Caspase-3 Is a Pivotal Regulator of Microvascular Rarefaction and Renal Fibrosis after Ischemia-Reperfusion Injury

Abstract

Ischemia-reperfusion injury (IRI) is a major risk factor for chronic renal failure. Here, we characterize the different modes of programmed cell death in the tubular and microvascular compartments during the various stages of IRI-induced AKI, and their relative importance to renal fibrogenesis. We performed unilateral renal artery clamping for 30 minutes and contralateral nephrectomy in wild-type mice (C57BL/6) or caspase-3 mice. Compared with their wild-type counterparts, caspase-3 mice in the early stage of AKI had high urine cystatin C levels, tubular injury scores, and serum creatinine levels. Electron microscopy revealed evidence of tubular epithelial cell necrosis in caspase-3 mice, and immunohistochemistry showed upregulation of the necroptosis marker receptor-interacting serine/threonine-protein kinase 3 (RIPK3) in renal cortical sections. Western blot analysis further demonstrated enhanced levels of phosphorylated RIPK3 in the kidneys of caspase-3 mice. In contrast, caspase-3 mice had less microvascular congestion and activation in the early and extension phases of AKI. In the long term (3 weeks after IRI), caspase-3 mice had reduced microvascular rarefaction and renal fibrosis, as well as decreased expression of -smooth muscle actin and reduced collagen deposition within peritubular capillaries. Moreover, caspase-3 mice exhibited signs of reduced tubular ischemia, including lower tubular expression of hypoxia-inducible factor-1 and improved tubular injury scores. These results establish the pivotal importance of caspase-3 in regulating microvascular endothelial cell apoptosis and renal fibrosis after IRI. These findings also demonstrate the predominant role of microvascular over tubular injury as a driver of progressive renal damage and fibrosis after IRI.

Potent Therapy and Transcriptional Profile of Combined Erythropoietin Derived Peptide CHBP and Caspase-3 siRNA against Kidney Ischemia/Reperfusion Injury in mice

“…The GREM1-VEGFR2 axis may be a novel therapeutic target for kidney in ammation and brosis (Mezzano et al, 2018). In addition, Yang and colleagues proposed that caspase-3 de ciency in mice reduced IR injury in kidneys through preserving microvascular density (Yang et al, 2018). However, whether the preservation of renal microvasculature in this study links to regulated GREM1 is worthy of further investigating.…”

Transcriptional Profiles in Ischemia/Reperfusion-Injured Murine Kidneys Synergistically Protected by Erythropoietin Derived Peptide CHBP and Caspase-3 siRNA

“…The GREM1-VEGFR2 axis may be a novel therapeutic target for kidney inflammation and fibrosis [54]. In addition, Yang and colleagues proposed that caspase-3 deficiency in mice reduced IR injury in kidneys through preserving microvascular density [55]. However, whether the preservation of renal microvasculature in this study links to regulated GREM1 is worthy of further investigating.…”

Extracellular Vesicles as Mediators of Cellular Crosstalk Between Immune System and Kidney Graft

“…IRI induces a complex vascular phenotype characterized by a progressive spectrum of functional and structural alterations: vasoconstriction, vascular inflammation, microvascular rarefaction of peritubular capillaries, chronic hypoxia, interstitial fibrosis, and tubular atrophy (126,127). Microvascular lesions appear to be a key driver of fibrosis after IRI, with a predominant effect over tubular ones (128).…”

“…Caspase-3 is a pivotal regulator of cell apoptosis (128); under physiological conditions, endothelial EVs protect parental cell by removing caspase-3 (130). During IRI, caspase-3 hyperactivation can overtake EV clearance and cause cell death.…”