Long-term impact of acute kidney injury on prognosis in patients with acute myocardial infarction

Association of SGLT2 inhibitor dapagliflozin with risks of acute kidney injury and all-cause mortality in acute myocardial infarction patients

OBJECTIVE

Sodium-glucose cotransporter 2 (SGLT2) inhibitors have well-documented effects in reducing hospitalization or cardiovascular mortality, while the association of SGLT2 inhibitor dapagliflozin (DAPA) and the risk of acute kidney injury (AKI) in acute myocardial infarction (AMI) patients has not been comprehensively investigated. Therefore, we aimed to assess the association between DAPA and AKI risk in AMI patients after percutaneous coronary intervention (PCI) therapy.

METHODS

Using the Changzhou Acute Myocardial Infarction Registry database, we retrospectively included AMI patients from January 2017 to August 2021 and analyzed the risk of AKI and all-cause mortality after PCI therapy. The patients were divided into two groups according to the use of DAPA (DAPA group and Ctrl group). Patients in the DAPA group started to use DAPA after admission and continued its use during hospitalization and follow-up period. Baseline characteristics were balanced between the two groups with a propensity score matching (PSM) analysis. The outcome was AKI within 7 days after PCI and all-cause mortality during a follow-up of 2 years. Univariate and multivariate logistic regression analyses were used to assess the association between DAPA and AKI risk.

RESULTS

A total of 1839 AMI patients undergoing PCI were enrolled. DAPA was used in 278 (15.1%) patients. Postoperative AKI occurred in 351 (19.1%) cases. A 1:1 PSM analysis was used to reduce confounding factors. The multivariate stepwise regression analysis showed that DAPA (odds ratio, OR 0.66; 95% confidence interval, CI 0.44-0.97; P = 0.036) was an independent protective factor in the entire cohort. After matching, the use of DAPA in AMI patients was independently associated with a decline of AKI risk (OR 0.32; 95% CI, 0.19-0.53; P < 0.001) after hospital admission. Meanwhile, there were significant differences in mortality between the DAPA group and Ctrl group (2.5% vs. 7.6%, P = 0.012).

CONCLUSION

SGLT2 inhibitor DAPA was associated with lower risks of incident AKI and all-cause mortality in AMI patients after PCI therapy.

Acute kidney injury prediction model utility in premature myocardial infarction

The incidence of premature myocardial infarction (PMI) has been rising and acute kidney injury (AKI) occurring in PMI patients severely impacts prognosis. This study aimed to develop and validate a prediction model for AKI specific to PMI patients. The MIMIC-Ⅲ-CV and MIMIC-Ⅳ databases were utilized for model derivation of PMI patients. Single-center data served for external validation. There were 571 and 182 AKI patients in the training set (n = 937) and external validation set (n = 292) cohorts, respectively. Finally, a 7-variable model consisting of: Sequential Organ Failure Assessment (SOFA) score, coronary artery bypass grafting (CABG), ICU stay time, loop diuretics, estimated glomerular filtration rate (eGFR) HCO3- and Albumin was developed, achieving an AUC of 0.85 (95% CI: 0.83-0.88) in the training set. External validation also confirmed model robustness. This model may assist clinicians in the early identification of patients at elevated risk for PMI. Further validation is warranted before clinical application.

Association between triglyceride-glucose index and acute kidney injury in patients with acute myocardial infarction based on medical information mart for intensive care database: A cross-sectional study

Background

The relationship between triglyceride glucose (TyG) index and the incidence of acute kidney injury (AKI) in patients with acute myocardial infarction (AMI) is unclear. This study aims to explore the relationship between the two.

Methods

Participants were enrolled from Medical Information Mart for Intensive Care IV (MIMICIV) and grouping of subjects based on the quartile interval of the TyG index. With the presence of AKI as the main outcome, a logistic regression model was constructed. The correlation of the TyG index with the results obtained was examined by using a restricted cubic spline (RCS) model.

