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ID PMID Title PublicationDate abstract
17133250 Drug Insight: abatacept for the treatment of rheumatoid arthritis. 2006 Dec Although the development of tumor necrosis factor antagonists has improved the clinical outcome of many patients with rheumatoid arthritis (RA), some patients fail to respond to these drugs or have contraindications preventing their use. Other approaches for treating this disease are, therefore, keenly sought. As T cells promote numerous disease pathways in RA, these cells are a logical target for anti-inflammatory therapy. One of the approaches being investigated involves targeting the co-stimulatory signals that accompany antigen-derived signals involved in the activation of T cells. Abatacept is a recombinant fusion protein that interrupts the T-cell co-stimulatory signal mediated through the CD28-CD80/CD86 pathway. Several clinical trials have now confirmed the efficacy of this compound in the treatment of RA. This article discusses the proposed mechanism of action of abatacept and reviews the data from phase II and phase III clinical trials on the safety and efficacy of this drug in RA.
16826237 Extensive multiallelic analysis of the relationship between HLA-DRB1 and rheumatoid arthri 2006 Sep To analyse the association between individual HLA-DRB1 locus genotypes and rheumatoid arthritis (RA) susceptibility, taking in account the multiallelic nature of the shared epitope (SE). In total, 538 patients and 536 controls were genotyped for 12 alleles of the HLA-DRB1 locus. A Bayesian partition model and multivariate logistic models were used to assess the role of the SE and of its individual components. The SE was associated with RA susceptibility (odds ratio (OR) 2 versus 0 SE copy=9.99 (95 CI 4.69-15.30) and OR 1 versus 0 SE copy=3.16 (95% CI 2.42-4.12)). The Bayesian partition model supplied a permutation of the HLA-DRBA locus alleles ordered by increasing disease risk. Alleles associated with highest risks are those that code for the SE. The individual OR estimations for the HLA-DRB1 locus genotypes went from OR=1.00 (95% CI 1.00-1.25) for the less associated genotype to OR=21.40 (95% CI 8.02-65.79) for the most associated one. In conclusion, the allele order risk and the OR estimations for individual genotypes of the HLA-DRB1 locus were consistent with the SE theory. Using an exploratory statistical method without a priori hypothesis, our study allowed a detailed analysis of the multiallelic nature of the SE.
15045525 Identification of the receptor for advanced glycation end products in synovial tissue of p 2005 Aug OBJECTIVES: Generation of advanced glycation end products (AGE) is an inevitable process in vivo and can be accelerated under pathologic conditions such as oxidative stress, e.g. in rheumatoid arthritis (RA). This process is mediated by the AGE-specific receptor (RAGE). In this study we analysed the presence of RAGE in RA and osteoarthritic (OA) synovial tissue using immunohistology. METHODS: Frozen synovial tissue samples from 11 RA patients and 12 OA patients were treated with goat anti-RAGE immunoglobulin G (IgG) and rabbit antigoat IgG. Immunostaining was visualised with streptavidin horse radish peroxidase (chromogen amino-ethyl-carbazole). Cell differentiation was performed with antibodies against CD68, CD45RO, and CD20. RESULTS: In 9/11 RA and 8/12 OA synovial specimens, RAGE was detected in synovial lining, sublining, and stroma. In RA, many T cells (CD45RO(+)) and some macrophages (CD68(+)) showed positive immunostaining for RAGE, whereas B cells were mostly negative. We found no difference in staining patterns between the RA and OA samples. CONCLUSIONS: We detected RAGE in RA and OA synovial tissue. The presence of RAGE on macrophages, T cells, and some B cells suggests its role in the pathogenesis of inflammatory joint disease.
