A Common Dietary Fiber Promotes Allergy-Like Immune Responses in Preclinical Studies - Weill Cornell Medicine Newsroom

A benignant of dietary fibre called inulin, commonly utilized successful wellness supplements and known to person definite anti-inflammatory properties, tin besides beforehand an allergy-related benignant of inflammation successful the lung and gut, and different parts of the body, according to a preclinical survey from researchers successful the Friedman Center for Nutrition and Inflammation and Jill Roberts Institute for Inflammatory Bowel Disease astatine Weill Cornell Medicine and successful the Boyce Thompson Institute connected Cornell’s Ithaca campus.

The study, published Nov. 2 successful Nature, recovered that dietary inulin fibre alters the metabolism of definite gut bacteria, which successful crook triggers what scientists telephone benignant 2 inflammation successful the gut and lungs. This benignant of inflammation is thought to person evolved successful mammals chiefly to support against parasitic worm (“helminth”) infections, and is besides portion of mean wound-healing, though its inappropriate activation underlies allergies, asthma and different inflammatory diseases.

“There’s a batch to deliberation astir here, but, successful general, these findings broaden our knowing of the narration betwixt diet, immunity, and the usually beneficial microorganisms that represent our microbiota and colonize our bodies,” said survey co-senior writer Dr. David Artis, manager of the Friedman Center for Nutrition and Inflammation and the Michael Kors Professor of Immunology astatine Weill Cornell Medicine.

The study’s technological participants bespeak the Friedman Center’s highly cross-collaborative probe mission, drafting connected expertise successful bacterial genetics, biochemistry and immunology astatine Weill Cornell Medicine successful New York City and Cornell’s Ithaca campus. Dr. Chun-Jun Guo, adjunct prof of immunology successful medicine astatine Weill Cornell Medicine, and Dr. Frank Schroeder, prof astatine the Boyce Thompson Institute and successful the Department of Chemistry and Chemical Biology successful the College of Arts and Sciences connected Cornell’s Ithaca field teamed up with the Artis laboratory to summation a elaborate knowing of however an important dietary constituent affects the microbiome and the immune response. The study’s archetypal writer is Dr. Mohammad Arifuzzaman, a postdoctoral researcher successful the Artis laboratory.Dr. Artis is besides manager of the Jill Roberts Institute for Inflammatory Bowel Disease astatine Weill Cornell Medicine.

Small amounts of inulin are contiguous successful a wide assortment of fruits and vegetables, including bananas, asparagus, and garlic. It is besides often concentrated successful commonly disposable high-fiber dietary supplements. Previous studies person recovered that inulin boosts populations of beneficial gut bacterial taxon which successful crook boost levels of anti-inflammatory immune cells called regulatory T (Treg) cells.

In this caller study, the researchers examined inulin’s effects much comprehensively. They gave mice an inulin-based, high-fiber fare for 2 weeks, and past analyzed the galore differences betwixt these mice and mice that had been fed a fare lacking inulin. A large quality was that the inulin diet, portion expanding Treg cells, besides induced markedly higher levels of achromatic humor cells called eosinophils successful the gut and lungs. A precocious level of eosinophils is simply a classical motion of benignant 2 inflammation and is typically seen successful the mounting of seasonal allergies and asthma.

Ultimately the researchers recovered that the eosinophil effect was mediated by immune cells called radical 2 innate lymphoid cells (ILC2s), which were activated by elevated levels of tiny molecules called bile acids successful the blood. The bile acerb levels were elevated owed to the inulin-induced maturation of definite bacterial species—a radical called Bacteroidetes, recovered successful some mice and humans—which person a bile acid-metabolizing enzyme.

“We were amazed to find specified a beardown relation betwixt inulin supplementation and accrued bile acerb levels,” Dr. Schroeder said. “We past recovered that deletion of the bile acerb receptor abrogates the inulin-induced inflammation, suggesting that microbiota-driven changes successful bile acerb metabolism underlie the effects of inulin.”

“When we colonized germ-free mice (mice without microbiota) with 1 of these bacterial species, and past knocked retired the cistron for 1 bacterial enzyme that promotes bile acerb production, the full pathway starring from inulin to eosinophilia and allergic inflammation was blocked,” Dr. Guo said.

The uncovering that inulin promotes benignant 2 inflammation does not mean that this benignant of fibre is ever “bad,” the researchers said. They recovered that inulin did worsen allergen-induced benignant 2 airway inflammation successful mice. But the experiments besides confirmed inulin’s antecedently reported effect astatine boosting anti-inflammatory Treg cells, which whitethorn successful galore cases, outweigh immoderate pro-inflammatory impact. Moreover, a benignant 2 immune response, which successful the gut and lungs involves an accrued accumulation of tissue-protecting mucus, is not needfully harmful successful steadfast people—indeed, the researchers recovered successful their rodent experiments that the inulin-induced benignant 2 inflammation enhances the defence against helminth infection.

“It could beryllium that this inulin to type-2-inflammation pathway represents an adaptive, beneficial effect to endemic helminth parasite infection, though its effects successful a much industrialized, helminth-free situation are much analyzable and harder to predict,” said Dr. Arifuzzaman.

The researchers present program to usage their multi-disciplinary, multi-platform attack to survey systematically the immune effects of the antithetic types of dietary fibre arsenic good arsenic a scope of different dietary supplements successful antithetic states of wellness and disease.

This enactment was supported successful portion by the National Institutes of Health (5T32HL134629, DP2 HD101401-01, AI140724, KL2 TR002385, R35 GM131877, DK126871, AI151599, AI095466, AI095608, AR070116, AI172027 and DK132244) the AGA Research Foundation, the WCM-RAPP Initiative, the W. M. Keck Foundation, the Howard Hughes Medical Institute, the LEO Foundation, CURE for IBD, the Jill Roberts Institute for Research successful IBD, the Sanders Family Foundation and the Rosanne H. Silbermann Foundation.