The SP1/SIRT1/ACLY signaling axis mediates fatty acid oxidation in renal ischemia-reperfusion-induced renal fibrosis.

Renal ischemia-reperfusion is the primary cause of acute kidney injury (AKI). Clinically, most patients who experience ischemia-reperfusion injury eventually progress gradually to renal fibrosis and chronic kidney disease (CKD). However, the underlying mechanism for AKI to CKD transition remain absent. Our study demonstrated that the downregulation of sirtuin 1 (Sirt1)-mediated fatty acid oxidation (FAO) facilitates IRI-induced renal fibrosis. The IRI animal model was established, and ribonucleic acid (RNA) sequencing was used to explore potential differentially expressed genes (DEGs) and pathways. The SIRT1 knockout mice were generated, and a recombinant adeno-associated virus that overexpresses SIRT1 was injected into mice to explore the function of SIRT1 in renal fibrosis induced by renal IRI. In vitro, hypoxia/reoxygenation (H/R) was used to establish the classical model of renal IRI and overexpression or knockdown of SIRT1 to investigate the SIRT1 function through lentiviral plasmids. The underlying molecular mechanism was explored through RNA sequencing, bioinformatics analysis, and chromatin immunoprecipitation assay. RNA sequencing analysis and western blot demonstrated that the expression of SIRT1 was significantly decreased in IRI mice. Overexpression of SIRT1 improved renal function and reduced lipid deposition and renal fibrosis. On the contrary, knockout of SIRT1 aggravated kidney injury and renal fibrosis. RNA sequencing, bioinformatics analysis, and chromatin immunoprecipitation assay mechanistically revealed that SIRT1 impairs the acetylation of histone H3K27 on the promoter region of ACLY, thereby impeding FAO activity and promoting renal fibrosis. Additionally, SP1 regulated FAO by directly modulating SIRT1 expression. Our findings highlight that downregulation of SIRT1-modulated FAO facilitated by the SP1/SIRT1/ACLY axis in the kidney increases IRI, suggesting SIRT1 to be a potential therapeutic target for renal fibrosis induced by renal IRI.

Wu H ，Wang L ，Kang P ，Zhou X ，Li W ，Xia Z ... -  《-》

The SIRT6/BAP1/xCT signaling axis mediates ferroptosis in cisplatin-induced AKI.

Cisplatin is extensively utilized in clinical settings for treating solid tumors; However, its use is restricted because of the kidney damage caused by side effects. Moreover, currently, no effective medications have been approved to prevent or treat acute kidney injury induced by cisplatin. Our research indicates that sirtuin 6 (SIRT6) can inhibit ferroptosis induced by cisplatin, and the use of SIRT6 agonists can alleviate acute kidney injury caused by cisplatin. An animal model of cisplatin-induced acute kidney injury (AKI) was established, followed by RNA sequencing to identify potential differentially expressed genes (DEGs) and associated pathways. To explore the role of SIRT6 in this model, SIRT6 knockout mice were generated, and recombinant adeno-associated virus was employed to achieve SIRT6 overexpression in the mice. In vitro, cells were cultured in a cisplatin-containing medium to establish a cisplatin-induced cell model. The function of SIRT6 was further investigated by overexpressing or knocking down the gene using lentiviral plasmids. To elucidate the underlying molecular mechanisms, we employed RNA sequencing, performed bioinformatics analyses, and conducted chromatin immunoprecipitation assays. RNA sequencing and Western blot analyses revealed a significant reduction in SIRT6 expression in mice with cisplatin-induced acute kidney injury (AKI). Enhancing SIRT6 expression improved renal function, reduced ferroptosis, and mitigated kidney damage, whereas SIRT6 knockout exacerbated kidney injury and heightened ferroptosis. Mechanistically, RNA sequencing, bioinformatics analysis, and chromatin immunoprecipitation assays demonstrated that SIRT6 inhibits ferroptosis by reducing the acetylation of histone H4K9ac at the BAP1 promoter. Furthermore, in vitro studies demonstrated that the SIRT6 agonist UBCS039 can alleviate cisplatin-induced acute kidney injury, highlighting its potential therapeutic role in mitigating cisplatin's damaging effects. However, further research is needed to fully elucidate the underlying mechanisms and to validate these findings in vivo. Our findings underscore the critical role of the SIRT6/BAP1/xCT axis in regulating ferroptosis, particularly via the downregulation of SIRT6, in the context of cisplatin-induced acute kidney injury (AKI). This suggests that SIRT6 could be a promising therapeutic target for treating cisplatin-induced AKI. However, additional research is required to explore the specific mechanisms and fully assess the therapeutic potential of SIRT6 in this context.

