Bidirectional relationships between acute kidney injury and chronic kidney disease

Transition from acute kidney injury to chronic kidney disease in liver cirrhosis patients: Current perspective

In liver cirrhosis patients, acute kidney injury (AKI) is a common and severe complication associated with significant morbidity and mortality, often leading to chronic kidney disease (CKD). This progression reflects a complex interplay of renal and hepatic pathophysiology, with AKI acting as an initiator through maladaptive repair mechanisms. These mechanisms—such as tubular cell cycle arrest, inflammatory cascades, and fibrotic processes—are exacerbated by the hemodynamic and neurohormonal disturbances characteristic of cirrhosis. Following AKI episodes, persistent kidney dysfunction or acute kidney disease (AKD) often serves as a bridge to CKD. AKD represents a critical phase in renal deterioration, characterized by prolonged kidney injury that does not fully meet CKD criteria but exceeds the temporal scope of AKI. The progression from AKD to CKD is further influenced by recurrent AKI episodes, impaired renal autoregulation, and systemic comorbidities such as diabetes and metabolic dysfunction-associated steatotic liver disease, which compound kidney damage. The clinical management of AKI and CKD in cirrhotic patients requires a multidimensional approach that includes early identification of kidney injury, the application of novel biomarkers, and precision interventions. Recent evidence underscores the inadequacy of traditional biomarkers in predicting the AKI-to-CKD progression, necessitating novel biomarkers for early detection and intervention.

Plasma neutrophil gelatinase-associated lipocalin as a single test rule out biomarker for acute kidney injury: A cross-sectional study in patients admitted to the emergency department

OBJECTIVES

Acute kidney injury (AKI) is a syndrome with high mortality and morbidity in part due to delayed recognition based on changes in creatinine. A marker for AKI based on a single measurement is needed and therefore the performance of a single measurement of plasma neutrophil gelatinase-associated lipocalin (pNGAL) to predict AKI in patients admitted to the emergency department was tested.

METHODS

Samples from the Triage study which included 6005 consecutive adult patients admitted to the emergency department were tested for pNGAL. The optimal cutoff for pNGAL was determined by the AUC and compared to AKI based on creatinine using different estimations of the premorbid kidney function.

RESULTS

In 4833 patients, two or more plasma creatinine (pCr) measurements were available allowing the detection of AKI. The highest prevalence of AKI (10%) was found when defining AKI as an increase in pCr ≥26.5 μmol/L from the prior year's mean pCr. At these conditions the AUC for pNGAL to predict AKI was 85% giving an optimal cutoff of 142.5 ng/mL with a negative predictive value of 0.96, a positive predictive value of 0.35, a specificity of 0.87 and a sensitivity of 0.70.

CONCLUSION

The study illustrates that the value of a single measurement of pNGAL is primarily in excluding AKI whereas it`s poorer in predicting the presence of AKI. When diagnosing AKI with pCr the optimal baseline pCr level is the mean of available pCr (mb-pCr) measurements from up to a year prior to the current event.

Nanocarrier-Based Drug Delivery Systems Targeting Kidney Diseases

BACKGROUND

The potential applications of nanotechnology in the medical field have become increasingly recognized in recent years. Nanocarriers have emerged as a versatile tool, offering a wide range of applications due to their unique properties. In addition to the targeted drugs delivery, nanocarriers have also proven to be extremely effective in imaging and diagnostics. Continuous advances in nanotechnology have paved the way for innovative solutions to complex challenges in human health, shaping the future of nanotechnology and its applications.

SUMMARY

By exploring different types of nanoparticles, this review delves into the different characteristics that can be tailored to enhance their kidney access. Although the structural complexity of the kidney may prevent nanocarriers passage, optimization of nanocarrier characteristics such as shape, size, charge, and surface modifications may overcome these barriers, allowing for targeted delivery. By harnessing the potential of nanoparticles, researchers aim to develop targeted and efficient therapies that can address various kidney-related disorders.

KEY MESSAGES

This review highlights the promising advancements in nanotechnology and their potential impact on improving the therapeutic outcomes for several kidney diseases.

Renoprotective mechanisms of exercise training against acute and chronic renal diseases - A perspective based on experimental studies

Regular exercise training can lead to several health benefits, reduce mortality risk, and increase life expectancy. On the other hand, a sedentary lifestyle is a known risk factor for chronic diseases and increased mortality. Acute kidney injury (AKI) and chronic kidney disease (CKD) represent a significant global health problem, affecting millions of people worldwide. The progression from AKI to CKD is well-recognized in the literature, and exercise training has emerged as a potential renoprotective strategy. Thus, this article aims to review the main molecular mechanisms underlying the renoprotective actions of exercise training in the context of AKI and CKD, focusing on its antioxidative, anti-inflammatory, anti-apoptotic, anti-fibrotic, and autophagy regulatory effects. For that, bibliographical research was carried out in Medline/PubMed and Scielo databases. Although the pathophysiological mechanisms involved in renal diseases are not fully understood, experimental studies demonstrate that oxidative stress, inflammation, apoptosis, and dysregulation of fibrotic and autophagic processes play central roles in the development of tissue damage. Increasing evidence has suggested that exercise can beneficially modulate these mechanisms, potentially becoming a safe and effective non-pharmacological strategy for kidney health protection and promotion. Thus, the evidence base discussed in this review suggests that an adequate training program emerges as a valuable tool for preserving renal function in experimental animals, mainly through the production of antioxidant enzymes, nitric oxide (NO), irisin, IL-10, and IL-11. Future research can continue to explore these mechanisms to develop specific guidelines for the prescription of exercise training in different populations of patients with kidney diseases.

Acute Kidney Injury and Subsequent Kidney Failure With Replacement Therapy Incidence in Older Adults With Advanced CKD: A Cohort Study of US Veterans

Rationale & Objective

Advanced age is a major risk factor for chronic kidney disease (CKD) development, which has high heterogeneity in disease progression. Acute kidney injury (AKI) hospitalization rates are increasing, especially among older adults. Previous AKI epidemiologic analyses have focused on hospitalized populations, which may bias results toward sicker populations. This study examined the association between AKI and incident kidney failure with replacement therapy (KFRT) while evaluating age as an effect modifier of this relationship.

