Distant effects of experimental renal ischemia/reperfusion injury

Risk factors and early prediction of cardiorenal syndrome type 3 among acute kidney injury patients: a cohort study

BACKGROUND

Type 3 cardiorenal syndrome (CRS type 3) triggers acute cardiac injury from acute kidney injury (AKI), raising mortality in AKI patients. We aimed to identify risk factors for CRS type 3 and develop a predictive nomogram.

METHODS

In this retrospective study, 805 AKI patients admitted at the Department of Nephrology, Second Hospital of Shanxi Medical University from 1 January 2017, to 31 December 2021, were categorized into a study cohort (406 patients from 2017.1.1-2021.6.30, with 63 CRS type 3 cases) and a validation cohort (126 patients from 1 July 2021 to 31 Dec 2021, with 22 CRS type 3 cases). Risk factors for CRS type 3, identified by logistic regression, informed the construction of a predictive nomogram. Its performance and accuracy were evaluated by the area under the curve (AUC), calibration curve and decision curve analysis, with further validation through a validation cohort.

RESULTS

The nomogram included 6 risk factors: age (OR = 1.03; 95%CI = 1.009-1.052; p = 0.006), cardiovascular disease (CVD) history (OR = 2.802; 95%CI = 1.193-6.582; p = 0.018), mean artery pressure (MAP) (OR = 1.033; 95%CI = 1.012-1.054; p = 0.002), hemoglobin (OR = 0.973; 95%CI = 0.96--0.987; p < 0.001), homocysteine (OR = 1.05; 95%CI = 1.03-1.069; p < 0.001), AKI stage [(stage 1: reference), (stage 2: OR = 5.427; 95%CI = 1.781-16.534; p = 0.003), (stage 3: OR = 5.554; 95%CI = 2.234-13.805; p < 0.001)]. The nomogram exhibited excellent predictive performance with an AUC of 0.907 in the study cohort and 0.892 in the validation cohort. Calibration and decision curve analyses upheld its accuracy and clinical utility.

CONCLUSIONS

We developed a nomogram predicting CRS type 3 in AKI patients, incorporating 6 risk factors: age, CVD history, MAP, hemoglobin, homocysteine, and AKI stage, enhancing early risk identification and patient management.

Lymphocytes and innate immune cells in acute kidney injury and repair

Acute kidney injury (AKI) is a common and serious disease entity that affects native kidneys and allografts but for which no specific treatments exist. Complex intrarenal inflammatory processes driven by lymphocytes and innate immune cells have key roles in the development and progression of AKI. Many studies have focused on prevention of early injury in AKI. However, most patients with AKI present after injury is already established. Increasing research is therefore focusing on mechanisms of renal repair following AKI and prevention of progression from AKI to chronic kidney disease. CD4+ and CD8+ T cells, B cells and neutrophils are probably involved in the development and progression of AKI, whereas regulatory T cells, double-negative T cells and type 2 innate lymphoid cells have protective roles. Several immune cells, such as macrophages and natural killer T cells, can have both deleterious and protective effects, depending on their subtype and/or the stage of AKI. The immune system not only participates in injury and repair processes during AKI but also has a role in mediating AKI-induced distant organ dysfunction. Targeted manipulation of immune cells is a promising therapeutic strategy to improve AKI outcomes.

Bidirectional pressure: a mini review of ventilator-lung-kidney interactions

Acute kidney injury and respiratory failure that requires mechanical ventilation are both common complications of critical illnesses. Failure of either of these organ systems also increases the risk of failure to the other. As a result, there is a high incidence of patients with concomitant acute kidney injury and the need for mechanical ventilation, which has a devasting impact on intensive care unit outcomes, including mortality. Despite decades of research into the mechanisms of ventilator-lung-kidney interactions, several gaps in knowledge remain and current treatment strategies are primarily supportive. In this review, we outline our current understanding of the mechanisms of acute kidney injury due to mechanical ventilation including a discussion of; 1) The impact of mechanical ventilation on renal perfusion, 2) activation of neurohormonal pathways by positive pressure ventilation, and 3) the role of inflammatory mediators released during ventilator induced lung injury. We also provide a review of the mechanisms by which acute kidney injury increases the risk of respiratory failure. Next, we outline a summary of the current therapeutic approach to preventing lung and kidney injury in the critically ill, including fluid and vasopressor management, ventilator strategies, and treatment of acute kidney injury. Finally, we conclude with a discussion outlining opportunities for novel investigations that may provide a rationale for new treatment approaches.

Disruption in glutathione metabolism and altered energy production in the liver and kidney after ischemic acute kidney injury in mice

Acute kidney injury (AKI) is a systemic disease that affects energy metabolism in various remote organs in murine models of ischemic AKI. However, AKI-mediated effects in the liver have not been comprehensively assessed. After inducing ischemic AKI in 8-10-week-old, male C57BL/6 mice, mass spectrometry metabolomics revealed that the liver had the most distinct phenotype 24 h after AKI versus 4 h and 7 days. Follow up studies with in vivo [13C6]-glucose tracing on liver and kidney 24 h after AKI revealed 4 major findings: (1) increased flux through glycolysis and the tricarboxylic (TCA) cycle in both kidney and liver; (2) depleted hepatic glutathione levels and its intermediates despite unchanged level of reactive oxygen species, suggesting glutathione consumption exceeds production due to systemic oxidative stress after AKI; (3) hepatic ATP depletion despite unchanged rate of mitochondrial respiration, suggesting increased ATP consumption relative to production; (4) increased hepatic and renal urea cycle intermediates suggesting hypercatabolism and upregulation of the urea cycle independent of impaired renal clearance of nitrogenous waste. Taken together, this is the first study to describe the hepatic metabolome after ischemic AKI in a murine model and demonstrates that there is significant liver-kidney crosstalk after AKI.

Hippo pathway activated by circulating reactive oxygen species mediates cardiac diastolic dysfunction after acute kidney injury

Acute kidney injury (AKI) can cause distal cardiac dysfunction; however, the underlying mechanism is unknown. Oxidative stress is proved prominent in AKI-induced cardiac dysfunction, and a possible bridge role of oxidative-stress products in cardio-renal interaction has been reported. Therefore, this study aimed to investigate the critical role of circulating reactive oxygen species (ROS) in mediating cardiac dysfunction after bilateral renal ischemia-reperfusion injury (IRI). We observed the diastolic dysfunction in the mice following renal IRI, accompanied by reduced ATP levels, oxidative stress, and branched-chain amino acids (BCAA) accumulation in the heart. Notably, ROS levels showed a sequential increase in the kidneys, circulation, and heart. Treatment with tempol, an ROS scavenger, significantly restored cardiac diastolic function in the renal IRI mice, corroborating the bridge role of circulating ROS. Accumulating evidence has identified oxidative stress as upstream of Mst1/Hippo in cardiac injury, which could regulate the expression of downstream genes related to mitochondrial quality control, leading to lower ATP, higher ROS and metabolic disorder. To verify this, we examined the activation of the Mst1/Hippo pathway in the heart of renal IRI mice, which was alleviated by tempol treatment as well. In vitro, analysis revealed that Mst1-knockdown cardiomyocytes could be activated by hydrogen peroxide (H2O2). Analysis of Mst1-overexpression cardiomyocytes confirmed the critical role of the Mst1/Hippo pathway in oxidative stress and BCAA dysmetabolism. Therefore, our results indicated that circulating ROS following renal IRI activates the Mst1/Hippo pathway of myocardium, leading to cardiac oxidative stress and diastolic dysfunction. This finding provides new insights for the clinical exploration of improved treatment options for cardiorenal syndrome.

Does cardiac impairment develop in ischemic renal surgery in rats depending on the reperfusion time?

Background

Renal dysfunction is known to cause heart failure. However, renal dysfunction associated with kidney surgeries (mediated by reperfusion injury) that affects the cardiac physiological function, especially during the recovery and repair phase of renal surgery is unknown.

Method

Male Wistar rats (238 ± 18 g) were subjected to renal sham and ischemia-reperfusion (IR-bilateral clamping for 15 min/45 min and reperfusion for 24 h/48 h/7 days) surgeries. At the end of the experiment, the heart was isolated from the animal (to exclude neurohormonal influence) and perfused for 60 min with Krebs-Hanseleit buffer to study the physiological changes.

Result

Renal artery bilateral occlusion for 45 min that creates ischemia, followed by 24 h of reperfusion did not impart any significant cardiac physiological functional decline but 48 h of reperfusion exhibited a significant decline in cardiac hemodynamic indices (Rate pressure product in x104 mmHg*beats/min: Sham- 3.53 ± 0.19, I45_R48-2.82 ± 0.21) with mild tissue injury. However, 7 days of reperfusion inflict significant physiological decline (Rate pressure product in x104 mmHg*beats/min - 2.5 ± 0.14) and tissue injury (Injury score- 4 ± 1.5) in isolated rat hearts. Interestingly, when the renal artery bilateral occlusion time was reduced to 15 min the changes in the hearts were negligible after 7 days. Cellular level exploration reveals a positive relation between functional deterioration of mitochondria and elevated mitochondrial oxidative stress and inflammation with cardiac physiological decline and injury linked with renal ischemia-reperfusion surgery.

Conclusion

Cardiac functional decline associated with renal surgery is manifested during renal repair or recovery. This decline depends on cardiac mitochondrial health, which is negatively influenced by the renal IR mediators and kidney function.

