Acute kidney injury is a risk factor for subsequent proteinuria

Urinary Cytokeratin 20 as a Biomarker for AKI-CKD Transition among Patients with Acute Decompensated Heart Failure and Acute Kidney Injury

Key Points

Background

Predicting the risk of AKI-CKD transition remains a major challenge in the management of acute decompensated heart failure (ADHF) and AKI. This study investigated the clinical utility of urinary cytokeratin 20 (CK20), a novel biomarker reflecting the severity of histological acute tubular injury, for identifying patients at risk of AKI-to-CKD progression.

Methods

This prospective cohort study included a test set comprising 279 consecutive hospitalized patients with ADHF and AKI in five centers and a validation set enrolling 206 similar patients at an external center. Urinary CK20 and seven reported renal tubular injury biomarkers at the time of AKI diagnosis were measured. The primary outcome was a composite of AKI-CKD transition 90 days after AKI or all-cause death within 90 days. The secondary outcome was AKI-to-CKD progression 90 days after AKI.

Results

In the test set, 115 patients (41%) reached the primary end point. Concentrations of urinary CK20 peaked on the day of AKI diagnosis and remained elevated 14 days after AKI. After multivariable adjustment, the highest tertile of urinary CK20 was associated with 21-fold higher risk of the primary outcome and 29-fold higher risk of the secondary outcome. For predicting the primary and secondary outcomes, urinary CK20 at the time of AKI diagnosis had an area under the receiver operating characteristic curve of 0.82 (95% confidence interval [CI], 0.77 to 0.87) and 0.81 (95% CI, 0.75 to 0.87), respectively, and outperformed other reported biomarkers reflecting acute tubular injury and risk of CKD. Adding urinary CK20 to the clinical variables improved the ability for predicting the primary outcome with an area under the receiver operating characteristic curve of 0.90 (95% CI, 0.85 to 0.94) and largely improved risk reclassification. The ability of urinary CK20 in predicting AKI-CKD transition was further confirmed in the validation set.

Conclusions

Urinary CK20 improved prediction of the risk of transition from AKI to CKD in patients with ADHF and AKI.

Comparison of the nephroprotective effect of [6]-gingerol and the [6]-gingerol-β-cyclodextrin complex against cisplatin-induced AKI

Cisplatin is an antineoplastic agent effective for the treatment of several cancers. However, due to its nephrotoxicity, its use is limited. Acute kidney injury (AKI) induced by cisplatin is caused by inflammation, apoptosis, and oxidative stress in renal tubular cells. Natural compounds derived from ginger (Zingiber officinale) such as [6]-gingerol, possess anti-inflammatory and antioxidant properties. This study explores the protective effects of [6]-gingerol and its β-cyclodextrin complex ([6]-gingerol-β-CD) on cisplatin-induced AKI in mice. We hypothesize that complexing [6]-gingerol with β-cyclodextrin would enhance its solubility and reduce its pungency, making it more suitable for clinical use. Additionally, we aim to determine whether β-cyclodextrin complexation can improve the oral bioavailability of [6]-gingerol without compromising its therapeutic efficacy. The minimum dose of cisplatin required to induce AKI was determined to be 15 mg/kg. Female Swiss mice (n = 6-8) were divided into four groups: control, cisplatin (15 mg/kg), [6]-gingerol (12.5 mg/kg), and [6]-gingerol-β-CD (12.5 mg/kg). The treatments were administered orally for 5 days. On the third day, cisplatin was administered intraperitoneally (i.p.), and the animals were euthanized after 5 days. All biochemical parameters investigated, such as plasma urea and creatinine, urinary gamma GT, urinary protein, MPO, and GSH were altered by cisplatin. The parameters evaluated in this study were categorized into renal function, inflammation, and oxidative stress. Both [6]-gingerol and complexed gingerol effectively restored most of the evaluated parameters to control levels. Following these analyses, we investigated the JAK/STAT pathway and observed that gingerol deactivates this pathway, thereby preventing cisplatin-induced nephrotoxicity. In conclusion, β-CD complexation did not interfere with [6]-gingerol therapeutic, emphasizing its indication for future clinical tests. Further analysis showed that [6]-gingerol prevented cisplatin nephrotoxicity by deactivating JAK/STAT signaling pathway.

Acute kidney injury

Acute kidney injury (AKI) is a common, heterogeneous, multifactorial condition, which is part of the overarching syndrome of acute kidney diseases and disorders. This condition's incidence highest in low-income and middle-income countries. In the short term, AKI is associated with increased mortality, an increased risk of complications, extended stays in hospital, and high health-care costs. Long-term complications include chronic kidney disease, kidney failure, cardiovascular morbidity, and an increased risk of death. Several strategies are available to prevent and treat AKI in specific clinical contexts. Otherwise, AKI care is primarily supportive, focused on treatment of the underlying cause, prevention of further injury, management of complications, and short-term renal replacement therapy in case of refractory complications. Evidence confirming that AKI subphenotyping is necessary to identify precision-oriented interventions is growing. Long-term follow-up of individuals recovered from AKI is recommended but the most effective models of care remain unclear.

ATP dynamics as a predictor of future podocyte structure and function after acute ischemic kidney injury in female mice

Acute kidney injury (AKI), typically caused by ischemia, is a common clinical complication with a poor prognosis. Although proteinuria is an important prognostic indicator of AKI, the underlying causal mechanism remains unclear. In vitro studies suggest that podocytes have high ATP demands to maintain their structure and function, however, analyzing their ATP dynamics in living kidneys has been technically challenging. Here, using intravital imaging to visualize a FRET-based ATP biosensor expressed systemically in female mice due to their suitability for glomerular imaging, we monitor the in vivo ATP dynamics in podocytes during ischemia reperfusion injury. ATP levels decrease during ischemia, but recover after reperfusion in podocytes, exhibiting better recovery than in glomerular endothelial cells. However, prolonged ischemia results in insufficient ATP recovery in podocytes, which is inversely correlated with mitochondrial fragmentation and foot process effacement during the chronic phase. Furthermore, preventing mitochondrial fission via pharmacological inhibition ameliorates podocyte injury in vitro, ex vivo, and in vivo. Thus, these findings provide several insights into how ATP depletion and mitochondrial fragmentation contribute to podocyte injury after ischemic AKI and could potentially be therapeutic targets.

Advancing Protein Detection and Analysis Based on Ag/Au PHCN for Enhanced SERS Sensitivity and Specificity in Biomolecular Diagnostics

In the realm of disease diagnostics, particularly for conditions such as proteinuria and hemoglobinuria, the quest for a method that combines accurate, label-free detection of protein compositions and their conformational changes remains a formidable challenge. In this study, we introduce an innovative Ag/Au plasmonic hybrid coupling nanoarray (Ag/Au PHCN) architecture marked by sub-10 nm interparticle gaps. These nanoarrays, leveraging plasmonic hybrid coupling and synergistic enhancement mechanisms, create a plethora of uniform surface-enhanced Raman spectroscopy (SERS) hotspots. The Ag/Au PHCN substrates demonstrated unparalleled sensitivity in the unmarked detection of hemoglobin (HGB), bovine serum albumin (BSA), and cytochrome C (Cyt.C) in bodily fluids, incorporating the advantages of high sensitivity, high reproducibility, durability, recyclability, and biocompatibility. Notably, the detection limits for BSA and HGB are unprecedented at 0.5 and 5 ng/mL, respectively. This achievement sets a new benchmark for label-free protein detection using two-dimensional nanostructures. Crucially, the Ag/Au PHCNs possess the novel capability to discern protein conformational changes post denaturation, underscoring their potential in probing protein functionalities. Most importantly, these nanoarrays can differentiate between normal and proteinuria-affected urine samples and monitor protein content variations over time, heralding a new era in clinical diagnostics with particular relevance to proteinuria and hemoglobinuria detection.

Outcomes after acute kidney injury and critical illness

PURPOSE OF REVIEW

Acute kidney injury (AKI) in critical illness is common, and survivors are faced with a host of adverse outcomes. In this article, we review the current landscape of outcomes and care in survivors of AKI and critical illness.

RECENT FINDINGS

Follow-up care of survivors of AKI and critical illness is prudent to monitor for and mitigate the risk of adverse outcomes. Observational data have suggested improvement in outcomes with nephrology-based follow-up care, and recent interventional studies demonstrate similar findings. However, current post-AKI care is suboptimal with various challenges, such as breakdowns in the transition of care during hospital episodes and into the community, barriers for patients in follow-up, and lack of identification of high-risk patients for nephrology-based follow-up. Tools predictive of renal nonrecovery and long-term outcomes may help to identify high-risk patients who may benefit the most from nephrology-based care post-AKI.

SUMMARY

Follow-up care of survivors of AKI and critical illness may improve outcomes and there is a need to prioritize transitions of care into the community. Further research is needed to elucidate the best ways to risk-stratify and manage post-AKI survivors to improve outcomes.

Risk Prediction Models for Renal Function Decline After Cardiac Surgery Within Different Preoperative Glomerular Filtration Rate Strata

BACKGROUND

Our goal was to create a simple risk-prediction model for renal function decline after cardiac surgery to help focus renal follow-up efforts on patients most likely to benefit.

