Inhibitory effects of Eplerenone on angiogenesis via modulating SGK1/TGF-β pathway in contralateral kidney of CKD pregnancy rats.

Background: Eplerenone is a selective aldosterone receptor blocker that is effective in preventing the progression of chroinic kidney disease (CKD). However, its mechanism and role in CKD pregnancy still remain uncertain. The aim of this study was to evaluate whether eplerenone could attenuated the fibrosis of unilateral ureteral obstruction (UUO) pregnant rats' contralateral kidney, improved pregnancy outcome and explore its therapeutic mechanisms.

Methods: A pregnancy rat model of UUO established, female Wistar rats were randomly assigned into sham-operated group (Sham group),sham-operated combined pregnancy group (SP group), unilateral ureteral obstruction combined pregnancy group (UUO + Pregnancy group), unilateral ureteral obstruction combined pregnancy, administered eplerenone (UUO + Pregnancy+Eplerenone group). On the 18th day of pregnancy, the rats were placed in a metabolic cage, 24 h urine was collected and stored at -80 °C. Next day, all animals were euthanized, and serum was collected by centrifugation and stored at -20 °C. Then the right kidney was extracted, a part of the kidney was placed in 4% paraformaldehyde for morphology, immunohistochemical staining, and immunofluorescence staining, and the other part was placed in a - 80 °C refrigerator for RNA and protein extraction. In vitro, HUVECs was treated with aldosterone, progesterone and estradiol, VEGFA and its receptor blocker bevacizumab. The ability of proliferation, migration and tubularization of HUVECs was detected by CCK-8, scratch wound assay and endothelial tube formation assay. And the co-expression of CD34 and α-SMA of HUVECs was detected by Flow cytometry.

Results: Immunofluorescence results showed that the co-expression of CD34 and α-SMA increased in the UUO + Pregnancy group was significantly increased. The expression of SGK-1, TGFβ-1, Smad2, Smad3, VEGF-A, VEGFR2, CD34, α-SMA and Collagen I was significantly higher in the kidneys of the UUO + Pregnancy group compared to the Sham group and SP group. Eplerenone inhibited the expression of those results. In vitro, the ability of proliferation, migration and tubularization was increased after treated with aldosterone, aldosterone with progesterone and estradiol or VEGFA. Similarly, the expression of α-SMA on the surface of HUVECs treated with aldosterone, aldosterone with progesterone and estradiol were increased, while eplerenone supressed its expression.

Conclusion: Eplerenone inhibits renal angiogenesis by blocking the SGK-1/TGFβ signal transduction pathway, thereby inhibiting the phenotypic transformation of endothelial cells, slowing down renal fibrosis, and reducing kidney damage caused by pregnancy.