Sepsis-associated Acute Kidney Injury Research Articles

Circ_0006944 aggravates LPS-induced HK2 cell injury via modulating miR-205-5p/UBL4A pathway

Circular RNAs (circRNAs) has been manifested to be involved in the development of human diseases, including sepsis-associated acute kidney injury (SA-AKI). However, the function and mechanism of circ_0006944 in SA-AKI has not been validated. Lipopolysaccharide (LPS) was utilised to induce AKI cell model. Levels of genes and proteins were monitored by quantitative real-time polymerase chain reaction (qRT-PCR) and western blot. Cell counting kit 8 assay, EdU assay and flow cytometry were exploited to estimate cell proliferation and apoptosis. The concentrations of inflammation factors were measured via using ELISA assay. The levels of MDA and SOD were tested by the corresponding kits. The relationship between miR-205-5p and circ_0006944 or UBL4A was verified by dual-luciferase reporter assay and RIP assay. Circ_0006944 was overexpressed in SA-AKI patients, and interference of circ_0006944 restrained LPS-stimulated HK2 cell proliferation repression, apoptosis, inflammation and oxidative stress. Mechanistically, circ_0006944 could sponge miR-205-5p, and miR-205-5p interference counteracted circ_0006944 inhibition-mediated impact on the biological functions in LPS-induced HK2 cell. Additionally, UBL4A was targeted by miR-205-5p, and UBL4A overexpression also partially abolished the repressive impacts of miR-205-5p on LPS-triggered HK2 cell damage. Importantly, circ_0006944 sponged miR-205-5p to mediate the expression of UBL4A. Our outcomes identified that circ_0006944 exacerbated SA-AKI development via miR-205-5p/UBL4A axis, which might be a potential treatment and diagnosis biomarker for SA-AKI.

Galectin-3 Mediates Endotoxin Internalization and Caspase-4/11 Activation in Tubular Epithelials and Macrophages During Sepsis and Sepsis-Associated Acute Kidney Injury.

Besides being recognized by membrane receptor TLR4, lipopolysaccharide (LPS) can also be internalized into the cytosol and activate Caspase-4/11 pyroptotic pathways to further amplify inflammation in sepsis. The objective of this study was to investigate whether Galectin-3 (Gal3) could promote the uptake of LPS by governing RAGE or administering endocytosis, consequently activating Caspase 4/11 and mediating pyroptosis in sepsis-associated acute kidney injury (SA-AKI). By pinpointing Gal3, LPS, and EEA1 (endosome-marker) or LAMP1 (lysosome-marker) respectively, immunofluorescence discovered that Gal3 and LPS were mainly aggregated in early endosomes initially and translocated into lysosomes afterwards. In cells and animal models, Gal3 and the Caspase-4/11 pathways were simultaneously activated, and the overexpression of Gal3 could exacerbate pyroptosis, whereas inhibition of Gal3 or the knockdown of its expression could ameliorate pyroptosis, reduce the pathological changes of SA-AKI and improve the survival of the animals with SA-AKI. Silencing RAGE reduced pyroptosis in primary tubular epithelial cells (PTCs) activated by Gal3 and LPS but not in cells activated by Gal3 and outer membrane vesicles (with LPS inside), whereas pyroptosis in both was reduced by blockade of Gal3, indicating Gal3 promoted pyroptosis through both RAGE-dependent and RAGE-independent pathways. Our investigation further revealed a positive correlation between serum Gal3 and pyroptotic biomarkers IL-1 beta and IL-18 in patients with sepsis, and that serum Gal3 was an independent risk factor for mortality. Through our collective exploration, we unraveled the significant role of Gal3 in the internalization of LPS and the provocation of more intense pyroptosis, thus making it a vital pathogenic factor in SA-AKI and a possible therapeutic target.Gal3 enabled the internalization of endotoxin into endosomes and lysosomes via both RAGE-dependent (A) and RAGE-independent (B) pathways, leading to pyroptosis. The suppression of Gal3 curbed Caspase4/11 noncanonical inflammasomes and diminished sepsis and SA-AKI.

