April 16, 2018
2 min read

Association possible between gut bacteria, uveitis

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A study showed a possible link between bacteria in the gut and the development of ocular manifestations, particularly uveitis, in patients with inflammatory bowel disease.

According to study data presented at the American Uveitis Society fall meeting, a microbial signature may be able to predict the development of uveitis in patients with inflammatory bowel disease (IBD), Faazil Kassam, MD, told Ocular Surgery News.

“It is poorly understood why patients with inflammatory bowel disease, Crohn’s disease and ulcerative colitis are at risk of developing uveitis, inflammation of the iris, ciliary body or choroid in the eye. We sought to examine whether there might be a link between the bacteria in the gut and the development of ocular manifestations, or more specifically, is there a microbial signature that could predict the development of the eye disease in IBD patients?” Kassam said.

Kassam and colleagues conducted a case-control study that collected biopsy tissue samples from the Intestinal Inflammation Tissue Bank at the University of Calgary. The study included patients with IBD with uveitis or episcleritis. The researchers found IBD control subjects who were matched for age, gender, type of IBD and biopsy location, and did not have any extraintestinal manifestations of their disease.

“Other information such as medical comorbidities, immunosuppressive therapies, recent use of antibiotics and bowel surgeries was also collected,” Kassam said.

The researchers compared the biopsies of patients with and without uveitis. Biopsy samples were analyzed using standard 16S rRNA sequencing and statistical analysis using DESeq2, Kassam said.

The tissue samples were sent to the MIT-MGH Center for Microbiome Informatics and Therapeutics in Cambridge, Massachusetts, for DNA extraction and 16S rRNA sequencing and statistical analysis, he said.

The study included 18 patients with IBD and uveitis or episcleritis and 34 control subjects. The mean age of the study patients was 46.8 years, with 61% female patients. The mean age of the control subjects was 44.8 years, with 62% female patients.

Notable differences

The microbiome profile of IBD patients with uveitis was distinct, with notable differences at the family and genus level, Kassam said.

“From the analysis, there were notable differences that included a decrease in the relative abundance of the family Coriobacteriaceae (P = .0007) and an increase in the relative abundance of Fusobacteriaceae (P = .005) in IBD patients with uveitis as compared to those without extraintestinal manifestations,” he said.

Kassam noted that this study is the first to demonstrate a possible association between gut microbiome and uveitis in IBD.

“Further studies are needed to determine whether these findings are replicable but raise the possibility that specific bacterial species could contribute to the development of the eye disease. If so, targeted therapies to alter the microbiome could potentially result in better treatment options for IBD patients with uveitis,” he said. – by Robert Linnehan

Disclosure: Kassam reports no relevant financial disclosures.