METHODS AND RESULTS

This single-center retrospective cohort study enrolled 24 904 patients who underwent cardiac surgery from 2012 to 2019 at Fuwai Hospital, Beijing, China. An estimated glomerular filtration rate (eGFR) reduction of ≥30% 3 months after surgery was considered evidence of renal function decline. Relative to patients with eGFR 60 to 89 mL/min per 1.73 m2 (4.5% [531/11733]), those with eGFR ≥90 mL/min per 1.73 m2 (10.9% [1200/11042]) had a higher risk of renal function decline, whereas those with eGFR ≤59 mL/min per 1.73 m2 (5.8% [124/2129]) did not. Each eGFR stratum had a different strongest contributor to renal function decline: increased baseline eGFR levels for patients with eGFR ≥90 mL/min per 1.73 m2, transfusion of any blood type for patients with eGFR 60 to 89 mL/min per 1.73 m2, and no recovery of renal function at discharge for patients with eGFR ≤59 mL/min per 1.73 m2. Different nomograms were established for the different eGFR strata, which yielded a corrected C-index value of 0.752 for eGFR ≥90 mL/min per 1.73 m2, 0.725 for eGFR 60-89 mL/min per 1.73 m2 and 0.791 for eGFR ≤59 mL/min per 1.73 m2.

CONCLUSIONS

Predictors of renal function decline over the follow-up showed marked differences across the eGFR strata. The nomograms incorporated a small number of variables that are readily available in the routine cardiac surgical setting and can be used to predict renal function decline in patients stratified by baseline eGFR.

Biomarkers in Contrast-Induced Acute Kidney Injury: Towards A New Perspective

Contrast-Induced Acute Kidney Injury (CI-AKI) remains a frequent iatrogenic condition since radiological procedures using intra-vascular iodinated contrast media (CM) are being widely administered for diagnostic and therapeutic purposes. Despite the improvement of the medical healthcare system worldwide, CI-AKI is still associated with direct short-term and indirect long-term outcomes including increased morbidity and mortality, especially in patients with underlying pre-existing renal function impairment, cardiovascular disease, or diabetes that could rapidly progress into Chronic Kidney Disease. Although the RIFLE (Risk, Injury, Failure, Loss, End-Stage Kidney Disease), AKIN (Acute Kidney Injury Network), and KDIGO (Kidney Disease Improving Global Outcomes) clinical criteria and recommendation guidelines are based on traditional "gold standard" biomarkers known as serum creatinine, glomerular filtration rate, and urinary output, new reliable serum and urinary biomarkers are still needed for an effective unified diagnostic strategy for AKI. Starting from previous and recent publications on the benefits and limitations of validated biomarkers responding to kidney injury, glomerular filtration, and inflammation among others, this review unravels the role of new emerging biomarkers used alone or in combination as reliable tools for early diagnosis and prognosis of CI-AKI, taking into account patients and procedures-risk factors towards a new clinical perspective.

Septic acute kidney injury and gut microbiome: Should we change our approach?

Incidence of acute kidney injury (AKI) remained relatively stable over the last decade and the adjusted risks for it and mortality are similar across different continents and regions. Also, the mortality of septic-AKI can reach 70% in critically-ill patients. These sole facts can give rise to a question: is there something we do not understand yet? Currently, there are no specific therapies for septic AKI and the treatment aims only to maintain the mean arterial pressure over 65mmHg by ensuring a good fluid resuscitation and by using vasopressors, along with antibiotics. On the other hand, there is an increased concern about the different hemodynamic changes in septic AKI versus other forms and the link between the gut microbiome and the severity of septic AKI. Fortunately, progress has been made in the form of administration of pre- and probiotics, short chain fatty acids (SCFA), especially acetate, and also broad-spectrum antibiotics or selective decontaminants of the digestive tract in a successful attempt to modulate the microbial flora and to decrease both the severity of AKI and mortality. In conclusion, septic-AKI is a severe form of kidney injury, with particular hemodynamic changes and with a strong link between the kidney and the gut microbiome. By modulating the immune response we could not only treat but also prevent severe forms. The most difficult part is to categorize patients and to better understand the key mechanisms of inflammation and cellular adaptation to the injury, as these mechanisms can serve in the future as target therapies.

Epidemiology and outcomes of post-AKI proteinuria

Background

Acute kidney injury (AKI) has been associated with increased risks of new-onset and worsening proteinuria. However, epidemiologic data for post-AKI proteinuria was still lacking. This study aimed to determine the incidence, risk factors and clinical correlations of post-AKI proteinuria among hospitalized patients.

Methods

This study was conducted in a multicenter cohort including patients aged 18-100 years with hospital-acquired AKI (HA-AKI) hospitalized at 19 medical centers throughout China. The primary outcome was the incidence of post-AKI proteinuria. Secondary outcomes included AKI recovery and kidney disease progression. The results of both quantitative and qualitative urinary protein tests were used to define post-AKI proteinuria. Cox proportional hazard model with stepwise regression was used to determine the risk factors for post-AKI proteinuria.

Results

Of 6206 HA-AKI patients without proteinuria at baseline, 2102 (33.9%) had new-onset proteinuria, whereas of 5137 HA-AKI with baseline proteinuria, 894 (17.4%) had worsening proteinuria after AKI. Higher AKI stage and preexisting CKD diagnosis were risk factors for new-onset proteinuria and worsening proteinuria, whereas treatment with renin-angiotensin system inhibitors was associated with an 11% lower risk of incident proteinuria. About 60% and 75% of patients with post-AKI new-onset and worsening proteinuria, respectively, recovered within 3 months. Worsening proteinuria was associated with a lower incidence of AKI recovery and a higher risk of kidney disease progression.

Conclusions

Post-AKI proteinuria is common and usually transient among hospitalized patients. The risk profiles for new-onset and worsening post-AKI proteinuria differed markedly. Worsening proteinuria after AKI was associated with adverse kidney outcomes, which emphasized the need for close monitoring of proteinuria after AKI.

A Retrospective Study on Clinical Outcomes of Pregnancy-Related Acute Kidney Injury Patients at a South Indian Tertiary Care Hospital

Introduction Acute kidney injury (AKI) significantly contributes to maternal morbidity and mortality in developing nations. In a retrospective study conducted at our tertiary care center in collaboration between the Department of Nephrology and the Department of Obstetrics and Gynecology, we investigated patients admitted with pregnancy-related acute kidney injury (PR-AKI) under the following parameters: incidence, etiology, and maternal outcomes. Methods We evaluated 70 patients admitted with PR-AKI from May 2016 to August 2020. A thorough evaluation was carried out for these patients. The results were analyzed for the association of mortality with the etiology of PR-AKI and the dialysis requirement. Results The mean age among the PR-AKI patients was 24.56 ± 4.2 years. During the study period, there were 33,403 deliveries, consisting of 20,126 vaginal deliveries, and 13,277 were performed via a lower segment cesarean section (LSCS). Seventy patients developed AKI, with an incidence of 2.9 per 1,000 deliveries. The various etiologies included sepsis in 54 cases (74.3%), preeclampsia/eclampsia in 44 (62.85%), LSCS in 27 (38.6%), abruptio placentae in 11 (15.7%), postpartum hemorrhage (PPH) in 11 (15.7%), post-abortion in eight (11.4%), and hemolysis, elevated liver enzymes, and low platelets (HELLP) syndrome in seven (10.46%). The number of patients in various stages of AKI was noted as one in Stage I, 22 in Stage II, and 47 in Stage III. The odds ratio of death in the abruptio placentae was 0.73 (95% CI: 0.08-6.72), whereas among those with PPH, it was 1.96 (95% CI: 0.34-11.29). The odds ratio of death among patients with LSCS was 0.50 (95% CI: 0.09-2.64). Out of the total, 34 patients (48.6%) required renal replacement therapy (RRT) provided as intermittent hemodialysis. In total, there were eight deaths (11.3%). The odds ratio of death in dialysis patients was 1.89 (95% CI: 0.42-8.54). Perinatal mortality was 32.9%, whereas total perinatal mortality among all patients was 3.5%. The odds ratio of perinatal mortality among those with AKI was 13.29 (95% CI: 8.05-21.96) with p < 0.0001. Conclusion Our study demonstrates that sepsis was the most common cause of PR-AKI, which can be attributed to a lack of antenatal and postnatal care. Other causes included preeclampsia, LSCS, and hemorrhage. The present study also shows that a significant association exists between PR-AKI and perinatal mortality. The requirement of RRT in AKI predicts a less favorable prognosis.

Renin-Angiotensin-Aldosterone System Blockade after AKI with or without Recovery among US Veterans with Diabetic Kidney Disease

SIGNIFICANCE STATEMENT

Among patients with CKD, optimal use of angiotensin-converting enzyme inhibitors or angiotensin II receptor blockers after AKI is uncertain. Despite these medications' ability to reduce risk of mortality and other adverse outcomes, there is concern that ACEi/ARB use may delay recovery of kidney function or precipitate recurrent AKI. Prior studies have provided conflicting data regarding the optimal timing of these medications after AKI and have not addressed the role of kidney recovery in determining appropriate timing. This study in US Veterans with diabetes mellitus and proteinuria demonstrated an association between ACEi/ARB use and lower mortality. This association was more pronounced with earlier post-AKI ACEi/ARB use and was not meaningfully affected by initiating ACEis/ARBs before versus after recovery from AKI.

BACKGROUND

Optimal use of angiotensin-converting enzyme inhibitors (ACEis) or angiotensin II receptor blockers (ARBs) after AKI is uncertain.

