Crohn's disease (CD) and ulcerative colitis (UC) are two forms of inflammatory bowel disease (IBD), where the role of gut but not skin dysbiosis is well recognized. Inhibitors of TNF have been successful in IBD treatment, but up to a quarter of patients suffer from unpredictable skin adverse events (SkAE). For this purpose, we analyzed temporal dynamics of skin microbiota and serum markers of inflammation and epithelial barrier integrity during anti-TNF therapy and SkAE manifestation in IBD patients. We observed that the skin microbiota signature of IBD patients differs markedly from healthy subjects. In particular, the skin microbiota of CD patients differs significantly from that of UC patients and healthy subjects, mainly in the retroauricular crease. In addition, we showed that anti-TNF-related SkAE are associated with specific shifts in skin microbiota profile and with a decrease in serum levels of L-FABP and I-FABP in IBD patients. For the first time, we showed that shifts in microbial composition in IBD patients are not limited to the gut and that skin microbiota and serum markers of the epithelium barrier may be suitable markers of SkAE during anti-TNF therapy.

Department of Dermatovenerology 2nd Faculty of Medicine Charles University University Hospital Bulovka Prague Czechia

Department of Gastroenterology and Hepatology Institute of Clinical and Experimental Medicine Prague Czechia

Department of Zoology Faculty of Science Charles University Prague Czechia

IBD Clinical and Research Centre ISCARE a s Prague Czechia

Institute of Medical Biochemistry and Laboratory Diagnostics General University Hospital and 1st Faculty of Medicine Charles University Prague Czechia

Institute of Microbiology of the Czech Academy of Sciences Prague Czechia

Prof Hercogova Dermatology Prague Czechia

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Paradoxical Reactions to Anti-TNFα and Anti-IL-17 Treatment in Psoriasis Patients: Are Skin and/or Gut Microbiota Involved?