Comparison of the course of biomarker changes and kidney injury in a rat model of drug-induced acute kidney injury.

OBJECTIVE: To aid in evaluating the performance of biomarkers, we measured kidney injury biomarkers in rat models of drug-induced acute kidney injury. METHODS AND RESULTS: Rats were treated with site-specific nephrotoxins, puromycin, gentamicin, cisplatin, or 2-bromoethylamine. Fifteen biomarkers (ß-2-microglobulin, calbindin, clusterin, cystatin-C, KIM-1, GST-α, GST-µ, NGAL, osteopontin, EGF, TIMP-1, VEGF, albumin, RPA-1, and urinary total protein) were examined in comparison with BUN, serum creatinine, and NAG. Some biomarkers, which were different depending in each nephrotoxin, showed ability to detect the prodromal stage of drug-induced kidney injury. Characteristic changing patterns of biomarkers were also found depending on the specific lesion site in the kidney. CONCLUSION: These data suggested that establishment of a suitable biomarker panel would facilitate detection of site-specific kidney injury with high sensitivity.

Effect of the inosine 5'-monophosphate dehydrogenase inhibitor BMS-566419 on renal fibrosis in unilateral ureteral obstruction in rats.

Chronic allograft nephropathy (CAN) is a major cause of late allograft loss. One morphological characteristic of CAN is renal interstitial fibrosis. Mycophenolate mofetil (MMF), the inosine 5'-monophosphate dehydrogenase (IMPDH) inhibitor, has been reported to attenuate the progression of renal interstitial fibrosis. However, the question of whether the newly synthesized IMPDH inhibitors with structures different from MMF have an antifibrotic effect remains unanswered. We evaluated the antifibrotic effects of BMS-566419, a chemically synthesized IMPDH inhibitor, using an experimental rat model, unilateral ureteral obstruction (UUO), in comparison with those of MMF. Expression levels of monocyte chemoattractant protein-1 (MCP-1) and transforming growth factor-beta1 (TGF-ß1), which play important roles in UUO-induced renal fibrosis, were also investigated to determine the mechanism by which BMS-566419 affects the progression of renal fibrosis. After 14 days of UUO, interstitial fibrosis was frequently observed in the renal cortex of rats administered vehicle control. BMS-566419 by oral administration showed a significant and dose-dependent suppressive effect on UUO-induced renal fibrosis in histopathological experiments. BMS-566419 treatment also decreased collagen content, as indicated by hydroxyproline concentration, and the expression of collagen type 1 mRNA. BMS-566419 also decreased the expression of mRNA for both MCP-1 and TGF-ß1. The antifibrotic effects of treatment with BMS-566419 at 60 mg/kg seemed comparable to those with MMF at 40 mg/kg. These results suggest that BMS-566419 and other chemically synthesized IMPDH inhibitors have beneficial pharmacological effects similar to those of MMF, and are potential pharmaceutical candidates in the treatment of fibrotic renal disease, including CAN.

Effect of the inosine 5'-monophosphate dehydrogenase inhibitor BMS-566419 on rat cardiac allograft rejection.

Inosine 5'-monophosphate dehydrogenase (IMPDH) inhibition is a critical target in solid organ transplantation, and the development of mycophenolate mofetil (MMF) represents a major advance in transplant medicine. In this study, the in vitro and in vivo pharmacological effects of BMS-566419, a novel chemically synthesized IMPDH inhibitor, were compared to those of mycophenolic acid (MPA) and MMF based on results from several immunological experiments. The in vitro inhibitory activity of BMS-566419 on IMPDH type I/II, immune cell proliferation and antibody production from lipopolysaccharide (LPS)-stimulated B cells was similar, albeit slightly less potent than that of MPA. In a rat heterotopic cardiac transplant model, monotherapy using orally administered BMS-566419 60mg/kg or MMF 40mg/kg prolonged the median survival time (MST) of transplanted grafts in the vehicle group from 5 to 18 and 18.5 days, respectively. In the presence of a sub-therapeutic dose of FK506, BMS-566419 30mg/kg and MMF 20mg/kg showed identical efficacy with an MST of 21.5 days. In dinitrophenol-LPS-stimulated rats in which calcineurin inhibitors failed to inhibit antibody production, in vivo oral administration of BMS-566419 resulted in antibody production suppression with similar efficacy to MMF. The in vivo antibody production against alloantigen was also suppressed by MMF or BMS-566419 treatment. In addition, gastrointestinal toxicity, considered a dose-limiting factor of MMF, was reduced in BMS-566419 treatment. These results suggest that BMS-566419 and other chemically synthesized IMPDH inhibitors have beneficial pharmacological effects similar to those of MMF, and are potential pharmaceutical candidates in transplant indications.

