Sepsis-Associated Acute Kidney Injury

Sepsis-mediated renal dysfunction: Pathophysiology, biomarkers and role of phytoconstituents in its management

Sepsis has evolved as an enormous health issue amongst critically ill patients. It is a major risk factor that results in multiple organ failure and shock. Acute kidney injury (AKI) is one of the most frequent complications underlying sepsis, which portends a heavy burden of mortality and morbidity. Thus, the present review is aimed to provide an insight into the recent progression in the molecular mechanisms targeting dysregulated immune response and cellular dysfunction involved in the development of sepsis-associated AKI, accentuating the phytoconstituents as eligible candidates for attenuating the onset and progression of sepsis-associated AKI. The pathogenesis of sepsis-mediated AKI entails a complicated mechanism and is likely to involve a distinct constellation of hemodynamic, inflammatory, and immune mechanisms. Novel biomarkers like neutrophil gelatinase-associated lipocalin, soluble triggering receptor expressed on myeloid cells 1, procalcitonin, alpha-1-microglobulin, and presepsin can help in a more sensitive diagnosis of sepsis-associated AKI. Many bioactive compounds like curcumin, resveratrol, baicalin, quercetin, and polydatin are reported to play an important role in the prevention and management of sepsis-associated AKI by decreasing serum creatinine, blood urea nitrogen, cystatin C, lipid peroxidation, oxidative stress, IL-1β, TNF-α, NF-κB, and increasing the activity of antioxidant enzymes and level of PPARγ. The plant bioactive compounds could be developed into a drug-developing candidate in managing sepsis-mediated acute kidney injury after detailed follow-up studies. Lastly, the gut-kidney axis may be a more promising therapeutic target against the onset of septic AKI, but a deeper understanding of the molecular pathways is still required.

Liensinine pretreatment reduces inflammation, oxidative stress, apoptosis, and autophagy to alleviate sepsis acute kidney injury

Liensinine is mainly derived from alkaloids extracted and isolated from lotus seeds (Nelumbo nucifera Gaertn). It possesses anti-inflammatory, and antioxidant, according to contemporary pharmacological investigations. However, the effects and therapeutic mechanisms of liensinine on acute kidney injury (AKI) models of sepsis are unclear. To gain insight into these mechanisms, we established a sepsis kidney injury model by LPS injection of mice treated with liensinine, and stimulation of HK-2 with LPS in vitro and treated with liensinine and inhibitors of p38 MAPK, JNK MAPK. We first found that liensinine significantly reduced kidney injury in sepsis mice, while suppressing excessive inflammatory responses, restoring renal oxidative stress-related biomarkers, reducing increased apoptosis in TUNEL-positive cells and excessive autophagy, and that this process was accompanied by an increase in JNK/ p38-ATF 2 axis. In vitro experiments further demonstrated that lensinine reduced the expression of KIM-1, NGAL, inhibited pro- and anti-inflammatory secretion disorders, regulated the activation of the JNK/p38-ATF 2 axis, and reduced the accumulation of ROS, as well as the reduction of apoptotic cells detected by flow cytometry, and that this process played the same role as that of p38 MAPK, JNK MAPK inhibitors. We speculate that liensinine and p38 MAPK, JNK MAPK inhibitors may act on the same targets and could be involved in the mechanism of alleviating sepsis kidney injury in part through modulation of the JNK/p38-ATF 2 axis. Our study demonstrates that lensinine is a potential drug and thus provides a potential avenue for the treatment of AKI.

The early diagnosis and pathogenic mechanisms of sepsis-related acute kidney injury

Sepsis is a syndrome caused by an imbalance in the inflammatory response of the body caused by an infection that leads to organ dysfunction, with the kidney being one of the most commonly affected organs. Sepsis-related acute kidney injury (SAKI) is strongly linked to increased mortality and poor clinical outcomes. Early diagnosis and treatment can significantly reduce patient mortality. On the other hand, the pathogenesis of SAKI is not fully understood, and early diagnosis of SAKI is a clinical challenge. Therefore, the current review describes biomarkers of acute kidney injury in sepsis and discusses the various pathogenic mechanisms involved in the progression of acute kidney injury in sepsis to develop new clinical treatment avenues.

The clinical application of ultrasound for acute kidney injury during sepsis-from macroscopic to microscopic renal perfusion perspectives

OBJECTIVE

The aim was to quantify macroscopic renal blood flow and renal cortical microcirculation in patients with septic acute kidney injury (AKI) using ultrasound and contrast-enhanced ultrasound.

METHODS

In this case-control study, patients in the intensive care unit diagnosed with septic AKI were divided into stages 1-3 based on the 2012 KDIGO (Kidney Disease: Improving Global Outcomes) AKI diagnostic criteria. The patients were categorized into mild (stage 1) and severe (stages 2 and 3) groups, while septic patients without AKI served as the control group. Ultrasound parameters such as macrovascular renal blood flow and time-averaged velocity, as well as cardiac function parameters such as cardiac output and cardiac index, were measured. The time-intensity curve in the microcirculation was analyzed through contrast-enhanced ultrasound imaging software to calculate imaging parameters such as peak time, rise time, fall half-time and mean transit time of the interlobar arteries in the renal cortex.

RESULTS

In terms of macrocirculation, renal blood flow and time-averaged velocity decreased gradually with the progression of septic acute renal injury (p = 0.004, p < 0.001). There was no difference in cardiac output and cardiac index values among the three groups (p = 0.17 and p = 0.12). In terms of microcirculation, ultrasonic Doppler parameters of the renal cortical interlobular artery, such as peak intensity, risk index and ratio of peak systolic velocity to end-diastolic velocity, gradually increased (all p values <0.05). The temporal contrast-enhanced ultrasound parameters-time to peak, rise time, fall half-time and mean transit time-were prolonged in AKI groups when compared with the control group (p < 0.001, p = 0.003, p = 0.004 and p = 0.009, respectively).

CONCLUSION

In patients with septic AKI, the renal blood flow and time average velocity of macrocirculation in the kidneys are reduced, while the time parameters of microcirculation such as time to peak, rise time, fall half-time and mean transit time are prolonged, especially in patients with severe AKI. These changes are not related to changes in cardiac output or cardiac index.

Explainable ensemble machine learning model for prediction of 28-day mortality risk in patients with sepsis-associated acute kidney injury

Background

Sepsis-associated acute kidney injury (S-AKI) is a major contributor to mortality in intensive care units (ICU). Early prediction of mortality risk is crucial to enhance prognosis and optimize clinical decisions. This study aims to develop a 28-day mortality risk prediction model for S-AKI utilizing an explainable ensemble machine learning (ML) algorithm.

Methods

This study utilized data from the Medical Information Mart for Intensive Care IV (MIMIC-IV 2.0) database to gather information on patients with S-AKI. Univariate regression, correlation analysis and Boruta were combined for feature selection. To construct the four ML models, hyperparameters were tuned via random search and five-fold cross-validation. To evaluate the performance of all models, ROC, K-S, and LIFT curves were used. The discrimination of ML models and traditional scoring systems was compared using area under the receiver operating characteristic curve (AUC). Additionally, the SHapley Additive exPlanation (SHAP) was utilized to interpret the ML model and identify essential variables. To investigate the relationship between the top nine continuous variables and the risk of 28-day mortality. COX regression-restricted cubic splines were utilized while controlling for age and comorbidities.

Results

The study analyzed data from 9,158 patients with S-AKI, dividing them into a 28-day mortality group of 1,940 and a survival group of 7,578. The results showed that XGBoost was the best performing model of the four ML models with AUC of 0.873. All models outperformed APS-III 0.713 and SAPS-II 0.681. The K-S and LIFT curves indicated XGBoost as the most effective predictor for 28-day mortality risk. The model's performance was evaluated using ROCpr curves, calibration curves, accuracy, precision, and F1 scores. SHAP force plots were utilized to interpret and visualize the personalized predictive power of the 28-day mortality risk model. Additionally, COX regression restricted cubic splines revealed an interesting non-linear relationship between the top nine variables and 28-day mortality.

Conclusion

The use of ensemble ML models has shown to be more effective than the LR model and conventional scoring systems in predicting 28-day mortality risk in S-AKI patients. By visualizing the XGBoost model with the best predictive performance, clinicians are able to identify high-risk patients early on and improve prognosis.

[Association of neutrophil, lymphocyte, platelet ratio with acute kidney injury in sepsis]

Background

Acute kidney injury (AKI) is frequent in sepsis (25 to 51%), with high mortality (40 to 80%) and long-term complications. Despite its importance we do not have accessible markers in intensive care. In other entities (post-surgical and COVID-19) the neutrophil/lymphocyte and platelet (N/LP) ratio has been associated with acute kidney injury; however, this relationship has not been studied in a pathology with a severe inflammatory response such as sepsis.

