MRAについて241120 ｜ざいつ内科クリニック｜山口市小郡の一般内科、血液内科、アレルギー科

MRAについて241120

MRA（ミネラルコルチコイド受容体拮抗薬）は、アルドステロンの働きを抑えることで血圧を下げ、心臓や腎臓を保護する薬です。

ミネラルコルチコイド受容体（MR）は、さまざまな組織や細胞に存在し、特に以下のような場所で見られます：

腎臓: 主に遠位尿細管と集合管の細胞に存在し、ナトリウムと水の再吸収を調節します。
心臓: 心筋細胞に存在し、心血管系の機能に影響を与えます。
大腸: 上皮細胞に存在し、電解質のバランスを維持します。
脳: 特に海馬や視床下部の神経細胞に存在し、神経機能に影響を与えます。
汗腺: 汗腺の細胞に存在し、汗の分泌を調節します。
脂肪組織: 脂肪細胞に存在し、脂肪の代謝に関与します。
血管内皮細胞: 血管の内皮細胞に存在し、血圧の調節に関与します。
唾液腺: 唾液腺の細胞に存在し、唾液の分泌を調節します。
皮膚: 皮膚の細胞に存在し、皮膚のバリア機能に関与します。
免疫細胞: 特定の免疫細胞に存在し、免疫応答に影響を与えます。

これらの組織や細胞におけるミネラルコルチコイド受容体の存在は、体内の電解質バランスや血圧の調節、代謝、免疫応答など、さまざまな生理機能に重要な役割を果たしています。

	MRAの作用
アルドステロンの働き	尿細管などにおけるアルドステロンの働きを阻害し、血圧を下げる
心臓の働き	心臓の肥大などに関わるアルドステロンの働きを抑える
腎臓の働き	腎臓の尿細管（主に集合管）のミネラルコルチコイド受容体（MR）に作用し、ナトリウムの再吸収およびカリウムの排泄を抑制する

MRAは、高血圧症や慢性心不全の治療に用いられます。また、心血管・腎障害の発症や進展を抑制する効果も期待できます。

MRAには、スピロノラクトン（アルダクトンA）、エプレレノン（セララ）、エサキセレノン（ミネブロ）、フィネレノン（ケレンディア）などがあります。

MRAの副作用には、血中カリウム値が上昇する、胸が張るなどの症状があります。定期的に血清カリウム値を測定することが重要です

It was also shown that the adipocyte-derived hormone leptin is a new direct regulator of aldosterone secretion and that leptin-mediated aldosterone production is a major contributor to obesity-associated hypertension in women

Vascular dysfunction and impaired endothelial mediated relaxation are powerful underlying abnormalities in the pathogenesis of hypertension, coronary heart disease, and stroke. Obesity, type 2 diabetes mellitus, and other metabolic abnormalities are associated with activation of mineralocorticoid receptor (MRs) in the vasculature and adipose tissue. While MR signaling is involved in the normal physiological differentiation and maturation of adipocyte, enhanced activation of MRs also contributes to increase oxidative stress, release of pro-inflammatory adipokines, and dysregulation of adipocyte autophagy. This, in turn, increases the maladaptive expansion of subcutaneous, visceral and perivascular adipose tissue, resulting in systemic and cardiovascular (CV) insulin resistance and increased CV stiffness and impaired vascular and cardiac relaxation. This review summarizes the normal role of MR activation in adipose tissues and explores the mechanisms by which excessive MR activation mediates adipose tissue inflammation and vascular dysfunction. Potential preventative and therapeutic strategies directed in the prevention of MR activation and CV disease are also discussed.

