Lipid lowering therapy in type 2 diabetes

Anti-Obesity Effects of Aqueous Extracts of Sunbanghwalmyung-Eum in High-Fat- and High-Cholesterol-Diet-Induced Obese C57BL/6J Mice

Sunbanghwalmyung-eum (SBH) is a traditional herbal medicine that exhibits various pharmacological properties, such as antioxidant, anti-inflammatory, and anticancer activities. In this study, we investigated the systemic anti-obesity effects of an aqueous extract of SBH in the liver, adipose, and muscle tissue from high-fat and high-cholesterol diet (HFHCD)-induced obese C57BL/6J mice. After 6 weeks of an HFHCD, the mice were continuously fed HFHC with oral administration of SBH (100 mg/kg/day), Sim (simvastatin, 5 mg/kg/day, positive control), or water (HFHC only) for another 6 weeks. Our results showed that SBH attenuated the HFHCD-induced body weight gain and fat accumulation in the liver, and improved plasma lipid levels, such as those of triglycerides (TGs), blood total cholesterol (TC), and low-density lipoprotein (LDL-c). SBH and Sim inhibited the inflammation accompanied by obesity via decreasing inflammatory cytokine interleukin (IL)-1β, tumor necrosis factor α (TNFα), and monocyte chemoattractant protein 1 (MCP1). Moreover, SBH downregulated the expression of protein levels of adipogenic-related factors, including peroxisome proliferator-activated receptor γ (PPARγ) and CCAAT/enhancer-binding protein α (C/EBPα), in the liver, adipose, and muscle tissue. The SBH and Sim treatment also significantly upregulated the phosphorylation of AMP-activated protein kinase α (AMPKα) in the liver and hormone-sensitive lipase (HSL) in the adipose tissue. Overall, the effects of SBH on HFHCD-induced obesity were similar to or more potent than those of simvastatin. These results indicated that SBH has great potential as a therapeutic herbal medicine for obesity.

Efficacy and adverse reaction to different doses of atorvastatin in the treatment of type II diabetes mellitus

Background: Type II diabetes mellitus (T2DM), a persistent metabolic disorder, is primarily characterized by insulin resistance, relative insulin deficiency and dyslipidemia. Here, we aimed to investigate whether different doses of atorvastatin (ATV) affect rats with T2DM. A total of 110 Sprague–Dawley rats were successfully established as T2DM models. Methods: First, the total cholesterol, triglyceride (TG), high-/low-/very-low-density lipoprotein cholesterol (HDL-c/LDL-c/VLDL-c), alanine transaminase (ALT), aspartate aminotransferase (AST), blood urea nitrogen (BUN), creatinine (Cr), apolipoprotein Al (ApoA1) and apolipoprotein B (ApoB) levels in rat serum were analyzed. In addition, cholesteryl ester transfer protein (CETP) and retinol-binding protein 4 (RBP4) were also measured. Then, the incidence of adverse reactions was noted. Finally, the pathological study of liver and pancreatic tissues was performed. Results: Rats administered ATV at the doses of 40 and 80 mg/(kg·day) showed down-regulated TG, LDL-c, ApoB, CETP and RBP4 levels yet up-regulated HDL-c and ApoAl levels. Rats administered ATV at a dose of 80 mg/(kg·day) exhibited a higher incidence of adverse reactions and higher ALT and AST levels but lower BUN and Cr levels, which might affect liver and kidney function. Rats administered ATV at the doses of 40 and 80 mg/(kg·day) demonstrated significantly improved liver injury and pancreatic injury induced by T2DM. Conclusion: These data revealed that ATV could improve the lipid metabolism in T2DM rats and 40 mg/(kg·day) may serve as the optimal dose for the reduction of lipid levels and the incidence of adverse effects.

