Reduced Mycobacterium tuberculosis association with monocytes from diabetes patients that have poor glucose control

Interaction between type 2 diabetes and past COVID-19 on active tuberculosis

BACKGROUND

The global setback in tuberculosis (TB) prevalence and mortality in the post-COVID-19 era has been partially attributed to pandemic-related disruptions in healthcare systems. The additional biological contribution of COVID-19 to TB is less clear. The goal of this study was to determine if there is an association between COVID-19 in the past 18 months and a new TB episode, and the role played by type 2 diabetes mellitus (DM) comorbidity in this relationship.

METHODS

A cross-sectional study was conducted among 112 new active TB patients and 373 non-TB controls, identified between June 2020 and November 2021 in communities along the Mexican border with Texas. Past COVID-19 was based on self-report or positive serology. Bivariable/multivariable analysis were used to evaluate the odds of new TB in hosts with past COVID-19 and/or DM status.

RESULTS

The odds of new TB were higher among past COVID-19 cases vs. controls, but only significant among DM patients (aOR 2.3). The odds of TB in people with DM was 2.7-fold higher among participants without past COVID-19 and increased to 7.9-fold among those with past COVID-19.

CONCLUSION

DM interacts with past COVID-19 synergistically to magnify the risk of TB. Latent TB screening and prophylactic treatment, if positive, is recommended in past COVID-19 persons with DM. Future studies are warranted with a longitudinal design and larger sample size to confirm our findings.

HUMAN ALVEOLAR MACROPHAGE FUNCTION IS IMPAIRED IN TUBERCULOSIS CONTACTS WITH DIABETES

Type 2 diabetes (T2D) increases susceptibility to tuberculosis (TB) with the underlying mechanisms remaining unknown. To determine whether immune dysfunction in the lung contributes to TB susceptibility, we obtained paired human alveolar macrophages (HAMs) and monocyte-derived macrophages (MDMs) from TB-exposed individuals with/without T2D. Upon infection with Mycobacterium tuberculosis (M.tb), T2D-HAMs had more M.tb growth and produced more TNF. There were fewer neutrophils in the bronchoalveolar lavage of T2D patients which was inversely correlated with M.tb growth. Both T2D-HAMs and MDMs expressed less CD32, with T2D patients having fewer M1-like MDMs. T2D-MDMs produced less IL-1RA and CSF2. Overall M.tb-induced gene expression was delayed in T2D-HAMs, but genes involved in negative regulation of neutrophil migration were upregulated. T2D-HAM DNA was hypermethylated compared to control HAMs, however genes linked to TNF signalling were hypomethylated. We show here the first in-depth analysis of T2D-HAMs providing an explanation for more severe TB in T2D patients.

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.

Diabetes and Infectious Diseases with a Focus on Melioidosis

Diabetes mellitus (DM) leads to impaired innate and adaptive immune responses. This renders individuals with DM highly susceptible to microbial infections such as COVID-19, tuberculosis and melioidosis. Melioidosis is a tropical disease caused by the bacterial pathogen Burkholderia pseudomallei, where diabetes is consistently reported as the most significant risk factor associated with the disease. Type-2 diabetes is observed in 39% of melioidosis patients where the risk of infection is 13-fold higher than non-diabetic individuals. B. pseudomallei is found in the environment and is an opportunistic pathogen in humans, often exhibiting severe clinical manifestations in immunocompromised patients. The pathophysiology of diabetes significantly affects the host immune responses that play a critical role in fighting the infection, such as leukocyte and neutrophil impairment, macrophage and monocyte inhibition and natural killer cell dysfunction. These defects result in delayed recruitment as well as activation of immune cells to target the invading B. pseudomallei. This provides an advantage for the pathogen to survive and adapt within the immunocompromised diabetic patients. Nevertheless, knowledge gaps on diabetes-infectious disease comorbidity, in particular, melioidosis-diabetes comorbidity, need to be filled to fully understand the dysfunctional host immune responses and adaptation of the pathogen under diabetic conditions to guide therapeutic options.

The potential association between metabolic disorders and pulmonary tuberculosis: a Mendelian randomization study

BACKGROUND

Metabolic disorders (MetDs) have been demonstrated to be closely linked to numerous diseases. However, the precise association between MetDs and pulmonary tuberculosis (PTB) remains poorly understood.

METHOD

Summary statistics for exposure and outcomes from genome-wide association studies (GWASs) for exposures and outcomes were obtained from the BioBank Japan Project (BBJ) Gene-exposure dataset. The 14 clinical factors were categorized into three groups: metabolic laboratory markers, blood pressure, and the MetS diagnostic factors. The causal relationship between metabolic factors and PTB were analyzed using two-sample Mendelian Randomization (MR). Additionally, the direct effects on the risk of PTB were investigated through multivariable MR. The primary method employed was the inverse variance-weighted (IVW) model. The sensitivity of this MR analysis was evaluated using MR-Egger regression and the MR-PRESSO global test.

RESULTS

According to the two-sample MR, HDL-C, HbA1c, TP, and DM were positively correlated with the incidence of active TB. According to the multivariable MR, HDL-C (IVW: OR 2.798, 95% CI 1.484-5.274, P = 0.001), LDL (IVW: OR 4.027, 95% CI 1.140-14.219, P = 0.03) and TG (IVW: OR 2.548, 95% CI 1.269-5.115, P = 0.009) were positively correlated with the occurrence of PTB. TC (OR 0.131, 95% CI 0.028-0.607, P = 0.009) was negatively correlated with the occurrence of PTB. We selected BMI, DM, HDL-C, SBP, and TG as the diagnostic factors for metabolic syndrome. DM (IVW, OR 1.219, 95% CI 1.040-1.429 P = 0.014) and HDL-C (IVW, OR 1.380, 95% CI 1.035-1.841, P = 0.028) were directly correlated with the occurrence of PTB.

CONCLUSIONS

This MR study demonstrated that metabolic disorders, mainly hyperglycemia, and dyslipidemia, are associated with the incidence of active pulmonary tuberculosis.

Interaction between type 2 diabetes and past COVID-19 on active tuberculosis

BACKGROUND

The global setback in tuberculosis (TB) prevalence and mortality in the post-COVID-19 era have been partially attributed to pandemic-related disruptions in healthcare systems. The additional biological contribution of COVID-19 to TB is less clear. The goal of this study was to determine if there is an association between COVID-19 in the past 18 months and a new TB episode, and the role played by type 2 diabetes mellitus (DM) comorbidity in this relationship.

METHODS

A cross-sectional study was conducted among 112 new active TB patients and 373 non-TB controls, identified between June 2020 and November 2021 in communities along the Mexican border with Texas. Past COVID-19 was based on self-report or positive serology. Bivariable/multivariable analysis were used to evaluate the odds of new TB in hosts with past COVID-19 and/or DM status.

RESULTS

The odds of new TB were higher among past COVID-19 cases vs. controls, but only significant among DM patients (aOR 2.3). The odds of TB given DM was 2.7-fold among participants without past COVID-19 and increased to 7.9-fold among those with past COVID-19.

CONCLUSION

DM interacts with past COVID-19 synergistically to magnify the risk of TB. Latent TB screening and prophylactic treatment, if positive, is recommended in this COVID-19/DM/latent TB high-risk group.

