Messengers without borders: mediators of systemic inflammatory response in AKI

The role of natural killer T cells in sepsis-associated acute kidney injury

The condition of sepsis, defined by the misregulation of the body's defensive mechanisms against infection, culminates in the potential for catastrophic organ damage and stands as a primary driver of mortality in Intensive Care Units (ICU) settings. Among patients in a critical condition, sepsis is a predominant factor in the development of acute kidney injury (AKI), and the death rate among those with both sepsis and AKI is considerably higher, underscoring the importance of addressing this health crisis. Sepsis-associated acute kidney injury (S-AKI) is a complex process involving inflammation, microcirculatory issues, and metabolic disorders. Among these, the inflammatory response has become a focal point of interest. Bridging the innate and adaptive immunity, natural killer T (NKT) cells can be rapidly activated in sepsis, contributing to sepsis-associated injury and downstream activation of inflammatory cells through the emission of Th1 or Th2 cytokines. They also contribute to S-AKI through the TNF-α/FasL and perforin pathways. Alpha-Galactosylceramide (α-GalCer), acting as a powerful activator for type I NKT (iNKT) cells, is able to regulate the secretory profile of iNKT cells, responding to the pro-inflammatory response and immunosuppressive profiles of sepsis. This review examines the part played by NKT cells in S-AKI and whether α-Galcer could function as a significant regulator in sepsis, based on studies of regression-related mechanisms.

SARS-CoV-2 nucleocapsid protein induces a Mincle-dependent macrophage inflammatory response in acute kidney injury

BACKGROUND

Although the COVID-19 pandemic has receded, the SARS-CoV-2 virus still poses a significant threat to individuals with pre-existing renal conditions, leading to severe acute kidney injury (AKI). However, the underlying mechanisms remain poorly understood.

METHODS

In this study, we used ultrasound microbubble technology to transfect and overexpress the SARS-CoV-2 nucleocapsid (N) protein in the kidneys of IRI (ischemia-reperfusion injury) and Cis (cisplatin) induced AKI mice. Additionally, we generated macrophage-specific Mincle knockout mice to investigate the amplifying effects of the SARS-CoV-2 N protein on AKI renal injury and the critical regulatory role of macrophage inducible C-type lectin (Mincle). Finally, we employed Mincle-neutralizing antibodies to intervene in the SARS-CoV-2 N-induced exacerbation of kidney injury in AKI.

RESULTS

We found that the specific overexpression of the SARS-CoV-2 N protein significantly aggravates kidney injury in the context of AKI. Mechanistically, we found that the exacerbation of acute kidney injury by the SARS-CoV-2 N protein is dependent on Mincle, as the SARS-CoV-2 N protein activates Mincle to enhance the Syk/NF-κB signaling pathway, leading to damage and inflammation of renal tubular epithelial cells. This was confirmed in Mincle knockout mice and cells, where Mincle knockout alleviated the renal tubular injury and inflammation caused by SARS-CoV-2 N transfection. Importantly, the use of anti-Mincle neutralizing antibodies could effectively mitigate the acute kidney injury exacerbated by the SARS-CoV-2 N protein.

CONCLUSIONS

In summary, we identified the SARS-CoV-2 N protein as a key mediator of kidney injury in AKI and demonstrated that it exacerbates the injury through a Mincle-dependent mechanism. Targeting Mincle may represent a novel therapeutic strategy for treating COVID-19-related acute kidney injury.

The Role of Mitochondrial AKT1 Signaling in Renal Tubular Injury of Metabolic Syndrome

Introduction

Metabolic syndrome (MetS) is increasingly recognized as a contributor to kidney disease, yet the underlying mechanisms remain poorly defined. Recent studies suggest a pivotal role for mitochondrial dysfunction in renal injury. We hypothesized that mitochondrial AKT1 signaling in renal tubules plays a critical role in MetS-related kidney injuries.

Methods

MetS was induced in a 8-week-old C57BL/6 male mice using a high-fat diet (HFD) for 4 months compared with controls on a standard chow diet. Additional experiments were conducted in DB/DB diabetic mice and their controls (WT and DB/WT) to validate findings. Renal metabolic parameters, mitochondrial AKT1 signaling, and markers of kidney injury were assessed.

Results

MetS mice exhibited significant weight gain, altered glucose handling, and decreased energy expenditure. Although kidney size and basic renal function (blood urea nitrogen [BUN], creatinine) were unchanged, markers of renal damage, including proteinuria (P = 0.0002) and KIM-1 (P < 0.0001) were elevated. Histological analyses showed increased tubular injury (P < 0.0001) and glomerulosclerosis (P = 0.0004). Transmission electron microscopy revealed aberrant mitochondria (P < 0.001), with reduced cristae length (P = 0.012) and numbers (P < 0.001). Immunohistochemistry, immunofluorescence, and Western blot analysis confirmed increased phosphorylated AKT1 (pAKT1) in the mitochondria of renal tubules (P = 0.0474), findings corroborated in DB/DB mice. This translocation of pAKT1 into mitochondria correlated with decreased cell viability upon inhibition of heat shock protein 90, indicating a dependency on mitochondrial AKT1 for cell survival.

Conclusion

These findings underscore the mechanistic link between mitochondrial AKT1 signaling and renal tubular injury in MetS. Targeting mitochondrial dysfunction may offer new avenues for preventing and treating kidney diseases in patients with MetS.

Inflammation and aging-related disease: A transdisciplinary inflammaging framework

Inflammaging, a state of chronic, progressive low-grade inflammation during aging, is associated with several adverse clinical outcomes, including frailty, disability, and death. Chronic inflammation is a hallmark of aging and is linked to the pathogenesis of many aging-related diseases. Anti-inflammatory therapies are also increasingly being studied as potential anti-aging treatments, and clinical trials have shown benefits in selected aging-related diseases. Despite promising advances, significant gaps remain in defining, measuring, treating, and integrating inflammaging into clinical geroscience research. The Clin-STAR Inflammation Research Interest Group was formed by a group of transdisciplinary clinician-scientists with the goal of advancing inflammaging-related clinical research and improving patient-centered care for older adults. Here, we integrate insights from nine medical subspecialties to illustrate the widespread impact of inflammaging on diseases linked to aging, highlighting the extensive opportunities for targeted interventions. We then propose a transdisciplinary approach to enhance understanding and treatment of inflammaging that aims to improve comprehensive care for our aging patients.

Renal and Vascular Functional Decline in Aged Low Birth Weight Murine Adults

INTRODUCTION

Maternal undernutrition (MUN)-induced low birth weight (LBW) neonates are susceptible to the development of high blood pressure and kidney disease later in life, although the underlying pathological causes remain unclear. The study here investigated the role of renal oxidative stress, impairment of vascular function, and altered sensitivity to angiotensin II (Ang II) as factors that contribute to these pathologies in aged LBW mice.

METHODS

LBW offspring were generated using a combined protein and caloric restricted MUN mouse model. The resulting LBW offspring were examined 1 year after birth for mean arterial blood pressure (MABP) (carotid artery catheterization), renal blood flow (RBF) (laser Doppler flowmetry), glomerular filtration rate (GFR) (sinistrin clearance), vasoreactivity (myograph), renal vascular density (CD31 staining), and reactive oxygen species (ROS) (ROS probes). Immunoblotting examined Ang II type 1 receptor (AT1R), soluble guanylate cyclase (sGC), and antioxidant systems. Pharmacological agents delivered to animals included the sGC stimulator δ-aminolevulinic acid (ALA), the AT1R inhibitor losartan, the antioxidant ethyl pyruvate (EP), and the toll-like receptor 4 inhibitor TAK242.

RESULTS

After 1 year, MABP was increased, while RBF, GFR, vascular reactivity, renal vascular density, and sGC were all reduced in the LBW aged adult. All four pharmacological agents improved MABP, RBF, GFR, vascular density, and vascular reactivity. Renal ROS was increased in the LBW adult but was reduced by ALA, EP, and TAK242 treatment. AT1R was upregulated in the LBW adult, while sGC was decreased, an effect reversed by ALA treatment. Endogenous antioxidant systems, including SOD1, catalase, and glutathione were downregulated in the LBW adult.

CONCLUSION

MUN-induced LBW mice experience increased Ang II sensitivity and oxidative stress. The increased Ang II sensitivity and ROS generation influences vascular density and reactivity, which drive an increase in MABP, and a concomitantly decrease in RBF and glomerular filtration. Pharmacological intervention that inhibits AT1R, enhances levels of sGC, reduces ROS, or inhibits toll-like receptor 4 improves vascular and renal function in the LBW adult.

