A review of JAK-STAT signalling in the pathogenesis of spondyloarthritis and the role of JAK inhibition.

Spondyloarthritis (SpA) comprises a group of chronic inflammatory diseases with overlapping clinical, genetic and pathophysiological features including back pain, peripheral arthritis, psoriasis, enthesitis and dactylitis. Several cytokines are involved in the pathogenesis of SpA, variously contributing to each clinical manifestation. Many SpA-associated cytokines, including IL-23, IL-17, IL-6, type I/II interferon and tumour necrosis factor signal directly or indirectly via the Janus kinase (JAK)-signal transducer and activator of transcription pathway. JAK signalling also regulates development and maturation of cells of the innate and adaptive immune systems. Accordingly, disruption of this signalling pathway by small molecule oral JAK inhibitors can inhibit signalling implicated in SpA pathogenesis. Herein we discuss the role of JAK signalling in the pathogenesis of SpA and summarize the safety and efficacy of JAK inhibition by reference to relevant SpA clinical trials.

Therapeutic interleukin-6 blockade reverses transforming growth factor-beta pathway activation in dermal fibroblasts: insights from the faSScinate clinical trial in systemic sclerosis.

OBJECTIVES: Skin fibrosis mediated by activated dermal fibroblasts is a hallmark of systemic sclerosis (SSc), especially in the subset of patients with diffuse disease. Transforming growth factor-beta (TGFß) and interleukin-6 (IL-6) are key candidate mediators in SSc. Our aim was to elucidate the specific effect of IL-6 pathway blockade on the biology of SSc fibroblasts in vivo by using samples from a unique clinical experiment-the faSScinate study-in which patients with SSc were treated for 24 weeks with tocilizumab (TCZ), an IL-6 receptor-α inhibitor. METHODS: We analysed the molecular, functional and genomic characteristics of explant fibroblasts cultured from matched skin biopsy samples collected at baseline and at week 24 from 12 patients receiving placebo (n=6) or TCZ (n=6) and compared these with matched healthy control fibroblast strains. RESULTS: The hallmark functional and molecular-activated phenotype was defined in SSc samples and was stable over 24 weeks in placebo-treated cases. RNA sequencing analysis robustly defined key dysregulated pathways likely to drive SSc fibroblast activation in vivo. Treatment with TCZ for 24 weeks profoundly altered the biological characteristics of explant dermal fibroblasts by normalising functional properties and reversing gene expression profiles dominated by TGFß-regulated genes and molecular pathways. CONCLUSIONS: We demonstrated the exceptional value of using explant dermal fibroblast cultures from a well-designed trial in SSc to provide a molecular framework linking IL-6 to key profibrotic pathways. The profound impact of IL-6R blockade on the activated fibroblast phenotype highlights the potential of IL-6 as a therapeutic target in SSc and other fibrotic diseases. TRIAL REGISTRATION NUMBER: NCT01532869; Post-results.

Safety and efficacy of subcutaneous tocilizumab in adults with systemic sclerosis (faSScinate): a phase 2, randomised, controlled trial.