Yang S ，Chen L ，Din S ，Ye Z ，Zhou X ，Cheng F ，Li W ... -  《-》

Leucine-rich alpha-2-glycoprotein 1 deficiency suppresses ischemia-reperfusion injury-induced renal fibrosis.

Ischemia reperfusion injury (IRI) is a major cause of acute kidney injury (AKI) and ultimately leads to renal fibrosis, primarily via the transforming growth factor-β (TGF-β) pathway. Leucine-rich alpha-2-glycoprotein 1 (LRG1), a novel modulator of the TGF-β pathway, has been implicated in the modulation of renal fibrosis by affecting the TGF-β/Smad3 signaling axis. However, the role of LRG1 in the transition from AKI to chronic kidney disease (CKD) remains unclear. This study aimed to investigate the functional role of LRG1 during the remodeling phase post-IRI. Unilateral IRI was induced in C57BL/6J wild-type (WT) mice and systemic LRG1 knockout (KO) mice. In C57BL/6J WT mice, renal LRG1 mRNA expression was significantly elevated on the ischemia/reperfusion side compared to the sham side over a 28-day period. In contrast, LRG1 KO mice demonstrated significantly reduced renal fibrosis compared to WT mice on postoperative day 28. Additionally, renal mRNA expression of TGF-β and associated pro-fibrotic genes was diminished in LRG1 KO mice compared to WT mice. Consequently, LRG1 KO mice exhibited attenuated IRI-induced chronic fibrosis. These findings indicate that LRG1 is involved in the pathogenesis of the transition from AKI to CKD and may be a potential therapeutic target.

Okami N ，Wakui H ，Azushima K ，Miyazawa T ，Kubo E ，Tsukamoto S ，Sotozawa M ，Taguchi S ，Urate S ，Ishiga K ，Kinguchi S ，Kanaoka T ，Tamura K ... -  《Scientific Reports》

Deletion of lymphotoxin-β receptor (LTβR) protects against acute kidney injury by PPARα pathway.

Recent data has shown a considerable advancement in understanding the role of lymphotoxin-β receptor (LTβR) in inflammation. However, the functions and underlying mechanisms of LTβR in acute kidney injury (AKI) remain largely unknown. AKI was induced in mice by renal ischemia-reperfusion (I/R). HK-2 cells and primary renal tubular epithelial cells (RTECs) were subjected to hypoxia/reoxygenation (H/R) injury. The effects of LTβR depletion were examined in mice, as well as primary RTECs. Bone marrow chimeric mice was generated to determine whether the involvement of LTβR expression by parenchymal cells or bone marrow derived cells contributes to renal injury during AKI. RNA sequencing techniques were employed to investigate the mechanism via which LTβR signaling provides protection against I/R-induced AKI RESULTS: LTβR expression was downregulated both in vivo and in vitro models of AKI. Moreover, depletion of LTβR decreased renal damage and inflammation in I/R-induced AKI. We also found that LTβR deficient mice engrafted with wild type bone marrow had significantly less tubular damage, implying that LTβR in renal parenchymal cells may play dominant role in I/R-induced AKI. RNA sequencing indicated that the protective effect of LTβR deletion was associated with activation of PPARα signaling. Furthermore, upregulation of PPARα was observed upon depletion of LTβR. PPARα inhibitor, GW6471, aggravated the tubular damage and inflammation in LTβR-/- mice following I/R injury. Then we further demonstrated that LTβR depletion down-regulated non-canonical NF-κB and Bax/Bcl-2 apoptosis pathway through PPARα. Our results suggested that the LTβR/PPARα axis may be a potential therapeutic target for the treatment of AKI.