Predictive modeling for acute kidney injury after percutaneous coronary intervention in patients with acute coronary syndrome: a machine learning approach

BACKGROUND

Acute kidney injury (AKI) is one of the preventable complications of percutaneous coronary intervention (PCI). This study aimed to develop machine learning (ML) models to predict AKI after PCI in patients with acute coronary syndrome (ACS).

METHODS

This study was conducted at Tehran Heart Center from 2015 to 2020. Several variables were used to design five ML models: Naïve Bayes (NB), Logistic Regression (LR), CatBoost (CB), Multi-layer Perception (MLP), and Random Forest (RF). Feature importance was evaluated with the RF model, CB model, and LR coefficients while SHAP beeswarm plots based on the CB model were also used for deriving the importance of variables in the population using pre-procedural variables and all variables. Sensitivity, specificity, and the area under the receiver operating characteristics curve (ROC-AUC) were used as the evaluation measures.

RESULTS

A total of 4592 patients were included, and 646 (14.1%) experienced AKI. The train data consisted of 3672 and the test data included 920 cases. The patient population had a mean age of 65.6 ± 11.2 years and 73.1% male predominance. Notably, left ventricular ejection fraction (LVEF) and fasting plasma glucose (FPG) had the highest feature importance when training the RF model on only pre-procedural features. SHAP plots for all features demonstrated LVEF and age as the top features. With pre-procedural variables only, CB had the highest AUC for the prediction of AKI (AUC 0.755, 95% CI 0.713 to 0.797), while RF had the highest sensitivity (75.9%) and MLP had the highest specificity (64.35%). However, when considering pre-procedural, procedural, and post-procedural features, RF outperformed other models (AUC: 0.775). In this analysis, CB achieved the highest sensitivity (82.95%) and NB had the highest specificity (82.93%).

CONCLUSION

Our analyses showed that ML models can predict AKI with acceptable performance. This has potential clinical utility for assessing the individualized risk of AKI in ACS patients undergoing PCI. Additionally, the identified features in the models may aid in mitigating these risk factors.

Acute Kidney Injury in Acute Myocardial Infarction and Its Outcome at 3 and 6 Months

Epidemiological data on the prevalence of acute kidney injury (AKI) in acute coronary syndrome are sparse, with most studies having been conducted retrospectively. This study prospectively analyzed the incidence of AKI in patients with acute myocardial infarction (AMI) and to identify the risk factors for AKI and their renal outcome at 3 and 6 months. This was a prospective and observational study, which enrolled 120 patients presenting with their first episode of AMI to our hospital and consented to the study. Renal function tests were performed at admission, at 48 h, and at follow-up at 3 and 6 months. The majority of the patients underwent a percutaneous coronary intervention (59.2%), 21.7% received thrombolytic therapy, and 19.2% were managed conservatively. At 48 h, 11 patients had AKI. At 3 months, 8 patients had died, and renal dysfunctions were seen in 9 out of 112 patients. At 6 months, 12 patients out of 112 had renal dysfunction. There was no difference in the incidence of AKI in patients with an estimated glomerular filtration rate above and below 60 mL/min/1.73 m2. Killip Class 4 and diabetes mellitus were associated with an increased incidence of renal dysfunction in AMI patients. The type of treatment and the use of a contrast agent in the coronary intervention did not affect the development of AKI. According to this study, if indicated, a percutaneous coronary intervention should not be denied to patients for fear of developing AKI. This needs to be examined in larger randomized trials.

What Promotes Acute Kidney Injury in Patients with Myocardial Infarction and Multivessel Coronary Artery Disease-Contrast Media, Hydration Status or Something Else?