Anti-obesity effects of yellow catfish protein hydrolysate on mice fed a 45% kcal high-fat diet

Obesity contributes to the etiologies of a variety of comorbid conditions, such as type 2 diabetes, hypertension and cardiovascular disease. In the present study, the anti-obesity effects of yellow catfish protein hydrolysate (YPh) were observed in mice fed a 45% kcal high-fat diet (HFD) compared with those of mice treated with simvastatin. The HFD-fed control mice exhibited noticeable increase in body weight, and whole-body and abdominal fat densities, periovarian and abdominal wall-deposited fat pad weight, as well as in the levels of triglycerides (TG), blood total cholesterol (TC), low-density lipoprotein, alanine aminotransferase, aspartate aminotransferase, creatinine, blood urea nitrogen, and in the fecal TG and TC contents. However, they exhibited a decrease in serum high-density lipoprotein levels. In addition, an increase was detected in periovarian and dorsal abdominally deposited fat pad thickness, adipocyte hypertrophy, the number of steatohepatitis regions, hepatocyte hypertrophy and lipid droplet deposition-related renal tubular vacuolation degenerative lesions, along with increased hepatic lipid peroxidation and a deteriorated endogenous antioxidant defense system (glutathione, catalase and superoxide dismutase). However, all the above-mentioned obesity-related complications were dose-dependently and significantly inhibited after 84 days of thye consecutive oral administration of 125, 250 and 500 mg/kg YPh. In addition, YPh dose-dependently depleted the liver endogenous antioxidant defense system and inhibited hepatic lipid peroxidation. Overall, the effects of 250 mg/kg YPh on HFD-induced obesity and related complications were similar or more potent than those of 10 mg/kg simvastatin. These results indicate that YPh is a promising new potent medicinal ingredient for possible use in the treatment of obesity and related complications.

Evidence for Feedback Regulation Following Cholesterol Lowering Therapy in a Prostate Cancer Xenograft Model

BACKGROUND

Epidemiologic data suggest cholesterol-lowering drugs may prevent the progression of prostate cancer, but not the incidence of the disease. However, the association of combination therapy in cholesterol reduction on prostate or any cancer is unclear. In this study, we compared the effects of the cholesterol lowering drugs simvastatin and ezetimibe alone or in combination on the growth of LAPC-4 prostate cancer in vivo xenografts.

METHODS

Proliferation assays were conducted by MTS solution and assessed by Student's t-test. 90 male nude mice were placed on a high-cholesterol Western-diet for 7 days then injected subcutaneously with 1 × 10⁵ LAPC-4 cells. Two weeks post-injection, mice were randomized to control, 11 mg/kg/day simvastatin, 30 mg/kg ezetimibe, or the combination and sacrificed 42 days post-randomization. We used a generalized linear model with the predictor variables of treatment, time, and treatment by time (i.e., interaction term) with tumor volume as the outcome variable. Total serum and tumor cholesterol were measured. Tumoral RNA was extracted and cDNA synthesized from 1 ug of total RNA for quantitative real-time PCR.

RESULTS

Simvastatin directly reduced in vitro prostate cell proliferation in a dose-dependent, cell line-specific manner, but ezetimibe had no effect. In vivo, low continuous dosing of ezetimibe, delivered by food, or simvastatin, delivered via an osmotic pump had no effect on tumor growth compared to control mice. In contrast, dual treatment of simvastatin and ezetimibe accelerated tumor growth. Ezetimibe significantly lowered serum cholesterol by 15%, while simvastatin had no effect. Ezetimibe treatment resulted in higher tumor cholesterol. A sixfold induction of low density lipoprotein receptor mRNA was observed in ezetimibe and the combination with simvastatin versus control tumors.

CONCLUSIONS

Systemic cholesterol lowering by ezetimibe did not slow tumor growth, nor did the cholesterol independent effects of simvastatin and the combined treatment increased tumor growth. Despite lower serum cholesterol, tumors from ezetimibe treated mice had higher levels of cholesterol. This study suggests that induction of low density lipoprotein receptor is a possible mechanism of resistance that prostate tumors use to counteract the therapeutic effects of lowering serum cholesterol. Prostate 77:446-457, 2017. © 2016 Wiley Periodicals, Inc.

