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.

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.

The IFNγ-PDL1 Pathway Enhances CD8T-DCT Interaction to Promote Hypertension.

BACKGROUND: Renal T cells contribute importantly to hypertension, but the underlying mechanism is incompletely understood. We reported that CD8Ts directly stimulate distal convoluted tubule cells (DCTs) to increase NCC (sodium chloride co-transporter) expression and salt reabsorption. However, the mechanistic basis of this pathogenic pathway that promotes hypertension remains to be elucidated. METHODS: We used mouse models of DOCA+salt (DOCA) treatment and adoptive transfer of CD8+ T cells (CD8T) from hypertensive animals to normotensive animals in in vivo studies. Co-culture of mouse DCTs and CD8Ts was used as in vitro model to test the effect of CD8T activation in promoting NCC-mediated sodium retention and to identify critical molecular players contributing to the CD8T-DCT interaction. Interferon (IFNγ)-KO mice and mice receiving renal tubule-specific knockdown of PDL1 were used to verify in vitro findings. Blood pressure was continuously monitored via radio-biotelemetry, and kidney samples were saved at experimental end points for analysis. RESULTS: We identified critical molecular players and demonstrated their roles in augmenting the CD8T-DCT interaction leading to salt-sensitive hypertension. We found that activated CD8Ts exhibit enhanced interaction with DCTs via IFN-γ-induced upregulation of MHC-I and PDL1 in DCTs, thereby stimulating higher expression of NCC in DCTs to cause excessive salt retention and progressive elevation of blood pressure. Eliminating IFN-γ or renal tubule-specific knockdown of PDL1 prevented T cell homing into the kidney, thereby attenuating hypertension in 2 different mouse models. CONCLUSIONS: Our results identified the role of activated CD8Ts in contributing to increased sodium retention in DCTS through the IFNγ-PDL1 pathway. These findings provide a new mechanism for T cell involvement in the pathogenesis of hypertension and reveal novel therapeutic targets.

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.

Aldosterone Induces the Proliferation of Renal Tubular Epithelial Cells In Vivo but Not In Vitro.

OBJECTIVE: To investigate the proliferation effect of aldosterone on renal tubular epithelial cells in vivo and in vitro. METHODS: Thirty-two male C57BL/6J mice (20-22 g) were divided randomly into four groups: sham, unilateral nephrectomy (UN), unilateral nephrectomy plus aldosterone infusion (UA), and UA plus eplerenone (UAE). The kidneys were removed 6 weeks after treatment. Expression of proliferating cell nuclear antigen (PCNA) was detected by immunohistochemistry and western blotting. Human kidney proximal tubular epithelial (HK2) and mouse distal convoluted tubule (mDCT) cell lines were stimulated by aldosterone (0, 10-9, 10-8, 10-7, and 10-6 mol/L) in vitro. Cells were collected after 3, 6, 12, 24, 36, and 48 h, and proliferation of each group detected by western blotting, flow cytometry, live imaging, and the MTT assay. In addition, mDCT cells were costimulated with a medium containing a final concentration of 161 mmol/L Na+ and different concentrations of aldosterone, and the number of cells and cellular DNA content was measured by the MTT assay and flow cytometry. RESULTS: Aldosterone could induce a significant increase in the number of PCNA-positive cells in mouse kidneys accompanied by increased deposition of collagen fibers. Eplerenone could inhibit aldosterone-induced cell proliferation and collagen deposition. HK2 cells and mDCT cells administered different concentrations, and different times of aldosterone stimulation failed to cause cell proliferation, and costimulation of aldosterone and salt did not cause proliferation changes in mDCT cells. CONCLUSIONS: Aldosterone perfusion can induce proliferation of mouse kidney cells in vivo, and eplerenone can inhibit this change, but aldosterone stimulates HK2 cells and mDCT in vitro without causing their proliferation.

Astragaloside IV Inhibits Mitochondrial-Dependent Apoptosis of the Dorsal Root Ganglion in Diabetic Peripheral Neuropathy Rats Through Modulation of the SIRT1/p53 Signaling Pathway.

