Lipoxygenation of arachidonic acid as a source of polymorphonuclear leukocyte chemotactic factors in synovial fluid and tissue in rheumatoid arthritis and spondyloarthritis

Leukotrienes: their possible role in pulpal and periapical diseases

Leukotrienes play an important role in inflammation and its sequelae such as pain, swelling, and bone resorption. This review covers, their history, structure, synthesis, metabolism, biological effects, inhibitors, antagonists, and their possible role in pathogenesis of pulpal and periapical disease.

Relationship between leukotriene B4 and immunological parameters in rheumatoid synovial fluids

Leukotriene B4 (LTB4) was measured in synovial fluid from 20 patients with rheumatoid arthritis and 15 patients with osteoarthritis. The level of LTB4 was significantly higher in synovial fluid from rheumatoid arthritis patients as compared with synovial fluid from osteoarthritis patients. LTB4 levels also significantly correlated with cell numbers, rheumatoid factor, and immune complexes in synovial fluid from rheumatoid arthritis patients. There was an inverse correlation between LTB4 levels and complement components. The high-pressure liquid chromatography peak of immunoreactivity extracted from the synovial fluid occurred at a retention volume identical to that of authentic LTB4. These results suggest that the increased level of this mediator in synovial fluid may contribute to perpetuation of inflammation and tissue destruction in rheumatoid arthritis.

Leukotriene B4, interleukin 1 and leucocyte accumulation in titanium and PTFE chambers after implantation in the rat abdominal wall

The inflammatory reaction elicited after implantation of non-biologic materials was studied by analysis of the exudate in pure titanium or polytetrafluorethylene chambers 1-9 d after insertion in the abdominal wall of the rat. In chambers made of pure titanium, the number of leucocytes increased about twofold from 1.8 x 10(6)/ml to 4.1 x 10(6)/ml between 24 h and 6 d, whereas a larger increase from 2.1 x 10(6)/ml to 8.3 x 10(6)/ml was observed in the polytetrafluorethylene chambers. Irrespective of implant material, polymorphonuclear granulocytes constituted the vast majority of leucocytes (greater than 81%). After 24 h the leukotriene B4 content was slightly higher in polytetrafluorethylene chambers than in titanium chambers. In contrast to the titanium chambers, a marked increase in leukotriene B4 levels was detected in polytetrafluorethylene chambers 6 d after insertion, whereas the greatest amount of leukotriene B4 in titanium chambers was measured at 9 d. Interleukin 1 was only detected in both types of chambers after 6 d. The present study, together with previous findings, shows that the materials used in this study elicit different degrees of inflammatory reactions in the chamber exudate. Since the number of leucocytes in the exudate retrieved from the chambers correlated well with the leukotriene B4 levels, it is suggested that leukotriene B4, but not interleukin 1, may be an important mediator for polymorphonuclear granulocyte migration into the implant-tissue interface.(ABSTRACT TRUNCATED AT 250 WORDS)

Muscle protein synthesis in patients with rheumatoid arthritis: effect of chronic corticosteroid therapy on prostaglandin F2 alpha availability

Using stable-isotope techniques, we measured rates of quadriceps muscle protein synthesis in twelve women with sero-positive rheumatoid arthritis. The results were compared to those from the normal limb of seven women with unilateral osteoarthritis of the knee. Six patients had never received corticosteroid immuno-suppression, but the other six had taken an average of 8 mg Prednisolone per day for 9 years. Quadriceps atrophy was present in both sets of patients with rheumatoid arthritis (normal legs 444 +/- 182, rheumatoid 190 +/- 40, rheumatoid + steroid 300 +/- 110 micrograms protein/micrograms DNA, means +/- SD, both P less than 0.001). Muscle protein synthesis, calculated by comparing the incorporation of 13C-leucine into biopsy samples taken after an 8 h L-[1-13C] leucine infusion with the time averaged enrichment of blood alpha-ketoisocaproate, was 0.056 +/- 0.005% h-1 in the patients not receiving steroids compared with 0.050 +/- 0.02% h-1 in normals (P greater than 0.05) indicating that muscular atrophy was primarily due to an increase in rate of muscle protein breakdown. Intra-muscular PGE2 concentration was increased in these patients (rheumatoid 0.12 +/- 0.06 ng mg-1 tissue, normals 0.06 +/- 0.03 ng mg-1 tissue, P less than 0.05). Patients taking corticosteroids had a markedly depressed rate of muscle protein synthesis (0.035 +/- 0.008% h-1, P less than 0.05) and reduced intra-muscular PGF 2 alpha concentration (P less than 0.01). We conclude that steroid therapy significantly influences the mechanism of skeletal muscle atrophy in patients with rheumatoid arthritis.

Neutrophil chemotactic factors in synovial fluids of patients with Lyme disease

We examined synovial fluid samples from 14 patients with Lyme arthritis for the presence of neutrophil chemotactic factors. Thirteen of the synovial fluids stimulated chemotaxis of normal human neutrophils. The chemotactic activity was heat-sensitive and was not inhibited by antibody to C5a or antibody to interleukin-8, or by a competitive inhibitor of the chemotactic peptide f-Met-Leu-Phe. A culture supernatant of Borrelia burgdorferi also contained neutrophil chemoattractants. Chromatography demonstrated that the chemoattractants in the synovial fluid samples were different from those in the B burgdorferi culture supernatant. One of the major chemotactic factors in Lyme disease synovial fluid had a calculated molecular weight of 13,900. We conclude that a novel, host-derived chemoattractant is present in the synovial fluid of patients with Lyme disease.

Complement C4-derived monocyte-directed chemotaxis-inhibitory factor. A molecular mechanism to cause polymorphonuclear leukocyte-predominant infiltration in rheumatoid arthritis synovial cavities

To reveal the mechanism of the lesser infiltration of monocytes in synovial cavities with rheumatoid arthritis despite the presence of chronic inflammation, the synovial fluid from 15 rheumatoid arthritis patients was analyzed with respect to leukocyte chemotaxis. The synovial fluid possessed strong chemotactic activity to polymorphonuclear leukocytes but rather suppressed one to monocytes. The synovial fluid contained two different inhibitory activities in monocyte chemotaxis. One, which also suppressed polymorphonuclear leukocyte chemotaxis, was identified as alpha 1 protease inhibitor. The other, with molecular weight of 8 kd, possessed the specificity to monocytes and shared the antigenicity with complement C4 but not with C3 or C5. A similar inhibitor was generated in normal human plasma when the classical pathway of the complement system was initiated with aggregated human IgG, while it was not when alternative pathway was initiated with zymosan. The small size factor in the synovial fluid, apparently derived from C4, seemed to be a cyto-directed factor that might block an early part of signal transduction system of monocytes in the chemotaxis. After removal of the small-size inhibitor, the synovial fluid exhibited chemotactic ability to monocytes. Therefore the apparent C4-derived factor might play a key role in the polymorphonuclear leukocyte-predominant infiltration in the synovial fluid of rheumatoid arthritis.

