The Regulation Mechanism Of Hedgehog And NF-κB Signal Pathway In The Inflammation Response Of AEC Ⅱ Infected By Mycobacterium Tuberculosis

Background:The lung function is gas exchange, it is contact with foreign substances directly through respiratory tract. The more evidence has been found that suggests the Type Ⅱ alveolar epithelial cells (AECⅡ), as stem cells, plays an important role in the body’s defense exogenous pathogens infection in the lung tissue. And they can secrete the cytokines to promote inflammatory response, which will help macrophage clear the exogenous pathogens. Many reserchers found that the hedgehog signaling pathway, which ever was the key pathway for regulating embryonic development, also play an important role in the process of resisting pathogens invasion and the NF-κB signaing pathway also take pate in this process. This phenomenon reminds us that Hedghog and NF-κB signaling pathways maybe play a role in the body’s inflammatory response for defensing against Mtb infection.Projectes:We want to find out the expression change of the signaling moleculars of Hedgehog and NF-κB signaling pathway in the inflammatory response during the M.tuberculosis (BCG/H37Rv) infecting the AEC II.Method:Detecte and anyalze the signaling moleculars of AEC II (A549 cell) by the Realtime-PCR, Westen-blot and ELISA after A549 cells of normal and its Shh or NF-κB overexpression infected with BCG and H37Rv respectively.Results:1. When A549 cells infected with BCG and H37Rv, the expression of Shh, Ptch and Glil in Hedgehog signaling pathwaysand the p-NF-KB in NF-κB signaling pathways are up-regulated. At the same time, IL-8 and TNF-a were down-regulatecd. In addition, the expression of Shh、Ptch、Glil and NF-κB in BCG group are higher than H37Rv group.2. The expression of Shh, Glil and IL-6, IL-8 can be up-regulated in A549 cells with NF-κB over-expression. When infected the NF-κB overexpression A549 cells with BCG, the expression of Shh, Gli 1, Ptch, IL-6 and TNF-a were increased, and the same as infected with H37Rv, but these molecules expression level is less than the BCG infected3. When Shh overexpressed in A549 cells, the expression of Shh, Glil, p-NF-KB and IL-8, TNF-a can be up-regulated. The expression of Shh, Gli 1 and p-NF-KB are also increased in shh-overexpression A549 cells infected with BCG and H37Rv respectively. And the expression of IL-6 and IL-8 were promoted in Shh-overexpression A549 cells infected with BCG, as contrast, the expression of IL-12A and TNF-a were promoted in Shh-overexpression A549 cells infected with H37Rv.Conclusions:1. The infection of H37Rv and BCG on AEC II cells can activate the Hedgehog and NF-κB signal pathway and inflammation response. The activation of Shh and NF-κB signaling pathway in AEC Ⅱ cells could be promoting mutually. And the signal pathway activativation level of H37Rv infected is less than BCG infected in AEC Ⅱ cells, the expression of inflammatory cytokines in H37Rv infected group are higher than BCG infected group.2. The regulation of AEC Ⅱ cells’ inflammatory response by Shh overexpression was content with the virulence of Mtb:the expression of inflammatory cytokine was inhibited by BCG infection, but promoted by H37Rv.3. The activation of Hedgehog signaling pathway and inflammatory response were all enhanced in the NF-κB over-expression AEC Ⅱ cell infected with BCG and H37Rv, but the activation level of Shh signaling pathway and inflammatory cytokines secreation in AEC Ⅱ infected with H37Rv was less intensine than BCG infected.