乳酸菌对尘螨致敏哮喘小鼠模型的免疫调节作用

目的：探讨乳酸菌（LAB）对尘螨（gh）变应原致哮喘小鼠模型的免疫调节作用。方法：将实验小鼠分为对照组（等渗盐水组），哮喘组（尘螨致敏激发组）、哮喘＋乳酸乳球菌组和哮喘＋植物乳杆菌组四组。将四组动物分别进行肺泡灌洗液（BALF）、细胞总数及嗜酸性粒细胞（EOS）计数，同时检测BALF中自细胞介素4（IL-4）、IL-5和1干扰素（IFN-1）细胞因子水平（ELISA法）；肺组织病理学检查；脾细胞分离培养，检测培养上清IL-4、IL-5、IFN-1和IL-10水平（ELISA法）以及脾细胞增殖实验（BrdU法）。结果：①哮喘组BALF细胞总数、EOS比率、IL-4、IL-5水平均比对照组显著增高（P〈0．05），哮喘＋乳酸乳球菌组比哮喘组显著减少（P〈0．05），哮喘＋植物乳杆菌组的IL-5水平也低于哮喘组（P〈0．05），其余指标与哮喘组比较无显著差异（P〉0．05）。②在基础状态下，哮喘＋乳酸乳球菌组和哮喘＋植物乳杆菌组脾细胞合成释放IL-4、IL-5及IFN-1水平均明显低于哮喘组（P〈0．05），哮喘＋乳酸乳球菌组明显低于对照组（P〈0．05）。与此同时，哮喘＋乳酸乳球菌组和哮喘＋植物乳杆菌组IL-10的生成显著增加（P〈0．05），并以哮喘＋乳酸乳球菌组更明显。尘螨刺激下，哮喘组脾细胞IL-4、IL-5的释放率明显高于对照组（P〈0．05），哮喘＋乳酸乳球菌的释放率明显低于哮喘组（P〈0．05），其余各组间无显著差异（P〉0．05）；IFN-1的释放率在各组间无显著差异（P〉0．05）；哮喘＋乳酸乳球菌组IL-10的释放率明显高于其余三组（P〈0．05）。③在基础状态（无尘螨刺激）下，各组间脾细胞BIdU掺入量无明显差异（P〉0．05）；尘螨刺激后。哮喘组细胞的掺入量明显高于其他各组（P〈0．05），而哮喘＋乳酸乳球菌组、哮喘＋植物乳杆菌组与对照组BrdU的掺入量无显著差异（P〉0．05）。结论：口服LAB可改善尘螨致哮喘小鼠的哮喘反应，乳酸乳球菌比植物乳杆菌更能下调尘螨所致的气道EOS炎症及相应的Th2细胞因子的水平。其免疫调节可能与诱导生成抑制性细胞因子IL-10、同时下调Th1／Th2细胞因子及相应的嗜酸细胞炎症相关。

Immunomodulatory effects of lactobacillus on dust mite sensitized murine model

Objective: To compare the immunomodulatory capability to allergic asthma between orally taken Lactococcus lactis and Lactobacillus Lactobacillus plantarum in dust mite-sensitized mice. Methods: C57BL/6 mice were divided into four groups;Group N,M,L and P.Mice in M,Land P groups were sensitized with 2 % mite extract on day 0,7and 14 and challenged with 4% mite extract on day 21,22,23 and 24.Meanwhile we fed Lactococcus lactis and Lactobacillus plantarum to mice in L and P group respectively from each day of sensitization on as well as from the first day of challenge on,continuing for five days.Mice in N and M group were treated with saline as control.Histopathologic examination in the lung tissues of the mice was performed at day 3 after the last challenge.Cell count and classification,and Th1/Th2 cytokine levels in BALF were measured simultaneously.Isolated splenocytes from the mice were subjected to the detection of cell proliferation by BrdU incorporation in response to the mite extract.Using ELISA,the levels of Th1/Th2 cytokines in the supernatant of mite-stimulated splenocytes were measured. Results: Pulmonary allergic inflammation with eosinophilic infiltration as well as increased levels of IL-4 and IL-5 in BALF were observed in mice sensitized/challenged with mite extract(Group M).Pulmonary inflammation was decreased significantly in group L concomitant with down regulated levels of IL-4 and IL-5,total cell count and the percentage of eosinophils in BALF(P<0.05).In isolated mice splenocytes in group L,BrdU incorporation and the levels of IL-4 and IL-5 in the supernatant of the cells were markedly lower than those in Group M(P<0.05),while the level of IL-10 was high(P<0.05).Mice fed with L.plantarum(P) had higher rate of eosinophilic airway inflammation and lower level of IL-10 in the culture supernatant of splenocytes than Group L. Conclusion: Oral administration of Lc.lactis was effective in decreasing allergic airway inflammation by the inhibition of dust mite-induced cytokines(IL-4 and IL-5) release from T cell,the elevation of IL-10 might play an important role in the process.It was suggested that Lc.lactis was optimal candidate as vector of oral vaccine for the management of allergic inflammation.