Hypoxia inducible factor stabilization improves defective ischemia-induced angiogenesis in a rodent model of chronic kidney disease

Abstract

Chronic kidney disease (CKD) is associated with increased risk and worse prognosis of cardiovascular disease, including peripheral artery disease. An impaired angiogenic response to ischemia may contribute to poor outcomes of peripheral artery disease in patients with CKD. Hypoxia inducible factors (HIF) are master regulators of angiogenesis and therefore represent a promising target for therapeutic intervention. To test this we induced hind-limb ischemia in rats with CKD caused by 5/6 nephrectomy and administered two different treatments known to stabilize HIF protein in vivo: carbon monoxide and a pharmacological inhibitor of prolyl hydroxylation 2-(1-chloro-4- hydroxyisoquinoline-3-carboxamido) acetate (ICA). Expression levels of pro-angiogenic HIF target genes (Vegf, Vegf-r1, Vegf-r2, Ho-1) were measured by qRT-PCR. Capillary density was measured by CD31 immunofluorescence staining and HIF expression was evaluated by immunohistochemistry. Capillary density in ischemic skeletal muscle was significantly lower in CKD animals compared to sham controls. Rats with CKD showed significantly lower expression of HIF and all measured pro-angiogenic HIF target genes, including VEGF. Both HIF stabilizing treatments rescued HIF target gene expression in animals with CKD and led to significantly higher ischemia-induced capillary sprouting compared to untreated controls. ICA was effective regardless of whether it was administered before or after induction of ischemia and led to a HIF expression in skeletal muscle. Thus, impaired ischemia-induced angiogenesis in rats with CKD can be improved by HIF stabilization, even if started after onset of ischemia.

Reduced Estimated GFR and Cardiac Remodeling: A Population-Based Autopsy Study

“…37 Uremia may lead to endothelial cell dropout or may cause angiogenesis to fail to occur as a compensatory response to ischemia, possibly because of destabilized hypoxia-inducible factor or the inhibition of nitric oxide synthase by asymmetric dimethylarginine. 38,39 In another pathway, elevated levels of asymmetric dimethyl arginine and other inhibitors of angiogenesis may lead to myocardial fibrosis and capillary rarefaction through endothelial-to-mesenchymal transformation; that is, the transformation of endothelial cells into fibroblasts. 40,41 Therefore, microvascular dysfunction may have caused the patchy and interstitial fibrosis observed in our present study.…”

“…In addition, to evaluate the width of cardiomyocytes or fibrosis of the myocardium pathohistologically, 95 individuals (45 men and 50 women) were randomly selected using a computergenerated random number from each eGFR category by matching for age at death and sex in a 2:1:1:1 ratio against individuals in the <30-mL/min/1.73 m 2 category, in which all individuals with eGFRs ≤ 30 mL/min/1.73 m 2 were used. The numbers of individuals in each group were 38,19,19, and 19 for eGFRs of ≥60, 45 to 59, 30 to 44, and <30 mL/min/1.73 m 2 , respectively. Autopsy examinations were performed at the Department of Pathology, Kyushu University.…”

Hypoxia and HIF Signaling: One Axis with Divergent Effects

“…In kidney injury and repair, hypoxia responses depend mainly on erythropoiesis, angiogenesis, and anaerobic glucose metabolism. Erythropoietin (EPO) and glycolytic genes are mainly regulated by HIF2-α or HIF1-α, respectively [ 129 , 130 ], while VEGF induction is regulated by HIF1-α and HIF2-α [ 131 ].…”

Role of hypoxia‐inducible factor 1α as a potential biomarker for renal diseases—A systematic review

“…CKD can result in the down regulation of HIF and of the genes it mediates, such as VEGF and HO‐1, which are crucial for angiogenesis. Schellinger et al studied renal ischemia in rodents and observed that increased HIF leads to capillary exploration and reduced angiogenesis during renal insufficiency, confirming the protective effect of HIF against ischemia‐induced renal disease.…”