NATCON 2022 Panel discussion: "TB vaccination - Going Forward"

Vaccination is important tuberculosis (TB) preventive strategy that is essential to achieve the goals of the End TB strategy. The BCG vaccination at birth offers protection against TB in young children but not in adolescents and adults. New TB vaccines are the need of the hour. The TB vaccine development pipeline in the past years is encouraging with newer TB vaccines in clinical trials in humans. The focus of the newer TB vaccine is the prevention of infection, disease, and recurrence of TB disease. Therapeutic vaccines focus on better treatment outcomes and prevention of TB recurrence. BCG revaccination is of current interest. Novel, safe, and efficient TB vaccines that prevent TB infection and disease if introduced in 2025 could drastically reduce the rate of TB incidence. However, the development of an effective vaccine for TB is challenging. Engagement of stakeholders, mobilizing funding, and advocacy could accelerate the newer TB vaccine development process.

Low body mass index is associated with diminished plasma cytokines and chemokines in both active and latent tuberculosis

Introduction

Low body mass index (BMI) is a major risk factor for tuberculosis (PTB). Low BMI can impair the immune system and thus might affect TB incidence.

Methods

We examined the plasma levels of Type 1, Type 17, pro-inflammatory, Type 2 and regulatory cytokines and CC and CXC chemokines in PTB and latent TB (LTB) individuals with low BMI (LBMI) or normal BMI (NBMI).

Results

Our data show that PTB is associated with significantly lower levels of IFNγ, TNFα, IL-2, IL-17A, IL-6, IL-12, IL-4 and IL-5 cytokines but significantly higher levels of IL-10, TGFβ and GM-CSF in LBMI compared to NBMI. Similarly, PTB is also associated with significantly lower levels of CCL2, CCL3, CCL11, CXCL1, CXCL9 and CXCL10 chemokines in LBMI compared to NBMI. Our data reveals that LTB is associated with significantly lower levels of IFNγ, TNFα, IL-2, IL1β, IL-12, IL-13 cytokines but significantly higher levels of IL-10, TGFβ, IL-4 and IL-22 in LBMI compared to NBMI. Similarly, LTB is also associated with significantly lower levels of CCL2, CXCL1, CXCL9 and CXCL10 and significantly higher levels of CCL1, CCL3, and CCL4 in LBMI compared to NBMI.

Conclusion

Thus, LBMI has a major impact on the cytokine and chemokine milieu of both PTB and LTB and might predispose to the increased risk of tuberculosis by this immunomodulatory effect.

Inactivated COVID-19 vaccines: durability of Covaxin/BBV152 induced immunity against variants of concern

BACKGROUND

Covaxin/BBV152 is one of the most widely used vaccines against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and one of the few vaccines used extensively in low- and middle-income countries (LMIC).

METHODS

We investigated the effect of Covaxin on the SARS-CoV-2 specific IgG and IgA and neutralizing antibody (NAb) levels at baseline (M0) and at Months 1 (M1), 2 (M2), 3 (M3), 4 (M4), 6 (M6) and 12 (M12) following vaccination in healthcare workers. In addition, we also examined the NAb levels against variant lineages of B.1.617.2 (Delta, India), B.1.617.2.1 (Delta Plus, India), B.1.351 (Beta, SA), B.1.1.7 (Alpha, UK) and B.1.1.529 (Omicron).

RESULTS

Covaxin induces enhanced SARS-CoV-2 binding antibodies of IgG and IgA responses against both spike (S) and nucleocapsid (N) antigens at M1, M2, M3, M4, M6 and M12 in comparison with M0. Our data also reveal that NAb levels against the ancestral strain (Wuhan, wild type) are elevated and sustained at M1, M2, M3, M4, M6 and M12 in comparison with M0 and against variant lineages of B.1.617.2 (Delta, India), B.1.617.2.1 (Delta Plus, India), B.1.351 (Beta, SA) and B.1.1.7 (Alpha, UK) are elevated at M3, M6 and M12 in comparison with M0. However, NAb levels against B.1.1.529 (Omicron) was consistently below the limit of detection except at M12.

CONCLUSION

Thus, Covaxin induces an enhanced humoral immune response, with persistence till at least 12 months post-vaccination against most SARS-CoV-2 variants.

Prime-Boost Vaccination With Covaxin/BBV152 Induces Heightened Systemic Cytokine and Chemokine Responses

Covaxin/BBV152 is a whole virion inactivated SARS-CoV-2 vaccine. The effect of prime-boost vaccination with Covaxin on systemic immune responses is not known. We investigated the effect of Covaxin on the plasma levels of a wide panel of cytokines and chemokines at baseline (M0) and at months 1 (M1), 2 (M2) and 3 (M3) following prime-boost vaccination in healthy volunteers. Our results demonstrate that Covaxin induces enhanced plasma levels of Type 1 cytokines (IFNγ, IL-2, TNFα), Type 2/regulatory cytokines (IL-4, IL-5, IL-10 and IL-13), Type 17 cytokine (IL-17A), other pro-inflammatory cytokines (IL-6, IL-12, IL-1α, IL-1β) and other cytokines (IL-3 and IL-7) but diminished plasma levels of IL-25, IL-33, GM-CSF and Type 1 IFNs. Covaxin also induced enhanced plasma levels of CC chemokine (CCL4) and CXC chemokines (CXCL1, CXCL2 and CX3CL1) but diminished levels of CXCL10. Covaxin vaccination induces enhanced cytokine and chemokine responses as early as month 1, following prime-boost vaccination, indicating robust activation of innate and adaptive immune responses in vaccine recipients.

Plasma Chemokines Are Baseline Predictors of Unfavorable Treatment Outcomes in Pulmonary Tuberculosis

BACKGROUND

Plasma chemokines are biomarkers of greater disease severity, higher bacterial burden, and delayed sputum culture conversion in pulmonary tuberculosis (PTB). Whether plasma chemokines could also serve as biomarkers of unfavorable treatment outcomes in PTB is not known.

METHODS

A cohort of newly diagnosed, sputum smear- and culture-positive adults with drug-sensitive PTB were recruited under the Effect of Diabetes on Tuberculosis Severity study in Chennai, India. Plasma chemokine levels measured before treatment initiation were compared between 68 cases with unfavorable outcomes (treatment failure, death, or recurrence) and 136 control individuals who had recurrence-free cure. A second validation cohort comprising newly diagnosed, culture-positive adults with drug-sensitive TB was used to measure plasma chemokine levels in 20 cases and 40 controls.

RESULTS

Six chemokines (CCL2, CCL3, CCL4, CXCL8, CXCL10, and CX3CL1) were associated with increased risk, while CXCL1 was associated with decreased risk of unfavorable outcomes in unadjusted and adjusted analyses in the test cohort. Similarly, CCL3, CXCL8, and CXCL10 were associated with increased risk of unfavorable treatment outcomes in the validation cohort. Receiver operating characteristic analysis revealed that combinations of CCL3, CXCL8, and CXCL10 exhibited very high sensitivity and specificity in differentiating cases vs controls.

CONCLUSIONS

Our study reveals a plasma chemokine signature that can be used as a novel biomarker for predicting adverse treatment outcomes in PTB.

