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ID PMID Title PublicationDate abstract
21875022 [Safety of rituximab in patients with rheumatoid arthritis]. 2010 RA is a chronic disease and long-term use of treatments that target TNF or B cells will be required for continued disease control. One approach to targeting B cells in RA is the use ofrituximab. It is a genetically engineered chimeric monoclonal antibody that selectively depletes peripheral B lymphocytes by binding CD20 on the cell surface. Long-term safety data show that rituximab treatment is associated with rates of infections and serious infections that remain stable over multiple treatment courses. Also, is associated with rates of malignancy consistent with data from the general RA population and is not associated with an increase in the rate of serious infections in patients who receive subsequent biologic treatment. In conclusion, rituximab is generally safe and well tolerated.
19066176 Golimumab, a human antibody to tumour necrosis factor {alpha} given by monthly subcutaneou 2009 Jun OBJECTIVE: The phase III GO-FORWARD study examined the efficacy and safety of golimumab in patients with active rheumatoid arthritis (RA) despite methotrexate therapy. METHODS: Patients were randomly assigned in a 3 : 3 : 2 : 2 ratio to receive placebo injections plus methotrexate capsules (group 1, n = 133), golimumab 100 mg injections plus placebo capsules (group 2, n = 133), golimumab 50 mg injections plus methotrexate capsules (group 3, n = 89), or golimumab 100 mg injections plus methotrexate capsules (group 4, n = 89). Injections were administered subcutaneously every 4 weeks. The co-primary endpoints were the proportion of patients with 20% or greater improvement in the American College of Rheumatology criteria (ACR20) at week 14 and the change from baseline in the health assessment questionnaire-disability index (HAQ-DI) score at week 24. RESULTS: The proportion of patients who achieved an ACR20 response at week 14 was 33.1% in the placebo plus methotrexate group, 44.4% (p = 0.059) in the golimumab 100 mg plus placebo group, 55.1% (p = 0.001) in the golimumab 50 mg plus methotrexate group and 56.2% (p<0.001) in the golimumab 100 mg plus methotrexate group. At week 24, median improvements from baseline in HAQ-DI scores were 0.13, 0.13 (p = 0.240), 0.38 (p<0.001) and 0.50 (p<0.001), respectively. During the placebo-controlled portion of the study (to week 16), serious adverse events occurred in 2.3%, 3.8%, 5.6% and 9.0% of patients and serious infections occurred in 0.8%, 0.8%, 2.2% and 5.6%, respectively. CONCLUSION: The addition of golimumab to methotrexate in patients with active RA despite methotrexate therapy significantly reduced the signs and symptoms of RA and improved physical function.
19155233 Safety of biological therapies following rituximab treatment in rheumatoid arthritis patie 2009 Dec OBJECTIVE: To assess the safety of biological disease-modifying antirheumatic drugs (DMARD) in rheumatoid arthritis (RA) patients following rituximab. METHODS: RA patients who participated in an international rituximab clinical trial programme were included. Patients who had received one or more rituximab courses and entered safety follow-up (SFU) were permitted additional biological DMARD. Serious infection events (SIE) were collected. RESULTS: Of 185 of 2578 patients who entered SFU and received another biological DMARD, 88.6% had peripheral B-cell depletion at the time of initiation of another biological agent. Thirteen SIE (6.99 events/100 patient-years) occurred following rituximab but before another biological DMARD and 10 SIE (5.49 events/100 patient-years) occurred following another biological DMARD. SIE were of typical type and severity for RA patients. 153 had received one or more tumour necrosis factor inhibitor(s). No fatal or opportunistic infections occurred. CONCLUSIONS: In this analysis, treatment with biological DMARD after rituximab was not associated with an increased serious infection rate. Sample size with limited follow-up restricts definitive conclusions.
