Project description:Background: Tuberculosis (TB) remains a major public health problem, especially in developing countries, with 1.5 million deaths annually worldwide. Antibiotics are commonly used in the treatment of bacterial infections. As with most drugs, antibiotic treatment can also alter host metabolism, leading to adverse side-effects. Antibiotics can also interfere with the immune system, indirectly through the disturbance of the body’s microbiota or directly by modulating the functions of immune cells. It is therefore important to understand how antibiotic treatment modulates immune cell functions. Here we aim to evaluate the impact of first-line anti-TB drugs on the response of human macrophages infected with Mycobacterium tuberculosis (MTB). Results: Human macrophages were stimulated with heat-killed Mycobacterium tuberculosis (hk-MTB) and treated with isoniazid (INH), rifampicin (RIF), ethambutol, pyrazinamide (PZA) or amikacin (AMK). After 24h of treatment, RNA was collected and we characterized the genome-wide gene expression profiles of drug-treated cells by RNAseq. 556, 752 and 7 genes were differentially expressed in hk-MTB-stimulated macrophages upon RIF, PZA and EMB treatment respectively, whereas in uninfected macrophages, 448 and 11 genes were differentially expressed upon RIF and PZA treatment respectively. No genes were differentially expressed upon INH and AMK treatment. We classified all modulated genes by performing gene-set enrichment analysis. The gene set regulated by PZA in infected macrophages was significantly enriched for genes involved in Integral to lumenal side of endoplasmic reticulum membrane, Cytokine-mediated signaling pathway or Interferon-gamma-mediated signaling pathway. In hk-MTB-stimulated macrophages treated by RIF, we found an enrichment in Endoplasmic reticulum unfolded protein response, NADP binding or Lipid metabolic process. Conclusions: Our results highlight the importance to understand how antibiotic treatment modulates macrophage (Mφ) functions, and more generally, how it impacts the host immune response.

Project description:Tuberculosis kills nearly 2 million people through out the world, every year. The outcome of M. tuberculosis infection is determined by the host and bacterial factors. A strong host immune response controls the growth of the bacilli effectively. However, in a host with suboptimal immune response, the bacilli grows and mounts disease. Activation of immune response following M. tuberculosis infection affects the expression of many host genes that are involved in the production of immune system molecules such as cytokines, chemokines, surface receptors and transcriptional regulators that manifest in the change of subsequent cellular events, including chemotaxis and proliferation of effector cells. The infecting bacilli counteracts the bactericidal activities of the host immune cells, primarily by modifying their gene expression. However, the specific nature of the host-pathogen interactions and the outcome of Mtb infection are not fully understood. Tumor necrosis factor-alpha (TNF-a), produced by the immune cells, is an important cytokine in protecting the host against Mtb infection. However, excessive TNF-a production leads to severe inflammation and host cell destruction. In fact, pharmacologic inhibition of TNF-a production has been considered as a therapeutic modality in inflammatory diseases. Interestingly, inhibitors of host phosphodiesterase-4 (PDE4) have been shown to reduce TNF-a production and dampen inflammation without complete immune suppression of the host. In this study, we have explored the use of one of the PDE4 inhibitors, CC-3052, as an adjunct immune modulatory drug, in combination with isoniazid (INH) treatment in rabbit pulmonary tuberculosis. We hypothesize that reducing TNF-a levels during Mtb infection would reduce the environmental pressure on the bacteria, rendering them more amenable to killing by INH. Mtb infected rabbits were treated with CC-3052 or INH or both and the lung tissue were harvested after 4 and 8 weeks of treatment. Lung bacterial load, histologic changes and host and bacterial gene expression were determined for each timepoint and compared between various treatment groups. The results of our study provides data to support the idea that combining anti-TB drugs with an adjunctive immune modulator may enhance the efficacy of current TB therapy regimens and shorten the duration of treatment if applied appropriately to humans. The microarray experiments involves 2 comparison groups. 1) Changes in rabbit gene expression between Mtb infected and uninfected animals; 2). Changes in rabbit gene expression between CC-3052 treated and untreated animals during Mtb infection at 4,8 and 12 weeks post infection. New Zealand White rabbits were infected with Mtb HN878 at 3.2log10 (on day 0). At 4 weeks post infection, one group of infected rabbits were treated with a phosphodiesterase-4 (PDE4) inhibitor, CC-3052, and the treatment was continued up to 12 weeks post infection. The compound was used at 25mg/kg body weight, dissolved in distilled water and administered through gavage five days a weeks. Lung tissue from Uninfected, Mtb-infected and Untreated or CC-3052 treated rabbits were isolated at Day0, 4,8 and 12 weeks post infection and used for total RNA extraction. Only the 8 and 12 week timepoints correspond to the associated publication.

Project description:Tuberculosis kills nearly 2 million people through out the world, every year. The outcome of M. tuberculosis infection is determined by the host and bacterial factors. A strong host immune response controls the growth of the bacilli effectively. However, in a host with suboptimal immune response, the bacilli grows and mounts disease. Activation of immune response following M. tuberculosis infection affects the expression of many host genes that are involved in the production of immune system molecules such as cytokines, chemokines, surface receptors and transcriptional regulators that manifest in the change of subsequent cellular events, including chemotaxis and proliferation of effector cells. The infecting bacilli counteracts the bactericidal activities of the host immune cells, primarily by modifying their gene expression. However, the specific nature of the host-pathogen interactions and the outcome of Mtb infection are not fully understood. Tumor necrosis factor-alpha (TNF-a), produced by the immune cells, is an important cytokine in protecting the host against Mtb infection. However, excessive TNF-a production leads to severe inflammation and host cell destruction. In fact, pharmacologic inhibition of TNF-a production has been considered as a therapeutic modality in inflammatory diseases. Interestingly, inhibitors of host phosphodiesterase-4 (PDE4) have been shown to reduce TNF-a production and dampen inflammation without complete immune suppression of the host. In this study, we have explored the use of one of the PDE4 inhibitors, CC-3052, as an adjunct immune modulatory drug, in combination with isoniazid (INH) treatment in rabbit pulmonary tuberculosis. We hypothesize that reducing TNF-a levels during Mtb infection would reduce the environmental pressure on the bacteria, rendering them more amenable to killing by INH. Mtb infected rabbits were treated with CC-3052 or INH or both and the lung tissue were harvested after 4 and 8 weeks of treatment. Lung bacterial load, histologic changes and host and bacterial gene expression were determined for each timepoint and compared between various treatment groups. The results of our study provides data to support the idea that combining anti-TB drugs with an adjunctive immune modulator may enhance the efficacy of current TB therapy regimens and shorten the duration of treatment if applied appropriately to humans. The microarray experiments involves 2 comparison groups. 1) Changes in rabbit gene expression between Mtb infected and uninfected animals; 2). Changes in rabbit gene expression between CC-3052 treated and untreated animals during Mtb infection at 4,8 and 12 weeks post infection.

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Deferoxamine as adjunct therapeutics for tuberculosis.

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