Multivessel coronary artery disease (MVCAD) is found in approximately 50% of patients with acute myocardial infarction (AMI) undergoing percutaneous coronary intervention (PCI). Although we have data showing the benefits of revascularization of significant non-culprit coronary lesions in patients with AMI, the optimal timing of angioplasty remains unclear. The most common reason for postponing subsequent percutaneous treatment is the fear of contrast-induced acute kidney injury (CI-AKI). Acute kidney injury (AKI) is common in patients with AMI undergoing PCI, and its etiology appears to be complex and incompletely understood. In this review, we discuss the definition, pathophysiology and risk factors of AKI in patients with AMI undergoing PCI. We present the impact of AKI on the course of hospitalization and distant prognosis of patients with AMI. Special attention was paid to the phenomenon of AKI in patients undergoing multivessel revascularization. We analyze the correlation between increased exposure to contrast medium (CM) and the risk of AKI in patients with AMI to provide information useful in the decision-making process about the optimal timing of revascularization of non-culprit lesions. In addition, we present diagnostic tools in the form of new biomarkers of AKI and discuss ways to prevent and mitigate the course of AKI.

Macrophages of the “Heart-Kidney” Axis: Their Dynamics and Correlations with Clinical Data and Outcomes in Patients with Myocardial Infarction

Changes in the macrophage infiltration of kidneys in rodents under ischemic conditions may affect cardiac macrophages and lead to development of adaptive cardiac remodeling. The aim of our study was to translate experimental findings into clinically relevant applications and assess the features of macrophage infiltration of the kidney and its correlations with changes in macrophage infiltration of the myocardium and with clinical data in patients who experienced a fatal myocardial infarction (MI). We examined fragments of both organs taken from patients (n = 30) who suffered from fatal MI. Macrophage infiltration was assessed by immunohistochemistry. Macrophage infiltration of the kidneys in patients with fatal MI is heterogeneous. The early period of MI was shown to be characterized by the prevalence of CD163+ and CD68+ cells, and in the long-term period by only CD163+ cells. However, only the level of CD206+ cells in the kidneys showed the dynamics representing the late MI period. Its decrease accompanied increase in the numbers of cardiac CD68+, CD163+, CD206+, and stabilin-1+ cells in the infarct area. Kidney CD206+ cells had more correlations with cardiac macrophages than other cells, and the presence of these cells also correlated with impairment of renal function and early death.

Acute kidney injury and in-hospital mortality in patients with ST-elevation myocardial infarction of different age groups

BACKGROUND

Acute kidney injury (AKI) is a well-known complication of ST-elevation acute myocardial infarction (STEMI) with an adverse impact on prognosis. Since AKI develops more frequently in elderly patients, we hypothesized that its higher incidence in older STEMI patients might explain their increased in-hospital mortality. We assessed the relationship between AKI and in-hospital mortality in patients with STEMI of different age groups.

METHODS

We retrospectively evaluated 5136 STEMI patients treated with primary percutaneous coronary intervention (pPCI). We defined AKI as ≥0.5 mg/dl creatinine increase in the first 72 h. Patients were grouped according to age (<75 [n = 4040] or ≥ 75 [n = 1096] years). The primary endpoint was in-hospital mortality.

RESULTS

The incidence of AKI was 7%. It was 4.6% in patients <75 years and 15.1% in those ≥75 years (P < 0.0001). The overall in-hospital mortality was 4%. It was 2.6% and 8.5% in patients younger and older than 75 years, respectively (P < 0.0001). It was higher in AKI than in non-AKI patients, both in the overall population (27% vs. 2%) and in the two age groups (25% vs. 2% and 29% vs. 5% in younger and older patients, respectively; P < 0.0001). The adjusted odds ratio of in-hospital mortality associated with AKI progressively decreased in parallel with increasing age decades (from 24.7 [95% CI 11.2-54.1] in patients <65 years to 3.9 [95% CI 1.6-9.7] in those >85 years).

CONCLUSIONS

In STEMI patients treated with pPCI, AKI incidence and in-hospital mortality steadily increase with age. However, the prognostic impact of AKI is progressively reduced as age increases.

