Significant Differences in the Bacterial Microbiome of the Pharynx and Skin in Patients with Psoriasis Compared with Healthy Controls

Abstract

Studies have shown differences in the skin and gut bacterial microbiomes in patients with psoriasis, but the pharyngeal microbiome has not been studied previously. The aim of this study was to investigate differences in the bacterial microbiome of the pharynx and skin of patients with psoriasis compared with healthy controls. Swabs were taken from the pharynx and elbow skin of 39 patients with psoriasis and 70 controls. Microbiomes were characterized by sequencing 16S rRNA genes on the Illumina MiSeq platform. Significant differences were found in alpha and beta diversity in the skin, but not in the pharynx. Significant differences were also found between several phyla and genera in both skin and pharynx. The severity of psoriasis did not correlate with any genera in the pharynx, but with Capnocytophaga, Leptotrichia, Abiotrophia and Tannerella in the skin. The composition of the pharyn-geal and skin microbiome may be of importance in the patho-genesis of psoriasis.

Keywords: pharynx; psoriasis; skin; microbiome.

Fig. 1

(a) No significant difference in the alpha diversity of the pharyngeal microbiome between healthy controls and patients with psoriasis. (Line=median, box=first and third quartile, whiskers=non-outlier range). (b) Significant differences in the alpha diversity in the skin microbiome when comparing healthy controls, lesional and non-lesional skin in patients with psoriasis. (**p < 0.01, ***p < 0.001, line=median, box=first and third quartile, whiskers=nonoutlier range). (c) Principal coordinate analysis (PCoA) of beta diversity using unweighted UniFrac showing no significant differences between the pharynx of healthy controls (blue) and patients with psoriasis (red); p > 0.05). (d) PCoA of beta diversity using Unweighted UniFrac with significant differences between skin in healthy controls (blue) and lesional skin in patients with psoriasis (red) (p < 0.001), between skin in healthy controls and non-lesional skin patients with psoriasis (green) (p < 0.001), and between lesional and non-lesional skin of patients with psoriasis (p < 0.001).

Fig. 2

(a) Bar chart showing relative abundance of bacteria in the pharynx at the phylum level in patients with psoriasis and controls. (b) Significant differences in the pharynx shown for the phylum Actinobacteria (false discovery rate (FDR); **p < 0.01). (c) Bar chart showing relative abundance of bacteria in the pharynx at the genus level in patients with psoriasis and controls. (d) Significant differences in the pharynx shown for the genera Prevotella, Campylobacter, Cutibacterium, Tepidimonas, ambiguous taxa of Absconditabacteriales order, Acidovorax and Staphylococcus. (FDR; *p < 0.05, ***p < 0.001).