Effect of miR-155 on acute lung injury in burned rats: Changes of nuclear factor-kappa B pathway / 中国组织工程研究

ABSTRACT

BACKGROUND: Currently, studies have focused on the role and mechanism of nuclear factor-kappa B pathway in the pathological process of acute lung injury in burned rats, such as the targeting inhibition of kB kinase by miR-155, which further weakens the activity of nuclear factor-KB and plays a role in acute lung injury in burned rats. However, there are still some pathological mechanisms to be studied and confirmed. OBJECTIVE: To investigate the effect of miR-155 on acute lung injury in burned rats through nuclear factor-KB pathway. METHODS: The rat models of acute lung injury were established by warm water bath simulating bum injury. The burned rats were divided into acute lung injury, miR-155-mimics and miR-155-inhibitor groups. After fluid resuscitation, the rats in the miR-155-mimics and miR-155-inhibitor groups were injected into the tail vein of 5 |_iL of miR-155-mimics and miR-155-inhibitions, respectively. The expression levels of tumor necrosis factor-a and interleukin-1 p in bronchoalveolar lavage fluid were detected by ELISA. The lung morphology in the three groups was observed by hematoxylin-eosin staining. The protein expression levels of nuclear factor-KB and cyclooxygenase 2 were evaluated by western blot assay. The nuclear factor-KB protein in lung tissues was detected by immunohistochemistry. RESULTS AND CONCLUSION: (1) The results of hematoxylin-eosin staining showed that the severity of lung injury in the miR-155-inhibitor group, acute lung injury group and the miR-155-mimics group was increased gradually (P < 0.05). (2) ELISA results showed that compared with the acute lung injury group, the expression levels of tumor necrosis factor-a and interleukin-1 p were increased in the miR-155-mimics group (P < 0.05), and decreased in the miR-155-inhibitor group (P < 0.05). (3) Western blot assay results showed that compared with the acute lung injury group, the expression levels of nuclear factor-KB and cyclooxygenase 2 proteins were increased in the miR-155-mimics group (P < 0.05), and decreased in the miR-155-inhibitor group (P < 0.05). (4) Immunohistochemical results showed that the expression level of nuclear factor-KB was increased in the miR-155-inhibitor group, which was dark brown. The expression of nuclear factor-KB in cytoplasm and nucleus of neutrophils, mononuclear macrophages, alveolar epithelial cells was the most obvious. (5) These results indicate that in lung tissue cells, decreased miR-155 can down-regulate nuclear factor-KB activity, which reduces the inflammatory response of the lung between the damaged tissue. The study was approved by the Laboratory Animal Ethics Committee of the First People’s Hospital of Neijiang, approval No. 1801270.