Berberine alleviated contrast-induced acute kidney injury by mitophagy-mediated NLRP3 inflammasome inactivation in a mice model

The incidence of contrast-induced acute kidney injury (CI-AKI) has escalated to become the third most prevalent cause of hospital-acquired AKI, with a lack of efficacious interventions. Berberine (BBR) possesses diverse pharmacological effects and exhibits renoprotective properties; however, limited knowledge exists regarding its impact on CI-AKI. Therefore, our study aimed to investigate the protective effects and underlying mechanisms of BBR on CI-AKI in a mice model, focusing on the nucleotide-binding oligomerization domain-like pyrin domain-containing protein 3 (NLRP3) inflammasome and mitophagy. The CI-AKI mice model was established by administering NG-nitro-L-arginine methyl ester (L-NAME) (10 mg/kg), indomethacin (10 mg/kg), and iohexol (11 g/kg) following water deprivation. A pretreatment of 100 mg/kg of BBR was orally administered to the mice for two weeks. Renal injury markers, damage-associated molecular patterns (DAMPs), renal histopathology, mitochondrial morphology, autophagosomes, and potential mechanisms were investigated. BBR effectively reduced levels of renal injury biomarkers such as serum cystatin C, urea nitrogen, and creatinine, downregulated the protein level of kidney injury molecule 1 (KIM1), and mitigated renal histomorphological damage. Moreover, BBR reduced DAMPs, including high mobility group box-1 (HMGB1), heat shock protein 70 (HSP70), and uric acid (UA). It also alleviated oxidative stress and inflammatory factors such as monocyte chemotactic protein-1 (MCP-1), tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), and interleukin-1 beta (IL-1β). Furthermore, the activation of NLRP3 inflammasome was attenuated in the BBR pretreatment group, as evidenced by both mRNA and protein levels. Electron microscopy and western blotting examination revealed that BBR mitigated mitochondrial damage and enhanced mitophagy. Additionally, BBR increased the P-AMPK/AMPK ratio. These findings indicated that BBR exerted a protective effect against CI-AKI by suppressing NLRP3 inflammasome activation and modulating mitophagy, providing a potential therapeutic strategy for its prevention.

The Association of Ischemia Type and Duration with Acute Kidney Injury after Robot-Assisted Partial Nephrectomy

BACKGROUND

Acute kidney injury (AKI) after robot-assisted partial nephrectomy (RAPN) is a robust surrogate for chronic kidney disease. The objective of this study was to evaluate the association of ischemia type and duration during RAPN with postoperative AKI.

MATERIALS AND METHODS

We reviewed all patients who underwent RAPN at our institution since 2011. The ischemia types were warm ischemia (WI), selective artery clamping (SAC), and zero ischemia (ZI). AKI was defined according to the Risk Injury Failure Loss End-Stage (RIFLE) criteria. We calculated ischemia time thresholds for WI and SAC using the Youden and Liu indices. Logistic regression and decision curve analyses were assessed to examine the association with AKI.

RESULTS

Overall, 154 patients met the inclusion criteria. Among all RAPNs, 90 (58.4%), 43 (28.0%), and 21 (13.6%) were performed with WI, SAC, and ZI, respectively. Thirty-three (21.4%) patients experienced postoperative AKI. We extrapolated ischemia time thresholds of 17 min for WI and 29 min for SAC associated with the occurrence of postoperative AKI. Multivariable logistic regression analyses revealed that WIT ≤ 17 min (odds ratio [OR] 0.1, p < 0.001), SAC ≤ 29 min (OR 0.12, p = 0.002), and ZI (OR 0.1, p = 0.035) significantly reduced the risk of postoperative AKI.

CONCLUSIONS

Our results confirm the commonly accepted 20 min threshold for WI time, suggest less than 30 min ischemia time when using SAC, and support a ZI approach if safely performable to reduce the risk of postoperative AKI. Selecting an appropriate ischemia type for patients undergoing RAPN can improve short- and long-term functional kidney outcomes.

Probiotics in septic acute kidney injury, a double blind, randomized control trial

INTRODUCTION

During acute kidney injury (AKI) due to sepsis, the intestinal microbiota changes to dysbiosis, which affects the kidney function recovery (KFR) and amplifies the injury. Therefore, the administration of probiotics could improve dysbiosis and thereby increase the probability of KFR.

METHODS

In this double-blind clinical trial, patients with AKI associated with sepsis were randomized (1:1) to receive probiotics or placebo for 7 consecutive days, with the objectives of evaluate the effect on KFR, mortality, kidney replacement therapy (KRT), urea, urine volume, serum electrolytes and adverse events at day 7.

RESULTS

From February 2019 to March 2022, a total of 92 patients were randomized, 48 to the Probiotic and 44 to Placebo group. When comparing with placebo, those in the Probiotics did not observe a higher KFR (HR 0.93, 0.52-1.68, p = 0.81), nor was there a benefit in mortality at 6 months (95% CI 0.32-1.04, p = 0.06). With probiotics, urea values decreased significantly, an event not observed with placebo (from 154 to 80 mg/dl, p = 0.04 and from 130 to 109 mg/dl, p = 0.09, respectively). Urinary volume, need for KRT, electrolyte abnormalities, and adverse events were similar between groups. (ClinicalTrial.gov NCT03877081) (registered 03/15/2019).

CONCLUSION

In AKI related to sepsis, probiotics for 7 consecutive days did not increase the probability of KFR, nor did other variables related to clinical improvement, although they were safe.

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.

Low-Dose vasopressin and renal perfusion in pediatric cardiac surgery

Background

Congenital heart surgeries are associated with post-bypass renal and cardiac dysfunctions. The use of low-dose vasopressin has been found to be beneficial in adult cardiac surgeries.

Objective

To assess the hemodynamic and renal effects of patients undergoing on-pump pediatric cardiac surgery under general anesthesia (GA) with low-dose vasopressin infusion.

Design

Prospective randomized controlled study.

Setting

Operation room and ICU, tertiary care teaching hospital.

Patients

Fifty-five pediatric cardiac patients undergoing repair for congenital heart diseases (CHD).

Interventions

Low-dose vasopressin infusion in the study group and placebo in the control group.

Measurements and Main Results

Renal near-infrared spectroscopy (NIRS), serum NGAL, and inflammatory mediators-IL6 and IL8 along with other renal and hemodynamic parameters in the perioperative period were recorded. Diastolic blood pressure (DBP) and cardiac index were significantly higher in the vasopressin group. Inflammatory markers were significantly high in the immediate postoperative period in all patients which later stabilized in the next 48 h but showed similar trends in both groups. Low-dose vasopressin infusion did not improve either renal perfusion or function. The duration of mechanical ventilation and length of hospital stay, the incidence of AKI development, and transfusion requirements were marginally lower in the vasopressin group, although not significant.

Conclusion

Low-dose vasopressin infusion improved hemodynamics and showed a decreased incidence of complications. However, it failed to show any benefit of renal function and overall outcome in pediatric cardiac surgery.

HMGB1 Is a Prognostic Factor for Mortality in Acute Kidney Injury Requiring Renal Replacement Therapy

INSTRUCTION

High mobility group box 1 (HMGB1) is a pro-inflammatory cytokine that reportedly causes kidney injury and other organ damage in rodent acute kidney injury (AKI) models. However, it remains unclear whether HMGB1 is associated with clinical AKI and related outcomes. This study aimed to evaluate the association with HMGB1 and prognosis of AKI requiring continuous renal replacement therapy (CRRT).

METHODS

AKI patients treated with CRRT in our intensive care unit were enrolled consecutively during 2013-2016. Plasma HMGB1 was measured on initiation. Classic initiation was defined as presenting at least one of the following conventional indications: hyperkalemia (K ≥6.5 mEq/L), severe acidosis (pH <7.15), uremia (UN >100 mg/dL), and diuretics-resistant pulmonary edema. Early initiation was defined as presenting no conventional indications. The primary outcome was defined as 90-day mortality.

RESULTS

A total of 177 AKI patients were enrolled in this study. HMGB1 was significantly associated with the primary outcome (hazard ratio, 1.06; 95% CI, 1.04-1.08). When the patients were divided into two-by-two groups by the timing of CRRT initiation and the HMBG1 cutoff value obtained by receiver operating curve (ROC) analysis, the high HMGB1 group (>10 ng/mL) with classic initiation was significantly associated with the primary outcome compared with the others, even after adjusting for other factors including the nonrenal serial organ failure assessment (SOFA) score.

CONCLUSION

HMGB1 was associated with 90-day mortality in AKI patients requiring CRRT. Notably, the highest mortality was observed in the high HMGB1 group with classic initiation. These findings suggest that CRRT should be considered for AKI patients with high HMGB1, regardless of the conventional indications.

Neuroimmune Control of Inflammation in Acute Kidney Injury: From Mouse Models to Human Disease

Inflammation is common in patients with acute kidney injury (AKI) and contributes to increased risk of morbidity and mortality. The central nervous system plays an important role in the immune and inflammatory pathways of AKI. In this review, we discuss the preclinical evidence for the neural pathways associated with neuromodulation in AKI, as well as clinical trials that translate these observations into the clinical context. The ultimate goal of these trials is to design strategies using noninvasive approaches, such as splenic pulsed ultrasonography, to prevent or attenuate inflammatory conditions at the bedside, including AKI.

