Sepsis-induced AKI: From pathogenesis to therapeutic approaches

A promising application of kidney-specific cell-free DNA methylation markers in real-time monitoring sepsis-induced acute kidney injury

Sepsis-induced acute kidney injury (SI-AKI) is a common clinical syndrome that is associated with high mortality and morbidity. Effective timely detection may improve the outcome of SI-AKI. Kidney-derived cell-free DNA (cfDNA) may provide new insight into understanding and identifying SI-AKI. Plasma cfDNA from 82 healthy individuals, 7 patients with sepsis non-acute kidney injury (SN-AKI), and 9 patients with SI-AKI was subjected to genomic methylation sequencing. We deconstructed the relative contribution of cfDNA from different cell types based on cell-specific methylation markers and focused on exploring the association between kidney-derived cfDNA and SI-AKI.Based on the deconvolution of the cfDNA methylome: SI-AKI patients displayed the elevated cfDNA concentrations with an increased contribution of kidney epithelial cells (kidney-Ep) DNA; kidney-Ep derived cfDNA achieved high accuracy in distinguishing SI-AKI from SN-AKI (AUC = 0.92, 95% CI 0.7801-1); the higher kidney-ep cfDNA concentrations tended to correlate with more advanced stages of SI-AKI; strikingly, SN-AKI patients with potential kidney damage unmet by SI-AKI criteria showed higher levels of kidney-Ep derived cfDNA than healthy individuals. The autonomous screening of kidney-Ep (n = 24) and kidney endothelial (kidney-Endo, n = 12) specific methylation markers indicated the unique identity of kidney-Ep/kidney-Endo compared with other cell types, and its targeted assessment reproduced the main findings of the deconvolution of the cfDNA methylome. Our study first demonstrates that kidney-Ep- and kidney-Endo-specific methylation markers can serve as a novel marker for SI-AKI emergence, supporting further exploration of the utility of kidney-specific cfDNA methylation markers in the study of SI-AKI.

Interleukin-10: Genetic and biochemical prediction of sepsis-induced acute kidney injury in critically ill patients in intensive care unit: A cross-sectional study

BACKGROUND

Sepsis is a potentially life-threatening condition that eventually causes multiorgan dysfunction in critically ill patients. Acute kidney injury (AKI) is a severe life-threatening complication of sepsis, a condition termed sepsis-induced AKI (S-AKI), with poor clinical outcomes and high mortality rates. Inflammatory and immunological responses are important variables in S-AKI. This study aimed to examine the relationship of rs1518111 polymorphism in the interleukin-10 ( IL-10 ) gene and serum/urine IL-10 levels with sepsis-induced AKI in critically ill patients in the intensive care unit (ICU).

METHODS

In this cross-sectional study, 310 critically ill adult patients were recruited, of whom, 197 developed S-AKI. Real-time polymerase chain reaction was performed to detect the rs1518111 polymorphism. Circulating blood and urine IL-10 levels of IL-10 were measured.

RESULTS

For rs1518111 SNP, the presence of at least one T allele increased the risk of occurrence of S-AKI (odds ratio [OR]: 1.34, 95% CI: 1.07-3.17; p < 0.001), regardless of the type of infection and severity of sepsis. Blood and urine IL-10 levels were an excellent prediction of S-AKI (area under the receiver operating characteristic curve [AUC]: 0.881 and 0.953 and sensitivity: 90.2% and 97.6% at cutoff of 133.5 and 5.67 pg/mL, respectively). Regression analysis showed that white blood cell count and increased blood and urine IL-10 levels, in addition to the presence of TT genotype, are independent risk factors for S-AKI.

CONCLUSION

rs1518111 polymorphism in the IL-10 gene is a risk factor for sepsis-induced AKI in the ICU. Serum/urine IL-10 levels may be used as predictors of S-AKI in critically ill patients with sepsis, thereby improving early management.

