Global epidemiology and outcomes of acute kidney injury

Discovery, biosynthesis, organic synthesis, and bioactivities of meroterpenoids from Rhododendron species

Meroterpenoids discovered in Rhododendrons species possess unique chemical structures and biological activities and are expected to become new drug targets for Alzheimer's disease, metabolic disorders, and chronic kidney disease, and these compounds have attracted increasing attention in recent years. In this study, Rhododendron meroterpenoids and their structures, classifications, racemate distribution, biosynthetic pathways, chemical synthesis, and bioactivities are reviewed prior to 2023.

The protective mechanism of SIRT3 and potential therapy in acute kidney injury

Acute kidney injury (AKI) is a complex clinical syndrome with a poor short-term prognosis, which increases the risk of the development of chronic kidney diseases and end-stage kidney disease. However, the underlying mechanism of AKI remains to be fully elucidated, and effective prevention and therapeutic strategies are still lacking. Given the enormous energy requirements for filtration and absorption, the kidneys are rich in mitochondria, which are unsurprisingly involved in the onset or progression of AKI. Accumulating evidence has recently documented that Sirtuin 3 (SIRT3), one of the most prominent deacetylases highly expressed in the mitochondria, exerts a protective effect on AKI. SIRT3 protects against AKI by regulating energy metabolism, inhibiting oxidative stress, suppressing inflammation, ameliorating apoptosis, inhibiting early-stage fibrosis and maintaining mitochondrial homeostasis. Besides, a number of SIRT3 activators have exhibited renoprotective properties both in animal models and in vitro experiments, but have not yet been applied to clinical practice, indicating a promising therapeutic approach. In this review, we unravel and summarize the recent advances in SIRT3 research and the potential therapy of SIRT3 activators in AKI.

The Dual-specificity Phosphatase 3 (DUSP3): A Potential Target Against Renal Ischemia/Reperfusion Injury

Renal ischemia/reperfusion (I/R) injury is a common clinical challenge faced by clinicians in kidney transplantation. I/R is the leading cause of acute kidney injury, and it occurs when blood flow to the kidney is interrupted and subsequently restored. I/R impairs renal function in both short and long terms. Renal ischemic preconditioning refers to all maneuvers intended to prevent or attenuate ischemic damage. In this context, the present review focuses on the dual-specificity phosphatase 3 (DUSP3), also known as vaccinia H1-related phosphatase, an uncommon regulator of mitogen-activated protein kinase (MAPK) phosphorylation. DUSP3 has different biological functions: (1) it acts as a tumor modulator and (2) it is involved in the regulation of immune response, thrombosis, hemostasis, angiogenesis, and genomic stability. These functions occur either through MAPK-dependent or MAPK-independent mechanisms. DUSP3 genetic deletion dampens kidney damage and inflammation caused by I/R in mice, suggesting DUSP3 as a potential target for preventing renal I/R injury. Here, we discuss the putative role of DUSP3 in ischemic preconditioning and the potential mechanisms of such an attenuated inflammatory response via improved kidney perfusion and adequate innate immune response.

Characteristics, Risk Factors, and Outcomes in Acute Kidney Injury Patients: A Retrospective Cross-Sectional Study, Palestine

Background

Acute kidney injury (AKI) is a major medical problem affecting patients' quality of life and healthcare costs.

Objectives

This study evaluated the severity, risk factors, and outcomes of patients diagnosed with acute kidney injury (AKI), including community-acquired AKI (CA-AKI) and hospital-acquired AKI (HA-AKI), who were admitted to tertiary institutions in Palestine.

Methods

This retrospective cross-sectional study was conducted at multiple tertiary care hospitals in Palestine by reviewing patient charts from January 2020 to March 2023. The study included all patients aged ≥18 years who were admitted to the hospital and diagnosed with AKI at admission (CA-AKI) or who developed AKI 48 hours after admission (HA-AKI). Patients with incomplete medical records and those with no reported creatinine levels during their stay, pregnant women, kidney transplant patients, and end-stage renal disease patients were excluded. Data were analyzed using SPSS v22.0. The incidence of AKI in each group was compared using the chi-squared test.

Results

This study included 259 participants. HA-AKI was present in 27.3% of the patients, while CA-AKI was 72.7%. The most common stage among patients was stage 3 (55.7%, HA-AKI) (42.9%, CA-AKI), and the most common comorbidity contributing to AKI was CKD. NSAIDs, ACE-I/ARBs, and DIURETICs were the most nephrotoxic drugs contributing to AKI. Patients with hyperphosphatemia, hyperkalemia, severe metabolic acidosis, or stage 3 AKI require renal replacement therapy. In addition, our findings revealed a significant association among AKI mortality, age, and heart disease.

Conclusion

CA-AKI was more prevalent than HA-AKI in Palestinian patients admitted for AKI. Risk factors for AKI included diabetes, CKD, and medications (antibiotics, NSAID, diuretics, and ACE-I/ARB). Preventive measures, medication management, and disease state management are necessary to minimize AKI during hospital admission or in the community.

From Rare Disorders of Kidney Tubules to Acute Renal Injury: Progress and Prospective

Background

Acute kidney injury (AKI) is a severe condition marked by rapid renal function deterioration and elevated mortality, with traditional biomarkers lacking sensitivity and specificity. Rare tubulointerstitial diseases encompass a spectrum of disorders, primarily including monogenic diseases, immune-related conditions, and drug-induced tubulointerstitial diseases. The clinical manifestations vary from electrolyte and acid-base imbalances to kidney function insufficiency, which is associated with AKI in up to 20% of cases. Evidence indicated that rare tubulointerstitial diseases might provide new conceptual insights and perspectives for novel biomarkers and potential therapeutic strategies for AKI.

Summary

Autosomal dominant tubulointerstitial kidney disease (ADTKD) and Fanconi syndrome (FS) are rare tubulointerstitial diseases. In ADTKD, UMOD and REN are closely related to AKI by affecting oxidative stress and tubuloglomerular feedback, which provide potential new biomarkers for AKI. Both rare tubulointerstitial diseases and AKI share etiologies and treatment responses. From the mechanism standpoint, rare tubulointerstitial diseases and AKI involve tubular transporter injury, initially manifesting as tubular dysfunction in tubulointerstitial disorder and progressing to AKI because of the programmed cell death with apoptosis, pyroptosis, or necroptosis of proximal tubule cells. Additionally, mitochondrial dysfunction has been identified as a common mechanism in both tubulointerstitial diseases and AKI induced by drugs, pSS, or monoclonal diseases. In the end, both AKI and FS patients and animal models responded well to the therapy of the primary diseases.

Key Messages

In this review, we describe an overview of ADTKD and FS to identify their associations with AKI. Mitochondrial dysfunction contributes to rare tubulointerstitial diseases and AKI, which might provide a potential therapeutic target.

LXA4 protected mice from renal ischemia/reperfusion injury by promoting IRG1/Nrf2 and IRAK-M-TRAF6 signal pathways

Excessive inflammatory response and increased oxidative stress play an essential role in the pathophysiology of ischemia/reperfusion (I/R)-induced acute kidney injury (IRI-AKI). Emerging evidence suggests that lipoxin A4 (LXA4), as an endogenous negative regulator in inflammation, can ameliorate several I/R injuries. However, the mechanisms and effects of LXA4 on IRI-AKI remain unknown. In this study, A bilateral renal I/R mouse model was used to evaluate the role of LXA4 in wild-type, IRG1 knockout, and IRAK-M knockout mice. Our results showed that LXA4, as well as 5-LOX and ALXR, were quickly induced, and subsequently decreased by renal I/R. LXA4 pretreatment improved renal I/R-induced renal function impairment and renal damage and inhibited inflammatory responses and oxidative stresses in mice kidneys. Notably, LXA4 inhibited I/R-induced the activation of TLR4 signal pathway including decreased phosphorylation of TAK1, p36, and p65, but did not affect TLR4 and p-IRAK-1. The analysis of transcriptomic sequencing data and immunoblotting suggested that innate immune signal molecules interleukin-1 receptor-associated kinase-M (IRAK-M) and immunoresponsive gene 1 (IRG1) might be the key targets of LXA4. Further, the knockout of IRG1 or IRAK-M abolished the beneficial effects of LXA4 on IRI-AKI. In addition, IRG1 deficiency reversed the up-regulation of IRAK-M by LXA4, while IRAK-M knockout had no impact on the IRG1 expression, indicating that IRAK-M is a downstream molecule of IRG1. Mechanistically, we found that LXA4-promoted IRG1-itaconate not only enhanced Nrf2 activation and increased HO-1 and NQO1, but also upregulated IRAK-M, which interacted with TRAF6 by competing with IRAK-1, resulting in deactivation of TLR4 downstream signal in IRI-AKI. These data suggested that LXA4 protected against IRI-AKI via promoting IRG1/Itaconate-Nrf2 and IRAK-M-TRAF6 signaling pathways, providing the rationale for a novel strategy for preventing and treating IRI-AKI.