Blending of Designer Synthetic Polymers to a Dual Targeted Nanoformulation for SARS-CoV-2 Associated Kidney Damage

As the COVID-19 pandemic has continued to spread, studies have shown that hospitalized COVID-19 patients are at significant risk for developing acute kidney injury (AKI), which can cause increased morbidity, the need for dialysis treatment, chronic kidney diseases, and even death. In this paper, we present a proof-of-concept study for the utilization of combination therapeutic-loaded dual-targeted biodegradable nanoparticles (NPs) to treat concurrent AKI and COVID-19 in patients by delivering the therapeutics across the gut epithelial barrier and to the kidney, in order to lower the viral load as well as reduce the symptoms of AKI. Despite recent vaccination efforts and the end of the COVID-19 pandemic in sight, problems related to the long-term effects of COVID-19 will continue to persist, including impacts on patients suffering from AKI and other chronic renal conditions. Therefore, the dual-targeted blended polymeric NP developed in this study to treat concurrent COVID-19 infection and AKI is a useful proof-of-concept nanoplatform for future treatments of these complications.

The Relationship Between AKI in Patients With STEMI and Short-Term Mortality: A Propensity Score Matching Analysis

Acute myocardial infarction (AMI) in patients with acute kidney injury (AKI) is associated with poor long-term outcome. However, the short-term prognosis of AKI in patients with ST-elevation AMI (STEMI) needs to be explored further. We assessed this relationship between these patients and short-term mortality in relation to AKI and chronic kidney disease (CKD). All data were extracted from the Medical Information Mart for Intensive Care III database. The primary outcome was 28-day mortality. Kaplan-Meier curves, logistic regression models, and propensity score matching analysis were used to evaluate the associations between AKI in patients with STEMI and outcomes. A total of 1031 patients with STEMI met the inclusion criteria. For 28-day mortality, in the multivariable logistic regression models, the odds ratio (95% CI) of group 2 (AKI but no CKD) and group 3 (AKI in the presence of CKD) were 3.24 (1.46-7.18) and 4.57 (1.83-11.37), respectively, compared with group 1 (no AKI and no CKD). Comorbid AKI increased the risk of short-term mortality among patients with STEMI, especially for those with AKI in the presence of CKD.

Risk factors for 28-day mortality in patients with sepsis-related myocardial injury in intensive care units

Objective

This study aimed to identify the risk factors for death in patients with sepsis-related myocardial injury.

Methods

A retrospective study was conducted in 158 patients with sepsis-related myocardial injury in a mixed medical intensive care unit from January 2009 to March 2020. The patients were divided into those who survived and those who died on the basis of whether they survived after 28 days. Demographic and clinical parameters were collected. Multivariate logistic regression was performed.

Results

Sixty-nine (43.7%) patients died within 28 days after admission to the intensive care unit. Multivariate logistic regression analysis showed that the oxygenation index (odds ratio [OR]: 0.979, 95% confidence interval [CI]: 0.970–0.989), acute kidney injury (OR: 4.787, 95% CI: 1.674–13.693), norepinephrine dose (OR: 1.706, 95% CI: 1.375–2.117), and abdominopelvic cavity infection (OR: 0.257, 95% CI: 0.076–0.866) were significantly associated with mortality within 28 days after admission in patients with sepsis-related myocardial injury.

Conclusions

Patients with sepsis-related myocardial injury have a high mortality rate. A high oxygenation index, occurrence of acute kidney injury, high norepinephrine dose, and occurrence of abdominopelvic cavity infection are independent risk factors for 28-day mortality in patients with sepsis-related myocardial injury.

Predictive value of stress hyperglycemia ratio for the occurrence of acute kidney injury in acute myocardial infarction patients with diabetes

Background

Acute hyperglycemia has been recognized as a robust predictor for occurrence of acute kidney injury (AKI) in nondiabetic patients with acute myocardial infarction (AMI), however, its discriminatory ability for AKI is unclear in diabetic patients after an AMI. Here, we investigated whether stress hyperglycemia ratio (SHR), a novel index with the combined evaluation of acute and chronic glycemic levels, may have a better predictive value of AKI as compared with admission glycemia alone in diabetic patients following AMI.

