March 2014

Inhibition of TAK1 and/or JAK can rescue impaired chondrogenic differentiation of human mesenchymal stem cells in osteoarthritis-like conditions

Tissue Engineering Part A doi:10/1089/ten.TEA.2013.0553

As it is nonvascularized and noninnervated, articular cartilage has a limited capacity to repair which presents a major clinical problem. In order to circumvent this inability to repair, stem cells can be placed into the joint or stimulated within the bone marrow. However, as the cartilage requiring repair is often in diseased joints, the factors involved in the disease state are potentially non-beneficial to the chondrogenesis of mesenchymal stem cells. In this study van Beuningen et al. invest...

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February 2014

Rheumatoid arthritis pathophysiology: update on emerging cytokine and cytokine-associated cell targets

Rheumatology doi:10.1093/rheumatology/ket414

Despite biologic therapies greatly improving the treatment of rheumatoid arthritis, many patients do not respond to current treatments or do not maintain response to these treatments. This review covers the evidence for the newly discovered role of Th17 cells, IL-12 and IL-17 family of cytokines in the pathogenesis of RA as well as the development of new therapies targeting these cytokines. With current biologics targeting cytokines such as TNF, IL-1ß and IL-6, the discovery of the Th17 subset o...

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January 2014

Selective inhibition of spleen tyrosine kinase (SYK) with a novel orally bioavailable small molecule inhibitor, RO9021, impinges on various innate and adaptive immune responses: implication for SYK inhibitors in autoimmune disease therapy

Arthritis Research and Therapy 2013 15:R146

Spleen tyrosine kinase (SYK) has already been described as a potential therapeutic target for the treatment of autoimmune diseases. Previously the SYK inhibitor fostamatinib was in clinical development for the treatment of rheumatoid arthritis, but has since been suspended. However, investigation into SYK inhibition continues with RO2091, a novel ATP-competitive inhibitor of SYK with reasonable selectivity, potency and oral bioavailability which has been shown to suppress various innate and adap...

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STA-21, a promising STAT3 inhibitor that reciprocally regulates Th17 and Treg, inhibits osteoclastgenesis and alleviates autoimmune inflammation

Arthritis and Rheumatism doi: 10.1002/art.38305

STAT3 (signal transducer and activator of transcription 3) is the major transcription factor in the differentiation of Th17 cells, which along with IL-17 are significant in the development of RA. STA-21 is a new small molecule with significant inhibitory effects on STAT3, impeding DNA binding activity, dimerization and STAT3-dependent luciferase activity. While the effect of STA-21 in RA has not been fully determined, it has been hypothesised that STA-21 will suppress arthritis in animal models ...

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The orally available Btk inhibitor ibrutinib (PCI-32765) protects against osteoclast-mediated bone loss

Bone 2014;60:8-15

Ibrutinib is a first-in-class, orally available Btk (Bruton’s tyrosine kinase) inhibitor which has been shown to be effective in the treatment against certain types of leukemia and autoimmune disorders. Btk regulates the expression of genes involved in the differentiation and function of osteoclasts, and therefore inhibiting Btk suppresses osteoclastic bone resorption. Results from in vitro testing showed the suppressive effects on osteoclasts and murine models of RA showed ibrutinib treatment p...

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Genome-wide association studies to advance our understanding of critical cell types and pathways in rheumatoid arthritis: recent findings and challenges

Curr. Opin. Rheumatol. 2014; 26:85–92. doi:10.1097/BOR.0000000000000012

A large number of loci implicated in disease susceptibility have been identified through genome-wide association studies (GWAS). In this review article, Diogo et al. discuss recent advances in GWAS in the context of rheumatoid arthritis pathogenesis and clinical applications. Relevant cells types and pathways in RA highlighted by GWAS to date include regulatory T-cells and CD4+ memory T cells as well as the JAK/STAT and NF-kB signalling pathways. The development of drugs targeting these pathways...

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October 2013

Proposal for a new nomenclature of disease-modifying antirheumatic drugs

Ann Rheum Dis 2013. doi: 10.1136/annrhuemdis-2013-204317

With the recent emergence of new therapeutics for rheumatoid arthritis, new nomenclature for disease-modifying antirheumatic drugs (DMARDs) may be needed to more accurately describe the new agents. Currently, DMARDs are divided into two broad groups: synthetic DMARDs (sDMARDs) and biological DMARDs (bDMARDs). The authors propose dividing synthetic DMARDs into conventional synthetic DMARDs (csDMARDs) which would encompass traditional DMARDs (e.g. methotrexate, leflunomide), and targeted synthetic...

Inhibition of JAK/STAT signalling pathway in rheumatoid synovial fibroblasts using small molecule compounds

Clin Exp Immunol. 2013 Aug 23. doi: 10.1111/cei.12190

Current JAK inhibitors CP-690,550 and INCB020850 have inhibitory effects on multiple JAK pathways, therefore Migita et al. tested whether selective inhibition of JAK3, using PF-956980, would be enough to ameliorate the rheumatoid inflammatory process. The results indicated that the inhibition of JAK3 alone is does not achieve control of STAT3-dependent signalling, and while it is suggested that the targeting of singular JAK pathways should lead to fewer adverse events, it appears that this appro...

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Tofacitinib in combination with nonbiologic disease-modifying antirheumatic drugs in patients with active rheumatoid arthritis

Ann Intern Med. 2013;159;253-261

Many patients with active RA have an inadequate response to biologic and nonbiologic DMARDs. Kremer et al carried out a one year, randomized trial studying the efficacy of tofacitinib in conjunction with background nonbiologic DMARDs (primarily methotrexate) in these patients. The results showed that using tofacitinib in combination with nonbiologic DMARDs rapidly improved physical function and reduced signs and symptoms of RA versus placebo, measured by ACR20 rates, DAS28 and HAQ-DI. The data f...

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August 2013

Targeting the SYK-BTK axis for the treatment of immunological and hematological disorders: recent progress and therapeutic perspectives

Pharmacol Ther. 2013 May; 138(2):294–309

This review focuses on targeting spleen tyrosine kinase (SYK) and Bruton’s tyrosine kinase (BTK) inhibitors as potential immunomodulatory agents for the treatment of autoimmune and inflammatory disorders with SYK inhibition showing encouraging efficacy in patients with RA. The paper describes the role of SYK and BTK in several therapy areas including autoimmune diseases, allergic inflammatory disorders and haematological cancers as well as their role in innate immunity and regulators of adaptive...

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