Anti-tuberculous Effects of Statin Therapy: A Review of Literature

Effect of calcium-channel blockers on the risk of active tuberculosis and mortality: systematic review and meta-analysis

Introduction: Recent studies suggest that calcium channel blockers (CCBs) could reduce the risk of active tuberculosis and improve clinical outcomes. We aimed to synthesize the evidence regarding the effect of CCBs on the risk of developing active tuberculosis and mortality. Methods: We systematically searched for observational studies and clinical trials published in six databases until 31 August 2023, following a PECO/PICO strategy. Results: We included eight observational studies, 4,020,830 patients, among whom 241,761 had diabetes mellitus and 30,397 had active tuberculosis. According to our results, CCBs reduce the risk of developing active tuberculosis by 29% (RR 0.71; 95% CI 0.67-0.75) in patients with and without diabetes mellitus. However, CCBs do not show any benefit in terms of tuberculosis-related mortality (RR 1.00; 95% CI 0.98-1.02). For both outcomes, no statistical heterogeneity was found (I2 = 0, p > 0.10). This protective effect of CCBs on the risk of active tuberculosis remained independent of the type of patient (with diabetes mellitus vs. general population) or the class of CCB administered (DHP-CCB vs. non-DHP-CCB) (test for subgroup differences I2 = 0, p > 0.10). However, this beneficial effect was more significant among the general population (RR 0.70; 95% CI 0.66-0.74) compared to patients with diabetes mellitus (RR 0.72; 95% CI 0.61-0.86) and among those patients treated with DHP-CCBs (RR 0.69; 95% CI 0.63-0.74) compared to patients treated with non-DHP-CCBs (RR 0.72; 95% CI 0.67-0.78). Conclusion: CCBs may reduce the risk of active TB in patients with diabetes and the general population. On the contrary, CCBs do not seem to have a protective effect on tuberculosis-related mortality. However, more evidence is still needed. We recommend developing clinical trials to verify these findings, including more diverse populations. Systematic Review Registration: [https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=352129].

Harnessing host-pathogen interactions for innovative drug discovery and host-directed therapeutics to tackle tuberculosis

Tuberculosis (TB) is a highly contagious bacterial infection caused by Mycobacterium tuberculosis (Mtb), which has been ranked as the second leading cause of death worldwide from a single infectious agent. As an intracellular pathogen, Mtb has well adapted to the phagocytic host microenvironment, influencing diverse host processes such as gene expression, trafficking, metabolism, and signaling pathways of the host to its advantage. These responses are the result of dynamic interactions of the bacteria with the host cell signaling pathways, whereby the bacteria attenuate the host cellular processes for their survival. Specific host genes and the mechanisms involved in the entry and subsequent stabilization of M. tuberculosis intracellularly have been identified in various genetic and chemical screens recently. The present understanding of the co-evolution of Mtb and macrophage system presented us the new possibilities for exploring host-directed therapeutics (HDT). Here, we discuss the host-pathogen interaction for Mtb, including the pathways adapted by Mtb to escape immunity. The review sheds light on different host-directed therapies (HDTs) such as repurposed drugs and vitamins, along with their targets such as granuloma, autophagy, extracellular matrix, lipids, and cytokines, among others. The article also examines the available clinical data on these drug molecules. In conclusion, the review presents a perspective on the current knowledge in the field of HDTs and the need for additional research to overcome the challenges associated HDTs.

Mechanisms of lung damage in tuberculosis: implications for chronic obstructive pulmonary disease

Pulmonary tuberculosis is increasingly recognized as a risk factor for COPD. Severe lung function impairment has been reported in post-TB patients. Despite increasing evidence to support the association between TB and COPD, only a few studies describe the immunological basis of COPD among TB patients following successful treatment completion. In this review, we draw on well-elaborated Mycobacterium tuberculosis-induced immune mechanisms in the lungs to highlight shared mechanisms for COPD pathogenesis in the setting of tuberculosis disease. We further examine how such mechanisms could be exploited to guide COPD therapeutics.

Cardiovascular risk factors among people with drug-resistant tuberculosis in Uganda

Background

Tuberculosis (TB) and its risk factors are independently associated with cardiovascular disease (CVD). We determined the prevalence and associations of CVD risk factors among people with drug-resistant tuberculosis (DRTB) in Uganda.

Methods

In this cross-sectional study, we enrolled people with microbiologically confirmed DRTB at four treatment sites in Uganda between July to December 2021. The studied CVD risk factors were any history of cigarette smoking, diabetes mellitus (DM) hypertension, high body mass index (BMI), central obesity and dyslipidaemia. We used modified Poisson regression models with robust standard errors to determine factors independently associated with each of dyslipidaemia, hypertension, and central obesity.