Antibody responses to the BBV152 vaccine in individuals previously infected with SARS-CoV-2: A pilot study

Background & objectives

Vaccination against SARS-CoV-2 is a recommendation from the World Health Organization as the foremost preference in the current situation to control the COVID-19 pandemic. BBV152 is one of the approved vaccines against SARS-CoV-2 in India. In this study, we determined SARS-CoV-2-specific antibody levels at day 0 (baseline, before vaccination), day 28 ± 2 post-first dose (month 1) and day 56 ± 2 post-first dose (month 2) of BBV152 whole-virion-inactivated SARS-CoV-2 recipients, and compared the antibody responses of individuals with confirmed pre-vaccination SARS-CoV-2 infection to those individuals without prior evidence of infection.

Methods

Blood samples were collected from 114 healthcare professionals and frontline workers who received BBV152 vaccine from February to May & June 2021. Prior infection with SARS-CoV-2 was determined at baseline. Serum samples were used to estimate SARS-CoV-2 nucleoprotein-specific IgG [IgG (N)], spike protein-specific IgG [IgG (S)] and neutralizing antibodies (NAb).

Results

Participants with previous SARS-CoV-2 infection after a single vaccine dose elicited IgG (N) and IgG (S) antibody levels along with NAb binding inhibition responses levels were similar to infection-naïve vaccinated participants who had taken two doses of vaccine.

Interpretation & conclusions

Our preliminary data suggested that a single dose of BBV152-induced humoral immunity in previously infected individuals was equivalent to two doses of the vaccine in infection-naïve individuals. However, these findings need to be confirmed with large sized cohort studies.

Strongyloides stercoralis Coinfection Is Associated With Greater Disease Severity, Higher Bacterial Burden, and Elevated Plasma Matrix Metalloproteinases in Pulmonary Tuberculosis

BACKGROUND

Helminths and tuberculosis (TB) largely overlap at the population level. Whether helminth infections influence disease severity and bacterial burdens in TB is not well understood.

METHODS

This study was conducted to examine the disease severity in a cohort of pulmonary TB (PTB) individuals with (Ss+) or without (Ss-) seropositivity for Strongyloides stercoralis infection.

RESULTS

Ss+ was associated with increased risk of cavitation (odds ratio [OR], 4.54; 95% confidence interval [CI], 2.33-9.04; P < .0001) and bilateral lung involvement (OR, 5.97; 95% CI, 3.03-12.09; P < .0001) in PTB individuals. Ss+ was also associated with higher bacterial burdens (OR, 7.57; 95% CI, 4.18-14.05; P < .0001) in PTB individuals. After multivariate analysis adjusting for covariates, Ss+ was still associated with greater risk of cavitation (adjusted OR [aOR], 3.99; 95% CI, 1.73-9.19; P = .0014), bilateral lung involvement (aOR, 4.09; 95% CI, 1.78-9.41; P = .0011), and higher bacterial burden (aOR, 9.32; 95% CI, 6.30-13.96; P < .0001). Finally, Ss+ was also associated with higher plasma levels of matrix metalloproteinases ([MMP]-1, -2, -7, -8, and -9) in PTB individuals.

CONCLUSIONS

Therefore, our data demonstrate that coexistent Ss infection is associated with greater disease severity and higher bacterial burden in PTB. Our data also demonstrate enhanced plasma levels of MMPs in coinfected individuals, suggesting a plausible biological mechanism for these effects.

Association of Plasma Matrix Metalloproteinase and Tissue Inhibitors of Matrix Metalloproteinase Levels With Adverse Treatment Outcomes Among Patients With Pulmonary Tuberculosis

IMPORTANCE

Identifying biomarkers of treatment response is an urgent need in the treatment of tuberculosis (TB). Matrix metalloproteinases (MMPs) and tissue inhibitors of matrix metalloproteinases (TIMPs) are potential diagnostic biomarkers in pulmonary TB (PTB).

OBJECTIVE

To assess whether baseline plasma levels of MMPs and TIMPs are also prognostic biomarkers for adverse treatment outcomes in patients with PTB.

DESIGN, SETTING, AND PARTICIPANTS

Two different cohorts (test and validation) of individuals with PTB were recruited from 2 different sets of primary care centers in Chennai, India, and were followed up for treatment outcomes. Participants were individuals with newly diagnosed TB that was sputum smear and culture positive and drug sensitive. A total of 68 cases and 133 controls were in the test cohort and 20 cases and 40 controls were in the validation cohort. A nested case-control study was performed by matching case patients to control participants in a 1:2 ratio for age, sex, and body mass index. Data for the test cohort was taken from a study performed from 2014 to 2019, and data for the validation cohort, from a study performed from 2008 to 2012. The data analysis was performed from November 2019 to May 2020.

INTERVENTIONS

Individuals with PTB were treated with antituberculosis chemotherapy for 6 months and followed up for 1 year after completion of treatment.

MAIN OUTCOMES AND MEASURES

Individuals with PTB with adverse outcomes (treatment failure, all-cause mortality, or recurrent TB) were defined as cases and those with favorable outcomes (recurrence-free cure) were defined as controls. Plasma levels of MMPs and TIMPs were measured before treatment as potential biomarkers.

RESULTS

In all, 68 cases and 133 matched controls were enrolled in the study (170 [85%] males and 31 [15%] females; median age, 45 years [range, 23-73 years]) in the test cohort and 20 cases with 40 matched controls (51 [85%] males and 9 [15%] females; median age, 45 years [range, 19-61 years]) in the validation cohort. Baseline plasma levels of 5 MMPs and 2 TIMPs in the test cohort and 5 MMPs and all 4 TIMPS in the validation cohort were significantly higher in cases vs controls. In the test cohort, the geometric means (GMs), cases vs controls, were as follows: for MMP-1, 3680 vs 2484 pg/mL (P = .008); for MMP-2, 6523 vs 4762 pg/mL (P < .001); for MMP-7, 3346 vs 2100 pg/mL (P < .001); for MMP-8, 1915 vs 1066 pg/mL (P < .001); for MMP-9, 2774 vs 2336 pg/mL (P = .009); for TIMP-1, 4491 vs 2910 pg/mL (P < .001); and for TIMP-2, 3082 vs 2115 pg/mL (P < .001). In the validation cohort, the GMs, cases vs controls were as follows: for MMP-1, 3680 vs 2484 pg/mL (P < .001); for MMP-2, 6523 vs 4762 pg/mL (P < .001); for MMP-7, 3346 vs 2100 pg/mL (P < .001); for MMP-9, 1915 vs 1066 pg/mL (P < .001); for MMP-13, 2774 vs 2336 pg/mL (P < .001); for TIMP-1, 4491 vs 2910 pg/mL (P = .003); for TIMP-2, 3082 vs 2115 pg/mL (P = .003); for TIMP-3, 2066 vs 1020 pg/mL (P < .001); and for TIMP-4, 2130 vs 694 pg/mL (P < .001). Plasma levels of MMPs and TIMPs were associated with increased risk of adverse outcomes according to both univariate and multivariable analysis in the test cohort (eg, univariate analysis: odds ratio [OR] for MMP-8, 2.04; 95% CI, 1.33-3.14; P = .001; multivariable analysis: OR for MMP-8, 2.16; 95% CI, 1.34-3.47; P = .001). Combined receiver operating characteristic analysis revealed significant area under the curve (AUC), with high sensitivity and specificity in both cohorts (eg, for a combination of MMP-2, MMP-7, and TIMP-1 in the test cohort: sensitivity, 84%; specificity, 83%; and AUC, 0.886; for a combination of MMP-2, MMP-7, TIMP-1, and TIMP-2 in the validation cohort: sensitivity, 85%; specificity, 95%; and AUC, 0.944).

