calcimycin and Colitis--Ulcerative

Colonic biopsy specimens from patients with active ulcerative colitis and controls were incubated for four hours in the presence or absence of calcium ionophore or antihuman immunoglobulin E (IgE). Platelet-activating factor (PAF) was determined in the tissue by aggregation assay after extraction with 80% ethanol. PAF was not detected in normal mucosa, whereas A23187 and antihuman IgE stimulated its activity: mean +/- SE, 43.2 +/- 8.6 and 33.0 +/- 6.1 pg/10 mg wet weight, respectively. In active ulcerative colitis, A23187 and antihuman IgE induced significantly higher stimulation of PAF synthesis compared to their effects on normal mucosa. The enhanced stimulation of PAF induced by A23187 was dose-dependently inhibited by sulphasalazine, 5-aminosalicylic acid and prednisolone, but not by sulfapyridine. Colonic interleukin-1 content and release during 24 h of culture were significantly higher in patients with active ulcerative colitis and Crohn's disease compared to normal subjects. Prednisolone significantly and dose-dependently inhibited interleukin-1 release. These results suggest that colonic generation of PAF and interleukin-1 are elevated in patients with inflammatory bowel disease and, thus, may have a role in its pathogenesis. Pharmacological suppression of colonic PAF and interleukin-1 production may have beneficial therapeutic effects.

Topics: Aminosalicylic Acids; Anti-Inflammatory Agents, Non-Steroidal; Antibodies, Anti-Idiotypic; Calcimycin; Colitis, Ulcerative; Colon; Crohn Disease; Humans; Imidazoles; Immunoglobulin E; Interleukin-1; Intestinal Mucosa; Mesalamine; Organ Culture Techniques; Platelet Activating Factor; Prednisolone; Sulfasalazine; Thiazoles

Eicosanoids were measured in colonic biopsies from eleven patients with active ulcerative colitis and from thirteen controls. Eicosanoid formation was measured after the addition of arachidonic acid and stimulation with calcium ionophore A23187. The 15-lipoxygenase derivative 15-hydroxy-eicosatetraenoic acid (15-HETE) was the predominant product formed in all biopsies. The amount of 15-HETE formed was dependent on the site of biopsy and decreased in the controls in biopsies taken in an aboral direction in the colon. The formation of 15-HETE and that of prostaglandin E2 (PGE2) and PGF2 alpha was proportional to the histologically obtained inflammation score. The role of 15-H(P)ETE as a mediator in ulcerative colitis should, therefore, be considered in addition to the effects of known modulators such as leukotriene B4 (LTB4) and PGE2.

Topics: Adult; Arachidonic Acid; Biopsy; Calcimycin; Colitis, Ulcerative; Colon; Eicosanoids; Female; Humans; Hydroxyeicosatetraenoic Acids; Intestinal Mucosa; Male; Middle Aged

The synthesis of 14C labelled arachidonic acid metabolites was measured in colonic tissues obtained from mice, rats, guinea pigs, rabbits, piglets and in colonic biopsies from humans during colonoscopy. The main eicosanoids formed after stimulation with calcium ionophore A23187 were: in humans, 15-hydroxy-eicosatetraenoic acid (15-HETE); in mice, 12-HETE; in rats, 12-HETE, 12-hydroxy-5,8,10-heptadecatrienoic acid (HHT) and 6-keto-prostaglandin F1 alpha (6kPGF1 alpha); in guinea pigs, PGD2; in rabbits, 6kPGF1 alpha, PGE2 and 15-HETE; and in pigs PGE2 and 12-HETE. In inflamed 15-HETE production was increased in man, HHT and 12-HETE production in rats and overall eicosanoid production in mice.

