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.

Esaxerenone Inhibits Interferon-γ Induced Pyroptosis of Macrophages in the Lungs of Aldosterone-treated Mice.

Lung immune cells such as lymphocytes and macrophages can induce an inflammatory response due to the activation of mineralocorticoid receptor (MR), which is manifested by the infiltration of inflammatory cells and the secretion of inflammatory cytokines and subsequent apoptosis, pyroptosis and necrosis of intrinsic lung cells and immune cells. Macrophages are immune cells that are abundant in the lung and act as the first line of defense against pathogens but are also aggravating factors of infection. The activation of the renin-angiotensin-aldosterone system (RAAS), especially aldosterone-stimulated MR activation, can induce macrophage and CD8+ T cell aggregation and the secretion of cytokines such as tumor necrosis factor-α (TNF-α) and interferon-gamma (IFN-γ). Increased IFN-γ secretion can induce macrophage pyroptosis and the release of interleukin 1-ß (IL-1ß), aggravating lung injury. In this study, lung injury in C57BL/6 mice was induced by subcutaneous micro-osmotic pump infusion of aldosterone. After 12 weeks of administration, the kidney, heart, blood vessels and lungs all showed obvious inflammatory injury, which manifested as rapid accumulation of macrophages. The overexpression of IFN-γ in the lungs of aldosterone-treated mice and the stimulation of MH-S and RAW264.7 alveolar macrophages (AMs) with aldosterone in vitro showed that IFN-γ induced pyroptosis of macrophages via the activation of the inflammasome, and the MR blocker esaxerenone effectively inhibited this effect and alleviated lung injury. In addition, IFN-γ secreted by CD8+ T cells is associated with macrophage pyroptosis. In conclusion, the inhibition of macrophage pyroptosis can effectively alleviate lung injury.

Exploratory study on the relationship between urinary sodium/potassium ratio, salt intake, and the antihypertensive effect of esaxerenone: the ENaK Study.

Excessive salt intake is one of the causes of hypertension, and reducing salt intake is important for managing the risk of hypertension and subsequent cardiovascular events. Esaxerenone, a mineralocorticoid receptor blocker, has the potential to exert an antihypertensive effect in hypertensive patients with excessive salt intake, but evidence is still lacking, especially in clinical settings. We aimed to determine if baseline sodium/potassium ratio and baseline estimated 24-h urinary sodium excretion can predict the antihypertensive effect of esaxerenone in patients with essential hypertension inadequately controlled with an angiotensin receptor blocker (ARB) or a calcium channel blocker (CCB). This was an exploratory, open-label, interventional study with a 4-week observation period and a 12-week treatment period. Esaxerenone was orally administered once daily in accordance with the Japanese package insert. In total, 126 patients met the eligibility criteria and were enrolled (ARB subcohort, 67; CCB subcohort, 59); all were included in the full analysis set (FAS) and safety analysis. In the FAS, morning home systolic blood pressure (SBP)/diastolic blood pressure (DBP) significantly decreased from baseline to end of treatment (primary efficacy endpoint) (-11.9 ± 10.9/ - 6.4 ± 6.8 mmHg, both p < 0.001); a similar trend was observed in both subcohorts. Significant reductions were also shown in bedtime home and office SBP/DBP (all p < 0.001). Each BP change was consistent regardless of the urinary sodium/potassium ratio or estimated 24-h urinary sodium excretion at baseline. The urinary albumin-creatinine ratio (UACR) and N-terminal pro-brain natriuretic peptide (NT-proBNP) significantly decreased from baseline to Week 12 in the total population and both subcohorts. No new safety concerns were raised. Esaxerenone significantly decreased morning home, bedtime home, and office BP; UACR; and NT-proBNP in this patient population, regardless of concomitant ARB or CCB use. The antihypertensive effect of esaxerenone was independent of the urinary sodium/potassium ratio and estimated 24-h urinary sodium excretion at baseline.

Development of a plasma maltose assay method as a screening test for upper gastrointestinal disorders.