Fermentation of Green Tea with 2% Aquilariae lignum Increases the Anti-Diabetic Activity of Green Tea Aqueous Extracts in the High Fat-Fed Mouse

Anti-diabetic effects on the metabolomic differences between green tea (GT) and Aquilariae lignum-fermented green tea (fGT) were investigated in the high fat-fed mouse. To prove the differences, hypoglycemic (blood glucose, insulin and glycated hemoglobin levels, pancreas weights and histopathological-immunohistochemistrical analysis of pancreas–insulin/glucagon cells), hepato- and nephron-protective (the changes in liver and kidney weight, histopathology of liver and kidney, serum aminotransferases (AST and ALT) levels, blood urea nitrogen, and serum creatinine levels), and hypolipidemic (the changes of serum total cholesterol, triglyceride, low- and high-density lipoprotein levels with fecal TC and TG contents) effects were evaluated. In addition, liver lipid peroxidation, the glutathione contents, and catalase and superoxide dismutase activities were measured according to the hepatic glucose-regulating enzyme activities of glucokinase (GK), glucose-6-phosphatase (G6pase) and phosphoenolpyruvate carboxykinase (PEPCK) for action mechanisms. As a result, fGT showed a stronger hypoglycemic, hepato- and nephron-protective, hypolipidemic, and anti-oxidant effect than GT in high fat-fed mice. In addition, fGT-treated mice exerted more favorable inhibitory activities against GK, G6pase, PERCK activities as compared to GT-treated mice. Taken together, fGT fermented with Aquilariae lignum, 1:49 (2%; g/g) has a stronger effect compared with GT. Therefore, fGT has the potential to increase bioactivity against type 2 diabetics.

ABCG5 and ABCG8 gene polymorphisms in type 2 diabetes mellitus in the Turkish population

OBJECTIVE

The aim of the present study was to investigate the relationship between ABCG5 and ABCG8 gene polymorphisms and plasma lipid concentrations in Turkish patients with type 2 diabetes mellitus.

METHODS

Included in this study were 80 patients with type 2 diabetes and 73 healthy controls. Two selected single nucleotide polymorphisms in ABC transporter genes, ABCG5 (rs6720173) and ABCG8 (rs4148211), were genotyped by using the polymerase chain reaction-restriction fragment length polymorphism technique.

RESULTS

The rate of having the ABCG8 AA genotype (p=0.001) was significantly higher in the patients than in the control subjects. Correspondingly, the rates of having the AG genotype (p=0.001) and the G allele (p=0.001) were significantly lower in the patients than in controls. Upon comparing the groups regarding ABCG5, the frequencies of occurrence of the GG genotype (p=0.031) and G allele (p=0.003) were considerably higher in patients than in control subjects. In the patients, the rates of having the CC genotype (p=0.003) and the C allele (p=0.031) were also significantly lower than those in control subjects. There was no significant difference between G5 and G8 polymorphism and lipid levels in the study groups. The ABCG8 AA genotype carriers had higher triglyceride (p=0.045) and very low-density-cholesterol (p=0.045) levels than the ABCG8 GG genotype carriers in all study populations.

CONCLUSIONS

These results indicate that the AA genotype for ABCG8 and the GG genotype and G allele for ABCG5 are risk factors for diabetes. This study reveals the first data concerning the ABCG5 and ABCG8 gene polymorphisms in Turkish patients with diabetes.

The role of Multidrug Resistance-1 (MDR1) variants in response to atorvastatin among Jordanians

The MDR1 gene encodes for P-glycoprotein (P-gp), which is an efflux transporter at the cell membrane. The P-gp has wide substrate specificity for multiple medications including the lipid lowering drug, atorvastatin. In this study, we investigated the possible association between three common MDR1 gene polymorphisms (G2677T, C3435T, and C1236T), and the lipid lowering effect of atorvastatin among Jordanians. Lipid and lipoproteins were measured in blood samples collected from patients (n = 201) at baseline and during atorvastatin treatment. MDR1 polymorphisms were genotyped using polymerase chain reaction-restriction fragment length polymorphism. Both the TT genotype of G2677T and the TT genotype of the C3435T polymorphisms were associated with lower levels of low-density lipoproteins after atorvastatin treatment. However, the effects of atorvastatin on the levels of total cholesterol, triglycerides, and high-density lipoprotein, were not correlated with any of the genotypes in both polymorphisms. Finally, the C1236T polymorphism was not associated with the lipid lowering effect of atorvastatin. In conclusion, the MDR1 gene polymorphisms G2677T, and C3435T, but not C1236T were associated with the lipid lowering effect of atorvastatin among Jordanians.

