Circulating human leucocyte elastase in rheumatoid arthritis

Comparison of maternal and cord blood polymorphonuclear leukocyte elastase levels

The main objective of this study was to examine the influence of parturition on the polymorphonuclear leukocyte elastase release in the fetus and the mother. There were 32 babies and parturients. The mean arterial cord blood elastase level was 294.8 +/- 129.15 ng/ml (median 304.25), while the mean plasma (venous) level in the adult normal controls was 35.66 +/- 14.1 ng/ml. The difference was highly significant at p < 0.0001 (Student's t test, two-tailed). The mean elastase level of the mothers was 143.45 +/- 109 ng/ml (median 115.25). This was significantly lower than the mean arterial cord blood elastase level (p < 0.0001) but higher than the mean elastase level in healthy adults (p < 0.0001). The mean cord blood and the mothers' white blood cell counts were 11.9 +/- 3.1 (median 11.8, range 6.3-18.7 x 10(9)/l) and 12.4 +/- 2.8 (median 12.4, range 7.3-17.1 x 10(9)/l) respectively. The difference was not statistically significant (p = 0.4). The WBC counts correlated significantly with the mothers' (r = 0.4, p = 0.03) and cord blood (r = 0.7, p < 0.0001) elastase levels. These results suggest that the raised arterial cord blood elastase levels during parturition may reflect the disturbance of fetal homeostasis during parturition.

Suppressive effects of hyaluronic acid on elastase release from rat peritoneal leucocytes

Effects of hyaluronic acid on the release of elastase from rat peritoneal leucocytes were studied by measuring the leucocyte elastase activity using a synthetic peptide substrate. Leucocyte elastase release was induced by opsonized zymosan, 12-O-tetradecanoyl phorbol-13-acetate (TPA) and N-formyl-L-methionyl-L-leucyl-L-phenylalanine combined with cytochalasin B. Calcium ionophore A23187 potentiated the action of TPA on leucocyte elastase release, whereas hyaluronic acid inhibited leucocyte elastase release regardless of the method of stimulation. Inhibitory effects of hyaluronic acid were dependent on its concentration and molecular weight. Hyaluronic acid of the highest molecular weight (2.0 x 10(6)) indicated a potent inhibitory effect on elastase release. Our present findings suggest that hyaluronic acid may elicit an anti-inflammatory effect by inhibiting leucocyte elastase-dependent pathological processes.

Markers of bone and collagen breakdown in early inflammatory arthritis

Inflammatory arthritis has the potential to cause irreversible erosive damage to cartilage and bone. This may occur very early in the course of the disease. At present it is not possible at diagnosis to identify those patients who will develop erosive damage. If this were possible, it would enable aggressive therapy to be targeted to those patients at greatest risk. There is therefore a need for sensitive markers to detect and quantify joint damage at as early a stage as possible. In this chapter we review potential biochemical markers of such damage and assess their clinical usefulness.

Predominant role of neutrophils in the inactivation of alpha 2-macroglobulin in arthritic joints

We studied the state of alpha 2-macroglobulin (alpha 2M), an important inhibitor of cartilage-degrading proteinases, in relation to activation of neutrophils in 82 patients with several types of arthritis, including 52 with rheumatoid arthritis and 11 with osteoarthritis. Levels of total inactive alpha 2M (i alpha 2M), which comprises alpha 2M complexed to proteinases and alpha 2M inactivated by oxidation or hydrolysis, were measured with a monoclonal antibody specific for i alpha 2M. In addition, levels of alpha 2M complexed to proteinases were quantitated with specific assays. Neutrophil activation was assessed by measuring elastase-alpha 1-antitrypsin complexes and lactoferrin. In 83% of the 82 patients tested, the synovial fluid (SF) to plasma ratio of i alpha 2M exceeded 1, indicating an intraarticular generation. Levels of i alpha 2M significantly correlated with neutrophil numbers (P less than 0.0005) and with levels of elastase-alpha 1-antitrypsin complexes and of lactoferrin (P less than 0.00001 for both). Moreover, part of i alpha 2M consisted of alpha 2M complexed to elastase-like and chymotrypsin-like proteinases, presumably, neutrophil elastase and cathepsin G, respectively. However, the amount of i alpha 2M was approximately 10-fold larger than the amount complexed to these proteinases. In vitro inactivation of alpha 2M by activated neutrophils was only partly inhibitable by eglin C, a specific inhibitor of both elastase and cathepsin G. Release of reactive oxygen species was presumably responsible for the additional inactivation of alpha 2M, because eglin C completely abolished the inactivation of alpha 2M by cell-free supernatant of activated neutrophils. Thus, our results suggest a predominant role of neutrophils in the inactivation of alpha 2M in the SF of patients with inflammatory joint diseases. However, this inactivation could be explained only in part by the release of neutrophilic proteinases. We propose that the inactivation of alpha 2M in SF was due to the concerted action of both reactive oxygen species and lysosomal proteinases.

