7-Hydroxycoumarin protects against cisplatin-induced acute kidney injury by inhibiting necroptosis and promoting Sox9-mediated tubular epithelial cell proliferation

Background7-Hydroxycoumarin (7-HC), also known as umbelliferon, is commonly found in Chinese herbs (e.g. Eucommiae Cortex, Prunellae Spica, Radix Angelicae Biseratae). Previous laboratory studies have indicated that 7-HC has anti-inflammatory, anti-oxidative, and anti-tumor effects. Cisplatin is a widely used chemotherapeutic agent for cancer. Nephrotoxicity is one of the limiting side effects of cisplatin use.PurposeThis study aimed to evaluate the renoprotective effect of 7-HC in a cisplatin-induced acute kidney injury (AKI) mouse model.MethodsAKI was induced in male C57BL/6 mice (aged 6–8 weeks) by a single intraperitoneal injection of cisplatin at 20 mg/kg. The mice received 7-HC at 30, 60, and 90 mg/kg intraperitoneally before or after cisplatin administration. Renal function, necroptosis, and cell proliferation were measured. Mechanisms underlying the reno-protective effect of 7-HC were explored in renal tubular epithelial cells treated with or without cisplatin.ResultsIn-vivo experiments showed that 7-HC significantly improved the loss in kidney function induced by cisplatin, as indicated by lower levels of serum creatinine and blood urea nitrogen, in AKI mice. Consistent herewith, cisplatin-induced tubular damage was alleviated by 7-HC as shown by morphological (periodic acid–Schiff staining) and kidney injury marker (KIM-1) analyses. We found that 7-HC suppressed renal necroptosis via the RIPK1/RIPK3/MLKL pathway and accelerated renal repair as evidenced by the upregulation of cyclin D1 in cisplatin-induced nephropathy. In-vitro experiments showed that knockdown of Sox9 attenuated the suppressive effect of 7-HC on KIM-1 and reversed the stimulatory effect of 7-HC on cyclin D1 expression in cisplatin-treated HK-2 cells, indicating that 7-HC may protect against AKI via a Sox9-dependent mechanism.Conclusion7-HC inhibits cisplatin-induced AKI by suppressing RIPK1/RIPK3/MLKL-mediated necroptosis and promoting Sox9-mediated tubular epithelial cell proliferation. 7-HC may serve as a preventive and therapeutic agent for AKI.     

TLR2 protects cisplatin-induced acute kidney injury associated with autophagy via PI3K/Akt signaling pathway

Toll-like receptors (TLRs), which are essential components of the innate immune response, play an important role in acute kidney injury (AKI). Toll-like receptor 2 (TLR2) is constitutively expressed in tubular epithelial cells of the kidney and participates in cisplatin-induced AKI. The autophagy is a dynamic catabolic process that maintains intracellular homeostasis, which is involved in the pathogenesis of AKI. Recent studies demonstrate that PI3K/Akt signaling pathway regulates autophagy in response to various stimuli. Therefore, we propose that cisplatin might activate TLR2, which subsequently phosphorylates PI3K/Akt, leading to enhanced autophagy of renal tubular epithelial cells and protecting cisplatin-induced AKI. We found that TLR2 expression was significantly increased in the kidney after the cisplatin treatment. TLR2-deficient mice exacerbated renal injury in cisplatin-induced AKI, with higher serum creatinine and blood urea nitrogen, more severe morphological injury compared with that of wild-type mice. In vitro, we found that inhibition of TLR2 reduced tubular epithelial cell autophagy after the cisplatin treatment. Mechanistically, TLR2 inhibited autophagy via activating PI3K/Akt signaling pathway in renal tubular epithelial cells after the cisplatin treatment. Take together, these results suggest that TLR2 may protect cisplatin-induced AKI by activating autophagy via PI3K/Akt signaling pathway.     

