Pathophysiology of acute kidney injury

The critical role of ion channels in kidney disease: perspective from AKI and CKD

Ion channels, particularly those in the transient receptor potential (TRP) family, play key roles in cellular stress responses like inflammation and apoptosis, significantly impacting renal disease progression. Some channels such as TRPV1, TRPM2, TRPC6 impact renal pathology by mediating detrimental calcium influx, exacerbating oxidative stress, and promoting inflammatory pathways. Their activities are especially pronounced in conditions like ischemia and nephrotoxicity, common in acute kidney injury, and persist into chronic kidney injury, influencing fibrosis and nephron loss. Additionally, potassium and sodium channels like Kir4.1, KATP, and ENaC play critical roles in maintaining electrolyte balance and cellular energy under stress conditions. Further exploration of ion channel functionality and regulation is necessary to clarify their roles in renal disease. This review summarizes the involvement of ion channels in AKI and CKD and examines their potential clinical value in diagnosing and treating kidney disease.

Altered renal vascular patterning reduces ischemic kidney injury and limits age-associated vascular loss

The kidney vasculature has a complex arrangement, which runs in both series and parallel to perfuse the renal tissue and appropriately filter plasma. Recent studies have demonstrated that the development of this vascular pattern is dependent on netrin-1 secreted by renal stromal progenitors. Mice lacking netrin-1 (Ntn1) from these cells develop an arterial tree with stochastic branching, particularly of the large interlobar vessels. The current study investigated whether abnormalities in renal vascular patterning altered kidney function or response to injury. To examine this, we analyzed kidney function at baseline as well as in response to a model of bilateral ischemic injury and measured vascular dynamics in 7- to 8-mo-old mice. We found no differences in kidney function or morphology at baseline between mice with an abnormal arterial pattern compared with control. Interestingly, male and female mutant mice with stochastic vascular patterning showed a reduction in tubular injury in response to ischemia. Similarly, mutant mice also had a preservation of perfused vasculature with increased age compared with a reduction in the control group. These results suggest that guided and organized patterning of the renal vasculature may not be required for normal kidney function, but uncovers new implications for patterning in response to injury. Understanding how patterning and maturation of the arterial tree affects physiology and response to injury has important implications for enhancing kidney regeneration and tissue engineering strategies.NEW & NOTEWORTHY Kidney vascular patterning is established through responses to guidance cues such as netrin-1; however, the significance of proper patterning to function and injury response remains unexplored. Here, utilizing a conditional knockout of netrin-1 (Ntn1) that displays persistent abnormal arterial patterning, we identify no significant disruptions to normal kidney physiology in adult animals but, surprisingly, less tubular damage in response to ischemic injury. This study uncovers new and significant implications for proper kidney vascular patterning.

Renal artery occlusion in a young woman - a tale of mysterious thrombosis

BackgroundRenal artery thrombosis is rare and limited reports exist in the young population. The most common aetiology is thromboembolic disease or abdominal trauma in this population and isolated occurrences are extremely rare. We present the case of an 18-year-old woman with spontaneous unilateral renal artery thrombosis and infarction for whom reperfusion was achieved through endovascular intervention. The aetiology of her thrombosis remains unclear and is under investigation with differential diagnoses being fibromuscular dysplasia, large and medium vessel vasculitis, and thromboembolic causes.ObjectiveTo demonstrate the value in attempting salvage of an ischaemic kidney in a young patient with an unexplained spontaneous renal thrombosis.MethodJM is an 18-year-old woman who presented to a large regional tertiary hospital with 3 days of right flank pain. She had no infective symptoms and no urinary or bowel changes before admission. She was not pregnant, and her only medication was the oral contraceptive pill commenced 3 months prior. A CT angiogram demonstrated right renal artery thrombosis with renal infarction. The kidney was deemed potentially salvageable, and ultrasound defined adequate vessel calibre to access for thrombectomy in the context of a negative coagulopathy screen.ResultsThe patient underwent thrombolysis, thrombectomy and balloon angioplasty. Intraoperatively, a thin segment of distal stenosis was identified, and angiogram reperfusion was achieved with subsequent improvement in renal function.ConclusionRenal artery thrombosis in young people is extremely rare and presents a diagnostic and management challenge requiring input from multiple teams including nephrology, rheumatology, paediatrics and vascular surgery. Systemic coagulopathy and vasculitis are differentials against anatomical aetiologies such as fibromuscular dysplasia. Our case adds to the limited literature regarding this in the young population. Renal artery thrombosis with occlusion in young people is very rare and is most often associated with a systemic coagulopathic disorder, such as antiphospholipid syndrome or structural pathology of the renal vasculature such as fibromuscular dysplasia. The work-up of a young female presenting with renal artery thrombosis without any previous medical history screens for a wide range of pathological processes.

Zebrafish metabolomics: a comprehensive approach to understanding health and disease

Zebrafish (Danio rerio) have become a valuable model in biomedical research due to their genetic similarity to humans, rapid development, and suitability for high-throughput studies. Metabolomic analyses in zebrafish provide critical insights into the biochemical pathways underlying health and disease. This review explores the applications of metabolomics in zebrafish research, highlighting its contributions to understanding embryonic development, tuberculosis, neurodegenerative disorders such as Alzheimer's disease, obesity-related metabolic dysfunction, and drug-induced toxicity through a thorough literature review. Zebrafish metabolomics reveals dynamic metabolite shifts during vertebrate development. In tuberculosis research, zebrafish models have helped identify metabolic biomarkers with potential translational relevance. Studies on Alzheimer's disease suggest that metabolomics can elucidate neuroprotective mechanisms, while investigations into obesity have provided insights into metabolic imbalances associated with kidney dysfunction. Furthermore, toxicometabolomic studies have demonstrated the utility of zebrafish in assessing drug-induced renal injury. Despite their advantages, zebrafish metabolomics faces challenges, including differences in metabolic rates compared to mammals, the need for standardized protocols, and limitations in metabolite database annotations. Nonetheless, integrating metabolomics with other omics approaches holds great promise for advancing disease research and paving the way for personalized medicine.

Advances in Nano-Immunomodulatory Systems for the Treatment of Acute Kidney Injury

Acute kidney injury (AKI) occurs when there is an imbalance in the immune microenvironment, leading to ongoing and excessive inflammation. Numerous immunomodulatory therapies have been suggested for the treatment of AKI, the current immunomodulatory treatment delivery systems are suboptimal and lack efficiency. Given the lack of effective treatment, AKI can result in multi-organ dysfunction and even death, imposing a significant healthcare burden on both the family and society. This underscores the necessity for innovative treatment delivery systems, such as nanomaterials, to better control pathological inflammation, and ultimately enhance AKI treatment outcomes. Despite the modification of numerous immunomodulatory nanomaterials to target the AKI immune microenvironment with promising therapeutic results, the literature concerning their intersection is scarce. In this article, the pathophysiological processes of AKI are outlined, focusing on the immune microenvironment, discuss significant advances in the comprehension of AKI recovery, and describe the multifunctionality and suitability of nanomaterial-based immunomodulatory treatments in managing AKI. The main obstacles and potential opportunities in the swiftly advancing research field are also clarified.