Tolfenamic acid inhibits leukotriene B4-induced chemotaxis of polymorphonuclear leukocytes in vitro

Inhibition of prostanoid synthesis is usually regarded as the mode of action of nonsteroidal antiinflammatory drugs (NSAIDs). In addition, some NSAIDs have been reported to have prostanoid-independent inhibitory effects on neutrophil functions. In the present study, we examined the effects of acetylsalicylic acid, diclofenac, indomethacin, ketoprofen, piroxicam and tolfenamic acid on leukotriene B4 (LTB4)-induced chemotaxis of human polymorphonuclear leukocytes (PMNs) in vitro. Tolfenamic acid inhibited LTB4-induced chemotaxis (IC50 59 microM), whereas the other compounds were ineffective. Tolfenamic acid inhibited also FMLP-induced chemotaxis at the same concentration range (IC50 46 microM). About 25% reduction in the chemotactic response was achieved with therapeutic concentrations of tolfenamic acid. We suggest that the inhibition of PMN chemotaxis is an additional mechanism in the antiinflammatory action of tolfenamic acid and that this action is not ligand specific.

Leukotriene B4 promotes phospholipid acylation in human neutrophils

The present study was undertaken to test the hypothesis that leukotriene B4 (LTB4) may promote extracellular fatty acid incorporation into neutrophil choline glycerophospholipids (PC) to replenish phospholipids after deacylation. Incubation of human neutrophils with LTB4 (1.5 to 150 nM) for 1 to 5 min resulted in increased fatty acid incorporation into phosphatidylinositol (PI), diacyl-sn-glycero-3-phosphocholine (diacyl-GPC) and alkylacyl-GPC. The magnitude of stimulation (percentage of control) of fatty acid incorporation appears to reflect increased activity of the acyltransferase catalyzing acylation of the respective lysophospholipids. LTB4 stimulation of arachidonic acid incorporation into PI was greater than into PC, whereas the stimulation of palmitic acid incorporation into PC was greater than into PI. LTB4 stimulated phosphatidic acid labeling by palmitic acid but not by arachidonic acid. LTB4 and 1-O-alkyl-2-N-methylcarbamyl-sn-glycero-3-phosphocholine (cPAF) exhibited a similar stimulatory effect on fatty acid incorporation into the PC fraction. Phosphate analysis could not detect changes in the mass of PI or of PC in neutrophils exposed to LTB4 or cPAF. The results suggest that increased fatty acid incorporation into phospholipids in LTB4-activated neutrophils reflects activation of phospholipase A2 and acyltransferases as well as of de novo phospholipid synthesis.

In vivo leukocyte migration in arthritis

We quantitated in vivo migration of neutrophils into the knees of patients with rheumatoid arthritis (RA) and osteoarthritis, using 99mtechnetium-hexamethyl-propylene-amineoxime-labeled leukocytes and gamma scintigraphy. Significant neutrophil migration occurred in patients with RA irrespective of disease duration, and it was reduced by 60% following intraarticular steroid injection. The reduction in neutrophil migration correlated with reduction in pain. Leukocyte migration into osteoarthritic joints was also demonstrated, although it was much less than that seen in rheumatoid joints. No significant leukocyte migration into the joints of patients without arthritis was demonstrated. This technique appears to provide a sensitive method for quantitatively assessing the neutrophil component of inflammation in individual joints of patients with arthritis.

Inhibition of leukotriene biosynthesis and polymorphonuclear leukocyte functions by orally active quinolylmethoxyphenylamines

The N-substituted quinolylmethoxyphenylamines, ETH603, ETH615 and ETH647, inhibited the formation of LTB4 in rat peritoneal leukocytes, human peripheral polymorphonuclear leukocytes and canine whole blood. In rat and human cells, the compounds also inhibited the formation of 5-HETE and stimulated the synthesis of 15-HETE. In rat leukocytes, the compounds were 15-30 times more potent inhibitors of LTB4 synthesis than nordihydroguaiaretic acid, but in canine whole blood they were significantly less potent, possibly due to protein binding. However, after oral administration of the compounds to dogs a long-lasting inhibition of LTB4 production in peripheral blood was observed at serum concentrations much lower than those required in vitro. Furthermore, the compounds inhibited the LTB4-directed chemotaxis and the phagocytosis of C. albicans blastospores by canine polymorphonuclear leukocytes both in vitro and following oral administration. The calcium ionophore A23187-induced release of LTB4 in the peritoneal cavity of rats was also inhibited by systemic administration of the compounds. We therefore conclude that these novel quinolines are orally active 5-lipoxygenase inhibitors which may accumulate in inflammatory cells in vivo, leading to potent inhibition of leukotriene biosynthesis and cell function.

Serum leukotriene B4 levels in patients with obstructive pulmonary disease

Leukotriene B4 has been found to be increased in the serum of cigarette smokers and some patients with bronchial asthma, as well as in the sputum of patients with cystic fibrosis and COPD. Corticosteroids supposedly may block the formation of LTB4. To determine if the effect of CS on airway disease is by reduction in LTB4, we studied serum LTB4 levels in clinically stable patients with asthma or COPD who were treated with or without CS. The LTB4 was extracted from serum and assayed by radioimmunoassay. Serum LTB4 concentrations, expressed as the mean +/- SD, were 0.36 +/- 0.15 ng/ml in ten normal controls, 0.56 +/- 0.18 ng/ml in nine asthmatic subjects, 0.67 +/- 0.2 ng/ml in eight asthmatic subjects receiving CS, 0.81 +/- 0.19 ng/ml in seven patients with COPD, and 0.97 +/- 0.29 ng/ml in eight patients with COPD receiving CS. Serum LTB4 levels in normal controls differed significantly from all groups with COPD or asthma (p less than 0.01). Levels of LTB4 in asthmatic subjects differed from levels in patients with COPD (p less than 0.03), and levels in asthmatic subjects receiving CS differed from subjects with COPD receiving CS (p less than 0.03). Concentrations of LTB4 within either the COPD or the asthmatic groups were not lower in the patients treated with CS. We conclude that serum LTB4 concentrations are higher in COPD than in asthma or normal controls and that administration of CS is not associated with low LTB4 levels. The beneficial effects of CS in obstructive airway disease appear to be mediated by mechanisms other than reduction of LTB4.

