Protease inhibitors in inflammatory synovial effusions

Damage-associated molecular patterns generated in osteoarthritis directly excite murine nociceptive neurons through Toll-like receptor 4

OBJECTIVE

To determine whether selected damage-associated molecular patterns (DAMPs) present in the osteoarthritic (OA) joints of mice excite nociceptors through Toll-like receptor 4 (TLR-4).

METHODS

The ability of S100A8 and α2 -macroglobulin to excite nociceptors was determined by measuring the release of monocyte chemoattractant protein 1 (MCP-1) by cultured dorsal root ganglion (DRG) cells as well as by measuring the intracellular calcium concentration ([Ca(2+) ]i ) in cultured DRG neurons from naive mice or from mice that had undergone surgical destabilization of the medial meniscus (DMM) 8 weeks previously. The role of TLR-4 was assessed using TLR-4(-/-) cells or a TLR-4 inhibitor. The [Ca(2+) ]i in neurons within ex vivo intact DRGs was measured in samples from Pirt-GCaMP3 mice. Neuronal expression of the Tlr4 gene was determined by in situ hybridization. DMM surgery was performed in wild-type and TLR-4(-/-) mice; mechanical allodynia was monitored, and joint damage was assessed histologically after 16 weeks.

RESULTS

DRG neurons from both naive and DMM mice expressed Tlr4. Both S100A8 and α2 -macroglobulin stimulated release of the proalgesic chemokine MCP-1 in DRG cultures, and the neurons rapidly responded to S100A8 and α2 -macroglobulin with increased [Ca(2+) ]i . Blocking TLR-4 inhibited these effects. Neurons within intact DRGs responded to the TLR-4 agonist lipopolysaccharide. In both of the calcium-imaging assays, it was primarily the nociceptor population of neurons that responded to TLR-4 ligands. TLR-4(-/-) mice were not protected from mechanical allodynia or from joint damage associated with DMM.

CONCLUSION

Our experiments suggest a role of TLR-4 signaling in the excitation of nociceptors by selected DAMPs. Further research is needed to delineate the importance of this pathway in relation to OA pain.

Current serological possibilities for the diagnosis of arthritis with special focus on proteins and proteoglycans from the extracellular matrix

This review discusses our current understanding of how the expression and turnover of components of the cartilage extracellular matrix (ECM) have been investigated, both as molecular markers of arthritis and as indicators of disease progression. The cartilage ECM proteome is well studied; it contains proteoglycans (aggrecan, perlecan and inter-α-trypsin inhibitor), collagens and glycoproteins (cartilage oligomeric matrix protein, fibronectin and lubricin) that provide the structural and functional changes in arthritis. However, the changes that occur in the carbohydrate structures, including glycosaminoglycans, with disease are less well studied. Investigations of the cartilage ECM proteome have revealed many potential biomarkers of arthritis. However, a clinical diagnostic or multiplex assay is yet to be realized due to issues with specificity to the pathology of arthritis. The future search for clinical biomarkers of arthritis is likely to involve both protein and carbohydrate markers of the ECM through the application of glycoproteomics.

The epidemiology and outcome of acute septic arthritis: a hospital based study

BACKGROUND

Septic arthritis is an acute bacterial infection affecting synovial joints. It is an orthopaedic emergency with potential high morbidity and mortality. This study determined the epidemiological pattern and outcome of acute septic arthritis and analyzed factors affecting morbidity and mortality Methods:This is a 5 year (2007-2012) retrospective study conducted at NKST rehabilitation hospital Mkar, North -Central Nigeria. All patients with septic arthritis upon presentation were consecutively selected. Patients with clear, non-purulent or haemorrhagic joint aspirate and those with incomplete data were excluded from the study. Data was analysed using SPSS version 21.

RESULTS

A total of 30 patients with 35septic joints were studied. Eighteen (60%) were males and 12(40%) were female with a male to female ratio of 1.5:1. Age range was 3months and 75years. The knee was the commonest 16(45.7 %) joint involved followed by the hip joint 11(31.4%). Staphylococcus aureus was the commonest organism cultured in joint aspirate in 19 (54.3%) patients and postoperative complications include joint stiffness 2(5.7%), painand stiffness 3(8.6%), bony ankylosis2(5.7%) and limb shortening 1(2.9%).

