Bruno Schisano

GLP-1 analogue, Liraglutide protects human umbilical vein endothelial cells against high glucose induced endoplasmic reticulum stress

BACKGROUND AND PURPOSE Hyperglycemia induced endoplasmic reticulum (ER) stress in diabetic vascular cells is considered an increasingly important factor for the genesis and development of atherosclerosis and cardiovascular complications. This study investigated firstly, the effect of hyperglycemia in ER stress induction in Human Umbilical Vein Endothelial Cells (HUVECs) and secondly, the impact of Glucagon like petide-1 (GLP-1) analogue, Liraglutide, in reducing ER stress in HUVECs exposed to high glucose (HG). EXPERIMENTAL APPROACH HUVECs were incubated for 12 hr in 5 mmol/L normal glucose (NG) or in 25 mmol/L (HG) glucose with or without different concentrations of Liraglutide (1 nM, 10 nM or 100 nM) and components of ER stress pathways studied, using western blotting, to assess their expression levels. KEY RESULTS Our data confirmed that exposure of HUVECs to HG up-regulated both up- (Bip/Grp78, PERK and IRE1α) and downstream (Calnexin, PDI and Ero1-Lα) markers of ER stress compared with control. Furthermore, Liraglutide showed a dose dependent capacity in preventing the onset of ER stress in HUVECs, with a maximum activity at 100 nM. HG also upregulated proapoptotic PUMA protein levels compared to controls. Interestingly, Liraglutide also induced OPA1, a marker of mitochondrial fusion, in a dose dependent manner. CONCLUSIONS AND IMPLICATIONS Liraglutide prevented the onset of ER stress in human endothelial cells exposed to HG. Our data suggest that Liraglutide may exert its effects by inducing mitochondrial fusion processes, thus preventing HG induced mitochondrial fragmentation and apoptosis in human endothelial cells.

Lipopolysaccharide, high glucose and saturated fatty acids induce endoplasmic reticulum stress in cultured primary human adipocytes: Salicylate alleviates this stress

Recent findings indicate that endoplasmic reticulum (ER) stress is significantly increased in adipose tissue of obese human subjects and is critical to the initiation and integration of pathways of inflammation and insulin action. But the factors inducing ER stress in human adipose tissue are unknown. The common factors increased in obesity and linked to insulin resistance are hyperglycaemia, hyperlipidemia and also endotoxemia. Therefore, our aims were to investigate: (1) the role of lipopolysaccharide (LPS), high glucose (HG) and saturated fatty acids (SFA) as inducers of ER stress in primary human adipocytes and (2) whether salicylate, a known anti-inflammatory compound, can alleviate this effect. Components of the ER stress pathways were studied in human abdominal subcutaneous (AbSc) adipose tissue (AT) from obese and lean. Following the culture and differentiation of primary human preadipocytes, these adipocytes were treated with LPS, HG, tunicamycin (Tun) and SFA either alone or in combination with sodium salicylate (Sal). Markers of ER stress were significantly increased in AbSc AT of obese. Differentiated human adipocytes treated with LPS, Tun, HG and SFA showed significant activation of eukaryotic translation initiation factor 2alpha (eIF2alpha) and activating transcription factor 6 (ATF6) and their down-stream targets. Sal alleviated this effect and activated AktSer473 phosphorylation. This study presents important evidence that: (1) there is increased ER stress in adipose tissue of obese individuals, (2) LPS, hyperglycaemia and saturated fatty acids induce significant ER stress in primary human adipocytes and (3) this induction is alleviated by salicylate.

Characterization of a novel polymorphism in PPARG regulatory region associated with type 2 diabetes and diabetic retinopathy in Italy.

Peroxisome proliferator-activated receptor gamma polymorphisms have been widely associated with type 2 diabetes, although their role in the pathogenesis of vascular complications is not yet demonstrated. In this study, a cohort of 211 type 2 diabetes, 205 obese, and 254 control individuals was genotyped for Pro12Ala, C1431T, C-2821T polymorphisms, and for a newly identified polymorphism (A-2819G). The above-mentioned polymorphisms were analyzed by gene-specific PCR and direct sequencing of all samples. A significant difference was found for -2819G frequency when patients with type 2 diabetes—particularly diabetic women with the proliferative retinopathy—were compared with healthy control individuals. In conclusion, we identified a novel polymorphism, A-2819G, in PPARG gene, and we found it to be associated with type 2 diabetes and proliferative retinopathy in diabetic females. In the analyzed population, this variant represents a genetic risk factor for developing the diabetic retinopathy, whereas Pro12Ala and C1431T do not.

Liraglutide down regulates endoplasmic reticulum stress in human endothelial cells exposed to hyperglycaemia

Background and aims: The association between type 2 diabetes and different forms of cognitive impairment is well established. The mechanism behind the association is however still unrevealed. We ha ...

A novel role for p53 in the regulation of oxidative stress in vascular cells in response to glucose fluctuation

Prevalence of lipid abnormalities before and after the introduction of lipid modifying therapy among Swedish patients with type 2 diabetes and/or coronary heart disease (PRIMULA Sweden)In the ACTION (A Coronary disease Trial Investigating Outcome with Nifedipine GITS) trial, the benefits of adding nifedipine GITS to the treatment of patients with stable symptomatic coronary artery disease were particularly apparent in those with concomitant hypertension. This further analysis has assessed whether or not the addition of nifedipine GITS is particularly beneficial in the treatment of patients with the combination of diabetes mellitus and chronic stable angina.Different sets of risk factors for the development of albuminuria and renal impairment in type 2 diabetes : the Swedish National Diabetes register (NDR)