The Risk of TB in Patients With Type 2 Diabetes Initiating Metformin vs Sulfonylurea Treatment

Effect of Metformin on systemic chemokine responses during anti-tuberculosis chemotherapy

BACKGROUND

Metformin (MET), by boosting immunity, has been suggested as a host-adjunctive therapy to anti-tuberculosis treatment (ATT).

METHODS

We evaluated whether adding MET to the standard ATT can alter the host chemokine response. We investigated the influence of metformin on the plasma levels of a wide panel of chemokines in a group of active tuberculosis patients before treatment, at 2nd month of ATT and at 6-months of ATT as part of our clinical study to examine the effect of metformin on ATT.

RESULTS

Our results demonstrated that addition of metformin resulted in diminished CC (CCL1 and CCL3) and CXC (CXCL-2 and CXCL-10) chemokines in MET arm as compared to non-MET arm at the 2nd month and 6th month of ATT. In addition to this, MET arm showed significantly diminished chemokines in individuals with high bacterial burden and cavitary disease.

CONCLUSION

Our current data suggest that metformin alters chemokines responses that could potentially curb excessive inflammation during ATT.

Metformin reduces the risk of poor treatment outcomes among individuals with rifampicin-resistant tuberculosis and type-2 diabetes mellitus

We conducted a retrospective cohort study among individuals with rifampicin-resistant tuberculosis and diabetes to determine the association between metformin use and tuberculosis treatment outcomes. We found that individuals with metformin use had a significantly lower risk of poor tuberculosis treatment outcomes (adjusted RR=0.25, 95%CI 0.06 - 0.95) compared to those without.

Metformin and the risks of cellulitis, foot infections, and amputation in patients with type 2 diabetes

BACKGROUND

Patients with diabetes tend to have cellulitis, foot infections, and amputation. We conducted this research to compare the risks of cellulitis, foot infections, and amputation between metformin no-use and use in persons with type 2 diabetes.

METHODS

Using propensity score matching, we identified 23 234 pairs of metformin nonusers and users from the National Health Insurance Research Database of Taiwan, since January 1, 2000, to December 31, 2017. Cox proportional hazards models were adopted to examine the risks of incident cellulitis, recurrent cellulitis, foot infections, and amputation between metformin use and no-use.

RESULTS

The mean follow-up period of metformin use and no-use was 6.31 (3.93) and 5.54 (3.97) years, respectively. Compared with metformin no-use, the adjusted hazard ratio and 95% confidence interval for metformin use in cellulitis development, recurrent cellulitis, foot infections, and amputation were 1.08 (1.04-1.12), 1.33 (1.14-1.55), 1.91 (1.75-2.09), and 1.88 (1.35-2.62), respectively. The longer cumulative duration of metformin usage had association with higher risks of these outcomes than metformin no-use.

CONCLUSION

This population-based cohort study revealed that metformin use had association with significantly higher risks of incident cellulitis, recurrent cellulitis, foot infections, and amputation than metformin no-use in patients with type 2 diabetes.

Relationship between metformin use and mortality in tuberculosis patients with diabetes: a nationwide cohort study

BACKGROUND/AIMS

To determine whether metformin, which is considered a host-directed therapy for tuberculosis (TB), is effective in improving the prognosis of patients with TB and diabetes mellitus (DM), who have higher mortality than those without DM.

METHODS

This cohort study included patients who were registered as having TB in the National Tuberculosis Surveillance System. The medical and death records of matched patients were obtained from the National Health Information Database and Statistics Korea, respectively, and data from 2011 to 2017 were collected retrospectively. We classified patients according to metformin use among participants who used diabetes drugs for more than 28 days. The primary outcome was all-cause mortality during TB treatment. Double propensity score adjustment was applied to reduce the effects of confounding and multivariable Cox proportional hazard models were used to estimate adjusted hazard ratio (aHR) with 95% confidence interval (CI).

