Improvement of the gastric tolerance of non-steroidal anti-inflammatory drugs by polyene phosphatidylcholine (Phospholipon 100)

The effect of co-administration with polyene phosphatidylcholine (Phospholipon 100) on the oral gastrotoxicity of various non-steroidal anti-inflammatory drugs (NSAIDs) was studied in the rat. The highly unsaturated phospholipid reduced gastric mucosal lesions measured 3.5 h after oral administration of aspirin, indomethacin, phenylbutazone, diclofenac, piroxicam and sudoxicam to rats which had received a 3 day bread diet followed by 24 h fasting. The extent of reduction of gastrotoxicity varied amongst the individual NSAIDs. Phospholipon 100 also reduced gastric lesions induced by 3 day oral piroxicam and diclofenac administration. A trend towards reduction of oral diclofenac gastrotoxicity was observed following intravenous Phospholipon 100 administration. Phospholipon 100 H (100% saturated phosphatidylcholine) was less effective than Phospholipon 100 in improving acute gastric tolerance to oral phenylbutazone, diclofenac and piroxicam. Administration of the NSAID-Phospholipon 100 combination produced little change in the anti-inflammatory activities of diclofenac on carrageenan paw oedema and diclofenac and piroxicam on adjuvant arthritis in the rat. Combination with Phospholipon 100 offers a novel means for reducing the gastric side-effects of NSAID therapy.

[Immunopathologic aspects of chronic erysipelas polyarthritis in swine]

Chronic erysipelas polyarthritis in pigs is considered to be an animal model closely resembling human rheumatoid arthritis. In an experimental study using SPF pigs infected with Erysipelothrix rhusiopathiae several immunopathological aspects were studied for up to 14 months after infection. After an initial febrile phase a progressive polyarthritis and discospondylitis developed at 2 weeks after infection. Quantitative determination of IgG and IgM revealed a significant increase in these immunoglobulins both in the serum and the synovia from arthritic joints. Arthritic joints containing viable Erysipelothrix bacteria at termination of the experiment have a higher content of IgG and IgM than bacteriologically negative joints. During the entire experiment the rheumatoid factor titer, determined by the Waaler Rose test, remained relatively low with increases and decreases. The Erysipelothrix antibody titers are highly significant. The total complement activity in the serum increases discontinuously and shows fluctuations similar to those of the rheumatoid factor titer. The highest enzyme activities of acid phosphatase and lactate dehydrogenase are demonstrable in the synovial fluid of arthritic joints with positive bacteriological or immunohistological findings. These joints also have the greatest numbers of IgG-producing plasma cells. By means of immunohistological methods Erysipelothrix antigen can be demonstrated in macrophages of the proliferating synovial membrane. Finally, there is a discussion of the pathogenic significance for the perpetuation of chronic polyarthritis of Erysipelothrix persisting in arthritic joints in spite of focal immune reactions.

Chemiluminescence from mouse resident macrophages: characterization and modulation by arachidonate metabolites

Oxidative burst dependent chemiluminescence (CL), generated by mouse resident peritoneal and alveolar macrophages obtained by peritoneal and lung lavage, has been studied using a lumanol-dependent assay. Alveolar macrophages generated greater CL in response to opsonized zymosan (OpZ, 0.017-0.67 mg/ml) than did peritoneal cells, but the former were less sensitive to inhibition by joint cyclo-oxygenase/lipoxygenase inhibitors and superoxide dismutase. Responses of peritoneal macrophages to OpZ and calcium ionophore A23187 (0.1-0.5 microM) were small in comparison to responses of C. parvum-elicited cells, while FMLP (2-20 microM) was ineffective. Arachidonic acid alone (40-80 microM) generated slight CL from resident peritoneal macrophages. When added with OpZ (0.017 mg/ml), arachidonate (40 microM) initially enhanced, then inhibited CL, the inhibition being indomethacin (10 microM) sensitive. These data indicate that modulation of resident macrophage CL by arachidonate products differs somewhat from that reported for elicited macrophages.

Platelet activating factor (PAF) induces the oxidative burst in macrophages

The response of guinea pig peritoneal macrophages to platelet activating factor (1-O-octadecyl-2-acetyl-sn-glycero-3-phosphoryl-choline) was examined. In Corynebacterium parvum induced macrophages, platelet activating factor, over a wide dose range (3.8 X 10(-5) to 3.8 X 10(-9)M) triggered the oxidative burst as indicated by increased luminol-dependent chemiluminescence and hydrogen peroxide release into culture supernatants. This effect of PAF was inhibited by superoxide dismutase and catalase. Resident macrophages exhibited only slight respiratory activity in response to platelet activating factor which could be increased by adding 1% gelatine to the medium. Activation of macrophages is a new biological effect exerted by platelet activating factor. In immuno-inflammatory reactions, cells capable of generating platelet activating factor may come into close contact with macrophages and by liberating this mediator cause them to release highly toxic oxygen species known to be microbicidal and cytocidal and able to produce vascular endothelial injury. Our findings lend further support to the view that platelet activating factor is a potent and rapid activator of physiological defence mechanisms.

