A combination of fructo-oligosaccharides and Bifidobacterium breve M-16V suppresses airway resistance and inflammation in house dust mite allergic mice

Background: Allergic asthma is strongly associated with exposure to house dust mite (HDM). Allergic asthma is characterised by eosinophilic inflammation, mucus hypersecretion and airway hyperresponsiveness. There is an increased interest in using specific non-digestible oligosaccharides (OS) and beneficial bacteria to prevent development or reduce symptoms in allergic asthma. Aim: Study the effect of non-digestible fructo OS either alone or combined with Bifidobacterium breve M-16V (BB) on the development of HDM-induced allergic asthma in mice. Method: BALB/c mice were intranasally (i.n.) sensitised with 1 lg HDM on day 0 and challenged i.n. with PBS or 10 lg HDM on days 7 till 11. From day -14 till 14 mice were fed a control diet or a diet containing a 1 w/w% 1:1 mixture of short chain fructo-OS (scFOS) and long chain fructo-OS (lcFOS) without or with BB. On day 14 airway resistance was measured by applying increasing doses of methacholine in the airways of mice. After sacrificing bronchoalveolar lavage (BAL) fluid and lungs were collected. Results: Airway resistance was increased in HDM-allergic animals on a control diet. Dietary intervention with scFOS/lcFOS reduced airway resistance in presence or absence of BB. HDM allergy resulted in an influx of leukocytes in the BAL fluid (P <0.001), which was reduced by the scFOS/lcFOS/BB diet (P <0.01). Dietary intervention with scFOS/lcFOS decreased BAL eosinophil numbers (P <0.001) and neutrophils (P <0.01), when BB was added also the lymphocyte (P <0.01) and macrophage numbers reduced (P <0.05). HDM allergy resulted in significantly increased levels of interleukin (IL)-6, IL-13 and IL-33 in lung homogenates. The scFOS/lcFOS/BB diets reduced IL-6 levels (P <0.05). Conclusion: These findings suggest that B. breve M16-V combined with scFOS/ lcFOS has a beneficial effect on airway inflammation and hyperresponsiveness in HDM allergic mice.