Secukinumab efficacy on resolution of enthesitis in psoriatic arthritis: pooled analysis of two phase 3 studies.

BACKGROUND: Enthesitis is one of the psoriatic arthritis (PsA) domains. Patients with enthesitis are associated with worse outcomes than those without enthesitis. The effect of secukinumab on the resolution of enthesitis in patients with PsA was explored using pooled data from the FUTURE 2 and 3 studies. METHOD: Assessments of enthesitis through week 104 used the Leeds Enthesitis Index. These post hoc analyses included resolution of enthesitis count (EC = 0), median time to first resolution of enthesitis (Kaplan-Meϊer estimate), and shift analysis (as observed) of baseline EC (1, 2, or 3-6) to full resolution (FR), stable (similar or reduction of EC), or worse (EC > baseline). Efficacy outcomes (ACR, PASI, HAQ-DI, SF-36 PCS, and DAS28-CRP) were assessed in patients with or without baseline enthesitis. Results are reported for secukinumab 300 and 150 mg in the overall population and by prior TNFi treatment. RESULTS: A total of 65% (466/712) of patients had baseline enthesitis. In the overall population, FR was achieved as early as week 16 in 65% (300 mg) and 56% (150 mg) versus 44% (placebo) patients, with further improvements to 91% (300 mg) and 88% (150 mg) at week 104. The majority (89%) of patients without enthesitis at baseline maintained this status at week 104. Median days to resolution of EC were shorter with secukinumab 300 and 150 mg versus placebo (57 and 85 vs 167 days, respectively). In patients with EC of 1 or 2, shift analysis from baseline to week 24 showed that more patients achieved FR with secukinumab 300 mg and 150 mg versus placebo, whereas no difference between secukinumab and placebo was shown in the more severe patients with EC of 3-6. Increases in proportions of patients with FR were observed with secukinumab irrespective of the severity of EC from baseline to week 104. Improvements in efficacy outcomes were similar in patients with or without enthesitis treated with secukinumab 300 mg. CONCLUSION: Secukinumab provided early and sustained resolution of enthesitis in patients with PsA over 2 years. Secukinumab 300 mg provided higher resolution than 150 mg in patients with more severe baseline EC and showed similar overall efficacy in patients with or without enthesitis. TRIAL REGISTRATION: FUTURE 2: ClinicalTrials.gov, NCT01752634 (date of study registration: December 19, 2012), and EudraCT, 2012-004439-22 (date of study registration: December 12, 2012) FUTURE 3: ClinicalTrials.gov, NCT01989468 (date of study registration: November 21, 2013), and EudraCT, 2013-004002-25 (date of study registration: December 17, 2013).

The role of microRNA-155/liver X receptor pathway in experimental and idiopathic pulmonary fibrosis.

BACKGROUND: Idiopathic pulmonary fibrosis (IPF) is progressive and rapidly fatal. Improved understanding of pathogenesis is required to prosper novel therapeutics. Epigenetic changes contribute to IPF; therefore, microRNAs may reveal novel pathogenic pathways. OBJECTIVES: We sought to determine the regulatory role of microRNA (miR)-155 in the profibrotic function of murine lung macrophages and fibroblasts, IPF lung fibroblasts, and its contribution to experimental pulmonary fibrosis. METHODS: Bleomycin-induced lung fibrosis in wild-type and miR-155-/- mice was analyzed by histology, collagen, and profibrotic gene expression. Mechanisms were identified by in silico and molecular approaches and validated in mouse lung fibroblasts and macrophages, and in IPF lung fibroblasts, using loss-and-gain of function assays, and in vivo using specific inhibitors. RESULTS: miR-155-/- mice developed exacerbated lung fibrosis, increased collagen deposition, collagen 1 and 3 mRNA expression, TGF-ß production, and activation of alternatively activated macrophages, contributed by deregulation of the miR-155 target gene the liver X receptor (LXR)α in lung fibroblasts and macrophages. Inhibition of LXRα in experimental lung fibrosis and in IPF lung fibroblasts reduced the exacerbated fibrotic response. Similarly, enforced expression of miR-155 reduced the profibrotic phenotype of IPF and miR-155-/- fibroblasts. CONCLUSIONS: We describe herein a molecular pathway comprising miR-155 and its epigenetic LXRα target that when deregulated enables pathogenic pulmonary fibrosis. Manipulation of the miR-155/LXR pathway may have therapeutic potential for IPF.

