C-terminal citrullinated peptide alters antigen-specific APC:T cell interactions leading to breach of immune tolerance.

In rheumatoid arthritis, the emergence of anti-citrullinated autoimmunity is associated with HLA-antigen-T cell receptor complexes. The precise mechanisms underpinning this breach of tolerance are not well understood. Porphyromonas gingivalis expresses an enzyme capable of non-endogenous C-terminal citrullination with potential to generate citrullinated autoantigens. Here we document how C-terminal citrullination of ovalbumin peptide323-339 alters the interaction between antigen-presenting cells and OTII T cells to induce functional changes in responding T cells. These data reveal that C-terminal citrullination is sufficient to breach T cell peripheral tolerance in vivo and reveal the potential of C-terminal citrullination to lower the threshold for T cell activation. Finally, we demonstrate a role for the IL-2/STAT5/CD25 signalling axis in breach of tolerance. Together, our data identify a tractable mechanism and targetable pathways underpinning breach of tolerance in rheumatoid arthritis and provide new conceptual insight into the origins of anti-citrullinated autoimmunity.

Stratification of alopecia areata reveals involvement of CD4 T cell populations and altered faecal microbiota.

Alopecia areata (AA) is an immune-mediated disease that causes non-scarring hair loss. Autoreactive CD8 T cells are key pathogenic effectors in the skin, and AA has been associated both with atopy and with perturbations in intestinal homeostasis. This study aimed to investigate mechanisms driving AA by characterizing the circulating immunophenotype and faecal microbiome, and by stratifying AA to understand how identified signatures associated with heterogeneous clinical features of the condition. Flow cytometric analyses identified alterations in circulating B cells and CD4 T cells, while 16S sequencing identified changes in alpha and beta diversity in the faecal microbiome in AA. The proportions of transitional and naïve B cells were found to be elevated in AA, particularly in AA samples from individuals with >50% hair loss and those with comorbid atopy, which is commonly associated with extensive hair loss. Although significant changes in circulating CD8 T cells were not observed, we found significant changes in CD4+ populations. In individuals with <50% hair loss higher frequencies of CCR6+CD4 ("Th17") and CCR6+CXCR3+CD4 ("Th1/17") T cells were found. While microbial species richness was not altered, AA was associated with reduced evenness and Shannon diversity of the intestinal microbiota, again particularly in those with <50% hair loss. We have identified novel immunological and microbial signatures in individuals with alopecia areata. Surprisingly, these are associated with lower levels of hair loss, and may therefore provide a rationale for improved targeting of molecular therapeutics.

Efficacy of secukinumab and adalimumab in patients with psoriatic arthritis and concomitant moderate-to-severe plaque psoriasis: results from EXCEED, a randomized, double-blind head-to-head monotherapy study.

BACKGROUND: Secukinumab [an interleukin (IL)-17A inhibitor] has demonstrated significantly higher efficacy vs. etanercept (a tumour necrosis factor inhibitor) and ustekinumab (an IL-12/23 inhibitor) in patients with moderate-to-severe plaque psoriasis. OBJECTIVES: To report 52-week results from a prespecified analysis of patients with active psoriatic arthritis (PsA) having concomitant moderate-to-severe plaque psoriasis from the head-to-head EXCEED monotherapy study comparing secukinumab with adalimumab. METHODS: Patients were randomized to receive secukinumab 300 mg via subcutaneous injection at baseline, week 1-4, and then every 4 weeks until week 48 or adalimumab 40 mg via subcutaneous injection every 2 weeks from baseline until week 50. Assessments in patients with concomitant moderate-to-severe psoriasis, defined as having affected body surface area > 10% or Psoriasis Area and Severity Index (PASI) ≥ 10 at baseline, included musculoskeletal, skin and quality-of-life outcomes. Missing data were handled using multiple imputation. RESULTS: Of the 853 patients [secukinumab (N = 426), adalimumab (N = 427)], 211 (24·7%) had concomitant moderate-to-severe psoriasis [secukinumab (N = 110, 25·8%), adalimumab (N = 101, 23·7%)]. Up to week 50, 5·5% of patients discontinued secukinumab vs.17·8% in the adalimumab group. The proportion of patients who achieved American College of Rheumatology (ACR) 20 response was 76·4% with secukinumab vs. 68·3% with adalimumab (P = 0·175), PASI 100 response was 39·1% vs. 23·8% (P = 0·013), and simultaneous improvement in ACR 50 and PASI 100 response at week 52 was 28·2% vs. 17·7%, respectively (P = 0·06). Secukinumab demonstrated consistently higher responses vs. adalimumab across skin endpoints. CONCLUSIONS: This prespecified analysis in PsA patients with concomitant moderate-to-severe plaque psoriasis in the EXCEED study provides further evidence that IL-17 inhibitors offer a comprehensive biological treatment to manage the concomitant features of psoriasis and PsA.