Fibronectin type III domain containing protein 5/irisin alleviated sepsis-induced acute kidney injury by abating ferroptosis through the adenosine 5'-monophosphate-activated protein kinase/nuclear factor erythroid-2-related factor 2 signaling pathway

Objective

Ferroptosis has been described in association with acute kidney injury (AKI)-induced sepsis. Fibronectin type III domain containing protein 5 (FNDC5)/irisin plays a crucial role in renal protection. The objective of this study was to investigate whether FNDC5/irisin is involved in AKI-induced sepsis by modulating ferroptosis, and the molecular mechanisms that may be involved.

Material and Methods

A sepsis-induced AKI model was built in vivo and in vitro through lipopolysaccharide (LPS) intervention. FNDC5, adenosine 5'-monophosphate-activated protein kinase (AMPK), phospho-AMPK (p-AMPK), nuclear factor erythroid-2-related factor 2 (Nrf2), heme oxygenase-1 (HO-1), glutathione peroxidase 4 (GPX4), and acyl-CoA synthetase long-chain family member 4 (ACSL4) concentrations in cells and mouse kidney tissues were appraised by Western blot. Pro-inflammatory cytokines concentrations in cell supernatants and mouse kidney tissues were appraised by enzyme-linked immunosorbent assay. Fe2+ concentration in cells and mouse kidney tissue was appraised by kit. The apoptosis rate of cells and mouse kidney tissue was measured by flow cytometry. Automatic biochemical analyzer was to test serum creatinine (SCr) and blood urea nitrogen (BUN). The kidney tissue sections from each groups were observed by hematoxylin and eosin staining.

Results

LPS abated FNDC5 concentration in human kidney-2 cells and mouse kidney tissue (P < 0.001). Overexpression of FNDC5 can abated proinflammatory cytokines concentrations in cells and mouse kidney tissue (P < 0.01). Meanwhile, overexpression of FNDC5 can boost GPX4 protein concentration, abate ACSL4 protein, and abate Fe2+ concentration in cells and mouse kidney tissues (P < 0.05). In addition, the overexpression of FNDC5 can reduce the rate of apoptosis (P < 0.01). In vivo experiments showed that FNDC5 overexpression reduced serum BUN and SCr concentrations and alleviated pathological damage in the mouse renal tissues (P < 0.05) and exhibited a certain renal protective effect. FNDC5 overexpression can boost p-AMPK/AMPK, Nrf2, and HO-1 protein concentrations (P < 0.01).

Conclusion

FNDC5/irisin improves sepsis-induced acute renal injury by abating ferroptosis through the AMPK/Nrf2 signaling pathway.

LncRNA AP001007 protects human renal tubular epithelial HK-2 cells and kidney organoids from LPS-induced injury

The regulation of long non-coding RNAs (lncRNAs) has been implicated in the pathogenesis of sepsis-induced acute kidney injury (SI-AKI). Nevertheless, the specific roles of individual lncRNAs in this process remain unclear. This study investigated the expression of lncRNA AP001007 in lipopolysaccharide (LPS)-induced HK-2 cells and in the peripheral blood of sepsis patients. The result shows that LPS treatment downregulated the expression of AP001007 in HK-2 cells and that circulating levels of AP001007 were lower in sepsis patients. Furthermore, overexpressing AP001007 in HK-2 cells improved cell viability, mitochondrial activity, and survival when exposed to LPS. Additionally, LPS-treated HK-2 cells secreted fewer pro-inflammatory cytokines when AP001007 was overexpressed. Similar protective effects were observed in human kidney organoids (HKOs) subjected to LPS. These findings suggest that AP001007 confers protection against LPS-induced damage in HK-2 cells and HKOs, highlighting its potential as a regulator of SI-AKI.

Diagnostic and Prognostic Values of KLF5 and RUNX1 in Acute Kidney Injury in Septic Patients