CONCLUSIONS AND RELEVANCE

Baseline plasma MMP and TIMP levels may be correlates of risk and prognostic biomarkers for treatment failure, relapse, and death in individuals with PTB and merit further evaluation as predictive biomarkers for stratification of patients to shortened or intensified treatment regimens.

Filarial Coinfection Is Associated With Higher Bacterial Burdens and Altered Plasma Cytokine and Chemokine Responses in Tuberculous Lymphadenitis

Filarial infections are known to modulate cytokine responses in pulmonary tuberculosis by their propensity to induce Type 2 and regulatory cytokines. However, very little is known about the effect of filarial infections on extra-pulmonary forms of tuberculosis. Thus, we have examined the effect of filarial infections on the plasma levels of various families of (IL-1, IL-12, γC, and regulatory) cytokines and (CC and CXC) chemokines in tuberculous lymphadenitis coinfection. We also measured lymph node culture grades in order to assess the burden of Mycobacterium tuberculosis in the two study groups [Fil+ (n = 67) and Fil– (n = 109)]. Our data reveal that bacterial burden was significantly higher in Fil+ compared to Fil– individuals. Plasma levels of IL-1 family (IL-1α, IL-β, IL-18) cytokines were significantly lower with the exception of IL-33 in Fil+ compared to Fil– individuals. Similarly, plasma levels of IL-12 family cytokines -IL-12 and IL-23 were significantly reduced, while IL-35 was significantly elevated in Fil+ compared to Fil– individuals. Filarial infection was also associated with diminished levels of IL-2, IL-9 and enhanced levels of IL-4, IL-10, and IL-1Ra. Similarly, the Fil+ individuals were linked to elevated levels of different CC (CCL-1, CCL-2, CCL-3, CCL-11) and CXC (CXCL-2, CXCL-8, CXCL-9, CXCL-11) chemokines. Therefore, we conclude that filarial infections exert powerful bystander effects on tuberculous lymphadenitis, effects including modulation of protective cytokines and chemokines with a direct impact on bacterial burdens.

Matrix Metalloproteinases and Tissue Inhibitors of Metalloproteinases Are Potential Biomarkers of Pulmonary and Extra-Pulmonary Tuberculosis

Matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinase (TIMPs) are potential regulators of tuberculosis (TB) pathology. Whether they are candidates for non-sputum-based biomarkers for pulmonary TB (PTB) and extra-pulmonary TB (EPTB) is not fully understood. Hence, to examine the association of MMPs and TIMPs with PTB and EPTB, we have measured the circulating levels of MMPs (MMP-1, 2, 3, 7, 8, 9, 12, and 13) and TIMPs (TIMP-1, 2, 3, and 4) in PTB, EPTB and compared them with latent tuberculosis (LTB) or healthy control (HC) individuals. We have also assessed their circulating levels before and after the completion of anti-tuberculosis treatment (ATT). Our data describes that systemic levels of MMP-1, 8, 9, 12 were significantly increased in PTB compared to EPTB, LTB, and HC individuals. In contrast, MMP-7 was significantly reduced in PTB compared to EPTB individuals. Likewise, the systemic levels of MMP-1, 7, 13 were significantly increased in EPTB in comparison to LTB and HC individuals. In contrast, MMP-8 was significantly reduced in EPTB individuals compared to LTB and HC individuals. In addition, the systemic levels of TIMP-1, 2, 3 were significantly diminished and TIMP-4 levels were significantly enhanced in PTB compared to EPTB, LTB, and HC individuals. The circulating levels of TIMP-2 was significantly reduced and TIMP-3 was significantly elevated in EPTB individuals in comparison with LTB and HCs. Some of the MMPs (7, 8, 9, 12, 13 in PTB and 1, 7, 8, 9 in EPTB) and TIMPs (1, 2, 3, 4 in PTB and 4 in EPTB) were significantly modulated upon treatment completion. ROC analysis showed that MMP-1, 9 and TIMP-2, 4 could clearly discriminate PTB from EPTB, LTB and HCs and MMP-13 and TIMP-2 could clearly discriminate EPTB from LTB and HCs. Additionally, multivariate analysis also indicated that these alterations were independent of age and sex in PTB and EPTB individuals. Therefore, our data demonstrates that MMPs and TIMPs are potential candidates for non-sputum-based biomarkers for differentiating PTB and EPTB from LTB and HC individuals.

Altered Systemic Adipokine Levels in Pulmonary Tuberculosis and Changes following Treatment

Pulmonary tuberculosis (PTB) is associated with modulation of levels of adipokines, specifically adiponectin and leptin, but the effect of standard antituberculosis treatment (ATT) on the systemic levels of adiponectin, resistin, and leptin has not been well explored. To identify the association of adipokines with PTB and their relationship with disease severity and bacterial burden, we measured the levels of adiponectin, resistin, and leptin in PTB individuals and compared them with latent tuberculosis (LTB) and healthy control (HC) individuals. Pulmonary tuberculosis was characterized by diminished circulating levels of adiponectin and leptin and heightened circulating levels of resistin in comparison to that in LTB and HC individuals. However, PTB with bilateral or cavitary disease did not exhibit any increased systemic levels of these adipokines in comparison with those with unilateral or non-cavitary disease, respectively. In addition, none of the adipokines exhibited a positive correlation with bacterial burdens, but adiponectin alone exhibited a negative correlation with body mass index in PTB individuals. Finally, on successful completion of ATT, PTB individuals exhibited significantly increased levels of adiponectin and leptin and significantly decreased levels of resistin. Therefore, our data identify an important association of systemic adipokine levels with PTB disease and its alteration following ATT.

Plasma Proinflammatory Cytokines Are Markers of Disease Severity and Bacterial Burden in Pulmonary Tuberculosis

Background

Type 1, type 17, and other proinflammatory cytokines are important in host immunity to tuberculosis (TB) in animal models. However, their role in human immunity to TB is not completely understood.

Methods

To examine the association of proinflammatory cytokines with pulmonary TB (PTB), we examined the plasma levels of type 1 (interferon [IFN]γ and tumor necrosis factor [TNF]α), type 17 (interleukin [IL]-17A and IL-17F), and other proinflammatory (IL-6, IL-12, and IL-1β) cytokines in individuals with PTB, latent TB (LTB), or healthy controls (HC).

Results

Individuals with PTB exhibited significantly higher plasma levels of most of the above cytokines compared with LTB or HC individuals. Principal component analysis based on these cytokines could clearly distinguish PTB from both LTB or HC individuals. Pulmonary TB individuals with bilateral or cavitary disease exhibited significantly higher levels of IFNγ, TNFα, IL-17A, and IL-1β compared with those with unilateral or noncavitary disease. Pulmonary TB individuals also exhibited a significant positive relationship between IFNγ, TNFα, and IL-17A levels and bacterial burdens. In addition, PTB individuals with delayed culture conversion exhibited significantly higher levels of IFNγ, TNFα, IL-17A, and IL-1β at baseline. Finally, the plasma levels of all the cytokines examined were significantly reduced after successful chemotherapy.

Conclusions

Therefore, our data demonstrate that PTB is associated with heightened levels of plasma proinflammatory cytokines, which are reversed after chemotherapy. Our data also reveal that proinflammatory cytokines are markers of disease severity, bacterial burden, and delayed culture conversion in PTB.

