Interleukin-6 blood levels in sensitive and multiresistant tuberculosis

Association of Selected Cardiovascular Markers With Tuberculosis: Community-Based Exploratory Cross-Sectional Analytical Study in Puducherry

Introduction India accounts for one-fourth of the global tuberculosis (TB) burden and also faces a rising burden of non-communicable diseases. Only a few have studied the association between the infective pathogenesis of TB and cardiovascular diseases (CVD). Methods A cross-sectional exploratory analytical design was used to compare CVD risk factors and immunological and radiological parameters. This was a pilot study conducted in two primary health centers in urban Puducherry between February 2020 and March 2021. Household contacts (HHC) were either spouses or siblings of the newly diagnosed pulmonary tuberculosis (PTB) patients selected for comparison as their exposure to infection would be similar to those who were diseased yet did not develop illness. Assuming a difference of 5% in CVD risk between the general population and TB patients, with a 95% confidence interval, the sample size calculated was 153 in each group by nMaster v2.0. Considering the feasibility and resource constrain, we recruited 50 newly diagnosed PTB patients, their age- and gender-matched 50 HHC and 50 PTB patients who completed treatment a year before. CVD risk factors were compared using chi-square or Fisher exact test. Interleukins-6 (IL-6), interferon-gamma (INF-γ), highly specific - C reactive protein (hs-CRP), and carotid intima-media thickness (CIMT) were compared using ANOVA or Kruskal-Wallis test. Results Most participants from each group belonged to lower socio-economic strata and were males (40/50). Alcohol intake was higher among newly diagnosed and treatment-completed PTB patients (82.5% vs 72.5%). Excess salt intake (58%) was present more in newly diagnosed PTB patients. General and abdominal obesity were seen more among HHC (64% and 84%) and treatment-completed PTB patients (50% and 74%). IL-6 was higher in newly diagnosed PTB patients, whereas INF-γ and hs-CRP were higher in treatment-completed PTB patients. The largest proportion of those having high CIMT values was also in the treatment-completed PTB patients. Conclusion Levels of immune markers hint at the role of inflammation due to TB disease being related to the high CIMT values among the newly diagnosed and treatment-completed PTB patients. CVD risk was higher among TB patients even if they had completed treatment and were declared cured.

A rapid triage test for active pulmonary tuberculosis in adult patients with persistent cough

Improved tuberculosis (TB) prevention and control depend critically on the development of a simple, readily accessible rapid triage test to stratify TB risk. We hypothesized that a blood protein-based host response signature for active TB (ATB) could distinguish it from other TB-like disease (OTD) in adult patients with persistent cough, thereby providing a foundation for a point-of-care (POC) triage test for ATB. Three adult cohorts consisting of ATB suspects were recruited. A bead-based immunoassay and machine learning algorithms identified a panel of four host blood proteins, interleukin-6 (IL-6), IL-8, IL-18, and vascular endothelial growth factor (VEGF), that distinguished ATB from OTD. An ultrasensitive POC-amenable single-molecule array (Simoa) panel was configured, and the ATB diagnostic algorithm underwent blind validation in an independent, multinational cohort in which ATB was distinguished from OTD with receiver operator characteristic-area under the curve (ROC-AUC) of 0.80 [95% confidence interval (CI), 0.75 to 0.85], 80% sensitivity (95% CI, 73 to 85%), and 65% specificity (95% CI, 57 to 71%). When host antibodies against TB antigen Ag85B were added to the panel, performance improved to 86% sensitivity and 69% specificity. A blood-based host response panel consisting of four proteins and antibodies to one TB antigen can help to differentiate ATB from other causes of persistent cough in patients with and without HIV infection from Africa, Asia, and South America. Performance characteristics approach World Health Organization (WHO) target product profile accuracy requirements and may provide the foundation for an urgently needed blood-based POC TB triage test.

Human Properdin Modulates Macrophage: Mycobacterium bovis BCG Interaction via Thrombospondin Repeats 4 and 5

Mycobacterium tuberculosis can proficiently enter macrophages and diminish complement activation on its cell surface. Within macrophages, the mycobacterium can suppress macrophage apoptosis and survive within the intracellular environment. Previously, we have shown that complement regulatory proteins such as factor H may interfere with pathogen–macrophage interactions during tuberculosis infection. In this study, we show that Mycobacterium bovis BCG binds properdin, an upregulator of the complement alternative pathway. TSR4+5, a recombinant form of thrombospondin repeats 4 and 5 of human properdin expressed in tandem, which is an inhibitor of the alternative pathway, was also able to bind to M. bovis BCG. Properdin and TSR4+5 were found to inhibit uptake of M. bovis BCG by THP-1 macrophage cells in a dose-dependent manner. Quantitative real-time PCR revealed elevated pro-inflammatory responses (TNF-α, IL-1β, and IL-6) in the presence of properdin or TSR4+5, which gradually decreased over 6 h. Correspondingly, anti-inflammatory responses (IL-10 and TGF-β) showed suppressed levels of expression in the presence of properdin, which gradually increased over 6 h. Multiplex cytokine array analysis also revealed that properdin and TSR4+5 significantly enhanced the pro-inflammatory response (TNF-α, IL-1β, and IL-1α) at 24 h, which declined at 48 h, whereas the anti-inflammatory response (IL-10) was suppressed. Our results suggest that properdin may interfere with mycobacterial entry into macrophages via TSR4 and TSR5, particularly during the initial stages of infection, thus affecting the extracellular survival of the pathogen. This study offers novel insights into the non-complement related functions of properdin during host–pathogen interactions in tuberculosis.

The influence of cattle breed on susceptibility to bovine tuberculosis in Ethiopia

Bovine tuberculosis in domestic livestock such as cattle is an economically important disease with zoonotic potential, particularly in countries with emerging economies. We discuss the findings of recent epidemiological and immunological studies conducted in Ethiopia on host susceptibility differences between native zebu and the exotic Holstein-Friesian cattle that are increasingly part of the Ethiopian National herd, due to the drive to increase milk yields. These findings support the hypothesis that native Zebu cattle are more resistant to bovine tuberculosis. We also summarise the results of experimental infections that support the epidemiological data, and of laboratory experiments that suggest a role for the innate immune response, and in particular interleukin-6, in the outcome of bovine tuberculosis infection.