CONCLUSION

Early accurate diagnosis and prompt interventionare crucial for a successful outcome. Appropriate drainage of septic joints and antibiotic treatment can result in prompt recovery with minimum or no long term morbidity. Close follow-up is needed to monitor the growth of the affected limbs until skeletal maturity. There is a need to maintain a high index of suspicion and to educate patients about early presentation, early referral, avoidance of improper use of antibiotics and regular follow-up after the acute pathology.

The role of ADAMTSs in arthritis

The ADAMTS (a disintegrin and metalloproteinase with thrombospondin motifs) family consists of 19 proteases. These enzymes are known to play important roles in development, angiogenesis and coagulation; dysregulation and mutation of these enzymes have been implicated in many disease processes, such as inflammation, cancer, arthritis and atherosclerosis. This review briefly summarizes the structural organization and functional roles of ADAMTSs in normal and pathological conditions, focusing on members that are known to be involved in the degradation of extracellular matrix and loss of cartilage in arthritis, including the aggrecanases (ADAMTS-4 and ADAMTS-5), ADAMTS-7 and ADAMTS-12, the latter two are associated with cartilage oligomeric matrix protein (COMP), a component of the cartilage extracellular matrix (ECM). We will discuss the expression pattern and the regulation of these metalloproteinases at multiple levels, including their interaction with substrates, induction by pro-inflammatory cytokines, protein processing, inhibition (e.g., TIMP-3, alpha-2-macroglobulin, GEP), and activation (e.g., syndecan-4, PACE-4).

Superficial zone chondrocytes in normal and osteoarthritic human articular cartilages synthesize novel truncated forms of inter-alpha-trypsin inhibitor heavy chains which are attached to a chondroitin sulfate proteoglycan other than bikunin

OBJECTIVE

We have examined the occurrence of the inflammation-associated inter-alpha-trypsin inhibitor (IalphaI) components, bikunin, heavy chain (HC)1 and HC2 in normal cartilage and osteoarthritis (OA) cartilage and synovial fluids.

DESIGN/METHODS

Cartilage extracts from normal donors and late-stage OA patients, and synovial fluids from OA patients were studied by Western blot with multiple antibodies to bikunin, HC1 and HC2. Cell and matrix localization was determined by immunohistochemistry and mRNA by RT-PCR.

RESULTS

Bikunin.chondroitin sulfate (CS) and IalphaI were abundant in OA cartilages, but virtually undetectable in normal. In both OA and normal cartilages, HCs were largely present in a novel C-terminally truncated 50-kDa form, with most, if not all of these being attached to CS on a proteoglycan other than bikunin. Synovial fluids from OA patients contained bikunin.CS and full-length (approximately 90 kDa) HCs linked to hyaluronan (HA) as HC.HA (SHAP.HA). Immunohistochemistry showed intracellular and cell-associated staining for bikunin and HCs, consistent with their synthesis by superficial zone chondrocytes. PCR on multiple human normal and OA cartilage samples detected transcripts for HC1 and HC2 but not for bikunin. In OA cartilages, immunostaining was predominantly matrix-associated, being most intense in regions with a pannus-like fibrotic overgrowth.

CONCLUSION

The truncated structure of HCs, their attachment to a proteoglycan other than bikunin, PCR data and intracellular staining are all consistent with synthesis of HC1 and HC2 by human articular chondrocytes. The presence of bikunin.CS and IalphaI in OA cartilage, but not in normal, appears to be due to diffusional uptake and retention through fibrillated (but not deeply fissured) cartilage surfaces.

Septic arthritis in Western and sub-Saharan African children - a review

This article reviews what is known about the incidence, aetiology, presentation, bacteriology and management of septic arthritis in children. It compares where possible the different presentations and characteristics of this condition in the Western and sub-Saharan African regions.