Apoptosis-related prognostic biomarkers and potential targets for acute kidney injury based on machine learning algorithm and in vivo experiments

Acute kidney injury (AKI) is a common critical illness in hospitalized patients, characterized by a rapid decline in kidney function over a short period, which can seriously endanger the patient's life. Currently, there is a lack of precise and universal AKI diagnostic biomarkers in clinical practice. In this study, weighted gene coexpression network analysis (WGCNA), differential expression analysis, univariate and multivariate logistic regression analyses, receiver operating characteristic (ROC) curves, and immune cell infiltration were performed to identify apoptosis-related biomarkers that can be used for AKI diagnosis. Three core apoptosis-related genes (ARGs), CBFB, EGF and COL1A1, were identified as AKI biomarkers. More importantly, an apoptosis-related signature containing three hub ARGs was validated as a diagnostic model. The hub genes exhibited good correlations with glomerular filtration rate (GFR) and serum creatinine (SCr) in the Nephroseq kidney disease database. Additionally, CIBERSORT immune infiltration analysis indicated that these core ARGs may affect immune cell recruitment and infiltration in AKI patients. Subsequently, we investigated the alteration of the expression levels of three core ARGs in AKI samples using single-cell RNA sequencing analysis and analyzed the cell types that mainly expressed these ARGs. More importantly, the expression of core ARGs was validated in folic acid- and cisplatin-induced AKI mouse models. In summary, our study identified three diagnostic biomarkers for AKI, explored the roles of ARGs in AKI progression and provided new ideas for the clinical diagnosis and treatment of AKI.

Site 1 protease aggravates acute kidney injury by promoting tubular epithelial cell ferroptosis through SIRT3-SOD2-mtROS signaling

Ischemia/reperfusion (I/R)-induced acute kidney injury (AKI) is a common clinical syndrome with high morbidity and mortality. Ferroptosis, a newly discovered form of oxidative cell death, is involved in the pathogenesis of renal I/R injury; however, the underlying mechanism remains to be explored. Here, we reported that site 1 protease (S1P) promotes ischemic kidney injury by regulating ferroptotic cell death of tubular epithelial cells. S1P abundance was measured in hypoxia/reoxygenation (H/R)-treated Boston University mouse proximal tubular (BUMPT) cells and I/R-induced murine kidney tissue. S1P expression in BUMPT cells and kidneys was initially activated by hypoxic stimulation, accompanied by the ferroptotic response. Blocking S1P blunted H/R-induced ferroptotic cell death, which also restored sirtuin 3 (SIRT3) expression and superoxide dismutase 2 (SOD2) activity in BUMPT cells. Next, inhibition of S1P expression restored I/R-suppressed SIRT3 abundance, SOD2 activity and reduced the elevated level of mitochondria reactive oxygen species (mtROS), which attenuated tubular cell ferroptosis and renal I/R injury. In conclusion, S1P promoted renal tubular epithelial cell ferroptosis under I/R status by activating SIRT3-SOD2-mtROS signaling, thereby accelerating kidney injury. Thus, targeting S1P signaling may serve as a promising strategy for I/R kidney injury.

Pyroptosis: The Determinator of Cell Death and Fate in Acute Kidney Injury

Background

Acute kidney injury (AKI) is kidney damage that leads to a rapid decline in function. AKI primarily occurs when the tubular epithelium is damaged, causing swelling, loss of brush margin, and eventual apoptosis. Research has shown that tubular epithelial cell damage in AKI is linked to cell cycle arrest, autophagy, and regulation of cell death.

Summary

Pyroptosis, a type of programmed cell death triggered by inflammation, is believed to play a role in the pathophysiology of AKI. Cumulative evidence has shown that pyroptosis is the main cause of tubular cell death in AKI. Thus, targeted intervention of pyroptosis may be a promising therapeutic approach for AKI. This review delves deep into the cutting-edge research surrounding pyroptosis in the context of AKI, shedding light on its intricate mechanisms and potential implications for clinical practice. Additionally, we explore the exciting realm of potential preclinical treatment options for AKI, aiming to pave the way for future therapeutic advancements.

Key Messages

Pyroptosis, a highly regulated form of cell death, plays a crucial role in determining the fate of cells during the development of AKI. This intricate process involves the activation of inflammasomes, which are multi-protein complexes that initiate pyroptotic cell death. By understanding the mechanisms underlying pyroptosis, researchers aim to gain insights into the pathogenesis of AKI and potentially identify new therapeutic targets for this condition.

Rodent models of AKI and AKI-CKD transition: an update in 2024

Despite known drawbacks, rodent models are essential tools in the research of renal development, physiology, and pathogenesis. In the past decade, rodent models have been developed and used to mimic different etiologies of acute kidney injury (AKI), AKI to chronic kidney disease (CKD) transition or progression, and AKI with comorbidities. These models have been applied for both mechanistic research and preclinical drug development. However, current rodent models have their limitations, especially since they often do not fully recapitulate the pathophysiology of AKI in human patients, and thus need further refinement. Here, we discuss the present status of these rodent models, including the pathophysiologic compatibility, clinical translational significance, key factors affecting model consistency, and their main limitations. Future efforts should focus on establishing robust models that simulate the major clinical and molecular phenotypes of human AKI and its progression.

Tolerogenic CD11c+dendritic cells regulate CD4+Tregs in replacing delayed ischemic preconditioning to alleviate ischemia-reperfusion acute kidney injury

Ischemia-reperfusion injury (IRI) is one of the primary clinical causes of acute kidney injury (AKI). The key to IRI lies in immune-inflammatory damage, where dendritic cells (DCs) play a central role in eliciting immune responses within the context of inflammation induced by ischemia-reperfusion. Our previous study has confirmed that delayed ischemic preconditioning (DIPC) can reduce the kidney injury by mediating DCs to regulate T-cells. However, the clinical feasibility of DIPC is limited, as pre-clamping of the renal artery is not applicable for the prevention and treatment of ischemia-reperfusion acute kidney injury (I/R-AKI) in clinical patients. Therefore, the infusion of DCs as a substitute for DIPC presents a more viable strategy for preventing renal IRI. In this study, we further evaluated the impact and mechanism of infused tolerogenic CD11c+DCs on the kidneys following IRI by isolating bone marrow-derived dendritic cells and establishing an I/R-AKI model after pre-infusion of DCs. Renal function was significantly improved in the I/R-AKI mouse model after pre-infused with CD11c+DCs. The pro-inflammatory response and oxidative damage were reduced, and the levels of T helper 2 (Th2) cells and related anti-inflammatory cytokines were increased, which was associated with the reduction of autologous DCs maturation mediated by CD11c+DCs and the increase of regulatory T-cells (Tregs). Next, knocking out CD11c+DCs, we found that the reduced immune protection of tolerogenic CD11c+DCs reinfusion was related to the absence of own DCs. Together, pre-infusion of tolerogenic CD11c+DCs can replace the regulatory of DIPC on DCs and T-cells to alleviate I/R-AKI. DC vaccine is expected to be a novel avenue to prevent and treat I/R-AKI.

Neutrophil Percentage as a Potential Biomarker of Acute Kidney Injury Risk and Short-Term Prognosis in Patients with Acute Myocardial Infarction in the Elderly

Objective

This study aimed to explore the association of preoperative neutrophil percentage (NEUT%) with the risk of acute kidney injury (AKI) in patients with acute myocardial infarction (AMI) having undergone coronary interventional therapy.

Methods

A single-center, retrospective and observational study was conducted. From December 2012 to June 2021, patients with AMI were enrolled and divided into AKI group and non-AKI group. The NEUT% in the two groups was compared. The association between NEUT% with the risk of post-AMI AKI was analyzed by univariate and multivariable logistic regression. Kaplan-Meier survival curve was drawn to evaluate the prognostic ability of NEUT% for short-term all-cause death following AMI.

Results

A total of 3001 consecutive patients were enrolled with an average age of 64.38 years. AKI occurred in 327 (10.9%) patients. The NEUT% was higher in the AKI group than in the non-AKI group ([76.65±11.43]% versus [73.22±11.83]%, P<0.001). NEUT% was also identified as an independent risk factor for AKI in AMI patients after adjustment (OR=1.021, 95% CI: 1.010-1.033, P < 0.001). Compared with those at the lowest quartile of NEUT%, the patients at quartiles 2-4 had a higher risk of AKI (P for trend = 0.003). The odds of AKI increased by 29.0% as NEUT% increased by 1 standard deviation (OR=1.290, 95% CI: 1.087-1.531, P = 0.004). After a median of 35 days follow-up, 93 patients died. Patients with a higher NEUT% presented a higher risk of all-cause death after AMI (Log rank: χ2 =24.753, P<0.001).

Conclusion

In AMI patients, the peripheral blood NEUT% was positively associated with the odds of AKI and short-term all-cause mortality. NEUT% may provide physicians with more information about disease development and prognosis.