RESULTS

The all-cause mortality rate during TB treatment was lower (9.5% vs. 12.4%, p < 0.01) in the metformin user group. The hazard of death due to all causes after double propensity score adjustment was also lower in the metformin user group (aHR 0.76, 95% CI 0.67-0.86, p < 0.01). There was no significant difference in mortality between metformin users and non-users for TB-related deaths (p = 0.22); however, there was a significant difference in the non-TB-related deaths (p < 0.01).

CONCLUSION

Metformin use in patients with TB-DM co-prevalence is associated with reduced all-cause mortality, suggesting the potential for metformin adjuvant therapy in these patients.

Interactive effect of oral anti-hyperglycaemic or anti-hypertensive drugs on the inhibitory and bactericidal activity of first line anti-TB drugs against M. tuberculosis

Co-existence of life style disorders, like, Diabetes or Hypertension, increases risk of, treatment failure, deaths and developing drug-resistant TB. Concomitant administration of drugs to treat dual/multi-morbidities may alter their effectiveness, in additive/synergistic or adverse/antagonistic manner. We evaluated interactive effect of 7 anti-hyperglycaemic (HG) and 6 anti-hypertensive (HT) drugs on the inhibitory (MICs) and bactericidal (% killing of intracellular bacilli) activities of anti-TB drugs, Isoniazid (INH), Rifampicin (RFM), Ethambutol (EMB) and Streptomycin (STR) against M. tuberculosis. Five anti-HG drugs, namely, Acarbose, Acetohexamide, Glyburide, Repaglinide and Sitagliptin imparted either 'additive' or 'no effect' on the activities (inhibition or % killing) of all the four anti-TB drugs, as evident by their lower FICs (Fractional Inhibitory concentrations) and higher bacterial killing in combination. Metformin and Rosiglitazone, however, exerted adverse effect on the Ethambutol (FICs >2.0). All the six anti-HT drugs, namely, Atenolol, Hydrochlorothiazide, Ramipril, Valsartan, Nifedipine and Verapamil exerted either 'additive'/'synergistic' or 'no effect' on the activities of anti-TB drugs. These findings may help clinicians to select safe and helpful anti-HG or anti-HT drugs for TB patients, if, suffering with diabetes or hypertension like co-morbidities and receiving DOTs (a set regimen for the treatment of TB based on the WHO guidelines).

Stratification of Nontuberculous Mycobacterial Disease Risk in Type 2 Diabetes Based on Metformin Use: a Population-Based Cohort Study in South Korea

In a 1:4 case-control matched analysis of data from a nationwide population-based cohort in South Korea, we evaluated whether metformin use mitigates the risk of nontuberculous mycobacterial disease in patients with type 2 diabetes. Multivariable analysis revealed no significant association of metformin use with a diminished risk for incident nontuberculous mycobacterial disease in patients with type 2 diabetes.

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 Oral Antidiabetic Drugs on Tuberculosis Risk and Treatment Outcomes: Systematic Review and Meta-Analysis

Tuberculosis and diabetes mellitus are two global pandemics and rising public health problems. Recent studies suggest that oral antidiabetic drugs (OADs) could reduce the risk of tuberculosis and improve clinical outcomes. However, the evidence is controversial. Therefore, we aimed to assess the effect of OADs on the risk of tuberculosis and treatment outcomes. We systematically searched for six databases from inception to 31 August 2022. We followed a predefined PICO/PECO strategy and included two randomized controlled trials and sixteen observational studies. This study collects 1,109,660 participants, 908,211 diabetic patients, and at least 13,841 tuberculosis cases. Our results show that metformin decreases the risk of active tuberculosis by 40% (RR 0.60; 95% CI 0.47-0.77) in diabetic patients. In addition, metformin exhibits a dose-response gradient (medium doses reduce the risk of active tuberculosis by 45%, while high doses reduce this risk by 52%). On the other hand, DPP IV inhibitors increase the risk of active tuberculosis by 43% (RR 1.43; 95% CI 1.02-2.02). Subgroup analysis showed that study design and metformin dose accounted for the heterogeneity. We conclude that metformin significantly protects against active tuberculosis among diabetic patients. On the contrary, DPP IV inhibitors could increase the risk of developing active tuberculosis.

