The gut microbiota plays a critical role in immune system function, with dysbiosis linked to systemic inflammation, contributing to conditions like psoriasis and depression. Although biological treatments for severe psoriasis are known to impact gut bacteria, less is understood about their effects on fungi. This study aims to investigate fungal gut microbiota changes in psoriasis patients transitioning from TNF-α inhibitors to brodalumab. Fecal samples from 20 patients were analyzed using Illumina MiSeq sequencing of the ITS2 region of 18S rRNA. Microbial diversity was assessed through Bray–Curtis dissimilarity and the Shannon–Wiener index. Clinical outcomes were measured using clinical scores for psoriasis and depression severity, with statistical analysis performed via Wilcoxon signed-rank tests and PERMANOVA. Results showed that Ascomycota was the dominant fungal phylum in both treatment groups, with Saccharomyces, Penicillium, Candida, and Debaryomyces as prevalent genera. No significant changes occurred at the phylum level after switching to brodalumab, though minor genome-level variations were observed. Beta diversity analysis highlighted inter-patient variability, with no significant correlation between fungal composition and clinical outcomes. Despite improved clinical scores, the fungal gut microbiota remained largely stable, suggesting that brodalumab does not significantly alter fungal communities in psoriasis patients. Further research is needed for a comprehensive understanding.

Psoriasis is a chronic, immune-mediated inflammatory skin disorder that significantly impacts patients’ quality of life. While TNF-α inhibitors are frequently used to treat moderate-to-severe cases, not all patients respond adequately. Brodalumab, a monoclonal antibody targeting the IL-17 receptor A, has emerged as an alternative for individuals unresponsive to prior therapies. This prospective study investigated the effects of brodalumab on serum cytokine levels—specifically IL-6, IL-17A, IFN-α, IFN-γ, and TNF-α—and their correlation with disease severity as assessed by Psoriasis Area and Severity Index (PASI). Eighteen patients with moderate-to-severe psoriasis who were unresponsive to TNF-α inhibitors received brodalumab for 12 weeks. Cytokine concentrations were measured at baseline and week 12 using an automated immunoassay (ELLA), and clinical outcomes were evaluated using PASI. The results showed a significant increase in IL-17A levels, while changes in IL-6, IFN-α, IFN-γ, and TNF-α did not reach statistical significance. No significant correlations were found between changes in cytokine levels and PASI improvement. However, the small number of available serum samples at week 12 (n = 11) limited the statistical power to detect treatment-related changes in cytokine levels. These findings suggest that while brodalumab influences specific immune markers, the clinical response may not be directly reflected by serum cytokine levels. This highlights the multifactorial nature of psoriasis pathogenesis and underscores the need for further studies to clarify the role of cytokine biomarkers in treatment response.

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.