Current biologic therapies for RA, such as biologic cytokine inhibitors, which selectively target inflammatory molecules with an exquisite degree of specificity, are not clinically effective in all patients with rheumatoid arthritis. As such, there remains an unmet clinical need for more effective and better tolerated therapies. Baricitinib (LY3009104, also previously known as INCB028050) is a potent and selective small molecule inhibitor of JAK1/2, which play an important role in cytokine signa...

IL-6 stimulates intestinal epithelial proliferation and repair after injury

PLoS One. 2014 Dec 5;9(12):e114195. doi: 10.1371/journal.pone.0114195. eCollection 2014.

IL-6 is an inflammatory cytokine known to contribute to a number of autoimmune diseases such as RA. Therapies targeting the soluble IL-6 receptor have now become effective treatments for RA. However, one unforeseen, yet rare, potential complication of anti-IL-6 therapy is bowel perforation. Yet within the intestine, IL-6 protects intestinal epithelial cells from apoptosis during prolonged inflammation.

The authors hypothesized that IL-6 may have beneficial properties in wound response/rep...

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December 2014

Non-response, parenteral administration and cost to produce are all aspects associated with the currently available anti-cytokine agents for RA. These related factors mean that alternative drugs are now being developed. Recent developments in therapeutic drugs to treat RA have focused on Janus kinases (JAKs) and signal transducer and activator of transcription (STATs) transcription pathways. Several cytokines that regulate immune responses in RA, such as IFN-g, IL-6 and IL-10, activate JAK-STAT ...

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The JAK inhibitor tofacitinib suppresses synovial JAK1-STAT signalling in rheumatoid arthritis

Ann Rheum Dis. 2014 Nov 14. pii: annrheumdis-2014-206028. doi: 10.1136/annrheumdis-2014-206028. [Epub ahead of print]

Targeting intracellular pathways such as JAK/STAT represents a novel approach to the treatment of RA. Tofacitinib is an oral JAK inhibitor, proven to be effective in the treatment of RA, yet the pathways affected by tofacitinib and the effects on gene expression in situ are unknown. In this study, Boyle et al. tested the hypothesis that tofacitinib targets cytokine signalling critical to the pathogenesis of rheumatoid synovitis by investigating tofacitinib effects on synovial pathobiology.

September 2014

SYK is a core signalling protein that drives inflammatory responses and is fundamental to the propagation of signals via numerous immune receptors. While the clinical development of the first SYK inhibitor, fostamatinib, was stopped due to poor results in the phase 3 RA programme, there remain important questions of mechanism which may aid future developments of this target.

In these murine studies, investigators sought to gain an understanding of how the active metabolite of fostamatini...

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August 2014

This study pools data from the global tofacitinib RA development programme (phase II, phase III and long-term extension studies) to determine the rate of infections and all-cause mortality with tofacitinib treatment. In total, 4,789 patients within these studies received tofacitinib, at varying doses and with varying duration.

The overall incidence rate of serious infections was 3.09 events/100 patient-years (95% CI 2.73–3.49), which was stable over time, with pneumonia and skin and soft...

July 2014

The abnormal activation of skin immune cells, such as dermal dendritic cells (DDCs) and interleukin (IL)-17-producing γδ T (γδT17) cells, by IL-23 is known to provoke psoriasis-type inflammation. What is less well known is how peripheral nerves regulate cutaneous immune responses. In this study, IL-23-dependent psoriasis-like inflammation was induced in mice to help determine the precise molecular mechanism of neuroimmune communication in the skin. Findings indicate nocic...

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June 2014

Class I cytokine receptors are key regulators of many processes within the body. The receptors use the JAK-STAT signalling pathway, the deregulation of which causes it to become an important pathway in oncogenesis. Despite this, the processes responsible for JAK2 activation by class I receptors remains elusive. Previous studies using growth hormone and its receptor have led to a model of receptor activation where hormone induced receptor dimerization resulted in close proximity of the receptor i...
The JAK family of kinases (JAK1, JAK2, JAK3 and TYK2) are receptor-associated tyrosine kinases that act downstream of many cytokines and interferons. Recent studies have provided structural information about the kinase and pseudokinase domains of JAKs however the molecular mechanism by which JAK activity is regulated by the pseudokinase domain is poorly understood. This study builds on a recent finding that the N terminus of the JAK1 pseudokinase group may act as a switch for kinase activation b...

April 2014

Our understanding of inflammatory rheumatic diseases such as rheumatoid arthritis has significantly increased over the last 20 years. With this greater understanding we have seen a significant improvement in the therapy of RA and other inflammatory rheumatic diseases. In this review, Moscai et al. discuss the improvements in therapies for the treatment of these diseases from the introduction of methotrexate as a frontline therapy through to the current era and approval of the first small molecul...

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