IL-17A Inhibitors Linked with Scalp and Gut Microbiota Improvement in Psoriasis Patients

Key Takeaways

• IL-17A inhibitors led to clinical improvement and changes in scalp and gut microbiota among patients with moderate-to-severe psoriasis in a new prospective study.

• Scalp microbiota showed reduced levels of Pseudomonas and increased Bifidobacterium following treatment, according to researchers.

• Gut microbiota diversity improved, with enrichment of SCFA-producing genera and shifts in microbial metabolic pathways.

Treatment with IL-17A inhibitors may help rebalance disrupted scalp and gut microbiota in patients with moderate-to-severe psoriasis vulgaris, according to a new study. 

Researchers collected scalp and fecal samples from 15 adults with psoriasis (PsO) before treatment, and again at 4 and 12 weeks following subcutaneous therapy with secukinumab or ixekizumab. Samples were compared to those from 10 age- and sex-matched healthy controls. High-throughput 16S rRNA gene sequencing was used to analyze microbial diversity and structure.

IL-17A inhibition led to clinically significant reductions in Psoriasis Area and Severity Index (PASI) scores, with all patients achieving at least partial remission by week 12. Microbiome analyses revealed that while Scalp microbial alpha and beta diversity did not differ significantly from controls post-treatment, although increases in beneficial Bifidobacterium and decreases in the pathogenic species were reported. Gut microbiota showed reduced species richness at baseline, which improved following treatment. 

“IL-17A inhibitor therapy has the potential to improve the structure and diversity of the scalp microbiome, gradually restoring it toward a healthier state while also enhancing gut microbiota diversity,” the authors wrote. “These therapeutic effects may be mediated through immune regulation, such as the Th17 pathway modulation, and microbial metabolites like short-chain fatty acids.”

They added: "These findings underscore the importance of further exploration into the interaction between microbial homeostasis and immune regulation. A deeper understanding of this relationship could clarify the key role of the microbiota in psoriasis pathogenesis as well as identify novel biological targets for innovative therapeutic strategies."

Source: Huwang W, et al. Frontiers in Infection and Microbiology. 2025. doi:doi.org/10.3389/fcimb.2025.1623003