Persisting eicosanoid pathways in rheumatic diseases.

An unmet clinical need exists for early treatment of rheumatic diseases and improved treatment strategies that can better maintain remission with reduced ongoing subclinical inflammation and bone destruction. Eicosanoids form one of the most complex networks in the body controlling many physiological and pathophysiological processes, including inflammation, autoimmunity and cancer. Persisting eicosanoid pathways are thought to be involved in the development of rheumatic diseases, and targeting this pathway might enable improved treatment strategies. Several enzymes of the arachidonic acid cascade as well as eicosanoid receptors (all part of the eicosanoid pathway) are today well-recognized targets for anti-inflammatory drugs that can reduce symptoms of inflammation in rheumatic diseases. In this Review, we outline the evidence supporting pivotal roles of eicosanoid signalling in the pathogenesis of rheumatic diseases and discuss findings from studies in animals and humans. We focus first on rheumatoid arthritis and discuss the upregulation of the cyclooxygenase and lipoxygenase pathways as most data are available in this condition. Research into the roles of eicosanoids in other rheumatic diseases (osteoarthritis, idiopathic inflammatory myopathies, systemic lupus erythematosus and gout) is also progressing rapidly and is discussed. Finally, we summarize the prospects of targeting eicosanoid pathways as anti-inflammatory treatment strategies for patients with rheumatic diseases.

The emerging roles of HTRA1 in musculoskeletal disease.

High-temperature requirement serine protease A1 (HTRA1) is one of four known proteases belonging to the broadly conserved family of HTRA proteins. Although it was originally considered as representing an important modulator of tumorigenesis, an increasing number of reports have suggested that its influence on human disease may extend beyond cancer. HTRA1 has the capacity to degrade numerous extracellular matrix proteins, and as such, its potential involvement in diseases of the musculoskeletal system has been gaining increased attention. Musculoskeletal disease constitutes a wide variety of degenerative conditions that can manifest themselves in different ways such as joint and back pain, as well as deficiencies in skeletal bone quality, and ultimately result in significant suffering and reduced quality of life. Convincing data now exist to support a detrimental role for HTRA1 in the pathogenesis of joint and intervertebral disk degeneration. However, the function of HTRA1 in other closely related musculoskeletal diseases affecting bone and muscle remains unclear and largely unexplored. To help set the stage for future research, we discuss here some of the recent advances in our understanding of the role played by HTRA1 in musculoskeletal pathology.

Basic science for the clinician 48: tyrosine kinases in disease: the potential for inhibitors in the treatment of immunologic diseases.

The magic bullet--a compound that will stop a disease dead in its tracks by specifically targeting the underlying pathogenic principle of that disease--is what every designer/developer of drugs wants. As cellular and molecular biology research delves deeper into how cells are activated by their ligands, the intracellular pathways of activation of individual cellular processes become better known and more attractive therapeutic targets. The receptors for transforming growth factor beta (TGFbeta) and platelet-derived growth factor (PDGF) activate a variety of cells via a series of tyrosine kinases; inhibition of specific tyrosine kinases has until recently been within the domain of oncologists, treating leukemia, and certain gastrointestinal tumors, but now there is mounting evidence that these agents might be of value in rheumatologic and autoimmune diseases. This is another example of "Better living (and curing!) through chemistry" that we as clinicians need to master to render optimal care.

Protein isoprenylation regulates secretion of matrix metalloproteinase 1 from rheumatoid synovial fibroblasts: effects of statins and farnesyl and geranylgeranyl transferase inhibitors.