Results

Among 212 participants, 118 (55.7%) had HIV. Overall, 196 (92.5%, 95% confidence interval (CI) 88.0-95.3) had ≥ 1 CVD risk factor. The prevalence; 95% CI of individual CVD risk factors was: dyslipidaemia (62.5%; 55.4–69.1), hypertension (40.6%; 33.8–47.9), central obesity (39.3%; 32.9–46.1), smoking (36.3%; 30.1–43.1), high BMI (8.0%; 5.0–12.8) and DM (6.5%; 3.7–11.1). Dyslipidaemia was associated with an increase in glycated haemoglobin (adjusted prevalence ratio (aPR) 1.14, 95%CI 1.06–1.22). Hypertension was associated with rural residence (aPR 1.89, 95% CI 1.14–3.14) and previous history of smoking (aPR 0.46, 95% CI 0.21–0.98). Central obesity was associated with increasing age (aPR 1.02, 95%CI 1.00–1.03), and elevated diastolic blood pressure (aPR 1.03 95%CI 1.00–1.06).

Conclusion

There is a high prevalence of CVD risk factors among people with DRTB in Uganda, of which dyslipidaemia is the commonest. We recommend integrated services for identification and management of CVD risk factors in DRTB.

Host-directed therapies in pulmonary tuberculosis: Updates on anti-inflammatory drugs

Tuberculosis (TB) is a lethal disease and remains one of the top ten causes of mortality by an infectious disease worldwide. It can also result in significant morbidity related to persistent inflammation and tissue damage. Pulmonary TB treatment depends on the prolonged use of multiple drugs ranging from 6 months for drug-susceptible TB to 6–20 months in cases of multi-drug resistant disease, with limited patient tolerance resulting from side effects. Treatment success rates remain low and thus represent a barrier to TB control. Adjunct host-directed therapy (HDT) is an emerging strategy in TB treatment that aims to target the host immune response to Mycobacterium tuberculosis in addition to antimycobacterial drugs. Combined multi-drug treatment with HDT could potentially result in more effective therapies by shortening treatment duration, improving cure success rates and reducing residual tissue damage. This review explores the rationale and challenges to the development and implementation of HDTs through a succinct report of the medications that have completed or are currently being evaluated in ongoing clinical trials.

CRISPR Interference Reveals That All-Trans-Retinoic Acid Promotes Macrophage Control of Mycobacterium tuberculosis by Limiting Bacterial Access to Cholesterol and Propionyl Coenzyme A

Macrophages are a protective replicative niche for Mycobacterium tuberculosis (Mtb) but can kill the infecting bacterium when appropriately activated. To identify mechanisms of clearance, we compared levels of bacterial restriction by human macrophages after treatment with 26 compounds, including some currently in clinical trials for tuberculosis. All-trans-retinoic acid (ATRA), an active metabolite of vitamin A, drove the greatest increase in Mtb control. Bacterial clearance was transcriptionally and functionally associated with changes in macrophage cholesterol trafficking and lipid metabolism. To determine how these macrophage changes affected bacterial control, we performed the first Mtb CRISPR interference screen in an infection model, identifying Mtb genes specifically required to survive in ATRA-activated macrophages. These data showed that ATRA treatment starves Mtb of cholesterol and the downstream metabolite propionyl coenzyme A (propionyl-CoA). Supplementation with sources of propionyl-CoA, including cholesterol, abrogated the restrictive effect of ATRA. This work demonstrates that targeting the coupled metabolism of Mtb and the macrophage improves control of infection and that it is possible to genetically map the mode of bacterial death using CRISPR interference. IMPORTANCE Tuberculosis, caused by the bacterium Mycobacterium tuberculosis, is a leading cause of death due to infectious disease. Improving the immune response to tuberculosis holds promise for fighting the disease but is limited by our lack of knowledge as to how the immune system kills M. tuberculosis. Our research identifies a potent way to make relevant immune cells more effective at fighting M. tuberculosis and then uses paired human and bacterial genomic methods to determine the mechanism of that improved bacterial clearance.

The Role of Lipid and the Benefit of Statin in Augmenting Rifampicin Effectivity for a Better Leprosy Treatment

Although leprosy remains as a serious disease of the skin and nervous system, the current treatment is still lacking in its effectiveness. This literature review will explore the association of lipid and leprosy, as well as the potential of statin and other lipid-lowering agents as adjunctive drugs to combat leprosy. Articles were searched through the PubMed, EBSCOhost, and Google Scholar with the keywords: immunomodulation, lipid-body, lipids, leprosy, Mycobacterium leprae, pathogenesis, rifampin or rifampicin, and statins. A manual searching is also carried out to find an additional relevant information to make this literature review more comprehensive. The literatures showed that lipids are highly correlated with leprosy through alterations in serum lipid profile, metabolism, pathogenesis, and producing oxidative stress. Statins can diminish lipid utilization in the pathogenesis of leprosy and show a mycobactericidal effect by increasing the effectiveness of rifampicin and recover the function of macrophages. In addition, Statins have anti-inflammatory properties which may aid in preventing type I and II reactions in leprosy. Standard multidrug therapy might reduce the efficacy of statins, but the effect is not clinically significant. The statin dose-response curve also allows therapeutic response to be achieved with minimal dose. The various pleiotropic effects of statins make it a potential adjunct to standard treatment for leprosy in the future.