Mesenchymal-like progenitors derived from human embryonic stem cells promote recovery from acute kidney injury via paracrine actions

Background aimsThe engraftment of mesenchymal stem cells (MSCs) is reported to promote recovery of renal function in animal models of acute kidney injury (AKI). However, it is unknown whether mesenchymal-like progenitors (MPs) derived from human embryonic stem cells (hESCs) can mediate similar therapeutic effects. We investigated the responses of recipient renal tissue to engraftment of hESC-MPs and underlying mechanisms of these effects.MethodsWe measured blood urea nitrogen and creatinine levels of AKI mice with hESC-MPs transplantation and control mice. We performed renal morphology analysis by immunohistochemistry and electron microscopy to confirm the renoprotective effects of engrafted hESC-MPs. Proliferation, apoptosis and gene expression of tubular cells were also monitored by immunohistochemistry and real-time quantitative polymerase chain reaction to investigate the mechanisms that occurred.ResultsAfter transplantation of hESC-MPs into mice with cisplatin-induced AKI, improvements in renal function and recovery from tubular epithelial cell injury were observed. Engrafted hESC-MPs were localized to areas of injured kidney 5 days after cisplatin induction, where they promoted tubular cell proliferation and decreased kidney cell apoptosis. The beneficial effect was further confirmed by the capability of the engrafted cells to up-regulate renal gene expression of anti-inflammatory cytokines and pro-survival cytokines. Meanwhile, infusion of these cells reduced renal gene expression of pro-inflammatory cytokines and monocyte chemotactic protein-1, a chemokine that stimulates monocyte and macrophage infiltration.ConclusionsOur results show that infused hESC-MPs may promote recovery from AKI by regulating related cytokines.     

Lansoprazole promotes cisplatin-induced acute kidney injury via enhancing tubular necroptosis

Acute kidney injury (AKI) is the main obstacle that limits the use of cisplatin in cancer treatment. Proton pump inhibitors (PPIs), the most commonly used class of medications for gastrointestinal complications in cancer patients, have been reported to cause adverse renal events. However, the effect of PPIs on cisplatin-induced AKI remains unclear. Herein, the effect and mechanism of lansoprazole (LPZ), one of the most frequently prescribed PPIs, on cisplatin-induced AKI were investigated in vivo and in vitro. C57BL/6 mice received a single intraperitoneal (i.p.) injection of cisplatin (18 mg/kg) to induce AKI, and LPZ (12.5 or 25 mg/kg) was administered 2 hours prior to cisplatin administration and then once daily for another 2 days via i.p. injection. The results showed that LPZ significantly aggravated the tubular damage and further increased the elevated levels of serum creatinine and blood urea nitrogen induced by cisplatin. However, LPZ did not enhance cisplatin-induced tubular apoptosis, as evidenced by a lack of significant change in mRNA and protein expression of Bax/Bcl-2 ratio and TUNEL staining. Notably, LPZ increased the number of necrotic renal tubular cells compared to that by cisplatin treatment alone, which was further confirmed by the elevated necroptosis-associated protein expression of RIPK1, p-RIPK3 and p-MLKL. Furthermore, LPZ deteriorated cisplatin-induced inflammation, as revealed by the increased mRNA expression of pro-inflammatory factors including, NLRP3, IL-1β, TNF-α and caspase 1, as well as neutrophil infiltration. Consistently, in in vitro study, LPZ increased HK-2 cell death and enhanced inflammation, compared with cisplatin treatment alone. Collectively, our results demonstrate that LPZ aggravates cisplatin-induced AKI, and necroptosis may be involved in the exacerbation of kidney damage.     

Gypenoside XLIX protects against acute kidney injury by suppressing IGFBP7/IGF1R-mediated programmed cell death and inflammation

BackgroundAcute kidney injury (AKI), characterised by excessive inflammatory cell recruitment and programmed cell death, has a high morbidity and mortality; however, effective and specific therapies for AKI are still lacking.ObjectiveThis study aimed to evaluate the renoprotective effects of gypenoside XLIX (Gyp XLIX) in AKI.MethodsThe protective effects of Gyp XLIX were tested in two AKI mouse models established using male C57BL/6 mice (aged 6–8 weeks) by a single intraperitoneal injection of cisplatin (20 mg/kg) or renal ischemia-reperfusion for 40 min. Gyp XLIX was administered intraperitoneally before cisplatin administration or renal ischemia-reperfusion. Renal function, tubular injury, renal inflammation and programmed cell death were evaluated. In addition, the renoprotective effects of Gyp XLIX were also evaluated in cisplatin- or hypoxia-treated tubular epithelial cells. The mechanisms underlying these effects were then explored using RNA sequencing.ResultsIn vivo, Gyp XLIX substantially suppressed the increase in serum creatinine and blood urea nitrogen levels. Moreover, tubular damage was alleviated by Gyp XLIX as shown by periodic acid-Schiff staining, electron microscopy and molecular analysis of KIM-1. Consistently, we found that Gyp XLIX suppressed renal necroptosis though the RIPK1/RIPK3/MLKL pathway. The anti-inflammatory and antinecroptotic effects were further confirmed in vitro. Mechanistically, RNA sequencing showed that Gyp XLIX markedly suppressed the levels of IGF binding protein 7 (IGFBP7). Co-immunoprecipitation and western blot analysis further showed that Gyp XLIX reduced the binding of IGFBP7 to IGF1 receptor (IGF1R). Additionally, picropodophyllin, an inhibitor of IGF1R, abrogated the therapeutic effects of Gyp XLIX on cisplatin-induced renal cell injury; this finding indicated that Gyp XLIX may function by activating IGF1R-mediated downstream signalling Additionally, we also detected the metabolic distribution of Gyp XLIX after injection; Gyp XLIX had a high concentration in the kidney and exhibited a long retention time. These findings may shed light on the application of Gyp XLIX for AKI treatment clinically.ConclusionGyp XLIX may serve as a potential therapeutic agent for AKI treatment via IGFBP7/ IGF1R-dependent mechanisms.     

