Project description:Objectives: Therapies being safe, effective and not vulnerable to develop resistance are highly desirable to counteract bacterial infections. Host-directed therapeutics is an alternative to conventional antibiotics based on perturbing host pathways subverted by pathogens during their life cycle by the use of host-directed drugs to counteract microbial infections. This study sought to identify cellular genes and pathways differentially expressed during airways epithelial infection by nontypable Haemophilus influenzae (NTHi). NTHi is an opportunistic pathogen that is an important cause of exacerbation of chronic obstructive pulmonary disease (COPD). Based on the proposed relationship between NTHi intracellular location and persistence, the antimicrobial potential of a panel of drugs perturbing host pathways used by NTHi to enter epithelial cells was investigated. Methods: We screened for host genes differentially expressed upon infection by the clinical isolate NTHi375 by analyzing A549 cell whole genome expression profiling, and identified a panel of host target candidates which were pharmacologically modulated. Interfering drugs were tested for their bactericidal effect, cytotoxicity, effect on the interplay NTHi-epithelial cell, and effect on NTHi respiratory infection in vivo, by assessing lung bacterial loads in a murine intranasal infection model. Results: The sirtuin-1 activator resveratrol showed a bactericidal effect against NTHi; the PDE4 inhibitor rolipram showed therapeutic efficacy by lowering NTHi375 counts both intracellularly and in the lungs of infected mice. Conclusions: PDE4 inhibition is currently prescribed in COPD; resveratrol is a geroprotector attractive for COPD treatment by preventing lung aging. This work provides evidence for the antimicrobial potential of rolipram and resveratrol against NTHi respiratory infection. Haemophilus influenzae clinical strain NTHi375 induced gene expression in A549 human type II pneumocyte cell line was measured at 2 h post-infection. Non infected cells were used as a control. Four independent experiments were performed for each condition.

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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Genome expression profiling identifies host-directed antimicrobial drugs against respiratory infection by nontypable Haemophilus influenzae

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