Association between volume status assessed by bioelectrical impedance analysis, lung ultrasound, or weight change and mortality in patients with sepsisassociated acute kidney injury receiving continuous kidney replacement therapy.

Fluid overload is an independent risk factor of mortality in patients with acute kidney injury (AKI) receiving continuous kidney replacement therapy (CKRT). However, the association between fluid status, as assessed by bioelectrical impedance analysis (BIA) or lung ultrasound, and survival in patients with AKI requiring CKRT has not been established. We analyzed 36 participants with sepsis-associated AKI who received CKRT at a tertiary hospital. The main exposures were volume surrogates: 1) overhydration normalized by extracellular water (OH/ECW, L/L) assessed by BIA, 2) the number of B-lines measured by lung ultrasound, and 3) weight change ([body weight at CKRT initiation - body weight at admission] × 100/body weight at admission). The primary outcome was the 28-day mortality. Seventeen participants (47.2%) died within 28 days. There were no significant correlations between OH/ECW and weight change (R2 = 0.040, p = 0.24), number of B-lines and OH/ECW (R2 = 0.056, p = 0.16), or weight change and number of B-lines (R2 = 0.014, p = 0.49). Kaplan-Meier analyses revealed that patients in the highest tertile of OH/ECW showed a significantly lower cumulative 28-day survival probability than the others (the lowest + middle tertiles). The survival probability of participants in the highest tertile of the number of B-lines or weight change did not differ from that of their counterparts. In a multivariate Cox proportional hazard model, the hazard ratio for the highest tertile of OH/ECW was 3.83 (95% confidence interval, 1.04-14.03). Volume overload assessed using BIA (OH/ECW) was associated with the 28-day survival rate in patients with sepsis-associated AKI who received CKRT.

SERUM HUMANIN IN PEDIATRIC SEPTIC SHOCK-ASSOCIATED MULTIPLE-ORGAN DYSFUNCTION SYNDROME.

Background: Multiple-organ dysfunction syndrome disproportionately contributes to pediatric sepsis morbidity. Humanin (HN) is a small peptide encoded by mitochondrial DNA and thought to exert cytoprotective effects in endothelial cells and platelets. We sought to test the association between serum HN (sHN) concentrations and multiple-organ dysfunction syndrome in a prospectively enrolled cohort of pediatric septic shock. Methods: Human MT-RNR2 ELISA was used to determine sHN concentrations on days 1 and 3. The primary outcome was thrombocytopenia-associated multiorgan failure (TAMOF). Secondary outcomes included individual organ dysfunctions on day 7. Associations across pediatric sepsis biomarker (PERSEVERE)-based mortality risk strata and correlation with platelet and markers of endothelial activation were tested. Results: One hundred forty subjects were included in this cohort, of whom 39 had TAMOF. The concentration of sHN was higher on day 1 relative to day 3 and among those with TAMOF phenotype in comparison to those without. However, the association between sHN and TAMOF phenotype was not significant after adjusting for age and illness severity in multivariate models. In secondary analyses, sHN was associated with presence of day 7 sepsis-associated acute kidney injury ( P = 0.049). Furthermore, sHN was higher among those with high PERSEVERE-mortality risk strata and correlated with platelet counts and several markers of endothelial activation. Conclusion: Future investigation is necessary to validate the association between sHN and sepsis-associated acute kidney injury among children with septic shock. Furthermore, mechanistic studies that elucidate the role of HN may lead to therapies that promote organ recovery through restoration of mitochondrial homeostasis among those critically ill.

Correlation between angiotensin and acute kidney injury in patients with sepsis.

