Atorvastatin attenuates experimental contrast-induced acute kidney injury: a role for TLR4/MyD88 signaling pathway

Objectives: To investigate the protective effect of different atorvastatin doses on contrast-induced acute kidney injury and the related mechanism.

Methods: Healthy male Sprague–Dawley (SD) rats were randomly divided into the blank control group, experimental control group and different-dose atorvastatin groups. A rat model of contrast-induced acute kidney injury was established. We detected changes in serum creatinine (Scr) and blood urea nitrogen (BUN) before and after model establishment, observed and scored renal tubular injury, analyzed rat renal cell apoptosis, and measure the expression of signal pathway proteins and downstream inflammatory factors.

Results: After contrast agent injection, the Scr and BUN levels of the experimental control group were significantly increased, the different doses applied in the atorvastatin group significantly reduced the Scr and BUN levels (p?p?p?p?Conclusion: Different atorvastatin doses have protective effects on contrast-induced acute renal tubular injury in rats, possibly by targeting TLR4, suppressing TLR4 expression, regulating the TLR4/Myd88 signaling pathway, and inhibiting the expression of downstream inflammatory factors.     

Isoliquiritigenin attenuates septic acute kidney injury by regulating ferritinophagy-mediated ferroptosis

Defined differently from apoptosis, necrosis, and autophagy, ferroptosis has been implicated in acute kidney injury (AKI) such as ischemia-reperfusion injury induced AKI, folic acid caused AKI and cisplatin induced AKI. However, whether ferroptosis is involved in LPS induced AKI could be remaining unclear and there is still a lack of therapies associated with ferroptosis in LPS induced AKI without side effects. This study aimed to elucidate the role of isoliquiritigenin (ISL) in ferroptosis of LPS-induced AKI. We used LPS to induce renal tubular injury, followed by treatment with ISL both in vitro and in vivo. Human renal tubular HK2 cells were pretreated with 50 μM or 100 μM ISL for 5 h before stimulation with 2 μg/mL LPS. Mice were administered a single dose of either 50 mg/kg ISL orally or 5 mg/kg ferroptosis inhibitor ferrostatin-1 intraperitoneally before 10 mg/kg LPS injection. We found that LPS could induce mitochondria injury of renal tubular presented as the shape of mitochondria appeared smaller than normal with increased membrane density and are faction or destruction of mitochondrial crista through scanning electron microscope. Ferrostatin-1 significantly protected mice against renal dysfunction and renal tubular damage in LPS-induced AKI. ISL inhibited Fe²⁺ and lipid peroxidation accumulation in LPS-stimulated HK2 cells. It also increased the expression of GPX4 and xCT, reduced the expression of HMGB1 and NCOA4 then attenuated mitochondria injury in renal tubular following LPS stimulation. These results indicated the potential role of ISL against ferritinophagy-mediated ferroptosis in renal tubular following LPS stimulation.     

Tetrahydrocurcumin protects against sepsis-induced acute kidney injury via the SIRT1 pathway