ACKR4 on Stromal Cells Scavenges CCL19 To Enable CCR7-Dependent Trafficking of APCs from Inflamed Skin to Lymph Nodes.

Dermal dendritic cells and epidermal Langerhans cells are APCs that migrate from skin to draining lymph nodes (LN) to drive peripheral tolerance and adaptive immunity. Their migration requires the chemokine receptor CCR7, which directs egress from the skin via dermal lymphatic vessels and extravasation into the LN parenchyma from lymph in the subcapsular sinus. CCR7 is activated by two chemokines: CCL19 and CCL21. CCL21 alone is sufficient for the migration of APCs from skin to LN. CCL19 and CCL21 also bind atypical chemokine receptor (ACKR) 4. ACKR4-mediated CCL21 scavenging by lymphatic endothelial cells lining the subcapsular sinus ceiling stabilizes interfollicular CCL21 gradients that direct lymph-borne CCR7(+)APCs into the parenchyma of mouse LN. In this study, we show that ACKR4 also aids APC egress from mouse skin under steady-state and inflammatory conditions. ACKR4 plays a particularly prominent role during cutaneous inflammation when it facilitates Langerhans cell egress from skin and enables the accumulation of dermal dendritic cells in skin-draining LN. Stromal cells in mouse skin, predominantly keratinocytes and a subset of dermal lymphatic endothelial cells, express ACKR4 and are capable of ACKR4-dependent chemokine scavenging in situ. ACKR4-mediated scavenging of dermal-derived CCL19, rather than CCL21, is critical during inflammation, because the aberrant trafficking of skin-derived APCs inAckr4-deficient mice is completely rescued by genetic deletion ofCcl19 Thus, ACKR4 on stromal cells aids the egress of APCs from mouse skin, and, during inflammation, facilitates CCR7-dependent cell trafficking by scavenging CCL19.

Targeting cell migration in rheumatoid arthritis.

PURPOSE OF REVIEW: To provide an update of past failures, future prospects and key challenges facing the therapeutic targeting of chemokines and their receptors in rheumatoid arthritis. RECENT FINDINGS: Clinical trials in rheumatoid arthritis have been undertaken with small molecule antagonists or neutralizing antibodies targeting CCR1, CCR5 and CXCL10. Some encouraging results have emerged. Laboratory and clinical research has identified CCL19, CXCL13 and CXCL12, and their receptors, as potential future targets. Developments in our appreciation of posttranslational chemokine modification highlight the complexity of chemokine networks operating in inflamed tissues, and the substantial gaps in existing knowledge. SUMMARY: Despite previous disappointments, there are still reasons to be optimistic that drugs targeting chemokines and their receptors could be developed for the treatment of rheumatoid arthritis. However, a deeper understanding of the chemokine networks at work in inflamed joints is a necessary prerequisite.

CCX-CKR deficiency alters thymic stroma impairing thymocyte development and promoting autoimmunity.

The atypical chemokine receptor CCX-CKR regulates bioavailability of CCL19, CCL21, and CCL25, homeostatic chemokines that play crucial roles in thymic lymphopoiesis. Deletion of CCX-CKR results in accelerated experimental autoimmunity induced by immunization. Here we show that CCX-CKR deletion also increases incidence of a spontaneous Sjögren's syndrome-like pathology, characterized by lymphocytic infiltrates in salivary glands and liver of CCX-CKR(-/-) mice, suggestive of a defect in self-tolerance when CCX-CKR is deleted. This prompted detailed examination of the thymus in CCX-CKR(-/-) mice. Negatively selected mature SP cells were less abundant in CCX-CKR(-/-) thymi, yet expansion of both DP and immature SP cells was apparent. Deletion of CCX-CKR also profoundly reduced proportions of DN3 thymocyte precursors and caused DN2 cells to accumulate within the medulla. These effects are likely driven by alterations in thymic stroma as CCX-CKR(-/-) mice have fewer cTECs per thymocyte, and cTECs express the highest level of CCX-CKR in the thymus. A profound decrease in CCL25 within the thymic cortex was observed in CCX-CKR(-/-) thymi, likely accounting for their defects in thymocyte distribution and frequency. These findings identify a novel role for CCX-CKR in regulating cTEC biology, which promotes optimal thymocyte development and selection important for self-tolerant adaptive immunity.

