Protective effect of metformin against tuberculosis infections in diabetic patients: an observational study of south Indian tertiary healthcare facility

Potential role of indole-3-propionic acid in tuberculosis: current perspectives and future prospects

INTRODUCTION

Indole-3-propionic acid (IPA), a tryptophan catabolite derived from gut bacterial metabolism, has been identified as a functional link between the gut microbiome and tuberculosis.

AREA COVERED

IPA has gained ample attention over the past two decades on account of its multiple physiological roles, besides being both detectable and quantifiable. IPA is well studied across different health conditions, including cardiovascular and neurological conditions. IPA blocks tryptophan synthesis in Mycobacterium by binding to the allosteric tryptophan-binding site of TrpE, thereby threatening Mycobacterium survival due to tryptophan deficit.

EXPERT OPINION

Characterizing IPA would enable its use as a tool to investigate the pathophysiology of tuberculosis. Integrating 'OMICS' techniques (through next-generation sequencing) along with targeted microbial metabolomics may help explore the possible association of serum IPA levels with TB in patients. This will aid in identifying IPA-producing gut microbes and selecting probiotic strains as a microbiome-targeting adjunct therapy, eventually enhancing our understanding of the molecular dynamics of the pathophysiology of tuberculosis in the context of the microbiome.

Glycemic Profile and Clinical Treatment in Patients with Diabetes Mellitus-Tuberculosis: An Update Scoping Review

Background

Type 2 diabetes mellitus (T2DM), characterized by chronic hyperglycemia, leads to a decreased immune system and increased susceptibility to infections, such as tuberculosis (TB). However, there are gaps in comprehensive reviews on the relationship between TB and the severity of glycemic control in patients with T2DM, characteristics of glycemic levels, and clinical treatment among patients with DM-TB.

Purpose

The primary aim of this study is to explore the association of DM-TB and glycemic control. The secondary aim of this study was to explore the association between DM-TB, successful treatment, and TB severity.

Methods

This study used a scoping review following the Arksey and O'Malley framework to provide an overview of glycemic control and clinical treatment of DM-TB. A literature search was performed using three databases, PubMed, Scopus, and Medline, with inclusion criteria for the population of patients with diabetes mellitus and tuberculosis who discuss glycemic control and clinical treatment. Critical appraisal in this study was assessed using the Joanna-Briggs Institute (JBI) critical appraisal tools.

Results

We included 16 studies from a total of 741 articles in the initial search. The results of this study showed that patients with DM-TB were more likely to have poor glycemic control than those with diabetes mellitus (DM) without TB. Severe hyperglycemia in patients with DM-TB is associated with an increased risk of TB treatment failure, a long recovery time, and the likelihood of developing multi-drug-resistant tuberculosis (MDR-TB). In addition, patients with DM-TB who did not start TB treatment were more likely to have poorer glycemic control than patients with DM-TB who underwent active TB treatment.

Conclusion

Patients with DM-TB, such as MDR-TB, are at a higher risk of poor glycemic control, treatment failure, and clinical severity. Adequate treatment, such as a continuum of glycemic monitoring and early detection and intervention for TB, is needed to improve treatment outcomes.

Impact of diabetes mellitus on tuberculosis prevention, diagnosis, and treatment from an immunologic perspective

The coexistence of diabetes mellitus (DM) and tuberculosis (TB) presents a significant global burden, with DM being recognized as a major risk factor for TB. This review comprehensively analyzes the immunological aspects of DM-TB comorbidity, shedding light on the impact of DM on TB pathogenesis and immune responses. It reveals that high blood glucose levels in TB patients contribute to reduced innate immune cell count, compromised phagocytic function, and delayed antigen presentation. These factors ultimately impair the clearance of Mycobacterium tuberculosis (MTB) and delay adaptive immune responses. With the interaction between TB and DM, there is an increase in inflammation and elevated secretion of pro-inflammatory cytokines by immune cells. This exacerbates the inflammatory response and contributes to poor treatment outcomes in TB. Moreover, the review explores the effects of DM on TB prevention, diagnosis, and treatment. It highlights how poor glycemic control, insulin resistance (IR), DM complications, and genetic factors increase the risk of MTB infection in individuals with DM. Additionally, DM-related immune suppression adversely affects the sensitivity of traditional diagnostic tests for TB, potentially resulting in underdiagnosis and delayed intervention. To mitigate the burden of TB in DM patients, the review emphasizes the need for further research on the mechanisms underlying DM reactivation in latent TB infection (LTBI). It shows how important it is to find and treat LTBI in DM patients as soon as possible and suggests looking into biomarkers that are specific to DM to make diagnosis more accurate.

Synthesis and characterization of some Metal ions complexes with mixed ligand of azo dye and Metformin and evaluation of its effectiveness on the growth of some pathogenic bacteria clinically isolated and study of its Toxicity on normal and cancerous Hepatocytes

Four metal compounds mixed ligand of azo dye ligand (L) and metformin.(Met) were produced at aquatic ethanol for (1:1:1) (M:L:Met). The prepared compounds were identified by utilizing atomic absorption flame, FT.IR and UV-Vis spectrum manners as well as conductivity mensuration. These compounds was assayed of the gained datum the octahedral geometry was proposed into whole prepared complexes.Also in this research was studied represented examining the antibacterial and antifungal impact of the azo dye ligand (L), metformin.(Met) and (Co,Ni, Cu and Cd complexes) on four types of pathogenic, clinically isolated bacteria that are resistant to antibiotic, like Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli, Klebsiella pneumonia, and fungi Candida albicans from human in Iraq. The results of the sensitivity test showed the effectiveness of these compounds at a very low condensation of (10-3) in inhibiting the isolated bacteria. On the other hand, cytotoxic effects of the ligand, Met and mix ligand complexes showed anticancer activity on HepG2 cells in a serial condensation 15.6, 31, 62, 125, 250, 500 μg/ml. As the effectiveness of the compounds increases with increasing their condensation, the most effective toxicant on hepatic cancer cells is Met and cd complex and with a rate of 68.5 and 68.3 % respectively.

Effect of Metformin on Plasma Exposure of Rifampicin, Isoniazid, and Pyrazinamide in Patients on Treatment for Pulmonary Tuberculosis

BACKGROUND

To evaluate the effect of metformin on the plasma levels of rifampicin, isoniazid, and pyrazinamide in patients with drug-sensitive pulmonary tuberculosis being treated with first-line antituberculosis treatment (ATT) and to assess the influence of gene polymorphisms on the metabolic pathway of metformin and plasma levels of antitubercular drugs.

METHODS

Nondiabetic adults aged 18-60 years with pulmonary tuberculosis were randomized to either the standard ATT (ATT group) or ATT plus metformin (METRIF group) groups in a phase IIB clinical trial. An intensive pharmacokinetic study with blood collection at 0 hour (predosing), followed by 1, 2, 4, 6, 8, and 12 hours after dosing was conducted during the first month of treatment in a subset of 60 study participants after a minimum of 14 doses. Plasma concentrations of rifampicin, isoniazid, pyrazinamide, and metformin were measured by high-performance liquid chromatography using validated methods, and pharmacokinetic parameters and OCT1 and MATE1 gene polymorphisms were compared between the groups.

RESULTS

Significant increases in the clearance of rifampicin, isoniazid, and pyrazinamide were observed in patients in the METRIF group (n = 29) compared with those in the ATT group (n = 31). The AA genotypes of the single-nucleotide polymorphism of rs2289669 ( MATE1 ) in the METRIF group showed a significantly decreased area under the concentration-time curve to the last observation point and increased clearance of rifampicin.