Altered circulating levels of B cell growth factors and their modulation upon anti-tuberculosis treatment in pulmonary tuberculosis and tuberculous lymphadenitis

B cell activating factor/a proliferation-inducing ligand (BAFF/APRIL) are members of the tumor necrosis factor alpha (TNF) α family of ligands, which are essential for B cell survival, development, and modulation of the immune system. To examine the association of circulating levels of BAFF and APRIL with pulmonary tuberculosis (PTB) and tuberculous lymphadenitis (TBL), we measured the systemic levels of APRIL and BAFF in individuals with PTB, TBL, latent tuberculosis (LTB) and healthy controls (HC). Further, we also examined the pre and post-treatment plasma levels of above-mentioned parameters in PTB and TBL individuals upon completion of anti-TB chemotherapy. Next, the association of these cytokines either with extent of disease, disease severity, bacterial burden in PTB and lymph node culture grade or the lymph node size in TBL was also assessed. Finally, ROC analysis was performed to examine the discrimination capacity of APRIL and BAFF between PTB or TBL with LTB. Our study revealed significantly diminished plasma levels of APRIL in PTB and higher plasma levels of BAFF in both PTB and TBL individuals compared to LTB and HC. Furthermore, we observed a significant increase in APRIL levels in TBL and significantly decreased plasma levels of BAFF in both PTB and TBL after the completion of successful anti-TB treatment. There was no statistically positive relationship between BAFF and APRIL levels and the extent of disease, disease severity and bacterial burden in PTB. In TBL, there was a significant correlation between APRIL (but not BAFF) levels with lymph node culture grades. In contrast, APRIL in PTB and BAFF in TBL were able to clearly discriminate from LTB in ROC analysis. In summary, our results showed altered levels of BAFF/APRIL and their modulation upon chemotherapy, suggesting that these cytokines might be involved in the immune-modulation of TB infection.

Modulation of Th1/Tc1 and Th17/Tc17 responses in pulmonary tuberculosis by IL-20 subfamily of cytokines

Although IL-10 is known to be an important cytokine in the immune response to TB, very little is known about the role of IL-20 subfamily of cytokines in the host response to TB. To identify the role of CD4+ T and CD8+ T cells producing IL-20 subfamily of cytokines in human TB, we enumerated the frequencies of IL-10, IL-19 and IL-24 expressing CD4+ and CD8+ T cells following Mtb-specific antigen stimulation of cells from individuals with pulmonary TB (PTB) and latent TB (LTB). We first demonstrated that Mtb-specific antigen induce an expansion of CD4+ and CD8+ T cells expressing IL-10, IL-19 and IL-24 in PTB and LTB individuals, with frequencies being significantly higher in PTB. Next, we demonstrated that IL-10, IL-19 and IL-24 play an important role in the regulation of CD4+ and CD8+ T cells expressing Th1/Tc1 and Th17/Tc17 cytokines in PTB but not LTB individuals. Thus, active PTB is characterized by an IL-10, IL-19 and IL-24 mediated down modulation of Th1/Tc1 and/or Th17/Tc17 cytokines in CD4+ and CD8+ T cell subsets. This suggests that the IL-20 subfamily of cytokines, similar to IL-10 might play a potentially crucial role in the modulation of T cell responses in active TB disease.

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.

Type 2 diabetes mellitus coincident with pulmonary or latent tuberculosis results in modulation of adipocytokines

Type 2 diabetes mellitus (T2DM) is recognized as major risk factor for the progress of active pulmonary tuberculosis (PTB), although the mechanistic link between diabetes and tuberculosis remains poorly characterized. Moreover, the influence of poorly controlled diabetes on the baseline levels of adipocytokines in the context of tuberculosis has not been explored in detail. To characterize the influence of coexistent DM on adipocytokine levels in pulmonary or latent TB (LTB), we examined circulating levels of adipocytokines in the plasma of individuals with PTB-DM or LTB-DM and compared them with those without DM (PTB or LTB). PTB-DM or LTB-DM is characterized by diminished circulating levels of adiponectin and adipsin and/or heightened circulating levels of leptin, visfatin and PAI-1. In addition, adiponectin and adipsin exhibit a significant negative correlation, whereas leptin, visfatin and PAI-1 display a significant positive correlation with HbA1C levels and random blood glucose levels. Therefore, our data reveal that PTB-DM or LTB-DM is characterized by alterations in the systemic levels of adipocytokines, indicating that altered adipose tissue inflammation underlying Type 2 diabetes potentially contributes to pathogenesis of TB disease.

Circulating Angiogenic Factors as Biomarkers of Disease Severity and Bacterial Burden in Pulmonary Tuberculosis

BACKGROUND

Angiogenesis and lymphangiogenesis are classical features of granuloma formation in pulmonary tuberculosis (PTB). In addition, the angiogenic factor--VEGF-A is a known biomarker for PTB.

AIMS/METHODOLOGY

To examine the association of circulating angiogenic factors with PTB, we examined the systemic levels of VEGF-A, VEGF-C, VEGF-D, VEGF-R1, VEGF-R2 and VEGF-R3in individuals with PTB, latent TB (LTB) or no TB infection (NTB).

RESULTS

Circulating levels of VEGF-A, VEGF-C andVEGF-R2 were significantly higher in PTB compared to LTB or NTB individuals. Moreover, the levels of VEGF-A, VEGF-C and VEGF-R2 were significantly higher in PTB with bilateral and/or cavitary disease. The levels of these factors also exhibited a significant positive relationship with bacterial burdens in PTB. ROC analysis revealed VEGF-A and VEGF-R2 as markers distinguishing PTB from LTB or NTB. Finally, the circulating levels of all the angiogenic factors examined were significantly reduced following successful chemotherapy.

CONCLUSION

Therefore, our data demonstrate that PTB is associated with elevated levels of circulating angiogenic factors, possibly reflecting vascular and endothelial dysfunction. In addition, some of these circulating angiogenic factors could prove useful as biomarkers to monitor disease severity, bacterial burden and therapeutic responses.

Number of sputum specimens during treatment follow-up of tuberculosis patients: two or one?

SETTING

National Institute for Research in Tuberculosis clinics in Chennai and Madurai, India.

OBJECTIVE

To examine the pattern of serial smears (negative-negative [NN], negative-positive [NP], positive-negative [PN], positive-positive [PP]) during treatment follow-up of culture-confirmed new smear-positive tuberculosis (TB) patients, and the proportion of culture-negatives in each category.

DESIGN

We reviewed the records and extracted follow-up smear (fluorescent microscopy) and culture (Löwenstein-Jensen) results of patients enrolled in clinical trials from January 2000 to August 2012 and treated with the Category I regimen (2EHRZ3/4HR3). Data entry and analysis were performed using EpiData.

RESULTS

Among 520 patients (176 infected with the human immunodeficiency virus), the proportions of culture-negative patients with NN, discordant (PN or NP) and PP patterns were approximately 98%, 80% and 40%, respectively. The smear-positive culture-negative phenomenon was more frequent in follow-up smear results graded 1+, followed by 2+ and 3+.

CONCLUSION

There is justification for discontinuing the examination of second specimens during treatment follow-up among TB patients. However, a positive result on the first smear needs to be confirmed by a second positive result before making clinical management decisions. The World Health Organization may need to reconsider its recommendation on this issue.

