Influence of tumour necrosis factor alpha on the outcome of ischaemic postconditioning in the presence of obesity and diabetes.

Obesity and diabetes contribute to cardiovascular disease and alter cytokine profile. The cytokine, tumour necrosis factor alpha (TNFα), activates a protective signalling cascade during ischaemic postconditioning (IPostC). However, most successful clinical studies with IPostC have not included obese and/or diabetic patients. We aimed to investigate the influence of TNFα on the outcome of IPostC in obese or diabetic mice. TNF knockout or wildtype mice were fed for 11 weeks with a high carbohydrate diet (HCD) to induce modest obesity. Diabetes was induced in a separate group by administration of a single intraperitoneal injection of streptozotocin. Hearts were then isolated and subjected to ischaemia (35 min of global ischaemia) followed by 45 min of reperfusion. HCD increased body weight, plasma insulin and leptin levels while the glucose level was unchanged. In streptozotocin-treated mice, blood glucose, plasma leptin and insulin were altered. Control, obese or diabetic mice were protected with IPostC in wiltype animals. In TNF knockout mice, IPostC failed to protect control and diabetic hearts while a slight protection was observed in obese hearts. Our data confirm a bidirectional role for TNFα associated with the severity of concomitant comorbidities and suggest that diabetic and/or modestly obese patients may still benefit from IPostC.