CONCLUSIONS

Metformin altered rifampicin and isoniazid plasma concentrations in patients receiving antituberculosis treatment for pulmonary tuberculosis with little effect on sputum conversion at the end of treatment. Studies with larger sample sizes are needed to understand host drug-drug interactions.

Metformin Use Is Associated With Lower Mortality in Veterans With Diabetes Hospitalized With Pneumonia

BACKGROUND

Recent studies suggest that metformin use may be associated with improved infectious disease-related outcomes, whereas other papers suggest potentially worse outcomes in serious bacterial infections. Our purpose was to examine the association of prior outpatient prescription of metformin on 30- and 90-day mortality for older veterans with pre-existing diabetes hospitalized with pneumonia.

METHODS

We conducted a retrospective cohort study using national Department of Veterans Affairs data of patients ≥65 years with a prior history of diabetes who were hospitalized with pneumonia over a 10-year period (fiscal years 2002-2012.) For our primary analysis, we created a propensity score and matched metformin users to nonusers 1:1.

RESULTS

We identified 34 759 patients who met the inclusion criteria, 20.3% of whom were prescribed metformin. Unadjusted 30-day mortality was 9.6% for those who received metformin versus 13.9% in nonusers (P < .003), and 90-day mortality was 15.8% for those who received metformin versus 23.0% for nonusers (P < .0001). For the propensity score model, we matched 6899 metformin users to 6899 nonusers. After propensity matching, both 30-day (relative risk [RR]: .86; 95% confidence interval [CI]: .78-.95) and 90-day (RR: .85; 95% CI: .79-.92) mortality was significantly lower for metformin users.

CONCLUSIONS

Prior receipt of metformin was associated with significantly lower mortality after adjusting for potential confounders. Additional research is needed to examine the safety and potential benefits of metformin use in patients with respiratory infections.

Host-directed immunotherapy of viral and bacterial infections: past, present and future

The advent of COVID-19 and the persistent threat of infectious diseases such as tuberculosis, malaria, influenza and HIV/AIDS remind us of the marked impact that infections continue to have on public health. Some of the most effective protective measures are vaccines but these have been difficult to develop for some of these infectious diseases even after decades of research. The development of drugs and immunotherapies acting directly against the pathogen can be equally challenging, and such pathogen-directed therapeutics have the potential disadvantage of selecting for resistance. An alternative approach is provided by host-directed therapies, which interfere with host cellular processes required for pathogen survival or replication, or target the host immune response to infection (immunotherapies) to either augment immunity or ameliorate immunopathology. Here, we provide a historical perspective of host-directed immunotherapeutic interventions for viral and bacterial infections and then focus on SARS-CoV-2 and Mycobacterium tuberculosis, two major human pathogens of the current era, to indicate the key lessons learned and discuss candidate immunotherapeutic approaches, with a focus on drugs currently in clinical trials.

Effect of Tuberculosis (TB) and Diabetes mellitus (DM) integrated healthcare on bidirectional screening and treatment outcomes among TB patients and people living with DM in developing countries: a systematic review

A systematic review (Prospero CRD42017075562) including articles published between 1 January 1990 and 31 October 2021 was performed to synthesize evidence on the effect of integrating tuberculosis (TB) and diabetes mellitus (DM) healthcare on screening coverage and treatment loss to follow-up as compared to non-integrated care services for TB and DM in low- to middle-income countries (LMICs). Searches were performed in PubMed, Web of Science, WHO Global Index Medicus, and Cochrane Central Library. This review followed Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, and we adopted Cochrane data collection form for Randomized Controlled Trials (RCTs) and non-RCTs. Due to heterogeneity and limited data of studies included, meta-analysis was not performed. Of 6902 abstracts, 10 studies from South America, Asia, and Africa were included. One study from Zimbabwe showed 57% increase in DM screening among TB patients in integrated care as compared to non-integrated care; 95% CI: 54.1, 59.8. Seven studies with before-after comparison groups reported increased screening coverage during implementation of integrated healthcare that ranged from 10.1% in Mexico to 99.1% in China. Three studies reported reduction in loss to follow-up among TB patients in integrated care; two in China showed 9.2%, 95% CI: -16.7, -1.7, and -9.5%, 95% CI: -18.4, -0.7 differences, while a study from Mexico showed -5.3% reduction, 95% CI: -9.8, -0.9.With few and heterogenous included studies, the synthesized evidence is weak to establish effect of TB/DM integrated care. Therefore, further robust studies such as randomized clinical trials and well-designed observational studies are needed.

The Changing Paradigm of Drug-Resistant Tuberculosis Treatment: Successes, Pitfalls, and Future Perspectives

Drug-resistant tuberculosis (DR-TB) remains a global crisis due to the increasing incidence of drug-resistant forms of the disease, gaps in detection and prevention, models of care, and limited treatment options. The DR-TB treatment landscape has evolved over the last 10 years. Recent developments include the remarkable activity demonstrated by the newly approved anti-TB drugs bedaquiline and pretomanid against Mycobacterium tuberculosis. Hence, treatment of DR-TB has drastically evolved with the introduction of the short-course regimen for multidrug-resistant TB (MDR-TB), transitioning to injection-free regimens and the approval of the 6-month short regimens for rifampin-resistant TB and MDR-TB. Moreover, numerous clinical trials are under way with the aim to reduce pill burden and shorten the DR-TB treatment duration. While there have been apparent successes in the field, some challenges remain. These include the ongoing inclusion of high-dose isoniazid in DR-TB regimens despite a lack of evidence for its efficacy and the inclusion of ethambutol and pyrazinamide in the standard short regimen despite known high levels of background resistance to both drugs. Furthermore, antimicrobial heteroresistance, extensive cavitary disease and intracavitary gradients, the emergence of bedaquiline resistance, and the lack of biomarkers to monitor DR-TB treatment response remain serious challenges to the sustained successes. In this review, we outline the impact of the new drugs and regimens on patient treatment outcomes, explore evidence underpinning current practices on regimen selection and duration, reflect on the disappointments and pitfalls in the field, and highlight key areas that require continued efforts toward improving treatment approaches and rapid biomarkers for monitoring treatment response.

Modulating macrophage function to reinforce host innate resistance against Mycobacterium avium complex infection

Mycobacterium avium complex (MAC) is the main causative agent of infectious diseases in humans among nontuberculous mycobacteria (NTM) that are ubiquitous organisms found in environmental media such as soil as well as in domestic and natural waters. MAC is a primary causative agent of NTM-lung disease that threaten immunocompromised or structural lung disease patients. The incidence and the prevalence of M. tuberculosis infection have been reduced, while MAC infections and mortality rates have increased, making it a cause of global health concern. The emergence of drug resistance and the side effects of long-term drug use have led to a poor outcome of treatment regimens against MAC infections. Therefore, the development of host-directed therapy (HDT) has recently gained interest, aiming to accelerate mycobacterial clearance and reversing lung damage by employing the immune system using a novel adjuvant strategy to improve the clinical outcome of MAC infection. Therefore, in this review, we discuss the innate immune responses that contribute to MAC infection focusing on macrophages, chief innate immune cells, and host susceptibility factors in patients. We also discuss potential HDTs that can act on the signaling pathway of macrophages, thereby contributing to antimycobacterial activity as a part of the innate immune response during MAC infection. Furthermore, this review provides new insights into MAC infection control that modulates and enhances macrophage function, promoting host antimicrobial activity in response to potential HDTs and thus presenting a deeper understanding of the interactions between macrophages and MACs during infection.