Objective

To demonstrate the association between N/LP with AKI secondary to sepsis in intensive care.

Material and methods

Ambispective cohort study in patients over 18 years who were admitted to intensive care with a diagnosis of sepsis. The N/LP ratio was calculated from admission up to the seventh day and up to the diagnosis of AKI and outcome. Statistical analysis was performed with chi squared test, Cramer's V and multivariate logistic regression.

Results

Out of the 239 patients studied, the incidence of AKI developed in 70%. 80.9% of patients with N/LP ratio > 3 had AKI (p < 0.0001, Cramer's V 0.458, OR 3.05, 95% CI 1.602-5.8) and increased renal replacement therapy (21.1 vs. 11.1%, p = 0.043).

Conclusion

N/LP ratio > 3 has a moderate association with AKI secondary to sepsis in the intensive care unit.

Immune dysregulation and RNA N6-methyladenosine modification in sepsis

Sepsis is defined as life-threatening organ dysfunction caused by the host immune dysregulation to infection. It is a highly heterogeneous syndrome with complex pathophysiological mechanisms. The host immune response to sepsis can be divided into hyper-inflammatory and immune-suppressive phases which could exist simultaneously. In the initial stage, systemic immune response is activated after exposure to pathogens. Both innate and adaptive immune cells undergo epigenomic, transcriptomic, and functional reprogramming, resulting in systemic and persistent inflammatory responses. Following the hyper-inflammatory phase, the body is in a state of continuous immunosuppression, which is related to immune cell apoptosis, metabolic failure, and epigenetic reprogramming. Immunosuppression leads to increased susceptibility to secondary infections in patients with sepsis. RNA N6-Methyladenosine (m6A) has been recognized as an indispensable epitranscriptomic modification involved in both physiological and pathological processes. Recent studies suggest that m6A could reprogram both innate and adaptive immune cells through posttranscriptional regulation of RNA metabolism. Dysregulated m6A modifications contribute to the pathogenesis of immune-related diseases. In this review, we summarize immune cell changes and the potential role of m6A modification in sepsis. This article is categorized under: RNA in Disease and Development > RNA in Disease RNA Processing > RNA Editing and Modification.

CIRC_0008882 STIMULATES PDE7A TO SUPPRESS SEPTIC ACUTE KIDNEY INJURY PROGRESSION BY SPONGING MIR-155-5P

ABSTRACT

Background: The importance of circular RNA (circRNA) in the progression of septic acute kidney injury (AKI) was gradually recognized. It has been confirmed that circ_0008882 expression was decreased in the blood of patients with AKI. However, the role of circ_0008882 in septic AKI progression remains unclear. Methods: Human kidney-2 (HK2) cells were stimulated with lipopolysaccharide (LPS) to establish a septic AKI cell model. The RNA and protein expression of circ_0008882, miR-155-5p, phosphodiesterase 7A (PDE7A), PCNA, Bax, and Bcl-2 were detected by quantitative real-time polymerase chain reaction and Western blot. Cell viability was investigated by cell counting kit-8 assay. Enzyme-linked immunosorbent assay (ELISA) was adopted to measure the levels of inflammatory factors (TNF-α, IL-1β, and IL-6). Flow cytometry was implemented to evaluate cell cycle and cell apoptosis. The Caspase3 activity was examined using Caspase3 Assay Kit. Dual-luciferase reporter assay and RNA immunoprecipitation assay were applied to verify the molecular target relations. Results: Septic AKI serum samples and LPS-induced HK2 cells displayed low expression of circ_0008882 and PDE7A, and high expression of miR-155-5p when compared with the controls. Overexpression of circ_0008882 relieved LPS-induced HK2 cell injury. MiR-155-5p was a target of circ_0008882, and miR-155-5p mimic restored circ_0008882 overexpression-mediated effects on LPS-treated HK2 cells. PDE7A was identified as a target gene of miR-155-5p, and PDE7A downregulation almost reverted the improvement impacts induced by the miR-155-5p inhibitor. Conclusions: Overexpression of circ_0008882 impeded LPS-induced HK2 cell injury by modulating miR-155-5p/PDE7A pathway, implying that circ_0008882 might be a possible circRNA-targeted therapy for septic AKI.

Insight Into Kidney Protection by Vacuum-Assisted Venous Drainage in Adult Cardiac Operation - A Multicenter Study

BACKGROUND

The relationship between venous congestion and acute kidney injury (AKI) in cardiac surgery after cardiopulmonary bypass has not thoroughly investigated. Vacuum-assisted venous drainage (VAVD) reduces venous congestion, so we hypothesized that it would reduce the incidence of AKI in cardiovascular surgery.

METHODS AND RESULTS

We used a retrospective propensity score-matched analysis to evaluate the effect of VAVD on AKI in adult patients undergoing cardiac surgery. The primary outcomes were AKI and renal replacement therapy (RRT). Multivariable logistic regression was used to explore the association between VAVD exposure and adverse kidney outcomes. Of 15,387 eligible subjects, 13,480 and 1,907 had gravity drainage (GD) or VAVD, respectively, during cardiopulmonary bypass. On the basis of propensity scores, there were 1,468 matched patient pairs for GD and VAVD. The average central venous pressure (CVP) in the GD group was higher than in the VAVD group (4.43±1.23 mmHg vs. 2.30±0.98 mmHg, P<0.001). The occurrence of AKI and RRT was statistically significantly different in the 2 groups [(600/1,468, 40.87%) vs. (445/1,468, 30.31%), P<0.001; (36/1,468, 2.45% vs. 8/1,468; 0.54%), P<0.001, respectively)]. Multivariate logistic regression analysis revealed that VAVD was effective in protecting kidney function.

CONCLUSIONS

VAVD was associated with a lower CVP and lower incidence of AKI, suggesting it protects adult cardiac patients from adverse renal outcomes.

Silica Cross-Linked Micelle-Based Theranostic System for the Imaging and Treatment of Acute and Chronic Kidney Injury

Acute kidney injury (AKI) is a common and serious disease with high mortality and morbidity, and the persistent inflammatory environment brought about by AKI promotes its deterioration into chronic kidney disease (CKD). An efficient and timely targeted drug delivery to the renal tubules is crucial for AKI treatment. Here, we prepared silica cross-linked micelles (SCLMs) with different sizes and studied their targeting ability to the injured kidney. It is found that the SCLMs with a size of 13 nm could rapidly accumulate and remain in the damaged kidney. Immunofluorescence results confirmed that SCLMs are selectively located in the damaged tubular cells but cannot be found in healthy renal tissue. Therefore, fluorescent dye-labeled SCLMs were used for the imaging of the injured kidney, which could reflect the status of the kidney injury. Furthermore, atorvastatin, an antioxidative and anti-inflammatory drug, was loaded in SCLMs as the therapeutic agents for the treatment of ischemia/reperfusion-induced AKI and CKD. Renal function indexes, such as tubular necrosis, collagen deposition, and inflammation, were effectively improved after the treatment.

Investigating the effect of dehydromiltirone on septic AKI using a network pharmacology method, molecular docking, and experimental validation

Acute kidney injury (AKI) is a severe and frequent complication of sepsis that occurs in intensive care units with inflammation and rapid decline in renal function as the main pathological features. Systemic inflammation, microvascular dysfunction, and tubule injury are the main causes of sepsis-induced AKI (SI-AKI). The high prevalence and death rate from SI-AKI is a great challenge for clinical treatment worldwide. However, in addition to hemodialysis, there is no effective drug to improve renal tissue damage and alleviate the decline in kidney function. We conducted a network pharmacological analysis of Salvia miltiorrhiza (SM), a traditional Chinese medicine, which is widely used for the treatment of kidney disease. Then, we combined molecular docking and a dynamics simulation to screen for the active monomer dehydromiltirone (DHT) that has therapeutic effects on SI-AKI and investigated its potential mechanism of action through experimental validation. The components and targets of SM were obtained by searching the database, and 32 overlapping genes were screened by intersection analysis with AKI targets. GO and KEGG data showed that the functions of a common gene were closely related to oxidative stress, mitochondrial function, and apoptosis. The molecular docking results combined with molecular dynamics simulations provide evidence for a binding model between DHT and cyclooxygenase-2 (COX2), both of which are mainly driven by van der Waals interactions and a hydrophobic effect. In vivo, we found that mice pretreated with an intraperitoneal injection of DHT (20 mg/kg/d) for 3 days ameliorated CLP surgery-induced renal function loss and renal tissue damage and inhibited inflammatory mediators IL-6, IL-1β, TNF-α, and MCP-1 production. In vitro, the DHT pretreatment decreased LPS-induced expression of COX2, inhibited cell death and oxidative stress, alleviated mitochondrial dysfunction, and restrained apoptosis in HK-2 cells. Our research indicates that the renal preventive effect of DHT is related to maintaining mitochondrial dynamic balance, restoring mitochondrial oxidative phosphorylation, and inhibiting cell apoptosis. The findings in this study provide a theoretical basis and a novel method for the clinical therapy of SI-AKI.