Unraveling the Mechanisms of Magnesium Supplementation in Alleviating Chronic Kidney Disease Complications and Progression: Balancing Risks and Benefits

Chronic kidney disease (CKD) is a major cause of death and disability worldwide. It is usually diagnosed at early levels because of its slow progression. Treatment should consider CKD complications (such as electrolyte level imbalance, vascular calcification, and bone mineral disorders), as well as the development of CKD itself. Large-scale studies have shown that current treatment guidelines are nearly ineffective and fail to achieve treatment goals. Guidelines have not paid as much attention to magnesium (Mg) as the other electrolytes, while Mg has a significant role in the treatment goals of CKD. Hypomagnesemia is the only electrolyte imbalance that is equally prevalent in all stages of CKD. A lower plasma Mg level in each stage of CKD is associated with a higher risk of CKD progression and cardiac events. Magnesium exerts its effects both directly and via other ions. Mg supplementation increases insulin sensitivity while reducing proteinuria and inflammation. It lowers blood pressure and inhibits vascular calcification primarily because of its effects on calcium and phosphate, respectively. Vitamin D supplementation for low-active vitamin D in CKD patients increases vascular calcification and cardiac events, but magnesium supplementation enhances vitamin D levels and activity without increasing the risk of cardiac events. However, careful attention is required due to the potential threats of hypermagnesemia, particularly in advanced CKD stages. Starting magnesium supplementation early in patients' treatment plans will result in fewer side effects and more advantages. More original research is needed to determine its optimal dose and serum levels.

Mehran vs. Mehran2 pre-procedure: which score better predicts risk of contrast-induced acute kidney injury in patients with acute coronary syndrome?

Background

Contrast-induced acute kidney injury (CI-AKI) is a significant concern during percutaneous coronary intervention (PCI) procedures. The novel Mehran 2 pre-procedural risk score, an updated version of the original Mehran score, shows promise as a predictive tool. However, its effectiveness specifically in acute coronary syndrome (ACS) patients requires further investigation. This study aims to evaluate the performance of Mehran 2 pre-procedure risk score compared to original score in predicting CI-AKI risk in acute coronary syndrome patients undergoing PCI.

Material and Methods

A prospective cohort study was conducted with patients with ACS undergoing PCI, who were followed up for 90 days (December 2019-February 2021). The Mehran 2 CI-AKI risk score with pre-procedure data was compared with the original Mehran score. Receiver operating characteristic (ROC) curve and area under the ROC curve (AUC-ROC) were used to evaluate the discriminative capacity.

Results

192 patients were analyzed and 33% (n = 64) developed CI-AKI. CI-AKI outcome was associated with advanced age, arterial hypertension, chronic kidney disease, troponin T, hemodynamic instability, serum hemoglobin, serum creatinine, and higher both Mehran scores. Both scores demonstrated good agreement. The original Mehran score demonstrated superior CI-AKI stratification with higher sensitivity (85.94%) and specificity (60.16%) compared to the Mehran 2 pre-procedural score (sensitivity 50%, specificity 75%). Significant differences were observed in the discriminative performance between both scores.

Conclusion

Sociodemographic, clinical, and laboratory variables were associated with CI-AKI. The original Mehran score demonstrated more consistent discriminative capacity for predicting CI-AKI risk in ACS patients undergoing PCI compared to the Mehran 2 pre-procedural score.

Impact of Dexmedetomidine Dosing and Timing on Acute Kidney Injury and Renal Outcomes After Cardiac Surgery: A Meta-Analytic Approach

BACKGROUND

Acute kidney injury (AKI) is a common and serious complication following cardiac surgery. Dexmedetomidine, a highly selective α2-adrenergic agonist, has shown potential renoprotective effects, but previous studies have yielded conflicting results.

OBJECTIVE

This meta-analysis aimed to evaluate the efficacy and safety of dexmedetomidine in preventing AKI and reducing postoperative serum creatinine levels in adult patients undergoing cardiac surgery.

METHODS

We comprehensively searched 5 databases for randomized controlled trials comparing dexmedetomidine with control groups in adult cardiac surgery patients. The main outcomes were the incidence of AKI and change in postoperative serum creatinine levels. Meta-analyses were conducted using RevMan 5.4 models, and subgroup analyses were performed based on dexmedetomidine dosing and timing of administration. Continuous outcomes were combined and analyzed using either mean difference (M.D.), while dichotomous outcomes were analyzed using risk ratio (RR) with 95% confidence intervals (CI).

RESULTS

Our study included a total of 14 trials involving 2744 patients. Dexmedetomidine administration significantly reduced the incidence of AKI compared to control groups (RR = 0.54, 95% CI: 0.41-0.70, P < 0.00001). Postoperative serum creatinine levels were also lower with dexmedetomidine (MD = -0.14 mg/dL, 95% CI: -0.28 to -0.001, P =0.04). Subgroup analyses revealed that higher initial doses (>0.5 μg/kg) and administration during intraoperative and postoperative periods were associated with more pronounced renoprotective effects. Dexmedetomidine did not significantly affect mortality but reduced the duration of the length of hospital stay and mechanical ventilation.

CONCLUSIONS AND RELEVANCE

This meta-analysis demonstrates that dexmedetomidine administration, particularly at higher doses and during both intraoperative and postoperative periods, reduces the risk of AKI in adults undergoing cardiac surgery. These findings support the use of dexmedetomidine as a preventive strategy to enhance renal outcomes in this population.

Identification and validation of leukemia inhibitory factor as a protective factor in ischemic acute kidney injury

BACKGROUND

Ischemia-reperfusion injury (IRI) is a common pathophysiological mechanism of acute kidney injury (AKI). There is an urgent need for a more comprehensive analysis of its underlying mechanisms.

MATERIALS AND METHODS

The RNA-sequencing dataset GSE153625 was used to examine differentially expressed genes (DEGs) of kidney tissues in IRI-AKI mice compared with sham mice. We used 10 algorithms provided by cytohubba plugin and four external datasets (GSE192532, GSE52004, GSE98622, and GSE185383) to screen for hub genes. The IRI-AKI mouse model with different reperfusion times was established to validate the expression of hub gene in the kidneys. HK-2 cells were cultured in vitro under hypoxia/reoxygenation (H/R) conditions, via transfection with si-LIF or supplementation with the LIF protein to explore the function of the LIF gene.

RESULTS

We screened a total of 1,540 DEGs in the IRI group compared with the sham group and identified that the LIF hub gene may play potential roles in IRI-AKI. LIF was markedly upregulated in the kidney tissues of IRI-AKI mice, as well as in HK-2 cells grown under H/R conditions. The knockdown of LIF aggravated apoptosis and oxidative stress (OS) injury under H/R conditions. Administration of the LIF protein rescued the effects of si-LIF, alleviating cellular apoptosis and OS.

CONCLUSION

These findings indicate an important role of the LIF gene in term of regulating apoptosis and OS in the early phases of IRI-AKI. Targeting LIF may therefore represent a promising therapeutic strategy for IRI-AKI.

Association Between Systemic Immune-Inflammation Index and Outcomes of Acute Myocardial Infarction: A Systemic Review and Meta-Analysis

Objective: To assess the link between systemic immune-inflammation index (SII) and risk of major adverse cardiovascular events (MACE), contrast-induced nephropathy (CIN), and overall mortality in patients with acute myocardial infarction (AMI). Patients and Methods: Electronic search of PubMed, EMBASE, Web of Science, and Scopus databases was done for observational studies with the data on the association of SII and outcomes, such as MACE, and CIN in adult (≥18 y) patients with AMI. A random-effects model was used, and the pooled effect sizes were expressed as relative risk (RR) with corresponding 95% confidence intervals (CI). Subgroup analysis was conducted on the basis of the type of AMI (ST elevation myocardial infarction and non-ST elevation myocardial infarction), sample size (≥500 and <500), and study design. GRADE assessment was used to evaluate the certainty of the evidence. Results: The analysis included 23 studies. Most studies were conducted in China (n = 13), followed by Turkey (n = 10). Majority of the studies (n = 20) had a retrospective cohort design. Patients with high SII had increased risk of MACE (RR 2.95, 95% CI: 1.25, 6.99; n = 5, I2 = 97.5%), overall mortality (RR 2.59, 95% CI: 1.64, 4.07; n = 6, I2 = 58.0%), and CIN (RR 4.58, 95% CI: 3.44, 6.10; n = 4, I2 = 0.0%), compared with patients with lower SII. Egger's test detected publication bias for MACE (p = 0.047) and overall mortality (p = 0.012) but not for CIN. These associations remained valid in subgroup analysis. Conclusion: Findings suggest that higher SII in patients with AMI is associated with increased risks of MACE, CIN, and overall mortality. This underscores SII's potential as a prognostic marker in AMI.