17092252 Microsatellite typing of the human leucocyte antigen region: analytical approach and contr 2006 Nov Within the major histocompatibility complex (MHC), the human leucocyte antigen (HLA)-DRB1 locus is clearly associated with rheumatoid arthritis (RA). Using a microsatellite (MSat) typing approach, we aimed to identify other loci associated with RA susceptibility and/or severity within the MHC. A panel of nine MSat HLA loci [D6S291, D6S2876 (G51152), D6S1666 (DQCAR II), D6S273, D6S2789 (TNFd), D6S2810 (MIB), D6S265, D6S2222, D6S2239], and HLA-A, -B and -DRB1 genes were typed in 170 RA cases and 282 controls. For susceptibility analysis, MSat and HLA allele distribution were compared between cases and controls, before and after stratification on HLA-DRB1*04. Haplotype frequencies were estimated using an expectation-maximization algorithm in a permutation test procedure. For severity analysis, we compared the distribution of structural damage score at onset and after 4 years of follow-up in RA cases carrying susceptibility alleles. Two MSat polymorphisms were positively associated with RA susceptibility: allele*136 of D6S265 [odds ratio, OR (confidence interval, CI) = 1.55 (1.11-2.17), P= 0.007], allele*116 of D6S2239 [OR = 1.34 (1-1.79), P= 0.03] and HLA-A2 [OR = 1.46 (1.08-1.98), P= 0.01]. Two MSat polymorphisms were negatively associated with RA susceptibility: allele*133 of D6S273 [OR = 0.3 (0.1-0.75), P= 0.005] and allele*177 of D6S291 [OR = 0.72 (0.53-0.96), P= 0.02]. The association between allele*136 of D6S265 and RA susceptibility remained unchanged after stratification on HLA-DRB1*04. The haplotypic analysis showed an overrepresentation of D6S265*136/HLA-A*02 haplotype, which suggests an effect independent of HLA-DRB1 locus in RA susceptibility. While HLA-A2 and HLA-DR4 were associated with RA severity, no MSat polymorphism was associated with structural damage score.
17024400 Computer-assisted screw insertion for cervical disorders in rheumatoid arthritis. 2007 Apr To reconstruct highly destructed unstable rheumatoid arthritis (RA) cervical lesions, the authors have been using C1/2 transarticular and cervical pedicle screw fixations. Pedicle screw fixation and C1/2 transarticular screw fixation are biomechanically superior to other fixation techniques for RA patients. However, due to severe spinal deformity and small anatomical size of the vertebra, including the lateral mass and pedicle, in the most RA cervical lesions, these screw fixation procedures are technically demanding and pose the potential risk of neurovascular injuries. The purpose of this study was to evaluate the accuracy and safety of cervical pedicle screw insertion to the deformed, fragile, and small RA spine lesions using computer-assisted image-guidance systems. A frameless, stereotactic image-guidance system that is CT-based, and optoelectronic was used for correct screw placement. A total of 21 patients (16 females, 5 males) with cervical disorders due to RA were surgically treated using the image-guidance system. Postoperative computerized tomography and plane X-ray was used to determine the accuracy of the screw placement. Neural and vascular complications associated with screw insertion and postoperative neural recovery were evaluated. Postoperative radiological evaluations revealed that only 1 (2.1%; C4) of 48 screws inserted into the cervical pedicle had perforated the vertebral artery canal more than 25% (critical breach). However, no neurovascular complications were observed. According to Ranawat's classification, 9 patients remained the same, and 12 patients showed improvement. Instrumentation failure, loss of reduction, or nonunion was not observed at the final follow-up (average 49.5 months; range 24-96 months). In this study, the authors demonstrated that image-guidance systems could be applied safely to the cervical lesions caused by RA. Image-guidance systems are useful tools in preoperative planning and in transarticular or transpedicular screw placement in the cervical spine of RA patients.
