Project description: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-γ 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. Adherent peripheral blood monuclear cells were derived by Ficoll-Hypaque from the whole blood of four healthy donors. Cells adhered to tissue culture-treated plates for 2 h in 1% Fetal Bovine Serum (FBS) in RPMI. Cells were washed then stimulated with IL-10 (10ng/ml), IL-15 (10ng/ml) (R&D Systems), or IL-4 (1U/ml) in RPMI 1640 supplemented with 10% FBS at 37°C, 5% CO2. Cells were harvested at 6 h and 24 h after stimulation and monocytes purified by CD14 microbeads (Miltenyi Biotec) for a confirmed monocyte purity of at least 90%. RNA from purified monocytes extracted by Trizol and purified by Qiagen RNeasy Kit. RNA probe and microarray performed by UCLA Clinical Microarray Core using Ambion labeling kit and Affymetrix Human U133 Plus 2.0 array.

Project description:Glucocorticoids are extensively used to treat inflammatory diseases, however their chronic intake increases the risk of mycobacterial infections. Meanwhile, the effects of glucocorticoids on innate host responses are incompletely understood. Here, we studied the direct effects of glucocorticoids on antimycobacterial host defense in primary human macrophages. We found that glucocorticoids triggered the expression of cathelicidin, an antimicrobial critical for antimycobacterial response, independent of the intracellular vitamin D metabolism. Despite upregulating cathelicidin, glucocorticoids failed to promote macrophage antimycobacterial activity. Gene expression profiles of human macrophages treated with glucocorticoids and/or IFN-gamma, which promotes induction of cathelicidin, as well as antimycobacterial activity, were investigated. Using weighted gene coexpression network analysis (WGCNA), we identified a module of highly connected genes that was strongly inversely correlated with glucocorticoid treatment and associated with IFN-gamma stimulation. This module was linked to the biological functions “autophagy”, “phagosome maturation” and “lytic vacuole/lysosome”, and contained the vacuolar H+-ATPase (v-ATPase) subunit a3, alias TCIRG1, a known antimycobacterial host defense gene, as a top hub gene. We next found that glucocorticoids, in contrast to IFN-gamma, failed to trigger expression and phagolysosome recruitment of TCIRG1, as well as to promote lysosome acidification. Finally, we demonstrated that the tyrosine kinase inhibitor imatinib induces lysosome acidification and antimicrobial activity in glucocorticoid-treated macrophages without reversing the anti-inflammatory effects of glucocorticoids. Taken together, we provide evidence that the induction of cathelicidin by glucocorticoids is not sufficient for macrophage antimicrobial activity, and identify the v-ATPase as a potential target for host-directed therapy in the context of glucocorticoid therapy.