19665644 Addition of infliximab compared with addition of sulfasalazine and hydroxychloroquine to m 2009 Aug 8 BACKGROUND: New treatment strategies for early rheumatoid arthritis are evolving rapidly. We aimed to compare addition of conventional disease-modifying antirheumatic drugs (sulfasalazine and hydroxychloroquine) with addition of a tumour necrosis factor antagonist (infliximab) to methotrexate in patients with early rheumatoid arthritis. METHODS: We undertook a randomised trial in 15 rheumatology units in Sweden. We enrolled patients with early rheumatoid arthritis (symptom duration <1 year) and administered methotrexate (up to 20 mg per week). After 3-4 months, those who had not achieved low disease activity but who could tolerate methotrexate were randomly allocated by computer addition of either sulfasalazine and hydroxychloroquine or infliximab. Primary outcome was achievement of a good response according to European League Against Rheumatism (EULAR) criteria at 12 months. Patients were followed up to 24 months; here, we present findings at 12 months. Analysis was by intention to treat and we used non-responder imputation. The Swefot (Swedish Pharmacotherapy) study is registered in the WHO database at the Karolinska University Hospital, number CT20080004. FINDINGS: 487 patients were initially enrolled. Of 258 who had not achieved low disease activity with methotrexate, 130 were allocated sulfasalazine and hydroxychloroquine and 128 were assigned infliximab. 32 of 130 (25%) patients allocated sulfasalazine and hydroxychloroquine achieved the primary outcome compared with 50 of 128 (39%) assigned infliximab (risk ratio 1.59 [95% CI 1.10-2.30], p=0.0160). Adverse events were balanced fairly well between the two groups and accorded with known adverse events of the drugs used. No deaths occurred in either group. INTERPRETATION: In patients with early rheumatoid arthritis in whom methotrexate treatment failed, addition of a tumour necrosis factor antagonist to methotrexate monotherapy is clinically superior to addition of conventional disease-modifying antirheumatic drugs. FUNDING: Swedish Rheumatism Association, Schering-Plough.
20149325 Risk and management of liver toxicity during methotrexate treatment in rheumatoid and psor 2009 Nov OBJECTIVES: To systematically review the literature on liver toxicity in rheumatoid arthritis (RA) and psoriatic arthritis (PsA) patients treated with methotrexate (MTX), as an evidence base for generating clinical practice recommendations for the management of MTX and the indication for a liver biopsy (LB) in case of elevated liver enzymes (LE). METHODS: A systematic literature search was carried out in MEDLINE, EMBASE, Cochrane Library and ACR/EULAR meeting abstracts. Data on the incidence of elevated LE, subsequent adjustments in MTX therapy and the prevalence of fibrosis/cirrhosis in pre-MTX and post-MTX LB were pooled. RESULTS: Forty-seven out of 426 identified references were included in the systematic review. For RA, the incidence rate of elevated LE in the first three years of MTX use was 13/100 patient-years with a cumulative incidence of 31%. MTX was permanently discontinued in 7%, paused or reduced in 26% and continued without any adjustment in 67% of patients with an abnormal test. After 4 years of MTX use, LB showed in 15.3% of the (unrelated) cases mild fibrosis, in 1.3% severe fibrosis and in 0.5% cirrhosis, while pre-MTX biopsies showed 9%, 0.3% and 0.3% abnormalities, respectively. For PsA, evidence is limited. Additional studies suggest that cumulative MTX dose and serial LE elevations among other risk factors are related to liver pathology. CONCLUSIONS: This review suggests that LE elevations during MTX therapy are a frequent but transient problem, that serial abnormal LE tests might be associated with liver pathology, but that cirrhosis is relatively rare. It is, however, not clear from the literature how therapy should be adjusted in case of elevated LE and to what extent MTX independently attributes to liver toxicity.
21125142 The importance of vitamin D levels in autoimmune diseases. 2010 Jan In addition to its role in calcium homeostasis, it is believed that the active form of vitamin D has immunomodulatory effects on cells of the immune system, particularly T lymphocytes, as well as on the production and action of several cytokines. The interaction of vitamin D with the immune system has been the target of a growing number of publications in recent years. Current studies have linked the deficiency of vitamin D with different autoimmune diseases, including insulin-dependent diabetes mellitus (IDDM), multiple sclerosis (MS), inflammatory bowel disease (IBD), systemic lupus erythematosus (SLE), and rheumatoid arthritis (RA). This article reviews the physiology and immunomodulatory role of vitamin D, emphasizing its involvement in rheumatic diseases such as SLE and RA.
