Gut microbiota analysis in systemic sclerosis according to disease characteristics and nutritional status

Objective. Systemic sclerosis (SSc) is a rare multi-organ disorder with a prominent gastrointestinal (GI) involvement. Altered gut microbiota is now considered a pivotal factor associated with the development of immune-mediated and inflammatory diseases. We performed a 16S ribosomal RNA (rRNA) gene-sequencing analysis of fecal microbiota in a cohort of SSc patients and matched healthy controls (HCs), with the aim to obtain some hints about a possible role of dysbiosis in the onset, progression, and severity of the disease. Methods. We analysed stool samples from 63 SSc patients with different disease duration, phenotype, and nutritional status and from 17 HCs through 16S ribosomal RNA (rRNA) gene-sequencing. Results. Microbial richness was lower for patients with long-standing disease. A similar observation was made for patients with diffuse cutaneous SSc (dsSSc) compared to those with limited variant (lcSSc) and for patients who reported a recent weight loss. Consistent with previous reports, we noted a deviation of the intestinal microbial composition in patients with SSc compared to HCs, with a greater expression of Lactobacillus and Streptococcus and a depletion of Sutterella. Nutritional status, assessed using BMI as a surrogate, appeared to have a marked impact on the gut microbiota, with overweight patients showing lower richness compared both to underweight and normal-BMI patients. Conclusion. Our findings expand the current knowledge of gut microbiota in SSc and could be useful to identify patients who would most benefit from treatments aimed at restoring the eubiosis.