Heart failure subtype after acute kidney injury

INTRODUCTION

Acute kidney injury (AKI) is associated with increased risk of heart failure (HF). Determining the type of HF experienced by AKI survivors (heart failure with preserved or reduced ejection fraction, HFpEF or HFrEF) could suggest potential mechanisms underlying the association and opportunities for improving post-AKI care.

METHODS

In this retrospective study of adults within the Vanderbilt University health system with a diagnosis of HF, we tested whether AKI events in the two years preceding incident HF associated more with HFpEF or HFrEF while controlling for known predictors. HF outcomes were defined by administrative codes and classified as HFpEF or HFrEF by echocardiogram data. We used multivariable logistic regression models to estimate the effects of AKI on the odds of incident HFpEF versus HFrEF.

RESULTS

AKI (all stages) trended towards a preferential association with HFpEF in adjusted analyses (adjusted OR 0.80, 95% CI 0.63 - 1.01). Stage 1 AKI was associated with higher odds of HFpEF that was statistically significant (adjusted OR 0.62, 95% CI 0.43 - 0.88), whereas stages 2-3 AKI showed a trend toward HFrEF that did not reach statistical significance (adjusted OR 1.11, 95% CI 0.76 - 1.63).

CONCLUSIONS

AKI as a binary outcome trended towards a preferential association with HFpEF. Stage 1 AKI was associated with higher odds of HFpEF, whereas stage 2-3 trended towards an association with HFrEF that did not meet statistical significance. Different mechanisms may predominate in incident HF following mild versus more severe AKI. Close follow-up with particular attention to volume status and cardiac function after discharge is warranted after even mild AKI.

Parental recovered acute kidney injury causes prenatal renal dysfunction and fetal growth restriction with sexually dimorphic implications for adult offspring

Introduction: Acute kidney injury (AKI) is rapidly increasing in global incidence and a healthcare burden. Prior maternal AKI diagnosis correlates with later pregnancy complications. As pregnancy influences developmental programming, we hypothesized that recovered parental AKI results in poor pregnancy outcomes, impaired fetal growth, and adult offspring disease. Methods: Using a well-characterized model of rhabdomyolysis-induced acute kidney injury (RIAKI), a form of AKI commonly observed in young people, we confirmed functional renal recovery by assessing glomerular filtration rate (GFR) 2 weeks following RIAKI. We bred sham and recovered RIAKI sires and dams in timed, matched matings for gestational day (GD) 16.5 and offspring (birth-12 weeks, 6 months) study. Results: Despite a normal GFR pre-pregnancy, recovered RIAKI dams at GD16.5 had impaired renal function, resulting in reduced fetoplacental ratios and offspring survival. Pregnant RIAKI dams also had albuminuria and less renal megalin in the proximal tubule brush border than shams, with renal subcapsular fibrosis and higher diastolic blood pressure. Growth-restricted offspring had a reduced GFR as older adults, with evidence of metabolic inefficiency in male offspring; this correlated with reduced renal AngII levels in female offspring from recovered RIAKI pairings. However, the blood pressures of 6-month-old offspring were unaffected by parental RIAKI. Conclusions: Our mouse model demonstrated a causal relationship among RIAKI, gestational risk, and developmental programming of the adult-onset offspring GFR and metabolic dysregulation despite parental recovery.

Acute Kidney Injury and Subsequent Cardiovascular Disease: Epidemiology, Pathophysiology, and Treatment

Cardiovascular disease poses a significant threat to individuals with kidney disease, including those affected by acute kidney injury (AKI). In the short term, AKI has several physiological consequences that can impact the cardiovascular system. These include fluid and sodium overload, activation of the renin-angiotensin-aldosterone system and sympathetic nervous system, and inflammation along with metabolic complications of AKI (acidosis, electrolyte imbalance, buildup of uremic toxins). Recent studies highlight the role of AKI in elevating long-term risks of hypertension, thromboembolism, stroke, and major adverse cardiovascular events, though some of this increased risk may be due to the impact of AKI on the course of chronic kidney disease. Current management strategies involve avoiding nephrotoxic agents, optimizing hemodynamics and fluid balance, and considering renin-angiotensin-aldosterone system inhibition or sodium-glucose cotransporter 2 inhibitors. However, future research is imperative to advance preventive and therapeutic strategies for cardiovascular complications in AKI. This review explores the existing knowledge on the cardiovascular consequences of AKI, delving into epidemiology, pathophysiology, and treatment of various cardiovascular complications following AKI.

Unraveling Chronic Cardiovascular and Kidney Disorder through the Butterfly Effect

Chronic Cardiovascular and Kidney Disorder (CCKD) represents a growing challenge in healthcare, characterized by the complex interplay between heart and kidney diseases. This manuscript delves into the "butterfly effect" in CCKD, a phenomenon in which acute injuries in one organ lead to progressive dysfunction in the other. Through extensive review, we explore the pathophysiology underlying this effect, emphasizing the roles of acute kidney injury (AKI) and heart failure (HF) in exacerbating each other. We highlight emerging therapies, such as renin-angiotensin-aldosterone system (RAAS) inhibitors, SGLT2 inhibitors, and GLP1 agonists, that show promise in mitigating the progression of CCKD. Additionally, we discuss novel therapeutic targets, including Galectin-3 inhibition and IL33/ST2 pathway modulation, and their potential in altering the course of CCKD. Our comprehensive analysis underscores the importance of recognizing and treating the intertwined nature of cardiac and renal dysfunctions, paving the way for more effective management strategies for this multifaceted syndrome.

Cardiorenal damages in mice at early phase after intervention induced by angiotensin II, nephrectomy, and salt intake

The interconnection of heart performance and kidney function plays an important role for maintaining homeostasis through a variety of physiological crosstalk between these organs. It has been suggested that acute or chronic dysfunction in one organ causes dysregulation in another one, like patients with cardiorenal syndrome. Despite its growing recognition as global health issues, still little is known on pathophysiological evaluation between the two organs. Previously, we established a preclinical murine model with cardiac hypertrophy and fibrosis, and impaired kidney function with renal enlargement and increased urinary albumin levels induced by co-treatment with vasopressor angiotensin II (A), unilateral nephrectomy (N), and salt loading (S) (defined as ANS treatment) for 4 weeks. However, how both tissues, heart and kidney, are initially affected by ANS treatment during the progression of tissue damages remains to be determined. Here, at one week after ANS treatment, we found that cardiac function in ANS-treated mice (ANS mice) are sustained despite hypertrophy. On the other hand, kidney dysfunction is evident in ANS mice, associated with high blood pressure, enlarged glomeruli, increased levels of urinary albumin and urinary neutrophil gelatinase-associated lipocalin, and reduced creatinine clearance. Our results suggest that cardiorenal tissues become damaged at one week after ANS treatment and that ANS mice are useful as a model causing transition from early to late-stage damages of cardiorenal tissues.

Allograft function predicts mortality in kidney transplant recipients with severe COVID-19: a paradoxical risk factor

Introduction

Kidney transplant recipients (KTRs) are at a higher risk of severe coronavirus disease (COVID-19) because of their immunocompromised status. However, the effect of allograft function on the prognosis of severe COVID-19 in KTRs is unclear. In this study, we aimed to analyze the correlation between pre-infection allograft function and the prognosis of severe COVID-19 in KTRs.

Methods

This retrospective cohort study included 82 patients who underwent kidney transplantation at the Sichuan Provincial Peoples Hospital between October 1, 2014 and December 1, 2022 and were diagnosed with severe COVID-19. The patients were divided into decreased eGFR and normal eGFR groups based on the allograft function before COVID-19 diagnosis (n=32 [decreased eGFR group], mean age: 43.00 years; n=50 [normal eGFR group, mean age: 41.88 years). We performed logistic regression analysis to identify risk factors for death in patients with severe COVID-19. The nomogram was used to visualize the logistic regression model results.

Results

The mortality rate of KTRs with pre-infection allograft function insufficiency in the decreased eGFR group was significantly higher than that of KTRs in the normal eGFR group (31.25% [10/32] vs. 8.00% [4/50], P=0.006). Pre-infection allograft function insufficiency (OR=6.96, 95% CI: 1.4633.18, P=0.015) and maintenance of a mycophenolic acid dose >1500 mg/day before infection (OR=7.59, 95% CI: 1.0853.20, P=0.041) were independent risk factors, and the use of nirmatrelvir/ritonavir before severe COVID-19 (OR=0.15, 95% CI: 0.030.72, P=0.018) was a protective factor against death in severe COVID-19.

Conclusions

Pre-infection allograft function is a good predictor of death in patients with severe COVID-19. Allograft function was improved after treatment for severe COVID-19, which was not observed in patients with non-severe COVID-19.

Interorgan communication networks in the kidney-lung axis

The homeostasis and health of an organism depend on the coordinated interaction of specialized organs, which is regulated by interorgan communication networks of circulating soluble molecules and neuronal connections. Many diseases that seemingly affect one primary organ are really multiorgan diseases, with substantial secondary remote organ complications that underlie a large part of their morbidity and mortality. Acute kidney injury (AKI) frequently occurs in critically ill patients with multiorgan failure and is associated with high mortality, particularly when it occurs together with respiratory failure. Inflammatory lung lesions in patients with kidney failure that could be distinguished from pulmonary oedema due to volume overload were first reported in the 1930s, but have been largely overlooked in clinical settings. A series of studies over the past two decades have elucidated acute and chronic kidney-lung and lung-kidney interorgan communication networks involving various circulating inflammatory cytokines and chemokines, metabolites, uraemic toxins, immune cells and neuro-immune pathways. Further investigations are warranted to understand these clinical entities of high morbidity and mortality, and to develop effective treatments.