Methods

SHR was calculated with admission blood glucose (ABG) divided by the glycated hemoglobin-derived estimated average glucose. A total of 1215 diabetic patients with AMI were enrolled and divided according to SHR tertiles. Baseline characteristics and outcomes were compared. The primary endpoint was AKI and secondary endpoints included all-cause death and cardiogenic shock during hospitalization. The logistic regression analysis was performed to identify potential risk factors. Accuracy was defined with area under the curve (AUC) by a receiver-operating characteristic (ROC) curve analysis.

Results

In AMI patients with diabetes, the incidence of AKI (4.4%, 7.8%, 13.0%; p < 0.001), all-cause death (2.7%, 3.6%, 6.4%; p = 0.027) and cardiogenic shock (4.9%, 7.6%, 11.6%; p = 0.002) all increased with the rising tertile levels of SHR. After multivariate adjustment, elevated SHR was significantly associated with an increased risk of AKI (odds ratio 3.18, 95% confidence interval: 1.99–5.09, p < 0.001) while ABG was no longer a risk factor of AKI. The SHR was also strongly related to the AKI risk in subgroups of patients. At ROC analysis, SHR accurately predicted AKI in overall (AUC 0.64) and a risk model consisted of SHR, left ventricular ejection fraction, N-terminal B-type natriuretic peptide, and estimated glomerular filtration rate (eGFR) yielded a superior predictive value (AUC 0.83) for AKI.

Conclusion

The novel index SHR is a better predictor of AKI and in-hospital mortality and morbidity than admission glycemia in AMI patients with diabetes.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12872-021-01962-2.

Myocardial Injury Promotes Matrix Metalloproteinase-9 Activity in the Renal Cortex in Preclinical Models of Acute Myocardial Infarction

New mechanistic insight into how the kidney responds to cardiac injury during acute myocardial infarction (AMI) is required. We hypothesized that AMI promotes inflammation and matrix metalloproteinase-9 (MMP9) activity in the kidney and studied the effect of initiating an Impella CP or veno-arterial extracorporeal membrane oxygenation (VA-ECMO) before coronary reperfusion during AMI. Adult male swine were subjected to coronary occlusion and either reperfusion (ischemia-reperfusion; IR) or support with either Impella or VA-ECMO before reperfusion. IR and ECMO increased while Impella reduced levels of MMP-9 in the myocardial infarct zone, circulation, and renal cortex. Compared to IR, Impella reduced myocardial infarct size and urinary KIM-1 levels, but VA-ECMO did not. IR and VA-ECMO increased pro-fibrogenic signaling via transforming growth factor-beta and endoglin in the renal cortex, but Impella did not. These findings identify that AMI increases inflammatory activity in the kidney, which may be attenuated by Impella support.

A prospective cohort study of acute kidney injury and kidney outcomes, cardiovascular events, and death

Acute kidney injury (AKI) has been reported to be associated with excess risks of death, kidney disease progression and cardiovascular events although previous studies have important limitations. To further examine this, we prospectively studied adults from four clinical centers surviving three months and more after hospitalization with or without AKI who were matched on center, pre-admission CKD status, and an integrated priority score based on age, prior cardiovascular disease or diabetes mellitus, preadmission estimated glomerular filtration rate (eGFR) and treatment in the intensive care unit during the index hospitalization between December 2009-February 2015, with follow-up through November 2018. All participants had assessments of kidney function before (eGFR) and at three months and annually (eGFR and proteinuria) after the index hospitalization. Associations of AKI with outcomes were examined after accounting for pre-admission and three-month post-discharge factors. Among 769 AKI (73% Stage 1, 14% Stage 2, 13% Stage 3) and 769 matched non-AKI adults, AKI was associated with higher adjusted rates of incident CKD (adjusted hazard ratio 3.98, 95% confidence interval 2.51-6.31), CKD progression (2.37,1.28-4.39), heart failure events (1.68, 1.22-2.31) and all-cause death (1.78, 1.24-2.56). AKI was not associated with major atherosclerotic cardiovascular events in multivariable analysis (0.95, 0.70-1.28). After accounting for degree of kidney function recovery and proteinuria at three months after discharge, the associations of AKI with heart failure (1.13, 0.80-1.61) and death (1.29, 0.84-1.98) were attenuated and no longer significant. Thus, assessing kidney function recovery and proteinuria status three months after AKI provides important prognostic information for long-term clinical outcomes.

