Summary
Type 2 diabetes mellitus (T2DM), is a life-threatening metabolic disease that increases TB incidence and
mortality in South Africa and Worldwide. Dysregulation of glucose homeostasis leads to the development of
hyperglycaemia. Amongst newly diagnosed T2DM patients, hyperglycaemia is associated with TB/T2DM co-
morbidity. Sustained hyperglycaemia results in enhanced sensitivity to Insulin-like Growth Factor-1 (IGF-1) in
vascular endothelial and smooth muscle cells. IGF-1 influence the innate immune system and predominantly
produced by monocytes/macrophages after hepatocytes. We have identified a transcriptomic signature of
increased IGF-1 in IL-4-stimulated macrophages in TB infection. Others have shown that IGF-1 facilitates
alternative activation and ablation of macrophage-IGF-1R hampers the inflammasome activation to reduce
chronic inflammation. Clinical studies revealed that high IGF-1 levels increased the risk of T2DM and increased
serum IGF-1 levels in patients with TB and TB/T2DM. These studies represent significant advances in our
understanding of IGF-1 and suggest altered immunometabolism in host immunity influencing the outcome of TB,
T2DM and TB/T2DM. However, there is still much work that needs to be done as immunometabolic and
immunogenetic regulations in IGF-1 signalling remain unknown in TB and TB/T2DM and a burden in Africa.
A better further understanding of the IGF-1 signalling-mediated dysregulation of immunometabolism and
immunogenetics could inform new biomarkers for diagnostics and improve treatment options for patients with
TB, T2DM and TB/T2DM. I hypothesize that IGF-1 immunometabolism increases the risk of TB, T2DM and
TB/T2DM co-morbidity. To test this, I propose a comprehensive career development plan comprising structured
activities and mentorship opportunities to determine the function of IGF-1 by acquiring advanced skills in (1)
metabolic studies in patient samples; (2) bioinformatics to identify genetic variants in clinical datasets and
functional interrogations in primary human macrophages; (3) assess an IGF-1R inhibitor as adjunctive therapy
in the C3HeB/FeJ mice.
The research proposed is highly relevant to regional/global health priorities, and the career development of the
PI. The project PI, Dr Suraj Parihar, is an immunologist at the University of Cape Town, South Africa, that wants
to conduct research that will improve life quality of patients having grown up in India and seen first-hand the
impact of TB as a significant public health problem.
This K43 award will position him to build an independent program of research and establish a unique scientific
niche in macrophage immunometabolism and immunogenetics that drives innovative diagnostic and therapeutic
approaches for patients in developing world.