Identification of c-Jun phosphorylation as a crucial mediator of complement activation in renal ischemia-reperfusion injury revealed by phosphoproteomics and functional validation

BACKGROUND

Ischemia reperfusion injury (IRI) is an unavoidable condition that primarily affects graft function in renal transplantation. Blockage of complement activation by complement receptor immunoglobulin/ factor H (CRIg/FH), a novel complement inhibitor, shows great potency to ameliorate renal IRI. Sublytic membrane attack complex (MAC) disrupts cellular functions via the activation of different protein kinases and phosphorylation of critical signal transduction factors. We aimed to investigate whether complement activation triggered shift in phosphorylation status in IRI.

METHODS AND RESULTS

We performed a LC-MS/MS-based quantitative phosphoproteomic analysis of CRIg/FH-IRI, PBS-IRI and Sham mice, depicting a thorough protein phosphorylation profile. C3d and MAC staining were conducted to study the complement activation status. In vitro model mimicking complement mediated IRI tubular injury was achieved by applying normal human serum (NHS) to TCMK cells. By hierarchical clustering, we observed that CRIg/FH treatment reversed the hyperphosphorylation status triggered by IRI. Differentially expressed phosphoproteins (DEPs) were associated with focal adhesion, integrin activation, actin cytoskeleton organization and cell junction. We identified c-Jun as the most differentially phosphorylated transcriptional factor regulated by complement activation, the S63 phosphorylation of which was verified both in vitro and in vivo and screened for its downstream targets. JNK inhibitor reduced the phosphorylation of c-Jun and attenuated accumulation of the C3d on the tubular epithelial cells.

CONCLUSION

We proposed a crucial role of c-Jun phosphorylation in complement activation induced by renal IRI by combining phosphoproteomic approaches and protein validation, which hopefully could provide novel insights into the pathological mechanisms of IRI.

Emerging role of mesenchymal stem cell-derived exosomes in the repair of acute kidney injury

Acute kidney injury (AKI) is a clinical syndrome characterized by a rapid deterioration in kidney function and has a significant impact on patient health and survival. Mesenchymal stem cells (MSCs) have the potential to enhance renal function by suppressing the expression of cell cycle inhibitors and reducing the expression of senescence markers and microRNAs via paracrine and endocrine mechanisms. MSC-derived exosomes can alleviate AKI symptoms by regulating DNA damage, apoptosis, and other related signaling pathways through the delivery of proteins, microRNAs, long-chain noncoding RNAs, and circular RNAs. This technique is both safe and effective. MSC-derived exosomes may have great application prospects in the treatment of AKI. Understanding the underlying mechanisms will foster the development of new and promising therapeutic strategies against AKI. This review focused on recent advancements in the role of MSCs in AKI repair as well as the mechanisms underlying the role of MSCs and their secreted exosomes. It is anticipated that novel and profound insights into the functionality of MSCs and their derived exosomes will emerge.

Adding insult to injury: the spectrum of tubulointerstitial responses in acute kidney injury

Acute kidney injury (AKI) encompasses pathophysiology ranging from glomerular hypofiltration to tubular cell injury and outflow obstruction. This Review will focus on the tubulointerstitial processes that underlie most cases of AKI. Tubular epithelial cell (TEC) injury can occur via distinct insults, including ischemia, nephrotoxins, sepsis, and primary immune-mediated processes. Following these initial insults, tubular cells can activate survival and repair responses or they can develop mitochondrial dysfunction and metabolic reprogramming, cell-cycle arrest, and programmed cell death. Developing evidence suggests that the fate of individual tubular cells to survive and proliferate or undergo cell death or senescence is frequently determined by a biphasic immune response with initial proinflammatory macrophage, neutrophil, and lymphocyte infiltration exacerbating injury and activating programmed cell death, while alternatively activated macrophages and specific lymphocyte subsets subsequently modulate inflammation and promote repair. Functional recovery requires that this reparative phase supports proteolytic degradation of tubular casts, proliferation of surviving TECs, and restoration of TEC differentiation. Incomplete resolution or persistence of inflammation can lead to failed tubular repair, fibrosis, and chronic kidney disease. Despite extensive research in animal models, translating preclinical findings to therapies remains challenging, emphasizing the need for integrated multiomic approaches to advance AKI understanding and treatment.

Prognostic value of contrast-enhanced ultrasound in dogs with acute renal injury treated with haemodialysis

BACKGROUND

It is clinically relevant to predict outcomes in dogs with acute kidney injury (AKI) treated with haemodialysis. The aim of this study was to evaluate the prognostic value of contrast-enhanced ultrasound (CEUS) and its role in discriminating between AKI and acute impairment associated with chronic kidney disease (AKI/CKD).

METHODS

Dogs diagnosed with AKI or AKI/CKD were prospectively enrolled in the study. For all dogs, CEUS was performed at admission (T0). In addition, in haemodialysis-treated dogs, it was performed after the first dialysis (T1) and 7 days (T7) and 30 days (T30) after admission.

RESULTS

A total of 41 dogs were enrolled, of which 30 were treated with haemodialysis and 11 received medical therapy. No significant difference was found between CEUS values at T0 in surviving and non-surviving patients after haemodialysis. A significant difference in cortical peak enhancement intensity (PI) values was found between T0, T1, T7 and T30, with the highest PI value at T0, a significant reduction at T1 and a progressive reduction in subsequent checks. There were no significant differences in CEUS parameters at T0 between patients with AKI and AKI/CKD.

LIMITATIONS

AKI aetiology was unknown in most cases, which limits the generalisability of the findings. Furthermore, the small sample size means that the statistical analysis is likely underpowered.

CONCLUSION

CEUS could be helpful in evaluating of the prognosis of dogs with AKI during haemodialysis.

Diallyl Trisulfide Attenuates Ischemia-Reperfusion-Induced ER Stress and Kidney Dysfunction in Aged Female Mice

Ischemia-reperfusion injury (IRI) is a common cause of acute kidney injury (AKI) in the aging population. Gender studies show that aging is associated with loss of protection from AKI in the female population. While ER stress contributes to IRI-induced AKI in the young, ER regulation during IR in the aged kidney is unclear. Because current evidence suggests hydrogen sulfide (H2S) modulates ER stress, we investigated whether exogenous supplementation of diallyl trisulfide (DATS), an H2S donor, mitigates AKI in aged female kidneys. Wild-type (WT, C57BL/6J) mice aged 75-78 weeks were treated with or without DATS before and after renal IRI. IRI increased ER stress proteins, inflammation, and fibrosis markers in the IRI kidney compared to the control. DATS mitigated ER stress, and reduced inflammation and fibrosis markers in the IRI kidney. Further, IRI kidneys demonstrated reduced blood flow, vascularity, angiogenesis, increased resistive index (RI), and reduced function. DATS treatment upregulated PI3K, AKT, p-mTOR, and pMAPK signaling to stimulate angiogenesis, which improved vascular density, blood flow, and renal function. Together, our results suggest that DATS rescues the aged female kidney IRI by modulating ER stress and upregulation of angiogenesis.