Role of granulocyte elastase in tissue injury in patients with septic shock complicated by multiple-organ failure

To better understand the role of granulocyte elastase (GE) in mediating tissue injury during sepsis, GE levels were measured in plasma and bronchoalveolar lavage fluid (BALF) in patients with septic shock (n = 16) and hemorrhagic shock (n = 30). Granulocyte elastase levels were compared to levels of alpha 1-protease inhibitor (alpha 1-PI). Results show that although plasma GE-alpha 1-PI complex was initially elevated in patients with hemorrhagic and septic shock, elevations in plasma GE-alpha 1-PI complex (831 +/- 241 micrograms/L) persisted in septic shock patients. alpha 1-Protease inhibitor levels in serum were increased, resulting in an inhibition of serum GE activity. Granulocyte elastase activity in BALF, however, was significantly higher in those patients with septic, as compared to hemorrhagic shock (31.4 +/- 25.8 versus 3.7 +/- 4.0 U/L, respectively). In addition GE levels were compared to other parameters, including respiratory index, blood neutrophil count, and plasma levels of endotoxin, fibronectin, and coagulation factor XIII. Significant correlations were observed between GE-alpha 1-PI and increased endotoxin concentration and decreased fibronectin and coagulation factor XIII levels. Significant correlation was found also between GE activity in BALF and respiratory index. These findings suggest that severe tissue damage occurred in patients with septic shock complicated by multiple-organ failure. Although GE activity appeared to be adequately inhibited by alpha 1-PI in blood, increased GE activity in local tissues, such as lung alveoli, may be responsible for significant local tissue injury during septic shock.

The leukocyte protein L1 in plasma and synovial fluid from patients with rheumatoid arthritis and osteoarthritis

L1 is a major granulocyte and monocyte protein, released during activation and turnover of such cells. Blood and synovial fluid (SF) from 41 patients with rheumatoid arthritis (RA) and 6 patients with osteoarthritis (OA), were analyzed for L1 and the acute phase proteins C-reactive protein, orosomucoid, haptoglobin, alpha 1-antitrypsin and albumin as well as for differential leukocyte count. L1 levels in plasma and SF showed highly significant differences (p less than 0.0001), between the RA and OA patients. All the OA patients had normal plasma concentrations of L1 and low concentrations of L1 in SF. All the RA patients had elevated plasma levels of L1 and high L1 concentrations in SF. In the RA patients, the ratios between the protein concentrations in SF and blood were 3.29 for L1 and less than or equal to 0.64 for the acute phase proteins. In the SF, the L1 levels did not correlate with the monocyte count, while a low, positive correlation was found between L1 and the granulocyte count. The high L1 concentrations observed in SF from RA patients probably reflected an increased turnover of leukocytes in the inflamed joints. In SF from RA patients, high L1 concentrations were found in joints with a high amount of swelling. The present study suggests that L1 may represent a marker of both local and systemic inflammation.

Cytidine deaminase activity in synovial fluid of patients with rheumatoid arthritis: relation to lactoferrin, acidosis, and cartilage proteoglycan release

It is claimed that cytidine deaminase activity reflects local granulocyte turnover or activity in the synovial fluid of patients with rheumatoid arthritis, but cytidine deaminase is not a granulocyte specific enzyme. Lactoferrin is a granulocyte specific protein that is released from the secondary granulae during activation. We measured cytidine deaminase activity and lactoferrin concentrations in 33 rheumatic synovial fluid samples. Cytidine deaminase activity and lactoferrin concentrations correlated closely, indicating that both analyses reflect similar events in the joint-that is, result in their release from granulocytes. Cytidine deaminase activity and granulocyte concentrations correlated less closely, suggesting that there are additional factors besides the cell number which contribute to this release. Joint acidosis may be one such factor, as pH and cytidine deaminase activity correlated inversely. There was no association with synovial fluid proteoglycan concentrations, a marker of cartilage degradation.