Kaempferol Reverses Acute Kidney Injury in Septic Model by Inhibiting NF-κB/AKT Signaling Pathway

Sepsis is the main cause of acute kidney injury (AKI), mainly due to systemic immune dysregulation. Kaempferol (KAE) is a natural flavonoid compound with multiple biological activities including anti-inflammatory, antioxidant, and antiapoptotic properties. In this study, we constructed a sepsis-induced AKI mouse model and an LPS-induced glomerular mesangial cell (HK-2) in vitro sepsis AKI model. We found that KAE ameliorated sepsis-induced renal pathological damage, reversed renal function damage, and inhibited p-p65 and p-AKT protein expression. In addition, KAE reversed LPS-induced proliferation and inhibited apoptosis in HK-2 cells. These studies suggest that KAE reverses sepsis by inhibiting activation of the NF-κB/AKT pathway to reverse acute kidney injury.

ADENOSINE MONOPHOSPHATE-ACTIVATED PROTEIN KINASE PHOSPHORYLATION MEDIATED BY SIRTUIN 5 ALLEVIATES SEPTIC ACUTE KIDNEY INJURY

ABSTRACT

Background : Our previous studies have shown that ameliorating mitochondrial damage in renal tubular epithelial cells (RTECs) can alleviate septic acute kidney injury (SAKI). It is reported that AMPK phosphorylation (p-AMPK) could ameliorate mitochondrial damage in renal tissue and Sirtuin 5 (SIRT5) overexpression significantly enhanced the level of p-AMPK in bovine preadipocytes. However, the role of SIRT5-mediated phosphorylation of AMPK in SAKI needs to be clarified. Methods : WT/SIRT5 gene knockout mouse model of cecal ligation and puncture-induced SAKI and a human kidney 2 cell model of LPS-induced SAKI were constructed. An AMPK chemical activator and SIRT5 overexpression plasmid were used. Indexes of mitochondrial structure and function, level of p-AMPK, and expression of SIRT5 protein in renal tissue and RTECs were measured. Results : After sepsis stimulation, the p-AMPK level was decreased, mitochondrial structure was disrupted, and ATP content was decreased. Notably, an AMPK activator alleviated SAKI. Sirtuin 5 gene knockout significantly aggravated SAKI, while SIRT5 overexpression alleviated mitochondrial dysfunction after LPS stimulation, as manifested by the increase of p-AMPK level, the alleviation of mitochondrial structure damage, the restoration of ATP content, the decrease of proapoptotic protein expression, as well as the reduction of reactive oxygen species generation. Conclusions : Upregulation of SIRT5 expression can attenuate mitochondrial dysfunction in RTECs and alleviate SAKI by enhancing the phosphorylation of AMPK.

S-Nitrosoglutathione protects acute kidney injury in septic rats by inhibiting the activation of NLRP3 inflammasome

Objectives

We aimed to study the effect of S-nitroso glutathione (SNG) on acute kidney injury (AKI) in septic rats by regulating nucleotide oligomerization domain-like receptor protein 3 (NLRP3).

Materials and Methods

Sprague Dawley rats were used to construct the AKI model, and biochemical methods were used to detect the levels of inflammatory factors and anti-oxidant enzymes in renal tissue. We observed the ultrastructural changes of renal tissue by transmission electron microscopy and detected the protein and mRNA levels of NLRP3, apoptosis-associated speck-like protein containing a caspase recruitment domain foci (ASC) and caspase-1 by western-blotting and RT-qPCR.

Results

Cecal ligation and puncture induced renal tubular epithelial tissue damage in septic rats, resulting in decreased renal function, increased levels of inflammation and decreased levels of anti-oxidant enzymes in renal tissue, and aggravated mitochondrial damage, significantly decreased mitochondrial density and enzyme complex I/II/III/IV levels (all P<0.001), and increased the protein and mRNA expression of NLRP3, ASC, and caspase-1 (all P<0.001). However, after pretreatment with SNG, the pathological damage of renal tubular epithelial tissue was reduced, the renal function was improved, the level of inflammation in renal tissue decreased and the level of anti-oxidant enzymes increased, the density of mitochondria and the level of enzyme complex I/II/III/IV were significantly increased (all P<0.001), meanwhile the protein and mRNA levels of NLRP3, ASC, and caspase-1 were all decreased significantly (all P<0.05).

Conclusion

SNG protects AKI in septic rats by inhibiting NLRP3 inflammasome activation.

Efficacy of Continuous Renal Replacement Therapy and Intermittent Hemodialysis in Patients with Renal Failure in Intensive Care Unit: A Systemic Review and Meta-analysis

Objective

This study aimed to compare the clinical efficacy of continuous renal replacement therapy (CRRT) and intermittent hemodialysis (IHD) in patients with renal failure in intensive care unit (ICU).

Methods

Relevant studies were searched in the databases including EMBASE, Cochrane Library, and MEDLINE (PubMed) from inception to January 04, 2021. The inclusion of available studies and the collection of data were independently conducted by two authors after reviewing the full text. Pooled analyses of relative risk (RR) and weighted mean difference (WMD) were performed to compare the outcomes of renal recovery, short-term mortality, length of ICU stays, and length of in-hospital stays between the two different treatment groups. Publication bias was assessed by the funnel plot.

Results

A total of 11 RCT studies including 1740 patients with renal failure were eligible for final analysis. Among them, 894 patients (51.4%) underwent CRRT and 846 patients (48.6%) received IHD. Pooled analysis did not find significant differences in renal recovery and short-term mortality between the two groups. Interestingly, patients underwent CRRT showed significantly shorter length of ICU stay and in-hospital stay than those who underwent IHD (ICU stay: RR: -0.61, 95%CI: -1.10--0.11, P < 0.05; I² = 93.6%; in-hospital stay: RR: -0.56, 95%CI: -1.41-0.28, P < 0.05; I² = 97.7%). No significant publication biases were observed on the funnel plots.

Conclusion

Compared with IHD, CRRT had similar effects on renal recovery and short-term mortality in patients with renal failure in ICU. As a promising technique in clinical practice, CRRT could significantly reduce the length of ICU stay and in-hospital stay of patients, which was of great significance for the reduction of medical costs and the long-term benefits of patients, thereby reducing the burden on society and individuals.

[Tanshinone IIA alleviates lipopolysaccharide-induced renal tubular epithelial cell apoptosis by inhibiting RIP3/FUNDC1 signaling pathway]

OBJECTIVE

To investigate the effect of tanshinone IIA pretreatment on acute renal injury in lipopolysaccharide (LPS)-induced septic mice and explore the possible mechanism.

METHODS

Thirty C57BL/6 mice were randomized for treatment with saline (control), 10 mg/kg LPS for 24 h, or 10 mg/kg tanshinone IIA 15 min before LPS treatment. After the treatments, serum creatinine and blood urea nitrogen levels of the mice were detected, renal pathologies were observed with PAS staining, and renal expressions of RIP3, cleaved caspase-3 and p¹⁸-FUNDC1 were detected with Western blotting. In the cell experiment, cultured normal human renal tubular epithelial cells (HK-2) were treated with LPS (10 mg/mL), LPS+ siNC, LPS+ siRIP3, or LPS+tanshinone IIA (10 mg/L), and the changes in cell apoptosis were examined with TUNEL staining; Western blotting was performed to detect the expression levels of RIP3, cleaved caspase-3 and p¹⁸-FUNDC1, and qRT-PCR was used to detect the expression of RIP3 mRNA.

RESULTS

LPS challenge for 24 h significantly increased serum creatinine and blood urea nitrogen levels in the mice, caused obviously damages in the proximal renal tubules, and increased renal expressions of RIP3, cleaved caspase-3 and p¹⁸-FUNDC1 proteins. Tanshinone IIA pretreatment significantly improved LPS-induced renal injury in the mice, alleviated apoptosis of the renal cells, and inhibited the expressions of RIP3, cleaved caspase-3 and p¹⁸-FUNDC1 proteins. In HK-2 cells, LPS stimulation significantly increased the protein expressions of RIP3, cleaved caspase-3 and p¹⁸-FUNDC1 and induced obvious cell apoptosis. Pretreatment with tanshinone IIA strongly inhibited the expression of RIP3 and p¹⁸-FUNDC1 and reduced LPS-induced apoptosis of HK-2 cells.

