Shari L. Caplan

Effect of Matrix Metalloproteinase Inhibition on Progression of Atherosclerosis and Aneurysm in LDL Receptor‐Deficient Mice Overexpressing MMP‐3, MMP‐12, and MMP‐13 and on Restenosis in Rats after Balloon Injury

ABSTRACT: The broad‐spectrum MMP inhibitor CGS 27023A was tested to determine its potential as a therapy for atherosclerosis, aneurysm, and restenosis. LDL receptor‐deficient (LDLr −/−) mice fed a high‐fat, cholic acid‐enriched diet for 16 weeks developed advanced aortic atherosclerosis with destruction of elastic lamina and ectasia in the media underlying complex plaques. Lesion formation correlated with a 4.6‐ to 21.7‐fold increase in MMP‐3, ‐12, and ‐13 expression. Treatment with CGS 27023A (p.o., b.i.d. at 50 mg/kg) had no effect on the extent of aortic atherosclerosis (36 ± 4% versus 30 ± 2% in controls), but both aortic medial elastin destruction and ectasia grade were significantly reduced (38% and 36%, respectively, p < 0.05). In the rat ballooned‐carotid‐artery model, CGS 27023A (12.5 mg/kg/day via osmotic minipump) reduced smooth muscle cell migration at 4 days by 83% (p < 0.001). Intimal lesions were reduced by 85% at 7 days (p < 0.001), but intimal smooth muscle proliferation was unaffected, and inhibitory efficacy was lost with time. At 12 days, intimal lesion reduction was less potent (52%, p < 0.01). At 3 and 6 weeks, reductions of 11% and 4%, respectively, were not significant. This demonstrates that it is essential to include late time points when the ballooned‐carotid‐artery model is employed to ensure that lesion size does not “catch up” when a compound solely inhibits smooth muscle cell migration. In summary, MMP inhibitor therapy delayed but did not prevent intimal lesions, thereby demonstrating little promise to prevent restenosis. In contrast, MMP inhibitor therapy may prove useful to retard progression of aneurysm.

Investigation of Functionally Liver Selective Glucokinase Activators for the Treatment of Type 2 Diabetes

Type 2 diabetes is a polygenic disease which afflicts nearly 200 million people worldwide and is expected to increase to near epidemic levels over the next 10-15 years. Glucokinase (GK) activators are currently under investigation by a number of pharmaceutical companies with only a few reaching early clinical evaluation. A GK activator has the promise of potentially affecting both the beta-cells of the pancreas, by improving glucose sensitive insulin secretion, as well as the liver, by reducing uncontrolled glucose output and restoring post-prandial glucose uptake and storage as glycogen. Herein, we report our efforts on a sulfonamide chemotype with the aim to generate liver selective GK activators which culminated in the discovery of 3-cyclopentyl-N-(5-methoxy-thiazolo[5,4-b]pyridin-2-yl)-2-[4-(4-methyl-piperazine-1-sulfonyl)-phenyl]-propionamide (17c). This compound activated the GK enzyme (alphaK(a) = 39 nM) in vitro at low nanomolar concentrations and significantly reduced glucose levels during an oral glucose tolerance test in normal mice.

Enhanced Expression of Matrix Metalloproteinase-3, -12, and -13 mRNAs in the Aortas of Apolipoprotein E-deficient Mice with Advanced Atherosclerosis

Increased expression of matrix metalloproteinases (MMPs) has been reported at sites of advanced atherosclerosis and aneurysm in humans. 1,2 An animal model that has been reported to develop advanced atherosclerosis and medial elastin degradation with progression to ectasia and aneurysm is the apolipoprotein E–deficient (apoE -/) mouse. 3–5 Using immunohistochemistry, a variety of MMPs have been demonstrated at sites of atherosclerosis and elastin degradation in apoE -/mice on a high-fat diet. 5 However, little information is available on MMP expression in apoE -/mice on a normal diet or in mice that are not as susceptible to atherosclerosis on either normal or high-fat diet. The present study compares mRNA expression of MMP-3, -9, -12, and -13 in mice that are highly susceptible (apoE -/), moderately susceptible (C57BL/6J and B6129F1/J), or resistant (C3H/HeJ and Balb/cJ) to diet-induced atherosclerosis. 6

Cevoglitazar, a Novel Peroxisome Proliferator-Activated Receptor-α/γ Dual Agonist, Potently Reduces Food Intake and Body Weight in Obese Mice and Cynomolgus Monkeys

Cevoglitazar is a dual agonist for the peroxisome proliferator-activated receptor (PPAR)-alpha and -gamma subtypes. Dual activation of PPARalpha and -gamma is a therapeutic approach in development for the treatment of type 2 diabetes mellitus and diabetic dyslipidemia. In this report, we show that, in addition to improving insulin sensitivity and lipid metabolism like other dual PPAR agonists, cevoglitazar also elicits beneficial effects on energy homeostasis in two animal models of obesity. In leptin-deficient ob/ob mice, administration of cevoglitazar at 0.5, 1, or 2 mg/kg for 18 d led to acute and sustained, dose-dependent reduction of food intake and body weight. Furthermore, plasma levels of glucose and insulin were normalized after 7 d of cevoglitazar treatment at 0.5 mg/kg. Plasma levels of free fatty acids and triglycerides were dose-dependently reduced. In obese and insulin-resistant cynomolgus monkeys, treatment with cevoglitazar at 50 and 500 mug/kg for 4 wk lowered food intake and body weight in a dose-dependent manner. In these animals, cevoglitazar also reduced fasting plasma insulin and, at the highest dose, reduced hemoglobin A1c levels by 0.4%. These preclinical results demonstrate that cevoglitazar holds promise for the treatment of diabetes and obesity-related disorders because of its unique beneficial effect on energy balance in addition to improving glycemic and metabolic control.

Characterization of recombinant human acetyl-CoA carboxylase-2 steady-state kinetics.

Acetyl-CoA carboxylase (ACC) catalyzes the carboxylation of acetyl-CoA to form malonyl-CoA, a key metabolite in the fatty acid synthetic and oxidation pathways. The present study describes the steady-state kinetic analysis of a purified recombinant human form of the enzyme, namely ACC2, using a novel LC/MS/MS assay to directly measure malonyl-CoA formation. Four dimensional matrices, in which bicarbonate (HCO(3)(-)), ATP, acetyl-CoA, and citrate were varied, and global data fitting to appropriate steady-state equations were used to generate kinetic constants. Product inhibition studies support the notion that the enzyme proceeds through a hybrid (two-site) random Ter Ter mechanism, one that likely involves a two-step reaction at the biotin carboxylase domain. Citrate, a known activator of animal forms of ACC, activates both by increasing k(cat) and k(cat)/K(M) for ATP and acetyl-CoA.