16984942 Abatacept improves both the physical and mental health of patients with rheumatoid arthrit 2007 Feb OBJECTIVE: To examine the impact of added abatacept treatment on health related quality of life (HRQoL) in patients with rheumatoid arthritis (RA) who have inadequate response to methotrexate (MTX). METHODS: The impact of abatacept treatment on HRQoL was examined in a longitudinal, randomised double blind, placebo controlled clinical trial. Effects of treatment on HRQoL were examined using repeated measures analysis of covariance and comparing rates of change in HRQoL across treatment groups. The relationship between American College of Rheumatology (ACR) clinical markers and disease duration with changes in HRQoL indicators was also examined. Finally, a responder analysis was used to examine the percentage of patients who improved by 0.5 SD in 12 months or who reached the normative levels seen in the US general population. RESULTS: Statistically significant improvements in the abatacept group relative to controls were observed across a range of HRQoL measures, including physical function, fatigue, all eight domains of the SF-36, and the physical and mental component summaries (PCS and MCS). Improvements were seen as early as day 29 for fatigue and for five out of eight SF-36 domains. By day 169, all HRQoL measures were significantly better with abatacept than with placebo. HRQoL gains were associated with greater ACR clinical improvement, and the effects were consistent for patients with different disease duration. A significantly greater percentage of patients treated with abatacept reached normative levels of PCS, MCS, physical functioning, and fatigue compared with patients treated with MTX alone. CONCLUSION: Combined abatacept and MTX treatment produces significant improvements across a wide range of HRQoL domains in patients with RA.
17062648 Sustained benefit in rheumatoid arthritis following one course of rituximab: improvements 2006 Dec OBJECTIVES: To evaluate the long-term impact on physical function of a single course of rituximab in rheumatoid factor, seropositive patients with active rheumatoid arthritis (RA) despite ongoing methotrexate treatment. METHODS: A randomized, controlled trial comparing rituximab alone [1,000 mg intravenously (iv) on days 1 and 15, n= 40], or in combination with cyclophosphamide (750 mg iv on days 3 and 7, n= 41) or oral methotrexate (> or =10 mg/week, n= 40) with placebo + methotrexate (> or =10 mg/week, n= 40), resulted in significant reductions in disease activity at weeks 24 and 48. Sustained improvements in physical function and standard effect sizes (SES) for changes in components of ACR and EULAR criteria were evaluated over 2 yrs. RESULTS: More patients receiving rituximab + methotrexate completed a 2-yr follow-up without further treatment than those receiving placebo + methotrexate (45% vs 15%, respectively), rituximab alone (10%) or rituximab + cyclophosphamide (22%). This reflected a higher percentage of patients receiving rituximab + methotrexate reporting improvements in Health Assessment Questionnaire Disability Index > or = minimum clinically important difference at 1 and 2 yrs (68% and 30%, respectively) compared with placebo + methotrexate (28% and 15%), rituximab monotherapy (43% and 10%) or rituximab + cyclophosphamide (39% and 12%). SES were high in all rituximab groups and revealed differing patterns of response over time. CONCLUSION: A single course of rituximab with continuing methotrexate in patients with active RA provided clinically meaningful improvements in physical function over 2 yrs, with lower discontinuation rates and larger SES for improvements in ACR and EULAR criteria components.
16200383 Lethal acute respiratory distress syndrome during anti-TNF-alpha therapy for rheumatoid ar 2006 May Tumor necrosis factor alpha (TNF-alpha) blocking drugs improve therapy for rheumatic diseases, but the risk of additional immunosuppression and infection is unclear. We report on a patient with rheumatoid arthritis treated with etanercept for 2 years, in addition to methotrexate and prednyliden, who developed fulminant pneumococcal pneumonia with rapid progression to fatal acute respiratory distress syndrome (ARDS) and septic shock. In patients receiving anti-TNF-alpha therapy, especially in combination with corticosteroids, signs of pulmonary infection should be regarded as very serious, as fulminant pneumonia with ARDS and severe sepsis may develop within 24 h.
15851523 Panel discussion on B cells and rituximab: mechanistic aspects, efficacy and safety in rhe 2005 May The clinical potential of rituximab (MabThera/Rituxan), a selective B-cell-depleting agent, in the treatment of patients with rheumatoid arthritis (RA) is rapidly becoming apparent. The data presented at an official satellite symposium of the European League Against Rheumatism (EULAR) Congress (2003, Lisbon, Portugal), reinforce the rationale for the use of this novel agent in RA and have provided an early indication of its clinical efficacy, safety and tolerability. The symposium presentations were followed by a panel discussion and a question and answer session in which the participants were able to shed further light on specific mechanistic issues relating to effects on B-cell populations based on available data and their own clinical experience of rituximab. Additionally, the implications of current results for longer-term clinical efficacy and safety were discussed. It is becoming clear that rituximab (alone or in combination with disease-modifying anti-rheumatic drugs) is highly efficacious in RA. Extensive data from patients with non-Hodgkin's lymphoma show that early concerns over increased infection rates due to prolonged suppression of B cells have not been realized. The effects of rituximab on long-term RA outcomes, such as joint erosion and duration of response (particularly in patients receiving combination therapy), are eagerly anticipated.
