The effect of anti-rheumatic agents on macrophage function

Oestrogen receptors in macrophages

The presence of receptors for oestradiol-17 beta and 5 alpha-dihydrotestosterone (5 alpha-DHT) in the human monocytic leukaemia cell line J111 and rat peritoneal macrophages was investigated using whole-cell assays. For both cell types, high-affinity binding species for oestrogen were detected, whereas no indication of specific binding was observed for 5 alpha-DHT. Analysis of the data according to Scatchard showed curved lines, indicating the presence of two different oestrogen-binding species. The dissociation constant (Kd) values for the receptors of the rat peritoneal macrophages were calculated to be 1.4 x 10(-10) M and 3.3 x 10(-9) M, while for the J111 cells, the Kd values were 8.7 x 10(-11) M and 2.5 x 10(-9) M. Sucrose-gradient ultracentrifugation identified one oestrogen-binding species of 7.1S. The receptors had a relatively high affinity for diethylstilboestrol (DES) but did not bind to a monoclonal antibody specific for the classical oestrogen receptor, suggesting that oestrogen receptors in macrophages could be of a different type.

The effect of gold sodium thiomalate and auranofin on lipopolysaccharide-induced interleukin-1 production by blood monocytes in vitro: variation in healthy subjects and patients with arthritis

The anti-rheumatic gold compounds gold sodium thiomalate (GST) and auranofin (AF) have variable and often unpredictable effects in patients treated for arthritis. As inhibition of interleukin-1 (IL-1) production may be an important effect of these drugs, we investigated their effect on IL-1 production by lipopolysaccharide (LPS) stimulated monocytes in a serum-free, non-adherent culture system. A bi-modal effect was observed: low concentrations (GST 10-250 ng/ml and AF 1-100 ng/ml) potentiated IL-1 production, and higher concentrations (GST 200-1000 ng/ml and AF10-500 ng/ml) inhibited it. This bi-modal effect was observed for both secreted and cell-associated IL-1 activity with the exception that GST failed to inhibit cell-associated IL-1 generation. The potentiating effect was dependent on the continuous presence of gold for at least the first few hours after LPS stimulation. The inhibitory effect of GST was dependent on its presence after LPS stimulation while that of AF was evident even if cells were pretreated with AF and washed before exposure to LPS. There was considerable individual variation in IL-1 production in response to LPS as well as in the effects of gold on cells from both healthy individuals and patients with arthritis. There was also some overlap in the range of concentrations of gold that potentiated and inhibited IL-1 production, and there was relative insensitivity to the inhibitory effects of gold in certain individuals. These results may explain some of the variability in the response of patients to chrysotherapy and support further studies to see if these in vitro effects might predict clinical response to gold.

Mepacrine impairs neutrophil response after acute lung injury in rats. Effects on neutrophil migration

Intraalveolar leukocytosis is integral in initiating and perpetuating airspace inflammatory reactions. We used intratracheal instillation of silica suspensions in adult male rats to cause neutrophil flux (32% increase over saline controls) without creating a protein leak, so simulating an early inflammatory response. We examined the in vivo effects of a known phospholipase A2 inhibitor (mepacrine) and the two mast cell active agents (cyproheptadine and reserpine) on lung lavage fluid chemotactic capability, alveolar macrophage (AM) production of chemotactic factor(s), and neutrophil diapedesis. Only mepacrine significantly depressed the leukocytosis (from 32% to 8% of total cells), with a similar diminution in AM chemotaxin production. Separate in vitro experiments using mepacrine-pretreated neutrophils and macrophages gave evidence that mepacrine: (1) diminishes neutrophil response to chemotaxin(s), (2) inhibits spontaneous, random neutrophil movement, and (3) diminishes macrophage-derived chemotactic factor production. These observations suggest that the earliest events in alveolar inflammatory reactions probably involve local production of chemotactic factors by AM, and that mepacrine's anti-inflammatory action results from inhibitory influences on both macrophage and neutrophil populations.

Compromised wound repair caused by perioperative use of ibuprofen

Nonsteroidal anti-inflammatory drugs have been shown to inhibit inflammation, an integral part of the wound-healing process. Compromised wound repair has been demonstrated in laboratory animals administered high-dose nonsteroidal anti-inflammatory drugs, a phenomenon we speculate could occur in humans undergoing surgery. We report a dramatic case of impaired wound healing in a patient ingesting high-dose perioperative ibuprofen, a nonsteroidal anti-inflammatory drug.