The role of leukotriene B4 in neutrophil infiltration in experimentally-induced inflammation of rat tooth pulp

Inflammation was induced in rat dental pulp by applying bacterial lipopolysaccharide (LPS). Extirpated tissue samples from inflamed pulps were incubated in vitro in a Krebs buffer containing Ca2+ ionophore A23187, and leukotriene (LT) B4 released into the medium was determined by radio-immunoassay. Production of LTB4 could be detected three to 24 h after the application of LPS and showed a maximum at 12 h. Histologically, marked infiltration of neutrophils, but not other leukocytes, was characteristically observed in the LPS-applied pulps, and the temporal change in neutrophil infiltration was almost parallel, but somewhat more delayed than LTB4 production. When BW755C, a dual inhibitor of cyclo-oxygenase and lipoxygenase, was given to the animals before the application of LPS, both the production of LTB4 and the number of infiltrated neutrophils were significantly decreased, whereas administration of indomethacin had no effect. These results suggest that LTB4 may be involved in neutrophil infiltration in pulpal inflammation. It was also suggested that a major early source of LTB4 in experimental pulpitis was leukocytes, primary neutrophils, because the synthesis of LTB4 in the inflammed pulp was diminished by depletion of circulating leukocytes with cyclophosphamide prior to the application of LPS.

Neutrophil chemotactic factors

Polymorphonuclear leukocytes (neutrophils) are recruited to inflammatory sites by a variety of soluble mediators (chemoattractants) that stimulate neutrophil directed migration (chemotaxis). Many neutrophil chemoattractants such as neutrophil activating proteins, leukotriene B4 (LTB4), platelet activating factor, and complement-derived C5a, are generated endogenously by host cells or enzymatic cleavage of host proteins. Other chemoattractants such as N-formyl peptides are generated exogenously by bacteria that invade the host. Oxidative modification of methionine residues or changes in the amino acid sequence of peptide chemoattractants dramatically alter their chemoattractive properties. Many of the well-defined neutrophil chemotactic factors and studies of their structure-function relationships will be reviewed.

Effect of interleukin 3 on the differentiation and histamine content of cultured bone marrow mast cells

Mouse bone marrow hematopoietic stem cells were isolated from mouse femur bone and cultured in RPMI 1640 supplemented medium with 20 units/ml of the purified T-cell lymphokine, interleukin 3 (IL-3), IL-3 was uniquely able to induce the proliferation and differentiation of mature mast cells in vitro. The sparse granulation of the bone marrow-derived mast cells (BMMC) can be seen by day 5, progressing to definable mast cells by day 7, the mast cells appear morphologically mature and comprise a 96% pure population after 14 days of the culture. The monocytes macrophages, eosinophils and neutrophils disappeared by day 9. After 4 weeks of tissue culture, mast cells are fully mature and completely granulated at 98% cell purity. The BMMC are mononuclear, oval or round in shape and appear smaller than rat peritoneal mast cells. BMMC are stable over 3-5 months in conditioned medium. The homogeneous mast cell population possesses membrane receptors and mediators, such as histamine in their metachromatic granules. The histamine content of BMMC in culture between 2 to 4 weeks rose from 1.43 to 1.82 pg/cell. Moreover, the percentage of histamine release caused by 0.1 microM and 1.0 microM ionophore A23187 was 15% and 35%, respectively. By contrast, the histamine releasing activity of 0.01% and 0.001% compound 48/80 were 12 +/- 2% and 59 +/- 7% respectively. The granular density, histamine content and histamine release activity of BMMC are different from that of peritoneal mast cells.

Phospholipases in biology and medicine

Phospholipases, a group of enzymes that catalyze the hydrolysis of membrane phospholipids, are classified according to the bond cleaved in a phospholipid into PLA1 (EC 3.1.1.3), PLA2 (EC 3.1.1.4), PLB (EC 3.1.1.5), PLC (EC 3.1.4.3), and PLD (EC 3.1.4.4). This paper reviews source and structure of PLA2 and the involvement of PLA2 and PLC in several biological phenomena, such as, signal transduction, photoreception, biosynthesis of lung surfactant, sperm motility, and fertilization. New assays for PLA2 activity and concentration in biological fluids are discussed. Phospholipases are involved in many inflammatory reactions by making arachidonate available for eicosanoid biosynthesis. The determination of PLA2 activity and mass concentration in plasma is useful in the diagnosis and prognosis of pancreatitis and of septic shock. Naturally occurring phospholipase inhibitors, such as lipocortins act as second messengers in the anti-inflammatory response to steroids. Lipocortins may be valuable therapeutic agents, because they are more specific in their anti-inflammatory action than glucocorticoids; therefore, they are less likely to produce harmful side effects.

Oxidative response of polymorphonuclear leucocytes to synovial fluids from patients with rheumatoid arthritis

Only a minority (7/35, 20%) of synovial fluids from patients with rheumatoid arthritis (RA) and none from patients with other arthritides stimulated the oxidative response of polymorphonuclear leucocytes (PMNs). Superoxide anion generation was measured by superoxide dismutase inhibitable reduction of cytochrome c. The same synovial fluids stimulated superoxide release by PMNs regardless of their source, though they elicited a greater response from RA synovial fluid PMNs than from either RA blood PMNs or blood PMNs from normal subjects. The remaining synovial fluids failed to stimulate any of the PMNs, though some (2/10) stimulated PMNs pretreated with cytochalasin B. The stimulatory activity was removed from RA synovial fluids by protein A-Sepharose and eluted with the void volume on gel chromatography. It is considered that immunoglobulin aggregates in some RA synovial fluids may stimulate the oxidative response of PMNs in the joint space but that most do not because these fluids contain either a specific inhibitor or immunoglobulin aggregates of an inappropriate type, or both.

Effects of N-acetyl-aspartyl glutamic acid and sodium cromoglycate on leukotriene B4 secretion by human leukocytes

Peripheral leukocytes from allergic subjects were treated for 30 min with sodium cromoglycate (SCG) or with N-acetyl-aspartyl glutamic acid (NAAGA) and challenged for leukotriene B4 (LTB4) production with calcium ionophore A 23187. NAAGA significantly inhibits LTB4 release at concentrations of 10(-2) M (-86%), 5 x 10(-3) M (-49%) and 10(-3) M (-34%), while SCG was not able to block LTB4 production within the range of 10(-2)-10(-4) M. In spite of the fact that SCG and NAAGA are chemically unrelated and that both show antiallergic properties, only NAAGA is able in this model to block production of LTB4, a chemical mediator strongly involved in inflammatory and hypersensitivity reactions.

