The inter-talk between Mycobacterium tuberculosis and the epigenetic mechanisms

The occurrence rate of Haarlem and Beijing genotypes among Middle Eastern isolates of multi drug resistant Mycobacterium tuberculosis: A systematic review and meta-analysis

Antibiotic resistance is a serious problem that poses a major challenge to tuberculosis control worldwide. Many developing countries still struggle with this infection in term of various aspects as it remains a major health concern. A number of developing countries are located in the Middle East, one of the world's most important regions. The control of this infection remains largely suboptimal despite intensive research in the field, and the mechanisms that lead to its progression have not yet been fully understood. Therefore, TB control must be amended through the identification of new strategies. For this reason, monitoring genetic characterizations of TB strains by molecular typing methods in different geographical regions can be important to setting local programs and global strategies to control TB infection. It is important to know the genotype of Mycobacterium tuberculosis strains to evaluate the occurrence of outbreaks and the transmission of this disease. Beijing and Haarlem genotypes are the most prevalent and, in these families, there is greater association with drug resistance, resulting in more severe forms of TB and higher levels of treatment failure than in other families. The current study is planned to systematically conduct a review using a meta-analysis to show the prevalence of Beijing and Haarlem genotypes in the Middle Eastern MDR-TB cases. M. tuberculosis strains pose particular epidemiological and clinical concerns as they can endanger tuberculosis control programs.

Tuberculosis and lung cancer: metabolic pathways play a key role

Despite the fact that some cases of tuberculosis (TB) are undiagnosed and untreated, it remains a serious global public health issue. In the diagnosis, treatment, and control of latent and active TB, there may be a lack of effectiveness. An understanding of metabolic pathways can be fundamental to treat latent TB infection and active TB disease. Rather than targeting Mycobacterium tuberculosis, the control strategies aim to strengthen host responses to infection and reduce chronic inflammation by effectively enhancing host resistance to infection. The pathogenesis and progression of TB are linked to several metabolites and metabolic pathways, and they are potential targets for host-directed therapies. Additionally, metabolic pathways can contribute to the progression of lung cancer in patients with latent or active TB. A comprehensive metabolic pathway analysis is conducted to highlight lung cancer development in latent and active TB. The current study aimed to emphasize the association between metabolic pathways of tumor development in patients with latent and active TB. Health control programs around the world are compromised by TB and lung cancer due to their special epidemiological and clinical characteristics. Therefore, presenting the importance of lung cancer progression through metabolic pathways occurring upon TB infection can open new doors to improving control of TB infection and active TB disease while stressing that further evaluations are required to uncover this correlation.

Epigenetic orchestration of host immune defences by Mycobacterium tuberculosis

Being among the top 10 causes of adult deaths, tuberculosis (TB) disease is considered a major global public health concern to address. The human tuberculosis pathogen, Mycobacterium tuberculosis (Mtb), is an extremely competent and well-versed pathogen that promotes pathogenesis by evading the host immune systems through numerous tactics. Investigations revealed that Mtb could evade the host defense mechanisms by reconfiguring the host gene transcription and causing epigenetic changes. Although results indicate the link between epigenetics and disease manifestation in other bacterial infections, little is known regarding the kinetics of the epigenetic alterations in mycobacterial infection. This literature review discusses the studies in Mtb-induced epigenetic alterations inside the host and its contribution in the host immune evasion strategies. It also discusses how the Mtb-induced alterations could be used as 'epibiomarkers' to diagnose TB. Additionally, this review also discusses therapeutic interventions to be enhanced through remodification by 'epidrugs'.

Association Between Promoter Methylation of Vitamin D Metabolic Pathway Genes and Tuberculosis and Diabetes Comorbidity in a Chinese Han Population: A Case-Control Study

Background

Deficiency vitamin D and hyperglycemia could be related to weakened innate immune response and aggravate the progression of tuberculosis (TB). This study hypothesized that DNA promoter methylation of the pivotal genes in the vitamin D metabolic pathway might be related to diabetes and tuberculosis co-morbidity (TB-DM) susceptibility.

Methods

A total of 50 TB-DM and 50 healthy subjects (HS) were included in the present study. Targeted bisulfite sequencing was applied to detect the methylation of the promoter regions of candidate genes in the vitamin D metabolic pathway (CYP24A1, CYP27B1, CYP2R1, DHCR7, and VDR) in whole blood.