OBJECTIVE: To determine whether protein prenylation (farnesyl/geranylgeranylation) regulates matrix metalloproteinase (MMP) secretion from rheumatoid arthritis (RA) synovial fibroblasts (RASFs), and whether MMP-1 secretion can be regulated by statins or prenyltransferase inhibitors via effects mediated by ERK, JNK, and NF-kappaB. METHODS: RASFs obtained from patients during elective knee replacement surgery were assessed by immunoblotting and/or enzyme-linked immunosorbent assay for secretion of MMP-1 and MMP-13 in the presence of tumor necrosis factor alpha (TNFalpha), interleukin-1beta (IL-1beta), statins, the farnesyl transferase (FT) inhibitor FTI-276 and geranylgeranyl transferase inhibitor GGTI-298, and prenyl substrates (farnesyl pyrophosphate [FPP] and geranylgeranyl pyrophosphate [GGPP]). Activities of JNK and ERK were determined by phosphoimmunoblotting, and NF-kappaB activation was determined by nuclear translocation of the p65 component. RESULTS: FTI-276, but not statins, inhibited RASF secretion of MMP-1, but not MMP-13, following induction with TNFalpha (P = 0.0007) or IL-1beta (P = 0.006). Loading RASFs with FPP to promote farnesylation enhanced MMP-1 secretion. FTI-276 inhibited activation of JNK (P < 0.05) and NF-kappaB (P = 0.02), but not ERK. In contrast, GGTI-298 enhanced, while GGPP inhibited, MMP-1 secretion. FTI-276 and GGTI-298 together had no effect on MMP-1 secretion. Stimulation of RASFs with TNFalpha or IL-1beta led to increased expression and activity of FT. CONCLUSION: Protein farnesylation is required for expression and secretion of MMP-1 from RASFs, via effects on JNK and NF-kappaB. The ability of cytokines to stimulate the expression and activity of FT suggests that FT may be increased in the rheumatoid joint. In contrast, geranylgeranylation down-regulates MMP-1 expression. Statins simultaneously inhibit farnesylation and geranylgeranylation, and in consequence do not inhibit MMP-1 secretion. The ability of FTI-276 to inhibit MMP-1 secretion suggests a potential therapeutic strategy in RA.

Reactive oxygen species and superoxide dismutases: role in joint diseases.

Reactive oxygen species (ROS) are produced in many normal and abnormal processes in humans, including atheroma, asthma, joint diseases, aging, and cancer. The superoxide anion O(2)(-) is the main ROS. Increased ROS production leads to tissue damage associated with inflammation. Superoxide dismutases (SODs) convert superoxide to hydrogen peroxide, which is then removed by glutathione peroxidase or catalase. Thus, SODs prevent the formation of highly aggressive ROS, such as peroxynitrite or the hydroxyl radical. Experimental models involving SOD knockout or overexpression are beginning to shed light on the pathophysiological role of SOD in humans. Although the antiinflammatory effects of exogenous native SOD (orgotein) are modest, synthetic SOD mimetics hold considerable promise for modulating the inflammatory response. In this review, we discuss new knowledge about the role of the superoxide anion and its derivates as mediators of inflammation and the role of SODs and SOD mimetics as antioxidant treatments in joint diseases such as rheumatoid arthritis, osteoarthritis, and crystal-induced arthropathies.

[The profile and clinical significance of azathioprine metabolic enzymes activity in rheumatological patients].

OBJECTIVE: To detect the activity of thiopurine methyltransferase (TPMT) and its relationship with azathioprine (AZA) tolerance. METHODS: 200 patients of rheumatism need AZA were included in the study. RBC TPMT activity was detected with high performance liquid chromatography. Then the patients took AZA doses of 50 mg/d for the first month, 100 mg/d for the second month and 150 mg/d for the third month. RESULTS: TPMT activity of 200 patients ranged from 0.75 - 32.35 U/ml RBC, averaged (12.04 +/- 6.90) U/ml RBC. The activity of TPMT showed a normal skewness distribution and no activity deficiency was founded. 194 patients (97%) completed the 3 month follow-up. 18 showed bone marrow depression including 2 severe hematological crisis and 6 showed hepatic damage during the 3 months. Bone marrow depression was recorded of 7 cases with the TPMT activity of 2.24 - 5.97 U/ml RBC, averaged (3.47 +/- 1.21) U/ml RBC, among the dose of 50 mg/d and 11 cases with the TPMT activity of 4.01 - 11.17 U/ml RBC, averaged (7.08 +/- 2.58) U/ml RBC, among the dose of 100 - 150 mg/d. The other 176 cases did not show bone marrow depression at all, with TPMT activity of 4.47 - 32.35 U/ml RBC, averaged (13.02 +/- 6.07) U/ml RBC. TPMT activities in the 3 groups of patients were significantly different according to statistical analysis (P < 0.01). CONCLUSIONS: Hematological side effects were highly associated with TPMT activity in AZA usage. Patients with low TPMT activity should use low dose of AZA routinely, even though, toxicity may occur. Test of TPMT activity before AZA description was of significance.