Machine Learning to Predict Contrast-Induced Acute Kidney Injury in Patients With Acute Myocardial Infarction

Objective: To develop predictive models for contrast induced acute kidney injury (CI-AKI) among acute myocardial infarction (AMI) patients treated invasively.

Methods: Patients with AMI who underwent angiography therapy were enrolled and randomly divided into training cohort (75%) and validation cohort (25%). Machine learning algorithms were used to construct predictive models for CI-AKI. The predictive models were tested in a validation cohort.

Results: A total of 1,495 patients with AMI were included. Of all the patients, 226 (15.1%) cases developed CI-AKI. In the validation cohort, Random Forest (RF) model with top 15 variables reached an area under the curve (AUC) of 0.82 (95% CI: 0.76–0.87), while the best logistic model had an AUC of 0.69 (95% CI: 0.62–0.76). ACEF (age, creatinine, and ejection fraction) model reached an AUC of 0.62 (95% CI: 0.53–0.71). RF model with top 15 variables achieved a high recall rate of 71.9% and an accuracy of 73.5% in the validation group. Random Forest model significantly outperformed logistic regression in every comparison.

Conclusions: Machine learning algorithms especially Random Forest algorithm improves the accuracy of risk stratifying patients with AMI and should be used to accurately identify the risk of CI-AKI in AMI patients.

A comparison between different definitions of contrast-induced acute kidney injury for long-term mortality in patients with acute myocardial infarction

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CI-AKI is associated with prognosis in AMI patients irrespective of its definitions.

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CI-AKI_C (Scr elevation ≥ 25% in the first 72 h) had the highest prevalence (18.77%)

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CI-AKI_A (Scr elevation ≥ 50%/ ≥0.3 mg/dL in the first 72 h) had the highest PAR.

Background

Few studies have demonstrated the association between contrast-induced acute kidney injury (CI-AKI) and long-term mortality and explored which definition of CI-AKI accounts for most long-term deaths among patients with acute myocardial infarction (AMI). Therefore, we aimed to evaluate this association and compared the population attributable risks (PARs) of three CI-AKI definitions.

Methods

We analyzed 1300 consecutive AMI patients undergoing angiography in Guangdong Provincial People‘s Hospital. The endpoint was all-cause mortality. CI-AKI was evaluated according to three definitions: (1) CI-AKI_A, with a serum creatinine elevation ≥ 50% or ≥ 0.3 mg/dL from baseline in the first 72 h after procedure; (2) CI-AKI_B, ≥ 0.5 mg/dL in 72 h; (3) CI-AKI_C: ≥ 25% in 72 h; multivariable Cox analysis was conducted to evaluate the association between CI-AKI and long-term mortality. PARs of CI-AKI under different definitions were calculated with their odds ratios and prevalence among our cohort.

Results

During the median follow-up period of 7.0 (5.5; 8.7) years, CI-AKI was significantly associated with poorer outcome regardless of the definition (adjusted hazard ratios: 1.417–2.711). Among the three definitions of CI-AKI, the prevalence was the highest for CI-AKI_C (18.77%), and PAR was the highest for CI-AKI_A (11.62%, 95% CI: 4.99–19.71), followed by CI-AKI_B (9.20%, 95% CI: 4.22–16.00) and CI-AKI_C (7.26%, 95% CI: 0.21–15.62).

Conclusions

Our results suggested that CI-AKI is associated with long-term mortality in patients with AMI irrespective of its definitions. Cardiologists and studies regarding long-term prognosis should pay more attention to the presence of CI-AKI, especially CI-AKI_A with the highest PAR.

