Sputum and serum microRNA-144 levels in patients with tuberculosis before and after treatment

MicroRNA-144-3p Inhibits Host Lipid Catabolism and Autophagy by Targeting PPARα and ABCA1 During Mycobacterium Tuberculosis Infection

MicroRNA-mediated metabolic reprogramming recently has been identified as an important strategy for Mycobacterium tuberculosis (Mtb) to evade host immune responses. However, it is unknown what role microRNA-144-3p (miR-144-3p) plays in cellular metabolism during Mtb infection. Here, we report the meaning of miR-144-3p-mediated lipid accumulation for Mtb-macrophage interplay. Mtb infection was shown to upregulate the expression of miR-144-3p in macrophages. By targeting peroxisome proliferator-activated receptor α (PPARα) and ATP-binding cassette transporter A1 (ABCA1), miR-144-3p overexpression promoted lipid accumulation and bacterial survival in Mtb-infected macrophages, while miR-144-3p inhibition had the opposite effect. Furthermore, reprogramming of host lipid metabolism by miR-144-3p suppressed autophagy in response to Mtb infection. Our findings uncover that miR-144-3p regulates host metabolism and immune responses to Mtb by targeting PPARα and ABCA1, suggesting a potential host-directed tuberculosis therapy by targeting the interface of miRNA and lipid metabolism.

A systematic review and meta-analysis of circulating serum and plasma microRNAs in TB diagnosis

BACKGROUND

Tuberculosis (TB) ranks as the second leading cause of death globally among all infectious diseases. This problem is likely due to the lack of biomarkers to differentiate the heterogeneous spectrum of infection. Therefore, the first step in solving this problem is to identify biomarkers to distinguish the different disease states of an individual and treat them accordingly. Circulating microRNA (miRNA) biomarkers are promising candidates for various diseases. In fact, we are yet to conceptualize how miRNA expression influences and predicts TB disease outcomes. Thus, this systematic review and meta-analysis aimed to assess the diagnostic efficacy of circulating miRNAs in Latent TB (LTB) and Active Pulmonary TB (PTB).

METHODS

Literature published between 2012 and 2021 was retrieved from PubMed, Web of Science, Cochrane, Scopus, Embase, and Google Scholar. Articles were screened based on inclusion and exclusion criteria, and their quality was assessed using the QUADAS-2 tool. Funnel plots and forest plots were generated to assess the likelihood of study bias and heterogeneity, respectively.

RESULTS

After the screening process, seven articles were selected for qualitative analysis. The study groups, which consisted of Healthy Control (HC) vs. TB and LTB vs. TB, exhibited an overall sensitivity of 81.9% (95% CI: 74.2, 87.7) and specificity of 68.3% (95% CI: 57.8, 77.2), respectively. However, our meta-analysis results highlighted two potentially valuable miRNA candidates, miR-197 and miR-144, for discriminating TB from HC. The miRNA signature model (miR197-3p, miR-let-7e-5p, and miR-223-3p) has also been shown to diagnose DR-TB with a sensitivity of 100%, but with a compromised specificity of only 75%.

CONCLUSION

miRNA biomarkers show a promising future for TB diagnostics. Further multicentre studies without biases are required to identify clinically valid biomarkers for different states of the TB disease spectrum.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO (CRD42022302729).

Diagnostic value of microRNAs in active tuberculosis based on quantitative and enrichment analyses

BACKGROUND

Tuberculosis (TB) infection remains a crucial global health challenge, with active tuberculosis (ATB) representing main infection source. MicroRNA (miRNA) has emerged as a potential diagnostic tool in this context. This study aims to identify candidate miRNAs for ATB diagnosis and explore their possible mechanisms.

METHODS

Differentially expressed miRNAs in ATB were summarized in qualitative analysis. The diagnostic values of miRNAs for ATB subtypes were assessed by overall sensitivity, specificity, and area under the curve. Additionally, we conducted enrichment analysis on miRNAs and target genes.