Wang Z ，Cheng Y ，Fan J ，Luo R ，Xu G ，Ge S ... -  《-》

Jia Wei Qingxin Lotus Seed Drink ameliorates epithelial mesenchymal transition injury in diabetic kidney disease via inhibition of JMJD1C/SP1/ZEB1 signaling pathway.

Diabetic kidney disease (DKD) is one of the most common microvascular complications in patients with diabetes mellitus. In this condition, renal tubular epithelial mesenchymal transition (EMT) is an important factor accelerating the progression of DKD and a major cause of renal fibrosis and end-stage renal disease. However, the therapeutic effect is unsatisfactory because of the lack of effective drugs. Jia Wei Qingxin Lotus Seed Drink (QISD) is a traditional Chinese medicine compound formula that has shown to be effective in the clinical treatment of DKD. However, the potential of QISD in DKD-EMT treatment has yet to be fully explored. This study aimed to investigate the role of QISD in ameliorating DKD-EMT injury and its mechanism. The active ingredients of QISD were identified via ultra-performance liquid chromatography-mass spectrometry/mass spectrometry (UHPLC-MS/MS). A DKD mouse model was constructed by high-fat diet feeding and intraperitoneal injection of STZ (60 mg/kg), and QISD (14.46, 28.92, and 57.84 g/kg/day) was administered by gavage for 12 consecutive weeks. Dapagliflozin (1 mg/kg/d) was used as a positive control. Renal pathological damage was observed by HE, PAS, and Masson staining. The expression levels of EMT-related proteins and pathway proteins were detected via immunohistochemistry, RT-qPCR, and western blot. In in vitro experiments, EMT injury was induced in human kidney tubular epithelial cells (HK-2) by using lipopolysaccharide (LPS). A combination of CCK8 assay, wound healing assay, small-molecule inhibitor intervention, and overexpression lentiviral transfection was used to investigate the effects of QISD on cell migration ability, adhesion ability, fibrotic factor formation, and mesenchymal properties. Animal experiments showed that QISD improved blood glucose, body weight, symptoms of excessive drinking and eating, and renal pathological injury in mice, reduced extracellular matrix deposition, delayed renal EMT injury, and inhibited the activation of the histone demethylase JMJD1C. UHPLC-MS/MS and molecular docking indicated that baicalin, wogonoside, oroxylin A-7-O-β-D-glucuronide, and glulisine A found in QISD could bind to JMJD1C. The ameliorating effect of QISD on DKD-EMT injury might be related to JMJD1C. The improvement of DKD-EMT injury by QISD was accompanied by the reduction of SP1 and ZEB1 expression. The SP1 overexpression not only reversed the therapeutic effect of JIB-04, an inhibitor of JMJD1C, on DKD-EMT but also exacerbated the expression of ZEB1 and downstream EMT-related factors. Thus, QISD might affect the expression of the epithelial marker E-cadherin by inhibiting the JMJD1C/SP1/ZEB1 signaling pathway, consequently preventing the transformation of epithelial cells to mesenchymal cells and ameliorating DKD-EMT injury. This study was the first to demonstrate that QISD might ameliorate DKD-EMT injury by inhibiting the JMJD1C/SP1/ZEB1 signaling pathway. These findings provide strong pharmacologic evidence for the clinical use of QISD in the treatment of DKD.

Xie J ，Lin H ，Jin F ，Luo Y ，Yang P ，Song J ，Yao W ，Lin W ，Yuan D ，Zuo A ，Sun J ，Wang M ... -  《-》