Diagnostic and prognostic values of Kruppel-like factor 5 (KLF5) and Runt-related transcription factor 1 (RUNX1) were determined in sepsis-induced acute kidney injury (SI-AKI). The study included 120 septic patients and set two groups: SI-AKI group (n = 60) or non-AKI group (n = 60). Fasting venous blood was drawn, and KLF5 and RUNX1 levels were measured. The receiver operating characteristic curve was plotted for diagnostic evaluation of KLF5 and RUNX1 in SI-AKI. The correlation between KLF5 and RUNX1 and serum creatinine (Scr), cystatin C (Cys-C), and kidney injury molecule 1 (KIM-1) were assessed by Pearson method. Predictive values of KLF5 and RUNX1 in 28-day survival of SI-AKI patients were considered by Kaplan-Meier survival curves and multivariate Cox regression analysis. Serum KLF5 and RUNX1 in SI-AKI patients were upregulated. Serum KLF5 and RUNX1 were of high diagnostic value in distinguishing SI-AKI patients from non-AKI patients. KLF5 and RUNX1 were in a positive correlation with Scr, Cys-C, and KIM-1, respectively. The 28-day survival of SI-AKI patients with high serum KLF5 or RUNX1 expression was poor, and serum KLF5 and RUNX1 expression were independently correlated with SI-AKI patients' survival. KLF5 and RUNX1 have diagnostic and prognostic values in SI-AKI patients.

The role of inflammatory response and metabolic reprogramming in sepsis-associated acute kidney injury: mechanistic insights and therapeutic potential

Sepsis represents a severe condition characterized by organ dysfunction resulting from a dysregulated host response to infection. Among the organs affected, the kidneys are particularly vulnerable, with significant functional impairment that markedly elevates mortality rates. Previous researches have highlighted that both inflammatory response dysregulation and metabolic reprogramming are crucial in the onset and progression of sepsis associated acute kidney injury (SA-AKI), making these processes potential targets for innovative therapies. This study aims to elucidate the pathophysiological mechanisms of renal injury in sepsis by perspective of inflammatory response dysregulation, with particular emphasis on pyroptosis, necroptosis, autophagy, and ferroptosis. Furthermore, it will incorporate insights into metabolic reprogramming to provide a detailed analysis of the mechanisms driving SA-AKI and explore potential targeted therapeutic strategies, providing solid theoretical framework for the development of targeted therapies for SA-AKI.

Role of Deoxyribonucleic Acid Origami for Alleviating Kidney and Liver Injury in Diabetic Sepsis

Treating diabetic sepsis (DS) can be challenging because of the persistent infection of multiple organs. To address this complicated pathological condition, it is necessary to develop advanced materials and gain a better understanding of their roles. In this study, we developed a two-dimensional planar material with a rectangular deoxyribonucleic acid origami nanostructure (termed Rec-DON). Rec-DON was used to improve liver and renal function in DS mice, as it preferentially accumulates in these organs, and has superior anti-inflammatory activity and the ability to scavenge reactive oxygen species. The role of Rec-DON in the treatment of DS mice was investigated via quantitative proteomics. This study revealed that Rec-DON can regulate key proteins located primarily in the cytoplasm and mitochondrion, involved in protein transport, antigen processing and presentation, and steroid metabolic process, and can also bind to various proteins to restore liver and renal function in DS mice. This study presented Rec-DON as a liver and kidney targeting material and revealed its role in alleviating multiorgan injury in DS.

Nanoparticles constructed from natural polyphenols are used in acute kidney injury

Acute kidney injury (AKI) is a severe clinical syndrome characterized by rapid deterioration of renal function caused by a variety of pathogeneses. Natural polyphenols have been considered to have potential in the treatment of AKI due to their powerful antioxidant and anti-inflammatory activities, but their low bioavailability in vivo limits their efficacy. Polyphenol nanoparticles based on a nano-delivery system show good effects in reducing kidney injury, improving renal function and promoting renal tissue repair, and brings new hope and possibility for the treatment of AKI. This review provides an overview of the common characteristics, treatments, and associated adverse effects of AKI. The classification and bioavailability of polyphenols as well as their therapeutic role in AKI and potential possible effects are outlined. The potential therapeutic effects of polyphenol-based nanoparticles on AKI and the underlying mechanisms are discussed.

