Dapagliflozin Alleviates Renal Fibrosis by Inhibiting RIP1-RIP3-MLKL-Mediated Necroinflammation in Unilateral Ureteral Obstruction

Dapagliflozin, a sodium-glucose cotransporter-2 inhibitor, offers renoprotection in diabetes. However, potential for use in nondiabetic kidney disease remains unknown. Herein, we assessed whether dapagliflozin alleviates renal fibrosis by interfering with necroinflammation in a rat model of unilateral ureteral obstruction (UUO) and in vitro. After induction of UUO, rats were administered dapagliflozin daily for seven consecutive days. UUO induced significant renal tubular necrosis and overexpression of RIP1-RIP3-MLKL axis proteins; these coincided with NLRP3 inflammasome activation, and subsequent development of renal fibrosis. Oxidative stress caused by UUO is tightly associated with endoplasmic reticulum stress and mitochondrial dysfunction, leading to apoptotic cell death through Wnt3α/β-catenin/GSK-3β signaling; all of which were abolished by both dapagliflozin and specific RIP inhibitors (necrostatin-1 and GSK872). In H2O2-treated HK-2 cells, dapagliflozin and RIP inhibitors suppressed overexpression of RIP1-RIP3-MLKL proteins and pyroptosis-related cytokines, decreased intracellular reactive oxygen species production and apoptotic cell death, whereas cell viability was improved. Moreover, activated Wnt3α/β-catenin/GSK-3β signaling was inhibited by dapagliflozin and Wnt/β-catenin inhibitor ICG-001. Our findings suggest that dapagliflozin ameliorates renal fibrosis by inhibiting RIP1-RIP3-MLKL-mediated necroinflammation via Wnt3α/β-catenin/GSK-3β signaling in UUO.

Kidney-Draining Lymph Node Fibrosis Following Unilateral Ureteral Obstruction

Although the primary organ has been the subject of intense investigation in the field of organ fibrosis over the past several decades, the presence of lymph node fibrosis due to persistent activation of the immune response in its partner organ remains largely unknown. Previously, we demonstrated that activation of the immune response following ischemia-reperfusion injury (IRI) and crescentic glomerulonephritis (CGN) in the kidney was associated with extracellular matrix (ECM) production by fibroblastic reticular cells (FRCs) of the kidney-draining lymph node (KLN). Here, we sought to determine whether FRCs in the KLN become similarly fibrogenic following unilateral ureteral obstruction (UUO) of the kidney. We subjected 6–8-week-old C57BL/6J mice to UUO for 2, 7, and 14 days. We examined the microarchitecture of the kidney and KLN by immunofluorescence staining at each timepoint, and we quantified immune cell populations in the KLN by flow cytometry. The contralateral kidney unaffected by UUO and its partner KLN were used as controls. We found through immunofluorescence staining that FRCs increased production of ECM fibers and remodeled the microarchitecture of the UUO KLN, contributing to fibrosis that mirrored the changes in the kidney. We also observed by flow cytometry that the populations of CD11b+ antigen-presenting cells, CD11c+ dendritic cells, and activated CD4+ and CD8+ T cells were significantly higher in the UUO KLN than the KLN draining the unaffected contralateral kidney. Expression of the TGFβ/TGFβR signaling pathway was upregulated and colocalized with FRCs in the UUO KLNs, suggesting a possible mechanism behind the fibrosis. Both release of ureteral ligation at 2 days following UUO and depletion of FRCs at the time of injury onset halted the progression of fibrosis in both the kidney and the KLN. These findings for the first time highlight the association between fibrosis both in the kidney and the KLN during UUO, and they lay the groundwork for future studies that will investigate more deeply the mechanisms behind the connection between FRCs and KLN fibrosis.

Tongluo Yishen Decoction Ameliorates Renal Fibrosis via Regulating Mitochondrial Dysfunction Induced by Oxidative Stress in Unilateral Ureteral Obstruction Rats

Tongluo Yishen (TLYS) decoction is an herb that is extensively applied for the treatment of chronic kidney disease (CKD) in traditional Chinese medicine. In this study, 37 different dominant chemical constituents of TLYS were identified. Rats with unilateral ureteral obstruction (UUO) were used as animal models, and TLYS decoction was administered orally for 14 days. TLYS decoction reduced the levels of renal function indicators, serum creatinine levels and blood urea nitrogen levels and alleviated renal pathological changes. Gene Ontology (GO) and KEGG pathway analyses of RNA sequencing data showed that TLYS decoction had significant effects on biological processes, cellular components and molecular functions in UUO rats and that the phagosome (a membrane source in the early stages of autophagy), lysosome (an important component of autolysosome), and oxidation pathways (which contribute to mitochondrial function) might be related to the antifibrotic effects of TLYS decoction. Moreover, we found significant mitochondrial function impairment, including a decreased mitochondrial membrane potential (MMP) and an imbalance in mitochondrial dynamics, excessive oxidative stress, and activation of Pink1/Parkin-mediated mitophagy in UUO rats. Treatment with TLYS decoction significantly increased the MMP, normalized mitochondrial dynamics and ameliorated renal injury. Moreover, TLYS alleviated the mitophagy clearance deficiency. In conclusion, our study showed that TLYS decoction can ameliorate mitochondrial dynamics by reducing oxidative stress and regulating mitophagy, thereby relieving renal injury, protecting renal function, and reducing renal fibrosis. This study provides support for the application of and further research on TLYS decoction.

