[Effects of drynaria total flavonoid on osteogenic differentiation of bone marrow mesenchymal stem cells at different glucose concentrations: experiment with rats].

OBJECTIVE: To study the effects of drynaria total flavonoid on osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs) at different glucose concentrations. METHODS: BMSCs of SD rats were isolated, cultivated in vitro, and divided into 6 groups to be induced to differentiate into osteoblasts under different conditions: (1) low glucose control group, (2) high glucose control group, (3) low glucose classical induction group (sodium glycerophosphate+vitamin C+dexamethasone), (4) high glucose classical induction group (sodium glycerophosphate+vitamin C+dexamethasone), (5) low glucose+drynaria total flavonoid group, and (6) high glucose with drynaria total flavonoid group. Alkaline phosphate (ALP) test kit was used to examine the level of ALP. The ALP staining positive rate was examined with modified calcium cobalt method. Alizarin red staining was adopted to observe the number of calcium nodes. Immunohistochemistry was used to detect type I collagen level. Advanced glycosylation end products (AGEs) were tested by ELISA. RESULTS: The A value indicating the ALP activity, ALP staining positive rate, calcium node number, and type I collagen expression score of the low glucose+drynaria total flavonoid group were (0.439±0.024), 48.7%, (9.75±1.71) nodes/HP, and (2.21±0.07) respectively, all significantly higher than those of the sodium glycerophosphate+vitamin C+dexamethasone [(0.385±0.029), 35.0%, (6.25±0.96) nodes/HP, and (1.93±0.13) respectively, all P<0.05]. The A value, ALP staining positive rate, calcium node number, and type I collagen expression score of the high glucose with drynaria total flavonoid group were (0.352±0.022), 25.3%, (4.50±1.29)/HP, and (1.70±0.03) respectively, all significantly higher than those of the sodium glycerophosphate+vitamin C+dexamethasone [(0.139±0.013), 22.7%, (3.25±1.50)/HP, and (1.28±0.27) respectively, all P<0.05]. The AGE expression levels of the high glucose classical induction group and high glucose+drynaria total flavonoid group were both significantly higher than those of the low glucose classical induction group and low glucose+drynaria total flavonoid group (both P<0.05). There were no significant differences in the AGE level among the low glucose control, low glucose classical induction, and low glucose+drynaria total flavonoid groups (all P<0.05); and among the high glucose control, high glucose classical induction, and high glucose+drynaria total flavonoid groups (all P<0.05). However, the AGE levels of the high glucose groups were all significantly higher than those of the corresponding low glucose groups (all P<0.05). Glucose increased the AGE levels dose- and time-dependently. The concentrations of AGEs were significantly negatively correlated with the expression of type I collagen (r=-0.410, P<0.05). CONCLUSIONS: Drynaria total flavonoid promotes the osteogenic differentiation of BMSCs and relieves the inhibitory effect of osteogenic differentiation by glucose at high concentration. Thus drynaria total flavonoid may provide a potential therapy for diabetic osteoporosis.

Polymorphism of human leptin receptor gene is associated with type 2 diabetic patients complicated with non-alcoholic fatty liver disease in China.

BACKGROUND AND AIM: To investigate the relationship between human leptin receptor (LEPR) gene G3057A polymorphism and type 2 diabetes mellitus (T2DM) patients complicated with or without non-alcoholic fatty liver disease (NAFLD). METHODS: Two hundred and sixteen cases of newly diagnosed T2DM patients (104 cases complicated with NAFLD) and 108 cases of normal glucose tolerances (NGT) were recruited. Hemi-nested polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) and PCR-direct sequence analysis were conducted to detect the polymorphism of LEPR G3057A variation. Plasma leptin levels were measured by enzyme-linked immunosorbent assay kit. Plasma lipid and glucose metabolic parameters were measured routinely. Liver ultrasound was carried out for all subjects. RESULTS: T2DM patients complicated with NAFLD had higher plasma insulin, leptin, triglycerides (TG) and low-density lipoprotein cholesterol (LDL-C) levels than those without NAFLD and NGT subjects. The variant frequency at nucleotide 3057 G-->A transversion was 76.0% in type 2 diabetic patients complicated with NAFLD, which was also significantly higher than those without NAFLD (62.1%) and NGT cases (53.2%). There was also significant difference in genotype distribution between the three groups (chi(2) = 14.63, P < 0.01). CONCLUSION: The polymorphism of LEPR gene 3057 probably contributes to the onset of NAFLD by regulating lipid metabolism and affecting insulin sensitivity.