The aim of the study was to analyze the changes in angiotensin (Ang) levels in patients with sepsis complicated with acute kidney injury (AKI) and evaluate the relationship between Ang and AKI. Prospective research methods were used in this study. A total of 66 sepsis patients admitted to the Intensive care Unit (ICU) of the First Hospital of Hebei Medical University from October 2020 to January 2021 were enrolled. According to the occurrence of AKI, patients were divided into the sepsis-associated AKI (SA-AKI) group and the non-AKI group. The levels of Ang-1 and Ang-2 were compared between the two groups. The relationship between Ang and glomerular filtration rate (GFR) in sepsis patients was studied by correlation analysis. Plasma Ang-1 in the SA-AKI group was significantly higher than that in the non-AKI group (0.39±1.05 ng/ml vs. 0.10±0.24 ng/ml, p=0.039). The Ang-2/Ang-1 in the SA-AKI group was lower than that in the non-AKI group with a significant difference (52.55±191.38 vs. 349.50±327.49, p=0.001). Correlation analysis indicated that Ang-1 was negatively correlated with GFR (r=-0.12, p=0.031), while Ang-2/Ang-1 was positively correlated with GFR (r=0.21, p<0.001). The Ang-2 was positively correlated with GFR (r=0.204, p<0.001) CONCLUSIONS: Plasma Ang-1 and Ang-2 levels are suggestive for assessing the risk of AKI in patients with sepsis.

Plasma oxidative lipidomics reveals signatures for sepsis-associated acute kidney injury

BackgroundOxidized lipids are essential bioactive lipid mediators generated during infection that regulate oxidative stress and the inflammatory response, but their signatures in patients with sepsis-associated acute kidney injury (SA-AKI) are poorly understood. This study analyzed the oxidative lipidomics of plasma from patients with SA-AKI to reveal the underlying biomarkers and pathophysiological mechanisms involved in sepsis. MaterialsA total of 67 patients with SA-AKI and 20 age- and sex-matched healthy controls (HCs) participated in this prospective cohort study. Among the patients with SA-AKI, 14 cases had stage I-II AKI and 53 cases had stage III AKI. Oxidative lipidomic analysis of plasma samples was conducted using ultra performance liquid chromatography coupled with tandem mass spectrometric (UPLC-MS /MS) detection. ResultsAmong 21 kinds of differentially oxidized lipids, 5(S),12(S)-DiHETE, 5-isoPGF2VI, 5,6-DiHETrE, 11,12-EET and 9,10-DiHOME showed the best performance. The prediction model incorporating them has shown highly sensitive and specific in distinguishing different stages of SA-AKI from HCs. The annotation of Kyoto Encyclopedia of Genes and Genomes illustrated that the overall downregulation of vascular smooth muscle contraction was closely related to the pathophysiological mechanism of SA-AKI. ConclusionThis study revealed alterations in the characteristic oxidized lipids in the plasma of SA-AKI patients, and these lipids had high diagnostic efficiency and potential targeted intervention value for SA-AKI.

Inhibition of retinoic acid signaling in proximal tubular epithelial cells protects against acute kidney injury.

Retinoic acid receptor (RAR) signaling is essential for mammalian kidney development but, in the adult kidney, is restricted to occasional collecting duct epithelial cells. We now show that there is widespread reactivation of RAR signaling in proximal tubular epithelial cells (PTECs) in human sepsis-associated acute kidney injury (AKI) and in mouse models of AKI. Genetic inhibition of RAR signaling in PTECs protected against experimental AKI but was unexpectedly associated with increased expression of the PTEC injury marker Kim1. However, the protective effects of inhibiting PTEC RAR signaling were associated with increased Kim1-dependent apoptotic cell clearance, or efferocytosis, and this was associated with dedifferentiation, proliferation, and metabolic reprogramming of PTECs. These data demonstrate the functional role that reactivation of RAR signaling plays in regulating PTEC differentiation and function in human and experimental AKI.

The role of renin-angiotensin system in sepsis-associated acute kidney injury: mechanisms and therapeutic implications.