Alopecia areata is characterized by dysregulation in systemic type 17 and type 2 cytokines, which may contribute to disease-associated psychological morbidity.

BACKGROUND: Alopecia areata (AA) is a common autoimmune disease, causing patchy hair loss that can progress to involve the entire scalp (totalis) or body (universalis). CD8+ NKG2D+ T cells dominate hair follicle pathogenesis, but the specific mechanisms driving hair loss are not fully understood. OBJECTIVES: To provide a detailed insight into the systemic cytokine signature associated with AA, and to assess the association between cytokines and depression. METHODS: We conducted multiplex analysis of plasma cytokines from patients with AA, patients with psoriatic arthritis (PsA) and healthy controls. We used the Hospital Anxiety and Depression Scale (HADS) to assess the occurrence of depression and anxiety in our cohort. RESULTS: Our analysis identified a systemic inflammatory signature associated with AA, characterized by elevated levels of interleukin (IL)-17A, IL-17F, IL-21 and IL-23 indicative of a type 17 immune response. Circulating levels of the type 2 cytokines IL-33, IL-31 and IL-17E (IL-25) were also significantly increased in AA. In comparison with PsA, AA was associated with higher levels of IL-17F, IL-17E and IL-23. We hypothesized that circulating inflammatory cytokines may contribute to wider comorbidities associated with AA. Our assessment of psychiatric comorbidity in AA using HADS scores showed that 18% and 51% of people with AA experienced symptoms of depression and anxiety, respectively. Using linear regression modelling, we identified that levels of IL-22 and IL-17E are positively and significantly associated with depression. CONCLUSIONS: Our data highlight changes in both type 17 and type 2 cytokines among people with AA, suggesting that complex systemic cytokine profiles may contribute both to the pathogenesis of AA and to the associated depression. What's already known about this topic? NKG2D+ CD8+ T cells cause hair loss in alopecia areata (AA) but the immunological mechanisms underlying the disease are not fully understood. AA is associated with changes in levels of interleukin (IL)-6, tumour necrosis factor-α, IL-1ß and type 17 cytokines. Psychiatric comorbidity is common among people with AA. What does this study add? People with AA have increased plasma levels of the type 2 cytokines IL-33, IL-31 and IL-17E (IL-25), in addition to the type 17 cytokines IL-17A, IL-21, IL-23 and IL-17F. Levels of IL-17E and IL-22 positively predict depression score. What is the translational message? AA is associated with increased levels of multiple inflammatory cytokines, implicating both type 17- and type 2 immune pathways. Our data indicate that therapeutic strategies for treating AA may need to address the underlying type 17- and type 2 immune dysregulation, rather than focusing narrowly on the CD8+ T-cell response. An immunological mechanism might contribute directly to the depression observed in people with AA.

Immunoglobulin A antibodies to oxidized collagen type II as a potential biomarker for the stratification of spondyloarthritis from rheumatoid arthritis.

