Effects of mPGES-1 deletion on eicosanoid and fatty acid profiles in mice.

mPGES-1 is considered an alternative target for anti-inflammatory treatment with improved selectivity and safety compared to NSAIDs. mPGES-1 depletion not only suppresses inflammation via absence of inducible PGE2 but might also cause an activation of anti-inflammatory pathways. We studied effects of mPGES-1 deletion on the eicosanoid and fatty acid (FA) profiles in mice. In LPS-induced peritoneal macrophages from mPGES-1 knock-out (mPGES-1-/-, KO) mice PGE2 production was markedly attenuated, whereas levels of PGD2 metabolites (15-deoxy-Δ(12,14) PGJ2 and 15-deoxy-Δ(12,14) PGD2) were increased compared to wild type mice. The levels of oxidized fatty acid 13-HODE were also significantly up-regulated in KO macrophages. Significant differences in the total lipid FA composition (decrease in monounsaturated FA and increase in eicosadienoic acid) were detected in spleen of KO and WT mice. These effects of mPGES-1 deletion on eicosanoid and fatty acid metabolism have important implications for future mPGES-1 inhibitors and deserve further investigation.

Characterization of a new mPGES-1 inhibitor in rat models of inflammation.

Microsomal prostaglandin E synthase (mPGES)-1 inhibition has been proposed as an alternative to cyclooxygenase (COX) inhibition in the treatment of pain and inflammation. This novel approach could potentially mitigate the gastro-intestinal and cardiovascular side effects seen after long-term treatment with traditional non-steroidal anti-inflammatory drugs (NSAIDs) and Coxibs respectively. Several human mPGES-1 inhibitors have been developed in the recent years. However, they were all shown to be considerably less active on rodent mPGES-1, precluding the study of mPGES-1 inhibition in rodent models of inflammation and pain. The aim of this study was to characterize the new mPGES-1 inhibitor compound II, a pyrazolone that has similar potency on rat and human recombinant mPGES-1, in experimental models of inflammation. In cell culture, compound II inhibited PGE2 production in synovial fibroblasts from patients with rheumatoid arthritis (RASF) and in rat peritoneal macrophages. In vivo, compound II was first characterized in the rat air pouch model of inflammation where treatment inhibited intra-pouch PGE2 production. Compound II was also investigated in a rat adjuvant-induced arthritis model where it attenuated both the acute and delayed inflammatory responses. In conclusion, compound II represents a valuable pharmacological tool for the study of mPGES-1 inhibition in rat models.

Characterization of a human and murine mPGES-1 inhibitor and comparison to mPGES-1 genetic deletion in mouse models of inflammation.

Microsomal prostaglandin E synthase-1 (mPGES-1) inhibition has been suggested as an alternative to cyclooxygenase (COX) inhibition in the treatment of pain and inflammation. We characterized a selective inhibitor of mPGES-1 activity (compound III) and studied its impact on the prostanoid profile in various models of inflammation. Compound III is a benzoimidazole, which has a submicromolar IC50 in both human and rat recombinant mPGES-1. In cellular assays, it reduced PGE2 production in A549 cells, mouse macrophages and blood, causing a shunt to the prostacyclin pathway in the former two systems. Lastly, we assayed compound III in the air pouch model to verify its impact on the prostanoid profile and compare it to the profile obtained in mPGES-1 k.o. mice. As opposed to mPGES-1 genetic deletion, which attenuated PGE2 production and caused a shunt to the thromboxane pathway, mPGES-1 inhibition with compound III reduced PGE2 production and tended to decrease the levels of other prostanoids.

Real-World Retention and Clinical Effectiveness of Secukinumab for Axial Spondyloarthritis: Results From the Canadian Spondyloarthritis Research Network.