Soluble ST2 associates with diabetes but not established cardiovascular risk factors: a new inflammatory pathway of relevance to diabetes?

Preliminary data mostly from animal models suggest the sST2/IL-33 pathway may have causal relevance for vascular disease and diabetes and thus point to a potential novel inflammatory link to cardiometabolic disease. However, the characterisation of sST2 levels in terms of metabolic or vascular risk in man is completely lacking. We sought to address this gap via a comprehensive analysis of risk factor and vascular correlates of sST2 in a cross-sectional study (pSoBid). We measured sST2 in plasma in 639 subjects and comprehensively related it to cardiovascular and diabetes risk factors and imaged atherosclerosis measures. Circulating sST2 levels increased with age, were lower in women and in highest earners. After adjusting for age and gender, sST2 levels associated strongly with markers of diabetes, including triglycerides [effect estimate (EE) per 1 standard deviation increase in sST2:1.05 [95%CI 1.01,1.10]), liver function (alanine aminotransaminase [ALT] and γ-glutamyl transferase [GGT]: EE 1.05 [1.01,1.09] and 1.13 [1.07,1.19] respectively), glucose (1.02 [1.00,1.03]) and sICAM-1 (1.05 [1.02,1.07]). However, sST2 levels were not related to smoking, cholesterol, blood pressure, or atheroma (carotid intima media thickness, plaque presence). These results suggest that sST2 levels, in individuals largely without vascular disease, are related principally to markers associated with diabetes and ectopic fat and add support for a role of sST2 in diabetes. Further mechanistic studies determining how sST2 is linked to diabetes pathways may offer new insights into the inflammatory paradigm for type 2 diabetes.

Simultaneous activation of the liver X receptors (LXRα and LXRß) drives murine collagen-induced arthritis disease pathology.

BACKGROUND: It has previously been shown that dual activation of the Liver X Receptors (LXRα and LXRß) by the agonist, GW3965, enhances pathology in a murine model of collagen-induced arthritis. OBJECTIVE: To determine whether LXRα or LXRß have discrete roles in driving articular inflammation. METHODS: Arthritis was induced in male C57BL/6 wild-type (WT), LXRα-/-, LXRß-/- and LXRα/ß double KO mice by injection with type II collagen and treated with 30 mg/kg of the LXR agonist GW3965 or vehicle control. The mice were monitored for articular inflammation and cartilage degradation by scoring for clinical signs of arthritis and by histological examination of the joints. RESULTS: Administration of 30 mg/kg GW3965 significantly increases the severity of arthritis in WT but not LXRα-/-, LXRß-/- or LXRα/ß KO mice as assessed by an increase in the clinical score, paw thickness and articular histological analysis. CONCLUSION: The proinflammatory effects associated with the administration of GW3965 are mediated specifically through LXRs. The absence of increased disease severity in the LXRα-/- and LXRß-/- GW3965-treated groups shows for the first time that agonism of both LXRα and LXRß is required to drive proinflammatory pathways in vivo.

IL-33 induces skin inflammation with mast cell and neutrophil activation.

Psoriasis is a common chronic autoimmune condition of the skin characterized by hyperplasia of epidermal keratinocytes associated with pro-inflammatory cytokines. IL-33 is a new member of the IL-1 superfamily that signals through the ST2 receptor and was originally defined as an inducer of T helper 2 (Th2) cytokines. Recently, broader immune activatory potential has been defined for IL-33 particularly via mast cell activation and neutrophil migration. Here, we show that ST2(-/-) mice exhibit reduced cutaneous inflammatory responses compared with WT mice in a phorbol ester-induced model of skin inflammation. Furthermore, injections of IL-33 into the ears of mice induce an inflammatory skin lesion. This inflammatory response was partially dependent on mast cells as mast cell-deficient mice (Kit(W-sh/W-sh) ) showed delayed responses to IL-33. IL-33 also recruited neutrophils to the ear, an effect mediated in part by increased production of the chemokine KC (CXCL1). Finally, we show that IL-33 expression is up-regulated in the epidermis of clinical psoriatic lesions, compared with healthy skin. These results therefore demonstrate that IL-33 may play a role in psoriasis-like plaque inflammation. IL-33 targeting may provide a new treatment strategy for psoriasis.

