Microbiota composition and mucosal immunity in patients with asymptomatic diverticulosis and controls

Abstract

Introduction The etiology of diverticulosis is still poorly understood. However, in patients with diverticulitis, markers of mucosal inflammation and microbiota alterations have been found. The aim of this study was to evaluate potential differences of the gut microbiota composition and mucosal immunity between patients with asymptomatic diverticulosis and controls. Methods We performed a prospective study on patients who underwent routine colonoscopy for causes not related to diverticular disease or inflammatory bowel disease. Participants were grouped based on the presence or absence of diverticula. Mucosal biopsies were obtained from the sigmoid and transverse colon. Microbiota composition was analyzed with IS-pro, a 16S-23S based bacterial profiling technique. To predict if patients belonged to the asymptomatic diverticulosis or control group a partial least squares discriminant analysis (PLS-DA) regression model was used. Inflammation was assessed by neutrophil and lymphocyte counts within the taken biopsies. Results Forty-three patients were enrolled. Intestinal microbiota profiles were highly similar within individuals for all phyla. Between individuals, microbiota profiles differed substantially but regardless of the presence (n = 19) of absence (n = 24) of diverticula. Microbiota diversity in both sigmoid and transverse colon was similar in all participants. We were not able to differentiate between diverticulosis patients and controls with a PLS-DA model. Mucosal lymphocyte counts were comparable among both groups; no neutrophils were detected in any of the studied biopsies. Conclusions Microbiota composition and inflammatory markers were comparable among asymptomatic diverticulosis patients and controls. This suggests that the gut microbiota and mucosal inflammation do not play a major role in the pathogenesis of diverticula formation.

Pathophysiology of Diverticular Disease: From Diverticula Formation to Symptom Generation

“…A recent study evaluated the microbiota profiling in the sigmoid and transverse colon of patients with diverticulosis in comparison with healthy subjects. By using a 16S-23S based bacterial profiling technique, authors showed no difference between subjects with and without diverticula; in addition, the microbiota profiling was similar in the sigmoid and in the transverse region [ 73 ].…”

“…A recent study evaluated T lymphocytes and neutrophils in the sigmoid and in the transverse colonic biopsies of patients with diverticulosis in comparison with healthy subjects. No difference emerged for T cells between the two groups, while neutrophils were not found in the analyzed samples [ 73 ]. Unfortunately, none of these three latter studies evaluated mucosal macrophages.…”

Microbiota Composition in Diverticular Disease: Implications for Therapy

“…Currently, the GM composition in patients with diverticulosis as the primary endpoint has been profiled in only two studies ( Table 1 ). Both studies analyzed mucosa-associated microbiota using PCR metagenomics [ 7 ] and 16S rRNA microbial profiling [ 8 ]. Although these studies had significantly different sample sizes, neither found a significant microbial imbalance in people with diverticulosis compared with controls [ 7 , 8 ].…”

“…Both studies analyzed mucosa-associated microbiota using PCR metagenomics [ 7 ] and 16S rRNA microbial profiling [ 8 ]. Although these studies had significantly different sample sizes, neither found a significant microbial imbalance in people with diverticulosis compared with controls [ 7 , 8 ]. However, one exciting feature arose from the study of Jones et al [ 7 ], who found a slight but not significant reduction in Proteobacteria and Comamondaceae in their patients.…”

“…The first exciting finding was that asymptomatic diverticulosis is not linked to significant GM alterations. As reported in Table 1 , two studies analyzing the mucosa-associated microbiota failed to find any significant alteration in these patients, except for a slight but insignificant reduction in Proteobacteria and Comamondaceae [ 7 , 8 ]. These findings probably mean that GM changes do not play any role in diverticulosis, in which genetics and the modifications of the characteristic of the colonic wall are still the most important factors [ 1 ].…”