Type 2 diabetes - Tuberculosis co-morbidity is associated with diminished circulating levels of IL-20 subfamily of cytokines

IL-20 subfamily of cytokines play an important role in both host defense mechanisms and glucose metabolism. Since, the interaction between tuberculosis (TB) and diabetes (DM) involves both of the above processes, we examined the association of IL-20 subfamily of cytokines in TB-DM co-morbidity. We examined circulating plasma cytokine levels in individuals with active TB with (PTB-DM) or without (PTB) diabetes and also those with latent TB with (LTB-DM) or without (LTB) diabetes. PTB-DM is characterized by diminished circulating levels of IL-19, IL-20, IL-22 and IL-24 but increased levels of IL-10. Similarly, LTB-DM was also characterized by diminished circulating levels of IL-10, IL-19, IL-20 and IL-24 but increased levels of IL-22. Moreover, there was a significant negative correlation of IL-10, IL-19, IL-20, IL-22 and IL-24 levels with hemoglobin A1C (HbA1c) levels in both PTB and/or LTB individuals. Finally, PTB is characterized by diminished levels of IL-19, IL-20, IL-22 and IL-24 in comparison to LTB individuals. Our data reveal that coincident diabetes in either PTB or LTB is characterized by decreased production of the IL-20 subfamily of cytokines and suggest that these cytokines might play an important role in pathogenesis or protection.

Heme Oxygenase-1 Regulation of Matrix Metalloproteinase-1 Expression Underlies Distinct Disease Profiles in Tuberculosis

Pulmonary tuberculosis (TB) is characterized by oxidative stress and lung tissue destruction by matrix metalloproteinases (MMPs). The interplay between these distinct pathological processes and the implications for TB diagnosis and disease staging are poorly understood. Heme oxygenase-1 (HO-1) levels were previously shown to distinguish active from latent TB, as well as successfully treated Mycobacterium tuberculosis infection. MMP-1 expression is also associated with active TB. In this study, we measured plasma levels of these two important biomarkers in distinct TB cohorts from India and Brazil. Patients with active TB expressed either very high levels of HO-1 and low levels of MMP-1 or the converse. Moreover, TB patients with either high HO-1 or MMP-1 levels displayed distinct clinical presentations, as well as plasma inflammatory marker profiles. In contrast, in an exploratory North American study, inversely correlated expression of HO-1 and MMP-1 was not observed in patients with other nontuberculous lung diseases. To assess possible regulatory interactions in the biosynthesis of these two enzymes at the cellular level, we studied the expression of HO-1 and MMP-1 in M. tuberculosis-infected human and murine macrophages. We found that infection of macrophages with live virulent M. tuberculosis is required for robust induction of high levels of HO-1 but not MMP-1. In addition, we observed that CO, a product of M. tuberculosis-induced HO-1 activity, inhibits MMP-1 expression by suppressing c-Jun/AP-1 activation. These findings reveal a mechanistic link between oxidative stress and tissue remodeling that may find applicability in the clinical staging of TB patients.

Effect of 1,25-dihydroxy vitamin D3 on cathelicidin expression in patients with and without cavitary tuberculosis

1,25-dihydroxy vitamin D3 (1,25(OH)2D3) is a potent immuno-modulator which induces LL-37, the active peptide of cathelicidin, and restricts the growth of Mycobacterium tuberculosis (Mtb) in human macrophages. In the present study, we investigated the effect of 1,25(OH)2D3 on cathelicidin antimicrobial peptide (CAMP) expression in healthy controls (HCs) and pulmonary tuberculosis (PTB) patients. Peripheral blood mononuclear cells (PBMCs) from 50 HCs and 35 PTB patients were cultured for 72 h either with Mtb alone or Mtb with 1,25(OH)2D3 at 10(-7) M concentration. 1,25(OH)2D3 significantly up regulated the macrophage phagocytosis, CD14, CAMP gene expression and hCAP18 protein in HCs and PTB patients (p < 0.05). A significant positive correlation was observed between macrophage phagocytosis and CAMP gene expression in both the study groups (p < 0.05). Moreover, 1,25(OH)2D3 up regulated CAMP gene expression was more prominent in PTB patients without lung cavity (less severe form of disease) as compared to patients with cavitary TB (severe form of disease) (p < 0.05). The present study suggests that vitamin D may be used as an adjunct to anti-TB treatment and may be useful for a quicker recovery from less severe forms of TB disease.

Profiling leucocyte subsets in tuberculosis-diabetes co-morbidity

The immune system plays an important role in the pathogenesis of pulmonary tuberculosis-type 2 diabetes mellitus (PTB-DM) co-morbidity. However, the phenotypic profile of leucocyte subsets at homeostasis in individuals with active or latent tuberculosis (LTB) with coincident diabetes is not known. To characterize the influence of diabetes on leucocyte phenotypes in PTB or LTB, we examined the frequency (Fo ) of leucocyte subsets in individuals with TB with (PTB-DM) or without (PTB) diabetes; individuals with latent TB with (LTB-DM) or without (LTB) diabetes and non-TB-infected individuals with (NTB-DM) or without (NTB) diabetes. Coincident DM is characterized by significantly lower Fo of effector memory CD4(+) T cells in LTB individuals. In contrast, DM is characterized by significantly lower Fo of effector memory CD8(+) T cells and significantly higher Fo of central memory CD8(+) T cells in PTB individuals. Coincident DM resulted in significantly higher Fo of classical memory B cells in PTB and significantly higher Fo of activated memory and atypical B cells in LTB individuals. Coincident DM resulted in significantly lower Fo of classical and intermediate monocytes in PTB, LTB and NTB individuals. Finally, DM resulted in significantly lower Fo of myeloid and plasmacytoid dendritic cells in PTB, LTB and NTB individuals. Our data reveal that coincident diabetes alters the cellular subset distribution of T cells, B cells, dendritic cells and monocytes in both individuals with active TB and those with latent TB, thus potentially impacting the pathogenesis of this co-morbid condition.

IL-27 and TGFβ mediated expansion of Th1 and adaptive regulatory T cells expressing IL-10 correlates with bacterial burden and disease severity in pulmonary tuberculosis

CD4⁺ T cell expression of IL-10 is an important mechanism controlling immunity to tuberculosis (TB). To identify the CD4⁺ T cell subsets producing IL-10 in human TB, we enumerated the frequencies of IL-10 expressing CD4⁺ T cell subsets following TB—antigen stimulation of cells from individuals with pulmonary (PTB) and latent TB (LTB). We first demonstrate that TB antigens induce an expansion of IL-10 expressing Th1 (IL-10⁺, IFNγ⁺, T-bet⁺), Th2 (IL-10⁺, IL-4⁺, GATA-3⁺), Th9 (IL-10⁺, IL-9⁺, IL-4⁻), Th17 (IL-10⁺, IL-17⁺, IFNγ⁻), and natural and adaptive regulatory T cells [nTregs; IL-10⁺, CD4⁺, CD25⁺, Foxp3⁺ and aTregs; IL-10 single⁺, CD4⁺, CD25⁻, Foxp3⁻] in PTB and LTB individuals, with frequencies being significantly higher in the former. However, only Th1 cells and adaptive Tregs expressing IL-10 exhibit a positive relationship with bacterial burdens and extent of disease in PTB. Finally, we show that IL-27 and TGFβ play an important role in the regulation of IL-10⁺ Th cell subsets. Thus, active PTB is characterized by an IL-27 and TGFβ mediated expansion of IL-10 expressing CD4⁺ T cell subsets, with IL-10⁺ Th1 and IL-10⁺ aTreg cells playing a potentially pivotal role in the pathogenesis of active disease.