Application of Electrolyzed Hydrogen Water for Management of Chronic Kidney Disease and Dialysis Treatment-Perspective View

Chronic kidney disease (CKD), which is globally on the rise, has become an urgent challenge from the perspective of public health, given its risk factors such as end-stage renal failure, cardiovascular diseases, and infections. The pathophysiology of CKD, including dialysis patients, is deeply associated with enhanced oxidative stress in both the kidneys and the entire body. Therefore, the introduction of a safe and widely applicable antioxidant therapy is expected as a measure against CKD. Electrolyzed hydrogen water (EHW) generated through the electrolysis of water has been confirmed to possess chemical antioxidant capabilities. In Japan, devices producing this water have become popular for household drinking water. In CKD model experiments conducted to date, drinking EHW has been shown to suppress the progression of kidney damage related to hypertension. Furthermore, clinical studies have reported that systemic oxidative stress in patients undergoing dialysis treatment using EHW is suppressed, leading to a reduction in the incidence of cardiovascular complications. In the future, considering EHW as one of the comprehensive measures against CKD holds significant importance. The medical utility of EHW is believed to be substantial, and further investigation is warranted.

Impact of acute kidney injury on major adverse cardiovascular events in intensive care survivors

Background

Acute kidney injury commonly occurs in patients admitted to ICU. After acute kidney injury, kidney function may not completely recover leading to increased risk of future cardiovascular events. We sought to ascertain the rates of cardiovascular events in ICU survivors and if these rates were affected by the presence of acute kidney injury whilst in ICU.

Methods

This retrospective observational cohort study utilised routinely collected data to identify patients who had survived an admission to one of two ICUs between July 2015 and June 2018. Baseline serum creatinine and subsequent values were used to identify acute kidney injury. Major adverse cardiovascular events described were myocardial injury, coronary artery intervention, or radiological evidence of stroke.

Results

Of the 3994 ICU survivors, major adverse cardiovascular events were identified in 385 patients (9.6%; 95% confidence interval [CI] 8.8-10.6%). Presence of acute kidney injury whilst in ICU was significantly associated with future major adverse cardiovascular events (hazard ratio=1.38; 95% CI 1.12-1.70; P-value=0.003) and future biochemical myocardial injury (hazard ratio=1.48; 95% CI 1.16-1.89; P-value=0.001). Acute kidney injury did not have a statistically significant association with future coronary artery interventions or future cerebrovascular events.

Conclusions

One in 10 ICU survivors experiences a major adverse cardiovascular event after discharge. Acute kidney injury whilst in ICU was associated with an increased risk of major adverse cardiovascular events and specifically myocardial injury. Further research is warranted on whether ICU survivors with acute kidney injury merit enhanced strategies for cardiovascular protection.

Postoperative decline in renal function after rectal resection and all-cause mortality: a retrospective cohort study

AIM

Fluid loss, dehydration and resultant kidney injury are common when a diverting ileostomy is formed during rectal cancer surgery, the consequences of which are unknown. The aim of this retrospective single-site cohort study is to evaluate the impact of sustained postoperative renal dysfunction after rectal resection on long-term renal impairment and survival.

METHOD

All patients with rectal adenocarcinoma undergoing resection between January 2003 and March 2017 were included, with follow-up to June 2020. The primary outcome was impact on long-term mortality attributed to a 25% or greater drop in estimated glomerular filtration rate (eGFR) following rectal resection. Secondary outcomes were the long-term effect on renal function resulting from the same drop in eGFR and the effect on long-term mortality and renal function of a 50% drop in eGFR. We also calculated the effect on mortality of a 1% drop in eGFR.

RESULTS

A total of 1159 patients were identified. Postoperative reductions in eGFR of 25% and 50% were associated with long-term overall mortality with adjusted hazard ratios of 1.84 (1.22-2.77) (p = 0.004) and 2.88 (1.45-5.71) (p = 0.002). The median survival of these groups was 86.0 (64.0-108.0) months and 53.3 (7.8-98.8) months compared with 144.5 (128.1-160.9) months for controls. Long-term effects on renal function were demonstrated, with those who sustained a >25% drop in renal function having a 38.8% mean decline in eGFR at 10 years compared with 10.2% in controls.

CONCLUSION

Persistent postoperative declines in renal function may be linked to long-term mortality. Further research is needed to assess causal relationships and prevention.

Protective effects of limb remote ischemic per-conditioning on the heart injury induced by renal ischemic-reperfusion through the interaction of the apelin with the RAS/iNOS pathway

Introduction

Remote ischemic conditioning upregulates endogenous protective pathways in response to ischemia-reperfusion injury. This study tested the hypothesis that limb remote ischemic per- conditioning (RIPerC) exerts cardioprotective effects via the renin-angiotensin system (RAS)/inducible nitric oxide synthase (iNOS)/apelin pathway.

Methods

Renal ischemia-reperfusion injury (I/R) was induced by bilateral occlusion of the renal pedicles for 60 minutes, followed by 24 hours of reperfusion; sham-operated rats served as controls. RIPerC was induced by four cycles (5 minutes) of limb ischemia-reperfusion along with bilateral renal ischemia. The functional disturbance was evaluated by renal (BUN and creatinine) and cardiac (troponin I and lactate dehydrogenase) injury biomarkers.

Results

Renal I/R injury increased renal and cardiac injury biomarkers that were reduced in the RIPerC group. Histopathological findings of the kidney and heart were also suggestive of amelioration injury-induced changes in the RIPerC group. Assessment of cardiac electrophysiology revealed that RIPerC ameliorated the decline in P wave duration without significantly affecting other cardiac electrophysiological changes. Further, renal I/R injury increased the plasma (322.40±34.01 IU/L), renal (8.27±1.10 mIU/mg of Protein), and cardiac (68.28±10.28 mIU/mg of protein) angiotensin-converting enzyme (ACE) activities in association with elevations in the plasma and urine nitrite (25.47±2.01 & 16.62±3.05 μmol/L) and nitrate (15.47±1.33 & 5.01±0.96 μmol/L) levels; these changes were reversed by RIPerC. Further, renal ischemia-reperfusion injury significantly (P=0.047) decreased the renal (but not cardiac) apelin mRNA expression, while renal and cardiac ACE2 (P<0.05) and iNOS (P=0.043) mRNA expressions were significantly increased compared to the sham group; these effects were largely reversed by RIPerC.

Conclusion

Our results indicated that RIPerC protects the heart against renal ischemia- reperfusion injury, likely via interaction of the apelin with the RAS/iNOS pathway.

Clinicopathological Characteristics and Prognosis of Lupus Nephritis Patients with Acute Kidney Injury

INTRODUCTION

Acute kidney injury (AKI) is common in lupus nephritis (LN) and a risk factor for chronic kidney failure. Here, we aimed to assess the characteristics and prognosis of LN patients with AKI.

METHODS

AKI and AKI severity stages in LN patients were defined by the Kidney Disease Improving Global Outcomes (KDIGO) classification. Long-term renal outcomes and patient mortality between different stages of AKI were compared by Cox regression analysis.

RESULTS

Of 1272 LN patients, 225 (17.69%) had AKI and 72 (5.66%) were AKI stage 3. Compared with the non-AKI group, the proportion of male patients was significantly higher in the AKI group (p = 0.002). In addition, there were markedly higher proportions of hematologic system damage, more severe renal manifestations, and higher Systemic Lupus Erythematosus Disease Activity Index (SLEDAI) scores in the AKI group than in the non-AKI group. The active and chronic lesions in renal biopsy were significantly higher in LN patients with AKI than those without AKI. During a median follow-up of 53 months, Kaplan-Meier curve showed that LN patients with AKI stage 3 had significantly poorer long-term renal outcomes (p = 0.002) and patient survival (p < 0.001) than those without AKI. Furthermore, AKI stage 3, but not stage 1 or 2 was significantly associated with adverse renal outcomes (hazard ratio [HR] = 2.52, 95% confidence interval [CI] 1.01-6.28, p = 0.048) and all-cause mortality (HR = 2.80, 95% CI: 1.18-6.61, p = 0.019) in LN patients. In patients with AKI, increased baseline serum creatinine and severe glomerular sclerosis were independent risk factors for worse renal outcomes, while higher blood pressure, increased baseline serum creatinine, and anti-Sjogren's syndrome A positivity could indicate poor survival.

DISCUSSION

LN patients with AKI stage 3, but not stages 1 and 2, have poorer long-term renal outcomes and patient survival. Our study demonstrates the importance of early identification and management of AKI in LN patients.

