Oxidized Low-Density Lipoprotein Decreases the Survival of Bone Marrow Stem Cells via Inhibition of Bcl-2 Expression.

Therapy with mesenchymal stem cells (MSCs) is considered an attractive strategy for the repair or regeneration of damaged tissues. However, low survival of MSCs limits their applications clinically. Oxidized low-density lipoprotein (ox-LDL) is significantly increased in patients with hyperlipidemia and decreases the survival of MSCs. Bcl-2 is critically involved in important cell functions, including cell membrane integrity and cell survival. The present study was designed to test the hypothesis that ox-LDL attenuates the survival of MSCs through suppression of Bcl-2 expression. Bone marrow MSCs from C57BL/6 mice were cultured with ox-LDL at different concentrations (0-140 µg/mL) for 24 h with native LDL as control. Ox-LDL treatment substantially decreased the survival of MSCs dose-dependently and enhanced the release of intracellular lactate dehydrogenase (LDH) in association with a significant decrease in Bcl-2 protein level without change in BAX protein expression in MSCs. Bcl-2 overexpression effectively protected MSCs against ox-LDL-induced damages with preserved cell numbers without significant increase in LDH release. Treatment with N-acetylcysteine (NAC) (1 mM) effectively preserved Bcl-2 protein expression in MSCs and significantly attenuated ox-LDL-induced decrease of cell number and increase in the release of intracellular LDH. These data indicated that ox-LDL treatment resulted in a significant damage of cell membrane and dramatically decreased the survival of MSCs dose-dependently through inhibition of Bcl-2 expression. NAC treatment significantly protected MSCs against the damage of cell membrane by ox-LDL and promoted the survival of MSCs in association with preserved Bcl-2 expression.

The source of circulating selenoprotein S and its association with type 2 diabetes mellitus and atherosclerosis: a preliminary study.

BACKGROUND: Selenoprotein S (SelS) is a transmembrane protein that is expressed in the liver, skeletal muscle, adipose tissue, pancreatic islets, kidney, and blood vessels. In addition to its transmembrane localization, SelS is also secreted from hepatoma HepG2 cells (but not L6 skeletal muscle cells, 3T3-L1 adipocytes, Min6 pancreatic ß cells and human embryonic kidney 293 cells) and has been detected in the serum of some human subjects, with a detection rate of 31.1 %. These findings prove that serum SelS is secreted by hepatocytes. However, whether vascularly expressed SelS can be secreted has not been reported. Transmembrane SelS has been suggested to play different roles in the pathogenesis and progression of diabetes mellitus (DM) and atherosclerosis (AS), but the association of secreted SelS with DM and macroangiopathy remains unclear. RESEARCH DESIGN AND METHODS: Supernatants were collected from human umbilical vein endothelial cells (HUVECs), human aortic vascular smooth muscle cells (HA/VSMCs) and human hepatoma HepG2 cells that were untransfected or transfected with the indicated plasmid and concentrated for western blotting. Serum samples were collected from 158 human subjects with or without type 2 DM (T2DM) and/or AS. Serum SelS levels were measured using an enzyme-linked immunosorbent assay. RESULTS: Secreted SelS was only detected in the supernatants of hepatoma HepG2 cells. The SelS detection rate among the 158 human serum samples was 100 %, and the average SelS level was 64.81 ng/dl. The serum SelS level in the isolated DM subjects was lower than the level in the healthy control subjects (52.66 ± 20.53 vs 70.40 ± 21.38 ng/dl). The serum SelS levels in the DM complicated with SAS subjects (67.73 ± 21.41 ng/dl) and AS subjects (71.69 ± 27.00 ng/dl) were significantly increased compared with the serum SelS level in the isolated DM subjects. There was a positive interaction effect between T2DM and AS on the serum SelS level (P = 0.002). Spearman correlation analysis showed that the serum SelS level was negatively correlated with fasting plasma glucose. CONCLUSIONS: Vascular endothelial and vascular smooth muscle cells could not secrete SelS. Serum SelS was primarily secreted by hepatocytes. SelS was universally detected in human serum samples, and the serum SelS level was associated with T2DM and its macrovascular complications. Thus, regulating liver and serum SelS levels might become a new strategy for the prevention and treatment of DM and its macrovascular complications.

Associations among glycemic excursions, glycated hemoglobin and high-sensitivity C-reactive protein in patients with poorly controlled type 2 diabetes mellitus.