Type 2 diabetes mellitus is associated with altered CD8(+) T and natural killer cell function in pulmonary tuberculosis

Type 2 diabetes mellitus (DM) is associated with expanded frequencies of mycobacterial antigen-specific CD4(+) T helper type 1 (Th1) and Th17 cells in individuals with active pulmonary tuberculosis (TB). No data are available on the role of CD8(+) T and natural killer (NK) cells in TB with coincident DM. To identify the role of CD8(+) T and NK cells in pulmonary TB with diabetes, we examined mycobacteria-specific immune responses in the whole blood of individuals with TB and DM (TB-DM) and compared them with those without DM (TB-NDM). We found that TB-DM is characterized by elevated frequencies of mycobacterial antigen-stimulated CD8(+) T cells expressing type 1 [interferon-γ and interleukin-2 (IL-2)] and type 17 (IL-17F) cytokines. We also found that TB-DM is characterized by expanded frequencies of TB antigen-stimulated NK cells expressing type 1 (tumour necrosis factor-α) and type 17 (IL-17A and IL-17F) cytokines. In contrast, CD8(+) T cells were associated with significantly diminished expression of the cytotoxic markers perforin, granzyme B and CD107a both at baseline and following antigen or anti-CD3 stimulation, while NK cells were associated with significantly decreased antigen-stimulated expression of CD107a only. This was not associated with alterations in CD8(+) T-cell or NK cell numbers or subset distribution. Therefore, our data suggest that pulmonary TB complicated with type 2 DM is associated with an altered repertoire of cytokine-producing and cytotoxic molecule-expressing CD8(+) T and NK cells, possibly contributing to increased pathology.

Are we justified in treating for multidrug-resistant tuberculosis based on positive follow-up smear results?

SETTING

National Institute for Research in Tuberculosis, India.

OBJECTIVE

To assess, among new culture-confirmed smear-positive pulmonary tuberculosis (TB) patients, the proportion of follow-up smear-positives that were culture-negative (S+C-) by month of follow-up examination, human immunodeficiency virus (HIV) status, pre-treatment drug susceptibility status and smear grading.

DESIGN

We extracted follow-up smear (fluorescence microscopy) and culture (Löwenstein-Jensen) results of patients enrolled in clinical trials from January 2000 to August 2012 and treated with the WHO Category I regimen (2EHRZ3/4HR3).

RESULTS

Of 520 patients, including 176 who were HIV-infected, respectively 199, 81, 47 and 43 were smear-positive at months 2, 4, 5 and 6; of these, respectively 138 (69%), 62 (75%), 32 (68%) and 27 (63%) were culture-negative. The S+C- phenomenon was more pronounced among '1+ positive' patients than in 2+ or 3+ positive patients and in 'pan-susceptible' patients than in those with any resistance, and did not vary by HIV status.

CONCLUSION

Nearly two thirds of patients with follow-up smears positive at months 5 and 6 were culture-negative. Starting multidrug-resistant TB (MDR-TB) treatment empirically based on smear results, even in resource-limited settings, is incorrect and can have hazardous consequences. There is an urgent need to revisit the WHO recommendation concerning empirical MDR-TB treatment.

Coincident pre-diabetes is associated with dysregulated cytokine responses in pulmonary tuberculosis

BACKGROUND

Cytokines play an important role in the pathogenesis of pulmonary tuberculosis (PTB)--Type 2 diabetes mellitus co-morbidity. However, the cytokine interactions that characterize PTB coincident with pre-diabetes (PDM) are not known.

METHODS

To identify the influence of coincident PDM on cytokine levels in PTB, we examined circulating levels of a panel of cytokines in the plasma of individuals with TB-PDM and compared them with those without PDM (TB-NDM).

RESULTS

TB-PDM is characterized by elevated circulating levels of Type 1 (IFNγ, TNFα and IL-2), Type 17 (IL-17A and IL-17F) and other pro-inflammatory (IL-1β, IFNβ and GM-CSF) cytokines. TB-PDM is also characterized by increased systemic levels of Type 2 (IL-5) and regulatory (IL-10 and TGFβ) cytokines. Moreover, TB antigen stimulated whole blood also showed increased levels of pro-inflammatory (IFNγ, TNFα and IL-1β) cytokines as well. However, the cytokines did not exhibit any significant correlation with HbA1C levels or with bacterial burdens.

CONCLUSION

Our data reveal that pre-diabetes in PTB individuals is characterized by heightened cytokine responsiveness, indicating that a balanced pro and anti - inflammatory cytokine milieu is a feature of pre-diabetes--TB co-morbidity.

Decreased frequencies of circulating CD4⁺ T follicular helper cells associated with diminished plasma IL-21 in active pulmonary tuberculosis

Background

Circulating T follicular helper (Tfh) cells represent a distinct subset of CD4⁺ T cells and are important in immunity to infections. Although they have been shown to play a role in experimental models of tuberculosis infection, their role in human tuberculosis remains unexplored.

Aims/Methodology

To determine the distribution of circulating Tfh cells in human TB, we measured the frequencies of Tfh cells exvivo and following TB - antigen or polyclonal stimulation in pulmonary TB (PTB; n = 30) and latent TB (LTB; n = 20) individuals, using the markers CXCR5, PD-1 and ICOS.

Results

We found that both exvivo and TB - antigen induced frequencies of Tfh cell subsets was significantly lower in PTB compared to LTB individuals. Similarly, antigen induced frequencies of Tfh cells expressing IL-21 was also significantly lower in PTB individuals and this was reflected in diminished circulating levels of IL-21 and IFNγ. This was not accompanied by diminished frequencies of activated or memory B cell subsets. Finally, the diminution in frequency of Tfh cells in PTB individuals was dependent on IL-10, CTLA-4 and PD-L1 invitro.

Conclusions

Thus, PTB is characterized by adiminution in the frequency of Tfh cell subsets.

Helminth infections coincident with active pulmonary tuberculosis inhibit mono- and multifunctional CD4+ and CD8+ T cell responses in a process dependent on IL-10

Tissue invasive helminth infections and tuberculosis (TB) are co-endemic in many parts of the world and can trigger immune responses that might antagonize each other. We have previously shown that helminth infections modulate the Th1 and Th17 responses to mycobacterial-antigens in latent TB. To determine whether helminth infections modulate antigen-specific and non-specific immune responses in active pulmonary TB, we examined CD4⁺ and CD8⁺ T cell responses as well as the systemic (plasma) cytokine levels in individuals with pulmonary TB with or without two distinct helminth infections—Wuchereria bancrofti and Strongyloides stercoralis infection. By analyzing the frequencies of Th1 and Th17 CD4⁺ and CD8⁺ T cells and their component subsets (including multifunctional cells), we report a significant diminution in the mycobacterial–specific frequencies of mono- and multi–functional CD4⁺ Th1 and (to a lesser extent) Th17 cells when concomitant filarial or Strongyloides infection occurs. The impairment in CD4⁺ and CD8⁺ T cell cytokine responses was antigen-specific as polyclonal activated T cell frequencies were equivalent irrespective of helminth infection status. This diminution in T cell responses was also reflected in diminished circulating levels of Th1 (IFN-γ, TNF-α and IL-2)- and Th17 (IL-17A and IL-17F)-associated cytokines. Finally, we demonstrate that for the filarial co-infections at least, this diminished frequency of multifunctional CD4⁺ T cell responses was partially dependent on IL-10 as IL-10 blockade significantly increased the frequencies of CD4⁺ Th1 cells. Thus, co-existent helminth infection is associated with an IL-10 mediated (for filarial infection) profound inhibition of antigen-specific CD4⁺ T cell responses as well as protective systemic cytokine responses in active pulmonary TB.

