Immunologic effects of nonsteroidal anti-inflammatory agents

Variation in interferon-gamma responses to Coxiella burnetii antigens with lymphocytes from vaccinated or naturally infected subjects

Previous work in our laboratory has shown that lymphocytes from persons vaccinated with a formalin-inactivated Phase I Q fever vaccine (Q-Vax CSL Ltd) show a mitogenic response to Coxiella burnetii antigens. The mitogenic response is the sum of that from various subsets of CD4+, T helper cells, CD8+ T cells and probably B cells. It does not distinguish between T helper cell responses leading to formation of interferon-gamma (IFN-gamma)--a cytokine responsible for clearing intracellular infection with C. burnetii organisms--and responses of other T cell subsets which may produce disease-enhancing cytokines. The present study analyses (i) the capacity of Q-Vax to induce T cell sensitization which leads to IFN-gamma responses on antigen stimulation, and (ii) the immunomodulatory, (down-regulatory) effects of the Phase I lipopolysaccharide (LPS) of the organism, which interacts with monocyte/macrophages to limit IL-2 production and production of IFN-gamma by sensitized T lymphocytes.

Inhibition of prostaglandin E2 formation and histamine action in cancer immunotherapy

The activity of cell-mediated defense systems is stimulated by consecutive formation of interleukin-1 beta (IL-1 beta), interleukin-2 (IL-2) and interferon gamma (IFN gamma). The system is inhibited by interleukin-4 (IL-4) and also by prostaglandin E2 (PGE2) and histamine, which are released when the immune system is activated. The inhibition is strong in cancer patients, because PGE2 is formed in many cancer cells and its formation is stimulated by IL-1 beta. The release of histamine is also stimulated by IL-1 beta. Thus PGE2 and histamine are feedback inhibitors of cell-mediated immunity. This inhibition can be abolished by inhibitors of the cyclo-oxygenase (e.g. indomethacin) and H-2 receptor antagonists (e.g. cimetidine). This may offer a new option to stimulate the immune system to kill cancer cells.

Treatment with a non-steroidal anti-inflammatory agent delays the growth of spontaneous pulmonary metastases of a mammary adenocarcinoma of non-detected immunogenicity

Previous reports showed that treatment with non-steroidal anti-inflammatory agents (NSAIA) can alter the growth profile of a variety of tumours. In this study, the effect of NSAIA treatment on the growth of the primary tumour and the appearance of spontaneous pulmonary metastases, was investigated. A mammary adenocarcinoma of non-detected immunogenicity, C7HI, was grafted subcutaneously in the lateral flank of Balb/c mice. Oral treatment with approximately 1 mg kg-1 day-1 piroxicam delayed both tumour growth and the growth of pulmonary metastases. Survival of mice bearing the primary tumour was significantly lengthened by anti-inflammatory treatment. Similarly, in separate experiments, after surgical removal of the primary tumour by day 34 after grafting, the group of mice treated orally with piroxicam also exhibited a higher survival rate than the control group. Upon surgical removal of the primary tumour 34 days after grafting, piroxicam treatment significantly decreased both the number and size of pulmonary metastases. The results of this study lends support to the hypothesis that inhibition or modulation of inflammation may delay tumour organisation and growth. It is suggested that piroxicam treatment may be an appropriate adjunct therapy to delay the appearance of pulmonary metastases and to increase life-expectancy in a host whose primary tumour has to be surgically removed.