RESULTS

Over 100 differentially expressed miRNAs were identified, with miR-29 family being the most extensively studied. The miR-29 family demonstrated sensitivity, specificity, and area under the curve of 80 %, 80 % and 0.86 respectively for active pulmonary TB (PTB). The differentially expressed miR-29-target genes in PTB were enriched in immune-related pathways.

CONCLUSIONS

The miR-29 family exhibits good diagnostic value for active PTB and shows association with immune process.

The Effects of Respiratory Training Combined with Limb Exercise on Pulmonary Function and Quality of Life in Patients with Bronchiectasis

Objective

To investigate the effects of respiratory rehabilitation training combined with limb rehabilitation on sputum clearance and quality of life in patients with bronchiectasis.

Methods

A retrospective analysis of 86 patients with bronchiectasis was divided into an intervention group and an observation group, with 43 cases in each group. All patients were above 18 years of age with no history of relevant drug allergies. Patients in the observation group were treated with conventional drugs, and those in the intervention group were given respiratory rehabilitation training and limb rehabilitation on this basis. After three months of treatment, the indexes of sputum discharge, sputum traits, lung function, and the 6-minute walk distance (6MWD) were compared and quality of life and survival skills were assessed using the Barthel index and a quality-of-life comprehensive assessment questionnaire (GQOLI-74).

Results

The percentage of patients with mild Barthel index in the intervention group was higher than that in the observation group, and the difference between the groups was statistically significant (P < 0.05). After treatment, the scores of life quality and the lung function in the intervention group were higher than those in the observation group (both P < 0.05). After three months of treatment, the sputum volume and sputum viscosity scores of the two groups were higher than those before treatment (P < 0.05).

Conclusion

Respiratory rehabilitation training with limb exercise rehabilitation can effectively improve the sputum clearance rate, lung function, and quality of life of patients with bronchiectasis and is thus worthy of clinical promotion and application.

p50-associated Cyclooxygenase-2 Extragenic RNA (PACER) and Long Non-coding RNA 13 (LNC13) as potential biomarkers for monitoring tuberculosis treatment

Gaps in early and accurate diagnosis, effective drug control, and treatment monitoring are hindering the global eradication effort of tuberculosis. This infectious disease has become the deadliest worldwide before the outbreak of Covid-19. The search for new molecular biomarkers of tuberculosis will help to reverse this trend. Long non-coding RNAs (lncRNAs) have emerged as important regulators of the host immune response to infection, hence their link with the etiology and diagnosis of tuberculosis has attracted some attention from the research community. However, very little is known about their potential for the monitoring of tuberculosis treatment. This study aimed at assessing the potential of two lncRNAs: p50-associated Cyclooxygenase-2 Extragenic RNA (PACER) and Long Non-coding RNA 13 (LNC13) in the monitoring of tuberculosis treatment. This was a cross-sectional study carried out in Douala, Cameroon from December 2020 to August 2021. A quantitative real-time polymerase chain reaction followed by Cq analysis using the Livak method were performed to measure the relative expression levels of PACER and LNC13 in whole blood of healthy controls, patients with active pulmonary tuberculosis at the initiation of treatment, after two, five, and six months into treatment. Receiver Operating Characteristic curves analysis was used to assess the ability of targeted lncRNAs to discriminate among those groups. The study showed that the lncRNAs PACER and LNC13 were significantly upregulated in patients with active pulmonary tuberculosis at the initiation of treatment than in healthy controls. The expression levels of the two lncRNAs were significantly downregulated in patients during the treatment as compared to the active pulmonary tuberculosis patients. However, the expression levels of the lncRNAs PACER and LNC13 in whole blood of patients after six months of treatment were similar to those in healthy controls. Similarly, lncRNAs PACER and LNC13 showed very good performance in distinguishing between active tuberculosis patients and healthy controls as well as in differentiating between newly diagnosed active tuberculosis patients and those under treatment. Interestingly, those lncRNAs could not discriminate healthy controls from patients after six months of treatment. The lncRNAs PACER and LNC13 are therefore potential biomarkers for the monitoring of tuberculosis treatment.