Sepsis Biomarkers: Advancements and Clinical Applications-A Narrative Review

Sepsis is now defined as a life-threatening syndrome of organ dysfunction triggered by a dysregulated host response to infection, posing significant challenges in critical care. The main objective of this review is to evaluate the potential of emerging biomarkers for early diagnosis and accurate prognosis in sepsis management, which are pivotal for enhancing patient outcomes. Despite advances in supportive care, traditional biomarkers like C-reactive protein and procalcitonin have limitations, and recent studies have identified novel biomarkers with increased sensitivity and specificity, including circular RNAs, HOXA distal transcript antisense RNA, microRNA-486-5p, protein C, triiodothyronine, and prokineticin 2. These emerging biomarkers hold promising potential for the early detection and prognostication of sepsis. They play a crucial role not only in diagnosis but also in guiding antibiotic therapy and evaluating treatment effectiveness. The introduction of point-of-care testing technologies has brought about a paradigm shift in biomarker application, enabling swift and real-time patient evaluation. Despite these advancements, challenges persist, notably concerning biomarker variability and the lack of standardized thresholds. This review summarizes the latest advancements in sepsis biomarker research, spotlighting the progress and clinical implications. It emphasizes the significance of multi-biomarker strategies and the feasibility of personalized medicine in sepsis management. Further verification of biomarkers on a large scale and their integration into clinical practice are advocated to maximize their efficacy in future sepsis treatment.

PTEN in kidney diseases: a potential therapeutic target in preventing AKI-to-CKD transition

Renal fibrosis, a critical factor in the development of chronic kidney disease (CKD), is predominantly initiated by acute kidney injury (AKI) and subsequent maladaptive repair resulting from pharmacological or pathological stimuli. Phosphatase and tensin homolog (PTEN), also known as phosphatase and tensin-associated phosphatase, plays a pivotal role in regulating the physiological behavior of renal tubular epithelial cells, glomeruli, and renal interstitial cells, thereby preserving the homeostasis of renal structure and function. It significantly impacts cell proliferation, apoptosis, fibrosis, and mitochondrial energy metabolism during AKI-to-CKD transition. Despite gradual elucidation of PTEN's involvement in various kidney injuries, its specific role in AKI and maladaptive repair after injury remains unclear. This review endeavors to delineate the multifaceted role of PTEN in renal pathology during AKI and CKD progression along with its underlying mechanisms, emphasizing its influence on oxidative stress, autophagy, non-coding RNA-mediated recruitment and activation of immune cells as well as renal fibrosis. Furthermore, we summarize prospective therapeutic targeting strategies for AKI and CKD-treatment related diseases through modulation of PTEN.

The Protecting Role of Black Seed Oil and Its Nano-Formulation in LPS-Induced Acute Kidney Injury in Mice: Evaluation of Oxidative Stress, Biochemical & Molecular Parameters

Background

Acute kidney injury (AKI) is a medical concern that is accompanied by the rapid deterioration of kidney function. It can be triggered by lipopolysaccharide (LPS) of gram-negative bacteria as it activates a complicated immune response, resulting in widespread inflammation and potential organ dysfunction. Black seed oil (BSO) is rich in beneficial constituents and has been widely used owing to its nutritional advantages.

Purpose

This research is aimed to investigate the potential protective effects of BSO and its nano-formulation on AKI induced by LPS. It also aimed to compare their anti-inflammatory activity with indomethacin, a known synthetic anti-inflammatory drug.

Materials and Methods

Forty-eight mice were placed randomly into 8 groups. A single intraperitoneal (i.p.) injection of 2.5 mg/kg B.W. of LPS was used to trigger inflammation, and pretreatment with BSO and its nano-formulation was at 0.2 mL/kg/day for 14 consecutive days. Indomethacin was used as a reference drug and its efficacy was tested alone or in combination with BSO at lower doses. Renal function was assessed using urea, creatinine, neutrophil gelatinase-associated lipocalin (NGAL) and kidney injury molecule-1 (KIM-1). Also, oxidative and inflammatory markers were assessed by measuring levels of reduced glutathione (GSH), nitric oxide (NO), cyclooxygenase-2 (COX-2), tumor necrosis factor alpha (TNF-α), and toll-like receptor-4 (TLR-4). Histopathological examination of the kidney tissues was also performed.

Results

The study showed that BSO and its nano-formulation had anti-inflammatory effects comparable to or better than those of indomethacin. They greatly decreased the oxidative stress and inflammatory markers induced by LPS. Their protective effect against pathological alterations in kidney tissues was significantly noticed.