Intra-renal arterial injection of autologous bone marrow mesenchymal stromal cells ameliorates cisplatin-induced acute kidney injury in a rhesus Macaque mulatta monkey model

BackgroundClinically, acute kidney injury (AKI) is a potentially devastating condition for which no specific therapy improves efficacy of the repair process. Bone marrow mesenchymal stromal cells (BM-MSCs) are proven to be beneficial for the renal repair process after AKI in different experimental rodent models, but their efficacy in large animals and humans remains unknown. This study aims to assess the effect of autologous rhesus Macaque mulatta monkey BM-MSC transplantation in cisplatin-induced AKI.MethodsWe chose a model of AKI induced by intravenous administration of 5 mg/kg cisplatin. BM-MSCs were transplanted through intra-arterial injection. The animals were followed for survival, biochemistry analysis and pathology.ResultsTransplantation of 5 × 10⁶ cells/kg ameliorated renal function during the first week, as shown by significantly lower serum creatinine and urea values and higher urine creatinine and urea clearance without hyponatremia, hyperkalemia, proteinuria and polyuria up to 84 d compared with the vehicle and control groups. The superparamagnetic iron oxide nanoparticle-labeled cells were found in both the glomeruli and tubules. BM-MSCs markedly accelerated Foxp3+ T-regulatory cells in response to cisplatin-induced damage, as revealed by higher numbers of Foxp3+ cells within the tubuli of these monkeys compared with cisplatin-treated monkeys in the control and vehicle groups.ConclusionsThese data demonstrate that BM-MSCs in this unique large-animal model of cisplatin-induced AKI exhibited recovery and protective properties.     

Farnesoid X Receptor Ligand Prevents Cisplatin-Induced Kidney Injury by Enhancing Small Heterodimer Partner

The farnesoid X receptor (FXR) is mainly expressed in liver, intestine and kidney. We investigated whether 6-ethyl chenodeoxycholic acid (6ECDCA), a semisynthetic derivative of chenodeoxycholic aicd (CDCA, an FXR ligand), protects against kidney injury and modulates small heterodimer partner (SHP) in cisplatin-induced kidney injury. Cisplatin inhibited SHP protein expression in the kidney of cisplatin-treated mice and human proximal tubular (HK2) cells; this effect was counteracted by FXR ligand. Hematoxylin and eosin staining revealed the presence of tubular casts, obstructions and dilatations in cisplatin-induced kidney injury, which was attenuated by FXR ligand. FXR ligand also attenuated protein expression of transforming growth factor-β1 (TGF-β1), Smad signaling, and the epithelial-to-mesenchymal transition process, inflammatory markers and cytokines, and apoptotic markers in cisplatin-treated mice. Cisplatin induced NF-κB activation in HK2 cell; this effect was attenuated by pretreatment with FXR ligand. In SHP knockdown by small interfering RNA, cisplatin-induced activation of TGF-β1, p-JNK and Bax/Bcl-2 ratio was not attenuated, while SHP overexpression and FXR ligand inhibited expression of these proteins in cisplatin-pretreated HK2 cells. In conclusion, FXR ligand, 6ECDCA prevents cisplatin-induced kidney injury, the underlying mechanism of which may be associated with anti-fibrotic, anti-inflammatory, and anti-apoptotic effects through SHP induction.     

