The Microbial Ecosystem Distinguishes Chronically Diseased Tissue from Adjacent Tissue in the Sigmoid Colon of Chronic, Recurrent Diverticulitis Patients

Abstract

Diverticular disease is commonly associated with the older population in the United States. As individual’s age, diverticulae, or herniation of the mucosa through the colonic wall, develop. In 10–25% of individuals, the diverticulae become inflamed, resulting in diverticulitis. The gut ecosystem relies on the interaction of bacteria and fungi to maintain homeostasis. Although bacterial dysbiosis has been implicated in the pathogenesis of diverticulitis, associations between the microbial ecosystem and diverticulitis remain largely unstudied. This study investigated how the cooperative network of bacteria and fungi differ between a diseased area of the sigmoid colon chronically affected by diverticulitis and adjacent non-affected tissue. To identify mucosa-associated microbes, bacterial 16S rRNA and fungal ITS sequencing were performed on chronically diseased sigmoid colon tissue (DT) and adjacent tissue (AT) from the same colonic segment. We found that Pseudomonas and Basidiomycota OTUs were associated with AT while Microbacteriaceae and Ascomycota were enriched in DT. Bipartite co-occurrence networks were constructed for each tissue type. The DT and AT networks were distinct for each tissue type, with no microbial relationships maintained after intersection merge of the groups. Our findings indicate that the microbial ecosystem distinguishes chronically diseased tissue from adjacent tissue.

Diverticular Disease: a Gut Microbiota Perspective

“…Blooming of Enterobacteriaceae is one of the main distinctive features of severe dysbiosis, and generally represents the consequence of mucosal inflammation [42,43]. These results were confirmed in 9 patients with SCAD, who were subdued to multiple colonic biopsies from diseased tissue and adjacent colonic mucosa [44]. Bacterial 16S rRNA microbial profiling revealed that the mucosal microbiota was significantly different between diseased and adjacent tissue, but also that Enterobacteriaceae, such as Pseudomonas, were overrepresented in all samples [44].…”

“…These results were confirmed in 9 patients with SCAD, who were subdued to multiple colonic biopsies from diseased tissue and adjacent colonic mucosa [44]. Bacterial 16S rRNA microbial profiling revealed that the mucosal microbiota was significantly different between diseased and adjacent tissue, but also that Enterobacteriaceae, such as Pseudomonas, were overrepresented in all samples [44]. Another small study revealed that acute diverticulitis was associated with the overrepresentation of Bifidobacteria, namely Bifidobacterium longum [45].…”

An Aberrant Microbiota is not Strongly Associated with Incidental Colonic Diverticulosis

“…Therefore, we cannot exclude the role of the gut microbiota in the disease progression. Several small studies have reported alterations in the gut microbiota in SUDD patients 15 – 17 . Tursi et al .…”

Role of Inflammation in the Pathogenesis of Diverticular Disease

“…It has been hypothesized that microbial imbalance, which is known as dysbiosis, may be the trigger of inflammation (and therefore symptoms) in people having diverticulosis [55]. Daniels et al found that patients at the first episode of acute diverticulitis have a higher diversity of Proteobacteria than controls [56], and Schieffer et al found that Microbacteriaceae were the most significant species associated with the disease [57]. Microbiota imbalance was found also in SUDD, sometimes significantly differing from that reported occurring in Inflammatory Bowel Diseases (IBD).…”