BACKGROUND: Systemic sclerosis is a rare disabling autoimmune disease with few treatment options. The efficacy and safety of tocilizumab, an interleukin 6 receptor-α inhibitor, was assessed in the faSScinate phase 2 trial in patients with systemic sclerosis. METHODS: We did this double-blind, placebo-controlled study at 35 hospitals in Canada, France, Germany, the UK, and the USA. We enrolled adults with progressive systemic sclerosis of 5 or fewer years' duration from first non-Raynaud's sign or symptom. Patients were randomly assigned (1:1) to weekly subcutaneous tocilizumab 162 mg or placebo. The primary endpoint was the difference in mean change from baseline in modified Rodnan skin score at 24 weeks. This study is registered with ClinicalTrials.gov, number NCT01532869. FINDINGS: We enrolled 87 patients: 43 assigned to tocilizumab and 44 assigned to placebo. The least squares mean change in modified Rodnan skin score at 24 weeks was -3·92 in the tocilizumab group and -1·22 in the placebo group (difference -2·70, 95% CI -5·85 to 0·45; p=0·0915). The least squares mean change at 48 weeks was -6·33 in the tocilizumab group and -2·77 in the placebo group (treatment difference -3·55, 95% CI -7·23 to 0·12; p=0·0579). In one of several exploratory analyses, fewer patients in the tocilizumab group than in the placebo group had a decline in percent predicted forced vital capacity at 48 weeks (p=0·0373). However, we detected no significant difference in disability, fatigue, itching, or patient or clinician global disease severity. 42 (98%) of 43 patients in the tocilizumab group versus 40 (91%) of 44 in the placebo group had adverse events. 14 (33%) versus 15 (34%) had serious adverse events. Serious infections were more common in the tocilizumab group (seven [16%] of 43 patients) than in the placebo group (two [5%] of 44). One patient died in relation to tocilizumab treatment. INTERPRETATION: Tocilizumab was not associated with a significant reduction in skin thickening. However, the difference was greater in the tocilizumab group than in the placebo group and we found some evidence of less decline in forced vital capacity. The efficacy and safety of tocilizumab should be investigated in a phase 3 trial before definitive conclusions can be made about its risks and benefits. FUNDING: F Hoffmann-La Roche, Genentech.

Identification of Plasma Biomarkers from Rheumatoid Arthritis Patients Using an Optimized Sequential Window Acquisition of All THeoretical Mass Spectra (SWATH) Proteomics Workflow.

Rheumatoid arthritis (RA) is a systemic autoimmune and inflammatory disease. Plasma biomarkers are critical for understanding disease mechanisms, treatment effects, and diagnosis. Mass spectrometry-based proteomics is a powerful tool for unbiased biomarker discovery. However, plasma proteomics is significantly hampered by signal interference from high-abundance proteins, low overall protein coverage, and high levels of missing data from data-dependent acquisition (DDA). To achieve quantitative proteomics analysis for plasma samples with a balance of throughput, performance, and cost, we developed a workflow incorporating plate-based high abundance protein depletion and sample preparation, comprehensive peptide spectral library building, and data-independent acquisition (DIA) SWATH mass spectrometry-based methodology. In this study, we analyzed plasma samples from both RA patients and healthy donors. The results showed that the new workflow performance exceeded that of the current state-of-the-art depletion-based plasma proteomic platforms in terms of both data quality and proteome coverage. Proteins from biological processes related to the activation of systemic inflammation, suppression of platelet function, and loss of muscle mass were enriched and differentially expressed in RA. Some plasma proteins, particularly acute-phase reactant proteins, showed great power to distinguish between RA patients and healthy donors. Moreover, protein isoforms in the plasma were also analyzed, providing even deeper proteome coverage. This workflow can serve as a basis for further application in discovering plasma biomarkers of other diseases.

Levels of CXCL13 and sICAM-1 correlate with disease activity score in patients with rheumatoid arthritis treated with tocilizumab.

BACKGROUND: Tocilizumab (TCZ), a humanized monoclonal antibody against the interleukin-6 receptor, has been proven to be a safe and effective treatment for rheumatoid arthritis (RA). Because RA is a heterogenous disease and patient response to treatments can vary, identifying characteristics that predict which patients are more likely to respond to TCZ is important for optimal patient care. Serum levels of C-X-C motif chemokine ligand 13 (CXCL13) and soluble intercellular adhesion molecule-1 (sICAM-1) have been associated with response to TCZ in patients with RA. OBJECTIVES: To evaluate the association of CXCL13 and sICAM-1 with disease activity and response to TCZ in patients with early RA and those with inadequate response to disease-modifying antirheumatic drugs (DMARD-IR). METHODS: Baseline and week 24 serum CXCL13 and sICAM-1 levels were measured using available patient samples from the FUNCTION (early RA) and LITHE (DMARD-IR) trials. Correlations between CXCL13 and sICAM-1 levels and Disease Activity Score in 28 joints calculated with erythrocyte sedimentation rate (DAS28-ESR) at baseline and between change in CXCL13 and sICAM-1 and change in DAS28-ESR at week 24 were estimated. CXCL13 and sICAM-1 changes from baseline to week 24 were compared between treatment arms. The effects of TCZ treatment and baseline DAS28-ESR, CXCL13 and sICAM-1 levels on DAS28-ESR remission and 50% improvement per the American College of Rheumatology (ACR50) response at week 24 were determined. RESULTS: Overall, 458 patients from FUNCTION and 287 patients from LITHE were included. Correlation of baseline serum CXCL13 and sICAM-1 levels with DAS28-ESR was weak to moderate. CXCL13 and sICAM-1 levels decreased significantly at week 24 in TCZ-treated patients in both the early-RA and DMARD-IR populations. CXCL13 and sICAM-1 changes correlated moderately to weakly with DAS28-ESR changes at week 24 in both populations. The treatment regimen, but not baseline CXCL13 and sICAM-1 levels, had a significant effect on the likelihood of DAS28-ESR remission and ACR50 response. CONCLUSIONS: Although CXCL13 and sICAM-1 are modestly associated with RA disease activity, they do not predict response to TCZ in all RA populations.