MicroRNA-155 as a proinflammatory regulator in clinical and experimental arthritis.

MicroRNA (miRNA) species (miR) regulate mRNA translation and are implicated as mediators of disease pathology via coordinated regulation of molecular effector pathways. Unraveling miR disease-related activities will facilitate future therapeutic interventions. miR-155 recently has been identified with critical immune regulatory functions. Although detected in articular tissues, the functional role of miR-155 in inflammatory arthritis has not been defined. We report here that miR-155 is up-regulated in synovial membrane and synovial fluid (SF) macrophages from patients with rheumatoid arthritis (RA). The increased expression of miR-155 in SF CD14(+) cells was associated with lower expression of the miR-155 target, Src homology 2-containing inositol phosphatase-1 (SHIP-1), an inhibitor of inflammation. Similarly, SHIP-1 expression was decreased in CD68(+) cells in the synovial lining layer in RA patients as compared with osteoarthritis patients. Overexpression of miR-155 in PB CD14(+) cells led to down-regulation of SHIP-1 and an increase in the production of proinflammatory cytokines. Conversely, inhibition of miR-155 in RA synovial CD14(+) cells reduced TNF-α production. Finally, miR-155-deficient mice are resistant to collagen-induced arthritis, with profound suppression of antigen-specific Th17 cell and autoantibody responses and markedly reduced articular inflammation. Our data therefore identify a role of miR-155 in clinical and experimental arthritis and suggest that miR-155 may be an intriguing therapeutic target.

Quantitative detection of human tumor necrosis factor α by a resonance raman enzyme-linked immunosorbent assay.

Tumor necrosis factor α is an inflammatory cytokine which has been linked with many infectious and inflammatory diseases. Detection and quantification of this key biomarker is commonly achieved by use of an enzyme-linked immunosorbent assay (ELISA). This fundamental technique uses the spectroscopic detection of a chromogen such as 3,3',5,5'-tetramethylbenzidine (TMB). Horseradish peroxidase (HRP), bound to the detection antibody, catalyzes the oxidation of TMB by hydrogen peroxide to generate colored products which may be measured spectrophotometrically. In this study we have used a conventional ELISA kit and shown that, by replacing the traditional colorimetric detection with resonance Raman spectroscopy, we can achieve 50 times lower detection limits and the potential for multiplexed analysis is increased. In this approach, the laser wavelength was tuned to be in resonance with an electronic transition of the oxidized TMB. The relative intensity of the enhanced Raman bands is proportional to the amount of TMB, thus providing a means of improved quantification. Furthermore, TMB is one of the most widely used chromogenic substrates for HRP-based detection and commercial ELISA test kits, indicating that this detection technique is applicable to a large number of target analytes.

Embracing novel cytokines in RA - complexity grows as does opportunity!

Current therapeutics for the treatment of rheumatoid arthritis (RA) offer limited efficacy in a restricted number of patients. There is, therefore, an unmet clinical need for the development of more efficacious therapeutics for the treatment of disease. Anti-TNFalpha therapy has provided proof of principle that cytokine blockade is an appropriate strategy by which to inhibit disease progression. In this review, we describe the basic biology of potential novel cytokine targets and the results of recent clinical trials, with particular focus on the cytokines related to Th17 biology, namely interleukin (IL)-12, IL-23 and IL-17, in addition to the TNF superfamily and the adipocytokines.

Interleukin-33 induces protective effects in adipose tissue inflammation during obesity in mice.