Prognostic Value of the Red Blood Cell Distribution Width-to-Albumin Ratio in Critically Ill Older Patients with Acute Kidney Injury: A Retrospective Database Study

Background. There is no evidence suggesting that red blood cell distribution width-to-albumin ratio (RA) predicts outcomes in severely ill older individuals with acute kidney injury (AKI). We hypothesized that RA is associated with all-cause mortality in critically ill older patients with AKI. Methods. We recorded demographics, laboratory tests, comorbidities, vital signs, and other clinical information from the MIMIC-III V1.4 dataset. The primary endpoint was 90-day all-cause mortality, and the secondary endpoints were 30-day mortality, one-year mortality, renal replacement treatment (RRT), duration of stay in the intensive care unit (ICU), sepsis, and septic shock. We generated Cox proportional hazards and logistic regression models to determine RA’s prognostic values and subgroup analyses to determine the subgroups’ mortality. We conducted a Pearson correlation analysis on RA and C-reactive protein (CRP) in the cohort of patients from the Second Affiliated Hospital of Wenzhou Medical University. Results. A total of 6,361 patients were extracted from MIMIC-III based on the inclusion and exclusion criteria. RA levels directly and linearly correlated with 90-day all-cause mortality. After controlling for ethnicity, gender, age, and other confounding variables in multivariate analysis, higher RA was significantly associated with an increased risk of 30-day, 90-day, and one-year all-cause mortality as opposed to the reduced levels of RA (tertile 3 vs. tertile 1: hazard ratios (HRs), 95% confidence intervals (CIs): 1.70, 1.43–2.01; 1.90, 1.64–2.19; and 1.95, 1.72–2.20, respectively). These results suggested that elevated levels of RA were linked to an elevated risk of 30-day, 90-day, and one-year all-cause death. There was a similar trend between RA and the use of RRT, length of stay in ICUs, sepsis, and septic shock. The subgroup analysis did not reveal any considerable interplay among strata. When areas under the curve were compared, RA was a weaker predictor than the SAPS II score but a stronger predictor than red blood cell distribution width (RDW) or albumin alone ( $P<0.001$ ); RA combined with SAPS II has better predictive power than SAPS II alone ( $P<0.001$ ). The Second Affiliated Hospital of Wenzhou Medical University cohort showed that CRP positively correlated with RA, with a coefficient of 0.2607 ( $P<0.001$ ). Conclusions. RA was an independent prognostic predictor in critically ill older patients with AKI, and greater RA was linked to a higher probability of death. The risk of AKI is complicated when RRT occurs; sepsis and septic shock increase with RA levels.

Early effects of bone marrow-derived mononuclear cells on lung and kidney in experimental sepsis

BACKGROUND

In experimental sepsis, functional and morphological effects of bone marrow-derived mononuclear cell (BMDMC) administration in lung tissue have been evaluated 1 and 7 days after therapy. However, to date no study has evaluated the early effects of BMDMCs in both lung and kidney in experimental polymicrobial sepsis.

MATERIAL AND METHODS

Twenty-five female C57BL/6 mice were randomly divided into the following groups: 1) cecal ligation and puncture (CLP)-induced sepsis; and 2) Sham (surgical procedure without CLP). After 1 h, CLP animals received saline (NaCl 0.9%) (CLP-Saline) or 10⁶ BMDMCs (CLP-Cell) via the jugular vein. At 6, 12, and 24 h after saline or BMDMC administration, lungs and kidneys were removed for histology and molecular biology analysis.

RESULTS

In lungs, CLP-Saline, compared to Sham, was associated with increased lung injury score (LIS) and keratinocyte chemoattractant (KC) mRNA expression at 6, 12, and 24 h. BMDMCs were associated with reduced LIS and KC mRNA expression regardless of the time point of analysis. Interleukin (IL)- 10 mRNA content was higher in CLP-Cell than CLP-Saline at 6 and 24 h. In kidney tissue, CLP-Saline, compared to Sham, was associated with tubular cell injury and increased neutrophil gelatinase-associated lipocalin (NGAL) levels, which were reduced after BMDMC therapy at all time points. Surface high-mobility-group-box (HMGB)- 1 levels were higher in CLP-Saline than Sham at 6, 12, and 24 h, whereas nuclear HMGB-1 levels were increased only at 24 h. BMDMCs were associated with decreased surface HMGB-1 and increased nuclear HMGB-1 levels. Kidney injury molecule (KIM)- 1 and IL-18 gene expressions were reduced in CLP-Cell compared to CLP-Saline at 12 and 24 h.

CONCLUSION

In the present experimental polymicrobial sepsis, early intravenous therapy with BMDMCs was able to reduce lung and kidney damage in a time-dependent manner. BMDMCs thus represent a potential therapy in well-known scenarios of sepsis induction.

PURPOSE

To evaluate early bone marrow-derived mononuclear cell (BMDMC) therapy on lung and kidney in experimental polymicrobial sepsis.

METHODS

Twenty-five female C57BL/6 mice were randomly divided into the following groups: cecal ligation and puncture (CLP)-induced sepsis; and sham (surgical procedure without CLP). After 1 h, CLP animals received saline (CLP-saline) or 10⁶ BMDMCs (CLP-cell) via the jugular vein. Lungs and kidneys were evaluated for histology and molecular biology after 6, 12, and 24 h.

RESULTS

In lungs, BMDMCs reduced the lung injury score and keratinocyte chemoattractant mRNA expression regardless of the time point of analysis; interleukin-10 mRNA content was higher in CLP-cell than CLP-saline at 6 and 24 h. In kidneys, BMDMCs reduced neutrophil gelatinase-associated lipocalin levels at all time points. BMDMCs decreased surface high mobility group box (HMGB)- 1 but increased nuclear HMGB-1 levels.

CONCLUSION

Early BMDMC therapy reduced lung and kidney damage in a time-dependent manner.

The Role of the Superior Cervical Sympathetic Ganglion in Ischemia Reperfusion-Induced Acute Kidney Injury in Rats

Acute kidney injury (AKI) has been found to be a serious clinical problem with high morbidity and mortality, and is associated with acute inflammatory response and sympathetic activation that subsequently play an important role in the development of AKI. It is well known that the sympathetic nervous system (SNS) and immune system intensely interact and mutually control each other in order to maintain homeostasis in response to stress or injury. Evidence has shown that the superior cervical sympathetic ganglion (SCG) participates in the bidirectional network between the immune and the SNS, and that the superior cervical ganglionectomy has protective effect on myocardial infarction, however, the role of the SCG in the setting of renal ischemic reperfusion injury has not been studied. Here, we sought to determine whether or not the SCG modulates renal ischemic reperfusion (IR) injury in rats. Our results showed that bilateral superior cervical ganglionectomy (SCGx) 14 days before IR injury markedly reduced the norepinephrine (NE) in plasma, and down-regulated the increased expression of tyrosine hydroxylase (TH) in the kidney and hypothalamus. Sympathetic denervation by SCGx in the AKI group increased the level of blood urea nitrogen (BUN) and kidney injury molecule-1 (KIM-1), and exacerbated renal pathological damage. Sympathetic denervation by SCGx in the AKI group enhanced the expression of pro-inflammatory cytokines in plasma, kidney and hypothalamus, and increased levels of Bax in denervated rats with IR injury. In addition, the levels of purinergic receptors, P2X3R and P2X7R, in the spinal cord were up-regulated in the denervated rats of the IR group. In conclusion, these results demonstrate that the sympathetic denervation by SCGx aggravated IR-induced AKI in rats via enhancing the inflammatory response, thus, the activated purinergic signaling in the spinal cord might be the potential mechanism in the aggravated renal injury.

Bioprotective and Functional Effect of Carnosine on Sepsis Induced Renal Damage in Male Albino Rat Model through Targeting IL-1β and TNF-α Production

Acute kidney injury (AKI), one of the frequently diagnosed and serious sepsis induced complication has high morbidity and mortality. The present study investigated the bioprotective and functional effect of carnosine on AKI induced pathological damage in Male Albino rat model in vivo. AKI in Albino rats was induced by cecal ligation and puncture surgery where as TNF-α and IL-1β levels were detected using ELISA assay. Protein expression was examined by western blotting and pathological damage using hematoxylin and eosin (H&E). Treatment with carnosine suppressed AKI induced urea nitrogen and creatinine in Male Albino rat serum in dose-dependent manner. Development of sepsis mediated renal injury in Albino rats was also effectively prevented on treatment with carnosine. Secretion of AKI-induced IL-1β, IL-18, and TNF-α in renal tissues was alleviated significantly in Albino rats by carnosine treatment. Additionally, in carnosine-treated Albino rats renal tissues AKI induced Bax expression was alleviated while as Bcl-2 was promoted compared to AKI Albino rats. Carnosine treatment improved the survival rate of the Albino rats with AKI. Carnosine inhibits renal tissue damage and increases survival rate in AKI Albino rat model. The mechanism involves alleviation of inflammatory cytokine secretion and promotion of Bcl-2 expression. Thus, carnosine may be used as a therapeutic agent for treatment of AKI.

The Mechanism of CD8+ T Cells for Reducing Myofibroblasts Accumulation during Renal Fibrosis

Renal fibrosis is a hallmark of chronic kidney disease (CKD) and a common manifestation of end-stage renal disease that is associated with multiple types of renal insults and functional loss of the kidney. Unresolved renal inflammation triggers fibrotic processes by promoting the activation and expansion of extracellular matrix-producing fibroblasts and myofibroblasts. Growing evidence now indicates that diverse T cells and macrophage subpopulations play central roles in the inflammatory microenvironment and fibrotic process. The present review aims to elucidate the role of CD8⁺ T cells in renal fibrosis, and identify its possible mechanisms in the inflammatory microenvironment.

Risk Factors of Acute Kidney Injury in ECMO Patients: A Systematic Review and Meta-Analysis

PURPOSE

Acute kidney injury (AKI) is one of the most common complications in patients receiving extracorporeal membrane oxygenation (ECMO), but there is no systematic analysis regarding its risk factors. This meta-analysis aims to determine the risk factors of AKI in adult patients with ECMO treatment.

METHODS

Two authors independently carried out a systemic literature search using PubMed, Web of Science, and Embase until April 20, 2020 (inclusive) to enroll 12 studies reporting the necessary clinical characteristics. The Gender (male), age, APACHE II score, SOFA score, cancer, diabetes mellitus (DM), intra-aortic balloon pump (IABP), postcardiotomy, and ECMO supporting duration were pooled for further analysis by STATA.