Study Design

Retrospective cohort study.

Setting & Participants

24,133 Veterans at least 65 years old with incident CKD stage 4 from 2011 to 2013.

Exposures

AKI, AKI severity, and age.

Outcomes

KFRT and death.

Analytical Approach

The Fine-Gray competing risk regression was used to model AKI and incident KFRT with death as a competing risk. A Cox regression was used to model AKI severity and death.

Results

Despite a nonsignificant age interaction between AKI and KFRT, a clinically relevant combined effect of AKI and age on incident KFRT was observed. Compared with our oldest age group without AKI, those aged 65-74 years with AKI had the highest risk of KFRT (subdistribution HR [sHR], 14.9; 95% CI, 12.7-17.4), whereas those at least 85 years old with AKI had the lowest (sHR, 1.71; 95% CI, 1.22-2.39). Once Veterans underwent KFRT, their risk of death increased by 44%. A 2-fold increased risk of KFRT was observed across all AKI severity stages. However, the risk of death increased with worsening AKI severity.

Limitations

Our study lacked generalizability, was restricted to ever use of medications, and used inpatient serum creatinine laboratory results to define AKI and AKI severity.

Conclusions

In this national cohort, advanced age was protective against incident KFRT but not death. This is likely explained by the high frequency of deaths observed in this population (51.1%). Nonetheless, AKI and younger age are substantial risk factors for incident KFRT.

Recent Update on Acute Kidney Injury-to-Chronic Kidney Disease Transition

Acute kidney injury (AKI) is characterized by an abrupt decline of excretory kidney function. The incidence of AKI has increased in the past decades. Patients diagnosed with AKI often undergo diverse clinical trajectories, such as early or late recovery, relapses, and even a potential transition from AKI to chronic kidney disease (CKD). Although recent clinical studies have demonstrated a strong association between AKI and progression of CKD, our understanding of the complex relationship between AKI and CKD is still evolving. No cohort study has succeeded in painting a comprehensive picture of these multi-faceted pathways. To address this lack of understanding, the idea of acute kidney disease (AKD) has recently been proposed. This presents a new perspective to pinpoint a period of heightened vulnerability following AKI, during which a patient could witness a substantial decline in glomerular filtration rate, ultimately leading to CKD transition. Although AKI is included in a range of kidney conditions collectively known as AKD, spanning from mild and self-limiting to severe and persistent, AKD can also occur without a rapid onset usually seen in AKI, such as when kidney dysfunction slowly evolves. In the present review, we summarize the most recent findings about AKD, explore the current state of biomarker discovery related to AKD, discuss the latest insights into pathophysiological underpinnings of AKI to CKD transition, and reflect on therapeutic challenges and opportunities that lie ahead.

Oleoylethanolamide attenuates acute-to-chronic kidney injury: in vivo and in vitro evidence of PPAR-α involvement

Chronic kidney disease (CKD) development after acute kidney injury (AKI) involves multiple mechanisms, including inflammation, epithelial-mesenchymal transition (EMT), and extracellular matrix deposition, leading to progressive tubulointerstitial fibrosis. Recently, a central role for peroxisome-proliferator activated receptor (PPAR)-α has been addressed in preserving kidney function during AKI. Among endogenous lipid mediators, oleoylethanolamide (OEA), a PPAR-α agonist, has been studied for its metabolic and anti-inflammatory effects. Here, we have investigated OEA effects on folic acid (FA)-induced kidney injury in mice and the underlying mechanisms. OEA improved kidney function, normalized urine output, and reduced serum BUN, creatinine, and albuminuria. Moreover, OEA attenuated tubular epithelial injury, as shown by histological analysis, and decreased expression of neutrophil gelatinase-associated lipocalin and kidney injury molecule-1. Gene expression analysis of kidney tissue indicated that OEA limited immune cell infiltration and inflammation. Moreover, OEA significantly inhibited Wnt7b and Catnb1 gene transcription and α-smooth muscle actin expression, indicating suppression of EMT. Accordingly, OEA exhibited an anti-fibrotic effect, as shown by Masson staining and the reduced levels of transforming growth factor (TGF)-β1, fibronectin, and collagen IV. Mechanistically, the nephroprotective effect of OEA was related to PPAR-α activation since OEA failed to exert its beneficial activity in FA-insulted PPAR-α-/- mice. PPAR-α involvement was also confirmed in HK2 cells where GW6471, a PPAR-α antagonist, blunted OEA activity on the TGF-β1 signalling pathway and associated pro-inflammatory and fibrotic patterns. Our findings revealed that OEA counteracts kidney injury by controlling inflammation and fibrosis, making it an effective therapeutic tool for limiting AKI to CKD progression.

Animal Models of Kidney Disease: Challenges and Perspectives

Kidney disease is highly prevalent and affects approximately 850 million people worldwide. It is also associated with high morbidity and mortality, and current therapies are incurable and often ineffective. Animal models are indispensable for understanding the pathophysiology of various kidney diseases and for preclinically testing novel remedies. In the last two decades, rodents continue to be the most used models for imitating human kidney diseases, largely because of the increasing availability of many unique genetically modified mice. Despite many limitations and pitfalls, animal models play an essential and irreplaceable role in gaining novel insights into the mechanisms, pathologies, and therapeutic targets of kidney disease. In this review, we highlight commonly used animal models of kidney diseases by focusing on experimental AKI, CKD, and diabetic kidney disease. We briefly summarize the pathological characteristics, advantages, and drawbacks of some widely used models. Emerging animal models such as mini pig, salamander, zebrafish, and drosophila, as well as human-derived kidney organoids and kidney-on-a-chip are also discussed. Undoubtedly, careful selection and utilization of appropriate animal models is of vital importance in deciphering the mechanisms underlying nephropathies and evaluating the efficacy of new treatment options. Such studies will provide a solid foundation for future diagnosis, prevention, and treatment of human kidney diseases.