Inhibition of hepatocyte nuclear factor 1β contributes to cisplatin nephrotoxicity via regulation of nf-κb pathway

Cisplatin nephrotoxicity has been considered as serious side effect caused by cisplatin-based chemotherapy. Recent evidence indicates that renal tubular cell apoptosis and inflammation contribute to the progression of cisplatin-induced acute kidney injury (AKI). Hepatocyte nuclear factor 1β (HNF1β) has been reported to regulate the development of kidney cystogenesis, diabetic nephrotoxicity, etc However, the regulatory mechanism of HNF1β in cisplatin nephrotoxicity is largely unknown. In the present study, we examined the effects of HNF1β deficiency on the development of cisplatin-induced AKI in vitro and in vivo. HNF1β down-regulation exacerbated cisplatin-induced RPTC apoptosis by indirectly inducing NF-κB p65 phosphorylation and nuclear translocation. HNF1β knockdown C57BL/6 mice were constructed by injecting intravenously with HNF1β-interfering shRNA and PEI. The HNF1β scramble and knockdown mice were treated with 30 mg/kg cisplatin for 3 days to induce acute kidney injury. Cisplatin treatment caused increased caspase 3 cleavage and p65 phosphorylation, elevated serum urea nitrogen and creatinine, and obvious histological damage of kidney such as fractured tubules in control mice, which were enhanced in HNF1β knockdown mice. These results suggest that HNF1β may ameliorate cisplatin nephrotoxicity in vitro and in vivo, probably through regulating NF-κB signalling pathway.     

ERK-mediated suppression of cilia in cisplatin-induced tubular cell apoptosis and acute kidney injury

In kidneys, each tubular epithelial cell contains a primary cilium that protrudes from the apical surface. Ciliary dysfunction was recently linked to acute kidney injury (AKI) following renal ischemia–reperfusion. Whether ciliary regulation is a general pathogenic mechanism in AKI remains unclear. Moreover, the ciliary change during AKI and its underlying mechanism are largely unknown. Here we examined the change of primary cilium and its role in tubular cell apoptosis and AKI induced by cisplatin, a chemotherapy agent with notable nephrotoxicity. In cultured human proximal tubular HK-2 epithelial cells, cilia became shorter during cisplatin treatment, followed by apoptosis. Knockdown of Kif3a or Polaris (cilia maintenance proteins) reduced cilia and increased apoptosis during cisplatin treatment. We further subcloned HK-2 cells and found that the clones with shorter cilia were more sensitive to cisplatin-induced apoptosis. Mechanistically, cilia-suppressed cells showed hyperphosphorylation or activation of ERK. Inhibition of ERK by U0126 preserved cilia during cisplatin treatment and protected against apoptosis in HK-2 cells. In C57BL/6 mice, U0126 prevented the loss of cilia from proximal tubules during cisplatin treatment and protected against AKI. U0126 up-regulated Polaris, but not Kif3a, in kidney tissues. It is suggested that ciliary regulation by ERK plays a role in cisplatin-induced tubular apoptosis and AKI.     

Microvesicles derived from mesenchymal stem cells enhance survival in a lethal model of acute kidney injury

Several studies demonstrated that treatment with mesenchymal stem cells (MSCs) reduces cisplatin mortality in mice. Microvesicles (MVs) released from MSCs were previously shown to favor renal repair in non lethal toxic and ischemic acute renal injury (AKI). In the present study we investigated the effects of MSC-derived MVs in SCID mice survival in lethal cisplatin-induced AKI. Moreover, we evaluated in vitro the effect of MVs on cisplatin-induced apoptosis of human renal tubular epithelial cells and the molecular mechanisms involved. Two different regimens of MV injection were used. The single administration of MVs ameliorated renal function and morphology, and improved survival but did not prevent chronic tubular injury and persistent increase in BUN and creatinine. Multiple injections of MVs further decreased mortality and at day 21 surviving mice showed normal histology and renal function. The mechanism of protection was mainly ascribed to an anti-apoptotic effect of MVs. In vitro studies demonstrated that MVs up-regulated in cisplatin-treated human tubular epithelial cells anti-apoptotic genes, such as Bcl-xL, Bcl2 and BIRC8 and down-regulated genes that have a central role in the execution-phase of cell apoptosis such as Casp1, Casp8 and LTA. In conclusion, MVs released from MSCs were found to exert a pro-survival effect on renal cells in vitro and in vivo, suggesting that MVs may contribute to renal protection conferred by MSCs.     