OBJECTIVE: Axial spondyloarthritis (axSpA) is a chronic, immune-mediated, inflammatory condition consisting of 2 clinical subsets: nonradiographic axSpA and ankylosing spondylitis, the latter having an estimated prevalence of 0.2% to 1% in Canada. Secukinumab (SEC) received Health Canada approval in 2016 for the treatment of adults with axSpA who have responded inadequately to conventional treatment, and has demonstrated efficacy and safety through extensive clinical trials. However, there is limited evidence on its real-world use in Canada. The objective of this study was to use the Canadian Spondyloarthritis (CanSpA) Research Network to describe real-world retention and effectiveness of SEC in the Canadian axSpA population. METHODS: This was an observational cohort study of Canadian patients with axSpA aged 18 to 65 years within the CanSpA network who had received treatment with SEC. Patients were indexed on the first date of SEC initiation. Retention and clinical effectiveness were assessed at 12 months postindex. Clinical effectiveness was measured as the proportion in remission and change in disease activity using multiple clinical indices. RESULTS: A total of 146 patients were included. Overall retention was estimated at 62.9%. Low disease activity (ie, Bath Ankylosing Spondylitis Disease Activity Index < 4) was achieved in 29.2% of patients, and 2% had achieved remission based on the Ankylosing Spondylitis Disease Activity Score. Bath Ankylosing Spondylitis Metrology Index scores improved by more than 60% from baseline to 12 months. CONCLUSION: The results of this real-world study of Canadian patients with axSpA, one of the first of its kind, support the effectiveness of SEC for treatment of axSpA. The CanSpA network presents an opportunity to continue building and improving the real-world evidence base for treatment of Canadian patients with spondyloarthritis.

Real-World Retention and Clinical Effectiveness of Secukinumab for Psoriatic Arthritis: Results From the Canadian Spondyloarthritis Research Network.

OBJECTIVE: Psoriatic arthritis (PsA) is an immune-mediated disease characterized by pain, stiffness, and swelling of peripheral joints, with an estimated prevalence in Canada of 0.45%. Treatment aims to minimize disease activity, reduce progression of damage, and improve quality of life. Secukinumab (SEC) is a biologic disease-modifying antirheumatic drug (bDMARD) that has demonstrated efficacy and safety for PsA in clinical trials; however, there is limited real-world evidence on its use in Canada. The objective of this study was to use the Canadian Spondyloarthritis (CanSpA) Research Network to describe real-world retention and effectiveness of SEC among Canadian patients with PsA. METHODS: This was an observational cohort study of Canadian patients with PsA, 18 to 65 years of age, who attended a clinic of the CanSpA network and received treatment with SEC. Patients were indexed on the date they first initiated SEC. Retention was assessed at 12 months postindex. Clinical effectiveness was measured as the proportion of patients in remission and change in disease activity from baseline to 12 months using several clinical indices. RESULTS: In total, 213 patients were included. Overall retention was estimated at 73.6% at 12 months (81.8% for bDMARD- or targeted synthetic DMARD-naïve patients). Out of 110 patients, 17 (15.5%) were in remission based on the Disease Activity Index in Psoriatic Arthritis in 28 joints, and 10 out of 70 patients (14.3%) were in remission based on the Psoriatic Arthritis Disease Activity Score at 12 months. The Psoriasis Area and Severity Index improved by 65.8%; the tender joint count in 68 joints and the swollen joint count in 66 joints improved by 65.5% and 73.7%, respectively. CONCLUSION: This is the first nationwide study that we know of to describe real-world use of SEC in Canada for PsA, and the results support its effectiveness in a Canadian real-world setting. The CanSpA network represents a unique opportunity to build and improve the real-world evidence base for SpA treatment in Canada.

Work-Related Issues and Physical and Psychological Burden in Canadian Patients With Axial Spondyloarthritis: Results From the International Map of Axial Spondyloarthritis.