This review aims to explore the relationship between the renin angiotensin system (RAS) and sepsis-associated acute kidney injury (SA-AKI), a common complication in critically ill patients associated with mortality, morbidity, and long-term cardiovascular complications. Additionally, this review aims to identify potential therapeutic approaches to intervene with the RAS and prevent the development of AKI. Recent studies have provided increasing evidence of RAS alteration during sepsis, with systemic and local RAS disturbance, which can contribute to SA-AKI. Angiotensin II was recently approved for catecholamine resistant vasodilatory shock and has been associated with improved outcomes in selected patients. SA-AKI is a common condition that can involve disturbances in the RAS, particularly the canonical angiotensin-converting enzyme (ACE) angiotensin-II (Ang II)/angiotensin II receptor 1 (AT-1R) axis. Increased renin levels, a key enzyme in the RAS, have been shown to be associated with AKI and may also guide vasopressor therapy in shock. In patients with high renin levels, angiotensin II administration may reduce renin concentration, improve intra-renal hemodynamics, and enhance signaling through the angiotensin II receptor 1. Further studies are needed to explore the role of the RAS in SA-AKI and the potential for targeted therapies.

Development of a nomogram model for the early prediction of sepsis-associated acute kidney injury in critically ill patients

Sepsis-associated acute kidney injury is a common complication of sepsis, but it is difficult to predict sepsis-associated acute kidney injury. In this retrospective observational study, adult septic patients were recruited from the MIMIC-III database as the training cohort (n = 4764) and from Xiangya Hospital (n = 1568) and Zhang’s database as validation cohorts. We identified eleven predictors with seven independent risk predictors of sepsis-associated acute kidney injury [fluid input_day1 ≥ 3390 ml (HR hazard ratio 1.42), fluid input_day2 ≥ 2734 ml (HR 1.64), platelet_min_day5 ≤ 224.2 × 109/l (HR 0.86), length of ICU stay ≥ 2.5 days (HR 1.24), length of hospital stay ≥ 5.8 days (HR 1.18), Bun_max_day1 ≥ 20 mmol/l (HR 1.20), and mechanical ventilation time ≥ 96 h (HR 1.11)] by multivariate Cox regression analysis, and the eleven predictors were entered into the nomogram. The nomogram model showed a discriminative ability for estimating sepsis-associated acute kidney injury. These results indicated that clinical parameters such as excess input fluid on the first and second days after admission and longer mechanical ventilation time could increase the risk of developing sepsis-associated acute kidney injury. With our study, we built a real-time prediction model for potentially forecasting acute kidney injury in septic patients that can help clinicians make decisions as early as possible to avoid sepsis-associated acute kidney injury.

Endothelial Injury in Paediatric Sepsis-associated Acute Kidney Injury

Background: Sepsis-associated acute kidney injury (SA-AKI) is an acute kidney injury in the presence of sepsis without other significant contributing factors explaining acute kidney injury (AKI). Circulating syndecan-1, angiopoietin-2, and urinary neutrophil gelatinase-associated lipocalin levels can potentially cause neglected AKI to become acute kidney disease (AKD) and even chronic kidney disease (CKD). Therefore, studying its levels in the early phase of AKI is important, especially in SAAKI. Objectives: This study aims to analyze the levels of syndecan-1, angiopoietin-2, and urine neutrophil gelatinase-associated lipocalin (uNGAL) as other modalities that might detect AKI earlier in children with SAAKI. Methods: This study enrolled 23 children between one month and 18 years with sepsis. Blood samples were collected from all patients at the baseline, 12, 24, and 48 hours after admission to assess serum creatinine, syndecan-1, angiopoietin-2, and a urine sample was collected to measure uNGAL levels. We used the Wilcoxon signed-rank test to compare each biomarker with the time of measurement and the Mann-Whitney test to compare the levels of biomarkers with the incidence of SA-AKI. Results: The highest median value for uNGAL was 78.30 (3.20 - 24098.40) in the 12th-hour measurement; for syndecan was 2.92 (0.06 - 83.00) in the baseline measurement, slightly decreased and continued to increase up to 48 hours, and for Ang-2 was 4159.60 (17.60 - 226428.00) in the 12th-hour measurement. The incidence of SA-AKI based on the pediatric risk-injury-failure-loss-end stage (pRIFLE) criteria were that five children (21.7%) had AKI in the risk/injury phase at baseline, 24-hour, 48-hour observations, and also six children (26.1%) at 12-hour observation. Conclusion: There was an increase in levels of syndecan-1 and ang-2 in children with severe sepsis, especially in the first 24 hours.

