Mohamed, Tamer

Abstract BACKGROUND AND AIMS Chronic kidney disease (CKD) is an independent risk factor for heart failure with preserved ejection fraction (HFpEF), a progressive condition that affects ˃50% of patients in dialysis. We developed a swine model of CKD-HFpEF and showed that renal inflammatory signaling plays a key role in HFpEF pathophysiology via cardiac activation of nuclear factor-kappa B (NF-kB). However, the mechanisms of CKD-induced cardiac NF-κB activation remain unclear. We hypothesized that micro-RNA (miRNA)-mediated processes contribute to cardiac NF-kB activation in CKD-HFpEF. METHOD Using an in-silico approach (miRWalk3.0 and TargetScan 7.2), we identified all miRNAs capable of targeting the NFKB Inhibitor Alpha (NFKBIA) gene. We then identified those expressed in swine myocardium and measured their levels in normal and CKD pigs by qPCR. In a biomimetic heart culture system that mimics the cardiac CKD-HFpEF microenvironment, pig heart slices were exposed to plasma from normal or CKD pigs, and cardiac kinetics, NF-kB signaling, and miRNA expression levels were investigated in vitro. RESULTS We identified 5 miRNAs expressed in swine hearts capable of targeting NFKBIA, of which only miR-1271–3p showed higher expression in the myocardium of CKD-HFpEF pigs compared to normal pigs. miR-1271–3p upregulation was mirrored in pig heart slices exposed to plasma from CKD pigs, associated with blunted cardiac contraction/relaxation kinetics, downregulation of NFKBIA, and increased protein expression of NF-κB (Figure). CONCLUSION Our data support a novel pathophysiological mechanism for cardiac activation of NF-κB in CKD via post-transcriptional modulation of NFKBIA partly through miR-1271–3p. This miRNA might represent a novel therapeutic target to ameliorate the deleterious effects that renal inflammatory signaling in CKD imposes on the heart and may lead to HFpEF.

Background Chronic kidney disease (CKD) carries a higher cardiovascular mortality and is a prominent risk factor for development of HFpEF. However, the pathophysiology of HFpEF in CKD has not been established. We have recently shown that experimental CKD‐HFpEF is associated with increased renal release of inflammatory cytokines, particularly tumor necrosis factor (TNF)‐α and interleukin (IL)‐6, to the systemic circulation. Using a unique physiological biomimetic heart culture system, we test whether inflammatory cytokines of kidney origin contribute to the development of HFpEF in CKD. Methods Pigs (4 each) were assigned to sham or CKD (bilateral renovascular disease and dyslipidemia) groups and followed for 14 weeks. Circulating levels of TNF‐α and IL‐6 were quantified (ELISA). In a biomimetic heart culture system, pig heart slices were exposed to plasma from normal or CKD pigs, or from normal pigs enriched with TNF‐α and IL‐6 (matching CKD concentration) with or without cytokine neutralizing antibodies (NA). Contractility and relaxation kinetics in vitro were determined in a dose/time dependent manner. Results CKD‐HFpEF pigs exhibited elevated systemic levels of TNF‐α and IL‐6 (Figure 1A), associated with renal dysfunction, cardiac hypertrophy and fibrosis, and diastolic dysfunction. Plasma was collected from all animals. Then, pig heart slices were exposed to CKD‐HFpEF, normal, or normal plasma enriched with cytokines, showing impaired contractility and speed of relaxation that improved after TNF‐α and IL‐6 neutralization (Figure 1B). Conclusions Our observations implicate circulating inflammatory mediators released by dysfunctional kidneys in imposing damage to the remote myocardium, supporting a role of inflammatory cytokines of renal origin in renal‐cardio pathophysiology in CKD‐HFpEF.