Dietary Fiber Intake Regulates Intestinal Microflora and Inhibits Ovalbumin-Induced Allergic Airway Inflammation in a Mouse Model

Abstract

BackgroundRecently, academic studies suggest that global growth of airway allergic disease has a close association with dietary changes including reduced consumption of fiber. Therefore, appropriate dietary fiber supplementation might be potential to prevent airway allergic disease (AAD).ObjectiveWe investigated whether dietary fiber intake suppressed the induction of AAD and tried to elucidate the possible underlying mechanisms.MethodsThe control mice and AAD model mice fed with 4% standard-fiber chow, while low-fiber group of mice fed with a 1.75% low-fiber chow. The two fiber-intervened groups including mice, apart from a standard-fiber diet, were also intragastric (i.g.) administrated daily with poorly fermentable cellulose or readily fermentable pectin (0.4% of daily body weight), respectively. All animals except normal mice were sensitized and challenged with ovalbumin (OVA) to induce airway allergic inflammation. Hallmarks of AAD were examined by histological analysis and ELISA. The variation in intestinal bacterial composition was assessed by qualitative analysis of 16S ribosomal DNA (rDNA) content in fecal samples using real-time PCR.ResultsLow-fiber diet aggravated inflammatory response in ovalbumin-induced allergic mice, whereas dietary fiber intake significantly suppressed the allergic responses, attenuated allergic symptoms of nasal rubbing and sneezing, decreased the pathology of eosinophil infiltration and goblet cell metaplasia in the nasal mucosa and lung, inhibited serum OVA-specific IgE levels, and lowered the levels of Th2 cytokines in NALF and BALF, but, increased Th1 (IFN-γ) cytokines. Additionally, dietary fiber intake also increased the proportion of Bacteroidetes and Actinobacteria, and decreased Firmicutes and Proteobacteria. Levels of probiotic bacteria, such as Lactobacillus and Bifidobacterium, were upgraded significantly.ConclusionLong-term deficiency of dietary fiber intake increases the susceptibility to AAD, whereas proper fiber supplementation promotes effectively the balance of Th1/Th2 immunity and then attenuates allergic inflammatory responses significantly, as well as optimizes the structure of intestinal microbiota, which suggests potential for novel preventive and therapeutic intervention.

Contributions of the intestinal microbiome in lung immunity

“…Future studies into the mechanistic relationship between diet, microbiota, genetics and lung inflammation may involve gnotobiotic models as well studying the effects of microbial metabolites on cell populations. responses such as lung eosinophilia, goblet cell metaplasia, as well as allergen-specific IgE and Th2 cytokines [63]. Protection in this model was associated with increased colonic Bacteroidetes and Actinobacteria species and decreased Firmicutes and Proteobacteria, suggesting that a high fiber diet may mitigate airway inflammation through modulation of the gut microbiota ( Fig.…”

“…IEC‐specific deletion of IKKβ, an inhibitor of the NF‐κB transcriptional complex, was associated with an increased ratio of Clostridia to Bacteroida and increased expression of Il17a and Ifng in lung tissue following allergen challenge. In contrast to a high‐fat diet, high fiber diets suppress airway allergic responses, including type‐2 responses such as lung eosinophilia, goblet cell metaplasia, as well as allergen‐specific IgE and Th2 cytokines . Protection in this model was associated with increased colonic Bacteroidetes and Actinobacteria species and decreased Firmicutes and Proteobacteria, suggesting that a high fiber diet may mitigate airway inflammation through modulation of the gut microbiota (Fig.…”

“…). For instance, the increased ratio of Bacteroidetes to Firmicutes species in response to high fiber diets will increase the production of SCFAs that suppress inflammation by activating GPR40‐43 . In future studies, it will be important to delineate which cell types must express individual GPRs in order to suppress airway inflammation and induce the generation of Tregs.…”

Neoagarotetraose protects mice against intense exercise‐induced fatigue damage by modulating gut microbial composition and function

“…A recent study proposed that an increased prevalence of Proteobacteria is a potential diagnostic signature of dysbiosis and risk of disease . Analogously, a recent report suggested that dietary fiber intake increases the proportion of Bacteroidetes and Actinobacteria while decreasing Firmicutes and Proteobacteria . In brief, the changed abundance of Bacteroidetes and Proteobacteria induced by NAT intervention is of great significance.…”

Efeitos da Suplementação de Fibras Solúveis, Dieta de Cafeteria e Exercício Físico sobre Aorta Torácica de Ratos

“…Como um nutriente essencial, têm apresentado um papel crucial na manutenção da saúde, com ações de prevenção e proteção para várias doenças humanas, tais como diabetes, doenças cardiovasculares e outras (MATTOS; MARTINS, 2000;BERNAUD;RODRIGUES, 2013;SLAVIN, 2013;ZHANG et al, 2016).…”