Abstract:

Objective: Preliminary exploration of miRNA-451a’s involvement in the pathogenesis of hematogenous disseminated pulmonary tuberculosis. Methods: (1) A prospective research method was adopted, from December 2018 to December 2019, 56 patients with secondary pulmonary tuberculosis and 24 patients with hematogenous disseminated pulmonary tuberculosis (HDPTB) treated at Beijing Chest Hospital were consecutively included as the case group, 17 healthy controls were selected from those who passed the physical examination in our hospital. Venous blood samples were collected along with sociodemographic and clinical data from all subjects. The expression levels of miRNA-451a and its target gene, macrophage migration inhibitory factor (MIF), in peripheral blood, were analyzed by real-time PCR (qRT-PCR). (2) Human acute monocytic leukemia cells (THP-1) were cultured and differentiated, and the miRNA-451a overexpression cell model was constructed by cell transfection technology, the cells were infected with H37Rv, qRT-PCR verified the gene expression level, and the protein expression level of was verified by Western blotting. The clearance ability of macrophages against H37Rv was determined by colony forming unit (CFU) assay. Results: (1) The relative expression levels of miRNA-451a in the secondary pulmonary tuberculosis patients, HDPTB patients, and healthy controls were 24.177 (5.150, 46.066), 81.742 (29.003, 117.388), and 77.762 (54.422, 134.633) respectively, with statistically significant differences (H=19.040, P<0.001); the relative expression levels of MIF were 0.306 (0.168, 0.795), 0.189 (0.073, 0.443), and 0.025 (0.012, 0.085) respectively, with statistically significant differences (H=35.967, P<0.001). (2) The relative expression level of MIF in the miRNA-451a overexpressed THP-1 cell model (0.442±0.019) was lower than that in the negative control group (1.477±0.190), with statistically significant differences (t=-9.384, P<0.001); 24 hours after H37Rv infection, the total intracellular bacterial survival rate in the miRNA-451a overexpression cell group (42.55%, 40/94) was higher than that in the negative control group (7.24%, 21/290) with statistically significant differences (χ²=66.247, P<0.001). Conclusion: miRNA-451a is involved in the pathogenesis of HDPTB by regulating the expression of MIF and then affecting the survival of bacteria in macrophages.

Key words: Tuberculosis, pulmonary, MicroRNAs, Macrophage migration-inhibitory factors