15720278 Chemokine expression and regulation of angiogenesis in rheumatoid arthritis. 2005 Regulation of angiogenesis occurs in the context of particular microenvironments and is governed by a sensitive balance between angiogenic and anti-angiogenic mediators. Under normal physiologic conditions, the expansion of existing blood vessels is held in check suggesting that homeostasis is maintained by a predominance of angiostatic factors. In the rheumatoid arthritis joint, it is probable that the expansive and tumor-like synovial pannus that invades cartilage requires additional nutrients and oxygen. In the face of these demands, there is likely a shift in the balance such that angiogenic mediators predominate leading to neovascularization, a hallmark of rheumatoid arthritis. Chemokines are a subset of cytokines that primarily mediate physiologic and pathophysiologic leukocyte trafficking during inflammation and immune cell differentiation. Chemokines are also fundamental participants, along with a variety of other factors, which regulate angiogenesis. Within the CXC family of chemokines, there is functional discrepancy, where some family members are angiogenic and others are angiostatic. Moreover, the expression of several chemokines has been well documented in rheumatoid arthritis synovial tissues and fluids. This review will discuss what is known about the role of specific chemokines in the regulation of angiogenesis with particular emphasis on those chemokines likely to participate in rheumatoid arthritis.
16632478 Patients' views on the quality of health care for rheumatoid arthritis. 2006 Dec OBJECTIVE: To study the experiences and views of patients with rheumatoid arthritis (RA) on the quality of health care received in primary and secondary care. METHOD: Semi-structured interviews with 26 individual patients with RA; these were stratified by sex, ethnicity and disease duration, based on the treated prevalence cohort of patients attending two outpatient clinics in South East England. RESULTS: Patients highlighted four main factors which influenced their attitude and approach towards hospital staff and the treatment offered: (i) their past experiences with the National Health Service (NHS), (ii) their own health beliefs, (iii) professional attitudes (e.g. listening to patients, receiving feedback on disease processes) and (iv) organizational aspects (e.g. good communication between health professionals) which would make their visits to the outpatient clinic easier. CONCLUSION: Most patients no longer see themselves as passive recipients of care. They appreciate acknowledgement from health care professionals of their contribution towards management of their own chronic illness, and welcome a more equal dialogue with health care staff. This is consistent with the emphasis of the Department of Health document on 'Supporting People with Long-term Conditions' such as RA.
16757761 Total ankle arthroplasty in inflammatory joint disease with use of two mobile-bearing desi 2006 Jun BACKGROUND: Interest in mobile-bearing total ankle arthroplasty has increased in recent years. However, to our knowledge, no study has focused exclusively on patients with the diagnosis of inflammatory joint disease or has provided a detailed analysis of the risk factors for failure. METHODS: A prospective observational study of the results of cementless mobile-bearing total ankle arthroplasty in patients with inflammatory joint disease (mainly rheumatoid arthritis) was conducted at two centers. Ninety-three total ankle arthroplasties were performed. The LCS (low contact stress) prosthesis was used initially, in nineteen ankles, between 1988 and 1992, and a modification of the LCS prosthesis, the Buechel-Pappas design, was used in seventy-four ankles between 1993 and 1999. Clinical and radiographic follow-up was performed at yearly intervals. Three clinical scoring systems were used, and any complication was recorded throughout follow-up. Actuarial survival (with revision as the end point), multivariate analysis, and a competing risk approach were used to describe the long-term outcome. RESULTS: The clinical result at one year after surgery showed a significant improvement in the scores on all three scoring systems (p < 0.05). Ankle dorsiflexion (mean, 7 degrees ) also improved significantly (p < 0.05) compared with the preoperative state. The most frequent complication was a malleolar fracture, which occurred in twenty ankles. Only when it occurred in combination with a deformity in the frontal plane did this complication have an adverse effect on the end result. At a mean follow-up of eight years, seventeen patients (twenty-one ankles) had died and fifteen ankles had been revised because of aseptic loosening (six ankles), primary or secondary axial deformity with edge-loading (six ankles), deep infection (two ankles), and a severe wound-healing problem (one ankle), leaving fifty-seven ankles (61%) that were evaluated. The mean overall survival rate at eight years was 84%. An increased failure rate was encountered in ankles with a preoperative deformity in the frontal plane of >10 degrees (p = 0.03) and in ankles in which an undersized tibial component had been implanted (p = 0.02). CONCLUSIONS: Mobile-bearing total ankle arthroplasty is a valid treatment option for the rheumatoid ankle if proper indications are used. Aseptic loosening and persistent deformity are the most important modes of failure.
