Microarray analysis adherent peripheral blood mononuclear cells stimulated with IL-10, IL-15, and IL-4

Tuberculosis remains a major cause of death from an infectious disease worldwide, yet only 10% of people infected with Mycobacterium tuberculosis develop disease. Defining both necessary and sufficient immunologic determinants of protection remains a great scientific challenge. Analysis of peripheral blood gene expression profiles of active tuberculosis patients has identified correlates of risk for disease or pathogenesis. We sought to identify human potential candidate markers of host defense by studying gene expression profiles of macrophages, cells which, upon infection by M. tuberculosis, can mount an antimicrobial response. Weighted gene co-expression network analysis revealed an association between the cytokine, IL-32, and the vitamin D antimicrobial pathway in a network of IFN- and IL-15 induced defense response genes. IL-32 was sufficient for induction of the vitamin D-dependent antimicrobial peptides, cathelicidin and DEFB4, and generation of antimicrobial activity in vitro, dependent on the presence of adequate 25-hydroxyvitamin D. The IL-15 induced defense response macrophage gene network was integrated with ranked pairwise comparisons of gene expression from five different clinical data sets of latent vs. active tuberculosis or healthy controls, and a co-expression network derived from gene expression in patients with tuberculosis undergoing chemotherapy. Together, these analyses identified eight common genes, including IL-32, as molecular markers of latent tuberculosis and the IL-15 induced gene network. Inferring that maintaining M. tuberculosis in a latent state and preventing transition to active disease represents host resistance, we believe these results identify IL-32 as one functional marker and potential correlate of protection against active tuberculosis.

32

Montoya D, Inkeles MS, Liu PT, Realegeno S, Teles RM, Vaidya P, Munoz MA, Schenk M, Swindell WR, Chun R, Zavala K, Hewison M, Adams JS, Horvath S, Pellegrini M, Bloom BR, Modlin RL