Gut microbiota dysbiosis in AKI to CKD transition

BACKGROUND AND AIM

The symptoms of acute kidney injury (AKI) include a sudden drop-in glomerular filtration rate (GFR), a rise in serum creatinine (sCr), blood urea nitrogen (BUN), and electrolytes, which leads to a rapid loss of kidney function. Chronic kidney disease progresses when AKI symptoms persist for over three months or 90 days. Numerous prevalent secondary risk factors, including diabetes, hypertension, obesity, and heart illness, are directly or indirectly linked to the development of AKI and the switch from AKI to CKD. Recently, the change of intestinal bacteria known as "gut dysbiosis" has been linked to distant organ dysfunction, including the heart, lungs, kidneys, and brain. Indirectly or directly, gut dysbiosis contributes to the progression of CKD and AKI. However, the effects of gut dysbiosis and the mechanism of action in the progression from AKI to CKD are unknown or need further investigation. The mechanism by which gut dysbiosis initiates AKI's progression to CKD should be explicitly concerned. The review primarily focuses on the action of gut dysbiosis in kidney disease, the effects of dysbiosis, the characterisation of dysbiosis and its pathogenic products, the various pathogenic routes and mechanism involved in expediting the transition from AKI to CKD.

CONCLUSION

We identified and briefly reviewed the impacts of dysbiosis in various situations such as hypoxia, mitochondrial induced reactive oxygen species (mtROS), aryl hydrocarbon receptor (AhR) activation and microbiota derived uremic toxemic substances profoundly to push AKI to CKD conditions.

Long-term outcomes of acute kidney injury in children

PURPOSE OF REVIEW

Acute kidney injury (AKI) affects up to 35% of all critically ill children and is associated with substantial short-term morbidity and mortality. However, the link between paediatric AKI and long-term adverse outcomes remains incompletely understood. This review highlights the most recent clinical data supporting the role of paediatric AKI as a risk factor for long-term kidney and cardiovascular consequences. In addition, it stresses the need for long-term surveillance of paediatric AKI survivors.

RECENT FINDINGS

Recent large-scale studies have led to an increasing understanding that paediatric AKI is a significant risk factor for adverse outcomes such as hypertension, cardiovascular disease and chronic kidney disease (CKD) over time. These long-term sequelae of paediatric AKI are most often observed in vulnerable populations, such as critically ill children, paediatric cardiac surgery patients, children who suffer from severe infections and paediatric cancer patients.

SUMMARY

A growing body of research has shown that paediatric AKI is associated with long-term adverse outcomes such as CKD, hypertension and cardiovascular disease. Although therapeutic pathways tailored to individual paediatric AKI patients are yet to be validated, we provide a framework to guide monitoring and prevention in children at the highest risk for developing long-term kidney dysfunction.

Renalase: a novel regulator of cardiometabolic and renal diseases

Renalase is a ~38 kDa flavin-adenine dinucleotide (FAD) domain-containing protein that can function as a cytokine and an anomerase. It is emerging as a novel regulator of cardiometabolic diseases. Expressed mainly in the kidneys, renalase has been reported to have a hypotensive effect and may control blood pressure through regulation of sympathetic tone. Furthermore, genetic variations in the renalase gene, such as a functional missense polymorphism (Glu37Asp), have implications in the cardiovascular and renal systems and can potentially increase the risk of cardiometabolic disorders. Research on the physiological functions and biochemical actions of renalase over the years has indicated a role for renalase as one of the key proteins involved in various disease states, such as diabetes, impaired lipid metabolism, and cancer. Recent studies have identified three transcription factors (viz., Sp1, STAT3, and ZBP89) as key positive regulators in modulating the expression of the human renalase gene. Moreover, renalase is under the post-transcriptional regulation of two microRNAs (viz., miR-29b, and miR-146a), which downregulate renalase expression. While renalase supplementation may be useful for treating hypertension, inhibition of renalase signaling may be beneficial to patients with cancerous tumors. However, more incisive investigations are required to unravel the potential therapeutic applications of renalase. Based on the literature pertaining to the function and physiology of renalase, this review attempts to consolidate and comprehend the role of renalase in regulating cardiometabolic and renal disorders.

Survival and recovery modeling of acute kidney injury in critically ill adults

Objectives:

Acute kidney injury is common among the critically ill. However, the incidence, medication use, and outcomes of acute kidney injury have been variably described. We conducted a single-center, retrospective cohort study to examine the risk factors and correlates associated with acute kidney injury in critically ill adults with a particular focus on medication class usage.

Methods:

We reviewed the electronic medical records of all adult patients admitted to an intensive care unit between 1 February and 30 August 2020. Acute kidney injury was defined by the 2012 Kidney Disease: Improving Global Outcomes guidelines. Data included were demographics, comorbidities, symptoms, laboratory parameters, interventions, and outcomes. The primary outcome was acute kidney injury incidence. A Least Absolute Shrinkage and Selection Operator regression model was used to determine risk factors associated with acute kidney injury. Secondary outcomes including acute kidney injury recovery and intensive care unit mortality were analyzed using a Cox regression model.

Results:

Among 226 admitted patients, 108 (47.8%) experienced acute kidney injury. 37 (34.3%), 39 (36.1%), and 32 patients (29.6%) were classified as acute kidney injury stages I–III, respectively. Among the recovery and mortality cohorts, analgesics/sedatives, anti-infectives, and intravenous fluids were significant (p-value < 0.05). The medication classes IV-fluid electrolytes nutrition (96.7%), gastrointestinal (90.2%), and anti-infectives (81.5%) were associated with an increased odds of developing acute kidney injury, odd ratios: 1.27, 1.71, and 1.70, respectively. Cox regression analyses revealed a significantly increased time-varying mortality risk for acute kidney injury-stage III, hazard ratio: 4.72 (95% confidence interval: 1–22.33). In the recovery cohort, time to acute kidney injury recovery was significantly faster in stage I, hazard ratio: 9.14 (95% confidence interval: 2.14–39.06) cohort when compared to the stage III cohort.