Sepsis-induced acute kidney injury (AKI) continues to be associated with poor outcomes in critical care patients. Previous research has revealed that tetrahydrocurcumin (THC) exerts renoprotective effects in multiple nephritic disorders by modulating inflammation and oxidative stress. However, the effects of THC on sepsis-induced AKI and the underlying mechanisms remain unclear. In this study, a mouse model of sepsis-induced AKI, generated by cecal ligation and puncture operation, was used to investigate the protective effects of THC and the role of SIRT1. Histological manifestation and TUNEL analysis were observed to determine the severity of kidney damage. Levels of BUN, SCr, KIM-1, and UAlb/Cr were calculated to assess the renal function. Expressions of IL-1β, IL-6, and TNF-α were measured to evaluate the inflammatory response. MDA content, SOD, GSH, CAT, and GPx activities and DHE staining were analyzed to estimate the degree of oxidative stress. Protein expressions of SIRT1, Ac-p65, and Ac-foxo1 were detected to explore the underlying mechanisms. We observed that THC not only increased the survival rate, improved the kidney function and ameliorated the renal histological damage of septic mice, but also inhibited inflammatory response, prohibited oxidative stress, and prevented cell apoptosis in renal tissues in septic mice. Mechanistically, THC remarkably increased the expression of SIRT1, accompanied by decreased expressions of downstream molecules Ac-p65 and Ac-foxo1. Meanwhile, the beneficial effects of THC were clearly abolished by the SIRT1-specific inhibitor EX527. These results delineate that THC prevents sepsis-induced AKI by suppressing inflammation and oxidative stress through activating the SIRT1 signaling.Abbreviation: Ac-p65: acetylated p65; Ac-foxo 1: acetylated forkhead box O1; AKI: acute kidney injury; BUN: blood urea nitrogen; CAT: catalase; DHE: dihydroethidium; GPx: glutathione peroxidase; GSH: reduced glutathione; IL-1β: Interleukin-1 beta; IL-6: Interleukin-6; KIM-1: kidney injury molecule 1; MDA: malondialdehyde; SCr: serum creatinine; SIRT1: silent information regulator 1; SOD: superoxide dismutase; THC: tetrahydrocurcumin; TNF-α: tumor necrosis factor-alpha; TUNEL: TdT-mediated dUTP Nick-End Labeling; UAlb/Cr: urine micro albumin/creatinine.     

The predictive performance of the lactate clearance rate combined with the APACHE II score in the prediction of sepsis-associated acute kidney injury in 7 days

BackgroundThe purpose of this study was to evaluate the accuracy of the lactate clearance rate (LCR) combined with the Acute Physiology and Chronic Health Evaluation II (APACHE II) score in the prediction of sepsis-associated acute kidney injury (SAKI).MethodsSepsis patients were divided into the SAKI group and non-SAKI group. Arterial blood lactate was collected at 0 h (before treatment), 2 h, 4 h, 6 h, and 8 h (after treatment), and the LCR was calculated. The physiological parameters and laboratory test results were used to calculate the APACHE II score and the Sequential Organ Failure Assessment (SOFA) score. The receiver operating characteristic (ROC) curves of LCR, APACHE II score and SOFA score for predicting patients with SAKI were drawn. Two single indicators with high areas under the curves (AUCs) were selected to calculate the joint probability through regression analysis, and the prediction efficiency corresponding to each curve was analyzed.ResultsThere were significant differences in LCR between different groups and time periods (F^group=17.44, P^group ≤0.0001, F^time =11.71, P^time =0.0014). After 8 h of treatment, there was a significant difference in the overall compliance rate between the 2 groups (P<0.0001). In addition, after 24 h of treatment, the APACHE II score in the SAKI group was significantly higher than that in the non-SAKI group (P=0.0007), and SOFA score was also significantly higher than that in the non-SAKI group (P=0.0001). ROC curve showed that the 0–8 h LCR and APACHE II scores had a high predictive performance for the acute kidney injury (AKI) occurrence in sepsis patients, and AUCs were 0.7637 and 0.7517, respectively, while the combined AUC of the 2 indicators was 0.7975.ConclusionsThe 0–8 h LCR combined with APACHE II score can improve the early predictive value of SAKI, reduce the risk of AKI in patients with sepsis/septic shock, and reduce the social and family burden, which is worthy of clinical application.     

Paradigm shift in the role of uric acid in acute kidney injury

It has been known for decades that uric acid causes acute kidney injury by intratubular crystal precipitation and obstructing the renal tubules. Uric acid crystals stimulate inflammation and elicit immune responses in many disease conditions, including gouty arthritis. More recently, soluble uric acid has been reported to stimulate proliferation of vascular smooth muscle cells, inhibit endothelial function, cause renal vasoconstriction, impair renal blood flow autoregulation, and induce inflammatory response via crystal-independent mechanisms. This article examines the changing role for uric acid in acute kidney injury.     