Monocyte activation in early onset rheumatoid arthritis

Monocytes from peripheral blood and synovial fluid of patients with definite and classic rheumatoid arthritis spontaneously produced significantly greater amounts of prostaglandin E2 (PGE2), leukotriene B4 (LTB4), and interleukin-1 beta (IL-1 beta) than samples of peripheral blood from normal controls. Peripheral blood monocytes from patients with rheumatoid arthritis produced significantly greater amounts of PGE2 than control samples when stimulated with lipopolysaccharide. There were no significant differences in the spontaneous release of superoxide or N-acetyl-beta-D-glucosaminidase by peripheral blood monocytes between patients and healthy controls. Both stimulated and unstimulated peripheral blood monocytes from patients with definite or classic rheumatoid arthritis produced significantly greater amounts of PGE2 than samples from normal controls. This was true, regardless of the stage of disease and the presence or absence of roentgenological joint abnormalities. Amounts of N-acetyl-beta-D-glucosaminidase released by peripheral blood monocytes from patients correlated positively with the erythrocyte sedimentation rate (ESR) and negatively with duration of disease. Amounts of IL-1 beta and N-acetyl-beta-D-glucosaminidase released from the peripheral blood monocytes of patients who had had their disease for less than one year were significantly higher than those of normal controls. There were no significant correlations between the types of treatment and the amounts of PGE2, LTB4, IL-1 beta or N-acetyl-beta-D-glucosaminidase released by peripheral blood monocytes in patients with rheumatoid arthritis. The findings suggest that monocytes are activated in patients with rheumatoid arthritis both at the onset of disease and during its chronic phase, and that they produce large amounts of mediators which may have a role in the induction and extension of the inflammatory process which leads to tissue damage.

Proliferation of adherent synovial fluid cell cultures is modified by eicosanoids

Synovial fluid cells obtained from a carrageenan-induced chronic arthritis in the juvenile dog knee were allowed to adhere and proliferate in culture flasks. After twelve days secondary cultures were made and either 10(-8)M leukotriene B4 (LTB4), 25 microM 15-hydroxy-eicosatetraenoic acid (15-HETE), or both, were added and the cells were cultured for another 6 days. LTB4 is generated via the 5-lipoxygenase pathway of arachidonic acid metabolism and stimulates a number of phagocyte functions. Compared to control cells LTB4 increased proliferation in 9 out of 10 cell cultures (p less than 0.05). The 15-lipoxygenase product, 15-HETE, is not proinflammatory and is an endogenous inhibitor of 5-lipoxygenase. Addition of 15-HETE decreased proliferation of cell cultures by 23% (p less than 0.01). It is speculated that LTB4 in addition to its effect on phagocytes may play a role in synovial hyperproliferation observed in arthritis.

Synovitis reduced by inhibition of leukotriene B4. Carrageenan-induced gonarthritis studied in dogs

The pathophysiologic significance of leukotriene B4 (LTB4) in arthritis was studied in dogs by unilateral intraarticular deposition of 15-hydroxy-eicosatetraenoic acid (15-HETE), an endogenous inhibitor of the formation and the effects of LTB4, in bilateral carrageenan-induced gonarthritis. LTB4 in synovial fluid was selectively inhibited in 15-HETE treated joints, the formation of prostaglandin E2 (PGE2) being largely unaffected. The clinical symptoms, intraarticular pressure, and extractable synovial fluid volume were reduced in treated joints. No effect could be discerned regarding blood flow in the synovial membrane, capsule, or juxta-articular bone as measured by tracer microspheres; and no effect on bone metabolism was found as judged by 99mTc-diphosphonate uptake. Thus, inhibition of LTB4 reduces joint exudation, but does not seem to interfere with changes in juxta-articular hemodynamics or bone metabolism following synovial inflammation.

Leukotriene B4 and prostaglandin E2-like activity in synovial fluid in osteoarthritis

LTB4 and PGE2-like activity in synovial fluid samples from patients with osteoarthritis of the knee joint were determined and found to be significantly higher than in samples obtained from normal patients. The results suggest that leukotrienes and prostaglandins may have a role in the pathogenesis of osteoarthritis.

Effects of the nonsteroidal anti-inflammatory compounds Lonazolac Ca, indomethacin and NDGA on inflammatory mediator generation and release from various cells

The effects of Lonazolac calcium in modulating histamine release, leukotriene and 12-HETE generation and PAF metabolism from various cells were compared with the cyclooxygenase and lipoxygenase inhibitors indomethacin and nordihydroguaiaretic acid (NDGA). For histamine release cells were stimulated with Ca ionophore, A23187. The release of histamine from human basophils was significantly decreased after preincubation of the cells with Lonazolac Ca. Lonazolac Ca and NDGA were equally potent and their activity exceeded that of indomethacin. Preincubation of human polymorphonuclear leukocytes (PMN) with Lonazolac Ca, indomethacin and NDGA at high concentrations led to an inhibition of leukotriene generation induced by either the Ca ionophore or opsonized zymosan. Different concentrations were required for inhibiting the enzymatic and the non-enzymatically generated leukotrienes. Lonazolac Ca was more potent than indomethacin. Incubation of PMN with Lonazolac calcium modulated the metabolism of exogenously added 3H-PAF and 3H-lyso-PAF. In comparison with NDGA. Lonazolac Ca affected different enzymes of the PAF metabolism.

Effects of fish oil supplementation in rheumatoid arthritis

Sixteen patients with rheumatoid arthritis entered a trial to determine the clinical and biochemical effects of dietary supplementation with fractionated fish oil fatty acids. A randomised, double blind, placebo controlled crossover design with 12 week treatment periods was used. Treatment with non-steroidal anti-inflammatory drugs and with disease modifying drugs was continued throughout the study. Placebo consisted of fractionated coconut oil. The following results favoured fish oil rather than placebo: joint swelling index and duration of early morning stiffness. Other clinical indices improved but did not reach statistical significance. During fish oil supplementation relative amounts of eicosapentaenoic acid and docosahexaenoic acid in the plasma cholesterol ester and neutrophil membrane phospholipid fractions increased, mainly at the expense of the omega-6 fatty acids. The mean neutrophil leucotriene B4 production in vitro showed a reduction after 12 weeks of fish oil supplementation. Leucotriene B5 production, which could not be detected either in the control or in the placebo period, rose to substantial quantities during fish oil treatment. This study shows that dietary fish oil supplementation is effective in suppressing clinical symptoms of rheumatoid arthritis.

Leukotrienes and inflammation

The leukotrienes are synthesized from essential fatty acids via a 5-lipoxygenase enzyme. Most is known about the four-series leukotrienes derived from arachidonic acid. Leukotriene B4 is a potent chemotactic agent for leukocytes and it induces neutrophil-dependent increased microvascular permeability. Leukotrienes C4, D4 and E4 are bronchoconstrictors; and potent mediators of microvascular tone and permeability. The leukotrienes have been suggested to have a role in many inflammatory conditions in man in the skin (e.g. psoriasis), the lung (e.g. allergic asthma), joints (e.g. rheumatoid arthritis) and in the heart (e.g. myocardial infarction). Drugs which inhibit the generation and the actions of leukotrienes are under development and are being tested clinically as potential anti-inflammatory agents.

