Glucose and Fatty Acid Metabolism in a 3 Tissue In-Vitro Model Challenged with Normo- and Hyperglycaemia

Nutrient balance in the human body is maintained through systemic signaling between different cells and tissues. Breaking down this circuitry to its most basic elements and reconstructing the metabolic network in-vitro provides a systematic method to gain a better understanding of how cross-talk between the organs contributes to the whole body metabolic profile and of the specific role of each different cell type. To this end, a 3-way connected culture of hepatocytes, adipose tissue and endothelial cells representing a simplified model of energetic substrate metabolism in the visceral region was developed. The 3-way culture was shown to maintain glucose and fatty acid homeostasis in-vitro. Subsequently it was challenged with insulin and high glucose concentrations to simulate hyperglycaemia. The aim was to study the capacity of the 3-way culture to maintain or restore normal circulating glucose concentrations in response to insulin and to investigate the effects these conditions on other metabolites involved in glucose and lipid metabolism. The results show that the system’s metabolic profile changes dramatically in the presence of high concentrations of glucose, and that these changes are modulated by the presence of insulin. Furthermore, we observed an increase in E-selectin levels in hyperglycaemic conditions and increased IL-6 concentrations in insulin-free-hyperglycaemic conditions, indicating, respectively, endothelial injury and proinflammatory stress in the challenged 3-way system

A polymorphism at the IL6ST (gp130) locus is associated with traits of the metabolic syndrome

The interleukin 6 signal transducer (IL6ST, also known as gp130) is a ubiquitously expressed intermediate of the interleukin-6 signaling pathway. We investigated whether genetic variability at the IL6ST locus is involved in the modulation of metabolic traits and the etiology of the metabolic syndrome (MS). Four haplotype-tagging single nucleotide polymorphisms were typed in two populations of non-diabetic subjects, one from Northern Italy (Padua (PD), n = 630), the other from Southern Italy (San Giovanni Rotondo (SGR), n = 553). In the PD population, a nominally significant association was observed between fasting glucose and rs715180 (P = 0.02), rs3729960 (P 0.02), and rs10940495 (P = 0.05), between homeostasis model assessment index (HOMA(IR)) and rs715180 (P = 0.04), and between triglycerides and rs3729960 (P = 0.03). In the SGR population, high-density lipoprotein (HDL) levels were associated with rs715180 (P = 0.01), systolic blood pressure and waist circumference with rs3729960 (P = 0.005 and 0.02, respectively). The frequency of rs715180 minor allele carriers progressively decreased from individuals with no MS components to those with three or more components (P for trend = 0.006 in the two populations combined). Compared to major allele homozygotes, minor allele carriers had 40% lower odds of having at least one MS component (Odds ratio = 0.6, 95% confidence interval 0.4-0.8, P = 0.005). These findings point to IL6ST variants as possible determinants of impaired glucose metabolism and other abnormalities of MS

Short-term statin discontinuation increases endothelial progenitor cells without inflammatory rebound in type 2 diabetic patients.

Type 2 diabetes (T2D) is characterized by impaired vascular regeneration owing to reduced endothelial progenitor cells (EPCs). While statins are known to increase EPCs, the effects of statin withdrawal on EPCs are unknown. Herein, we evaluated the effects of statin discontinuation on EPCs, inflammation and in vivo angiogenesis. Thirty-four T2D patients were randomized to 5-day discontinuation or continuation of statin treatment. At baseline and at day 5, we determined lipid profile, EPC levels, monocyte-macrophage polarization, and concentrations of hsCRP, VEGF, SDF-1\u3b1, and G-CSF. Angiogenesis by human circulating cells was assessed in vivo. At day 5, patients who stopped statins showed raised total and LDL cholesterol and EPCs compared to baseline, while no changes were observed in patients who continued statins. No changes were observed in hsCRP, VEGF, SDF-1\u3b1, G-CSF, M1 and M2 macrophages and classical, intermediate and nonclassical monocytes in both groups. In vivo angiogenesis by circulating cells was increased in patients who stopped statin treatment. In vitro, cholesterol supplementation stimulated mobilizing signals in human bone marrow mesenchymal stem cells. In conclusion, a brief statin withdrawal increases circulating EPCs and functional proangiogenic cells in T2D. These findings identify statin-sensitive pathways as reverse target mechanisms to stimulate vascular repair in diabetes