Evaluation of Systemic Inflammation Before and After Standard Anti-tuberculosis Treatment in Patients With Active Pulmonary Tuberculosis and Diabetes Mellitus

Background Diabetes mellitus (DM) is a common comorbidity of active pulmonary tuberculosis (APTB) that increases the risk of treatment failure during anti-tuberculosis chemotherapy. Evaluating systemic inflammatory response could help determine differences in response to treatment between APTB patients and those with APTB and DM. Methodology To explore changes in systemic inflammation, measured by a set of inflammatory mediators in subjects with APTB and TBDM before and after six months of anti-tuberculosis chemotherapy, 30 APTB and nine TBDM subjects underwent cytokine testing, including interleukin (IL)-6, IL-8, IL-10, interferon-gamma (IFN-γ), tumor necrosis factor-alpha (TNF-α), and transforming growth factor-beta 1 (TGF-β1) by enzyme-linked immunosorbent assay, C-reactive protein by nephelometry, and sialic acid by colorimetric assay at baseline and following six months of standard anti-tuberculosis treatment. Sputum smear microscopy or molecular biology (Xpert MTB/RIF) was used for diagnosis, and sputum smear microscopy was performed monthly during the treatment of the patient with pulmonary tuberculosis to evaluate his evolution. Principal component analysis examined changes in the inflammatory status. Results Both groups showed negative sputum smear microscopy in the sixth month after starting anti-tuberculosis chemotherapy. TGF-β1 was found to be significantly higher in subjects with TBDM before treatment compared to APTB patients (p<0.001), and systemic inflammation continued only in TBDM subjects after treatment (accumulation and persistence of inflammatory mediators like IL-6, IL-8, IL-10, IFN-γ, TNF-α, TGF-β1, C-reactive protein, and sialic acid in blood). On the other hand, the mediators IFN-γ, C-reactive protein, and total sialic acid were found to be most influential in distinguishing pre- and post-treatment inflammatory response in subjects with APTB without DM. Conclusions Inflammatory mediators analyzed in combination, including IFN-γ, CRP, and total sialic acid, may be useful in evaluating the systemic inflammatory response in subjects with APTB and TBDM before and after anti-tuberculosis treatment. Determining these mediators revealed persistent systemic inflammation in TBDM subjects after six months of standard tuberculosis treatment, despite negative sputum smear microscopy results and good glycemic control. This suggests a need for inflammation-modulating therapies during tuberculosis control. Finally, monitoring sputum smear microscopy results alongside the determination of proposed inflammatory mediators (IFN-γ, CRP, and total sialic acid) are effective in evaluating the response to anti-tuberculosis treatment in APTB subjects without DM, warranting further investigation.

The cause-effect relation of tuberculosis on incidence of diabetes mellitus

Tuberculosis (TB) is one of the oldest human diseases and is one of the major causes of mortality and morbidity across the Globe. Mycobacterium tuberculosis (Mtb), the causal agent of TB is one of the most successful pathogens known to mankind. Malnutrition, smoking, co-infection with other pathogens like human immunodeficiency virus (HIV), or conditions like diabetes further aggravate the tuberculosis pathogenesis. The association between type 2 diabetes mellitus (DM) and tuberculosis is well known and the immune-metabolic changes during diabetes are known to cause increased susceptibility to tuberculosis. Many epidemiological studies suggest the occurrence of hyperglycemia during active TB leading to impaired glucose tolerance and insulin resistance. However, the mechanisms underlying these effects is not well understood. In this review, we have described possible causal factors like inflammation, host metabolic changes triggered by tuberculosis that could contribute to the development of insulin resistance and type 2 diabetes. We have also discussed therapeutic management of type 2 diabetes during TB, which may help in designing future strategies to cope with TB-DM cases.

Immunological aspects of host-pathogen crosstalk in the co-pathogenesis of diabetes and latent tuberculosis

Introduction

Diabetes is a potent risk factor for the activation of latent tuberculosis and worsens the tuberculosis (TB) treatment outcome. The major reason for mortality and morbidity in diabetic patients is due to their increased susceptibility to TB. Thus, the study was conducted to understand the crosstalk between M. tuberculosis and its host upon latent tuberculosis infection and under hyperglycemic conditions or diabetes.

Methods

An animal model was employed to study the relationship between latent tuberculosis and diabetes. BCG immunization was done in mice before infection with M. tuberculosis, and latency was confirmed by bacillary load, histopathological changes in the lungs and gene expression of hspX, tgs1, tgs3 and tgs5. Diabetes was then induced by a single high dose of streptozotocin (150 mg/kg body weight). Host factors, like various cytokines and MMPs (Matrix metalloproteinases), which play an important role in the containment of mycobacterial infection were studied in vivo and in vitro.

Results

A murine model of latent TB was developed, which was confirmed by CFU counts (<10⁴ in the lungs and spleen) and granuloma formation in lungs in the latent TB group. Also, the gene expression of hspX, tgs1, and tgs5 was upregulated, and after diabetes induction, blood glucose levels were >200 mg/dl. An in vitro study employing a THP-1 macrophage model of latent and active tuberculosis under normal and high glucose conditions showed that dormant bacilli were better contained in the presence of 5.5 mM glucose concentration as compared with active bacilli. However, the killing and restriction efficiency of macrophages decreased, and CFU counts increased significantly with an increase in glucose concentration.

Discussion

The decreased levels of MCP-1, decreased expression of mmp-9, and increased expression of mmp-1 in the latent group at high glucose concentrations could explain the failure of granuloma formation at high glucose conditions.

The association between diabetes status and latent-TB IGRA levels from a cross-sectional study in eastern China

Background

There is a debate regarding the sensitivity of the QuantiFERON-TB Gold In-Tube (QFT) among people with diabetes, and prior studies have shown heterogeneous results. We evaluated whether the QFT TB antigen was modified among persons with differing diabetes status and other related risk factors.

Methods

A cross-sectional study of 5,302 people was conducted to screen latent tuberculosis infection (LTBI) in eastern China. The QFT assay was performed as an indicator of LTBI. Fasting plasma glucose (FPG) was collected from each participant; the definition of diabetes followed the guidelines from the American Diabetes Association. Participants were classified into normoglycemia, prediabetes, undiagnosed diabetes, and previously diagnosed diabetes to evaluate the relationship between the QFT TB antigen and distinct diabetes status.

Results

TB antigen values from the QFT were statistically different among participants with differing diabetes status (P = 0.008). Persons with undiagnosed diabetes had a higher TB antigen value (0.96 ± 0.20) than persons with normoglycemia (0.50 ± 0.02, P < 0.05). However, the TB antigen values demonstrated no significant difference among the four different diabetic groups when stratified by the standard cutoff for the QFT (P = 0.492 for the positive group and P = 0.368 for the negative group). In a linear regression model, we found that FPG, age, and smoking were positively associated with the QFT TB antigen value (P = 0.017, P < 0.001, and P < 0.001).

Conclusions

Diabetes status had little influence on the level of QFT TB antigen response among IGRA-positive persons. However, FPG, old age, and smoking were important risk factors for increasing levels of QFT TB antigen.

Prevalence of Pulmonary Tuberculosis in Diabetic Patients: Epidemiology, Immunological Basis, and Its Amalgamated Management

Tuberculosis (TB) is one of the most widespread and infectious diseases in the world, which is brought on by Mycobacterium tuberculosis (MTB). Most infection lacks traditional signs. Latent TB is the name given to this ailment. Of these latent infections, 10% become active and cause illness. Fever, night sweats, a prolonged cough with blood-containing mucus, and weight loss are common signs of active TB infection. Diabetes, on the other hand, is a group of metabolic illnesses characterized by elevated serum glucose levels. It is a chronic metabolic condition brought on by a deficiency in insulin secretion or resistance. It is of two types, that is, type 1 and type 2. Among all the cases of diabetes, the occurrence of type 2 is more common and less fatal than type 1. The prevalence of diabetes is currently increasing in low- and middle-income nations. As both diabetes and TB come under the most widespread chronic condition; therefore, their combined effect is evaluated. In recent years, the higher occurrence of TB in patients with hyperglycemia has come to light. People with elevated blood glucose levels exhibit several risk factors that make them more vulnerable to contracting TB. This review provides information on epidemiological data about the prevalence of TB in patients with hyperglycemia. In addition, this paper discusses the immunological underpinnings of TB development in patients with diabetes mellitus and how glycemic management reduces the risk of TB infection. It illustrates how the clinical signs and radiographic evidence of TB differ between people with diabetes and healthy people and mentions diabetes and TB combined management.

Increased frequency of CD14+HLA-DR-/low cells in type 2 diabetes patients with poor glycemic control

AIMS

Type 2 diabetes (T2DM) is associated with alterations of the immune response and T2DM patients have an increased risk for infections and certain sorts of cancers. Although CD14⁺HLA-DR^-/low cells have emerged as important mediators of immunosuppression in several pathologies, including cancer and non-malignant diseases, the presence of these cells in T2DM is not fully characterized.

METHODS

In this study, we evaluated the frequency of CD14⁺HLA-DR^-/low cells in non-obese T2DM patients and their association with glycemic control. Peripheral blood mononuclear cells were isolated from healthy controls (HC, n = 24) and non-obese T2DM patients (n = 25), the population was evaluated by flow cytometry, and an analysis of correlation between cell frequencies and clinical variables was performed.

RESULTS

CD14⁺HLA-DR^-/low monocytes were expanded in patients with T2DM compared to HC regardless of weight. Among the subjects with T2DM, the frequency of CD14⁺HLA-DR^-/low was higher in patients with poor glycemic control (HbA1c > 9%) compared to those with better glycemic control (HbA1c < 9%) and, positively correlated with the years since the diagnosis of T2DM, the age of the patients and the glycemic index.

