| Tuberculosis is a chronic wasting zoonoses that was caused by Mycobacterium tuberculosis (Mtb) infection, about 20 million people infected with the disease worldwide in a year, of which 10% is likely to develop active tuberculosis. Pathogenesis of Mycobacterium tuberculosis is very complex. In recent years, drug-resistant tuberculosis (DR-TB) and extensively drug-resistant tuberculosis (XDR-TB) appears that lead to clinical treatment of tuberculosis great difficulties, especially in mixed infections with other diseases (such as HIV) increases the mortality. However, currently, BCG is the only means of preventing tuberculosis that only effective for children and young people, not for adult, for protection rate of BCG is very low. Therefore, searching for new and effective ways to conquer TB is particularly emergency. In recent years, found that alveolar type Ⅱ cells (AECⅡ) as the lungs of the "physical barrier", together with alveolar macrophages in the body against Mtb infection plays an important immune regulatory functions. The miRNA is derived as a non-coding RNA has a regulatory function which play a important role in the course of the organisms’development, physiology and pathogenesis. miRNA can affect host resistance Mtb infection process, and its abnormal expression is closely related to the tuberculosis. As we all know, Toll-like receptors (Toll-like receptors, TLRs) as the innate immune pattern recognition receptors (PRR) which is a bridge connect innate immunity and acquired immunity, its ability to monitor and identify a variety of pathogen-associated molecular pattern (PAMP), as "the first barrier" to resist the pathogens (such as Mtb) infection. Therefore, in order to reveal The immune regulation of miRNA on Toll-like receptor signaling pathway during alveolar Ⅱ type epithelial cell infected with Mycobacterium tuberculosis, we built cells-bacterial interaction model with the establishment of international standards of Mycobacterium tuberculosis H37Rv and attenuated strain virulent strain BCG infect human AEC Ⅱ (A549). Based on the initial experiment results that differences in miRNA expression profiles, we analyze the AEC Ⅱ cells changes that TLRs signaling pathways and the expression of miR-29a, miR-146a and miR-200c after Mtb infection, and depeth analysis of the overexpressing miR-146a impact on TLRs signaling pathway in AEC Ⅱ cells. The results list below:(1) H37Rv or BCG infection AECⅡ(A549) in 6 hour,12 hour and 24 hour, we detect the expression of TLRs signaling pathway, proinflammatory cytokines and miR-29a, miR-146a and miR-200c. The results showed that A549 cells’ TLR2/4, NFκB, MyD88 mRNA and protein expression levels were significantly highe infection at 6h and H37Rv infected group higher than BCG infection. Cytokines TNF-α, EL-1α and IL-6 mRNA expression levels of IL-8 and IL-12α increases with time of infection, and the expression of TNF-α, IL-1α, IL-6 and IL-8 in H37Rv infection group was significantly higher than that of BCG infection, IL-12α difference was not significant, however IL-6 significantly decrease at 24 hour in H37Rv infection group. With the infection time the miR-146a was significantly increased and H37Rv higher than BCG. The miR-29a expression level was significantly higher than that of BCG. H37Rv infection at 6h, but at... |
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