Gut microbiota metabolism of dietary fiber influences allergic airway disease and hematopoiesis

 Aurélien Trompette, Eva S Gollwitzer, Koshika Yadava, Anke K Sichelstiel, Norbert Sprenger, Catherine Ngom-Bru, Carine Blanchard, Tobias Junt, Laurent P Nicod, Nicola L Harris and Benjamin J Marsland. Nat Med. (2014) 20:159-166

Speaker: Chi-Ting Hsieh (謝其庭)                                 Time: 14:10~15:00, May. 7, 2014

Commentator: Dr. Lien-I Hor (何漣漪 老師)             Place: Room 601

Abstract:

Dietary fibers have been shown to reduce risks of in gastrointestinal inflammatory disorders, but whether they provide an anti-inflammatory function outside the intestine remains unknown. Interestingly, epidemiologic studies indicate a potential association between insufficient dietary fiber uptake and asthma, an inflammatory /allergic response in airways. In this study, the authors showed that low-fiber diet enhanced, while high-fiber diet reduced, the allergic response in an animal model of allergic airway inflammation (AAI). Previous studies indicate that antibiotic-driven changes of intestinal microbiota enhance susceptibility to allergic asthma. Notably, the authors found that dietary fibers also altered the constitution of the gut microbiota, increasing the proportion of Bacteriodetes, the bacteria able to ferment soluble fibers into short-chain fatty acids (SCFAs). Consistently, mice fed with a high-fiber diet had an increased concentration of SCFAs in the cecum and serum, and mice treated with a SCFA propionate also showed resistance to development of AAI. The protective effect of propionate was dependent on G protein-coupled receptor 41 but was not associated with regulatory T cells. The authors further found that propionate increased both dendritic cell (DC) precursors in the bone marrow and newly recruited DCs in the lung. In the lung of propionate-treated mice, newly recruited DCs had phagocytic capacity but impaired ability to activate T helper type 2 cells, in agreement with the reduction of pulmonary inflammation. In conclusion, this study links dietary fibers, gut microbiota and its metabolites to the improvement of AAI. Therefore, modulation of the dietary fiber content should be a good strategy to control inflammation in both digestive and respiratory systems.

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