Psoriatic patients have a distinct structural and functional fecal microbiota compared with controls.

Alterations in the gut microbiome have been implicated in the pathogenesis of several immune-mediated inflammatory diseases such as psoriatic arthritis. This work aimed to characterize the gut microbial signature of patients with active psoriasis as compared with age-, body mass index- and comorbidity-matched non-psoriatic controls and to correlate them with differential expression of metabolic pathways. Fecal samples were processed and 16S rRNA was sequenced. PICRUSt was used to perform an analysis of metabolic pathways. Of the 46 participants, 52% (n = 24) suffered from psoriasis. There was a significant difference in β-diversity between the two groups. Psoriatic patients had a significant increase in the Firmicutes and Actinobacteria phyla as compared with matched controls. At the genus level, psoriatic patients had a unique bacterial composition. At the species level, the psoriatic patients showed significant increases in the relative proportions of (false discovery rate, <0.05) in Ruminoccocus gnavus, Dorea formicigenerans and Collinsella aerofaciens, while Prevotella copri and Parabacteroides distasonis were significantly decreased as compared with controls. PICRUSt analysis revealed increases in metabolic pathways related to lipopolysaccharide function in the psoriatic cohort. These data demonstrate unique fecal microbial and metabolic signatures in psoriatic patients.