Project description:Glucocorticoids are extensively used to treat inflammatory diseases, however their chronic intake increases the risk of mycobacterial infections. Meanwhile, the effects of glucocorticoids on innate host responses are incompletely understood. Here, we studied the direct effects of glucocorticoids on antimycobacterial host defense in primary human macrophages. We found that glucocorticoids triggered the expression of cathelicidin, an antimicrobial critical for antimycobacterial response, independent of the intracellular vitamin D metabolism. Despite upregulating cathelicidin, glucocorticoids failed to promote macrophage antimycobacterial activity. Gene expression profiles of human macrophages treated with glucocorticoids and/or IFN-gamma, which promotes induction of cathelicidin, as well as antimycobacterial activity, were investigated. Using weighted gene coexpression network analysis (WGCNA), we identified a module of highly connected genes that was strongly inversely correlated with glucocorticoid treatment and associated with IFN-gamma stimulation. This module was linked to the biological functions âautophagyâ, âphagosome maturationâ and âlytic vacuole/lysosomeâ, and contained the vacuolar H+-ATPase (v-ATPase) subunit a3, alias TCIRG1, a known antimycobacterial host defense gene, as a top hub gene. We next found that glucocorticoids, in contrast to IFN-gamma, failed to trigger expression and phagolysosome recruitment of TCIRG1, as well as to promote lysosome acidification. Finally, we demonstrated that the tyrosine kinase inhibitor imatinib induces lysosome acidification and antimicrobial activity in glucocorticoid-treated macrophages without reversing the anti-inflammatory effects of glucocorticoids. Taken together, we provide evidence that the induction of cathelicidin by glucocorticoids is not sufficient for macrophage antimicrobial activity, and identify the v-ATPase as a potential target for host-directed therapy in the context of glucocorticoid therapy. Peripheral blood mononuclear cells (PBMCs) of three healthy human donors were isolated by Ficoll-Paque (GE Healthcare). Monocytes were isolated via CD14+ MACS cell separation (Miltenyi Biotec) according to the manufacturers instructions. Monocyte-derived macrophages (MDMs) were prepared by culturing peripheral blood monocytes in RPMI media containing 10% FCS for four to seven days in the presence of M-CSF (50 ng/ml). Afterwards cells were cultured in fresh media with 10% vitamin D-sufficient human AB serum. Cells were stimulated with media, dexamethasone, interferon-gamma and dexamethasone/interferon-gamma for 20h. Total RNA of was isolated with TRIZOL (Life Technologies) and RNA quality was confirmed using micro capillary electrophoresis (2100 Bioanalyzer, Agilent). 100ng RNA was labeled and hybridized to Sureprint G3 human GE 8x60K whole genome mRNA microarray according to the manufacturerâs specifications. The arrays were scanned (Agilent G2595C scanner), data extracted and processed using the Genespring XII software (Agilent).

Project description:The immune mechanisms that control resistance vs. susceptibility to mycobacterial infection in humans were investigated by studying leprosy skin lesions, the site where the battle between the host and the pathogen is joined. Using an integrative genomics approach, we found an inverse correlation between of IFN-beta and IFN-gamma gene expression programs at the site of disease. The Type II IFN, IFN-gamma and its downstream vitamin D-dependent antimicrobial genes were preferentially expressed in the lesions from patients with the self-healing tuberculoid form of the disease and mediated antimicrobial activity against the pathogen, Mycobacterium leprae in vitro. In contrast, the Type I IFN, IFN-beta and its downstream genes, including IL-27 and IL-10, were induced in monocytes by M. leprae in vitro, and were preferentially expressed in the lesions of disseminated and progressive lepromatous form. The IFN-gamma induced macrophage antimicrobial response was inhibited by IFN-beta/IL-10, by a mechanism involving blocking the generation of bioactive 1,25-dihyroxy vitamin D as well as inhibiting induction of antimicrobial peptides cathelicidin and DEFB4. The ability of IFN-M-oM-^AM-" to inhibit the IFN-gamma induced vitamin D pathway including antimicrobial activity was reversed by neutralization of IL-10, suggesting a possible target for therapeutic intervention. Finally, a common IFN-beta and IL-10 gene signature was identified in both the skin lesions of leprosy patients and in the peripheral blood of active tuberculosis patients. Together these data suggest that the ability of IFN-beta to downregulate protective IFN-gamma responses provides one general mechanism by which some bacterial pathogens of humans evade protective host responses and contribute to pathogenesis. Peripheral blood monuclear cells derived through Ficoll-Hypaque from the blood of healthy human donors (n=4). Cells adhered to tissue culture treated 6-well plates for 2 hours in 1% Fetal Bovine Serum (FBS) RPMI and then stimulated by IL-10 (R&D Systems) 10ng/ml or media alone in 10% FBS RPMI for 24 hours at 37M-BM-0C, 5% CO2. After stimulation, cells harvested and monocytes isolated through CD14 positive selection (Miltenyi Biotec). RNA from purified monocytes extracted by Trizol and purified by Qiagen RNeasy Kit. RNA probe and microarray performed by UCLA Clinical Microarray Core using Ambion labeling kit and Affymetrix Human U133 Plus 2.0 array.

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Toll-like receptor triggering of a vitamin D-mediated human antimicrobial response

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