Non-Antibiotic Drug Repositioning as an Alternative Antimicrobial Approach

The worldwide scenario of antibiotic resistance and the falling number of funds for the development of novel antibiotics have led research efforts toward the study of specific cost-effective strategies aimed at discovering drugs against microbial infections. Among the potential options, drug repositioning, which has already exhibited satisfactory results in other medical fields, came out as the most promising. It consists of finding new uses for previously approved medicines and, over the years, many “repurposed drugs” displayed some encouraging in vitro and in vivo results beyond their initial application. The principal theoretical justification for reusing already existing drugs is that they have known mechanisms of action and manageable side effects. Reuse of old drugs is now considered an interesting approach to overcome the drawbacks of conventional antibiotics. The purpose of this review is to offer the reader a panoramic view of the updated studies concerning the repositioning process of different classes of non-antibiotic drugs in the antimicrobial field. Several research works reported the ability of some non-steroidal anti-inflammatory drugs (NSAIDs), antidepressants, antipsychotics, and statins to counteract the growth of harmful microorganisms, demonstrating an interesting winning mode to fight infectious diseases caused by antimicrobial resistant bacteria.

Shedding Light on Autophagy During Human Tuberculosis. A Long Way to Go

Immunity against Mycobacterium tuberculosis (Mtb) is highly complex, and the outcome of the infection depends on the role of several immune mediators with particular temporal dynamics on the host microenvironment. Autophagy is a central homeostatic mechanism that plays a role on immunity against intracellular pathogens, including Mtb. Enhanced autophagy in macrophages mediates elimination of intracellular Mtb through lytic and antimicrobial properties only found in autolysosomes. Additionally, it has been demonstrated that standard anti-tuberculosis chemotherapy depends on host autophagy to coordinate successful antimicrobial responses to mycobacteria. Notably, autophagy constitutes an anti-inflammatory mechanism that protects against endomembrane damage triggered by several endogenous components or infectious agents and precludes excessive inflammation. It has also been reported that autophagy can be modulated by cytokines and other immunological signals. Most of the studies on autophagy as a defense mechanism against Mycobacterium have been performed using murine models or human cell lines. However, very limited information exists about the autophagic response in cells from tuberculosis patients. Herein, we review studies that face the autophagy process in tuberculosis patients as a component of the immune response of the human host against an intracellular microorganism such as Mtb. Interestingly, these findings might contribute to recognize new targets for the development of novel therapeutic tools to combat Mtb. Actually, either as a potential successful vaccine or a complementary immunotherapy, efforts are needed to further elucidate the role of autophagy during the immune response of the human host, which will allow to achieve protective and therapeutic benefits in human tuberculosis.

Randomized trial of Metformin with Anti-tuberculosis drugs For Early Sputum Conversion in Adults with Pulmonary Tuberculosis

Background

Metformin, by reducing intracellular Mycobacterium tuberculosis growth, can be considered an adjunctive therapy to anti-tuberculosis treatment (ATT). We determined whether metformin with standard ATT reduces time to sputum culture conversion and tissue inflammation in adults with pulmonary tuberculosis (PTB).

Methods

In a randomized, 8-week, clinical trial, newly diagnosed, culture-positive PTB patients were randomized to standard ATT (HREZ = control arm) or standard ATT plus daily 1000 mg metformin (MET-HREZ = Metformin with Rifampicin [METRIF] arm) for 8 weeks during 2018–2020 at 5 sites in India. The primary end point was time to sputum culture conversion by liquid culture during 8 weeks of ATT. Plasma inflammatory markers were estimated in a subset. A Cox proportional hazard model was used to estimate time and predictors of culture conversion.

Results

Of the 322 patients randomized, 239 (74%) were male, and 212 (66%) had bilateral disease on chest radiograph with 54 (18%) showing cavitation. The median time to sputum culture conversion by liquid culture was 42 days in the METRIF arm and 41 days in the control arm (hazard ratio, 0.8; 95% confidence interval [CI], .624–1.019). After 8 weeks of ATT, cavitary lesions on X-ray (7, 5.3% vs 18, 12.9%; relative risk, 0.42; 95% CI, .18–.96; P = .041) and inflammatory markers were significantly lower in the METRIF arm. Higher body mass index and lower sputum smear grading were associated with faster sputum culture conversion.

Conclusions

The addition of metformin to standard ATT did not hasten sputum culture conversion but diminished excess inflammation, thus reducing lung tissue damage as seen by faster clearance on X-ray and reduced inflammatory markers.

Clinical Trials Registration

Clinical Trial Registry of India (CTRI/2018/01/011176)

The cumulative dose-dependent effects of metformin on the development of tuberculosis in patients newly diagnosed with type 2 diabetes mellitus

BACKGROUND

Diabetes mellitus (DM) is a well-known risk factor for tuberculosis (TB). Metformin, which is an essential anti-diabetic drug, has been shown to exhibit anti-TB effects in patients with DM. Its effect on preventing the development of TB among patients who are newly diagnosed with DM remains unclear.

METHODS

This was a retrospective cohort study using the claims database of the Korean Health Insurance Review and Assessment Service. The study population included patients who were newly diagnosed with type 2 DM and who were treated with anti-diabetic drugs between 1 January 2003 and 31 March 2011. A patient was defined as a metformin user if he/she had taken metformin for more than 28 days within 6 months since cohort entry, and as a metformin non-user if he/she had never been treated with metformin. The development of TB within 2 years after the index date was compared by Cox proportional hazard regression models between metformin users and 1:1 propensity score (PS)-matched non-users.

RESULTS

Among 76,973 patients who were newly diagnosed with type 2 DM, 13,396 were classified as metformin users, 52,736 were classified as metformin non-users, and 10,841 were excluded from the final analysis. PS-matched Cox proportional hazard regression models revealed that metformin use was not associated overall with the prevention of TB development (HR 1.17; 95% CI 0.75-1.83; P = 0.482). There was a trend, however, towards a reduction in the development of TB among patients taking a higher cumulative dose of metformin. Patients who were in the highest quartile (Q4) of cumulative metformin dose had only a 10% risk of developing TB compared to metformin non-users. In contrast, during the early phases of metformin treatment, patients in the second quartile (Q2) of cumulative metformin use had a higher risk of developing TB than patients in the first quartile (Q1).

CONCLUSIONS

Only the highest cumulative doses of metformin were protective against the development of TB among patients who were newly diagnosed with type 2 DM; lower cumulative doses of metformin did not appear to reduce the incidence of active TB infection.

Metformin as a potential protective therapy against tuberculosis in patients with diabetes mellitus: A retrospective cohort study in a single teaching hospital

AIMS/INTRODUCTION

The convergence of tuberculosis (TB) and diabetes mellitus (DM) is a new challenge in Asia as a result of the rising prevalence of diabetes mellitus with higher TB infection rates, and also because diabetes mellitus itself enhances TB disease activity and consequently the spread of TB. We aimed to address the risk presented by diabetes mellitus for TB infection.

MATERIALS AND METHODS

Patients with diabetes mellitus were retrospectively recruited. The baseline assessments included age, sex, body mass index, fasting blood glucose, glycated hemoglobin, urine albumin-to-creatinine ratio and estimated glomerular filtration rate. TB was determined by meeting the international classification of disease, for TB diagnosis and receiving anti-TB treatment for at least 2 months.