Heme oxygenase-1 induction mitigates burn-associated early acute kidney injury via the TLR4 signaling pathway

ObjectivesEarly acute kidney injury (AKI) after burn contributes to disastrous prognoses for severely burned patients. Burn-induced renal oxidative stress and secondary proinflammatory mediator release contribute to early AKI development, and Toll-like receptor (TLR) 4 regulates inflammation. Heme oxygenase-1 (HO-1) is a stress-responsive enzyme that plays a vital role in protecting against ischemia-induced organ injury via its antioxidant properties and regulation of inflammation. We investigated the potential effect of HO-1 induction in preventing burn-induced early AKI and its related mechanism.MethodsA classic major-burn rat model was established using a 100 °C water bath, and hemin was injected intraperitoneally immediately after the injury to induce HO-1. Histological staining and blood tests were used to assess AKI progression based on structural changes and function. Renal levels of HO-1, oxidative stress, proinflammatory mediators and TLR4-related signals were detected using ELISA, immunostaining, qRT-PCR, and western blotting. The selective TLR4 inhibitor TAK242 and TLR4 inducer LPS were introduced to determine the roles of HO-1 in burn-related renal inflammation and the TLR4 pathway.ResultsHemin improved burn-induced renal histological damage and dysfunction, and this beneficial effect was related to reduced renal oxidative stress and the release of proinflammatory mediators, such as tumor necrosis factor-alpha (TNF-α), interleukin (IL)-1β, IL-6 and intracellular adhesion molecule-1 (ICAM-1). Hemin downregulated the expression of TLR4 and the subsequent phosphorylation of IKKα/β, IκBα, and NF-κB p65;. TAK242 exerted an effect similar to but weaker than hemin; and LPS reversed the antiinflammatory effect of hemin and the regulation of TLR4 signals. These results suggested that the TLR4 signaling pathway mediated the HO-1-facilitated regulation of renal inflammation after burn.ConclusionThe present study demonstrated that HO-1 induction prevented burn-induced early AKI by targeting renal inflammation, which was mediated via regulation of the TLR4/NF-κB signaling pathway.     

ERK信号通路在右美托咪定减轻小鼠神经母细胞瘤细胞氧化应激损伤中的作用

目的观察右美托咪定对过氧化氢(H_2O_2)所致小鼠神经母细胞瘤细胞(mouse neuroblastoma N2acells,N2a)氧化应激损伤的影响,探讨ERK信号通路的作用。方法在N2a细胞培养基中加入一定浓度的H_2O_2建立N2a细胞氧化应激损伤模型。将细胞分为五组:对照组(C组)、右美托咪定组(D组)、H_2O_2组(H组)、H_2O_2+右美托咪定组(HD组)、H_2O_2+右美托咪定+ERK抑制剂组(HDP组)。H组、HD组和HDP组给予200μmol/L的H_2O_2,HD组在H_2O_2处理前30min加入100ng/ml右美托咪定,HDP组在H_2O_2处理前30 min加入100ng/ml右美托咪定和20μmol/LERK抑制剂PD98059,D组在相应时点加入100ng/ml右美托咪定,C组给予等容量生理盐水。在H_2O_2刺激1h,检测细胞上清SOD活性,并分析ERK磷酸化水平;H_2O_2刺激4h,观察细胞生存、细胞形态学变化。结果与C组比较,H组N2a细胞生存率明显降低,细胞形态明显损伤,SOD活性明显下降(P0.05);与H组比较,HD组的细胞生存率明显升高,细胞形态明显改善,SOD活性明显升高,ERK磷酸化水平明显增强(P0.05);与HD组比较,HDP组细胞生存率明显降低,细胞形态明显恶化,SOD活性明显降低(P0.05)。C组和D组细胞生存率、细胞形态、SOD活性及ERK磷酸化水平差异无统计学意义。结论右美托咪定预处理能够减轻H_2O_2所致的N2a细胞氧化应激损伤,其机制可能是通过激活细胞内ERK信号通路和提高SOD活性。     

