Abstract
Biological agents used to treat severe psoriasis may alter the gut microbiota, though current knowledge is limited. This study examines whether switching from TNFα inhibitors, from which patients had reduced or lost effect, to brodalumab, an IL-17 inhibitor, affects the gut microbiota in patients with psoriasis and how these changes correlate with the clinical variables of psoriasis severity and depressive symptoms. Fecal samples from patients were collected before the treatment switch and 12 weeks after the switch and were analyzed for the microbiota composition using next-generation sequencing targeting the V3-V5 region of the 16S rRNA gene, followed by bioinformatics analysis. No significant changes in overall gut microbiota composition were observed after the treatment switch, although individual variations in the Firmicutes/Bacteroidetes ratio were noted, and no significant correlations with clinical variables were found. These findings suggest that short-term changes in gut microbiota in patients with psoriasis are limited and that dysbiosis may be influenced by the interplay of various microbial populations rather than specific taxa. This study provides a foundation for further research into the effects of biological treatments on the gut microbiota in patients with psoriasis.