The Influence of Malnutrition, Diabetes Mellitus, and Helminth Infections on Biosignatures in Latent Tuberculosis in a South Indian Population

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.

• PARTICIPANT INCLUSION CRITERIA (Screening Phase)

Individuals who meet the following criteria are eligible to participate in the screening phase:

• Aged 14 to 65 years.
• Willingness to provide blood, urine, and stool samples for examination.
• Willingness to have samples and data stored.
• Able to provide informed consent.

PARTICIPANT EXCLUSION CRITERIA (Screening Phase)

• Pulmonary symptoms suggestive of TB (cough >2 weeks in duration and/or intermittent fever >1 week in duration and/or hemoptysis).
• Two IGRA tests with indeterminate results (mitogen values <10 IU).

PARTICIPANT INCLUSION CRITERIA (Study Phase)

Individuals are eligible for the study phase if they meet the requirements for one of the study groups, as follows:

• LTBI+ and severe to moderate malnutrition (BMI <17 kg/m2);
• LTBI+ and uncontrolled DM (HbA1c >8%);
• LTBI+ and helminth infection (positive stool qPCR and/or serology);
• LTBI+ with more than one of the conditions defined in groups 1 3;
• healthy LTBI+ controls who are negative for all of the above conditions; and
• healthy LTBI-negative controls with none of the above conditions.

PARTICIPANT EXCLUSION CRITERIA (Study Phase)

• Pulmonary symptoms suggestive of TB (cough >2 weeks in duration and/or intermittent fever >1 week in duration and/or hemoptysis).
• Pregnant or lactating women.
• Previous treatment for LTBI.
• Anemia with hemoglobin <8 g/dl (evaluated at the screening phase visit).
• For LTBI+ participants, clinically indicated chest X-ray positive for pulmonary TB.
• For malnourished participants, clinically indicated abdominal ultrasound positive for abdominal TB.
• Known documented cases of cancer, acquired immune deficiency syndrome, or other immunosuppressive illness.
• History of any other illness or condition which, in the investigator s judgment, may substantially increase the risk associated with the participant s participation in the protocol, or compromise the scientific objectives.