Growing body of evidence suggests a functional interplay between gut microbiome, intestinal barrier and immune system. That so-called „gut-skin axis” has been considered as a key factor in the etiology of psoriasis. The aim of this study was to compare psoriasis severity, intensity of self-reported gastrointestinal symptoms and concentration of gut microbiota-derived metabolites (trimethylamine N-oxide; TMAO and indoxyl sulfate) between psoriatic patients with and without altered intestinal barrier. One hundred twenty consecutive patients with chronic plaque psoriasis were enrolled. To examine gut barrier integrity we investigated serum concentrations of claudin-3, a modulator of intestinal tight junctions and intestinal fatty acid-binding protein, a marker of enterocyte damage. Gastrointestinal symptoms were evaluated with a validated questionnaire – Gastrointestinal Symptom Rating Scale (GSRS). Concentration of TMAO and indoxyl sulfate was measured through high performance liquid chromatography. Patients with altered gut barrier showed significantly higher score in GSRS (3.09 vs 1.23; p<0.05), especially in “indigestion” section. Moreover, patients with psoriasis and disrupted intestinal barrier demonstrated higher disease activity (PASI: 18.9±1.9 vs 10.1±2.5, p<0.05). The inflammatory parameters and markers of bacterial translocation were significantly higher in a subgroup of patients with damaged gut integrity (TMAO: 375.7±51.9 vs 119.4±27.5 ng/mL; indoxyl sulfate: 1016.4±85.3 vs 654.2±69.1 ng/mL). Our results support the hypothesis that alterations of the intestinal barrier may play an essential role in the pathogenesis of psoriasis. Further study should focus on developing therapies that enhance intestinal barrier function.

Altered intestinal barrier in psoriasis is associated with disease severity, gastrointestinal symptoms and presence of bacteria metabolites in the blood.