IL-1 receptor antagonist anakinra downregulates inflammatory cytokines during renal normothermic machine perfusion: Preliminary results

BACKGROUND

The interleukin 1 (IL-1) cytokine group plays a key role in sterile inflammation and may be an important target for transplant-related renal injury. This study examined the effects of anakinra, a non-specific IL-1 receptor antagonist, administered during normothermic machine perfusion (NMP) of porcine kidneys.

METHOD

Paired porcine kidneys (n = 5 pairs) underwent 15 min of warm ischemia plus 2 h of static cold storage in ice. Kidneys were then perfused with autologous whole blood using an ex vivo NMP platform. Kidneys were randomly allocated to receive anakinra or vehicle administered at the start of NMP. Cortical biopsies were collected at baseline before ischemic injury and at the end of NMP. Functional parameters were recorded and calculated, and inflammatory markers were measured by qPCR and ELISA techniques.

RESULTS

During NMP, there were no statistically significant differences in renal blood flow, urine output, creatinine clearance or fractional excretion of sodium in the anakinra and control groups. The administration of anakinra significantly downregulated transcriptional expression of IL-6, Fas ligand and intercellular adhesion molecule 1 (p = 0.029, 0.029, 0.028, respectively).

CONCLUSION

Anakinra, an IL-1 receptor blocker, successfully attenuated the downstream inflammatory and immune-mediated response within the kidney during NMP.

Clopidogrel protects against gentamicin-induced nephrotoxicity through targeting oxidative stress, apoptosis, and coagulation pathways

Gentamicin (Genta)-induced nephrotoxicity poses a significant clinical challenge due to its detrimental effects on kidney function. Clopidogrel (Clop), an antiplatelet drug known for its ability to prevent blood clots by inhibiting platelet aggregation, also has potential effects on oxidative stress and cell death. This study investigates Clop's protective role against Genta-induced nephrotoxicity, emphasizing the importance of the coagulation cascade. The 32 adult male albino rats were randomly assigned to four groups of eight (n = 8). The first group received only the vehicle. Genta was injected intraperitoneally at 100 mg/kg/day for 8 days in the second group. Groups 3 and 4 received oral Clop at 10 and 20 mg/kg/day for 1 week before Genta delivery and throughout the experiment. Renal tissue showed renal function tests, oxidative stress, pro-inflammatory cytokines, apoptotic markers, coagulation profile, and fibrin expression. Clop improved Genta-induced kidney function and histopathology. Clop substantially reduced pro-inflammatory cytokines, oxidative stress indicators, pro-apoptotic proteins, and fibrin protein. Clop also significantly boosted renal tissue anti-inflammatory and anti-apoptotic protein expression. Genta-induced nephrotoxicity involves oxidative stress, apoptosis, and coagulation system activation, according to studies. This study underscores that Genta-induced nephrotoxicity is associated with oxidative stress, apoptosis, and activation of the coagulation system. Clop's protective effects on nephrons are attributed to its anticoagulant, antioxidant, anti-inflammatory, and anti-apoptotic properties, presenting it as a promising therapeutic strategy against Genta-induced kidney damage.

Crosstalk between glomeruli and tubules

Models of kidney injury have classically concentrated on glomeruli as the primary site of injury leading to glomerulosclerosis or on tubules as the primary site of injury leading to tubulointerstitial fibrosis. However, current evidence on the mechanisms of progression of chronic kidney disease indicates that a complex interplay between glomeruli and tubules underlies progressive kidney injury. Primary glomerular injury can clearly lead to subsequent tubule injury. For example, damage to the glomerular filtration barrier can expose tubular cells to serum proteins, including complement and cytokines, that would not be present in physiological conditions and can promote the development of tubulointerstitial fibrosis and progressive decline in kidney function. In addition, although less well-studied, increasing evidence suggests that tubule injury, whether primary or secondary, can also promote glomerular damage. This feedback from the tubule to the glomerulus might be mediated by changes in the reabsorptive capacity of the tubule, which can affect the glomerular filtration rate, or by mediators released by injured proximal tubular cells that can induce damage in both podocytes and parietal epithelial cells. Examining the crosstalk between the various compartments of the kidney is important for understanding the mechanisms underlying kidney pathology and identifying potential therapeutic interventions.

Active immunologic participation and metabolic shutdown of kidney structural cells during kidney transplant rejection

Contrary to immune cells, the response of the kidney structural cells in rejection is less established. We performed single-cell RNA sequencing of 18 kidney transplant biopsies from 14 recipients. Single-cell RNA sequencing identified cells from the major compartments of the kidney, next to infiltrated immune cells. Endothelial cells from the glomerulus, peritubular capillaries, and vasa recta showed upregulation of class I and II human leukocyte antigen genes, adhesion molecules, cytokines, and chemokines, suggesting active participation in the alloimmune process, with compartment-specific differences. Epithelial cells including proximal tubular, loop of Henle, and collecting duct cells, also showed increased expression of immune genes. Strikingly, in proximal tubule cells, a strong downregulation of energy metabolism upon inflammation was observed. There was a large overlap between the cell-specific expression changes upon alloimmune inflammation and those observed in 2 large microarray biopsy cohorts. In conclusion, the kidney structural cells, being the main target of the alloimmune process, appear to actively contribute herein, enhancing the damaging effects of the infiltrating immune cells. In epithelial cells, a profound shutdown of metabolism was seen upon inflammation, which is associated with poor kidney function. These observations highlight the critical role of the graft in triggering and sustaining rejection after transplantation.

The differential effect of Interferon-gamma on acute kidney injury and parasitemia in experimental malaria

Malaria-associated acute kidney injury (MAKI) is a common complication of Plasmodium infection, affecting ~ 50% of severe malaria cases and associated with increased mortality. However, its immunopathogenesis remains unclear. Interferon-gamma (IFN-gamma) is a crucial cytokine that influences parasite clearance and mediates pathogenesis in experimental models of malaria. This study explored the role of IFN-gamma in kidney pathology in C57BL/6 mice infected with Plasmodium berghei NK65 (PbNK65) and P. chabaudi AS (PcAS). PbNK65-infected mice, normally susceptible to severe malaria, were protected from both MAKI and malaria-associated acute respiratory distress syndrome (MA-ARDS) when lacking IFN-gamma. Infected IFN-gamma knockout (KO) mice developed low parasitemia levels, minimal kidney histopathological changes and reduced expression of the kidney injury marker Neutrophil Gelatinase-Associated Lipocalin (NGAL). In contrast, upon PcAS-infection, IFN-gamma deficiency led to increased parasitemia and aggravated kidney pathology, evidenced by proteinuria, hyaline casts in kidneys and increased renal mRNA expression of Heme Oxygenase 1 (HO-1) and NGAL. In both models, IFN-gamma induced renal C-X-C Motif Chemokine Ligand 10 (CXCL10) but did not affect Tumor Necrosis Factor-alpha (TNF-alpha) expression. Our data indicate that IFN-gamma exerts a dual effect on kidney pathology, which is conditioned by the mouse model and its impact on parasitemia.

