Bootcongres

Introduction. Ischemia-reperfusion injury (IRI) is inevitable during kidney transplantation and leads to oxidative stress and inflammation. We previously reported that short-term preoperative dietary restriction (DR), 3-day fasting and a protein-free diet protect against IRI while a fat-free or carbohydrate-free (CHO-free) diet do not. To understand the underlying mechanisms, we performed microarray analysis and compared gene expression profiles of both protective and non-protective diets in search for pathways involved in the effect. Methods. Male C57BL/6 mice, between 8-12 weeks of age and weighing 20-25 grams were randomized to preoperative ad libitum feeding or one of several diets: 2 weeks 30%DR, 3-day fasting, 3-day protein free-, 3-day CHO-free or 3-day fat-free. Directly after each diet, kidneys were harvested and RNA was isolated. Gene expression profiles of kidneys were analysed by Affymetrix array and the R software. Pathway analysis was done with Ingenuity. Cut-off values for significance were set on fold change ≥1.5 and p-value <0.05. Results. Compared to ad libitum fed, 2 weeks 30%DR resulted in 492 differentially expressed genes (DEG) in kidney tissue. Similarly, 3-day fasting led to 2604 DEG and a protein-free diet to 391 DEG. The fat-free diet resulted in zero DEG while a CHO-free diet led to 1717 DEG. Comparing gene expression profiles, 70 DEG overlapped in all 3 diets protective against IRI, of which 30 were also differentially expressed in CHO-free. Ingenuity analysis of the 70 genes revealed the involvement of metabolic processes like retinol biosynthesis as well as stress responses like GADD45, Acute Phase Response Signalling and up-regulation of the NRF2-pathway. Preliminary in depth analysis shows differences in expression of genes involved in these pathways between protective diets and a CHO-free diet, such as txnip and mrp1. This suggests a central role of these genes. Conclusions. This unique microarray dataset of different dietary interventions points to the involvement of pathways related to oxidative stress resistance and retinol metabolism in the beneficial effects of 3 diets protective against renal IRI. Since the non-protective CHO-free diet also induced up-regulation of potentially protective pathways, these findings need to be further explored. Collectively, these data suggest that a combined action of both metabolic and stress resistance pathways results in protection against IRI by preoperative dietary interventions.