Hyperlipidemias: Tsutsumi K

Tsutsumi K. · Research and Development, Otsuka Pharmaceutical Factory, Inc., Naruto, Tokushima 772-8601, Japan. · Curr Vasc Pharmacol. · Pubmed #15320848 No free full text.

Abstract: Lipoprotein lipase (LPL) is a rate-limiting enzyme that hydrolyzes circulating triglyceride-rich lipoprotein such as very low density lipoproteins and chylomicrons. A decrease in LPL activity is associated with an increase in plasma triglycerides (TG) and decrease in high density lipoprotein (HDL) cholesterol. The increase in plasma TG and decrease in HDL cholesterol are risk factors of coronary heart disease. However, whether LPL directly or indirectly promotes or protects against atherosclerosis remains unclear as two contrary views exist in this regard: one where LPL promotes atherosclerosis and one where LPL protects against atherosclerosis. Many studies have been carried out to investigate whether LPL is an anti-atherogenic or atherogenic enzyme by using animals with genetic defects or with an excess of this enzyme. From these studies, much evidence has been acquired showing that LPL is an anti-atherogenic enzyme. We hypothesized that elevating LPL activity would cause a reduction of plasma TG and increase in HDL cholesterol, resulting in protection against the development of atherosclerosis. To test this hypothesis, we studied the effects of the LPL activator NO-1886 in animals. NO-1886 has been shown to increase LPL mRNA in adipose tissue and myocardium, and increase LPL activity in adipose tissue, myocardium and skeletal muscle, resulting in an elevation of postheparin plasma LPL activity and LPL mass in rats. NO-1886 has also been shown to decrease plasma TG levels accompanied by a concomitant rise in HDL cholesterol. Long-term administration of NO-1886 to rats and rabbits with experimental atherosclerosis inhibited the development of atherosclerotic lesions in coronary arteries and aortae. The results of multiple regression analysis in these studies suggest that the increase in plasma HDL cholesterol and the decrease in TG protect against atherosclerosis. We have determined in our studies that the atherogenic lipid profile is changed to an anti-atherogenic lipid profile by increasing LPL activity, resulting in protection against the development of atherosclerosis. Therefore, we believe that high activity of LPL is anti-atherogenic, whereas a low activity of LPL is atherogenic.

Yin W, Tsutsumi K. · Department of Biochemistry and Molecular Biology, Medical School, Nanhua University, Hengyang 421001, China. · Cardiovasc Drug Rev. · Pubmed #12847564 No free full text.

Abstract: Lipoprotein lipase (LPL) is a rate-limiting enzyme that hydrolyzes circulating triglyceride-rich lipoproteins such as very low-density lipoproteins and chylomicrons. A decrease in LPL activity is associated with an increase in plasma triglycerides (TG) and a decrease in plasma high-density lipoprotein cholesterol (HDL-C). The increase in plasma TG and decrease in plasma HDL-C are risk factors for cardiovascular disease. Tsutsumi et al. hypothesized that elevating LPL activity would cause a reduction of plasma TG and an increase in plasma HDL-C, resulting in protection against the development of atherosclerosis. To test this hypothesis, Otsuka Pharmaceutical Factory, Inc. synthesized the LPL activator NO-1886. NO-1886 increased LPL mRNA and LPL activity in adipose tissue, myocardium and skeletal muscle, resulting in an elevation of postheparin plasma LPL activity and LPL mass in rats. NO-1886 also decreased plasma TG concentration and caused a concomitant rise in plasma HDL-C. Long-term administration of NO-1886 to rats and rabbits with experimental atherosclerosis inhibited the development of atherosclerotic lesions in coronary arteries and aortas. Multiple regression analysis suggested that the increase in plasma HDL-C and the decrease in plasma TG protect from atherosclerosis. The atherogenic lipid profile is changed to an antiatherogenic profile by increasing LPL activity, resulting in protection from atherosclerosis. Therefore, the LPL activator NO-1886 or other possible LPL activating agents are potentially beneficial for the treatment of hypertriglyceridemia, hypo-HDL cholesterolemia, and protection from atherosclerosis.