Combined Plasma Olink Proteomics and Transcriptomics Identifies CXCL1 and TNFRSF12A as Potential Predictive and Diagnostic Inflammatory Markers for Acute Kidney Injury

Acute kidney injury (AKI) poses a significant global public health challenge. Current methods for detecting AKI rely on monitoring changes in serum creatinine (Scr), blood urea nitrogen (BUN), urinary output and some commonly employed biomarkers. However, these indicators are usually neither specific nor sensitive to AKI, especially in cases of mild kidney injury. AKI is accompanied by severe inflammatory reactions, resulting in the upregulation of numerous inflammation-associated proteins in the plasma. Plasma biomarkers are a noninvasive method for detecting kidney injury, and to date, plasma inflammation-associated cytokines have not been adequately studied in AKI patients. The objective of our research was to identify novel inflammatory biomarkers for AKI. We utilized Olink proteomics to analyze the alterations in plasma inflammation-related proteins in the serum of healthy mice (n = 2) or mice treated with cisplatin (n = 6). Additionally, transcriptome datasets for the lipopolysaccharide (LPS), cisplatin, and ischemia‒reperfusion injury (IRI) groups were obtained from the National Center of Biotechnology Information (NCBI) Gene Expression Omnibus (GEO) database. We calculated the intersection of differentially expressed proteins (DEPs) and genes (DEGs) from both datasets. In the Olink proteomics analysis, the AKI group had significantly greater levels of 11 DEPs than did the control group. In addition, 56 common upregulated DEGs were obtained from the transcriptome dataset. The expression of CXCL1 and TNFRSF12A overlapped across all the datasets. The transcription and protein expression levels of CXCL1 and TNFRSF12A were detected in vivo. The gene and protein levels of CXCL1 and TNFRSF12A were significantly increased in different AKI mouse models and clinical patients, suggesting that these genes and proteins could be potential specific biomarkers for the identification of AKI.

Prognostic Value of Leukocyte-Based Risk Model for Acute Kidney Injury Prediction in Critically Ill Acute Exacerbation of Chronic Obstructive Pulmonary Disease Patients

Purpose

Acute kidney injury (AKI) is a common complication of acute exacerbation of chronic obstructive pulmonary disease (AECOPD), and inflammation is the potential link between AKI and AECOPD. However, little is known about the incidence and risk stratification of AKI in critically ill AECOPD patients. In this study, we aimed to establish risk model based on white blood cell (WBC)-related indicators to predict AKI in critically ill AECOPD patients.

Material and Methods

For the training cohort, data were taken from the Medical Information Mart for eICU Collaborative Research Database (eICU-CRD) database, and for the validation cohort, data were taken from the Medical Information Mart for Intensive Care-IV (MIMIC-IV) database. The study employed logistic regression analysis to identify the major predictors of WBC-related biomarkers on AKI prediction. Subsequently, a risk model was developed by multivariate logistic regression, utilizing the identified significant indicators.

Results

Finally, 3551 patients were enrolled in training cohort, 926 patients were enrolled in validation cohort. AKI occurred in 1206 (33.4%) patients in training cohort and 521 (56.3%) patients in validation cohort. According to the multivariate logistic regression analysis, four WBC-related indicators were finally included in the novel risk model, and the risk model had a relatively good accuracy for AKI in the training set (C-index, 0.764, 95% CI 0.749-0.780) as well as in the validation set (C-index, 0.738, 95% CI: 0.706-0.770). Even after accounting for other models, the critically ill AECOPD patients in the high-risk group (risk score > 3.44) still showed an increased risk of AKI (odds ratio: 4.74, 95% CI: 4.07-5.54) compared to those in low-risk group (risk score ≤ 3.44). Moreover, the risk model showed outstanding calibration capability as well as therapeutic usefulness in both groups for AKI and ICU mortality and in-hospital mortality of critical ill AECOPD patients.

Conclusion

The novel risk model showed good AKI prediction performance. This risk model has certain reference value for the risk stratification of AECOPD complicated with AKI in clinically.

Neutrophils and NADPH Oxidases Are Major Contributors to Mild but Not Severe Ischemic Acute Kidney Injury in Mice

Upregulation of free radical-generating NADPH oxidases (NOX), xanthine oxidoreductase (XOR), and neutrophil infiltration-induced, NOX2-mediated respiratory burst contribute to renal ischemia-reperfusion injury (IRI), but their roles may depend on the severity of IRI. We investigated the role of NOX, XOR, and neutrophils in developing IRI of various severities. C57BL/6 and Mcl-1ΔMyelo neutrophil-deficient mice were used. Oxidases were silenced by RNA interference (RNAi) or pharmacologically inhibited. Kidney function, morphology, immunohistochemistry and mRNA expression were assessed. After reperfusion, the expression of NOX enzymes and XOR increased until 6 h and from 15 h, respectively, while neutrophil infiltration was prominent from 3 h. NOX4 and XOR silencing or pharmacological XOR inhibition did not protect the kidney from IRI. Attenuation of NOX enzyme-induced oxidative stress by apocynin and neutrophil deficiency improved kidney function and ameliorated morphological damage after mild but not moderate/severe IRI. The IR-induced postischemic renal functional impairment (BUN, Lcn-2), tubular necrosis score, inflammation (TNF-α, F4/80), and decreases in the antioxidant enzyme (GPx3) mRNA expression were attenuated by both apocynin and neutrophil deficiency. Inhibition of NOX enzyme-induced oxidative stress or the lack of infiltration by NOX2-expressing neutrophils can attenuate reperfusion injury after mild but not moderate/severe renal IR.

Cisplatin induces acute kidney injury by downregulating miR-30e-5p that targets Galnt3 to activate the AMPK signaling pathway

Cisplatin nephrotoxicity is an etiological factor for acute kidney injury (AKI). MicroRNA (miRNA) expression is dysregulated in cisplatin-induced AKI (cAKI) although the underlying mechanisms are unclear. A cAKI model was established by intraperitoneally injecting cisplatin, and key miRNAs were screened using high-throughput miRNA sequencing. The functions of key miRNAs were determined using the cell viability, live/dead, reactive oxygen species (ROS), and 5-ethynyl-2'-deoxyuridine (EdU) proliferation assays. Additionally, the macrophage membrane was wrapped around a metal-organic framework (MOF) loaded with miRNA agomir to develop a novel composite material, macrophage/MOF/miRNA agomir nanoparticles (MMA NPs). High-throughput miRNA sequencing revealed that miR-30e-5p is a key miRNA that is downregulated in cAKI. The results of in vitro experiments demonstrated that miR-30e-5p overexpression partially suppressed the cisplatin-induced or lipopolysaccharide (LPS)-induced downregulation of cell viability, proliferation, upregulation of ROS production, and cell death. Meanwhile, the results of in vivo and in vitro experiments demonstrated that MMA NPs alleviated cAKI by exerting anti-inflammatory effects. Mechanistically, cisplatin downregulates the expression of miR-30e-5p, and the downregulated miR-30e-5p can target Galnt3 to activate the adenosine 5'-monophosphate activated protein kinase (AMPK) signaling pathway, which promotes the progression of AKI. Our study found that miR-30e-5p is a key downregulated miRNA in cAKI. The downregulated miR-30e-5p promotes AKI progression by targeting Galnt3 to activate the AMPK signaling pathway. The newly developed MMA NPs were found to have protective effects on cAKI, suggesting a potential novel strategy for preventing cAKI.

Development and validation of a deep interpretable network for continuous acute kidney injury prediction in critically ill patients

Early detection of acute kidney injury (AKI) may provide a crucial window of opportunity to prevent further injury, which helps improve clinical outcomes. This study aimed to develop a deep interpretable network for continuously predicting the 24-hour AKI risk in real-time and evaluate its performance internally and externally in critically ill patients. A total of 21,163 patients' electronic health records sourced from Beth Israel Deaconess Medical Center (BIDMC) were first included in building the model. Two external validation populations included 3025 patients from the Philips eICU Research Institute and 2625 patients from Zhongda Hospital Southeast University. A total of 152 intelligently engineered predictors were extracted on an hourly basis. The prediction model referred to as DeepAKI was designed with the basic framework of squeeze-and-excitation networks with dilated causal convolution embedded. The integrated gradients method was utilized to explain the prediction model. When performed on the internal validation set (3175 [15 %] patients from BIDMC) and the two external validation sets, DeepAKI obtained the area under the curve of 0.799 (95 % CI 0.791-0.806), 0.763 (95 % CI 0.755-0.771) and 0.676 (95 % CI 0.668-0.684) for continuousAKI prediction, respectively. For model interpretability, clinically relevant important variables contributing to the model prediction were informed, and individual explanations along the timeline were explored to show how AKI risk arose. The potential threats to generalisability in deep learning-based models when deployed across health systems in real-world settings were analyzed.