Crosstalk between adipose tissue and blood vessels is vital to vascular homeostasis and is disturbed in cardiovascular and metabolic diseases such as hypertension, diabetes and obesity. Cardiometabolic syndrome (CMS) refers to the clustering of obesity-related metabolic disorders such as insulin resistance, glucose and lipid profile alterations, hypertension and cardiovascular diseases. Mechanisms underlying these associations remain unclear. Adipose tissue associated with the vasculature [known as perivascular adipose tissue (PVAT)] has been shown to produce myriads of adipose tissue-derived substances called adipokines, including hormones, cytokines and reactive oxygen species (ROS), which actively participate in the regulation of vascular function and local inflammation by endocrine and/or paracrine mechanisms. As a result, the signaling from PVAT to the vasculature is emerging as a potential therapeutic target for obesity and diabetes-related vascular dysfunction. Accumulating evidence supports a shift in our understanding of the crucial role of elevated plasma levels of aldosterone in obesity, promoting insulin resistance and hypertension. In obesity, aldosterone/mineralocorticoid receptor (MR) signaling induces an abnormal secretion of adipokines, ROS production and systemic inflammation, which in turn contribute to impaired insulin signaling, reduced endothelial-mediated vasorelaxation, and associated cardiovascular abnormalities. Thus, aldosterone excess exerts detrimental metabolic and vascular effects that participate to the development of the CMS and its associated cardiovascular abnormalities. In this review, we focus on the physiopathological roles of corticosteroid receptors in the interplay between PVAT and the vasculature, which underlies their potential as key regulators of vascular function.

The perivascular adipose tissue (PVAT) is now recognized as an active contributor to vascular function. Adipocytes and stromal cells contained within PVAT are a source of an ever-growing list of molecules with varied paracrine effects on the underlying smooth muscle and endothelial cells, including adipokines, cytokines, reactive oxygen species, and gaseous compounds. Their secretion is regulated by systemic or local cues and modulates complex processes, including vascular contraction and relaxation, smooth muscle cell proliferation and migration, and vascular inflammation. Recent evidence demonstrates that metabolic and cardiovascular diseases alter the morphological and secretory characteristics of PVAT, with notable consequences. In obesity and diabetes, the expanded PVAT contributes to vascular insulin resistance. PVAT-derived cytokines may influence key steps of atherogenesis. The physiological anticontractile effect of PVAT is severely diminished in hypertension. Above all, a common denominator of the PVAT dysfunction in all these conditions is the immune cell infiltration, which triggers the subsequent inflammation, oxidative stress, and hypoxic processes to promote vascular dysfunction. In this review, we discuss the currently known mechanisms by which the PVAT influences blood vessel function. The important discoveries in the study of PVAT that have been made in recent years need to be further advanced, to identify the mechanisms of the anticontractile effects of PVAT, to explore the vascular-bed and species differences in PVAT function, to understand the regulation of PVAT secretion of mediators, and finally, to uncover ways to ameliorate cardiovascular disease by targeting therapeutic approaches to PVAT.

PVAT (perivascular adipose tissue) has recently been recognized as a novel factor in vascular biology, with implications in the pathophysiology of cardiovascular disease. Composed mainly of adipocytes, PVAT releases a wide range of biologically active molecules that modulate vascular smooth muscle cell contraction, proliferation and migration. PVAT exerts an anti-contractile effect in various vascular beds which seems to be mediated by an as yet elusive PVRF [PVAT-derived relaxing factor(s)]. Considerable progress has been made on deciphering the nature and mechanisms of action of PVRF, and the PVRFs proposed until now are reviewed here. However, complex pathways seem to regulate PVAT function and more than one mechanism is probably responsible for PVAT actions in vascular biology. The present review describes our current knowledge on the structure and function of PVAT, with a focus on its role in modulating vascular tone. Potential involvements of PVAT dysfunction in obesity, hypertension and atherosclerosis will be highlighted.

. 2015 Aug;64(8):603-14.

doi: 10.1007/s00011-015-0838-5. Epub 2015 Jun 14.

Crosstalk between ppar gamma and MR in TNFa activated renal tubular cell

Abstract

Introduction: In our previous study, we observed the crosstalk between peroxisome proliferator-activated receptor-γ (PPAR-γ) and angiotensin II in activated renal tubular cells. The present study is aimed to further explore the crosstalk between PPAR-γ and mineralocorticoid receptor (MR) in tumor necrosis factor (TNF)-α activated renal tubular cells.