20215140 Treating rheumatoid arthritis to target: recommendations of an international task force. 2010 Apr BACKGROUND: Aiming at therapeutic targets has reduced the risk of organ failure in many diseases such as diabetes or hypertension. Such targets have not been defined for rheumatoid arthritis (RA). OBJECTIVE: /st> To develop recommendations for achieving optimal therapeutic outcomes in RA. METHODS: A task force of rheumatologists and a patient developed a set of recommendations on the basis of evidence derived from a systematic literature review and expert opinion; these were subsequently discussed, amended and voted upon by >60 experts from various regions of the world in a Delphi-like procedure. Levels of evidence, strength of recommendations and levels of agreement were derived. RESULTS: The treat-to-target activity resulted in 10 recommendations. The treatment aim was defined as remission with low disease activity being an alternative goal in patients with long-standing disease. Regular follow-up (every 1-3 months during active disease) with appropriate therapeutic adaptation to reach the desired state within 3 to a maximum of 6 months was recommended. Follow-up examinations ought to employ composite measures of disease activity which include joint counts. Additional items provide further details for particular aspects of the disease. Levels of agreement were very high for many of these recommendations (> or =9/10). CONCLUSION: The 10 recommendations are supposed to inform patients, rheumatologists and other stakeholders about strategies to reach optimal outcomes of RA based on evidence and expert opinion.
18751703 The effect of tourniquet use on hidden blood loss in total knee arthroplasty. 2009 Oct The objective of this study was to examine the characteristics of hidden blood loss and assess the effects of using a tourniquet on postoperative hidden loss in patients undergoing primary total knee arthroplasty. Eighty patients were randomised into two groups: one group underwent operation with a tourniquet and one without. Operating time, perioperative blood loss, hidden blood loss, free haemoglobin, swelling, ecchymosis, straight leg raising action and knee flexion were measured. There were significant differences in the hidden blood loss, free haemoglobin, postoperative swelling, extent of ecchymosis, straight leg raising and postoperative knee flexion in the early period after operation between the two groups. Our results indicate that knee arthroplasty operations with a tourniquet might promote postoperative hidden blood loss and hinder patients' in early postoperative rehabilitation exercises.
20047356 Maternal fatigue and its relationship to the caregiving environment. 2009 Dec For women with an autoimmune illness, fatigue can be a debilitating symptom that impacts many aspects of their life. There is scant research on maternal fatigue and its impact on the caregiving environment for either well women or women with chronic illnesses. The objective of this study was to examine the role maternal fatigue played in the caregiving environment, specifically in the mother's experience of the daily hassles of parenting, the discipline style she employed, and how she monitored her child's whereabouts. Two-hundred sixty-two mothers participated in this study: 103 mothers with multiple sclerosis (MS), 68 mothers with rheumatoid arthritis (RA), and a comparison group of 91 well mothers. Mothers completed questionnaires assessing their self-reported levels of fatigue, depression, quality and quantity of sleep, parenting daily hassles, discipline styles, and monitoring. After sleep, depression, and number of children were controlled for, fatigue explained additional variance in predicting monitoring for all three groups of mothers. Fatigue was also a significant predictor of parenting daily hassles for both well mothers and mothers with RA, but not for mothers with MS. For mothers with MS, it was the covariates (i.e., the number of children in the family and sleep quality and quantity) that were predictive of parenting daily hassles. Several explanations for mothers with MS not being as influenced by fatigue are discussed.
19877026 Amelioration of experimental arthritis by a telomerase-dependent conditionally replicating 2009 Nov OBJECTIVE: Synovial fibroblasts (SFs) play a pivotal role in the pathogenesis of rheumatoid arthritis (RA). It has been documented that the phenotype of rheumatoid synovium is similar, in many respects, to that of an aggressive tumor. In this study, a novel, genetically engineered adenovirus was designed to lyse SFs that exhibit high telomerase activity and p53 mutations, and its effects as a novel therapeutic strategy were assessed in an experimental arthritis model. METHODS: An E1B-55-kd-deleted adenovirus driven by the human telomerase reverse transcriptase promoter was constructed (designated Ad.GS1). Cytolysis of SFs and productive replication of Ad.GS1 in the SFs of rats with collagen-induced arthritis (CIA), as well as the SFs of patients with RA (RASFs), were assessed in vitro and in vivo. Treatment responses, as well as the presence of disease-related cytokines and enzymes in the ankle joints, were determined in the murine model. RESULTS: Ad.GS1 replicated in and induced cytolysis of human RASFs and SFs from arthritic rats, but spared normal fibroblasts. Bioluminescence imaging in vivo also demonstrated replication of Ad.GS1 in arthritic rat joints, but not in normal rat joints. Intraarticular administration of Ad.GS1 significantly reduced the ankle circumference, articular index scores, radiographic scores, and histologic scores and decreased the production of interleukin-1beta, matrix metalloproteinase 9, and prolyl 4-hydroxylase in rats with CIA compared with their control counterparts. CONCLUSION: This study is the first to demonstrate the amelioration of arthritic symptoms by a novel, telomerase-dependent adenovirus in the rat CIA model, an experimental model that resembles human RA. In addition, the results suggest that because of its ability to induce cytolysis of SFs, this virus may be further explored as a therapeutic agent in patients with RA.