Aromadendrin alleviates LPS-induced kidney apoptosis and inflammation by inhibiting phosphorylation of MAPK and NF-κB signaling pathways

BACKGROUND

Excessive inflammation and apoptosis in kidneys are critical players in the pathogenesis of acute kidney injury (AKI). Aromadendrin is a natural flavonoid characterized by anti-inflammatory, anti-apoptotic, and antioxidant actions. Thus, we investigated the roles and mechanisms of aromadendrin in the development of AKI.

METHODS

Lipopolysaccharide (LPS) was used to induce AKI mice, and one hour after LPS challenge, the mice received oral administration of aromadendrin or vehicle. Renal functions were assessed by measuring blood urea nitrogen and creatinine in serum. Histological changes were determined by hematoxylin and eosin staining. Apoptotic cells of renal tissues were detected by TUNEL staining. Gene expression was measured by western blotting and RT-qPCR.

RESULTS

Aromadendrin alleviated LPS-induced renal dysfunctions and histological defects in mice. Additionally, aromadendrin suppressed excessive inflammation and tissue apoptosis in the kidneys of LPS-induced AKI mice. Mechanistically, aromadendrin blocked the activation of NF-κB and MAPK pathways in LPS-induced AKI mice.

CONCLUSION

Aromadendrin alleviates LPS-stimulated inflammation and tissue cell apoptosis in kidneys by inactivating the NF-κB and MAPK pathways.

Pan AMPK activation protects tubules in rat ischemic acute kidney injury

Acute kidney injury (AKI) is characterized by an abrupt decline in kidney function and has been associated with excess risks of death, kidney disease progression, and cardiovascular events. The kidney has a high energetic demand with mitochondrial health being essential to renal function, and damaged mitochondria have been reported across AKI subtypes. 5' Adenosine monophosphate-activated protein kinase (AMPK) activation preserves cellular energetics through improvement of mitochondrial function and biogenesis when ATP levels are low, such as under ischemia-induced AKI. We developed a selective potent small molecule pan AMPK activator, compound 1, and tested its ability to increase AMPK activity and preserve kidney function during ischemia/reperfusion injury in rats. A single administration of compound 1 caused sustained activation of AMPK for at least 24 hours, protected against acute tubular necrosis, and reduced clinical markers of tubular injury such as NephroCheck and fractional excretion of sodium. Reduction in plasma creatinine and increased glomerular filtration rate indicated preservation of kidney function. Surprisingly, we observed a strong diuretic effect of AMPK activation associated with natriuresis both with and without AKI. Our findings demonstrate that activation of AMPK leads to protection of tubular function under hypoxic/ischemic conditions which holds promise as a potential novel therapeutic approach for AKI. SIGNIFICANCE STATEMENT: No approved pharmacological therapies currently exist for acute kidney injury. We developed compound 1, which dose-dependently activated 5' adenosine monophosphate-activated protein kinase in the kidney and protected kidney function and tubules after ischemic renal injury in the rat. This was accompanied by natriuresis in injured as well as uninjured rats.

Temporary bilateral clamping of renal arteries induces ischemia-reperfusion: A new pig model of acute kidney injury using total intravenous anesthesia

Ischemia-reperfusion (IR) is a leading cause of acute kidney injury (AKI), and pigs are commonly used in preclinical AKI models. However, existing models often vary in the methods used to induce ischemia, and the resulting AKI tends to be mild-to-moderate. Moreover, follow-up is often performed under volatile anesthesia, which, in contrast to total intravenous anesthesia (TIVA), can induce malignant hyperthermia and cause hemodynamic instability. Here we present a novel surgical model of IR-induced AKI using bilateral renal artery clamping under TIVA. Anesthesia was induced via TIVA with diazepam, ketamine, and morphine. After retroperitoneal exposure, the renal arteries were isolated and clamped with a plastic tube for 90 min, followed by 8 h of reperfusion. The IR group (n = 6) was compared with a Sham group (n = 5) that underwent the same procedure without IR. The IR group developed moderate-to-severe AKI as evidenced by reduced glomerular filtration, a 158% increase in plasma creatinine versus 21% in the Sham group, and elevated neutrophil gelatinase-associated lipocalin levels (+280% in IR vs. 0% in Sham), indicating tubular injury. Histopathology confirmed these findings. Thus, this preclinical model successfully induced moderate-to-severe AKI in pigs. The TIVA anesthetic protocol offered several advantages compared to halogenated gas anesthesia.

Excess dietary sodium restores electrolyte and water homeostasis caused by loss of the endoplasmic reticulum molecular chaperone, GRP170, in the mouse nephron

The maintenance of fluid and electrolyte homeostasis by the kidney requires proper folding and trafficking of ion channels and transporters in kidney epithelia. Each of these processes requires a specific subset of a diverse class of proteins termed molecular chaperones. One such chaperone is GRP170, which is an Hsp70-like, endoplasmic reticulum (ER)-localized chaperone that plays roles in protein quality control and protein folding in the ER. We previously determined that loss of GRP170 in the mouse nephron leads to hypovolemia, electrolyte imbalance, and rapid weight loss. In addition, GRP170-deficient mice develop an acute kidney injury (AKI)-like phenotype, typified by tubular injury, elevation of kidney injury markers, and induction of the unfolded protein response (UPR). By using an inducible GRP170 knockout cellular model, we confirmed that GRP170 depletion induces the UPR, triggers apoptosis, and disrupts protein homeostasis. Based on these data, we hypothesized that UPR induction underlies hyponatremia and volume depletion in these rodents and that these and other phenotypes might be rectified by sodium supplementation. To test this hypothesis, control and GRP170 tubule-specific knockout mice were provided a diet containing 8% sodium chloride. We discovered that sodium supplementation improved electrolyte imbalance and kidney injury markers in a sex-specific manner but was unable to restore weight or tubule integrity. These results are consistent with UPR induction contributing to the kidney injury phenotype in the nephron-specific GR170 knockout model and indicate that GRP170 function in kidney epithelia is essential to both maintain electrolyte balance and ER homeostasis.NEW & NOTEWORTHY Loss of the endoplasmic reticulum chaperone, GRP170, results in widespread kidney injury and induction of the unfolded protein response (UPR). We now show that sodium supplementation is able to at least partially restore electrolyte imbalance and reduce kidney injury markers in a sex-dependent manner.

Involvement of Mineralocorticoid Receptor Activation by High Mobility Group Box 1 and Receptor for Advanced Glycation End Products in the Development of Acute Kidney Injury

Key Points

Our study revealed that high mobility group box 1 activates the mineralocorticoid receptor (MR) through the receptor for advanced glycation end products (RAGE) in AKI. MR antagonists and RAGE aptamers inhibited high mobility group box 1–induced Rac1/MR activation and downstream inflammatory molecules in endothelial cells. MR antagonists and RAGE aptamers may represent promising therapeutic strategies for preventing AKI and CKD progression.

Background

Although AKI is associated with an increased risk of CKD, the underlying mechanisms remain unclear. High mobility group box 1 (HMGB1), one of the ligands for the receptor for advanced glycation end products (RAGE), is elevated in patients with AKI. We recently demonstrated that the mineralocorticoid receptor (MR) is activated by the RAGE/Rac1 pathway, contributing to chronic renal damage in hypertensive mice. Therefore, this study investigated the role of the HMGB1/RAGE/MR pathway in AKI and progression to CKD.

Methods

We performed a mouse model of renal ischemia–reperfusion (I/R) with or without MR antagonist (MRA). In vitro experiments were conducted using cultured endothelial cells to examine the interaction between the HMGB1/RAGE and Rac1/MR pathways.