OBJECTIVES: The discovery of diseased tissue-specific neoantigens offers the opportunity to develop important disease tissue-specific biomarkers that can help in the prediction, diagnosis, and stratification of diseases. This opportunity is specifically significant for autoimmune diseases where diagnostic biomarkers are not available. Inflammatory autoimmune diseases are commonly associated with local generation of large amounts of reactive oxidants. We have previously identified oxidative post-translationally modified (oxPTM) tissue-specific neoantigens in rheumatoid arthritis (RA) and type 1 diabetes that elicit an immune response. In the current study, we studied the presence and clinical significance of antibodies to oxPTM collagen type II (CII) in patients with spondyloarthritis (SpA). METHOD: Levels of antibodies specific to native CII and oxPTM-CII were assessed by enzyme-linked immunosorbent assay. RESULTS: Immunoglobulin G (IgG) binding to oxPTM-CII was observed in 52%, 83%, and 28% of serum samples from patients with axial spondyloarthritis (axSpA), RA, and psoriatic arthritis (PsA), respectively. Importantly, while strong IgA anti-oxPTM-CII responses were detected in axSpA and PsA patients, with 47% and 84% respective binders, no IgA anti-oxPTM-CII was detected in RA patients. IgA anti-oxPTM-CII reactivity in axSpA patients treated with biologics was higher and more frequent, with 85% binders compared to 9% binders in patients treated with synthetic disease-modifying anti-rheumatic drugs. CONCLUSION: Our data imply that SpA and PsA are associated with the presence of antibodies to oxPTM-CII, suggesting that there may be a humoral component that may distinguish patients with SpA from RA. Our approach could be adapted to other diseases, particularly to inflammatory autoimmune diseases.

Driving chronicity in rheumatoid arthritis: perpetuating role of myeloid cells.

Acute inflammation is a complex and tightly regulated homeostatic process that includes leucocyte migration from the vasculature into tissues to eliminate the pathogen/injury, followed by a pro-resolving response promoting tissue repair. However, if inflammation is uncontrolled as in chronic diseases such as rheumatoid arthritis (RA), it leads to tissue damage and disability. Synovial tissue inflammation in RA patients is maintained by sustained activation of multiple inflammatory positive-feedback regulatory pathways in a variety of cells, including myeloid cells. In this review, we will highlight recent evidence uncovering biological mechanisms contributing to the aberrant activation of myeloid cells that contributes to perpetuation of inflammation in RA, and discuss emerging data on anti-inflammatory mediators contributing to sustained remission that may inform a novel category of therapeutic targets.

JAK Inhibitors in Rheumatology: Implications for Paediatric Syndromes?

PURPOSE OF REVIEW: Given the recent increase in the profile and use of Janus kinase inhibitors (JAKinibs) in adult patients with rheumatic diseases, we aimed to review the current evidence accruing for use in paediatric rheumatology patients. RECENT FINDINGS: Significant advances have been made in the management of rheumatic diseases in the past two decades. The introduction of biologic agents in both adults and children has provided significant improvements to patient outcomes and led to better quality of life. Moreover, responses to similar agents allude to common effector pathways operating across juvenile and adult synovitis especially. However, inefficacy and intolerance of these agents leads to a subset of children with limited treatment options. Since 2012, Janus kinase (JAK) inhibitors (JAKinibs), a novel group of oral small molecule inhibitors, have demonstrated their efficacy in several forms of adult inflammatory arthritis, such as rheumatoid arthritis (RA) and psoriatic arthritis (PsA). There are hopes that these successes will be transferable to the paediatric population. In the following review, we discuss the development and progress of JAKinibs in this regard.

EULAR recommendations for cardiovascular disease risk management in patients with rheumatoid arthritis and other forms of inflammatory joint disorders: 2015/2016 update.

Patients with rheumatoid arthritis (RA) and other inflammatory joint disorders (IJD) have increased cardiovascular disease (CVD) risk compared with the general population. In 2009, the European League Against Rheumatism (EULAR) taskforce recommended screening, identification of CVD risk factors and CVD risk management largely based on expert opinion. In view of substantial new evidence, an update was conducted with the aim of producing CVD risk management recommendations for patients with IJD that now incorporates an increasing evidence base. A multidisciplinary steering committee (representing 13 European countries) comprised 26 members including patient representatives, rheumatologists, cardiologists, internists, epidemiologists, a health professional and fellows. Systematic literature searches were performed and evidence was categorised according to standard guidelines. The evidence was discussed and summarised by the experts in the course of a consensus finding and voting process. Three overarching principles were defined. First, there is a higher risk for CVD in patients with RA, and this may also apply to ankylosing spondylitis and psoriatic arthritis. Second, the rheumatologist is responsible for CVD risk management in patients with IJD. Third, the use of non-steroidal anti-inflammatory drugs and corticosteroids should be in accordance with treatment-specific recommendations from EULAR and Assessment of Spondyloarthritis International Society. Ten recommendations were defined, of which one is new and six were changed compared with the 2009 recommendations. Each designated an appropriate evidence support level. The present update extends on the evidence that CVD risk in the whole spectrum of IJD is increased. This underscores the need for CVD risk management in these patients. These recommendations are defined to provide assistance in CVD risk management in IJD, based on expert opinion and scientific evidence.