Results

The overall methylation level of candidate genes in this study was lower in patients with TB-DM than HS, except for CYP2R1. The results of the ROC demonstrated the potential of CYP24A1, CYP27B1, DHCR7, and VDR promoter methylation as a biomarker for diagnosing TB-DM, with all the AUC above 0.7. In subgroup analysis, we found that lower circulating vitamin D is related to a low level of CYP24A1, CYP27B1, and DHCR7 promoter methylation in patients with TB-DM. With decreasing methylation level, risk of TB-DM was significantly increased (odds ratio, 95% CI 0.343, 0.144-0.821 for CYP24A1; 0.461, 0.275-0.773 for CYP27B1; 0.09, 0.015-0.530 for DHCR7; 0.006, 0.0003-0.115 for VDR). Besides, our results revealed that there was a significant correlation between DNA promoter methylation of selected genes in the vitamin D metabolic pathway and platelet indices in TB-DM. However, there was no correlation between DNA methylation of the four genes and fasting glucose and HbA1c.

Conclusion

Our results could suggest that the selected genes in the vitamin D metabolic pathway may be involved in the pathological process of TB-DM, but independent of the process of hyperglycemia to impaired immune responses to Mtb.

The landscape of histone modifications in epigenomics since 2020

Histone proteins are a primary component of chromatin; therefore, any modifications to their structure are anticipated to affect the behavior of our genetic material, which is manifested in the form of phenotypic changes at a molecular, cellular or organic level. The majority of histone modifications are of either methylation or acetylation type that regulate gene expression. Though, not all of these modifications are concerned with the direct regulation of gene transcription. Throughout its 13-year run, Epigenomics has never ceased to cover these most gripping epigenetic stories, a significant proportion of which is in the matter of histones and their modifications. As such, the current perspective piece is intended to highlight original histone-oriented contributions published in Epigenomics since 2020.

Tuberculosis conundrum - current and future scenarios: A proposed comprehensive approach combining laboratory, imaging, and computing advances

Tuberculosis (TB) remains a global threat, with the rise of multiple and extensively drug resistant TB posing additional challenges. The International health community has set various 5-yearly targets for TB elimination: mathematical modelling suggests that a 2050 target is feasible with a strategy combining better diagnostics, drugs, and vaccines to detect and treat both latent and active infection. The availability of rapid and highly sensitive diagnostic tools (Gene-Xpert, TB-Quick) will vastly facilitate population-level identification of TB (including rifampicin resistance and through it, multi-drug-resistant TB). Basic-research advances have illuminated molecular mechanisms in TB, including the protective role of Vitamin D. Also, Mycobacterium tuberculosis impairs the host immune response through epigenetic mechanisms (histone-binding modulation). Imaging will continue to be key, both for initial diagnosis and follow-up. We discuss advances in multiple imaging modalities to evaluate TB tissue changes, such as molecular imaging techniques (including pathogen-specific positron emission tomography imaging agents), non-invasive temporal monitoring, and computing enhancements to improve data acquisition and reduce scan times. Big data analysis and Artificial Intelligence (AI) algorithms, notably in the AI sub-field called “Deep Learning”, can potentially increase the speed and accuracy of diagnosis. Additionally, Federated learning makes multi-institutional/multi-city AI-based collaborations possible without sharing identifiable patient data. More powerful hardware designs - e.g., Edge and Quantum Computing- will facilitate the role of computing applications in TB. However, “Artificial Intelligence needs real Intelligence to guide it!” To have maximal impact, AI must use a holistic approach that incorporates time tested human wisdom gained over decades from the full gamut of TB, i.e., key imaging and clinical parameters, including prognostic indicators, plus bacterial and epidemiologic data. We propose a similar holistic approach at the level of national/international policy formulation and implementation, to enable effective culmination of TB’s endgame, summarizing it with the acronym “TB - REVISITED”.

Class Ⅰ histone deacetylase inhibitor regulate of Mycobacteria-Driven guanylate-binding protein 1 gene expression

Guanylate-binding proteins (GBPs) are a class of interferon (IFN)-stimulated genes with well-established activity against viruses, intracellular bacteria, and parasites. The effect of epigenetic modification on GBP activity upon Mycobacterium tuberculosis (Mtb) infection is poorly understood. In this study, we found that Mtb infection can significantly increase the expression of GBPs. Class Ⅰ histone deacetylase inhibitor (HDACi) MS-275 can selectively inhibit GBP1 expression, ultimately affecting the release of inflammatory cytokines IL-1β and suppressing Mtb intracellular survival. Moreover, interfering with GBP1 expression could reduce the production of IL-1β and the level of cleaved-caspase-3 in response to Mtb infection. GBP1 silencing did not affect Mtb survival. Besides, using the bisulfite sequencing PCR, we showed that the CpG site of the GBP1 promoter was hypermethylated, and the methylation status of the GBP1 promoter did not change significantly upon Mtb infection. Overall, this study sheds light on the role of GBP in Mtb infection and provides a link between epigenetics and GBP1 activity.