Epigenetic code during mycobacterial infections: therapeutic implications for tuberculosis

Epigenetics involves changing the gene function without any change in the sequence of the genes. In the case of tuberculosis (TB) infections, the bacilli, Mycobacterium tuberculosis (M.tb), uses epigenetics as a tool to protect itself from the host immune system. TB is a deadly disease-causing maximum death per year due to a single infectious agent. In the case of TB, there is an urgent need for novel host-directed therapies which can effectively target the survival and long-term persistence of the bacteria without developing drug resistance in the bacterial strains while also reducing the duration and toxicity associated with the mainstream anti-TB drugs. Recent studies have suggested that TB infection has a significant effect on the host epigenome thereby manipulating the host immune response in the favor of the pathogen. M.tb alters the activation status of key genes involved in the immune response against TB to promote its survival and subvert the antibacterial strategies of the host. These changes are reversible and can be exploited to design very efficient host-directed therapies to fight against TB. This review has been written with the purpose of discussing the role of epigenetic changes in TB pathogenesis and the therapeutic approaches involving epigenetics, which can be utilized for targeting the pathogen.

The Role of microRNAs and Long Non-Coding RNAs in the Regulation of the Immune Response to Mycobacterium tuberculosis Infection

Non-coding RNAs have emerged as critical regulators of the immune response to infection. MicroRNAs (miRNAs) are small non-coding RNAs which regulate host defense mechanisms against viruses, bacteria and fungi. They are involved in the delicate interplay between Mycobacterium tuberculosis, the causative agent of tuberculosis (TB), and its host, which dictates the course of infection. Differential expression of miRNAs upon infection with M. tuberculosis, regulates host signaling pathways linked to inflammation, autophagy, apoptosis and polarization of macrophages. Experimental evidence suggests that virulent M. tuberculosis often utilize host miRNAs to promote pathogenicity by restricting host-mediated antibacterial signaling pathways. At the same time, host- induced miRNAs augment antibacterial processes such as autophagy, to limit bacterial proliferation. Targeting miRNAs is an emerging option for host-directed therapies. Recent studies have explored the role of long non-coding RNA (lncRNAs) in the regulation of the host response to mycobacterial infection. Among other functions, lncRNAs interact with chromatin remodelers to regulate gene expression and also function as miRNA sponges. In this review we attempt to summarize recent literature on how miRNAs and lncRNAs are differentially expressed during the course of M. tuberculosis infection, and how they influence the outcome of infection. We also discuss the potential use of non-coding RNAs as biomarkers of active and latent tuberculosis. Comprehensive understanding of the role of these non-coding RNAs is the first step towards developing RNA-based therapeutics and diagnostic tools for the treatment of TB.

Integrating serum microRNAs and electronic health records improved the diagnosis of tuberculosis

Background

To verify the differential expression of miR‐30c and miR‐142‐3p between tuberculosis patients and healthy controls and to investigate the performance of microRNA (miRNA) and subsequently models for the diagnosis of tuberculosis (TB).

Methods

We followed up 460 subjects suspected of TB, and finally enrolled 132 patients, including 60 TB patients, 24 non‐TB disease controls (TB‐DCs), and 48 healthy controls (HCs). The differential expression of miR‐30c and miR‐142‐3p in serum samples of the TB patients, TB‐DCs, and HCs were identified by reverse transcription–quantitative real‐time PCR. Diagnostic models were developed by analyzing the characteristics of miRNA and electronic health records (EHRs). These models evaluated by the area under the curves (AUC) and calibration curves were presented as nomograms.