Results

In renal I/R injury mice, renal MR activation was associated with elevated serum HMGB1, renal RAGE, and activated Rac1, all of which were suppressed by MRA. Renal I/R injury led to renal dysfunction, tubulointerstitial injury, and increased expressions of inflammation and fibrosis mediators, which were ameliorated by MRA. In vitro , RAGE aptamer or MRA inhibited HMGB1-induced Rac1/MR activation and upregulation of monocyte chemoattractant protein 1 and NF-κB expressions. Seven days after I/R injury, renal I/R injury mice developed CKD, whereas MRA prevented renal injury progression and decreased the mortality rate. Furthermore, in case of MRA treatment even after I/R injury, attenuated renal dysfunction compared with untreated mice was also observed.

Conclusions

Our findings suggest that HMGB1 may play a crucial role in AKI and CKD development by activating the Rac1/MR pathway through interactions with RAGE.

Robotic-Assisted Radical Cystectomy and Acute Intraoperative Hyperkalemia: A Case Series

Taking into consideration the effects of pneumoperitoneum on kidney function, anesthesiologists should diligently monitor potassium levels during robotic-assisted radical cystectomy, particularly during prolonged ureter clamping, in the presence of chronic kidney disease, administration of renin-angiotensin-aldosterone system-blocking medications, or when there is a high risk of rhabdomyolysis.

Effect of adenosine triphosphate on methylphenidate-induced oxidative and inflammatory kidney damage in rats

The purpose of this trial was to assess the effects of methylphenidate on the kidney tissues and to investigate the protective effect of adenosine triphosphate (ATP) against possible methylphenidate nephrotoxicity in rats. The rats were separated into; healthy control (HG), methylphenidate (MPHG), ATP (ATPG), and ATP+ methylphenidate (AMPG). The ATPG and AMPG groups were administered ATP 4 mg/kg bw/d, and the HG and MPHG groups received distilled water intraperitoneally. One hour from, ATP and distilled water administration, methylphenidate 10 mg/kg bw/d was applied via oral gavage to the AMPG and MPHG groups once daily for 30 d (1 × 1). Animals were euthanized after 30 d and tissues were collected. The levels of certain oxidant/antioxidant parameters, pro-inflammatory cytokines, and Blood urea nitrogen (BUN) and creatinine levels were measured. Kidneys were also examined histopathologically. ATP inhibited the increase in oxidant and decrease antioxidant levels induced by methylphenidate. The amounts of pro-inflammatory cytokines were increased in methylphenidate-treated kidney tissue compared with the HG and AMPG groups. However, ATP increased oxidative damage markers and cytokines levels close to the healthy group. Serum BUN and creatinine levels increased with methylphenidate but ATP prevented BUN and creatinine from rising in the ATPG and MPHG groups. ATP also reduced the histopathological damage increased by methylphenidate. The potential efficacy of ATP in treating kidney damage induced by methylphenidate use.

Association between intraoperative fluid management and postoperative outcomes in living kidney donors: a retrospective cohort study

Optimal fluid strategy for laparoscopic donor nephrectomy (LDN) remains unclear. LDN has been a domain for liberal fluid management to ensure graft perfusion, but this can result in adverse outcomes due to fluid overload. We compared postoperative outcome of living kidney donors according to the intraoperative fluid management. Five hundred and five LDNs performed over a six-year period at a tertiary hospital were analyzed. Donors were divided into tertiles according to intraoperative crystalloid infusion rate (ml/kg/hr), and associations between the tertile and outcomes were investigated with inverse probability of treatment weighting with entropy balancing. Primary outcome was maximal rise of serum creatinine (sCr). Secondary outcomes were sCr rise meeting Acute Kidney Injury (AKI) criteria, time to reach minimal sCr, and length of hospital stay. The following covariates were used: age, sex, body weight, height, diabetes mellitus, hypertension, preoperative estimated glomerular filtration rate, operation duration, surgeon, nephrectomy side, and estimated blood loss. Median intraoperative crystalloid infusion rate was 3.5, 4.6, and 6.0 ml/kg/hr in the first, second, and third tertile, respectively (group 1, 2, and 3). Maximal rise of sCr did not differ between groups (P = 0.274). Twofold increase in sCr (equivalent to stage 2 AKI) during the first week and prolonged hospitalization were most frequent in group 1 [7.8 vs. 1.1 vs. 1.5%, P = 0.004; 7.9 vs. 3.1 vs. 0.7%, P = 0.003]. Time to reach minimal sCr was longest in group 1. No differences were found in recipient early renal function. Hypovolemia is associated with poor postoperative outcomes after LDN. Efforts to find the optimal fluid management should be continued.

Trehalose activates autophagy to alleviate cisplatin-induced chronic kidney injury by targeting the mTOR-dependent TFEB signaling pathway

Rationale: Cisplatin is a potent chemotherapeutic agent limited by significant nephrotoxicity. Multiple cycles of cisplatin administration are necessary to confer chronic disease. Autophagy is a lysosomal degradation pathway that enables the clearance and reuse of cytoplasmic components and is essential for maintaining the integrity and normal physiological function of tissues and organs. However, the precise role of autophagy in renal fibrosis has been controversial. Trehalose, a well-known autophagy inducer, plays a cytoprotective role under various stress conditions, such as oxidative damage, dehydration, and temperature changes. In this study, we established a model of cisplatin-induced chronic kidney disease (CKD) and human renal tubular epithelial cells (HK2) injury to investigate the nephroprotective effects of trehalose on cisplatin-induced CKD and the underlying mechanisms involved. Methods: Firstly, we measured the role of autophagy in cisplatin-induced injury models both in vivo and in vitro by western blot and immunofluorescence staining, combined with transcriptomics. Then, biomedical, cellular, and molecular approaches were utilized to evaluate the potential protective effect of trehalose intervention in regulating autophagy. Mechanistically, we performed this study using proximal tubular epithelial cells-specific transcription factor EB (TFEB) knockout mice and TFEB small-interfering RNA technology to determine whether TFEB deficiency affects the pharmacological effected of trehalose in cisplatin-induced injury models. Results: Due to the activation of autophagy, trehalose inhibited mitochondrial dysfunction (mitochondrial fragmentation, depolarization, reactive oxygen species) and cellular senescence induced by cisplatin both in vitro and in vivo. Moreover, renal dysfunction, pathological changes and fibrosis were alleviated in CKD mice after trehalose treatment. Mechanistic investigations revealed that trehalose accumulated in lysosomes and inhibited mTORC1 activity, which triggered TFEB and TFEB-mediated autophagy. In addition, siRNA-mediated knockdown of TFEB in HK2 cells or renal proximal tubular epithelial cells-specific (TECs-specific) TFEB deficiency in mice markedly abolished the beneficial effects of trehalose. Conclusion: Our findings suggested that trehalose induced autophagy to alleviate cisplatin-induced chronic kidney injury by targeting the mTOR-dependent TFEB signaling pathway.

Severe Diabetic Ketoacidosis in Children with Type 1 Diabetes: Ongoing Challenges in Care

Diabetic ketoacidosis is the most common acute complication in children and adolescents with type 1 diabetes, and contributes significantly to morbidity, mortality, and healthcare burden. This review aims to explore the multifaceted aspects of severe diabetic ketoacidosis in pediatric age, including its epidemiology, pathogenesis, risk factors, complications and emphasizing advances in prevention strategies. Incidence rates vary due to influences from geographic, socioeconomic, cultural and demographic factors. Pathogenesis is linked to insulin deficiency and an excess of counter-regulatory hormones, which disrupt glucose, protein, and lipid metabolism, causing hyperglycemia, ketosis, acidosis, dehydration, and electrolyte imbalances. According to the International Society for Pediatric and Adolescent Diabetes guidelines, severe diabetic ketoacidosis is characterized by a pH < 7.1 or bicarbonate < 5 mmol/L. This condition can lead to a wide range of life-threatening complications, including cerebral edema that represents the leading cause of death. Several prevention strategies, including awareness campaigns, early diagnosis of diabetes, regular monitoring and management, effective insulin therapy, education, access to healthcare and technological assistance, may contribute to reduce the risk of severe diabetic ketoacidosis episodes in children and adolescents.