16044897 [About a short series of Swanson arthroplasty]. 2005 May The authors report a series of 12 patients who underwent digital arthroplasty using a swanson implant. Six patients had the sequellae of an injured hand, and the other six patients had rheumatoid arthritis. The majority of patients were men with an average age of 33 years. The patients were examined again about 4 years later on average. The lateral stability of the operated finger was considered to be satisfactory in 11 cases. The mean movement gain was 40 degrees. There was no sign of silicone particle synovitis, because it was fixed arthroplasty.
16770616 Treatment of rheumatoid arthritis with ornidazole: a randomized, double-blind, placebo-con 2006 Oct The aim of our study was to evaluate the clinical efficacy, safety, and tolerability of ornidazole in patients with rheumatoid arthritis (RA). This was 3 months, randomized, double-blind,placebo-controlled study. A total of 160 patients with active RA were randomly assigned to receive 1,000 mg ornidazole (n = 53), 500 mg ornidazole (n = 55), or placebo (n = 52). A significantly greater percentage of patients treated with 1,000 mg ornidazole met the American College of Rheumatology 20% improvement criteria (achieved an ACR20 response) at 3 months compared with patients who received placebo (62.0 vs. 32.4%; P < 0.001). Greater percentages of patients treated with 1,000 mg ornidazole also achieved ACR50 responses (38.3 vs. 10.9%; P < 0.001) and ACR70 responses (19.6 vs. 1.2%; P < 0.001) compared with patients who received placebo. Ornidazole treatment was also associated with significant reductions in pain and duration of morning stiffness, significant improvement in the quality of life and both the physician's and patient's global assessments, and significant reductions in disease activity as assessed by objective laboratory measures (erythrocyte sedimentation rate and C-reactive protein level). Ornidazole was well tolerated. There were no dose-limiting toxic effects. In this 3-month-trial ornidazole was safe, well tolerated, and associated with improvement in the inflammatory symptoms of RA.
16076608 Relative transcriptional activities of SAA1 promoters polymorphic at position -13(T/C): po 2005 Mar The risk associated with the serum amyloid A (SAA) 1 gene and developing AA-amyloidosis is still controversial. In familial Mediterranean fever or Caucasoid rheumatoid arthritis (RA), the SAA1.1 allele is a risk factor for the development of AA-amyloidosis. However, individuals with the SAA1.3 allele are susceptible to AA-amyloidosis in the Japanese RA population, but those with the SAA1.1 are not. Previous reports have indicated that the -13T/C single nucleotide polymorphism (SNP) at the 5'-flanking region of SAA1 appears to be a better marker of AA-amyloidosis than the exon-3 based haplotype, i.e., SAA1.1 or SAA1.3, in both Japanese and American Caucasian populations. So far, it is unknown why the -13T SNP increases the amyloidogenicity of the patients. In the present study, a luciferase reporter gene assay showed that the transcriptional activity of the SAA1 having the -13T-containing promoter was significantly higher than activities of those with -13C-containing promoters (Fisher's protected least significance difference test). We suggest that having the -13T SNP in the SAA1 promoter correlates with the amyloidogenicity in part as a result of this increased transcriptional activity.