RATIONALE: Chronic low-grade inflammation involving adipose tissue likely contributes to the metabolic consequences of obesity. The cytokine interleukin (IL)-33 and its receptor ST2 are expressed in adipose tissue, but their role in adipose tissue inflammation during obesity is unclear. OBJECTIVE: To examine the functional role of IL-33 in adipose tissues and investigate the effects on adipose tissue inflammation and obesity in vivo. METHODS AND RESULTS: We demonstrate that treatment of adipose tissue cultures in vitro with IL-33 induced production of Th2 cytokines (IL-5, IL-13, IL-10) and reduced expression of adipogenic and metabolic genes. Administration of recombinant IL-33 to genetically obese diabetic (ob/ob) mice led to reduced adiposity, reduced fasting glucose and improved glucose and insulin tolerance. IL-33 also induced accumulation of Th2 cells in adipose tissue and polarization of adipose tissue macrophages toward an M2 alternatively activated phenotype (CD206(+)), a lineage associated with protection against obesity-related metabolic events. Furthermore, mice lacking endogenous ST2 fed high-fat diet had increased body weight and fat mass and impaired insulin secretion and glucose regulation compared to WT controls fed high-fat diet. CONCLUSIONS: In conclusion, IL-33 may play a protective role in the development of adipose tissue inflammation during obesity.

Mast cells express IL-17A in rheumatoid arthritis synovium.

The proinflammatory cytokine IL-17A is considered a crucial player in rheumatoid arthritis (RA) pathogenesis. In experimental models of autoimmune arthritis, it has been suggested that the cellular source of IL-17A is CD4(+) T cells (Th17 cells). However, little is known about the source of IL-17 in human inflamed RA tissue. We explored the cellular sources of IL-17A in human RA synovium. Surprisingly, only a small proportion of IL-17-expressing cells were T cells, and these were CCR6 negative. Unexpectedly, the majority of IL-17A expression colocalized within mast cells. Furthermore, we demonstrated in vitro that mast cells produced RORC-dependent IL-17A upon stimulation with TNF-alpha, IgG complexes, C5a, and LPS. These data are consistent with a crucial role for IL-17A in RA pathogenesis but suggest that in addition to T cells innate immune pathways particularly mediated via mast cells may be an important component of the effector IL-17A response.

Apolipoprotein E-deficient mice are resistant to the development of collagen-induced arthritis.

OBJECTIVE: To determine whether elevated serum lipid levels resulting from feeding animals a high-fat diet can affect the inflammatory process in C57BL/6 (B6) wild-type (WT) and B6 ApoE(-/-) mouse models of collagen-induced arthritis (CIA). METHODS: Male B6 WT or ApoE(-/-) mice were fed either a normal chow diet or a high-fat diet. CIA was induced in mice at 12 weeks of age using type II chicken collagen, Freund's complete adjuvant, and, on occasion, a lipopolysaccharide boost. Expression levels of autoantibodies and cytokines were measured using enzyme-linked immunosorbent assay and multiplex assay, respectively. RESULTS: Whereas B6 WT mice developed severe articular inflammation after collagen immunization, ApoE(-/-) mice developed no clinical or histologic evidence of disease regardless of whether they had been fed a high-fat diet or a normal chow diet. The fact that arthritis was not present in ApoE(-/-) mice did not result from inadequate production of serum IgG2a collagen antibodies, since levels observed in ApoE(-/-) mice were similar to those observed in arthritic B6 WT control mice. Critically, development of atherosclerosis in ApoE(-/-) mice was not affected by the CIA protocol. CONCLUSION: Our findings suggest that ApoE(-/-) mice are resistant to the development of CIA. Intriguingly, induction of host autoimmunity in the absence of articular inflammation had no effect on atherosclerosis progression, suggesting that articular inflammatory load may be a critical risk factor in vascular pathology.

Animal models of rheumatoid arthritis.

Animal models have been used extensively in studies of rheumatoid arthritis pathogenesis. Despite the inherent limitations of all animal models, several rodent models have significantly progressed our understanding of the fundamental mechanisms underpinning rheumatoid arthritis and contributed to several current major advances in treatment. These models include the induced arthritis models such as collagen-induced arthritis, collagen-antibody-induced arthritis, zymosan-induced arthritis, and the methylated BSA model, and the genetically manipulated or spontaneous arthritis models such as the TNF-alpha-transgenic mouse, K/BxN mouse, and the Skg mouse. Here, we describe these animal models and discuss their advantages and limitations.