Fibroblastic reticular cell-derived exosomes are a promising therapeutic approach for septic acute kidney injury

Sepsis-induced acute kidney injury (S-AKI) is highly lethal, and effective drugs for treatment are scarce. Previously, we reported the robust therapeutic efficacy of fibroblastic reticular cells (FRCs) in sepsis. Here, we demonstrate the ability of FRC-derived exosomes (FRC-Exos) to improve C57BL/6 mouse kidney function following cecal ligation and puncture-induced sepsis. In vivo imaging confirmed that FRC-Exos homed to injured kidneys. RNA-Seq analysis of FRC-Exo-treated primary kidney tubular cells (PKTCs) revealed that FRC-Exos influenced PKTC fate in the presence of lipopolysaccharide (LPS). FRC-Exos promoted kinase PINK1-dependent mitophagy and inhibited NLRP3 inflammasome activation in LPS-stimulated PKTCs. To dissect the mechanism underlying the protective role of Exos in S-AKI, we examined the proteins within Exos by mass spectrometry and found that CD5L was the most upregulated protein in FRC-Exos compared to macrophage-derived Exos. Recombinant CD5L treatment in vitro attenuated kidney cell swelling and surface bubble formation after LPS stimulation. FRCs were infected with a CD5L lentivirus to increase CD5L levels in FRC-Exos, which were then modified in vitro with the kidney tubular cell targeting peptide LTH, a peptide that binds to the biomarker protein kidney injury molecule-1 expressed on injured tubule cells, to enhance binding specificity. Compared with an equivalent dose of recombinant CD5L, the modified CD5L-enriched FRC-Exos selectively bound PKTCs, promoted kinase PINK-ubiquitin ligase Parkin-mediated mitophagy, inhibiting pyroptosis and improved kidney function by hindering NLRP3 inflammasome activation, thereby improving the sepsis survival rate. Thus, strategies to modify FRC-Exos could be a new avenue in developing therapeutics against kidney injury.

DIA proteomics analysis reveals the mechanism of folic acid-induced acute kidney injury and the effects of icariin

The complexities of acute kidney injury (AKI), a multifaceted pathological occurrence, are not fully understood. At present, there is a lack of effective pharmaceutical treatments in clinical practice. Studies have shown that icariin has beneficial effects in models of acute kidney injury (AKI) caused by cisplatin and lipopolysaccharide (LPS). The aim is to explore the mechanisms that cause folic acid (FA)-induced AKI and examine the protective effects of icariin against this condition. To establish a mouse model of AKI, FA was administered via intraperitoneal injection. Icariin was used as the drug intervention. The model and the impact of drug intervention were assessed using measurements of renal function parameters, staining with hematoxylin and eosin, and Q-PCR. The analysis of protein expression changes in the control, model, and icariin treatment groups was conducted using proteomics. KEGG signaling pathway analysis indicates that differential expressed proteins are enriched in the component and coagulation cascades signaling pathway. Through protein-protein interaction network analysis, it was found that compared to the normal group, the expression of Fibrinogen and other proteins was significantly upregulated at the center of the protein interaction network in the model group. After drug treatment, the expression of these proteins was significantly downregulated. The validation experiment supports the above results. In conclusion, this study clarified the molecular mechanism of FA induced acute renal injury from the proteomics level, and provided target selection for AKI; At the same time, the mechanism of icariin in the treatment of AKI was analyzed from the proteomics level.

Acute kidney injury: exploring endoplasmic reticulum stress-mediated cell death

Acute kidney injury (AKI) is a global health problem, given its substantial morbidity and mortality rates. A better understanding of the mechanisms and factors contributing to AKI has the potential to guide interventions aimed at mitigating the risk of AKI and its subsequent unfavorable outcomes. Endoplasmic reticulum stress (ERS) is an intrinsic protective mechanism against external stressors. ERS occurs when the endoplasmic reticulum (ER) cannot deal with accumulated misfolded proteins completely. Excess ERS can eventually cause pathological reactions, triggering various programmed cell death (autophagy, ferroptosis, apoptosis, pyroptosis). This article provides an overview of the latest research progress in deciphering the interaction between ERS and different programmed cell death. Additionally, the report consolidates insights into the roles of ERS in AKI and highlights the potential avenues for targeting ERS as a treatment direction toward for AKI.

Mitochondrial metabolism and targeted treatment strategies in ischemic-induced acute kidney injury

Ischemia-reperfusion injury (IRI) is a common cause of acute kidney injury (AKI). The kidney is susceptible to IRI under several clinical conditions, including hypotension, sepsis, and surgical procedures, such as partial nephrectomy and kidney transplantation. Extensive research has been conducted on the mechanism and intervention strategies of renal IRI in past decades; however, the complex pathophysiology of IRI-induced AKI (IRI-AKI) is not fully understood, and there remains a lack of effective treatments for AKI. Renal IRI involves several processes, including reactive oxygen species (ROS) production, inflammation, and apoptosis. Mitochondria, the centers of energy metabolism, are increasingly recognized as substantial contributors to the early phases of IRI. Multiple mitochondrial lesions have been observed in the renal tubular epithelial cells (TECs) of IRI-AKI mice, and damaged or dysfunctional mitochondria are toxic to the cells because they produce ROS and release cell death factors, resulting in TEC apoptosis. In this review, we summarize the recent advances in the mitochondrial pathology in ischemic AKI and highlight promising therapeutic approaches targeting mitochondrial dysfunction to prevent or treat human ischemic AKI.

Assessment of Acute Kidney Injury using MRI

There has been growing interest in using quantitative magnetic resonance imaging (MRI) to describe and understand the pathophysiology of acute kidney injury (AKI). The ability to assess kidney blood flow, perfusion, oxygenation, and changes in tissue microstructure at repeated timepoints is hugely appealing, as this offers new possibilities to describe nature and severity of AKI, track the time-course to recovery or progression to chronic kidney disease (CKD), and may ultimately provide a method to noninvasively assess response to new therapies. This could have significant clinical implications considering that AKI is common (affecting more than 13 million people globally every year), harmful (associated with short and long-term morbidity and mortality), and currently lacks specific treatments. However, this is also a challenging area to study. After the kidney has been affected by an initial insult that leads to AKI, complex coexisting processes ensue, which may recover or can progress to CKD. There are various preclinical models of AKI (from which most of our current understanding derives), and these differ from each other but more importantly from clinical AKI. These aspects are fundamental to interpreting the results of the different AKI studies in which renal MRI has been used, which encompass different settings of AKI and a variety of MRI measures acquired at different timepoints. This review aims to provide a comprehensive description and interpretation of current studies (both preclinical and clinical) in which MRI has been used to assess AKI, and discuss future directions in the field. LEVEL OF EVIDENCE: 1 TECHNICAL EFFICACY: Stage 3.

Practical Lessons on Antimicrobial Therapy for Critically Ill Patients

Sepsis stands as a formidable global health challenge, with persistently elevated mortality rates in recent decades. Each year, sepsis not only contributes to heightened morbidity but also imposes substantial healthcare costs on survivors. This narrative review aims to highlight the targeted measures that can be instituted to alleviate the incidence and impact of sepsis in intensive care. Here we discuss measures to reduce nosocomial infections and the prevention of equipment and patient colonisation by resilient pathogens. The overarching global crisis of bacterial resistance to newly developed antimicrobial agents intensifies the imperative for antimicrobial stewardship and de-escalation. This urgency has been accentuated in recent years, notably during the COVID-19 pandemic, as high-dose steroids and opportunistic infections presented escalating challenges. Ongoing research into airway colonisation's role in influencing disease outcomes among critically ill patients underscores the importance of tailoring treatments to disease endotypes within heterogeneous populations, which are important lessons for intensivists in training. Looking ahead, the significance of novel antimicrobial delivery systems and drug monitoring is poised to increase. This narrative review delves into the multifaceted barriers and facilitators inherent in effectively treating critically ill patients vulnerable to nosocomial infections. The future trajectory of intensive care medicine hinges on the meticulous implementation of vigilant stewardship programs, robust infection control measures, and the continued exploration of innovative and efficient technological solutions within this demanding healthcare landscape.

Regional Practice Variation and Outcomes in the Standard Versus Accelerated Initiation of Renal Replacement Therapy in Acute Kidney Injury (STARRT-AKI) Trial: A Post Hoc Secondary Analysis

OBJECTIVES

Among patients with severe acute kidney injury (AKI) admitted to the ICU in high-income countries, regional practice variations for fluid balance (FB) management, timing, and choice of renal replacement therapy (RRT) modality may be significant.

DESIGN

Secondary post hoc analysis of the STandard vs. Accelerated initiation of Renal Replacement Therapy in Acute Kidney Injury (STARRT-AKI) trial (ClinicalTrials.gov number NCT02568722).

SETTING

One hundred-fifty-three ICUs in 13 countries.

PATIENTS

Altogether 2693 critically ill patients with AKI, of whom 994 were North American, 1143 European, and 556 from Australia and New Zealand (ANZ).

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Total mean FB to a maximum of 14 days was +7199 mL in North America, +5641 mL in Europe, and +2211 mL in ANZ (p < 0.001). The median time to RRT initiation among patients allocated to the standard strategy was longest in Europe compared with North America and ANZ (p < 0.001; p < 0.001). Continuous RRT was the initial RRT modality in 60.8% of patients in North America and 56.8% of patients in Europe, compared with 96.4% of patients in ANZ (p < 0.001). After adjustment for predefined baseline characteristics, compared with North American and European patients, those in ANZ were more likely to survive to ICU (p < 0.001) and hospital discharge (p < 0.001) and to 90 days (for ANZ vs. Europe: risk difference [RD], -11.3%; 95% CI, -17.7% to -4.8%; p < 0.001 and for ANZ vs. North America: RD, -10.3%; 95% CI, -17.5% to -3.1%; p = 0.007).