α2-Macroglobulin Is a Novel Substrate for ADAMTS-4 and ADAMTS-5 and Represents an Endogenous Inhibitor of These Enzymes

Osteoarthritis is characterized by the loss of aggrecan and collagen from the cartilage extracellular matrix. The proteinases responsible for the breakdown of cartilage aggrecan include ADAMTS-4 (aggrecanase 1) and ADAMTS-5 (aggrecanase 2). Post-translational inhibition of ADAMTS-4/-5 activity may be important for maintaining normal homeostasis of aggrecan metabolism, and thus, any disruption to this inhibition could lead to accelerated aggrecan breakdown. To date TIMP-3 (tissue inhibitor of matrix metalloproteinases-3) is the only endogenous inhibitor of ADAMTS-4/-5 that has been identified. In the present studies we identify alpha(2)-macroglobulin (alpha(2)M) as an additional endogenous inhibitor of ADAMTS-4 and ADAMTS-5. alpha(2)M inhibited the activity of both ADAMTS-4 and ADAMTS-5 in a concentration-dependent manner, demonstrating 1:1 stoichiometry with second-order rate constants on the order of 10(6) and 10(5) m(-1) s(-1), respectively. Inhibition of the aggrecanases was mediated by proteolysis of the bait region within alpha(2)M, resulting in physical entrapment of these proteinases. Both ADAMTS-4 and ADAMTS-5 cleaved alpha(2)M at Met(690)/Gly(691), representing a novel proteinase cleavage site within alpha(2)M and a novel site of cleavage for ADAMTS-4 and ADAMTS-5. Finally, the use of the anti-neoepitope antibodies to detect aggrecanase-generated alpha(2)M-fragments in synovial fluid was investigated and found to be uninformative.

Determination of cathepsins B and H in sera and synovial fluids of patients with different joint diseases

Synovial fluids and sera of patients with inflammatory and metabolic joint diseases contain different cysteine proteinases. The quantities of cathepsins B and H were determined by newly developed specific enzyme-linked immunoassay tests (ELISA), with detection limits of 0.5 microgram/l for cathepsin B and 3 micrograms/l for cathepsin H. The values of cathepsin B in normal sera ranged from 0.6 microgram/l to 2 micrograms/l, whereas in sera of patients with joint diseases they ranged from 1.7 micrograms/l to 18 micrograms/l. Cathepsin H was not found in sera (values below 3 micrograms/l), but was measurable in patients' synovial fluids. Patients with rheumatoid arthritis have on average the highest values of cathepsin B in synovial fluids, whereas patients with undifferentiated arthritis have the highest values of cathepsin H. The results show that cathepsins B and H are present in arthritic synovial fluids, where they may be implicated in destructive processes. There is yet no clear correlation between the quantity of each cathepsin released in synovia and the clinical diagnosis or the stage of the disease.

Correlation between synovial neopterin and inflammatory activity in rheumatoid arthritis

According to recent investigations neopterin (a pyrazinopyrimidine derivative) is a biochemical marker that reflects the activity of the proinflammatory immunocellular system of the synovial tissue in rheumatoid arthritis (RA). Interferon gamma, derived from antigen activated T lymphocytes, stimulates macrophages to synthesise and release neopterin into the culture supernatant in vitro. To extend this in vitro model to a clinical level a sensitive new radioimmunoassay technique was used to measure neopterin concentrations in the synovial fluid (SF) of 17 patients with active RA, nine with osteoarthritis, and six with acute gout, and in that of 12 controls undergoing meniscectomy. The SF neopterin concentrations were significantly higher in patients with RA than in the other groups of patients, particularly the controls. Multivariant analysis showed that SF neopterin concentrations correspond better with the systemic inflammatory activity of RA than with the local disease activity of the knee joints. Thus the study strengthens the hypothesis that neopterin reflects the essential role of the activated immunocellular reaction in the pathogenesis of RA.

Induction of articular cartilage degradation by recombinant interleukin 1 alpha and 1 beta

The purpose of this study was to compare the effects of human recombinant interleukin 1, alpha and beta, on articular cartilage. The effects of rIL-1 alpha and rIL-1 beta on proteoglycan degradation and synthesis following treatment of bovine articular cartilage in serum-free organ culture were quantified. Purified human IL-1 and both rIL-1 alpha and rIL-1 beta induced a two-fold or greater increase in glycosaminoglycan (GAG) release from cultured articular cartilage. Levels or rIL-1 alpha as low as 15 pM induced increased proteoglycan degradation whereas identical levels of rIL-1 beta did not. Killing of the cartilage cells abolished induced GAG release by all forms of IL-1. Analysis of proteoglycan size following IL-1 treatment showed limited degradation of material released into the culture medium or remaining within cartilage. Both forms of recombinant IL-1 inhibited GAG synthesis when continually present in the culture medium. Actinomycin D and cycloheximide inhibited IL-1 dependent cartilage destruction whereas indomethacin did not.