Skin Gene Expression Is Prognostic for the Trajectory of Skin Disease in Patients With Diffuse Cutaneous Systemic Sclerosis.

OBJECTIVE: At present, there are no clinical or laboratory measures that accurately forecast the progression of skin fibrosis and organ involvement in patients with systemic sclerosis (SSc). The goal of this study was to identify skin biomarkers that could be prognostic for the progression of skin fibrosis in patients with early diffuse cutaneous SSc (dcSSc). METHODS: We analyzed clinical data and gene expression in skin biopsy samples from 38 placebo-treated patients, part of the Roche Safety and Efficacy of Subcutaneous Tocilizumab in Adults with Systemic Sclerosis (FASSCINATE) phase II study of tocilizumab in SSc. RNA samples were analyzed using nCounter. A trajectory model based on a modified Rodnan skin thickness score was used to describe 3 skin disease trajectories over time. We examined the association of skin gene expression with skin score trajectory groups, by chi-square test. Logistic regression was used to examine the prognostic power of each gene identified. RESULTS: We found that placebo-treated patients with high expression of messenger RNA for CD14, SERPINE1, IL13RA1, CTGF, and OSMR at baseline were more likely to have progressive skin score trajectories. We also found that those genes were prognostic for the risk of skin progression and that IL13RA1, OSMR, and SERPINE1 performed the best. CONCLUSION: Skin gene expression of biomarkers associated with macrophages (CD14, IL13RA1) and transforming growth factor ß activation (SERPINE1, CTGF, OSMR) are prognostic for progressive skin disease in patients with dcSSc. These biomarkers may provide guidance in decision-making about which patients should be considered for aggressive therapies and/or for clinical trials.

NK cell regulation of T cell-mediated responses.

NK cells promote adaptive immune responses through their production of type 1 and type 2 cytokines or chemokines. Secretion of these factors by activated NK cells influences the differentiation of B and T lymphocytes. Increasing evidence indicates that NK cells are also directly involved in dendritic cell (DC) maturation. By contrast, a potential role for direct cell-cell interactions between NK and T lymphocytes, in particular CD4(+) T cells, has not been explored. We provide evidence that activated human NK cells are able of promoting TcR-dependent proliferation of resting autologous peripheral blood CD4(+) T cells by a process that involves costimulatory molecules of the immunoglobulin (Ig) and tumor necrosis factor (TNF) superfamilies. These findings suggest a novel link between natural and adaptative immune responses.

The CD25-binding antibody Daclizumab High-Yield Process has a distinct glycosylation pattern and reduced antibody-dependent cell-mediated cytotoxicity in comparison to Zenapax®.

