Mitochondrial and contractile dysfunction in a swine model of early chronic kidney disease

Abstract

Abstract Background Numerous clinical trials have demonstrated that patients with kidney damage have an increased chance of developing heart failure, and the risk is compounded in people with diabetes. Cardiac remodeling occurs at very early stages of kidney injury but studies undertaken to pinpoint the common biomarkers of cardiorenal signaling are still inadequate, which may be due to the fact that research done on rodent models does not fully reflect the complexity of the disease. We and our collaborators established swine models for diabetes (DM- insulin gene INS mutation) and chronic kidney disease (CKD- renal microembolisation) to overcome the translational gap associated with rodent models. Purpose In order to provide mechanistic as well as therapeutic insights, we used proteomic analyses to elucidate the pathophysiological effects of DM and CKD on the heart. Methods We used microspheres to embolise both kidneys of wild type and diabetic swine at 10-12 weeks of age and 6 months later we performed quantitative LC-MS-MS based proteomic analyses of left ventricular tissue from these four groups (wild type (WT), wild type with CKD (WT_CKD), diabetic (DM) and diabetic with CKD (DM_CKD). STRING bioinformatics software was used to identify significantly enriched pathways. Results Masson Trichrome staining confirmed the presence of kidney damage and fibrosis in CKD animals (Fig1 A). Quantitative proteomic analysis detected significant differences in the left ventricle of the WT or DM swine when compared to those with CKD using a volcano plot (Fig1B,C). STRING pre-ranked functional analysis showed pathway enrichments in both the comparisons (Fig2A,B). We found that proteins involved in the remodeling of the extracellular matrix (ECM), such as C3, F9, Col6A2, and FBN1, were downregulated in both groups (WT CKD and DM CKD as compared to WT and DM respectively). Interestingly, in WT_CKD we found that mitochondrial proteins like cytochrome oxidase (MT-CO2) and ATP5 synthase subunit were downregulated suggesting mitochondrial dysfunction. Strong indicators of this dysfunction include pathways with altered regulation of reactive oxygen species like hydrogen peroxide and substantial downregulation of contractile proteins like phospholamban, which maintains the Ca2+ homeostasis. DM_CKD on the other hand when compared to DM suggested presence of an inflammatory milieu with alterations of metabolic, wound healing and immune cell regulation pathways. Conclusions Our proteomic data in swine model provides strong evidence that mild CKD can induce early alterations in contractile proteins of the heart due to mitochondrial dysfunction along with ECM remodeling. In the presence of diabetes, metabolic and immune cells play a more predominant role in early part of the disease. Thus, we aim to further our understanding by applying our proteomic findings in conjunction with functional hemodynamic data in this swine model of cardiorenal disease.Figure 1Figure 2