CONCLUSIONS

An increased frequency of CD14⁺HLA-DR^-/low cells in the blood of T2DM patients was recorded. The influence of hyperglycemia seems to be independent of obesity, but related to glycemic control and age.

[Epidemiologic-clinical, biological and radiological features of pulmonary tuberculosis in patients with diabetes in Antananarivo, Madagascar]

Pulmonary tuberculosis is frequently associated with diabetes mellitus and, sometimes, it may present with atypical signs. The purpose of this study is to identify the epidemiological, clinical, biological and radiological features of pulmonary tuberculosis in patients with diabetes versus patients without diabetes in order to improve treatment. We conducted a retrospective, cross-sectional descriptive and analytical study in the Department of Endocrinology and Pneumology at the Joseph Raseta Befelatanana University Hospital Center and in the Department of Respiratory Diseases at the Soavinandriana Hospital Center in Antananarivo, Madagascar. It involved patients diagnosed with pulmonary tuberculosis who presented a positive bacilloscopy exam from January 2018 to January 2020 (25 months). In our study, the overall prevalence of diabetes among TB patients was 20.31 %. Older age, insidious clinical course, severe biologic inflammatory syndrome, fewer caves but more systematized opacities and diffuse radiological lesions in the basal zone (more commonly unilateral right lesions) were mainly detected in patients with diabetes compared to patients without diabetes. Knowledge of signs of pulmonary TB in patients with diabetes can help health care workers to make a diagnosis, even in patients with atypical signs. Moreover, as the majority of pulmonary tuberculosis occur in patients with unstable diabetes, a good glycemic balance can certainly reduce its incidence.

High Glucose Concentrations Impair the Processing and Presentation of Mycobacterium tuberculosis Antigens In Vitro

Type 2 diabetes is an established risk factor for tuberculosis, but the underlying mechanisms are largely unknown. We established an in vitro model to analyze the effect of high glucose concentrations in antigen processing and presentation in antigen-presenting cells. Human monocyte-derived macrophages (MDMs) were exposed to high (11 mM and 30 mM) and low (5.5 mM) glucose concentrations and infected with Mycobacterium tuberculosis (Mtb). Flow cytometry was used to analyze the effect of high glucose concentrations in histocompatibility complex (MHC) class II molecules (HLA-DR) and co-stimulatory molecules (CD80 and CD86), indispensable for an adequate antigenic presentation and CD4+ T cell activation. HLA-DR and CD86 were significantly decreased by high glucose concentrations compared with low glucose concentrations. Confocal microscopy was used to detect Rab 5 and Lamp-1, proteins involved in the kinetics of antigen processing as early markers, and Rab 7 and cathepsin D as late markers. We observed a delay in the dynamics of the acquisition of Rab 7 and cathepsin D in high glucose concentrations. Moreover, the kinetics of the formation M. tuberculosis peptide-MHC II complexes in MDMs was decreased under high glucose concentrations, reducing their capacity for T cell activation. These findings suggest that high glucose concentrations directly affect antigenic processing, and therefore antigenic presentation.

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.

Type 2 Diabetes Mellitus and Latent Tuberculosis Infection Moderately Influence Innate Lymphoid Cell Immune Responses in Uganda

Background

Type 2 diabetes mellitus (T2DM) is a major risk factor for the acquisition of latent tuberculosis (TB) infection (LTBI) and development of active tuberculosis (ATB), although the immunological basis for this susceptibility remains poorly characterised. Innate lymphoid cells (ILCs) immune responses to TB infection in T2DM comorbidity is anticipated to be reduced. We compared ILC responses (frequency and cytokine production) among adult patients with LTBI and T2DM to patients (13) with LTBI only (14), T2DM only (10) and healthy controls (11).

Methods

Using flow cytometry, ILC phenotypes were categorised based on (Lin⁻CD127⁺CD161⁺) markers into three types: ILC1 (Lin⁻CD127⁺CD161⁺CRTH2^-CD117⁻); ILC2 (Lin⁻CD127⁺CD161⁺CRTH2⁺) and ILC3 (Lin⁻CD127⁺CD161⁺CRTH2⁻NKp44^+/−CD117⁺). ILC responses were determined using cytokine production by measuring percentage expression of interferon-gamma (IFN-γ) for ILC1, interleukin (IL)-13 for ILC2, and IL-22 for ILC3. Glycaemic control among T2DM patients was measured using glycated haemoglobin (HbA1c) levels. Data were analysed using FlowJo version 10.7.1, and GraphPad Prism version 8.3.

Results

Compared to healthy controls, patients with LTBI and T2DM had reduced frequencies of ILC2 and ILC3 respectively (median (IQR): 0.01 (0.005-0.04) and 0.002 (IQR; 0.002-0.007) and not ILC1 (0.04 (0.02-0.09) as expected. They also had increased production of IFN-γ [median (IQR): 17.1 (5.6-24.9)], but decreased production of IL-13 [19.6 (12.3-35.1)]. We however found that patients with T2DM had lower ILC cytokine responses in general but more marked for IL-22 production (median (IQR): IFN-γ 9.3 (4.8-22.6); IL-13 22.2 (14.7-39.7); IL-22 0.7 (IQR; 0.1-2.1) p-value 0.02), which highlights the immune suppression status of T2DM. We also found that poor glycaemic control altered ILC immune responses.

Conclusion

This study demonstrates that LTBI and T2DM, and T2DM were associated with slight alterations of ILC immune responses. Poor T2DM control also slightly altered these ILC immune responses. Further studies are required to assess if these responses recover after treatment of either TB or T2DM.

Impact of Type 2 Diabetes on the capacity of human macrophages infected with Mycobacterium tuberculosis to modulate monocyte differentiation through a bystander effect

Type 2 diabetes mellitus (T2DM) is a risk factor for the development of tuberculosis (TB) through mechanisms poorly understood. Monocytes and macrophages are key effector cells to control TB, but they are also subverted by Mycobacterium tuberculosis (Mtb). Specifically, Mtb can induce a bystander effect that skews monocyte differentiation towards macrophages with a permissive phenotype to infection. Here, we evaluated whether T2DM impacts this TB aspect. Our approach was to differentiate monocytes from healthy control (HC) subjects and T2DM patients into macrophages (MDM), and then assess their response to Mtb infection, including their secretome content and bystander effect capacity. Through flow cytometry analyses, we found a lower level of activation markers in MDM from T2DM patients in comparison to those from HC in response to mock (HLA-DR, CD86, and CD163) or Mtb challenge (CD14 and CD80). In spite of high TGF-β1 levels in mock-infected MDM from T2DM patients, cytometric bead arrays indicated there were no major differences in the secretome cytokine content in these cells relative to HC-MDM, even in response to Mtb. Mimicking a bystander effect, the secretome of Mtb-infected HC-MDM drove HC monocytes towards MDM with a permissive phenotype for Mtb intracellular growth. However, the secretome from Mtb-infected T2DM-MDM did not exacerbate the Mtb load compared to cmMTB-HC, possibly due to the high IL-1β production relative to Mtb-infected HC-MDM. Collectively, despite T2DM affecting the basal MDM activation, our approach revealed it has no major consequence on their response to Mtb or capacity to generate a bystander effect influencing monocyte differentiation.