RESULTS

Adult patients receiving ECMO who develop AKI and severe AKI incidents are usually older or have a higher APACHE II scores; in addition, severe AKI is related to higher SOFA scores, DM, and longer duration of ECMO support.

CONCLUSIONS

Patients with these clinical characteristics should be paid more attention during ECMO. There remains a need for additional studies to validate these conclusions and to detect additional AKI risk factors for ECMO patients.

Role of Damage-Associated Molecular Patterns in Septic Acute Kidney Injury, From Injury to Recovery

Damage-associated molecular patterns (DAMPs) are a group of immunostimulatory molecules, which take part in inflammatory response after tissue injury. Kidney-specific DAMPs include Tamm-Horsfall glycoprotein, crystals, and uromodulin, released by tubular damage for example. Non-kidney-specific DAMPs include intracellular particles such as nucleus [histones, high-mobility group box 1 protein (HMGB1)] and cytosol parts. DAMPs trigger innate immunity by activating the NRLP3 inflammasome, G-protein coupled class receptors or the Toll-like receptor. Tubular necrosis leads to acute kidney injury (AKI) in either septic, ischemic or toxic conditions. Tubular necrosis releases DAMPs such as histones and HMGB1 and increases vascular permeability, which perpetuates shock and hypoperfusion via Toll Like Receptors. In acute tubular necrosis, intracellular abundance of NADPH may explain a chain reaction where necrosis spreads from cell to cell. The nature AKI in intensive care units does not have preclinical models that meet a variation of blood perfusion or a variation of glomerular filtration within hours before catecholamine infusion. However, the dampening of several DAMPs in AKI could provide organ protection. Research should be focused on the numerous pathophysiological pathways to identify the relative contribution to renal dysfunction. The therapeutic perspectives could be strategies to suppress side effect of DAMPs and to promote renal function regeneration.

The role of phytochemicals in sepsis: A mechanistic and therapeutic perspective

Sepsis and septic shock are still a leading cause of mortality and morbidity in intensive care units worldwide. Sepsis is an uncontrolled and excessive response of the innate immune system toward the invading infectious microbes, characterized by the hyper-production of pro-inflammatory mediators such as interleukin (IL)-1β, IL-6, tumor-necrosis factor (TNF)-α, and high-mobility group box 1 (HMGB1). In severe sepsis, the overwhelming production of pro-inflammatory cytokines and reactive oxygen species may compromise organ function and lead to the induction of abnormal apoptosis in different organs, resulting in multiple organ dysfunction syndrome and death. Hence, compounds that are able to attenuate inflammatory responses may have therapeutic potential for sepsis treatment. Understanding the pathophysiology and underlying molecular mechanisms of sepsis may provide useful insights in the discovery and development of new effective therapeutics. Therefore, numerous studies have invested much effort into elucidating the mechanisms involved with the onset and development of sepsis. The present review mainly focuses on the molecules and signaling pathways involved in the pathogenicity of sepsis. Additionally, several well-known natural bioactive herbal compounds and phytochemicals, which have shown protective and therapeutic effects with regard to sepsis, as well as their mechanisms of action, are presented. This review suggests that these phytochemicals are able to attenuate the overwhelming inflammatory responses developed during sepsis by modulating different signaling pathways. Moreover, the anti-inflammatory and cytoprotective activities of phytochemicals make them potent compounds to be included as complementary therapeutic agents in the diets of patients suffering from sepsis in an effort to alleviate sepsis and its life-threatening complications, such as multi-organ failure.

Tubular mitochondrial AKT1 is activated during ischemia reperfusion injury and has a critical role in predisposition to chronic kidney disease

Kidney tubular dysfunction contributes to acute kidney injury and to the transition to chronic kidney disease. Although tubular mitochondria have been implicated in the pathophysiology of kidney failure, the mechanisms are not yet clear. Here, we demonstrated that ischemia-reperfusion injury induced acute translocation and activation of mitochondrial protein kinase B (also known as AKT1) in the kidney tubules. We hypothesized that mitochondrial AKT1 signaling protects against the development of acute kidney injury and subsequent chronic kidney disease. To test this prediction, we generated two novel kidney tubule-specific transgenic mouse strains with inducible expression of mitochondria-targeted dominant negative AKT1 or constitutively active AKT1, using a Cre-Lox strategy. Inhibition of mitochondrial AKT1 in mitochondria-targeted dominant negative AKT1 mice aggravated azotemia, tubular injuries, kidney fibrosis, glomerulosclerosis, and negatively impacted survival after ischemia-reperfusion injury. Conversely, enhancing tubular mitochondrial AKT1 signaling in mitochondria-targeted constitutively active AKT1 mice attenuated kidney injuries, protected kidney function, and significantly improved survival after ischemia-reperfusion injury (76.9% vs. 20.8%, respectively). Uncoupled mitochondrial respiration and increased oxidative stress was found in the kidney tubules when mitochondria AKT1 was inhibited, supporting the role of mitochondrial dysfunction in the pathophysiology of kidney failure. Thus, our studies suggest tubular mitochondrial AKT1 signaling could be a novel target to develop new strategies for better prevention and treatment of kidney injury.

Immunopathophysiology of trauma-related acute kidney injury

Physical trauma can affect any individual and is globally accountable for more than one in every ten deaths. Although direct severe kidney trauma is relatively infrequent, extrarenal tissue trauma frequently results in the development of acute kidney injury (AKI). Various causes, including haemorrhagic shock, rhabdomyolysis, use of nephrotoxic drugs and infectious complications, can trigger and exacerbate trauma-related AKI (TRAKI), particularly in the presence of pre-existing or trauma-specific risk factors. Injured, hypoxic and ischaemic tissues expose the organism to damage-associated and pathogen-associated molecular patterns, and oxidative stress, all of which initiate a complex immunopathophysiological response that results in macrocirculatory and microcirculatory disturbances in the kidney, and functional impairment. The simultaneous activation of components of innate immunity, including leukocytes, coagulation factors and complement proteins, drives kidney inflammation, glomerular and tubular damage, and breakdown of the blood-urine barrier. This immune response is also an integral part of the intense post-trauma crosstalk between the kidneys, the nervous system and other organs, which aggravates multi-organ dysfunction. Necessary lifesaving procedures used in trauma management might have ambivalent effects as they stabilize injured tissue and organs while simultaneously exacerbating kidney injury. Consequently, only a small number of pathophysiological and immunomodulatory therapeutic targets for TRAKI prevention have been proposed and evaluated.

Neuroimmune Mechanisms in Signaling of Pain During Acute Kidney Injury (AKI)

Acute kidney injury (AKI) is a significant global health concern. The primary causes of AKI include ischemia, sepsis and nephrotoxicity. The unraveled interface between nervous system and immune response with specific focus on pain pathways is generating a huge interest in reference to AKI. The nervous system though static executes functions by nerve fibers throughout the body. Neuronal peptides released by nerves effect the immune response to mediate the hemodynamic system critical to the functioning of kidney. Pain is the outcome of cellular cross talk between nervous and immune systems. The widespread release of neuropeptides, neurotransmitters and immune cells contribute to bidirectional neuroimmune cross talks for pain manifestation. Recently, we have reported pain pathway genes that may pave the way to better understand such processes during AKI. An auxiliary understanding of the functions and communications in these systems will lead to novel approaches in pain management and treatment through the pathological state, specifically during acute kidney injury.

The Impact of Acute Kidney Injury in the Perioperative Period on the Incidence of Postoperative Delirium in Patients Undergoing Coronary Artery Bypass Grafting-Observational Cohort Study

Recent data indicate that acute kidney damage leads to inflammation in the brain and other distant organs. The purpose of this study was to investigate the effect of acute kidney injury (AKI) according to the Kidney Disease Improving Global Outcome (KDIGO) criteria on the occurrence of postoperative delirium in patients undergoing coronary artery bypass grafting (CABG). We performed a retrospective cohort analysis that included all consecutive patients undergoing elective CABG. The CAM-ICU (Confusion Assessment Method for Intensive Care Unit) was used for delirium assessment. Patients were divided into four groups, depending on the occurrence of AKI in the perioperative period according to KDIGO criteria. Overall, 902 patients were included in the final analysis, the mean age was 65.95 ± 8.01 years, and 76.83% were males (693/957). The majority of patients presented with normal kidney function-baseline creatinine level of 0.91 ± 0.21 (mg/dL). The incidence of AKI in the perioperative setting was 22.17% (200/902). Postoperative delirium was diagnosed in 115/902 patients (12.75%). Compared with no AKI, the odds of developing POD were increased for KDIGO stage 1 (OR 2.401 (95% confidence interval 1.484–3.884), p < 0.001); KDIGO stage 2 (OR 3.387 (95% confidence interval 1.459–7.866), p = 0.005); and highest for KDIGO stage 3 (OR equal to 9.729 (95% confidence interval 2.675–35.382), p = 0.001). Acute kidney injury, based on AKI staging, should be regarded as an independent risk factor for postoperative delirium after cardiac surgery.

The Long Noncoding RNA ANRIL Promotes Cell Apoptosis in Lipopolysaccharide-Induced Acute Kidney Injury Mediated by the TLR4/Nuclear Factor-Kappa B Pathway

BACKGROUND/AIMS

The purpose of this study is to analyze the expression and biological function of lncRNA ANRIL, microRNA-199a, TLR4, and nuclear factor-kappa B (NF-κB) in acute renal injury (AKI) induced by lipopolysaccharide (LPS).

