Helicobacter pylori–specific Protection Against Inflammatory Bowel Disease Requires the NLRP3 Inflammasome and IL-18

Abstract

BACKGROUND The Gram-negative bacterium Helicobacter pylori is a constituent of the human gastric microbiota. Chronic infection with H. pylori causes gastritis and predisposes to gastric carcinoma but has also been inversely linked to various allergic and chronic inflammatory conditions. In particular, large meta-analyses have documented an inverse association between H. pylori infection and the risk of developing ulcerative colitis and Crohn's disease. METHODS We investigated possible protective effects of experimental H. pylori infection and of regular treatment with H. pylori extract in 2 mouse models of colitis and in mouse models of type I diabetes and multiple sclerosis. The mechanism of protection was examined in mouse strains lacking specific innate immune recognition pathways and cytokines. RESULTS We show here that experimental infection with H. pylori and administration of regular doses of H. pylori extract both alleviate the clinical and histopathological features of dextran sodium sulfateinduced chronic colitis and of T-cell transfer-induced colitis. High resolution endoscopy of the protected animals revealed the accumulation of large amounts of colonic mucus upon H. pylori exposure, which could be attributed to transcriptional activation of the mucin 2 gene. The protection against dextran sodium sulfate-induced colitis was dependent on the NLRP3 inflammasome and interleukin-18 signaling. Other autoimmune diseases, i.e., experimental autoimmune encephalomyelitis and type I diabetes, were not controlled by H. pylori. CONCLUSIONS In summary, we propose here that the immunomodulatory activity of an ancient constituent of the gut microbiota, H. pylori, may be exploited for the prevention and/or treatment of inflammatory bowel diseases.

Helicobacter pylori controls NLRP3 expression by regulating hsa-miR-223-3p and IL-10 in cultured and primary human immune cells

“…7 In contrast, persistent infection of H. pylori has also been found to be beneficial for the human host by suppressing other illnesses, including asthma, allergies and inflammatory bowel disease. [8][9][10][11] Host gene polymorphisms play a crucial role in producing different associated pathologies of H. pylori infection. Among these, a specific IL-1b gene polymorphism has prominence and was directly related to gastric cancer development.…”

The Gastrointestinal Tract Microbiota and Allergic Diseases

“…Semi-mature DCs are tolerogenic, that is, they exhibit a high propensity for priming Treg differentiation, but have only a limited ability to prime effector T-cell responses [86,87]. The tolerogenic DC/Treg axis likely accounts for the protection of H. pylori -infected individuals not only against allergic diseases but also against IBD [88,89,90,91] (fig. 2) and potentially against auto-immunity, as demonstrated in models of multiple sclerosis [92].…”

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