Because our immune system has a complex interaction with gut microbiome and enteric pathogens, exploring autoimmune pathways in gut dysmotility could lead to biomarker-driven immunotherapies, Ali Rezaie, MD, MSc, said during his abstract presentation at the 2023 American College of Gastroenterology Postgraduate Course on October 21, in Vancouver, Canada.

Dr Rezaie is medical director of the GI motility program at Cedars-Sinai Medical Center in Los Angeles, California.

“Small intestinal bacterial overgrowth is an objectively defined secondary dysbiotic disease,” Dr Rezaie said in his presentation on the role of autoimmunity in postinfectious irritable bowel syndrome (IBS).

To answer where autoimmunity fits in the IBS pathophysiology, Dr Rezaie explained that “not every defined pathophysiologic pathway of IBS equally applies to each individual patient.” Autoimmune pathways have been linked to postinfectious dysmotility and microbiome pathways.

Dr Rezaie referred to the TARGET 3 trial in diarrhea-predominant IBS (IBS-D) by Dr Anthony Lembo and colleagues to suggest that repeat treatment with rifaximin was effective and well-tolerated. The phase 3, randomized, double blind, placebo-controlled trial showed that the 64.4% of the patients that relapsed to the first round of open-label rifaximin, when exposed to second round of rifaximin, responded much better. The responders to repeat rifaximin were 38.1% compared to responders to placebo (31.5%)

Why does it matter if autoimmunity is present in IBS? So that discovery of antibodies can pave the path for precision immunotherapy in a proportion of patients with dysmotility, Dr Rezaie explained.

Reference:

Rezaie A. Are SIBO and IBS autoimmune responses to intestinal dysbiosis? Symposium C: Autoimmune and dysbiotic GI diseases from celiac disease to eosinophilic gastrointestinal disorders: What is the scoop? Presented at: 2023 ACG Postgraduate Course. Vancouver, Canada. October 21, 2023.