| Background:Tuberculosis(TB),which is caused by Mycobacterium tuberculosis(MTB)infection,is still the highest infectious disease in the world.The host's immune defense system is particularly important in TB patients,innate immunity is the first line of defense against M.tuberculosis infection.Macrophages(M?)are antigen-presenting cells that play an important role in the natural immune anti-tuberculosis effect.However,M.tuberculosis can achieve immune escape through various mechanisms.In macrophages,the pattern recognition receptors that mediate M.tuberculosis infection are mainly Toll-like receptors,whose downstream plays a significant anti-tuberculous effect.?-arrestin 2 is a classic scaffold protein that participates in the regulation of signal pathways such as MAPK belong to downstream of G protein-coupled receptors and regulates the NF-?B pathway belongs to downstream of TLR4 activated by LPS.But it has not been reported that the effect and mechanism of ?-arrestin 2 in macrophage against M.tuberculosis infection.Objectives:1.To validate ?-arrestin 2 expression and effects in tuberculosis patients and its immunomodulatory effects against M.tuberculosis in vivo.2.To explore the expression of ?-arrestin 2 in M? infected by M.tuberculosis,and the survival of M.tuberculosis in M?.3.To explore the mechanism and effect of ?-arrestin 2 in anti-tuberculosis effect in macrophages.4.To demonstrate the mechanism of ?-arrestin 2 signaling pathway that regulates M?anti-M.tuberculosis infection activity.5.To explore the upstream TLR species of ?-arrestin 2-ERK1/2 signal pathway.Methods:1.The expression and activation of protein:Real-time PCR,immunofluorescence and Western blot.2.The expression of cytokine detection:Real-time PCR and ELISA.3.Colony-forming units(CFU)assays were utilized to ensure the reliable quantification of intracellular mycobacterial?spleen and lung in vivo.4.Spleen and lung were stained with HE to detect the degree of organ damage.Results:1.Elevated level of ?-arrestin 2 in lung tissue biopsies from TB patients;Silencing of P-arrestin 2 protects organ from M.tuberculosis infection in vivo.2.p-arrestin 2 decreased first and then increased at the RNA level,and increased expression at the protein level in M.tuberculosis infected M?.3.Silencing of ?-arrestin 2 protects M? from M tuberculosis infection.4.Silencing of ?-arrestin 2 promotes the expression of vital pro-inflammatory cytokines.5.The pro-inflammatory mediator response of P-arrestin 2 is mainly through inhibiting ERK1/2 pathway in M.tuberculosis infectioius M?.6.The ?-arrestin 2-ERK1/2 pathway is Downstream of the TLR2 receptor.Conclusions:The study found that ?-arrestin 2 increased significantly in M.tuberculosis-infected macrophages,suggesting that ?-arrestin 2 plays an important role in anti-tuberculosis immunity of macrophages.In addition,this study found that silencing of ?-arrestin 2 can notably promote the expression of proinflammatory factors TNF-?,IL-1? and IL-6 in M.tuberculosis infectious macrophages,thereby inhibiting M.tuberculosis survival and reducing experimental animal tissue damage.Mechanism studies have shown that ?-arrestin 2 inhibits the activation and transcriptional regulation of ERK1/2 belong to downstream of TLR2,regulates the expression of TNF-?,and thus regulates M? anti-M.tuberculosis infection activity.In summary,?-arrestin 2 up-regulated after M.tuberculosis infection inhibits the killing effect of M? on intracellular bacteria and promotes the immune escape of M.tuberculosis.The TLR2-?-arres tin 2-ERK1/2-TNF-? axis of action provides a new target for anti-tuberculosis immunotherapy... |
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