METHODS

Using data derived from electronic medical records, we sought to estimate the association between ACEi/ARB use after AKI and mortality in US military Veterans with indications for such treatment (diabetes and proteinuria) while accounting for AKI recovery. We used ACEi/ARB treatment after hospitalization with AKI (defined as serum creatinine ≥50% above baseline concentration) as a time-varying exposure in Cox models. The outcome was all-cause mortality. Recovery was defined as return to ≤110% of baseline creatinine. A secondary analysis focused on ACEi/ARB use relative to AKI recovery (before versus after).

RESULTS

Among 54,735 Veterans with AKI, 31,146 deaths occurred over a median follow-up period of 2.3 years. Approximately 57% received an ACEi/ARB <3 months after hospitalization. In multivariate analysis with time-varying recovery, post-AKI ACEi/ARB use was associated with lower risk of mortality (adjusted hazard ratio [aHR], 0.74; 95% confidence interval [CI], 0.72 to 0.77). The association between ACEi/ARB use and mortality varied over time, with lower mortality risk associated with earlier initiation ( P for interaction with time <0.001). In secondary analysis, compared with those with neither recovery nor ACEi/ARB use, risk of mortality was lower in those with recovery without ACEi/ARB use (aHR, 0.90; 95% CI, 0.87 to 0.94), those without recovery with ACEi/ARB use (aHR, 0.69; 95% CI, 0.66 to 0.72), and those with ACEi/ARB use after recovery (aHR, 0.70; 95% CI, 0.67 to 0.73).

CONCLUSIONS

This study demonstrated lower mortality associated with ACEi/ARB use in Veterans with diabetes, proteinuria, and AKI, regardless of recovery. Results favored earlier ACEi/ARB initiation.

Risk of de novo proteinuria following hospitalization with acute kidney injury

BACKGROUND

Acute Kidney Injury (AKI) incidence has continued to rise and is recognized as a major risk factor for kidney disease progression and cardiovascular complications. Early recognition of factors associated with post-AKI complications is fundamental to stratifying patients that could benefit from closer follow-up and management after an episode of AKI. Recent studies have shown that proteinuria is a prevalent sequela after AKI and a strong predictor of complications post-AKI. This study aims to evaluate the frequency and timing of the development of de-novo proteinuria after an AKI episode in patients with known kidney function and no prior history of proteinuria.

METHODS

We retrospectively analyzed data from adult AKI patients with pre- and post-kidney function information between Jan 2014 and March 2019. The presence of proteinuria determined before and after index AKI encounter was based on ICD-10 code and/or urine dipstick and UPCR during the follow-up period.

RESULTS

Of 9697 admissions with AKI diagnoses between Jan 2014 and March 2019, 2120 eligible patients with at least one assessment of Scr and proteinuria before AKI index admission were included in the analysis. The median age was 64 (IQR 54-75) years, and 57% were male. 58% (n-1712) patients had stage 1 AKI, 19% (n = 567) stage 2 AKI, and 22% (n = 650) developed stage 3 AKI. De novo proteinúria was found in 62% (n = 472) of patients and was already present by 90 days post-AKI in 59% (209/354). After adjusting for age and comorbidities, severe AKI (stage 2/3 AKI) and diabetes, were independently associated with increased risk for De novo proteinuria.

CONCLUSION

Severe AKI is an independent risk factor for subsequent de novo proteinuria post-hospitalization. Further prospective studies are needed to determine whether strategies to detect AKI patients at risk of proteinuria and early therapeutics to modify proteinuria can delay the progression of kidney disease.

Acute kidney injury and distant organ dysfunction-network system analysis

Acute kidney injury (AKI) occurs in about half of critically ill patients and associates with high in-hospital mortality, increased long-term mortality post-discharge and subsequent progression to chronic kidney disease. Numerous clinical studies have shown that AKI is often complicated by dysfunction of distant organs, which is a cause of the high mortality associated with AKI. Experimental studies have elucidated many mechanisms of AKI-induced distant organ injury, which include inflammatory cytokines, oxidative stress and immune responses. This review will provide an update on evidence of organ crosstalk and potential therapeutics for AKI-induced organ injuries, and present the new concept of a systemic organ network to balance homeostasis and inflammation that goes beyond kidney-crosstalk with a single distant organ.

The protective effects of SGLT-2 inhibitors, GLP-1 receptor agonists, and RAAS blockers against renal injury in patients with type 2 diabetes

Diabetic kidney disease is one of the most severe complications of type 2 diabetes mellitus. Patients with diabetic kidney disease have a worse prognosis in terms of mortality and morbidity, compared with patients who have diabetes alone. Strict control of blood pressure and blood glucose is the primary method for prevention of initial kidney damage and delaying further progression of existing damage. Other management approaches include the use of exogenous drugs that can effectively protect the kidneys from diabetes, such as sodium-glucose transporter 2 inhibitors, glucagon-like peptide-1 receptor agonists, and renin-angiotensin-aldosterone system blockers. These drugs may protect against kidney injury through various molecular mechanisms. This review focuses on renal impairment in patients with type 2 diabetes; it discusses the direct and indirect effects of sodium-glucose transporter 2 inhibitors, glucagon-like peptide-1 receptor agonists, and renin-angiotensin-aldosterone system blockers on diabetic kidney disease. Finally, it discusses the effects of combination treatment with two or three types of drugs in patients with chronic kidney disease.

Acute kidney injury increases risk of kidney stones-a retrospective propensity score matched cohort study

BACKGROUND

Acute kidney injury (AKI) is common. An episode of AKI may modify the risk of developing kidney stones by potential long-term effects on urine composition. We aimed to investigate the association between AKI and the risk of kidney stone presentations.

METHODS

The retrospective cohort study used patient data (1 January 2008-31 December 2017), from an Australian Local Health District, which included AKI diagnosis, demographics, comorbidities and kidney stone admissions. Time-varying Cox proportional hazards and propensity-matched analysis were used to determine the impact of AKI on the risk of kidney stones. To address possible population inhomogeneity in comparisons between no AKI and hospitalized AKI, sub-group analysis was done comparing inpatient and outpatient AKI versus no AKI, to assess consistency of association with future stones. Sensitivity analysis was undertaken to capture the impact of a known AKI status and AKI severity.

RESULTS

Out of 137 635 patients, 23 001 (17%) had an AKI diagnosis and 2295 (2%) had kidney stone presentations. In the unadjusted analysis, AKI was associated with kidney stones, with AKI used as a time-varying exposure, [hazard ratio (HR) 1.32, 95% confidence interval (CI) 1.16-1.50)]. Both inpatient-AKI (HR 1.19, 95% CI 1.01-1.39) and outpatient-AKI (HR 1.59, 95% CI 1.30-1.94) were significantly associated with future stones compared to no AKI subjects. This association persisted in the adjusted analysis (HR 1.45, 95% CI 1.26-1.66), propensity-matched dataset (HR 1.67, 95% CI 1.40-1.99) and sensitivity analysis. There was a dose-response relationship with higher stages of AKI being associated with a greater risk of kidney stones.

CONCLUSIONS

In a large cohort of patients, AKI is associated with a greater risk of kidney stones, which increases with higher stages of AKI. This association should be examined in other cohorts and populations for verification.

Long-Term Consequences of Acute Kidney Injury After Pediatric Cardiac Surgery: A Systematic Review

OBJECTIVE

The objective of this study was to evaluate the available data on long-term kidney dysfunction, hypertension, and mortality after cardiac surgery-associated acute kidney injury (AKI) in the pediatric population.

STUDY DESIGN

PubMed/MEDLINE, Embase, Scopus, and reference lists of relevant articles were searched for eligible studies published from inception through March 2022. Long-term outcomes after pediatric cardiac surgery complicated by AKI and those without were investigated.

RESULTS

We identified 14 studies published between 2013 and 2022 that included a total of 6701 patients (AKI: 1376 patients; no AKI: 5325 patients). These studies used different well-established classifications to define AKI. All the studies suggested that AKI after heart surgery is common in the pediatric patient population and reported a potential link between cardiac surgery-associated AKI and important clinical outcomes. However, only 4 out of 11 studies found a strong association between (absence of recovery from) cardiac surgery-associated AKI and risk of developing chronic kidney disease, and 3 out of 5 studies found a significant increase in mortality rates for pediatric patients who developed AKI after cardiac surgery. Only 1 out of 4 studies found an association between AKI and hypertension at 12 months postoperatively, but found no association at later follow-up times.

CONCLUSIONS

Although there is a trend, evidence on the long-term consequences of cardiac surgery-associated AKI in the pediatric population is mixed. Genetic syndromes, preexisting kidney disease, univentricular or cyanotic heart conditions, and/or high-complexity surgery may be more important for the development of kidney dysfunction by adolescence and early adulthood. Regardless, these children may benefit from a long-term kidney follow-up.

Pregnancy-related acute kidney injury in the African continent: where do we stand? A systematic review

BACKGROUND

Pregnancy-Related Acute kidney injury (PR-AKI) is a global health problem with substantial maternal and fetal morbidity and mortality. However, little is known about the current situation in the developing world including African countries. Africa is the poorest continent per capita, and women from Sub-Saharan Africa alone account for 66% of the estimated global maternal deaths from preventable obstetric causes.

METHODS

OBJECTIVE: To review the literature on the clinical profile, maternal and renal outcomes of women with PR-AKI in the African continent.

