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Endothelium-derived neuregulin protects the heart against ischemic injury.

ABSTRACT: Removal of cardiac endothelial cells (EC) has been shown to produce significant detrimental effects on the function of adjacent cardiac myocytes, suggesting that EC play a critical role in autocrine/paracrine regulation of the heart. Despite this important observation, the mediators of the protective function of EC remain obscure. Neuregulin (NRG, a member of the epidermal growth factor family) is produced by EC and cardiac myocytes contain receptors (erbB) for this ligand. We hypothesized that NRG is an essential factor produced by EC, which promotes cardioprotection against ischemic injury.We demonstrate that human cardiac EC express and release NRG in response to hypoxia-reoxygenation. Under conditions where hypoxia--reoxygenation causes significant cardiac myocyte cell death, NRG can significantly decrease apoptosis of isolated adult ventricular myocytes. Coculturing adult murine myocytes with human umbilical vein, murine lung microvascular, or human coronary artery EC can also protect myocytes against hypoxia--reoxygenation--induced apoptosis. These protective effects are abolished by NRG gene deletion or silencing of NRG expression in EC. Finally, endothelium-selective deletion of NRG in vivo leads to significantly decreased tolerance to ischemic insult, as demonstrated by impaired postischemic contractile recovery in a perfused whole-organ preparation and larger infarct sizes after coronary artery ligation.Together, these data demonstrate that EC-derived NRG plays an important role in cardiac myocyte protection against ischemic injury in the heart and supports the idea that manipulation of this signaling pathway may be an important clinical target in this setting.

SUBMITTER: Hedhli N

PROVIDER: S-EPMC3104502 | biostudies-literature | 2011 May

REPOSITORIES: biostudies-literature

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Endothelium-derived neuregulin protects the heart against ischemic injury.

Hedhli Nadia N Huang Qunhua Q Kalinowski April A Palmeri Monica M Hu Xiaoyue X Russell Raymond R RR Russell Kerry S KS

Circulation 20110509 20

<h4>Background</h4>Removal of cardiac endothelial cells (EC) has been shown to produce significant detrimental effects on the function of adjacent cardiac myocytes, suggesting that EC play a critical role in autocrine/paracrine regulation of the heart. Despite this important observation, the mediators of the protective function of EC remain obscure. Neuregulin (NRG, a member of the epidermal growth factor family) is produced by EC and cardiac myocytes contain receptors (erbB) for this ligand. We ...[more]

PMID: 21555713

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Project description:Background: Acute kidney injury (AKI) is a common clinical event with high morbidity and mortality. We previously demonstrated that injection of cord blood endothelial colony forming cell (ECFC)-derived exosomes, highly enriched in miRNA(miR)-486-5p, prevented ischemic kidney injury in mice. While preclinical models support involvement of several miRs in AKI, the direct effects of miR-486-5p on injury and the kidney transcriptome are unknown. Objective: We studied effects of miR-486-5p in mice with kidney ischemia-reperfusion (IR) injury, and compared the impact of miR-486-5p and ECFC-derived exosomes on the transcriptome of proximal tubules (PTs) and renal endothelial cells. Methods: Adult male mice were subjected to bilateral kidney ischemia (30 min), and injected via tail vein with or without vehicle, miR-486-5p mimic, ECFC-derived exosomes, or scramble miR at the start of reperfusion. Plasma and tissues were collected 24 hrs after reperfusion, and proximal tubular and endothelial cells were isolated for mRNA analysis by RNA-Seq. Results: In mice with kidney IR, injection of miR-486-5p mimic increased levels of miR-486-5p in proximal tubules and endothelial cells, and significantly improved plasma creatinine, histological injury, neutrophil infiltration, and apoptosis, compared to vehicle treatment. MiR-486-5p inhibited expression of phosphatase and tensin homolog (PTEN), and activated AKT. Similar results were observed with exosomes, but scramble miR had no effect. In proximal tubules, miR-486-5p or exosomes reduced expression of several AKI genes (e.g. Lcn2, Havcr1 and Krt20) and caused alterations in apoptotic genes compared to IR alone. In endothelium, miR-486-5p or exosomes caused milder effect than in PTs but still impacting on expression of injury-related genes. Conclusion: MiR-486-5p protects mice against ischemic kidney injury. Both miR-486-5p and exosomes reduce expression of apoptotic genes in PTs and endothelium. The results suggest that systemic delivery of miR-486-5p has therapeutic potential in ischemic AKI.

Project description:BackgroundUremic cardiomyopathy is a common cardiovascular complication of chronic kidney disease (CKD) characterized by left ventricular hypertrophy (LVH) and fibrosis enhancing the susceptibility of the heart to acute myocardial infarction. In the early stages of CKD, approximately 60% of patients are women. We aimed to investigate the influence of sex on the severity of uremic cardiomyopathy and the infarct size-limiting effect of ischemic preconditioning (IPRE) in experimental CKD.MethodsCKD was induced by 5/6 nephrectomy in 9-week-old male and female Wistar rats. Two months later, serum and urine laboratory parameters were measured to verify the development of CKD. Transthoracic echocardiography was performed to assess cardiac function and morphology. Cardiomyocyte hypertrophy and fibrosis were measured by histology. Left ventricular expression of A- and B-type natriuretic peptides (ANP and BNP) were measured by qRT-PCR and circulating BNP level was measured by ELISA. In a subgroup of animals, hearts were perfused according to Langendorff and were subjected to 35 min global ischemia and 120 min reperfusion with or without IPRE (3 × 5 min I/R cycles applied before index ischemia). Then infarct size or phosphorylated and total forms of proteins related to the cardioprotective RISK (AKT, ERK1,2) and SAFE (STAT3) pathways were measured by Western blot.ResultsThe severity of CKD was similar in males and females. However, CKD males developed more severe LVH compared to females as assessed by echocardiography. Histology revealed cardiac fibrosis only in males in CKD. LV ANP expression was significantly increased due to CKD in both sexes, however, LV BNP and circulating BNP levels failed to significantly increase in CKD. In both sexes, IPRE significantly decreased the infarct size in both the sham-operated and CKD groups. IPRE significantly increased the phospho-STAT3/STAT3 ratio in sham-operated but not in CKD animals in both sexes. There were no significant differences in phospho-AKT/AKT and phospho-ERK1,2/ERK1,2 ratios between the groups.ConclusionThe infarct size-limiting effect of IPRE was preserved in both sexes in CKD despite the more severe uremic cardiomyopathy in male CKD rats. Further research is needed to identify crucial molecular mechanisms in the cardioprotective effect of IPRE in CKD.

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Endothelium-derived neuregulin protects the heart against ischemic injury.

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Endothelium-derived neuregulin protects the heart against ischemic injury.

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