Results

There were differential expression of miR‐30c and miR‐142‐3p between TB patients and HCs (p < 0.05). Individual miRNA has a limited diagnostic value for TB. However, diagnostic performance has been both significantly improved when we integrated miR‐142‐3p and ordinary EHRs to develop two models for the diagnosis of tuberculosis. The AUC of the model for distinguishing tuberculosis patients from healthy controls has increased from 0.75 (95% CI: 0.66–0.84) to 0.96 (95% CI: 0.92–0.99) and the model for distinguishing tuberculosis patients from non‐TB disease controls has increased from 0.67 (95% CI: 0.55–0.79) to 0.94 (95% CI: 0.89–0.99).

Conclusions

Integrating serum miR‐142‐3p and EHRs is a good strategy for improving TB diagnosis.

MiR-144-3p is associated with pathological inflammation in patients infected with Mycobacteroides abscessus

Infection with rapidly growing nontuberculous mycobacteria is emerging as a global health issue; however, key host factors remain elusive. Here, we investigated the characteristic immune profiles of peripheral blood mononuclear cells (PBMCs) from patients infected with Mycobacteroides abscessus subsp. abscessus (Mabc) and M. abscessus subsp. massiliense (Mmass). Using an integrated analysis of global mRNA and microRNA expression profiles, we found that several inflammatory cytokines/chemokines [interleukin (IL)-1β, IL-6, C-X-C motif chemokine ligand 2, and C-C motif chemokine ligand 2] and miR-144-3p were significantly upregulated in PBMCs from patients compared with those from healthy controls (HCs). Notably, there was a strong correlation between the expression levels of miR-144-3p and proinflammatory cytokines/chemokines. Similarly, upregulated expression of miR-144-3p and proinflammatory cytokines/chemokines was found in macrophages and lungs from mice after infection with Mabc and Mmass. We showed that the expression of negative regulators of inflammation (SARM1 and TNIP3) was significantly downregulated in PBMCs from the patients, although they were not putative targets of miR-144-3p. Furthermore, overexpression of miR-144-3p led to a marked increase in proinflammatory cytokines/chemokines and promoted bacterial growth in macrophages. Together, our results highlight the importance of miR-144-3p linking to pathological inflammation during M. abscessus infection.

MicroRNA-155 from sputum as noninvasive biomarker for diagnosis of active pulmonary tuberculosis

Objectives

Tuberculosis (TB), caused by Mycobacterium tuberculosis, is a widespread infectious disease around the world. Early diagnosis is always important in order to avoid spreading. At present, many studies have confirmed that microRNA (miRNA) could be a useful tool for diagnosis. This study aimed to evaluate whether miRNAs could be regarded as a noninvasive diagnosis biomarker from sputum for pulmonary tuberculosis (PTB).

Materials and Methods

The M. tuberculosis strain H37Rv was incubated and cultured with human macrophage line THP-1. The total RNA was extracted from the THP-1 cells for detection. Six increased expressions of miRNAs were selected by miRNA microarray chips and the miRNAs were confirmed by qRT-PCR in the M. tuberculosis infection cell model. At last, the efficiency of other methods was compared with using miRNA.

Results

Only miR-155 showed a better diagnostic value for PTB than the other five miRNAs to distinguish PTB from non-PTB, including pneumonia, lung cancer, and unexplained pulmonary nodules. Next, we detected and analyzed the results of 68 PTB patients and 122 non-PTB, the sensitivity and specificity of miR-155 detection was 94.1% and 87.7%, respectively. It was higher than sputum smear detection and anti-TB antibody detection. But slightly lower than ELISpot (97%, P=0.404). Interestingly, the ranking of sputum smear by Ziehl-Neelsen staining had positive correlation with the expression level of miR-155 in smear-positive sputum (R²=0.8443, P<0.05).

Conclusion

Our research suggested that miR-155 may be an efficiency biomarker for active PTB diagnosis and bacteria-loads evaluation.

