The cutaneous and intestinal microbiome in psoriatic disease

Psoriasis (PsO) and psoriatic arthritis (PsA) are chronic immune-mediated inflammatory diseases of multifactorial etiology. In addition to genetic and environmental factors, evidence supports involvement of a dysregulated human microbiome in the pathogenesis of psoriatic disease. In particular, alterations in the composition of the microbiome, termed dysbiosis, can result in downstream proinflammatory effects in the gut, skin, and joints. Both the cutaneous and intestinal microbial populations are implicated in the pathogenesis of psoriatic disease, although exact mechanisms are unclear. Herein, we review the relationship between the human microbiome and psoriatic disease. Further insight into the functions of the microbiome may allow for greater understanding of inflammatory disease processes and identification of additional therapeutic targets. •Recent evidence supports involvement of a dysregulated microbiome in the pathogenesis of human psoriatic disease.•Alterations in both the cutaneous and intestinal microbiome have been noted in patients with psoriasis.•Although studies differ, an alteration in the intestinal Firmicutes/Bacteriodetes ratio is implicated in psoriatic arthritis.