KDM2B regulates inflammation and oxidative stress of sepsis via targeting NF-κB and AP-1 pathways.

The kidney is an easily affected organ with sepsis which is a main underlying cause of acute kidney injury (AKI). Histone-modifying lysine-specific demethylase 2B (KDM2B) is involved in numerous pathological processes, such as cell senescence and tumor development. However, the role of KDM2B in sepsis-induced AKI is unclear. To investigate the role of KDM2B on cell viability, inflammation and oxidative stress of sepsis-associated AKI, and the involved signaling pathways. An AKI model in vitro was established through lipopolysaccharide (LPS)-induction in HK-2 cells. Western blots were performed to evaluate the expression of KDM2B, cyclooxygenase 2 (COX2), inducible nitric oxide synthase (iNOS), p65, c-Jun and c-Fos, as well as p65 phosphorylation. Cell viability was measured using CCK-8 kit. ELISA was performed to analyze the production of layered double hydroxide (LDH), tumor necrosis factor (TNF)-α, interleukin (IL)-1β, IL-18, vascular cell adhesion molecule-1 (VCAM-1), superoxide dismutase (SOD), malondialdehyde (MDA), glutathione (GSH), and H2 O2 . The qPCR was used to evaluate the transcription level of TNF-α, IL-1β, IL-18, and VCAM-1. KDM2B knockdown alleviated LPS-induced cytotoxicity, decreased LDH release, and improved cell viability. KDM2B knockdown reduced concentration of inflammation-related molecules including TNF-α, IL-1β, IL-18, and VCAM-1, and inhibited their transcription. Moreover, KDM2B knockdown promoted the quantity of SOD and GSH, while declined the production of MDA, H2 O2 , COX2, and iNOS. Further, KDM2B played a role in LPS-induced HK-2 cell injury by activating nuclear factor κB (NF-κB) and activator protein 1 (AP-1) pathways. KDM2B knockdown reduced cytotoxicity, inflammation and oxidative stress in LPS-induced AKI via inhibiting NF-κB and AP-1 pathways, indicating KDM2B may be a promising therapeutic target for the treatment of sepsis-associated AKI.

Nlrp3 Deficiency Alleviates Lipopolysaccharide-Induced Acute Kidney Injury via Suppressing Renal Inflammation and Ferroptosis in Mice.

The nucleotide-binding oligomerization domain-like receptor protein 3 (NLRP3) inflammasome is a vital component of many inflammatory responses. Here, we intended to investigate the involvement of NLRP3 in lipopolysaccharide (LPS)-induced sepsis-associated acute kidney injury (S-AKI) and explore its mechanisms. For the first time, we validated elevated NLRP3 expression in the renal tissues of S-AKI patients by immunohistochemistry analysis. Through LPS injection in both wild-type and Nlrp3-/- mice, a S-AKI model was developed. It was found that LPS-induced kidney injury, including an abnormal morphology in a histological examination, abnormal renal function in a laboratory examination, and an increase in the expression of AKI biomarkers, was dramatically reversed in Nlrp3-deficient mice. Nlrp3 deletion alleviated renal inflammation, as evidenced by the suppression of the expression of pro-inflammatory cytokines and chemokines. A combinative analysis of RNA sequencing and the FerrDb V2 database showed that Nlrp3 knockout regulated multiple metabolism pathways and ferroptosis in LPS-induced S-AKI. Further qPCR coupled with Prussian blue staining demonstrated that Nlrp3 knockout inhibited murine renal ferroptosis, indicating a novel mechanism involving S-AKI pathogenesis by NLRP3. Altogether, the aforementioned findings suggest that Nlrp3 deficiency alleviates LPS-induced S-AKI by reducing renal inflammation and ferroptosis. Our data highlight that NLRP3 is a potential therapeutic target for S-AKI.

