Esaxerenone inhibits the macrophage-to-myofibroblast transition through mineralocorticoid receptor/TGF-β1 pathway in mice induced with aldosterone

Crosstalk between macrophages and adjacent cells in AKI to CKD transition

Acute kidney injury (AKI), triggered by ischemia, sepsis, toxicity, or obstruction, is marked by a rapid impairment of renal function and could lead to the initiation and advancement of chronic kidney disease (CKD). The concept of AKI to CKD transition has gained much interest. Despite a series of studies highlighting the diverse roles of renal macrophages in the immune response following AKI, the intricate mechanisms of macrophage-driven cell-cell communication in AKI to CKD transition remains incompletely understood. In this review, we introduce the dynamic phenotype change of macrophages under the different stages of kidney injury. Importantly, we present novel perspectives on the extensive interaction of renal macrophages with adjacent cells, including tubular epithelial cells, vascular endothelial cells, fibroblasts, and other immune cells via soluble factors, extracellular vesicles, and direct contact, to facilitate the transition from AKI to CKD. Additionally, we summarize the potential therapeutic strategies based on the adverse macrophage-neighboring cell crosstalk.

Fibroblast to macrophage-like cell transition in renal inflammatory injury through the MR/CSF1 pathway induced by aldosterone

AIMS

Inflammatory injury promotes the chronic kidney disease (CKD) progression，with renal macrophage accumulation and proliferation of as typical manifestations of inflammatory injury. We aimed to verify fibroblast to macrophage-like cell transition as a new source of macrophages that participate in renal inflammatory injury.

MATERIALS AND METHODS

Wistar rats were divided into Sham, ALD (aldosterone infusion for 12 weeks), and ESA (aldosterone infusion and esaxerenone by diet for 12 weeks) groups. Rat kidney interstitial fibroblast (RKF) were cultured, induced with aldosterone or CSF1, and treated with antagonists in vitro. The proportions of FSP-1+ F4/80+ cells in the rat kidney and RKF, including M1 marker iNOS/CD86 and M2 marker CD206/CD163 were assessed by flow cytometry and immunofluorescence staining. Single-cell RNA sequencing was used to assess the origin of macrophages in the rat kidneys and related gene expression. Additionally, immunofluorescence was used to detect FSP-1+ F4/80+ cells in kidney biopsy samples from CKD patients.

KEY FINDINGS

Fibroblast to macrophage-like cell transition was observed in both the kidneys of aldosterone-infused rats and in vitro aldosterone-treated RKF, with a predominant differentiation into the M1 phenotype. This transformation was mediated through the MR/CSF1 signalling pathway, revealing a novel source of macrophages and providing significant insights into the mechanisms underlying organ fibrosis.

SIGNIFICANCE

Aldosterone induces fibroblast to macrophage-like cell transition through the MR/ CSF1 pathway.

Proliferation of renal macrophage via MR/CSF1 pathway induced with aldosterone and inhibited by esaxerenone

Macrophage proliferation plays a critical role in kidney injury and repair, but due to their high plasticity and heterogeneity, the origins and subtypes of these proliferating cells remain unclear. This study investigates aldosterone-induced proliferation of renal macrophages, focusing on their origins, subtypes, and regulatory mechanisms using immunofluorescence, flow cytometry, and single-cell sequencing. The findings suggest that both resident and infiltrating macrophages proliferate in response to aldosterone, a significant proportion of which are renal resident macrophages, predominantly of the M1 subtype. The study also identifies the mineralocorticoid receptor/colony stimulation factor-1 (MR/CSF1) pathway as a key regulator of this process. Inhibition of this pathway through antagonists and inhibitors reduces macrophage proliferation and kidney damage, suggesting that targeting MR/CSF1 could be therapeutic against aldosterone-induced renal damage and inflammation.

Regulatory mechanisms of macrophage-myofibroblast transdifferentiation: A potential therapeutic strategy for fibrosis

Macrophage-myofibroblast transdifferentiation (MMT), a fibrotic process impacting diverse tissue types, has garnered recent scholarly interest. Within damaged tissues, the role of myofibroblasts is pivotal in the accumulation of excessive fibrous connective tissue, leading to persistent scarring or organ dysfunction. Consequently, the examination of MMT-related fibrosis is imperative. This review underscores MMT as a fundamental mechanism in myofibroblast generation during tissue fibrosis, and its exploration is crucial for elucidating the regulatory mechanisms underlying this process. Gaining insight into these mechanisms promises to facilitate the development of therapeutic approaches aimed at inhibiting and reversing fibrosis, thereby offering potential avenues for the treatment of fibrotic diseases.