IL-6 mediates the hepatic acute phase response after prerenal azotemia in a clinically defined murine model

Prerenal azotemia (PRA) is a major cause of acute kidney injury and uncommonly studied in preclinical models. We sought to develop and characterize a novel model of PRA that meets the clinical definition: acute loss of glomerular filtration rate (GFR) that returns to baseline with resuscitation. Adult male C57BL/6J wild-type (WT) and IL-6-/- mice were studied. Intraperitoneal furosemide (4 mg) or vehicle was administered at time = 0 and 3 h to induce PRA from volume loss. Resuscitation began at 6 h with 1 mL intraperitoneal saline for four times for 36 h. Six hours after furosemide administration, measured glomerular filtration rate was 25% of baseline and returned to baseline after saline resuscitation at 48 h. After 6 h of PRA, plasma interleukin (IL)-6 was significantly increased, kidney and liver histology were normal, kidney and liver lactate were normal, and kidney injury molecule-1 immunofluorescence was negative. There were 327 differentially regulated genes upregulated in the liver, and the acute phase response was the most significantly upregulated pathway; 84 of the upregulated genes (25%) were suppressed in IL-6-/- mice, and the acute phase response was the most significantly suppressed pathway. Significantly upregulated genes and their proteins were also investigated and included serum amyloid A2, serum amyloid A1, lipocalin 2, chemokine (C-X-C motif) ligand 1, and haptoglobin; hepatic gene expression and plasma protein levels were all increased in wild-type PRA and were all reduced in IL-6-/- PRA. This work demonstrates previously unknown systemic effects of PRA that includes IL-6-mediated upregulation of the hepatic acute phase response.NEW & NOTEWORTHY Prerenal azotemia (PRA) accounts for a third of acute kidney injury (AKI) cases yet is rarely studied in preclinical models. We developed a clinically defined murine model of prerenal azotemia characterized by a 75% decrease in measured glomerular filtration rate (GFR), return of measured glomerular filtration rate to baseline with resuscitation, and absent tubular injury. Numerous systemic effects were observed, such as increased plasma interleukin-6 (IL-6) and upregulation of the hepatic acute phase response.

Acute kidney injury in infants hospitalized for viral bronchiolitis

We investigated prevalence of and factors associated with acute kidney injury (AKI) in a group of patients hospitalized with viral bronchiolitis. We retrospectively enrolled 139 children (mean age = 3.2 ± 2.1 months; males = 58.9%) hospitalized for viral bronchiolitis in a non-pediatric intensive care unit (PICU) setting. The Kidney Disease/Improving Global Outcomes creatinine criterion was used to diagnose AKI. We estimated basal serum creatinine by back-calculating it by Hoste (age) equation assuming that basal eGFR were the median age-based eGFR normative values. Univariate and multivariate logistic regression models were used to explore associations with AKI. Out of 139 patients, AKI was found in 15 (10.8%). AKI was found in 13 out of 74 (17.6%) patients with and in 2 out of 65 (3.1%) without respiratory syncytial virus (RSV) infection (p = 0.006). No patient required renal replacement therapies, while 1 out of 15 (6.7%) developed AKI stage 3, 1 (6.7%) developed AKI stage 2, and 13 (86.6%) developed AKI stage 1. Among the 15 patients with AKI, 13 (86.6%) reached the maximum AKI stage at admission, 1 (6.7%) at 48 h, and 1 (6.7%) at 96 h. At multivariate analysis, birth weight < 10th percentile (odds ratio, OR = 34.1; 95% confidence interval, CI = 3.6-329.4; p = 0.002), preterm birth (OR = 20.3; 95% CI = 3.1-129.5; p = 0.002), RSV infection (OR = 27.0; 95% CI = 2.6-279.9; p = 0.006), and hematocrit levels > 2 standard deviation score (SDS) (OR = 22.4; 95% CI = 2.8-183.6; p = 0.001) were significantly associated with AKI.

CONCLUSION

About 11% of patients hospitalized with viral bronchiolitis in a non-PICU setting develop an AKI (frequently mild in degree). Preterm birth, birth weight < 10th percentile, hematocrit levels > 2SDS, and RSV infection are significantly associated with AKI in the setting of viral bronchiolitis.

WHAT IS KNOWN

• Viral bronchiolitis affects children in the first months of life and in 7.5% of cases it can be complicated by acute kidney injury (AKI). • No studies investigated associations with AKI in infants hospitalized for viral bronchiolitis.

WHAT IS NEW

• About 11% of patients hospitalized with viral bronchiolitis can develop an AKI (frequently mild in degree). • Preterm birth, birth weight <10th percentile, hematocrit levels > 2 standard deviation score, and respiratory syncytial virus infection are associated with AKI development in infants with viral bronchiolitis.

Impaired microvascular circulation in distant organs following renal ischemia

Mortality in acute kidney injury (AKI) patients remains very high, although very important advances in understanding the pathophysiology and in diagnosis and supportive care have been made. Most commonly, adverse outcomes are related to extra-renal organ dysfunction and failure. We and others have documented inflammation in remote organs as well as microvascular dysfunction in the kidney after renal ischemia. We hypothesized that abnormal microvascular flow in AKI extends to distant organs. To test this hypothesis, we employed intravital multiphoton fluorescence imaging in a well-characterized rat model of renal ischemia/reperfusion. Marked abnormalities in microvascular flow were seen in every organ evaluated, with decreases up to 46% observed 48 hours postischemia (as compared to sham surgery, p = 0.002). Decreased microvascular plasma flow was found in areas of erythrocyte aggregation and leukocyte adherence to endothelia. Intravital microscopy allowed the characterization of the erythrocyte formations as rouleaux that flowed as one-dimensional aggregates. Observed microvascular abnormalities were associated with significantly elevated fibrinogen levels. Plasma flow within capillaries as well as microthrombi, but not adherent leukocytes, were significantly improved by treatment with the platelet aggregation inhibitor dipyridamole. These microvascular defects may, in part, explain known distant organ dysfunction associated with renal ischemia. The results of these studies are relevant to human acute kidney injury.

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.

Autologous Extracellular Vesicles Attenuate Cardiac Injury in Experimental Atherosclerotic Renovascular Disease More Effectively Than Their Parent Mesenchymal Stem/Stromal Cells

Atherosclerotic renovascular disease (RVD) leads to hypertension, chronic kidney disease (CKD), and heart disease. Intrarenal delivery of mesenchymal stem cells (MSCs) and MSC-derived extracellular vesicles (EVs) attenuate renal injury and suppress release of inflammatory cytokines in porcine RVD. We hypothesized that this strategy would also be useful for cardioprotection. Pigs with renovascular hypertension and metabolic syndrome were studied 4 weeks after treatment with a single intrarenal infusion of autologous MSCs, EVs, or vehicle. Cardiac structure and function were assessed in vivo, and myocardial remodeling and expression of the pro-fibrotic factor growth factor receptor-bound protein-2 (Grb2) were measured ex-vivo. Inflammatory cytokine levels were measured in the systemic circulation and myocardial tissue. Blood pressure was elevated in all RVD groups, but serum creatinine increased in RVD and decreased in both RVD + MSCs and RVD + EVs. RVD-induced diastolic dysfunction (lower E/A ratio) was normalized in both MSCs- and EVs- treated pigs. Intrarenal delivery of MSCs and EVs also attenuated RVD-induced myocardial fibrosis, collagen deposition, and Grb2 expression, yet EVs restored capillary density and inflammation more effectively than MSCs. These observations suggest that autologous EVs attenuate cardiac injury in experimental RVD more effectively than their parent MSCs.

Intensive Care Unit-Acquired Weakness in Patients With Acute Kidney Injury: A Contemporary Review

Acute kidney injury (AKI) and intensive care unit-acquired weakness (ICU-AW) are 2 frequent complications of critical illness that, until recently, have been considered unrelated processes. The adverse impact of AKI on ICU mortality is clear, but its relationship with muscle weakness-a major source of ICU morbidity-has not been fully elucidated. Furthermore, improving ICU survival rates have refocused the field of intensive care toward improving long-term functional outcomes of ICU survivors. We begin our review with the epidemiology of AKI in the ICU and of ICU-AW, highlighting emerging data suggesting that AKI and AKI treated with kidney replacement therapy (AKI-KRT) may independently contribute to the development of ICU-AW. We then delve into human and animal data exploring the pathophysiologic mechanisms linking AKI and acute KRT to muscle wasting, including altered amino acid and protein metabolism, inflammatory signaling, and deleterious removal of micronutrients by KRT. We next discuss the currently available interventions that may mitigate the risk of ICU-AW in patients with AKI and AKI-KRT. We conclude that additional studies are needed to better characterize the epidemiologic and pathophysiologic relationship between AKI, AKI-KRT, and ICU-AW and to prospectively test interventions to improve the long-term functional status and quality of life of AKI survivors.

Risk and Timing of De Novo Sepsis in Critically Ill Children after Acute Kidney Injury

Key Points

Critically ill children who developed AKI have a 42% increase in the probability of developing subsequent hospital-acquired sepsis when compared with children without AKI. When evaluating risk of sepsis over time, children with stage 3 AKI remain at increased risk for sepsis for at least 2 weeks after AKI onset. Medical providers should monitor for signs of sepsis after AKI and limit exposures that may increase the risk for infection.

Background

AKI is common among critically ill children and is associated with an increased risk for de novo infection; however, little is known about the epidemiology and temporal relationship between AKI and AKI-associated infection in this cohort.

Methods

We conducted a single-center retrospective cohort study of children admitted to the pediatric and cardiac intensive care units (ICUs) at a tertiary pediatric care center. The relationship between nonseptic AKI and the development of hospital-acquired sepsis was assessed using Cox proportional hazards models using AKI as a time-varying covariate.