Immunologic and imaging signatures in post tuberculosis lung disease

Post Tuberculosis Lung Disease (PTLD) affects millions of tuberculosis survivors and is a global health burden. The immune mechanisms that drive PTLD are complex and have historically been under investigated. Here, we discuss two immune-mediated paradigms that could drive human PTLD. We review the characteristics of a fibrotic granuloma that favors the development of PTLD via an abundance of T-helper-2 and T-regulatory cells and an upregulation of TGF-β mediated collagen deposition. Next, we discuss the post-primary tuberculosis paradigm and the complex mixture of caseous pneumonia, cavity formation and fibrosis that can also lead to PTLD. We review the delicate balance between cellular subsets and cytokines of the innate and adaptive immune system in conjunction with host-derived proteases that can perpetuate the parenchymal lung damage seen in PTLD. Next, we discuss the role of novel host directed therapies (HDT) to limit the development of PTLD and in particular, the recent repurposing of established medications such as statins, metformin and doxycycline. Finally, we review the emerging role of novel imaging techniques as a non-invasive modality for the early recognition of PTLD. While access to computed tomography imaging is unlikely to be available widely in countries with a high TB burden, its use in research settings can help phenotype PTLD. Due to a lack of disease-specific biomarkers and controlled clinical trials, there are currently no evidence-based recommendations for the management of PTLD. It is likely that an integrated antifibrotic strategy that could simultaneously target inflammatory and pro-fibrotic pathways will probably emerge as a successful way to treat this complex condition. In a disease spectrum as wide as PTLD, a single immunologic or radiographic marker may not be sufficient and a combination is more likely to be a successful surrogate that could aid in the development of successful HDTs.

Metformin: Is it a drug for all reasons and diseases?

Metformin was first used to treat type 2 diabetes in the late 1950s and in 2022 remains the first-choice drug used daily by approximately 150 million people. An accumulation of positive pre-clinical and clinical data has stimulated interest in re-purposing metformin to treat a variety of diseases including COVID-19. In polycystic ovary syndrome metformin improves insulin sensitivity. In type 1 diabetes metformin may help reduce the insulin dose. Meta-analysis and data from pre-clinical and clinical studies link metformin to a reduction in the incidence of cancer. Clinical trials, including MILES (Metformin In Longevity Study), and TAME (Targeting Aging with Metformin), have been designed to determine if metformin can offset aging and extend lifespan. Pre-clinical and clinical data suggest that metformin, via suppression of pro-inflammatory pathways, protection of mitochondria and vascular function, and direct actions on neuronal stem cells, may protect against neurodegenerative diseases. Metformin has also been studied for its anti-bacterial, -viral, -malaria efficacy. Collectively, these data raise the question: Is metformin a drug for all diseases? It remains unclear as to whether all of these putative beneficial effects are secondary to its actions as an anti-hyperglycemic and insulin-sensitizing drug, or result from other cellular actions, including inhibition of mTOR (mammalian target for rapamycin), or direct anti-viral actions. Clarification is also sought as to whether data from ex vivo studies based on the use of high concentrations of metformin can be translated into clinical benefits, or whether they reflect a 'Paracelsus' effect. The environmental impact of metformin, a drug with no known metabolites, is another emerging issue that has been linked to endocrine disruption in fish, and extensive use in T2D has also raised concerns over effects on human reproduction. The objectives for this review are to: 1) evaluate the putative mechanism(s) of action of metformin; 2) analyze the controversial evidence for metformin's effectiveness in the treatment of diseases other than type 2 diabetes; 3) assess the reproducibility of the data, and finally 4) reach an informed conclusion as to whether metformin is a drug for all diseases and reasons. We conclude that the primary clinical benefits of metformin result from its insulin-sensitizing and antihyperglycaemic effects that secondarily contribute to a reduced risk of a number of diseases and thereby enhancing healthspan. However, benefits like improving vascular endothelial function that are independent of effects on glucose homeostasis add to metformin's therapeutic actions.

