December 2014

Safety and efficacy of baricitinib at 24 weeks in patients with rheumatoid arthritis who have had an inadequate response to methotrexate

Ann Rheum Dis. 2015;74(2):333–340

Recent innovations in the treatment of RA have focused on the use of small molecules to inhibit intracellular kinases such as the JAK family. Baricitinib (LY3009104, formerly INCB028050) is an orally administered, potent, selective and reversible inhibitor of JAK1 and JAK2, which has shown anti-inflammatory effects, as well as preservation of cartilage and bone, in preclinical rodent studies.

This phase IIb study was designed to investigate multiple doses and dosing regimens of baricitin...

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The activity of JAK-STAT pathways in rheumatoid arthritis: constitutive activation of STAT3 correlates with interleukin 6 levels

Rheumatology (Oxford). 2014 Nov 17. pii: keu430. [Epub ahead of print]

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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September 2014

The active metabolite of spleen tyrosine kinase inhibitor fostamatinib abrogates the CD4+T cell-priming capacity of dendritic cells

Rheumatology (Oxford). 2015;54(1):169–177

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

Changes in serum creatinine in patients with active rheumatoid arthritis treated with tofacitinib: results from clinical trials

Arthritis Res Ther. 2014;16(4):R158

Despite preclinical and healthy volunteer studies of tofacitinib showing no evidence of nephrotoxicity, increases in mean serum creatinine levels have been observed in patients treated with the drug during the RA clinical development programme. This report explores the clinical significance of this change.

Serum creatinine values and renal adverse event data were pooled from patients who received =1 dose of tofacitinib either with background DMARDs or as monotherapy in five Phase 3 studie...

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July 2014

Nociceptive sensory neurons drive interleukin-23-mediated psoriasiform skin inflammation

Nature. 2014;510(7503):157–161.

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

Differential regulation of anti-inflammatory genes by p38 MAP kinase kinase 6

Journal of Inflammation 2014, 11:14

Several p38α inhibitors have been developed and evaluated in RA. However, despite pre-clinical data showing promise, the compounds have been shown to have little therapeutic efficacy. Previous studies have suggested this may be a result of inhibitors blocking the role of p38 in limiting inflammation. Previous studies by the same authors have shown that the targeting of MKK3 or MKK 6, which are the upstream activators of p38, may be superior to p38 blockade as the anti-inflammatory effects ...

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Alternative p38 MAPKs Are Essential for Collagen-Induced Arthritis

Arthritis and Rheumatology Vol66, No. 5, May2014 pp 1208-1217

MAPK family proteins are regulatory proteins, affecting processes such as synthesis and release of proinflammatory molecules which contribute to the pathogenesis of RA. In particular, the p38 MAPK protein family is central to proinflammatory cytokine production. There are four member of the p38 group; p38α, p38β, p38γ and p38δ. This study sought to evaluate p38γ and p38δ deficiency in mice CIA model. In p38γ-/- or p38δ-/- mice, the percentage of mic...

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Mechanism of Activation of Protein Kinase JAK2 by the Growth Hormone Receptor

Science 344, 2014; doi: 10.1126/science.1249783

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...

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Structure of the pseudokinase-kinase domains from protein kinase TYK2 reveals a mechanism for Janus kinase (JAK) autoinhibition

Proc Natl Acad Sci U S A. 2014 May 19. pii: 201401180. [Epub ahead of print]

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...

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Structural basis for the recognition of interferon-α receptor by tyrosine kinase 2

Nat Struct Mol Biol. 2014 May;21(5):443-8. doi: 10.1038/nsmb.2807. Epub 2014 Apr 6

Janus kinases, JAKs, are essential in the mediation of cytokine and interferon signalling whilst also being crucial to body processes such as immune function, hematopoeises, metabolism and cellular growth. However, it is not known is how the four members of the JAK family interact with and are activated by over 30 cytokine receptors with near perfect affinity and specificity. Currently, there are no crystal structures available for any JAK bound to a cytokine receptor. This study sought address ...

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