Results

Among the 5695 children included in this study, AKI occurred in 20.2% from ICU admission through 30 days. Hospital-acquired sepsis occurred twice as often among children with AKI compared with those without AKI (10.1% versus 4.6%) with an adjusted hazard ratio of 1.42 (95% confidence interval, 1.12 to 1.81). Among the 117 children who developed sepsis after AKI, 80.3% developed sepsis within 7 days and 96.6% within 14 days of AKI onset, with a median time from AKI onset to sepsis of 2.6 days (interquartile range, 1.5–4.7). When assessing change in risk over time, the hazard rate for sepsis remained elevated for children with stage 3 AKI compared with children without AKI at 13.5 days after AKI onset, after which the estimation of hazard rates was limited by the number of children remaining in the hospital.

Conclusions

AKI is an independent risk factor for de novo sepsis. Critically ill children with stage 3 AKI remain at increased risk for sepsis at 13.5 days after AKI onset.

Interaction of acute heart failure and acute kidney injury on in-hospital mortality of critically ill patients with sepsis: A retrospective observational study

BACKGROUND

The present study aimed to evaluate the synergistic impact of acute heart failure (AHF) and acute kidney injury (AKI) on in-hospital mortality in critically ill patients with sepsis.

METHODS

We undertook a retrospective, observational analysis using data acquired from the Medical Information Mart for Intensive Care-IV (MIMIC-IV) database and eICU Collaborative Research Database (eICU-CRD). The effects of AKI and AHF on in-hospital mortality were examined using a Cox proportional hazards model. Additive interactions were analyzed using the relative extra risk attributable to interaction.

RESULTS

A total of 33,184 patients were eventually included, comprising 20,626 patients in the training cohort collected from the MIMIC-IV database and 12,558 patients in the validation cohort extracted from the eICU-CRD database. After multivariate Cox analysis, the independent variables for in-hospital mortality included: AHF only (HR:1.20, 95% CI:1.02-1.41, P = 0.005), AKI only (HR:2.10, 95% CI:1.91-2.31, P < 0.001), and both AHF and AKI (HR:3.80, 95%CI:13.40-4.24, P < 0.001). The relative excess risk owing to interaction was 1.49 (95% CI:1.14-1.87), the attributable percentage due to interaction was 0.39 (95%CI:0.31-0.46), and the synergy index was 2.15 (95%CI:1.75-2.63), demonstrated AHF and AKI had a strong synergic impact on in-hospital mortality. And the findings in the validation cohort indicated identical conclusions to the training cohort.

CONCLUSION

Our data demonstrated a synergistic relationship of AHF and AKI on in-hospital mortality in critically unwell patients with sepsis.

Cardiac effects of renal ischemia

Mortality in acute kidney injury (AKI) remains very high, yet the cause of death is often failure of extrarenal organs. We and others have demonstrated remote organ dysfunction after renal ischemia. The term "cardiorenal syndrome" was first applied to the "cross talk" between the organs by the National Heart, Lung, and Blood Institute of the National Institutes of Health, and the clinical importance is being increasingly appreciated. Nevertheless, more information is needed to effectively address the consequences of renal injury on the heart. Since AKI often occurs in patients with comorbidities, we investigated the effect of renal ischemia in the setting of existing cardiac failure. We hypothesized that the cardiac effects of renal ischemia would be significantly amplified in experimental cardiomyopathy. Male Sprague-Dawley rats with preexisting cardiac and renal injury due to low-dose doxorubicin were subjected to bilateral renal artery occlusion. Cardiac structure and function were examined 2 days after reperfusion. Loss of functional myocardial tissue with decreases in left ventricular pressure, increases in apoptotic cell death, inflammation, and collagen, and greater disruption in ultrastructure with mitochondrial fragmentation were seen in the doxorubicin/ischemia group compared with animals in the groups treated with doxorubicin alone or following ischemia alone. Systemic inflammation and cardiac abnormalities persisted for at least 21 wk. These results suggest that preexisting comorbidities can result in much more severe distant organ effects of acute renal injury. The results of this study are relevant to human AKI.NEW & NOTEWORTHY Acute kidney injury is common, expensive, and deadly, yet morbidity and mortality are often secondary to remote organ dysfunction. We hypothesized that the effects of renal ischemia would be amplified in the setting of comorbidities. Sustained systemic inflammation and loss of functional myocardium with significantly decreased systolic and diastolic function, apoptotic cell death, and increased collagen and inflammatory cells were found in the heart after renal ischemia in the doxorubicin cardiomyopathy model (vs. renal ischemia alone). Understanding the remote effects of renal ischemia has the potential to improve outcomes in acute kidney injury.

Organ Crosstalk in Acute Kidney Injury: Evidence and Mechanisms

Acute kidney injury (AKI) is becoming a public health problem worldwide. AKI is usually considered a complication of lung, heart, liver, gut, and brain disease, but recent findings have supported that injured kidney can also cause dysfunction of other organs, suggesting organ crosstalk existence in AKI. However, the organ crosstalk in AKI and the underlying mechanisms have not been broadly reviewed or fully investigated. In this review, we summarize recent clinical and laboratory findings of organ crosstalk in AKI and highlight the related molecular mechanisms. Moreover, their crosstalk involves inflammatory and immune responses, hemodynamic change, fluid homeostasis, hormone secretion, nerve reflex regulation, uremic toxin, and oxidative stress. Our review provides important clues for the intervention for AKI and investigates important therapeutic potential from a new perspective.

Role of coagulation in persistent renal ischemia following reperfusion in an animal model

Ischemic acute kidney injury is common, deadly, and accelerates the progression of chronic kidney disease, yet has no specific therapy. After ischemia, reperfusion is patchy with early and persistent impairment in regional renal blood flow and cellular injury. We tested the hypothesis that intrarenal coagulation results in sustained renal ischemia following reperfusion, using a well-characterized model. Markedly decreased, but heterogeneous, microvascular plasma flow with microthrombi was found postischemia by intravital microscopy. Widespread tissue factor expression and fibrin deposition were also apparent. Clotting was accompanied by complement activation and inflammation. Treatment with exosomes derived from renal tubular cells or with the fibrinolytic urokinase, given 24 h postischemia when renal failure was established, significantly improved microvascular flow, coagulation, serum creatinine, and histological evidence of injury. These data support the hypothesis that intrarenal clotting occurs early and the resultant sustained ischemia is a critical determinant of renal failure following ischemia; they demonstrate that the coagulation abnormalities are amenable to therapy and that therapy results in improvement in both function and postischemic inflammation.NEW & NOTEWORTHY Ischemic renal injury carries very high morbidity and mortality, yet has no specific therapy. We found markedly decreased, heterogeneous microvascular plasma flow, tissue factor induction, fibrin deposition, and microthrombi after renal ischemia-reperfusion using a well-characterized model. Renal exosomes or the fibrinolytic urokinase, administered after renal failure was established, improved microvascular flow, coagulation, renal function, and histology. Data demonstrate that intrarenal clotting results in sustained ischemia amenable to therapy that improves both function and postischemic inflammation.

Acute kidney injury-associated delirium: a review of clinical and pathophysiological mechanisms

Acute kidney injury is a known clinical risk factor for delirium, an acute cognitive dysfunction that is commonly encountered in the critically ill population. In this comprehensive review of clinical and basic research studies, we detail the epidemiology, clinical implications, pathogenesis, and management strategies of patients with acute kidney injury-associated delirium. Specifically addressed are the pathological roles of endogenous toxin or drug accumulation, acute kidney injury-mediated neuroinflammation, and acute kidney injury-associated volume overload as discrete potential biological mechanisms of the condition. The optimization of clinical contributors and normalization of renal function are reviewed as pragmatic management strategies in addition to potential and emerging therapeutic approaches.

Association between proteinuria trajectories and outcomes in critically ill patients with sepsis or shock

Background

Proteinuria results from kidney damage and can be a predictor of illness severity and mortality in the intensive care unit (ICU). However, the optimal timing of proteinuria measurements and the reference values remain undetermined. Our objective was to identify the patterns of proteinuria change associated with mortality in ICU patients with sepsis or shock.

Methods

This monocentric retrospective cohort study performed from April 2010 to April 2018 involved all ICU patients with sepsis or shock and at least two measurements of proteinuria from a 24h-urine collection during the first 10 days of ICU stay, the first of which was made within 48h after ICU admission. We identified proteinuria trajectories by a semi-parametric mixture model and analysed the association between the trajectories and the mortality at day 28 by Cox proportional-hazards model.

Results

A total of 3,344 measurements of proteinuria from 659 patients were analysed. Four proteinuria trajectories were identified. Trajectories 1, 2, 3 and 4 comprised 127, 421, 60 and 51 patients, and were characterized by a first proteinuria of 1.14 [0.66–1.55], 0.52 [0.26–0.91], 2.92 [2.38–3.84] and 2.58 [1.75–3.32] g/24h (p<0.001) and a mortality of 24.4%, 38%, 20% and 43% (p = 0.002), respectively. Trajectories 3 and 4 had a high first proteinuria (>2g/24h). Only, the proteinuria of trajectory 4 increased within 3 days following the first measurement and was associated with increased mortality at day 28 (hazard ratio: 2.36 95%CI [1.07–5.19], p = 0.03), regardless of acute renal failure. The factors associated with trajectory 4 were cancer (relative risk: 8.91 95%CI [2.09–38.02], p = 0.003) and use of inotropic drugs (relative risk: 0.17 95%CI [0.04–0.69], p = 0.01).

