Prostaglandins and surgical diseases: Part I

In vitro effects of prostaglandin E1 and indomethacin on mitomycin C-induced sister-chromatid exchanges in mitogen-stimulated human lymphocytes

In this study, the individual and combined effects of prostaglandin E1 (PGE1) and Indomethacin on mitomycin C (MMC)-induced SCEs in human lymphocytes was investigated in vitro. All MMC-treated cultures showed a great increase of SCEs (approximately two-fold), indicating its ability to induce mutations. SCE data showed that MMC-induced SCEs were reduced significantly in the presence of PGE1 in pooled analysis of six experiments (60.55% reduction of SCEs at 10(-6) M, 34.13% reduction of SCEs at 10(-9) M). In contrast the presence of indomethacin in the medium during MMC treatment of cells failed to show a significant reduction of SCEs in pooled analysis (21.17%). However, individual analyses revealed only two of six donors with a significant SCE response. Thus, the findings suggest that PGE1 can modify the DNA damaging effect of carcinogens and thereby may prevent the initiation of the carcinogenic process.

Effect of PGE in multiple experimental models. IX: In vivo effects of PGE on immune response of leucocytes to wounds

There have been conflicting results obtained when comparing the in vitro with in vivo effects of prostaglandin E (PGE) on immune function. The in vitro studies have demonstrated immune suppression with PGE administration while the in vivo studies demonstrated improved survival when utilizing infected models. To attempt to resolve this discrepancy, we evaluated the in vivo effect of PGE on host immune function utilizing multiple rat models. PGE was found to have no effect on the ability of leucocytes to infiltrate a sponge matrix wound over a 2-week period of study. PGE also failed to alter the percentage of T-lymphocyte subset populations infiltrating the sponge matrix model. There was noted to be no effect of PGE on the ability of neutrophils to chemiluminescence, or on metabolic function of lymphocytes. In conclusion, PGE does not appear to have immunosuppressive properties when studied using certain in vivo models.

Effect of prostaglandin E in multiple experimental models. IV. Effect on resistance to endotoxin and tumor necrosis factor shock

Administration of a long-acting prostaglandin E, 16,16-dimethyl-PGE (dPGE), to rats improves their survival of bacterial peritonitis. We examined the mechanism of this protective effect with reference to its interaction with the release of cachectin (TNF). Sixty rats received saline, 20 micrograms/kg dPGE, or 80 micrograms/kg dPGE 12 hr prior to endotoxin and continuing for 48 hr. Survival rates for the saline, 20 micrograms/kg dPGE, and 80 micrograms/kg dPGE groups were 0, 40, and 85%, respectively. Forty rats received saline or 80 micrograms/kg dPGE, with the initial dose being 3 hr following endotoxin challenge and continuing for 48 hr. Survival rates for both groups were 0%. Sixty rats received saline or 80 micrograms/kg dPGE at 12 and 1 hr prior to endotoxin. Two hours after challenge, they were sacrificed and plasma TNF levels were assayed. The plasma TNF level in saline-treated rats was 22.72 +/- 0.83 ng/ml and in the dPGE-treated group, 16.03 +/- 1.13 ng/ml (P less than 0.001).

Effect of prostaglandin E in multiple experimental models. VII. Effect on resistance to sepsis

The immunosuppression seen following burn injury has frequently been attributed to elevated prostaglandin E levels. We evaluated the contribution of elevated prostaglandin E levels on susceptibility to infectious complications utilizing multiple mouse models. The administration of 100 micrograms/kg of the long-acting derivative of prostaglandin E, 16,16-dimethyl-prostaglandin E, was found to improve survival in C3/HEN mice challenged with 1 x 10(8) Escherichia coli organisms intraperitoneally. The administration of indomethacin was found to decrease survival in the same model. With C3/HEJ (endotoxin-resistant) mice, indomethacin was found to increase mortality rates in animals challenged with 1 x 10(8), 1 x 10(9) or 1 x 10(10) Escherichia coli organisms. These findings suggest that elevated prostaglandin E levels seen in burn patients may not be responsible for the postburn increased susceptibility to infectious complications.

Postburn suppression of murine lymphocyte and neutrophil functions is not reversed by prostaglandin blockade

Certain arachidonic acid metabolites, including prostaglandins (PGs) E1 and E2, have been shown to exert marked immunosuppressive effects on T-cell and macrophage functions. Cyclooxygenase blockade with indomethacin or ibuprofen may ameloriate these effects. In the current study we measured lymphocyte proliferation by thymidine incorporation, the presence of T-cell activation antigens with monoclonal antibodies and two-color flow cytometry, and neutrophil (PMN) oxidative burst using a fluorescent marker, in control mice and in burned mice treated with indomethacin for 10 days after injury. One-half of the cell cultures were treated with indomethacin in vitro to ensure its continued presence during stimulation. Separate groups of mice were fed a fish oil-based diet which leads to the production of PGE3 rather than PGE2, versus standard mouse chow, a soy-bean oil-based diet which leads to PGE2 production. Lymphocyte proliferation, expression of T-cell activation antigens, and PMN oxidative burst remained depressed in burned mice treated with indomethacin in vivo (plus in vitro) and in those which received the fish oil-based diet, compared to control. Blockade of PG synthesis after murine burn injury by cyclooxygenase inhibition or alterations in the diet failed to restore T-lymphocyte activation or proliferation or to improve PMN oxidative burst. These data suggest that PGE2 alone does not explain the immunosuppression noted after burn injury.

Effect of prostaglandin E in multiple experimental models. VI. Effect on T-cell subsets

Burn injuries have been shown to impair immune function. One of the hypotheses for the etiology of the immunosuppression is that burn injuries result in an elevation of prostaglandin E (PGE) levels which then impair leukocyte function. We evaluated the effect of PGE levels on immune function in multiple animal models utilizing T cell subset levels for our immunologic measurements. Elevations in PGE levels were achieved by administering 16,16-dimethyl-prostaglandin E (dPGE) and reductions by administering indomethacin. The animal models included burned rats, burned-septic rats, and nonburned rats. Neither indomethacin nor dPGE administration resulted in alterations of any of the T cell subset populations in our models.