSION:Swab sampling is valid for studying microbiota by mass sequencing.Many of the fungal readings in psoriasis-affected skin could not be taxonomically assigned,indicating the presence of fungal species that have not yet been included in databases.Treatment with phototherapy has an antimicrobial impact on both affected and healthy skin.