Topics: 12-Hydroxy-5,8,10,14-eicosatetraenoic Acid; 6-Ketoprostaglandin F1 alpha; Animals; Calcimycin; Colitis, Ulcerative; Colon; Dinoprostone; Eicosanoids; Fatty Acids, Unsaturated; Guinea Pigs; Humans; Hydroxyeicosatetraenoic Acids; Intestinal Mucosa; Mice; Mice, Inbred BALB C; Prostaglandin D2; Rabbits; Rats; Rats, Wistar; Species Specificity

Platelet-activating factor is released from inflammatory cells. It activates neutrophils, releases secondary messengers, and mediates mucosal ulceration and ischemia in the rat. We assessed its possible role in the pathogenesis of ulcerative colitis. Colonic biopsy specimens from patients with active ulcerative colitis and controls were incubated for 4 h in Tyrode's buffer in the presence or absence of 0.2 microM calcium ionophore (A23187) or 50 microliter of antihuman immunoglobulin E. Platelet-activating factor was determined in the tissue by aggregation assay after extraction with 80% ethanol and was confirmed by thin-layer chromatography and its inactivation by phospholipases. Platelet-activating factor was not detected in normal mucosa. Only A23187 and antihuman immunoglobulin E stimulated its activity: mean +/- SE, 43.2 +/- 8.6 and 33.0 +/- 6.1 pg/10 mg wet wt, respectively. In active ulcerative colitis basal platelet-activating factor activity was 8.9 +/- 3.5 pg/10 mg wet wt. A23187 and antihuman immunoglobulin E induced significantly higher stimulation of platelet-activating factor synthesis when compared with their effects on normal mucosa: 200 +/- 28 and 70 +/- 8.3 pg/10 mg wet wt, respectively. The enhanced stimulation induced by A23187 was dose-dependently inhibited by salazopyrine, 5-amino-salicylic acid, and prednisolone, but not by sulfapyridine. It is thus suggested that platelet-activating factor may be involved in the pathogenesis of the inflammatory response in ulcerative colitis and that its inhibition by steroids, 5-aminosalicylic acid, and salazopyrine may be an additional mechanism to explain their therapeutic effects.

Topics: Adult; Aminosalicylic Acids; Calcimycin; Colitis, Ulcerative; Colon; Drug Combinations; Female; Glucosamine; Humans; Immunoglobulin E; Intestinal Mucosa; Male; Middle Aged; Platelet Activating Factor; Prednisolone; Rectum; Sulfapyridine; Sulfasalazine

The metabolism of endogenous arachidonic acid P(AA) was investigated in activated neutrophils from 20 patients with Crohn's disease, 20 with ulcerative colitis, and 25 healthy volunteers. 1-14C-P(AA) was incorporated into intracellular pools of phospholipids prior to activation of the cells with ionophore A23187 and analyses of released arachidonic acid metabolites by thin layer chromatography. Total release of radioactivity expressing the release of arachidonic acid and its metabolites, was equal in the experimental and control groups, which suggests a normal substrate availability. In contrast, there was a marked increase in the relative release of leucotriene B4 (LTB4) and its omega-oxidation products, 20-hydroxy-LTB4 (20-OH-LTB4) and 20-carboxy-LTB4 (20-COOH-LTB4), with LTB4 values exceeding the reference interval in seven of 20 patients with Crohn's disease, median 8.7%, and in six of 20 patients with ulcerative colitis, median 7.7%, as compared with a median of 5.3% in healthy volunteers. Furthermore, a decreased release of unmetabolised arachidonic acid, correlating inversely with the release of LTB4 in all experimental and control groups, and normal values for the production of other metabolites of arachidonic acid--for example, 5-hydroxyeicosatetraenoic acid (5-HETE) and 12-hydroxyheptadecatrienoic acid (HHT), point to an enzymatic abnormality such as increased activity of leucotriene B synthetase. An increased capacity for release of LTB4, the major pro-inflammatory metabolite of arachidonic acid lipoxygenation by polymorphonuclear leucocytes, may contribute to perpetuation of the inflammation and to tissue destruction in chronic inflammatory bowel disease. Our findings agree with previous reports of an increased release of LTB4 by the colonic mucosa in this condition.

Topics: Adolescent; Adult; Arachidonic Acid; Arachidonic Acids; Calcimycin; Colitis, Ulcerative; Crohn Disease; Female; Humans; Hydroxyeicosatetraenoic Acids; Leukotriene B4; Male; Middle Aged; Neutrophils