European League Against Rheumatism (EULAR) recommendations for the management of psoriatic arthritis with pharmacological therapies: 2015 update.

BACKGROUND: Since the publication of the European League Against Rheumatism recommendations for the pharmacological treatment of psoriatic arthritis (PsA) in 2012, new evidence and new therapeutic agents have emerged. The objective was to update these recommendations. METHODS: A systematic literature review was performed regarding pharmacological treatment in PsA. Subsequently, recommendations were formulated based on the evidence and the expert opinion of the 34 Task Force members. Levels of evidence and strengths of recommendations were allocated. RESULTS: The updated recommendations comprise 5 overarching principles and 10 recommendations, covering pharmacological therapies for PsA from non-steroidal anti-inflammatory drugs (NSAIDs), to conventional synthetic (csDMARD) and biological (bDMARD) disease-modifying antirheumatic drugs, whatever their mode of action, taking articular and extra-articular manifestations of PsA into account, but focusing on musculoskeletal involvement. The overarching principles address the need for shared decision-making and treatment objectives. The recommendations address csDMARDs as an initial therapy after failure of NSAIDs and local therapy for active disease, followed, if necessary, by a bDMARD or a targeted synthetic DMARD (tsDMARD). The first bDMARD would usually be a tumour necrosis factor (TNF) inhibitor. bDMARDs targeting interleukin (IL)12/23 (ustekinumab) or IL-17 pathways (secukinumab) may be used in patients for whom TNF inhibitors are inappropriate and a tsDMARD such as a phosphodiesterase 4-inhibitor (apremilast) if bDMARDs are inappropriate. If the first bDMARD strategy fails, any other bDMARD or tsDMARD may be used. CONCLUSIONS: These recommendations provide stakeholders with an updated consensus on the pharmacological treatment of PsA and strategies to reach optimal outcomes in PsA, based on a combination of evidence and expert opinion.

Ultrasound-guided synovial biopsy: a safe, well-tolerated and reliable technique for obtaining high-quality synovial tissue from both large and small joints in early arthritis patients.

OBJECTIVE: To determine the tolerability, safety and yield of synovial tissue in an early arthritis cohort using a minimally invasive, ultrasound (US)-guided, synovial biopsy technique in small, medium and large joints. METHODS: 93 sequential biopsy procedures were assessed from a total of 57 patients (baseline and 36 repeat biopsies at 6 months) recruited as part of the 'Pathobiology of Early Arthritis Cohort' study. Patients completed a tolerability questionnaire prior to and following the synovial biopsy procedure. The synovial biopsy was performed under US guidance with US images of the joint recorded prior to each procedure. Synovial tissue was harvested for immunohistochemistry and RNA extraction. RESULTS: Five different joint sites were biopsied (knee, elbow, wrist, metacarpal phalangeal and proximal interphalangeal). No significant complications were reported following the procedure. No difference in pain, swelling and stiffness of the biopsied joint from before and after the procedure was demonstrated. A median of 14 biopsy samples was retrieved from each procedure with 93% of biopsy procedures yielding good quality tissue. RNA yield was good in all joints and in repeat biopsies. Multivariant analysis demonstrated a significantly greater yield of RNA and graded tissue in relation to a high prebiopsy, grey-scale synovitis score (0-3, semiquantitative). CONCLUSIONS: A minimally invasive approach to synovial tissue harvesting, using US guidance, is both safe and well-tolerated by patients. Tissue quality/RNA yield is preserved in subsequent biopsies following therapeutic intervention. A high US grey-scale synovitis score is a predictor of good quality/quantity of tissue and RNA.

Achilles tendon biomechanics in psoriatic arthritis patients with ultrasound proven enthesitis.