Arachidonic acid metabolism in neutrophil granulocytes obtained from synovial fluid in rheumatoid arthritis

Circulating human neutrophil granulocytes (PMNs) from patients with rheumatoid arthritis (RA) have earlier been described to possess an enhanced capacity for production of certain 5-lipoxygenase-derived metabolites of arachidonic acid (AA), 5-hydroxyeicosatetraenoic acid (5-HETE) and leukotriene B4 (LTB4). In the present investigation the endogenous AA metabolism of synovial fluid PMNs of RA patients was studied and compared with that of the corresponding circulating PMNs. Synovial fluid PMNs prelabelled with 14C-AA released significantly less radioactivity than circulating PMNs when stimulated with calcium ionophore. Furthermore, synovial fluid PMNs produced significantly smaller amounts of both 5-HETE and LTB4 than circulating PMNs from the same patients, whereas no such difference was observed in the LTB4 catabolites or the cyclo-oxygenase products. More information dealing with the complex way in which arachidonic acid is metabolized in diseased RA joints may provide future rational approaches in the treatment of this chronic inflammatory disease.

SC-41930: an inhibitor of leukotriene B4-stimulated human neutrophil functions

SC-41930 was evaluated for effects on human neutrophil chemotaxis and degranulation. At concentrations up to 100 microM, SC-41930 alone exhibited no effect on neutrophil migration, but dose-dependently inhibited neutrophil chemotaxis induced by leukotriene B4 (LTB4) in a modified Boyden chamber. Concentrations of SC-41930 from 0.3 microM to 3 microM competitively inhibited LTB4-induced chemotaxis with a pA2 value of 6.35. While inactive at 10 microM against C5a-induced chemotaxis, SC-41930 inhibited N-formyl-methionyl-leucyl-phenylalanine (fMLP)-induced chemotaxis, with 10 times less potency than against LTB4-induced chemotaxis. SC-41930 inhibited [3H]LTB4 and [3H]fMLP binding to their receptor sites on human neutrophils with KD values of 0.2 microM and 2 microM, respectively. SC-41930 also inhibited neutrophil chemotaxis induced by 20-OH LTB or 12(R)-HETE. At concentrations up to 10 microM, SC-41930 alone did not cause neutrophil degranulation, but inhibited LTB4-induced degranulation in a noncompetitive manner. SC-41930 also inhibited fMLP- or C5a-induced degranulation, but was about 8 and 10 times less effective for fMLP and C5a, respectively. The results indicate that SC-41930 is a human neutrophil LTB4 receptor antagonist with greater specificity for LTB4 than for fMLP or C5a receptors.

Eicosanoid production in rheumatoid synovitis

Leukotriene B4 (LTB4) synthesis in rheumatoid synovitis was studied using peripheral and synovial fluid polymorphonuclear leukocytes (PMNs) and rheumatic synovial lining cells. No differences were found in LTB4 synthesis between peripheral PMNs from healthy volunteers and rheumatoid arthritis patients. When peripheral and synovial PMNs from the same RA patient were compared, arachidonic acid-induced LTB4 synthesis in synovial fluid PMNs was increased 1.7-7.2 fold, whereas the response to Ca ionophore A23187 stimulation was similar. This suggests 5-lipoxygenase stimulating factor(s) in inflamed joints. Rheumatic synovial lining cells in a primary cell culture produced small amounts of LTB4, the concentrations being less than 0.1 per cent of those of prostaglandin E2 (PGE2). PGE2 synthesis in synovial cells was increased when arachidonic acid or interleukin-1 was added to the culture, whereas LTB4 production remained unaltered. The present results suggest that in inflamed joints LTB4 originates mainly from PMNs whereas synovial lining cells are the source for PGE2.

Nutrition, immune function, and inflammation: an overview

The collective evidence suggests that nutritional insult to both cell-mediated and humoral immunity in the presence of protein-energy malnutrition contributes to abnormalities of inflammation. The primary goal of nutritional support in inflammatory disease is to provide adequate energy and protein to meet endogenous requirements for tissue repair, IL-1 production, and restored cellular function, thus preventing secondary infection. Substrate provision should aim at improving the acute phase of injury while avoiding immune dysfunction. This goal may be achieved by altering the eicosanoid pathway toward a more regulated inflammatory state. In the context of allograft response, macrophages are central to the initiation of allosensitization by virtue of their ability to present antigen to T-cells. Activated T-cells may further modulate macrophage function by the secretion of lymphokines. Manipulation of macrophage eicosanoid production by dietary omega-3 PUFA may reduce cellular immune response. (table; see text) Nutritional support should also focus on providing essential micronutrients, with their potentially immunomodulating role, as adjunctive therapy in order to protect the host from toxic effects of free-radicals and chemicals released during inflammatory events. (Feeding regimens currently under investigation and development are presented in Table 4.) By integrating dietary immunotherapy with the use of recombinant hormones, monoclonal antibodies, and various available monokines, an optimal outcome for each patient may be achieved. However, effective application of immunotherapy to nutritional supplementation will require accurate monitoring of immune function in individual patients in order to avoid inappropriate treatment.

Platelet-activating factor regulates phospholipid metabolism in human neutrophils

This study extended the earlier finding that platelet-activating factor (1-O-alkyl-2-acetyl-sn-glycero-3-phosphocholine) promotes arachidonic acid incorporation into neutrophil phosphatidylinositol (PI) and phosphatidylcholine (PC). In the present study the effect of PAF on fatty acid uptake by human neutrophils and the incorporation of extracellular linoleic acid and palmitic acid into phospholipids were investigated. Incubation of 10(-7) M PAF with neutrophils and radiolabeled arachidonic acid or linoleic acid or palmitic acid for 1-10 min resulted in an increased rate of loss of label from the incubation medium. PAF stimulated the incorporation of linoleic acid and palmitic acid most significantly into PI and PC. The magnitude of stimulation was greater in PI than in PC for the incorporation of linoleic acid, and vice versa for the incorporation of palmitic acid. The positional distribution of linoleic acid and palmitic acid in PI and PC and the mass of these phospholipids were not altered in PAF-stimulated neutrophils. An increased incorporation of all three fatty acids into both diacyl and alkylacyl species of PC was demonstrated after a two minute incubation of cells with PAF. While more radioactivity was recovered in the diacyl species, the magnitude of increase of radioactivity in the alkylacyl species was more pronounced than that in the diacyl species of PC. These results suggest that both increased fatty acid uptake and increased available lysophospholipids may be contributory to the increased phospholipid acylation induced by PAF.

Effect of auranofin on eicosanoids and protein kinase C in human neutrophils

Auranofin (AF), a lipophilic chrysotherapeutic agent, was investigated for its effect on the formation of lipoxygenase products and the activity of protein kinase C in human neutrophils. We have previously shown that inhibition of LTB4 formation by 5-lipoxygenase (5-LO) inhibitors is intimately associated with a marked increased in 15-HETE in excess of arachidonic acid. The calcium- and phospholipid-dependent protein kinase, protein kinase C, is activated in FMLP- and A23187-stimulated neutrophils, is hypothesized to stimulate superoxide generation, and plays an essential role in eicosanoid production. AF dose-dependently inhibited the generation of leukotriene B4(LTB4) in FMLP-stimulated neutrophils, the ID50 was approximately 4.5 micrograms/ml. Unlike known 5-LO inhibitors, AF did not enhance the production of 15-HETE. In neutrophils stimulated with the calcium ionophore, A23187, AF did not inhibit the generation of LTB4 nor did AF change the 15-HETE levels. AF inhibited superoxide generation in FMLP-stimulated neutrophils dose-dependently, but did not change the activation of protein kinase C in the cells. We therefore conclude, that AF inhibition of LTB4 production in neutrophils is different from 5-lipoxygenase inhibitors and is elicited at a step distal to protein kinase C activation.