PSTPIP2 inhibits cisplatin-induced acute kidney injury by suppressing apoptosis of renal tubular epithelial cells

Cisplatin (CP) is an effective chemotherapeutic agent widely used in the treatment of various solid tumours. However, CP nephrotoxicity is an important limitation for CP use; currently, there is no method to ameliorate cisplatin-induced acute kidney injury (AKI). Recently, we identified a specific role of proline–serine–threonine phosphatase-interacting protein 2 (PSTPIP2) in cisplatin-induced AKI. PSTPIP2 was reported to play an important role in a variety of diseases. However, the functions of PSTPIP2 in experimental models of cisplatin-induced AKI have not been extensively studied. The present study demonstrated that cisplatin downregulated the expression of PSTPIP2 in the kidney tissue. Administration of AAV-PSTPIP2 or epithelial cell-specific overexpression of PSTPIP2 reduced cisplatin-induced kidney dysfunction and inhibited apoptosis of renal tubular epithelial cells. Small interfering RNA-based knockdown of PSTPIP2 expression abolished PSTPIP2 regulation of epithelial cell apoptosis in vitro. Histone acetylation may impact gene expression at the epigenetic level, and histone deacetylase (HDAC) inhibitors were reported to prevent cisplatin-induced nephrotoxicity. The UCSC database was used to predict that acetylation of histone H3 at lysine 27 (H3K27ac) induces binding to the PSTPIP2 promoter, and this prediction was validated by a ChIP assay. Interestingly, an HDAC-specific inhibitor (TSA) was sufficient to potently upregulate PSTPIP2 in epithelial cells. Histone acetylation-mediated silencing of PSTPIP2 may contribute to cisplatin nephrotoxicity. PSTPIP2 may serve as a potential therapeutic target in the prevention of cisplatin nephrotoxicity.Subject terms: Cancer, Cancer prevention     

Fibulin7 aggravates calcium oxalate-induced acute kidney injury by binding to calcium oxalate crystals

Fibulin7 (Fbln7) is a matricellular protein that is structurally similar to short fibulins but does not possess elastogenic abilities. Fbln7 is localized on the cell surface of the renal tubular epithelium in the adult kidney. We previously reported that Fbln7 binds artificial calcium phosphate particles in vitro, and that heparin counteracts this binding by releasing Fbln7 from the cell surface. Fbln7 gene (Fbln7) deletion in vivo decreased interstitial fibrosis and improved renal function in a high phosphate diet-induced chronic kidney disease mouse model. However, the contribution of Fbln7 during acute injury response remains largely unknown. We hypothesized that Fbln7 serves as an exacerbating factor in acute kidney injury (AKI). We employed three AKI models in vivo and in vitro, including unilateral ureteral obstruction (UUO), cisplatin-induced AKI, and calcium oxalate (CaOx)-induced AKI. Here, we report that Fbln7KO mice were protected from kidney damage in a CaOx-induced AKI model. Using HEK293T cells, we found that Fbln7 overexpression enhanced the CaOx-induced upregulation of EGR1 and LAMB3, and that heparin treatment canceled this effect. Interestingly, the protective function observed in Fbln7KO kidneys was limited to the CaOx-induced AKI model, while Fbln7KO mice were not protected against UUO-induced renal fibrosis or cisplatin-induced renal tubular damage. Taken together, our study indicates that Fbln7 mediates the local deposition of CaOx and damages the renal tubular epithelium. Releasing Fbln7 from the cell surface via heparin/heparin derivatives or Fbln7 inhibitory antibodies may provide a general strategy to mitigate calcium crystal-induced kidney injuries.     

miR-21-5p in extracellular vesicles obtained from adipose tissue-derived stromal cells facilitates tubular epithelial cell repair in acute kidney injury

