TLR4-mediated IL-12 production enhances IFN-γ and IL-1β production, which inhibits TGF-β production and promotes antibody-induced joint inflammation
Copyright policy )TLR4-mediated IL-12 production enhances IFN-γ and IL-1β production, which inhibits TGF-β production and promotes antibody-induced joint inflammation
Abstract Introduction Toll-like receptor (TLR)4 promotes joint inflammation in mice. Despite that several studies report a functional link between TLR4 and interleukin-(IL-)1β in arthritis, TLR4-mediated regulation of the complicated cytokine network in arthritis is poorly understood. To address this, we investigated the mechanisms by which TLR4 regulates the cytokine network in antibody-induced arthritis. Methods To induce arthritis, we injected mice with K/BxN serum. TLR4-mediated pathogenesis in antibody-induced arthritis was explored by measuring joint inflammation, cytokine levels and histological alteration. Results Compared to wild type (WT) mice, TLR4-/- mice showed attenuated arthritis and low interferon (IFN)-γ, IL-12p35 and IL-1β transcript levels in the joints, but high transforming growth factor (TGF)-β expression. Injection of lipopolysaccharide (LPS) enhanced arthritis and exaggerated joint cytokine alterations in WT, but not TLR4-/- or IL-12p35-/- mice. Moreover, STAT4 phosphorylation in joint cells and intracellular IL-12p35 expression in macrophages, mast cells and Gr-1+ cells were detected in WT mice with arthritis and enhanced by LPS injection. Therefore, IL-12p35 appears to act downstream of TLR4 in antibody-induced arthritis. TLR4-mediated IL-12 production enhanced IFN-γ and IL-1β production via T-bet and pro-IL-1β production. Recombinant IL-12, IFN-γ and IL-1β administration restored arthritis, but reduced joint TGF-β levels in TLR4-/- mice. Moreover, a TGF-β blockade restored arthritis in TLR4-/- mice. Adoptive transfer of TLR4-deficient macrophages and mast cells minimally altered joint inflammation and cytokine levels in macrophage- and mast cell-depleted WT mice, respectively, whereas transfer of WT macrophages or mast cells restored joint inflammation and cytokine expression. Gr-1+ cell-depleted splenocytes partially restored arthritis in TLR4-/- mice. Conclusion TLR4-mediated IL-12 production by joint macrophages, mast cells and Gr-1+ cells enhances IFN-γ and IL-1β production, which suppresses TGF-β production, thereby promoting antibody-induced arthritis.
- Seoul National University Korea (Republic of)
- Seoul National University College of Medicine Korea (Republic of)
- New Generation University College Ethiopia
Lipopolysaccharides, Male, Immunology, Interleukin-1beta, Mice, Transgenic, Interferon-gamma, Mice, Rheumatology, Mice, Inbred NOD, Transforming Growth Factor beta, Immunology and Allergy, Animals, Mast Cells, Mice, Knockout, Arthritis, Macrophages, Interleukin-12, Mice, Inbred C57BL, Toll-Like Receptor 4, Disease Models, Animal, Female, Research Article, Signal Transduction
Lipopolysaccharides, Male, Immunology, Interleukin-1beta, Mice, Transgenic, Interferon-gamma, Mice, Rheumatology, Mice, Inbred NOD, Transforming Growth Factor beta, Immunology and Allergy, Animals, Mast Cells, Mice, Knockout, Arthritis, Macrophages, Interleukin-12, Mice, Inbred C57BL, Toll-Like Receptor 4, Disease Models, Animal, Female, Research Article, Signal Transduction
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