Methods: Human proximal renal tubular epithelial cells HK-2 were cultured with the pre-treatment of PPAR-γ agonist, pioglitazone (5 μM), MR antagonist, eplerenone (5 μM), or their combined treatment, followed by activation with TNF-α (20 ng/ml). In the parallel experiment, PPAR-γ inhibitor GW9662 (25 µM) was used to study the independence of PPAR-γ. Gene expression and protein synthesis of intercellular adhesion molecule-1 (ICAM-1), interleukin-6 (IL-6), MR and PPAR-γ were measured by RT-PCR, ELISA and Western blot, respectively; nuclear factor κB (NF-κB) nuclear translocation activity in the nucleus was examined by EMSA assay.

Results: TNF-α effectively activated HK-2 cells by up-regulating gene expression and protein synthesis of ICAM-1, IL-6 and MR and down-regulating PPAR-γ in a dose-dependent manner. TNF-α also significantly induced NF-κB nuclear translocation in HK-2 cells. Dual treatment of pioglitazone and eplerenone demonstrated synergistic effect on reducing ICAM-1 and IL-6 expression and alleviating NF-κB activation when compared with their monotherapies in TNF-α activated renal tubular cells. PPAR-γ antagonist, GW9662, significantly attenuated protective effect on ICAM-1, IL-6 and PPAR-γ expression by pioglitazone, eplerenone and their combined treatment.

Conclusions: Our data suggest that pioglitazone, in a PPAR-γ-dependent manner, trans-represses MR signaling by suppressing NF-κB activation. MR antagonist also restored PPAR-γ expression. Dual treatment of pioglitazone and eplerenone present better efficacy in attenuating excessive inflammatory response in activated renal tubular cells under stimulation of TNF-α than single treatment.

. 2008 Feb;89(2):311-7.

doi: 10.1016/j.fertnstert.2007.03.061. Epub 2007 Jun 6.

PPARg ligand reduced TNFa induced IL8 production and growth in endometriotic stromal cell

Abstract

Objective: To evaluate the influence of peroxisome proliferator-activated receptor-gamma (PPAR gamma) ligand (pioglitazone) on tumor necrosis factor-alpha (TNF-alpha)-induced interleukin-8 (IL-8) expression in endometriotic stromal cells (ESCs) and on proliferation of ESCs.

Design: Prospective study.

Setting: Department of Obstetrics and Gynecology, Tottori University Hospital, Yonago, Japan.

Patient(s): Twenty-seven patients who underwent laparoscopic surgery.

Intervention(s): The ESCs were obtained from the chocolate cyst linings of ovaries.

Main outcome measure(s): The expression of PPAR gamma gene and protein was determined by reverse transcriptase-polymerase chain reaction (RT-PCR) and immunocytochemistry. We determined the effect of pioglitazone on the production of TNF-alpha-induced IL-8 protein in culture supernatant of ESCs using ELISA. The effect of pioglitazone on TNF-alpha-induced proliferation of ESCs was evaluated by 5-bromo-2'-deoxyuridine proliferation assay. The activation of nuclear factor (NF)-kappaB in ESCs was evaluated by Western blot analyses and NF-kappaB transcription factor assays.

Result(s): Immunocytochemistry and RT-PCR revealed the expression of PPAR gamma gene and protein in ESCs. The PPAR gamma protein was predominantly located in the cell nucleus. Measurement of IL-8 protein by ELISA showed that adding TNF-alpha (100 pg/mL) significantly increased IL-8 protein. Treating ESCs with 0.1-10 microM of pioglitazone significantly reduced the TNF-alpha-induced IL-8 production. The presence of 0.1-10 microM of pioglitazone significantly suppressed growth of ESCs. The TNF-alpha increased the expression of phosphorylation of inhibitor kappaB (I kappaB). Adding pioglitazone (10 microM) did not influence the expression of phosphorylated inhibitor kappaB (I kappaB). The TNF-alpha markedly increased the intranuclear concentration of p65, and adding pioglitazone (10 microM) significantly reduced the concentration of p65.

Conclusion(s): The present study demonstrates for the first time that PPAR gamma is expressed in ESCs, and that pioglitazone reduced IL-8 secretion and the proliferation of ESCs. The PPAR gamma ligand may be an attractive therapeutic agent for endometriosis.