The temporal relationship between mitochondrial quality and renal tissue recovery following ischemia-reperfusion injury

Background

Growing evidence indicates that disruptions in mitochondrial quality management contribute to the development of acute kidney injury (AKI), incomplete or maladaptive kidney repair, and chronic kidney disease. However, the temporal dynamics of mitochondrial quality control alterations in relation to renal injury and its recovery remain poorly understood and are addressed in this manuscript.

Method

ology: Male Wistar rats (n = 60) were subjected to varying durations of ischemia and reperfusion. Ischemia was instigated by clamping both renal arteries and for reperfusion, the clamps were removed to restore the blood flow. Renal injury, physiological function, mitochondrial assessment, and cellular mediators were analyzed.

Results

Prolonging ischemia duration reduces bioenergetic function while disrupting the balance of mitochondrial fusion, fission, and mitophagy at the gene expression level while maintaining intact mitochondrial copy number. However, reperfusing a kidney after 45 min of ischemia with varying reperfusion times exacerbates mitochondrial dysfunction and significantly decreases mitochondrial copy number. These declines are particularly evident at 24 h of reperfusion, with some parameters improving by 7 days of reperfusion. Despite these improvements, 7 days of reperfusion did not correlate with renal injury indicators (CrCl- 0.46 ± 0.01, BUN-86.29 ± 4.9, Cr-1.75 ± 0.16) following 45 min of ischemia. Conversely, 15 min of ischemia followed by 7 days of reperfusion restored mitochondrial quality and renal function (CrCl- 7.33 ± 0.59, BUN-43.6 ± 3.16, Cr-0.93 ± 0.14).

Conclusion

The above findings emphasize that mitochondrial quality control alters with the extent of ischemia and subsequent reperfusion time, impacting not only mitochondrial copy number but also the resilience of mitochondria during tissue repair.

Leucine-rich alpha-2-glycoprotein 1 deficiency suppresses ischemia-reperfusion injury-induced renal fibrosis

Ischemia reperfusion injury (IRI) is a major cause of acute kidney injury (AKI) and ultimately leads to renal fibrosis, primarily via the transforming growth factor-β (TGF-β) pathway. Leucine-rich alpha-2-glycoprotein 1 (LRG1), a novel modulator of the TGF-β pathway, has been implicated in the modulation of renal fibrosis by affecting the TGF-β/Smad3 signaling axis. However, the role of LRG1 in the transition from AKI to chronic kidney disease (CKD) remains unclear. This study aimed to investigate the functional role of LRG1 during the remodeling phase post-IRI. Unilateral IRI was induced in C57BL/6J wild-type (WT) mice and systemic LRG1 knockout (KO) mice. In C57BL/6J WT mice, renal LRG1 mRNA expression was significantly elevated on the ischemia/reperfusion side compared to the sham side over a 28-day period. In contrast, LRG1 KO mice demonstrated significantly reduced renal fibrosis compared to WT mice on postoperative day 28. Additionally, renal mRNA expression of TGF-β and associated pro-fibrotic genes was diminished in LRG1 KO mice compared to WT mice. Consequently, LRG1 KO mice exhibited attenuated IRI-induced chronic fibrosis. These findings indicate that LRG1 is involved in the pathogenesis of the transition from AKI to CKD and may be a potential therapeutic target.

Circadian Clock Gene Bmal1: A Molecular Bridge from AKI to CKD

Acute kidney injury (AKI) and chronic kidney disease (CKD) represent two frequently observed clinical conditions. AKI is characterized by an abrupt decrease in glomerular filtration rate (GFR), generally associated with elevated serum creatinine (sCr), blood urea nitrogen (BUN), and electrolyte imbalances. This condition usually persists for approximately a week, causing a transient reduction in kidney function. If these abnormalities continue beyond 90 days, the condition is redefined as chronic kidney disease (CKD) or may advance to end-stage renal disease (ESRD). Recent research increasingly indicates that maladaptive repair mechanisms after AKI significantly contribute to the development of CKD. Thus, implementing early interventions to halt the progression from AKI to CKD has the potential to markedly improve patient outcomes. Although considerable research has been conducted, the exact mechanisms linking AKI to CKD are complex, and effective treatments remain limited. Kidney function is influenced by circadian rhythms, with the circadian gene Bmal1 being vital in managing these cycles. Recent research indicates that Bmal1 is significantly involved in the progression of both AKI and CKD. In this study, we conducted a retrospective analysis of Bmal1's role in AKI and CKD, reviewed recent research advancements, and investigated how Bmal1 influences the pathological mechanisms underlying the progression from AKI to CKD. Additionally, we highlighted gaps in the existing research and examined the potential of Bmal1 as a therapeutic target in kidney disease management. This work aims to provide meaningful insights for future studies on the role of the circadian gene Bmal1 in the transition from AKI to CKD, with the goal of identifying therapeutic approaches to mitigate kidney disease progression.

Association between frailty and acute kidney injury after cardiac surgery: unraveling the moderation effect of body fat through an international, retrospective, multicohort study

BACKGROUND

Acute kidney injury (AKI) is a common and serious complication after cardiac surgery that significantly affects patient outcomes. Given the limited treatment options available, identifying modifiable risk factors is critical. Frailty and obesity, two heterogeneous physiological states, have significant implications for identifying and preventing AKI. Our study investigated the interplay among frailty, body composition, and AKI risk after cardiac surgery to inform patient management strategies.

MATERIAL AND METHODS

This retrospective cohort study included three international cohorts. Primary analysis was conducted on adult patients who underwent cardiac surgery between 2014 and 2019 at Wuhan Union Hospital, China. We tested the generalizability of our findings with data from two independent international cohorts, the Medical Information Mart for Intensive Care IV (MIMIC-IV) and the eICU Collaborative Research Database. Frailty was assessed using a clinical lab-based frailty index (FI-LAB), while total body fat percentage (BF%) was calculated based on a formula accounting for BMI, sex, and age. Logistic regression models were used to analyze the associations between frailty, body fat, and AKI, adjusting for pertinent covariates.

RESULTS

A total of 8785 patients across three international cohorts were included in the study. In the primary analysis of 3569 patients from Wuhan Union Hospital, moderate and severe frailty were associated with an increased AKI risk after cardiac surgery. Moreover, a nonlinear relationship was observed between BF% and AKI risk. When stratified by the degree of frailty, lower body fat correlated with a decreased incidence of AKI. Extended analyses using the MIMIC-IV and eICU cohorts ( n =3951 and n =1265, respectively) validated these findings and demonstrated that a lower total BF% was associated with decreased AKI incidence. Moderation analysis revealed that the effect of frailty on AKI risk was moderated by the BF%. Sensitivity analyses demonstrated results consistent with the main analyses.

CONCLUSION

Higher degrees of frailty were associated with an elevated risk of AKI following cardiac surgery, and total BF% moderated this relationship. This research underscores the significance of integrating frailty and body fat assessments into routine cardiovascular care to identify high-risk patients for AKI and implement personalized interventions to improve patient outcomes.