Orally administered tolfenamic acid inhibits leukotriene synthesis in isolated human peripheral polymorphonuclear leukocytes

Special interest has been focused on the development of dual inhibitors of the cyclo-oxygenase and lipoxygenase pathways of arachidonic acid metabolism. In contrast to other classic NSAIDs, some fenamates in clinically achievable concentrations have been shown to inhibit synthesis of 5-lipoxygenase products in vitro. In the present work, we studied the effect of orally administered tolfenamic acid (600 mg) on Ca ionophore A 23187 -induced leukotriene synthesis in isolated human polymorphonuclear leukocytes. Leukotriene production was reduced in all 14 subjects studied, the mean inhibition of LTB4 synthesis being 16 +/- 3% and that of LTC4 33 +/ 7%. The inhibition correlated positively with serum acid concentrations. We suggest that inhibition of leukotriene synthesis is an additional mechanism of the anti-inflammatory, antimigraine and antidysmenorrhoeic effects of tolfenamic acid, and a possible explanation for its rare gastric and bronchoconstrictive side-effects.

Characterisation of soluble and cell associated phospholipase A2 from rheumatoid synovial fluid

The hydrolysis of radiolabelled Escherichia coli phospholipids, and micellar dispersions of phosphatidylethanolamine and phosphatidylcholine, were used to characterise the phospholipase A2 activity in synovial fluid from patients with rheumatoid arthritis. Cell free fractions of synovial fluid contain a phospholipase A2 enzyme that preferentially releases [14C]oleic acid from E coli biomembranes (specific activity 291.3 (SEM 27.6) pmol/min/mg). This enzyme requires calcium and is optimally active at neutral pH. Purified dispersions of phosphatidylethanolamine are also readily degraded by the soluble enzyme, but it is not active against phosphatidylcholine. The substitution of [14C]oleic acid by [3H]arachidonic acid for the labelling of E coli allowed differentiation between the soluble phospholipase A2 and the cell associated phospholipase A2 present in sonicates of mononuclear cells and neutrophils from peripheral blood and synovial fluid. The cell associated phospholipase A2 preferentially releases [3H]arachidonic acid from E coli cardiolipin. In this paper the phospholipid substrate specificity of phospholipase A2 from rheumatoid synovial fluid, the optimal assay conditions for its detection, and a standardised expression of activity in terms of pmol per minute per mg of protein are established.

Biochemical characterization of soluble phospholipase A2 from rheumatoid synovial fluid

Radiolabeled E. coli, Phosphatidylethanolamine (PE) and Phosphatidylcholine (PC), were used to characterize the phospholipase A2 (PLA2) activity in synovial fluid (SF) from rheumatoid arthritis (RA) patients. Cell-free fractions of SF contain a PLA2 enzyme that preferentially releases [14C]oleic acid from E. coli, requires calcium and is optimally active at neutral pH. Purified PE, but not PC is also readily degraded by the soluble enzyme. A cell-associated PLA2 present in sonicates of SF mononuclear cells and neutrophils preferentially releases [3H]AA from E. coli. These studies suggest the presence of at least two different enzymes with activity of PLA2 in rheumatoid SF.

Leukocyte migration in synovial tissue. Leukocyte distribution, orientation, and migratory pattern after immune complex deposition in rabbit knee joints

Complement-activating bovine serum albumin (BSA)-anti-BSA immune complexes (ICs) were injected into rabbit knee joint cavities; the contralateral control joint was injected with BSA together with normal rabbit serum. The migration of leukocytes from the synovial venules into the joint cavity was analyzed with light microscopy (LM), scanning (SEM) and transmission (TEM) electron microscopy. EM autoradiography was used to study the endocytosis of ICs by leukocytes. The shape, orientation, and distribution of migrating polymorphonuclear granulocytes (PMNGs) were analyzed by LM morphometry. PMNGs accumulated in the joints injected with ICs. The peak of the number of PMNGs in the synovial tissue was reached after 4 hours, in the joint cavity after 6 hours. PMNGs in the synovial tissue were concentrated in the intimal layer. Migrating PMNGs were polarized, as judged by the ratio between the long (D max) and short (D min) axes of the cells. There was a close association between the migrating PMNGs and the collagen fibers. The morphometric data showed that the nonflattened, cylindrically-shaped PMNGs were oriented along the collagen bundles, running parallel to the synovial surface, and did not migrate in the straight direction of a theoretic leukotactic gradient originating in the joint cavity after IC deposition. SEM and TEM showed that the PMNGs were aligned along the collagen fibers and interacted activity with the collagen by pseudopods and cytoplasmic projections. EM autoradiography showed that the PMNGs in the joint cavity had ingested 125I-labeled ICs and were degranulated. In contrast, the PMNGs within the synovial membrane did not show any signs of IC endocytosis or any apparent degranulation. Synovial type A cells were found to contain ICs. This study indicates that the response of PMNGs in IC-induced synovitis consists of two distinct phases: an initial, mainly migratory phase in the synovial membrane where the PMNGs appear to use the collagen fibres as a climbing framework, and a second phase, in the joint cavity, characterized by PMNG metabolic activation, endocytosis of ICs, and degranulation. The apparent inability of PMNGs in the synovial membrane to ingest ICs and become degranulated might be due to not only concentration differences of ICs and leukotactic factors between the joint cavity and the synovial tissue but also might be related to the apparently active interaction with collagen.

Eicosanoids and rheumatology: inflammatory and vascular aspects

Eicosanoids are not only involved in inflammation but also are important in the maintenance of blood vessel tone and blood flow. This may be relevant in the rheumatological disorders of vasculitis and RS. Although little work has been carried out in vasculitis, the beneficial effects of the natural and synthetic antiplatelet vasodilator PGs in RS are well documented. Less well tested has been the effects of manipulation of AA metabolism. It should be remembered however that many patients with Raynaud's Phenomenon do not have an associated rheumatological disorder. Conservative management with vasodilators such as the calcium channel blockers may be very successful (119). At the present time PG treatment should be reserved for patients with severe RS, particularly those whose Raynaud's is complicated by digital ulceration.

Sulfasalazine: a potential psoriasis therapy?

In an open study, 32 patients with moderate to severe stable plaque psoriasis were treated with sulfasalazine, 3 gm daily for 8 weeks. Twenty-four patients completed the study, and 19 had modest to marked improvement or clearing. If confirmed by a double-blind study, sulfasalazine could become an alternative therapy in some patients with moderate to severe psoriasis.

