Gut bacterial microbiota in psoriasis: A case control study

Gut microbiota is mainly composed of four phyla; however, the human gut microbiota is dominated by only 2 of them and most of them are uncultivable. Psoriasis is an inflammatory skin disorder with associated inflammation of internal organs and musculoskeletal system. This study aimed to, identify numerically abundant bacteria phyla in fecal samples of patients with psoriasis, evaluate whether differences in fecal microbiota correlate with the occurrence of psoriasis and understand the possible pathogenesis behind psoriasis-related bacterial targets. From April, 2015 to 2016, 90 adults were selected prospectively to allocate 2 equal groups: Gr1 (45 cases) patients with psoriasis, and Gr2 (45 cases) healthy controls. Psoriasis Area and Severity Index (PASI) for each psoriasis patient was detected. All subjects were subjected to history taking, clinical examination, and fecal real time polymerase chain reaction (PCR) testing for the Firmicutes, Bacteroidetes, and Actinobacterial phyla. In both groups, Firmicutes were the most common detected phylum followed by Bacteroidetes and finally Actinobacterial phyla. High statistically significant difference was reported for the Firmicutes/ Bacteroidetes ratio between the psoriasis patients and the control group and showed statistically significant positive correlations with PASI. Actinobacterial count was significantly higher in the control group than in psoriasis patients and showed statistically significant negative correlations with PASI. It is believed that, there are fractions of the gut microbiota with the ability to counteract inflammation (Bacteroidetes and Actinobacterial), and others that are more prone to induce inflammation (Firmicutes) and the disturbed microbiome ratio may be the cause for inducing psoriasis.