The cyclo-oxygenase inhibitor, piroxicam, enhances cytokine-induced lymphocyte proliferation in vitro and in vivo

The effects of Piroxicam on the production and activity of lymphoproliferative cytokines (LC) produced by mononuclear phagocytes (MNP) were examined. In vitro, Piroxicam did not affect IL-1 induced thymocyte proliferation (LAF assay). However, the LAF activity from lipopolysaccharide (LPS)-treated MNP cultures was increased after Piroxicam (0.1-20 mumol/L) treatment. The increase in apparent LC activity was largely due to suppression of prostaglandin E2 (PGE2) production. Peripheral blood, spleen and thymus lymphocytes from animals predosed with Piroxicam (5 mg/kg per day for 3 days) synthesized more DNA than untreated mice (as measured by [3H]-thymidine uptake ex vivo). MNP from Piroxicam-treated animals produced significantly more LC. Piroxicam had similar effects in both inflamed and non-inflamed mice. Piroxicam and other non-steroidal anti-inflammatory drugs (NSAID) may therefore stimulate or modulate the immune functions requiring lymphoproliferation by suppressing the formation of PGE2, a natural inhibitor of both LC production and LC-induced lymphoproliferation.

Comparative effect of tiaprofenic acid and piroxicam alone and as adjuvants to antibilharzial therapy on pulmonary granuloma in unsensitized mice

Granulomata formed in the liver or lung of man and animals infected with schistosomiasis are common manifestation of an inflammatory delayed hypersensitivity reaction. Non-steroidal anti-inflammatory drugs (NSAIDs) (tiaprofenic acid and piroxicam) have been used alone and as adjuvants to praziquantel in treating pulmonary granulomata induced in mice by injecting them intravenously with S. mansoni eggs. The size of the granulomata, as well as some immunological parameters, have been measured at the end of treatment. Both anti-inflammatory drugs effectively reduced the size of lung granulomata in a dose-dependent manner. The immediate skin reaction and, to a lesser extent, the delayed reaction were reduced by these drugs. Tiaprofenic acid, but not piroxicam, reduced the percent macrophage migration inhibition in vitro. The combined therapy of either of the drugs with praziquantel did not result in an additive effect.

Aspirin-induced asthma as a viral disease

A hypothesis is presented which states that aspirin-induced asthma results from chronic viral infection. This type of asthma has, indeed, a highly characteristic clinical course, reminiscent of viral upper respiratory tract infection. It is suggested that, in response to a virus, a long time after the initial exposure, specific cytotoxic lymphocytes are produced. Their activity is suppressed by prostaglandin E2 (PGE2) produced by pulmonary alveolar macrophages. Anti-cyclo-oxygenase analgesics block PGE2 production, and allow cytotoxic lymphocytes to attack and kill their target cells, i.e. the virus-affected cells of the respiratory tract. During this reaction, toxic oxygen intermediates, lysosomal enzymes and mediators are released, which precipitate attacks of asthma. These acute attacks can be prevented by avoidance of all drugs with anti-cyclo-oxygenase activity, however, asthma continues to run a protracted course because of chronic viral infection.

An alternate mechanism for regulation of leukotriene production in leukocytes: studies with an anti-inflammatory drug, sodium diclofenac

Sodium diclofenac, a potent cyclooxygenase inhibitor, was recently shown to inhibit arachidonic acid conversion to leukotriene products in human leukocytes. This activity was confirmed by radioimmunoassay in calcium ionophore A 23187-stimulated leukocytes isolated from the rat peritoneal cavity and human peripheral blood. Studies with rat peritoneal leukocytes revealed that this effect was not mediated by inhibition of 5-lipoxygenase or phospholipase A2, but rather through modulation of arachidonic acid uptake and release. The potency of this effect was dependent upon cell type; macrophages being more sensitive to the drug than neutrophils. In leukocytes treated with sodium diclofenac, arachidonic acid released from phospholipids in response to A 23187 challenge was reincorporated into triacylglycerols. The drug enhanced the spontaneous uptake of arachidonic acid into the cellular triacylglycerol pool and, in this manner, decreased the availability of intracellular arachidonic acid. Therefore, sodium diclofenac, in addition to inhibition of cyclooxygenase, regulates leukotriene production of inflammatory cells by a mechanism mediated in part through the redistribution of arachidonic acid in lipid pools.