Role of Metformin in Morbidity and Mortality Associated with Urinary Tract Infections in Patients with Type 2 Diabetes

We conducted this study to compare the morbidity and mortality associated with UTI and sepsis, between metformin users and nonusers in patients with diabetes. As such, 40,774 propensity score-matched metformin users and nonusers were identified from Taiwan’s National Health Insurance Research Database, between 1 January 2000 and 31 December 2017. We adopted the Cox proportional hazards model with robust standard error estimates for comparing the risks of UTI, sepsis, and death due to UTI or sepsis, in patients with T2DM. Compared with the nonuse of metformin, the aHRs (95% CI) for metformin use in UTI, recurrent UTI, sepsis, and death due to UTI or sepsis were 1.06 (0.98, 1.15), 1.08 (0.97, 1.2), 1.01 (0.97, 1.06), and 0.58 (0.42, 0.8), respectively. The cumulative incidence of death due to UTI or sepsis was significantly lower in metformin users than in nonusers (p = 0.002). A longer cumulative duration of metformin use had a lower aHR in the risk of death due to UTI or sepsis than metformin nonuse. In patients with T2DM, metformin use showed no significant differences in the risks of UTI, recurrent UTI, or sepsis. However, it was associated with a lower risk of death due to UTI or sepsis than metformin nonuse.

Association of metformin use with Alzheimer's disease in patients with newly diagnosed type 2 diabetes: a population-based nested case-control study

Metformin reduces insulin resistance, which constitutes a pathophysiological connection of diabetes with Alzheimer’s disease (AD), but the evidence of metformin on AD development was still insufficient and conflicting. We investigated AD risk in patients with newly diagnosed type 2 DM treated with metformin. This retrospective, observational, nested case–control study included patients with newly diagnosed type 2 DM obtained from the Korean National Health Insurance Service DM cohort (2002–2017). Among 70,499 dementia-free DM patients, 1675 AD cases were matched to 8375 controls for age, sex, and DM onset and duration. The association between AD and metformin was analyzed by multivariable regression analyses, adjusted for comorbidities and cardiometabolic risk profile. Metformin use was associated with an increased odds of AD (adjusted odds ratio [AOR] 1.50; 95% CI 1.23–1.83). The risk of AD was higher in patients with a longer DM duration. Furthermore, AD risk was significantly high in DM patients with depression (AOR 2.05; 95% CI 1.02–4.12). Given the large number of patients with DM who are taking metformin worldwide, a double-blinded, prospective study is required to determine the long-term cognitive safety of metformin.

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.

Host Immune-Metabolic Adaptations Upon Mycobacterial Infections and Associated Co-Morbidities

Mycobacterial diseases are a major public health challenge. Their causative agents include, in order of impact, members of the Mycobacterium tuberculosis complex (causing tuberculosis), Mycobacterium leprae (causing leprosy), and non-tuberculous mycobacterial pathogens including Mycobacterium ulcerans. Macrophages are mycobacterial targets and they play an essential role in the host immune response to mycobacteria. This review aims to provide a comprehensive understanding of the immune-metabolic adaptations of the macrophage to mycobacterial infections. This metabolic rewiring involves changes in glycolysis and oxidative metabolism, as well as in the use of fatty acids and that of metals such as iron, zinc and copper. The macrophage metabolic adaptations result in changes in intracellular metabolites, which can post-translationally modify proteins including histones, with potential for shaping the epigenetic landscape. This review will also cover how critical tuberculosis co-morbidities such as smoking, diabetes and HIV infection shape host metabolic responses and impact disease outcome. Finally, we will explore how the immune-metabolic knowledge gained in the last decades can be harnessed towards the design of novel diagnostic and therapeutic tools, as well as vaccines.