RESULTS

In total, 9,750 individuals with diabetes mellitus were recruited. The event rate of TB was 47 (0.48%). Younger age, lower proportion of men, higher fasting blood glucose and glycated hemoglobin values, and better renal function (estimated glomerular filtration rate and urine albumin-to-creatinine ratio) were observed in the metformin-exposed groups. Old age and male sex were associated with higher TB infection risk on multivariate analysis. Metformin users had a significantly lower risk for TB infection, whereas insulin users had a higher risk for TB infection. However, glycemic status had no effect on TB infection risk.

CONCLUSIONS

This study provides clinical evidence from a survey of TB in individuals with diabetes mellitus. Old age, male sex and insulin use were risk factors for TB infection. Metformin remains the first choice of treatment for diabetes mellitus and has a potential protective effect against TB infection.

Tuberculosis: An Update on Pathophysiology, Molecular Mechanisms of Drug Resistance, Newer Anti-TB Drugs, Treatment Regimens and Host- Directed Therapies

Human tuberculosis (TB) is primarily caused by Mycobacterium tuberculosis (Mtb) that inhabits inside and amidst immune cells of the host with adapted physiology to regulate interdependent cellular functions with intact pathogenic potential. The complexity of this disease is attributed to various factors such as the reactivation of latent TB form after prolonged persistence, disease progression specifically in immunocompromised patients, advent of multi- and extensivelydrug resistant (MDR and XDR) Mtb strains, adverse effects of tailor-made regimens, and drug-drug interactions among anti-TB drugs and anti-HIV therapies. Thus, there is a compelling demand for newer anti-TB drugs or regimens to overcome these obstacles. Considerable multifaceted transformations in the current TB methodologies and molecular interventions underpinning hostpathogen interactions and drug resistance mechanisms may assist to overcome the emerging drug resistance. Evidently, recent scientific and clinical advances have revolutionised the diagnosis, prevention, and treatment of all forms of the disease. This review sheds light on the current understanding of the pathogenesis of TB disease, molecular mechanisms of drug-resistance, progress on the development of novel or repurposed anti-TB drugs and regimens, host-directed therapies, with particular emphasis on underlying knowledge gaps and prospective for futuristic TB control programs.

The association of glycemic level and prevalence of tuberculosis: a meta-analysis

BACKGROUND

Diabetes is a well-known risk factor for tuberculosis and poorly glycemic control may increase the risk of tuberculosis. We performed a meta-analysis to explore the association of glycemic control in diabetic patients and their tuberculosis prevalence.

METHODS

We included observational studies that investigated the prevalence of tuberculosis associated with glycemic control. The markers of glycated hemoglobin A1c (HbA1c) and fasting plasma glucose were used to evaluate the exposure of interest in the study. We searched related articles in PubMed, EMBASE and Web of Science through 14 December 2019. The Newcastle-Ottawa scale was used to assess the risk of bias of included studies.

RESULTS

Seventeen studies (four cohort studies, five case-control studies and eight cross-sectional studies) were included, involving 1,027,074 participants. The meta-analysis found the pooled odds ratio of prevalent tuberculosis increased a 2.05-fold (95%CI: 1.65, 2.55) for the patients with HbA1c ≥7.0% compared to those with HbA1c concentration < 7.0%. Furthermore, we found the mean of HbA1c was higher in the diabetes mellitus with tuberculosis group than the diabetes-only group (P = 0.002). In the sensitivity analysis, the finding remains consistent.

CONCLUSION

Our study provides the evidence that poorly controlled diabetes in diabetics may be associated with increased prevalence of tuberculosis. More efforts should focus on screening tuberculosis in uncontrolled diabetes.

Metformin as a Potential Adjuvant Antimicrobial Agent Against Multidrug Resistant Bacteria

Introduction

The continuous increase in the incidence of bacterial resistance to existing antibiotics represents a worldwide health burden. A surrogate strategy to combat such crisis is to find compounds that restore the antimicrobial activity of the already existing antibiotics against multidrug resistant bacteria. Metformin is a commonly used antidiabetic medication. It has proven benefits in other diseases including cancer, aging-related and infectious diseases. In this study, the potential effect of metformin as an adjuvant therapy to antibiotics was investigated.

Methods

Two multidrug resistant bacterial strains were used; methicillin-resistant Staphylococcus aureus (MRSA; ATCC 33,591) and multidrug resistant Pseudomonas aeruginosa (ATCC BAA-2114). To assess its efficacy, metformin was combined with several antibiotics: levofloxacin, chloramphenicol, rifampicin, ampicillin, and doxycycline. The antibacterial effect of metformin was tested using the micro broth dilution method. The minimum inhibitory concentration (MIC) was also measured. Cytotoxicity studies were also performed on mammalian cells to assess its safety.

Results

Metformin exhibited an antibacterial effect when combined with the antibiotics on the two tested strains. It also showed low toxicity on the mammalian cells. Moreover, synergetic studies showed that metformin enhanced the effect of the combined antibiotics, as these combinations provide either a synergistic or additive effect with significant reduction in the MIC.

Conclusion

Metformin exerts an adjuvant antibacterial effect; thus, it could be a possible candidate as an adjuvant therapy to reduce antimicrobial resistance.

Effect of anti-tuberculosis treatment on the systemic levels of tissue inhibitors of metalloproteinases in tuberculosis - Diabetes co-morbidity

Objectives

To study the association of Tissue inhibitors of matrix metalloproteinases (TIMP) levels with tuberculosis-diabetes comorbidity (TB-DM) comorbidity at baseline and in response to anti-TB treatment (ATT).

Methods

We examined the levels of TIMP-1, -2, -3 and -4 in pulmonary tuberculosis alone (TB) or TB-DM at baseline and after ATT.

Results

TIMP-1, -3 and -4 were significantly increased in TB-DM compared to TB at baseline and after ATT. ATT resulted in a significant reduction in TIMP-2 and -3 levels and a significant increase in TIMP-1 in both TB and TB-DM. TIMP-1, -3 and -4 were also significantly increased in TB-DM individuals with bilateral, cavitary disease and also exhibited a positive relationship with bacterial burden in TB-DM and HbA1c in all TB individuals. Within the TB-DM group, those known to be diabetic before incident TB (KDM) exhibited higher levels of TIMP-1, -2, -3 and -4 at baseline and TIMP-2 at post-treatment compared to those newly diagnosed with DM (NDM). KDM individuals on metformin treatment exhibited lower levels of TIMP-1, -2 and -4 at baseline and of TIMP-4 at post-treatment.

Conclusions

TIMP levels were elevated in TB-DM, associated with disease severity and bacterial burden, correlated with HbA1c levels and modulated by duration of DM and metformin treatment.

Impact of metformin therapy on health-related quality of life outcomes in tuberculosis patients with diabetes mellitus in India: A prospective study

OBJECTIVE

To assess the impact of metformin use on health-related quality of life (HRQoL) in tuberculosis (TB) patients who are presented with type 2 diabetes mellitus (T2DM).

METHODOLOGY

In this community-based prospective study, TB patients attending Hakeem Abdul Hameed Centenary Hospital, New Delhi (India) and had comorbidity of T2DM between April 2018 and July 2019 were enrolled. Patients were divided into metformin users and metformin non-users on the basis of the presence of metformin in their routine as antidiabetic drug(s). HRQoL was determined using a validated TB-specific tool (Dhingra and Rajpal-12 scale ie, DR-12) consists of symptom and socio-psychological and exercise adaptation domains. The HRQoL scores were compared at pretreatment (1st visit), end of intensive phase (2nd visit) and end of treatment (3rd visit) between the two groups.