Pre-analytical problems in the measurement of tumor type pyruvate kinase (tumor M2-PK).

INTRODUCTION: Tumor M2-PK is an isoform of the glycolytic enzyme pyruvate kinase. This isoform exists in an active tetrameric and less active dimeric form. The dimeric form is expressed by various tumor cells and can be measured in blood by a specific ELISA. MATERIALS AND METHODS: We included 500 healthy persons, 20 patients with an acute rheumatic disease (high CRP) and 30 patients with a nephropathy and proteinuria with more than 20 mg/dl. We measured Tumor M2-PK in each of these groups in different specimens of EDTA-plasma, serum, heparin-, citrate-, fluoride- and oxalate-plasma. RESULTS: We found different concentrations of Tumor M2-PK in healthy persons depending on the kind of specimen. The normal range of Tumor M2-PK concentration was higher in the serum than in the plasma, with 35 U/l compared to 15 U/l. In haemolytic material we found concentrations up to 80 U/l in healthy persons. Lipaemic or icteric serum material showed a higher concentration of Tumor M2-PK as well. In patients with a triglyceride concentration higher than 300 mg/dl, the normal range for Tumor M2-PK was measured between 30-50 U/l. Similar results were found in patients with icteric serum. Patients with an active rheumatic disease and elevated CRP concentration showed a Tumor M2-PK concentration between 40-60 U/l. Patients with a nephropathy and proteinuria over 20 mg/dl had an elevated Tumor M2-PK concentration from 25-60 U/l. CONCLUSION: We conclude that different materials seem to be suitable for the measurement of Tumor M2-PK concentration as long as attention is paid to different normal ranges. Haemolytic material should not be used as it offers false-positive results. Some diseases such as rheumatic disease, hyperlipidaemia and nephropathy have an influence on Tumor M2-PK concentration that should not be neglected.

Pyruvate kinase type tumor M2 plasma levels in patients afflicted with rheumatic diseases.

BACKGROUND: Since tumor markers can be increased in the course of many benign diseases, the aim of this study was to verify if this also occurs in the course of rheumatic diseases. MATERIALS AND METHODS: We investigated the incidence and characteristics of Tumor M2-PK in the EDTA-plasma of 137 patients suffering from rheumatic diseases. RESULTS: The tumor M2-PK concentration was increased in 52 out of 63 patients (82%) with classical rheumatoid arthritis, in 15 out of 21 patients (71%) with systemic lupus erythematosus, in 14 out of 17 patients (82%) with seronegative spondylarthritis and in 13 out of 28 patients with miscellaneous rheumatic diseases (46%). Malignant neoplasm was not detected in any of the patients with rheumatic diseases. CONCLUSION: These results demonstrated that the EDTA-plasma concentrations of Tumor M2-PK were increased in patients with rheumatic diseases.

Pain and disability, perceptions and beliefs of a rural Indian population: A WHO-ILAR COPCORD study. WHO-International League of Associations for Rheumatology. Community Oriented Program for Control of Rheumatic Diseases.