CONCLUSION

Tanshinone IIA can reduce LPS-induced apoptosis of renal tubular epithelial cells by inhibiting RIP3/FUNDC1 signal pathway.

Update on Pediatric Acute Kidney Injury

Acute kidney injury (AKI) is common in children and is associated with significant morbidity and mortality. In the last decade our understanding of AKI has improved significantly, and it is now considered a systemic disorder that affects other organs including heart, lung, and brain. In spite of its limitations, serum creatinine remains the mainstay in the diagnosis of AKI. However, newer approaches such as urinary biomarkers, furosemide stress test, and clinical decision support are being increasingly used and have the potential to improve the accuracy and timeliness of AKI diagnosis.

Results of the 2018 Japan Society for Blood Purification in Critical Care survey: current status and outcomes

Background

The Japan Society for Blood Purification in Critical Care (JSBPCC) has reported survey results on blood purification therapy (BPT) for critically ill patients in 2005, 2009, and 2013. To clarify the current clinical status, including details of the modes used, treated diseases, and survival rate, we conducted this cohort study using data from the nationwide JSBPCC registry in 2018.

Methods

We analyzed data of 2371 patients who underwent BPT in the intensive care units of 43 facilities to investigate patient characteristics, disease severity, modes of BPTs, including the dose of continuous renal replacement therapy (CRRT) and hemofilters, treated diseases, and the survival rate for each disease. Disease severity was assessed using Acute Physiology and Chronic Health Evaluation (APACHE) II and Sequential Organ Failure Assessment (SOFA) scores.

Results

BPT was performed 2867 times in the 2371 patients. Mean APACHE II and SOFA scores were 23.5 ± 9.4 and 10.0 ± 4.4, respectively. The most frequently used mode of BPT was CRRT (67.4%), followed by intermittent renal replacement therapy (19.1%) and direct hemoperfusion with the polymyxin B-immobilized fiber column (7.3%). The most commonly used anticoagulant was nafamostat mesilate (78.6%). Among all patients, the 28-day survival rate was 61.7%. CRRT was the most commonly used mode for many diseases, including acute kidney injury (AKI), multiple organ failure (MOF), and sepsis. The survival rate decreased according to the severity of AKI (P = 0.001). The survival rate was significantly lower in patients with multiple organ failure (MOF) (34.6%) compared with acute lung injury (ALI) (48.0%) and sepsis (58.0%). Multivariate logistic regression analysis revealed that sepsis, ALI, acute liver failure, cardiovascular hypotension, central nervous system disorders, and higher APACHE II scores were significant predictors of higher 28-day mortality.

Conclusion

This large-scale cohort study revealed the current status of BPT in Japan. It was found that CRRT was the most frequently used mode for critically ill patients in Japan and that 28-day survival was lower in those with MOF or sepsis. Further investigations are required to clarify the efficacy of BPT for critically ill patients.

Trial Registration: UMIN000027678.

Renoprotective Effects of Luteolin: Therapeutic Potential for COVID-19-Associated Acute Kidney Injuries

Acute kidney injury (AKI) has been increasingly reported in critically-ill COVID-19 patients. Moreover, there was significant positive correlation between COVID-19 deaths and renal disorders in hospitalized COVID-19 patients with underlying comorbidities who required renal replacement therapy. It has suggested that death in COVID-19 patients with AKI is 3-fold higher than in COVID-19 patients without AKI. The pathophysiology of COVID-19-associated AKI could be attributed to unspecific mechanisms, as well as COVID-19-specific mechanisms such as direct cellular injury, an imbalanced renin-angiotensin-aldosterone system, pro-inflammatory cytokines elicited by the viral infection and thrombotic events. To date, there is no specific treatment for COVID-19 and its associated AKI. Luteolin is a natural compound with multiple pharmacological activities, including anticoronavirus, as well as renoprotective activities against kidney injury induced by sepsis, renal ischemia and diverse nephrotoxic agents. Therefore, in this review, we mechanistically discuss the anti-SARS-CoV-2 and renoprotective activities of luteolin, which highlight its therapeutic potential in COVID-19-AKI patients.

Biomarkers for the Prediction and Judgement of Sepsis and Sepsis Complications: A Step towards precision medicine?

Sepsis and septic shock are a major public health concern and are still associated with high rates of morbidity and mortality. Whilst there is growing understanding of different phenotypes and endotypes of sepsis, all too often treatment strategies still only employ a “one-size-fits-all” approach. Biomarkers offer a unique opportunity to close this gap to more precise treatment approaches by providing insight into clinically hidden, yet complex, pathophysiology, or by individualizing treatment pathways. Predicting and evaluating systemic inflammation, sepsis or septic shock are essential to improve outcomes for these patients. Besides opportunities to improve patient care, employing biomarkers offers a unique opportunity to improve clinical research in patients with sepsis. The high rate of negative clinical trials in this field may partly be explained by a high degree of heterogeneity in patient cohorts and a lack of understanding of specific endotypes or phenotypes. Moving forward, biomarkers can support the selection of more homogeneous cohorts, thereby potentially improving study conditions of clinical trials. This may finally pave the way to a precision medicine approach to sepsis, septic shock and complication of sepsis in the future.

Hederagenin ameliorates cisplatin-induced acute kidney injury via inhibiting long non-coding RNA A330074k22Rik/Axin2/β-catenin signalling pathway

BACKGROUND

Acute kidney injury (AKI), a kidney disease with high morbidity and mortality, is characterized by a dramatic decline in renal function. Hederagenin (HDG), a pentacyclic triterpenoid saponin isolated from astragalus membranaceus, has been shown to have significant anti-inflammatory effects on various diseases. However, the effects of HDG on renal injury and inflammation in AKI has not been elucidated.

METHODS

In this research, mice model of AKI was established by intraperitoneal injection of cisplatin in vivo, the inflammatory model of renal tubular epithelial cells was established by LPS stimulation in vitro, and HDG was used to intervene in vitro and in vivo models. Transcriptome sequencing was used to analyze the alterations of LncRNA and mRNA expression in AKI model and LncRNA-A330074k22Rik (A33) knockdown cells, respectively. Renal in situ electrotransfer knockdown plasmid was used to establish mice model of AKI with low expression of A33 in kidney.

RESULTS

The results showed that HDG effectively alleviate cisplatin-induced kidney injury and inflammation in mice. Transcriptome sequencing results showed that multiple LncRNAs in kidney of AKI model exhibited significant changes, among which LncRNA-A33 had the most obvious change trend. Subsequent results showed that A33 was highly expressed in kidney of AKI mice and LPS-induced renal tubular cells. After in situ renal electroporation knockdown plasmid down-regulated A33 in kidney of AKI mice, it was found that inhibition of A33 could significantly relieve cisplatin-induced kidney injury and inflammation of AKI, while HDG could effectively suppress the expression of A33 in vitro and in vivo, respectively. Subsequently, transcriptome sequencing was again used to analyze the changes in mRNA expression of renal tubular cells after A33 knockdown by siRNA. The results showed that a large number of inflammation-related signaling pathways were down-regulated, Axin2 and its downstream β-catenin signal were significantly inhibited. Cell recovery test showed that HDG inhibited Axin2/β-catenin signal by down-regulating A33, and improved kidney injury and inflammation of AKI.

CONCLUSION

Taken together, HDG significantly ameliorated cisplatin-induced kidney injury through LncRNA-A330074k22Rik/Axin2/β-catenin signal axis, which providing a potential therapeutic approach for the treatment of AKI.

Sepsis-induced AKI: From pathogenesis to therapeutic approaches

Sepsis is a heterogenous and highly complex clinical syndrome, which is caused by infectious or noninfectious factors. Acute kidney injury (AKI) is one of the most common and severe complication of sepsis, and it is associated with high mortality and poor outcomes. Recent evidence has identified that autophagy participates in the pathophysiology of sepsis-associated AKI. Despite the use of antibiotics, the mortality rate is still at an extremely high level in patients with sepsis. Besides traditional treatments, many natural products, including phytochemicals and their derivatives, are proved to exert protective effects through multiple mechanisms, such as regulation of autophagy, inhibition of inflammation, fibrosis, and apoptosis, etc. Accumulating evidence has also shown that many pharmacological inhibitors might have potential therapeutic effects in sepsis-induced AKI. Hence, understanding the pathophysiology of sepsis-induced AKI may help to develop novel therapeutics to attenuate the complications of sepsis and lower the mortality rate. This review updates the recent progress of underlying pathophysiological mechanisms of sepsis-associated AKI, focuses specifically on autophagy, and summarizes the potential therapeutic effects of phytochemicals and pharmacological inhibitors.