RESULTS

A total of 120 patients were enrolled, of which 24 were excluded as they did not respond at follow-up visits. Among the metformin users (n = 48) the mean age of patients was 47.56 years and 62.50% was males. Among the metformin non-users (n = 48), the mean age of patients was 49.02 years and 54.10% was males. The baseline characteristics were similar in both groups except for the substance used history (P = .025), literacy level (P = .048) and BMI (P = .028). Metformin users demonstrated significant improvement in symptom scores (2nd visit: P < .001; 3rd visit: P = .001) and socio-psychological and exercise adaptation scores (2nd visit: P < .0001; 3rd visit: P < .0001) as compared with metformin non-users at 2nd visit and 3rd visit. Overall, scores were also found to be significantly improved in metformin users (2nd visit: P < .001; 3rd visit: P = .001).

CONCLUSION

Metformin therapy exerted favourable effects on HRQoL in patients with TB and T2DM and can be recommended as an adjuvant antitubercular drug in TB patients with co-morbidity of T2DM, unless contraindicated.

Diabetes Mellitus and Tuberculosis Treatment Outcomes in Pune, India

Background

Diabetes mellitus (DM) increases the risk of tuberculosis (TB) disease. Knowledge of the impact of DM on TB treatment outcomes is primarily based on retrospective studies.

Methods

We conducted a prospective cohort study of new pulmonary TB patients with and without DM (TB-DM and TB only) in India. The association of DM with a composite unfavorable TB treatment outcome (failure, recurrence, mortality) over 18 months was determined, and the effect of DM on all-cause mortality and early mortality (death during TB treatment) was assessed.

Results

Of 799 participants, 574 (72%) had TB only and 225 (28%) had TB-DM. The proportion of patients with DM who experienced the composite outcome was 20%, as compared with 21% for TB-only participants (adjusted hazard ratio [aHR], 1.13; 95% CI, 0.75–1.70). Mortality was higher in participants with DM (10% vs 7%), and early mortality was substantially higher among patients with DM (aHR, 4.36; 95% CI, 1.62–11.76).

Conclusions

DM was associated with early mortality in this prospective cohort study, but overall unfavorable outcomes were similar to participants without DM. Interventions to reduce mortality during TB treatment among people with TB-DM are needed.

Susceptibility for Some Infectious Diseases in Patients With Diabetes: The Key Role of Glycemia

Uncontrolled diabetes results in several metabolic alterations including hyperglycemia. Indeed, several preclinical and clinical studies have suggested that this condition may induce susceptibility and the development of more aggressive infectious diseases, especially those caused by some bacteria (including Chlamydophila pneumoniae, Haemophilus influenzae, and Streptococcus pneumoniae, among others) and viruses [such as coronavirus 2 (CoV2), Influenza A virus, Hepatitis B, etc.]. Although the precise mechanisms that link glycemia to the exacerbated infections remain elusive, hyperglycemia is known to induce a wide array of changes in the immune system activity, including alterations in: (i) the microenvironment of immune cells (e.g., pH, blood viscosity and other biochemical parameters); (ii) the supply of energy to infectious bacteria; (iii) the inflammatory response; and (iv) oxidative stress as a result of bacterial proliferative metabolism. Consistent with this evidence, some bacterial infections are typical (and/or have a worse prognosis) in patients with hypercaloric diets and a stressful lifestyle (conditions that promote hyperglycemic episodes). On this basis, the present review is particularly focused on: (i) the role of diabetes in the development of some bacterial and viral infections by analyzing preclinical and clinical findings; (ii) discussing the possible mechanisms by which hyperglycemia may increase the susceptibility for developing infections; and (iii) further understanding the impact of hyperglycemia on the immune system.

Targeting Autophagy as a Strategy for Developing New Vaccines and Host-Directed Therapeutics Against Mycobacteria

Mycobacterial disease is an immense burden worldwide. This disease group includes tuberculosis, leprosy (Hansen's disease), Buruli Ulcer, and non-tuberculous mycobacterial (NTM) disease. The burden of NTM disease, both pulmonary and ulcerative, is drastically escalating globally, especially in developed countries such as America and Australia. Mycobacteria's ability to inhibit or evade the host immune system has contributed significantly to its continued prevalence. Pre-clinical studies have highlighted promising candidates that enhance endogenous pathways and/or limit destructive host responses. Autophagy is a cell-autonomous host defense mechanism by which intracytoplasmic cargos can be delivered and then destroyed in lysosomes. Previous studies have reported that autophagy-activating agents, small molecules, and autophagy-activating vaccines may be beneficial in restricting intracellular mycobacterial infection, even with multidrug-resistant strains. This review will examine how mycobacteria evade autophagy and discusses how autophagy could be exploited to design novel TB treatment strategies, such as host-directed therapeutics and vaccines, against Mycobacterium tuberculosis and NTMs.

Metformin enhances protection in guinea pigs chronically infected with Mycobacterium tuberculosis

Tuberculosis (TB) is a chronic inflammatory disease that is often associated with alterations in systemic and cellular metabolism that resolves following successful antimicrobial drug treatment. We hypothesized that altered systemic glucose metabolism as a consequence of Mycobacterium tuberculosis (Mtb) infection, contributes to TB pathogenesis, and when normalized with anti-glycemic drugs would improve clinical outcomes. To test this hypothesis, guinea pigs were treated daily with the anti-diabetic drug metformin starting 4 weeks prior or concurrent with aerosol exposure to the H37Rv strain of Mtb. In the chronic stages of infection, Mtb infected metformin-treated animals had restored systemic insulin sensitivity but remained glucose intolerant as determined by oral glucose tolerance testing. Despite persistent glucose intolerance, metformin-treated guinea pigs had a 2.8-fold reduction in lung lesion burden and a 0.7 log decrease in CFUs. An alternative hypothesis that metformin treatment improved clinical disease by having a direct effect on immune cell energy metabolism was tested using extracellular flux analysis and flow cytometry. The proinflammatory immune response to Mtb infection in untreated guinea pigs was associated with a marked increase in energy metabolism (glycolysis and mitochondrial respiration) of peripheral blood mononuclear cells (PBMCs), which was normalized in metformin-treated guinea pigs. Moreover, both CD4⁺ and CD8⁺ T lymphocytes from Mtb infected, metformin treated animals maintained a more normal mitochondrial membrane potential while those isolated from untreated animals had persistent mitochondrial hyperpolarization. These data suggest that metformin promotes natural host resistance to Mtb infection by maintaining immune cell metabolic homeostasis and function during the chronic stages of active TB disease.