Levosimendan in rats decreases acute kidney injury after cardiopulmonary resuscitation by improving mitochondrial dysfunction

BackgroundAcute kidney injury (AKI), the most common complication after cardiac resuscitation, is highly prevalent and harmful. There is increasing evidence that levosimendan can improve cardiac output, increase renal blood flow, and prevent AKI. As a novel calcium sensitizer, levosimendan may exert its protective effect via mitochondria.MethodsRat models of asphyxia-induced cardiac arrest and cardiopulmonary resuscitation (CPR) were set up. Thirty healthy adult male SD rats were randomly divided into CPR group (CPR group, n=10), levosimendan-treated group (levo group, n=10), and sham-operated group (sham group, n=10). Twelve hours after CPR, serum renal function indicators were measured, the kidney injury and mitochondrial morphological changes were observed. Oxygen uptake of the mitochondria, mitochondrial adenosine triphosphate (ATP) and mitochondrial free Ca²⁺ concentration were measured. Oxidative stress-related indicator levels in rat kidney tissues were further detected to analyze the differences in apoptosis rates among these three groups. Mitochondrial optic atrophy 1 (Opa1), dynamin-related protein 1 (Drp1), and apoptosis-related proteins were detected using Western blotting.ResultsCompared with the sham group, the CPR group had a significant increase in renal tissue damage. PAS staining and HE stains confirmed that CPR led to renal histopathological damage and destruction of the mitochondrial structure. Levosimendan improved the histopathological and ultrastructural damages of kidneys. Further analysis revealed that mitochondrial ATP content, NADH dehydrogenase, succinate dehydrogenase/cytochrome C oxidase, superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (CSH-Px) decreased. Free Ca²⁺ concentration and malondialdehyde (MDA) significantly increased (all P<0.05) in the kidney tissues of rats in the CPR group. However, mitochondrial ATP content, NADH dehydrogenase, succinate dehydrogenase/cytochrome C oxidase, SOD, CAT, and CSH-Px increased, whereas free Ca²⁺ concentration and MDA decreased (all P<0.05) in the levo group. The apoptosis rate increased in the CPR group. There were significantly increased levels of Drp1 protein levels, and significantly decreased Opa1 expression (all P<0.05). However, the levo group showed the opposite effects (all P<0.05).ConclusionsLevosimendan can alleviate AKI following CPR, which may be achieved by improving mitochondrial dysfunction and suppressing the mitochondrial apoptosis pathway.     

The proteome microenvironment determines the protective effect of preconditioning in cisplatin-induced acute kidney injury

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Altered kidney function induced by SARS-CoV-2 infection and acute kidney damage markers predict survival outcomes of COVID-19 patients: a prospective pilot study

BackgroundLiterature with regard to coronavirus disease 2019 (COVID-19) associated morbidities and the risk factors for death are still emerging. In this study, we investigated the presence of kidney damage markers and their predictive value for survival among hospitalized subjects with COVID-19.MethodsForty-seven participants was included and grouped as: ‘COVID-19 patients before treatment’, ‘COVID-19 patients after treatment’, ‘COVID-19 patients under treatment in intensive care unit (ICU)’, and ‘controls’. Kidney function tests and several kidney injury biomarkers were compared between the groups. Cumulative rates of death from COVID-19 were determined using the Kaplan–Meier method. The associations between covariates including kidney injury markers and death from COVID-19 were examined, as well.ResultsSerum creatinine and cystatin C levels, urine Kidney Injury Molecule-1 (KIM-1)/creatinine ratio, and Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI), CKD-EPI cystatin C, and CKD-EPI creatinine–cystatin C levels demonstrated significant difference among the groups. The most significant difference was noted between the groups ‘COVID-19 patients before treatment’ and ‘COVID-19 patients under treatment in ICU’. Advancing age, proteinuria, elevated serum cystatin C, and urine KIM-1/creatinine ratio were all significant univariate correlates of death (p < 0.05, for all). However, only elevated urine KIM-1/creatinine ratio retained significance in an age, sex, and comorbidities adjusted multivariable Cox regression (OR 6.11; 95% CI: 1.22–30.53; p = 0.02), whereas serum cystatin C showing only a statistically non-significant trend (OR 1.42; 95% CI: 0.00–2.52; p = 0.09).ConclusionsOur findings clearly demonstrated the acute kidney injury related to COVID-19. Moreover, urine KIM-1/creatinine ratio was associated with COVID-19 specific death.     