Ginger (Zingiber officinale) and rheumatic disorders

Oxygenation of arachidonic acid is increased in inflamed tissues. In this condition products of two enzymic pathways--the cyclooxygenase and the 5-lipoxygenase producing respectively prostaglandins and leukotrienes--are elevated. Of the cyclooxygenase products, PGE2 and of the lipoxygenase products, LTB4 are the strongest candidates for mediating inflammation. Non-steroidal anti-inflammatory drugs which inhibit the cyclooxygenase, and corticosteroids are used to treat such disorders. Both types of drugs produce adverse side-effects on prolonged use. Ginger is reported in Ayurvedic and Tibb systems of medicine to be useful in rheumatic disorders. Seven patients suffering from such disorders reported relief in pain and associated symptoms on ginger administration.

Leukotrienes. Biology and role in disease

Leukotrienes are a novel group of chemical messengers derived from arachidonic acid. They are produced by several different tissues by processes linked to phospholipid flux in response to specific stimuli. The leukotrienes interact with specific receptors in target cell membranes to initiate a response. Most of these responsive cells are derived from bone marrow, skin, smooth muscle, and vascular endothelium. Leukotrienes are powerful mediators of inflammation and smooth muscle contraction, and there is increasing evidence that they are important factors in immune-mediated disease. Several available effective antiinflammatory drugs may act partially by inhibiting the production of leukotrienes.

Late appearance of phospholipid platelet-activating factor and leukotriene B4 in human skin after repeated antigen challenge

Inflammatory mediators were assessed in supernatants of chamber fluids from eight ragweed- or grass-sensitive subjects during antigen-induced cutaneous inflammatory responses. Platelet activating factor (PAF) accumulated at concentrations of 1 pm to 90 mumol/L in six of eight subjects beginning at 3 hours and continuing for 9 hours after antigen challenge. Leukotriene B4 (LTB4) was detectable at cutaneous sites of antigen challenge in five of five subjects throughout the 9-hour period at levels from 1 to 36 nmol, a range of 38% to 80% of which were omega-oxidation metabolites. Histamine levels peaked in the first hour at 106 +/- 18 ng/ml and decreased to a plateau of 11 to 13 ng/ml at 3 to 9 hours after antigen challenge. No PAF and only very low levels of LTB4 (0.1 to 1.3 nmol) and of histamine (less than 2 ng/ml) were detected at buffer-control sites during the 9 hours of study. Continuous antigen exposure thus results in the persistent release of histamine and LTB4 and the late appearance of PAF, all of which may contribute to the chronicity of allergic disorders and may have a bearing on the IgE-mediated, late-phase cutaneous response.

Inhibition of human neutrophils by auranofin: chemotaxis and metabolism of arachidonate via the 5-lipoxygenase pathway

The effect of auranofin on human neutrophil (PMN) 5-lipoxygenase activity and leucotriene B4 (LTB4) chemotaxis was investigated. [1-14C]Arachidonic acid was incorporated into the purified cells until steady state conditions were obtained. After preincubations with serial dilutions of auranofin arachidonic acid release and metabolism were stimulated with calcium ionophore A23187. The radioactive eicosanoids released were extracted and separated by thin layer chromatography, followed by autoradiography and quantitative laser densitometry. Chemotaxis of PMNs towards LTB4 was measured in a modified Boyden chamber. Auranofin showed dose dependent inhibition of both the 5-lipoxygenase pathway (IC50 17.4 X 10(-6) mol/l) and of chemotaxis (IC50 45 X 10(-6) mol/l). The release of arachidonic acid from phospholipids was unaffected in the concentration range tested (1-1000 mumol/l). Inhibition of both neutrophil motility and cellular synthesis of proinflammatory eicosanoids may thus contribute to the beneficial clinical effects of auranofin in rheumatoid arthritis.

Differential effects of 20-trifluoromethyl leukotriene B4 on human neutrophil functions

A leukotriene B4 (LTB4) analog, 20-trifluoromethyl LTB4 (20CF3-LTB4), has been synthesized and evaluated with human neutrophils for effects on chemotaxis and degranulation. 20CF3-LTB4 was equipotent to LTB4 as a chemoattractant (EC50, 3 nM), produced 50% of maximal activity of LTB4, and competed with [H] LTB4 for binding to intact human neutrophil LTB4 receptors. In contrast to chemotactic activity, 20CF3-LTB4 in nanomolar concentrations exhibited antagonist activity without agonist activity up to 10 microM on LTB4-induced degranulation. The analog had no significant effect on degranulation induced by the chemoattractant peptide, N-formyl-methionyl-leucyl-phenylalanine (fMLP). Like LTB4, 20CF3-LTB4 induced neutrophil desensitization to degranulation by LTB4. The results indicate that hydrogen atoms at C-20 of LTB4 are critical for its intrinsic chemotactic and degranulation activities. The fact that 20CF3-LTB4 is a partial agonist for chemotaxis and an antagonist for degranulation suggests that different LTB4 receptor subtypes are coupled to these neutrophil functions. Desensitization of the neutrophil degranulation response to LTB4 can result from receptor occupancy by an antagonist, and therefore, the desensitization is not specific for an agonist.

15-Hydroxy-eicosatetraenoic acid (15-HETE) inhibits carrageenan-induced experimental arthritis and reduces synovial fluid leukotriene B4 (LTB4)

15-Hydroxy-eicosatetraenoic acid (15-HETE), a product of arachidonic acid, has no proinflammatory capacity, but can inhibit the formation and the chemotactic response of neutrophils to leukotriene B4 (LTB4), a potent mediator of inflammation. The purpose of the present study was to determine whether intraarticular administration of 15-HETE in carrageenan-induced acute arthritis might decrease the levels of LTB4 in synovial fluid and modify the arthritis. A bilateral acute knee joint arthritis was established in 7 dogs by intraarticular injections of carrageenan every third day. To the right joints, 15-HETE was administered both concomitantly with the carrageenan injections and continuously via an osmotic pump. In samples of synovial fluid obtained on day 0, 3 and 10 PGE2 and LTB4 were determined using reversed phase high performance liquid chromatography combined with radioimmunoassays and neutrophil chemokinesis. In the presence of 15-HETE the clinical severity of arthritis was significantly reduced and the volume of synovial effusate was decreased on an average by 42%. Furthermore, the relative number of neutrophils in histological sections of synovial tissue was decreased by 58%. Intraarticular caragheenan injections induced LTB4 formation, and maximum levels were obtained on day 3 (279.2 +/- 148.2 pg/joint). PGE2 was also present on day 3, but maximum levels were detected on day 10 (9.5 +/- 4.8 ng/joint). In joints injected with both carragheenan and 15-HETE the levels of LTB4 on days 3 and 10 were inhibited by 90% and 83%, respectively. For PGE2 a small but insignificant decrease was found on both day 3 and on day 10. These results show that LTB4 may be an important mediator of acute arthritis induced by carragheenan in dogs, and that intraarticular administration of 15-HETE can modify this arthritis by inhibiting LTB4 formation.