α-Glucosidase Inhibitor Can Effectively Inhibit the Risk of Tuberculosis in Patients with Diabetes: A Nested Case-Control Study

Diabetes mellitus (DM) and tuberculosis (TB) are major public health and economic burdens. DM increases Mycobacterium tuberculosis (M.tb) infection rates and treatment durations. This study evaluated the relationship between five classes of oral DM medications and TB infection risk in DM patients. We used longitudinal records from the Taiwan Longitudinal Health Insurance Research Database. DM patients were identified using the International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) code 250 and A code A181. TB patients were identified using ICD-9-CM code 010.x-017.x. Oral DM medications were divided into five classes: sulfonylureas, biguanides, meglitinides, α-glucosidase inhibitors (AGIs), and thiazolidinediones. Users were classified as nonusers, low-concentration users, and high-concentration users. The incidence rate ratio (IRR) was derived using multivariate Poisson regression to calculate the relative risk of TB infection. DM patients using low- and high-concentration AGIs had significantly lower TB infection risks compared with nonusers. The IRRs of the sulfonylureas and AGI users were [CI] 0.693-0.948) and (95% CI 0.651-0.995), respectively. The other four classes of medications exhibited no significant effect on TB infection risk in DM patients. Furthermore, DM patients using high-concentration AGIs had a significantly lower TB infection risk compared with those using low-concentration AGIs (IRR 0.918, 95% CI: 0.854-0.987). We noted a dose-response relationship in the effects of DM medications on TB risk. Accordingly, we suggest that DM patients use AGIs to benefit from their protective effect on TB infection risk.

Metformin as Host-Directed Therapy for TB Treatment: Scoping Review

Tuberculosis (TB) disease is an international health concern caused by the bacteria Mycobacterium tuberculosis (Mtb). Evolution of multi-drug-resistant strains may cause bacterial persistence, rendering existing antibiotics ineffective. Hence, development of new or repurposing of currently approved drugs to fight Mtb in combination with existing antibiotics is urgently needed to cure TB which is refractory to current therapy. The shortening of TB therapy and reduction in lung injury can be achieved using adjunctive host-directed therapies. There is a wide range of probable candidates which include numerous agents permitted for the treatment of other diseases. One potential candidate is metformin, a Food and Drug Administration (FDA)-approved drug used to treat type 2 diabetes mellitus (DM). However, there is a scarcity of evidence supporting the biological basis for the effect of metformin as a host-directed therapy for TB. This scoping review summarizes the current body of evidence and outlines scientific gaps that need to be addressed in determining the potential role of metformin as a host-directed therapy.

Host-Directed Therapies and Anti-Virulence Compounds to Address Anti-Microbial Resistant Tuberculosis Infection

Despite global efforts to contain tuberculosis (TB), the disease remains a leading cause of morbidity and mortality worldwide, further exacerbated by the increased resistance to antibiotics displayed by the tubercle bacillus Mycobacterium tuberculosis. In order to treat drug-resistant TB, alternative or complementary approaches to standard anti-TB regimens are being explored. An area of active research is represented by host-directed therapies which aim to modulate the host immune response by mitigating inflammation and by promoting the antimicrobial activity of immune cells. Additionally, compounds that reduce the virulence of M. tuberculosis, for instance by targeting the major virulence factor ESX-1, are being given increased attention by the TB research community. This review article summarizes the current state of the art in the development of these emerging therapies against TB.

Effects of host-directed therapies on the pathology of tuberculosis

Mycobacterium tuberculosis, the causative agent of tuberculosis (TB), has co-evolved with the human immune system and utilizes multiple strategies to persist within infected cells, to hijack several immune mechanisms, and to cause severe pathology and tissue damage in the host. This delays the efficacy of current antibiotic therapy and contributes to the evolution of multi-drug-resistant strains. These challenges led to the development of the novel approach in TB treatment that involves therapeutic targeting of host immune response to control disease pathogenesis and pathogen growth, namely, host-directed therapies (HDTs). Such HDT approaches can (1) enhance the effect of antibiotics, (2) shorten treatment duration for any clinical form of TB, (3) promote development of immunological memory that could protect against relapse, and (4) ameliorate the immunopathology including matrix destruction and fibrosis associated with TB. In this review we discuss TB-HDT candidates shown to be of clinical relevance that thus could be developed to reduce pathology, tissue damage, and subsequent impairment of pulmonary function. © 2020 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Therapeutic host-directed strategies to improve outcome in tuberculosis

Bacille Calmette-Guérin (BCG) is the only licenced tuberculosis (TB) vaccine, but has limited efficacy against pulmonary TB disease development and modest protection against extrapulmonary TB. Preventative antibiotic treatment for Mycobacterium tuberculosis (Mtb) infections in high-prevalence settings is unfeasible due to unclear treatment durability, drug toxicity, logistical constraints related to directly observed treatment strategy (DOTS) and the lengthy treatment protocols. Together, these factors promote non-adherence, contributing to relapse and establishment of drug-resistant Mtb strains. Although antibiotic treatment of drug-susceptible Mtb is generally effective, drug-resistant TB has a treatment efficacy below 50% and can, in a proportion, develop into progressive, untreatable disease. Other immune compromising co-infections and/or co-morbidities require more complex prevention/treatment approaches, posing huge financial burdens to national health services. Novel TB treatment strategies, such as host-directed therapeutics, are required to complement pathogen-targeted approaches. Pre-clinical studies have highlighted promising candidates that enhance endogenous pathways and/or limit destructive host responses. This review discusses promising pre-clinical candidates and forerunning compounds at advanced stages of clinical investigation in TB host-directed therapeutic (HDT) efficacy trials. Such approaches are rationalized to improve outcome in TB and shorten treatment strategies.

Impacts of metformin on tuberculosis incidence and clinical outcomes in patients with diabetes: a systematic review and meta-analysis

BACKGROUND

Accumulating evidence suggested that the use of metformin had more benefits for both prevention and treatment of tuberculosis (TB) than non-metformin use in patients with diabetes mellitus (DM); however, it remains to be fully elucidated on this topic. Thus, we conducted a systematic review and meta-analysis of published studies to determine the association between metformin use and TB in patients with diabetes.

METHODS

The MEDLINE, EMBASE, Information Sciences Institute (ISI) Web of Science, and Cochrane CENTRAL databases were searched from their inception to 15 April 2019. Studies that evaluated the use of metformin and TB disease were included. The quality of each study was evaluated through the Newcastle-Ottawa Scale (NOS). For pooled data, the relative risk (RR) and 95% confidence intervals (CIs) were calculated; otherwise, a systematic review.

RESULTS

Seventeen observational studies were included, all of which indicated a low risk of bias according to the NOS. The pooled analysis showed that metformin use was associated with a significantly lower active TB incidence and mortality among individuals with DM (RR = 0.51; 95% CI, 0.38-0.69, P ⩽ 0.001) and with TB-DM (RR = 0.34; 95% CI, 0.20-0.57, P ⩽ 0.001), respectively.

CONCLUSIONS

This meta-analysis indicated metformin use is related to benefits in both prevention and treatment outcomes of tuberculosis among patients with diabetes. Prospective clinical trials are needed to confirm these associations.

Impact of metformin use among tuberculosis close contacts with diabetes mellitus in a nationwide cohort study

BACKGROUND

The protective effect of metformin against active tuberculosis (TB) among TB close contacts is unknown.

METHODS

TB close contacts with diabetes mellitus (DM) and normal renal function were selected from the National Health Insurance Research Database of Taiwan. Metformin users were patients who received ≥90 cumulative defined daily doses within 1 year before the index date. For each metformin user, a propensity-score matched metformin nonuser and an age- and sex-matched healthy TB close contact were selected. The outcome was incident TB, identified using previously validated diagnostic criteria. Independent predictors were investigated using stratified Cox regression analysis. Interaction analysis was also performed.