SEARCH STRATEGY

Medline, ISI Web of Science, Scopus, and Cochrane library were searched in February 2022, using the MeSH terms and text key words: "pregnancy", "pregnant", "acute kidney injury", "acute renal insufficiency", "acute renal injury", "acute renal failure", and "Africa".

SELECTION CRITERIA AND DATA COLLECTION

Studies from African countries which reported maternal and renal outcomes in women with PR-AKI during pregnancy or postpartum were included. Editorials, short communications, and case reports were excluded. The study quality was assessed using the NHLBI tool. Data extraction was done using predefined data fields.

RESULTS

A total of 167 studies were evaluated, of which 14 studies from seven African countries met the inclusion criteria. Preeclampsia, obstetric hemorrhage, and sepsis represented the main causes of PR-AKI. Maternal mortality ranged between 0 and 34.4%. Although the majority of women needed ICU admission and hemodialysis, renal recovery occurred in 53.1-90% of patients. Perinatal mortality has been reported to be 1.5-60.5% in the included studies.

AUTHORS' CONCLUSIONS

PR-AKI in Africa represents the second leading cause of AKI. Limited access to obstetric care, late referral, and late diagnosis of women with risks for PR-AKI hinder the curtailment of the problem. Provision of health care facilities with adequately trained personnel and implementation of preventive strategies will be of great value in decreasing the magnitude of the problem.

Localized periodontitis and kidney function for the risk of proteinuria in young adults in the CHIEF oral health study

This study aimed to investigate the association of localized periodontitis with proteinuria in 1281 military young adults in Taiwan. Localized periodontitis was classified as Healthy/Stage I (N = 928) or Stage II/III (N = 353). Stage 2 chronic kidney disease (CKD) was defined as an estimated glomerular filtration rate (eGFR) of 60-89 mL/min/1.73 m². Proteinuria was defined as protein levels of 2+ or 3+ on the dipstick test. Multiple logistic regression analysis with adjustments for age, sex, body mass index, remaining teeth number and other potential covariates were used to determine the association between localized Stage II/III periodontitis and dipstick proteinuria in patients with and without CKD. Localized stage II/III periodontitis was associated with a higher risk of dipstick proteinuria [odds ratio (OR) and 95% confidence interval: 1.89 (1.04-3.42)], but not with stage 2 CKD. However, the association between localized stage II/III periodontitis and dipstick proteinuria was observed only in patients with stage 2 CKD [OR: 3.80 (1.56-9.27)], while the association was null in participants without stage 2 CKD [OR: 1.02 (0.42-2.45)]. Our findings suggest that among young adults, especially those with a mildly impaired eGFR, localized periodontitis might contribute to acute or chronic kidney injury, which manifests as proteinuria.

Body, metabolic and renal changes following cross-sex estrogen/progestogen therapy in a rodent model simulating its use by transwomen

PURPOSE

The use of sex steroids by trans people has been of paramount importance regarding body changes during gender transition. The objective of this study was to assess the effects of an injectable steroid combination frequently used by transwomen, namely estradiol enanthate with dihydroxyprogesterone acetophenide (E2EN/DHPA), on blood pressure and metabolic outcomes using an animal model.

METHODS

Two-month-old male Wistar rats were orchiectomized or sham-operated and divided into groups: (1) Sham treated with sesame oil vehicle (SG), (2) sham treated with E2EN/DHPA (SP), (3) orchiectomized rats treated with vehicle (OG), and (4) orchiectomized rats treated with E2EN/DHPA (OP), with all groups treated every 10 days for 5 months. We evaluated systolic blood pressure (SBP), body weight (BW), abdominal circumference, nasoanal length (NAL), food and water intake (FI, WI), lipid profile (triglycerides, LDL, and HDL), serum C-reactive protein (CRP), plasma concentrations of urea (URpl) and creatinine (CRpl), 24 h urinary volume (V24 h), sodium and potassium excretion (UNa⁺, UK⁺), and proteinuria.

RESULTS

E2EN/DHPA administration reduced BW (SP 324.5 ± 31.1; OP 291.7 ± 41.3 g) and NAL (SP 24.5 ± 0.4; OP 24.6 ± 1.0 cm), without changing blood pressure, but increased URpl concentration (SP 55.0 ± 4.8; OP 42.5 ± 8.8 mg/dL) and CRpl (SP 0.47 ± 0.05; OP 0.46 ± 0.04 mg/dL), sodium (SP 3.1 ± 0.8; OP 3.3 ± 0.4 µEq/min/kg), potassium (SP 0.91 ± 0.22; OP 0.94 ± 0.22 µEq/min/kg) excretions and urinary volume (SP 15.5 ± 2.1; OP 16.4 ± 2.9 mL/24 h).

CONCLUSION

Cross-sex hormone therapy with E2EN/DHPA significantly modified body characteristics in male rats, producing a feminizing change without altering blood pressure or generating harmful metabolic parameters, but larger translational studies are still needed.

The Effects of Race on Acute Kidney Injury

Racial disparities in incidence and outcomes of acute kidney injury (AKI) are pervasive and are driven in part by social inequities and other factors. It is well-documented that Black patients face higher risk of AKI and seemingly have a survival advantage compared to White counterparts. Various explanations have been advanced and suggested to account for this, including differences in susceptibility to kidney injury, severity of illness, and socioeconomic factors. In this review, we try to understand and further explore the link between race and AKI using the incidence, diagnosis, and management of AKI to illustrate how race is directly related to AKI outcomes, with a focus on Black and White individuals with AKI. In particular, we explore the effect of race-adjusted estimated glomerular filtration rate (eGFR) equation on AKI prediction and discuss racial disparities in the management of AKI and how this might contribute to racial differences in AKI-related mortality among Blacks with AKI. We also identify some opportunities for future research and advocacy.

Pathophysiology of Acute Kidney Injury in Critical Illness: A Narrative Review

Acute kidney injury (AKI) is a syndrome that entails a rapid decline in kidney function with or without injury. The consequences of AKI among acutely ill patients are dire and lead to higher mortality, morbidity, and healthcare cost. To prevent AKI and its short and long-term repercussions, understanding its pathophysiology is essential. Depending on the baseline kidney histology and function reserves, the number of kidney insults, and the intensity of each insult, the clinical presentation of AKI may differ. While many factors are capable of inducing renal injury, they can be categorized into a few processes. The three primary processes reported in the literature are hemodynamic changes, inflammatory reactions, and nephrotoxicity. The majority of patients with AKI will suffer from more than one during their development and/or progression of AKI. Moreover, the development of one usually leads to the instigation of another. Thus, the interactions and progression between these mechanisms may determine the severity and duration of the AKI. Other factors such as organ crosstalk and how our concurrent therapies interact with these mechanisms complicate the pathophysiology of the progression of the AKI even further. In this narrative review article, we describe these three main pathophysiological processes that lead to the development and progression of AKI. © 2022 American Physiological Society. Compr Physiol 12: 1-14, 2022.

Acute kidney injury and risk of cardiovascular outcomes: A nationwide cohort study

BACKGROUND

Acute kidney injury (AKI) has been associated with cardiovascular disease, but this is sparsely studied in non-selected populations and with little attention to the effect in age and renal function. Using nationwide administrative data, we investigated the hypothesis of increased one-year risk of cardiovascular event or death associated with AKI.

METHODS

In a cohort study, we identified all admissions in Denmark between 2008 and 2018. AKI was defined as ≥1.5 times increase from baseline to peak creatinine during admission, or dialysis. We excluded patients with age <50 years, estimated glomerular filtration rate (eGFR) <15ml/min/1.73m², renal transplantation, index-admission due to cardiovascular disease or death during index-admission. The primary outcome was cardiovascular risk within one year from discharge, which was a composite of the secondary outcomes ischemic heart disease, heart failure or stroke. To estimate risks, we applied multiple logistic regression fitted by inverse probability of censoring weighting and stratified estimations by eGFR and age. We adjusted for proteinuria in the subcohort with measurements available.

RESULTS

Among 565,056 hospital admissions, 39,569 (7.0%) cases of AKI were present. In total, 18,642 patients sustained a cardiovascular outcome. AKI was significantly associated with cardiovascular outcome with an adjusted OR [CI] of 1.33 [1.16-1.53], 1.43 [1.33-1.54], 1.23 [1.14-1.34], 1.38 [1.18-1.62] for eGFR ≥90, 60-89, 30-59 and 15-29ml/min/1.73m², respectively. When omitting the outcome heart failure, these results were 1.24 [1.06-1.45], 1.22 [1.11-1.33], 1.05 [0.95-1.16], 1.25 [1.02-1.54]. Results did not change substantially in strata of age groups, in AKI stages and in the subcohort adjusted for proteinuria.

CONCLUSION

Non-selected patients aged 50 years or above with AKI during admission had significantly higher one-year risk of cardiovascular event or death, especially, but not only due to heart failure, independent of age and eGFR.

Perioperative albuminuria and clinical model to predict acute kidney injury in paediatric cardiac surgery

BACKGROUND

AKI is an important complication post cardiac surgery in children. An early diagnosis can help in mitigating complications and allow for prognostication. Urinary albumin:creatinine ratio (ACR) as a biomarker can provide a cheaper and more accessible AKI risk assessment and prediction. There is a paucity of paediatric literature regarding its utility.