20398273 Infections requiring hospitalization in the abatacept clinical development program: an epi 2010 INTRODUCTION: Patients with rheumatoid arthritis (RA) have an increased risk of infection and this risk appears to be higher with anti-TNF (tumor necrosis factor) agents. We pooled data from the cumulative abatacept RA clinical development program, both double-blind and open-label periods, to estimate the incidence rates (IRs) of infections requiring hospitalization including pneumonia and opportunistic infections, in comparison with RA patients treated with non-biologic disease-modifying antirheumatic drugs (DMARDs) from several reference cohorts. METHODS: Infections reported in seven abatacept clinical trials of RA patients (double-blind and open-label periods) were tabulated. Comparisons were made between the observed IRs in abatacept-treated patients and those in over 133,000 patients exposed to non-biologic DMARDs in six reference RA cohorts. Age- and sex-adjusted IRs of infections requiring hospitalization, including pneumonia (most frequent hospital infection), were used to estimate the expected IRs with abatacept by the method of indirect adjustment. Standardized incidence ratios (SIR) and 95% CI were calculated comparing incidence in the cumulative abatacept experience with incidence in each RA cohort. RESULTS: A total of 1,955 (double-blind period) and 4,134 (double-blind + open-label periods with a cumulative exposure of 8,392 person-years) abatacept-treated RA patients were analyzed. Observed IRs for infections requiring hospitalization during the double-blind period were 3.05 per 100-patient years for abatacept-treated patients and 2.15 per 100 patient years for placebo. In the cumulative population, observed IR for infections requiring hospitalization was 2.72 per 100-patient years. Rates for abatacept were similar to expected IRs based on other RA non-biologic DMARD cohorts. CONCLUSIONS: IRs of infections requiring hospitalization and pneumonia in abatacept trials are consistent with expected IRs based on reference RA DMARD cohorts. RA patients are at higher risk of infection compared with the general population, making the RA DMARD cohorts an appropriate reference group. The safety of abatacept, including incidence of infections requiring hospitalization, will continue to be monitored in a post-marketing surveillance program.
19953907 [Efficacy and safety of infliximab in patients with rheumatoid arthritis]. 2009 Jul 21 OBJECTIVE: To investigate the efficacy and safety of Infliximab (IFX) plus methotrexate (MTX) combination therapy in patients with rheumatoid arthritis (RA). METHODS: Prospectively observe refractory RA patients who were treated with combination therapy of MTX and IFX. IFX was infused at the dosage of 3 mg/kg, in week 0, 2, 6, and then every 8 weeks. During treatment, clinical variables, disease activity and adverse effects were evaluated. RESULTS: After treatment, 69.8%, 52.4%, 29.5% and 7.2% RA patients achieved ACR20, ACR50, ACR70 and ACR90 respectively. There were significant statistical differences in the changes of swollen joint counts, tender joint counts, VAS scale, patient' s global assessment, and physician's global assessment before and after therapy. CONCLUSION: Infliximab plus MTX achieved significant efficacy and safety in refractory RA patients.
20196869 Urokinase-type plasminogen activator and arthritis progression: role in systemic disease w 2010 INTRODUCTION: Urokinase-type plasminogen activator (u-PA) has been implicated in fibrinolysis, cell migration, latent cytokine activation, cell activation, T-cell activation, and tissue remodeling, all of which are involved in the development of rheumatoid arthritis. Previously, u-PA has been reported to play a protective role in monoarticular arthritis models involving mBSA as the antigen, but a deleterious role in the systemic polyarticular collagen-induced arthritis (CIA) model. The aim of the current study is to determine how u-PA might be acting in systemic arthritis models. METHODS: The CIA model and bone marrow chimeras were used to determine the cellular source of u-PA required for the arthritis development. Gene expression of inflammatory and destructive mediators was measured in joint tissue by quantitiative PCR and protein levels by ELISA. The requirement for u-PA in the type II collagen mAb-induced arthritis (CAIA) and K/BxN serum transfer arthritis models was determined using u-PA(-/-) mice. Neutrophilia was induced in the peritoneal cavity using either ovalbumin/anti-ovalbumin or the complement component C5a. RESULTS: u-PA from a bone marrow-derived cell was required for the full development of CIA. The disease in u-PA(-/-) mice reconstituted with bone marrow from C57BL/6 mice was indistinguishable from that in C57BL/6 mice, in terms of clinical score, histologic features, and protein and gene expression of key mediators. u-PA(-/-) mice were resistant to both CAIA and K/BxN serum transfer arthritis development. u-PA(-/-) mice developed a reduced neutrophilia and chemokine production in the peritoneal cavity following ovalbumin/anti-ovalbumin injection; in contrast, the peritoneal neutrophilia in response to C5a was u-PA independent. CONCLUSIONS: u-PA is required for the full development of systemic arthritis models involving immune complex formation and deposition. The cellular source of u-PA required for CIA is bone marrow derived and likely to be of myeloid origin. For immune complex-mediated peritonitis, and perhaps some other inflammatory responses, it is suggested that the u-PA involvement may be upstream of C5a signaling.