Mycobacterial Growth Inhibition Assay (MGIA) as a Host Directed Diagnostic Tool for the Evaluation of the Immune Response in Subjects Living With Type 2 Diabetes Mellitus

The lack of efficient and cost-effective diagnostic tools contributes to poor control of tuberculosis in endemic countries. Moreover, host biological processes influence susceptibility, and infection resolution. It is well known that comorbidities such as type 2 diabetes mellitus (DM2) affect the host immune response, making individuals more susceptible to Mycobacterium tuberculosis infection. Currently, there are no laboratory tools that can identify those subjects who have a higher risk of developing the disease. In this study, we used a whole blood mycobacterial growth inhibition assay to assess the immune response capacity to inhibit mycobacterial growth between healthy subjects and those living with DM2 with optimal and poor glycemic control. We also measured cytokine levels in the culture supernatant by cytokine bead arrays. We included 89 patients with DM2: 54 patients with optimal control (mean age 56.2 ± 11.75 years) and 35 patients with poor control (mean age 52.05 ± 9.94 years). We also included 44 healthy subjects as controls (mean age 42.12 ± 11.75 years). We compared the Δlog UFC (a value that represents the difference between mycobacterial growth in the control tube versus the subject’s blood) between each group. Our results demonstrate that patients with DM2 had a lower capacity to inhibit M. tuberculosis growth (Δlog UFC DM2 subjects 0.9581 (-0.3897 to 2.495) vs Δlog UFC healthy subjects 0.7190 (-0.2678 to 2.098); p=0.013). Comparing subjects living with DM2 (optimal and poor glycemic control) vs healthy subjects, we found only significant differences between healthy subjects and patients poorly controlled (Δlog UFC optimal control group 0.876 (-0.3897 to 2.495); Δlog UFC poor control group 1.078 (0.068 to 2.33); Δlog UFC healthy subjects 0.7190 (-0.2678 to 2.098); p= 0.022). Therefore, glycemic control assessed by glycosylated hemoglobin values influences the capacity of the host to control the infection. Our results confirm that the whole blood mycobacterial growth inhibition assay has potential utility as an in vitro marker of M. tuberculosis immunological control in vivo in subjects living with DM2. This assay can be used to evaluate the immune response of each individual against M. tuberculosis, allowing clinicians to choose a more specific host-directed therapy.

Hyperglycemia and dyslipidemia: Reduced HLA-DR expression in monocyte subpopulations from diabetes patients

Immune dysfunction contributes to the higher risk of communicable and non-communicable diseases among diabetics. HLA-DR expression is a robust marker of immune competence in mononuclear cells, including antigen presentation to CD4 lymphocytes. Given the high prevalence of obesity among diabetics, we evaluated the independent association between hyperglycemia and dyslipidemias with respect to HLA-DR expression in blood monocytes from type 2 diabetes patients. The monocytes from individuals with (n = 16) or without diabetes (n = 25) were phenotyped by flow cytometry to assess the differential expression of HLA-DR on their three subpopulations (classical, intermediate and non-classical monocytes). Diabetes was independently associated with lower HLA-DR expression across all monocyte subpopulations (p < 0.05). Blood triglycerides were associated with further HLA-DR depression (interaction p < 0.002). Cholesterols counterbalanced the reductive effect, with CD36, a receptor for oxidized cholesterol, correlating with HLA-DR (rho = 0.373; p = 0.016). Future studies are warranted to elucidate the complex interactions between hyperglycemia and dyslipidemias on antigen presentation in diabetic monocytes.

Perspectives and Advances in the Understanding of Tuberculosis

Mycobacterium tuberculosis (Mtb), the causative agent of tuberculosis (TB), remains a leading cause of death due to infection in humans. To more effectively combat this pandemic, many aspects of TB control must be developed, including better point of care diagnostics, shorter and safer drug regimens, and a protective vaccine. To address all these areas of need, better understanding of the pathogen, host responses, and clinical manifestations of the disease is required. Recently, the application of cutting-edge technologies to the study of Mtb pathogenesis has resulted in significant advances in basic biology, vaccine development, and antibiotic discovery. This leaves us in an exciting era of Mtb research in which our understanding of this deadly infection is improving at a faster rate than ever, and renews hope in our fight to end TB. In this review, we reflect on what is known regarding Mtb pathogenesis, highlighting recent breakthroughs that will provide leverage for the next leaps forward in the field.

Human monocyte-derived macrophage responses to M. tuberculosis differ by the host's tuberculosis, diabetes or obesity status, and are enhanced by rapamycin

Human macrophages play a major role in controlling tuberculosis (TB), but their anti-mycobacterial mechanisms remain unclear among individuals with metabolic alterations like obesity (TB protective) or diabetes (TB risk). To help discern this, we aimed to: i) Evaluate the impact of the host's TB status or their comorbidities on the anti-mycobacterial responses of their monocyte-derived macrophages (MDMs), and ii) determine if the autophagy inducer rapamycin, can enhance these responses. We used MDMs from newly diagnosed TB patients, their close contacts and unexposed controls. The MDMs from TB patients had a reduced capacity to activate T cells (surrogate for antigen presentation) or kill M. tuberculosis (Mtb) when compared to non-TB controls. The MDMs from obese participants had a higher antigen presenting capacity, whereas those from chronic diabetes patients displayed lower Mtb killing. The activation of MDMs with rapamycin led to an enhanced anti-mycobacterial activity irrespective of TB status but was not as effective in patients with diabetes. Further studies are warranted using MDMs from TB patients with or without metabolic comorbidities to: i) elucidate the mechanisms through which host factors affect Mtb responses, and ii) evaluate host directed therapy using autophagy-inducing drugs like rapamycin to enhance macrophage function.

Inflammation: A bridge between diabetes and COVID-19, and possible management with sitagliptin

Patients with SARS-CoV-2 infections experience lymphopenia and inflammatory cytokine storms in the severe stage of the disease, leading to multi-organ damage. The exact pattern of immune system changes and their condition during the disease process is unclear. The available knowledge has indicated that the NF-kappa-B pathway, which is induced by several mediators, has a significant role in cytokine storm through the various mechanisms. Therefore, identifying the state of the immune cells and the dominant mechanisms for the production of cytokines incorporated in the cytokine storm can be a critical step in the therapeutic approach. On the other hand, some studies identified a higher risk for diabetic patients. Diabetes mellitus exhibits a close association with inflammation and increases the chance of developing COVID-19. Patients with diabetes mellitus have shown to have more virus entry, impaired immunity response, less viral elimination, and dysregulated inflammatory cytokines. The parallel analysis of COVID-19 and diabetes mellitus pathogenesis has proposed that the control of the inflammation through the interfering with the critical points of major signaling pathways may provide the new therapeutic approaches. In recent years, the role of Dipeptidyl Peptidase 4 (DPP4) in chronic inflammation has been proved. Numerous immune cells express the DPP4 protein. DPP4 regulates antibody production, cytokine secretion, and immunoglobulin class switching. DPP4 inhibitors like sitagliptin reduce inflammation intensity in different states. Following the accumulating data, we hypothesize that sitagliptin might reduce COVID-19 severity. Sitagliptin, an available DPP4 inhibitor drug, showed multidimensional anti-inflammatory effects among diabetic patients. It reduces the inflammation mostly by affecting on NF-kappa-B signaling pathway. Under the fact that inflammatory mediators are active in individuals with COVID-19, blocking the predominant pathway could be helpful.

The Echo of Pulmonary Tuberculosis: Mechanisms of Clinical Symptoms and Other Disease-Induced Systemic Complications

Clinical symptoms of active tuberculosis (TB) can range from a simple cough to more severe reactions, such as irreversible lung damage and, eventually, death, depending on disease progression. In addition to its clinical presentation, TB has been associated with several other disease-induced systemic complications, such as hyponatremia and glucose intolerance. Here, we provide an overview of the known, although ill-described, underlying biochemical mechanisms responsible for the clinical and systemic presentations associated with this disease and discuss novel hypotheses recently generated by various omics technologies. This summative update can assist clinicians to improve the tentative diagnosis of TB based on a patient's clinical presentation and aid in the development of improved treatment protocols specifically aimed at restoring the disease-induced imbalance for overall homeostasis while simultaneously eradicating the pathogen. Furthermore, future applications of this knowledge could be applied to personalized diagnostic and therapeutic options, bettering the treatment outcome and quality of life of TB patients.

Glibenclamide alters interleukin-8 and interleukin-1β of primary human monocytes from diabetes patients against Mycobacterium tuberculosis infection

Type 2 diabetes mellitus (T2DM) is an important risk factor for development of tuberculosis (TB). Our previous study showed glibenclamide, an anti-diabetic drug used to control blood glucose concentration, reduced interleukin (IL)-8 secretion from primary human monocytes challenged with M. tuberculosis (Mtb). In mice infected with Mtb, IL-1β is essential for host resistance through the enhancement of cyclooxygenase that limits excessive Type I interferon (IFN) production and fosters Mtb containment. We hypothesize that glibenclamide may also interfere with monocyte mediated immune responses against Mtb and alter the balance between IL-1β and IFNα-mediated immunity. Purified monocytes from non-diabetic and diabetic individuals were infected with Mtb or M. bovis BCG. We demonstrate that monocytes from diabetes patients who were being treated with glibenclamide showed reduced IL-1β and IL-8 secretion when exposed to Mtb. Additionally, these responses also occurred when monocytes from non-diabetic individuals were pre-treated with glibenclamide in vitro. Moreover, this pre-treatment enhanced IFNa1 expression but was not involved with prostaglandin E2 (PGE2) expression in response to Mtb infection. Taken together, our data show that glibenclamide might exacerbate susceptibility of diabetes patients to Mtb infection by reducing IL-1β and IL-8 production by monocytes.