Conclusion:

Evaluation of vital signs, laboratory, and medication use data may be useful to determine acute kidney injury risk stratification. The influence of particular medication classes further impacts the risk of developing acute kidney injury, necessitating the importance of examining pharmacotherapeutic regimens for early recognition of renal impairment and prevention.

Klotho and Mesenchymal Stem Cells: A Review on Cell and Gene Therapy for Chronic Kidney Disease and Acute Kidney Disease

Chronic kidney disease (CKD) and acute kidney injury (AKI) are public health problems, and their prevalence rates have increased with the aging of the population. They are associated with the presence of comorbidities, in particular diabetes mellitus and hypertension, resulting in a high financial burden for the health system. Studies have indicated Klotho as a promising therapeutic approach for these conditions. Klotho reduces inflammation, oxidative stress and fibrosis and counter-regulates the renin-angiotensin-aldosterone system. In CKD and AKI, Klotho expression is downregulated from early stages and correlates with disease progression. Therefore, the restoration of its levels, through exogenous or endogenous pathways, has renoprotective effects. An important strategy for administering Klotho is through mesenchymal stem cells (MSCs). In summary, this review comprises in vitro and in vivo studies on the therapeutic potential of Klotho for the treatment of CKD and AKI through the administration of MSCs.

Harnessing the Physiological Functions of Cellular Prion Protein in the Kidneys: Applications for Treating Renal Diseases

A cellular prion protein (PrP^C) is a ubiquitous cell surface glycoprotein, and its physiological functions have been receiving increased attention. Endogenous PrP^C is present in various kidney tissues and undergoes glomerular filtration. In prion diseases, abnormal prion proteins are found to accumulate in renal tissues and filtered into urine. Urinary prion protein could serve as a diagnostic biomarker. PrP^C plays a role in cellular signaling pathways, reno-protective effects, and kidney iron uptake. PrP^C signaling affects mitochondrial function via the ERK pathway and is affected by the regulatory influence of microRNAs, small molecules, and signaling proteins. Targeting PrP^C in acute and chronic kidney disease could help improve iron homeostasis, ameliorate damage from ischemia/reperfusion injury, and enhance the efficacy of mesenchymal stem/stromal cell or extracellular vesicle-based therapeutic strategies. PrP^C may also be under the influence of BMP/Smad signaling and affect the progression of TGF-β-related renal fibrosis. PrP^C conveys TNF-α resistance in some renal cancers, and therefore, the coadministration of anti-PrP^C antibodies improves chemotherapy. PrP^C can be used to design antibody-drug conjugates, aptamer-drug conjugates, and customized tissue inhibitors of metalloproteinases to suppress cancer. With preclinical studies demonstrating promising results, further research on PrP^C in the kidney may lead to innovative PrP^C-based therapeutic strategies for renal disease.

Association of Serum Zinc Concentration with Preservation of Renal Function After Bariatric Surgery: a Retrospective Pilot Study

BACKGROUND

Although serum zinc level (Zn) is known to impact renal function in patients with diabetes, their correlation following bariatric surgery remains unknown. This study aimed at assessing the association of Zn with estimated glomerular filtration rate (eGFR) after laparoscopic sleeve gastrectomy (LSG).

METHODS

One hundred and twenty-nine patients in total (mean age, 38.1 ± 10.8; body mass index, 39.1 ± 5.1 kg/m²) with normal preoperative kidney function undergoing LSG at a single tertiary referral center were reviewed. The primary study endpoint was the relationship between Zn and post-LSG eGFR at 12-month follow-up. The secondary outcomes were the associations of percentage weight loss (%WL) with changes in Zn (△Zn) and eGFR (△eGFR).

RESULTS

The incidence of zinc deficiency was 8.5%, 8.1%, and 29.9% at baseline, post-LSG and one- and 12-month follow-up, respectively. At 12-month follow-up, Zn dropped from 104.1 ± 19.2 to 85.3 ± 38.9 μg/dL (p = 0.001), while eGFR levels decreased from 106.6 ± 10.3 to 102.1 ± 19.4 mL/min per 1.73 m² (p = 0.025). Zn correlated positively with eGFR at 6-month (r = 0.252, p = 0.037) and 12-month (r = 0.41, p = 0.001) follow-ups. Multiple linear regression analyses including baseline variables of age, sex, BMI, %WL, and diabetes identified Zn and %WL as independent predictors of eGFR at 12-month follow-up. There was no evidence of multicollinearity among these variables. Despite positive association between %WL and △eGFR (r = 0.222, p = 0.031), no correlation was noted between %WL and △Zn (r = - 0.129, p = 0.40).

CONCLUSION

The results demonstrated a positive relationship between post-LSG serum zinc levels and preservation of renal function among patients with obesity in a surgical setting. Large-scale studies are warranted to support the findings.

Pulsed focused ultrasound enhances the therapeutic effect of mesenchymal stromal cell-derived extracellular vesicles in acute kidney injury

BACKGROUND

Acute kidney injury (AKI) is characterized by rapid failure of renal function and has no curative therapies. Mesenchymal stromal cell (MSC)-derived extracellular vesicles (EVs) are known to carry therapeutic factors, which have shown promise in regenerative medicine applications, including AKI. However, there remains an unmet need to optimize their therapeutic effect. One potential avenue of optimization lies in pulsed focused ultrasound (pFUS), where tissues-of-interest are treated with sound waves. pFUS has been shown to enhance MSC therapy via increased cell homing, but its effects on cell-free EV therapy remain largely unexplored.

METHODS

We combine pFUS pretreatment of the kidney with MSC-derived EV therapy in a mouse model of cisplatin-induced AKI.

