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TNF-induced structural joint damage is mediated by IL-1.

ABSTRACT: Blocking TNF effectively inhibits inflammation and structural damage in human rheumatoid arthritis (RA). However, so far it is unclear whether the effect of TNF is a direct one or indirect on up-regulation of other mediators. IL-1 may be one of these candidates because it has a central role in animal models of arthritis, and inhibition of IL-1 is used as a therapy of human RA. We removed the effects of IL-1 from a TNF-mediated inflammatory joint disease by crossing IL-1alpha and beta-deficient mice (IL-1-/-) with arthritic human TNF-transgenic (hTNFtg) mice. Development of synovial inflammation was almost unaffected on IL-1 deficiency, but bone erosion and osteoclast formation were significantly reduced in IL-1-/-hTNFtg mice, compared with hTNFtg mice based on an intrinsic differentiation defect of IL-1-deficient monocytes. Most dramatically, however, cartilage damage was absent in IL-1-/-hTNFtg mice. Chimera studies revealed that protection of cartilage is based on the loss of IL-1 on hematopoietic, but not mesenchymal, cells, leading to decreased expression of ADAMTS-5 and MMP-3. These data show that TNF-mediated cartilage damage is completely and TNF-mediated bone damage is partially dependent on IL-1, suggesting that IL-1 is a crucial mediator for inflammatory cartilage and bone degradation.

SUBMITTER: Zwerina J

PROVIDER: S-EPMC1913858 | biostudies-other | 2007 Jul

REPOSITORIES: biostudies-other

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TNF-induced structural joint damage is mediated by IL-1.

Zwerina Jochen J Redlich Kurt K Polzer Karin K Joosten Leo L Krönke Gerhard G Distler Joerg J Hess Andreas A Pundt Noreen N Pap Thomas T Hoffmann Oskar O Gasser Juerg J Scheinecker Clemens C Smolen Josef S JS van den Berg Wim W Schett Georg G

Proceedings of the National Academy of Sciences of the United States of America 20070703 28

Blocking TNF effectively inhibits inflammation and structural damage in human rheumatoid arthritis (RA). However, so far it is unclear whether the effect of TNF is a direct one or indirect on up-regulation of other mediators. IL-1 may be one of these candidates because it has a central role in animal models of arthritis, and inhibition of IL-1 is used as a therapy of human RA. We removed the effects of IL-1 from a TNF-mediated inflammatory joint disease by crossing IL-1alpha and beta-deficient m ...[more]

PMID: 17609389

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Project description:PurposeWith the current use of biologics in rheumatoid arthritis (RA), there is a need to monitor ongoing structural joint damage due to the dissociation of articular cartilage damage from disease activity of RA. This study longitudinally analyzed levels of serum cartilage biomarkers during 54 weeks of infliximab therapy, to evaluate the feasibility of biomarkers for monitoring structural joint damage.MethodsSubjects comprised 33 patients with early RA and 33 patients with established RA. All patients received 3 mg/kg of infliximab and methotrexate for 54 weeks. Levels of the following serum cartilage markers were measured at baseline and at weeks 14, 22, and 54: hyaluronan (HA); cartilage oligometric matrix protein (COMP); type II collagen (CII)-related neoepitope (C2C); type II procollagen carboxy-propeptide (CPII); and keratin sulfate (KS). Time courses for each biomarker were assessed, and relationships between these biomarkers and clinical or radiographic parameters generally used for RA were investigated.ResultsLevels of CRP, MMP-3, DAS28-CRP, and annual progression of TSS were improved to similar degrees in both groups at week 54. HA and C2C/CPII were significantly decreased compared to baseline in the early RA group (p<0.001), whereas HA and COMP, but not C2C/CPII, were decreased in the established RA group. Strikingly, serum C2C/CPII levels were universally improved in early RA, regardless of EULAR response grade. Both ?HA and ?C2C/CPII from baseline to week 54 correlated significantly with not only ?CRP, but also ?DAS28 in early RA. Interestingly, when partial correlation coefficients were calculated by standardizing CRP levels, the significant correlation of ?HA to ?DAS28 disappeared, whereas correlations of ?C2C/CPII to ?DAS28, ?JNS, and ?HAQ remained significant. These results suggest a role of ?C2C/CPII as a marker of ongoing structural joint damage with the least association with CRP, and that irreversible cartilage damage in established RA limits restoration of the C2C/CPII level, even with tight control of joint inflammation.ConclusionThe temporal course of C2C/CPII level during anti-TNF therapy indicates that CII turnover shifts toward CII synthesis in early RA, but not in established RA, potentially due to irreversible cartilage damage. ?C2C/CPII appears to offer a useful marker reflecting ongoing structural joint damage, dissociated from inflammatory indices such as CRP and MMP-3.

Project description:IntroductionToll-like receptor (TLR)4 promotes joint inflammation in mice. Despite that several studies report a functional link between TLR4 and interleukin-(IL-)1? 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.MethodsTo 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.ResultsCompared to wild type (WT) mice, TLR4-/- mice showed attenuated arthritis and low interferon (IFN)-?, IL-12p35 and IL-1? transcript levels in the joints, but high transforming growth factor (TGF)-? 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-? and IL-1? production via T-bet and pro-IL-1? production. Recombinant IL-12, IFN-? and IL-1? administration restored arthritis, but reduced joint TGF-? levels in TLR4-/- mice. Moreover, a TGF-? 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.ConclusionTLR4-mediated IL-12 production by joint macrophages, mast cells and Gr-1+ cells enhances IFN-? and IL-1? production, which suppresses TGF-? production, thereby promoting antibody-induced arthritis.

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TNF-induced structural joint damage is mediated by IL-1.

Publications

TNF-induced structural joint damage is mediated by IL-1.

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