Recent Advances in the Development of Type 2 Sodium-Glucose Cotransporter Inhibitors for the Treatment of Type 2 Diabetes Mellitus

BACKGROUND

Type 2 diabetes mellitus (T2DM) is one of the most serious and prevalent diseases worldwide. In the last decade, type 2 sodium-glucose cotransporter inhibitors (iSGLT2) were approved as alternative drugs for the pharmacological treatment of T2DM. The anti-hyperglycemic mechanism of action of these drugs involves glycosuria. In addition, SGLT2 inhibitors cause beneficial effects such as weight loss, a decrease in blood pressure, and others.

OBJECTIVE

This review aimed to describe the origin of SGLT2 inhibitors and analyze their recent development in preclinical and clinical trials.

RESULTS

In 2013, the FDA approved SGLT2 inhibitors as a new alternative for the treatment of T2DM. These drugs have shown good tolerance with few adverse effects in clinical trials. Additionally, new potential anti-T2DM agents based on iSGLT2 (O-, C-, and N-glucosides) have exhibited a favorable profile in preclinical evaluations, making them candidates for advanced clinical trials.

CONCLUSION

The clinical results of SGLT2 inhibitors show the importance of this drug class as new anti-T2DM agents with a potential dual effect. Additionally, the preclinical results of SGLT2 inhibitors favor the design and development of more selective new agents. However, several adverse effects could be a potential risk for patients.

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.

Metformin enhances anti-mycobacterial responses by educating CD8+ T-cell immunometabolic circuits

Patients with type 2 diabetes (T2D) have a lower risk of Mycobacterium tuberculosis infection, progression from infection to tuberculosis (TB) disease, TB morality and TB recurrence, when being treated with metformin. However, a detailed mechanistic understanding of these protective effects is lacking. Here, we use mass cytometry to show that metformin treatment expands a population of memory-like antigen-inexperienced CD8+CXCR3+ T cells in naive mice, and in healthy individuals and patients with T2D. Metformin-educated CD8+ T cells have increased (i) mitochondrial mass, oxidative phosphorylation, and fatty acid oxidation; (ii) survival capacity; and (iii) anti-mycobacterial properties. CD8+ T cells from Cxcr3-/- mice do not exhibit this metformin-mediated metabolic programming. In BCG-vaccinated mice and guinea pigs, metformin enhances immunogenicity and protective efficacy against M. tuberculosis challenge. Collectively, these results demonstrate an important function of CD8+ T cells in metformin-derived host metabolic-fitness towards M. tuberculosis infection.

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.

Metformin use and post-exposure incident tuberculosis: a nationwide tuberculosis-contact cohort study in Taiwan

Patients with diabetes mellitus are susceptible to active tuberculosis (TB) and latent TB infection (LTBI) [1–3]. Close contact with patients with infectious TB is associated with an increased risk of having coprevalent TB or developing incident TB [4, 5]. However, information on the burden of incident TB in contacts with underlying diabetes is limited. Considering post-exposure TB in patients with diabetes, metformin has demonstrated anti-TB effects in preclinical studies and association with a low LTBI prevalence in a cross-sectional survey [6, 7]. Despite metformin's wide use and correlation with a lower TB risk in patients with type 2 diabetes (T2D) [8], the impact of metformin use during TB exposure on subsequent TB risk has not been thoroughly investigated. We aimed to obtain the rate of post-exposure incident TB, but not coprevalent TB, in T2D patients and evaluate whether TB risk can be modified by metformin use during the TB-exposure period.

This TB contact cohort study showed that the risk of incident TB, not coprevalent TB, was highest in the diabetes group without metformin use during TB exposure, followed by the nondiabetes population, and was lowest in the diabetes group with metformin usehttps://bit.ly/3fpJyF0

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.