RNA Expression Analysis of Mycobacterial Methyltransferases Genes in Different Resistant Strains of Mycobacterium tuberculosis

BACKGROUND

Tuberculosis infection still represents a global health issue affecting patients worldwide. Strategies for its control may be not as effective as it should be, specifically in case of resistant strains of Mycobacterium tuberculosis (M.tb.) In this regard, the role of mycobacterial methyltransferases (MTases) in TB infection can be fundamental, though it has not been broadly deciphered.

METHODS

Five resistant isolates of M.tb were obtained. M.tb H37Rv (ATCC 27249) was used as a reference strain. Seven putative mycobacterial MTase genes (Rv0645c, Rv2966c, Rv1988, Rv1694, Rv3919c, Rv2756c, and Rv3263) and Rv1392 as SAM synthase were selected for analysis. PCR-sequencing and qRT-PCR were performed to compare mutations and expression levels of MTases in different strains. The 2-ΔΔCt method was employed to calculate the relative expression levels of these genes.

RESULTS

Only two mutations were found in isoniazid resistance (INHR) strain for Rv3919c (T to G in codon 341) and Rv1392 (G to A in codon 97) genes. Overexpression of Rv0645c, Rv2756c, Rv3263, and Rv2966c was detected in all sensitive and resistant isolates. However, Rv1988 and Rv3919c decreased and Rv1694 increased in the sensitive strains. The Rv1392 expression level also decreased in INHR isolate.

CONCLUSION

We found a correlation between mycobacterial MTases expression and resistance to antibiotics in M.tb strains. Some MTases undeniably are virulence factors that specifically hijack the host defense mechanism. Further evaluations are needed to explore the complete impact of mycobacterial MTases within specific strains of M.tb to introduce novel diagnosis and treatment strategies.

Relationship between DNA Methylation Profiles and Active Tuberculosis Development from Latent Infection: a Pilot Study in Nested Case-Control Design

Individuals with latent tuberculosis infection (LTBI) were regarded as an enormous reservoir of cases with active tuberculosis (TB). To strengthen LTBI management, biomarkers and tools are urgently required for identifying and ruling out active TB in a fast and effective way. Based on an open-label randomized controlled trial aiming to explore short-course LTBI treatment regimens, DNA methylation profiles were retrospectively detected to explore potential biomarkers, which could discriminate active TB from LTBI. The Infinium MethylationEPIC BeadChip array was used to analyze genomewide DNA methylation levels for 15 persons with LTBI who later developed active TB and for 15 LTBI controls who stayed healthy. The differentially methylated CpGs (dmCpGs) located in the promoter regions pre- and post-TB diagnosis were selected (P < 0.05 and |Δβ|>0.10) and evaluated by receiver operating characteristic (ROC) analysis. Eight dmCpGs were identified to be associated with TB occurrence; six were located in hypermethylated genes (cg02493602, cg02206980, cg02214623, cg12159502, cg14593639, and cg25764570), and two were located in hypomethylated genes (cg02781074 and cg12321798). ROC analysis indicated that the area under curve (AUC) of these eight dmCpGs ranged from 0.72 to 0.84. Given 90% sensitivity, the specificity was highest for cg14593639 at 66.67%. The combination analysis indicated that “cg02206980 + cg02214623 + cg12159502 + cg12321798” showed the best performance, with an AUC of 0.88 (95% confidence interval [CI]: 0.72, 0.97), a sensitivity of 93.33% (95% CI: 70.18%, 99.66%), and a specificity of 86.67% (95% CI: 62.12%, 97.63%). Our preliminary results indicate the potential value of the DNA methylation level as a diagnostic biomarker for discriminating active disease in LTBI testing. This finding requires further verification in independent populations with large sample sizes.