OBJECTIVE: To identify factors associated with work-related issues in Canadian patients with axial spondyloarthritis. METHODS: Data from 542 Canadian patients who participated in the International Map of Axial Spondyloarthritis online survey were analyzed. Participants who were employed, unemployed, or on short-term disability were included in this analysis. Regression analysis was used to study the association between work-related issues, disease activity (Bath Ankylosing Spondylitis Disease Activity Index [BASDAI]), and psychological distress (12-item General Health Questionnaire [GHQ-12]). RESULTS: The mean age of surveyed participants was 44.3 (SD 13.9) years, 81% were university educated, and 52.6% employed. A substantial proportion had high disease activity (BASDAI ≥ 4, 72.1%) and psychological distress (GHQ-12 ≥ 3, 53.1%); 81% had work-related issues. This study analyzed responses from a subset of participants who were either employed, unemployed, or on short-term disability (n = 339). Ninety percent of this subset reported at least 1 work-related issue in the year before questionnaire completion, with the most frequent being absenteeism (49.3%) and missing work for healthcare provider visits (42.5%). Factoring in disability benefits eliminated the association between work-related issues and disease activity for all variables except fatigue (r = 0.217; P = 0.03) and discomfort (r = 0.196; P = 0.047). Difficulty fulfilling working hours (ß 2.342, 95% CI 1.413-3.272) and effect on professional advancement (ß 1.426, 95% CI 0.355-2.497) were associated with psychological distress. In the presence of disability benefits, only the effect on professional advancement remained (ß 2.304, 95% CI 0.082-4.527). CONCLUSION: Work-related issues are associated with worse patient-reported outcomes, both physical and psychological.

TNF production in macrophages is genetically determined and regulates inflammatory disease in rats.

Dysregulation of TNF is an important pathophysiological phenotype for many diseases. Recently, certain genetically regulated loci have been identified to regulate several inflammatory diseases. We hypothesized that a region on rat chromosome 4 known to regulate experimental autoimmune encephalomyelitis, experimental arthritis and experimental autoimmune neuritis harbors a gene regulating central inflammatory molecules, such as TNF. We therefore mapped TNF production using linkage analysis in the 12th generation of an advanced intercross line between DA and PVG.AV1 rats, which differ in susceptibility to several inflammatory conditions. A single TNF-regulating quantitative trait locus with a logarithm of odds score of 6.2 was identified and its biological effect was confirmed in a congenic rat strain. The profound TNF regulation mapped in congenic strains to the macrophage population. Several TLR signaling cascades led to the same reduced proinflammatory phenotype in congenic macrophages, indicating control of a convergence point for innate inflammatory activity. The decreased TNF potential and reduced proinflammatory macrophage phenotype in congenic rats was also associated with reduced clinical severity in experimental autoimmune encephalomyelitis, pristane-induced arthritis and sepsis experimental models. Determination of genes and mechanisms involved in this genetically determined TNF regulation will be valuable in understanding disease pathogenesis and aid treatment development.

The Toll-like receptor 7/8-ligand resiquimod (R-848) primes human neutrophils for leukotriene B4, prostaglandin E2 and platelet-activating factor biosynthesis.

Toll-like receptors (TLR) recognize pathogen-associated molecular patterns and play important roles in the innate immune system. While single-stranded viral RNA is the natural ligand of TLR7/TLR8, the imidazoquinoline resiquimod (R-848) is recognized as a potent synthetic agonist of TLR7/TLR8. We investigated the effects of TLR7/8 activation on lipid mediator production in polymorphonuclear leukocytes exposed to R-848. Although R-848 had minimal effects by itself, it strongly enhanced leukotriene B4 formation on subsequent stimulation by fMLP, platelet-activating factor, and the ionophore A23187. R-848 acted via TLR8 but not TLR7 as shown by the lack of effect of the TLR7-specific ligand imiquimod. Priming with R-848 also resulted in enhanced arachidonic acid release and platelet-activating factor formation following fMLP stimulation, as well as enhanced prostaglandin E2 synthesis following the addition of arachidonic acid. Western blot analysis demonstrated that R-848 induced the phosphorylation of the cytosolic phospholipase A2alpha, promoted 5-lipoxygenase translocation and potently stimulated the expression of the type 2 cyclooxygenase. Bafilomycin A1, an inhibitor of endosomal acidification, efficiently inhibited all R-848-induced effects. These studies demonstrate that TLR8 signaling strongly promotes inflammatory lipid mediator biosynthesis and provide novel insights on innate immune response to viral infections.

Serotonin 5-HT2A and 5-HT5A receptors are expressed by different motoneuron populations in rat Onuf's nucleus.