Increased susceptibility to Mycobacterium tuberculosis infection in a diet-induced murine model of type 2 diabetes

Tuberculosis (TB)-type 2 diabetes mellitus (T2D) comorbidity is re-emerging as a global public health problem. T2D is a major risk factor for increased susceptibility to TB infection and reactivation leading to higher morbidity and mortality. The pathophysiological mechanisms of T2D contributing to TB susceptibility are not fully understood, but likely involve dysregulated immune responses. In this study, a diet-induced murine model that reflects the cardinal features of human T2D was used to assess the immune responses following an intravenous Mycobacterium tuberculosis (Mtb) infection. In this study, T2D significantly increased mortality, organ bacillary burden and inflammatory lesions compared to non-diabetic controls. Organ-specific pro-inflammatory cytokine responses were dysregulated as early as one day post-infection in T2D mice. Macrophages derived from T2D mice showed reduced bacterial internalization and killing capacity. An early impairment of antimycobacterial functions of macrophages in diabetes is a key mechanism that leads to increased susceptibility of T2D.

Evidence for a More Disrupted Immune-Endocrine Relation and Cortisol Immunologic Influences in the Context of Tuberculosis and Type 2 Diabetes Comorbidity

Pulmonary tuberculosis (PTB), caused by Mycobacterium tuberculosis (Mtb), is a major health problem worldwide, further aggravated by the convergence of type 2 diabetes mellitus (DM) which constitutes an important risk factor for TB development. The worse scenario of patients with PTB and DM may be partly related to a more unbalanced defensive response. As such, newly diagnosed PTB patients with DM (TB+DM, n = 11) or not (TB, n = 21), as well as DM (n = 18) patients and pair matched controls (Co, n = 22), were investigated for the circulating immuno-endocrine-metabolic profile (ELISA), along with studies in peripheral blood mononuclear cells (PBMC) analyzing transcript expression (RT-qPCR) of mediators involved in glucocorticoid functionality. Given the hyperglycemic/hypercortisolemic scenario of TB+DM patients, PBMC were also exposed to stress-related cortisol concentrations (0.1 and 1 μM) and supraphysiologic glucose doses (10, 20, and 40 mM) and assessed for the specific response against Mtb stimulation (lymphoproliferation, -thymidine incorporation-, and cytokine production -bead-cytometry). All TB patients displayed increased plasma amounts of cortisol, growth hormone -hGH-, and proinflammatory mediators. In turn, TB+DM showed even higher levels of interferon gamma -IFN-γ- and hGH (vs. TB), or IL-6, C reactive protein, cortisol and hGH (vs. DM). Both DM groups had equally augmented values of IL-10. All TB patients showed decreased dehydroepiandrosterone- sulfate concentrations, even more in TB+DM cases. Leptin was also decreased in both TB cases, particularly in the TB group, revealing a lower body mass index, as well. Unlike PBMC from TB cases showing a decreased relationship between the glucocorticoids receptor (GR) isoforms (GRα/GRβ; functional isoform/negative isoform), cells from TB+DM patients had no changes in this regard, along with an increased expression of 11-beta hydroxysteroid dehydrogenase type-1, the enzyme facilitating intracellular cortisone to cortisol conversion. TB+DM patients also showed an increased Mtb antigen-driven lymphoproliferation. Compared to TB, DM and HCo counterparts, PBMC from TB+DM patients had a biased Th1 response to Mtb stimulation (increased IL-2 and IFN-γ production), even when exposed to inhibitory cortisol doses. TB+DM patients show a more unbalanced immuno-endocrine relationship, respect the non-diabetic counterparts, with a relative deficiency of cortisol immunomodulatory influences, despite their more favorable microenvironment for cortisol-mediated immune effects.

An Inflammatory Story: Antibodies in Tuberculosis Comorbidities

Mycobacterium tuberculosis (Mtb) resides in a quarter of the world's population and is the causative agent for tuberculosis (TB), the most common infectious reason of death in humans today. Although cellular immunity has been firmly established in the control of Mtb, there is growing evidence that antibodies may also modulate the infection. More specifically, certain antibody features are associated with inflammation and are divergent in different states of human infection and disease. Importantly, TB impacts not just the healthy but also those with chronic conditions. While HIV represents the quintessential comorbid condition for TB, recent epidemiological evidence shows that additional chronic conditions such as diabetes and kidney disease are rising. In fact, the prevalence of diabetes as a comorbid TB condition is now higher than that of HIV. These chronic diseases are themselves independently associated with pro-inflammatory immune states that encompass antibody profiles. This review discusses isotypes, subclasses, post-translational modifications and Fc-mediated functions of antibodies in TB infection and in the comorbid chronic conditions of HIV, diabetes, and kidney diseases. We propose that inflammatory antibody profiles, which are a marker of active TB, may be an important biomarker for detection of TB disease progression within comorbid individuals. We highlight the need for future studies to determine which inflammatory antibody profiles are the consequences of comorbidities and which may potentially contribute to TB reactivation.

Factors associated with tuberculosis in a population of diabetics: A case-control study

This study analyzed the factors associated with tuberculosis in diabetics seen at health units of Vitória, ES, Brazil. This is a case-control study of 45 cases of diabetics seen in the 30 units of the municipality and reported in the SINAN with a diagnosis of tuberculosis in the 2007-2013 period and 90 cases of diabetic controls. We used data from the SINAN, the Health Information System of Vitória, and the Central Municipal Laboratory, as well a structured interview. Bivariate and multivariate analyses were performed, using logistic regression with the significant variables (p < 0.05). The case group presented a higher frequency of health-damaging life habits as compared to the control group, such as compulsive drinking (p < 0.001) and tobacco smoking (p = 0.060), as well as worse biochemical parameters, such as fasting blood sugar (p < 0.001) and glycosylated hemoglobin (p = 0.034). Regular drinking (OR 6.612, CI 2,151-20.330), previous contact with people with tuberculosis (OR 4.418, CI 1.678-11.631), and fasting blood sugar (OR 1.017, CI 1.007-1.026) were associated with tuberculosis in diabetics. The study reveals that poorer lifestyle habits and glycemic control and previous contact with active tuberculosis increase the chance of diabetics developing tuberculosis.

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.

Diabetic lung disease: fact or fiction?

Diabetes mellitus is a chronic, progressive, incompletely understood metabolic disorder whose prevalence has been increasing steadily worldwide. Even though little attention has been paid to lung disorders in the context of diabetes, its prevalence has recently been challenged by newer studies of disease development. In this review, we summarize and discuss the role of diabetes mellitus involved in the progression of pulmonary diseases, with the main focus on pulmonary fibrosis, which represents a chronic and progressive disease with high mortality and limited therapeutic options.

The re-emerging association between tuberculosis and diabetes: Lessons from past centuries

The association between tuberculosis (TB) and diabetes mellitus (DM) had a common place in the literature up to the first half of the 20th century, but virtually disappeared with the discovery of insulin to treat DM and antibiotics to cure TB. In the late 1990s the literature began to re-emerge with the worldwide increase in type 2 DM, particularly in TB-endemic countries. Today, type 2 DM is the most prevalent comorbidity among TB patients and the World Health Organization considers it a threat to TB control. We summarize the literature on TB and DM up to the 1960s. Then we evaluate unique aspects of this comorbidity in older times, such as the frequent diabetic comas that suggest challenges for proper DM management as insulin was being implemented, or the absence of antibiotics to cure TB. Despite the unique aspects of each study period, the literature across times is consistent in key aspects of the association. Namely, a higher TB prevalence among DM (versus non-DM patients), the importance of glucose control and chronic DM on TB susceptibility and the higher risk of death among patients with the co-morbidity. From the older literature, we can infer the likely contribution of type 1 DM to TB (in addition to type 2), regardless of their differing autoimmune or metabolic pathophysiology, respectively. Furthermore, in the older literature there was a notable reporting of DM development among TB patients, even though DM usually preceded TB. This observation deserves further epidemiological and basic studies to elucidate this intriguing aspect of the relationship between TB and DM.