Polygonum cuspidatum Sieb. et Zucc. Extracts improve sepsis-associated acute kidney injury by inhibiting NF-κB-mediated inflammation and pyroptosis

Ethnopharmacological relevancePolygonum cuspidatum Sieb. et Zucc. (Polygonum cuspidatum) is a herbaceous perennial plant in the Polygonaceae family that produces biofunctional stilbenes and quinones. The dried rhizome and root of P. cuspidatum in traditional oriental medicine have been used for ameliorating inflammatory illnesses, diabetes, gout, cancer, and other ailments. Aim of the studyThis work aimed to investigate the protective effects of P. cuspidatum extracts (PCE) on sepsis-associated acute kidney injury (SA-AKI) and its underlying mechanism. Materials and methodsThe potential mechanisms by which PCE improved SA-AKI were preliminarily predicted by network pharmacology. The dry powders of PCE were obtained using the freeze-drying method. A mouse model of SA-AKI was established by intraperitoneal injection of lipopolysaccharide (LPS). The protective effects of PCE on SA-AKI in vivo were studied using pathological and biochemical methods. LPS-stimulated HK-2 cells were prepared for in vitro evaluation. The qPCR and immunoblotting assays were performed to confirm the mechanism involved. ResultsThe network pharmacology results indicate that emodin (Emo) and polydatin (PD) are potential active components of P. cuspidatum ameliorating SA-AKI. The experimental results showed that PCE improved renal function indices (creatinine, urea nitrogen, and urinary protein) in SA-AKI mice. Mechanistically, PCE mitigated oxidative stress, regulated the expression levels of pyroptosis-related proteins, and repressed the production of inflammatory cytokines by inactivating nuclear factor-kappa B (NF-κB) signaling in vivo. Similar results were observed in LPS-stimulated HK-2 cells in the presence of Emo or PD. ConclusionsOur results demonstrated that PCE and active ingredients (Emo and PD) in PCE ameliorated SA-AKI by suppressing oxidative stress, inflammation, and pyroptosis.

Furosemide Stress Test and Renal Resistive Index for Prediction of Severity of Acute Kidney Injury in Sepsis.

Introduction The furosemide stress test (FST) predicts the severity and the need for renal replacement therapy (RRT) in patients with sepsis-associated acute kidney injury(S-AKI). The renal resistive index (RRI) indicates renal vascular resistance. Objectives The primary objective was to find the correlation between FST and RRI in S-AKI. The secondary objectives were to evaluate the role of FST and RRI on the progression of S-AKI. Methods A total of 154 consenting adult patients with S-AKI were administered FST. Renal echography was performed within the first 12 hours of admission, and RRI was calculated. The patients were grouped either into progressors or non-progressors to AKI-KDIGO stage 3. Results Of the patients who had RRI at Day 1 less than 0.73, 60% recovered, 34.3% needed RRT, and 35.5% died, whereas in those who had RRI at Day 1 greater than 0.73, only 22% recovered, 46.6% required RRT, and 51.6% died. RRI value of 0.73 predicted the need for RRT with a sensitivity of 35.1%, specificity of 80.4% and accuracy of 69.1%. The highest number of patients of KDIGO stage 3 (50%), followed by stage 2 (28.1%) and stage 1 (21.9%), presented technical difficulties in measuring the RRI. Conclusion FST is an economical and easily administered test to assess renal tubular function and can predict the occurrence and progression of S-AKI. RRI is a modest marker for predicting the need for RRT or persistent AKI.

Multidimensional Landscape of SA-AKI Revealed by Integrated Proteomics and Metabolomics Analysis.

Sepsis-associated acute kidney injury (SA-AKI) is a severe and life-threatening condition with high morbidity and mortality among emergency patients, and it poses a significant risk of chronic renal failure. Clinical treatments for SA-AKI remain reactive and non-specific, lacking effective diagnostic biomarkers or treatment targets. In this study, we established an SA-AKI mouse model using lipopolysaccharide (LPS) and performed proteomics and metabolomics analyses. A variety of bioinformatic analyses, including gene set enrichment analysis (GSEA), weighted gene co-expression network analysis (WGCNA), protein and protein interactions (PPI), and MetaboAnalyst analysis, were conducted to investigate the key molecules of SA-AKI. Integrated proteomics and metabolomics analysis revealed that sepsis led to impaired renal mitochondrial function and metabolic disorders. Immune-related pathways were found to be activated in kidneys upon septic infection. The catabolic products of polyamines accumulated in septic kidneys. Overall, our integrated analysis provides a multidimensional understanding of SA-AKI and identifies potential pathways for this condition.