CONCLUSIONS

Among STARRT-AKI trial centers, significant regional practice variation exists regarding FB, timing of initiation of RRT, and initial use of continuous RRT. After adjustment, such practice variation was associated with lower ICU and hospital stay and 90-day mortality among ANZ patients compared with other regions.

Designing acute kidney injury clinical trials

Acute kidney injury (AKI) is a common clinical condition with various causes and is associated with increased mortality. Despite advances in supportive care, AKI increases not only the risk of premature death compared with the general population but also the risk of developing chronic kidney disease and progressing towards kidney failure. Currently, no specific therapy exists for preventing or treating AKI other than mitigating further injury and supportive care. To address this unmet need, novel therapeutic interventions targeting the underlying pathophysiology must be developed. New and well-designed clinical trials with appropriate end points must be subsequently designed and implemented to test the efficacy of such new interventions. Herein, we discuss predictive and prognostic enrichment strategies for patient selection, as well as primary and secondary end points that can be used in different clinical trial designs (specifically, prevention and treatment trials) to evaluate novel interventions and improve the outcomes of patients at a high risk of AKI or with established AKI.

Challenges in the Care of Patients with AKI Receiving Outpatient Dialysis: AKINow Recovery Workgroup Report

BACKGROUND

Up to one third of survivors of AKI that required dialysis (AKI-D) during hospitalization remain dialysis dependent at hospital discharge. Of these, 20%-60%, depending on the clinical setting, eventually recover enough kidney function to stop dialysis, and the remainder progress to ESKD.

METHODS

To describe the challenges facing those still receiving dialysis on discharge, the AKINow Committee conducted a group discussion comprising 59 participants, including physicians, advanced practitioners, nurses, pharmacists, and patients. The discussion was framed by a patient who described gaps in care delivery at different transition points and miscommunication between care team members and the patient.

RESULTS

Group discussions collected patient perspectives of ( 1 ) being often scared and uncertain about what is happening to and around them and ( 2 ) the importance of effective and timely communication, a comfortable physical setting, and attentive and caring health care providers for a quality health care experience. Provider perspectives included ( 1 ) the recognition of the lack of evidence-based practices and quality indicators, the significant variability in current care models, and the uncertain reimbursement incentives focused on kidney recovery and ( 2 ) the urgency to address communication barriers among hospital providers and outpatient facilities.

CONCLUSIONS

The workgroup identified key areas for future research and policy change to ( 1 ) improve communication among hospital providers, dialysis units, and patients/care partners; ( 2 ) develop tools for risk classification, subphenotyping, and augmented clinical decision support; ( 3 ) improve education to providers, staff, and patients/care partners; ( 4 ) identify best practices to improve relevant outcomes; ( 5 ) validate quality indicators; and ( 6 ) assess the effect of social determinants of health on outcomes. We urge all stakeholders involved in the process of AKI-D care to align goals and work together to fill knowledge gaps and optimize the care to this highly vulnerable patient population.

Dimethyl malonate preserves renal and mitochondrial functions following ischemia-reperfusion via inhibition of succinate dehydrogenase

BACKGROUND

Acute kidney injury (AKI), often experienced at the intensive care units, is associated with high morbidity/mortality where ischemia-reperfusion injury is a main causative factor. Succinate accumulation during ischemia contributes to the excessive generation of reactive oxygen species at reperfusion. Inhibition of succinate dehydrogenase has been associated with protective outcome in cardiac ischemia-reperfusion after 24h, but the effects on kidney and mitochondrial functions are less well studied.

AIM

To investigate the therapeutic potential of succinate dehydrogenase inhibition, by using dimethyl malonate (DMM), on kidney and mitochondria functions in a mouse model of AKI.

METHODS

Male C57BL/6J mice were pre-treated with DMM or placebo, i.p. 30min prior to bilateral renal ischemia (20min). After 3-days of reperfusion, glomerular filtration rate (GFR) was calculated from plasma clearance of FITC-inulin. Kidney mitochondria was isolated and mass specific and intrinsic mitochondrial function were evaluated by high resolution respirometry. Kidney sections were stained (i.e., hematoxylin-eosin and TUNEL) and analyzed for histopathological evaluation of injuries and apotosis, respectively. NADPH oxidase activity in kidney and human proximal tubular cell-line (HK2) were measured luminometrically.

RESULTS

DMM treatment improved GFR (p < 0.05) and reduced levels of blood urea nitrogen (p < 0.01) compared to untreated animals, which was associated with lower degree of ischemia-reperfusion-induced tubular injuries (P < 0.001) and apoptosis (P < 0.01). These therapeutic renal effects were linked with improved mitochondrial function, both mass-specific and intrinsic. Finally, DMM treatment prevented ischemia-reperfusion-induced NADPH oxidase activity in the kidney (p < 0.001), which was showed also in HK2 cells exposed to hypoxia and reoxygenation (P < 0.01).

CONCLUSION

Inhibition of succinate dehydrogenase with DMM, in conjunction with the ischemia-reperfusion phase, significantly improved both renal and mitochondrial functions. These findings may have clinical implications for future therapeutic strategies to prevent development of AKI and associated adverse complications, especially in high risk hospitalized patients.

Natural products applied in acute kidney injury treatment: polymer matters

Acute kidney injury (AKI) is a global health threat due to its high morbidity and mortality. There is still a lack of effective therapeutic methods to deal with AKI clinically. Natural products with outstanding accessibility and bioactivity are potential candidates for AKI treatment. Natural product-based prodrugs or nano-structures with improved properties are frequently fabricated for maximizing bioavailability and decreasing side effects, in which natural polymers are selected as carriers, or natural drugs are loaded as cargos on designed polymers. In this review, the etiologies of AKI are briefly presented, and emerging natural products delivered rationally for AKI therapy, as either carriers or cargos, are both introduced. Moreover, the challenges of the future development of nature-based nanodrugs or prodrugs for AKI have also been discussed.

Integrin β1-rich extracellular vesicles of kidney recruit Fn1+ macrophages to aggravate ischemia-reperfusion-induced inflammation

Ischemia-reperfusion injury-induced (IRI-induced) acute kidney injury is accompanied by mononuclear phagocyte (MP) invasion and inflammation. However, systematic analysis of extracellular vesicle-carried (EV-carried) proteins mediating intercellular crosstalk in the IRI microenvironment is still lacking. Multiomics analysis combining single-cell RNA-Seq data of kidney and protein profiling of kidney-EV was used to elucidate the intercellular communication between proximal tubular cells (PTs) and MP. Targeted adhesion and migration of various MPs were caused by the secretion of multiple chemokines as well as integrin β1-rich EV by ischemic-damaged PTs after IRI. These recruited MPs, especially Fn1+ macrophagocyte, amplified the surviving PT's inflammatory response by secreting the inflammatory factors TNF-α, MCP-1, and thrombospondin 1 (THBS-1), which could interact with integrin β1 to promote more MP adhesion and interact with surviving PT to further promote the secretion of IL-1β. However, GW4869 reduced MP infiltration and maintained a moderate inflammatory level likely by blocking EV secretion. Our findings establish the molecular bases by which chemokines and kidney-EV mediate PT-MP crosstalk in early IRI and provide insights into systematic intercellular communication.

DDRGK1-mediated ER-phagy attenuates acute kidney injury through ER-stress and apoptosis

Acute kidney injury (AKI) constitutes a prevalent clinical syndrome characterized by elevated morbidity and mortality rates, emerging as a significant public health issue. This study investigates the interplay between endoplasmic reticulum (ER) stress, unfolded protein response (UPR), and ER-associated degradation (ER-phagy) in the pathogenesis of AKI. We employed four distinct murine models of AKI-induced by contrast media, ischemia-reperfusion injury, cisplatin, and folic acid-to elucidate the relationship between ER-phagy, ER stress, and apoptosis. Our findings reveal a marked decrease in ER-phagy coinciding with an accumulation of damaged ER, elevated ER stress, and increased apoptosis across all AKI models. Importantly, overexpression of DDRGK1 in HK-2 cells enhanced ER-phagy levels, ameliorating contrast-induced ER stress and apoptosis. These findings unveil a novel protective mechanism in AKI, wherein DDRGK1-UFL1-mediated ER-phagy mitigates ER stress and apoptosis in renal tubular epithelial cells. Our results thereby contribute to understanding the molecular underpinnings of AKI and offer potential therapeutic targets for its treatment.