BACKGROUND AND OBJECTIVE: The disaccharide loading test is a method to assess gastric mucosal damage. Since Trelan-G75, which is used for the sugar tolerance test, contains disaccharide maltose, if maltose is detected at a high sensitivity in the sample blood used in the sugar tolerance test, screening for upper gastrointestinal mucosal damage can be made simultaneously with the sugar tolerance test for the diagnosis of diabetes. METHODS: Glucose-6-phosphate is generated by treating maltose with maltose phosphorylase, ß-phosphoglucomutase, and glucose-1,6-bisphosphate. Then, change in the absorbance at 405 nm is measured by the enzymatic cycling method using Thio-NADP, ß-NADPH, and Glucose-6-phosphate dehydrogenase. After evaluating the optimal condition for this method, it is mounted on an automatic biochemical analyzer, and samples after the sugar tolerance test were assayed. RESULTS: Regarding the performance of this method, the repeatability was 10-50 µmol/L with a CV of ≤1.1%. Concerning the assay range, a curve passing the origin with a range of linearity up to 120 µmol/L was obtained. No effect of dyes or sugars in the blood was noted. As a result of application to patients with gastric mucosal disorders (those who had a health checkup), significant differences were observed depending on the stage of atrophic gastritis. DISCUSSION: This method has a high sensitivity and a high precision and can be used for high-speed analysis on an automatic analyzer. It has the potential to be used as a screening test for gastric mucosal damage.

Rationale and design of a multicenter randomized study comparing the efficacy and safety of esaxerenone versus trichlormethiazide in patients with uncontrolled essential hypertension: EXCITE-HT study.

The next-generation mineralocorticoid receptor blocker (MRB) esaxerenone has favorable antihypertensive effects in patients who do not respond to treatment with first-line antihypertensive agents and may be beneficial as a second-line treatment. However, MRBs are currently considered a fourth-line treatment as there is no clinical evidence comparing the efficacy of esaxerenone with other classes of antihypertensive agents. The multicenter, randomized, open-label, parallel-group EXCITE-HT study will evaluate the efficacy and safety of esaxerenone as a second-line agent in the treatment of Japanese patients with uncontrolled essential hypertension. After a 4-week run-in period, patients will receive either esaxerenone or trichlormethiazide for 12 weeks per the package insert and the Japanese Society of Hypertension Guidelines for the Management of Hypertension. At Weeks 4 and 8, the dose of esaxerenone or trichlormethiazide may be increased. Blood pressure (home [morning and bedtime] and office), serum biomarkers, and urinary biomarkers will be measured. The primary efficacy endpoint is the change from baseline in morning home systolic blood pressure/diastolic blood pressure to the end of treatment. The EXCITE-HT study is expected to validate the non-inferiority of esaxerenone to trichlormethiazide and provide the first evidence for the early use of esaxerenone as a second-line agent in the treatment of Japanese patients with uncontrolled essential hypertension instead of its current use as a fourth-line agent.

Sex differences in the evaluation of proteinuria using the urine dipstick test.

Background: The urine protein dipstick test is widely used, but false-positive and false-negative results may occur. This study aimed to compare the urine protein dipstick test with a urine protein quantification method. Methods: The data were extracted using the Abbott Diagnostic Support System, which analyzes the inspection results using multiple parameters. This study included 41,058 specimens tested using the urine dipstick test and protein creatinine ratio from patients aged ≥18 years. The proteinuria creatinine ratio was classified according to the Kidney Disease Outcomes Quality Initiative guidelines. Results: Urine protein on the dipstick test was negative in 15,548 samples (37.9%), trace in 6,422 samples (15.6%), and ≥1+ in 19,088 samples (46.5%). Among the trace proteinuria samples, A1 (<0.15 g/gCr), A2 (0.15-0.49 g/gCr), and A3 (≥0.5 g/gCr) category proteinuria accounted for 31.2, 44.8, and 24.0% of samples, respectively. All trace proteinuria specimens with a specific gravity of <1.010 were classified as A2 and A3 category proteinuria. In the trace proteinuria cases, women had a lower specific gravity and a higher percentage of A2 or A3 category proteinuria than men. The sensitivity in the "dipstick proteinuria" ≥ trace" group was higher than that in the "dipstick proteinuria ≥ 1+" group within the lower specific gravity group. The sensitivity in the "dipstick proteinuria ≥ 1+" group was higher for men than for women, and the sensitivity in the "dipstick proteinuria ≥ trace" group was higher than that in the "dipstick proteinuria ≥ 1+" group for women. Conclusion: Pathological proteinuria assessment requires caution; this study suggests that evaluating the specific gravity of urine specimens with trace proteinuria is essential. Particularly for women, the sensitivity of the urine dipstick test is low, and caution is needed even with trace specimens.

Esaxerenone Inhibits Renal Angiogenesis and Endothelial-Mesenchymal Transition via the VEGFA and TGF-ß1 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-ß1 (TGF-ß1) 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.

NGAL is a Novel Target in Hypertension by Modulating the NCC-Mediated Renal Na Balance.