METHODS

This was a prospective observational study, enrolling all children aged 1 month to 18 years, who underwent cardiac surgery, with use of cardiopulmonary bypass. Cohort was divided into groups < 2 years and ≥ 2 years for analyses to account for differences in physiological albumin excretion with age.

RESULTS

Of 143 children enrolled in the study, 36 developed AKI. In both age groups, the post-operative ACR was higher than pre-operative ACR among patients with and without AKI. In the group aged ≥ 2 years, the highest first post-operative ACR tertile (> 75.8 mg/g) predicted post-operative AKI after adjusting for clinical variables (adjusted RR, 11.71; 1.85-16.59). In the group aged < 2 years, the highest first post-operative ACR tertile (> 141.3 mg/g) predicted post-operative AKI in unadjusted analysis but not after adjusting for clinical variables (RR, 2.78; 0.70-6.65). For AKI risk prediction, AUC (95% CI) was highest after combining clinical model and pre-operative ACR for groups aged < 2 years [0.805 (0.713-0.896)] and ≥ 2 years [0.872 (0.772-0.973)].

CONCLUSIONS

This study provides evidence for use of albuminuria as a feasible biomarker in AKI prediction in children post cardiac surgery, especially when added to a clinical model. A higher resolution version of the Graphical abstract is available as Supplementary information.

Clinical Predictors and Long-term Impact of Acute Kidney Injury on Progression of Diabetic Kidney Disease in Chinese Patients With Type 2 Diabetes

We aim to assess the long-term impact of acute kidney injury (AKI) on progression of diabetic kidney disease (DKD) and all-cause mortality and investigate determinants of AKI in Chinese patients with type 2 diabetes (T2D). A consecutive cohort of 9,096 Chinese patients with T2D from the Hong Kong Diabetes Register was followed for 12 years (mean ± SD age 57 ± 13.2 years; 46.9% men; median duration of diabetes 5 years). AKI was defined based on the Kidney Disease: Improving Global Outcomes (KDIGO) criteria using serum creatinine. Estimated glomerular filtration rate measurements were used to identify the first episode with chronic kidney disease (CKD) and end-stage renal disease (ESRD). Polygenic risk score (PRS) composed of 27 single nucleotide polymorphisms (SNPs) known to be associated with serum uric acid (SUA) in European populations was used to examine the role of SUA in pathogenesis of AKI, CKD, and ESRD. Validation was sought in an independent cohort including 6,007 patients (age 61.2 ± 10.9 years; 59.5% men; median duration of diabetes 10 years). Patients with AKI had a higher risk for developing incident CKD (hazard ratio 14.3 [95% CI 12.69-16.11]), for developing ESRD (12.1 [10.74-13.62]), and for all-cause death (7.99 [7.31-8.74]) compared with those without AKI. Incidence rate for ESRD among patients with no episodes of AKI and one, two, and three or more episodes of AKI was 7.1, 24.4, 32.4, and 37.3 per 1,000 person-years, respectively. Baseline SUA was a strong independent predictor for AKI. A PRS composed of 27 SUA-related SNPs was associated with AKI and CKD in both discovery and replication cohorts but not ESRD. Elevated SUA may increase the risk of DKD through increasing AKI. The identification of SUA as a modifiable risk factor and PRS as a nonmodifiable risk factor may facilitate the identification of individuals at high risk to prevent AKI and its long-term impact in T2D.

Perioperative anemia predicts kidney injury after partial nephrectomy

Purpose

Partial nephrectomy (PN) induced kidney injury is still a challenging clinical matter that has not been completely conquered. This study aimed to explore the influences of perioperative anemia on renal function after PN.

Materials and Methods

A total of 114 patients undergoing PN were retrospectively studied. Serum creatinine was tested preoperatively and 24 hours and 3 days after PN to evaluate the occurrence of acute kidney injury (AKI). Perioperative anemia was evaluated on the basis of the hemoglobin (Hb) value at 24 hours and 3 days postoperation. Patients were then followed up for the development of chronic kidney disease (CKD). Associations between perioperative anemia and postoperative AKI and CKD were determined.

Results

The cumulative incidence of perioperative anemia was 33.33% in the study. A total of 32.46% of patients suffered from postoperative AKI, and 16.67% of patients progressed to CKD. The incidences of AKI and CKD in perioperative anemia patients were dramatically exceeded in those without anemia. Further statistical analyses indicated that perioperative anemia was a relevant factor for postoperative kidney injury, presenting the highest odds ratio of 31.272 for postoperative AKI and 17.179 for postoperative CKD. Receiver operating characteristic curve analysis showed that ΔHb=(preoperative Hb)-(postoperative Hb nadir) was a meaningful predictor of postoperative kidney injury, with an area under the curve of 0.784 for predicting postoperative AKI and 0.805 for postoperative CKD.

Conclusions

Perioperative anemia can predict kidney injury after PN, and ΔHb shows a meaningful predictive value for postoperative AKI and CKD.

Long-Term Preservation of Renal Function in Septic Shock Burn Patients Requiring Renal Replacement Therapy for Acute Kidney Injury

BACKGROUND

The real impact of septic shock-associated acute kidney injury (AKI) on the long-term renal outcome is still debated, and little is known about AKI-burn patients. In a cohort of burn survivors treated by continuous renal replacement therapy (CRRT) and sorbent technology (CPFA-CRRT), we investigated the long-term outcome of glomerular and tubular function.

METHODS

Out of 211 burn patients undergoing CRRT from 2001 to 2017, 45 survived, 40 completed the clinical follow-up (cumulative observation period 4067 months, median 84 months, IR 44-173), and 30 were alive on 31 December 2020. Besides creatinine and urine albumin, in the 19 patients treated with CPFA-CRRT, we determined the normalized GFR by 99mTc-DTPA (NRI-GFR) and studied glomerular and tubular urine protein markers.

RESULTS

At the follow-up endpoint, the median plasma creatinine and urine albumin were 0.99 (0.72-1.19) and 0.0 mg/dL (0.0-0.0), respectively. NRI-GFR was 103.0 mL/min (93.4-115). Four patients were diabetic, and 22/30 presented at least one risk factor for chronic disease (hypertension, dyslipidemia, and overweight). Proteinuria decreased over time, from 0.47 g/day (0.42-0.52) at 6 months to 0.134 g/day (0.09-0.17) at follow-up endpoint. Proteinuria positively correlated with the peak of plasma creatinine (r 0.6953, p 0.006) and the number of CRRT days (r 0.5650, p 0.035) during AKI course, and negatively with NRI-GFR (r -0.5545, p 0.049). In seven patients, urine protein profile showed a significant increase of glomerular marker albumin and glomerular/tubular index.

CONCLUSIONS

Burn patients who experienced septic shock and AKI treated with CRRT had a long-term expectation of preserved renal function. However, these patients were more predisposed to microalbuminuria, diabetes, and the presence of risk factors for intercurrent comorbidities and chronic renal disease.

Comparison of COVID-19 versus influenza on the incidence, features, and recovery from acute kidney injury in hospitalized United States Veterans

Acute kidney injury is a common complication in patients hospitalized with SARSCoV-2 (COVID-19), with prior studies implicating multiple potential mechanisms of injury. Although COVID-19 is often compared to other respiratory viral illnesses, few formal comparisons of these viruses on kidney health exist. In this retrospective cohort study, we compared the incidence, features, and outcomes of acute kidney injury among Veterans hospitalized with COVID-19 or influenza and adjusted for baseline conditions using weighted comparisons. A total of 3402 hospitalizations for COVID-19 and 3680 hospitalizations for influenza admitted between October 1, 2019 and May 31, 2020 across 127 Veterans Administration hospitals nationally were studied using the electronic medical record. Acute kidney injury occurred more frequently among those with COVID-19 compared to those with influenza (40.9% versus 29.4%, weighted analysis) and was more severe. Patients with COVID-19 were more likely to require mechanical ventilation and vasopressors and experienced higher mortality. Proteinuria and hematuria were frequent in both groups but more common in COVID-19. Recovery of kidney function was less common in patients with COVID-19 and acute kidney injury but was similar among survivors. Thus, findings from this study confirm that acute kidney injury is more common and severe among patients hospitalized with COVID-19 compared to influenza, a finding that may be driven largely by illness severity. Hence, the combined impact of these two illnesses on kidney health may be significant and have important implications for resource allocation.

Complication and Sequelae of COVID-19: What Should We Pay Attention to in the Post-Epidemic Era

COVID-19 is widespread worldwide and seriously affects the daily life and health of humans. Countries around the world are taking necessary measures to curb the spread. However, COVID-19 patients often have at least one organ complication and sequelae in addition to respiratory symptoms. Controlling the epidemic is only a phased victory, and the complication and sequelae of COVID-19 will need more attention in the post-epidemic era. We collected general information from over 1000 articles published in 2020 after the COVID-19 outbreak and systematically analyzed the complication and sequelae associated with eight major systems in COVID-19 patients caused by ACE2 intervention in the RAS regulatory axis. The autoimmune response induced by 2019-nCoV attacks and damages the normal tissues and organs of the body. Our research will help medical workers worldwide address COVID-19 complication and sequelae.

Survival and kidney recovery among recipients of continuous renal replacement therapy

Continuous renal replacement therapy (CRRT) is widely used in the care of critically ill patients with acute kidney injury (AKI). Despite hopeful trends suggested by recent studies, mortality among CRRT recipients with severe AKI remains extremely high. Moreover, CRRT does not confer a reduction in mortality in trials comparing CRRT to intermittent RRT modalities. Among AKI survivors, some preliminary studies suggest a higher likelihood of kidney recovery and dialysis independence in CRRT recipients. AKI survivors are at risk for a broad array of adverse outcomes; strategies that may mitigate these risks are discussed.