19371261 Angio-oedema in a patient treated with etanercept for rheumatoid arthritis. 2009 Jun In the treatment of rheumatoid arthritis, specific drugs targeting disease-related proinflammatory cytokines such as tumour necrosis factor-alpha have been observed to show a positive impact on the clinical course of the disease. One of these drugs, etanercept, is a recombinant soluble fusion protein of tumour necrosis factor-alpha type 2 receptor. Although it has many well-established side effects, up to date there has not been any report of angio-oedema in the literature. Hence, we aimed to present clinical findings of a 59-year-old female patient who received etanercept for rheumatoid arthritis and developed angio-oedema during treatment, and to the discuss side effects of the drug within the context of current literature.
19723899 Association of the X-chromosomal genes TIMP1 and IL9R with rheumatoid arthritis. 2009 Oct OBJECTIVE: Rheumatoid arthritis (RA) is an inflammatory joint disease with features of an autoimmune disease with female predominance. Candidate genes located on the X-chromosome were selected for a family trio-based association study. METHODS: A total of 1452 individuals belonging to 3 different sample sets were genotyped for 16 single-nucleotide polymorphisms (SNP) in 7 genes. The first 2 sets consisted of 100 family trios, each of French Caucasian origin, and the third of 284 additional family trios of European Caucasian origin. Subgroups were analyzed according to sex of patient and presence of anti-cyclic citrullinated peptide (anti-CCP) autoantibodies. RESULTS: Four SNP were associated with RA in the first sample set and were genotyped in the second set. In combined analysis of sets 1 and 2, evidence remained for association of 3 SNP in the genes UBA1, TIMP1, and IL9R. These were again genotyped in the third sample set. Two SNP were associated with RA in the joint analysis of all samples: rs6520278 (TIMP1) was associated with RA in general (p = 0.035) and rs3093457 (IL9R) with anti-CCP-positive RA patients (p = 0.037) and male RA patients (p = 0.010). A comparison of the results with data from whole-genome association studies further supports an association of RA with TIMPL The sex-specific association of rs3093457 (IL9R) was supported by the observation that men homozygous for rs3093457-CC are at a significantly higher risk to develop RA than women (risk ratio male/female = 2.98; p = 0.048). CONCLUSION: We provide evidence for an association of at least 2 X-chromosomal genes with RA: TIMP1 (rs6520278) and IL9R (rs3093457).
19487267 Real-world anti-tumor necrosis factor treatment in rheumatoid arthritis, psoriatic arthrit 2009 Jul OBJECTIVE: To determine the effectiveness and cost-effectiveness of anti-tumor necrosis factor (anti-TNF) medications in a real-world environment for the treatment of rheumatoid arthritis (RA), psoriatic arthritis (PsA), and ankylosing spondylitis (AS) using the Health Assessment Questionnaire (HAQ). METHODS: We created a database of patients with RA, PsA, or AS treated with anti-TNF agents (etanercept, infliximab, or adalimumab) at a large outpatient rheumatology clinic. Patient characteristics, baseline HAQ prior to treatment, subsequent yearly HAQ, and reasons for termination were collected. The cost based on percentage of patients achieving >or= 0.2 improvement in HAQ (minimal clinically important difference, MCID) was calculated using the 2008 direct cost (Cdn) of the medication. RESULTS: Data were available on 297 patients (206 with RA, 57 PsA, 34 AS). The mean age was 55 years, with 12 years of disease, and the mean baseline HAQ (standard error, SE) was 1.37 (0.04). The changes in HAQ (SE) at Years 1, 2, and 3 were -0.31 (0.04), -0.24 (0.06), and -0.27 (0.07) for annual cost to achieve MCID of $41,636, $42,077, and $42,147, respectively. The number needed to treat (NNT) was 1.94 (RA), 1.88 (PsA), and 2.30 (AS). There were no statistical differences between the diseases studied. CONCLUSION: We obtained data on the effectiveness and cost-effectiveness of anti-TNF drugs using the HAQ score, which is known to be an excellent predictor of work disability, morbidity, and mortality. HAQ scores decreased with treatment and were sustained throughout the 3-5 years of followup. The NNT of approximately 2 seems favorable and was similar between diseases.
