Estrogen deficiency aggravates fluorine ion-induced renal fibrosis via the TGF-β1/Smad signaling pathway in rats

Association between estrogen and kidney function: population based evidence and mutual bidirectional Mendelian randomization study

BACKGROUND

Previous studies have suggested a potential role of estrogen in the pathophysiology of chronic kidney disease (CKD); however, the association and causality between estrogen and kidney function remain unclear.

METHODS

The cross-sectional correlation between serum estradiol concentration and estimated glomerular filtration rate (eGFR) and urinary albumin-to-creatinine ratio (ACR) was analyzed using data from the National Health and Nutrition Examination Survey 2013-2016. Causality was tested using mutual bidirectional Mendelian randomization (MR) approaches based on six large-scale GWAS studies. Weighted generalized multivariate linear regression was employed to estimate the association between estradiol and eGFR and ACR, and a restricted cubic spline analysis was utilized to investigate potential nonlinear relationships.

RESULTS

A total of 8932 participants were included. Serum estradiol concentration was positively associated with eGFR after adjusting for potential covariates (β, 0.76; 95% CI 0.24 to 1.27) and with ACR (β, 5.99; 95% CI 1.62 to 10.36). A nonlinear positive association was found between estradiol and eGFR, while an inverse "V"-shaped relationship was seen with ACR. Sensitivity analyses confirmed the stability of the relationship between estradiol and eGFR but indicated a less robust association with ACR. Stratified analysis showed that the association between estradiol and eGFR was particularly significant in populations with CKD and hypertension. All forward MR analyses demonstrated a positive causal relationship between estradiol and eGFR, but no causality was found between estradiol and ACR. No reverse causal association was observed.

CONCLUSIONS

Serum estradiol concentration was causally associated with eGFR. Further longitudinal research is needed to validate these findings.

Mechanistic insights into the anti-fibrotic effects of estrogen via the PI3K-Akt pathway in frozen shoulder

The development of frozen shoulder (FS) is primarily characterized by pathological fibrosis, yet clinical treatment options remain limited. Recent studies have identified estrogen depletion during perimenopause as a significant contributor to the onset of FS and fibrosis. This study investigates the role of estradiol (E2) and the estrogen-related receptor (GPER) in fibrotic processes associated with FS to elucidate the underlying mechanisms. The functional relationship between E2, GPER, and FS progression was examined using a rat immobilization model and synovial-derived fibroblasts (SFs) from FS patients. E2's effects on GPER expression, fibroblast activation, and tissue fibrosis were evaluated through Western blotting, immunofluorescence staining, collagen contraction assays, wound healing assays, and histological staining. RNA sequencing identified signaling pathways and key regulators involved in E2 treatment. Both E2 and the GPER activator G1 exhibited antifibrotic effects, improving shoulder mobility, reducing extracellular matrix (ECM) deposition in the periarticular capsule, and decreasing the expression of fibrosis-related genes, including fibronectin, α-SMA, and COL3. In contrast, the GPER inhibitor G15 reversed these effects, suggesting that E2 mediates its antifibrotic action through GPER activation. Mechanistically, KEGG pathway analysis revealed that E2 suppresses the PI3K/AKT signaling pathway by inhibiting PI3K and AKT phosphorylation, thereby preventing fibroblast activation and reversing FS-associated fibrosis. These findings provide mechanistic insights into the previously unrecognized role of GPER in FS progression and may open new avenues for research to optimize future clinical therapies.

Eucommiae cortex extract alleviates renal fibrosis in CKD mice induced by adenine through the TGF-β1/Smad signaling pathway

Research into the potential therapeutic benefits of herbal remedies for treating chronic kidney disease (CKD), a condition marked by renal fibrosis and persistent inflammation, has become popular. Eucommiae cortex (EC) is a vital herb for strengthening bones and muscles and tonifying the kidneys and liver. In the study, C57 BL/6 mice were given a diet containing 0.2% adenine to create a CKD model. The findings demonstrated that exogenous EC supplementation successfully decreased the levels of creatinine and urea nitrogen, down-regulated the TGF-β1/Smad signaling pathway's expression levels of TGF-β1, α-SMA, Smad3, and phospho-Smad3, and prevented renal fibrosis. Consequently, it was determined that EC might have a nephroprotective impact.

Study on effects and relevant mechanisms of Mudan granules on renal fibrosis in streptozotocin-induced diabetes rats

AIMS

The effects and relevant mechanisms of Mudan granules in the renal fibrosis of diabetic rats were explored through in vivo experiments, which provided a scientific basis for expanding their clinical indications.

METHODS

Male SD rats were given a single intraperitoneal injection of STZ (65 mg/kg) to induce diabetes rat models. After treatment with Mudan granules, the general condition of rats was recorded. Blood glucose, blood lipids, and renal function-related indicators were detected, renal tissue morphological changes and fibrosis-related indicators were observed, and the expression of pathway-related proteins were examined.

RESULTS

The general condition of diabetes rats was improved after the treatment of Mudan granules, the 24-h urinary protein and urinary albumin to creatinine ratio were reduced, and the renal function and lipid results were modified. The tissue damage to the rat kidney has been repaired. Expression of TGF-β1/Smad-related pathway proteins was suppressed in kidney tissues, and the fibrosis factor CO-IV, FN, and LN were reduced in serum.

CONCLUSION

Mudan granules may inhibit of TGF-β1/Smad pathway, inhibit the production of ECM, reduce the levels of fibrosis factors CO-IV, FN, and LN, to have a protective effect on kidney in diabetes rats.