OBJECTIVE: To investigate Achilles tendon (AT) biomechanics in psoriatic arthritis (PsA) patients with ultrasound confirmed features of enthesitis. METHOD: PsA patients and healthy control subjects underwent three-dimensional (3D) gait analysis to measure walking speed, rotational joint motion and the moments, power, and AT force at the ankle-subtalar joint complex. The Glasgow Ultrasound Enthesitis Scoring System (GUESS) was used to score the presence of enthesophytes, erosions, retrocalcaneal bursitis, and tendon thickening. Power Doppler ultrasound signal (PDUS) was used to detect active disease. Peripheral joint arthritis, acute-phase reactants, global health, disability, and foot impairments were recorded. A core set of biomechanical variables that influence the insertion of the AT and indirect estimates of tendon loading were compared between PsA patients and control subjects with and without enthesitis. RESULTS: Forty-two PsA patients with a mean disease duration of 10.6 (SD 9.4) years and 29 control subjects were studied. Seventeen (40%) PsA patients had clinically detectable AT entheseal pain. Twenty-eight (67%) PsA patients and nine (31%) control subjects had one or more GUESS enthesitis features, predominantly enthesophytes. PsA patients with enthesitis walked significantly more slowly than control subjects (p = 0.019) and generated lower peak ankle joint moments (p = 0.006), power (p = 0.001), and AT force (p = 0.003). Ankle-subtalar joint complex motion was comparable and no between-group differences were found for peak dorsiflexion (p = 0.59), eversion (p = 0.05), and internal rotation (p = 0.19). CONCLUSIONS: In this group of PsA patients, the AT insertional angle was not influenced by ankle-subtalar joint motion in those with and without enthesitis. Moreover, the PsA patients with enthesitis had significantly lower AT loading.

Abatacept modulates proinflammatory macrophage responses upon cytokine-activated T cell and Toll-like receptor ligand stimulation.

OBJECTIVES: We investigated whether Abatacept might reduce proinflammatory cytokine production by macrophages upon contact with cytokine activated T cells and/or stimulation with TLR ligands. METHODS: Macrophages and cytokine stimulated T cells (Tck) were added together in the presence of Abatacept or a control Ig, with or without TLR ligands. The production of cytokines was determined by luminex. RESULTS: Abatacept reduced Tck-induced production of TNFa by macrophages. Tck and TLR ligands synergistically induced the production of proinflammatory cytokines by macrophages, especially IL-12p70. The production of IL-12p70 coincided with the production of IFNg, which were both reduced in the presence of Abatacept. CONCLUSIONS: Tck induce the production of TNFa by macrophages and facilitate the highly increased production of proinflammatory cytokines in the presence of TLR ligands. Abatacept was shown to potently suppress these pathways suggesting that its role may extend beyond antigen specific T cell mediated effector function.

PAR(2) expression in peripheral blood monocytes of patients with rheumatoid arthritis.

OBJECTIVES: Proteinase-activated receptor 2 (PAR(2)) is a G protein-coupled receptor activated by serine proteinases with proinflammatory activity. A study was undertaken to investigate the presence and functional significance of PAR(2) expression on rheumatoid arthritis (RA)-derived leucocyte subsets. METHODS: Venous blood was obtained from patients with RA and osteoarthritis (OA) as well as healthy control subjects. Surface expression of PAR(2) on peripheral blood mononuclear cells (PBMCs) was analysed by flow cytometry and interleukin 6 (IL-6) generation by ELISA. RESULTS: Patients with RA had elevated but variable surface expression of PAR(2) on CD14+ monocytes compared with control subjects (median (1st to 3rd quartiles) 1.76% (0.86-4.10%) vs 0.06% (0.03-0.81%), p<0.0001). CD3+ T cells showed a similar pattern with significantly higher PAR(2) expression in patients with RA compared with controls (3.05% (0.36-11.82%) vs 0.08% (0.02-0.28%), p<0.0001). For both subsets, PAR(2) expression was significantly higher (p<0.00001) in patients with high levels of disease activity: PAR(2) expression for both CD14+ and CD3+ cells correlated to C reactive protein and erythrocyte sedimentation rate. Furthermore, in a cohort of patients with newly diagnosed RA, elevated PAR(2) expression in both CD14+ and CD3+ cells was significantly reduced 3 months after methotrexate or sulfasalazine treatment and this reduction correlated significantly with the reduction in the 28-joint Disease Activity Scale score (p<0.05). PAR(2) expression on cells from patients with OA was low, similar to levels seen in control subjects. Generation of IL-6 by monocytes in response to a selective PAR(2) agonist was significantly greater in patients with RA than in patients with OA and control subjects (p<0.05). CONCLUSIONS: These findings are consistent with a pathogenic role for PAR(2) in RA.