METHODS

The levels of ANRIL and microRNA-199a in mouse cells and kidneys were detected by quantitative-polymerase chain reaction. Western blot analysis was used for the NF-κB pathway protein. MTT assay was used for cell viability. Enzyme-linked immunosorbent assay was used for the secretion of inflammatory factors in mouse kidney tissue. Apoptosis was measured by flow cytometry and Western blotting. The potential binding region between ANRIL and miR-199a was verified by luciferase reporter assay.

RESULTS

The upregulation of ANRIL can reduce the expression of microRNA-199a and increases the number of apoptotic cells. The expression levels of ANRIL in LPS-induced AKI mice and LPS-treated HK2 cells were upregulated compared with the control group. Overexpression of ANRIL increased apoptosis and promoted TLR4 (Toll-like receptor 4), NF-κB phosphorylation, and downstream transcription factor production.

CONCLUSION

ANRIL/NF-κB pathway in LPS-induced apoptosis provided theoretical guidance for ANRIL in the treatment of AKI.

Specific impact of past and new major cardiovascular events on acute kidney injury and end-stage renal disease risks in diabetes: a dynamic view

BACKGROUND

Interconnections between major cardiovascular events (MCVEs) and renal events are recognized in diabetes, however, the specific impact of atrial fibrillation (AF), heart failure (HF) and acute coronary syndrome (ACS) on the risk of end-stage renal disease (ESRD) on top of established renal risk factors is unclear in type 2 diabetes mellitus.

METHODS

We conducted a retrospective study in 861 consecutive patients followed in a nephrology setting during the 2000-13 period.

RESULTS

The mean age was 70 ± 10 years, 65.1% were men and the estimated glomerular filtration rate (eGFR) was 42.4 ± 21.0 mL/min/1.73 m2. During follow-up (median 59 months), 194 patients reached ESRD. A history of AF, HF or ACS was associated with an increased risk of reduced baseline eGFR. In turn, reduced baseline eGFR resulted in a greater risk of new MCVE (especially HF) during follow-up. Finally, all new MCVEs were risk factors for subsequent acute kidney injury (AKI) {HF: hazard ratio [HR] 8.99 [95% confidence interval (CI) 7.06-11.4]; AF: HR 5.42 (3.91-7.52); ACS: HR 8.82 (6.24-12.5); all P < 0.0001} and ESRD [HF: HR 5.52 (95% CI 4.01-7.60), P < 0.0001; AF: HR 3.48 (2.30-5.21), P < 0.0001; ACS: HR 2.31 (1.43-3.73), P = 0.0006]. The AF- and HF-associated risks of ESRD were significant after adjustments on all renal risks of ESRD (gender, blood pressure, eGFR, albuminuria, renin-angiotensin blockers, retinopathy and AKI), but the association was less strong for ACS. Importantly, no association was noted between other major events such as stroke or infections and the risk of ESRD.

CONCLUSIONS

Past and new cardiovascular events (more HF and AF than ACS) have a strong, independent impact on the development of ESRD above and beyond established risk factors in diabetes.

Acute Kidney Injury and Pediatric Bone Health

Acute kidney injury (AKI) has been associated with deleterious impacts on a variety of body systems. While AKI is often accompanied by dysregulation of mineral metabolism-including alterations in calcium, phosphate, vitamin D, parathyroid hormone, fibroblast growth factor 23, and klotho-its direct effects on the skeletal system of children and adolescents remain largely unexplored. In this review, the pathophysiology of dysregulated mineral metabolism in AKI and its potential effects on skeletal health are discussed, including data associating AKI with fracture risk.

Molecular nephrology: types of acute tubular injury

The acute loss of kidney function has been diagnosed for many decades using the serum concentration of creatinine - a muscle metabolite that is an insensitive and non-specific marker of kidney function, but is now used for the very definition of acute kidney injury (AKI). Fortunately, myriad new tools have now been developed to better understand the relationship between acute tubular injury and elevation in serum creatinine (SCr). These tools include unbiased gene and protein expression analyses in kidney, urine and blood, the localization of specific gene transcripts in pathological biopsy samples by rapid in-situ RNA technology and single-cell RNA-sequencing analyses. However, this molecular approach to AKI has produced a series of unexpected problems, because the expression of specific kidney-derived molecules that are indicative of injury often do not correlate with SCr levels. This discrepancy between kidney injury markers and SCr level can be reconciled by the recognition that many separate subtypes of AKI exist, each with distinct patterning of molecular markers of tubular injury and SCr data. In this Review, we describe the weaknesses of isolated SCr-based diagnoses, the clinical and molecular subtyping of acute tubular injury, and the role of non-invasive biomarkers in clinical phenotyping. We propose a conceptual model that synthesizes molecular and physiological data along a time course spanning from acute cellular injury to organ failure.

Postdischarge Major Adverse Cardiovascular Events of ICU Survivors Who Received Acute Renal Replacement Therapy

OBJECTIVES

Long-term risk of a major adverse cardiovascular events in ICU survivors who underwent acute renal replacement therapy requires further investigation.

DESIGN

Nationwide population-based study using the claims database of Korea.

SETTING

Index admission cases of ICU survivors in government-designated tertiary hospitals PATIENTS:: The study group consisted of ICU survivors who underwent acute renal replacement therapy, and the control group consisted of those without acute renal replacement therapy. Patients were excluded if they 1) were under age 20, 2) expired within 30 days after discharge, 3) received ICU care for less than 24 hours, 4) had a previous ICU admission, 5) had a history of major adverse cardiovascular event, or 6) had a major adverse cardiovascular event-related cardio/cerebrovascular diseases. The outcomes of the patients who received continuous renal replacement therapy were compared with those of patients who received only intermittent renal replacement therapy.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Information regarding patient characteristics and treatment modalities was collected and adjusted. The main outcome was major adverse cardiovascular event, including acute myocardial infarction, revascularization, and acute ischemic stroke. Patient mortality and progression to end-stage renal disease were also evaluated. We included 12,380 acute renal replacement therapy patients and 382,018 patients in the control group. Among the study group, 6,891 patients were included in the continuous renal replacement therapy group, and 5,034 in the intermittent renal replacement therapy group. The risks of major adverse cardiovascular event (adjusted hazard ratio, 1.463 [1.323-1.619]; p < 0.001), all-cause mortality (adjusted hazard ratio, 1.323 [1.256-1.393]; p < 0.001), and end-stage renal disease (adjusted hazard ratio, 18.110 [15.779-20.786]; p < 0.001) were higher in the acute renal replacement therapy patients than the control group. When we compared the continuous renal replacement therapy patients with the intermittent renal replacement therapy patients, the risk of major adverse cardiovascular event was comparable (adjusted hazard ratio, 1.049 [0.888-1.239]; p = 0.575).

CONCLUSIONS

Clinicians should note the increased risk of a long-term major adverse cardiovascular event in acute renal replacement therapy patients and consider appropriate risk factor management. Significant difference in the risk of postdischarge major adverse cardiovascular event was not identified between continuous renal replacement therapy and intermittent renal replacement therapy.

Renal Inflammation and Fibrosis: A Double-edged Sword

Renal tissue injury initiates inflammatory and fibrotic processes that occur to promote regeneration and repair. After renal injury, damaged tissue releases cytokines and chemokines, which stimulate activation and infiltration of inflammatory cells to the kidney. Normal tissue repair processes occur simultaneously with activation of myofibroblasts, collagen deposition, and wound healing responses; however, prolonged activation of pro-inflammatory and pro-fibrotic cell types causes excess extracellular matrix deposition. This review focuses on the physiological and pathophysiological roles of specialized cell types, cytokines/chemokines, and growth factors, and their implications in recovery or exacerbation of acute kidney injury.

Effects of Justicia acuminatissima, or Amazonian Sara Tudo, on ischemic acute kidney injury: an experimental study

OBJECTIVE

To evaluate the effects of Justicia acuminatissima , or Amazonian Sara Tudo , on renal hemodynamics, oxidative profile, and renal histology in rats with ischemic acute kidney injury.

METHOD

Preclinical assay with adult male Wistar rats, weighing from 250 g to 350 g, distributed into Sham, ischemia, and ischemia + Sara Tudo groups. Hemodynamic parameters, renal function, oxidative stress, and renal histology were evaluated.

RESULTS

Pretreatment with Sara Tudo reduced the functional injury, which was shown by the increase in creatinine clearance and thiols; reduction of oxidative markers, renal vascular resistance, and tubulointerstitial injury in the renal tissue; and the significant improvement in renal blood flow.

CONCLUSION

The renoprotection provided by Justicia acuminatissima , or Sara Tudo , in cases of ischemic acute kidney injury was characterized by a marked improvement in renal function, reducing the oxidative injury, and impacting on renal histology positively.

Endothelial glycocalyx-the battleground for complications of sepsis and kidney injury

After briefly discussing endothelial glycocalyx and its role in vascular physiology and renal disease, this overview focuses on its degradation very early in the course of microbial sepsis. We describe our recently proposed mechanism for glycocalyx degradation induced by exocytosis of lysosome-related organelles and release of their cargo. Notably, an intermediate in nitric oxide synthesis, NG-hydroxy-l-arginine, shows efficacy in curtailing exocytosis of these organelles and improvement in animal survival. These data not only depict a novel mechanism responsible for very early glycocalyx degradation, but may also outline a potential preventive therapy. The second issue discussed in this article is related to the therapeutic acceleration of restoration of already degraded endothelial glycocalyx. Here, using as an example our recent findings obtained with sulodexide, we illustrate the importance of the expedited repair of degraded endothelial glycocalyx for the survival of animals with severe sepsis. These two focal points of the review on glycocalyx may not only have broader disease applicability, but they may also provide additional evidence to buttress the idea of the importance of endothelial glycocalyx and its maintenance and repair in the prevention and treatment of an array of renal and nonrenal diseases.