Interaction of estradiol and renin-angiotensin system with microRNAs-21 and -29 in renal fibrosis: focus on TGF-β/smad signaling pathway

Kidney fibrosis is one of the complications of chronic kidney disease (CKD (and contributes to end-stage renal disease which requires dialysis and kidney transplantation. Several signaling pathways such as renin-angiotensin system (RAS), microRNAs (miRNAs) and transforming growth factor-β1 (TGF-β1)/Smad have a prominent role in pathophysiology and progression of renal fibrosis. Activation of classical RAS, the elevation of angiotensin II (Ang II) production and overexpression of AT1R, develop renal fibrosis via TGF-β/Smad pathway. While the non-classical RAS arm, Ang 1-7/AT2R, MasR reveals an anti-fibrotic effect via antagonizing Ang II. This review focused on studies illustrating the interaction of RAS with sexual female hormone estradiol and miRNAs in the progression of renal fibrosis with more emphasis on the TGF-β signaling pathway. MiRNAs, especially miRNA-21 and miRNA-29 showed regulatory effects in renal fibrosis. Also, 17β-estradiol (E2) is a renoprotective hormone that improved renal fibrosis. Beneficial effects of ACE inhibitors and ARBs are reported in the prevention of renal fibrosis in patients. Future studies are also merited to delineate the new therapy strategies such as miRNAs targeting, combination therapy of E2 or HRT, ACEis, and ARBs with miRNAs mimics and antagomirs in CKD to provide a new therapeutic approach for kidney patients.

Lupenone improves type 2 diabetic nephropathy by regulating NF-κB pathway-mediated inflammation and TGF-β1/Smad/CTGF-associated fibrosis

BACKGROUND

Type 2 diabetic nephropathy is a common diabetic complication and the main cause of death in patients with diabetes. Research has aimed to find an ideal drug with minimal side effects for treating this disease. Banana peel has been shown to be anti-diabetic, with lupenone isolated from banana peel exhibiting antidiabetic and anti-inflammatory activities; However, the effects of lupenone on type 2 diabetic nephropathy are largely unknown.

PURPOSE

This study aimed to investigate the ameliorative effect of lupenone on type 2 diabetic nephropathy, and its mechanism from both anti-inflammatory and anti-fibrotic perspectives.

METHODS

Spontaneous type 2 diabetic nephropathy db/db mouse models were given three levels of lupenone (24 or 12 or 6 mg/kg/d) via intragastric administration for six weeks, and irbesartan treatment was used for the positive control group. We explored the effects and mechanism of lupenone action using enzyme-linked immunosorbent assay, automatic biochemical analyzer, hematoxylin-eosin and Masson staining, real time-PCR, and western blotting. Concurrently, a high-sugar and high-fat diet combined with a low-dose streptozotocin-induced type 2 diabetic nephropathy rat model was used for confirmatory research.

RESULTS

Lupenone administration maintained the fasting blood glucose; reduced glycosylated hemoglobin, insulin, and 24 h proteinuria levels; and markedly regulated changes in biochemical indicators associated with kidney injury in serum and urine (including 24 h proteinuria, micro-albumin, N-acetyl-β-d-glucosaminidase, α1-micro-globulin, creatinine, urea nitrogen, uric acid, total protein, and albumin) of type 2 diabetic nephropathy mice and rats. Hematoxylin-eosin and Masson staining as well as molecular biology tests revealed that inflammation and fibrosis are the two key processes affected by lupenone treatment. Lupenone protected type 2 diabetic nephropathy kidneys by regulating the NF-κB-mediated inflammatory response and TGF-β1/Smad/CTGF pathway-associated fibrosis.

CONCLUSION

Lupenone has potential as an innovative drug for preventing and treating diabetic nephropathy. Additionally, it has great value for the utilization of banana peel resources.

Th17-Related Cytokines Involved in Fluoride-Induced Cecal and Rectal Barrier Damage of Ovariectomized Rats

To investigate fluoride (F)-induced intestine barrier damage and the role of estrogen deficiency in this progress, a rat model of estrogen deficiency was established through bilateral surgical removal of ovaries. The F exposure model was then continued by adding sodium fluoride (0, 25, 50, and 100 mg/L, calculated on a fluorine ion basis) to drinking water for 90 days. Afterward, intestinal mucosal structure, barrier function, and inflammatory cytokines were evaluated. The results showed that excessive F decreased the developmental parameters (crypt depth) of the cecum and rectum and inhibited the proliferation capacity of the intestinal epithelia, which are more obvious in the state of estrogen deficiency. The distribution of goblet cells and glycoproteins in the intestinal mucosa decreased with the increase in F concentration, and estrogen deficiency led to a further decline, especially in the rectum. Using the immunofluorescence method, the study showed that excessive F caused interleukin-17A (IL-17A) significantly decrease in the cecum and increase in the rectum. Meanwhile, F treatment remarkably upregulated the expression of intestinal IL-1β, IL-23, and IL-22, while the level of IL-6 was downregulated. In addition, estrogen deficiency increased IL-1β, IL-6, IL-23, and IL-22, but decreased IL-17A expression in the cecum and rectum. Collectively, F exposure damaged intestinal morphological structure, inhibited epithelial cell proliferation and mucus barrier function, and resulted in the disturbance of T helper (Th) 17 cell-related cytokines expression. Estrogen deficiency may further aggravate F-induced damage to the cecum and rectum.