The nuclear factor kappa B signaling pathway is a master regulator of renal fibrosis

Renal fibrosis is increasingly recognized as a global public health problem. Acute kidney injury (AKI) and chronic kidney disease (CKD) both result in renal fibrosis. Oxidative stress and inflammation play central roles in progressive renal fibrosis. Oxidative stress and inflammation are closely linked and form a vicious cycle in which oxidative stress induces inflammation through various molecular mechanisms. Ample evidence has indicated that a hyperactive nuclear factor kappa B (NF-ƙB) signaling pathway plays a pivotal role in renal fibrosis. Hyperactive NF-ƙB causes the activation and recruitment of immune cells. Inflammation, in turn, triggers oxidative stress through the production of reactive oxygen species and nitrogen species by activating leukocytes and resident cells. These events mediate organ injury through apoptosis, necrosis, and fibrosis. Therefore, developing a strategy to target the NF-ƙB signaling pathway is important for the effective treatment of renal fibrosis. This Review summarizes the effect of the NF-ƙB signaling pathway on renal fibrosis in the context of AKI and CKD (immunoglobulin A nephropathy, membranous nephropathy, diabetic nephropathy, hypertensive nephropathy, and kidney transplantation). Therapies targeting the NF-ƙB signaling pathway, including natural products, are also discussed. In addition, NF-ƙB-dependent non-coding RNAs are involved in renal inflammation and fibrosis and are crucial targets in the development of effective treatments for kidney disease. This Review provides a clear pathophysiological rationale and specific concept-driven therapeutic strategy for the treatment of renal fibrosis by targeting the NF-ƙB signaling pathway.

Automated machine learning for early prediction of acute kidney injury in acute pancreatitis

BACKGROUND

Acute kidney injury (AKI) represents a frequent and grave complication associated with acute pancreatitis (AP), substantially elevating both mortality rates and the financial burden of hospitalization. The aim of our study is to construct a predictive model utilizing automated machine learning (AutoML) algorithms for the early prediction of AKI in patients with AP.

METHODS

We retrospectively analyzed patients who were diagnosed with AP in our hospital from January 2017 to December 2021. These patients were randomly allocated into a training set and a validation set at a ratio of 7:3. To develop predictive models for each set, we employed the least absolute shrinkage and selection operator (LASSO) algorithm along with AutoML. A nomogram was developed based on multivariate logistic regression analysis outcomes. The model's efficacy was assessed using receiver operating characteristic (ROC) curves, calibration curves, and decision curve analysis (DCA). Additionally, the performance of the model constructed via AutoML was evaluated using decision curve analysis (DCA), feature importance, SHapley Additive exPlanations (SHAP) plots, and locally interpretable model-agnostic explanations (LIME).

RESULTS

This study incorporated a total of 437 patients who met the inclusion criteria. Out of these, 313 were assigned to the training cohort and 124 to the validation cohort. In the training and validation cohorts, AKI occurred in 68 (21.7%) and 29(23.4%) patients, respectively. Comparative analysis revealed that the AutoML models exhibited enhanced performance over traditional logistic regression (LR). Furthermore, the deep learning (DL) model demonstrated superior predictive accuracy, evidenced by an area under the ROC curve of 0.963 in the training set and 0.830 in the validation set, surpassing other comparative models. The key variables identified as significant in the DL model within the training dataset included creatinine (Cr), urea (Urea), international normalized ratio (INR), etiology, smoking, alanine aminotransferase (ALT), hypertension, prothrombin time (PT), lactate dehydrogenase (LDH), and diabetes.

CONCLUSION

The AutoML model, utilizing DL algorithm, offers considerable clinical significance in the early detection of AKI among patients with AP.

Shear wave elastography: A noninvasive approach for assessing acute kidney injury in critically ill patients

Traditional markers, such as serum creatinine and blood urea nitrogen, frequently show delayed elevations following acute kidney injury (AKI), limiting their utility for prompt detection and timely intervention in AKI management. Shear wave elastography (SWE) exhibits potential for AKI diagnosis by measuring tissue stiffness. Our study aimed to evaluate the diagnostic performance of SWE in detecting AKI by measuring the stiffness of kidney tissue. Between July 2022 and December 2022, a total of 103 consecutive participants who met the eligibility criteria were prospectively enrolled, underwent SWE measurements, and were classified into AKI or non-AKI groups based on the 2012 Kidney Disease: Improving Global Outcomes (KDIGO) criteria. A receiver operating characteristic (ROC) curve was drawn to examine the feasibility of differentiating between AKI and non-AKI patients and assessing diagnostic performance. The effects of tissue anisotropy on SWE measurements were also examined. Our results revealed that patients in the AKI group exhibited significantly increased stiffness values in specific kidney regions compared with those in the non-AKI group. For the diagnosis of AKI, the optimal cut-off values were identified as 9.9 kPa, 2.9 kPa, and 4.4 kPa for the upper pole medulla, middle cortex, and middle medulla, respectively, in the longitudinal plane. Correspondingly, the areas under the ROC curves for these regions were 0.737 (95% confidence interval [CI]: 0.637, 0.822), 0.736 (95% CI: 0.637, 0.821), and 0.784 (95% CI: 0.688, 0.861). Additionally, we observed a significant variability in stiffness values due to tissue anisotropy, specifically in the segments of the upper pole cortex, and medulla across both longitudinal and transverse planes. SWE serves as a noninvasive approach for the quantification of tissue stiffness and shows promise as an adjunctive tool for the assessment of AKI.

Novel 3-hydroxypyridin-4(1H)-One derivatives as ferroptosis inhibitors with iron-chelating and reactive oxygen species scavenging activities and therapeutic effect in cisplatin-induced cytotoxicity

Recent advances in understanding the role of iron and ROS in cell death suggest new therapeutic avenues to treat organ damage including acute kidney injury (AKI). Inhibiting ferroptosis was expected to have great potential for the treatment of this disease. Ferroptosis is characterized by iron-dependent lipid peroxidation and currently, a majority of reported ferroptosis inhibitors belong to either radical-trapping antioxidants or iron chelators. However, clinically used iron chelators such as deferoxamine and deferiprone have limited efficacy against ferroptosis (generally with EC50 > 100 μM), despite their proven safety. Herein, we present the rational design of novel ferroptosis inhibitors by incorporating the naturally occurring cinnamic acid scaffold and the 3-hydroxypyridin-4(1H)-one iron-chelating pharmacophore. Through ABTS˙+ radical-scavenging assay, oxygen radical absorbance capacity (ORAC) measurement, Fe3+ affinity evaluation, and anti-erastin-induced HT22 cell ferroptosis assays, we identified compound 9c as the most prospective ferroptosis inhibitor (ABTS˙+, IC50 = 4.35 ± 0.05 μM; ORCA = 23.79 ± 0.56 TE; pFe3+ = 18.59; EC50 = 14.89 ± 0.08 μM, respectively). Notably, 9c dose-dependently alleviated cell death in cisplatin-induced AKI model. Our results provide insight into the development of new ferroptosis inhibitors through rational incorporation of pharmacophores from existing ferroptosis inhibitors, and compound 9c could be a promising lead compound worth further investigation.

Incidence of acute kidney injury (AKI) and its impact on patient outcomes among adult hospitalized patients with carbapenem-resistant Gram-negative infections who received targeted treatment with a newer β-lactam or β-lactam/β-lactamase inhibitor-, polymyxin- or aminoglycoside-containing regimen

BACKGROUND

Limited comparative data exist on acute kidney injury (AKI) risk and AKI-associated outcomes in hospitalized patients with carbapenem-resistant Gram-negative infections (CR-GNIs) treated with a newer β-lactam/β-lactam-β-lactamase inhibitor (BL/BL-BLI)-, polymyxin (PB)- or aminoglycoside (AG)-containing regimen. This study quantified the risk of AKI and AKI-related outcomes among patients with CR-GNIs treated with a newer BL/BL-BLI-, PB- or AG-containing regimen.

METHODS

A multicentre, retrospective, observational study was performed (2016-20). The study included adult hospitalized patients with (i) baseline estimated glomerular filtration rates ≥30 mL/min/1.73 m2; (ii) CR-GN pneumonia, complicated urinary tract infection or bloodstream infection; and (iii) receipt of newer BL/BL-BLI, PG or AG within 7 days of index CR-GN culture for ≥3 days. Outcomes included AKI, in-hospital mortality and hospital costs.

RESULTS

The study included 750 patients and most (48%) received a newer BL/BL-BLI. The median (IQR) treatment duration was 8 (5-11), 5 (4-8) and 7 (4-8) days in the newer BL/BL-BLI group, AG group and PB group, respectively. The PB group had the highest adjusted AKI incidence (95% CI) (PB: 25.1% (15.6%-34.6%) versus AG: 8.9% (5.7%-12.2%) versus newer BL/BL-BLI: 11.9% (8.1%-15.7%); P = 0.001). Patients with AKI had significantly higher in-hospital mortality (AKI: 18.5% versus 'No AKI': 5.6%; P = 0.001) and mean hospital costs (AKI: $49 192 versus 'No AKI': $38,763; P = 0.043).

CONCLUSIONS

The AKI incidence was highest among PB patients and patients with AKI had worse outcomes. Healthcare systems should consider minimizing the use of antibiotics that augment AKI risk as a measure to improve outcomes in patients with CR-GNIs.