The aim of the present study was to explore the associations among glycemic excursions, glycated hemoglobin (HbA1c) and high-sensitivity C-reactive protein (hs-CRP) in patients with poorly controlled type 2 diabetes mellitus (T2DM) using a continuous glucose monitoring system (CGMS). Sixty-three patients with T2DM whose HbA1c levels were >7% wore a CGMS device for 72 h. According to their HbA1c levels, patients were divided into three groups as follows: Group A (HbA1c ≤9.32%), group B (9.32%< HbA1c ≤11.76%) and group C (HbA1c >11.76%). Patients were also divided into two groups according to the mean amplitude of glycemic excursions (MAGE) as follows: Low glycemic excursion group (MAGE, <3.9 mmol/l) and high glycemic excursion group (MAGE, ≥3.9 mmol/l). Clinical data and the hs-CRP levels in different groups were compared. No significant difference was observed in the MAGE among groups A, B and C (P>0.05). The level of hs-CRP was significantly higher in group C compared with that in groups A and B, and in group B compared with that in group A (P<0.05). Multivariate stepwise regression analysis indicated that HbA1c correlated with hs-CRP (P<0.05). MAGE and HbA1c were independent indices for the assessment of glycemic control. In addition, HbA1c had a considerable effect on the serum hs-CRP level.

Effects of selenoprotein S on oxidative injury in human endothelial cells.

BACKGROUND: Selenoprotein S (SelS) is an important endoplasmic reticulum and plasma membrane-located selenoprotein implicated in inflammatory responses and insulin resistance. However, the effects of SelS on endothelial cells (ECs) have not been reported. In the present study, the role of SelS in oxidative stress and the underlying mechanism were investigated in human ECs. METHODS: A SelS over-expression plasmid (pc-SelS) and a SelS-siRNA plasmid were transfected into human umbilical vein endothelial cells (American Type Culture Collection, USA). The cells were divided into four groups: control, SelS over-expression (transfected with pc-SelS), vector control, and SelS knockdown (transfected with siRNA-SelS). After treating the cells with H2O2, the effects of oxidative stress and the expression of caveolin-1 (Cav-1) and protein kinase Cα (PKCα) were investigated. RESULTS: Following treatment with H2O2, over-expression of SelS significantly increased cell viability and superoxide dismutase (SOD) activity, and decreased malondialdehyde (MDA) production and Cav-1 gene and protein expression. However, no effects on PKCα were observed. In contrast, knockdown of SelS significantly decreased cell viability, SOD activity, and PKCα gene and protein expression, and increased MDA production and Cav-1 gene and protein expression. CONCLUSIONS: SelS protects ECs from oxidative stress by inhibiting the expression of Cav-1 and PKCα.

[Relationship of amyloid-ß with vascular endothelial cell damage induced by diabetic serum].

OBJECTIVE: To explore the relationship of the impairment of human umbilical vein endothelial cell (HUVEC) with amyloid-ß. METHODS: HUVECs were cultured in the serum of patients with type 2 diabetes mellitus (DM) or serum of healthy control (HC), while fetal bovine serum (FBS) was used as a negative control. The proliferative activity of HUVEC were assessed by thiazolyl blue tetrazolium bromide (MTT) after 72 h. The supernatant concentrations of superoxide dismutase (SOD), maleic dialdehyde (MDA), nitric oxide (NO), amyloid-ß40 (Aß40) and Aß42 were measured after 0.5, 3 and 72 h respectively. RESULTS: Glycosylated hemoglobin values, fasting plasma glucose and fasting plasma Aß40 concentrations of diabetic patients were higher than those of healthy counterparts (P < 0.01). Proliferative activity of HUVECs in group DM were significantly lower than that of group HC. Both group and the time of intervention had crossover effects on the levels of MDA, SOD, NO and Aß40 ((163 ± 64), (207 ± 69), (286 ± 75) ng/L in group DM; (146 ± 76), (154 ± 75), (161 ± 72) ng/L in group HC after 0.5, 3 and 72 h, P < 0.05) and Aß42 ((48 ± 46), (54 ± 43), (79 ± 44) ng/L in group DM; (41 ± 12), (44 ± 16), (48 ± 12) ng/L in group HC after 0.5, 3 and 72 h, P < 0.05). With the elongating time of intervention, the levels of SOD and NO decreased significantly in group DM and reached the lowest after 72 h while increased significantly in groups HC and FBS and peaked after 72 h. The concentrations of MDA, Aß40 and Aß42 increased significantly in all three groups while the fastest and marked increments were found in group DM (P < 0.01). Pearson correlation analysis showed that SOD was negatively correlated with Aß40 (r = -0.482, P = 0.02) and Aß42 (r = -0.422, P = 0.02) while MDA positively with Aß40 (r = 0.418, P < 0.05) and Aß42 (r = 0.833, P < 0.05) after 72 h. CONCLUSION: Oxidative stress of vascular endothelial cells may be correlated with Aß40 and Aß42 in diabetes.

