The Mechanism Of MiR-495 Regulating The Intracellular Survival Of Mycobacterium Tuberculosis After Infection With Macrophages By Targeting SOD2

Mycobacterium tuberculosis(Mtb)is the causative agent of the chronic infectious disease tuberculosis.The pathogen can cause various diseases,with pulmonary tuberculosis being the most common.Tuberculosis is mainly spread through the respiratory tract and can cause outbreaks in groups.In order to prevent and treat tuberculosis,it is very important to study the pathogenicity of Mtb.The immune escape mechanism of tuberculosis has always been an urgent but difficult problem.The escape mechanism promotes the bacteria to exist in macrophages without being eliminated.Therefore,it is important to study the intracellular survival mechanism of tuberculosis.Preliminary studies in our laboratory found that SOD2 protein level increased under Mtb infection.To explore the mechanism and the effect of SOD2,series of experiments were carried out and the main experiments and results are as follows:1.The level of SOD2 rises under Mtb infectionThe expression of SOD2 was detected by bacterial and cell interaction test in vitro and infection test in vivo.The results showed that BCG or H37 Rv infection could increase the expression level of SOD2 in the host.2.SOD2 promotes the intracellular survival of BCG/H37 Rv by reducing the level of ROSThrough experiments such as overexpression and silencing of cell SOD2,detection of intracellular ROS levels,and cellular ROS induction,we found that SOD2 inhibits intracellular ROS level,the intracellular survival of BCG decreased under the action of ROS inducer,and SOD2 can promote the bacteria invasion and intracellular replication of BCG/H37 Rv.These results proved that SOD2 can promote the intracellular survival of BCG/H37 Rv by inhibiting the ROS level.3.Mtb promotes the expression of SOD2 through mi R-495,reduces the level ofintracellular ROS,and improves its intracellular survival.In order to explore the regulation mechanism of SOD2,bioinformatics analysis and prediction were used and five micro RNAs that may regulate SOD2 were screened out.Through experiments such as detection of mi RNA expression level under BCG/H37 Rv infection,dual luciferase expression system,overexpression/suppression of micro RNA and other experiments,we confirmed that Mi R-495 inhibits SOD2 expression by directly binding to the 3’UTR of the SOD2.Through the detection of cellular ROS levels,the CFU assay after BCG/H37 Rv infection,we have confirmed that Mtb can increase the expression level of SOD2 by inhibiting the expression of mi R-495,thereby decreasing the level of intracellular ROS and improve its own intracellular viability.In summary,this study revealed the effect of SOD2 on the intracellular survival of Mtb and elucidated the regulatory mechanism of SOD2.