Nonsteroidal Mineralocorticoid Receptor Antagonist Finerenone Protects Against Acute Kidney Injury-Mediated Chronic Kidney Disease: Role of Oxidative Stress.

Acute kidney injury induced by ischemia/reperfusion (IR) is a frequent complication in hospitalized patients. Mineralocorticoid receptor antagonism has shown to be helpful against renal IR consequences; however, the potential benefit of novel nonsteroidal mineralocorticoid receptor antagonists such as finerenone has to be further explored. In this study, we evaluated the efficacy of finerenone to prevent the acute and chronic consequences of ischemic acute kidney injury. For the acute study (24 hours), 18 rats were divided into sham, bilateral renal ischemia of 25 minutes, and rats that received 3 doses of finerenone at 48, 24, and 1 hour before the ischemia. For the chronic study (4 months), 23 rats were divided into sham, rats that underwent 45 minutes of bilateral ischemia, and rats treated with finerenone at days 2 and 1 and 1 hour before IR. We found that after 24 hours of reperfusion, the untreated IR rats presented kidney dysfunction and tubular injury. Kidney injury molecule-1 and neutrophil gelatinase associated to lipolacin mRNA levels were increased. In contrast, the rats treated with finerenone displayed normal kidney function and significantly lesser tubular injury and kidney injury molecule-1 and neutrophil gelatinase associated to lipolacin levels. After 4 months, the IR rats developed chronic kidney disease, evidenced by kidney dysfunction, increased proteinuria and renal vascular resistance, tubular dilation, extensive tubule-interstitial fibrosis, and an increase in kidney transforming growth factor-ß and collagen-I mRNA. The transition from acute kidney injury to chronic kidney disease was fully prevented by finerenone. Altogether, our data show that in the rat, finerenone is able to prevent acute kidney injury induced by IR and the chronic and progressive deterioration of kidney function and structure.

Cardiomyocyte-specific overexpression of oestrogen receptor ß improves survival and cardiac function after myocardial infarction in female and male mice.

ERß (oestrogen receptor ß) activation has been shown to be cardioprotective, but the cell types and mechanisms involved are not understood. To investigate whether ERß restricted to cardiomyocytes contributes to the observed cardioprotection, we tested the effects of cardiomyocyte-specific ERß-OE (ERß overexpression) on survival, cardiac remodelling and function after MI (myocardial infarction) and studied the molecular pathways potentially involved. Female and male mice with cardiomyocyte-specific ERß-OE and WT (wild-type) littermates were subjected to chronic anterior coronary artery ligation or sham surgery. Two weeks after MI, ERß-OE mice showed improved survival (100% and 83% compared with 76% and 58% in WT females and males respectively). ERß-OE was associated with attenuated LV (left ventricular) dilatation, smaller increase in heart weight, less lung congestion at similar MI size, and improved systolic and diastolic function in both sexes. We identified two potential pathways for ERß-mediated myocardial protection. First, male and female ERß-OE mice had a lower reduction of SERCA2a (sarcoplasmic/endoplasmic reticulum Ca(2+)-ATPase 2a) expression after MI, suggesting less reduction in diastolic Ca(2+)-reuptake into the sarcoplasmic reticulum post-MI. Secondly, male ERß-OE revealed attenuated cardiac fibrosis in the remote LV tissue and expression of fibrosis markers collagen I and III, periostin and miR-21. Cardiomyocyte-specific ERß-OE improved survival associated with reduced maladaptive remodelling, improved cardiac function and less heart failure development after MI in both sexes. These effects seem to be related, at least in part, to a better maintenance of Ca(2+) cycling in both sexes and a lower induction of cardiac fibrosis in males after MI.

Cardiomyocyte-specific Estrogen Receptor Alpha Increases Angiogenesis, Lymphangiogenesis and Reduces Fibrosis in the Female Mouse Heart Post-Myocardial Infarction.

Experimental studies showed that 17ß-estradiol (E2) and activated Estrogen Receptors (ER) protect the heart from ischemic injury. However, the underlying molecular mechanisms are not well understood. To investigate the role of ER-alpha (ERα) in cardiomyocytes in the setting of myocardial ischemia, we generated transgenic mice with cardiomyocyte-specific overexpression of ERα (ERα-OE) and subjected them to Myocardial Infarction (MI). At the basal level, female and male ERα-OE mice showed increased Left Ventricular (LV) mass, LV volume and cardiomyocyte length. Two weeks after MI, LV volume was significantly increased and LV wall thickness decreased in female and male WT-mice and male ERα-OE, but not in female ERα-OE mice. ERα-OE enhanced expression of angiogenesis and lymphangiogenesis markers (Vegf, Lyve-1), and neovascularization in the peri-infarct area in both sexes. However, attenuated level of fibrosis and higher phosphorylation of JNK signaling pathway could be detected only in female ERα-OE after MI. In conclusion, our study indicates that ERα protects female mouse cardiomyocytes from the sequelae of ischemia through induction of neovascularization in a paracrine fashion and impaired fibrosis, which together may contribute to the attenuation of cardiac remodelling.

Neutrophil gelatinase-associated lipocalin is a novel mineralocorticoid target in the cardiovascular system.

