Depletion of Saccharomyces cerevisiae in psoriasis patients, restored by Dimethylfumarate therapy (DMF)

BACKGROUND Psoriasis and inflammatory bowel disease (IBD) are chronic inflammatory diseases sharing similar pathogenic pathways. Intestinal microbial changes such as a decrease of bakers' yeast Saccharomyces cerevisiae have been reported in IBD, suggesting the presence of a gut-skin axis. OBJECTIVE To investigate whether the S. cerevisiae abundance was altered in psoriasis patients versus healthy controls, and whether dimethylfumarate (DMF) interacted with this yeast. METHODS Using qPCR, faecal samples were compared between psoriasis patients without DMF (n = 30), psoriasis patients with DMF (n = 28), and healthy controls (n = 32). RESULTS Faecal S. cerevisiae abundance was decreased in psoriasis compared to healthy controls (p<0.001). Interestingly, DMF use raised S. cerevisiae levels (p<0.001). Gastrointestinal adverse-effects of DMF were correlated with a higher S. cerevisiae abundance (p = 0.010). In vitro, a direct effect of DMF on S. cerevisiae growth was observed. In addition, anti-Saccharomyces cerevisiae antibodies were not elevated in psoriasis. CONCLUSION The abundance of baker's yeast S. cerevisiae is decreased in psoriasis patients, but appears to be restored upon DMF use. S. cerevisiae is generally classified as a yeast with beneficial immunomodulatory properties, but may also be involved in the occurrence of DMF's gastrointestinal adverse-effects. Potentially, DMF might be a new therapy for IBD.