Antithrombin III Attenuates AKI Following Acute Severe Pancreatitis

BACKGROUND

Antithrombin III (ATIII), the predominant coagulation factor inhibitor, possesses anti-inflammatory properties and exerts renoprotective effects on renal ischemia-reperfusion injury in animal models. However, the ATIII's protective effects of ATIII on acute kidney injury (AKI) following severe acute pancreatitis (SAP) need to be confirmed.

METHODS

We assessed the association between ATIII activities and the incidence of AKI in patients with SAP, and explored therapeutic effects and potential mechanisms of ATIII on kidney injury in sodium taurocholate induced SAP rat model. Rats were intravenously injected with ATIII (500 μg/kg) before or after the induction of SAP.

RESULTS

The results demonstrated ATIII did not attenuate pancreatic injury, but significantly ameliorate renal dysfunction and renal histological injury. ATIII administration alleviated renal inflammation response, oxidative stress, and cell apoptosis. Moreover, ATIII attenuated tumor necrosis factor α (TNFα)-stimulated intercellular cell adhesion molecule 1(ICAM-1) and monocyte chemotactic protein 1 (MCP-1) upregulation in cultured renal tubular epithelial cells.

CONCLUSION

ATIII appears to ameliorate SAP-induced kidney injury by inhibiting inflammation, oxidative stress, and apoptosis. ATIII supplementation may have a potential prophylactic and therapeutic effect on SAP induced AKI.

Acute kidney injury and disease: Long-term consequences and management

With increasing longevity and the presence of multiple comorbidities, a significant proportion of hospitalized patients, and an even larger population in the community, is at increased risk of developing an episode of acute kidney injury (AKI). Because of improvements in short-term outcomes following an episode of AKI, survivors of an episode of AKI are now predisposed to develop its long-term sequel. The identification of risk for progression to chronic kidney disease (CKD) is complicated by the absence of good biomarkers that identify this risk and the variability of risk associated with clinical factors including, but not limited to, the number of AKI episodes, severity, duration of previous AKI and pre-existing CKD that has made the prediction for long-term outcomes in survivors of AKI more difficult. Being a significant contributor to the growing incidence of CKD, there is a need to implement measures to prevent AKI in both the community and hospital settings, target interventions to treat AKI that are also associated with better long-term outcomes, accurately identify patients at risk of adverse consequences following an episode of AKI and institute therapeutic strategies to improve these long-term outcomes. We discuss the lasting renal and non-renal consequences following an episode of AKI, available biomarkers and non-invasive testing to identify ongoing intra-renal pathology and review the currently available and future treatment strategies to help reduce these adverse long-term outcomes.

The Effect of Overexpression of the Enhancer of Zeste Homolog 1 (EZH1) Gene on Aristolochic Acid-Induced Injury in HK-2 Human Kidney Proximal Tubule Cells In Vitro

Background

Acute kidney injury (AKI) involves the renal tubular epithelium. The enhancer of zeste homolog 1 (EZH1) gene has a role in cell development and differentiation. This study aimed to investigate the effect of overexpression of the EZH1 gene on aristolochic acid-induced injury in HK-2 human kidney proximal tubule epithelial cells in vitro.

Material/Methods

The HK-2 cells were cultured and treated with aristolochic acid and the effects of aristolochic acid-injury were evaluated using a cell counting kit-8 (CCK-8) assay. Overexpression of EZH1 used gene plasmid transfection into HK-2 cells. The cell apoptosis rate and levels of intracellular reactive oxygen species (ROS) were measured using flow cytometry. Quantitative real-time polymerase chain reaction (qRT-PCR) and Western blot were performed to determine the expressions of inflammatory cytokines including interleukin (IL)-1β, IL-6, tumor necrosis factor-α (TNF-α), apoptosis-related genes, and the downstream target genes of NF-κB signaling pathway, including NFKBIA, CXCL8, and cyclin D1.

Results

Aristolochic acid inhibited HK-2 cell viability, induced cell apoptosis, increased the levels of ROS and inflammatory cytokines, including IL-1β, IL-6, TNF-α, and activated the NF-κB pathway. Overexpression the EZH1 gene inhibited HK-2 cell apoptosis, reduced ROS levels, and down-regulated the expressions of IL-1β, IL-6, TNF-α, Bax and Cyt C mRNA and protein, and increased the expressions of Bcl-2 and NFKBIA, CXCL8 and cyclin D1, indicating that overexpression of EZH1 suppressed NF-κB signaling in aristolochic acid-injured HK-2 cells.

Conclusions

Overexpression of EZH1 reduced HK-2 cell injury induced by aristolochic acid in vitro by inhibition of NF-κB signaling.

Brain consequences of acute kidney injury: Focusing on the hippocampus

The high mortality rates associated with acute kidney injury are mainly due to extra-renal complications that occur following distant-organ involvement. Damage to these organs, which is commonly referred to as multiple organ dysfunction syndrome, has more severe and persistent effects. The brain and its sub-structures, such as the hippocampus, are vulnerable organs that can be adversely affected. Acute kidney injury may be associated with numerous brain and hippocampal complications, as it may alter the permeability of the blood-brain barrier. Although the pathogenesis of acute uremic encephalopathy is poorly understood, some of the underlying mechanisms that may contribute to hippocampal involvement include the release of multiple inflammatory mediators that coincide with hippocampus inflammation and cytotoxicity, neurotransmitter derangement, transcriptional dysregulation, and changes in the expression of apoptotic genes. Impairment of brain function, especially of a structure that has vital activity in learning and memory and is very sensitive to renal ischemic injury, can ultimately lead to cognitive and functional complications in patients with acute kidney injury. The objective of this review was to assess these complications in the brain following acute kidney injury, with a focus on the hippocampus as a critical region for learning and memory.

Antithrombotic properties of hemofilter coated with polymer having a hydrophilic blood-contacting layer

OBJECTIVE:

Extracorporeal circulation devices are coated with a biocompatible polymer coating agent (BPCA) that has a hydrophilic blood-contacting layer, but hemofilters are not. We aimed to investigate the antithrombotic properties of a BPCA-coated hemofilter.

METHODS:

Four experiments using BPCA-coated circuits and non-coated hemofilters and four experiments using BPCA-coated circuits and BPCA-coated hemofilters were performed with whole human blood and compared by measuring the circuit pressure every 5 min, antithrombin activity every 40 min, and thrombin-antithrombin complex every 40 min, for a total of 240 min of recirculation.

RESULTS:

The mean time required for the pressure at the inlet of the hemofilter to increase sharply was longer in BPCA-coated than in non-coated hemofilters (66 ± 11 min vs 25 ± 9 min, p < 0.01). The mean antithrombin activity value at 200 and 240 min of recirculation was significantly higher in the experiments with BPCA-coated versus non-coated hemofilters (43.3 ± 2.87 vs 33.3 ± 5.74, p = 0.04; 42.8 ± 3.59 vs 31.0 ± 5.35, p = 0.01, respectively); the antithrombin activity values at the other time points were not significantly different. Furthermore, all thrombin-antithrombin complex values in experiments with the BPCA-coated hemofilters achieved overrange at 80 min of recirculation, whereas those with the non-coated hemofilter achieved overrange at 40 min.

CONCLUSION:

This study suggests that BPCA-coated hemofilters can inhibit antithrombin consumption, contributing to antithrombotic effects in extracorporeal circulation circuits.

miR-214 ameliorates acute kidney injury via targeting DKK3 and activating of Wnt/β-catenin signaling pathway

Background

miR-214 was demonstrated to be upregulated in models of renal disease and promoted fibrosis in renal injury independent of TGF-β signaling in vivo. However, the detailed role of miR-214 in acute kidney injury (AKI) and its underlying mechanism are still largely unknown.

Methods

In this study, an I/R-induced rat AKI model and a hypoxia-induced NRK-52E cell model were used to study AKI. The concentrations of kidney injury markers serum creatinine, blood urea nitrogen, and kidney injury molecule-1 were measured. The expressions of miR-214, tumor necrosis factor-α, interleukin (IL)-1β, IL-6, were detected by RT-qPCR. The protein levels of Bcl-2, Bax, Dickkopf-related protein 3, β-catenin, c-myc, and cyclinD1 were determined by western blot. Cell apoptosis and caspase 3 activity were evaluated by flow cytometry analysis and caspase 3 activity assay, respectively. Luciferase reporter assay was used to confirm the interaction between miR-214 and Dkk3.

Results

miR-214 expression was induced in ischemia–reperfusion (I/R)-induced AKI rat and hypoxic incubation of NRK-52E cells. Overexpression of miR-214 alleviated hypoxia-induced NRK-52E cell apoptosis while inhibition of miR-214 expression exerted the opposite effect. Dkk3 was identified as a target of miR-214. Anti-miR-214 abolished the inhibitory effects of DKK3 knockdown on hypoxia-induced NRK-52E cell apoptosis by inactivation of Wnt/β-catenin signaling. Moreover, miR-214 ameliorated AKI in vivo by inhibiting apoptosis and fibrosis through targeting Dkk3 and activating Wnt/β-catenin pathway.

Conclusion

miR-214 ameliorates AKI by inhibiting apoptosis through targeting Dkk3 and activating Wnt/β-catenin signaling pathway, offering the possibility of miR-214 in the therapy of ischemic AKI.