Background aimsAcute kidney injury (AKI) is often associated with poor patient outcomes. Extracellular vesicles (EVs) have a marked therapeutic effect on renal recovery. This study sought to explore the functional mechanism of EVs from adipose tissue-derived stromal cells (ADSCs) in tubular epithelial cell (TEC) repair in AKI.MethodsADSCs were cultured and EVs were isolated and identified. In vivo and in vitro AKI models were established using lipopolysaccharide (LPS).ResultsEVs increased human kidney 2 (HK-2) cell viability; decreased terminal deoxynucleotidyl transferase dUTP nick end labeling-positive cells and levels of kidney injury molecule 1, cleaved caspase-1, apoptosis-associated speck-like protein containing a CARD, gasdermin D-N, IL-18 and IL-1β; and elevated pro-caspase-1. EVs carried miR-21-5p into LPS-induced HK-2 cells. Silencing miR-21-5p partly eliminated the ability of EVs to suppress HK-2 cell pyroptosis and inflammation. miR-21-5p targeted toll-like receptor 4 (TLR4) and inhibited TEC pyroptosis and inflammation after AKI by inhibiting TLR4. TLR4 overexpression blocked the inhibitory effects of EVs on TEC pyroptosis and inflammation. EVs suppressed the nuclear factor-κB/NOD-like receptor family pyrin domain-containing 3 (NF-κB/NLRP3) pathway via miR-21-5p/TLR4. Finally, AKI mouse models were established and in vivo assays verified that ADSC-EVs reduced TEC pyroptosis and inflammatory response and potentiated cell repair by mediating miR-21-5p in AKI mice.ConclusionsADSC-EVs inhibited inflammation and TEC pyroptosis and promoted TEC repair in AKI by mediating miR-21-5p to target TLR4 and inhibiting the NF-κB/NLRP3 pathway.     

ET-1 deletion from endothelial cells protects the kidney during the extension phase of ischemia/reperfusion injury

BackgroundThe prognosis of patients after acute kidney injury (AKI) is poor and treatment is limited. AKI is mainly caused by renal ischemia/reperfusion injury (IRI). During the extension phase of IRI, endothelial damage may participate in ischemia and inflammation. Endothelin-1 (ET-1) which is mostly secreted by endothelial cells is an important actor of IRI, particularly through its strong vasoconstrictive properties. We aimed to analyze the specific role of ET-1 from the endothelial cells in AKI.MethodsWe used mice lacking ET-1 in the vascular endothelial cells (VEETKO). We induced IRI in VEETKO mice and wild type controls by clamping both kidneys for 30 min. Sham operated mice were used as controls. Mice were sacrificed one day after IRI in order to investigate the extension phase of IRI. Kidney function was assessed based on serum creatinine concentration. Levels of expression of ET-1, its receptor ET_A, protein kinase C, eNOS, E-Cadherin and inflammation markers were evaluated by real time PCR or western blot. Tubular injury was scored on periodic acid Schiff stained kidney preparations. Lumen and wall area of small intrarenal arteries were measured on kidney slices stained for alpha smooth muscle cell actin. Oxidative stress, macrophage infiltration and cell proliferation was evaluated on slices stained for 8-hydroxy-2′-deoxyguanosine, F4/80 and PCNA, respectively.ResultsIRI induced kidney failure and increased ET-1 and ET_A receptor expression. This was accompanied by tubular injury, wall thickening and reduction of lumen area/wall area ratio of small renal arteries, increased oxidative stress and inflammation. These parameters were attenuated in VEETKO mice.ConclusionOur results suggest that suppression of ET-1 from the endothelial cells attenuates IRI kidney injury. Blocking ET-1 effects may represent a therapeutic strategy in the management of AKI.     

SAP130 released by damaged tubule drives necroinflammation via miRNA-219c/Mincle signaling in acute kidney injury

Tubules injury and immune cell activation are the common pathogenic mechanisms in acute kidney injury (AKI). However, the exact modes of immune cell activation following tubule damage are not fully understood. Here we uncovered that the release of cytoplasmic spliceosome associated protein 130 (SAP130) from the damaged tubular cells mediated necroinflammation by triggering macrophage activation via miRNA-219c(miR-219c)/Mincle-dependent mechanism in unilateral ureteral obstruction (UUO) and cisplatin-induced AKI mouse models, and in patients with acute tubule necrosis (ATN). In the AKI kidneys, we found that Mincle expression was tightly correlated to the necrotic tubular epithelial cells (TECs) with higher expression of SAP130, a damaged associated molecule pattern (DAMP), suggesting that SAP130 released from damaged tubular cells may trigger macrophage activation and necroinflammation. This was confirmed in vivo in which administration of SAP130-rich supernatant from dead TECs or recombinant SAP130 promoted Mincle expression and macrophage accumulation which became worsen with profound tubulointerstitial inflammation in LPS-primed Mincle WT mice but not in Mincle deficient mice. Further studies identified that Mincle was negatively regulated via miR-219c-3p in macrophages as miR-219c-3p bound Mincle 3′-UTR to inhibit Mincle translation. Besides, lentivirus-mediated renal miR-219c-3p overexpression blunted Mincle and proinflammatory cytokine expression as well as macrophage infiltration in the inflamed kidney of UUO mice. In conclusion, SAP130 is released by damaged tubules which elicit Mincle activation on macrophages and renal necroinflammation via the miR-219c-3p-dependent mechanism. Results from this study suggest that targeting miR-219c-3p/Mincle signaling may represent a novel therapy for AKI.Subject terms: Cell death and immune response, Acute kidney injury     