PURPOSE: To investigate the effect of astragaloside IV (AS-IV) on mitochondrial-dependent apoptosis in the dorsal root ganglion of diabetic peripheral neuropathy (DPN) rats through the SIRT1/p53 pathway. METHODS: Diabetic rat model was induced by high-carbohydrate/high-fat diet and intraperitoneal injection of STZ. Diabetic rats were divided into three groups (n =16 per group): DPN group, AS-IV group (60mg/kg/d) and α-lipoic acid (ALA) group (60mg/kg/d). Weight and blood glucose levels were monitored every 4 weeks for 12 weeks. DPN was evaluated using the Von Frey Filaments Test and nerve conduction velocity. The dorsal root ganglia of rats were isolated and the pathological changes of mitochondria were observed by electron microscopy. The activity of mitochondrial electron transport chain complex, mitochondrial membrane potential, malonaldehyde (MDA) and glutathione (GSH) levels were measured. Neural apoptosis was detected using the Terminal Deoxynucleotidyl Nick-End Labeling (TUNEL) assay kit. The cleaved caspase-3, major proteins in the SIRT1/p53 pathway, including SIRT1, acetyl p53, Drp1, BAX, and BCL-2, were detected using immunohistochemistry and Western blot. Gene expression of major proteins in the SIRT1/p53 pathway was also detected. RESULTS: After 12 weeks of treatment, AS-IV and ALA did not significantly affect body weight or fasting glucose levels, but reduced mechanical abnormal pain in DPN and improved nerve conduction velocity. AS-IV and ALA increased the level of GSH and decreased the level of MDA. Both AS-IV and ALA can reduce mitochondrial damage, improve mitochondrial electron transport chain complex activity and mitochondrial membrane potential, and reduce the percentages of positive cells with DNA fragmentation and the expression of cleaved caspase-3 protein. AS-IV and ALA up-regulated the expression of SIRT1 and down-regulated the expression of acetyl-p53, Drp1 and the ratio of BAX to BCL-2. Changes in gene expression were similar. CONCLUSION: AS-IV can reduce the occurrence of mitochondrial-dependent apoptosis by regulating the SIRT1/p53 pathway. It has a similar therapeutic effect as ALA and is therefore a promising drug for the potential treatment of DPN.

Eplerenone Attenuates Fibrosis in the Contralateral Kidney of UUO Rats by Preventing Macrophage-to-Myofibroblast Transition.

Severe renal fibrosis often occurs in obstructive kidney disease, not only in the obstructed kidney but also in the contralateral kidney, causing renal dysfunction. Although the mechanisms of injury in obstructed kidney have been studied for years, the pathogenesis of fibrosis in the contralateral kidney remains largely unknown. Here, we examined long-term unilateral ureteral obstruction (UUO) model in male Sprague-Dawley rats and found that macrophage-to-myofibroblast transition (MMT) is contributing to renal fibrosis in the contralateral kidney of UUO rats. Interestingly, this process was attenuated by treatment of eplerenone, a specific blocker of the mineralocorticoid receptor (MR). In-vitro, stimulating MR in primary cultured or cell line macrophages enhances MMT, which were also inhibited by MR blockade. Collectively, these findings provide a plausible mechanism for UUO-induced injury in the contralateral kidney, suggesting the benefit of using MR blockage as a part of treatment to UUO to protect the contralateral kidney thereby preserve renal function.

UUO induces lung fibrosis with macrophage-myofibroblast transition in rats.

Progression of chronic kidney disease (CKD) to uremia is often accompanied by varying degrees of lung damage and this is also an important cause of death. Although there are many studies on the mechanism of lung injury, it is not clearly understood. Inflammatory macrophages may associated with fibrosis in the lungs. Here, we investigated the role of macrophage-myofibroblast transition (MMT) in lung fibrosis with unilateral ureteral obstruction (UUO) rats. We found that cells undergoing MMT accounted for an important part of the myofibroblast population, and correlated with lung fibrosis, MMT cells in lungs have a predominant M2 phenotype, and this process was attenuated after treatment with eplerenone. In conclusion, our studies provide a possible mechanism for UUO-induced kidney damage and lung injury, indicating the possibility of using eplerenone, a mineralocorticoid receptor blocker, to treat UUO to reduce kidney damage and protect lung function.