Electronic supplementary material

The online version of this article (10.1186/s40659-018-0179-2) contains supplementary material, which is available to authorized users.

Long-term consequences of acute kidney injury in the perioperative setting

PURPOSE OF REVIEW

Recent studies indicate that acute kidney injury (AKI) and chronic kidney disease (CKD) are interconnected syndromes. Although the majority of patients who suffer an episode of AKI will recover laboratory indices suggesting complete or near complete recovery of renal function, a significant portion of post-AKI survivors will develop major kidney events, including development of late-stage CKD, need for renal replacement therapies, and death.

RECENT FINDINGS

Our review highlights epidemiology of adverse post-AKI events, association of AKI with late development of nonrenal adverse outcomes, use of bedside equations that facilitate prognostication of adverse renal outcomes of AKI, and how variability in serum creatinine values in individual patients, even among those with normal baseline renal function may indicate risk for the development of CKD. Use of common laboratory parameters such as serum creatinine and albumin, along with certain clinical and demographic markers, individualize patients at high risk of complications and in need of close postdischarge follow-up. Evidence that 'organ crosstalk' following a major AKI episode may increase the risk of heart failure, stroke, and hypertension, places its survivors in a special patient category deserving active efforts to minimize risk for cardiovascular events.

SUMMARY

AKI is a major cause for acute in-hospital mortality and development of both late-stage CKD and cardiovascular events. Perioperative care to prevent AKI must challenge the notion that a single normal point of contact serum creatinine value substantially reduces the likelihood of its occurrence.

Assessing the influence of acute kidney injury on the mortality in patients with acute myocardial infarction: a clinical trail

Objectives: Acute kidney injury (AKI) increases the risk of death following acute myocardial infarction (AMI). In this current study, we tried to understand the role of newly KDIGO defined AKI in AMI-induced early and late mortality.

Methods: We retrospectively analyzed the clinical data of AMI patients (totaling 1371 cases) from the hospital’s computer database. And AKI was defined based on the KDIGO criteria but GFR or urinary output assessment was not used. Subsequently, we compared the association of AKI with 30-day and 30-day to 5-year all-cause mortality, using multivariate COX regression analysis with two models.

Results: We observed the development of AKI in 410 (29.9%) patients during the hospital stay. The 30-day and 30-day to 5-year mortality rates were 5.6% and 11.3%, respectively, in 1371 AMI patients. Further, adjusted Cox regression analysis based on model 1 revealed that AKI severity was an independent risk factor of 30-day mortality, while AKI Stage 3 was an independent predictor of 30-day to 5-year mortality. Adjusted Cox regression analysis based on model 2 revealed that normal baseline renal function with AKI and impaired renal function with AKI were independent risk factors of 30-day mortality, while normal baseline renal function with AKI and impaired renal function with AKI were identified to be independent predictors of 30-day to 5-year mortality.

Conclusions: Whether the baseline renal function decreased or not, AKI strongly correlated with short- and long-term all-cause mortality in patients with AMI. Specifically, the short-term mortality of AMI patients increased with more severe AKI.

Inhibition of semaphorin-3a suppresses lipopolysaccharide-induced acute kidney injury

Semaphorin-3a (Sema3A), a soluble axon guidance cue, appears to play an important role in the development of acute kidney injury (AKI) and has been regarded as an early diagnostic marker to evaluate the progression of AKI. However, the role of Sema3A in sepsis-associated AKI remains unknown. In this study, lipopolysaccharide (LPS) was used to simulate sepsis-associated AKI and the role of Sema3A in LPS-induced AKI was investigated in vivo and in vitro. In our in vivo study, Sema3A was found in tubular epithelial cells (TECs), which presented a higher level after LPS treatment. Meanwhile, the results of our in vitro experiment showed that Sema3A was also elevated in NRK-52E cells treated by LPS. Notably, inhibition of Sema3A by (-)-epigallocatechin-3-gallate (EGCG) could significantly reduce kidney inflammation and apoptosis in mice. Likewise, EGCG intervention also ameliorated the inflammation and apoptosis of cells in vitro. Furthermore, our research also found that the Rac1/NF-κB p65 and JNK pathways were possibly involved in the Sema3A-mediated inflammation and apoptosis of TECs, respectively. Our findings suggest that Sema3A play a pathogenic role by promoting inflammation and apoptosis of TECs in LPS-induced AKI. It might serve as a useful treatment target in ameliorating sepsis-associated AKI. KEY MESSAGES: Sema3A is upregulated in LPS-induced AKI. Inhibition of Sema3A attenuates inflammation and apoptosis of TECs in LPS-induced AKI. Sema3A enhances the LPS-induced inflammation of TECs through the Rac1/NF-κB p65 pathway. Sema3A exacerbates the LPS-induced apoptosis of TECs through the JNK pathway.

miR-182 enhances acute kidney injury by promoting apoptosis involving the targeting and regulation of TCF7L2/Wnt/β-catenins pathway

Acute kidney injury (AKI) is a sudden decay in renal function leading to increasing morbidity and mortality. miR-182 has been reported to be actively involved in kidney diseases. However, the function and molecular mechanism of miR-182 in AKI still need to be elucidated. The levels of serum creatinine (SCr), blood urea nitrogen (BUN), and urine Kim-1 in I/R-induced rat AKI model were detected by a Beckman Autoanalyzer. miR-182 and transcription factor 7-like-2 (TCF7L2) mRNA expression were measured by qRT-PCR. Flow cytometry and caspase-3 colorimetry analysis were performed to determine NRK-52E cell apoptosis. Bioinformatics and dual-luciferase reporter were used to identify the interaction between miR-182 and TCF7L2. miR-182 expression was increased in both I/R-induced rat models and hypoxia-treated NRK-52E cells, and miR-182 overexpression stimulated the apoptosis of hypoxia-induced NRK-52E cells. Dual-luciferase analysis disclosed that TCF7L2 was a target of miR-182. TCF7L2 suppressed hypoxia-induced apoptosis in NRK-52E cells, and the inhibitory effect of TCF7L2 on cell apoptosis could be reversed with miR-182 restoration. Moreover, the activity of Wnt/β-catenin signaling pathway was promoted following overexpression of TCF7L2 in NRK-52E cells with hypoxia treatment, and this effect was greatly attenuated by the increased miR-182 expression. Finally, in vivo experiment also validated the alleviation of miR-182 inhibitor on I/R-induced kidney injury and apoptosis via regulating TCF7L2/ Wnt/β-catenin pathway. miR-182 exacerbated AKI involving the targeting and regulation of TCF7L2/Wnt/β-catenin signaling, unveiling a novel regulatory pathway in ischemia-reperfusion injury and elucidating a potential biomarker for AKI treatment.

Acute Kidney Injury as a Condition of Renal Senescence

Acute kidney injury (AKI), characterized by a sharp drop in glomerular filtration, continues to be a significant health burden because it is associated with high initial mortality, morbidity, and substantial health-care costs. There is a strong connection between AKI and mechanisms of senescence activation. After ischemic or nephrotoxic insults, a wide range of pathophysiological events occur. Renal tubular cell injury is characterized by cell membrane damage, cytoskeleton disruption, and DNA degradation, leading to tubular cell death by necrosis and apoptosis. The senescence mechanism involves interstitial fibrosis, tubular atrophy, and capillary rarefaction, all of which impede the morphological and functional recovery of the kidneys, suggesting a strong link between AKI and the progression of chronic kidney disease. During abnormal kidney repair, tubular epithelial cells can assume a senescence-like phenotype. Cellular senescence can occur as a result of cell cycle arrest due to increased expression of cyclin kinase inhibitors (mainly p21), downregulation of Klotho expression, and telomere shortening. In AKI, cellular senescence is aggravated by other factors including oxidative stress and autophagy. Given this scenario, the main question is whether AKI can be repaired and how to avoid the senescence process. Stem cells might constitute a new therapeutic approach. Mesenchymal stem cells (MSCs) can ameliorate kidney injury through angiogenesis, immunomodulation, and fibrosis pathway blockade, as well as through antiapoptotic and promitotic processes. Young umbilical cord–derived MSCs are better at increasing Klotho levels, and thus protecting tissues from senescence, than are adipose-derived MSCs. Umbilical cord–derived MSCs improve glomerular filtration and tubular function to a greater degree than do those obtained from adult tissue. Although senescence-related proteins and microRNA are upregulated in AKI, they can be downregulated by treatment with umbilical cord–derived MSCs. In summary, stem cells derived from young tissues, such as umbilical cord–derived MSCs, could slow the post-AKI senescence process.

Biomarkers of AKI Progression after Pediatric Cardiac Surgery

Background As children progress to higher stages of AKI, the risk for adverse outcomes dramatically increases. No reliable methods exist to predict AKI progression in hospitalized children. To determine if biomarkers of inflammation and kidney injury can predict AKI progression, we conducted a three-center prospective cohort study of children undergoing cardiopulmonary bypass.Methods On the first day of serum creatinine-defined AKI, we measured urine biomarkers (neutrophil gelatinase-associated lipocalin [NGAL], IL-18, kidney injury molecule 1, liver fatty acid binding protein [L-FABP], albumin, and cystatin C) and plasma biomarkers (IFN, IL-1, IL-2, IL-4, IL-6, IL-8, IL-10, IL-12, IL-13, TNF-α, NGAL, and cystatin C). We defined AKI progression as a worsening of AKI stage or persisting stage 3 AKI (≥2 consecutive days).Results In all, 176 of 408 (43%) children developed postoperative AKI. Among the children with AKI, we diagnosed stages 1, 2, and 3 AKI in 145 (82.5%), 25 (14%), and six (3.5%) children, respectively, on the first day of AKI; 28 (7%) children had AKI progression. On the first day of AKI, nine of 17 biomarkers were significantly higher in patients with than without AKI progression. Urine L-FABP (among injury biomarkers) and plasma IL-8 (among inflammatory biomarkers) had the highest discrimination for AKI progression: optimism-corrected area under the curve, 0.70; 95% confidence interval, 0.58 to 0.81 and optimism-corrected area under the curve, 0.80; 95% confidence interval, 0.69 to 0.91, respectively.Conclusions If validated in additional cohorts, plasma IL-8 could be used to improve clinical care and guide enrollment in therapeutic trials of AKI.