19448496 Update on rheumatology: part 1. 2009 May There are many rheumatic diseases. Part 1 of this 2 part series on rheumatology presented a few of those most commonly seen in the community. Home health clinicians can be helpful in managing these diseases and preventing progression by watching for new symptoms or acute attacks of pain or disability, ensuring that patients take their medications appropriately, reminding patients to see their rheumatology providers and have their lab work done regularly, and reporting adverse effects to medications promptly. Additionally, as with most home health patients, an interdisciplinary approach that includes physical and occupational therapy, social work, nursing, nutrition, and other disciplines as needed should be implemented so that all patient needs are met and the patient is discharged at the highest level of self-care that is possible. Part 2 of this series will discuss the care of the patient with rheumatic disease at home and will provide a more in-depth look at lab diagnosis of rheumatic diseases.
20032100 Vitamin D status and its associations with disease activity and severity in African Americ 2010 Feb OBJECTIVE: To examine the prevalence of vitamin D insufficiency and the associations of vitamin D concentration with disease status in African Americans with rheumatoid arthritis (RA). METHODS: Study participants (n = 266) were enrolled in the Consortium for the Longitudinal Evaluation of African Americans with Early RA (CLEAR) Registry. The vitamin 25(OH)-D was measured on baseline plasma, and associations of 25(OH)-D with disease status (baseline and at 3 years' disease duration) were examined using univariate and multivariate regression. RESULTS: The prevalence of 25(OH)-D insufficiency (
20556357 What have we learned from LCS mobile-bearing knee system? 2010 Oct Three hundred and sixty-four low contact stress (LCS) total knee arthroplasties that could be followed up for more than 5 years were clinically and radiographically analyzed. The median postoperative Hospital for Special Surgery score improved from 56 (range 32-77) to 91 (range 64-100) points, but median range of motion did not change from 120° (range 50°-135°) to 120° (range 85°-135°). Complications occurred in 16 cases (4%), and included postoperative polyethylene dislocation and intraoperative tibial condylar fracture, while five knees (1%) required revision surgery due to mechanical reasons. The overall prosthesis survival rate was 91% at 12 years. Although the LCS mobile-bearing knee system has theoretical advantages in terms of wear and loosening, the problem of polyethylene dislocation, intraoperative tibial fracture, and radiolucent lines should be solved for long survival. The clinical relevance of this study is that the LCS system provided good clinical and survival results.
20656922 Nonredundant roles for leukotriene B4 receptors BLT1 and BLT2 in inflammatory arthritis. 2010 Sep 1 Lipid mediators derived from arachidonic acid through the cyclooxygenase and lipoxygenase pathways are known to be important mediators of inflammation. Studies in mouse models demonstrated an important role for the high-affinity leukotriene B(4) receptor BLT1 in arthritis, atherosclerosis, and asthma. BLT2, a low-affinity leukotriene B(4) receptor, was also shown to be a high-affinity receptor for cyclooxygenase-1 derived 12(S)-hydroxyheptadeca-5Z, 8E, 10E-trienoic acid. However, its biochemical activities and physiological roles remain unknown. In this study, we developed mice deficient in BLT2 by targeted disruption. The BLT2(-/-) mice developed normally, and analysis of immune cells showed that disruption of BLT2 did not alter BLT1 expression or function. Mast cells from the C57BL/6 mice but not from the BLT2(-/-) mice showed intracellular calcium mobilization in response to 12(S)-hydroxyheptadeca-5Z, 8E, 10E-trienoic acid. In an autoantibody-induced inflammatory arthritis model, the BLT2(-/-) mice showed reduced incidence and severity of disease, including protection from bone and cartilage loss. Reciprocal bone marrow transplant experiments identified that loss of BLT2 expression on a bone marrow-derived cell lineage offers protection against severe disease. Thus, BLT2, a unique receptor for 5-lipoxygenase- and cyclooxygenase-1-derived lipid mediators, represents a novel target for therapies directed at treating inflammation associated with arthritis.