Conclusion

BSO and its nano-formulation could be used as nephroprotective and anti-inflammatory supplements.

Nucleic acid-based nanotherapeutics for treating sepsis and associated organ injuries

In recent years, gene therapy has been made possible with the success of nucleic acid drugs against sepsis and its related organ dysfunction. Therapeutics based on nucleic acids such as small interfering RNAs (siRNAs), microRNAs (miRNAs), messenger RNAs (mRNAs), and plasmid DNAs (pDNAs) guarantee to treat previously undruggable diseases. The advantage of nucleic acid-based therapy against sepsis lies in the development of nanocarriers, achieving targeted and controlled gene delivery for improved efficacy with minimal adverse effects. Entrapment into nanocarriers also ameliorates the poor cellular uptake of naked nucleic acids. In this study, we discuss the current state of the art in nanoparticles for nucleic acid delivery to treat hyperinflammation and apoptosis associated with sepsis. The optimized design of the nanoparticles through physicochemical property modification and ligand conjugation can target specific organs-such as lung, heart, kidney, and liver-to mitigate multiple sepsis-associated organ injuries. This review highlights the nanomaterials designed for fabricating the anti-sepsis nanosystems, their physicochemical characterization, the mechanisms of nucleic acid-based therapy in working against sepsis, and the potential for promoting the therapeutic efficiency of the nucleic acids. The current investigations associated with nanoparticulate nucleic acid application in sepsis management are summarized in this paper. Noteworthily, the potential application of nanotherapeutic nucleic acids allows for a novel strategy to treat sepsis. Further clinical studies are required to confirm the findings in cell- and animal-based experiments. The capability of large-scale production and reproducibility of nanoparticle products are also critical for commercialization. It is expected that numerous anti-sepsis possibilities will be investigated for nucleic acid-based nanotherapeutics in the future.

EARLY FLUID PLUS NOREPINEPHRINE RESUSCITATION DIMINISHES KIDNEY HYPOPERFUSION AND INFLAMMATION IN SEPTIC NEWBORN PIGS

ABSTRACT

Sepsis is the most frequent risk factor for acute kidney injury (AKI) in critically ill infants. Sepsis-induced dysregulation of kidney microcirculation in newborns is unresolved. The objective of this study was to use the translational swine model to evaluate changes in kidney function during the early phase of sepsis in newborns and the impact of fluid plus norepinephrine resuscitation. Newborn pigs (3-7-day-old) were allocated randomly to three groups: 1) sham, 2) sepsis (cecal ligation and puncture) without subsequent resuscitation, and 3) sepsis with lactated Ringer plus norepinephrine resuscitation. All animals underwent standard anesthesia and mechanical ventilation. Cardiac output and glomerular filtration rate were measured noninvasively. Mean arterial pressure, total renal blood flow, cortical perfusion, medullary perfusion, and medullary tissue oxygen tension (mtPO 2 ) were determined for 12 h. Cecal ligation and puncture decreased mean arterial pressure and cardiac output by more than 50%, with a proportional increase in renal vascular resistance and a 60-80% reduction in renal blood flow, cortical perfusion, medullary perfusion, and mtPO 2 compared to sham. Cecal ligation and puncture also decreased glomerular filtration rate by ~79% and increased AKI biomarkers. Isolated foci of tubular necrosis were observed in the septic piglets. Except for mtPO 2 , changes in all these parameters were ameliorated in resuscitated piglets. Resuscitation also attenuated sepsis-induced increases in the levels of plasma C-reactive protein, proinflammatory cytokines, lactate dehydrogenase, alanine transaminase, aspartate aminotransferase, and renal NLRP3 inflammasome. These data suggest that newborn pigs subjected to cecal ligation and puncture develop hypodynamic septic AKI. Early implementation of resuscitation lessens the degree of inflammation, AKI, and liver injury.