OBJECTIVE: The WHO-ILAR Community Oriented Program for Control of Rheumatic Diseases (COPCORD) primarily aims to estimate the burden of rheumatic-musculoskeletal symptoms/disorders (RMS). We investigated data on pain and disability, perceptions and beliefs in the first rural community based COPCORD study in India. METHODS: A total of 4092 adults were interviewed (response rate 89%) in a population survey (Stage 1) in Bhigwan village in 1996 using modified COPCORD core questionnaires. Twenty-one trained volunteers completed the survey in 5 weeks. Those reporting RMS were identified (Phase 1) to complete a self-evaluation questionnaire (Phase 2) prior to rheumatological evaluation (Phase 3). Phase 2 included questions on perceptions and beliefs regarding pain, effect on life, work and socioeconomic factors, disability, and therapy; only the moderate and severe grades were considered significant. Patients marked their pain sites on a manikin during the presurvey week. A validated modified Health Assessment Questionnaire disability index (HAQDI) in the local language evaluated functional disability. RESULTS: RMS were the predominant ailments reported by 746 adult villagers (18.2%; 95% CI 17.1, 19.2). Moderate pain of > 2 years' duration was reported by almost 60% of RMS patients. Neck (6%), lumbar (11.4%), shoulder (7.4%), elbow (6.5%), wrist (6.4%), hand (6.1%), knee (13.2%), calf (6.6%), and ankle (6.5%) were the common painful sites, predominantly in women; 91%, 89%, and 31% with RMS reported a significant grade of pain, RMS illness, and disturbed sleep, respectively. In the age group 25-54 years, 21% of those with RMS perceived a significant effect on work ability, while less than 20% of those with RMS admitted a similar effect on their personal life (including finances). About 10% with RMS had ceased to work because of RMS. Among RMS subjects 21% scored a significant HAQDI, but many more reported significant difficulty (HAQ) in the individual items of walking, hygiene (squatting), arising (from sitting cross-legged), reaching, and occupational/household chores; this corresponded to the dominant pain sites in low back and lower limbs. Oral tobacco use was reported to be significantly greater (p < 0.001) in the RMS patients. Past trauma was recalled by 23% of patients, and many connected this to their RMS. Modern medicines were consumed by 55% of patients with RMS. Among patients, 86% and 65% expected "pain relief" and "cure," respectively, from their doctor; 23% of patients wanted greater sympathy and attention. However, 21% of patients had never visited a doctor and were only identified by the COPCORD study. CONCLUSION: The findings of this study (1) demonstrate that RMS, although a predominant ailment, has a modest effect on daily living in most subjects with RMS; (2) indicate there is inconsistency between the measures of pain and disability (using HAQ) and their effects; (3) describe the beliefs and expectations of the community. Based on the data and community support, the COPCORD has been continued for Stages II and III, especially with a view to health education.

Telomerase activity in the synovial tissues of chronic inflammatory and non-inflammatory rheumatic diseases.

Telomerase is a ribonucleoprotein complex which can compensate for telomeric loss originating from each cell division, and its activation plays a critical role in cellular immortality. We previously found that telomerase is activated not only in immortal cancer cells but also in activated lymphocytes. To assess the diagnostic significance of telomerase activity in RA synovial tissues, we quantitatively examined telomerase activity in synovial tissue samples obtained from 47 patients with RA, 31 with osteoarthritis (OA), and 23 with other joint diseases. Telomerase activity in synovial tissues was detected in 28 of 47 (59.6%) patients with RA, including monoarticular-type RA, but in none of those with other joint diseases except one case each of synovial chondromatosis and OA. Thus, the specificity of telomerase activity in synovial tissues for RA among joint diseases was 96.3% (52/54). In RA samples, the telomerase activity was detected in 14 of 27 (51. 9%) patients with total joint replacement, 7 of 12 (58.3%) open synovectomy cases, and 7 of 8 (87.5%) arthroscopic synovectomy cases. Detection of telomerase activity in synovial tissues is considered to be useful for diagnosis of RA, including monoarticular-type RA, or active inflammation with lymphocyte infiltration, and arthroscopy can be applied for this purpose.

Neutrophil gelatinase levels in plasma and synovial fluid of patients with rheumatic diseases.