IMPORTANCE Approximately a quarter of the world population had been infected with Mycobacterium tuberculosis, and about 5 to 10% of these individuals might develop active disease in their lifetimes. As a critical component of the “end TB strategies,” preventive treatment was shown to protect 60 to 90% of high-risk LTBIs from developing active disease. Developing new TB screening tools based on blood-based biomarkers, which could identify and rule out active TB from LTBI, are prerequisite before initialing intervention. We tried to explore potential DNA methylation diagnostic biomarkers through retrospectively detected DNA methylation profiles pre- and post-TB diagnosis. Eight dmCpGs were identified, and the combination of “cg02206980 + cg02214623 + cg12159502 + cg12321798” showed a sensitivity of 93.33% and a specificity of 86.67%. The preliminary results provided new insight into detecting the DNA methylation level as a potential tool to distinguish TB from LTBI.

Surveying the Epigenetic Landscape of Tuberculosis in Alveolar Macrophages

Tuberculosis (TB) remains the leading cause of bacterial disease-related death and is among the top 10 overall causes of death worldwide. The complex nature of this infectious lung disease has proven difficult to treat, and significant research efforts are now evaluating the feasibility of host-directed, adjunctive therapies. An attractive approach in host-directed therapy targets host epigenetics, or gene regulation, to redirect the immune response in a host-beneficial manner. Substantial evidence exists demonstrating that host epigenetics are dysregulated during TB and that epigenetic-based therapies may be highly effective to treat TB. However, the caveat is that much of the knowledge that exists on the modulation of the host epigenome during TB has been gained using in vitro, small-animal, or blood-derived cell models, which do not accurately reflect the pulmonary nature of the disease. In humans, the first and major target cells of Mycobacterium tuberculosis are alveolar macrophages (AM). As such, their response to infection and treatment is clinically relevant and ultimately drives the outcome of disease. In this review, we compare the fundamental differences between AM and circulating monocyte-derived macrophages in the context of TB and summarize the recent advances in elucidating the epigenomes of these cells, including changes to the transcriptome, DNA methylome, and chromatin architecture. We will also discuss trained immunity in AM as a new and emerging field in TB research and provide some perspectives for the translational potential of targeting host epigenetics as an alternative TB therapy.

Comparative transcriptomic analysis of THP-1-derived macrophages infected with Mycobacterium tuberculosis H37Rv, H37Ra and BCG

Tuberculosis (TB) remains a worldwide healthcare concern, and the exploration of the host‐pathogen interaction is essential to develop therapeutic modalities and strategies to control Mycobacterium tuberculosis (M.tb). In this study, RNA sequencing (transcriptome sequencing) was employed to investigate the global transcriptome changes in the macrophages during the different strains of M.tb infection. THP‐1 cells derived from macrophages were exposed to the virulent M.tb strain H37Rv (Rv) or the avirulent M.tb strain H37Ra (Ra), and the M.tb BCG vaccine strain was used as a control. The cDNA libraries were prepared from M.tb‐infected macrophages and then sequenced. To assess the transcriptional differences between the expressed genes, the bioinformatics analysis was performed using a standard pipeline of quality control, reference mapping, differential expression analysis, protein‐protein interaction (PPI) networks, gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis. Q‐PCR and Western blot assays were also performed to validate the data. Our findings indicated that, when compared to BCG or M.tb H37Ra infection, the transcriptome analysis identified 66 differentially expressed genes in the M.tb H37Rv‐infected macrophages, out of which 36 genes were up‐regulated, and 30 genes were down‐regulated. The up‐regulated genes were associated with immune response regulation, chemokine secretion, and leucocyte chemotaxis. In contrast, the down‐regulated genes were associated with amino acid biosynthetic and energy metabolism, connective tissue development and extracellular matrix organization. The Q‐PCR and Western blot assays confirmed increased expression of pro‐inflammatory factors, altered energy metabolic processes, enhanced activation of pro‐inflammatory signalling pathways and increased pyroptosis in H37Rv‐infected macrophage. Overall, our RNA sequencing‐based transcriptome study successfully identified a comprehensive, in‐depth gene expression/regulation profile in M.tb‐infected macrophages. The results demonstrated that virulent M.tb strain H37Rv infection triggers a more severe inflammatory immune response associated with increased tissue damage, which helps in understanding the host‐pathogen interaction dynamics and pathogenesis features in different strains of M.tb infection.

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.

Methylome-wide Analysis Reveals Epigenetic Marks Associated With Resistance to Tuberculosis in Human Immunodeficiency Virus-Infected Individuals From East Africa

BACKGROUND

Tuberculosis (TB) is the most deadly infectious disease globally and is highly prevalent in the developing world. For individuals infected with both Mycobacterium tuberculosis (Mtb) and human immunodeficiency virus (HIV), the risk of active TB is 10% or more annually. Previously, we identified in a genome-wide association study (GWAS) a region on chromosome 5 associated with resistance to TB, which included epigenetic marks that could influence gene regulation. We hypothesized that HIV-infected individuals exposed to Mtb who remain disease free carry epigenetic changes that strongly protect them from active TB.