BACKGROUND: The expression of NGAL/lcn2 (neutrophil gelatinase-associated lipocalin) is directly modulated by mineralocorticoid receptor activation but its role in blood pressure control is unclear. METHODS: a potential relationship between NGAL plasma levels, systolic blood pressure and urinary Na excretion was assessed in the STANISLAS cohort. The specific role of NGAL/lcn2 in salt-sensitive hypertension was studied using lcn2-knockout mice (lcn2 KO) fed with low-Na diet (0Na). RESULTS: we show that NGAL plasma levels positively correlate with systolic blood pressure, whereas they negatively correlate with urinary Na excretion in subjects of the STANISLAS cohort. Prolonged feeding of lcn2 KO mice with a 0Na diet induced lower systolic blood pressure than that of the control group (wildtype), suggesting a role for NGAL/lcn2 in Na-balance homeostasis. Short-term or prolonged 0Na increased Na-Cl cotransporter (NCC) phosphorylation in the cortex of wildtype mice, which was prevented in lcn2 KO mice. Recombinant mouse lcn2 injections in lcn2 KO mice induced NCC phosphorylation in the kidney cortex, associated with decreased urinary Na excretion. Ex vivo experiments using kidney slices from lcn2 KO mice showed increased NCC phosphorylation by recombinant murine lcn2. In addition, recombinant murine lcn2 induced activation of CamK2ß (calcium/calmodulin-dependent protein kinase II ß subunit) phosphorylation in lcn2 KO mice and in kidney slices, providing an underlying mechanism involved in lcn2-induced NCC phosphorylation. Indeed, the inhibition of CamK2ß prevented NCC phosphorylation induced by recombinant lcn2 in kidney slices. CONCLUSIONS: we highlight a novel role of NGAL/lcn2 as a modulator of the activity of the renal sodium transporter NCC affecting salt-sensitive blood pressure.

Variation in antibody titers determined by Abbott and Roche Elecsys SARS-CoV-2 assays in vaccinated healthcare workers.

SARS-CoV-2-specific antibody measurement is important for evaluating COVID-19 vaccine efficacy. We quantified and compared anti-spike (S) antibodies using different commercial immunoassays. We tested serum samples from 70 SARS-CoV-2-naive health care workers 2 weeks after vaccination with a single dose of BNT162b2, 2 and 4 weeks, and 3 months after the second dose of BNT162b2. The following quantitative assays were used: Roche Elecsys Anti-SARS-CoV-2 S (Roche-S), Abbott SARS-CoV-2 IgG II Quant [Abbott-IgG(S)], and Abbott SARS-CoV-2 IgM (Abbott-IgM). All samples tested positive for Roche-S and Abbott-IgG antibodies after the second dose, with 83.6% Abbott-IgM positive rate. Roche-S and Abbott-IgG(S) correlated significantly in all samples (r = 0.920, p < 0.0001), and the Roche-S and Abbott-IgG(S) assay showed a strong correlation with each other at each time point after vaccination. Roche-S and Abbott-IgG(S) antibody titers were correlated with age; their rate of decline was age-dependent in males but not in females. Abbott-IgG(S) antibody titers decreased from 2 weeks after the second dose. Roche-S antibody titers peaked 2 weeks after the second dose in 76.2% of the participants; the titers recovered 3 months post-vaccination after declining at week 4 in 40.7% of the participants. The concordance between Roche-S and Abbott-IgG(S) antibody titers over time was 47.5%. Most participants presented significantly high Roche-S and Abbott-IgG(S) antibody titers after immunization. Some measurements were inconsistent with titer changes between these assays, possibly because of differences in the immunoglobulin-specificity of the kits.

How animal models can be utilized to find new biomarkers for cardiovascular diseases.

It has been more than 60 years since the colonized genetic model of hypertension was first established. Model animals contribute greatly to the advance of understanding of the pathophysiology and development of effective therapy. In this review, the author focuses on two points: gene-related biomarkers and the use of humanized mice to search for biomarkers. First, the author provides an overview of the history of the establishment of hypertension and salt-sensitivity model rats, as well as advances in genetic analysis of causative genes of hypertension and the theory of renal causes of salt-sensitive hypertension. The recent animal model analysis adds the notion of the importance of epigenetic alterations in addition to the genetic causes of hypertension. Both germline mutations and epigenetic analysis of congenic animal models are complementary and should carry out furtherly. Among epigenetic factors, non-coding RNA is a promising new 'liquid biopsy' which is originally applied to diagnose cancers by detecting cancer cell-derived DNA, RNA, or other molecules in a person's body fluid and now it can be applied to any pathophysiological conditions. Then, the author reviews the usefulness of humanized mice. Few studies have used such mice in cardiovascular research, but the present study highlights a study of immune-related disease and the search for biomarkers in such mice. Perspectives on using humanized mice in cardiovascular research are discussed.