Mineralocorticoid Receptor Antagonists in Heart Failure: An Update

Spironolactone, a steroidal mineralocorticoid receptor antagonist (MRA), has been used to treat patients with heart failure (HF) for more than half a century. Spironolactone improved outcomes in patients with severely symptomatic HF with reduced ejection fraction, and later, eplerenone expanded the benefits to patients with mildly symptomatic HF with reduced ejection fraction and myocardial infarction complicated by HF. Spironolactone reduced HF events in some patients with HF with preserved ejection fraction, but the results were not generalizable to all patients with HF with preserved ejection fraction. More recently, the nonsteroidal MRA finerenone improved the HF outcomes of patients with HF with preserved ejection fraction, expanding the benefits previously seen among patients with diabetes and albuminuric chronic kidney disease. The use of MRAs has been limited due to excessive concern about hyperkalemia. Education about the limited true risk associated with hyperkalemia, and about how to predict, prevent, and manage hyperkalemia, may lead to wider acceptability and use of these agents. Several ongoing trials are testing steroidal and nonsteroidal MRAs in HF populations. In this review, we perform a critical appraisal of MRA use in HF populations and point toward future directions.

Advances in macrophage-myofibroblast transformation in fibrotic diseases

Macrophage-myofibroblast transformation (MMT) has emerged as a discovery in the field of fibrotic disease research. MMT is the process by which macrophages differentiate into myofibroblasts, leading to organ fibrosis following organ damage and playing an important role in fibrosis formation and progression. Recently, many new advances have been made in studying the mechanisms of MMT occurrence in fibrotic diseases. This article reviews some critical recent findings on MMT, including the origin of MMT in myofibroblasts, the specific mechanisms by which MMT develops, and the mechanisms and effects of MMT in the kidneys, lungs, heart, retina, and other fibrosis. By summarizing the latest research related to MMT, this paper provides a theoretical basis for elucidating the mechanisms of fibrosis in various organs and developing effective therapeutic targets for fibrotic diseases.

Novel glucomannan-like polysaccharide from Lycium barbarum L. ameliorates renal fibrosis via blocking macrophage-to-myofibroblasts transition

The macrophage to myofibroblasts transition (MMT) has been reported as a newly key target in renal fibrosis. Lycium barbarum L. is a traditional Chinese medicine for improving renal function, in which its polysaccharides (LBPs) are the mainly active components. However, whether the role of LBPs in treating renal fibrosis is related to MMT process remain unclear. The purpose of this study was to explore the relationship between the regulating effect on MMT process and the anti-fibrotic effect of LBPs. Initially, small molecular weight LBPs fractions (LBP-S) were firstly isolated via Sephadex G-100 column. Then, the potent inhibitory effect of LBP-S on MMT process was revealed on bone marrow-derived macrophages (BMDM) model induced by TGF-β. Subsequently, the chemical structure of LBP-S was elucidated through monosaccharide, methylation and NMR spectrum analysis. In vivo biodistribution characteristics studies demonstrated that LBP-S exhibited effectively accumulation in kidney via intraperitoneal administration. Finally, LBP-S showed a satisfactory anti-renal fibrotic effect on unilateral ureteral obstruction operation (UUO) mice, which was significantly reduced following macrophage depletion. Overall, our findings indicated that LPB-S could alleviate renal fibrosis through regulating MMT process and providing new candidate agents for chronic kidney disease (CKD) related fibrosis treatment.

Esaxerenone Attenuates Aldosterone-Induced Mitochondrial Damage-Mediated Pyroptosis in Mouse Aorta and Rat Vascular Smooth Muscle Cells

BACKGROUND

Vascular smooth muscle cell (VSMC) injury caused by the inflammatory response plays a key role in cardiovascular disease (CVD), and the vasoprotective effects of mineralocorticoid receptor blockers (MRBs) support the role of mineralocorticoid receptor (MR) activation.

METHODS

C57BL/6 mice and VSMCs isolated from rats were treated with aldosterone and esaxerenone. Caspase-1, GSDMD-N, IL-1β, and NR3C2 expression and DNA damage in aortic VSMCs were detected using immunohistochemistry, Western blotting, and TUNEL staining. Mitochondrial changes were detected by transmission electron microscopy (TEM). Reactive oxygen species (ROS), MitoTracker, JC-I, mitochondrial respiratory chain complexes I-V, and NR3C2 were detected using immunofluorescence and flow cytometry. Pyroptosis was detected with scanning electron microscopy (SEM).

RESULTS

After aldosterone treatment, the number of TUNEL-positive cells increased significantly, and the expression of caspase-1, GSDMD-N, and IL-1β increased. TEM revealed mitochondrial damage, and SEM revealed specific pyroptotic changes, such as cell membrane pore changes and cytoplasmic extravasation. Increased ROS levels and nuclear translocation of NR3C2 were also observed. These pyroptosis-related changes were reversed by esaxerenone.