Immune-endocrine interactions related to a high risk of infections in chronic metabolic diseases: The role of PPAR gamma

Diverse disturbances in immune-endocrine circuitries are involved in the development and aggravation of several chronic metabolic diseases (CMDs), including obesity, diabetes, and metabolic syndrome. The chronic inflammatory syndrome observed in CMDs culminates in dysregulated immune responses with low microbial killing efficiency, by means low host innate immune response, and loss of ability to eliminate the pathogens, which results in a high prevalence of infectious diseases, including pneumonia, tuberculosis, and sepsis. Herein, we review evidence pointing out PPARγ as a putative player in immune-endocrine disturbances related to increased risk of infections in CMDs. Cumulated evidence indicates that PPARγ activation modulates host cells to control inflammation during CMDs because of PPARγ agonists have anti-inflammatory and pro-resolutive properties, increasing host ability to eliminate pathogen, modulating hormone production, and restoring glucose and lipid homeostasis. As such, we propose PPARγ as a putative therapeutic adjuvant for patients with CMDs to favor a better infection control.

Dysregulation of key cytokines may contribute to increased susceptibility of diabetic mice to Mycobacterium bovis BCG infection

Diabetes is one of the major co-morbidities contributing to the high global burden of tuberculosis (TB). The increased susceptibility of individuals with type 2 diabetes (T2D) to TB is multifactorial and may influence the efficacy of vaccines. This study was undertaken to determine the early immune responses that occur following infection with Mycobacterium bovis Bacille Calmette-Guérin (BCG) in a diet-induced murine model of T2D. The phagocytic capabilities of alveolar (AM) and resident peritoneal macrophages (RPM) were assessed using ex vivo assays. Compared to macrophages from non-diabetic mice, macrophages from diabetic animals showed decreased BCG uptake and killing and inflammatory cytokine production (TNF-α, MCP-1, IL-6, IL-1β). In vivo susceptibility to BCG was determined following intravenous infection and diabetic mice showed a trend towards increased mortality, higher bacterial burden in the lung, liver and spleen and increased inflammatory lesions compared to controls. Differences between tissue cytokines were observed as early as one day post-infection and by days 14 and 35, lung and liver TNF-α and IFN-γ levels were decreased in diabetic mice compared to controls. These results suggest that early dysregulated immune responses may influence the susceptibility of T2D mice to BCG infection.

Higher risk of developing active TB among adult diabetics exposed to TB during childhood: A study from Kerala, India

INTRODUCTION

Factors associated with tuberculosis (TB) in Kerala, the southern Indian state that notifies approximately 33 microbiologically confirmed new cases per 100,000 population every year for the past two decades, are still unclear. We did a community-based case-control study in Kollam district, Kerala, to identify the individual-level risk factors for TB.

METHODS

Structured questionnaire was applied to 101 microbiologically confirmed new TB cases registered under Revised National Tuberculosis Control Program and 202 age- and gender-matched neighborhood controls without present or past TB. Information was sought on socioeconomic status (SES), smoking, consumption of alcohol, close contact with active TB during childhood or recent past, diabetes mellitus (DM), and other comorbid conditions.

RESULTS

Close contact with TB during childhood [odds ratio (OR) 15.88, 95% confidence interval (CI) 3.21-78.55], recent close contact with TB (OR 4.81, 95% CI 2.09-11.07), DM (OR 1.64, 95% CI 1.04-3.06), SES (OR 2.16, 95% CI 1.16-4.03), smoking more than 10 cigarettes/beedis per day (OR 3.32, 95% CI 1.27-8.96), consuming more than 10 standard drinks per week (OR 2.91, 95% CI 1.33-6.37), and the interaction term of having close contact with TB during childhood and DM at present (OR 7.37, 95% CI 1.18-50.29) were found to be associated with TB.

CONCLUSION

Close contact with a case of TB, presence of DM, lower SES, smoking, and alcohol consumption were associated with active TB in Kollam. Having close contact with a case of TB during childhood and development of DM in later life together are significantly associated with active TB in the study population. The findings also direct further studies to confirm and explore mechanisms of interaction of diabetes with childhood exposure to TB.

Effect of Diabetes Mellitus on the Pharmacokinetics and Pharmacodynamics of Tuberculosis Treatment

Diabetes mellitus (DM) and tuberculosis (TB) are two common diseases with increasing geographic overlap and clinical interactions. The effect of DM and hemoglobin A1c (HbA1c) values on the pharmacokinetics (PK) and pharmacodynamics (PD) of anti-TB drugs remains poorly characterized. Newly diagnosed TB patients with and without DM starting fixed-dose, thrice-weekly treatment underwent sampling for PK assessments (predose and 0.5, 2, and 6 h postdose) during the intensive and continuation phases of treatment. The effect of DM and HbA1c values on the maximum concentration (C _max) of rifampin, isoniazid, and pyrazinamide and the association between drug concentrations and microbiologic and clinical outcomes were assessed. Of 243 patients, 101 had DM. Univariate analysis showed significant reductions in the C _max of pyrazinamide and isoniazid (but not rifampin) with DM or increasing HbA1c values. After adjusting for age, sex, and weight, DM was associated only with reduced pyrazinamide concentrations (adjusted geometric mean ratio = 0.74, P = 0.03). In adjusted Cox models, female gender (adjusted hazards ratio [aHR] = 1.75, P = 0.001), a lower smear grade with the Xpert assay (aHR = 1.40, P < 0.001), and the pyrazinamide C _max (aHR = 0.99, P = 0.006) were independent predictors of sputum culture conversion to negative. Higher isoniazid or rifampin concentrations were associated with a faster time to culture conversion in patients with DM only. A pyrazinamide C _max above the therapeutic target was associated with higher unfavorable outcomes (treatment failure, relapse, death) (odds ratio = 1.92, P = 0.04). DM and higher HbA1c values increased the risk of not achieving therapeutic targets for pyrazinamide (but not rifampin or isoniazid). Higher pyrazinamide concentrations, though, were associated with worse microbiologic and clinical outcomes. DM status also appeared to influence PK-PD relationships for isoniazid and rifampin.

The effect of metformin on culture conversion in tuberculosis patients with diabetes mellitus

BACKGROUND/AIMS

Patients with diabetes mellitus (DM) and tuberculosis (TB) have increased morbidity and a high risk of treatment failure or recurrence. It is important to manage both diseases simultaneously. Among anti-diabetic drugs, metformin inhibits intracellular growth of mycobacteria. Therefore, we examined the effects of metformin on TB treatment, especially in patients with DM.

METHODS

This retrospective cohort study included patients with culture-positive pulmonary TB diagnosed between 2011 and 2012. The primary study outcome was sputum culture conversion after 2 months of treatment.

RESULTS

Of 499 patients diagnosed with culture-positive pulmonary TB, 105 (21%) had DM at diagnosis. Among them, 62 (59.5%) were treated with metformin. Baseline characteristics, except for the presence of chronic renal disease, were not significantly different between the metformin and non-metformin groups. Metformin treatment had no significant effect on sputum culture conversion (p = 0.60) and recurrence within 1 year after TB treatment completion (p = 0.39). However, metformin improved the sputum culture conversion rate in patients with cavitary pulmonary TB, who have higher bacterial loads (odds ratio, 10.8; 95% confidence interval, 1.22 to 95.63).

CONCLUSION

Among cavitary pulmonary TB patients with DM, metformin can be an effective adjunctive anti-TB agent to improve sputum culture conversion after 2 months of treatment.

Metabolomics applied to the discovery of tuberculosis and diabetes mellitus biomarkers

Tuberculosis (TB) and diabetes mellitus Type 2 (DM2) are two diseases as ancient as they are harmful to human health. The outcome for both diseases in part depends on immune and metabolic individual responses. DM2 is increasing yearly, mainly due to environmental, genetic and lifestyle habits. There are multiple evidence that DM2 is one of the most important risk factor of becoming infected with TB or reactivating latent TB. Mass spectrometry-based metabolomics is an important tool for elucidating the metabolites and metabolic pathways that influence the immune responses to M. tuberculosis infection during diabetes. We provide an up-to-date review highlighting the importance and benefit of metabolomics for identifying biomarkers as candidate molecules for diagnosis, disease activity or prognosis.

Hyperglycaemia is inversely correlated with live M. bovis BCG-specific CD4+ T cell responses in Tanzanian adults with latent or active tuberculosis

Introduction

The rising prevalence of Diabetes mellitus (DM) in high TB‐endemic countries may adversely affect sustainability of TB control since DM constitutes a risk factor for development of active tuberculosis (TB). The impact of DM on TB specific adaptive immune responses remains poorly addressed, particularly in people living in Sub‐Saharan countries. We performed a functional characterization of TB specific cellular immune response in Tanzanian subjects with active or latent Mycobacterium tuberculosis (Mtb) infection stratified by their diabetic status.