RESULTS

A total of 5846 TB close contacts who were metformin users, metformin non-users, and healthy contacts were analysed. The incidence of active TB was 755 (600-938), 1117 (927-1335), and 526 (393-689) cases per 100,000 person-years in each group, respectively. Multivariate analysis revealed that healthy contacts had the lowest risk of developing active TB (adjusted hazard ratio [aHR]: 0.42 [0.30-0.60]) and metformin use partially reversed the risk associated with DM (aHR: 0.73 [0.54-0.98]). Subpopulation analysis revealed a significant interaction between insulin use and metformin use.

CONCLUSIONS

Metformin use is associated with a lower risk of developing active TB among TB close contacts with DM, especially for insulin users. It may be an alternative choice for primary prevention against active TB if no contraindications exist. However, prospective studies are needed to confirm the findings.

Immunological Impacts of Diabetes on the Susceptibility of Mycobacterium tuberculosis

The interaction between diabetes and major world infections like TB is a major public health concern because of rapidly rising levels of diabetes. The dual burden of tuberculosis (TB) and diabetes mellitus (DM) has become a major global public health problem. Diabetes mellitus is a major risk factor for the development of active and latent tuberculosis. Immune mechanisms contributing to the increased susceptibility of diabetic patients to TB are due to the defects in bacterial recognition, phagocytic activity, and cellular activation which results in impaired production of chemokines and cytokines. The initiation of adaptive immunity is delayed by impaired antigen-presenting cell (APC) recruitment and function in hyperglycemic host, which results in reduced frequencies of Th1, Th2, and Th17 cells and its secretion of cytokines having a great role in activation of macrophage and inflammatory response of tuberculosis. In addition, impaired immune response and killing of intracellular bacteria potentially increase bacterial load, chronic inflammation, and central necrosis that facilitate bacterial dissemination and miliary tuberculosis. Understanding of the immunological and biochemical basis of TB susceptibility in diabetic patients will tell us the rational development of implementation and therapeutic strategies to alleviate the dual burden of the diseases. Therefore, the aim of this review was focused on the association between diabetes and tuberculosis, focusing on epidemiology, pathogenesis, and immune dysfunction in diabetes mellitus, and its association with susceptibility, severity, and treatment outcome failure to tuberculosis.

Potentials of Host-Directed Therapies in Tuberculosis Management

Tuberculosis (TB) remains as a leading cause of mortality in developing countries, persisting as a major threat to the global public health. Current treatment involving a long antibiotic regimen brings concern to the topic of patient compliance, contributing to the emergence of drug resistant TB. The current review will provide an updated outlook on novel anti-TB therapies that can be given as adjunctive agents to current anti-TB treatments, with a particular focus on modulating the host immune response to effectively target all forms of TB. Additional potential therapeutic pathway targets, including lipid metabolism alteration and vascular endothelial growth factor (VEGF)-directed therapies, are discussed.

Metformin and Dipeptidyl Peptidase-4 Inhibitor Differentially Modulate the Intestinal Microbiota and Plasma Metabolome of Metabolically Dysfunctional Mice

OBJECTIVES

Recent evidence indicates that gut microbiota is altered considerably by a variety of commonly prescribed medications. This study assessed the impact of 2 antidiabetic therapeutics on gut microbiota and markers of cardiometabolic disease in metabolically dysfunctional mice.

METHODS

C57BL/6 mice were fed a high-fat diet for 24 weeks while receiving 1 of 2 antidiabetic therapeutics-metformin or dipeptidyl peptidase-4 (DPP-4) inhibitor, PKF-275-055-for the final 12 weeks. Mice were assessed for weight gain, glucose and cholesterol metabolism, and adiposity. In addition, cecal microbiota was analyzed by 16S compositional sequencing, and plasma metabolome was analyzed by liquid chromatography with tandem mass spectrometry.

RESULTS

Both therapeutics had similar metabolic effects, attenuating mesenteric adiposity and improving cholesterol metabolism and insulin sensitivity. However, multivariate analyses of microbiota and metabolomics data revealed clear divergence of the therapeutic groups. Although both metformin and PKF-275-055 mice displayed significantly decreased Firmicutes/Bacteroidetes ratios, only metformin harboured metabolic health-associated Akkermansia, Parabacteroides and Christensenella. Paradoxically, metformin also reduced α diversity, a metric frequently associated with host metabolic fitness. PKF-275-055 mice displayed elevated levels of butyrate-producing Ruminococcus and acetogen Dorea, with reduced levels of certain plasma sphingomyelin, phosphatidylcholine and lysophosphatidylcholine entities. In turn, metformin reduced levels of acylcarnitines, a functional group associated with systemic metabolic dysfunction. Finally, several associations were identified between metabolites and altered taxa.

CONCLUSIONS

This study represents the first direct comparison of the microbiota-modifying effects of metformin and a DPP-4 inhibitor, and proposes several putative microbial targets both in terms of novel therapeutic development and adverse effect prevention.

Immunometabolism and Pulmonary Infections: Implications for Protective Immune Responses and Host-Directed Therapies

The biology and clinical efficacy of immune cells from patients with infectious diseases or cancer are associated with metabolic programming. Host immune- and stromal-cell genetic and epigenetic signatures in response to the invading pathogen shape disease pathophysiology and disease outcomes. Directly linked to the immunometabolic axis is the role of the host microbiome, which is also discussed here in the context of productive immune responses to lung infections. We also present host-directed therapies (HDT) as a clinically viable strategy to refocus dysregulated immunometabolism in patients with infectious diseases, which requires validation in early phase clinical trials as adjuncts to conventional antimicrobial therapy. These efforts are expected to be continuously supported by newly generated basic and translational research data to gain a better understanding of disease pathology while devising new molecularly defined platforms and therapeutic options to improve the treatment of patients with pulmonary infections, particularly in relation to multidrug-resistant pathogens.

Host-directed therapies to combat tuberculosis and associated non-communicable diseases

Mycobacterium tuberculosis (Mtb) has coevolved with a human host to evade and exploit the immune system in multiple ways. Mtb is an enormously successful human pathogen that can remain undetected in hosts for decades without causing clinical disease. While tuberculosis (TB) represents a perfect prototype of host-pathogen interaction, it remains a major challenge to develop new therapies to combat mycobacterial infections. Additionally, recent studies emphasize on comorbidity of TB with different non-communicable diseases (NCDs), highlighting the impact of demographic and lifestyle changes on the global burden of TB. In the recent past, host-directed therapies have emerged as a novel and promising approach to treating TB. Drugs modulating host responses are likely to avoid the development of bacterial resistance which is a major public health concern for TB treatment. Interestingly, many of these drugs also form treatment strategies for non-communicable diseases. In general, technological advances along with novel host-directed therapies may open an exciting and promising research area, which can eventually deliver effective TB treatment as well as curtail the emergent synergy with NCDs.

Evaluation of metformin in combination with rifampicin containing antituberculosis therapy in patients with new, smear-positive pulmonary tuberculosis (METRIF): study protocol for a randomised clinical trial

INTRODUCTION

Shorter duration of treatment for the management of drug-susceptible pulmonary tuberculosis (TB) would be a significant improvement in the care of patients suffering from the disease. Besides newer drugs and regimens, other modalities like host-directed therapy are also being suggested to reach this goal. This study's objective is to assess the efficacy and safety of metformin-containing anti-TB treatment (ATT) regimen in comparison to the standard 6-month ATT regimen in the treatment of patients with newly diagnosed sputum smear-positive drug-sensitive pulmonary TB.