Mineralocorticoid receptor (MR) activation may be deleterious to the cardiovascular system, and MR antagonists improve morbidity and mortality of patients with heart failure. However, mineralocorticoid signaling in the heart remains largely unknown. Using a pan-genomic transcriptomic analysis, we identified neutrophil gelatinase-associated lipocalin (NGAL or lipocalin 2) as a strongly induced gene in the heart of mice with conditional and targeted MR overexpression in cardiomyocytes (whereas induction was low in glucocorticoid receptor-overexpressing mice). NGAL mRNA levels were enhanced after hormonal stimulation by the MR ligand aldosterone in cultured cardiac cells and in the heart of wild-type mice. Mineralocorticoid pathological challenge induced by nephrectomy/aldosterone/salt treatment upregulated NGAL expression in the heart and aorta and its plasma levels. We show evidence for MR binding to an NGAL promoter, providing a mechanism for NGAL regulation. We propose that NGAL may be a marker of mineralocorticoid-dependent injury in the cardiovascular system in mice.

The epidermal growth factor receptor is involved in angiotensin II but not aldosterone/salt-induced cardiac remodelling.

Experimental and clinical studies have shown that aldosterone/mineralocorticoid receptor (MR) activation has deleterious effects in the cardiovascular system; however, the signalling pathways involved in the pathophysiological effects of aldosterone/MR in vivo are not fully understood. Several in vitro studies suggest that Epidermal Growth Factor Receptor (EGFR) plays a role in the cardiovascular effects of aldosterone. This hypothesis remains to be demonstrated in vivo. To investigate this question, we analyzed the molecular and functional consequences of aldosterone exposure in a transgenic mouse model with constitutive cardiomyocyte-specific overexpression of a mutant EGFR acting as a dominant negative protein (DN-EGFR). As previously reported, Angiotensin II-mediated cardiac remodelling was prevented in DN-EGFR mice. However, when chronic MR activation was induced by aldosterone-salt-uninephrectomy, cardiac hypertrophy was similar between control littermates and DN-EGFR. In the same way, mRNA expression of markers of cardiac remodelling such as ANF, BNF or ß-Myosin Heavy Chain as well as Collagen 1a and 3a was similarly induced in DN-EGFR mice and their CT littermates. Our findings confirm the role of EGFR in AngII mediated cardiac hypertrophy, and highlight that EGFR is not involved in vivo in the damaging effects of aldosterone on cardiac function and remodelling.

Epidermal growth factor receptor mediates the vascular dysfunction but not the remodeling induced by aldosterone/salt.

Pathophysiological aldosterone (aldo)/mineralocorticoid receptor signaling has a major impact on the cardiovascular system, resulting in hypertension and vascular remodeling. Mineralocorticoids induce endothelial dysfunction, decreasing vasorelaxation in response to acetylcholine and increasing the response to vasoconstrictors. Activation of the epidermal growth factor receptor (EGFR) is thought to mediate the vascular effects of aldo, but this has yet to be demonstrated in vivo. In this study, we analyzed the molecular and functional vascular consequences of aldo-salt challenge in the waved 2 mouse, a genetic model with a partial loss of EGFR tyrosine kinase activity. Deficient EGFR activity is associated with global oxidative stress and endothelial dysfunction. A decrease in EGFR activity did not affect the arterial wall remodeling process induced by aldo-salt. By contrast, normal EGFR activity was required for the aldo-induced enhancement of phenylephrine- and angiotensin II-mediated vasoconstriction. In conclusion, this in vivo study demonstrates that EGFR plays a key role in aldosterone-mediated vascular reactivity.

Cardiac aldosterone overexpression prevents harmful effects of diabetes in the mouse heart by preserving capillary density.

Recent reports showed an unexpected worsening of endothelial function by aldosterone antagonism in diabetic patients, suggesting that aldosterone could interfere with the detrimental consequences of diabetes on microvasculature and thus on cardiac function. To test this hypothesis, diabetes (D) was induced using streptozotocin in transgenic (Tg) male mice overexpressing aldosterone-synthase in the heart and in wild-type (Wt) mice. Eight weeks after streptozotocin injection, impairment of left ventricular systolic function, measured by echocardiography (fractional shortening), was accompanied by a decrease in capillaries/cardiomyocyte ratio (-20%) and VEGFa expression (-40%) in Wt-D mice compared with normoglycemic littermates. Furthermore, Wt-D mice demonstrated an increase in superoxide production (+100%) and protein carbonylation (+33%), hallmarks of oxidative stress. Except for a slight increase in protein carbonylation, all of these diabetes-associated cardiac alterations were undetectable in Tg-D mice. Fibrosis was induced similarly in both diabetic groups. Eplerenone (an aldosterone antagonist) abolished all of the effects of aldosterone-synthase overexpression but had no effect in Wt-D mice. Thus, aldosterone prevents systolic dysfunction through a mineralocorticoid receptor-dependent mechanism that may include preventing VEGFa down-regulation and maintaining capillary density. Understanding how aldosterone prevents VEGFa down-regulation in experimental diabetes could be important to define new strategies targeting the prevention of a decrease in capillary density.