RESULTS

EVs significantly improved kidney function, reduced injury markers, mediated increased proliferation, and reduced inflammation and apoptosis. While pFUS did not enhance EV homing to the kidney, the combined treatment resulted in a superior therapeutic effect compared to either treatment alone. We identified several molecular mechanisms underlying this synergistic therapeutic effect, including upregulation of proliferative signaling (MAPK/ERK, PI3K/Akt) and regenerative pathways (eNOS, SIRT3), as well as suppression of inflammation.

CONCLUSION

Taken together, pFUS may be a strategy for enhancing the therapeutic efficacy of MSC-derived EV treatment for the treatment of AKI.

Emerging role of lncRNAs in renal fibrosis

Fibrosis is the final common pathological feature of a wide variety of chronic kidney disease (CKD). However, an understanding of the mechanisms underlying the development of renal fibrosis remains challenging and controversial. As the current focus of molecular research, noncoding RNAs (ncRNAs), mainly microRNAs (miRNAs), long noncoding RNAs (lncRNAs) and circular noncoding RNAs (circRNAs), have powerful and abundant biological functions, which essentially makes them mediators of the physiological and pathological processes of various system diseases. The role of ncRNAs in renal fibrosis has also received great attention in recent years, but most research has mainly focused on miRNAs. In fact, although a large number of studies of lncRNAs have emerged recently, the role these molecules play in renal fibrosis haven't been fully understood till now. Thus, this review discusses the discovery of lncRNAs and their biological functions in different types of renal fibrosis, as well as the imminent applications of these findings in clinical use. Undoubtedly, in the future, further understanding of the function of all types of lncRNAs will reveal large breakthroughs in the treatment of renal fibrosis.

Reversing Acute Kidney Injury Using Pulsed Focused Ultrasound and MSC Therapy: A Role for HSP-Mediated PI3K/AKT Signaling

Acute kidney injury (AKI) is characterized by a sudden failure of renal function, but despite increasing worldwide prevalence, current treatments are largely supportive, with no curative therapies. Mesenchymal stromal cell (MSC) therapy has been shown to have a promising regenerative effect in AKI but is limited by the ability of cells to home to damaged tissue. Pulsed focused ultrasound (pFUS), wherein target tissues are sonicated by short bursts of sound waves, has been reported to enhance MSC homing by upregulating local homing signals. However, the exact mechanism by which pFUS enhances MSC therapy remains insufficiently explored. In this study, we studied the effect of bone marrow-derived MSCs (BM-MSCs), in conjunction with pFUS, in a mouse model of cisplatin-induced AKI. Here, BM-MSCs improved kidney function, reduced histological markers of kidney injury, decreased inflammation and apoptosis, and promoted cellular proliferation. Surprisingly, whereas pFUS did not upregulate local cytokine expression or improve BM-MSC homing, it did potentiate the effect of MSC treatment in AKI. Further analysis linked this effect to the upregulation of heat shock protein (HSP)20/HSP40 and subsequent phosphatidylinositol 3-kinase (PI3K)/Akt signaling. In summary, our results suggest that pFUS and BM-MSCs have independent as well as synergistic therapeutic effects in the context of AKI.

Incidence, Risk Factors, and Outcomes of Transition of Acute Kidney Injury to Chronic Kidney Disease in Cirrhosis: A Prospective Cohort Study

Transition to chronic kidney disease (CKD) after an episode of acute kidney injury (AKI) is known in patients without cirrhosis. We studied the incidence and risk factors for development of CKD in patients with cirrhosis. Competing risk analysis was performed to identify risk factors for CKD development. Of 818 patients with cirrhosis (age, 50.4 ± 11.8 years; 84% males; Model for End-Stage Liver Disease [MELD], 19.9 ± 9.9), 36% had AKI at enrollment, 27% had previous AKI, and 61% developed new episodes of AKI during the follow-up period. CKD developed in 269 (33%) patients. Serum cystatin C (CysC; subdistribution hazard ratio [SHR], 1.58; 1.07-2.33), episodes of previous AKI (SHR, 1.26; 1.02-1.56), and AKI stage at enrollment (no AKI [SHR, 1] vs. stage 1 [SHR, 3.28; 1.30-8.25] vs. stage 2 [SHR, 4.33; 1.76-10.66] vs. stage 3 [SHR, 4.5; 1.59-12.73]) were identified as baseline risk factors for CKD development. On time-varying competing risk analysis, MELD (SHR, 1.01; 1.00-1.03), number of AKI episodes (SHR, 1.25; 1.15-1.37), and CysC (SHR, 1.38; 1.01-1.89) predicted CKD development. Development of CKD was associated with higher risk of death. Reduction in glomerular filtration rate (GFR) not meeting CKD criteria was observed in 66% of patients with cirrhosis, more so in those with previous AKI episodes and a high CysC level and MELD score. Renal histology, available in 55 patients, showed tubulointerstitial injury in 86%, cholemic nephrosis in 29%, and glomerular changes in 38%. Conclusion: Almost two-thirds of patients with cirrhosis develop episodes of AKI and reduction in GFR; one-third progress to CKD, resulting in adverse outcomes. Higher MELD and CysC levels and number of AKI episodes predict development of CKD in patients with cirrhosis.

Current understanding of the administration of mesenchymal stem cells in acute kidney injury to chronic kidney disease transition: a review with a focus on preclinical models

Incomplete recovery from acute kidney injury (AKI) can result in long-term functional deficits and has been recognized as a major contributor to chronic kidney disease (CKD), which is termed the AKI-CKD transition. Currently, an effective intervention for this disorder is still lacking. Principally, therapeutic strategies targeting the AKI-CKD transition can be divided into those reducing the severity of AKI or promoting the regenerative process towards beneficially adaptive repair pathways. Considering the fact that mesenchymal stem cells (MSCs) have the potential to address both aspects, therapeutic regimens based on MSCs have a promising future. In light of this information, we focus on the currently available evidence associated with MSC therapy involved in the treatment of the AKI-CKD transition and the underlying mechanisms. All of these discussions will contribute to the establishment of a reliable therapeutic strategy for patients with this problem, who can be easily ignored by physicians, and will lead to a better clinical outcome for them.

