Comorbidities and Coinfections in Latent TB

Approximately 2 billion people worldwide are infected with Mycobacterium tuberculosis (TB), with 90% of individuals having latent infection (LTBI). The control of TB requires clearly delineated helper T cell (Th) 1 responses and, to a lesser extent, Th17 responses, which both play important roles in the induction and maintenance of protective immune responses in mouse models of TB infection and in the prevention of active disease, as seen in LTBI. During latency, M. tuberculosis is contained in localized granulomas. Mycobacteria specific T cells mediate delayed type hypersensitivity reactions to purified protein derivative (PPD), and this reaction is generally considered to indicate an LTBI status in the absence of demonstrable active infection. Among the various risk factors that are known to play a role in promoting active TB, HIV is the most well studied and described. However, in low-HIV-endemic countries like India, other risk factors might play a more prominent role in active TB pathogenesis. These include malnutrition, diabetes mellitus (DM), and helminth infections. LTBI individuals with these comorbidities or coinfections could be at a higher risk for developing active TB than their "healthy" LTBI counterparts without these comorbidities. Thus, it is imperative to study the pathogenesis of TB infection and disease in these "at risk" populations. In this study, we will estimate the prevalence of severe to moderate malnutrition, uncontrolled DM, and helminth infections in LTBI-positive individuals. We will collect samples from a cohort of individuals with LTBI, those with LTBI and coexistent malnutrition, DM, or helminth coinfection, and those without any of these conditions. Individual participation may last up to 6 months. The main objective of the study is to estimate the prevalence of malnutrition, DM, and helminth infections in LTBI individuals. Simultaneously, we will perform transcriptomic, proteomic, and metabolomic assays, including profiles in serum and urine, to determine the biosignature portfolio of these individuals. In addition, immunological assays examining cytokine/chemokine signatures as well as other immune parameters related to innate and adaptive responses will be performed to enhance the understanding of the immunological cross talk between LTBI and malnutrition, DM, and helminth infections.