Positive pathogens in stool could predict the clinical outcomes of sepsis-associated acute kidney injury in critical ill patient

In this study, we sought to evaluate the influence of positive pathogens in stool (PPS) on clinical outcomes in critical ill patients with Sepsis-associated acute kidney injury (S-AKI) from intensive care unit. Our sample consisted of 7338 patients, of whom 752 (10.25%) had PPS. We found that the presence of Clostridium difficile (C. difficile) and protists in stool samples was correlated with survival during hospitalization, as well as 30-day and 90-day survival. Interestingly, there was no significant difference in overall survival and 30-day in-hospital survival between the PPS group and the negative pathogens in stool (NPS) control group. However, the cumulative incidence of 90-day infection-related mortality was significantly higher in the PPS group (53 vs. 48%, P = 0.022), particularly in patients with C. difficile in their stool specimens. After adjusting for propensity scores, the results also have statistical significance. These findings suggest that PPS may affect the 90-days survival outcomes of S-AKI, particularly in patients with C. difficile and protists in their stool samples. Further research is warranted to further explore these associations.

Reduction in NGAL at 48 h predicts the progression to CKD in patients with septic associated AKI: a single-center clinical study

BACKGROUND

In this study, our objective was to investigate the predictive value of serum and urine fluctuations of neutrophil gelatinase-associated lipid transporters (NGAL) in relation to the progression of chronic kidney disease (CKD) among patients with septic associated AKI (SA-AKI).

METHODS

A total of 425 SA-AKI patients were enrolled in this study and divided into the recovery group (n = 320) and the AKI-to-CKD group (n = 105) based on 3-month follow-up data. The serum and urine NGAL levels on the day of AKI diagnosis (T0) and 48 h after anti-AKI treatment (T1) were recorded and calculated.

RESULTS

The levels of NGAL in serum and urine were found to be higher in the AKI-to-CKD group compared to the recovery group at T1 point (P < 0.05). The reductions of NGAL at 48 h in serum and urine were lower in the AKI-to-CKD group than those observed in the recovery group (P < 0.05). In comparison to T0, a significant decrease was noted for both serum and urine NGAL levels on T1 among patients who recovered from AKI (P < 0.05), whereas no such trend was observed among those with AKI-to-CKD transition (P > 0.05). After adjusting age, sex, and BMI through partial correlation analysis, the reduction of serum NGAL was found to be most strongly associated with the transition from AKI to CKD. ROC analysis showed an AUC of 0.832 for serum NGAL reduction, with a cut-off value of - 111.24 ng/ml and sensitivity and rates of 76.2% and 81.2%, respectively. Logistic regression analysis indicated that a reduction of serum NGAL ≥ - 111.24 ng/ml was the early warning indicator for the progression of CKD in SA-AKI patients.

CONCLUSION

The reduction of serum NGAL following 48 h of anti-AKI therapy represents a distinct hazard factor for the advancement of CKD in patients with SA-AKI, independent of other variables.

Galgravin Isolated from Piper kadsura Ameliorates Lipopolysaccharide (LPS)-Induced Endotoxemia in Mice

Sepsis results from uncontrolled inflammation, characterized by cytokine storm and immunoparalysis. To assess whether galgravin, a natural lignan isolated from Piper kadsura, can be used to treat sepsis, models of bacterial lipopolysaccharide (LPS)-activated macrophages and LPS-induced endotoxemia mice were used. Galgravin suppressed NF-κB activation in LPS-activated RAW 264.7 macrophages without causing significant cytotoxicity, in which proinflammatory molecules like TNF-α, IL-6, iNOS, and COX-2 were downregulated. In addition, the expression of TNF-α and IL-6 was also suppressed by galgravin in LPS-activated murine bone marrow-derived macrophages. Moreover, galgravin significantly downregulated the mRNA expression of TNF-α, IL-6, and iNOS in the lungs and decreased TNF-α and IL-6 in the serum and IL-6 in the bronchoalveolar lavage fluid of LPS-challenged mice. The COX-2 expression in tissues, including the lung, liver, and kidney, as well as the lung alveolar hemorrhage, was also reduced by galgravin. The present study reveals the anti-inflammatory effects of galgravin in mouse models and implies its potential application in inflammation diseases.

