Severity and mortality of experimental pancreatitis are dependent on interleukin-1 converting enzyme (ICE).

Interleukin-1 beta (IL-1 beta) is produced in large amounts during acute pancreatitis and is believed to play a role in disease progression. Because secretion of IL-1 beta is dependent on intracellular processing of pro-IL-1 beta by IL-1 converting enzyme (ICE), we aimed to determine the efficacy of a novel ICE inactivator (VE-13045) in inhibiting secretion of active IL-1 beta in vivo and if the loss of ICE activity would affect the severity and mortality of experimental pancreatitis. Severe hemorrhagic pancreatitis was induced in adult rats by infusion of bile acid into the pancreatic duct. Animals were randomized to receive VE-13045 or vehicle before induction of pancreatitis. To confirm our findings and to ensure that the results were not model dependent, a second series of experiments was conducted using mice possessing a homozygous knockout of the ICE gene in which lethal pancreatitis was induced by feeding a choline-deficient, ethionine-supplemented diet. The severity of pancreatitis was assessed for both experiments by standard surrogate markers, blind histologic grading, and serum IL-1 beta and tumor necrosis factor-alpha (TNF-alpha) levels. Pancreatic IL-1 beta mRNA induction was assessed by differential RT-PCR. Acute pancreatitis was associated with a 120-fold increase in IL-1 beta mRNA, which was not affected by ICE inhibition or gene deletion. Cytokine processing and secretion were affected, as evidenced by decreased serum levels of IL-1 beta and TNF-alpha (p < 0.001) in all animals with an inactive ICE enzyme. This lack of cytokine production increased survival from 32% to 78% following bile salt pancreatitis (p < 0.01) and from 24% to 80% following diet-induced pancreatitis (p < 0.005). Both ICE-defective groups demonstrated decreased pancreatic necrosis, edema, inflammation, wet weight (all p < 0.05), and amylase and lipase (p < 0.01). In vivo blockade or genetic deletion of ICE inhibits pancreatitis-induced secretion of proinflammatory cytokines without altering IL-1 mRNA production and is associated with decreased pancreatitis severity and dramatic survival benefits.

The nuclear hormone receptor coactivator SRC-1 is a specific target of p300.

p300 and its family member, CREB-binding protein (CBP), function as key transcriptional coactivators by virtue of their interaction with the activated forms of certain transcription factors. In a search for additional cellular targets of p300/CBP, a protein-protein cloning strategy, surprisingly identified SRC-1, a coactivator involved in nuclear hormone receptor transcriptional activity, as a p300/CBP interactive protein. p300 and SRC-1 interact, specifically, in vitro and they also form complexes in vivo. Moreover, we show that SRC-1 encodes a new member of the basic helix-loop-helix-PAS domain family and that it physically interacts with the retinoic acid receptor in response to hormone binding. Together, these results implicate p300 as a component of the retinoic acid signaling pathway, operating, in part, through specific interaction with a nuclear hormone receptor coactivator, SRC-1.

Interleukin-1 beta converting enzyme inhibition blocks progression of type II collagen-induced arthritis in mice.

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.

Ex vivo lipopolysaccharide-induced interleukin-1 secretion from murine peritoneal macrophages inhibited by probucol, a hypocholesterolemic agent with antioxidant properties.

Probucol, 4,4'-(isopropylidenedithio)bis(2,6-di-tert-butyl-phenol), has been shown to inhibit atherogenesis in genetically hypercholesterolemic (Watanabe) rabbits. Since atherosclerotic lesions contain macrophages capable of screting interleukin 1 (IL 1) and other cytokines that could contribute to the pathogenesis of the disease, we have investigated whether probucol affects IL 1 secretion. Resident peritoneal macrophages from mice dosed with probucol secreted 40-80% less IL 1 than macrophages from control animals when stimulated in vitro with lipopolysaccharide (LPS). The inhibitory effect of probucol was observed when IL 1 was assayed by the standard bioassay, the thymocyte proliferation assay, or a competitive IL 1 receptor binding assay. Probucol treatment had no effect on LPS-induced membrane IL 1 expression; secretion of tumor necrosis factor (TNF); Con A-induced splenic interleukin 2 (IL 2) and interleukin 3 (IL 3) release; and prostaglandin- or zymosan-induced secretion of prostacyclin, leukotriene C4, acid phosphatase, or superoxide anion. In contrast to the effect of oral administration, direct addition of probucol to macrophage cultures did not inhibit IL 1 release. Probucol administration did, however, inhibit the fall in serum zinc level induced by intravenous injection of LPS in zymosan-primed mice but had no effect on the LPS-induced increase in serum triglyceride levels, which indirectly confirms that probucol administration inhibits IL 1 but not TNF secretion. Paw granuloma induced in mice by heat-killed mycobacteria was inhibited by oral administration of probucol, an effect that may be attributable to inhibition of IL 1 secretion. Probucol neither reduced zymosan-induced liver granulomata in mice nor inhibited adjuvant-induced arthritis in rats. We suggest that inhibition of IL 1 secretion from macrophages by probucol contributes to its therapeutic effects in atherosclerosis and may also result in beneficial activity in some chronic inflammatory diseases.

Neural factors contribute to atherogenesis.

Electron microscopic evidence of early atherogenic changes in the aorta and coronary arteries was obtained in normal fed, conscious, unrestrained rats receiving electrical stimulation in the lateral hypothalamus for periods of up to 62 days. Hypertension and hypercholesterolemia were not etiologic factors. In view of recent observations concerning neuropsychological mechanisms in human ischemic heart disease, the findings raise the possibility that the human central nervous system has a role in the development of atherosclerotic lesions.