Quality is not an act, it is a habit-Aristotle.

To measure blood pressure precisely and make the data comparable among facilities, measurement methods and devices must be standardized. Since the Minamata Convention on Mercury, there is no metrological standard for sphygmomanometers. The current validation methods recommended by non-profit organizations in Japan, the US, and European Union countries are not necessarily applicable to the clinical setting, and no protocol for daily or routine performance of quality control has been defined. In addition, recent rapid technological advances have enabled monitoring blood pressure at home with wearable devices or without a cuff by using a smartphone app. A clinically relevant validation method for this recent technology is not available. The importance of out-of-office blood pressure measurement is highlighted by guidelines for the diagnosis and treatment of hypertension, but an appropriate protocol for validating a device is required.

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.

Urinary lipid profile of patients with coronavirus diseases 2019.

The coronavirus diseases 2019 (COVID-19) pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is ongoing. Over 490 million people have been infected with this virus worldwide. Although many patients present with lower respiratory symptoms, some may progress to acute respiratory distress syndrome and even multi-organ damage. Therefore, there is an urgent need to establish treatment and management methods for this infectious disease. Here, we comprehensively analyzed urinary lipid mediators and their metabolites to identify non-invasive biomarkers that reflect the disease status of COVID-19 patients. We diagnosed 16 patients by polymerase chain reaction (PCR) analysis, who presented with mild-to-moderate symptoms, including fever and cough, between May and October 2020 in Japan, and collected their urine samples. Using mass spectrometry, we analyzed the lipid metabolites in these urine samples. In all the urine samples from the patients, 21 types of fatty acids and their metabolites were consistently detected in the samples among the 214 metabolites which were analyzed. Interestingly, urinary levels of fatty acids, docosahexaenoic acid was increased by approximately 3-fold in patients with COVID-19 compared to those in healthy subjects. Metabolites of major proinflammatory lipid mediators, PGE2, TXA2, and PGF2α, were also detected at significantly higher levels in the urine of patients with COVID-19. These observations suggest that urinary lipids can reflect the inflammatory status of patients with COVID-19, which can be a useful index to manage this disease.

Eplerenone Prevents Cardiac Fibrosis by Inhibiting Angiogenesis in Unilateral Urinary Obstruction Rats.

Introduction: Cardiovascular disease constitutes the leading cause of mortality in patients with chronic kidney disease (CKD), which is termed cardiorenal syndrome type 4 (CRS-4). Here, we report the development of pathological cardiac remodeling and fibrosis in unilateral urinary obstruction (UUO) rats. Methods: Hematoxylin and eosin (H&E) staining was performed to observe the pathology of myocardial tissue. The degree of myocardial tissue fibrosis was observed by Masson and Sirius red staining. Immunohistochemical staining was applied to detect the expression of CD34 and CD105 in myocardial tissue, and immunofluorescent staining was performed to examine the expression of CD34, collagen I/collagen III, and alpha smooth muscle actin (α-SMA). The expression of the signal pathway-related proteins vascular endothelial growth factor A (VEGFA), vascular endothelial growth factor receptor 2 (VEGFR2), nuclear factor κB (NF-κB), and interleukin (IL)-1ß was tested by western blotting. Reverse transcription-polymerase chain reaction (RT-PCR) was used to detect the mRNA levels of serum and glucocorticoid-inducible kinase (SGK)-1, NF-κB, and interleukin-1ß (IL-1ß). Results: The results showed the development of pathological cardiac remodeling and cardiac dysfunction in UUO rats. Moreover, there was more angiogenesis and endothelial-mesenchymal transition (End-MT) in the UUO group, and these effects were inhibited by eplerenone. Conclusions: The results indicated that this cardiac fibrosis was associated with angiogenesis and that End-MT was related to aldosterone and mineralocorticoid receptor (MR) activation. Moreover, in association with the MR/IL-1ß/VEGFA signaling pathway, early treatment with the MR antagonist eplerenone in rats with UUO-induced CKD may significantly attenuate MR activation and cardiac fibrosis.

Eplerenone ameliorates lung fibrosis in unilateral ureteral obstruction rats by inhibiting lymphangiogenesis.