Knockdown of P2Y4 ameliorates sepsis-induced acute kidney injury in mice via inhibiting the activation of the NF-κB/MMP8 axis

Sepsis-induced acute kidney injury (S-AKI) has emerged as a frequent and life-threatening complication in critically ill patients, which is characterized by a systematic inflammatory response and a rapid decline in kidney function. P2Y4, a member of G protein–coupled P2Y nucleotide receptor family, has been reported to serve as a crucial player in inflammatory responses during the development of neurocognitive disorder and myocardial infarction. Nonetheless, the biological role of P2Y4 in S-AKI remains largely unclear. This study aimed to decipher the biological role of P2Y4 in S-AKI and illuminate the potential mechanisms. In this study, S-AKI models were successfully established in mice via cecal ligation and puncture. Results showed that the kidney tissues from S-AKI mouse models exhibited a higher P2Y4 expression level than from the sham-operated group. Knockdown of P2Y4 was found to remarkably alleviate kidney damage and reduce inflammatory response in mice of S-AKI models. Moreover, P2Y4 ablation inhibited the activation of the NF-κB/MMP-8 signaling axis. Additionally, mechanistic studies revealed that rescuing MMP-8 reversed the alleviating effects of P2Y4 knockdown against renal cell damage. Collectively, our findings indicate that P2Y4 knockdown ameliorated S-AKI in mice via inhibiting the activation of the NF-κB/MMP-8 axis and that P2Y4 may represent a novel therapeutic target for S-AKI patients.

Sepsis and Acute Kidney Injury: A Review Focusing on the Bidirectional Interplay

Although sepsis and acute kidney injury (AKI) have a bidirectional interplay, the pathophysiological mechanisms between AKI and sepsis are not clarified and worthy of a comprehensive and updated review. The primary pathophysiology of sepsis-associated AKI (SA-AKI) includes inflammatory cascade, macrovascular and microvascular dysfunction, cell cycle arrest, and apoptosis. The pathophysiology of sepsis following AKI contains fluid overload, hyperinflammatory state, immunosuppression, and infection associated with kidney replacement therapy and catheter cannulation. The preventive strategies for SA-AKI are non-specific, mainly focusing on infection control and preventing further kidney insults. On the other hand, the preventive strategies for sepsis following AKI might focus on decreasing some metabolites, cytokines, or molecules harmful to our immunity, supplementing vitamin D3 for its immunomodulation effect, and avoiding fluid overload and unnecessary catheter cannulation. To date, several limitations persistently prohibit the understanding of the bidirectional pathophysiologies. Conducting studies, such as the Kidney Precision Medicine Project, to investigate human kidney tissue and establishing parameters or scores better to determine the occurrence timing of sepsis and AKI and the definition of SA-AKI might be the prospects to unveil the mystery and improve the prognoses of AKI patients.

miR-181a-5p Inhibits Pyroptosis in Sepsis-Induced Acute Kidney Injury through Downregulation of NEK7

Sepsis is a life-threatening organ dysfunction caused by the uncontrolled inflammation, easily affecting the kidney. Sepsis-induced acute kidney injury (S-AKI) has high morbidity and mortality, of which the pathophysiological mechanisms have not been completely illuminated, leading to nonspecific therapies. Specific microRNAs were related with the pathogenesis of AKI. However, only limited studies focused on the pyroptosis in the context of S-AKI. The in vitro LPS-induced HK-2 cell model and in vivo CLP-induced mouse model were established. qRT-PCR, Western blot, ELISA, and RNA pulldown were used for expression examination. Multiple biological databases were used for miRNA screening. H&E staining and IHC staining were performed. The LPS-induced HK-2 cells showed significantly increased (P < 0.01) fluorescence intensity of N-GSDMD and ASC compared with the HK-2 cells. The expression of NLRP3, NEK7, ASC, active caspase-1, and N-GSDMD was significantly enhanced (P < 0.05) and the inflammatory factors including IL-18, IL-1β, and THF-α were all increased in LPS-induced HK-2 cells and CLP-induced mice. Renal edema, serum Cr and BUN, and expression of KIM-1 and NGAL were significantly higher (P < 0.05) in CLP-induced S-AKI mice than the sham group. miR-101-3p, miR-144-3p, miR-181a-5p, miR-4262, and miR-513b-5p could inhibit NEK7. NEK7 is an interacting protein of miRNA-181a-5p. miR-181a-5p inhibits pyroptosis of the LPS-induced HK-2 cells through downregulation of NEK7. Pyroptosis of HK-2 cells promotes inflammation. miR-181a-5p inhibits pyroptosis through downregulation of NEK7 in LPS-induced HK-2 cells and CLP-induced mice. Our study indicated miR-181a-5p as a new potential therapeutic target for S-AKI therapy.

Characteristics of risk factors for acute kidney injury among inpatients administered sulfamethoxazole/trimethoprim: a retrospective observational study

Background

Sulfamethoxazole/trimethoprim (SMX/TMP) potentially increases the serum creatinine levels, resulting in acute kidney injury (AKI). However, the clinical characteristics of the AKI associated with SMX/TMP and the risk factors for its development have not been fully characterized.

Methods

A retrospective cohort observational analysis was conducted on adult inpatients who started SMX/TMP treatment at the Tokyo Women’s Medical University, Yachiyo Medical Center, from April 2018 to March 2020. The primary outcome was AKI, defined as an increase in serum creatinine level of ≥ 50% from baseline. Multivariate logistic regression analysis was used to determine the risk factors for the AKI associated with SMX/TMP.

Results

Of the 281 patients, 32 (11.4%) developed AKI. The multivariate logistic regression analysis identified that body mass index (BMI) (odds ratio [OR] = 0.86, 95% confidence interval [95% CI] 0.76–0.97, p < 0.01), presence of hypertension (OR = 2.69, 95% CI 1.11–6.49, p = 0.02), SMX/TMP daily dose (OR = 1.16, 95% CI 1.03–1.30, p = 0.02), and concomitant loop diuretic use (OR = 2.91, 95% CI 1.08–7.78, p = 0.04) were the associated risk factors for AKI in patients who were administered SMX/TMP.

Conclusions

This study showed that low BMI, hypertension, high-dose SMX/TMP, and concomitant loop diuretic use increased the risk of AKI in patients administered SMX/TMP. Clinicians should consider monitoring the renal function in patients at a high risk of AKI.

Inhibition of Xanthine Oxidase Protects against Sepsis-Induced Acute Kidney Injury by Ameliorating Renal Hypoxia

Xanthine oxidase (XO) utilizes molecular oxygen as a substrate to convert purine substrates into uric acid, superoxide, and hydrogen peroxide, which is one of the main enzyme pathways to produce reactive oxygen species (ROS) during septic inflammation and oxidative stress. However, it is not clear whether XO inhibition can improve sepsis-induced renal hypoxia in sepsis-induced acute kidney injury (SI-AKI) mice. In this study, pretreatment with febuxostat, an XO-specific inhibitor, or kidney knockdown of XO by shRNA in vivo significantly improved the prognosis of SI-AKI, not only by reducing the levels of blood urea nitrogen, serum creatinine, tumor necrosis factor-α, interleukin-6, and interleukin-1β in peripheral blood but also by improving histological damage and apoptosis, reducing the production of ROS, and infiltrating neutrophils and macrophages in the kidney. More importantly, we found that pharmacological and genetic inhibition of XO significantly improved renal hypoxia in SI-AKI mice by a hypoxia probe via fluorescence staining. This effect was further confirmed by the decrease in hypoxia-inducible factor-1α expression in the kidneys of mice with pharmacological and genetic inhibition of XO. In vitro, the change in XO activity induced by lipopolysaccharide was related to the change in hypoxia in HK-2 cells. Febuxostat and XO siRNA significantly relieved the hypoxia of HK-2 cells cultured in 2% oxygen and reversed the decrease in cell viability induced by lipopolysaccharide. Our results provide novel insights into the nephroprotection of XO inhibition in SI-AKI, improving cell hypoxia by inhibiting XO activity and reducing apoptosis, inflammation, and oxidative stress.