CONCLUSIONS

Aldosterone activates the MR and mediates mitochondrial damage, thereby inducing pyroptosis in VSMCs via the NLRP3/caspase-1 pathway. Esaxerenone inhibits MR activation and reduces mitochondrial damage and oxidative stress, thereby inhibiting pyroptosis.

Exploring unconventional targets in myofibroblast transdifferentiation outside classical TGF-β signaling in renal fibrosis

We propose that the key initiators of renal fibrosis are myofibroblasts which originate from four predominant sources-fibroblasts, pericytes, endothelial cells and macrophages. Increased accumulation of renal interstitial myofibroblasts correlates with an increase in collagen, fibrillar proteins, and fibrosis severity. The canonical TGF-β pathway, signaling via Smad proteins, is the central molecular hub that initiates these cellular transformations. However, directly targeting these classical pathway molecules has proven challenging due their integral roles in metabolic process, and/or non-sustainable effects involving compensatory cross-talk with TGF-β. This review explores recently discovered alternative molecular targets that drive transdifferentiation into myofibroblasts. Discovering targets outside of the classical TGF-β/Smad pathway is crucial for advancing antifibrotic therapies, and strategically targeting the development of myofibroblasts offers a promising approach to control excessive extracellular matrix deposition and impede fibrosis progression.

Eplerenone reduces lymphangiogenesis in the contralateral kidneys of UUO rats

Inflammation and fibrosis often occur in the kidney after acute injury, resulting in chronic kidney disease and consequent renal failure. Recent studies have indicated that lymphangiogenesis can drive renal inflammation and fibrosis in injured kidneys. However, whether and how this pathogenesis affects the contralateral kidney remain largely unknown. In our study, we uncovered a mechanism by which the contralateral kidney responded to injury. We found that the activation of mineralocorticoid receptors and the increase in vascular endothelial growth factor C in the contralateral kidney after unilateral ureteral obstruction could promote lymphangiogenesis. Furthermore, mineralocorticoid receptor activation in lymphatic endothelial cells resulted in the secretion of myofibroblast markers, thereby contributing to renal fibrosis. We observed that this process could be attenuated by administering the mineralocorticoid receptor blocker eplerenone, which, prevented the development of fibrotic injury in the contralateral kidneys of rats with unilateral ureteral obstruction. These findings offer valuable insights into the intricate mechanisms underlying kidney injury and may have implications for the development of therapeutic strategies to mitigate renal fibrosis in the context of kidney disease.

The role of a novel mineralocorticoid receptor antagonist, finerenone, in chronic kidney disease: mechanisms and clinical advances

BACKGROUND

Chronic kidney disease (CKD) poses a significant health risk in contemporary society. Current CKD treatments primarily involve renin-angiotensin-aldosterone system inhibitors and mineralocorticoid receptor antagonists, albeit associated with hyperkalemia risks. A novel selective mineralocorticoid receptor antagonist, finerenone, offers a promising, safer alternative for CKD therapy. This review comprehensively assesses the role and efficacy of finerenone in CKD treatment by analyzing clinical and animal studies. Emerging evidence consistently supports finerenone's ability to effectively slow the progression of CKD. By targeting the mineralocorticoid receptor, finerenone not only mitigates renal damage but also exhibits a favorable safety profile, minimizing hyperkalemia concerns.

CONCLUSION

Finerenone emerges as a valuable addition to CKD therapy, demonstrating potential benefits in delaying CKD progression while minimizing side effects. Nevertheless, further clinical trials are necessary to provide a comprehensive understanding of its safety and efficacy.

Esaxerenone Inhibits Renal Angiogenesis and Endothelial-Mesenchymal Transition via the VEGFA and TGF-β1 Pathways in Aldosterone-Infused Mice

Renal fibrosis is an inevitable process in the progression of chronic kidney disease (CKD). Angiogenesis plays an important role in this process. Vascular endothelial cells are involved in renal fibrosis by phenotypic transformation and secretion of extracellular matrix. Aldosterone stimulates mineralocorticoid receptor (MR) activation and induces inflammation, which is important for angiogenesis. Clinically, MR blockers (MRBs) have a protective effect on damaged kidneys, which may be associated with inhibition of angiogenesis. In this study, we used aldosterone-infused mice and found that aldosterone induced angiogenesis and that endothelial-mesenchymal transition (EndMT) in neovascular endothelial cells was involved in renal fibrosis. Notably, aldosterone induced inflammation and stimulated macrophages to secrete vascular endothelial growth factor (VEGF) A to regulate angiogenesis by activating MR, whereas EndMT occurred in response to transforming growth factor-β1 (TGF-β1) induction and participated in renal fibrosis. These effects were antagonized by the MRB esaxerenone. These findings suggest that reducing angiogenesis may be an effective strategy for treating renal fibrosis.