Impact of serum uric acid on renal function after bariatric surgery: a retrospective study

BACKGROUND

Despite a known negative association between serum uric acid level (SUA) and renal function, this correlation in patients after bariatric surgery remains unknown.

OBJECTIVE

To assess correlation between postoperative SUA and estimated glomerular filtration rate (eGFR) at 12 months after bariatric surgery.

SETTING

A single tertiary referral center.

METHODS

A total of 252 patients (age = 40.5 ± 11.2; body mass index = 39.0 ± 5.5 kg/m²) undergoing bariatric surgery divided into 2 groups (i.e., normal renal function [90 ≤ eGFR < 125 mL/min/1.73 m², n = 176] versus renal function impairment [eGFR < 90 mL/min/1.73 m², n = 76]) were assessed for relationships between SUA and eGFR in both groups (primary endpoint) and associations of percentage weight loss with changes in SUA (△SUA) and eGFR (△eGFR) for all patients (secondary endpoint) at 12 months.

RESULTS

Overall, prevalence of hyperuricemia was 40.4% and 22.2% (baseline and postoperative 12 mo, respectively). Reverse relationship was observed between SUA and eGFR (r = -.152, P = .007) for all patients with no association noted between baseline SUA and eGFR in each group as well as between SUA and eGFR at 12 months in the normal group (r = -.076, P = .437). The reverse relationship was found (r = -.417, P = .005) in renal function impairment group for whom SUA was identified as a predictor of eGFR at 12 months. There was no association of percentage weight loss with △SUA (r = .089, P = .601) and △eGFR (r = -.046, P = .785).

CONCLUSION

The results demonstrated a negative relationship between postoperative SUA and renal function in patients with preexisting renal dysfunction undergoing bariatric surgery. Clinical significance of our findings warrants further investigation.

Predictores de progresión de enfermedad renal en el paciente anciano

El riñón del anciano experimenta cambios estructurales y funcionales, que lo convierte en más vulnerable para la enfermedad renal. La mayoría de ancianos con enfermedad renal crónica fallece antes de desarrollar progresión renal. Sin embargo, el principal grupo de pacientes incidentes de nefropatía terminal es el de personas mayores de 65 años, representando la diabetes mellitus y las causas vasculares sus principales etiologías. En esta revisión se analizan elementos renales (filtrado glomerular, proteinuria/albuminuria, potasio, fracaso renal agudo y diuréticos) y factores geriátricos (estado funcional, cognitivo y fragilidad) como predictores de progresión de enfermedad renal. La identificación de estos factores contribuirá a establecer estrategias de prevención renal y al pronóstico de la enfermedad en la toma decisiones.

Establishing Surrogate Kidney End Points for Lupus Nephritis Clinical Trials: Development and Validation of a Novel Approach to Predict Future Kidney Outcomes

OBJECTIVE

End points currently used in lupus nephritis (LN) clinical trials lack uniformity and questionably reflect long-term kidney survival. This study was undertaken to identify short-term end points that predict long-term kidney outcomes for use in clinical trials.

METHODS

A database of 944 patients with LN was assembled from 3 clinical trials and 12 longitudinal cohorts. Variables from the first 12 months of treatment after diagnosis of active LN (prediction period) were assessed as potential predictors of long-term outcomes in a 36-month follow-up period. The long-term outcomes examined were new or progressive chronic kidney disease (CKD), severe kidney injury (SKI), and the need for permanent renal replacement therapy (RRT). To predict the risk for each outcome, hazard index tools (HITs) were derived using multivariable analysis with Cox proportional hazards regression.

RESULTS

Among 550 eligible subjects, 54 CKD, 55 SKI, and 22 RRT events occurred. Variables in the final CKD HIT were prediction-period CKD status, 12-month proteinuria, and 12-month serum creatinine level. The SKI HIT variables included prediction-period CKD status, International Society of Nephrology (ISN)/Renal Pathology Society (RPS) class, 12-month proteinuria, 12-month serum creatinine level, race, and an interaction between ISN/RPS class and 12-month proteinuria. The RRT HIT included age at diagnosis, 12-month proteinuria, and 12-month serum creatinine level. Each HIT validated well internally (c-indices 0.84-0.92) and in an independent LN cohort (c-indices 0.89-0.92).

CONCLUSION

HITs, derived from short-term kidney responses to treatment, correlate with long-term kidney outcomes, and now must be validated as surrogate end points for LN clinical trials.

Acute Kidney Injury in Pregnancy: The Need for Higher Awareness. A Pragmatic Review Focused on What Could Be Improved in the Prevention and Care of Pregnancy-Related AKI, in the Year Dedicated to Women and Kidney Diseases

Pregnancy-related acute kidney injury (pAKI), preeclampsia (PE), and the hypertensive disorders of pregnancy are closely related conditions, which are, in turn, frequently linked to pre-existing and often non-diagnosed chronic kidney disease (CKD). The current literature and research mainly underline the effects of pregnancy complications on the offspring; this review strongly emphasizes the maternal health as well. These conditions not only negatively affect pregnancy outcomes, but have a relevant effect on the future health of affected mothers and their children. Therefore, dedicated diagnostic and follow-up programs are needed, for optimizing materno-foetal health and reducing the impact of pregnancy-related problems in the mothers and in the new generations. This narrative review, performed on the occasion of the 2018 World Kidney Day dedicated to women's health, focuses on three aspects of the problem. Firstly, the risk of AKI in the hypertensive disorders of pregnancy (the risk is the highest in developing countries; however PE is the main cause of pregnancy related AKI worldwide). Secondly, the effect of AKI and the hypertensive disorders of pregnancy on the development of CKD in the mother and offspring: long-term risks are increased; the entity and the trajectories are still unknown. Thirdly, the role of CKD in the pathogenesis of AKI and the hypertensive disorders of pregnancy: CKD is a major risk factor and the most important element in the differential diagnosis; pregnancy is a precious occasion for early diagnosis of CKD. Higher awareness on the importance of AKI in pregnancy is needed to improve short and long term outcomes in mothers and children.