Complement activation is a crucial driver of acute kidney injury in rhabdomyolysis

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Obesity,acute kidney injury and mortality in patients with sepsis: a cohort analysis

Although the prognostic effect of obesity has been studied in critically ill patients its impact on outcomes of septic patients and its role as a risk factor for acute kidney injury (AKI) is not consensual. We aimed to analyze the impact of obesity on the occurrence of AKI and on in-hospital mortality in a cohort of critically ill septic patients. This study is retrospective including 456 adult patients with sepsis admitted to the Division of Intensive Medicine of the Centro Hospitalar Lisboa Norte (Lisbon, Portugal) between January 2008 and December 2014. Obesity was defined as a body mass index of 30?kg/m² or higher. The Kidney Disease Improving Global Outcomes classification was used to diagnose and classify patients developing AKI. AKI occurred in 87.5% of patients (19.5% with stage 1, 22.6% with stage 2 and 45.4% with stage 3). Obese patients developed AKI more frequently than non-obese patients (92.8% versus 85.5%, p?=?.035; unadjusted OR 2.2 (95% CI: 1.04–4.6), p?=?.039; adjusted OR 2.31 (95% CI: 1.07–5.02), p?=?.034). The percentage of obese patients, however, did not differ between AKI stages (stage 1, 25.1%; stage 2, 28.6%; stage 3, 15.4%; p?=?.145). There was no association between obesity and mortality (p?=?.739). Of note, when comparing AKI patients with or without obesity in terms of in-hospital mortality there were also no significant differences between those groups (38.4% versus 38.4%, p?=?.998). Obesity was associated with the occurrence of AKI in critically ill patients with sepsis; however, it was not associated with in-hospital mortality.     

脑肠肽对脓毒症相关性肾损伤的保护作用研究

目的 探讨脑肠肽对内毒素所致大鼠脓毒症相关性肾损伤的影响.方法 健康雄性SD大鼠36只,随机分为3组：正常对照组,急性肾损伤（acute kidney injury,AKI）组,脑肠肽治疗组.采用内毒素静注制备脓毒症AKI模型,脑肠肽治疗组于造模前后30 min给予皮下注射脑肠肽（1.0mg/kg）,选择不同时间点（6 h、12 h、24 h）处死动物后留取血标本和肾组织,检测血清肌酐（SCr）、尿素氮（BUN）、血清肿瘤坏死因子-α（tumor necrosis factor-α,TNF-α）、观察肾组织的病理变化并检测肾脏组织中核因子κB的活化.结果 与同时间点比较,AKI组6h和12 h大鼠血清中TNF-α表达水平明显升高（P＜0.01）,24 h降至对照组水平（P＞0.05）,AKI组6h、12 h和24 h大鼠血清中BUN水平逐渐升高（P＜0.05）,24 h血清中SCr水平明显升高（P＜0.01）;AKI组24 h大鼠肾脏组织核因子κB p65核阳性率明显升高（P＜0.01）.脑肠肽治疗组对应时间点血清BUN和SCr水平较AKI组明显降低（P＜0.01）.TNF-α和核因子κB p65表达明显低于AKI组（P＜0.01）.病理显示脑肠肽治疗组大鼠肾损伤减轻,SCr、BUN、TNF-α、光镜检查均未见明显差异.结论 脑肠肽可通过抑制肾组织核因子κB的表达,下调TNF水平,对脓毒症相关性肾损伤发挥保护作用.