Hypertension as an atypical presentation of unilateral ureteral obstruction

Ureteral obstruction (ureteropelvic or ureterovesical junction obstruction) is frequently diagnosed during the workup investigation of an asymptomatic infant or child with upper urinary tract dilatation, commonly identified in a prenatal ultrasound. In older children, recurrent lumbar pain is a red flag for ureteral obstruction. Although less frequent, hypertension may be the initial and only manifestation of ureteral obstruction. The authors present two pediatric cases of unilateral ureteral obstruction with hypertension, in which the surgical treatment of the obstruction leads to blood pressure normalisation. In all pediatric age groups, a systematic investigation for secondary causes of hyperten‑ sion is of paramount importance. In some cases, especially those of an obstructive nature, early surgical management can be curative, with normalization of blood pressure levels and prevention of renal injury.

The changes of the tubular epithelium phenotype in the contralateral kidney nephrons while developing unilateral ureteral obstruction: an experimental study

Introduction. The high prevalence of renal diseases caused by urinary tract obstruction led to the need for experimental research of compensatory and pathological processes with kidney injury. It is also of relevance to study key mechanisms providing a compensatory function of the contralateral kidney for early diagnosis, treatment, and prognosis of obstructive renal diseases.Purpose of the study. To examine epithelial nephron cells phenotype dynamics changes in contralateral kidney using unilateral ureteral obstruction experimental model.Materials and methods. Model of unilateral ureteral obstruction was established using adult rabbits. The studies were carried out on days 7, 14 and 21 of complete obstruction of the left ureter. Immunophenotyping was performed on contralateral kidney tissue samples using epithelial (cytokeratin 7, E-cadherin) and mesenchymal (vimentin, α-smooth muscle actin) markers.Results. The contralateral kidney under additional load can maintain the morphological and functional characteristics of the nephron for a long time. The first transmogrify signs in the nephron epithelium phenotype were detected by day 21 as the diffuse appearance of mesenchymal marker vimentin with unaltered visualization of epithelial phenotype markers.Conclusion. The results obtained allow us to assume that the compensatory reserve of the contralateral kidney is gradually decreasing when the duration of the obstruction increases. Thus, the likelihood of developing negative disorders increases.

Renoprotective Effects of Maslinic Acid on Experimental Renal Fibrosis in Unilateral Ureteral Obstruction Model via Targeting MyD88

Maslinic acid (MA), also named crategolic acid, is a pentacyclic triterpene extracted from fruits and vegetables. Although various beneficial pharmacological effects of MA have been revealed, its effect on renal fibrosis remains unclear. This study was designed to clarify whether MA could attenuate renal fibrosis and determine the putative underlying molecular mechanisms. We demonstrated that MA-treated mice with unilateral ureteral obstruction (UUO) developed a histological injury of low severity and exhibited downregulated expression of fibrotic markers, including α-smooth muscle actin (α-SMA), vimentin, and fibronectin by 38, 44 and 40%, and upregulated expression of E-cadherin by 70% as compared with untreated UUO mice. Moreover, MA treatment restored the expression levels of α-SMA, connective tissue growth factor, and vimentin to 10, 7.8 and 38% of those induced by transforming growth factor (TGF)-β in NRK49F cells. MA decreased expression of Smad2/3 phosphorylation and Smad4 in UUO kidneys and TGF-β treated NRK49F cells (p < 0.05, respectively). Notably, MA specifically interferes with MyD88, an adaptor protein, thereby mitigating Smad4 nuclear expression (p < 0.01 compared to TGF-β treated group) and ameliorating renal fibrotic changes (p < 0.01 for each fibrotic markers compared to TGF-β induced cells). In addition, in the UUO model and lipopolysaccharide-induced NRK49F cells, MA treatment decreased the expression of IL-1β, TGF-α and MCP-1, ICAM-1, associated with the suppression of NF-κB signaling. These findings suggest that MA is a potential agent that can reduce renal interstitial fibrosis, to some extent, via targeting TGF-β/Smad and MyD88 signaling.