On the interactions between macrophages and developmental stages of Schistosoma mansoni: the cytotoxic mechanisms involved in macrophage-mediated killing of schistosomula in vitro

In an in vitro cytotoxicity assay, mouse adherent peritoneal exudate macrophages (APEM), harvested 8-10 weeks post Schistosoma mansoni infection caused sizable (greater than 90%) specific killing of schistosomula. This cidal effect was not diminished by the addition of scavengers of oxidative burst products to the cytotoxicity assay, albeit macrophages from schistosome-infected mice produced more H2O2 than did macrophages from non-infected mice. Of inhibitors of lysosomal enzyme function and release added to the cytotoxicity assay, trypan blue (1 mg/ml) fully abolished the schistosomulicidal effect; hydrocortisone (100 micrograms/ml) was partly effective, and gold salts (1 mg/ml) were ineffective. A cidal effect was not apparent in the absence of L-arginine nor in the presence of excess (greater than 400 micrograms/ml) L-arginine, L-lysine or L-ornithine. Arginase (5 U/ml) totally abrogated the schistosomulicidal effect. The findings suggest that a macrophage protein of a lysosomal origin, dependent on arginine for its reaction and/or production, may be involved in the in vitro killing of schistosomula by macrophages from S. mansoni-infected mice.

Macrophage activation in rat models of inflammation and arthritis: determination of markers of stages of activation

Disease-associated alterations in macrophage functions were assessed by investigating the stages of activation of peritoneal macrophages obtained from adjuvant-induced arthritic rats. The stages of activation were established by defining several functional parameters in macrophages obtained from normal, sterile-irritant injected and Propionibacterium acnes injected animals. Peritoneal macrophages taken from arthritic rats 17 days post adjuvant injection displayed parameters characteristic of activated, but not elicited or resident macrophages. Specifically, an increased number of macrophages was recovered from arthritic rats which spread readily in culture, exhibited enhanced Fc receptor-mediated phagocytosis, increased leucine aminopeptidase ectoenzyme activity, enhanced secretion of prostaglandin E2 and interleukin 1, and ability to lyse tumor cells spontaneously. In addition, these macrophages were impaired in their ability to secrete superoxide anion. These data demonstrate distinct differences in parameters of peritoneal macrophage activation in rats compared to mice and that macrophage activation is associated with disease progression in adjuvant-induced arthritic rats.

[1-14C]Arachidonic acid incorporation into glycerolipids and prostaglandin synthesis in peritoneal macrophages: effect of chloramphenicol

Peritoneal macrophages from normal mice were labelled with [1-14C]arachidonic acid after 2 h culture. The uptake of arachidonic acid into cellular lipids was rapid, time-dependent and can be represented within the limit of the studied times by a parabolic regression. Indomethacin decreased the kinetics of uptake; this inhibition is dose-dependent. Chloramphenicol had no effect on macrophage [1-14C]arachidonic acid uptake. After 3 h, the radioactivity was recovered in phosphatidylcholine (38.6%), phosphatidylserine-phosphatidylinositol (8.5%), phosphatidylethanolamine (22.1%), diacylglycerol (2.9%), triacyglycerol (2%) and cholesteryl ester (11.8%). Chloramphenicol and indomethacin inhibited the labelling of phospholipids and stimulated the labelling of neutral lipids and cholesteryl ester. Studies on arachidonic acid release from glycerolipids of prelabelled 2-h cultured macrophages showed that phosphatidylcholine and phosphatidylserine-phosphatidylinositol are the major source of arachidonic acid in prostaglandin synthesis in macrophages stimulated or not by zymosan. Chloramphenicol inhibited release of fatty acid from phosphatidylcholine and phosphatidylserine-phosphatidylinositol; indomethacin had no effect. Both drugs inhibited prostaglandin synthesis in stimulated or non-stimulated macrophages. In the culture medium, indomethacin increased the release of free arachidonic acid by stimulated macrophages. Possible explanations for the mechanisms underlying these effects are presented. It is concluded that indomethacin and chloramphenicol exert profound effects on the metabolism of phospholipids and its zymosan activation. Chloramphenicol appears to impair prostaglandin synthesis through several mechanisms and especially through phospholipase inhibition.