Eplerenone Ameliorates Cell Pyroptosis in Contralateral Kidneys of Rats with Unilateral Ureteral Obstruction.

BACKGROUND: The progression of chronic renal failure in patients with unilateral renal injury is associated with loss of function in the contralateral kidney, but the molecular mechanism remains unclear. The activation of mineralocorticoid receptor (MR) in the kidney contributes to renal cell damage, leading to apoptosis, pyroptosis, and necrosis. Pyroptosis is a programmed cell death induced by caspase-1, which is usually activated by nod-like receptor pyrin-containing 3 (NLRP3) inflammasomes. Our study aimed to investigate the effects of eplerenone (EPL) on cell pyroptosis in the contralateral kidneys of unilateral ureteral obstruction (UUO) rats. METHODS: Sprague-Dawley rats were randomly divided into 3 groups: sham group, UUO group (10 days of left ureter ligation), and UUO treated with EPL (UUO + EPL) group. The contralateral kidneys of all rats were collected for studies. RESULTS: We observed evidently increased number of pyroptosis cells in the contralateral kidneys of UUO rats compared to those from Sham rats. The expression of NLRP3, caspase-1, interleukin-1ß, serum and glucocorticoid-inducible protein kinase-1, and nuclear factor kappa B were also upregulated in the contralateral kidneys of UUO rats compared to Sham kidneys, and these effects were reduced by MR blocker EPL. CONCLUSION: Our data suggest that the activation of MR is involved in NLRP3/caspase-1 pathway-induced cell pyroptosis in the contralateral kidney of UUO model.

[Effect of Huayu Jiedu Recipe on the Expressions of NLRP3, Caspasel, and IL-1 ß in Kidneys of Obstructive Nephropathy Rats].

Objective To observe the effect of Huayu Jiedu Recipe (HJR) on the expressions of nucleotide-binding oligomerization domain (NOD)-like receptor protein 3 (NLRP3) , Caspase-1 , IL-1 ß in kidneys of obstructive nephropathy rats. Methods Totally 40 clean grade SD rats were randomly divided into the sham-operation group (n =10) and the model group (n =30). The model of obstructive nephropa- thy was established by unilateral ureteral obstruction (UUO). Totally 30 successfully modeled UUO rats were randomly divided into the model group, the Western medicine group, the Chinese medicine group, 10 in each group. Eplerenone (100 mg . kg ⁻¹ . d⁻¹) was administrated to rats in the Western medicine group. HJR (13.7 g . kg ⁻¹ . d⁻¹) was administrated to rats in the Chinese medicine group. Equal volume of normal saline was administered to rats in the sham-operation group and the model group. All medica- tion was performed once daily for 10 successive days. The serum IL-1 ß level was detected. Protein and mRNA expressions of NLRP3, Caspase-1, and IL-1 ß in renal tissue were detected. TUNEL positive rate was detected by TUNEL method. Results The expression of NLRP3 was not obviously seen, Caspase-1 and IL-1 ß were weakly expressed, and only fewer amount of TUNEL positive cells could be seen in the sham-operation group. Compared with the sham-operation group, serum IL-1ß level increased (P < 0. 01) , mRNA and protein expression of NLRP3, Caspase-1 , and IL-1 ß were up-regulated in renal tissue of the model group (P <0. 01). NLRP3 was mainly expressed in renal interstitial macrophages and renal tubular epithelial cells. Caspase-1 and IL-1 ß were mainly expressed in the cytoplasm of renal tubular epithelial cells. TUNEL positive cells were significantly increased, mainly dominated in interstitial expanded epithelial cells of distal tubules (P <0. 01). Compared with the model group, serum IL-1 ß level was significantly decreased (P <0. 01) ; mRNA and protein expressions of NLRP3, Caspase-1 , and IL- ß were obviously down-regulated (P <0. 01) , and the TUNEL positive rate was obviously decreased (P <0. 05, P < 0. 01) in the two medicated groups. Conclusion HJR could down-regulate mRNA and protein expres- sions of NLRP3, Caspase-1 , and IL-1ß, thus attenuating inflammatory injury of renal tissue.