To examine the clinical significance of neutrophil gelatinase in rheumatic diseases, plasma and synovial fluid (SF) gelatinase levels were determined in 62 patients with rheumatoid arthritis (RA), 12 patients with ankylosing spondylitis (AS), 18 patients with osteoarthritis (OA) and 17 healthy controls. The gelatinase level was measured by enzyme-linked immunoassay (ELISA). The assay had a sensitivity of 1 ng/ml and a working range of 5-25 ng/ml. Gelatinase levels were significantly higher in the plasma of patients with RA and of patients with RA complicated by amyloidosis or vasculitis as compared to those of healthy controls. Moreover, the mean value of gelatinase in the plasma of patients with RA complicated by vasculitis was found to be significantly higher than that of RA patients without vasculitis. A significant increase in gelatinase concentration was also observed in the plasma of AS patients but not in the plasma of patients with OA. The concentration of gelatinase in the RA SF samples was much higher (18-fold) than the level of the enzyme in the plasma of RA patients. There was also a higher concentration of gelatinase (four-fold) in OA SF compared with OA plasma. The results suggested that circulating gelatinase may reflect some degree of neutrophil activation in patients with inflammatory arthritis, especially in those with RA complicated by vasculitis. However, the results did not allow a differentiation between chronic and acute inflammation.

Elevated levels of xanthine oxidase in serum of patients with inflammatory and autoimmune rheumatic diseases.

Sera of patients with various inflammatory and autoimmune rheumatic diseases were screened for the presence of xanthine oxidase (XOD) and compared to sera from healthy donors and patients with nonrheumatic diseases including AIDS, internal diseases, and different carcinomas. Up to 50-fold higher levels of XOD were detected in rheumatic sera (P < 0.001). In addition, serum sulfhydryls (SH) were determined as sensitive markers of oxidative stress. The SH status in rheumatic patients was diminished by 45-75% (P < 0.001) and inversely correlated to the concentration of serum XOD (R = 0.73), suggesting a causal interrelation. The depletion of serum sulfhydryls by the oxyradical-producing XOD/acetaldehyde system was mimicked successfully ex vivo in human serum from healthy donors. Cortisone treatment of patients suffering from systemic lupus erythematosus and rheumatoid arthritis impressively normalized elevated XOD concentrations in rheumatic sera to those of healthy controls. The participation of xanthine oxidase in the depletion of serum antioxidants in rheumatic patients is discussed in the light of substrate availability and Km values.

Human autoantibodies to poly(adenosine diphosphate-ribose) polymerase recognize cross-reactive epitopes associated with the catalytic site of the enzyme.

The factors responsible for the production of autoantibodies against self-components are not well understood. We have identified monospecific human autoantibodies to poly(ADP-ribose) polymerase (ADPRP) in the sera of rheumatic patients. Since this nuclear enzyme has been extensively characterized, and its entire structure is known, we could investigate in detail the epitope specificity of the human autoantibodies, and their effects on the biological functions of the enzyme. All sera with autoantibodies to ADPRP recognized the NAD-binding domain of the enzyme, as demonstrated by either immunoblotting or immunoprecipitation of partially proteolyzed ADPRP. The autoantibodies also inhibited the catalytic activity of the purified enzyme, as measured by the transfer of ADP-ribose from [32P]NAD to either histones or to ADPRP itself. Because comparative structural analyses have shown that the active sites of enzymes are often conserved during evolution, we tested the ability of the autoantibodies to react with ADPRP from lower eukaryotes. The human autoantibodies reacted with ADPRP in cellular extracts from mammalian, avian, amphibian, arthropod, and protozoan cells, and also inhibited the catalytic activity of the various enzymes. Collectively, these experiments indicate that the human autoantibodies to ADPRP recognize a distinct group of evolutionarily conserved antigenic determinants that are closely related to the catalytic site of the enzyme. The results are consistent with the hypothesis that the epitope selectivity of human autoantibodies to ADPRP is influenced by cross-reactive antigens in the external environment.

Red cell enzyme types in rheumatic diseases.

We studied the frequencies of red cell enzyme types, AcP, PGM1 and EsD in 213 patients with rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), rheumatic heart disease (RHD), scleroderma (Scl) and psoriatic arthropathy (PsA). The differences in frequency of AcP phenotypes between RA, Scl, and PsA and the Moscow population were significant. In PsA the PGM1 phenotype 1-1 frequency was significantly decreased, while the phenotype 2-1 frequency was significantly increased.

