Plain language summary
Psoriasis is a common inflammatory skin disease that results in patches of dry, scaly skin that can be itchy or sore. Psoriatic arthritis is an inflammatory arthritis that affects up to 30% of psoriasis patients. The role of skin bacteria (the skin microbiome) is not well understood. This systematic review summarised the literature on the microbiome in psoriatic disease. The researchers looked at nine studies: seven on psoriasis only, and two studies comparing the microbiome characteristics between psoriasis and psoriatic arthritis. Compared to healthy controls, the skin of psoriasis patients demonstrated a decreased species diversity, higher relative abundances of Firmicutes, and lower relative abundances of Actinobacteria. Less conclusive were genus-level results, which demonstrated trends towards increased Streptococcus, Staphylococcus, and Corynebacterium, and decreased Propionibacterium in the skin of psoriasis patients versus healthy controls. However, the studies’ designs and methodologies varied, and therefore the researchers concluded that further research into the role of the skin microbiome in psoriatic disease is needed.
Abstract
BACKGROUND Psoriasis affects 1-3% of the Canadian population. Psoriatic arthritis (PsA), the most common comorbidity of psoriasis, affects up to 30% of psoriasis patients. The skin microbiome is hypothesized to play a role in the pathogenesis of psoriatic disease (PsD-psoriasis and PsA). OBJECTIVE To summarize the current state of literature on the skin microbiome in PsD. METHODS A systematic review was performed using searches in Ovid, Medline, Embase, Medline Epub Ahead of Print and In-Process & Other Non-Indexed Citations, and Cochrane Central Register of Controlled Trials (CENTRAL). Search was limited to humans and English language, with no limits for date or publication type. RESULTS Of 4,032 citations identified, 9 studies met inclusion criteria (7 on psoriasis only and 2 studies compared the microbiome characteristics between psoriasis and PsA). Compared to healthy controls, lesions demonstrated a decreased alpha diversity, higher relative abundances of Firmicutes, and lower relative abundances of Actinobacteria. Less conclusive were genus-level results, which nonetheless demonstrated trends towards increased Streptococcus, Staphylococcus, and Corynebacterium and decreased Propionibacterium in lesions vs. control. LIMITATIONS Study designs were heterogeneous, including sampling technique and exclusion criteria. CONCLUSIONS Phyla- and selected genus-level characteristic of the psoriatic microbiome are presented; further research is warranted.
Methodological quality
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