Dexpanthenol improved stem cells against cisplatin-induced kidney injury by inhibition of TNF-α, TGFβ-1, β-catenin,and fibronectin pathways

IntroductionCisplatin interacts with DNA and induces an immunological response and reactive oxygen species, which are nephrotoxic mediators. Stem cells self-renew through symmetric divisions and can develop into other cell types due to their multipotency. Dexpanthenol has been proven to protect against renal injury.AimThis study aims to demonstrate that dexpanthenol could improve the effect of adipose-derived mesenchymal stem cells (ADMSC) against cisplatin-induced acute kidney injury.MethodsSixty male Sprague-Dawley rats were divided into 5 groups (N = 12): control, cisplatin, cisplatin & dexpanthenol, cisplatin & ADMSC, and cisplatin & dexpanthenol & ADMSCs. On the 5th day following cisplatin injection, half the rats in each group were sacrificed, and the other half were sacrificed on the 12th day. Histopathological examination, molecular studies (IL-6, Bcl2, TGFβ-1, Caspase-3, Fibronectin, and β-catenin), antioxidants (superoxide dismutase and catalase), and renal function were all investigated.ResultsIn contrast to cisplatin group, the dexpanthenol and ADMSCs treatments significantly decreased renal function and oxidative stress while significantly enhancing antioxidants. Dexpanthenol improved stem cells by significantly down-regulating caspase-3, IL-6, TGF-β1, Fibronectin, and β-catenin and significantly up-regulating Bcl2 and CD34, which reversed the cisplatin effect.ConclusionDexpanthenol enhanced ADMSCs' ability to protect against cisplatin-induced AKI by decreasing inflammation, apoptosis, and fibrosis.     

TAK1 mediates excessive autophagy via p38 and ERK in cisplatin‐induced acute kidney injury

The ability of cisplatin (cis‐diamminedichloroplatinum II) toxicity to induce acute kidney injury (AKI) has attracted people's attention and concern for a long time, but its molecular mechanisms are still widely unknown. We found that the expression of transforming growth factor‐β (TGF‐β)‐activated kinase 1 (TAK1) could be increased in kidneys of mice administrated with cisplatin. Autophagy is an evolutionarily conserved catabolic pathway and is involved in various acute and chronic injuries. Moreover, p38 MAPK (mitogen‐activated protein kinase) and ERK regulate autophagy in response to various stimuli. Therefore, our hypothesis is that cisplatin activates TAK1, which phosphorylates p38 and ERK, leading to excessive autophagy of tubular epithelial cells and thus exacerbating kidney damage. Here, BALB/c mice were intraperitoneally injected with a TAK1 inhibitor and were then administrated with sham or cisplatin at 20 mg/kg by intraperitoneal injection. Compared with mice in the vehicle cisplatin group, mice intraperitoneally injected with a TAK1 inhibitor were found to have lower serum creatinine and less tubular damage following cisplatin‐induced AKI. Furthermore, inhibition of TAK1 reduced p38 and Erk phosphorylation, decreased expression of LC3II and reversed the down‐regulation of P62 expression induced by cisplatin. The hypothesis was verified with tubular epithelial cells administrated with cisplatin in vitro. Finally, p38 inhibitor or ERK inhibitor abated autophagy activation and cell viability reduction in tubular epithelial cells treated with cisplatin plus TAK1 overexpression vector. Taken together, our results show that cisplatin activates TAK1, which phosphorylates p38 and ERK, leading to excessive autophagy of tubular epithelial cells that exacerbates kidney damage.     

