Abstract
Stress hyperglycemia and inflammation frequently develop in open heart surgery patients. Although both factors independently contribute to increased peri-operative morbidity and mortality, the impact of high glucose levels on cardiac inflammatory response remains unknown. We investigated the isolated working rat heart as a model to study cardiac early stress response to surgery. Hearts of male Sprague Dawley rats were cold-arrested and subjected to 60 minutes normothermic reperfusion in the working mode with Krebs-Henseleit buffer supplemented with ketone bodies and propionate plus glucose (25 mM) or mannitol (25 mM; osmotic control). Alterations of gene expression in the left ventricle were determined by microarray and real-time PCR analyses. Compared to non-perfused hearts, perfused hearts displayed a more than twofold increased expression for 71 genes (mannitol group) and 103 genes (glucose group) connected to inflammation, cell proliferation, and apoptosis. The transcriptional changes were highly similar to gene alterations previously reported in the right atrium (
P
< 2.34E-16) and left ventricle (
P
< 4.83E-46) of patients who underwent cardiac surgery with cardiopulmonary bypass. Pathway analysis with Reactome revealed an up-regulation of metabolic processes associated with the proliferation and activation of immune cells, including glycolysis, glutaminolysis, fatty acid synthesis, polyamine synthesis, and hexosamine synthesis. Although the transcriptional remodeling occurred independently from the presence of glucose, glucose significantly increased further the expression of several transcription factors and markers associated with M2 polarization of macrophages, including Myc (1.6-fold), Nr4a1 (1.3-fold), Nr4a2 (1.8-fold), Zc3h12a (1.3-fold), Fosl2 (1.4-fold), Cebpb (1.2-fold), and Arg1 (1.7-fold). Interestingly, glucose failed to enhance the expression of M2-related genes in the heart of rats rendered insulin resistant by high-sucrose feeding. Besides demonstrating that the isolated working rat heart accurately reproduces the stress response associated with open heart surgery, the results also suggest that glucose promotes the alternative activation of resident cardiac macrophages in the stressed heart.