HMGB1 redox during sepsis

During sepsis, the alarmin HMGB1 is released from tissues and promotes systemic inflammation that results in multi-organ damage, with the kidney particularly susceptible to injury. The severity of inflammation and pro-damage signaling mediated by HMGB1 appears to be dependent on the alarmin's redox state. Therefore, we examined HMGB1 redox in kidney cells during sepsis. Using intravital microscopy, CellROX labeling of kidneys in live mice indicated increased ROS generation in the kidney perivascular endothelium and tubules during lipopolysaccharide (LPS)-induced sepsis. Subsequent CellROX and MitoSOX labeling of LPS-stressed endothelial and kidney proximal tubule cells demonstrated increased ROS generation in these cells as sepsis worsens. Consequently, HMGB1 oxidation increased in the cytoplasm of kidney cells during its translocation from the nucleus to the circulation, with the degree of oxidation dependent on the severity of sepsis, as measured in in vivo mouse samples using a thiol assay and mass spectrometry (LC-MS/MS). The greater the oxidation of HMGB1, the greater the ability of the alarmin to stimulate pro-inflammatory cyto-/chemokine release (measured by Luminex Multiplex) and alter mitochondrial ATP generation (Luminescent ATP Detection Assay). Administration of glutathione and thioredoxin inhibitors to cell cultures enhanced HMGB1 oxidation during sepsis in endothelial and proximal tubule cells, respectively. In conclusion, as sepsis worsens, ROS generation and HMGB1 oxidation increases in kidney cells, which enhances HMGB1's pro-inflammatory signaling. Conversely, the glutathione and thioredoxin systems work to maintain the protein in its reduced state.

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Endotoxins (LPS) increase cellular oxidative stress during sepsis.

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During its translocation, HMGB1 gets oxidized in the cytoplasm.

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Thioredoxin and glutathione keep HMGB1 in a reduced redox state during sepsis.

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HMGB1 oxidation enhances its stimulation of inflammatory cyto-/chemokine release.

Therapeutic Restoration of Endothelial Glycocalyx in Sepsis

Endothelial glycocalyx (EG) is disintegrated during sepsis. We have previously shown that this occurs very early in the course of sepsis and its prevention improves the survival of mice with sepsis. Here, we sought to investigate the possibility of pharmacologically accelerating the restoration of disintegrated EG in sepsis. We used a soilage injection model to induce polymicrobial sepsis in C57/BL6 mice and measured total body EG. En face aortic preparations were used for staining of markers of EG and atomic force microscopy was used to measure EG in vitro. In vitro studies were conducted in cultured endothelial cells either exposed to a lipopolysaccharide or enzymatically denuded of EG. Sulodexide (SDX), a heparin sulfate-like compound resistant to degradation by heparanase, accelerated EG regeneration in vitro and in vivo. The total volume of EG was drastically reduced in septic mice. Administration of SDX produced a dramatic acceleration of EG restoration. This effect, unrelated to any SDX-induced differences in microbial burden, was associated with better control of vascular permeability. Notably, SDX demonstrated not only a remarkable capacity for EG regeneration in vitro and in vivo but was also associated with improved animal survival, even when instituted 2 hours after induction of severe sepsis. In conclusion, 1) EG is disintegrated in sepsis, the event which contributes to high animal mortality; 2) pharmacologic acceleration of EG restoration can be achieved using SDX; and 3) SDX reduces vascular permeability, which is elevated in septic mice, and improves animal survival.

Acute kidney injury increases the risk of end-stage renal disease after cardiac surgery in an Asian population: a prospective cohort study

BACKGROUND

Acute kidney injury (AKI) after cardiac surgery is associated with increased morbidity and mortality. The long-term association between AKI and end-stage renal disease (ESRD) in an Asian population is unknown. Given the high prevalence of diabetes and a younger age of presentation for cardiac surgery, it is important to track this progression of kidney disease. Therefore, we studied the long-term risk of ESRD and mortality in our Asian patients who developed AKI after cardiac surgery.

METHODS

With ethics approval, we prospectively recruited 3008 patients who underwent cardiac surgery in Singapore between 2008 and 2012, and followed them up till 2014. ESRD and mortality information were obtained from the Singapore Renal Registry and Singapore Registry of Births and Deaths respectively. AKI was defined using the Acute Kidney Injury Network (AKIN) criteria, and ESRD was defined as stage 5 chronic kidney disease requiring renal replacement therapy. The Cox proportional hazards regression model was used to analyze associations between AKI and the primary outcome of ESRD and the secondary outcome of death.

RESULTS

The AKI incidence was 29.1%. During a mean follow-up of 4.4 ± 2.8 years, 0.9% developed ESRD. The hazard ratio (HR) for developing ESRD was 4.7 (95% C.I. = 1.736-12.603, p = 0.002) for AKIN stage 1 patients, and 5.8 (95% C.I. = 1.769-18.732, p = 0.004) for AKIN stage 2 and 3 patients; while the HR for mortality was 1.7 (95% C.I. = 1.165-2.571, p = 0.007) for AKIN stage 1 patients, and 2.5 (95% C.I. = 1.438-4.229, p < 0.001) for AKIN stage 2 and 3 patients.

CONCLUSIONS

AKI is associated with ESRD and mortality after cardiac surgery in our Asian population. The trajectory from AKI to ESRD is rapid within 5 years of cardiac surgery. A concerted periodic follow-up assessment is advocated for AKI patients post-cardiac surgery.

The glycocalyx and its significance in human medicine

Cells are covered by a surface layer of glycans that is referred to as the 'glycocalyx'. In this review, we focus on the role of the glycocalyx in vascular diseases (atherosclerosis, stroke, hypertension, kidney disease and sepsis) and cancer. The glycocalyx and its principal glycosaminoglycans [heparan sulphate (HS) and hyaluronic acid (HA)] and core proteins (syndecans and glypicans) are degraded in vascular diseases, leading to a breakdown of the vascular permeability barrier, enhanced access of leucocytes to the arterial intima that propagate inflammation and alteration of endothelial mechanotransduction mechanisms that protect against disease. By contrast, the glycocalyx on cancer cells is generally robust, promoting integrin clustering and growth factor signalling, and mechanotransduction of interstitial flow shear stress that is elevated in tumours to upregulate matrix metalloproteinase release which enhances cell motility and metastasis. HS and HA are consistently elevated on cancer cells and are associated with tumour growth and metastasis. Later, we will review the agents that might be used to enhance or protect the glycocalyx to combat vascular disease, as well as a different set of compounds that can degrade the cancer cell glycocalyx to suppress cell growth and metastasis. It is clear that what is beneficial for either vascular disease or cancer will not be so for the other. The overarching conclusions are that (i) the importance of the glycocalyx in human medicine is only beginning to be recognized, and (ii) more detailed studies of glycocalyx involvement in vascular diseases and cancer will lead to novel treatment modalities.

The Role of Activin A and B and the Benefit of Follistatin Treatment in Renal Ischemia-Reperfusion Injury in Mice

Background

Activins, members of the TGF-β superfamily, are key drivers of inflammation and are thought to play a significant role in ischemia-reperfusion injury (IRI), a process inherent to renal transplantation that negatively impacts early and late allograft function. Follistatin (FS) is a protein that binds activin and inhibits its activity. This study examined the response of activin A and B in mice after renal IRI and the effect of exogenous FS in modulating the severity of renal injury.

Methods

Mice were treated with recombinant FS288 or vehicle before renal IRI surgery. Activin A, B, and FS levels in the serum and kidney, and renal injury parameters were measured at 3, 6, and 24 hours after reperfusion.

Results

Serum and kidney activin B levels were increased within 6 hours postrenal IRI, accompanied by renal injury—increased serum creatinine, messenger (m)RNA expression of kidney injury molecule-1 (KIM-1) and neutrophil gelatinase-associated lipocalin (NGAL); endothelial activation—increased E-selectin mRNA; and systemic inflammation—increased serum levels of IL-6, monocyte chemotactic protein-1 and TNF-α. Further injury was potentiated by an upsurge in activin A by 24 hours, with further increases in serum creatinine, KIM-1 and NGAL mRNA expression. Follistatin treatment significantly reduced the level of serum activin B and subsequently blunted the increase in activin A. Renoprotection was evident with the attenuated rise in serum creatinine, KIM-1 and NGAL expression, tubular injury score, renal cell apoptosis, and serum IL-6 and monocyte chemotactic protein-1 levels.

Conclusions

We propose that activin B initiates and activin A potentiates renal injury after IRI. Follistatin treatment, through binding and neutralizing the actions of activin B and subsequently activin A, reduced renal IRI by minimizing endothelial cell activation and dampening the systemic inflammatory response. These data support the potential clinical application of FS treatment to limit IRI during renal transplantation.