15792203 A radiological study of the intraprosthetic movements of the bipolar shoulder replacement 2005 Feb A radiological study of the intraprosthetic movements of a bipolar shoulder replacement was undertaken in 25 shoulders in 20 patients with rheumatoid arthritis and rotator cuff arthropathy. No significant difference was found between intraprosthetic movement and shell - glenoid movement. Some shoulders were found to exhibit paradoxical movement at the intraprosthetic interface. Repeating the measurements after an interval of three years in a subgroup of 12 shoulders showed a significant reduction in intraprosthetic movement over this time interval. In conclusion, movement of the bipolar shoulder prosthesis in shoulders affected by rheumatoid arthritis was preserved up to eight years from operation. Intraprosthetic movement was independent from shell - glenoid movement and paradoxical to glenohumeral movement.
16255021 Refining the complex rheumatoid arthritis phenotype based on specificity of the HLA-DRB1 s 2005 Nov OBJECTIVE: The main genetic risk factor for rheumatoid arthritis (RA), the HLA region, has been known for 25 years. Previous research has demonstrated, within the RA population, an association between HLA-DRB1 alleles carrying the shared epitope (SE) and antibodies directed against cyclic citrullinated peptides (anti-CCP antibodies). We undertook this study to make the first comparison of SE allele frequencies in the healthy population with those in RA patients who do or do not harbor anti-CCP antibodies. METHODS: HLA-DRB1 typing was performed in 408 RA patients from the Leiden Early Arthritis Clinic (the Leiden EAC; a Dutch population-based inception cohort in which disease course was followed up over time), in 423 healthy Dutch controls, and in 720 affected members of 341 US multiplex (sibpair) families of Caucasian origin from the North American RA Consortium (NARAC) with well-established disease and fulfilling the American College of Rheumatology classification criteria for RA. The presence of anti-CCP antibodies was determined by enzyme-linked immunosorbent assay. RESULTS: For the Leiden EAC, the odds ratio (OR) describing the association of 2 copies of the SE allele with anti-CCP positivity (using no copies of the SE allele in the healthy control group as the referent) was 11.79 (P < 0.0001), while the OR for 1 SE allele was 4.37 (P < 0.0001). No association with the SE was observed in the Dutch anti-CCP-negative RA patients. For the NARAC families, linkage and association analysis revealed the SE to be associated only with anti-CCP-positive disease and not with anti-CCP-negative disease. Stratified analyses indicated that anti-CCP antibodies primarily mediated association of the SE with joint damage or disease persistence. CONCLUSION: HLA-DRB1 alleles encoding the SE are specific for disease characterized by antibodies to citrullinated peptides, indicating that these alleles do not associate with RA as such, but rather with a particular phenotype.
15458956 Prognostic laboratory markers of joint damage in rheumatoid arthritis. 2005 Feb OBJECTIVE: To investigate whether determination of a set of laboratory markers at baseline provides prognostic information on joint damage in hands and feet in rheumatoid arthritis. METHODS: 183 patients with early rheumatoid arthritis included in a prospective study were examined. Radiographic changes in hands and feet at 5 and 10 years after inclusion were evaluated (Larsen). The markers analysed were: erythrocyte sedimentation rate (ESR); HLA-DRB alleles typed by restriction fragment length polymorphism; and C reactive protein, cartilage oligomeric matrix protein (COMP), rheumatoid factor (RF) (IgG, IgA, and IgM subtypes), antibodies against cyclic citrullinated peptide (anti-CCP), and antibodies against interleukin 1alpha (anti-IL1alpha), analysed by immunoassays. Multiple linear regression with backward elimination was used to determine the prognostic value of the variables. RESULTS: 117/176 patients were positive for IgG RF, 138/176 for IgA RF, 139/176 for IgM RF, 140/176 for anti-CCP, and 40/182 for anti-IL1alpha. After five years, ESR, the presence of IgA RF, serum COMP, and the presence of anti-CCP were significantly associated with more severe joint damage, and the presence of anti-IL1alpha with less severe joint damage. Baseline C reactive protein and anti-CCP predicted radiographic outcome after 10 years. A stronger prediction was obtained by combining the prognostic factors. CONCLUSIONS: Early determination of anti-CCP, IgA RF, anti-IL-1alpha, ESR, C reactive protein, and COMP predicted the development of joint damage in hands and feet in this cohort. A combination of these measures reflecting different aspects of the disease process should be useful for evaluating prognosis in individual patients with early rheumatoid arthritis.