Understanding the Reciprocal Interplay Between Antibiotics and Host Immune System: How Can We Improve the Anti-Mycobacterial Activity of Current Drugs to Better Control Tuberculosis?

Tuberculosis (TB), caused by Mycobacterium tuberculosis (Mtb) infection, remains a global health threat despite recent advances and insights into host-pathogen interactions and the identification of diverse pathways that may be novel therapeutic targets for TB treatment. In addition, the emergence and spread of multidrug-resistant Mtb strains led to a low success rate of TB treatments. Thus, novel strategies involving the host immune system that boost the effectiveness of existing antibiotics have been recently suggested to better control TB. However, the lack of comprehensive understanding of the immunomodulatory effects of anti-TB drugs, including first-line drugs and newly introduced antibiotics, on bystander and effector immune cells curtailed the development of effective therapeutic strategies to combat Mtb infection. In this review, we focus on the influence of host immune-mediated stresses, such as lysosomal activation, metabolic changes, oxidative stress, mitochondrial damage, and immune mediators, on the activities of anti-TB drugs. In addition, we discuss how anti-TB drugs facilitate the generation of Mtb populations that are resistant to host immune response or disrupt host immunity. Thus, further understanding the interplay between anti-TB drugs and host immune responses may enhance effective host antimicrobial activities and prevent Mtb tolerance to antibiotic and immune attacks. Finally, this review highlights novel adjunctive therapeutic approaches against Mtb infection for better disease outcomes, shorter treatment duration, and improved treatment efficacy based on reciprocal interactions between current TB antibiotics and host immune cells.

Monocyte progenitors give rise to multinucleated giant cells

The immune response to mycobacteria is characterized by granuloma formation, which features multinucleated giant cells as a unique macrophage type. We previously found that multinucleated giant cells result from Toll-like receptor-induced DNA damage and cell autonomous cell cycle modifications. However, the giant cell progenitor identity remained unclear. Here, we show that the giant cell-forming potential is a particular trait of monocyte progenitors. Common monocyte progenitors potently produce cytokines in response to mycobacteria and their immune-active molecules. In addition, common monocyte progenitors accumulate cholesterol and lipids, which are prerequisites for giant cell transformation. Inducible monocyte progenitors are so far undescribed circulating common monocyte progenitor descendants with high giant cell-forming potential. Monocyte progenitors are induced in mycobacterial infections and localize to granulomas. Accordingly, they exhibit important immunological functions in mycobacterial infections. Moreover, their signature trait of high cholesterol metabolism may be piggy-backed by mycobacteria to create a permissive niche.

Cardiovascular morbidity and mortality among persons diagnosed with tuberculosis: A systematic review and meta-analysis

Introduction

The emerging epidemiological evidence of increased cardiovascular disease (CVD) risk among persons diagnosed with tuberculosis (TB) has not been systematically reviewed to date. Our aim was to review the existing epidemiological evidence for elevated risk of CVD morbidity and mortality among persons diagnosed with TB compared to controls.

Materials and methods

EMBASE, MEDLINE, and Cochrane databases were searched (inception to January 2020) for terms related to “tuberculosis” and “cardiovascular diseases”. Inclusion criteria: trial, cohort, or case-control study design; patient population included persons diagnosed with TB infection or disease; relative risk (RR) estimate and confidence interval reported for CVD morbidity or mortality compared to suitable controls. Exclusion criteria: no TB or CVD outcome definition; duplicate study; non-English abstract; non-human participants. Two reviewers screened studies, applied ROBINS-I tool to assess risk of bias, and extracted data independently. Random effects meta-analysis estimated a pooled RR of CVD morbidity and mortality for persons diagnosed with TB compared to controls.

Results

6,042 articles were identified, 244 full texts were reviewed, and 16 were included, meta-analyzing subsets of 8 studies’ RR estimates. We estimated a pooled RR of 1.51 (95% CI: 1.16–1.97) for major adverse cardiac events among those diagnosed with TB compared to non-TB controls (p = 0.0024). A ‘serious’ pooled risk of bias was found across studies with between-study heterogeneity (I2 = 75.3%).

Conclusions

TB appears to be a marker for increased CVD risk; however, the literature is limited and is accompanied by serious risk of confounding bias and evidence of publication bias. Further retrospective and prospective studies are needed. Pending this evidence, best practice may be to consider persons diagnosed with TB at higher risk of CVD as a precautionary measure.