Mortality and mode of dialysis: meta-analysis and systematic review

BACKGROUND

The global use of kidney replacement therapy (KRT) has increased, mirroring the incidence of acute kidney injury and chronic kidney disease. Despite its growing clinical usage, patient outcomes with KRT modalities remain controversial. In this meta-analysis, we sought to compare the mortality outcomes of patients with any kidney disease requiring peritoneal dialysis (PD), hemodialysis (HD), or continuous renal replacement therapy (CRRT).

METHODS

The investigation was conducted according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). PubMed (MEDLINE), Cochrane Library, and Embase databases were screened for randomized trials and observational studies comparing mortality rates with different KRT modalities in patients with acute or chronic kidney failure. A random-effects model was applied to compute the risk ratio (RR) and 95% confidence intervals (95%CI) with CRRT vs. HD, CRRT vs. PD, and HD vs. PD. Heterogeneity was assessed using I2 statistics, and sensitivity using leave-one-out analysis.

RESULTS

Fifteen eligible studies were identified, allowing comparisons of mortality risk with different dialytic modalities. The relative risk was non-significant in CRRT vs. PD [RR = 0.95, (95%CI 0.53, 1.73), p = 0.92 from 4 studies] and HD vs. CRRT [RR = 1.10, (95%CI 0.95, 1.27), p = 0.21 from five studies] comparisons. The findings remained unchanged in the leave-one-out sensitivity analysis. Although PD was associated with lower mortality risk than HD [RR = 0.78, (95%CI 0.62, 0.97), p = 0.03], the significance was lost with the exclusion of 4 out of 5 included studies.

CONCLUSION

The current evidence indicates that while patients receiving CRRT may have similar mortality risks compared to those receiving HD or PD, PD may be associated with lower mortality risk compared to HD. However, high heterogeneity among the included studies limits the generalizability of our findings. High-quality studies comparing mortality outcomes with different dialytic modalities in CKD are necessary for a more robust safety and efficacy evaluation.

The Beneficial Effects of Mesenchymal Stem Cells in Acute Kidney Injury: A Narrative Review

BACKGROUND

Acute kidney injury (AKI) is a multifaced disease characterized by a rapid decline in renal function. However, with growing insight into the pathophysiologic mechanisms of AKI, currently available interventions for AKI are merely supportive. Thus, novel therapies are urgently needed to improve the outcomes of patients with AKI. This narrative review aims to explore enhancing the beneficial effects of Mesenchymal Stem Cells(MSCs) in AKI.

METHODS

The authors examined all studies regarding the role of MSCs in AKI. And the authors undertook a structured search of bibliographic databases for peer-reviewed research literature using a focused review question. The most relevant and up-to-date research was included.

RESULTS AND DISCUSSION

Based on encouraging preclinical results, stem cell therapy has been widely explored over the last decade. Among the various stem cell types investigated, mesenchymal stem cells are being intensely investigated by virtue of their numerous strengths, such as easy derivation, undemanding cell culture conditions, anti-apoptosis, immunomodulation, and anti-inflammation effects. Mounting evidence suggests that MSCs hold great potential in accelerating kidney repair following AKI in various preclinical models. Unfortunately, low engrafting efficiency and poor survival rate of injected MSCs in the injured renal tissue are major obstacles MSCs clinical application faces.

CONCLUSION

Various strategies, including genetic manipulation, mimicking the cellular microenvironment with different culture conditions, optimizing MSCs preparation and administration schedule, and screening patients who may more like benefit from MSCs therapy, have been developed to enhance the therapeutic potential of MSCs in AKI.

Protective effect of small extracellular vesicles (EVs) derived from ACE2-modified human umbilical cord mesenchymal stem cells against renal ischemia-reperfusion injury

AIM

Acute kidney injury is a severe disease that is closely associated with substantial morbidity and mortality. The most common cause of AKI is renal ischemia-reperfusion injury. Mesenchymal stem cells (MSCs) have previously been shown to have renoprotective effects. However, extracellular vesicles secreted by MSCs are thought to be the key for the therapeutic effects of MSCs. This study investigated whether small EVs derived from ACE2-modified human umbilical cord MSCs could alleviate RIRI and explored their underlying molecular mechanisms METHODS: A lentivirus carrying an ACE2 overexpression vector was constructed and used to infect MSCs. The small EVs were isolated from MSC-conditioned medium by ultracentrifugation. HK-2 cells were cocultured with MSC-ACE2-EVs and subjected to hypoxia/reoxygenation injury. MSCs-ACE2-EVs were injected into RIRI mice. Biochemical and morphological characteristics were assessed, and the levels of inflammatory-related factors, oxidative stress products, and apoptosis in HK-2 cells and kidney tissues were assessed RESULTS: In vitro, MSC-ACE2-EVs had stronger anti-inflammatory, antioxidative stress, and antiapoptotic effects in HK-2 cells subjected to H/R than MSC-NC-EVs. In vivo, MSC-ACE2-EVs could target the injured kidney, reduce blood creatinine and urea nitrogen levels, and protect the kidney from I/R, and this effect may have been related to the activation of the Nrf2/HO-1 signalling pathway CONCLUSION: Taken together, our results demonstrated the anti-inflammatory, antioxidative stress, and antiapoptotic effects of MSC-ACE2-EVs, which protected against I/R injury in vitro and vivo. MSC-ACE2-EVs may be therapeutic agents for RIRI.

11. Chronic Kidney Disease and Risk Management: Standards of Care in Diabetes-2024

The American Diabetes Association (ADA) "Standards of Care in Diabetes" includes the ADA's current clinical practice recommendations and is intended to provide the components of diabetes care, general treatment goals and guidelines, and tools to evaluate quality of care. Members of the ADA Professional Practice Committee, an interprofessional expert committee, are responsible for updating the Standards of Care annually, or more frequently as warranted. For a detailed description of ADA standards, statements, and reports, as well as the evidence-grading system for ADA's clinical practice recommendations and a full list of Professional Practice Committee members, please refer to Introduction and Methodology. Readers who wish to comment on the Standards of Care are invited to do so at professional.diabetes.org/SOC.

Adherence to guidelines for management of acute kidney injury

BACKGROUND AND AIM

Acute kidney injury (AKI) affects a significant number of patients and the prognosis for this condition remains poor. The aim of this study was to assess adherence to KDIGO clinical practice guidelines and identify areas for improvement.

METHODS

For this retrospective study, data were extracted from the medical database of the University Hospital Brandenburg, for patients who had been diagnosed with AKI from January to March 2021. Implementation rates of eight KDIGO AKI therapeutic measures were analyzed in relation to several AKI severity/risk categories.

RESULTS

Data from 200 patients were included in the study. Three specific measures were commonly implemented: hyperglycemia control (100%), volume therapy (82%), and fluid balance management (65%). Nephrotoxic medications were discontinued in 51% patients, while iodinated contrast media was used in 35% patients. Patients with an increased risk of complications, such as those requiring ICU therapy or with sepsis, received these measures more frequently.

CONCLUSIONS

While some 2012 KDIGO recommended measures were implemented for a substantial number of affected individuals, others were not. Our study highlights the need for improvement in the quality of care for patients with AKI.

Fatty Acid Binding Protein-4 Silencing Inhibits Ferroptosis to Alleviate Lipopolysaccharide-induced Injury of Renal Tubular Epithelial Cells by Blocking Janus Kinase 2/Signal Transducer and Activator of Transcription 3 Signaling

Sepsis-induced kidney injury (SAKI) has been frequently established as a prevailing complication of sepsis which is linked to unfavorable outcomes. Fatty acid-binding protein-4 (FABP4) has been proposed as a possible target for the treatment of SAKI. In the current work, we aimed to explore the role and underlying mechanism of FABP4 in lipopolysaccharide (LPS)-induced human renal tubular epithelial cell damage. In LPS-induced human kidney 2 (HK2) cells, FABP4 expression was tested by the reverse transcription-quantitative polymerase chain reaction and Western blot. Cell counting kit-8 method assayed cell viability. Inflammatory levels were detected using the enzyme-linked immunosorbent assay. Immunofluorescence staining measured the nuclear translocation of nuclear factor kappa B p65. Thiobarbituric acid-reactive substances assay and C11 BODIPY 581/591 probe were used to estimate the level of cellular lipid peroxidation. Fe2+ content was examined by the kit. In addition, the expression of proteins related to inflammation-, ferroptosis- and Janus kinase 2 (JAK2)/signal transducer, and activator of transcription 3 (STAT3) signaling was detected by the Western blot analysis. The results revealed that FABP4 was significantly upregulated in LPS-treated HK2 cells, the knockdown of which elevated the viability, whereas alleviated the inflammation and ferroptosis in HK2 cells challenged with LPS. In addition, down-regulation of FABP4 inactivated JAK2/STAT3 signaling. JAK2/STAT3 stimulator (colivelin) and ferroptosis activator (Erastin) partially restored the effects of FABP4 interference on LPS-triggered inflammation and ferroptosis in HK2 cells. Together, FABP4 knockdown inhibited ferroptosis to alleviate LPS-induced injury of renal tubular epithelial cells through suppressing JAK2/STAT3 signaling.