Interference of cartilage surface with interaction of granulocyte elastase with alpha 1-proteinase inhibitor. An in vitro model of enzyme inhibition in the joint space

Synovial fluids of patients suffering from rheumatoid arthritis contain elevated levels of granulocyte (PMN) elastase in complex with alpha 1-proteinase inhibitor (alpha 1-PI), whereas free-elastase activity is usually not detectable. This absence of free enzymatic activity in joint effusions has cast some doubt on the pathophysiological relevance of PMN elastase in inflammatory joint destruction. Our in vitro experiments using bovine nasal cartilage demonstrate that incubation with elastase and alpha 1-PI in equimolar concentrations to or even in excess of the serum proteinase inhibitor resulted in significant tissue destruction as assessed by histological staining for proteoglycans, release of uronic acid from the matrix and loss of mechanical stability. Though in the supernatants containing alpha 1-PI, free-elastase activity was not detectable, immunofluorescent staining for elastase evidenced penetration of the enzyme into the matrix. Simultaneous measurements of the incubation media employing a sandwich enzyme-linked immunoadsorption assay (ELISA) revealed PMN elastase in complex with alpha 1-PI but without correlation to the parameters of tissue degradation. In comparison with the results obtained using the chromogenic substrate Suc-Ala-Ala-Ala-pNA (SAPA) for titration of alpha 1-PI against elastase, the employment of cartilage matrix showed that a fourfold increase in inhibitor concentration was necessary to achieve 100% enzyme inhibition. Hence, cartilage surface obviously interferes with the interaction between alpha 1-PI and elastase. Measurements of elastase-inhibitor concentrations or free enzymatic activity in synovial fluid seem to have limited value in predicting cartilage destruction.

Modulation of cartilage destruction by select nonsteroidal antiinflammatory drugs. In vitro effect on the synthesis and activity of catabolism-inducing cytokines produced by osteoarthritic and rheumatoid synovial tissue

Non-enzymatic factors produced by synovial tissue can potentially mediate cartilage destruction by inducing the synthesis and release of matrix-degrading proteinases from chondrocytes. Pharmacologic control of this process is of potential clinical relevance. The in vitro effect of therapeutic concentrations of select nonsteroidal antiinflammatory drugs on the synthesis and activity of catabolism-inducing cytokines produced by 6-day explant cultures of osteoarthritic and rheumatoid synovial tissue was studied. Piroxicam regularly suppressed such factor synthesis by both types of tissue without significantly affecting total protein synthesis. This did not occur using sodium salicylate or indomethacin in osteoarthritis tissue cultures and was observed only occasionally in rheumatoid arthritis cultures. None of the nonsteroidal antiinflammatory drugs studied consistently blocked catabolism-inducing activity in osteoarthritis tissue, whereas piroxicam more consistently inhibited activity produced by rheumatoid arthritis tissue. Results suggest that the catabolism-inducing factors produced by the 2 tissue sources may differ.

Immunological aspects of the rheumatoid synovium

The characteristics of the immunocompetent lymphoid cells which have invaded the synovial membrane during rheumatoid arthritis, juvenile rheumatoid arthritis and related disorders are briefly reviewed. Various functional aspects of these cells are also discussed.

A modified double antibody sandwich enzyme-linked immunosorbent assay for measurement of alpha-1-antitrypsin in biologic fluids