Regulation of RNA polymerase I by phosphorylation and production of anti-RNA polymerase I antibodies in rheumatic autoimmune diseases.

Relative to resting liver, Morris hepatomas with different growth rates (3924A, 5123D, 7800, and 7777) all had higher (two to eightfold) levels (activity/gm tissue) of RNA polymerase I. Only the most rapidly growing tumor (hepatoma 3924A) showed a substantial increase (fivefold) in RNA polymerase III activity. RNA polymerase II activity/gm tissue in the hepatomas was similar to that in resting liver. The elevation in the hepatoma RNA polymerase I activity resulted from both an increase in the number of transcriptionally active enzyme molecules and an increase in the specific activity of the enzyme as a result of phosphorylation. Phosphorylation of RNA polymerase I from Morris hepatoma 3924A could be catalyzed either by an endogenous protein kinase or by a highly purified preparation of NII protein kinase from the same tumor. Three out of eight polypeptides (Mr 120,000, 65,000, and 25,000) or RNA polymerase I were phosphorylated. Phosphorylation resulted in enhanced RNA synthesis at the level of chain elongation. Another nuclear protein kinase, NI, had no significant effect on RNA polymerase I. The activity and/or amount of the NII protein kinase was significantly reduced in resting liver, which correlated with decreased specific activity of the liver RNA polymerase I. Anti-RNA polymerase I antibodies were found in the sera of patients with rheumatic autoimmune diseases such as systemic lupus erythematosus (SLE), mixed connective tissue disease (MCTD), and rheumatoid arthritis (RA). Sera from these patients were capable of specifically inhibiting RNA polymerase I activity in vitro. Antibodies were produced predominantly against three of the polypeptides--S3 (Mr 65,000), S4 (Mr 42,000), and S5 (Mr 25,000) of RNA polymerase I. The spectrum and proportion of the antibodies against these three subunits differ with each patient and with the type of the autoimmune disease. These observations indicate that (1) the NII kinase can regulate RNA polymerase I activity, (2) protein kinase NII is associated with the polymerase I enzyme complex, and (3) certain polypeptides of this enzyme complex may be the target antigens in rheumatic autoimmune disease.

Human collagenases: comparative and immunolocalization studies.

Four human collagenases derived from different tissues or cells were shown to have different physicochemical properties with regard to molecular size and protein charge. Such differences have been used to demonstrate that the collagenase activity of rheumatoid synovial fluids is of granulocytic origin. Immunolocalization studies have demonstrated that immunoreactive collagenase is present in a variety of human tissues. Its production by cells in normal tissues suggests a role in collagen remodelling processes, whereas its more frequent occurrence in diseased tissues suggests an important role in pathological collagen resorption. In nearly all the positive specimens examined the enzyme was restricted to a single cell or small groups of cells, or collagenous elements, suggesting microenvironmental rather than widespread collagenolytic activity.

Macrophage proteases and rheumatic diseases: regulation of plasminogen activator by thymus-derived lymphocytes.

Macrophages in culture secrete a variety of products including neutral protease activities such as plasminogen activator(s) (P.A.), collagenase and elastase. These products are not made by unstimulated macrophages, but only after induction by inflammatory stimuli, phagocytosis and lymphokines. Phagocytosis induces the prompt release of high levels of P.A. by endotoxin-primed macrophages and prolonged secretion follows uptake of non-degradable particles. Stimulation of lymphocytes results in the release of a supernatant product which enhances P.A. secretion by unstimulated mouse macrophages up to 5-fold. The production of the P.A. inducer (P.A.I.) is immunologically specific and is found in allogeneic mixed leukocyte culture (MLC) reactions, but not in syngeneic controls. The P.A. is also induced in activated macrophages from animals infected with BCG of T. cruzi and challenged with specific antigen. Production of the P.A.I. in MLC reactions depends on the presence of thymus-derived (T) lymphocytes and is closely correlated with the appearance of macrophage migration inhibition factor (MIF). The induction of macrophage P.A. and other proteases provides an important pathway for activating macrophages in delayed hypersensitivity reactions and could contribute significantly to tissue destruction in chronic inflammatory diseases in joints.