Acute kidney injury and risk of cardiovascular outcomes: A nationwide cohort study

BACKGROUND

Acute kidney injury (AKI) has been associated with cardiovascular disease, but this is sparsely studied in non-selected populations and with little attention to the effect in age and renal function. Using nationwide administrative data, we investigated the hypothesis of increased one-year risk of cardiovascular event or death associated with AKI.

METHODS

In a cohort study, we identified all admissions in Denmark between 2008 and 2018. AKI was defined as ≥1.5 times increase from baseline to peak creatinine during admission, or dialysis. We excluded patients with age <50 years, estimated glomerular filtration rate (eGFR) <15ml/min/1.73m2, renal transplantation, index-admission due to cardiovascular disease or death during index-admission. The primary outcome was cardiovascular risk within one year from discharge, which was a composite of the secondary outcomes ischemic heart disease, heart failure or stroke. To estimate risks, we applied multiple logistic regression fitted by inverse probability of censoring weighting and stratified estimations by eGFR and age. We adjusted for proteinuria in the subcohort with measurements available.

RESULTS

Among 565,056 hospital admissions, 39,569 (7.0%) cases of AKI were present. In total, 18,642 patients sustained a cardiovascular outcome. AKI was significantly associated with cardiovascular outcome with an adjusted OR [CI] of 1.33 [1.16-1.53], 1.43 [1.33-1.54], 1.23 [1.14-1.34], 1.38 [1.18-1.62] for eGFR ≥90, 60-89, 30-59 and 15-29ml/min/1.73m2, respectively. When omitting the outcome heart failure, these results were 1.24 [1.06-1.45], 1.22 [1.11-1.33], 1.05 [0.95-1.16], 1.25 [1.02-1.54]. Results did not change substantially in strata of age groups, in AKI stages and in the subcohort adjusted for proteinuria.

CONCLUSION

Non-selected patients aged 50 years or above with AKI during admission had significantly higher one-year risk of cardiovascular event or death, especially, but not only due to heart failure, independent of age and eGFR.

Serum-free medium and hypoxic preconditioning synergistically enhance the therapeutic effects of mesenchymal stem cells on experimental renal fibrosis

Background

Mesenchymal stem cells (MSCs) repair injured tissue in a paracrine manner. To enhance their therapeutic properties, preconditioning with various factors has been researched. We have previously showed that MSCs cultured in serum-free medium (SF-MSCs) promote their immunosuppressive ability, thereby enhancing their anti-fibrotic effect. Here, we examined whether serum-free medium and hypoxic preconditioning synergistically enhance the therapeutic effects of MSCs on renal fibrosis in rats with ischemia–reperfusion injury (IRI).

Methods

SF-MSCs were incubated under 1% O₂ conditions (hypo-SF-MSCs) or 21% O₂ conditions (normo-SF-MSCs) for 24 h before collection. After IRI procedure, hypo-SF-MSCs or normo-SF-MSCs were injected through the abdominal aorta. At 7 or 21 days post-injection, the rats were killed and their kidneys were collected to evaluate inflammation and fibrosis. In in vitro experiments, we investigated whether hypo-SF-MSCs enhanced secretion of anti-fibrotic humoral factors using transforming growth factor (TGF)-β1-stimulated HK-2 cells incubated with conditioned medium from hypo-SF-MSCs or normo-SF-MSCs.

Results

Normo-SF-MSCs showed attenuation of senescence, which increased their proliferative capacity. Although no significant difference in cellular senescence was found between normo-SF-MSCs and hypo-SF-MSCs, hypo-SF-MSCs further increased their proliferative capacity compared with normo-SF-MSCs. Additionally, administration of hypo-SF-MSCs more strongly ameliorated renal fibrosis than that of normo-SF-MSCs. Moreover, although hypo-SF-MSCs strongly attenuated infiltration of inflammatory cells compared with the control rats, which were treated with PBS, this attenuation was almost equal between normo-SF-MSCs and hypo-SF-MSCs. In vitro experiments revealed that hypo-SF-MSCs more significantly inhibited transforming growth factor (TGF)-β/Smad signaling compared with normo-SF-MSCs. Moreover, hypoxic preconditioning increased hepatocyte growth factor (HGF) secretion even under serum-free conditions, whereas knockdown of HGF in hypo-SF-MSCs attenuated inhibition of TGF-β/Smad signaling.

Conclusions

These results indicate that administration of ex vivo-expanded, hypoxia-preconditioned SF-MSCs may be a useful cell therapy to prevent renal fibrosis.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-021-02548-7.

Development of mortality prediction model in the elderly hospitalized AKI patients

Acute kidney injury (AKI) correlates with increased health-care costs and poor outcomes in older adults. However, there is no good scoring system to predict mortality within 30-day, 1-year after AKI in older adults. We performed a retrospective analysis screening data of 53,944 hospitalized elderly patients (age > 65 years) from multi-centers in China. 944 patients with AKI (acute kidney disease) were included and followed up for 1 year. Multivariable regression analysis was used for developing scoring models in the test group (a randomly 70% of all the patients). The established models have been verified in the validation group (a randomly 30% of all the patients). Model 1 that consisted of the risk factors for death within 30 days after AKI had accurate discrimination (The area under the receiver operating characteristic curves, AUROC: 0.90 (95% CI 0.875–0.932)) in the test group, and performed well in the validation groups (AUROC: 0.907 (95% CI 0.865–0.949)). The scoring formula of all-cause death within 1 year (model 2) is a seven-variable model including AKI type, solid tumor, renal replacement therapy, acute myocardial infarction, mechanical ventilation, the number of organ failures, and proteinuria. The area under the receiver operating characteristic (AUROC) curves of model 2 was > 0.80 both in the test and validation groups. Our newly established risk models can well predict the risk of all-cause death in older hospitalized AKI patients within 30 days or 1 year.

Acute kidney injury

Acute kidney injury (AKI) is defined by a sudden loss of excretory kidney function. AKI is part of a range of conditions summarized as acute kidney diseases and disorders (AKD), in which slow deterioration of kidney function or persistent kidney dysfunction is associated with an irreversible loss of kidney cells and nephrons, which can lead to chronic kidney disease (CKD). New biomarkers to identify injury before function loss await clinical implementation. AKI and AKD are a global concern. In low-income and middle-income countries, infections and hypovolaemic shock are the predominant causes of AKI. In high-income countries, AKI mostly occurs in elderly patients who are in hospital, and is related to sepsis, drugs or invasive procedures. Infection and trauma-related AKI and AKD are frequent in all regions. The large spectrum of AKI implies diverse pathophysiological mechanisms. AKI management in critical care settings is challenging, including appropriate volume control, nephrotoxic drug management, and the timing and type of kidney support. Fluid and electrolyte management are essential. As AKI can be lethal, kidney replacement therapy is frequently required. AKI has a poor prognosis in critically ill patients. Long-term consequences of AKI and AKD include CKD and cardiovascular morbidity. Thus, prevention and early detection of AKI are essential.

Acute kidney injury in the critically ill: an updated review on pathophysiology and management

Acute kidney injury (AKI) is now recognized as a heterogeneous syndrome that not only affects acute morbidity and mortality, but also a patient’s long-term prognosis. In this narrative review, an update on various aspects of AKI in critically ill patients will be provided. Focus will be on prediction and early detection of AKI (e.g., the role of biomarkers to identify high-risk patients and the use of machine learning to predict AKI), aspects of pathophysiology and progress in the recognition of different phenotypes of AKI, as well as an update on nephrotoxicity and organ cross-talk. In addition, prevention of AKI (focusing on fluid management, kidney perfusion pressure, and the choice of vasopressor) and supportive treatment of AKI is discussed. Finally, post-AKI risk of long-term sequelae including incident or progression of chronic kidney disease, cardiovascular events and mortality, will be addressed.

Long-term consequences of acute kidney injury: a narrative review

The incidence of acute kidney injury (AKI) has increased in the past decades. AKI complicates up to 15% of hospitalizations and can reach up to 50-60% in critically ill patients. Besides the short-term impact of AKI in patient outcomes, several studies report the association between AKI and adverse long-term outcomes, such as recurrent AKI episodes in 25-30% of cases, hospital re-admissions in up to 40% of patients, an increased risk of cardiovascular events, an increased risk of progression of chronic kidney disease (CKD) after AKI and a significantly increased long-term mortality. Despite the long-term impact of AKI, there are neither established guidelines on the follow-up care of AKI patients, nor treatment strategies to reduce the incidence of sequelae after AKI. Only a minority of patients have been referred to nephrology post-discharge care, despite the evidence of improved outcomes associated with nephrology referral by addressing cardiovascular risk and risk of progression to CKD. Indeed, AKI survivors should have specialized nephrology follow-up to assess kidney function after AKI, perform medication reconciliation, educate patients on nephrotoxic avoidance and implement strategies to prevent CKD progression. The authors provide a comprehensive review of the transition from AKI to CKD, analyse the current evidence on the long-term outcomes of AKI and describe predisposing risk factors, highlight the importance of follow-up care in these patients and describe the current therapeutic strategies which are being investigated on their impact in improving patient outcomes.