Alpha-1-antitrypsin (alpha 1AT) is the major protease inhibitor in human serum, and plays an important role protecting tissues from potentially harmful enzymes released during inflammatory reactions. Proteolytic enzymes such as leukocyte elastase are usually released and inactivated locally at the site of inflammation, so there has been much recent interest in measuring local alpha 1AT concentrations in biologic fluids. In this study, we developed a modified double antibody sandwich enzyme-linked immunosorbent assay (ELISA) and used it to measure alpha 1AT concentrations in several biologic fluids. The assay was sensitive to as little as 20 ng/ml of alpha 1AT. Serum concentrations measured by the ELISA correlated well with levels determined by radial immunodiffusion (RID) and the ELISA was far more sensitive than RID. In synovial fluid, higher concentrations determined by the ELISA compared with RID probably reflect interference of diffusion of alpha 1AT in the RID gel by hyaluronic acid and protease-inhibitor complexes. Synovial fluid did not interfere with the detection of added alpha 1AT by ELISA, but it did reduce the amount detected by RID by about 30% in 2 fluids. In saliva, alpha 1AT concentrations of less than 1 microgram/ml were easily quantified. Bronchoalveolar lavage fluids have been extensively studied because of the important role of alpha 1AT in pulmonary inflammatory processes. We found concentrations of 1-3 micrograms/ml in most samples with our assay. These levels were comparable to those previously reported with assays that required up to 50-fold concentration of the fluid. Neither saliva nor bronchoalveolar fluid significantly interfered with detection by ELISA of added alpha 1AT. This modified double antibody sandwich ELISA may have broad applications for studies of the role of alpha 1AT in health and disease.

Influence of the severity and duration of murine antigen-induced arthritis on cartilage proteoglycan synthesis and chondrocyte death

Recent studies have shown that joint inflammation can suppress chondrocyte proteoglycan synthesis and can even kill chondrocytes. In the present study, we investigated the influence of the severity and chronicity of murine antigen-induced arthritis on the degree of these toxic effects on chondrocytes. Joint inflammation, quantitated by measurements of 99m technetium pertechnetate uptake, was significantly correlated with the inhibition of proteoglycan synthesis, measured by 35S-sulfate incorporation. Histologic grading of the extent of chondrocyte death on day 28 after arthritis induction correlated best with the degree of inflammation present on day 14. High scores for chondrocyte death were found only in mice with persistent, severe arthritis. Our data indicate that the severity of joint inflammation is a major determinant of the degree of chondrocyte proteoglycan synthesis inhibition, whereas both the severity and chronicity of the inflammation determine chondrocyte killing and, therefore, irreversible joint destruction.

Nonsteroidal anti-inflammatory drugs and modulation of cartilaginous changes in osteoarthritis and rheumatoid arthritis. Clinical implications

Nonsteroidal anti-inflammatory drugs have a potential for modifying the complex pathophysiologic events leading to cartilage destruction in various forms of arthritis. Following an evaluation of basic mechanisms in the pathogenesis of cartilaginous destructive lesions, the effects of nonsteroidal anti-inflammatory drugs on normal chondrocyte metabolism are discussed. Their capacity to modulate cartilage and bone lesions in experimental forms of arthritis is addressed, as is the manner in which they may modify the pathophysiology of cartilage destruction in human forms of arthritis. Different classes of nonsteroidal anti-inflammatory drugs produce different effects in certain in vivo or in vitro settings.

Cytokine modulation of chondrocyte metabolism--in vivo and in vitro effects of piroxicam

Changes in the macromolecular proteolycan (PG) and collagen of the cartilage matrix may culminate in irreparable tissue destruction. Molecular modifications appear to result from: (A) exogenous proteinases, (B) endogenous chondrocyte proteinases whose synthesis and release is modulated by exogenous non-enzymatic cytokines (CKs) and (C) quantitative and/or qualitative alterations in chondrocyte PG and collagen synthesis which are potentially induced by exogenous CKs. Studies have recently been initiated to determine the effect of piroxicam on the synthesis and activity of such metabolic regulatory CKs in patients with rheumatoid arthritis and osteoarthritis, and in age-, sex-, and race-matched controls. Therapeutic doses of piroxicam alone had no effect on the anabolic or catabolic function of chondrocytes. Current studies concern the effect of piroxicam on: (a) spontaneous and lectin-driven production by peripheral blood monocytes and T-cells of trypsin-sensitive, heat-labile CKs (interleukin 1, lymphokine) which, in a protein- and RNA-synthesis-dependent manner, induce a concentration and duration of substrate exposure dependent release of chondrocyte PG- and collagen- degrading neutral proteinases in cartilage organ and chondrocyte suspension culture systems; (b) spontaneous and lectin-driven synthesis by peripheral blood T-cells of lymphokines capable of suppressing chondrocyte PG, glycosaminoglycan, protein, collagen and nucleic acid synthesis in a quantitatively reversible manner; (c) pathological synovial membrane synthesis of such catabolic-inducing and anabolic-modulatory CKs. These experimental model system are reviewed together with preliminary data on the effect of piroxicam.