METHODS

We conducted a methylome-wide study in HIV-infected, TB-exposed cohorts from Uganda and Tanzania and integrated data from our GWAS.

RESULTS

We identified 3 regions of interest that included markers that were differentially methylated between TB cases and controls with latent TB infection: chromosome 1 (RNF220, P = 4 × 10-5), chromosome 2 (between COPS8 and COL6A3, P = 2.7 × 10-5), and chromosome 5 (CEP72, P = 1.3 × 10-5). These methylation results co-localized with associated single-nucleotide polymorphisms (SNPs), methylation QTLs, and methylation × SNP interaction effects. These markers were in regions with regulatory markers for cells involved in TB immunity and/or lung.

CONCLUSIONS

Epigenetic regulation is a potential biologic factor underlying resistance to TB in immunocompromised individuals that can act in conjunction with genetic variants.

Rv0802c is an acyltransferase that succinylates and acetylates Mycobacterium tuberculosis nucleoid-associated protein HU

Among the nucleoid-associated proteins (NAPs), HU is the most conserved in eubacteria, engaged in overall chromosome organization and regulation of gene expression. Unlike other bacteria, HU from Mycobacterium tuberculosis (MtHU), has a long carboxyl terminal domain enriched in basic amino acids, resembling eukaryotic histone N-terminal tails. As with histones, MtHU undergoes post-translational modifications and we have previously identified interacting kinases, methyltransferases, an acetyltransferase and a deacetylase. Here we show that Rv0802c interacts and succinylates MtHU. Although categorized as a succinyltransferase, we show that this GNAT superfamily member can catalyse both succinylation and acetylation of MtHU with comparable kinetic parameters. Like acetylation of MtHU, succinylation of MtHU caused reduced interaction of the NAP with DNA, determined by electrophoretic mobility shift assay and surface plasmon resonance. However, in vivo expression of Rv0802c did not significantly alter the nucleoid architecture. Although such succinylation of NAPs is rare, these modifications of the archetypal NAP may provide avenues to the organism to compensate for the underrepresentation of NAPs in its genome to control the dynamics of nucleoid architecture and cellular functions.

Key Macrophage Responses to Infection With Mycobacterium tuberculosis Are Co-Regulated by microRNAs and DNA Methylation

Tuberculosis (TB) is the leading cause of death from infection with a single bacterial pathogen. Host macrophages are the primary cell type infected with Mycobacterium tuberculosis (Mtb), the organism that causes TB. Macrophage response pathways are regulated by various factors, including microRNAs (miRNAs) and epigenetic changes that can shape the outcome of infection. Although dysregulation of both miRNAs and DNA methylation have been studied in the context of Mtb infection, studies have not yet investigated how these two processes may jointly co-regulate critical anti-TB pathways in primary human macrophages. In the current study, we integrated genome-wide analyses of miRNA abundance and DNA methylation status with mRNA transcriptomics in Mtb-infected primary human macrophages to decipher which macrophage functions may be subject to control by these two types of regulation. Using in vitro macrophage infection models and next generation sequencing, we found that miRNAs and methylation changes co-regulate important macrophage response processes, including immune cell activation, macrophage metabolism, and AMPK pathway signaling.

Perspectives for systems biology in the management of tuberculosis

Standardised management of tuberculosis may soon be replaced by individualised, precision medicine-guided therapies informed with knowledge provided by the field of systems biology. Systems biology is a rapidly expanding field of computational and mathematical analysis and modelling of complex biological systems that can provide insights into mechanisms underlying tuberculosis, identify novel biomarkers, and help to optimise prevention, diagnosis and treatment of disease. These advances are critically important in the context of the evolving epidemic of drug-resistant tuberculosis. Here, we review the available evidence on the role of systems biology approaches - human and mycobacterial genomics and transcriptomics, proteomics, lipidomics/metabolomics, immunophenotyping, systems pharmacology and gut microbiomes - in the management of tuberculosis including prediction of risk for disease progression, severity of mycobacterial virulence and drug resistance, adverse events, comorbidities, response to therapy and treatment outcomes. Application of the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) approach demonstrated that at present most of the studies provide "very low" certainty of evidence for answering clinically relevant questions. Further studies in large prospective cohorts of patients, including randomised clinical trials, are necessary to assess the applicability of the findings in tuberculosis prevention and more efficient clinical management of patients.