Tuberculosis-Associated MicroRNAs: From Pathogenesis to Disease Biomarkers

Tuberculosis (TB) caused by Mycobacterium tuberculosis is one of the most lethal infectious diseases with estimates of approximately 1.4 million human deaths in 2018. M. tuberculosis has a well-established ability to circumvent the host immune system to ensure its intracellular survival and persistence in the host. Mechanisms include subversion of expression of key microRNAs (miRNAs) involved in the regulation of host innate and adaptive immune response against M. tuberculosis. Several studies have reported differential expression of miRNAs during active TB and latent tuberculosis infection (LTBI), suggesting their potential use as biomarkers of disease progression and response to anti-TB therapy. This review focused on the miRNAs involved in TB pathogenesis and on the mechanism through which miRNAs induced during TB modulate cell antimicrobial responses. An attentive study of the recent literature identifies a group of miRNAs, which are differentially expressed in active TB vs. LTBI or vs. treated TB and can be proposed as candidate biomarkers.

miRNA Expression Profiles and Potential as Biomarkers in Nontuberculous Mycobacterial Pulmonary Disease

Pulmonary disease (PD) due to nontuberculous mycobacteria (NTM) is increasing globally, but specific biomarkers for NTM-PD have not been established. As circulating miRNAs are promising biomarkers for various diseases, we investigated whether miRNAs have potential as NTM-PD biomarkers. Sera from 12 NTM-PD patients due to Mycobacterium avium, M. intracellulare, M. abscessus, or M. massiliense and three healthy controls were initially evaluated via small RNA sequencing. Multiple miRNAs showed significant differences in expression in patients compared to in healthy controls, with some expression differences unique to PD caused by a specific mycobacterial species. Notably, 14 miRNAs exhibited significant expression differences in PD associated with all four mycobacteria. Validation by quantitative reverse-transcription-PCR in an additional 40 patients with NTM-PD and 40 healthy controls confirmed that four differentially expressed miRNAs (hsa-miR-484, hsa-miR-584-5p, hsa-miR-625-3p, and hsa-miR-4732-5p) showed significantly higher serum expressions in NTM-PD patients than in controls. Receiver operating characteristic curve analysis of these four miRNAs supported the discriminative potential for NTM-PD and their combination provided an improved diagnostic value for NTM-PD. Furthermore, bioinformatics analysis revealed their 125 target genes, which were mostly associated with immune responses. Collectively, this study identified four miRNAs as potential biomarkers for NTM-PD and provided insight into NTM-PD pathophysiology.

Unraveling the Role of MicroRNAs in Mycobacterium tuberculosis Infection and Disease: Advances and Pitfalls

Tuberculosis (TB) is an infectious disease of extremely high epidemiological burden worldwide that is easily acquired through the inhalation of infected respiratory droplets. The complex pathogenesis of this infection spans from subjects never developing this disease despite intense exposure, to others in which immune containment fails catastrophically and severe or disseminated forms of disease ensue. In recent decades, microRNAs (miRNAs) have gained increasing attention due to their role as gene silencers and because of their altered expression in diverse human diseases, including some infections. Recent research regarding miRNAs and TB has revealed that the expression profile for particular miRNAs clearly changes upon Mycobacterium tuberculosis infection and also varies in the different stages of this disease. However, despite the growing number of studies-some of which have even proposed some miRNAs as potential biomarkers-methodological variations and key differences in relevant factors, such as sex and age, cell type analyzed, M. tuberculosis strain, and antimicrobial therapy status, strongly hinder the comparison of data. In this review, we summarize and discuss the literature and highlight the role of selected miRNAs that have specifically and more consistently been associated with M. tuberculosis infection, together with a discussion of the possible gene and immune regulation pathways involved.