Th17/Regulatory T-Cell Imbalance and Acute Kidney Injury in Patients with Sepsis

To analyze the predictive value of the Th17/Treg ratio for renal injury in sepsis patients, a prospective observational study was conducted. Adult patients with sepsis were enrolled and divided into a sepsis-induced acute kidney injury (SAKI) group and a sepsis-without-AKI group. Logistic regression was used to analyze the independent predictors of SAKI, and the ROC curve was plotted to evaluate the predictive value of the Th17/Treg ratio for renal injury in patients with sepsis. A total of 124 patients were enrolled in this study, including 60 cases (48.39%) of SAKI. Patients who developed sepsis-induced acute kidney injury had a higher Th17/Treg ratio level compared to patients without it (0.11 [0.07, 0.28] versus 0.06 [0.05, 0.16], p < 0.05, respectively. The area under the receiver operating characteristic curve of the Th17/Treg ratio to predict sepsis-induced acute kidney injury was 0.669 (95% CI 0.574−0.763, p < 0.05). The Th17/Treg ratio was associated with SAKI (OR 1.15, 95%CI [1.06−1.24], p < 0.05, non-adjusted and R 1.12, 95%CI [1.00−1.25], p < 0.05, adjusted). The use of the Th17/Treg ratio improved the prediction performance of the prediction model of NAGL. The median Th17/Treg ratio significantly increased with the stratified KDIGO stage (p < 0.05). Th17/Treg imbalance was associated with occurrence of acute kidney injury and AKI severity in patients with sepsis. The Th17/Treg ratio could be a potential predictive marker of sepsis-induced acute kidney injury.

Influence of the Initial Neutrophils to Lymphocytes and Platelets Ratio on the Incidence and Severity of Sepsis-Associated Acute Kidney Injury: A Double Robust Estimation Based on a Large Public Database

Background

Acute kidney injury (AKI) is a frequent consequence of sepsis and has been linked to poor prognosis. In critically ill patients, the ratio of neutrophils to lymphocytes and platelets (N/LP) has been confirmed as an inflammation-related marker connected with the development of renal dysfunction. However, the effect of the N/LP ratio on the initiation and development of AKI in patients with sepsis remained unclear. The purpose of this study was to determine if the N/LP ratio on intensive care unit (ICU) admission was associated with the occurrence of sepsis-associated AKI (S-AKI) and severe AKI.

Methods

Adult septic patients from the Medical Information Mart for Intensive Care-IV database were screened and classified into three categories (low, middle, or high) based on their N/LP ratio quartiles. The Cox proportional hazard and competing risk models were used to determine the risk of S-AKI in various N/LP groups, whilst the logistic regression model and restricted cubic splines (RCS) analysis were employed to investigate the link between N/LP ratios and the occurrence of severe AKI. Finally, we did a doubly robust estimation, a subgroup analysis, and a sensitivity analysis to determine the findings’ robustness.

Results

We categorized 485, 968, and 485 septic patients into three groups based on their N/LP ratios: low, intermediate, and high. According the Cox proportional hazard model, the hazard rate (95% CI) for those in the middle and high N/LP groups on the incidence of S-AKI were 1.30(1.07, 1.58) and 1.27(1.02, 1.59), respectively, as compared to those in the low N/LP group. And the Fine-Gray proportional subdistribution hazards model indicated that mortality was not a substantial competing risk for S-AKI. Additionally, multivariate logistic regression revealed that the risk of severe AKI increased 1.83 fold in the high group compared to the low group. The RCS result also suggested that the probability of severe AKI rose significantly when N/LP > 9.5. The consistency of these findings was confirmed using doubly robust estimation. However, subgroup and sensitivity analyses revealed that the association between N/LP and the incidence of S-AKI, severe AKI varied considerably between different populations and diagnostic criteria.

Conclusion

A raised initial N/LP level may induce the development of S-AKI and severe AKI within 7 days after ICU admission in septic patients. These influences were enhanced in elder, male, septic shock, and those with poor health condition. Furthermore, high NLP was more strongly connected to the risk of S-AKI and severe AKI in sepsis patients on the urine output-based AKI criteria than on the serum creatinine-based criteria.

A Single Oral Dose of Diclofenac Causes Transition of Experimental Subclinical Acute Kidney Injury to Chronic Kidney Disease

Nephrotoxic drugs can cause acute kidney injury (AKI) and analgesic nephropathy. Diclofenac is potentially nephrotoxic and frequently prescribed for pain control. In this study, we investigated the effects of single and repetitive oral doses of diclofenac in the setting of pre-existing subclinical AKI on the further course of AKI and on long-term renal consequences. Unilateral renal ischemia–reperfusion injury (IRI) for 15 min was performed in male CD1 mice to induce subclinical AKI. Immediately after surgery, single oral doses (100 mg or 200 mg) of diclofenac were administered. In a separate experimental series, repetitive treatment with 100 mg diclofenac over three days was performed after IRI and sham surgery. Renal morphology and pro-fibrotic markers were investigated 24 h and two weeks after the single dose and three days after the repetitive dose of diclofenac treatment using histology, immunofluorescence, and qPCR. Renal function was studied in a bilateral renal IRI model. A single oral dose of 200 mg, but not 100 mg, of diclofenac after IRI aggravated acute tubular injury after 24 h and caused interstitial fibrosis and tubular atrophy two weeks later. Repetitive treatment with 100 mg diclofenac over three days aggravated renal injury and caused upregulation of the pro-fibrotic marker fibronectin in the setting of subclinical AKI, but not in sham control kidneys. In conclusion, diclofenac aggravated renal injury in pre-existing subclinical AKI in a dose and time-dependent manner and already a single dose can cause progression to chronic kidney disease (CKD) in this model.

Sepsis Encephalopathy Is Partly Mediated by miR370-3p-Induced Mitochondrial Injury but Attenuated by BAM15 in Cecal Ligation and Puncture Sepsis Male Mice

BAM15 (a mitochondrial uncoupling agent) was tested on cecal ligation and puncture (CLP) sepsis mice with in vitro experiments. BAM15 attenuated sepsis as indicated by survival, organ histology (kidneys and livers), spleen apoptosis (activated caspase 3), brain injury (SHIRPA score, serum s100β, serum miR370-3p, brain miR370-3p, brain TNF-α, and apoptosis), systemic inflammation (cytokines, cell-free DNA, endotoxemia, and bacteremia), and blood-brain barrier (BBB) damage (Evan's blue dye and the presence of green fluorescent E. coli in brain after an oral administration). In parallel, brain miR arrays demonstrated miR370-3p at 24 h but not 120 h post-CLP, which was correlated with metabolic pathways. Either lipopolysaccharide (LPS) or TNF-α upregulated miR370-3p in PC12 (neuron cells). An activation by sepsis factors (LPS, TNF-α, or miR370-3p transfection) damaged mitochondria (fluorescent color staining) and reduced cell ATP, possibly through profound mitochondrial activity (extracellular flux analysis) that was attenuated by BAM15. In bone-marrow-derived macrophages, LPS caused mitochondrial injury, decreased cell ATP, enhanced glycolysis activity (extracellular flux analysis), and induced pro-inflammatory macrophages (iNOS and IL-1β) which were neutralized by BAM15. In conclusion, BAM15 attenuated sepsis through decreased mitochondrial damage, reduced neuronal miR370-3p upregulation, and induced anti-inflammatory macrophages. BAM15 is proposed to be used as an adjuvant therapy against sepsis hyperinflammation.

Machine learning for the prediction of acute kidney injury in patients with sepsis

BACKGROUND

Acute kidney injury (AKI) is the most common and serious complication of sepsis, accompanied by high mortality and disease burden. The early prediction of AKI is critical for timely intervention and ultimately improves prognosis. This study aims to establish and validate predictive models based on novel machine learning (ML) algorithms for AKI in critically ill patients with sepsis.

METHODS

Data of patients with sepsis were extracted from the Medical Information Mart for Intensive Care III (MIMIC- III) database. Feature selection was performed using a Boruta algorithm. ML algorithms such as logistic regression (LR), k-nearest neighbors (KNN), support vector machine (SVM), decision tree, random forest, Extreme Gradient Boosting (XGBoost), and artificial neural network (ANN) were applied for model construction by utilizing tenfold cross-validation. The performances of these models were assessed in terms of discrimination, calibration, and clinical application. Moreover, the discrimination of ML-based models was compared with those of Sequential Organ Failure Assessment (SOFA) and the customized Simplified Acute Physiology Score (SAPS) II model.

RESULTS

A total of 3176 critically ill patients with sepsis were included for analysis, of which 2397 cases (75.5%) developed AKI during hospitalization. A total of 36 variables were selected for model construction. The models of LR, KNN, SVM, decision tree, random forest, ANN, XGBoost, SOFA and SAPS II score were established and obtained area under the receiver operating characteristic curves of 0.7365, 0.6637, 0.7353, 0.7492, 0.7787, 0.7547, 0.821, 0.6457 and 0.7015, respectively. The XGBoost model had the best predictive performance in terms of discrimination, calibration, and clinical application among all models.

CONCLUSION

The ML models can be reliable tools for predicting AKI in septic patients. The XGBoost model has the best predictive performance, which can be used to assist clinicians in identifying high-risk patients and implementing early interventions to reduce mortality.