While it has long been recognized that helminth infections alter the pathophysiology of allergic and autoimmune disease, data suggest that helminth infections also exert an important immunological effect on concomitant infections and vaccine responses. In particular, helminth coinfection can modulate the severity, pathogenesis and transmission of other infectious diseases. In this study, we examine the mechanism by which helminth infections modulate the immunological responses to tuberculosis antigens in individuals with active pulmonary tuberculosis. Our data suggest that two different helminth infections, with different life cycles, tissue localization and modes of transmission essentially exert very similar effects on the adaptive immune response to tuberculosis antigens in pulmonary tuberculosis. This includes a compromised induction of protective cytokine-expressing T cells as well as inhibitory effects on systemic cytokines that are potentially protective in tuberculosis. The strength of this study lies in the fact that this is the first study to demonstrate that two different helminth infections essentially impair cytokine responses in a similar manner in pulmonary tuberculosis.

Altered CD8(+) T cell frequency and function in tuberculous lymphadenitis

CD8(+) T cells secreting Type1 and Type 17 cytokines and cytotoxic molecules play a major role in immunity and protection against pulmonary tuberculosis (PTB), although their role in tuberculous lymphadenitis (TBL) is not well known. To identify the distribution and function of CD8(+) T cells expressing Type1, Type 2 and Type 17 cytokines and cytotoxic molecules in TBL, we examined baseline and mycobacterial-antigen specific immune responses in the whole blood of individuals with PTB and compared them with TBL. TBL is characterized by elevated frequencies of baseline and mycobacterial-antigen stimulated CD8(+) T cells expressing Type 1 (IL-2 and TNFα) and Type 17 (IL-17A and IL-17F) cytokines in comparison to PTB individuals. In contrast, TBL individuals exhibited diminished frequency of CD8(+) T cells expressing perforin, granzyme B and CD107a. The blockade of IL-1R and IL-6R during antigenic stimulation resulted in significantly diminished frequencies of CD8(+) T cells expressing Type 1 and Type 17 cytokines in TBL. Therefore, our data suggest that TBL is characterized by an IL-1 and IL-6 dependent expansion of CD8(+) T cells expressing Type 1 and Type 17 cytokines as well as altered frequencies of cytotoxic molecules, reflecting an important association of these cells with the pathogenesis of TBL.

Heightened plasma levels of heme oxygenase-1 and tissue inhibitor of metalloproteinase-4 as well as elevated peripheral neutrophil counts are associated with TB-diabetes comorbidity

BACKGROUND

The increased prevalence of type 2 diabetes mellitus (T2DM) in countries endemic for TB poses a serious complication in the clinical management of this major infectious disease. Understanding the impact of T2DM on TB and the determinants of comorbidity is critical in responding to this growing public health problem with better therapeutic approaches. Here, we performed an exploratory study assessing a series of biologic parameters that could serve as markers of pathogenesis in TB with T2DM.

METHODS

Cross-sectional analyses of levels of heme oxygenase-1 (HO-1), acute phase proteins, tissue metalloproteinases, and tissue inhibitors of metalloproteinase (TIMPs) as well as cytokines and chemokines were performed in plasma samples from individuals with active pulmonary TB or with coincident TB and T2DM from South India.

RESULTS

Compared with patients with TB without diabetes, those with coincident T2DM exhibited increased Mycobacterium tuberculosis bacillary loads in sputum. Plasma levels of HO-1 but not of other acute phase proteins were higher in patients with TB and T2DM than in patients without diabetes, independent of bacillary sputum loads. HO-1 concentrations also positively correlated with random plasma glucose, circulating glycosylated hemoglobin, and low-density lipoprotein levels. Moreover, patients with coincident TB and T2DM exhibited increased plasma levels of TIMP-4 and elevated peripheral blood neutrophil counts, which, when considered together with HO-1, resulted in increased power to discriminate individuals with active TB with and without T2DM.

CONCLUSIONS

Elevated plasma levels of HO-1 and TIMP-4 and peripheral blood neutrophil counts are potential single and combined markers of pathogenesis in TB and T2DM.

Type 2 diabetes mellitus coincident with pulmonary tuberculosis is associated with heightened systemic type 1, type 17, and other proinflammatory cytokines

RATIONALE

Type 2 diabetes mellitus is a major risk factor for the development of active tuberculosis, although the biological basis underlying this susceptibility remains poorly characterized.

OBJECTIVES AND METHODS

To identify the influence of coincident diabetes mellitus on cytokine levels in pulmonary tuberculosis, we examined circulating levels of a panel of cytokines and chemokines in the plasma of individuals with tuberculosis with diabetes and compared them with those of individuals without diabetes.

MEASUREMENTS AND MAIN RESULTS

Tuberculosis with diabetes is characterized by elevated circulating levels of type 1 (IFN-γ, tumor necrosis factor-α, and IL-2), type 2 (IL-5), and type 17 (IL-17A) cytokines but decreased circulating levels of IL-22. This was associated with increased systemic levels of other proinflammatory cytokines (IL-1β, IL-6, and IL-18) and an antiinflammatory cytokine (IL-10) but not type 1 IFNs. Moreover, tuberculosis antigen-stimulated whole blood also showed increased levels of proinflammatory cytokines. Finally, type 1 and type 17 cytokines in plasma exhibit a significant positive correlation with hemoglobin A1C levels, indicating that impaired control of diabetes is associated with this proinflammatory milieu. Multivariate analysis revealed that the association of proinflammatory cytokines with diabetes mellitus was not influenced by age, sex, or other metabolic parameters.

CONCLUSIONS

Our data reveal that tuberculosis with diabetes is characterized by heightened cytokine responsiveness, indicating that chronic inflammation underlying type 2 diabetes potentially contributes to increased immune pathology and poor control in tuberculosis infection.

Randomized clinical trial of thrice-weekly 4-month moxifloxacin or gatifloxacin containing regimens in the treatment of new sputum positive pulmonary tuberculosis patients

BACKGROUND

Shortening tuberculosis (TB) treatment duration is a research priority. This paper presents data from a prematurely terminated randomized clinical trial, of 4-month moxifloxacin or gatifloxacin regimens, in South India.

METHODS

Newly diagnosed, sputum-positive HIV-negative pulmonary TB patients were randomly allocated to receive gatifloxacin or moxifloxacin, along with isoniazid and rifampicin for 4 months with pyrazinamide for first 2 months (G or M) or isoniazid and rifampicin for 6 months with ethambutol and pyrazinamide for first 2 months (C). All regimens were administered thrice-weekly. Clinical and bacteriological assessments were done monthly during treatment and for 24 months post-treatment. The Data and Safety Monitoring Board recommended termination of the trial due to high TB recurrence rates in the G and M regimens.