Increased R-spondin 3 contributes to aerobic exercise-induced protection against renal vascular endothelial hyperpermeability and acute kidney injury.

Exercise training exerts protective effects against sepsis-associated multiple organ dysfunction. This study aimed to investigate whether aerobic exercise protected against sepsis-associated acute kidney injury (AKI) via modulating R-spondin 3 (RSPO3) expression. To investigate the effects of aerobic exercise on lipopolysaccharide (LPS)-induced AKI, LPS (20 mg/kg) was intraperitoneally injected after six weeks of treadmill training. To investigate the role of RSPO3 in LPS-induced AKI, wild-type (WT) or inducible endothelial cell-specific RSPO3 knockout (RSPO3EC-/- ) mice were intraperitoneally injected with 12 mg/kg LPS. RSPO3 was intraperitoneally injected 30 min before LPS treatment. Aerobic exercise-trained mice were more resistant to LPS-induced body weight loss and hypothermia and had a significant higher survival rate than sedentary mice exposed to LPS. Exercise training restored the LPS-induced decreases in serum and renal RSPO3 levels. Exercise or RSPO3 attenuated, whereas inducible endothelial cell-specific RSPO3 knockout exacerbated LPS-induced renal glycocalyx loss, endothelial hyperpermeability, inflammation, and AKI. Bioinformatics analysis results revealed significant increases in the expression of matrix metalloproteinases (MMPs) in kidney tissues of mice exposed to sepsis or endotoxaemia, which was validated in renal tissue from LPS-exposed mice and LPS-treated human microvascular endothelial cells (HMVECs). Both RSPO3 and MMPs inhibitor restored LPS-induced downregulation of tight junction protein, adherens junction protein, and glycocalyx components, thus ameliorating LPS-induced endothelial leakage. Exercise or RSPO3 reversed LPS-induced upregulation of MMPs in renal tissues. Increased renal expression of RSPO3 contributes to aerobic exercise-induced protection against LPS-induced renal endothelial hyperpermeability and AKI by suppressing MMPs-mediated disruption of glycocalyx and tight and adherens junctions.

Design, Synthesis, and Biological Evaluation of Novel P2X7 Receptor Antagonists for the Treatment of Septic Acute Kidney Injury.

Sepsis-associated acute kidney injury (AKI) is a serious clinical problem, without effective drugs. Abnormal activation of the purinergic P2X7 receptor (P2X7R) in septic kidneys makes its antagonist a promising therapeutic approach. Herein, a series of novel P2X7R antagonists were designed, synthesized, and structurally optimized. Based on in vitro potency in human/mouse P2X7R using HEK293 cells, hepatic microsomal stability, and pharmacokinetic and preliminary in vivo assessments, compound 14a was identified by respective human and mouse P2X7R IC50 values of 64.7 and 10.1 nM, together with favorable pharmacokinetic properties. Importantly, 14a dose-dependently alleviated kidney dysfunction and pathological injury in both lipopolysaccharide (LPS)- and cecal ligation/perforation (CLP)-induced septic AKI mice with a good safety profile. Mechanistically, 14a could suppress NLRP3 inflammasome activation to inhibit the expression of cleaved caspase-1, gasdermin D, IL-1β, and IL-18 in the injured kidneys of septic mice. Collectively, these results highlighted that P2X7R antagonist 14a exerted a therapeutic potential against septic AKI.

Structure-Activity Relationship Studies of 2,4,5-Trisubstituted Pyrimidine Derivatives Leading to the Identification of a Novel and Potent Sirtuin 5 Inhibitor against Sepsis-Associated Acute Kidney Injury.