Acute Kidney Disease to Chronic Kidney Disease

Acute kidney injury (AKI) and chronic kidney disease are common interconnected syndromes that represent a public health problem. Acute kidney disease (AKD) is defined as the post-AKI status of acute or subacute kidney damage/dysfunction manifested by persistence of AKI beyond 7 to 90 days after the initial AKI diagnosis. Limited clinical data exist regarding AKD epidemiology but its incidence is observed in ∼25% of AKI survivors. Useful risk-stratification tools to predict risk of AKD and its prognosis are needed. Interventions on fluid management, nephrotoxic exposure, and follow-up care hold promise to ameliorate the burden of AKD and its complications.

Individualized acute kidney injury after care

PURPOSE OF REVIEW

The aim of this study was to summarize the current evidence around the impact of individualizing patient care following an episode of acute kidney injury (AKI) in the ICU.

RECENT FINDINGS

Over the last years, evidence has demonstrated that the follow-up care after episodes of AKI is lacking and standardization of this process is likely needed. Although this is informed largely by large retrospective cohort studies, a few prospective observational trials have been performed. Medication reconciliation and patient/caregiver education are important tenants of follow-up care, regardless of the severity of AKI. There is evidence the initiation and/or reinstitution of renin-angiotensin-aldosterone agents may improve patient's outcomes following AKI, although they may increase the risk for adverse events, especially when reinitiated early. In addition, 3 months after an episode of AKI, serum creatinine and proteinuria evaluation may help identify patients who are likely to develop progressive chronic kidney disease over the ensuing 5 years. Lastly, there are emerging differences between those who do and do not require renal replacement therapy (RRT) for their AKI, which may require more frequent and intense follow-up in those needing RRT.

SUMMARY

Although large scale evidence-based guidelines are lacking, standardization of post-ICU-AKI is needed.

Care of the Survivor of Critical Illness and Acute Kidney Injury: A Multidisciplinary Approach

Acute kidney injury (AKI) is a common complication of critical illness and is associated with adverse short- and long-term health consequences. Survivors of critical illness and AKI experience poor kidney, cardiovascular and quality of life outcomes, along with increased mortality. Yet, many patients surviving AKI are unaware that there is a problem with their kidney health, and post-AKI nephrology follow-up occurs at very low rates. Although there is a paucity of evidence-based studies to guide post-AKI care, attention to risk factors such as hypertension and albuminuria are requisite. There are several ongoing or planned studies which are expected to help inform specific management in the future. Until then, a multidisciplinary approach is warranted to address areas such as quality of life, physical rehabilitation, dietary modifications, and medication reconciliation.

Prospective Cohort Study of Renin-Angiotensin System Blocker Usage after Hospitalized Acute Kidney Injury

BACKGROUND AND OBJECTIVES

The risk-benefit ratio of angiotensin-converting enzyme inhibitor or angiotensin receptor blocker therapy after AKI may be altered due to concerns regarding recurrent AKI. We evaluated, in a prospective cohort, the association between use (versus nonuse) of angiotensin-converting enzyme inhibitors/angiotensin receptor blockers and the subsequent risk of AKI and other adverse outcomes after hospitalizations with and without AKI.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We studied 1538 patients recently discharged from the hospital who enrolled in the multicenter, prospective ASSESS-AKI study, with approximately half of patients experiencing AKI during the index hospitalization. All participants were seen at a baseline visit 3 months after their index hospitalization and were categorized at that time on whether they were using angiotensin-converting enzyme inhibitors/angiotensin receptor blockers or not. We used multivariable Cox regression, adjusting for demographics, comorbidities, eGFR, urine protein-creatinine ratio, and use of other medications, to examine the association between angiotensin-converting enzyme inhibitor/angiotensin receptor blocker use and subsequent risks of AKI, death, kidney disease progression, and adjudicated heart-failure events.

RESULTS

The use of angiotensin-converting enzyme inhibitors/angiotensin receptor blockers was 50% (386/769) among those with AKI during the index hospitalization and 47% (362/769) among those without. Among those with AKI during the index hospitalization, angiotensin-converting enzyme inhibitor/angiotensin receptor blocker use was not associated with a higher risk of recurrent hospitalized AKI (adjusted hazard ratio, 0.88; 95% confidence interval, 0.69 to 1.13). Associations between angiotensin-converting enzyme inhibitor/angiotensin receptor blocker use and death, kidney disease progression, and adjudicated heart-failure events appeared similar in study participants who did and did not experience AKI during the index hospitalization (all interaction P values >0.05).

CONCLUSIONS

The risk-benefit ratio of angiotensin-converting enzyme inhibitor/angiotensin receptor blocker therapy after hospital discharge appears to be similar regardless of whether AKI occurred during the hospitalization.

Cyclophilin Inhibition Protects Against Experimental Acute Kidney Injury and Renal Interstitial Fibrosis

Cyclophilins have important homeostatic roles, but following tissue injury, cyclophilin A (CypA) can promote leukocyte recruitment and inflammation, while CypD can facilitate mitochondrial-dependent cell death. This study investigated the therapeutic potential of a selective cyclophilin inhibitor (GS-642362), which does not block calcineurin function, in mouse models of tubular cell necrosis and renal fibrosis. Mice underwent bilateral renal ischemia/reperfusion injury (IRI) and were killed 24 h later: treatment with 10 or 30 mg/kg/BID GS-642362 (or vehicle) began 1 h before surgery. In the second model, mice underwent unilateral ureteric obstruction (UUO) surgery and were killed 7 days later; treatment with 10 or 30 mg/kg/BID GS-642362 (or vehicle) began 1 h before surgery. GS-642362 treatment gave a profound and dose-dependent protection from acute renal failure in the IRI model. This protection was associated with reduced tubular cell death, including a dramatic reduction in neutrophil infiltration. In the UUO model, GS-642362 treatment significantly reduced tubular cell death, macrophage infiltration, and renal fibrosis. This protective effect was independent of the upregulation of IL-2 and activation of the stress-activated protein kinases (p38 and JNK). In conclusion, GS-642362 was effective in suppressing both acute kidney injury and renal fibrosis. These findings support further investigation of cyclophilin blockade in other types of acute and chronic kidney disease.

Renal ischemia-reperfusion leads to hypertension and changes in proximal tubule Na+ transport and renin-angiotensin-aldosterone system: Role of NADPH oxidase

Acute renal injury (AKI) is a risk factor for the development of hypertension, which involves oxidative stress, changes in Na⁺ handling, and the intrarenal renin-angiotensin-aldosterone system (RAAS) as underlying mechanisms. We investigated in rats whether renal ischemia-reperfusion (IR) leads to changes in the proximal tubule ATP-dependent Na⁺ transport and the intrarenal content of RAAS components, as well as the role of NADPH oxidase. Rats weighing 300-350 g were submitted to AKI by bilateral IR (n = 25). After IR injury, the animals were followed up for 4 weeks. One part (n = 7) received daily treatment with the NADPH oxidase inhibitor apocynin (100 mg/kg, drinking water), while another part (n = 9) received apocynin 24 h before and after IR. One group was submitted to sham surgery (n = 8). Four weeks after IR, the rats presented elevated systolic blood pressure, as well as increased lipid peroxidation, NADPH oxidase activity, (Na⁺+K⁺)ATPase activity, and upregulation of type 1 angiotensin II receptor in the renal cortex. On the other hand, there was a decrease in Na⁺-ATPase activity and downregulation of the isoforms 1 and 2 of the angiotensin-converting enzyme, type 2 angiotensin II receptor, and of the α and ε isoforms of protein kinase C. Most of these alterations was prevented by both apocynin treatment protocols. Thus, we conclude that AKI-induced by IR may induce changes in proximal tubule ATPases and RAAS components compatible with renal Na⁺ retention and hypertension. These data also indicate that the NADPH oxidase represents a key factor in the origin of these alterations.

The Protective Effect of Shen Qi Wan on Adenine-Induced Podocyte Injury

Podocytes are a special type of differentiated epithelial cells that maintain the glomerular filtration barrier in the kidney. Injury or damages in podocytes can cause kidney-related disorders, like CKD. The injury or dysfunction of podocytes can occur by different metabolic disorders. Due to the severity and complexity of podocyte injuries, this state is considered as a serious health issue worldwide. Here, we examined and addressed the efficacy of an alternative Chinese medicine, Shen Qi Wan (SQW), on podocyte-related kidney injury. We evaluated the role and mechanism of action of SQW in podocyte injury. We observed that SQW significantly reduced 24-hour urinary protein and blood urea nitrogen levels and alleviated the pathological damage caused by adenine. Moreover, SQW significantly decreased the expression of nephrin and increased the expression of WT1 and AQP1 in the kidney of mice treated with adenine. We observed that SQW did not effectively reduce the high level of proteinuria in AQP1^−/− mice indicating the prominent role of AQP1 in the SQW-ameliorating pathway. Transmission electron microscopy (TEM) images indicated the food processes effacement in AQP1^−/− mice were not lessened by SQW. In conclusion, podocyte injury could alter the pathological nature of the kidney, and SQW administration relieves the nature of pathogenesis by activating AQP1.

