Mineralocorticoid Receptor Deficiency in Macrophages Inhibits Neointimal Hyperplasia and Suppresses Macrophage Inflammation Through SGK1-AP1/NF-κB Pathways

Abstract

Objective-Restenosis after percutaneous coronary intervention remains to be a serious medical problem. Although mineralocorticoid receptor (MR) has been implicated as a potential target for treating restenosis, the cellular and molecular mechanisms are largely unknown. This study aims to explore the functions of macrophage MR in neointimal hyperplasia and to delineate the molecular mechanisms. Approach and Results-Myeloid MR knockout (MMRKO) mice and controls were subjected to femoral artery injury.MMRKO reduced intima area and intima/media ratio, Ki67-and BrdU-positive vascular smooth muscle cells, expression of proinflammatory molecules, and macrophage accumulation in injured arteries. MMRKO macrophages migrated less in culture. MMRKO decreased Ki67-and BrdU-positive macrophages in injured arteries. MMRKO macrophages were less Ki67-positive in culture. Conditioned media from MMRKO macrophages induced less migration, Ki67 positivity, and proinflammatory gene expression of vascular smooth muscle cells. After lipopolysaccharide treatment, MMRKO macrophages had decreased p-cFos and p-cJun compared with control macrophages, suggesting suppressed activation of activator protein-1 (AP1). Nuclear factor-κB (NF-κB) pathway was also inhibited by MMRKO, manifested by decreased p-IκB kinase-β and p-IκBα, increased IκBα expression, decreased nuclear translocation of p65 and p50, as welll as decreased phosphorylation and expression of p65. Finally, overexpression of serum-and-glucocorticoid-induciblekinase-1 (SGK1) attenuated the effects of MR deficiency in macrophages. This manuscript was sent to Kathryn Moore, Consulting Editor, for review by expert referees, editorial decision, and final disposition. *These authors contributed equally to this article. angioplasty of coronary arteries and neointima formation after stent implantation in coronary arteries of swine. 3,4 However, the effects of MR antagonists on restenosis in human patients are uncertain. Early study has shown that spironolactone, another antagonist of MR, does not change the incidence of restenosis at 6 months after stenting in a clinical trial. Conclusions-Selective5 More recent results, however, have demonstrated that spironolactone reduces the rate of repeat revascularization at 1 year after PCI.6 Different population, length of treatments, and end points between the 2 studies may have contributed to the differential results. More fundamental studies on the cellular and molecular mechanisms how MR is involved in restenosis are needed to provide new insights for ultimately using this target to treat restenosis.Recent studies using knockout mouse models have begun to reveal the cell type-specific influence of MR in the vasculature.7 MR in monocytes/macrophages may play important roles in neointimal hyperplasia. Myeloid MR knockout (MMRKO) mouse was established and used to study the functions of macrophage MR in the cardiovascular system. The data have illustrated the importance of macrophage MR in cardiac hypertrophy, fibrosis, and inflammation. [8][9][10]...

Macrophages

“…Myeloid deficiency in mineralocorticoid receptor attenuated vascular inflammation in a model of femoral artery injury and led to reduced macrophage migration, proliferation, and activation, in association with reduced activation of AP1/NF-κB pathways. 51 The results are consistent with the atheroprotective phenotype of serum-and glucocorticoid-inducible kinase-1 deficiency in Apoe −/− mice, which was also attributed to reduced NF-κB activation in macrophages. 52 NF-κB signaling is generally considered as proatherogenic, although its activation in macrophages may lead to atheroprotection in some settings.…”

Mineralocorticoid Receptor Deficiency in Macrophages Inhibits Atherosclerosis by Affecting Foam Cell Formation and Efferocytosis

“…Animal studies have shown that these antagonists inhibit atherosclerosis, whereas aldosterone, an endogenous agonist of MR, promotes atherosclerosis (8,12). Utilizing a myeloid MR knock-out (MRKO) mouse model, we and others have previously demonstrated that MR regulates macrophage polarization and inflammation and that macrophage MR is important in controlling cardiac and vascular remodeling (13)(14)(15)(16)(17). However, it has remained unknown whether macrophage MR plays a role in atherosclerosis.…”

30 YEARS OF THE MINERALOCORTICOID RECEPTOR: Mineralocorticoid receptor null mice: informing cell-type-specific roles

“…The MR in target cells can be activated by aldosterone and glucocorticoids with almost identical binding affinities; unprotected MRs thus act primarily as a high-affinity GR due to the much higher circulating and intracellular concentrations of glucocorticoids. In aldosterone target cells and tissues, specificity is afforded by the expression of the 11β-hydroxysteroid dehydrogenase type II (11β-HSD2) enzyme that efficiently metabolises Protected from DOC/salt fibrosis and hypertension, protected Rickard et al (2009) Protected from L-NAME/salt fibrosis but not hypertension Bienvenu et al (2012) Reduced macrophage recruitment in stroke and AngII/L-NAME Usher et al (2010) Fibrosis, but not hypertension; protection from atherosclerosis Frieler et al (2011), Shen et al (2016 intracellular cortisol or corticosterone to inactive steroids. The MR, in contrast to the GR, which is ubiquitously expressed, has a restricted expression pattern in mammals, and is expressed in the epithelia of organs such as the kidney, colon and salivary gland, where it primarily acts as the receptor for aldosterone to regulate fluid and electrolyte/solute homeostasis.…”

“…In an effort to determine the cellular mechanisms of MR signalling in monocytes/macrophages Usher and coworkers performed microarray on peritoneal-derived macrophages and showed MR null cells to have a gene expression pattern that overlapped with GR and PPARγ agonist activity. Shen and coworkers (2016) isolated cardiac tissue macrophages from vehicle and DOC/ salt treated mice and found that pro-inflammatory and pro-fibrotic profiles were indeed lost but the alternative activation profile was not pronounced (Shen et al 2016). Another group identified JNK signalling pathways to be MR dependent and potentially NFκB signalling (Shen et al 2016.…”

“…Shen and coworkers (2016) isolated cardiac tissue macrophages from vehicle and DOC/ salt treated mice and found that pro-inflammatory and pro-fibrotic profiles were indeed lost but the alternative activation profile was not pronounced (Shen et al 2016). Another group identified JNK signalling pathways to be MR dependent and potentially NFκB signalling (Shen et al 2016. Thus in less than a decade, there has been significant steps towards dissecting and defining the cellular mechanisms of MR signalling in the cardiovascular system.…”