A major deleterious side effect of glucocorticoids is skin atrophy. Glucocorticoids activate the glucocorticoid and the mineralocorticoid (MR) receptor, both present in the epidermis. We hypothesized that glucocorticoid-induced epidermal atrophy may be related to inappropriate occupancy of MR by glucocorticoids. We evaluated whether epidermal atrophy induced by the topical glucocorticoid clobetasol could be limited by coadministration of MR antagonist. In cultured human skin explants, the epidermal atrophy induced by clobetasol was significantly limited by MR antagonism (canrenoate and eplerenone). Blockade of the epithelial sodium channel ENaC by phenamil was also efficient, identifying a role of MR-ENaC cascade in keratinocytes, acting through restoration of clobetasol-induced impairment of keratinocyte proliferation. In the SPIREPI randomized double-blind controlled trial, gels containing clobetasol, the MR antagonist spironolactone, both agents, or placebo were applied on four zones of the forearms of 23 healthy volunteers for 28 days. Primary outcome was histological thickness of the epidermis with clobetasol alone or clobetasol+spironolactone. Spironolactone alone did not affect the epidermal thickness but coapplication of clobetasol and spironolactone significantly limited clobetasol-induced atrophy and was well tolerated. Altogether, these findings identify MR as a factor regulating epidermal homeostasis and suggest that topical MR blockade could limit glucocorticoid-induced epidermal atrophy.

Abstract-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 mineralocorticoiddependent injury in the cardiovascular system in mice. (Aldo) is a main regulator of renal sodium reabsorption, with an overall effect on volemia and blood pressure. Aldo binds to the mineralocorticoid receptor (MR), a transcription factor of the nuclear receptor family present in the kidney.1 Extrarenal pathophysiological effects of this hormone have been characterized, extending its actions to the CV system, the brain, the adipose tissue, the skin, and the eye.2-5 Inappropriate MR activation has been shown to promote cardiac fibrosis in experimental models 6,7 The Randomized Aldactone Evaluation Study, 8 Eplerenone Post-Acute Myocardial Infarction Heart Failure Efficacy and Survival Study, 9 and Eplerenone in Mild Patients Hospitalization and Survival Study in Heart Failure 10 clinical trials have demonstrated that the addition of the MR antagonists spironolactone or eplerenone to standard care markedly reduced the overall and CV mortality in patients with left ventricular systolic dysfunction and mild or severe symptoms of chronic heart failure (HF) or with HF signs after acute myocardial infarction.The molecular mechanisms of Aldo and MR activation in the CV system are not yet fully established. A better understanding of these mechanisms may unveil novel biotargets for pharmacological modulation of the signaling cascades induced by mineralocorticoids in CV diseases.In this study we identified neutrophil gelatinase-associated lipocalin (NGAL) in a pan-genomic transcriptomic analysis performed on hearts of transgenic mice that overexpress the MR in cardiomyocytes. NGAL (lipocalin 2 or 24p3) is a 25-kDa glycoprotein belonging to the lipocalin superfamily.11,12 The cell-specific roles of NGAL remain elusive, but enhanced NGAL in tissues, plasma, or urine has been reported in several pathological states, such as kidney failure 13 and obesity, 14,15 and many other situations. Increased systemic and myocardial expressions of NGAL have been observed in clinical and experimental HF. 16,17 Hormona...