Metalloproteinases and collagenase inhibitors in rheumatoid synovial fluid

The levels of metalloproteinases and metalloproteinase inhibitors were measured in rheumatoid synovial fluid. Reliable estimates of total enzyme and inhibitor levels in the synovial fluids were obtained only after hyaluronidase treatment and gel filtration. Three latent metalloproteinases were found which, after activation, degraded collagen, proteoglycan, and gelatin. These enzymes closely resembled the metalloproteinases secreted into connective tissue culture medium. In addition to alpha 2 macroglobulin, an Mr 30,000 collagenase inhibitor was detected which closely resembled the tissue inhibitor of metalloproteinase found in tissue culture medium.

Synovial protease/inhibitor ratios in erosive and nonerosive arthropathies

Although rheumatoid joint fluids contain numerous polymorphs capable of secreting neutral proteases known to be able to digest cartilage, the high level of inhibitors (mainly alpha 1-antitrypsin and alpha 2-macroglobulin) has always been considered to be more than sufficient to inhibit their activity completely. Consequently little interest has been paid to the potential role of these enzymes in cartilage damage. Four arthropathies of different erosive potential are here compared: spondyloarthropathies, rheumatoid arthritis with and without gold or D-penicillamine therapy, and septic arthritis. The synovial concentration of the inhibitors alpha 1-antitrypsin and alpha 2-macroglobulin has been compared with the polymorph enzyme output, as measured by beta-glucuronidase. Total haemolytic complement, white cell count, and C-reactive protein have also been measured in the joint fluid. The range of white cell count and inhibitors was the same in all 4 groups, while the enzyme output varied substantially from low levels in the spondyloarthropathies to very high levels in the septic joints. The higher the erosive potential of the disease, therefore, the more disadvantageous is the inhibitor/enzyme ratio. It is also pointed out that cartilage has physiochemical properties which facilitate and enhance polymorph enzyme output while severely curtailing the activity of the inhibitors. The observation that synovial fluid is inhibitory in vitro may therefore bear little relationship to the situation at the cartilage surface in vivo.

Polymorphonuclear granulocytes in rheumatic tissue destruction. VI. The occurrence of PMNs in menisci of patients with rheumatoid arthritis

The meniscal surfaces from patients with and without inflammatory joint diseases were investigated for the presence of superficially located polymorphonuclear granulocytes (PMNs). In histochemically stained tissue sections as well as in electron microscopic investigations on previously paraffin-embedded menisci, PMNs were observed in cases with inflammatory rheumatoid joint diseases. The inflammatory cells were located in fibrin adhering to the meniscal surface and in the fibrous meniscal tissue just beneath the fibrin. From these observations it is concluded that PMNs in the inflammatory synovial fluid may gain access to the fibrous structures of the joint, thus participating in tissue destruction, as has been assumed from in vitro investigations by other authors.

Cytokine modulation of chondrocyte proteinase release

Nonenzymatic, trypsin sensitive cytokines derived from lectin stimulated normal human mononuclear cells have been shown to induce release of proteoglycan and collagen degrading proteinase activity from chondrocytes in cartilage organ and isolated suspension culture systems. Active chondrocyte protein and RNA synthesis were required to induce activity. Cytokines responsible were of both monocyte and T cell origin. Direct monokine catabolic induction and monokine/lectin-triggered lymphokine inducing activity could be demonstrated. Cyclooxygenase inhibitors and direct or indirect modulation of mononuclear cell or chondrocyte cAMP levels had no effect on factor synthesis or activity. Hydrocortisone abrogated the effect. Cytokines responsible were heat labile, unaffected by reduction/alkylation or neuraminidase exposure, and stable over a pH range of 3-10.