17017948 Role of nitric oxide and reactive oxygen species in arthritis. 2006 A vast amount of circumstantial evidence implicates oxygen-derived free radicals, especially reactive oxygen species and nitric oxide as mediators of inflammation and/or tissue destruction in inflammatory and arthritic disorders. The aim of the current article is to overview the recent developments in this field, as it relates to the roles of nitric oxide (NO) and reactive oxygen species in the pathogenesis of this condition. The first part of the review focuses on the biochemical impact of NO and reactive oxygen species. The second part of the review deals with the novel findings related to the recently identified regulatory roles of the inducible isoform of nitric oxide synthase (iNOS) in the expression of pro-inflammatory mediators in inflammation. Reactive oxygen species can initiate a wide range of toxic oxidative reactions. These include initiation of lipid peroxidation, direct inhibition of mitochondrial respiratory chain enzymes, inactivation of glyceraldehyde-3phosphate dehydrogenase, inhibition of membrane sodium/potassium ATP-ase activity, inactivation of membrane sodium channels, and other oxidative modifications of proteins. All these toxicities are likely to play a role in the pathophysiology of inflammation. Reactive oxygen species are all potential reactants capable of initiating DNA single strand breakage, with subsequent activation of the nuclear enzyme poly (ADP ribose) synthetase (PARS), leading to eventual severe energy depletion of the cells, and necrotic-type cell death. Recently it has been demonstrated that iNOS inhibitor prevents the activation of poly (ADP ribose) synthetase, and prevents the organ injury associated with inflammation. Although the severity and duration of inflammation may dictate the timing and extent of NOS expression, it is now evident that the up-regulation of NOS can take place during sustained inflammation. Thus, induced nitric oxide, in addition to being a "final common mediator" of inflammation, is essential for the up-regulation of the inflammatory response. Furthermore, a picture of a pathway is evolving that contributes to tissue damage both directly via the formation of reactive oxygen species, with them associated toxicities, and indirectly through the amplification of the inflammatory response.
16146751 Matrix metalloproteinases: role in arthritis. 2006 Jan 1 The irreversible destruction of the cartilage, tendon, and bone that comprise synovial joints is the hallmark of both rheumatoid arthritis (RA) and osteoarthritis (OA). While cartilage is made up of proteoglycans and type II collagen, tendon and bone are composed primarily of type I collagen. RA is an autoimmune disease afflicting numerous joints throughout the body; in contrast, OA develops in a small number of joints, usually resulting from chronic overuse or injury. In both diseases, inflammatory cytokines such as interleukin-1 beta (IL-1 beta) and tumor necrosis factor-alpha (TNF-alpha) stimulate the production of matrix metalloproteinases (MMPs), enzymes that can degrade all components of the extracellular matrix. The collagenases, MMP-1 and MMP-13, have predominant roles in RA and OA because they are rate limiting in the process of collagen degradation. MMP-1 is produced primarily by the synovial cells that line the joints, and MMP-13 is a product of the chondrocytes that reside in the cartilage. In addition to collagen, MMP-13 also degrades the proteoglycan molecule, aggrecan, giving it a dual role in matrix destruction. Expression of other MMPs such as MMP-2, MMP-3 and MMP-9, is also elevated in arthritis and these enzymes degrade non-collagen matrix components of the joints. Significant effort has been expended in attempts to design effective inhibitors of MMP activity and/or synthesis with the goal of curbing connective tissues destruction within the joints. To date, however, no effective clinical inhibitors exist. Increasing our knowledge of the crystal structures of these enzymes and of the signal transduction pathways and molecular mechanisms that control MMP gene expression may provide new opportunities for the development of therapeutics to prevent the joint destruction seen in arthritis.