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To IL-1 beta is a principal mediator in the pathogenesis of inflammatory disease. The IL-1 beta-converting enzyme (ICE), a novel cysteine protease, is required for processing of the 31 kDa IL-1 beta precursor to generate the 17 kDa proinflammatory mature form. We investigated the effect of two irreversible peptidyl ICE inhibitors, VE-13,045 and VE-16,084, on IL-1 production in vitro and in vivo in acute and chronic inflammatory disease models. In vitro, VE-13,045 and VE-16084 inhibited IL-1 beta secretion by LPS-stimulated human adherent mononuclear cells (IC50's of 0.4 microM and 2.0 microM, respectively) and murine splenic monocytes (IC50's of 10 microM and 1.3 microM, respectively). Both VE-13,045 and VE-16,084 also inhibited LPS stimulated IL-1 alpha secretion, although with reduced potency. In vivo, a single intraperitoneal dose of VE-13,045 (50 mg/kg) administered to mice 60 to 75 minutes after a 40 mg/kg LPS challenge significantly reduced IL-1 beta serum levels by 50 to 70%. In the DBA/1J mouse model of Type II collagen-induced arthritis, prophylactic treatment with VE-13,045 (50 and 100 mg/kg/day) significantly delayed the onset of inflammation, with a 60% overall reduction in disease severity. VE-13,045 was more effective than either indomethacin (2 mg/kg/day) or methyl prednisolone (10 mg/kg/day). VE-13,045 was also effective in reducing inflammation and progression of arthritis when administered to mice with established disease. Histological analysis of wrist joints showed a reduction in synovial membrane damage, inflammatory cell infiltration and fibrosis, and cartilage erosion in VE-13,045-treated animals. This is the first demonstration of efficacy for an ICE inhibitor in a chronic disease model and suggests that ICE is an important target for design of anti-inflammatory or disease modifying drugs.

We measured gastric and duodenal mucosal prostaglandin concentrations in 69 patients with active or inactive duodenal or gastric ulcer disease and 26 non-ulcer controls. Each underwent endoscopy enabling us to obtain multiple biopsies from the gastric body and antrum and from the duodenal bulb and postbulbar duodenum for measurement of mucosal prostaglandin concentrations, as well as a single biopsy from each region for mucosal histology. Using a multivariate linear regression model, we found that neither gastric nor duodenal ulcer disease significantly affected gastric or duodenal mucosal prostaglandin concentrations. Mucosal prostaglandin concentrations were similar at the edge of the ulcer and in the adjacent non-ulcerated mucosa. Neither gender symptoms, smoking, use of H2-receptor antagonists, disease activity, nor Helicobacter pylori infection had an independent effect on mucosal prostaglandins in any region. Gastritis in the body of the stomach was associated with significantly higher prostaglandins, while older age was associated with significantly lower gastric and duodenal prostaglandins. Gastroduodenal mucosal prostaglandins are thus not altered in patients with active or inactive peptic ulcer disease, even when multiple demographic and histologic variables are taken into consideration.

Gastric mucosal prostaglandin E2 and F2 alpha content was evaluated in healthy human subjects who received either fish oil or olive oil (control) daily for 3 wk before exposure to aspirin or no aspirin. Two hours after aspirin administration, when mean serum salicylate concentration was approximately 12 mg/dl, gastric mucosal prostaglandin E2 and F2 alpha content was reduced by greater than 95% in the fundus and antrum (p less than 0.001) and there was endoscopic evidence of gastric mucosal damage (erosions, submucosal hemorrhages). Fish oil feeding had no significant effect on mucosal prostaglandin E2 or F2 alpha content or on the damaging effect of aspirin on the stomach, despite the fact that fish oil reduced serum triglyceride concentrations significantly. These studies indicate that the damaging effects of aspirin on the gastric mucosa are not influenced by dietary fish oil.

The role of prostaglandins in regulating splanchnic blood flow during hemorrhage has been investigated in the anesthesized dog using the microsphere technique. Indomethacin selectively decreased blood flow to the gastrointestinal tract, but did not change hepatic arterial flow. Hemorrhage (5 ml/kg and 10 ml/kg) generally increased peripheral resistance in the gastrointestinal tract as much as total peripheral resistance was increased. However, resistance in the stomach and pancreas increased to a greater extent while there was no change in hepatic arterial resistance. The effect of hemorrhage on splanchnic blood flow distribution was not changed by prior indomethacin treatment. Thus, prostaglandins contribute to the regulation of basal flow to the gastrointestinal tract but are not involved in regulatory changes in splanchnic blood flow during hemorrhage. The enhanced sensitivity of the gastric and pancreatic vascular beds to hemorrhage may contribute to local toxicity during hemorrhage.

In humans eicosapentaenoic acid can be converted to 3-series prostaglandins (PGF3 alpha, PGI3, and PGE3). Whether 3-series prostaglandins can protect the gastric mucosa from injury as effectively as their 2-series analogs is unknown. Therefore, we compared the protective effects of PGF3 alpha and PGF2 alpha against gross and microscopic gastric mucosal injury in rats. Animals received a subcutaneous injection of either PGF3 alpha or PGF2 alpha in doses ranging from 0 (vehicle) to 16.8 mumol/kg and 30 min later they received intragastric administration of 1 ml of absolute ethanol. Whether mucosal injury was assessed 60 min or 5 min after ethanol, PGF3 alpha was significantly less protective against ethanol-induced damage than PGF2 alpha. These findings indicate that the presence of a third double bond in the prostaglandin F molecule between carbons 17 and 18 markedly reduces the protective effects of this prostaglandin on the gastric mucosa.