Does combination therapy with statins and fibrates prevent cardiovascular disease in diabetic patients with atherogenic mixed dyslipidemia?

Type 2 diabetes mellitus (T2DM) is associated with the development and progression of cardiovascular disease (CVD). Statins have an established efficacy in the management of dyslipidemia primarily by decreasing the levels of low-density lipoprotein cholesterol and thus decreasing CVD risk. They also have a favorable safety profile. Despite the statin-mediated benefit of CVD risk reduction a residual CVD risk remains, especially in T2DM patients with high triglyceride (TG) and low high-density lipoprotein cholesterol (HDL-C) values. Fibrates decrease TG levels, increase HDL-C concentrations, and improve many other atherosclerosis-related variables. Fibrate/statin co-administration improves the overall lipoprotein profile in patients with mixed dyslipidemia and may reduce the residual CVD risk during statin therapy. However, limited data exists regarding the effects of statin/fibrate combination on CVD outcomes in patients with T2DM. In the Action to Control Cardiovascular Risk in Diabetes (ACCORD) study the statin/fibrate combination did not significantly reduce the rate of CVD events compared with simvastatin/placebo in patients with T2DM. However, it did show a possible benefit in a pre-specified analysis in the subgroup of patients with high TG and low HDL-C levels. Furthermore, in the ACCORD study the simvastatin/fenofibrate combination significantly reduced the rate of progression of retinopathy compared with statin/placebo administration in patients with T2DM. The present review presents the available data regarding the effects of statin/fibrate combination in patients with T2DM and atherogenic mixed dyslipidemia.

Effect of insulin analog initiation therapy on LDL/HDL subfraction profile and HDL associated enzymes in type 2 diabetic patients

BACKGROUND

Insulin treatment can lead to good glycemic control and result in improvement of lipid parameters in type 2 diabetic patients. This study was designed to evaluate the effect of insulin analog initiation therapy on low-density lipoprotein (LDL)/ high-density lipoprotein (HDL) sub-fractions and HDL associated enzymes in type 2 diabetic patients during early phase.

METHODS

Twenty four type 2 diabetic patients with glycosylated hemoglobin (HbA1c) levels above 10% despite ongoing combination therapy with sulphonylurea and metformin were selected. Former treatment regimen was continued for the first day followed by substitution of sulphonylurea therapy with different insulin analogs (0.4 U/kg/day) plus metformin. Glycemic profiles were determined over 72 hours by continuous glucose monitoring system (CGMS) and blood samples were obtained from all patients at 24 and 72 hours. Plasma levels of cholesteryl ester transfer protein (CETP), lecithin-cholesterol acyltransferase (LCAT), apolipoprotein B (apoB) and apolipoprotein A-1 (apoA-I) were determined by enzyme-linked immunosorbent assay (ELISA). Measurement of CETP and LCAT activity was performed via fluorometric analysis. Paraoxonase (PON1) enzyme activity was assessed from the rate of enzymatic hydrolysis of phenyl acetate to phenol formation. LDL and HDL subfraction analysis was done by continuous disc polyacrylamide gel electrophoresis.

RESULTS

Mean blood glucose, total cholesterol (TC), triglyceride (TG) and very low-density lipoprotein cholesterol (VLDL-C) levels were significantly decreased while HDL-C levels were significantly increased after insulin treatment. Although LDL-C levels were not significantly different before and after insulin initiation therapy a significant increase in LDL-1 subgroup and a significant reduction in atherogenic LDL-3 and LDL-4 subgroups were observed. Insulin analog initiation therapy caused a significant increase in HDL-large, HDL- intermediate and a significant reduction in HDL-small subfractions. CETP protein level and activity was significantly increased while apoB levels were significantly decreased following insulin analog initiation therapy. No significant difference was found in LCAT mass, LCAT activity, apoA-I and PON-1 arylesterase levels following insulin initiation therapy.

CONCLUSION

These findings indicate that insulin analog initiation therapy activates lipid metabolism via up-regulating CETP and shows anti-atherogenic effects by increasing HDL-large and decreasing LDL-3 and LDL-4 subfractions in a short time period.