Arthritis & Rheumatism, Volume 63,
November 2011 Abstract Supplement

Abstracts of the American College of
Rheumatology/Association of Rheumatology Health Professionals
Annual Scientific Meeting
Chicago, Illinois November 4-9, 2011.

The CYLD/IKKbeta Axis Functions in Synovial Fibroblasts to Regulate TNF-Driven Arthritis.

Armaka1,  Maria, Pasparakis2,  Manolis, Mosialos3,  George, Kollias1,  George

Biomedical Sciences Research Center 'Alexander Fleming', Vari, Greece
Institute for Genetics, Centre for Molecular Medicine, University of Cologne, Cologne, Germany
School of Biology, Aristotle University of Thessaloniki, Thessaloniki, Greece and Biomedical Sciences Research Center 'Alexander Fleming', Vari, Greece


Synovial fibroblasts (SFs) are major cellular players in rheumatoid arthritis. We have shown previously in the human TNF transgenic (TghuTNF, Tg197) model of inflammatory polyarthritis that SF targeting by TNF is sufficient for the orchestration of the complete pathogenic process. Here, we have sought to identify SF-specific TNF-driven signaling pathways with physiological roles in the arthritogenic process. The deubiquitinating enzyme (DUB) CYLD is a tumor suppressor protein known for its role in repression of NF-kB and MAPK activation. The aim of this study was to assess the role of SF-specific ablation of the DUB CYLD and/or the NF-kappaB-related kinase, IKKbeta, in the development of arthritis in the TghuTNF model.


ColVI-Cre mice providing floxed-allele recombination specificity for SFs were crossbred into the TghuTNF, CYLD and/or IKKbeta conditional knock-out backgrounds. Histological analysis of synovial inflammation, as well as cartilage and bone destruction was performed in week 4, 8 and 14. SF cultures were generated in order to study the TNF-mediated responses of gene-deficient SFs by RT-PCR, western blot and FACS analysis.


TNF stimulation of CYLD-deficient SFs revealed that CYLD negatively regulates NF-kappaB whereas it does not affect MAPK responses of SFs. As a consequence, the expression profile of arthritis-related NF-kappaB-regulated genes was affected. Notably, the TghuTNF ColVI-Cre CYLDf/f mice show exacerbations of the arthritic phenotype over controls as early as 4weeks of age with profound synovial inflammation and cartilage degradation. Significant exacerbations over controls were also evident at the age of 8 weeks with intense TRAP activity in the joint area and complete loss of joint architecture. SFs from these mice showed a stronger activation phenotype exhibiting upregulation of VCAM-1, ICAM-1, high gelatinase activity and deregulated inflammatory gene expression compared to their non-Cre littermate controls. Furthermore, we show that TghuTNF ColVI-Cre IKKbetaf/f mice exhibit attenuated arthritic manifestations and that concomitant loss of both CYLD and IKKbeta expression in SFs from TghuTNF mice also results in the amelioration of the arthritic phenotype.


Our results demonstrate a physiologically significant role of the CYLD/IKKbeta pathway in modeled arthritis by showing that in TghuTNF mice the CYLD/IKKbeta axis regulates SF–specific arthritogenic responses downstream of TNF.

To cite this abstract, please use the following information:
Armaka, Maria, Pasparakis, Manolis, Mosialos, George, Kollias, George; The CYLD/IKKbeta Axis Functions in Synovial Fibroblasts to Regulate TNF-Driven Arthritis. [abstract]. Arthritis Rheum 2011;63 Suppl 10 :1640

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