The effect of some anti-inflammatory agents on elastase release from neutrophils in-vitro

In view of the potential role of released polymorphonuclear leucocyte elastase in causing tissue damage, the effect of commonly used anti-inflammatory drugs on elastase release from neutrophils has been studied in-vitro. Elastase release from neutrophils exposed to the synthetic bacterial cell wall peptide N-formyl-L-methionyl-L-leucyl-L-phenylalanine (10(-6) M) was quantitated using a radiometric immunoassay and a functional assay of elastase. Prednisolone and non-steroidal anti-inflammatory drugs inhibited elastase release at concentrations from 0.1 mM-0.1 nM. No inhibition by sulphosalicylic acid, D-penicillamine or chloroquine sulphate was observed. The clinical relevance of these findings is discussed.

Molecular distribution of elastase between its two main inhibitors: direct quantitation of elastase-alpha 2-macroglobulin complex with a novel ELISA technique

A novel enzyme-linked immunosorbent assay for the quantitation of elastase linked to alpha 2-macroglobulin (alpha 2M) (elastase-alpha 2M complex, EMC) in body fluids is presented. The assay has a lower detection limit of 1.5 ng bound elastase per ml. The critical factor allowing immunological detection of alpha 2M-bound elastase is the addition of phenyl methyl sulphonyl fluoride (PMSF) to the assay buffer. The assay has been used to quantitate EMC in plasma and serum of healthy volunteers, and assess the distribution of elastase between its two main inhibitors, alpha 2M and alpha 1-proteinase inhibitor (API). EMC levels in serum samples from volunteers were significantly higher than in plasma (26.9 vs 21.9 ng/ml, p = 0.05, Student's t-test for paired samples). The API-bound elastase levels were 70.2 and 170.1 ng/ml in plasma and serum respectively (statistically significantly higher in serum, p less than 0.0001). The ratio of macroglobulin to alpha 1-proteinase-bound elastase levels was 0.333 in plasma and 0.168 in serum (p less than 0.0001). As alpha 2M bound elastase retains some proteolytic activity, direct measurement of circulating levels in inflammatory conditions should be of interest.

Plasma and synovial fluid levels of granulocytal elastase-alpha-1-protease inhibitor complex in patients with rheumatoid arthritis

Plasma and synovial fluid levels and granulocytal elastase-alpha-1-protease inhibitor complex (EIC) in patients with rheumatoid arthritis (RA) were measured by enzyme-linked immunoassay and the results compared with those in patients with osteoarthrosis (OA). It was found that the plasma and synovial fluid levels of EIC in RA patients were higher than those in OA patients. There was a positive correlation between plasma EIC level in RA patients in Lansbury's index score of disease activity, as this tends to be higher when titer of RAHA in the plasma is high. The level of EIC in the synovial fluids correlated positively with granulocyte count and alpha-1-protease inhibitor (alpha-1-PI) level, and this, too, tends to be higher when titer of RAHA in synovial fluid is high. The results suggested that the level of EIC in the plasma or synovial fluids can be a good marker for the systemic or localized activation of the granulocytes and that IgM rheumatoid factor (IgMRF) is involved in the mechanism of the release of elastase.

A sensitive and specific assay for granulocyte elastase in inflammatory tissue fluid using L-pyroglutamyl-L-prolyl-L-valine-p-nitroanilide

Granulocyte elastase (GE, EC 3.4.21.37) is a key enzyme in tissue injury. To elucidate the role of GE in tissue injury, a new method of measuring GE activity in various inflammatory tissue fluids was developed using diazotization and the chromogenic synthetic substrate, L-pyroglutamyl-L-prolyl-L-valine-p-nitroanilide (S-2482). GE activity demonstrated first order kinetics in the range from 1.9 to 30 U/l. Other proteases, such as pancreatic elastase, trypsin, and chymotrypsin did not hydrolyze S-2484. This assay permits the determination of GE activity with a coefficient of variance less than 7.8% and 95.6 to 105.4% recovery. With this method, hydrolytic GE activity was found to be increased in bronchoalveolar lavage fluid from patients with ARDS or pneumonia, synovial fluid from patients with rheumatoid arthritis, and blister fluid from burn patients.

