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Dissection of a type I interferon pathway in controlling bacterial intracellular infection in mice.

ABSTRACT: Defence mechanisms against intracellular bacterial pathogens are incompletely understood. Our study characterizes a type I IFN-dependent cell-autonomous defence pathway directed against Legionella pneumophila, an intracellular model organism and frequent cause of pneumonia. We show that macrophages infected with L. pneumophila produced IFN? in a STING- and IRF3- dependent manner. Paracrine type I IFNs stimulated upregulation of IFN-stimulated genes and a cell-autonomous defence pathway acting on replicating and non-replicating Legionella within their specialized vacuole. Our infection experiments in mice lacking receptors for type I and/or II IFNs show that type I IFNs contribute to expression of IFN-stimulated genes and to bacterial clearance as well as resistance in L. pneumophila pneumonia in addition to type II IFN. Overall, our study shows that paracrine type I IFNs mediate defence against L. pneumophila, and demonstrates a protective role of type I IFNs in in vivo infections with intracellular bacteria.

SUBMITTER: Lippmann J

PROVIDER: S-EPMC3196383 | biostudies-literature | 2011 Nov

REPOSITORIES: biostudies-literature

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Dissection of a type I interferon pathway in controlling bacterial intracellular infection in mice.

Lippmann Juliane J Müller Holger C HC Naujoks Jan J Tabeling Christoph C Shin Sunny S Witzenrath Martin M Hellwig Katharina K Kirschning Carsten J CJ Taylor Gregory A GA Barchet Winfried W Bauer Stefan S Suttorp Norbert N Roy Craig R CR Opitz Bastian B

Cellular microbiology 20110824 11

Defence mechanisms against intracellular bacterial pathogens are incompletely understood. Our study characterizes a type I IFN-dependent cell-autonomous defence pathway directed against Legionella pneumophila, an intracellular model organism and frequent cause of pneumonia. We show that macrophages infected with L. pneumophila produced IFNβ in a STING- and IRF3- dependent manner. Paracrine type I IFNs stimulated upregulation of IFN-stimulated genes and a cell-autonomous defence pathway acting on ...[more]

PMID: 21790939

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Project description:Analysis of Mtb infected murine macrophages derived from C57Bl/6 WT, TPL2KO, IFNARKO & TPL2IFNAR DKO mice [Set 2] Tuberculosis, caused by Mycobacterium tuberculosis (Mtb), remains a leading cause of mortality and morbidity worldwide, causing approximately 1.4 million deaths per year. Key immune components for host protection during tuberculosis include the cytokines IL‐12, IL‐1 and TNF‐α, as well as IFN‐γ and CD4+ Th1 cells. However, immune factors determining whether individuals control infection or progress to active tuberculosis are incompletely understood. Excess amounts of type I interferon have been linked to exacerbated disease during tuberculosis in mouse models and to active disease in patients, suggesting tight regulation of this family of cytokines is critical to host resistance. In addition, the immunosuppressive cytokine IL‐10 is known to inhibit the immune response to Mtb in murine models through the negative regulation of key pro-inflammatory cytokines and the subsequent Th1 response. We show here, using a combination of transcriptomic analysis, genetics and pharmacological inhibitors that the TPL-2-ERK1/2 signaling pathway is important in mediating host resistance to tuberculosis through negative regulation of type I interferon production. The TPL-2-ERK1/2 signalling pathway regulated production by macrophages of several cytokines important in the immune response to Mtb as well as regulating induction of a large number of additional genes, many in a type I IFN dependent manner. In the absence of TPL-2 in vivo, excess type I interferon promoted IL-10 production and exacerbated disease. These findings describe an important regulatory mechanism for controlling tuberculosis and reveal mechanisms by which type I interferon may promote susceptibility to this important disease. Macrophages were derived from C57Bl/6 WT, TPL2KO, IFNARKO & TPL2IFNARKO bone marrow, plated and infected with Mtb H37Rv (or not) in triplicate wells. The indicated samples were also treated with 5ng/ml IFNgamma at the time of infection. Samples were then harvested for RNA at time 0, 1hr and 6hr. Please note that *Sample and *Medium control samples (e.g. '0hr TPL2-/-IFNabR-/- Sample' vs '0hr TPL2-/-IFNabR-/- Medium Control Sample') are the same sample group (i.e. uninfected) with one group being a repeat re-run of the other (indicated in the correponding SAMPLE description field).

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Dataset Information

Dissection of a type I interferon pathway in controlling bacterial intracellular infection in mice.

Publications

Dissection of a type I interferon pathway in controlling bacterial intracellular infection in mice.

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