European League Against Rheumatism recommendations for the management of psoriatic arthritis with pharmacological therapies.

BACKGROUND: Psoriatic arthritis (PsA) is a clinically heterogeneous disease. Clear consensual treatment guidance focused on the musculoskeletal manifestations of PsA would be advantageous. The authors present European League Against Rheumatism (EULAR) recommendations for the treatment of PsA with systemic or local (non-topical) symptomatic and disease-modifying antirheumatic drugs (DMARD). METHODS: The recommendations are based on evidence from systematic literature reviews performed for non-steroidal anti-inflammatory drugs (NSAID), glucocorticoids, synthetic DMARD and biological DMARD. This evidence was discussed, summarised and recommendations were formulated by a task force comprising 35 representatives, and providing levels of evidence, strength of recommendations and levels of agreement. RESULTS: Ten recommendations were developed for treatment from NSAID through synthetic DMARD to biological agents, accounting for articular and extra-articular manifestations of PsA. Five overarching principles and a research agenda were defined. CONCLUSION: These recommendations are intended to provide rheumatologists, patients and other stakeholders with a consensus on the pharmacological treatment of PsA and strategies to reach optimal outcomes, based on combining evidence and expert opinion. The research agenda informs directions within EULAR and other communities interested in PsA.

Interleukin-33: a novel mediator with a role in distinct disease pathologies.

Interleukin-33 (IL-33) is a novel member of IL-1 cytokine family. It can act both as a nuclear factor and as a soluble mediator; however, the precise role of IL-33 within the nucleus is still not clear. As a cytokine, IL-33 is suggested to function as an alarmin that is released upon endothelial or epithelial cell damage. As such, IL-33 targets multiple cell types thereby alerting the immune system to endogenous trauma such as physical stress or infection. However, a dysregulated release of IL-33 has a potential to drive distinct pathologies. In this review, we discuss the contribution of IL-33 to the pathophysiology of asthma, arthritis, obesity and atherosclerosis as well as the potential of IL-33 for therapeutic intervention.

Interleukin-15 mediates T cell-dependent regulation of tumor necrosis factor-alpha production in rheumatoid arthritis.

Tumor necrosis factor-alpha occupies a central role in rheumatoid arthritis (RA) pathogenesis. We now report that interleukin-15 (IL-15) can induce TNF-alpha production in RA through activation of synovial T cells. Peripheral blood (PB) T cells activated by IL-15 induced significant TNF-alpha production by macrophages via a cell-contact-dependent mechanism. Freshly isolated RA synovial T cells possessed similar capability, and in vitro, IL-15 was necessary to maintain this activity. IL-15 also induced direct TNF-alpha production by synovial T cells. In contrast, IL-2 induced significantly lower TNF-alpha production in either cell-contact-dependent or direct culture, and IL-8 and MIP-1 alpha were ineffective. Antibodies against CD69, LFA-1 or ICAM-1 significantly inhibited the ability of T cells to activate macrophages by cell contact.

The role of interleukin-15 in T-cell migration and activation in rheumatoid arthritis.

Interleukin 15 (IL-15) is a novel cytokine with interleukin-2-like activity. It is also a potent T-lymphocyte chemoattractant. Rheumatoid arthritis (RA) is a chronic inflammatory disease characterized by the presence of activated T lymphocytes, macrophages and synoviocytes in the synovial membrane. The mechanisms of T-cell activation in RA are currently unclear. We report the presence of high concentrations of IL-15 in rheumatoid arthritis (RA) synovial fluid and have demonstrated its expression in the synovial membrane lining layer by immunohistochemistry. RA synovial fluids were found to contain chemotactic activity, which was attributable in part to the presence of IL-15. Moreover, in a murine model, injection of recombinant IL-15 was found to induce a local tissue inflammatory infiltrate consisting predominantly of T lymphocytes. Synovial fluid T lymphocytes proliferate in response to IL-15, demonstrating that continued responsiveness to IL-15 is a feature of T cells after entry into the synovial compartment. These data suggest that IL-15 can recruit and activate T lymphocytes in the synovial membrane, thereby contributing to RA pathogenesis.