Effects of five-year intensive multifactorial intervention on the serum amyloid A and macroangiopathy in patients with short-duration type 2 diabetes mellitus.

BACKGROUND: A five-year follow-up study of intensive multifactorial intervention was undertaken to assess the changes of circulating serum amyloid A (SAA) levels and the incidence of atherosclerosis (AS) in patients with short-duration type 2 diabetes mellitus (T2DM) without macroangiopathy, and whether intensive multifactorial intervention could prevent or at least postpone the occurrence of macroangiopathy. METHODS: Among 150 patients with short-duration T2DM, 75 were assigned to receive conventional outpatient treatment (conventional group) and the others underwent intensive multifactorial integrated therapy targeting hyperglycemia, hypertension, dyslipidemia and received aspirin simultaneously (intensive group). RESULTS: Plasma SAA levels were higher in diabetic patients than those in healthy control subjects, and decreased obviously after intensive multifactorial intervention. The levels of SAA were positively correlated with body mass index (BMI), waist hip ratio (WHR), triglyceride (TG), high sensitive C-reactive protein (hs-CRP) and common carotid intima-media thickness (CC-IMT). The standard-reaching rates of glycemia, blood pressure and lipidemia were significantly higher in intensive group than those of conventional group. The incidence of macroangiopathy decreased by 58.96% in intensive group compared with conventional group. CONCLUSIONS: Intensive multifactorial intervention may significantly reduce the SAA levels and prevent the occurrence of AS in short-duration patients with T2DM. SAA might be one of the risk factors of T2DM combined with AS.

[Primary preventive effect of metformin upon atherosclerosis in patients with type 2 diabetes mellitus].

OBJECTIVE: To investigate the preventive action of metformin for atherosclerosis (AS) in patients with type 2 diabetes mellitus (T2DM). METHODS: A total of 140 cases with T2DM were assigned to 2 groups taking metformin (n = 75) or not (n = 65). All cases received intensive control of blood glucose, blood pressure and blood lipids for 100 weeks. The data before and after intensive control were recorded and statistically analyzed. Common carotid intima-media thickness (CC-IMT) was the efficacy endpoint of AS. RESULTS: Diastolic blood pressure (DBP), fasting blood glucose, post 2-hour blood glucose, glycated hemoglobin A1c, triglyceride (TG) and total cholesterol (TC) decreased in both groups after intensive metabolic control for 100 weeks (P < 0.05). Body mass index (BMI), HOMA insulin resistance index (HOMA-IR) and CC-IMT decreased in metformin group (P < 0.05) while high-density lipoprotein cholesterol (HDL-C) increased (P < 0.05). BMI (23.1 +/- 0.98) kg/m2, HOMA-IR (1.68 +/- 0.20) and CC-IMT (0.55 +/- 0.13) mm in metformin group were lower than those in non-metformin group [(24.1 +/- 0.05) kg/m2, 2.03 +/- 1.38, (0.70 +/- 0.15) mm)] at 100 week (P < 0.05). CC-IMT was positively correlated with BMI (r = 0.489, P < 0.05) , TC (r = 0.429, P < 0.05), low-density lipoprotein cholesterol (LDL-C) (r = 0.426, P < 0.05) and HOMA-IR (r = 0.428, P < 0.05). CONCLUSION: Metformin attenuates CC-IMT of patients with T2DM and it has the primary preventive effect upon AS in patients with T2DM.

Association of SelS mRNA expression in omental adipose tissue with Homa-IR and serum amyloid A in patients with type 2 diabetes mellitus.

BACKGROUND: Tanis was reported as a putative receptor for serum amyloid A (SAA) involving glucose regulated protein in insulin regulated resistance. It was found to be dysregulated in diabetic rats (Psammomys obesus, Israeli sand rat) and its homologue for humans is SelS/AD-015. The present study analyzed mRNA expression of SelS in omental adipose tissue biopsies from patients with type 2 diabetes mellitus (T2DM), and age- and weight-matched nondiabetic patients, the relationship of SelS mRNA with Homa-IR and serum SAA level. METHODS: Human omental adipose tissues from ten cases of type 2 diabetic patients and twelve cases of nondiabetic individuals were analyzed for the expression level of SelS mRNA by semiquantitative polymerase chain reaction (PCR), Homa-IR estimated by standard formula and SAA level by enzyme-linked immunosorbent assay (ELISA). RESULTS: SelS mRNA expression, Homa-IR and serum SAA were higher in T2DM sufferers than in nondiabetic control group. SelS mRNA level was positively correlated with Homa-IR and SAA level in each group. CONCLUSIONS: SelS protein may be involved in insulin resistance in Chinese with T2DM by acting as the SAA receptor, thus playing an important role in the development of T2DM and atherosclerosis.