Application of 17 Contrast-Induced Acute Kidney Injury Risk Prediction Models

INTRODUCTION

Contrast-induced acute kidney injury (CI-AKI) is a frequent complication of percutaneous coronary interventions (PCI). Various groups have developed and validated risk scores for CI-AKI. Although the majority of these risk scores achieve an adequate accuracy, their usability in clinical practice is limited and greatly debated.

OBJECTIVE

With the present study, we aimed to prospectively assess the diagnostic performance of recently published CI-AKI risk scores (up to 2018) in a cohort of patients undergoing PCI.

METHODS

We enrolled 1,247 consecutive patients (80% men, mean age 62 ± 10 years) treated with elective or urgent PCI. For each patient, we calculated the individual CI-AKI risk score based on 17 different risk models. CI-AKI was defined as an increase of ≥25% (liberal) or ≥0.5 mg/dL (strict) in pre-PCI serum creatinine 48 h after PCI.

RESULTS

CI-AKI definition and, therefore, CI-AKI incidence have a significant impact on risk model performance (median negative predictive value increased from 85 to 99%; median c-statistic increased from 0.516 to 0.603 using more strict definition criteria). All of the 17 published models were characterized by a weak-to-moderate discriminating ability mainly based on the identification of "true-negative" cases (median positive predictive value 19% with liberal criterion and 3% with strict criterion). In none of the models, c-statistic was >0.800 with either CI-AKI definition. Novel, different combinations of the >35 independent variables used in the published models either by down- or by up-scaling did not result in significant improvement in predictive performance.

CONCLUSIONS

The predictive ability of all models was similar and only modest, derived mainly by identifying true-negative cases. A new approach is probably needed by adding novel markers or periprocedural characteristics.

Dietary omega-3 PUFA improved tubular function after ischemia induced acute kidney injury in mice but did not attenuate impairment of renal function

BACKGROUND

Acute kidney injury (AKI) is an important complication after major surgery and solid organ transplantation. Here, we present a dietary omega-3 polyunsaturated fatty acid (n3-PUFA) supplementation study to investigate whether pre-treatment can reduce ischemia induced AKI in mice.

METHODS

Male 12-14 week old C57BL/6 J mice received a linoleic acid rich sunflower oil based standard diet containing 10 % fat (STD) or the same diet enriched with n3-PUFA (containing 1 % EPA and 1 % DHA) (STD + n3). After 14 days of feeding bilateral 30 min renal ischemia reperfusion injury (IRI) was conducted to induce AKI and mice were sacrificed at 24 h. Serum creatinine and blood urea nitrogen (BUN) as well as liver enzyme elevation were measured. Kidney damage was analyzed by histology and immunohistochemistry. Furthermore, pro-inflammatory cytokines (IL-6, MCP-1) were determined by qPCR. FA and oxylipin pattern were quantified in blood and kidneys by GC-FID and LC-MS/MS, respectively.

RESULTS

n3-PUFA supplementation prior to renal IRI increased systemic and renal levels of n3-PUFA. Consistently, eicosanoids and other oxylipins derived from n3-PUFA including precursors of specialized pro-resolving mediators were elevated while n6-PUFA derived mediators such as pro-inflammatory prostaglandins were decreased. Feeding of n3-PUFA did not attenuate renal function impairment, morphological renal damage and inflammation characterized by IL-6 and MCP-1 elevation or neutrophil infiltration. However, the tubular transport marker alpha-1 microglobulin (A1M) was significantly higher expressed in proximal tubular epithelial cells of STD + n3 compared to STD fed mice. This indicates a better integrity of proximal tubular epithelial cells and thus significant protection of tubular function. In addition, heme oxygenase-1 (HO-1) which protects tubular function was also up-regulated in the treatment group receiving n3-PUFA supplemented chow.

DISCUSSION

We showed that n3-PUFA pre-treatment did not affect overall renal function or renal inflammation in a mouse model of moderate ischemia induced AKI, but tubular transport was improved. In conclusion, dietary n3-PUFA supplementation altered the oxylipin levels significantly but did not protect from renal function deterioration or attenuate ischemia induced renal inflammation.