Motoneurons of Onuf's nucleus innervate the pelvic striated muscles, which play a crucial role in erection, ejaculation, and urinary continence. Serotonergic descending projections from the brain are involved in the modulation of Onuf's motoneuron activity. However, conflicting results regarding the effects of spinal serotonin (5-HT) on pelvi-perineal functions have been reported. They may be partly accounted for by the multiplicity of neuronal targets and receptor subtypes on which 5-HT is acting. In order to provide comparative data regarding 5-HT receptor expression in various groups of Onuf's motoneurons, we used retrograde tracing techniques from different pelvic muscles combined with immunocytochemistry of 5-HT2A and 5-HT5A receptors in male and female rats. In males, 5-HT2A receptor immunolabeling was very dense in motoneurons innervating the ischiocavernosus muscle. By contrast, in female rats, 5-HT2A receptor expression in Onuf's nucleus was very weak. In both genders, 5-HT5A receptor immunoreactivity was found in motoneurons innervating the external urethral sphincter. In males, a moderate or low 5-HT5A immunolabeling was observed in motoneurons innervating the bulbospongiosus and ischiocavernosus muscles, respectively. These data show a preferential localization of 5-HT2A and 5-HT5A receptors to motoneurons controlling the striated muscles located at the penile crus and sphincter muscles, respectively, suggesting a specific serotoninergic control on different pelvic functions. In addition, the subcellular distribution of receptors suggests a different mode of action of 5-HT, paracrine at 5-HT2A receptors and synaptic at 5-HT5A receptors. This might have implications for pharmacological research targeting different pelvic functions e.g., micturition and ejaculation.

Expression of Prostaglandin E2 Enzymes in the Synovium of Arthralgia Patients at Risk of Developing Rheumatoid Arthritis and in Early Arthritis Patients.

OBJECTIVE: Arthralgia may precede the development of synovial inflammation in autoantibody-positive individuals at risk of developing rheumatoid arthritis (RA). A major pathway involved in pain is the prostaglandin (PG) E2 pathway. We investigated this pathway in the synovium of individuals with RA-specific autoantibodies and in early arthritis patients. METHODS: Nineteen autoantibody-positive individuals (IgM-rheumatoid factor and/or anti-cyclic citrullinated peptide antibodies) with arthralgia (n=15) and/or a positive family history of RA (n=8), who had been prospectively followed for at least 2 years, were included. In addition, we included early arthritis patients (disease-modifying antirheumatic drug naïve) who after 2 years follow up fulfilled classification criteria for RA (n=63), spondyloarthritis (SpA; n=14), or had unclassified arthritis (UA; n=27). In all subjects we assessed pain and performed synovial biopsy sampling by mini-arthroscopy at baseline. Tissue sections were examined by immunohistochemistry to detect and quantify PGE2 pathway enzymes expression levels (mPGES-1; COX-1 and -2; 15-PGDH). RESULTS: In both study groups synovial expression of PGE2 enzymes was not clearly related to pain sensation. Expression levels at baseline were not associated with the development of arthritis after follow up (6 out of 19 autoantibody-positive individuals). However, in early SpA patients the expression levels of mPGES-1 and COX-1 were significantly increased compared to RA and UA patients. CONCLUSION: Pain in autoantibody-positive individuals without synovial inflammation who are at risk of developing RA and in early arthritis patients may be regulated by pathways other than the PGE2 pathway or originate at sites other than the synovium. In contrast, in SpA, the PGE2 pathway may be inherently linked to the pathophysiology/etiology of the disease.

Limited effect of anti-rheumatic treatment on 15-prostaglandin dehydrogenase in rheumatoid arthritis synovial tissue.