Mineralocorticoid receptor (MR) has been recently identified in adipose tissue, where its excessive activation contributes to several metabolic derangements often observed in obesity and metabolic syndrome. Recent findings support the existence of a bidirectional cross-talk between adipose tissue and adrenal glands, contributing to obesity-related hyperaldosteronism and subsequent adipocyte MR excessive activation. In this regard, MR pharmacological blockade has led to prevention of weight gain and metabolic benefits in murine models of genetic or diet-induced obesity. However, there is still a lack of knowledge on the potential metabolic effects of MR antagonists in clinical settings. Hence, larger clinical studies are deemed necessary to clarify the role of MR antagonism in obesity and metabolic syndrome in humans.

The mineralocorticoid receptor (MR) controls adipocyte function, but its role in the conversion of white adipose tissue (WAT) into thermogenic fat has not been elucidated. We investigated responses to the MR antagonists spironolactone (spiro; 20 mg/kg/d) and drospirenone (DRSP; 6 mg/kg/d) in C57BL/6 mice fed a high-fat (HF) diet for 90 d. DRSP and spiro curbed HF diet-induced impairment in glucose tolerance, and prevented body weight gain and white fat expansion. Notably, either MR antagonist induced up-regulation of brown adipocyte-specific transcripts and markedly increased protein levels of uncoupling protein 1 (UCP1) in visceral and inguinal fat depots when compared with the HF diet group. Positron emission tomography and magnetic resonance spectroscopy confirmed acquisition of brown fat features in WAT. Interestingly, MR antagonists markedly reduced the autophagic rate both in murine preadipocytes in vitro (10(-5) M) and in WAT depots in vivo, with a concomitant increase in UCP1 protein expression. Moreover, the autophagy repressor bafilomycin A1 (10(-8) M) mimicked the effect of MR antagonists, increasing UCP1 protein expression in primary preadipocytes. Hence, we showed that adipocyte MR regulates brown remodeling of WAT through a modulation of autophagy. These results provide a rationale for the use of MR antagonists to prevent the adverse metabolic consequences of adipocyte dysfunction.

Keywords: UCP1; adipogenesis; aldosterone; metabolic syndrome; obesity; uncoupling protein 1.

Background: We have previously shown that antagonism of the mineralocorticoid receptor (MR) results in a potent antiadipogenic activity, in vitro and in vivo. Excessive glucocorticoid exposure is associated with obesity and related disorders in humans and mice.

Methods: In this study, responses to a novel combined glucocorticoid receptor (GR)/MR antagonist were investigated in a model of diet-induced obesity. Female 10-week-old C57BL/6J mice were fed with normal chow or a high-fat diet (HFD) for 9 weeks. Mice fed a HFD were concomitantly treated for 9 weeks with the GR antagonist mifepristone (80 mg kg(-1) per day) or the novel combined GR/MR antagonist CORT118335 (80 mg kg(-1) per day). Male, juvenile 6-week-old C57BL/6J mice fed HFD were treated with CORT118335 for 4 weeks.

Results: Mice fed a HFD showed a significant increase in total body weight and white fat mass, with impaired glucose tolerance and increased fat infiltration in livers. Interestingly, only CORT118335 completely prevented the HFD-induced weight gain and white fat deposition, whereas mifepristone showed no effect on body weight and modestly increased subcutaneous fat mass. Importantly, food intake was not affected by either treatment, and CORT118335 dramatically increased PGC-1α protein expression in adipose tissue, without any effect on UCP1. Both CORT118335 and mifepristone produced metabolic benefit, improving glucose tolerance, increasing adiponectin plasma levels, decreasing leptin and reducing mean adipocyte size. When tested in vitro, CORT118335 markedly reduced 3T3-L1 differentiation and reversed MR-mediated pro-adipogenic effects of aldosterone; differently, GR-mediated effects of dexamethasone were not antagonized by CORT118335, suggesting that it mostly acts as an antagonist of MR in cultured preadipocytes.

Conclusions: Combined GR/MR pharmacological antagonism markedly reduced HFD-driven weight gain and fat mass expansion in mice through the increase in adipose PGC-1α, suggesting that both receptors represent strategic therapeutic targets to fight obesity. The effects of CORT118335 in adipocytes seem predominantly mediated by MR antagonism.

2024年11月19日 | カテゴリー：循環器, 動脈硬化症, 慢性腎臓病, 慢性腎臓病、心不全 |