Kidney disease models: tools to identify mechanisms and potential therapeutic targets

Acute kidney injury (AKI) and chronic kidney disease (CKD) are worldwide public health problems affecting millions of people and have rapidly increased in prevalence in recent years. Due to the multiple causes of renal failure, many animal models have been developed to advance our understanding of human nephropathy. Among these experimental models, rodents have been extensively used to enable mechanistic understanding of kidney disease induction and progression, as well as to identify potential targets for therapy. In this review, we discuss AKI models induced by surgical operation and drugs or toxins, as well as a variety of CKD models (mainly genetically modified mouse models). Results from recent and ongoing clinical trials and conceptual advances derived from animal models are also explored.

Serum Cystatin C Predicts AKI and the Prognosis of Patients in Coronary Care Unit: a Prospective, Observational Study

BACKGROUND/AIMS

Acute Kidney Injury (AKI) is a serious clinical state associated with high morbidity and mortality, particularly in critical ill patients. We investigated the hypothesis that serum Cystatin C (sCysC) is a good predictor for AKI and may affect the short-term prognosis of coronary care unit (CCU) patients.

METHODS

In this prospective, observational study, we screened 412 adults admitted to the CCU from January 1, 2014 to June 1, 2015 at Zhongnan Hospital of Wuhan University. Serum samples were obtained at the time of admission, and sCysC was quantified through nephelometry. AKI was defined based on KDIGO-AKI criteria. After the patients' hospital discharge, the survivors in this study were followed up for up to 2 years. The primary endpoint was the incidence of AKI stratified by severity stage, while the second endpoints included 2-year mortality, rehospitalization and failure in renal recovery rates, as well as the progression of AKI to CKD.

RESULTS

According to the KDIGO-AKI criteria, AKI occurred in 130 (31.6%) patients. After multivariate adjustments, the highest quartile of sCysC was associated with a 9-fold increased risk of incident AKI compared with the lowest quartile. For predicting AKI, sCysC [area under the receiver operating characteristic curve (AUC=0.842)] outperformed β2-micro globulin (AUC=0.813) and the clinical model (AUC=0.777), and a cutoff of 1.255 mg/L yielded good sensitivity and specificity. After a median 19.8-month follow-up, 112 (27.2%) patients died within 2 years after admission. The sCysC independently predicted the risk of 2-year mortality [adjusted odds ratio (OR), 4.955; 95% confidence interval (95% CI), 2.853 to 8.603] and rehospitalization (OR, 3.128; 95% CI, 2.011 to 4.867), as well as renal recovery failure (OR, 3.618, 95% CI, 1.753 to 7.463).

CONCLUSIONS

Serum CysC is a strong predictor of AKI and the short-term prognosis of CCU patients.

Global kidney health 2017 and beyond: a roadmap for closing gaps in care, research, and policy

The global nephrology community recognises the need for a cohesive plan to address the problem of chronic kidney disease (CKD). In July, 2016, the International Society of Nephrology hosted a CKD summit of more than 85 people with diverse expertise and professional backgrounds from around the globe. The purpose was to identify and prioritise key activities for the next 5-10 years in the domains of clinical care, research, and advocacy and to create an action plan and performance framework based on ten themes: strengthen CKD surveillance; tackle major risk factors for CKD; reduce acute kidney injury-a special risk factor for CKD; enhance understanding of the genetic causes of CKD; establish better diagnostic methods in CKD; improve understanding of the natural course of CKD; assess and implement established treatment options in patients with CKD; improve management of symptoms and complications of CKD; develop novel therapeutic interventions to slow CKD progression and reduce CKD complications; and increase the quantity and quality of clinical trials in CKD. Each group produced a prioritised list of goals, activities, and a set of key deliverable objectives for each of the themes. The intended users of this action plan are clinicians, patients, scientists, industry partners, governments, and advocacy organisations. Implementation of this integrated comprehensive plan will benefit people who are at risk for or affected by CKD worldwide.

The Role of Acute Kidney Injury in Chronic Kidney Disease

There is increasing recognition that acute kidney injury (AKI) and chronic kidney disease (CKD) are closely linked and likely promote one another. Underlying CKD now is recognized as a clear risk factor for AKI because both decreased glomerular filtration rate and increased proteinuria have been shown to be associated strongly with AKI. A growing body of literature also provides evidence that AKI accelerates the progression of CKD. Individuals who suffered dialysis-requiring AKI are particularly vulnerable to worse long-term renal outcomes, including end-stage renal disease. The association between AKI and subsequent renal function decline is amplified by pre-existing severity of CKD, higher stage of AKI, and the cumulative number of AKI episodes. However, residual confounding and ascertainment bias may partly explain the epidemiologic association between AKI and CKD in observational studies. As the number of AKI survivors increases, we need to better understand other clinically important outcomes after AKI, identify those at highest risk for the most adverse sequelae, and develop strategies to optimize their care.

High Risk of Herpes Zoster among Patients with Advance Acute Kidney Injury--A Population-Based Study

The risk for herpes zoster (HZ) in acute kidney injury (AKI) survivors was never explored. We identified 2,387 adults in the Taiwan National Health Insurance Research Database who recovered from dialysis-requiring AKI and matched them with non-recovery and non-AKI patients by propensity score. During a mean follow-up of 2.7 years, the incidences of HZ were 6.9, 8.2 and 4.8 episodes per 1,000 person-years in AKI-non-recovery, AKI-recovery and non-AKI group, respectively. The recovery group was more likely to develop herpes zoster than those without acute kidney injury [incidence-rate ratios 1.71, 95% confidence interval 1.16-2.52; p = 0.007]. Patients without acute kidney injury were less likely to develop herpes zoster than those AKI, recovered from dialysis or not (hazard ratio HR 0.66, 95% CI 0.46-0.95). Dialysis-requiring acute kidney injury poses a long-term risk of herpes zoster after hospital discharge. Even patients who have recovered from dialysis still carry a significantly higher risk of developing herpes zoster.