Small RNA Profiles of Serum Exosomes Derived From Individuals With Latent and Active Tuberculosis

Tuberculosis (TB) has been the leading lethal infectious disease worldwide since 2014, and about one third of the world’s population has a latent TB infection (LTBI). This is largely attributed to the difficulties in diagnosis and treatment of TB and LTBI patients. Exosomes offer a new perspective on investigation of the process of TB infection. In this study, we performed small RNA sequencing to explore small RNA profiles of serum exosomes derived from LTBI and TB patients and healthy controls (HC). Our results revealed distinct miRNA profile of the exosomes in the three groups. We screened 250 differentially expressed miRNAs including 130 specifically expressed miRNAs. Some miRNAs were further validated to be specifically expressed in LTBI (hsa-let-7e-5p, hsa-let-7d-5p, hsa-miR-450a-5p, and hsa-miR-140-5p) and TB samples (hsa-miR-1246, hsa-miR-2110, hsa-miR-370-3P, hsa-miR-28-3p, and hsa-miR-193b-5p). Additionally, we demonstrated four expression panels in LTBI and TB groups, and six expression patterns among the three groups. These specifically expressed miRNAs and differentially expressed miRNAs in different panels and patterns provide potential biomarkers for detection/diagnosis of latent and active TB using exosomal miRNAs. Additionally, we also discovered plenty of small RNAs derived from genomic repetitive sequences, which might play roles in host immune responses along with Mtb infection progresses. Overall, our findings provide important reference and an improved understanding about miRNAs and repetitive region-derived small RNAs in exosomes during the Mtb infectious process, and facilitate the development of potential molecular targets for detection/diagnosis of latent and active tuberculosis.

Downregulation of miR-144 by triptolide enhanced p85α-PTEN complex formation causing S phase arrest of human nasopharyngeal carcinoma cells

Selective pharmacologic targeting of cell cycle regulators is a potent anti-cancer therapeutic strategy. Here, we show that caspase-3-mediated p21 cleavage involves p53 independent of triptolide (TPL)-induced S phase arrest in human type 1 nasopharyngeal carcinoma (NPC) cells. Coimmunoprecipitation studies demonstrated that TPL causes S phase cell cycle arrest by suppressing the formation of cyclin A-phosphor (p)-cyclin-dependent kinas 2 (CDK2) (Thr 39) complexes. Ectopic expression of constitutively active protein kinase B1 (Akt1) blocks the induction of S phase arrest and the suppression of cyclin A expression and CDK2 Thr 39 phosphorylation by TPL. Expression of the phosphomimetic mutant CDK2 (T39E) rescues the cells from TPL-induced S phase arrest, whereas phosphorylation-deficient CDK2 (T39A) expression regulates cell growth with significant S phase arrest and enhances TPL-triggered S phase arrest. Treatment with TPL induces an increase in the formation of complexes between unphosphorylated phosphatase and tensin homolog deleted from chromosome 10 (PTEN) and p85α in the plasma membrane. Decreased microRNA (miR)-144 expression and increased PTEN expression after TPL treatment were demonstrated, and TPL-enhanced p85α-PTEN complexes and inhibitory effects on Akt (Ser 473) phosphorylation and S phase arrest were suppressed by ectopic PTEN short hairpin RNA or miR-144 expression. Knockdown of endogenous miR-144 by miR-144 Trap upregulated PTEN expression and accordingly enhanced p85α-PTEN complex formation and S phase arrest. Collectively, the effect of TPL on S phase arrest in human NPC cells is likely to enhance the p85α-PTEN interaction in the plasma membrane by suppressing miR-144 expression, resulting in the attenuation of cyclin A-p-CDK2 (Thr 39) complex formation via Akt inactivation.

miRNAs in immune responses to Mycobacterium tuberculosis infection

Tuberculosis (TB) is one of the most fatal infectious diseases, affecting one third of the world's population. The causative agent, Mycobacterium tuberculosis (Mtb), has a well-established ability to circumvent the host's immune system for its long-term intracellular survival. MicroRNAs (miRNAs) are crucial post-transcriptional regulators of immune response. They act by negatively regulating the expression levels of important genes in both innate and adaptive immunity. It has been established in recent studies that the host immune response against Mtb is regulated by many miRNAs, most of which are induced by Mtb infection. Moreover, differential expression of miRNA in tuberculosis (TB) patients may help distinguish between TB patients and healthy individuals or latent TB. In this review, we present the recent advancements on the miRNA regulation of the host responses against Mtb infection, as well as the potential of miRNAs to as biomarkers for TB diagnosis.