Mechanisms of mediator release from neutrophils

The encounter of neutrophils with immune complexes and complement components - in the bulk phase or on a surface - leads to their secretion of lysosomal hydrolases, especially neutral proteases, which provoke tissue injury. Secretion of lysosomal enzymes and generation of reactive oxygen species (e.g., O2-. generation are stimulus-specific and can be dissected to establish cause and effect relationships by means of: a) kinetic analysis, b) variations in the stimulus, and c) use of impermeant reagents to block discrete responses. Neutrophils also generate products of 11-cyclooxygenase (e.g., PGE2, TxA2) and of the 5- and 15-lipoxygenases (mono-, di-, and tri-HETEs, LTB4, and their isomers). But the cyclooxygenase products (save TxA2) are not phlogistic by themselves: they inhibit the functions of neutrophils, platelets, macrophages, and mast cells. The most potent pro-inflammatory agent yet identified as a product of arachidonate is LTB4. LTB4 is a potent Ca ionophore, constricts airways, is a potent chemoattractant, and induces local inflammation.

Articular patterns in the early course of rheumatoid arthritis

Articular patterns of rheumatoid arthritis were determined based upon the numbers of joints found to be tender or swollen in 50 younger adult patients with early-diagnosed rheumatoid arthritis examined semi-annually over a mean interval of 5.7 years. Numbers of joints involved were analyzed according to (1) cross-sectional frequency distributions, (2) cumulative probability plots of each patient's linear regression slope during follow-up, and (3) clinically intuitive definitions of course patterns. These approaches converged on three articular patterns, that is, monocyclic, polycyclic, and progressive. Monocyclic course was observed more frequently in men, in patients without rheumatoid factor, and in those with the fewest numbers of joints involved at entry. Polycyclic course was the most common and characterized by a level regression slope of involved joints during follow-up, although fluctuating over time. This course could be subdivided into the intermittent (having at least one remission of joint involvement for at least six months) and the continuing patterns. Progressive course was least common and found in patients with the greatest numbers of joints involved at entry. These data indicate that articular patterns in rheumatoid arthritis are usually established within the early course of disease. Further study of the early course of rheumatoid arthritis should be pursued for proper understanding of its host determinants, prognostic factors, and optimal patient management.

Stimulation of murine macrophage cathepsin B by serum from patients with rheumatoid arthritis: an indicator of disease activity

Cultures of non-elicited mouse peritoneal macrophages were used as a test system to study the effect of sera from patients with rheumatoid arthritis (RA) on intra-cellular cathepsin B activity of macrophages. Sequential sera obtained during and after pregnancy from six RA patients, and sera from six actively ill, non-pregnant RA patients were compared to six healthy female controls and 3rd trimester healthy women. Sera from actively ill RA patients (both pregnant and non-pregnant) caused macrophage cathepsin B levels significantly above normal controls, while intra-cellular activities of beta-glucuronidase and N-acetyl-glucosaminidase did not differ from the controls. A significant correlation between activity of RA and intracellular cathepsin B was found in pregnant patients. It is suggested that a factor (or factors) present in serum from patients with active RA causes a rise of intracellular cathepsin B in macrophages.

Neutrophils: release of mediators of inflammation with special reference to rheumatoid arthritis

The encounter of neutrophils with immune complexes and complement components, in the bulk phase or on a surface, leads to their secretion of lysosomal hydrolases, especially neutral proteases, which provoke tissue injury. Secretion of lysosomal enzymes and generation of reactive oxygen species (e.g., O(2)) is part of a stimulus-secretion response to a variety of secretagogues, including immune complexes and complement components. However, the pathways of secretion and O(2) generation are stimulus-specific and can be dissected to establish cause and effect relationships by means of: a) kinetic analysis, b) variations in the stimulus, and c) use of impermeant reagents to block discrete responses. Neutrophils also generate products of 11-cyclooxygenase (e.g., PGE2, TxA2) and of the 5-and 15-lipoxygenases (mono-, di-, and tri-HETEs, LTB4, and their isomers). But the cyclooxygenase products (save TxA2) are not phlogistic by themselves: they inhibit the functions of neutrophils, platelets, macrophages, and mast cells. The most potent pro-inflammatory agent yet identified as a product of arachidonate is LTB4. LTB4 is a potent Ca ionophore, constricts airways, is a potent chemoattractant, and induces local inflammation.