Human Kidney Proximal Tubule-Microvascular Model Facilitates High-Throughput Analyses of Structural and Functional Effects of Ischemia-Reperfusion Injury

Kidney ischemia reperfusion injury (IRI) poses a major global healthcare burden, but effective treatments remain elusive. IRI involves a complex interplay of tissue-level structural and functional changes caused by interruptions in blood and filtrate flow and reduced oxygenation. Existing in vitro models poorly replicate the in vivo injury environment and lack means of monitoring tissue function during the injury process. Here, a high-throughput human primary kidney proximal tubule (PT)-microvascular model is described, which facilitates in-depth structural and rapid functional characterization of IRI-induced changes in the tissue barrier. The PREDICT96 (P96) microfluidic platform's user-controlled fluid flow can mimic the conditions of IR to induce pronounced changes in cell structure that resemble clinical and in vivo phenotypes. High-throughput trans-epi/endo-thelial electrical resistance (TEER) sensing is applied to non-invasively track functional changes in the PT-microvascular barrier during the two-stage injury process and over repeated episodes of injury. Notably, ischemia causes an initial increase in tissue TEER followed by a sudden increase in permeability upon reperfusion, and this biphasic response occurs only with the loss of both fluid flow and oxygenation. This study demonstrates the potential of the P96 kidney IRI model to enhance understanding of IRI and fuel therapeutic development.

New biomarkers in acute kidney injury

Acute kidney injury (AKI) is a commonly encountered clinical syndrome. Although it often complicates community acquired illness, it is more common in hospitalized patients, particularly those who are critically ill or who have undergone major surgery. Approximately 20% of hospitalized adult patients develop an AKI during their hospital care, and this rises to nearly 60% in the critically ill, depending on the population being considered. In general, AKI is more common in older adults, in those with preexisting chronic kidney disease and in those with known risk factors for AKI (including diabetes and hypertension). The development of AKI is associated with an increase in both mortality and morbidity, including the development of post-AKI chronic kidney disease. Currently, AKI is defined by a rise in serum creatinine from either a known or derived baseline value and/or oliguria or anuria. However, clinicians may fail to recognize the initial development of AKI because of a delay in the rise of serum creatinine or because of inaccurate urine output monitoring. This, in turn, delays any putative measures to treat AKI or to limit its degree. Consequently, efforts have focused on new biomarkers associated with AKI that may allow early recognition of this syndrome with the intent that this will translate into improved patient outcomes. Here we outline current biomarkers associated with AKI and explore their potential in aiding diagnosis, understanding the pathophysiology and directing therapy.

Multiparametric Magnetic Resonance Investigations on Acute and Long-Term Kidney Injury

Acute kidney injury (AKI) is a frequent complication of critical illness and carries a significant risk of short- and long-term mortality. The prediction of the progression of AKI to long-term injury has been difficult for renal disease treatment. Radiologists are keen for the early detection of transition from AKI to long-term kidney injury, which would help in the preventive measures. The lack of established methods for early detection of long-term kidney injury underscores the pressing needs of advanced imaging technology that reveals microscopic tissue alterations during the progression of AKI. Fueled by recent advances in data acquisition and post-processing methods of magnetic resonance imaging (MRI), multiparametric MRI is showing great potential as a diagnostic tool for many kidney diseases. Multiparametric MRI studies offer a precious opportunity for real-time noninvasive monitoring of pathological development and progression of AKI to long-term injury. It provides insight into renal vasculature and function (arterial spin labeling, intravoxel incoherent motion), tissue oxygenation (blood oxygen level-dependent), tissue injury and fibrosis (diffusion tensor imaging, diffusion kurtosis imaging, T1 and T2 mapping, quantitative susceptibility mapping). The multiparametric MRI approach is highly promising but the longitudinal investigation on the transition of AKI to irreversible long-term impairment is largely ignored. Further optimization and implementation of renal MR methods in clinical practice will enhance our comprehension of not only AKI but chronic kidney diseases. Novel imaging biomarkers for microscopic renal tissue alterations could be discovered and benefit the preventative interventions. This review explores recent MRI applications on acute and long-term kidney injury while addressing lingering challenges, with emphasis on the potential value of the development of multiparametric MRI for renal imaging on clinical systems. EVIDENCE LEVEL: 1 TECHNICAL EFFICACY: Stage 2.

Optimum Care of AKI Survivors Not Requiring Dialysis after Discharge: An AKINow Recovery Workgroup Report

AKI survivors experience gaps in care that contribute to worse outcomes, experience, and cost.Challenges to optimal care include issues with information transfer, education, collaborative care, and use of digital health tools.Research is needed to study these challenges and inform optimal use of diagnostic and therapeutic interventions to promote recovery AKI affects one in five hospitalized patients and is associated with poor short-term and long-term clinical and patient-centered outcomes. Among those who survive to discharge, significant gaps in documentation, education, communication, and follow-up have been observed. The American Society of Nephrology established the AKINow taskforce to address these gaps and improve AKI care. The AKINow Recovery workgroup convened two focus groups, one each focused on dialysis-independent and dialysis-requiring AKI, to summarize the key considerations, challenges, and opportunities in the care of AKI survivors. This article highlights the discussion surrounding care of AKI survivors discharged without the need for dialysis. On May 3, 2022, 48 patients and multidisciplinary clinicians from diverse settings were gathered virtually. The agenda included a patient testimonial, plenary sessions, facilitated small group discussions, and debriefing. Core challenges and opportunities for AKI care identified were in the domains of transitions of care, education, collaborative care delivery, diagnostic and therapeutic interventions, and digital health applications. Integrated multispecialty care delivery was identified as one of the greatest challenges to AKI survivor care. Adequate templates for communication and documentation; education of patients, care partners, and clinicians about AKI; and a well-coordinated multidisciplinary posthospital follow-up plan form the basis for a successful care transition at hospital discharge. The AKINow Recovery workgroup concluded that advancements in evidence-based, patient-centered care of AKI survivors are needed to improve health outcomes, care quality, and patient and provider experience. Tools are being developed by the AKINow Recovery workgroup for use at the hospital discharge to facilitate care continuity.

Madecassoside alleviates acute kidney injury by regulating JNK-mediated oxidative stress and programmed cell death

BACKGROUND

Acute kidney injury (AKI) has high morbidity and mortality, which is manifested by inflammation and apoptosis. Effective treatment methods for AKI are currently lacking.

OBJECTIVE

This study demonstrated the protecting effects of Madecassoside (MA) in the cisplatin- and hypoxia-reoxygenation-induced renal tubular epithelial cells in vitro and AKI mice in vivo.

METHODS

In vivo AKI mouse models were established by inducing them with cisplatin and renal ischemia-reperfusion. In vitro injury models of mouse renal tubular epithelial cells were established by inducing them with cisplatin and hypoxia and reoxygenation, respectively. The mechanism of MA effects was further explored using molecular docking and RNA-sequencing.

RESULTS

MA could significantly reduce kidney injury in the cisplatin-and renal ischemia-reperfusion (IRI)-induced AKI. Further validation in the two cellular models also showed that MA had protect effects. MA can alleviate AKI in vitro and in vivo by inhibiting inflammation, cell apoptosis, and oxidative stress. MA exhibited high permeability across the Caco-2 cell, can enter cells directly. Through RNA-seq and molecular docking analysis, this study further demonstrated that MA inhibits its activity by directly binding to JNK kinase, thereby inhibiting c-JUN mediated cell apoptosis and improving AKI. In addition, MA has better renal protective effects compared to curcumin and JNK inhibitor SP600125.

CONCLUSION

The results demonstrate that MA might be a potential drug for the treatment of AKI and act through the JNK/c-JUN signaling pathway.

CD36 promotes tubular ferroptosis by regulating the ubiquitination of FSP1 in acute kidney injury

Reactive oxidative species (ROS) production-driven ferroptosis plays a role in acute kidney injury (AKI). However, its exact molecular mechanism is poorly understood. Scavenger receptor CD36 has important roles in oxidizing lipids, lipid accumulation, metabolic syndrome, and insulin resistance in chronic kidney disease, but its roles remain unexplored in AKI. The present study investigated the role and mechanism of CD36 in regulating proximal tubular cell ferroptosis and AKI. The expression of CD36 was found to be significantly up-regulated in AKI renal tissues and correlated with renal function, which might serve as an independent biomarker for AKI patients. Moreover, in adult mice subjected to AKI, deletion of CD36 (CD36-/-) induced tubular cell ROS accumulation, ferroptosis activation, and renal injury. Mechanistically, combining LC-MS/MS, co-IP, and ubiquitination analyses revealed that CD36 could specifically bind to ferroptosis suppressor protein 1 (FSP1) and regulate its ubiquitination at sites K16 and K24, leading to FSP1 degradation and progression of ferroptosis in AKI. The present results emphasize a novel mechanism of CD36 in cisplatin-induced AKI. The discovery of the special CD36 roles in promoting ferroptosis and AKI development by regulating the ubiquitination of FSP1 in proximal tubular cells may be potential therapeutic targets for AKI. Moreover, CD36 may play a key role in the progression of AKI. Therefore, targeting CD36 may provide a promising treatment option for AKI.