Gut microbiota in alopecia areata.

Introduction: In the past few years, the advancement of 16S rRNA metagenomic analysis sequencing has enabled assessing the impact of gut microbiota on the development of skin disease. Alopecia areata (AA) is a nonscarring hair loss disorder with an unknown etiopathogenesis, however, it is hypothesised that a combination of genetic and environmental factors might be involved. Although numerous studies have shown that the microbiome plays a key role at the beginning of skin diseases, the link between AA and gut dysbiosis remains unclear. Aim: To analyse the intestinal microbiome in patients suffering from AA. Material and methods: The study describes the conceivable involvement of gut microbiota in the unclear pathogenesis of AA. We enrolled 25 patients, over 18 years of age with an active state of AA who donated their stool samples. The samples were examined at the human gut microbial community at the species level by metataxonomic analysis of the full-length 16S V3-V4 sequencing. Results: The four major genera that constitute the microbiome's core are Lachnoclostridium, Bifidobacterium, Streptococcus, and Eubacterium, as well as three major phyla: Firmicutes, Proteobacteria, and Actinobacteria. Firmicutes and Proteobacteria are overrepresented in the microflora, which might suggest a disturbed microflora. Furthermore, the composition of bacterial communities suggests a loss of overall richness and a decrease in taxonomic diversity across all samples. Conclusions: This study describes, for the first time, the characteristics of the gut microbiome in AA patients and may provide new insight into the gut microbiome that may play a role in the development of AA.