Conclusion

This exploratory study of ICU patients with sepsis or shock identified four proteinuria trajectories with distinct patterns of proteinuria change over time and mortality rates. These results provide novel insights into renal pathophysiology and may be helpful to investigate subphenotypes of kidney injury among ICU patients in future studies.

Chronic critical illness and post-intensive care syndrome: from pathophysiology to clinical challenges

Background

Post‐intensive care syndrome (PICS) encompasses physical, cognition, and mental impairments persisting after intensive care unit (ICU) discharge. Ultimately it significantly impacts the long‐term prognosis, both in functional outcomes and survival. Thus, survivors often develop permanent disabilities, consume a lot of healthcare resources, and may experience prolonged suffering. This review aims to present the multiple facets of the PICS, decipher its underlying mechanisms, and highlight future research directions.

Main text

This review abridges the translational data underlying the multiple facets of chronic critical illness (CCI) and PICS. We focus first on ICU-acquired weakness, a syndrome characterized by impaired contractility, muscle wasting, and persisting muscle atrophy during the recovery phase, which involves anabolic resistance, impaired capacity of regeneration, mitochondrial dysfunction, and abnormalities in calcium homeostasis. Second, we discuss the clinical relevance of post-ICU cognitive impairment and neuropsychological disability, its association with delirium during the ICU stay, and the putative role of low-grade long-lasting inflammation. Third, we describe the profound and persistent qualitative and quantitative alteration of the innate and adaptive response. Fourth, we discuss the biological mechanisms of the progression from acute to chronic kidney injury, opening the field for renoprotective strategies. Fifth, we report long-lasting pulmonary consequences of ARDS and prolonged mechanical ventilation. Finally, we discuss several specificities in children, including the influence of the child’s pre-ICU condition, development, and maturation.

Conclusions

Recent understandings of the biological substratum of the PICS’ distinct features highlight the need to rethink our patient trajectories in the long term. A better knowledge of this syndrome and precipitating factors is necessary to develop protocols and strategies to alleviate the CCI and PICS and ultimately improve patient recovery.

Protective effect of saxagliptin against renal ischaemia reperfusion injury in rats

Saxagliptin is an effective and selective dipeptidyl peptidase-4 (DPP-4) inhibitor. This study was designed to determine possible protective effects of saxagliptin against damage caused by renal ischaemia/reperfusion (I/R) in rats. In this study, 40 rats were divided into 4 groups (n = 10 for each). Group 1 (Control), Group 2 (I/R) in both kidneys ischaemia of 45 min was performed, and then reperfusion was applied for 24 h. Saxagliptin (Group 3: 2 mg/kg and Group 4: 10 mg/kg) was administered by oral gavage to the animals in treatment groups, before the I/R. Saxagliptin decreased the markers (BUN, Cre, NGAL, KIM-1 and IL-18) of acute renal damage in blood and kidney tissue. Saxagliptin provided increase in antioxidant enzyme levels and decrease in MDA and apoptosis. Histological results showed that the administration of saxagliptin exhibited a protective effect against renal damage caused by I/R. These results indicates that saxagliptin provide protection against kidney injury caused by I/R.

Toward Human Models of Cardiorenal Syndrome in vitro

Heart and kidney diseases cause high morbidity and mortality. Heart and kidneys have vital functions in the human body and, interestingly, reciprocally influence each other’s behavior: pathological changes in one organ can damage the other. Cardiorenal syndrome (CRS) is a group of disorders in which there is combined dysfunction of both heart and kidney, but its underlying biological mechanisms are not fully understood. This is because complex, multifactorial, and dynamic mechanisms are likely involved. Effective treatments are currently unavailable, but this may be resolved if more was known about how the disease develops and progresses. To date, CRS has actually only been modeled in mice and rats in vivo. Even though these models can capture cardiorenal interaction, they are difficult to manipulate and control. Moreover, interspecies differences may limit extrapolation to patients. The questions we address here are what would it take to model CRS in vitro and how far are we? There are already multiple independent in vitro (human) models of heart and kidney, but none have so far captured their dynamic organ-organ crosstalk. Advanced in vitro human models can provide an insight in disease mechanisms and offer a platform for therapy development. CRS represents an exemplary disease illustrating the need to develop more complex models to study organ-organ interaction in-a-dish. Human induced pluripotent stem cells in combination with microfluidic chips are one powerful tool with potential to recapitulate the characteristics of CRS in vitro. In this review, we provide an overview of the existing in vivo and in vitro models to study CRS, their limitations and new perspectives on how heart-kidney physiological and pathological interaction could be investigated in vitro for future applications.

The Role of Gut-Derived, Protein-Bound Uremic Toxins in the Cardiovascular Complications of Acute Kidney Injury

Acute kidney injury (AKI) is a frequent disease encountered in the hospital, with a higher incidence in intensive care units. Despite progress in renal replacement therapy, AKI is still associated with early and late complications, especially cardiovascular events and mortality. The role of gut-derived protein-bound uremic toxins (PBUTs) in vascular and cardiac dysfunction has been extensively studied during chronic kidney disease (CKD), in particular, that of indoxyl sulfate (IS), para-cresyl sulfate (PCS), and indole-3-acetic acid (IAA), resulting in both experimental and clinical evidence. PBUTs, which accumulate when the excretory function of the kidneys is impaired, have a deleterious effect on and cause damage to cardiovascular tissues. However, the link between PBUTs and the cardiovascular complications of AKI and the pathophysiological mechanisms potentially involved are unclear. This review aims to summarize available data concerning the participation of PBUTs in the early and late cardiovascular complications of AKI.

Urinary Thioredoxin as a Biomarker of Renal Redox Dysregulation and a Companion Diagnostic to Identify Responders to Redox-Modulating Therapeutics

Significance: The development and progression of renal diseases, including acute kidney injury (AKI) and chronic kidney disease (CKD), are the result of heterogeneous pathophysiology that reflects a range of environmental factors and, in a lesser extent, genetic mutations. The pathophysiology specific to most kidney diseases is not currently identified; therefore, these diseases are diagnosed based on non-pathological factors. For that reason, pathophysiology-based companion diagnostics for selection of pathophysiology-targeted treatments have not been available, which impedes personalized medicine in kidney disease. Recent Advances: Pathophysiology-targeted therapeutic agents are now being developed for the treatment of redox dysregulation. Redox modulation therapeutics, including bardoxolone methyl, suppresses the onset and progression of AKI and CKD. On the other hand, pathophysiology-targeted diagnostics for renal redox dysregulation are also being developed. Urinary thioredoxin (TXN) is a biomarker that can be used to diagnose tubular redox dysregulation. AKI causes oxidation and urinary excretion of TXN, which depletes TXN from the tubules, resulting in tubular redox dysregulation. Urinary TXN is selectively elevated at the onset of AKI and correlates with the progression of CKD in diabetic nephropathy. Critical Issues: Diagnostic methods should provide information about molecular mechanisms that aid in the selection of appropriate therapies to improve the prognosis of kidney disease. Future Directions: A specific diagnostic method enabling detection of redox dysregulation based on pathological molecular mechanisms is much needed and could provide the first step toward personalized medicine in kidney disease. Urinary TXN is a candidate for a companion diagnostic method to identify responders to redox-modulating therapeutics. Antioxid. Redox Signal. 36, 1051-1065.

Hyperoxia and Acute Kidney Injury: A Tale of Oxygen and the Kidney

Although oxygen supplementation is beneficial to support life in the clinic, excessive oxygen therapy also has been linked to damage to organs such as the lung or the eye. However, there is a lack of understanding of whether high oxygen therapy directly affects the kidney, leading to acute kidney injury, and what molecular mechanisms may be involved in this process. In this review, we revise our current understanding of the mechanisms by which hyperoxia leads to organ damage and highlight possible areas of investigation for the scientific community interested in novel mechanisms of kidney disease. Overall, we found a significant need for both animal and clinical studies evaluating the role of hyperoxia in inducing kidney damage. Thus, we urge the research community to further investigate oxygen therapy and its impact on kidney health with the goal of optimizing oxygen therapy guidelines and improving patient care.

Magnolol reduces myocardial injury induced by renal ischemia and reperfusion

BACKGROUND

Magnolol is a component of the bark of Magnolia officinalis, which is a traditional herbal remedy used in China. In this study, we investigated whether magnolol can reduce myocardial injury induced by renal ischemia and reperfusion (I/R).

METHODS

Renal I/R was elicited by a 60-minute occlusion of the bilateral renal arteries and a 24-hour reperfusion in Sprague-Dawley rats. Magnolol was administered intravenously 10 minutes before renal I/R to evaluate its effects on myocardial injury induced by renal I/R.