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.

Metformin Alters Human Host Responses to Mycobacterium tuberculosis in Healthy Subjects

BACKGROUND

Metformin, the most widely administered diabetes drug, has been proposed as a candidate adjunctive host-directed therapy for tuberculosis, but little is known about its effects on human host responses to Mycobacterium tuberculosis.

METHODS

We investigated in vitro and in vivo effects of metformin in humans.

RESULTS

Metformin added to peripheral blood mononuclear cells from healthy volunteers enhanced in vitro cellular metabolism while inhibiting the mammalian target of rapamycin targets p70S6K and 4EBP1, with decreased cytokine production and cellular proliferation and increased phagocytosis activity. Metformin administered to healthy human volunteers led to significant downregulation of genes involved in oxidative phosphorylation, mammalian target of rapamycin signaling, and type I interferon response pathways, particularly following stimulation with M. tuberculosis, and upregulation of genes involved in phagocytosis and reactive oxygen species production was increased. These in vivo effects were accompanied by a metformin-induced shift in myeloid cells from classical to nonclassical monocytes. At a functional level, metformin lowered ex vivo production of tumor necrosis factor α, interferon γ, and interleukin 1β but increased phagocytosis activity and reactive oxygen species production.

CONCLUSION

Metformin has a range of potentially beneficial effects on cellular metabolism, immune function, and gene transcription involved in innate host responses to M. tuberculosis.

Opposite effects of statins on the risk of tuberculosis and herpes zoster in patients with diabetes: A population-based cohort study

It remains uncertain whether statin use is associated with the risks of tuberculosis (TB) and herpes zoster in patients with type 2 diabetes. This study aims to assess the effects of statins vs nonstatin lipid-lowering agents on the risk of these infectious diseases in patients with diabetes.

METHODS

Participants in the Taiwan National Health Insurance Research Database diagnosed with type 2 diabetes in 2001-2013 were classified as statin users, nonstatin users and lipid-lowering drug-free groups. Participants were observed for incident TB and herpes zoster from diabetes diagnosis until treatment crossover or December 2013. Statin user and nonstatin user were the time-dependent variables in Cox regression analysis.

RESULTS

Over 240 782 person-years of observation, statin users (n = 17 696) were associated with a lower TB risk than nonstatin users (n = 5327) and the drug-free group (n = 22 316) (adjusted hazard ratio [aHR]: 0.66; 95% confidence interval [CI]: 0.44-0.99 and aHR: 0.57; 95% CI: 0.44-0.73). Compared with nonstatin users, statin users showed a dose-dependent association with TB risk (low-potency statin users, aHR: 0.692; 95% CI: 0.455-1.053; high-potency users, aHR: 0.491; 95% CI: 0.241-0.999). Statin users presented with a higher risk of herpes zoster than nonstatin users and the drug-free group (aHR: 1.23; 95% CI: 1.01-1.50 and aHR: 1.20; 95% CI: 1.09-1.33). The risks of TB and herpes zoster were not statistically different between nonstatin users and the drug-free group.

CONCLUSION

Compared with nonstatin drugs, statin use was specifically associated with a decreased risk of TB but a moderately increased risk of herpes zoster in this cohort study.

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.

Impact of metformin on the risk and treatment outcomes of tuberculosis in diabetics: a systematic review

BACKGROUND

Tuberculosis (TB) remains one of the infectious diseases with a leading cause of death among adults worldwide. Metformin, a first-line medication for the treatment of type 2 diabetes, may have potential for treating TB. The aims of the present systematic review were to evaluate the impact of metformin prescription on the risk of tuberculosis diseases, the risk of latent TB infection (LTBI) and treatment outcomes of tuberculosis among patients with diabetic mellitus.