RESULTS

Of 416 patients in intent-to-treat analysis, 6 (5%) of 124, 2 (2%) of 110 and 2 (2%) of 137 patients with drug-susceptible TB in the G, M and C arms respectively had unfavorable response at the end of treatment; during the next 24 months, 17 (15%) of 115, 11 (11%) of 104 and 8 (6%) of 132 patients respectively, had TB recurrence. Of 38 drug-resistant patients 1 of 8 and 3 of 26 in the G and C arms respectively had unfavourable response at the end of treatment; and TB recurrence occurred in 2 of 7 and 2 of 23 patients, respectively. The differences in TB recurrence rates between the G and C arms was statistically significant (p = 0.02). Gastro-intestinal symptoms occurred in 23%, 22% and 9% of patients in the G, M and C arms respectively, but most reactions were mild and manageable with symptomatic measures; 1% required regimen modification.

CONCLUSIONS

4-month thrice-weekly regimens of gatifloxacin or moxifloxacin with isoniazid, rifampicin and pyrazinamide, were inferior to standard 6-month treatment, in patients with newly diagnosed sputum positive pulmonary TB.

TRIAL REGISTRATION

Clinical Trials Registry of India CTRI/2012/10/003060.

Expansion of pathogen-specific T-helper 1 and T-helper 17 cells in pulmonary tuberculosis with coincident type 2 diabetes mellitus

BACKGROUND

Type 2 diabetes mellitus (DM) is a major risk factor for the development of active pulmonary tuberculosis, although the immunological mechanisms underlying this interaction remain unexplored. The influence of poorly controlled diabetes on pathogen-specific T-helper 1 (Th1) and T-helper 17 (Th17) responses have not been examined.

METHODS

To identify the role of Th1 and Th17 cells in tuberculosis with coincident DM, we examined mycobacteria-specific immune responses in the whole blood of individuals who had tuberculosis with DM and compared them to those in individuals who had tuberculosis without DM.

RESULTS

Tuberculosis coincident with DM is characterized by elevated frequencies of monofunctional and dual-functional CD4(+) Th1 cells following Mycobacterium tuberculosis antigen stimulation and elevated frequencies of Th17 subsets at both baseline and following antigen stimulation. This was associated with increased systemic (plasma) levels of both Th1 and Th17 cytokines and decreased baseline frequencies of natural regulatory T cells but not interleukin 10 or transforming growth factor β.

CONCLUSIONS

Therefore, our data reveal that tuberculosis in persons with DM is characterized by elevated frequencies of Th1 and Th17 cells, indicating that DM is associated with an alteration in the immune response to tuberculosis, leading to a biased induction of Th1- and Th17-mediated cellular responses and likely contributing to increased immune pathology in M. tuberculosis infection.

IL-10 dependent suppression of type 1, type 2 and type 17 cytokines in active pulmonary tuberculosis

Background

Although Type 1 cytokine responses are considered protective in pulmonary tuberculosis (PTB), their role as well as those of Type 2, 17 and immunoregulatory cytokines in tuberculous lymphadenitis (TBL) and latent tuberculosis (LTB) have not been well studied.

Aim and Methods

To identify cytokine responses associated with pulmonary tuberculosis (TB), TB lymphadenitits and latent TB, we examined mycobacterial antigen-specific immune responses of PTB, TBL and LTB individuals. More specifically, we examined ESAT-6 and CFP-10 induced Type 1, Type 2 and Type 17 cytokine production and their regulation using multiplex ELISA.

Results

PTB individuals exhibited a significantly lower baseline as well as antigen-specific production of Type 1 (IFNγ, TNFα and IL-2); Type 2 (IL-4) and Type 17 (IL-17A and IL-17F) cytokines in comparison to both TBL and LTB individuals. TBL individuals exhibited significantly lower antigen-specific IFNγ responses alone in comparison to LTB individuals. Although, IL-10 levels were not significantly higher, neutralization of IL-10 during antigen stimulation resulted in significantly enhanced production of IFNγ, IL-4 and IL-17A in PTB individuals, indicating that IL-10 mediates (at least partially) the suppression of cytokine responses in PTB.

Conclusion

Pulmonary TB is characterized by an IL-10 dependent antigen-specific suppression of Type 1, Type 2 and Type 17 cytokines, reflecting an important association of these cytokines in the pathogenesis of active TB.

Expansion of pathogen-specific mono- and multifunctional Th1 and Th17 cells in multi-focal tuberculous lymphadenitis

Background

Th1 and Th17 responses are known to play an important role in immunity to pulmonary tuberculosis (PTB), although little is known about their role in extrapulmonary forms of tuberculosis (TB).

Methods

To identify the role of Th1, Th17, and Th22 cells in multi-focal TB lymphadenitis (TBL), we examined mycobacteria–specific immune responses in the whole blood of individuals with PTB (n = 20) and compared them with those with TBL (n = 25).

Results

Elevated frequencies of CD4⁺ T cells expressing IFN- γ, TNF-α, and IL-2 were present in individuals with TBL compared with those with PTB at baseline and in response to ESAT-6 and CFP-10. Similarly, increased frequencies of CD4⁺ T cells expressing IL-17A, IL-17F, and IFN-γ were also present in individuals with TBL at baseline and following ESAT-6 and CFP-10 stimulation although no significant difference in frequency of Th22 cells was observed. Finally, frequencies of Th1 (but not Th17) cells exhibited a significantly negative correlation with natural regulatory T cell frequencies at baseline.

Conclusions

Multi-focal TB lymphadenitis is therefore characterized by elevated frequencies of Th1 and Th17 cells, indicating that Th1 and Th17 responses in TB disease are probably correlates of disease severity rather than of protective immunity.

Effect of vitamin D3 on phagocytic potential of macrophages with live Mycobacterium tuberculosis and lymphoproliferative response in pulmonary tuberculosis

Immune responses are elicited through antigen presentation and recognition by macrophages and T-lymphocytes, respectively. The immunomodulatory effect of vitamin D(3) on macrophage phagocytic potential with live Mycobacterium tuberculosis, spontaneous and M. tuberculosis culture filtrate antigen induced lymphocyte responses were studied in pulmonary tuberculosis patients (PTBPs) ( n = 31) and normal healthy subjects (NHSs) ( n = 43). Vitamin D(3) at a concentration of 10(-7) M significantly enhanced the macrophage phagocytosis of live M. tuberculosis in normal subjects with low phagocytic potential (less than 10%) ( p = 0.015). No such increase was observed in PTBPs. Vitamin D(3) significantly decreased the spontaneous lymphoproliferative response ( p = 0.022) and increased the apoptosis of peripheral blood mononuclear cells in PTBPs ( p = 0.024). In normals, vitamin D(3) increased the spontaneous lymphoproliferative response. An inverse correlation between macrophage phagocytosis and spontaneous response was observed in NHSs, whereas a direct correlation was seen between vitamin D(3)-treated cells in normal subjects under in vitro condition. Vitamin D(3) decreased the M. tuberculosis culture filtrate antigen induced lymphocyte response significantly in normal subjects ( p = 0.0003), while it had no influence on the lymphocyte response in PTBPs. The present study suggests that exposure to vitamin D(3) increases the phagocytic potential and spontaneous lymphoproliferative response but brings down the antigen-induced response in normals. In tuberculosis, addition of vitamin D(3) has no significant effect on antigen-induced lymphoproliferative response. This may be due to the unresponsive nature of the cells to the action of vitamin D(3) by virtue of the disease, which renders them inactive.