Lactobacillus paracasei subsp. paracasei NTU 101對氣喘模式小鼠腸道與過敏免疫反應的影響

Abstract

Allergic asthma is the most common disease of type I hypersensitivity. Patients with allergic asthma have higher levels of IgE in serum which then act on Th2-prone immune responses. Lactobacilli are probiotic bacteria that can improve the intestinal environment and regulate the allergic reaction, but the efficacy vary with the different varieties. Lactobacillus paracasei subsp. paracasei NTU 101 (NTU 101) isolated from human faeces can promote Th1-prone immune responses of Peyer’s patches and primary splenocytes in several studies. The purpose of this study was to evaluate whether oral administration of the sample containing NTU 101 dead bacteria may prossess an immunomodulation effect on airway inflammation and gut immune responses in murine model of asthma. In this study, the 8-week-old BALB/c female mice were sensitized with ovalbumin (OVA) in Al(OH)3 adjuvant intraperitoneally. Mice were grouped by total IgE concentration in serum after one OVA-injection. Seven groups of mice were: control group (OVA/Ctrl), low (OVA/L), medium (OVA/M), high (OVA/H) dose NTU 101 product, inulin filler group (OVA / Inu), prednisolone group (OVA / Pred) as positive control, and non-sensitized mice (PBS / PBS) as blank control. During the tube-feeding period, mice were challenged with 5% OVA aerosol to induce allergic airway inflammation. 24 hours after aerosol OVA challenge, the AHR challenged by Mch were measured. Mice were sacrificed after tube-feeding for twenty-two weeks. The results showed that fed with NTU 101 product can’t attenuate AHR, indicate NTU 101 product can not ameliorate airway smooth muscle hyperresponsiveness. But in BALF, NTU 101 product reduced IL-4, TNF-α and IL-6 content. OVA/H group also decreased lung tissue weight, eotaxin content and eosinophil cell count. Fed with NTU 101 product could decrease not only the IL-13 production of OVA-stimulated splenocytes, but also the IFN-γ production of LPS-stimulated splenocytes. NTU 101 increased IFN-γ and IL-6 production in Peyer’s patches. OVA/H group and OVA/Inu group had significantly higher IL-10 production in MLN. In PP and MLN, OVA/L group significantly increased IL-2 level. Serum OVA-IgG2a spectacularly decreased in OVA/L group and OVA/M group. OVA/M group had significantly higher serum total IgG, total IgA and phagocytotic activity. Subsequently, EL4 cell line was treated with heat-killed NTU 101, inulin and NTU 101 product. The results showed the three group decreased IL-4 secretion in EL4 cell line. NTU 101 product may alleviate the Th2-prone immune responses in allergic asthma. In conclusion, OVA-sensitized mice fed with NTU 101 product could decrease the Th2-prone immune responses, but promote intestinal Th1-prone immune responses. NTU 101 product may reduce the systemic inflammatory response and respiratory tract inflammation.