Treatment with PPARδ agonist alleviates non-alcoholic fatty liver disease by modulating glucose and fatty acid metabolic enzymes in a rat model.

Non-alcoholic fatty liver disease (NAFLD) is an increasingly common condition which is associated with certain features of metabolic syndrome and insulin resistance. Peroxisome proliferator­activated receptor (PPAR)δ is an important regulator of energy metabolism and insulin resistance in diabetes. However, the function of PPARδ in NAFLD has not yet been fully elucidated. In the present study, in order to explore the function of PPARδ in NAFLD, we created a rat model of NALFD induced by a high-fat diet (HFD) and treated the rats with GW501516, a PPARδ agonist. We found that the lipid levels decreased, and hepatocellular ballooning and inflammatory cell infiltration were also significantly decreased following treatment of the rats with GW501516 compared to the untreated rats. Treatment with GW501516 also significantly decreased the homeostasis model assessment of insulin resistance (HOMA-IR) index, as well as the low­density lipoprotein (LDL) levels. In addition, treatment with GW501516 increased the levels of insulin­like growth factor­1 (IGF-1) and high­density lipoprotein (HDL) compared to the HFD group. Furthermore, the elevated levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), gamma­glutamyl transpeptidase (GGT) and alkaline phosphatase (ALP) in the HFD group were all restored to the normal control levels following treatment with GW501516. RT­qPCR and immunohistochemical staining revealed that the expression levels of sterol regulatory element binding protein­1c (SREBP­1c) and glucose transporter 2 (GLUT­2) were both restored to normal control levels following treatment with GW501516. Also, the levels of enzymes related to lipid metabolism were increased following treatment with GW501516. In conclusion, our findings demonstrate that treatment with GW501516 alleviates NAFLD by modulating glucose and fatty acid metabolism.

High prevalence of coronary heart disease in type 2 diabetic patients with non-alcoholic fatty liver disease.

BACKGROUND AND AIMS: Nonalcoholic fatty liver disease (NAFLD) is closely associated with insulin resistance and metabolic syndrome. Prevalence of NAFLD increases greatly in patients with type 2 diabetes mellitus (T2DM), and it may also increase cardiovascular disease mortality and morbidity. The aim of our study was to investigate the prevalence of NAFLD in T2DM population and to compare the prevalence of coronary heart disease (CHD) and its risk factors between diabetic patients with and without NAFLD in a Chinese population. METHODS: A cross-sectional survey was conducted among 560 cases of in-patient T2DM patients from January 2002 to January 2009 in southern China. Patients were divided into two groups (NAFLD and non-NAFLD) and underwent clinical examination, anthropometry, laboratory tests and routine liver ultrasonography. RESULTS: Prevalence of NAFLD was 75.18% (421 cases) among all participants, and 285 cases (67.70%) had normal liver function and no symptoms. NAFLD group had higher body mass index (BMI), waist/hip circumference ratio (WHR), alanine aminotransferase (ALT), triglycerides (TG) and low-density lipoprotein cholesterol (LDL-C) levels than those without NAFLD (p<0.01). Moreover, the prevalence of CHD was also higher in the NAFLD group (p<0.01), especially in those male patients with elevated plasma ALT. CONCLUSIONS: NAFLD is a common condition among T2DM patients. Its occurrence may be related to sex, age, abdominal obesity, dyslipidemia metabolism, etc. and it is associated with a higher prevalence of CHD. Plasma ALT levels may act as a marker.