[Long-term outcomes of children treated with continuous renal replacement therapy]

INTRODUCTION

The objective of this study is to analyze long-term outcomes and kidney function in children requiring continuous renal replacement therapy (CRRT) after an acute kidney injury episode.

PATIENTS AND METHODS

A retrospective observational study was performed using a prospective database of 128 patients who required CRRT admitted to the pediatric intensive care unit between years 2006 and 2012. The subsequent outcomes were assessed in those surviving at hospital discharge.

RESULTS

Of the 128 children who required RRT in the pediatric intensive care unit, 71 survived at hospital discharge (54.4%), of whom 66 (92.9%) were followed up. Three patients had chronic renal failure prior to admission to the NICU. Of the 63 remaining patients, 6 had prolonged or relapses of renal function disturbances, but only one patient with atypical Hemolytic Uremic Syndrome developed end-stage renal failure. The rest had normal kidney function at the last check-up.

CONCLUSIONS

Most of surviving children that required CRRT have a positive outcome later on, presenting low mortality rates and recovery of kidney function in the medium term.

Cisplatinum nephrotoxicity in oncology therapeutics: retrospective review of patients treated between 2005 and 2012

BACKGROUND

Cisplatinum (CP) is associated with acute kidney injury. The aim of this study was to define the spectrum of CP-induced nephrotoxicity in current practice.

CASE-DIAGNOSIS/TREATMENT

A single-center, retrospective chart review was performed on children who received CP for treatment of a malignancy at the Hassenfeld Children's Center for Blood and Cancer Disorders of NYU Langone Medical Center between 2005 and 2012. Patients were considered to have nephrotoxicity if they had: (1) a decrease in estimated glomerular filtration rate (eGFR) of ≥30 % or (2) a decline in serum magnesium of ≥0.2 meq/L or (3) a decline in serum potassium of ≥0.2 meq/L. Thirty-two patients (mean age 8.0 ± 7.0 years) were included in this review, of whom 21 had a brain tumor (BT) and 11 had an osteosarcoma (OS); 31 (97 %) of the patients had a disturbance in renal function. The mean reduction in eGFR, serum magnesium and potassium was 37 ± 17, 30 ± 16 and 25 ± 14 %, respectively. The decline in eGFR, hypomagnesemia and hypokalemia was persistent in 38, 60 and 40 % of cases, respectively, through the short-term follow-up period. No patients required dialysis.

CONCLUSIONS

Nearly all patients receiving CP in current care experience modest glomerular and tubular injury. The abnormalities persist in 40-60 % of cases during the short-term recovery period after CP treatment.

The impact of acute kidney injury on the long-term risk of stroke

BACKGROUND

The incidence of acute kidney injury (AKI) requiring dialysis in hospitalized patients is increasing; however, information on the long-term incidence of stroke in patients surviving to discharge after recovering from AKI after dialysis has not been reported.

METHODS AND RESULTS

Patients that survived after recovery from dialysis-requiring AKI during index hospitalizations from 1999 to 2008 were identified in nationwide administrative registries. The risk of de novo stroke and death were analyzed with time-varying Cox proportional hazard models. The results were validated by a critical care database. We enrolled 4315 patients in the AKI-recovery group (men, 57.7%; mean age, 62.8±16.8 years) and matched 4315 control subjects as the non-AKI group by propensity scores. After a median follow-up period of 3.36 years, the incident stroke rate was 15.6 per 1000 person-years. The AKI-recovery group had higher risk (hazard ratio: 1.25; P=0.037) and higher severity of stroke events than the non-AKI group, regardless of progression to subsequent chronic kidney disease. The rate of incident stroke was not statistically different in those with diabetes alone (without AKI) and in those with AKI alone (without diabetes) after hospital discharge (P=0.086). Furthermore, the risk of mortality in the AKI-recovery group was higher than in the non-AKI group (hazard ratio: 2.4; P<0.001).

CONCLUSIONS

The patients who recovered from AKI had a higher incidence of developing incident stroke and mortality than the patients without AKI, and the impact was similar to diabetes. Our results suggest that a public health initiative is needed to enhance postdischarge follow-up of renal function and to control the subsequent incidence of stroke among patients who recover from AKI after dialysis.

Long-term risk of coronary events after AKI

The incidence rate of AKI in hospitalized patients is increasing. However, relatively little attention has been paid to the association of AKI with long-term risk of adverse coronary events. Our study investigated hospitalized patients who recovered from de novo dialysis-requiring AKI between 1999 and 2008 using patient data collected from inpatient claims from Taiwan National Health Insurance. We used Cox regression with time-varying covariates to adjust for subsequent CKD and ESRD after discharge. Results were further validated by analysis of a prospectively constructed database. Among 17,106 acute dialysis patients who were discharged, 4869 patients recovered from dialysis-requiring AKI (AKI recovery group) and were matched with 4869 patients without AKI (non-AKI group). The incidence rates of coronary events were 19.8 and 10.3 per 1000 person-years in the AKI recovery and non-AKI groups, respectively. AKI recovery associated with higher risk of coronary events (hazard ratio [HR], 1.67; 95% confidence interval [95% CI], 1.36 to 2.04) and all-cause mortality (HR, 1.67; 95% CI, 1.57 to 1.79) independent of the effects of subsequent progression to CKD and ESRD. The risk levels of de novo coronary events after hospital discharge were similar in patients with diabetes alone and patients with AKI alone (P=0.23). Our results reveal that AKI with recovery associated with higher long-term risks of coronary events and death in this cohort, suggesting that AKI may identify patients with high risk of future coronary events. Enhanced postdischarge follow-up of renal function of patients who have recovered from temporary dialysis may be warranted.