miRNAs reshape immunity and inflammatory responses in bacterial infection

Pathogenic bacteria cause various infections worldwide, especially in immunocompromised and other susceptible individuals, and are also associated with high infant mortality rates in developing countries. MicroRNAs (miRNAs), small non-coding RNAs with evolutionarily conserved sequences, are expressed in various tissues and cells that play key part in various physiological and pathologic processes. Increasing evidence implies roles for miRNAs in bacterial infectious diseases by modulating inflammatory responses, cell penetration, tissue remodeling, and innate and adaptive immunity. This review highlights some recent intriguing findings, ranging from the correlation between aberrant expression of miRNAs with bacterial infection progression to their profound impact on host immune responses. Harnessing of dysregulated miRNAs in bacterial infection may be an approach to improving the diagnosis, prevention and therapy of infectious diseases.

Changes in production of tiny cellular RNAs in response to bacterial infection could guide the development of better diagnostics and therapies. MicroRNAs regulate other genes by binding to messenger RNA strands and controlling their translation into proteins. Xikun Zhou, Min Wu and colleagues of the University of North Dakota have now reviewed current knowledge about how microRNA levels shift during infection with various bacterial pathogens. These microRNAs can modulate the immune response as well as pathways that influence metabolic activity and cell survival. Increasing studies have indicated that shifts in microRNA levels in response to different infections could provide a potential bacterial ‘fingerprint’ for achieving accurate diagnosis. With deeper insight into how different microRNAs influence infection, it might one day day become possible to target these molecules with ‘antisense’ or ‘agonist’ drugs that modulate their activity.

miRNAs in Tuberculosis: New Avenues for Diagnosis and Host-Directed Therapy

Tuberculosis (TB) is one of the most fatal infectious diseases and a leading cause of mortality, with 95% of these deaths occurring in developing countries. The causative agent, Mycobacterium tuberculosis (Mtb), has a well-established ability to circumvent the host's immune system for its intracellular survival. microRNAs (miRNAs) are small, non-coding RNAs having an important function at the post-transcriptional level and are involved in shaping immunity by regulating the repertoire of genes expressed in immune cells. It has been established in recent studies that the innate immune response against TB is significantly regulated by miRNAs. Moreover, differential expression of miRNA in Mtb infection can reflect the disease progression and may help distinguish between active and latent TB infection (LTBI). These findings encouraged the application of miRNAs as potential biomarkers. Similarly, active participation of miRNAs in modulation of autophagy and apoptosis responses against Mtb opens an exciting avenue for the exploitation of miRNAs as host directed therapy (HDT) against TB. Nanoparticles mediated delivery of miRNAs to treat various diseases has been reported and this technology has a great potential to be used in TB. In reality, this exploitation of miRNAs as biomarkers and in HDT is still in its infancy stage, and more studies using animal models mimicking human TB are advocated to assess the role of miRNAs as biomarkers and therapeutic targets. In this review, we attempt to summarize the recent advancements in the role of miRNAs in TB as immune modulator, miRNAs' capability to distinguish between active and latent TB and, finally, usage of miRNAs as therapeutic targets against TB.

Screening and identification of four serum miRNAs as novel potential biomarkers for cured pulmonary tuberculosis