Recent progress in the diagnosis and treatment of primary aldosteronism

Primary aldosteronism (PA) is caused by excessive secretion of aldosterone from the adrenal glands, with subsequent changes in the renin-angiotensin system. In Japan, chemiluminescent enzyme immunoassay is currently performed for aldosterone assay rather than the earlier method of radioimmunoassay. This change in aldosterone measurement methods has resulted in faster and more accurate measurement of blood aldosterone levels. Since 2019, esaxerenone, a mineralocorticoid receptor antagonist (MRA) with a non-steroidal skeleton, has been available in Japan for the treatment of hypertension. Esaxerenone has been reported to have various effects, such as strong antihypertensive and anti-albuminuric/proteinuric effects. Treatment of PA with MRAs has been reported to improve the patient's quality of life and to suppress the onset of cardiovascular events independent of their effects on blood pressure. Measuring renin levels is recommended for monitoring the extent of mineralocorticoid receptor blockade during MRA treatment. Patients receiving MRAs are prone to developing hyperkalemia, and combining MRAs with sodium/glucose cotransporter 2 inhibitors is expected to prevent severe hyperkalemia and provide additional cardiorenal protection. Mineralocorticoid receptor-associated hypertension is a broad concept of hypertension that includes not only PA, but also hypertension caused by borderline aldosteronism, obesity, diabetes, and sleep apnea syndrome. New findings on primary aldosteronism, which is part of MR-associated hypertension. Aldosterone measurements have been changed to the CLEIA method. Treatment of primary aldosteronism with MRAs has a variety of positive effects. CT-guided radiofrequency ablation and transarterial embolization are alternatives to surgery for aldosterone-producing adenomas. BP blood pressure, CLEIA chemiluminescent enzyme immunoassay, CT computed tomography, K serum potassium, MR mineralocorticoid receptor, MRA mineralocorticoid receptor antagonist, QOL quality of life, SGLT2i sodium/glucose cotransporter 2 inhibitor.

Single-cell sequencing reveals homogeneity and heterogeneity of the cytopathological mechanisms in different etiology-induced AKI

Homogeneity and heterogeneity of the cytopathological mechanisms in different etiology-induced acute kidney injury (AKI) are poorly understood. Here, we performed single-cell sequencing (scRNA) on mouse kidneys with five common AKI etiologies (CP-Cisplatin, IRI-Ischemia-reperfusion injury, UUO-Unilateral ureteral obstruction, FA-Folic acid, and SO-Sodium oxalate). We constructed a potent multi-model AKI scRNA atlas containing 20 celltypes with 80,689 high-quality cells. The data suggest that compared to IRI and CP-AKI, FA- and SO-AKI exhibit injury characteristics more similar to UUO-AKI, which may due to tiny crystal-induced intrarenal obstruction. Through scRNA atlas, 7 different functional proximal tubular cell (PTC) subtypes were identified, we found that Maladaptive PTCs and classical Havcr1 PTCs but not novel Krt20 PTCs affect the pro-inflammatory and pro-fibrotic levels in different AKI models. And cell death and cytoskeletal remodeling events are widespread patterns of injury in PTCs. Moreover, we found that programmed cell death predominated in PTCs, whereas apoptosis and autophagy prevailed in the remaining renal tubules. We also identified S100a6 as a novel AKI-endothelial injury biomarker. Furthermore, we revealed that the dynamic and active immune (especially Arg1 Macro_2 cells) -parenchymal cell interactions are important features of AKI. Taken together, our study provides a potent resource for understanding the pathogenesis of AKI and early intervention in AKI progression at single-cell resolution.

Eplerenone inhibits the macrophage-to-myofibroblast transition in rats with UUO-induced type 4 cardiorenal syndrome through the MR/CTGF pathway

Cardiovascular complications are the leading causes of death in patients with chronic kidney disease (CKD), accounting for approximately 50% of deaths. Despite significant advances in the understanding of cardiac disease due to CKD, the underlying mechanisms involved in many pathological changes have not been fully elucidated. In our previous study, we observed severe fibrosis in the contralateral kidney of a 6-month-old rat UUO model. In the present experiment, we also observed severe fibrosis in the hearts of rats subjected to UUO and the macrophage-to-myofibroblast transition (MMT). These effects were inhibited by the mineralocorticoid receptor (MR) blocker eplerenone. Notably, in vitro, aldosterone-activated MR induced the MMT and subsequently promoted the secretion of CTGF, the target of MR, from macrophages; these changes were inhibited by eplerenone. The CTGF also induced the MMT and both the aldosterone and CTGF-induced MMT could be alleviated by the CTGF blocker. In conclusion, our results suggest that targeting the MR/CTGF pathway to inhibit the MMT may be an effective therapeutic strategy for the treatment of cardiac fibrosis.