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An antiinflammatory role for IKKbeta through the inhibition of "classical" macrophage activation.

ABSTRACT: The nuclear factor kappaB (NF-kappaB) pathway plays a central role in inflammation and immunity. In response to proinflammatory cytokines and pathogen-associated molecular patterns, NF-kappaB activation is controlled by IkappaB kinase (IKK)beta. Using Cre/lox-mediated gene targeting of IKKbeta, we have uncovered a tissue-specific role for IKKbeta during infection with group B streptococcus. Although deletion of IKKbeta in airway epithelial cells had the predicted effect of inhibiting inflammation and reducing innate immunity, deletion of IKKbeta in the myeloid lineage unexpectedly conferred resistance to infection that was associated with increased expression of interleukin (IL)-12, inducible nitric oxide synthase (NOS2), and major histocompatibility complex (MHC) class II by macrophages. We also describe a previously unknown role for IKKbeta in the inhibition of signal transducer and activator of transcription (Stat)1 signaling in macrophages, which is critical for IL-12, NOS2, and MHC class II expression. These studies suggest that IKKbeta inhibits the "classically" activated or M1 macrophage phenotype during infection through negative cross talk with the Stat1 pathway. This may represent a mechanism to prevent the over-exuberant activation of macrophages during infection and contribute to the resolution of inflammation. This establishes a new role for IKKbeta in the regulation of macrophage activation with important implications in chronic inflammatory disease, infection, and cancer.

SUBMITTER: Fong CH

PROVIDER: S-EPMC2413025 | biostudies-literature | 2008 Jun

REPOSITORIES: biostudies-literature

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An antiinflammatory role for IKKbeta through the inhibition of "classical" macrophage activation.

Fong Carol Ho Yan CH Bebien Magali M Didierlaurent Arnaud A Nebauer Ruth R Hussell Tracy T Broide David D Karin Michael M Lawrence Toby T

The Journal of experimental medicine 20080519 6

The nuclear factor kappaB (NF-kappaB) pathway plays a central role in inflammation and immunity. In response to proinflammatory cytokines and pathogen-associated molecular patterns, NF-kappaB activation is controlled by IkappaB kinase (IKK)beta. Using Cre/lox-mediated gene targeting of IKKbeta, we have uncovered a tissue-specific role for IKKbeta during infection with group B streptococcus. Although deletion of IKKbeta in airway epithelial cells had the predicted effect of inhibiting inflammatio ...[more]

PMID: 18490491

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Project description:Experimental pulmonary Cryptococcus neoformans infection in BALB/c mice is associated with polarized Th2-type cytokine production, alternative macrophage activation, and severe bronchopneumonia. In contrast, pulmonary infection with a C. neoformans strain that secretes IFN-γ, H99γ, elicits Th1-type cytokine production and classical macrophage activation. Additionally, mice infected with H99γ resolve the acute infection and are subsequently protected against challenge with wild-type C. neoformans. The present study characterizes macrophage activation during the protective response to wild-type C. neoformans in mice previously immunized with H99γ. We observed increased pulmonary Th1-type cytokine production in lung homogenates and classical macrophage activation as evidenced by enhanced expression of inducible NO synthase in the lungs of H99γ-immunized mice compared with mice given a nonprotective immunization with heat-killed C. neoformans (HKCn). Furthermore, macrophages isolated from H99γ-immunized mice on day 7 postchallenge and cultured in vitro were fungistatic against C. neoformans, whereas cryptococcal growth was uncontrolled within macrophages from HKCn-immunized mice. Th2-type cytokine production and induction of alternatively activated macrophages were also observed in lungs of HKCn-immunized mice during rechallenge. Gene expression arrays showed that classical macrophage activation during challenge infection in H99γ-immunized mice was associated with induction of the transcription factor STAT1 and its downstream targets IFN regulatory factor-1, suppressor of cytokine signaling-1, CXCL9, and CXCL10. These studies demonstrate that protective responses to C. neoformans challenge in immunized mice include classical macrophage activation and enhanced macrophage fungistasis of C. neoformans yeasts. Finally, the classical activation phenotype of protective anticryptococcal macrophages is likely mediated via STAT1 signal transduction pathways.

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An antiinflammatory role for IKKbeta through the inhibition of "classical" macrophage activation.

Publications

An antiinflammatory role for IKKbeta through the inhibition of "classical" macrophage activation.

Similar Datasets

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