Circ_0001490/miR-579-3p/FSTL1 axis modulates the survival of mycobacteria and the viability, apoptosis and inflammatory response in Mycobacterium tuberculosis-infected macrophages
Introduction
Tuberculosis (TB) is a common systemic infectious disease, and is mainly caused by the infection of Mycobacterium tuberculosis (M.tb) [1]. M.tb acts as the intracellular pathogen to infect host macrophages [2]. In turn, macrophages play a crucial role in suppressing the survival and replication of M.tb by initiating innate immune responses [3,4]. However, M.tb can still evade from the defense of macrophages [5]. Illustrating macrophages-M.tb interactions is vital to find novel effective strategy for TB therapy.
Circular RNAs (circRNAs) are a special class of non-coding RNA molecules without 5′ or 3′ end, and circRNAs have been identified to be diagnostic bio-markers for TB. For instance, circ_0001953 and circ_0009024 are reported to be markedly up-regulated in the plasma of active TB patients, and the levels of circ_0001953 and circ_0009024 in plasma are positively correlated with TB severity [6]. Huang et al. found that circ_0001204 and circ_0001747 might be novel plasma diagnostic markers for active TB [7]. Luo et al. found that circ_0001380 level is decreased in the blood samples of active pulmonary TB patients, and it might be a diagnostic marker for active pulmonary TB patients [8]. However, the biological significance underlying the dysregulation of circRNAs in TB is largely unknown. Circ_0001490 is reported to be notably down-regulated in TB patients [6]. Circ_0001490 is generated from the back-splicing of its host gene kinesin family member 2A (KIF2A). Here, we analyzed function of circ_0001490 in TB and its associated molecular mechanism.
CircRNAs serve as molecular sponges for microRNAs (miRNAs) to regulate cell biological behaviors [9]. Accumulating evidence have demonstrated that miRNAs are important regulators in TB progression. For example, miR-155 is reported to regulate immune response to the infection of mycobacteria by regulating cellular reprogramming process [10]. miR-140 is reported to facilitate the survival of M.tb pathogen and decrease the release of inflammation-associated cytokines in macrophages partly by targeting TRAF6 [11]. miR-579-3p was one of the candidate targets of circ_0001490 via the prediction of circinteractome database. miR-579 has been reported to promote the death of M.tb-infected macrophages [12]. In this article, the functional correlation between miR-579-3p and circ_0001490 was explored in TB progression.
miRNAs post-transcriptionally regulate the expression of target messenger RNAs (mRNAs) via binding to their 3′ untranslated region (3′UTR) [13]. Based on the prediction of StarBase bioinformatics database, follistatin-like protein 1 (FSTL1) was a candidate target of miR-579-3p. FSTL1 is reported to induce the release of macrophages- and fibroblasts-derived inflammatory cytokines [14], demonstrating that FSTL1 plays a pro-inflammatory role. Zhang et al. found that miR-32-5p facilitates the survival of M.tb pathogen and restrains the release of inflammatory factors in macrophages, and FSTL1 overexpression reverses miR-32-5p-mediated effects [15]. We tested the interaction between miR-579-3p and FSTL1 and further explored the working mechanism of FSTL1 in THP-1 macrophages infected with M.tb pathogen.
In this study, we first analyzed the expression of circ_0001490 in the serum samples of TB patients and normal volunteers, and we found that circ_0001490 was markedly down-regulated in TB patients. To uncover the role of circ_0001490 in TB pathology, THP-1 macrophages were infected with M.tb to establish TB model in vitro. Bioinformatics analysis and a series of functional experiments were then conducted to explore the working mechanism of circ_0001490 in TB progression.
Section snippets
Clinical samples
A total of 30 TB patients and 23 normal volunteers were recruited at Jiangxi Chest Hospital. The diagnosis of TB patients (n = 30) was based on sputum smear examination using Ziehl-neelsen acid fast staining and clinical symptoms. TB patients were free of immunodeficiency disease and other pulmonary diseases. Normal volunteers (n = 23) without bacteriological or clinical evidence of TB were enrolled in this study. A volume of 5 mL peripheral blood samples from TB patients who had not received
Circ_0001490 expression is decreased in TB patients and M.tb-infected THP-1 macrophages
We first measured the level of circ_0001490 in the serum samples of normal volunteers (n = 23) and TB patients (n = 30), and the RT-qPCR data uncovered that circ_0001490 level was down-regulated in TB patients compared with normal volunteers (Fig. 1A). THP-1 macrophages are widely utilized as the in vitro model to analyze the interaction between the host and pathogen during M.tb infection [17]. We measured the level of circ_0001490 in THP-1 macrophages infected with M.tb at different MOIs via
Discussion
Accumulating studies have demonstrated that circRNAs play important roles in TB pathology [8,20,21]. In our study, we found that circ_0001490 was down-regulated in serum samples of TB patients compared with that in healthy volunteers. Also, M.tb infection reduced circ_0001490 expression in THP-1 macrophages in a dose-dependent manner. Through gain-of-function experiments, we found that circ_0001490 overexpression suppressed M.tb survival and elevated the viability and inflammatory response of
Author contribution
Qun Deng had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis. Study concept and design: Qun Deng, Jian Huang, Jinjin Yan; acquisition of data: Erning Mao, HuiJuan Chen, Caiwen Wang; critical revision of the manuscript for important intellectual content: Qun Deng; administrative, technical or material support: Qun Deng, Jian Huang, Jinjin Yan; study supervision: Qun Deng.
Disclosure of interest
The authors declare that they have no conflicts of interest.
Funding
None.
Availability of data and materials
Please contact the correspondence author for the data request.
Ethics approval and consent participate
Written informed consent was obtained from patients with approval by the Institutional Review Board in Jiangxi Chest Hospital.
Consent for publication
Not applicable.
Acknowledgment
None.
References (26)
- et al.
The epidemiology, pathogenesis, transmission, diagnosis, and management of multidrug-resistant, extensively drug-resistant, and incurable tuberculosis
Lancet Res Med
(2017) - et al.
microRNA-579 upregulation mediates death of human macrophages with mycobacterium tuberculosis infection
Biochem Biophys Res Commun
(2019) - et al.
TLR-4/miRNA-32-5p/FSTL1 signaling regulates mycobacterial survival and inflammatory responses in Mycobacterium tuberculosis-infected macrophages
Exp Cell Res
(2017) - et al.
The circular RNA of peripheral blood mononuclear cells: hsa_circ_0005836 as a new diagnostic biomarker and therapeutic target of active pulmonary tuberculosis
Mol Immunol
(2017) Mycobacterium tuberculosis: here today, and here tomorrow
Nat Rev Mol Cell Biol
(2001)- et al.
Characteristic pro-inflammatory cytokines and host defence cathelicidin peptide produced by human monocyte-derived macrophages infected with Neospora caninum
Parasitology
(2018) - et al.
PKC δ gene can induce macrophages to release inflammatory factors against Mycobacterium tuberculosis infection
Eur Rev Med Pharmacol Sci
(2018) - et al.
Mycobacterium tuberculosis and macrophage nuclear receptors: what we do and don't know
Tuberculosis
(2019) - et al.
Plasma circular RNAs hsa_circ_0001953 and hsa_circ_0009024 as diagnostic biomarkers for active tuberculosis
Front Microbiol
(2010) - et al.
Circulating circular RNAs hsa_circ_0001204 and hsa_circ_0001747 act as diagnostic biomarkers for active tuberculosis detection
Int J Clin Exp Pathol
(2018)