Methods

HIV negative active TB patients (≥18 years) with Xpert MTB/RIF positive pulmonary TB were included before starting TB treatment in Dar es Salaam, Tanzania between April and December 2013. HIV negative healthy controls latently infected with TB but without past TB history were also included. Active and latent TB patients were stratified in two groups according to their diabetic status. Peripheral Blood Mononuclear cells were stimulated with either live M. bovis BCG or Mtb‐specific peptide pools and analyzed by intracellular cytokine staining and polychromatic flow cytometry.

Results

Our results show a lower frequency of IFN‐γ CD4⁺ T cells in patients with active TB and DM compared to patients with active TB only after live M. bovis BCG (p = 0.04) but not after Mtb peptide pools re‐stimulation. Irrespective of TB status, level of glycaemia is selectively inversely correlated with IFN‐γ and TNF‐α CD4⁺ T cell production (p = 0.02 and p = 0.03) after live M. bovis BCG stimulation.

Conclusions

These results support the hypothesis that hyperglycaemia negatively impacts antigen processing and/or presentation of whole mycobacteria delaying secretion of key cytokines involved in TB immunity.

Modulation of iron status biomarkers in tuberculosis-diabetes co-morbidity

Tuberculosis (TB) and diabetes mellitus (DM) remain vital disease burdens in developing countries and the dual burden of DM and TB clearly signifies a growing global public health concern. While modulation of iron status biomarkers in TB is well described, very little is known about the association of these markers with TB-DM. To examine the association of circulating iron status biomarkers in TB disease, we examined the systemic levels of ferritin, hepcidin, soluble transferrin receptor (sTfR), transferrin, apotransferrin and hemopexin in pulmonary TB (PTB) individuals with DM (PTB-DM), without DM (PTB) and those with diabetes only (DM). Circulating levels of ferritin and hepcidin were significantly enhanced in PTB-DM and PTB compared to the DM group. On the other hand, the circulating levels of transferrin and apotransferrin were significantly diminished in PTB-DM and PTB compared to the DM group. The levels of ferritin and hepcidin exhibited a significant positive relationship with HbA1c, whereas apotransferrin exhibited negative relationship with HbA1c in PTB-DM and PTB. ROC analysis revealed that ferritin, hepcidin and transferrin are markers that can distinguish PTB-DM from DM individuals. Our results suggest that some of these circulating iron status markers could prove useful as biomarkers to monitor disease severity.

Molecular clustering of patients with diabetes and pulmonary tuberculosis: A systematic review and meta-analysis

Introduction

Many studies have explored the relationship between diabetes mellitus (DM) and tuberculosis (TB) demonstrating increased risk of TB among patients with DM and poor prognosis of patients suffering from the association of DM/TB. Owing to a paucity of studies addressing this question, it remains unclear whether patients with DM and TB are more likely than TB patients without DM to be grouped into molecular clusters defined according to the genotype of the infecting Mycobacterium tuberculosis bacillus. That is, whether there is convincing molecular epidemiological evidence for TB transmission among DM patients. Objective: We performed a systematic review and meta-analysis to quantitatively evaluate the propensity for patients with DM and pulmonary TB (PTB) to cluster according to the genotype of the infecting M. tuberculosis bacillus.

Materials and methods

We conducted a systematic search in MEDLINE and LILACS from 1990 to June, 2016 with the following combinations of key words “tuberculosis AND transmission” OR “tuberculosis diabetes mellitus” OR “Mycobacterium tuberculosis molecular epidemiology” OR “RFLP-IS6110” OR “Spoligotyping” OR “MIRU-VNTR”. Studies were included if they met the following criteria: (i) studies based on populations from defined geographical areas; (ii) use of genotyping by IS6110- restriction fragment length polymorphism (RFLP) analysis and spoligotyping or mycobacterial interspersed repetitive unit-variable number of tandem repeats (MIRU-VNTR) or other amplification methods to identify molecular clustering; (iii) genotyping and analysis of 50 or more cases of PTB; (iv) study duration of 11 months or more; (v) identification of quantitative risk factors for molecular clustering including DM; (vi) > 60% coverage of the study population; and (vii) patients with PTB confirmed bacteriologically. The exclusion criteria were: (i) Extrapulmonary TB; (ii) TB caused by nontuberculous mycobacteria; (iii) patients with PTB and HIV; (iv) pediatric PTB patients; (v) TB in closed environments (e.g. prisons, elderly homes, etc.); (vi) diabetes insipidus and (vii) outbreak reports. Hartung-Knapp-Sidik-Jonkman method was used to estimate the odds ratio (OR) of the association between DM with molecular clustering of cases with TB. In order to evaluate the degree of heterogeneity a statistical Q test was done. The publication bias was examined with Begg and Egger tests. Review Manager 5.3.5 CMA v.3 and Biostat and Software package R were used.

Results

Selection criteria were met by six articles which included 4076 patients with PTB of which 13% had DM. Twenty seven percent of the cases were clustered. The majority of cases (48%) were reported in a study in China with 31% clustering. The highest incidence of TB occurred in two studies from China. The global OR for molecular clustering was 0.84 (IC 95% 0.40–1.72). The heterogeneity between studies was moderate (I² = 55%, p = 0.05), although there was no publication bias (Beggs test p = 0.353 and Eggers p = 0.429).

Conclusion

There were very few studies meeting our selection criteria. The wide confidence interval indicates that there is not enough evidence to draw conclusions about the association. Clustering of patients with DM in TB transmission chains should be investigated in areas where both diseases are prevalent and focus on specific contexts.

Low serum vitamin D levels in type 2 diabetes patients are associated with decreased mycobacterial activity

Background

Concurrent diabetes mellitus and tuberculosis represent a significant health problem worldwide. Patients with diabetes mellitus have a high risk of tuberculosis, which may be mediated by an abnormal innate immune response due to hyperglycaemia or low vitamin D levels.

Methods

In the present study, we evaluated inactive vitamin D serum levels and the monocyte response to infection with M. tuberculosis, including phagocytosis of M. tuberculosis, antimycobacterial activity, LL-37, human β defensin-2 and IL-10 gene expression and nitric oxide production, between type 2 diabetes mellitus patients (n = 51) and healthy volunteers (n = 38).

Results

Twenty-seven type 2 diabetes mellitus patients had inadequate inactive vitamin D levels (<50 nM). The percentages of M. tuberculosis phagocytosis between monocytes were similar across groups according to microscopy. Intracellular mycobacterial growth was similar in infected monocytes from both groups. However, M. tuberculosis growth was significantly higher in monocytes obtained from type 2 diabetes mellitus patients and lower vitamin D levels after 1-h (D0) and 72-h (D3) post-infection (p ≤ 0.05). LL-37, human β defensin-2 and IL-10 mRNA expression were similar between monocytes across groups; vitamin D serum levels and LL-37, human β defensin-2 and IL-10 expression were not correlated. Nitric oxide production was significantly higher in healthy volunteers than in type 2 diabetes mellitus patients with low vitamin D serum levels at D3 post-infection (p ≤ 0.05).

Conclusions

Our results show that monocytes from type 2 diabetes mellitus patients and low vitamin D serum levels show an impaired ability to control the intracellular growth of M. tuberculosis, which is not associated with significant decrease of LL-37 or human β defensin-2 expression. Vitamin D could be the link between diabetes and tuberculosis susceptibility.

Electronic supplementary material

The online version of this article (10.1186/s12879-017-2705-1) contains supplementary material, which is available to authorized users.

Diabetes and Tuberculosis

The increase in type 2 diabetes mellitus (DM) patients in countries where tuberculosis (TB) is also endemic has led to the reemerging importance of DM as a risk factor for TB. DM causes a 3-fold increase in TB risk and a 2-fold increase in adverse TB treatment outcomes. Given the sheer numbers of DM patients worldwide, there are now more TB patients with TB-DM comorbidity than TB-HIV coinfection. There is an urgent need to implement strategies for TB prevention and control among the millions of DM patients exposed to Mycobacterium tuberculosis. This chapter summarizes the current epidemiological, clinical, and immunological knowledge on TB and DM and their clinical and public health implications. These include the underlying mechanisms for TB risk in DM patients and their clinical and sociodemographic characteristics that distinguish them from TB patients without DM. TB-DM comorbidity is posing a new challenge for integrating the short-term care for TB with the long-term care for DM, particularly in low- and middle-income countries.