METHODS AND ANALYSIS

We are conducting a multicentric, randomised open-label controlled clinical trial to achieve the study objective. The intervention group will receive isoniazid (H), rifampicin (R), ethambutol (E) and pyrazinamide (Z) along with 1000 mg of daily metformin (Met) for the first 2 months while the control group will receive only HRZE. After 2 months, both the groups will receive HRE daily for 4 months. The primary endpoint is time to sputum culture conversion. Secondary endpoints will include time to detection of Mycobacterium tuberculosis in sputum, pharmacokinetics and pharmacogenomics of study drugs, drug-drug interactions, safety and tolerability of the various combinations and measurement of autophagy and immune responses in the study participants.

ETHICS AND DISSEMINATION

The ethics committee of the participating institutes have approved the study. Results from this trial will contribute to evidence towards constructing a shorter, effective and safe regimen for patients with TB. The results will be shared widely with the National Programme managers, policymakers and stakeholders through open access publications, dissemination meetings, conference abstracts and policy briefs. This is expected to provide a new standard of care for drug-sensitive patients with pulmonary TB who will not only reduce the number of clinic visits and lost to follow-up of patients from treatment but also reduce the burden on the healthcare system.

TRIAL REGISTRATION NUMBER

CTRI/2018/01/011176; Pre-results.

Metformin as a host-directed therapeutic in tuberculosis: Is there a promise?

To complement the development of new or repurposed drugs for improving the treatment outcomes of drug-susceptible and drug-resistant tuberculosis, current insight also focuses on the use of host-directed therapy. Metformin, a drug often used in the management of type 2 diabetes mellitus, has attracted attention by virtue of its favourable activity as an adjunctive agent against tuberculosis, discovered through laboratory and clinical studies. To definitively establish its role as a host-directed therapeutic in tuberculosis, more preclinical and clinical research is still required to better delineate its mechanism(s) of action and optimal clinical use.

The Effect of Metformin in Experimentally Induced Animal Models of Epileptic Seizure

Background

Epilepsy is one of the common neurological illnesses which affects millions of individuals globally. Although the majority of epileptic patients have a good response for the currently available antiepileptic drugs (AEDs), about 30-40% of epileptic patients are developing resistance. In addition to low safety profiles of most of existing AEDs, there is no AED available for curative or disease-modifying actions for epilepsy so far.

Objectives

This systematic review is intended to evaluate the effect of metformin in acute and chronic animal models of an epileptic seizure.

Methods

We searched PubMed, SCOPUS, Sciences Direct, and grey literature in order to explore articles published in English from January 2010 to November 2018, using key terms “epilepsy,” “seizure,” “metformin,” “oral hypoglycemic agents,” and “oral antidiabetic drugs”. The qualities of all the included articles were assessed according to the Collaborative Approach to Meta-Analysis and Review of Animal Data from Experimental Studies (CAMARADES).

Results

Out of six hundred fifty original articles retrieved, eleven of them fulfilled the inclusion criteria and were included for final qualitative analysis. In these studies, metformin showed to control seizure attacks by attenuating seizure generation, delaying the onset of epilepsy, reducing hippocampal neuronal loss, and averting cognitive impairments in both acute and chronic models of an epileptic seizure. The possible mechanisms for its antiseizure or antiepileptic action might be due to activation of AMPK, antiapoptotic, antineuroinflammatory, and antioxidant properties, which possibly modify disease progression through affecting epileptogenesis.

Conclusion

This review revealed the benefits of metformin in alleviating symptoms of epileptic seizure and modifying different cellular and molecular changes that affect the natural history of the disease in addition to its good safety profile.

Improving treatment outcomes for MDR-TB - Novel host-directed therapies and personalised medicine of the future

Multidrug-resistant TB (MDR-TB) is a major threat to global health security. In 2017, only 50% of patients with MDR-TB who received WHO-recommended treatment were cured. Most MDR-TB patients who recover continue to suffer from functional disability due to long-term lung damage. Whilst new MDR-TB treatment regimens are becoming available, conventional drug therapies need to be complemented with host-directed therapies (HDTs) to reduce tissue damage and improve functional treatment outcomes. This viewpoint highlights recent data on biomarkers, immune cells, circulating effector molecules and genetics which could be utilised for developing personalised HDTs. Novel technologies currently used for cancer therapy which could facilitate in-depth understanding of host genetics and the microbiome in patients with MDR-TB are discussed. Against this background, personalised cell-based HDTs for adjunct MDR-TB treatment to improve clinical outcomes are proposed as a possibility for complementing standard therapy and other HDT agents. Insights into the molecular biology of the mechanisms of action of cellular HDTs may also aid to devise non-cell-based therapies targeting defined inflammatory pathway(s) in Mtb-driven immunopathology.

Metformin use is associated with a low risk of tuberculosis among newly diagnosed diabetes mellitus patients with normal renal function: A nationwide cohort study with validated diagnostic criteria

Human studies on the use of metformin as host-directed therapy (HDT) for tuberculosis (TB) are rare. We performed a nationwide cohort study to evaluate the effect of metformin on mitigating the risk of active TB among patients with diabetes mellitus (DM). Among newly diagnosed DM patients identified in the Taiwan National Health Insurance Research Database, metformin users, defined on the basis of >90 cumulative defined daily doses within 1 year, and propensity-score-matched metformin nonusers were selected. The primary outcome was incident TB, identified using diagnostic criteria validated by real patient data at a medical center. Independent predictors were investigated using Cox regression analysis. Similar analysis was performed in a subpopulation without a history of hypertensive nephropathy and renal replacement therapy. A total of 88,866 metformin users and 88,866 propensity-score-matched nonusers were selected. Validation results showed that the TB diagnostic criteria had a sensitivity of 99.13% and specificity of 99.90%. During follow-up, 707 metformin users and 807 nonusers developed active TB. Metformin use was independently associated with a lower risk of incident TB (hazard ratio [HR]: 0.84 [0.74-0.96]). TB risk was lower in high-dose metformin users than in low-dose users (HR: 0.83 [0.72-0.97]). The effect of metformin remained when analysis was restricted in the subpopulation without renal function impairment. Newly diagnosed diabetic patients without contraindication should receive metformin as an anti-diabetic medication, with potential additional benefit against TB.

The Synergistic Effects of the Glutathione Precursor, NAC and First-Line Antibiotics in the Granulomatous Response Against Mycobacterium tuberculosis

Mycobacterium tuberculosis (M. tb), the causative bacterial agent responsible for tuberculosis (TB) continues to afflict millions of people worldwide. Although the human immune system plays a critical role in containing M. tb infection, elimination proves immensely more challenging. Consequently, there has been a worldwide effort to eradicate, and limit the spread of M. tb through the conventional use of first-line antibiotics. Unfortunately, with the emergence of drug resistant and multi-drug resistant strains of M. tb the archetypical antibiotics no longer provide the same ascendancy as they once did. Furthermore, when administered, these first-line antibiotics commonly present severe complications and side effects. The biological antioxidant glutathione (GSH) however, has been demonstrated to have a profound mycobactericidal effect with no reported adverse consequences. Therefore, we examined if N-Acetyl Cysteine (NAC), the molecular precursor to GSH, when supplemented in combination with suboptimal levels of standalone first-line antibiotics would be sufficient to completely clear M. tb infection within in vitro derived granulomas from healthy subjects and individuals with type 2 diabetes (T2DM). Our results revealed that by virtue of immune modulation, the addition of NAC to subprime levels of isoniazid (INH) and rifampicin (RIF) was indeed capable of inducing complete clearance of M. tb among healthy individuals.