Sepsis-associated acute kidney injury (AKI) is a serious clinical problem without effective drugs. Inhibition of sirtuin 5 (SIRT5) has been confirmed to protect against AKI, suggesting that SIRT5 inhibitors might be a promising therapeutic approach for AKI. Herein, structural optimization was performed on our previous compound 1 (IC50 = 3.0 μM), and a series of 2,4,5-trisubstituted pyrimidine derivatives have been synthesized. The structure-activity relationship (SAR) analysis led to the discovery of three nanomolar level SIRT5 inhibitors, of which the most potent compound 58 (IC50 = 310 nM) was demonstrated to be a substrate-competitive and selective inhibitor. Importantly, 58 significantly alleviated kidney dysfunction and pathological injury in both lipopolysaccharide (LPS)- and cecal ligation/perforation (CLP)-induced septic AKI mice. Further studies revealed that 58 regulated protein succinylation and the release of proinflammatory cytokines in the kidneys of septic AKI mice. Collectively, these results highlighted that targeting SIRT5 has a therapeutic potential against septic AKI.

CIRC_0002131 CONTRIBUTES TO LPS-INDUCED APOPTOSIS, INFLAMMATION, AND OXIDATIVE INJURY IN HK-2 CELLS VIA INHIBITING THE BINDING BETWEEN MIR-942-5P AND OXSR1.

Background: Circular RNAs are implicated in the progression of sepsis-associated acute kidney injury (AKI). Circ_0002131 was shown to aggravate cell inflammation and oxidative stress in sepsis-induced AKI. The aim of this study was to investigate the role and underlying mechanism of circ_0002131 in sepsis-induced AKI. Methods: Cell counting Ki-8 assay was used for cell viability detection. Cell apoptosis was measured using flow cytometry. Circ_0002131, microRNA-942-5p (miR-942-5p), and oxidative stress responsive 1 (OXSR1) level analysis was performed through reverse transcription-quantitative polymerase chain reaction assay. The protein levels were examined by western blot. Inflammatory factors were determined using enzyme-linked immunosorbent assay. Oxidative injury was assessed via commercial kits. Target relation was analyzed by dual-luciferase reporter assay and RNA immunoprecipitation assay. Results: HK-2 cell viability was suppressed and apoptosis was enhanced by LPS. Circ_0002131 was highly expressed in LPS-treated HK-2 cells and sepsis-induced AKI patients. LPS-induced apoptosis, inflammation, and oxidative injury of HK-2 cells were attenuated after silence of circ_0002131. Then, miR-942-5p was identified as a target for circ_0002131, and the regulation of circ_0002131 in LPS-induced cell injury was ascribed to reduce miR-942-5p level. In addition, circ_0002131 targeted miR-942-5p to elevate OXSR1 expression. MiR-942-5p prevented LPS-evoked HK-2 cell injury via targeting OXSR1. Conclusion : All results demonstrated that circ_0002131 promoted LPS-mediated HK-2 cell injury via miR-942-5p-mediated upregulation of OXSR1, suggesting that the circ_0002131/miR-942-5p/OXSR1 axis was related to sepsis-induced AKI progression.

Involvement of Innate Immune System in the Pathogenesis of Sepsis-Associated Acute Kidney Injury.

Although experimental models have shown that the innate immune system is a main contributor to acute kidney injury (AKI), its involvement in human sepsis-associated AKI (SA-AKI) remains unclear. We retrospectively evaluated 19 patients with SA-AKI who were treated with continuous renal replacement therapy (CRRT). Serum cytokine, complement components, and the proportion and functions of innate immune cells, such as CD56+ T cells, CD56+ natural killer (NK) cells, and monocytes, were analyzed. There were no differences in the proportions of CD56+ T and NK cells between patients with SA-AKI and healthy controls. In patients with SA-AKI, fas ligand (FasL) expression in CD56+ T cells was significantly upregulated, and the proportion of perforin-positive CD56+ T cells tended to be higher than that in healthy controls. The positive rate of both FasL and perforin of CD56+ T cells was significantly higher than that of CD56- T cells, which include cytotoxic T cells. Antigen-presenting capacity and phagocytic activity of monocytes in patients with SA-AKI were significantly decreased compared to those of healthy controls and did not recover soon after the initiation of CRRT. CD56+ T cells are involved in the disease processes of human SA-AKI through effector molecules such as FasL or perforin.