Circulating neutrophil elastase in infectious diseases in geriatric patients

Enzyme-linked immunosorbent assay has been used to measure elastase proteinase inhibitor complex (EPIC) and C-reactive protein (CRP) in the elderly, with and without infection. Median EPIC levels in the elderly with infection, hospital controls, healthy elderly residents in old people's homes and healthy blood donors were 300, 104, 96 and 74 ng/ml respectively. Ninety-five per cent of the patients with infection had EPIC levels well above the normal range. The median EPIC level in the elderly with infection showed a statistically significant difference from that in the control groups (p less than 0.0001, Mann U test). CRP showed similar results. Elevation of EPIC or CRP did not depend on the type of infection or bacteria isolated. We would conclude that neutrophil inhibitor-bound elastase could be used as a marker of inflammation in old people.

Effect of piroxicam therapy on granulocyte function and granulocyte elastase concentration in peripheral blood and synovial fluid of rheumatoid arthritis patients

The effect of piroxicam therapy (20 mg/day for 15 days) on various polymorphonuclear granulocyte (PMN) responses and on PMN elastase concentration was investigated in nine patients with active rheumatoid arthritis. Peripheral blood and synovial fluid samples were collected before starting therapy and 12 h after the last dose of the drug. All patients were evaluable for peripheral blood analysis and six for synovial fluid analysis. Piroxicam therapy had no effect on PMN random migration and phagocytosis, while it significantly reduced both FMLP-induced aggregation and FMLP-induced chemotaxis. This seems mainly due to an effect on FMLP binding, as no differences were observed after therapy in PMA- and PHA-induced aggregation as well as in serum-induced chemotaxis. In contrast, a marked impairment of NBT test and PMA- and FMLP-induced superoxide anion (O2-) production was found after piroxicam therapy. This effect was as evident in peripheral blood as in synovial fluid PMN. Also, a significant reduction in synovial fluid PMN number and synovial fluid PMN elastase concentration (elastase-alpha 1-proteinase complex) was found after treatment. It is concluded that piroxicam may act at different sites on various PMN responses. Its effect on O2- generation and PMN elastase concentration in synovial fluid may have an important role in reducing destruction of arthritic joint tissue.

Circulating inhibitor bound elastase in patients with ankylosing spondylitis and rheumatoid arthritis and the influence of sulphasalazine treatment

The plasma concentration of granulocyte elastase in complex with alpha 1 proteinase inhibitor was determined in 42 patients with ankylosing spondylitis (AS) and 33 patients with rheumatoid arthritis (RA). Significantly raised levels of plasma elastase were found in patients with RA, whereas patients with AS had normal values. No correlation was seen between the elastase values and erythrocyte sedimentation rate (ESR), serum haptoglobin, immunoglobulins, or polymorphonuclear cell (PMN) count in either of the patient groups. A correlation was found between the Ritchie index and plasma elastase in patients with RA. After three months' treatment with sulphasalazine a clinical improvement was seen and this paralleled a reduction of the acute phase reaction in both patient groups. A reduction of the circulating elastase values was seen in the patients with RA, whereas no change was seen in patients with AS.

Adenosine deaminase activity in joint effusions

The activity of adenosine deaminase (ADA) was determined in serum and synovial fluid of 98 patients with joint effusions of various causes. Compared with osteoarthritis, there were significantly higher mean synovial fluid ADA activities in seropositive rheumatoid arthritis (p less than 0.01), chronic seronegative polyarthritis (p less than 0.001), juvenile chronic arthritis (p less than 0.001) and reactive arthritis (p less than 0.001). In inflammatory joint diseases higher mean ADA activities in synovial fluid than in serum were observed, indicating a local release of ADA by cells within the joints. ADA activity in synovial fluid correlated with general disease activity as measured by haemoglobin concentration and erythrocyte sedimentation rate, and may provide an additional measure of the degree of inflammation in joint diseases.