The CD25-binding antibody daclizumab high-yield process (DAC HYP) is an interleukin (IL)-2 signal modulating antibody that shares primary amino acid sequence and CD25 binding affinity with Zenapax®, a distinct form of daclizumab, which was approved for the prevention of acute organ rejection in patients receiving renal transplants as part of an immunosuppressive regimen that includes cyclosporine and corticosteroids. Comparison of the physicochemical properties of the two antibody forms revealed the glycosylation profile of DAC HYP differs from Zenapax in both glycan distribution and the types of oligosaccharides, most notably high-mannose, galactosylated and galactose-α-1,3-galactose (α-Gal) oligosaccharides, resulting in a DAC HYP antibody material that is structurally distinct from Zenapax. Although neither antibody elicited complement-dependent cytotoxicity in vitro, DAC HYP antibody had significantly reduced levels of antibody-dependent cell-mediated cytotoxicity (ADCC). The ADCC activity required natural killer (NK) cells, but not monocytes, suggesting the effects were mediated through binding to Fc-gamma RIII (CD16). Incubation of each antibody with peripheral blood mononuclear cells also caused the down-modulation of CD16 expression on NK cells and the CD16 down-modulation was greater for Zenapax in comparison to that observed for DAC HYP. The substantive glycosylation differences between the two antibody forms and corresponding greater Fc-mediated effector activities by Zenapax, including cell killing activity, manifest as a difference in the biological function and pharmacology between DAC HYP and Zenapax.

Levels of CXCL13 and sICAM-1 correlate with disease activity score in patients with rheumatoid arthritis treated with tocilizumab

Abstract Background: Tocilizumab (TCZ), a humanized monoclonal antibody against the interleukin-6 receptor, has been proven to be a safe and effective treatment for rheumatoid arthritis (RA). Because RA is a heterogenous disease and patient response to treatments can vary, identifying characteristics that predict which patients are more likely to respond to TCZ is important for optimal patient care. Serum levels of C-X-C motif chemokine ligand 13 (CXCL13) and soluble intercellular adhesion molecule-1 (sICAM-1) have been associated with response to TCZ in patients with RA. Objectives: To evaluate the association of CXCL13 and sICAM-1 with disease activity and response to TCZ in patients with early RA and those with inadequate response to disease-modifying antirheumatic drugs (DMARD-IR). Methods: Baseline and week 24 serum CXCL13 and sICAM-1 levels were measured using available patient samples from the FUNCTION (early RA) and LITHE (DMARD-IR) trials. Correlations between CXCL13 and sICAM-1 levels and Disease Activity Score in 28 joints calculated with erythrocyte sedimentation rate (DAS28-ESR) at baseline and between change in CXCL13 and sICAM-1 and change in DAS28-ESR at week 24 were estimated. CXCL13 and sICAM-1 changes from baseline to week 24 were compared between treatment arms. The effects of TCZ treatment and baseline DAS28-ESR, CXCL13 and sICAM-1 levels on DAS28-ESR remission and 50% improvement per the American College of Rheumatology (ACR50) response at week 24 were determined. Results: Overall, 458 patients from FUNCTION and 287 patients from LITHE were included. Correlation of baseline serum CXCL13 and sICAM-1 levels with DAS28-ESR was weak to moderate. CXCL13 and sICAM-1 levels decreased significantly at week 24 in TCZ-treated patients in both the early-RA and DMARD-IR populations. CXCL13 and sICAM-1 changes correlated moderately to weakly with DAS28-ESR changes at week 24 in both populations. The treatment regimen, but not baseline CXCL13 and sICAM-1 levels, had a significant effect on the likelihood of DAS28-ESR remission and ACR50 response. Conclusions: Although CXCL13 and sICAM-1 are modestly associated with RA disease activity, they do not predict response to TCZ in all RA populations.

Cross-talk between activated human NK cells and CD4+ T cells via OX40-OX40 ligand interactions.

It is important to understand which molecules are relevant for linking innate and adaptive immune cells. In this study, we show that OX40 ligand is selectively induced on IL-2, IL-12, or IL-15-activated human NK cells following stimulation through NKG2D, the low affinity receptor for IgG (CD16) or killer cell Ig-like receptor 2DS2. CD16-activated NK cells costimulate TCR-induced proliferation, and IFN-gamma produced by autologous CD4+ T cells and this process is dependent upon expression of OX40 ligand and B7 by the activated NK cells. These findings suggest a novel and unexpected link between the natural and specific immune responses, providing direct evidence for cross-talk between human CD4+ T cells and NK receptor-activated NK cells.