Artesunate relieves acute kidney injury through inhibiting macrophagic Mincle-mediated necroptosis and inflammation to tubular epithelial cell

Artesunate is a widely used derivative of artemisinin for malaria. Recent researches have shown that artesunate has a significant anti-inflammatory effect on many diseases. However, its effect on acute kidney injury with a significant inflammatory response is not clear. In this study, we established a cisplatin-induced AKI mouse model and a co-culture system of BMDM and tubular epithelial cells (mTEC) to verify the renoprotective and anti-inflammatory effects of artesunate on AKI, and explored the underlying mechanism. We found that artesunate strongly down-regulated the serum creatinine and BUN levels in AKI mice, reduced the necroptosis of tubular cells and down-regulated the expression of the tubular injury molecule Tim-1. On the other hand, artesunate strongly inhibited the mRNA expression of inflammatory cytokines (IL-1β, IL-6 and TNF-α), protein levels of inflammatory signals (iNOS and NF-κB) and necroptosis signals (RIPK1, RIPK3 and MLKL) in kidney of AKI mouse. Notably, the co-culture system proved that Mincle in macrophage can aggravate the inflammation and necroptosis of mTEC induced by LPS, and artesunate suppressed the expression of Mincle in macrophage of kidney in AKI mouse. Overexpression of Mincle in BMDM restored the damage and necroptosis inhibited by artesunate in mTEC, indicating Mincle in macrophage is the target of artesunate to protect tubule cells in AKI. Our findings demonstrated that artesunate can significantly improve renal function in AKI, which may be related to the inhibition of Mincle-mediated macrophage inflammation, thereby reducing the damage and necroptosis to tubular cells that provide new option for the treatment of AKI.     

Neutral ceramidase deficiency protects against cisplatin-induced acute kidney injury

Cisplatin is a commonly used chemotherapeutic for the treatment of many solid organ cancers; however, its effectiveness is limited by the development of acute kidney injury (AKI) in 30% of patients. AKI is driven by proximal tubule cell death, leading to rapid decline in renal function. It has previously been shown that sphingolipid metabolism plays a role in regulating many of the biological processes involved in cisplatin-induced AKI. For example, neutral ceramidase (nCDase) is an enzyme responsible for converting ceramide into sphingosine, which is then phosphorylated to become sphingosine-1-phosphate, and our lab previously demonstrated that nCDase knockout (nCDase?/?) in mouse embryonic fibroblasts led to resistance to nutrient and energy deprivation–induced cell death via upregulation of autophagic flux. In this study, we further characterized the role of nCDase in AKI by demonstrating that nCDase?/? mice are resistant to cisplatin-induced AKI. nCDase?/? mice display improved kidney function, reduced injury and structural damage, lower rates of apoptosis, and less ER stress compared to wild-type mice following cisplatin treatment. Although the mechanism of protection is still unknown, we propose that it could be mediated by increased autophagy, as chloroquine treatment resensitized nCDase?/? mice to AKI development. Taken together, we conclude that nCDase may represent a novel target to prevent cisplatin-induced nephrotoxicity.     

The liver X receptor agonist TO901317 protects mice against cisplatin-induced kidney injury

Liver X receptors are in the nuclear receptor superfamily and are contained in the regulation of lipid and cholesterol metabolism. Besides, liver X receptors are considered crucial regulators of the inflammatory response and innate immunity. The current study evaluates the in vivo effects that the synthetic liver X receptor agonist TO901317 protects against cisplatin-induced kidney injury in mice. Mice received cisplatin administration through a single intraperitoneal injection (20 mg/kg in saline). And then the mice were treated with the TO901317 by daily gavage (10 mg/kg/day) 12 h postcisplatin administration, and cisplatin nephrotoxicity was evaluated. At 72 h after cisplatin treatment, elevated plasma urea and creatinine levels (P < 0.05) were evidenced which indicates the renal dysfunction of the vehicle-treated mice, consistent with tubular necrosis, protein cast, dilation of renal tubules, and desquamation of epithelial cells in renal tubules. In contrast, the severity of renal dysfunction and histological damage was reduced in TO901317 treated mice (P < 0.05). In accordance, circulating tumor necrosis factor alpha levels, renal tumor necrosis factor alpha, p47^phox, gp91^phox, and protein expression levels and COX-2 mRNA, renal monocyte chemoattractant protein 1, VACAM-1 mRNA and intercellular adhesion molecule-1 contents, and renal prostaglandin E₂ amounts, were higher in samples from cisplatin-treated mice in comparison with controls (P < 0.05) but attenuated in the TO901317 treatment group (P < 0.05). Taken together, treatment with the liver X receptor agonist TO901317 ameliorated the inflammatory response and oxidative stress in cisplatin-induced kidney injury in mice.