Biosynthesis, catabolism, and biological properties of HPETEs, hydroperoxide derivatives of arachidonic acid

The oxygenation of arachidonic acid by lipoxygenases results in the formation of HPETEs (hydroperoxyeicosatetraenoic acids), the first products of the LOX pathway. These compounds are short lived and are catabolised into various families of more stable compounds of which the HETEs, hepoxilins, lipoxins and leukotrienes have been identified so far. The development of new techniques have helped to identify and understand the structures of various HPETEs and only recently the biological effects of HPETEs and their various catabolites are being unraveled. Although lipoxygenases are ubiquitous, not all tissues possess the same spectrum of lipoxygenase enzymes. Hence different HPETEs can be formed in different tissues. Recent studies have revealed that HPETEs or products derived from them possess a diversity of important biological properties including the regulation of electrolyte flux and eicosanoid and corticosterone syntheses, release of histamine, regulation of oocyte maturation and release of various reproductive hormones. HPETEs appear to be involved in some pathological conditions viz, skin psoriasis, Clarkson's disease, nerve injury and spinal cord ischemia. These novel eicosanoids are associated with the release of insulin as well as renin. Recently HPETEs have been suggested to act as second messengers in the Aplysia sensory neurons and its catabolite, hepoxilin, has been demonstrated to have effects on mammalian hippocampal neurons. The purpose of this review is to provide a brief summary of the formation of the HPETEs and the various families of compounds derived from them as well as the various types of biological activities for these products described so far.

Leukotriene b4 production by peripheral blood neutrophils in rheumatoid arthritis

Leukotriene B4 (LTB4) is an activator of white blood cells (WBC) and it has been suggested that its inhibition may be useful in rheumatoid arthritis (RA). Its production by peripheral WBC has not yet been investigated. We measured LTB4 production in 105 patients with RA and compared it with 59 matched controls. C-reactive protein (CRP) and ESR were measured in 90 patients and correlated with LTB4 values. Ten millilitres of blood were drawn. Separation was undertaken to obtain polymorphonuclear leukocytes (PMN) which were stimulated with calcium ionophore, and the supernatant was frozen for radioimmunoassay of LTB4. Results show that RA patients produce significantly higher levels of LTB4. It has been suggested that blockage of the cyclo-oxygenase enzyme by non-steroid anti-inflammatory drugs (NSAID) leads to increased production of LT via the lipoxygenase enzyme. Twenty-one patients not taking NSAID were compared with 84 on therapy. There was no significant difference. A linear regression was used to obtain Pearson's correlation coefficients. With LTB4 and CRP, r = 0.3 (p less than 0.003). With LTB4 and ESR, r = 0.25 (p less than 0.02). Low but significant correlations with CRP and ESR were obtained.

Phospholipid metabolism in polymorphonuclear leukocytes from rheumatoid arthritis patients: effects of non-steroidal anti-inflammatory agents and clotrimazole

Arachidonic acid (AA) metabolism and phospholipase A2 (PLA2) activity were measured in the peripheral blood polymorphonuclear leukocytes (PMNL) from ten patients with rheumatoid arthritis (RA) on treatment with various non-steroidal anti-inflammatory agents (NSAIA). AA metabolism and PLA2 activity were measured both initially and after treatment with either placebo or Clotrimazole, a broad spectrum anti-mycotic agent, as a possible anti-rheumatic drug. AA metabolism was also measured in PMNL from ten patients with active RA untreated with any NSAIA and ten normal volunteers. Using 3H-AA prelabeled cells, we show that there was a significantly higher (P less than 0.025) production of 3H-LTB4 in response to stimulation with the calcium ionophore A23187 in untreated RA patients than in normal volunteers (mean +/- S.D.:4.8 +/- 1.6% and 3.1 +/- 1.0%, respectively). The production of 3H-LTB4 by PMNL from patients on NSAIAs was less elevated (mean +/- S.D.:4.1 +/- 1.5%) and was not significantly different from normal controls. Concurrently we examined PLA2 activity in PMNL-sonicates from ten of our study patients using autoclaved [14C]oleate-labeled E. coli biomembranes as an exogenous substrate. Using linear regression analysis, we demonstrate a significant correlation between in vitro PLA2 activity and the release of 3H-AA from the cellular phospholipids (deacylation) in response to A23187 stimulation (r = -0.526, P less than 0.025). We also demonstrate significant correlations between the overall clinical state of the RA patient, as evaluated by a modified rheumatoid activity index (MRAI), and both the release of 3H-AA from the cellular phospholipids and its production of total [3H]eicosanoids (r = -0.557, P less than 0.025 and r = 0.644, P less than 0.005, respectively). This data suggests that: PLA2 activity may, in part, account for the higher generation of LTB4 by RA PMNL; NSAIAs may be capable of modulating this abnormality; and Clotrimazole may affect the clinical or laboratory data of RA patients already on treatment with NSAIA.

Effect of single oral administrations of non steroidal antiinflammatory drugs to healthy volunteers on arachidonic acid metabolism in peripheral polymorphonuclear and mononuclear leukocytes

The effects of a single oral administration of acetylsalicylic acid (500 mg), indomethacin (50 mg) and piroxicam (40 mg) to healthy volunteers on functional and biochemical parameters of platelets, polymorphonuclear (PMN) and mononuclear (MNL) leukocytes were evaluated. Blood was collected before and two hours after the drug intake and blood cells separated according to conventional techniques. The considered drugs almost completely suppressed the aggregation of platelets, whereas they did not affect either PMN and MNL aggregation. Superoxide anion generation by leukocytes was (PMN), or no effect (MNL) was observed after piroxicam and indomethacin respectively. The formation of arachidonate metabolites via the 5-lipoxygenase pathway by PMN and MNL challenged with 10 microM A23187 was unchanged following aspirin and indomethacin. In this respect a selective increase of 5-HETE and LTC4 synthesis by MNL only was detected after piroxicam administration. The three drugs similarly reduced TXB2 synthesis by platelets and PMN (-80% for aspirin and indomethacin, and -40% for piroxicam). As far as MNL is concerned, aspirin inhibited this metabolite by 80%, while indomethacin reduced it by 40% only. In contrast piroxicam increased TXB2 synthesis by stimulated MNL. It can be concluded that the considered antiinflammatory drugs 1) differently affect the cyclooxygenase enzyme in platelets and leukocytes; 2) at variance with the situation in platelets, the inhibition of thromboxane formation by leukocytes is not related to modifications of cellular function; 3) the formation of arachidonate metabolites via the 5-lipoxygenase pathway is affected by piroxicam only.