Acyl CoA/diacylglycerol acyltransferase (DGAT) 1 is one of two known DGAT enzymes that catalyze the final and only committed step in triglyceride biosynthesis. The purpose of this study was to test the hypothesis that chronic inhibition of DGAT-1 with a small-molecule inhibitor will reduce serum triglyceride concentrations in both genetic and diet-induced models of hypertriglyceridemia. Zucker fatty rats and diet-induced dyslipidemic hamsters were dosed orally with A-922500 (0.03, 0.3, and 3-mg/kg), a potent and selective DGAT-1 inhibitor, for 14 days. Serum triglycerides were significantly reduced by the 3 mg/kg dose of the DGAT-1 inhibitor in both the Zucker fatty rat (39%) and hyperlipidemic hamster (53%). These serum triglyceride changes were accompanied by significant reductions in free fatty acid levels by 32% in the Zucker fatty rat and 55% in the hyperlipidemic hamster. In addition, high-density lipoprotein-cholesterol was significantly increased (25%) in the Zucker fatty rat by A-922500 administered at 3 mg/kg. This study provides the first report that inhibition of DGAT-1, the final and only committed step of triglyceride synthesis, with a selective small-molecule inhibitor, significantly reduces serum triglyceride levels in both genetic and diet-induced animal models of hypertriglyceridemia. The results of this study support further investigation of DGAT-1 inhibition as a novel therapeutic approach to the treatment of hypertriglyceridemia in humans, and they suggest that inhibition of triglyceride synthesis may have more diverse beneficial effects on serum lipid profiles beyond triglyceride lowering.

S1P5 is one of 5 receptors for sphingosine-1-phosphate and is highly expressed on endothelial cells within the blood-brain barrier, where it maintains barrier integrity in in vitro models (J. Neuroinflamm. 2012, 9, 133). Little more is known about the effects of S1P5 modulation due to the absence of tool molecules with suitable selectivity and drug-like properties. We recently reported that molecule A-971432 (Harris, 2010) (29 in this paper) is highly efficacious in reversing lipid accumulation and age-related cognitive decline in rats (Van der Kam , , AAIC 2014). Herein we describe the development of a series of selective S1P5 agonists that led to the identification of compound 29, which is highly selective for S1P5 and has excellent plasma and CNS exposure after oral dosing in preclinical species. To further support its suitability for in vivo studies of S1P5 biology, we extensively characterized 29, including confirmation of its selectivity in pharmacodynamic assays of S1P1 and S1P3 function in rats. In addition, we found that 29 improves blood-brain barrier integrity in an in vitro model and reverses age-related cognitive decline in mice. These results suggest that S1P5 agonism is an innovative approach with potential benefit in neurodegenerative disorders involving lipid imbalance and/or compromised blood-brain barrier such as Alzheimer's disease or multiple sclerosis.

Introduction:Surgical 5/6 nephrectomy and adenine-induced kidney failure in rats are frequently used models of progressive renal failure. In both models, rats develop significant morphological changes in the kidneys and quantification of these changes can be used to measure the efficacy of prophylactic or therapeutic approaches. In this study, the Aperio Genie Pattern Recognition technology, along with the Positive Pixel Count, Nuclear and Rare Event algorithms were used to quantify histological changes in both rat renal failure models.Methods:Analysis was performed on digitized slides of whole kidney sagittal sections stained with either hematoxylin and eosin or immunohistochemistry with an anti-nestin antibody to identify glomeruli, regenerating tubular epithelium, and tubulointerstitial myofibroblasts. An anti-polymorphonuclear neutrophil (PMN) antibody was also used to investigate neutrophil tissue infiltration.Results:Image analysis allowed for rapid and accurate quantification of relevant histopathologic changes such as increased cellularity and expansion of glomeruli, renal tubular dilatation, and degeneration, tissue inflammation, and mineral aggregation. The algorithms provided reliable and consistent results in both control and experimental groups and presented a quantifiable degree of damage associated with each model.Conclusion:These algorithms represent useful tools for the uniform and reproducible characterization of common histomorphologic features of renal injury in rats.

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A high-throughput screen against human DGAT-1 led to the identification of a core structure that was subsequently optimized to afford the potent, selective, and orally bioavailable compound 14. Oral administration at doses ≥0.03 mg/kg significantly reduced postprandial triglycerides in mice following an oral lipid challenge. Further assessment in both acute and chronic safety pharmacology and toxicology studies demonstrated a clean profile up to high plasma levels, thus culminating in the nomination of 14 as clinical candidate ABT-046.