INTRODUCTION: Rheumatoid arthritis (RA) is a chronic inflammatory disease in which prostaglandin E2 (PGE2) displays an important pathogenic role. The enzymes involved in its synthesis are highly expressed in the inflamed synovium, while little is known about 15- prostaglandin dehydrogenase (15-PGDH) that metabolizes PGE2. Here we aimed to evaluate the localization of 15-PGDH in the synovial tissue of healthy individuals or patients with inflammatory arthritis and determine the influence of common RA therapy on its expression. METHODS: Synovial tissue specimens from healthy individuals, psoriatic arthritis, ostheoarthritis and RA patients were immunohistochemically stained to describe the expression pattern of 15-PGDH. In addition, the degree of enzyme staining was evaluated by computer analysis on stained synovial biopsies from two groups of RA patients, before and after RA specific treatment with either intra-articular glucocorticoids or oral methotrexate therapy. Prostaglandins derived from the cyclooxygenase (COX) pathway were determined by liquid-chromatography mass spectrometry in supernatants from interleukin (IL) 1ß-activated fibroblast-like synoviocytes (FLS) treated with methotrexate. RESULTS: 15-PGDH was present in healthy and inflamed synovial tissue, mainly in lining macrophages, fibroblasts and vessels. Intra-articular glucocorticoids showed a trend towards reduced 15-PGDH expression in RA synovium (p = 0.08) while methotrexate treatment left the PGE2 pathway unaltered both in biopsies ex vivo and in cultured FLS. CONCLUSIONS: Early methotrexate therapy has little influence on the expression of 15-PGDH and on any of the PGE2 synthesizing enzymes or COX-derived metabolites. Thus therapeutic strategies involving blocking induced PGE2 synthesis may find a rationale in additionally reducing local inflammatory mediators.

Nucleobindin co-localizes and associates with cyclooxygenase (COX)-2 in human neutrophils.

The inducible cyclooxygenase isoform (COX-2) is associated with inflammation, tumorigenesis, as well as with physiological events. Despite efforts deployed in order to understand the biology of this multi-faceted enzyme, much remains to be understood. Nucleobindin (Nuc), a ubiquitous Ca(2+)-binding protein, possesses a putative COX-binding domain. In this study, we investigated its expression and subcellular localization in human neutrophils, its affinity for COX-2 as well as its possible impact on PGE(2) biosynthesis. Complementary subcellular localization approaches including nitrogen cavitation coupled to Percoll fractionation, immunofluorescence, confocal and electron microscopy collectively placed Nuc, COX-2, and all of the main enzymes involved in prostanoid synthesis, in the Golgi apparatus and endoplasmic reticulum of human neutrophils. Immunoprecipitation experiments indicated a high affinity between Nuc and COX-2. Addition of human recombinant (hr) Nuc to purified hrCOX-2 dose-dependently caused an increase in PGE(2) biosynthesis in response to arachidonic acid. Co-incubation of Nuc with COX-2-expressing neutrophil lysates also increased their capacity to produce PGE(2). Moreover, neutrophil transfection with hrNuc specifically enhanced PGE(2) biosynthesis. Together, these results identify a COX-2-associated protein which may have an impact in prostanoid biosynthesis.

Potentiation of neutrophil cyclooxygenase-2 by adenosine: an early anti-inflammatory signal.

Neutrophils, which are often the first to migrate at inflamed sites, can generate leukotriene B(4) from the 5-lipoxygenase pathway and prostaglandin E(2) through the inducible cyclooxygenase-2 pathway. Adenosine, an endogenous autacoid with several anti-inflammatory properties, blocks the synthesis of leukotriene B(4) while it potentiates the cyclooxygenase-2 pathway in fMLP-treated neutrophils, following activation of the A(2A) receptor. Using the murine air pouch model of inflammation, we observed that inflammatory leukocytes from mice lacking the A(2A) receptor have less cyclooxygenase-2 induction than wild-type animals. In human leukocytes, A(2A) receptor activation specifically elicited potentiation of cyclooxygenase-2 in neutrophils, but not in monocytes. Signal transduction studies indicated that the cAMP, ERK1/2, PI-3K and p38K intracellular pathways are implicated both in the direct upregulation of cyclooxygenase-2 and in its potentiation. Together, these results indicate that neutrophils are particularly important mediators of adenosine's effects. Given the uncontrolled inflammatory phenotype observed in knockout mice and in view of the potent inhibitory actions of prostaglandin E(2) on inflammatory cells, an increased cyclooxygenase-2 expression resulting from A(2A) receptor activation, observed particularly in neutrophils, may take part in an early modulatory mechanism promoting anti-inflammatory activities of adenosine.