Liver X receptor agonism promotes articular inflammation in murine collagen-induced arthritis.

OBJECTIVE: Liver X receptors (LXRs) have previously been implicated in the regulation of inflammation and have, in general, been ascribed an antiinflammatory role. This study was therefore undertaken to explore the biologic mechanisms of LXRs in vivo and in vitro in an experimental inflammatory arthritis model. METHODS: Male DBA/1 mice were immunized with type II collagen and treated from an early or established stage of arthritis with 2 different concentrations of the LXR agonists T1317 and GW3965 or vehicle control. The mice were monitored for articular inflammation and cartilage degradation by scoring for clinical signs of arthritis, histologic examination of the joints, and analysis of serum cytokine and antibody levels. In vitro, primary human monocytes and T cells were cultured in the presence of GW3965 or T1317, and the concentrations of proinflammatory cytokines were measured by multiplex assay. RESULTS: Contrary to expectations, LXR agonism with the use of 2 discrete, specific molecular entities led to substantial exacerbation of articular inflammation and cartilage destruction in this murine collagen-induced arthritis model. This was associated ex vivo with elevated cytokine expression, with enhanced Th1 and Th17 cellular responses, and with elevated collagen-specific autoantibody production. In vitro, LXR agonists, in concert with lipopolysaccharide, promoted cytokine and chemokine release from human monocytes, and similar effects were observed in a T cell-macrophage coculture model that closely recapitulates the pathways that drive synovial cytokine release. CONCLUSION: Since LXRs are present in rheumatoid arthritis (RA) synovium, these results suggest that LXR-mediated pathways could exacerbate the chronic inflammatory response typical of RA.

IL-33 reduces the development of atherosclerosis.

Atherosclerosis is a chronic inflammatory disease of the vasculature commonly leading to myocardial infarction and stroke. We show that IL-33, which is a novel IL-1-like cytokine that signals via ST2, can reduce atherosclerosis development in ApoE(-/-) mice on a high-fat diet. IL-33 and ST2 are present in the normal and atherosclerotic vasculature of mice and humans. Although control PBS-treated mice developed severe and inflamed atherosclerotic plaques in the aortic sinus, lesion development was profoundly reduced in IL-33-treated animals. IL-33 also markedly increased levels of IL-4, -5, and -13, but decreased levels of IFNgamma in serum and lymph node cells. IL-33 treatment also elevated levels of total serum IgA, IgE, and IgG(1), but decreased IgG(2a), which is consistent with a Th1-to-Th2 switch. IL-33-treated mice also produced significantly elevated antioxidized low-density lipoprotein (ox-LDL) antibodies. Conversely, mice treated with soluble ST2, a decoy receptor that neutralizes IL-33, developed significantly larger atherosclerotic plaques in the aortic sinus of the ApoE(-/-) mice compared with control IgG-treated mice. Furthermore, coadministration of an anti-IL-5 mAb with IL-33 prevented the reduction in plaque size and reduced the amount of ox-LDL antibodies induced by IL-33. In conclusion, IL-33 may play a protective role in the development of atherosclerosis via the induction of IL-5 and ox-LDL antibodies.

Emerging cytokine targets in rheumatoid arthritis.

PURPOSE OF REVIEW: The utility of cytokines as therapeutic targets in rheumatoid arthritis has been unequivocally demonstrated by the success of tumour necrosis factor blockade in clinical practice. Partial and non-responses to tumour necrosis factor blocking agents, however, together with the increasing clinical drive to remission induction, requires that further therapeutic targets be identified. RECENT FINDINGS: Numerous cytokine activities with pathogenetic potential have now been demonstrated in rheumatoid arthritis synovial membrane, including members of the IL-1 superfamily and the IL-12 superfamily. Continued efforts are ongoing to target IL-6 and IL-15 in clinical trials with promising data emerging. There is particular interest in the biology of IL-17 and of the recently described IL-32 as critical effector mediators. SUMMARY: Novel cytokine activities are emerging on an ongoing basis. There remain difficulties in ascribing the optimal regulatory hierarchy for given moieties on the basis of existing preclinical model systems. This in turn poses novel challenges in determining which cytokines represent the best therapeutic targets.