Rapid and efficient methods for the determination of cured pulmonary tuberculosis (TB) are lacking. We screened serum miRNAs using the Solexa sequencing method among untreated TB patients, two-month treated TB patients, cured TB patients, and healthy controls. A total of 100 differentially expressed miRNAs were identified in cured TB patients, including 37 up-regulated (fold change >1.50, P < 0.05) and 63 down-regulated (fold change <0.60, P < 0.05) miRNAs. Gene ontology (GO) enrichment analysis revealed that most of the predicted genes were present in the nucleus with a strong protein binding function. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis strongly suggested alterations in the metabolic pathways. Following quantitative real time chain reaction (qRT-PCR), significantly reduced expression levels of miR-21-5p (0.30, P < 0.001), miR-92a-3p (0.63, P < 0.001), and miR-148b-3p (0.17, P < 0.001) were found in the cured TB patients compared with the untreated TB patients, while significantly increased expression levels of miR-21-5p (2.09, P = 0.001), miR-92a-3p (1.40, P = 0.005), and miR-148b-3p (4.80, P = 0.003) were found in the untreated TB patients compared with the healthy controls. And significantly increased level of miR-125a-5p was found between two-month treated TB patients and untreated TB patients (1.81, P = 0.004). We established a cured TB model with 83.96% accuracy by four miRNAs (miR-21-5p, miR-92a-3p, miR-148b-3p, and miR-125a-5p), and also established a diagnostic model with 70.09% accuracy. Our study provides experimental data for establishing objective indicators of cured TB, and also provides a new experimental basis to understand the pathogenesis and prognosis of TB.

MicroRNA-144-3p inhibits autophagy activation and enhances Bacillus Calmette-Guérin infection by targeting ATG4a in RAW264.7 macrophage cells

MicroRNAs (miRNAs) are small noncoding nucleotides that play major roles in the response of host immune cells. Autophagy plays a key role in activating the antimicrobial host defense against Mycobacterium tuberculosis (M. tuberculosis). Whether miRNAs specifically influence the activation of macrophage autophagy during M. tuberculosis infection is largely unknown. In the present study, we demonstrate that Mycobacterium bovis Bacillus Calmette-Guérin (BCG) infection of macrophages leads to increased expression of miR-144-3p, which targets autophagy-related gene 4a (ATG4a), to inhibit autophagy activation and antimicrobial responses to BCG. Overexpression of miR-144-3p significantly decreased both mRNA and protein levels of ATG4a, inhibited the formation of autophagosomes in RAW264.7 cells and increased intracellular survival of BCG. However, transfection with miR-144-3p inhibitor led to an increase in ATG4a levels, accelerated the autophagic response in macrophages, and decreased BCG survival in macrophages. The experimental results of this study reveal a novel role of miR-144-3p in inhibiting autophagy activation by targeting ATG4a and enhancing BCG infection, and provide potential targets for developing improved treatment.

Levels of microRNA miR-16 and miR-155 are altered in serum of patients with tuberculosis and associate with responses to therapy

Identification of blood biomarkers that can be useful for predicting Mycobacterium tuberculosis (M.TB) infection, effect of therapy and Multi Drug Resistant (MDR) TB infected individuals is clinically useful for combating tuberculosis epidemic. In this study, we have evaluated the levels of selected miRNAs in serum of TB and MDR TB patients. In addition, we have studied their levels in serum of patients post-therapy. The levels of 4-miRNAs (miR-16, miR-29a, miR-125b and miR-155) were measured in 30 newly diagnosed TB patients, 19 Multi Drug Resistant (MDR) TB patients, 10 patients who completed TB therapy and were TB negative. 30 healthy individuals were recruited as controls. The levels of the miRNAs were estimated by qRT-PCR. Of the four miRNAs studied, the levels of miR-16 were significantly elevated and miR-155 were significantly reduced in serum of TB patients as compared to uninfected controls. The Receiver Operating Characteristic (ROC) curve of miR-16 and miR-155 exhibited a significant distinguishing efficiency with an AUC value of 1 (95% CI, 1 to 1) and 0.967 (95% CI, 0.92-1.04) respectively. Following the therapy, the levels of miR-16 and miR-155 returned to those observed in healthy subjects. In patients with MDR TB, miR-155 was lower as compared to healthy controls and TB treated group but higher as compared to TB naïve patients. miR-16 levels were lowest in serum of MDR TB patients compared to TB naïve, TB treated group and healthy controls. In conclusion, miR-16 and miR-155 in serum may act as surrogate biomarker for studying TB infection, progression of therapy and MDR TB.