Implitapide, a microsomal triglyceride transfer protein inhibitor, reduces progression of atherosclerosis in apolipoprotein E knockout mice fed a Western-type diet: involvement of the inhibition of postprandial triglyceride elevation.

Microsomal triglyceride transfer protein (MTP) is essential for the synthesis of both chylomicron in the intestine and very low-density lipoprotein in the liver. An MTP inhibitor, (2S)-2-cyclopentyl-2-[4-[(2,4-dimethyl-9H-pyrido[2,3-b]indol-9-yl)methyl]phenyl]-N-[(1S)-2-hydroxy-1-phenylethyl]ethanamide (implitapide), has been shown to suppress atherosclerosis in apolipoprotein E knockout (apoE KO) mice. To elucidate the antiatherosclerotic mechanisms of implitapide in the mice, we examined the effects on plasma lipid levels, triglyceride (TG) elevation after oral fat loading, and development of atherosclerosis in apoE KO mice fed a Western-type diet. Implitapide at a dosage of approximately 3.2 mg/kg/day significantly reduced both total cholesterol and TG levels during the 8-week treatment period. In addition, implitapide significantly inhibited the increase in plasma TG levels after oral olive oil loading tests conducted after 4 weeks of treatment. After the treatment, implitapide significantly suppressed the atherosclerotic lesion area by 83% compared with a control group. These results provide direct evidence that the antiatherosclerotic effects of implitapide in apoE KO mice are associated with the inhibition of postprandial TG elevation, in addition to the reduction of both plasma total cholesterol and TG levels.

Possible involvement of enhanced intestinal microsomal triglyceride transfer protein (MTP) gene expression in acceleration of lipid absorption by a western-type diet in apolipoprotein E knockout mice.

Evidence has been accumulating that triglyceride (TG)-rich lipoproteins are atherogenic. Microsomal TG transfer protein (MTP) is essential for the synthesis of both chylomicron in the intestine and very low density lipoprotein in the liver. To investigate whether a western-type diet, a so-called atherogenic diet, alters intestinal lipid absorption via change in intestinal MTP expression, the effects of two different diet regimes in apolipoprotein-E knockout (apoE KO) mice were examined. Male apoE KO mice aged 6 weeks were fed a western-type diet or a chow diet for 5 weeks. Then, measurement of plasma TG levels after oral fat-loading and analysis of jejunal MTP gene expression were performed. Both the maximum level and the 0-8 h area under the curve (AUC) of the increase in TG levels in the western-type diet-fed mice were almost three times greater than those in the chow diet-fed mice. MTP gene expression, determined by reverse transcriptase-polymerase chain reaction (RT-PCR), was obviously enhanced in the western-type diet-fed mice compared to the chow diet-fed mice. These results suggest that the enhancement of intestinal MTP gene expression is involved in the accelerated lipid absorption in the western-type diet-fed mice.

A gastrointestinal lipase inhibitor reduces progression of atherosclerosis in mice fed a western-type diet.

To investigate whether gastrointestinal lipase inhibition reduces the progression of a western-type diet induced atherosclerosis, male apolipoprotein-E knockout (apoE KO) mice were administered orlistat ((S)-1-[[(S, 2S, 3S)-3-hexyl-4-oxo-2-oxetanyl] methyl]dodecyl-(S)-2-formamido-4-methylvalerate) mixed with a western-type diet for 8 weeks. Orlistat significantly reduced plasma triglyceride levels, but not total cholesterol levels, at 4 and 8 weeks of treatment. Increase in plasma triglyceride levels after oral olive oil loading in the mice fed a western-type diet was significantly suppressed in the orlistat treated group at 4 weeks of treatment. After 8 weeks treatment, atherosclerotic lesion area in the aorta of the orlistat treated group was significantly smaller than that of the control group. These results suggest that gastrointestinal lipase inhibition reduces the progression of atherosclerosis through a triglyceride-lowering effect, via inhibition of fat absorption.