Chronic kidney disease (CKD) involves progressive and irreversible loss of renal function, often causing complications and comorbidities and impairing the function of various organs. In particular, lung injury is observed not only in advanced CKD but also in early-stage CKD. The present study investigated the potential involvement of mineralocorticoid receptors (MRs) and lymphatic vessels in lung injury using a 180-day unilateral ureteral obstruction (UUO) model for CKD. Changes in lung associated with lymphangiogenesis and inflammatory were analyzed in UUO rats. The pathology of the lung tissue was observed by hematoxylin and eosin and Masson's staining. Detection of the expression of lymphatic vessel endothelial hyaluronic acid receptor-1 (LYVE-1), Podoplanin, vascular endothelial growth factor receptor-3 (VEGFR-3) and VEGF C to investigate lymphangiogenesis. The mRNA and protein expression levels of IL-1ß, monocyte chemotactic protein 1, tumor necrosis factor-α, nuclear factor κB, phosphorylated serum and glucocorticoid-induced protein kinase-1 and MR were evaluated using western blot, reverse transcription-quantitative PCR, immunohistochemical staining and immunofluorescence staining. In the present study, long-term UUO caused kidney damage, which also led to lung inflammation, accompanied by lymphangiogenesis. However, treatment with eplerenone, an MR blocker, significantly reduced the severity of lung injury and lymphangiogenesis. Therefore, lymphangiogenesis contributed to lung fibrosis in UUO rats due to activation of MRs. In addition, transdifferentiation of lymphatic epithelial cells into myofibroblasts may also be involved in lung fibrosis. Collectively, these findings provided a potential mechanism for lung fibrosis in CKD and suggested that the use of eplerenone decreased kidney damage and lung fibrosis.

Esaxerenone inhibits the macrophage-to-myofibroblast transition through mineralocorticoid receptor/TGF-ß1 pathway in mice induced with aldosterone.

Renal fibrosis is the inevitable pathway of the progression of chronic kidney disease to end-stage renal disease, which manifests as progressive glomerulosclerosis and renal interstitial fibrosis. In a previous study, we observed severe interstitial fibrosis in the contralateral kidneys of 6-month unilateral ureteral obstruction (UUO) rats, which was accompanied by increased macrophage infiltration and phenotypic transformation; after eplerenone administration, these effects were reduced. Therefore, we hypothesized that this effect was closely related to mineralocorticoid receptor (MR) activation induced by the increased aldosterone (ALD) level. In this study, we used uninephrectomy plus continuous aldosterone infusion in mice to observe whether aldosterone induced macrophage-to-myofibroblast transition (MMT) and renal fibrosis and investigated the signaling pathways. Notably, aldosterone induced predominantly M1 macrophage-to-myofibroblast transition by activating MR and upregulating TGF-ß1 expression, which promoted renal fibrosis. These effects were antagonized by the MR blocker esaxerenone. These findings suggest that targeting the MR/TGF-ß1 pathway may be an effective therapeutic strategy for renal fibrosis.

Eplerenone inhibits UUO-induced lymphangiogenesis and cardiac fibrosis by attenuating inflammatory injury.

Cardiorenal syndrome (CRS) is the leading cause of death associated with chronic kidney disease (CKD) and end-stage renal disease (ESRD). However, the underlying mechanisms of CRS are still poorly understood. Here, we studied a CKD model of unilateral ureteral obstruction (UUO) and observed pathological cardiac fibrosis and lymphangiogenesis in 180-day old UUO rats, in which inflammatory injury plays a major role. In addition, treatment of UUO rats with eplerenone, a mineralocorticoid receptor blocker (MRB), significantly reduced cardiac lymphangiogenesis and fibrosis. In conclusion, our experimental results showed that cardiac lymphangiogenesis in long-term UUO rats may be involved in the formation of cardiac fibrosis and that eplerenone can alleviate lymphangiogenesis and cardiac fibrosis by inhibiting inflammation.

Chronic intermittent hypoxia induces renal fibrosis through MR activation.

Obstructive sleep apnea syndrome (OSAS) is a disorder characterized by recurrent arousal from sleep and chronic intermittent hypoxia (CIH). OSAS-associated chronic kidney disease is mainly caused by CIH-induced tissue damage. Therefore, an OSAS model was established by CIH exposure in a hypoxic chamber for five weeks. In our study, macrophage infiltration and macrophage-myofibroblast transition (MMT) were observed in the kidneys of CIH rats and appeared to contribute to the development of renal fibrosis. However, the underlying mechanisms are not well defined. We also found that upon binding to the mineralocorticoid receptor (MR), aldosterone stimulated MMT and consequently led to renal fibrosis under hypoxic conditions. Additionally, an in vitro study of RAW264.7 macrophages demonstrated that MR activation may contribute to MMT, which resulted in a predominant M1 phenotype under hypoxic conditions. These effects were reversed by the MR blocker eplerenone. These results provide preliminary evidence that MR activation might be involved in the transdifferentiation of macrophages into myofibroblasts in the CIH model. The attenuation of renal injury demonstrates a protective role of MR blockade in CIH-induced renal disease.