Macrophage, lymphocyte and chronic inflammatory responses in selenium deficient rodents. Association with decreased glutathione peroxidase activity

The influence of a selenium deficient diet in mice and rats has been studied on glutathione peroxidase (GSH-Px) and secretory activities of peritoneal macrophages, mitogenesis of spleen cells and adjuvant arthritis. Macrophage GSH-Px activity was significantly reduced from 9 weeks on the selenium deficient diet. This reduction was associated with enhanced macrophage H2O2 release on zymosan stimulation after 12 weeks on the diet, a similar trend in chemiluminescence and reduced mitogenesis of spleen cell cultures to T and B cell mitogens after 8 weeks on the diet. Macrophage beta-glucuronidase release was not significantly altered. Phorbol myristic acetate induced macrophage H2O2 generation was reduced by selenium deficiency, possibly due to increased cellular damage. Adjuvant arthritis of rats was significantly enhanced after 6 and 12 weeks on the selenium deficient diet. The enhanced release of H2O2 by macrophages after zymosan stimulation can be directly attributable to loss of GSH-Px activity leading to reduced peroxide breakdown. Peroxide-mediated cell injury would also account for the reduction in lymphocyte mitogenesis and enhancement of adjuvant arthritis. These data provide support for a role of selenium in immune and inflammatory responses.

Animal experiments on the safety pharmacology of lofexidine

These experiments were carried out to supplement the pharmacodynamic profile of 2[1-(2,6-dichlorophenoxy)-ethyl]-2-imidazoline hydrochloride (lofexidine, Lofetensin and Loxacor), a potent hypotensive imidazoline derivative with a central mode of action. Effects indicative of a central sedative action were seen in various experiments on mice and rats. However, comparative studies with clonidine, particularly those involving the interaction with hexobarbital, the effect on motor coordination on a rotating rod, the effect on body temperature and other experiments, indicated that lofexidine had a 10 to 100 fold less sedative effect than clonidine, depending on the test and the route of administration. In rats there was a dose-related, diuretic and saluretic effect. This effect was not seen in dogs. In rabbits and guinea pigs, lofexidine exhibited local anaesthetic effects and its potency and duration of action were comparable to those of the reference compounds (tetracaine or mepivacaine). Lofexidine did not modify gastric secretion in rats. On the other hand, it inhibited chemically induced (phenylbutazone) and stress-induced (swimming) gastric ulcer formation in rats. Antiinflammatory and analgesic activities in rats and mice were, at most, very weak. Lofexidine increased blood glucose levels of normoglycaemic rats; clonidine is known to have the same effect. In order to investigate the possibility of combining lofexidine with a diuretic drug for the treatment of hypertension, the interaction with hydrochlorothiazide was studied in some experiments. The results obtained from these experiments showed that there was no adverse effect and the diuretic and saluretic effects of hydrochlorothiazide were not impaired. No findings militated against the use of lofexidine as an antihypertensive drug. It is likely that lofexidine, in contrast to clonidine, has less marked central sedative effects.

Macrophages from different sources, their production of chemiluminescence under various stimuli and the effects of PGE2 and drugs

We are currently characterizing different macrophages sub-populations according to their release of oxygen free radicals (measured as chemiluminescence) under various stimuli and their responses to drugs and mediators. Mouse macrophages were obtained by peritoneal or lung lavage and stimulated in vitro with opsonized zymosan (OpZ) or the calcium ionophore A23187. Chemiluminescence was measured in a luminometer and responses obtained after 5 min expressed as percentages of standard responses to the stimuli. Almost identical dose-response curves to OpZ were obtained with peritoneal and alveolar macrophages, while the dose-response curve of peritoneal macrophages to A23187 was much shallower. The response to A23187 was generally much weaker than that to OpZ and in both types of macrophages PGE2 was a more effective inhibitor of OpZ-induced chemiluminescence than of that induced by A23187. The response to OpZ in peritoneal macrophages was inhibited in a dose-related manner by both PGE2 and superoxide dismutase, but not by indomethacin, d-penicillamine, piroxicam or phenylbutazone. OpZ but not A23187, is a suitable stimulus for pharmacological studies on macrophage chemiluminescence.

[Enzyme, enzyme-histochemical and immunohistological studies in chronic erysipelas polyarthritis of swine]

The chronic Erysipelas-polyarthritis in pigs has been considered an animal model resembling human rheumatoid arthritis. Fifteen specifically pathogenfree (SPF) pigs 45 days old were experimentally infectec with strain T 28 of Erysipelothrix rhusiopathiae-bacteria. During the subsequent 32 weeks several enzymatic, immunohistological and microbiological parameters were monitored. Compared to 5 age and sex matched healthy controls the infected pigs showed increased activity of plasma acid phosphatase starting 4 weeks after the infection. Acid phosphatase activity was usually enhanced in synovial fluid of chronically ill animals. Histochemically increased activity of acid phosphatase, beta-glucuronidase and beta-acetylglucosaminidase was found in lining cells and fibroblasts of the synovial membrane of chronically diseased joints. Immunohistochemically Erysipelas-antigen was demonstrated in the synovial membrane even of those inflamed joints from which no living bacteria had been isolated. The microbiological and immunohistochemical results correlated positively with the enzymehistochemical data. The release of lysosomal enzymes from cells of the synovial membrane in chronically diseased joints due to the influence of Erysipelas-bacteria and the possible implications of persistent bacteria on the perpetuation of chronic Erysipelas-polyarthritis are discussed.