RESULTS

Renal I/R significantly increased the serum levels of creatine phosphokinase (CPK), lactate dehydrogenase (LDH), and cardiac troponin I and caused myocardial damage. The terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling-positive nuclei and caspase-3 activation was significantly increased in the myocardium, indicating increase of apoptosis. Echocardiography revealed left ventricular dysfunction, as evidenced by reduction of left ventricular ejection fraction and left ventricular fractional shortening. Furthermore, serum levels of tumor necrosis factor-α (TNF-α), interleukin (IL)-1β, and IL-6 were significantly elevated, while the IL-10 level was suppressed. However, intravenously, pretreatment with magnolol at doses of 0.003 and 0.006 mg/kg 10 minutes before renal I/R significantly prevented the increases of CPK, LDH, and cardiac troponin I levels, as well as the histological damage and the apoptosis in the myocardium. Echocardiography showed significant improvement of left ventricular function. Furthermore, the increases in TNF-α, IL-1β, and IL-6 and the decrease in IL-10 were significantly limited, while Bcl-2 was increased and Bax was decreased in the myocardium. Phosphorylation of Akt and extracellular signal-regulated kinases 1 and 2 was increased, while phosphorylation of p38 and c-Jun N-terminal kinase was reduced.

CONCLUSION

Magnolol reduces myocardial injury induced by renal I/R. The underlying mechanisms for this effect might be related to modulation of the production of pro- and anti-inflammatory cytokines and the limiting of apoptosis.

Role of T cells in ischemic acute kidney injury and repair

Ischemic acute kidney injury (AKI) is a common medical problem with significant mortality and morbidity, affecting a large number of patients globally. Ischemic AKI is associated with intrarenal inflammation as well as systemic inflammation; thus, the innate and adaptive immune systems are implicated in the pathogenesis of ischemic AKI. Among various intrarenal immune cells, T cells play major roles in the injury process and in the repair mechanism affecting AKI to chronic kidney disease transition. Importantly, T cells also participate in distant organ crosstalk during AKI, which affects the overall outcomes. Therefore, targeting T cell-mediated pathways and T cell-based therapies have therapeutic promise for ischemic AKI. Here, we review the major populations of kidney T cells and their roles in ischemic AKI.

From cardiorenal syndromes to cardionephrology: a reflection by nephrologists on renocardiac syndromes

Cardiorenal syndromes (CRS) are broadly defined as disorders of the heart and kidneys whereby acute or chronic dysfunction in one organ may induce acute or chronic dysfunction of the other. CRS are currently classified into five categories, mostly based on disease-initiating events and their acuity or chronicity. CRS types 3 and 4 (also called renocardiac syndromes) refer to acute and chronic kidney dysfunction resulting in acute and chronic heart dysfunction, respectively. The notion of renocardiac syndromes has broadened interest in kidney-heart interactions but uncertainty remains in the nephrological community's understanding of the clinical diversity, pathophysiological mechanisms and optimal management approaches of these syndromes. This triple challenge that renocardiac syndromes (and likely other cardiorenal syndromes) pose to the nephrologist can only be faced through a specific and demanding training plan to enhance his/her cardiological scientific knowledge and through an appropriate clinical environment to develop his/her cardiological clinical skills. The first must be the objective of the subspecialty of cardionephrology (or nephrocardiology) and the second must be the result of collaboration with cardiologists (and other specialists) in cardiorenal care units. This review will first consider various aspects of the challenges that renocardiac syndromes pose to nephrologists and, then, will discuss those aspects of cardionephrology and cardiorenal units that can facilitate an effective response to the challenges.

Adipose-derived stem cell and their extracellular vesicles ameliorates immune function, and cardiac markers in experimental model of cardiorenal syndrome type III: TNF-α, IFN-γ and IL-10 cytokine production and their correlation with genotype

Cardio-renal syndrome (CRS) denotes the convergence of heart-kidney interactions across several mechanisms. The current study is conducted to evaluate the anti-inflammatory role of adipose tissue-derived stem cells (ASCs) versus adipose stem cell-derived extracellular vesicles (ADSCs-EVs) in experimental model of cardiorenal syndrome type III. The study was conducted on 50 male rats that were equally divided to: group I (control group); Group II (experimental cardiorenal syndrome group) which induced by right renal artery ligation (ICRSIII); Group III (Sham-operated control group) which underwent surgical incision without renal artery ligation; Group IV (ICRSIII which received ADSCs-extracellular vesicles (ADSCs-EVs); Group V (ICRSIII which received adipose tissue stem cells (ASCs). Assessment of pro-inflammatory cytokines; IL-10, IL-1α, IL-6, IL-1 β, IFN-γ, NF-α and their mRNA gene expression quantitation, (NGAL), and brain natriuretic peptide (BNP) as markers of cardiac dysfunction, as well as histopathological examination of renal tissue was examined by H& E, Masson trichrome and periodic acid-Schiff stains (PAS). The ICRS group exhibited significant acute tubular injury with tubular dilation, loss of brush borders, epithelial flattening, and occasional sloughed cells in lumen. Use of either ADSCs-EVs or ASCs significantly ameliorated the histological findings of tubular injury. Proinflammatory cytokines, BNP and NGAL were significantly elevated in ICRSIII group as compared to all other studied groups. Administration of ADSCs-EVs or ASCs led to significant decrease in all proinflammatory cytokines as well as BNP and NGAL levels with no significant difference between them. In conclusion, ADSCs-EXs and ASCs exhibited significant repairing effects in experimental-induced cardiorenal syndrome type III as evidenced by amelioration of histological findings of tubular injury, anti-inflammatory effects, and the significant decrease in markers of cardiac dysfunction. ADSC-EVs reprogramed injured cardiac cells by activating regenerative processes.

Experimental models of acute kidney injury for translational research

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

Possible kidney-lung cross-talk in COVID-19: in silico modeling of SARS-CoV-2 infection

Background

Publicly available genomics datasets have grown drastically during the past decades. Although most of these datasets were initially generated to answer a pre-defined scientific question, their repurposing can be useful when new challenges such as COVID-19 arise. While the establishment and use of experimental models of COVID-19 are in progress, the potential hypotheses for mechanisms of onset and progression of COVID-19 can be generated by using in silico analysis of known molecular changes during COVID-19 and targets for SARS-CoV-2 invasion.

Methods

Selecting condition: COVID-19 infection leads to pneumonia and mechanical ventilation (PMV) and associated with acute kidney injury (AKI). There is increasing data demonstrating mechanistic links between AKI and lung injury caused by mechanical ventilation.

Selecting targets: SARS-CoV-2 uses angiotensin-converting enzyme 2 (ACE2) and transmembrane protease serine 2 (TMPRSS2) for cell entry. We hypothesized that expression of ACE2 and TMPRSS2 would be affected in models of AKI and PMV. We therefore evaluated expression of ACE2 and TMPRSS2 as well as other novel molecular players of AKI and AKI-lung cross-talk in the publicly available microarray datasets GSE6730 and GSE60088, which represent gene expression of lungs and kidneys in mouse models of AKI and PMV, respectively.

Results

Expression of COVID-19 related genes ACE2 and TMPRSS2 was downregulated in lungs after 6 h of distant AKI effects. The expression of ACE2 decreased further after 36 h, while expression of TMPRSS2 recovered. In kidneys, both genes were downregulated by AKI, but not by distant lung injury. We also identified 53 kidney genes upregulated by PMV; and 254 lung genes upregulated by AKI, 9 genes of which were common to both organs. 3 of 9 genes were previously linked to kidney-lung cross-talk: Lcn2 (Fold Change (FC)_{Lung (L)} = 18.6, FC_{Kidney (K)} = 6.32), Socs3 (FC_L = 10.5, FC_K = 10.4), Inhbb (FC_L = 6.20, FC_K = 6.17). This finding validates the current approach and reveals 6 new candidates, including Maff (FC_L = 7.21, FC_K = 5.98).

Conclusions

Using our in silico approach, we identified changes in COVID-19 related genes ACE2 and TMPRSS2 in traditional mouse models of AKI and kidney-lung cross-talk. We also found changes in new candidate genes, which could be involved in the combined kidney-lung injury during COVID-19.

Female and male mice have differential longterm cardiorenal outcomes following a matched degree of ischemia-reperfusion acute kidney injury

Acute kidney injury (AKI) is common in patients, causes systemic sequelae, and predisposes patients to long-term cardiovascular disease. To date, studies of the effects of AKI on cardiovascular outcomes have only been performed in male mice. We recently demonstrated that male mice developed diastolic dysfunction, hypertension and reduced cardiac ATP levels versus sham 1 year after AKI. The effects of female sex on long-term cardiac outcomes after AKI are unknown. Therefore, we examined the 1-year cardiorenal outcomes following a single episode of bilateral renal ischemia-reperfusion injury in female C57BL/6 mice using a model with similar severity of AKI and performed concomitantly to recently published male cohorts. To match the severity of AKI between male and female mice, females received 34 min of ischemia time compared to 25 min in males. Serial renal function, echocardiograms and blood pressure assessments were performed throughout the 1-year study. Renal histology, and cardiac and plasma metabolomics and mitochondrial function in the heart and kidney were evaluated at 1 year. Measured glomerular filtration rates (GFR) were similar between male and female mice throughout the 1-year study period. One year after AKI, female mice had preserved diastolic function, normal blood pressure, and preserved levels of cardiac ATP. Compared to males, females demonstrated pathway enrichment in arginine metabolism and amino acid related energy production in both the heart and plasma, and glutathione in the plasma. Cardiac mitochondrial respiration in Complex I of the electron transport chain demonstrated improved mitochondrial function in females compared to males, regardless of AKI or sham. This is the first study to examine the long-term cardiac effects of AKI on female mice and indicate that there are important sex-related cardiorenal differences. The role of female sex in cardiovascular outcomes after AKI merits further investigation.