METHODS

Databases were searched through March 2019. Observational studies reporting the effect of metformin prescription on the risk and treatment outcomes of TB were included in the systematic review. We qualitatively analyzed results of included studies, and then pooled estimate effects with 95% confidence intervals (CIs) of different outcome using random-effect meta-analyses.

RESULTS

This systematic review included 6980 cases from 12 observational studies. The meta-analysis suggested that metformin prescription could decrease the risk of TB among diabetics (pooled odds ratio [OR], 0.38; 95%CI, 0.21 to 0.66). Metformin prescription was not related to a lower risk of LTBI (OR, 0.73; 95%CI, 0.30 to 1.79) in patients with diabetes. Metformin medication during the anti-tuberculosis treatment is significantly associated with a smaller TB mortality (OR, 0.47; 95%CI, 0.27 to 0.83), and a higher probability of sputum culture conversion at 2 months of TB disease (OR, 2.72; 95%CI, 1.11 to 6.69) among patients with diabetes. The relapse of TB was not statistically reduced by metformin prescription (OR, 0.55; 95%CI, 0.04 to 8.25) in diabetics.

CONCLUSIONS

According to current observational evidence, metformin prescription significantly reduced the risk of TB in patients with diabetes mellitus. Treatment outcomes of TB disease could also be improved by the metformin medication among diabetics.

The burdens of tuberculosis on patients with malignancy: incidence, mortality and relapse

Population with malignancy is growing worldwide; however, its tuberculosis (TB) burden including remains unclear regarding incidence, mortality, and relapse. We retrieved information and identified patients with malignancy and TB between 2000 and 2015 from the Taiwanese National Health Insurance reimbursement datasets, Taiwan cancer registry and death registration. We analyzed the incidence of new TB in patients with malignancy and their mortality as well as TB recurrence. During study period, we reviewed 1,105,009 patients after exclusion and among them, 19,906 had newly diagnosed TB. The TB incidence in cancer patients divided all TB events increased annually, from 3% in 2000 to 13% in 2015. The standard incidence rates (SIR) were highest in cancer of respiratory tract (5.45), hematology (3.70) and then head and neck area (2.58). The mortality directly due to TB was defined as 0.83% and all-cause mortality were approximately 10.5% at 3 months and 20.56% at 12 months. After completing TB treatment, recurrence was diagnosed in 626 (3.14%), and 1001 (5.03%) patients within the first and the first two years, respectively. In conclusion, the incidence of TB in patients with malignancy increase yearly as well as its proportion within overall cases. The twelve-month all-cause mortality during TB and the two-year recurrence are as high as 20.56% and 5.03%, respectively. It indicates the importance of this population in future TB control, especially for those with malignancy of respiratory tract, and hematology as well as head and neck area.

Pulmonary tuberculous cavities in diabetic patients: Glycemic control is still the dominant factor despite the emerging role of metformin

BACKGROUND

Previous studies have reported an increased risk of cavities in diabetic patients with pulmonary tuberculosis (PTB), which may be associated with poor glycemic control. Cavities have a negative impact on PTB treatment outcomes; however, the possible interaction of other potentially confounding diabetes-related variables regarding pulmonary cavities have not been fully evaluated.

METHODS

We conducted a retrospective cohort study of diabetic patients with culture-proven PTB. The patients' chest X-rays (CXRs) and computed tomography (CT) scans were reviewed to assess the effects of clinical factors, glycosylated hemoglobin (HbA1c) levels, and antidiabetic agents on cavitary lesions.

RESULTS

Among 128 diabetic PTB patients, those with pulmonary cavities on CXRs and CT scans presented younger ages, lack of metformin treatment, and significantly higher HbA1c levels than those without cavities. Multivariate logistic regression analysis revealed significantly higher HbA1c levels in patients with cavities than in those without cavities on CXRs (odds ratio [OR], 1.34; 95% confidence interval [CI], 1.12-1.61) and CT scans (OR, 1.36; 95% CI, 1.13-1.64). Patients with multiple cavities had significantly higher HbA1c levels than those with a single cavity on CT scans (p = 0.002). No significant differences in other variables, including metformin treatment, were noted between the groups.