Niho N, Mutoh M, Takahashi M, Tsutsumi K, Sugimura T, Wakabayashi K. · Cancer Prevention Basic Research Project, National Cancer Center Research Institute, 5-1-1 Tsukiji, Chuo-ku, Tokyo 104-0045, Japan. · Proc Natl Acad Sci U S A. · Pubmed #15710887 links to  free full text

Abstract: We have previously reported a hyperlipidemic state in two strains of Apc-deficient mice, Min and Apc(1309), associated with low expression levels of lipoprotein lipase (LPL) in the liver and small intestine, and enforced induction of LPL mRNA by peroxisome proliferator-activated receptor (PPAR)alpha and PPARgamma agonists clearly suppressed hyperlipidemia and intestinal polyp formation in these mice. Meanwhile, a compound, NO-1886, has been shown to increase LPL mRNA and protein levels but not to possess PPARalpha and PPARgamma agonistic activity. In this study, therefore, the effects of NO-1886 on hyperlipidemia and intestinal polyp formation were investigated in Min mice. Administration of 400 and 800 ppm NO-1886 in the diet for 13 weeks from 7 weeks of age caused a reduction of serum triglycerides to 39% and 31% of the untreated value, respectively, and the values for very low-density lipoprotein cholesterol, low-density lipoprotein cholesterol, and high-density lipoprotein cholesterol were improved almost to the wild-type level with a corresponding elevation of the LPL mRNA. Moreover, total numbers of intestinal polyps in the groups receiving NO-1886 at 400 and 800 ppm were decreased to 48% and 42% of the control value, respectively. We also found that NO-1886 suppressed cyclooxygenase-2 transcriptional promoter activity in a reporter gene assay and reduced cyclooxygenase-2 mRNA levels in the small intestine of Min mice. These results indicate that suppression of serum lipid levels by increasing LPL activity may contribute to a reduction of intestinal polyp formation with Apc-deficiency, and NO-1886 and its derivatives could be useful as chemopreventive agents for colon cancer.

Tsutsumi K, Inoue Y, Murase T. · Nutrition Research Institute, Otsuka Pharmaceutical Factory, Inc., Tokushima, Japan. · Arzneimittelforschung. · Pubmed #10719613 No free full text.

Abstract: The novel compound NO-1886 ([4-(4-bromo-2-cyano-phenylcarbamoyl)-benzyl]-phosphonic acid diethyl ester, CAS 133208-93-2) is a lipoprotein lipase (LPL) activator, and long term administration of NO-1886 protects against the development of experimental atherosclerosis in rats and rabbits. In the present experiments, the effects of this compound were examined in Watanabe heritable hyperlipidaemic (WHHL) rabbits, an animal model for familial hypercholesterolemia lacking low density lipoprotein (LDL) receptors. NO-1886 increased postheparin plasma LPL activity, resulting in a reduction of plasma triglycerides with concomitant elevation of HDL cholesterol in heterozygous WHHL rabbits. However, the compound did not cause any changes in plasma lipids and postheparin plasma LPL activity in homozygous WHHL rabbits. The different responses suggest that the effects of NO-1886 may be either mediated by LDL receptors, or that persistent exposure to extreme hypercholesterolemia might affect the cellular response to this particular compound in homozygous WHHL rabbits.

Tsutsumi K, Inoue Y, Yoshida C. · Nutrition Research Institute, Otsuka Pharmaceutical Factory, Inc., Tokushima, Japan. · Biol Pharm Bull. · Pubmed #9989659 No free full text.

Abstract: Diabetic cataracts are thought to be caused by hyperglycemia associated with disturbed glucose metabolism. Diabetes mellitus often involves abnormal lipid metabolism in addition to abnormal glucose metabolism. To date, however, very few studies have counted hyperlipidemia as a risk factor for diabetic cataracts. The present study was undertaken to determine whether this abnormal lipid metabolism is a risk factor for diabetic cataracts in rats. Cataracts were caused by streptozotocin (STZ) administration in the ordinary diet or cholesterol rich diet fed rats. When rats with STZ (65 mg/kg)-induced diabetes mellitus were fed an ordinary diet, cataracts became evident at 9 weeks in 26.7% of animals, and increased to an incidence of 53.3% after 10 weeks of STZ treatment. However, in rats with STZ-induced diabetes mellitus that were fed a cholesterol rich diet to induce severe hyperlipidemia and low high density lipoprotein (HDL) cholesterol, cataracts were observed one week earlier, after 8 weeks of treatment, in 40.0% of animals, with an increase to a 53.3% incidence and an 86.7% incidence after 9 and 10 weeks of STZ treatment, respectively. Plasma glucose levels did not differ between the groups. These results suggest that hyperlipidemia and low HDL cholesterol are associated with an earlier onset and an elevated incidence of diabetic cataracts. We then investigated the relationship between plasma lipids and cataracts by STZ (45-85 mg/kg) administration. The results showed that the onset of cataracts correlated positively with plasma total cholesterol, triglyceride, non-HDL cholesterol and glucose levels, and negatively with HDL cholesterol levels. The results of this study suggest that hyperlipidemia and low HDL cholesterol levels may be risk factors for the onset of diabetic cataracts and that diabetic cataracts may be accelerated by hyperlipidemia and low HDL cholesterol in rats.