The miR-26a-5p/IL-6 axis alleviates sepsis-induced acute kidney injury by inhibiting renal inflammation

Sepsis-induced acute kidney injury (AKI) is a common and life-threatening complication in hospitalized and critically ill patients and has unacceptable morbidity and mortality rates. However, effective approaches for the diagnosis and treatment of septic AKI are still lacking. Here, we demonstrated significant increases in the miR-26a-5p levels in renal tubular cells of LPS-induced septic AKI models both in vivo and in vitro. Mechanistically, we provided evidence of the involvement of NF-κB in miR-26a-5p induction. LPS treatment of renal tubular cells led to the activation of NF-κB, and inhibition of NF-κB by TPCA-1 prevented the induction of miR-26a-5p. These results indicated that NF-κB was a key upstream factor for the induction of miR-26a-5p in septic AKI. Anti-miR-26a-5p enhanced the expression of IL-6 at both the protein and mRNA levels following LPS treatment. Furthermore, our luciferase microRNA target reporter assay verified that IL-6 is a direct target of miR-26a-5p. Blocking miR-26a-5p promoted renal inflammation and worsened kidney injury. Thus, our study indicated that the miR-26a-5p/IL-6 axis can alleviate sepsis-induced acute kidney injury by inhibiting renal inflammation. This mechanism may represent a therapeutic target for septic AKI.

Autophagy-driven neutrophil extracellular traps: The dawn of sepsis

Sepsis is a systemic inflammatory syndrome caused by infection disorders. The core mechanism of sepsis is immune dysfunction. Neutrophils are the most abundant circulating white blood cells, which play a crucial role in mediating the innate immune response. Previous studies have shown that an effective way to treat sepsis is through the regulation of neutrophil functions. Autophagy, a highly conserved degradation process, is responsible for removing denatured proteins or damaged organelles within cells and protecting cells from external stimuli. It is a key homeostasis process that promotes neutrophil function and differentiation. Autophagy has been shown to be closely associated with inflammation and immunity. Neutrophils, the first line of innate immunity, migrate to inflammatory sites upon their activation. Neutrophil-mediated autophagy may participate in the clinical course of sepsis. In this review, we summarized and analyzed the latest research findings on the changes in neutrophil external traps during sepsis, the regulatory role of autophagy in neutrophil, and the potential application of autophagy-driven NETs in sepsis, so as to guide clinical treatment of sepsis.

Salidroside Protects Acute Kidney Injury in Septic Rats by Inhibiting Inflammation and Apoptosis

Purpose

To clarify the protective effect and mechanism of salidroside (SLDS) on acute kidney injury (AKI) in septic rats.

Methods

We pretreated rats with different doses of SLDS and analyzed the impact of SLDS on the survival of septic rats. We evaluated the levels of inflammatory factors in rats, the expression of NF-ƙB p65 in the kidney, and the apoptosis of kidney tubular epithelial cells (KTECs).

Results

SLDS significantly decreased the mortality of septic rats, and it reduced the levels of TNF-α, IL-1β, and IL-17A in plasma and kidneys and decreased the levels of serum creatinine, plasma renal injury molecule-1 and plasma neutrophil gelatin-associated lipocalin. Moreover, SLDS could significantly decrease the expression of NF-ƙB p65 in kidney tissues and the apoptotic number of KETCs, while reducing the mRNA levels of Caspase-3 and Bax mRNA, and increasing the level of Bcl-2 mRNA.

Conclusion

SLDS pretreatment protects against AKI in septic rats by inhibiting the inflammation of kidney and the apoptosis of KTECs.

Relevant Equine Renal Anatomy, Physiology, and Mechanisms of Acute Kidney Injury: A Review

Regulation of renal blood flow is by both extrinsic and intrinsic systems. Intrinsic regulation occurs via the afferent and efferent arterioles and tubuloglomerular feedback mechanisms with activation of the juxtaglomerular apparatus. Mechanisms of acute kidney injury are frequently associated with changes in renal blood flow. Acute tubular necrosis and apoptosis are common in horses following ischemic or toxic insults and in sepsis-associated acute kidney injury. Sepsis-associated renal injury often has a complex mechanism of disease involving both functional and obstructive changes in intrarenal circulation. Acute interstitial nephritis may occur following Leptospira sp infection or can be secondary to tubular necrosis.

Experimental models of acute kidney injury for translational research

Preclinical models of human disease provide powerful tools for therapeutic discovery but have limitations. This problem is especially apparent in the field of acute kidney injury (AKI), in which clinical trial failures have been attributed to inaccurate modelling performed largely in rodents. Multidisciplinary efforts such as the Kidney Precision Medicine Project are now starting to identify molecular subtypes of human AKI. In addition, over the past decade, there have been developments in human pluripotent stem cell-derived kidney organoids as well as zebrafish, rodent and large animal models of AKI. These organoid and AKI models are being deployed at different stages of preclinical therapeutic development. However, the traditionally siloed, preclinical investigator-driven approaches that have been used to evaluate AKI therapeutics to date rarely account for the limitations of the model systems used and have given rise to false expectations of clinical efficacy in patients with different AKI pathophysiologies. To address this problem, there is a need to develop more flexible and integrated approaches, involving teams of investigators with expertise in a range of different model systems, working closely with clinical investigators, to develop robust preclinical evidence to support more focused interventions in patients with AKI.

Impact of central venous pressure on the mortality of patients with sepsis-related acute kidney injury: a propensity score-matched analysis based on the MIMIC IV database

Background

Sepsis has long been a life-threatening organ dysfunction. Sepsis associated acute kidney injury (SA-AKI) is an important complication of sepsis, as an important hemodynamic index, the impact of central venous pressure (CVP) on sepsis patients needs to be explored. Thus this study aimed to investigate the relationship between CVP and the mortality of SA-AKI.

Methods

Clinical data of adult patients with sepsis-related acute kidney injury, defined as met both the Sepsis 3.0 criteria and the Kidney Disease Improving Global Outcomes Clinical Practice Guideline (KDIGO) criteria, were obtained from the Medical Information Mart for Intensive Care-IV (MIMIC-IV) database. The included cohort was divided into a high CVP and a low CVP group were determined based on the cuf-off value from receiver operating characteristic curve, with propensity score-matched analysis of the 28-day mortality for both groups and sensitivity analysis using inverse the probability-weighting model, multifactorial regression, and doubly robust estimation, patients acquired chronic coronary syndrome (CCS) and diabetes were also taken into consideration.

Results

Of 1,377 patients with sepsis-related acute kidney injury, low CVP group (<13 mmHg) was 67.4% (n=928) and high CVP group (≥13 mmHg) was 32.6% (n=449). The two groups were matched 1:1 by propensity score to obtain a matched cohort (n=288). The mortality rates in the low versus high CVP group (19.4% vs. 34.7%) were statistically difference (odds ratio OR: 0.454; 95% confidence interval 0.263, 0.771). Moreover, the bistable analysis of logistic regression of the matched cohort (OR: 0.434; 95% CI: 0.244, 0.757), propensity score inverse probability weighting (IPW) (OR: 0.547; 95% CI: 0.454, 0.658), and multifactorial logistic regression (OR: 0.352; 95% CI: 0.127, 0.932) all yielded the same results.

Conclusions

In patients with sepsis-related acute kidney injury, a lower CVP level (<13 mmHg) is an independent variable associated with decreased mortality. The threshold of CVP needs to be controlled in clinical work to improve the prognosis of patients with SA-AKI.

Astragalus polysaccharide protects sepsis model rats after cecum ligation and puncture

To investigate the protective effect and mechanism of Astragalus polysaccharide (APS) on septic rats, the present project applied APS at concentrations of 400, 600, and 800 mg/kg/d to rats for prophylactic administration for 7 d, and a rat sepsis model was constructed by the cecum ligation and puncture (CLP) method. Forty-eight rats were divided into six groups of eight each. Each experiment was repeated at least three times. Rat serum levels of VD₃, 25(OH)D₃, 1,25(OH)₂D₃, IL-6, TNF-α, CRP, sICAM-1, corticosterone (CORT), and short-chain fatty acids (SCFAs) in each group were detected, and renal damage was observed by H&E. We also determined the protein expression of CYP27B1, CYP24A1, vitamin D receptor (VDR), steroidogenic acute regulatory protein (STAR), 3β-hydroxysteroid dehydrogenase (3β-HSD), CYP21A2, CYP17A1, and CYP11B1. An operational taxonomic unit (OTU) was used to determine the gut microbiota diversity of septic rats after prophylactic administration and before modeling. Results revealed that APS markedly increased the contents of 25(OH)D₃ and 1,25(OH)₂D₃ but greatly decreased those of TNF-α, IL-6, CRP, sICAM-1, and CORT. APS alleviated renal tubular dilation and vascular congestion in rat kidneys and substantially reduced renal cell apoptosis. Moreover, the expression of CYP24A1, VDR, CYP11B1, CYP21A2, CYP17A1, STAR, and 3β-HSD in the kidneys of the H-APS group was substantially decreased compared to that of the model group, whereas CYP27B1 was markedly increased. GC-MS detection indicated a substantial increase in SCFAs and acetic acid content in the H-APS group versus model group. Through 16S sequencing, the abundance of genus and gut microbiota species increased in the APS groups compared to that of the control group. Taken together, APS increased the activity of the vitamin D axis, inhibited the production of inflammatory factors in the body, altered the structure of rat intestinal flora, and increased the amount of acetic acid and SCFAs in rats, thereby effectively hindering inflammation and organ damage in septic rats.