β-hydroxybutyrate ameliorates sepsis-induced acute kidney injury

BACKGROUND

Sepsis is a major cause of acute kidney injury (AKI). Recent studies have demonstrated that β-hydroxybutyrate (β-HB) alleviates renal ischemia-reperfusion injury and cisplatin-induced renal injury in murine models. This study aimed to investigate whether β-HB ameliorates sepsis-induced AKI (SIAKI) in a lipopolysaccharide (LPS)-induced mouse sepsis model.

METHODS AND RESULTS

SIAKI was induced by intraperitoneally injecting LPS to C57BL/6 male mice. β-HB was administrated intraperitoneally before LPS injection. The mice were divided into sham, β-HB, LPS, and β-HB + LPS groups. The histological damage score and serum creatinine level were significantly increased in the LPS group mice, but attenuated in the β-HB + LPS group mice. The expression of phosphorylated nuclear factor-κB tumor necrosis factor-α/interleukin-6 and the number of F4/80-positive macrophages in the β-HB + LPS group mice were lower than those in the LPS group mice. The number of TdT-mediated dUTP nick-end labeling (TUNEL)-positive tubular cells, cleaved caspase-3 expression, and Bax/Bcl-2 ratio in the β-HB + LPS group mice were lower than those in the LPS group mice.

CONCLUSION

β-HB pre-treatment ameliorates SIAKI by reducing tubular apoptosis and inflammatory responses. Thus, β-HB pre-treatment could be a potential prophylactic strategy against SIAKI.

Aspirin reduces the mortality risk of sepsis-associated acute kidney injury: an observational study using the MIMIC IV database

Introduction: Sepsis-associated acute kidney injury (SA-AKI) is a complication of sepsis and is characterized by high mortality. Aspirin affects cyclooxygenases which play a significant role in inflammation, hemostasis, and immunological regulation. Sepsis is an uncontrolled inflammatory and procoagulant response to a pathogen, but aspirin can inhibit platelet function to attenuate the inflammatory response, thus improving outcomes. Several studies have generated contradictory evidence regarding the effect of aspirin on patients with sepsis-associated acute kidney injury (SA-AKI). We conducted an analysis of the MIMIC IV database to investigate the correlation between aspirin utilization and the outcomes of patients with SA-AKI, as well as to determine the most effective dosage for aspirin therapy. Materials and methods: SA-AKI patients' clinical data were extracted from MIMIC-IV2.1. Propensity score matching was applied to balance the baseline characteristics between the aspirin group and the non-user group. Subsequently, the relationship between aspirin and patient death was analyzed by Kaplan-Meier method and Cox proportional hazard regression models. Results: 12,091 patients with SA-AKI were extracted from the MIMIC IV database. In the propensity score-matched sample of 7,694 individuals, lower 90-day mortality risks were observed in the aspirin group compared to the non-users group (adjusted HR: 0.722; 95%CI: 0.666, 0.783) by multivariable cox proportional hazards analysis. In addition, the Kaplan-Meier survival curves indicated a superior 90-day survival rate for aspirin users compared to non-users (the log-rank test p-value was 0.001). And the median survival time of patients receiving aspirin treatment was significantly longer than those not receiving (46.47 days vs. 24.26 days). In the aspirin group, the average ICU stay length was shorter than non-users group. (5.19 days vs. 5.58 days, p = 0.006). There was no significant association between aspirin and an increased risk of gastrointestinal hemorrhage (p = 0.144). Conclusion: Aspirin might reduce the average ICU stay duration and the 30-day or 90-day mortality risks of SA-AKI patients. No statistically significant difference in the risk of gastrointestinal hemorrhage was found between the aspirin group and the control group.