Defining a Research Agenda to Address the Converging Epidemics of Tuberculosis and Diabetes: Part 2: Underlying Biologic Mechanisms

There is growing interest in the re-emerging interaction between type 2 diabetes (DM) and TB, but the underlying biologic mechanisms are poorly understood despite their possible implications in clinical management. Experts in epidemiologic, public health, basic science, and clinical studies recently convened and identified research priorities for elucidating the underlying mechanisms for the co-occurrence of TB and DM. We identified gaps in current knowledge of altered immunity in patients with DM during TB, where most studies suggest an underperforming innate immunity, but exaggerated adaptive immunity to Mycobacterium tuberculosis. Various molecular mechanisms and pathways may underlie these observations in the DM host. These include signaling induced by excess advanced glycation end products and their receptor, higher levels of reactive oxidative species and oxidative stress, epigenetic changes due to chronic hyperglycemia, altered nuclear receptors, and/or differences in cell metabolism (immunometabolism). Studies in humans at different stages of DM (no DM, pre-DM, and DM) or TB (latent or active TB) should be complemented with findings in animal models, which provide the unique opportunity to study early events in the host-pathogen interaction. Such studies could also help identify biomarkers that will complement clinical studies in order to tailor the prevention of TB-DM, or to avoid the adverse TB treatment outcomes that are more likely in these patients. Such studies will also inform new approaches to host-directed therapies.

Influence of diabetes mellitus on immunity to human tuberculosis

Type 2 diabetes mellitus(DM) is a major risk factor for the development of active pulmonary tuberculosis (TB), with development of DM pandemic in countries where TB is also endemic. Understanding the impact of DM on TB and the determinants of co-morbidity is essential in responding to this growing public health problem with improved therapeutic approaches. Despite the clinical and public health significance posed by the dual burden of TB and DM, little is known about the immunological and biochemical mechanisms of susceptibility. One possible mechanism is that an impaired immune response in patients with DM facilitates either primary infection with Mycobacterium tuberculosis or reactivation of latent TB. Diabetes is associated with immune dysfunction and alterations in the components of the immune system, including altered levels of specific cytokines and chemokines. Some effects of DM on adaptive immunity that are potentially relevant to TB defence have been identified in humans. In this review, we summarize current findings regarding the alterations in the innate and adaptive immune responses and immunological mechanisms of susceptibility of patients with DM to M. tuberculosis infection and disease.

Diabetes Mellitus and Latent Tuberculosis Infection: A Systematic Review and Metaanalysis

Background

Despite the well-documented association between diabetes and active tuberculosis, evidence of the association between diabetes and latent tuberculosis infection (LTBI) remains limited and inconsistent.

Methods

We included observational studies that applied either the tuberculin skin test or the interferon gamma release assay for diagnosis of LTBI and that provided adjusted effect estimate for the association between diabetes and LTBI. We searched PubMed and EMBASE through 31 January 2016. The risk of bias of included studies was assessed using a quality assessment tool modified from the Newcastle-Ottawa scale.

Results

Thirteen studies (1 cohort study and 12 cross-sectional studies) were included, involving 38263 participants. The cohort study revealed an increased but nonsignificant risk of LTBI among diabetics (risk ratio, 4.40; 95% confidence interval [CI], 0.50-38.55). For the cross-sectional studies, the pooled odds ratio from the random-effects model was 1.18 (95% CI, 1.06-1.30), with a small statistical heterogeneity across studies (I2, 3.5%). The risk of bias assessment revealed several methodological issues, but the overall direction of biases would reduce the positive causal association between diabetes and LTBI.

Conclusions

Diabetes was associated with a small but statistically significant risk for LTBI. Findings from this review could be used to inform future cost-effectiveness analysis on the impact of LTBI screening programs among diabetics.

Profile of glycated-hemoglobin, antioxidant vitamin and cytokine levels in pulmonary tuberculosis patients: A cross sectional study at Pulmonary Diseases Center Semarang City, Indonesia

Background

Uncontrolled blood glucose, which marked by high level of HbA1c, increases risk of pulmonary TB because of cellular immunity dysfunction. This study aimed to analyze profile of glycated hemoglobin, antioxidant vitamins status and cytokines levels in active pulmonary TB patients.

Methods

This was a cross sectional study, conducted at Pulmonary Diseases Center Semarang City, Indonesia. Study subject consisted of 62 pulmonary TB patients, diagnosed with positive acid fast bacilli and chest X-ray. ELISA was used to measure IFN-γ and IL-12. Status of antioxidant vitamins was determined by concentration of vitamin A and E using HPLC. Blood glucose control was determined by HbA1c concentration (HbA1c ≥7% is considered as uncontrolled).

Results

A significant difference of age between pulmonary tuberculosis patients with normal and uncontrolled blood glucose (p = 0.000) was showed, while all other characteristics (sex, education, occupation) did not differ with p = 0.050, 0.280, 0.380 respectively. Mean HbA1c was 7.25 ± 2.70%. Prevalence of uncontrolled glucose among pulmonary TB patients was 29%. Levels of IFN-γ and IL-12 did not differ according to HbA1c concentration (p = 0.159 and p = 0.965 respectively). Pulmonary tuberculosis patients with uncontrolled blood glucose has higher vitamin E (p = 0.006), while vitamin A did not differ significantly (p = 0.478).

Conclusions

This study supports the importance of performing diabetes screening among pulmonary TB patients. Further study needs to be done to determine the feasibility of TB-DM co-management.

NK-CD11c+ Cell Crosstalk in Diabetes Enhances IL-6-Mediated Inflammation during Mycobacterium tuberculosis Infection

In this study, we developed a mouse model of type 2 diabetes mellitus (T2DM) using streptozotocin and nicotinamide and identified factors that increase susceptibility of T2DM mice to infection by Mycobacterium tuberculosis (Mtb). All Mtb-infected T2DM mice and 40% of uninfected T2DM mice died within 10 months, whereas all control mice survived. In Mtb-infected mice, T2DM increased the bacterial burden and pro- and anti-inflammatory cytokine and chemokine production in the lungs relative to those in uninfected T2DM mice and infected control mice. Levels of IL-6 also increased. Anti-IL-6 monoclonal antibody treatment of Mtb-infected acute- and chronic-T2DM mice increased survival (to 100%) and reduced pro- and anti-inflammatory cytokine expression. CD11c+ cells were the major source of IL-6 in Mtb-infected T2DM mice. Pulmonary natural killer (NK) cells in Mtb-infected T2DM mice further increased IL-6 production by autologous CD11c+ cells through their activating receptors. Anti-NK1.1 antibody treatment of Mtb-infected acute-T2DM mice increased survival and reduced pro- and anti-inflammatory cytokine expression. Furthermore, IL-6 increased inflammatory cytokine production by T lymphocytes in pulmonary tuberculosis patients with T2DM. Overall, the results suggest that NK-CD11c+ cell interactions increase IL-6 production, which in turn drives the pathological immune response and mortality associated with Mtb infection in diabetic mice.

Modulation of dendritic cell and monocyte subsets in tuberculosis-diabetes co-morbidity upon standard tuberculosis treatment

Type 2 diabetes mellitus (DM) is a major risk factor for the development of active pulmonary tuberculosis (PTB), with development of DM pandemic in countries where tuberculosis (TB) is also endemic. However, the effect of anti-TB treatment on the changes in dentritic cell (DC) and monocyte subset phenotype in TB-DM co-morbidity is not well understood. In this study, we characterized the frequency of DC and monocyte subsets in individuals with PTB with (PTB-DM) or without coincident diabetes mellitus (PTB-NDM) before, during and after completion of anti-TB treatment. PTB-DM is characterized by diminished frequencies of plasmacytoid and myeloid DCs and classical and intermediate monocytes at baseline and 2 months of anti-TB treatment but not following 6 months of treatment completion in comparison to PTB-NDM. DC and monocyte subsets exhibit significant but borderline correlation with fasting blood glucose and glycated hemoglobin levels. Finally, while minor changes in the DC and monocyte compartment were observed at 2 months of treatment, significantly increased frequencies of plasmacytoid and myeloid DCs and classical and intermediate monocytes were observed at the successful completion of anti-TB treatment. Our data show that coincident diabetes alters the frequencies of innate subset distribution of DC and monocytes in TB-DM co-morbidity and suggests that most of these changes are reversible following anti-TB therapy.