Pediatric sepsis biomarkers for prognostic and predictive enrichment

Sepsis is a major public health problem in children throughout the world. Given that the treatment guidelines emphasize early recognition, there is interest in developing biomarkers of sepsis, and most attention is focused on diagnostic biomarkers. While there is a need for ongoing discovery and development of diagnostic biomarkers for sepsis, this review will focus on less well-known applications of sepsis biomarkers. Among patients with sepsis, the biomarkers can give information regarding the risk of poor outcome from sepsis, risk of sepsis-related organ dysfunction, and subgroups of patients with sepsis who share underlying biological features potentially amenable to targeted therapeutics. These types of biomarkers, beyond the traditional concept of diagnosis, address the important concepts of prognostic and predictive enrichment, which are key components of bringing the promise of precision medicine to the bedside of children with sepsis.

Renal histopathology in critically ill patients with Septic Acute Kidney Injury(S-AKI)

PURPOSE

To describe the kidney histopathology of patients with S-AKI and correlate the histological findings with AKI severity, presence of septic shock, and the degree of multiple organic dysfunction (MOD) using the SOFA score.

MATERIALS AND METHODS

This was a prospective, observational, and analytical study of a cohort of critically ill patients with S-AKI who died from sepsis at the "Hospital Español" intensive care unit (ICU). Kidney necropsies were performed within 2 h after death.

RESULTS

We considered twenty (20) patients, with all of them exhibiting S-AKI stage 3 at the same time. In renal histopathology analysis, nonspecific tubulointerstitial (TI) lesions were found in almost all patients (95%). The more frequently found nonspecific TI lesions involved leukocyte infiltration (85%). Necrotic TI lesions were found in 6 patients (30%), and necrotic tubular cell casts were the most frequent lesions (50% of patients). It was not possible to demonstrate an association between the presence of necrotic TI lesions and factors such as the APACHE II score, the global SOFA score, ICU stays, AKI length and renal replacement therapy (RRT).

CONCLUSIONS

The main histopathological findings in kidney necropsies in patients with S-AKI KDIGO 3, showed nonspecific TI lesions, and TI necrosis was only observed in 30% of the cases; therefore, S-AKI cannot be considered to be synonymous with acute tubular necrosis (ATN).

LncRNA KCNQ1OT1 (potassium voltage-gated channel subfamily Q member 1 opposite strand/antisense transcript 1) aggravates acute kidney injury by activating p38/NF-κB pathway via miR-212-3p/MAPK1 (mitogen-activated protein kinase 1) axis in sepsis

Acute kidney injury (AKI), a common complication of sepsis, is characterized by a rapid loss of renal excretory function. A variety of etiologies and pathophysiological processes may contribute to AKI. Previously, mitogen-activated protein kinase 1 (MAPK1) was reported to regulate cellular processes in various sepsis-associated diseases. The current study aimed to further explore the biological function and regulatory mechanism of MAPK1 in sepsis-induced AKI. In our study, MAPK1 exhibited high expression in the serum of AKI patients. Functionally, knockdown of MAPK1 suppressed inflammatory response, cell apoptosis in response of lipopolysaccharide (LPS) induction in HK-2 cells. Moreover, MAPK1 deficiency alleviated renal inflammation, renal dysfunction, and renal injury in vivo. Mechanistically, MAPK1 could activate the downstream p38/NF-κB pathway. Moreover, long noncoding RNA potassium voltage-gated channel subfamily Q member 1 opposite strand/antisense transcript 1 (KCNQ1OT1) was identified to serve as a competing endogenous RNA for miR-212-3p to regulate MAPK1. Finally, rescue assays indicated that the inhibitory effect of KCNQ1OT1 knockdown on inflammatory response, cell apoptosis, and p38/NF-κB pathway was reversed by MAPK1 overexpression in HK-2 cells. In conclusion, KCNQ1OT1 aggravates acute kidney injury by activating p38/NF-κB pathway via miR-212-3p/MAPK1 axis in sepsis. Therefore, KCNQ1OT may serve as a potential biomarker for the prognosis and diagnosis of AKI patients.

Neutrophil extracellular traps and organ dysfunction in sepsis

Sepsis is a clinical syndrome resulting from infection followed by inflammation and is one of the significant causes of mortality worldwide. The underlying reason is the host's uncontrolled inflammatory response due to an infection led to multiple organ dysfunction/failure. Neutrophils, an innate immune cell, are forerunners to reach the site of infection/inflammation for clearing the infection and resolute the inflammation during sepsis. A relatively new neutrophil effector function, neutrophil extracellular traps (NETs), have been demonstrated to kill the pathogens by releasing DNA decorated with histone and granular proteins. A growing number of pieces of shreds of evidence suggest that unregulated incidence of NETs have a significant influence on the pathogenesis of sepsis-induced multiple organ damage, including arterial hypotension, hypoxemia, coagulopathy, renal, neurological, and hepatic dysfunction. Thus, excessive production and improper resolution of NETs are of significant therapeutic value in combating sepsis-induced multiple organ failure. The purpose of this review is intended to highlight the role of NETs in sepsis-induced organ failure. Furthermore, the current status of therapeutic strategies to intersect the harmful effects of NETs to restore organ functions is discussed.

Sepsis: Evidence-based pathogenesis and treatment

Sepsis can develop during the body’s response to a critical illness leading to multiple organ failure, irreversible shock, and death. Sepsis has been vexing health care providers for centuries due to its insidious onset, generalized metabolic dysfunction, and lack of specific therapy. A common factor underlying sepsis is the characteristic hypermetabolic response as the body ramps up every physiological system in its fight against the underlying critical illness. A hypermetabolic response requires supraphysiological amounts of energy, which is mostly supplied via oxidative phosphorylation generated ATP. A by-product of oxidative phosphorylation is hydrogen peroxide (H₂O₂), a toxic, membrane-permeable oxidizing agent that is produced in far greater amounts during a hypermetabolic state. Continued production of mitochondrial H₂O₂ can overwhelm cellular reductive (antioxidant) capacity leading to a build-up within cells and eventual diffusion into the bloodstream. H₂O₂ is a metabolic poison that can inhibit enzyme systems leading to organ failure, microangiopathic dysfunction, and irreversible septic shock. The toxic effects of H₂O₂ mirror the clinical and laboratory abnormalities observed in sepsis, and toxic levels of blood H₂O₂ have been reported in patients with septic shock. This review provides evidence to support a causal role for H₂O₂ in the pathogenesis of sepsis, and an evidence-based therapeutic intervention to reduce H₂O₂ levels in the body and restore redox homeostasis, which is necessary for normal organ function and vascular responsiveness.

PICK1 Deficiency Exacerbates Sepsis-Associated Acute Kidney Injury

We performed in vitro and in vivo experiments to explore the role of protein kinase C-binding protein 1 (PICK1), an intracellular transporter involved in oxidative stress-related neuronal diseases, in sepsis-related acute kidney injury (AKI). Firstly, PCR, western blotting, and immunohistochemistry were used to observe the expression of PICK1 after lipopolysaccharide- (LPS-) induced AKI. Secondly, by inhibiting PICK1 in vivo and silencing PICK1 in vitro, we further explored the effect of PICK1 on AKI. Finally, the relationship between PICK1 and oxidative stress and the related mechanisms were explored. We found that the expression of PICK1 was increased in LPS-induced AKI models both in vitro and in vivo. PICK1 silencing significantly aggravated LPS-induced apoptosis, accompanied by ROS production in renal tubular epithelial cells. FSC231, a PICK1-specific inhibitor, aggravated LPS-induced kidney injury. Besides, NAC (N-acetylcysteine), a potent ROS scavenger, significantly inhibited the PICK1-silencing-induced apoptosis. In conclusion, PICK1 might protect renal tubular epithelial cells from LPS-induced apoptosis by reducing excessive ROS, making PICK1 a promising preventive target in LPS-induced AKI.