Thymosin beta 4 sulfoxide is an anti-inflammatory agent generated by monocytes in the presence of glucocorticoids.

The possibility that glucocorticoids upregulate the expression of anti-inflammatory mediators is an exciting prospect for therapy in inflammatory diseases, because these molecules could give the therapeutic benefits of steroids without toxic side effects. Supernatants from monocytes and macrophages cultured in the presence of glucocorticoids increase the dispersion of neutrophils from a cell pellet in the capillary tube migration assay. This supernatant factor, unlike other neutrophil agonists, promotes dispersive locomotion of neutrophils at uniform concentration, lowers their adhesion to endothelial cells, inhibits their chemotactic response to fMLP and induces distinctive morphological changes. Here we show that thymosin beta4 sulfoxide is generated by monocytes in the presence of glucocorticoids and acts as a signal to inhibit an inflammatory response. In vitro, thymosin beta4 sulfoxide inhibited neutrophil chemotaxis, and in vivo, the oxidized peptide, but not the native form, was a potent inhibitor of carrageenin-induced edema in the mouse paw. Thymosin beta4 is unique, because oxidation attenuates its intracellular G-actin sequestering activity, but greatly enhances its extracellular signaling properties. This description of methionine oxidation conferring extracellular function on a cytosolic protein may have far-reaching implications for future strategies of anti-inflammatory therapy.

Production of nitric oxide in the synovial membrane of rheumatoid and osteoarthritis patients.

We have demonstrated spontaneous nitric oxide (NO) production by primary synovial cultures from rheumatoid (RA) and osteoarthritis patients. Increased NO production followed addition of staphylococcal enterotoxin B. Immunochemical double staining with specific anti-human inducible NO synthase (iNOS) and nonspecific esterase (NSE), or anti-CD68 (markers for tissue macrophages) showed that although many lining layer cells in RA synovium expressed iNOS, most (approximately 90%) were NSE- and CD68-, with only a minor population (approximately 10%) which were iNOS+, CD68+/NSE+. These data demonstrate the capacity for high output of NO by human synovial tissue and show that, although human macrophages can express high levels of iNOS, the majority of cells expressing iNOS are fibroblasts. We also report that synoviocytes, and macrophage cell lines, cultured with the NO donor, S-nitroso-acetyl penicillamine, produced high concentrations of tumor necrosis factor (TNF)-alpha. These results suggest that NO may mediate pathology in RA through the induction of TNF-alpha production.

Selective expression and functions of interleukin 18 receptor on T helper (Th) type 1 but not Th2 cells.

Interleukin (IL)-18 induces interferon (IFN)-gamma synthesis and synergizes with IL-12 in T helper type 1 (Th1) but not Th2 cell development. We report here that IL-18 receptor (IL-18R) is selectively expressed on murine Th1 but not Th2 cells. IL-18R mRNA was expressed constitutively and consistently in long-term cultured clones, as well as on newly polarized Th1 but not Th2 cells. IL-18 sustained the expression of IL-12Rbeta2 mRNA, indicating that IL-18R transmits signals that maintain Th1 development through the IL-12R complex. In turn, IL-12 upregulated IL-18R mRNA. Antibody against an IL-18R-derived peptide bound Th1 but not Th2 clones. It also labeled polarized Th1 but not Th2 cells derived from naive ovalbumin-T cell antigen receptor-alphabeta transgenic mice (D011.10). Anti-IL-18R antibody inhibited IL-18- induced IFN-gamma production by Th1 clones in vitro. In vivo, anti-IL-18R antibody reduced local inflammation and lipopolysaccharide-induced mortality in mice. This was accompanied by shifting the balance from Th1 to Th2 responses, manifest as decreased IFN-gamma and proinflammatory cytokine production and increased IL-4 and IL-5 synthesis. Therefore, these data provide a direct mechanism for the selective effect of IL-18 on Th1 but not Th2 cells. They also show that the synergistic effect of IL-12 and IL-18 on Th1 development may be due to the reciprocal upregulation of their receptors. Furthermore, IL-18R is a cell surface marker distinguishing Th1 from Th2 cells and may be a therapeutic target.