CONCLUSION

This study suggests that despite multiple potential confounding variables, including metformin use, poor glycemic control is still the dominant risk factor for cavitary lesions in diabetic patients with PTB. Efforts to improve glycemic control in diabetic PTB patients may be of considerable value in facilitating antimycobacterial treatment.

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.

Risk of cardiotoxicity induced by adjuvant anthracycline-based chemotherapy and radiotherapy in young and old Asian women with breast cancer

PURPOSE

The risk of cardiotoxicity induced by adjuvant anthracycline-based chemotherapy (CT) and radiotherapy (RT) is yet to be investigated in a large-scale randomized controlled trial with an adequate sample size of young and old women with breast cancer.

PATIENTS AND METHODS

To compare the occurrence of major heart events (heart failure and coronary artery disease) in patients with breast cancer, 3489 women who underwent surgical resection of the breast tumor were retrospectively selected from the Taiwan National Health Insurance Research Database. The patients were categorized into the following groups based on their treatment modalities: group 1 (n = 1113), no treatment; group 2 (n = 646), adjuvant RT alone; group 3 (n = 705), adjuvant anthracycline-based CT alone; and group 4 (n = 1025), combined adjuvant RT and anthracycline-based CT.

RESULTS

The mean patient age was 50.35 years. Subsequent coronary artery disease and heart failure were identified in 244 (7.0%) and 206 (5.9%) patients, respectively. All three adjuvant therapies were significant independent prognostic factors of major heart events (adjusted hazard ratio [95% confidence interval]: 1.47 [1.24-1.73]; 1.48 [1.25-1.75], and 1.92 [1.65-2.23] in groups 2, 3, and 4, respectively). In patients aged ≥50 years with breast cancer who underwent surgery, the log-rank p values of groups 2 and 3 after adjustment were 0.537 and 0.001, respectively.

CONCLUSION

Adjuvant RT can increase cardiotoxicity in patients with breast cancer, particularly when used in combination with anthracycline-based CT. Therefore, it should be offered with optimal heart-sparing techniques, particularly in younger patients with good prognosis and long life expectancy.

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.

Metformin is associated with a lower risk of active tuberculosis in patients with type 2 diabetes

BACKGROUND AND OBJECTIVE

Metformin is an oral anti-diabetic therapy (ADT) to manage type 2 diabetes mellitus (T2DM), and has been reported to have potential anti-tuberculosis (TB) effects. This study investigates the risk of active TB among persons with T2DM who were treated with various ADT and insulin therapies.

METHODS

We conducted a nationwide population-based cohort study using the Taiwan Longitudinal Health Insurance Database, including 49 028 T2DM patients who were metformin users (n = 44 002) or non-users (n = 5026). A total of 5026 propensity score-matched pairs of metformin users and non-users with T2DM were evaluated from 1998 to 2010. The data were analysed using Cox proportional hazard models.

RESULTS

Patients with T2DM had a significantly higher rate of incident TB than did the control subjects (adjusted hazard ratio: 2.01; 95% confidence interval (95% CI): 1.80-2.25). After adjusting for comorbidities, diabetes complications, ADT type and statin use, metformin use was an independent factor for predicting a reduced risk of active TB (adjusted relative risk (aRR): 0.24; 95% CI: 0.18-0.32). The association between metformin use and active TB risk was also consistent in most subgroup analyses, except for patients with metabolic disorders (aRR: 0.46; 95% CI: 0.11-1.87). This protective effect of metformin was dose-dependent but diminished gradually in the elderly population.

CONCLUSION

Among all types of ADT and insulin therapies, metformin is the only agent with a decreased risk of active TB in the T2DM population. However, this effect was diminished in the elderly population and was not observed in patients with metabolic disorders.