PDHA1 hyperacetylation-mediated lactate overproduction promotes sepsis-induced acute kidney injury via Fis1 lactylation

The increase of lactate is an independent risk factor for patients with sepsis-induced acute kidney injury (SAKI). However, whether elevated lactate directly promotes SAKI and its mechanism remain unclear. Here we revealed that downregulation of the deacetylase Sirtuin 3 (SIRT3) mediated the hyperacetylation and inactivation of pyruvate dehydrogenase E1 component subunit alpha (PDHA1), resulting in lactate overproduction in renal tubular epithelial cells. We then found that the incidence of SAKI and renal replacement therapy (RRT) in septic patients with blood lactate ≥ 4 mmol/L was increased significantly, compared with those in septic patients with blood lactate < 2 mmol/L. Further in vitro and in vivo experiments showed that additional lactate administration could directly promote SAKI. Mechanistically, lactate mediated the lactylation of mitochondrial fission 1 protein (Fis1) lysine 20 (Fis1 K20la). The increase in Fis1 K20la promoted excessive mitochondrial fission and subsequently induced ATP depletion, mitochondrial reactive oxygen species (mtROS) overproduction, and mitochondrial apoptosis. In contrast, PDHA1 activation with sodium dichloroacetate (DCA) or SIRT3 overexpression decreased lactate levels and Fis1 K20la, thereby alleviating SAKI. In conclusion, our results show that PDHA1 hyperacetylation and inactivation enhance lactate overproduction, which mediates Fis1 lactylation and exacerbates SAKI. Reducing lactate levels and Fis1 lactylation attenuate SAKI.

Epigenetic dysregulation of autophagy in sepsis-induced acute kidney injury: the underlying mechanisms for renoprotection

Sepsis-induced acute kidney injury (SI-AKI), a common critically ill, represents one of the leading causes of global death. Emerging evidence reveals autophagy as a pivotal modulator of SI-AKI. Autophagy affects the cellular processes of renal lesions, including cell death, inflammation, and immune responses. Herein, we conducted a systematic and comprehensive review on the topic of the proposed roles of autophagy in SI-AKI. Forty-one relevant studies were finally included and further summarized and analyzed. This review revealed that a majority of included studies (24/41, 58.5%) showed an elevation of the autophagy level during SI-AKI, while 22% and 19.5% of the included studies reported an inhibition and an elevation at the early stage but a declination of renal autophagy in SI-AKI, respectively. Multiple intracellular signaling molecules and pathways targeting autophagy (e.g. mTOR, non-coding RNA, Sirtuins family, mitophagy, AMPK, ROS, NF-Kb, and Parkin) involved in the process of SI-AKI, exerting multiple biological effects on the kidney. Multiple treatment modalities (e.g. small molecule inhibitors, temsirolimus, rapamycin, polydatin, ascorbate, recombinant human erythropoietin, stem cells, Procyanidin B2, and dexmedetomidine) have been found to improve renal function, which may be attributed to the elevation of the autophagy level in SI-AKI. Though the exact roles of autophagy in SI-AKI have not been well elucidated, it may be implicated in preventing SI-AKI through various molecular pathways. Targeting the autophagy-associated proteins and pathways may hint towards a new prospective in the treatment of critically ill patients with SI-AKI, but more preclinical studies are still warranted to validate this hypothesis.

Antioxidant, Antiapoptotic, and Anti-Inflammatory Effects of Hesperetin in a Mouse Model of Lipopolysaccharide-Induced Acute Kidney Injury

Sepsis is a severe inflammatory condition that can cause organ dysfunction, including acute kidney injury (AKI). Hesperetin is a flavonoid aglycone that has potent antioxidant and anti-inflammatory properties. However, the effect of hesperetin on septic AKI has not yet been fully investigated. This study examined whether hesperetin has a renoprotective effect on lipopolysaccharide (LPS)-induced septic AKI. Hesperetin treatment ameliorated histological abnormalities and renal dysfunction in LPS-injected mice. Mechanistically, hesperetin attenuated LPS-induced oxidative stress, as evidenced by the suppression of lipid and DNA oxidation. This beneficial effect of hesperetin was accompanied by downregulation of the pro-oxidant NADPH oxidase 4, restoration of glutathione levels, and activation of antioxidant enzymes. This flavonoid compound also inhibited apoptotic cell death via suppression of p53-dependent caspase-3 pathway. Furthermore, hesperetin alleviated Toll-like receptor 4-mediated cytokine production and macrophage infiltration. Our findings suggest that hesperetin ameliorates LPS-induced renal structural and functional injury through suppressing oxidative stress, apoptosis, and inflammation.