RESUMO
The roles and characteristics of low-density granulocytes (LDGs) have recently attracted attention; however, the mechanism of the formation of LDGs is yet unclear. In one of our previous studies, the frequency of LDGs was significantly elevated in the peripheral blood of tuberculosis patients, and in situ activation contributed to the generation of LDGs upon Mycobacterium tuberculosis infection. However, the underlying molecular mechanisms are yet to be elucidated. In the present study, the release of neutrophil extracellular traps (NETs) and the levels of ROS were regulated before the normal-density granulocytes (NDGs) to be infected with M. tuberculosis, and the conversion of NDGs to LDGs was monitored subsequently as well. The results showed that tuberculosis-related LDGs spontaneously released high levels of NETs. Promoting the release of NETs led to increase in the conversion of NDGs to LDGs in M. tuberculosis infection, while inhibiting the release of NETs suppressed this conversion after the infection. The M. tuberculosis infection significantly increased the ROS levels in neutrophils and the conversion of NDGs to LDGs. Scavenging ROS or blocking the ROS generation of M. tuberculosis-infected NDGs significantly suppressed the release of NETs and blocked the generation of LDGs. Moreover, inhibiting the formation of NETs without affecting the levels of ROS significantly decreased the conversion of NDGs to LDGs after M. tuberculosis infection. Overall, this study demonstrated that M. tuberculosis could induce the generation of LDGs by promoting the release of NET via ROS pathway.
RESUMO
BACKGROUND/AIMS: Dysregulated expression of circular RNAs (circRNAs) was demonstrated to be implicated in many diseases. Here, we aimed to determine circRNA profile in peripheral blood mononuclear cells (PBMCs) from active tuberculosis (TB) patients to identify novel biomarkers for TB. METHODS: Expression profile of circRNAs in PBMCs from 3 active pulmonary TB patients and 3 healthy controls were analyzed by microarray assay. Six circRNAs were selected for validation using real time-quantitative PCR (qRT-PCR) in 40 TB patients and 40 control subjects. Receiver operating characteristic (ROC) curve was constructed to evaluate their values in TB diagnosis. Hsa_circRNA_001937 was chosen for further evaluation in an independent cohort consisting of 115 TB, 40 pneumonia, 40 COPD, 40 lung cancer patients and 90 control subjects. An eight-month follow up was performed in 20 newly diagnosed TB patients to investigate the expression change of hsa_circRNA_001937 after chemotherapy. RESULTS: We revealed and confirmed that a number of circRNAs were dysregulated in TB patients. Of the six studied physio circRNAs, the levels of hsa_circRNA_001937, hsa_circRNA_009024 and hsa_ circRNA_005086 were significantly elevated and hsa_circRNA_102101, hsa_circRNA_104964 and hsa_circRNA_104296 were significantly reduced in PBMCs from TB patients as compared to healthy controls. ROC curve analysis suggested that hsa_circRNA_001937 has the largest area under the curve (AUC = 0.873, P<0.001). Hsa_circRNA_001937 was significantly increased in patients with TB compared with patients with pneumonia, COPD and lung cancer. Hsa_ circRNA_001937 was correlated with TB severity (r = 0.4053, P = 0.010) and its expression significantly decreased after treatment. CONCLUSION: This study identified a set of deregulated circRNAs in active TB PBMCs, our data also suggest that hsa_circRNA_001937 can be used as a potential diagnostic biomarker of TB.