Incidence and risk factors of kidney impairment on patients with COVID-19: A meta-analysis of 10180 patients

BACKGROUND

The novel coronavirus is pandemic around the world. Several researchers have given the evidence of impacts of COVID-19 on the respiratory, cardiovascular and gastrointestinal system. Studies still have debated on kidney injury of COVID-19 patients. The purpose of the meta-analysis was to evaluate the association of kidney impairment with the development of COVID-19.

METHODS

The PubMed, Embase and MedRxiv databases were searched until May 1, 2020. We extracted data from eligible studies to summarize the clinical manifestations and laboratory indexes of kidney injury on COVID-19 infection patients and further compared the prevalence of acute kidney injury (AKI) and the mean differences of three biomarkers between in ICU/severe and non-ICU/non-severe cases. Heterogeneity was evaluated using the I2 method.

RESULTS

In the sum of 24 studies with 10180 patients were included in this analysis. The pooled prevalence of AKI, increased serum creatinine (Scr), increased blood urea nitrogen (BUN), increased D-dimer, proteinuria and hematuria in patients with COVID-19 were 16.2%, 8.3%, 6.2%, 49.8%, 50.1% and 30.3% respectively. Moreover, the means of Scr, BUN and D-dimer were shown 6.4-folds, 1.8-folds and 0.67-folds, respectively, higher in ICU/severe cases than in corresponding non-ICU/non-severe patients. The prevalence of AKI was about 30 folds higher in ICU/severe patients compared with the non-ICU/non-severe cases.

CONCLUSIONS

Overall, we assessed the incidences of the clinic and laboratory features of kidney injury in COVID-19 patients. And kidney dysfunction may be a risk factor for COVID-19 patients developing into the severe condition. In reverse, COVID-19 can also cause damage to the kidney.

Association of Proteinuria and Hematuria with Acute Kidney Injury and Mortality in Hospitalized Patients with COVID-19

INTRODUCTION

Acute kidney injury (AKI) is strongly associated with poor outcomes in hospitalized patients with coronavirus disease 2019 (COVID-19), but data on the association of proteinuria and hematuria are limited to non-US populations. In addition, admission and in-hospital measures for kidney abnormalities have not been studied separately.

METHODS

This retrospective cohort study aimed to analyze these associations in 321 patients sequentially admitted between March 7, 2020 and April 1, 2020 at Stony Brook University Medical Center, New York. We investigated the association of proteinuria, hematuria, and AKI with outcomes of inflammation, intensive care unit (ICU) admission, invasive mechanical ventilation (IMV), and in-hospital death. We used ANOVA, t test, χ2 test, and Fisher's exact test for bivariate analyses and logistic regression for multivariable analysis.

RESULTS

Three hundred patients met the inclusion criteria for the study cohort. Multivariable analysis demonstrated that admission proteinuria was significantly associated with risk of in-hospital AKI (OR 4.71, 95% CI 1.28-17.38), while admission hematuria was associated with ICU admission (OR 4.56, 95% CI 1.12-18.64), IMV (OR 8.79, 95% CI 2.08-37.00), and death (OR 18.03, 95% CI 2.84-114.57). During hospitalization, de novo proteinuria was significantly associated with increased risk of death (OR 8.94, 95% CI 1.19-114.4, p = 0.04). In-hospital AKI increased (OR 27.14, 95% CI 4.44-240.17) while recovery from in-hospital AKI decreased the risk of death (OR 0.001, 95% CI 0.001-0.06).

CONCLUSION

Proteinuria and hematuria both at the time of admission and during hospitalization are associated with adverse clinical outcomes in hospitalized patients with COVID-19.

Acute Kidney Injury: A Bona Fide Complication of Diabetes

The landscape of kidney disease in diabetes has shifted. The classical dogma of "diabetic nephropathy" progressing through stages of albuminuria, leading to decline in glomerular filtration rate and end-stage kidney disease (ESKD), has been replaced by a more nuanced understanding of the complex and heterogeneous nature of kidney disease in diabetes. Paralleling this evolution, standardized definitions have resulted in a growing appreciation that acute kidney injury (AKI) is increasing in its incidence rapidly and that people with diabetes are much more likely to develop AKI than people without diabetes. Here, I propose that AKI should be considered a complication of diabetes alongside other complications that similarly do not fit neatly into the historical microvascular/macrovascular paradigm. In this article, we take a look at the evidence indicating that diabetes is a major risk factor for AKI and we review the causes of this increased risk. We consider the long-term implications of AKI in diabetes and its potential contribution to the future development of chronic kidney disease, ESKD, and mortality. Finally, we look toward the future at strategies to better identify people at risk for AKI and to develop new approaches to improve AKI outcomes. Recognizing AKI as a bona fide complication of diabetes should open up new avenues for investigation that may ultimately improve the outlook for people living with diabetes and at risk for kidney disease.

Short- and potential long-term adverse health outcomes of COVID-19: a rapid review

The coronavirus disease 2019 (COVID-19) pandemic has resulted in millions of patients infected worldwide and indirectly affecting even more individuals through disruption of daily living. Long-term adverse outcomes have been reported with similar diseases from other coronaviruses, namely Middle East Respiratory Syndrome (MERS) and Severe Acute Respiratory Syndrome (SARS). Emerging evidence suggests that COVID-19 adversely affects different systems in the human body. This review summarizes the current evidence on the short-term adverse health outcomes and assesses the risk of potential long-term adverse outcomes of COVID-19. Major adverse outcomes were found to affect different body systems: immune system (including but not limited to Guillain-Barré syndrome and paediatric inflammatory multisystem syndrome), respiratory system (lung fibrosis and pulmonary thromboembolism), cardiovascular system (cardiomyopathy and coagulopathy), neurological system (sensory dysfunction and stroke), as well as cutaneous and gastrointestinal manifestations, impaired hepatic and renal function. Mental health in patients with COVID-19 was also found to be adversely affected. The burden of caring for COVID-19 survivors is likely to be huge. Therefore, it is important for policy makers to develop comprehensive strategies in providing resources and capacity in the healthcare system. Future epidemiological studies are needed to further investigate the long-term impact on COVID-19 survivors.

Renin-angiotensin aldosterone inhibitor use at hospital discharge among patients with moderate to severe acute kidney injury and its association with recurrent acute kidney injury and mortality

Recurrent episodes of acute kidney injury (AKI) are common among AKI survivors. Renin-angiotensin aldosterone inhibitors (RAASi) are often indicated for these patients but may increase the risk for recurrent AKI. Here, we examined whether RAASi associates with a higher risk for recurrent AKI and mortality among survivors of moderate to severe AKI in a retrospective cohort of Veterans who survived Stage II or III AKI. The primary exposure was RAASi at hospital discharge and the primary endpoint was recurrent AKI within 12 months. Cox proportional hazards models were fit on a propensity score-weighted cohort to compare time to recurrent AKI and mortality by RAASi exposure. Among 96,983 patients, 40% were on RAASi at discharge. Compared to patients who continued RAASi use, those discontinuing use experienced no difference in risk for recurrent AKI but had a significantly higher risk of mortality [hazard ratio 1.33 (95% confidence interval1.26-1.41)]. No differences in recurrent AKI risk was observed for non-users started or not on RAASi compared to prevalent users who continued RAASi. Subgroup analyses among those with diabetes, chronic kidney disease, heart failure, and malignancy were similar with exception of a modest reduction in recurrent AKI risk among RAASi discontinuers with chronic kidney disease. Thus, RAASi use among survivors of moderate to severe AKI was associated with little to no difference in risk for recurrent AKI but was associated with improved survival. Reinitiating or starting RAASi among patients with strong indications is warranted but should be balanced with individual overall risk for recurrent AKI and with adequate monitoring.

Impaired angiotensin II type 1 receptor signaling contributes to sepsis-induced acute kidney injury

In sepsis-induced acute kidney injury, kidney blood flow may increase despite decreased glomerular filtration. Normally, angiotensin-II reduces kidney blood flow to maintain filtration. We hypothesized that sepsis reduces angiotensin type-1 receptor (AT1R) expression to account for this observation and tested this hypothesis in a patient case-control study and studies in mice. Seventy-three mice underwent cecal ligation and puncture (a sepsis model) or sham operation. Additionally, 94 septic mice received losartan (selective AT1R antagonist), angiotensin II without or with losartan, or vehicle. Cumulative urine output, kidney blood flow, blood urea nitrogen, and creatinine were measured. AT1R expression was assessed using ELISA, qPCR, and immunofluorescence. A blinded pathologist evaluated tissue for ischemic injury. AT1R expression was compared in autopsy tissue from seven patients with sepsis to that of the non-involved portion of kidney from ten individuals with kidney cancer and three non-infected but critically ill patients. By six hours post ligation/puncture, kidney blood flow doubled, blood urea nitrogen rose, and urine output fell. Concurrently, AT1R expression significantly fell 2-fold in arterioles and the macula densa. Creatinine significantly rose by 24 hours and sham operation did not alter measurements. Losartan significantly exacerbated ligation/puncture-induced changes in kidney blood flow, blood urea nitrogen, creatinine, and urine output. There was no histologic evidence of cortical ischemia. Significantly, angiotensin II prevented changes in kidney blood flow, creatinine, and urine output compared to vehicle. Co-administering losartan with angiotensin-II reversed this protection. Relative to both controls, patients with sepsis had low AT1R expression in arterioles and macula densa. Thus, murine cecal ligation/puncture and clinical sepsis decrease renal AT1R expression. Angiotensin II prevents functional changes while AT1R-blockade exacerbates them independent of ischemia in mice.