Fiber rich food suppressed airway inflammation, GATA3 + Th2 cells, and FcεRIα+ eosinophils in asthma.

Background: Allergic Asthma is a disease presenting various endotypes and no current therapies act curative but alleviate disease symptoms. Dietary interventions are gaining increasing importance in regulating immune responses. Furthermore, short chain fatty acids (SFCA), as the main products of dietary fiber's fermentation by the gut bacteria, ameliorate the pathogenesis and disease burden of different illnesses including asthma. Nevertheless, the connection and crosstalk between the gut and lung is poorly understood. Objective: In this work, the role of high fiber diet on the development of allergic asthma at baseline and after exacerbation of disease induced by respiratory viruses was investigated. Methods: Hereby, SCFA in serum of asthmatic and non-asthmatic pre-school children before and after airway disease symptoms were analyzed. Moreover, the effect of high fiber diet Results: In this study, a decrease of the SCFA 3-Hydroxybutyric acid in serum of asthmatic children after symptomatic episodes at convalescent visit as compared to asthmatic and control children at baseline visit was observed. In experimental asthma, in mice fed with high fiber diet, a reduced lung GATA3 + Th2 type mediated inflammation, mucus production and collagen deposition and expression of Fc epsilon receptor Ia (FcεRIa) in eosinophils was observed. By contrast, the CD8+ memory effector T cells were induced in the lungs of asthmatic mice fed with high fiber diet. Then, total lung cells from these asthmatic mice fed with either standard food or with fiber rich food were infected with RV Conclusion: Convalescent preschool asthmatic children after a symptomatic episode have less serum ß-Hydroxybutyric acid as compared to control and asthmatic children at baseline visit. Fiber rich diet associated with anti-inflammatory effects as well as anti-allergic effects by decreasing Type 2 and IgE mediated immune responses and inducing CD8+ memory effector T cells in a murine model of allergic asthma. Finally, Clinical implications: Dietary interventions with increased content in natural fibers like pectins would ameliorate asthma exacerbations. Moreover, respiratory infection in asthma downregulated SCFA in the gut contributing to asthma exacerbations.