El Hadad Sahar, Zakareya Ayeshah, Al-Hejin Ahmed, Aldahlawi Alia, Alharbi Mona
Department of Biological Science, Faculty of Science, King Abdulaziz University, Jeddah, Saudi Arabia.
Research Center of Genetic Engineering and Bioinformatics, VACSERA, Cairo, Egypt.
Heliyon. 2019 Dec 12;5(12):e02866. doi: 10.1016/j.heliyon.2019.e02866. eCollection 2019 Dec.
Numerous dietary products are supplemented with probiotics that may be beneficial for human health. Recently, bifidobacteria have received increasing attention as a genus of probiotic bacteria with high efficiency and few side effects. To examine potential effects of different bifidobacteria concentrations on the mucosal immune response, we fed mice with (a) 10 colony-forming units (CFU) of bifidobacteria (group 10 ), and (b) with 10 CFU of bifidobacteria (group 10 ) over 42 days and assessed gene expression in intestinal mucosa and immune marker concentrations in serum samples; ten untreated female mice were used as a control. Continuous exposure to 10 CFU of bifidobacteria activated both macrophages and T immune cells through significantly increasing the expression of mucosal TLR2 and IL10-mRNA genes, but inhibited Th1 and Th2 cells via significant downregulation of IL4 and IFNγ gene expression, compared to untreated mice. Interestingly, group 10 showed down-regulated expression of TLR2, IL10, and IL4 genes but up-regulated expression of IFNγ, compared to group 10 and to the control. Also, polyclonal immunoglobulins IgG, IgM, and IgA showed a significant increase in all treated mice compared to the control. We conclude that high concentrations of bifidobacteria reduced innate immune functions. Furthermore, adaptive immunity seemed to be enhanced by increasing stimulation of T and B lymphocytes, suggesting aberration of the immune system following intestinal inflammation due to constant exposure to high concentrations of bifidobacteria. Both experimental bifidobacteria concentrations increased the total levels of circulating Igs, particularly of IgA.
许多膳食产品都添加了可能对人体健康有益的益生菌。最近，双歧杆菌作为一类高效且副作用少的益生菌受到了越来越多的关注。为了研究不同浓度双歧杆菌对黏膜免疫反应的潜在影响，我们在42天内给小鼠喂食：(a) 10个双歧杆菌菌落形成单位（CFU）（10组），以及(b) 10⁸CFU的双歧杆菌（10⁸组），并评估肠道黏膜中的基因表达以及血清样本中的免疫标志物浓度；十只未处理的雌性小鼠用作对照。与未处理的小鼠相比，持续暴露于10⁸CFU的双歧杆菌通过显著增加黏膜TLR2和IL10 - mRNA基因的表达激活了巨噬细胞和T免疫细胞，但通过显著下调IL4和IFNγ基因表达抑制了Th1和Th2细胞。有趣的是，与10组和对照组相比，10⁸组显示TLR2、IL10和IL4基因的表达下调，但IFNγ的表达上调。此外，与对照组相比，所有处理组小鼠的多克隆免疫球蛋白IgG、IgM和IgA均显著增加。我们得出结论，高浓度的双歧杆菌会降低先天免疫功能。此外，适应性免疫似乎通过增加对T和B淋巴细胞的刺激而增强，这表明由于持续暴露于高浓度双歧杆菌导致肠道炎症后免疫系统出现异常。两种实验性双歧杆菌浓度均增加了循环免疫球蛋白的总水平，尤其是IgA的水平。