Interorgan crosstalk mechanisms in disease: the case of acute kidney injury-induced remote lung injury

Homeostasis and health of multicellular organisms with multiple organs depends on interorgan communication. Tissue injury in one organ disturbs this homeostasis and can lead to disease in multiple organs, or multiorgan failure. Many routes of interorgan crosstalk during homeostasis are relatively well known, but interorgan crosstalk in disease still lacks understanding. In particular, how tissue injury in one organ can drive injury at remote sites and trigger multiorgan failure with high mortality is poorly understood. As examples, acute kidney injury can trigger acute lung injury and cardiovascular dysfunction; pneumonia, sepsis or liver failure conversely can cause kidney failure; lung transplantation very frequently triggers acute kidney injury. Mechanistically, interorgan crosstalk after tissue injury could involve soluble mediators and their target receptors, cellular mediators, in particular immune cells, as well as newly identified neuro-immune connections. In this review, I will focus the discussion of deleterious interorgan crosstalk and its mechanistic concepts on one example, acute kidney injury-induced remote lung injury.

BI-1 ameliorates myocardial injury by activating the mitochondrial unfolded protein response and FUNDC1-related mitophagy in cardiorenal syndrome type 3

It has been suggested that mitochondrial dysfunction underlies the myocardial injury seen following cardiorenal syndrome type 3 (CRS-3). Both mitophagy and the mitochondrial unfolded protein response (UPR^mt) are protective programs that preserve mitochondrial homeostasis. Here, we explored whether Bax inhibitor-1 (BI-1) overexpression attenuates CRS-3-related myocardial injury through activation of mitophagy and the UPR^mt in cardiomyocytes. Following CRS-3 induction via renal ischemia-reperfusion injury, BI-1 transgenic (BI1^TG) mice showed greater preservation of myocardial integrity and relaxation function and less cardiomyocyte apoptosis than wild-type (WT) mice. Moreover, BI-1 overexpression attenuated CRS-3-mediated myocardial inflammation, as indicated by decreased MCP-1 and IL-6 expression and normalized ATP production in cardiomyocytes. After CRS-3 induction, mitophagy was inhibited in cardiomyocytes from WT mice, as indicated by both decreased Fundc1 transcription and mt-Keima fluorescence, and modest activation of the UPR^mt, denoted by a slight increase in Atf6 mRNA levels. By contrast, activation of mitophagy and marked UPR^mt upregulation were observed in cardiac tissue from BI1^TG mice. shRNA-mediated silencing of Fundc1 or Atf6 greatly impaired mitochondrial metabolism and survival in cultured cardiomyocytes overexpressing BI-1. Thus, upregulation of BI-1 expression aimed at activating mitophagy and the UPR^mt may represent a useful therapeutic approach for the treatment of CRS-3.

Interaction of Acute Respiratory Failure and Acute Kidney Injury on in-Hospital Mortality of Patients with Acute Exacerbation COPD

Purpose

Both acute respiratory failure (ARF) and acute kidney injury (AKI) are two common complications in patients with acute exacerbation of chronic obstructive pulmonary disease (AECOPD). Moreover, both ARF and AKI are reported as increasing the risk of mortality of patients with AECOPD. However, the interaction of ARF and AKI on the mortality of patients with AECOPD remains unknown. Therefore, the aim of this study is to investigate the joint effect of ARF and AKI on in-hospital mortality in AECOPD patients.

Patients and Methods

We performed a retrospective, observational cohort study of data from Nanjing First Hospital. The effect of AKI and ARF on in-hospital mortality was assessed using a multivariate logistic regression model. Additive interaction was assessed with the relative excess risk due to interaction.

Results

A total of 1647 participants were enrolled. ARF and AKI occurred in 515 (31.3%) and 357 (21.7%) patients, respectively. Overall, in-hospital mortality was 5.7%. The in-hospital mortality of the neither ARF nor AKI group, the ARF only group, the AKI only group, and both the ARF and AKI group were 0.8%, 7.0%, 7.5%, and 29.9%, respectively. After multivariate logistic regression analysis, the independent factors for in-hospital death included: albumin (OR 0.88, 95% CI 0.83–0.93, P < 0.001), ARF only (OR 8.53, 95% CI 3.64–19.99, P < 0.001), AKI only (OR 8.99, 95% CI 3.58–22.55, P < 0.001), and both ARF and AKI (OR 39.13, 95% CI 17.02–89.97, P < 0.001). The relative excess risk due to interaction was 22.62 (95% CI, 0.31 to 44.93), the attributable proportion due to interaction was 0.59 (95% CI, 0.36 to 0.79), and the synergy index was 2.46 (95% CI, 1.44 to 4.20), indicating ARF and AKI had a significant synergic effect on in-hospital mortality.

Conclusion

ARF and AKI had a synergistic effect on in-hospital mortality in AECOPD patients.

Additive harmful effects of acute kidney injury and acute heart failure on mortality in hospitalized patients

Background

Organ crosstalk between the kidney and the heart has been suggested. Acute kidney injury (AKI) and acute heart failure (AHF) are well-known independent risk factors for mortality in hospitalized patients. This study aimed to investigate if these conditions have an additive effect on mortality in hospitalized patients, as this has not been explored in previous studies.

Methods

We retrospectively reviewed the records of 101,804 hospitalized patients who visited two tertiary hospitals in the Republic of Korea over a period of 5 years. AKI was diagnosed using serum creatinine-based criteria, and AHF was classified using International Classification of Diseases codes within 2 weeks after admission. Patients were divided into four groups according to the two conditions. The primary outcome was all-cause mortality.

Results

AKI occurred in 6.8% of all patients (n = 6,920) and AHF in 1.2% (n = 1,244). Three hundred thirty-one patients (0.3%) developed both conditions while AKI alone was present in 6,589 patients (6.5%) and AHF alone in 913 patients (0.9%). Among the 5,181 patients (5.1%) who died, 20.8% died within 1 month. The hazard ratio for 1-month mortality was 29.23 in patients with both conditions, 15.00 for AKI only, and 3.39 for AHF only. The relative excess risk of interaction was 11.85 (95% confidence interval, 2.43‒21.27), and was more prominent in patients aged <75 years and those without chronic heart failure.

Conclusion

AKI and AHF have a detrimental additive effect on short-term mortality in hospitalized patients.

Incidence and Outcomes Associated With Clostridioides difficile Infection in Solid Organ Transplant Recipients

IMPORTANCE

Little is known about the incidence and outcomes of Clostridioides difficile infection (CDI) in solid organ transplant (SOT) recipients.

OBJECTIVE

To estimate the CDI incidence and outcomes in SOT recipients.

DESIGN, SETTING, AND PARTICIPANTS

A population-based cohort study was conducted using administrative health care data for all Ontario, Canada, residents who received organ allografts from April 1, 2003, to December 31, 2017; March 31, 2020, was the end of the study period.

MAIN OUTCOMES AND MEASURES

The primary outcome was hospital admission with CDI diagnosis. The secondary outcomes included all-cause death, intensive care unit admission, acute kidney injury requiring dialysis, and fulminant CDI comprising any of the following: toxic megacolon, ileus, perforation, or colectomy. The association between short- vs long-term mortality (ie, death occurring within or after 90 days post-CDI) and the following variables was evaluated: age, sex, Deyo-Charlson Comorbidity Index, SOT type, early- vs late-onset CDI, fulminant CDI, intensive care unit admission, and acute kidney injury requiring acute dialysis.

RESULTS

Overall, 10 724 SOT recipients (6901 [64.4%] men; median age, 54 [IQR, 44-62] years) were eligible. Kidney transplant was the most common SOT type (6453 [60.2%]). The median follow-up time was 5.0 (IQR, 2.3-8.8) years, resulting in 61 987 person-years of follow-up. A total of 726 patients (6.8%) were hospitalized with CDI. The 1-year CDI incidence significantly increased in annual cohorts (ie, from 23.1; 95% CI, 12.8-41.8 per 1000 person-years in 2004 to 46.7; 95% CI, 35.0-62.3 per 1000 person-years in 2017; P = .001). Clostridioides difficile was associated with a 16.8% rate (n = 122) of 90-day mortality. In patients who underwent kidney transplant, CDI was typically late-onset (median interval, 2.2; IQR, 0.4-6.0 years) compared with recipients of other organs. Acute kidney injury requiring dialysis was significantly associated with short-term (adjusted odds ratio [aOR], 1.86; 95% CI, 1.07-3.26) and long-term (adjusted hazard ratio [aHR], 1.89; 95% CI, 1.29-2.78) mortality, and late-onset CDI was also significantly associated with a greater risk of short-term (aOR, 4.26; 95% CI, 2.51-7.22) and long-term (aHR, 2.49; 95% CI, 1.78-3.49) mortality.

CONCLUSIONS AND RELEVANCE

In this study, increasing CDI trends in annual cohorts of SOT recipients were observed. Posttransplant CDI was associated with mortality, and late-onset CDI was associated with a greater risk of death than early-onset CDI. These findings suggest that preventive strategies should not be limited to the initial months following transplantation. Comprehensive therapeutic approaches targeting acute kidney injury risk factors in SOT recipients may reduce short- and long-term post-CDI mortality.