The Metabolism of Creatinine and Its Usefulness to Evaluate Kidney Function and Body Composition in Clinical Practice

Serum creatinine levels are the most used clinical marker to estimate renal function as the glomerular function rate because it is simple, fast, and inexpensive. However, creatinine has limitations, as its levels can be influenced by factors such as advanced age, physical activity, protein-rich diets, male gender, medications, and ethnicity. Serum cystatin C and its combination with serum creatinine may serve as an alternative since these factors do not affect it. Most creatinine synthesis occurs in the muscles, making it a valuable marker for assessing lean body mass within body composition. This measurement is crucial for evaluating and monitoring nutritional status in patients with chronic kidney disease. This review aimed to discuss the literature on creatinine metabolism, its advantages and disadvantages in assessing renal function, and its utility in measuring lean body mass. The variability in the creatinine generation rate among individuals should be considered when assessing the glomerular function rate.

Combined extracts of Curcuma longa and Curcuma zedoaria ameliorates cisplatin-induced kidney damage in rats

Background

Cisplatin (CIS) is a highly effective chemotherapeutic drug. However, it is associated with various side effects, including kidney damage, due to its nephrotoxic properties.

Aim

This study aimed to evaluate the renoprotective potential of the combined extract of Curcuma longa and Curcuma zedoaria in reducing nephrotoxicity by examining its effects on tumor necrosis factor-alpha (TNF-α), KIM-1, and caspase-3 levels.

Methods

Twenty-five rats were divided into normal control groups (NS), CIS control groups, and three treatment groups that received doses of the combined extract at 100, 200, and 400 mg/kg (CUR100, CUR200, and CUR400), respectively, on day 1-20. All groups, except the NS group (receiving normal saline i.p.), received intraperitoneal CIS (1 mg/kg) on days 7 and 14 of the 20-day extract treatment.

Results

Compared with the rats in the CIS group, rats given the combined extract had a considerable gain in body weight and decreased TNF-α, KIM-1, and caspase-3 expression levels. Histopathological examination revealed that the extract group experienced less kidney damage than the CIS group. The combined extract, administered at 200 mg/kg, exerted the most apparent protective effect, decreasing renal TNF-α, KIM-1, and caspase 3.

Conclusion

The combined extract of C. longa and C. zedoaria has the potential to be a therapeutic agent for reducing nephrotoxicity by suppressing TNF-α, KIM-1, and caspase-3 levels. Further research is required to determine the potential of this combination therapy in humans.

Epigenetic therapeutics attenuate kidney injury and fibrosis by restoring the expression of epigenetically reprogrammed fibrogenic genes and signaling pathways

Kidney fibrosis is a commonly observed pathological condition during development of chronic kidney disease. Therapeutic options currently available are effective only in slowing the progression of kidney fibrosis and there is no cure for this disease. Aberrant expression and excessive accumulation of extracellular matrix (ECM) proteins in the peritubular space is a characteristic pathological feature of fibrotic kidney. However, the molecular basis of aberrant regulation of fibrotic genes in kidneys is not clear. In this context, this study aimed to evaluate the role of epigenetic reprogramming in kidney fibrosis. Folic acid (FA)-induced acute kidney injury (AKI) and kidney fibrosis in mice as an in vivo model and long-term arsenic or FA-exposed fibrogenic HK-2 cells as an in vitro model were used to evaluate the role of DNA methylation and histone modifications in fibrosis. DNA demethylating agent 5aza2 deoxycytidine (5-aza-2-dC) and histone deacetylase inhibitor Trichostatin A (TSA) were used to treat FA-injected mice. Results of histopathological and immunofluorescence staining of kidney tissue, serum albumin- creatinine levels, body weight, and gene expression analysis revealed significant protective effects of 5-aza-2-dC and TSA in FA-induced AKI and fibrosis. Insignificant change in the expression of N-cadherin whereas a significant decrease in E-cadherin as well as an increase in the expression of Vimentin and α-SMA suggest partial EMT associated with fibrosis. Aberrant expression of epithelial-mesenchymal-transition (EMT) and ECM-regulators (MMP2, Smad7, and TIMP3) as well as fibrogenic signaling pathways (Notch, TGF-beta, and Wnt signaling), and their restoration by 5-aza-2-dC and TSA treatments suggest epigenetic reprogramming of these genes and signaling pathways during FA-induced fibrosis. In summary, this study provides new information on the role of epigenetic reprogramming of fibrogenic genes and signaling pathways during the development of kidney fibrosis. Attenuation of fibrosis after 5-aza-2-dC and TSA treatments suggest the promise of these epigenetic-based therapeutics in the clinical management of this disease.

Combined extracts of Curcuma longa and Curcuma zedoaria ameliorates cisplatin-induced kidney damage in rats

Background

Cisplatin (CIS) is a highly effective chemotherapeutic drug. However, it is associated with various side effects, including kidney damage, due to its nephrotoxic properties.

Aim

This study aimed to evaluate the renoprotective potential of the combined extract of Curcuma longa and Curcuma zedoaria in reducing nephrotoxicity by examining its effects on tumor necrosis factor-alpha (TNF-α), KIM-1, and caspase-3 levels.

Methods

Twenty-five rats were divided into normal control groups (NS), CIS control groups, and three treatment groups that received doses of the combined extract at 100, 200, and 400 mg/kg (CUR100, CUR200, and CUR400), respectively, on day 1-20. All groups, except the NS group (receiving normal saline i.p.), received intraperitoneal CIS (1 mg/kg) on days 7 and 14 of the 20-day extract treatment.

Results

Compared with the rats in the CIS group, rats given the combined extract had a considerable gain in body weight and decreased TNF-α, KIM-1, and caspase-3 expression levels. Histopathological examination revealed that the extract group experienced less kidney damage than the CIS group. The combined extract, administered at 200 mg/kg, exerted the most apparent protective effect, decreasing renal TNF-α, KIM-1, and caspase 3.

Conclusion

The combined extract of C. longa and C. zedoaria has the potential to be a therapeutic agent for reducing nephrotoxicity by suppressing TNF-α, KIM-1, and caspase-3 levels. Further research is required to determine the potential of this combination therapy in humans.

The Kidney Precision Medicine Project and Single-Cell Biology of the Injured Proximal Tubule

Single-cell RNA sequencing (scRNA-seq) has led to major advances in our understanding of proximal tubule subtypes in health and disease. The proximal tubule serves essential functions in overall homeostasis, but pathologic or physiological perturbations can affect its transcriptomic signature and corresponding tasks. These alterations in proximal tubular cells are often described within a scRNA-seq atlas as cell states, which are pathophysiological subclassifications based on molecular and morphologic changes in a cell's response to that injury compared with its native state. This review describes the major cell states defined in the Kidney Precision Medicine Project's scRNA-seq atlas. It then identifies the overlap between the Kidney Precision Medicine Project and other seminal works that may use different nomenclature or cluster proximal tubule cells at different resolutions to define cell state subtypes. The goal is for the reader to understand the key transcriptomic markers of important cellular injury and regeneration processes across this highly dynamic and evolving field.

miRNA and mRNA Signatures in Human Acute Kidney Injury Tissue

Acute kidney injury (AKI) is an important contributor to the development of chronic kidney disease (CKD). There is a need to understand molecular mediators that drive recovery and progression to CKD. In particular, the regulatory role of miRNAs in AKI is poorly understood. Herein, miRNA and mRNA sequencing were performed on biobanked human kidney tissues obtained during the routine care of subjects with a diagnosis of AKI, minimal change disease, or on nephrectomy tissue with no known kidney disease. mRNA analysis revealed that nephrectomy tissues exhibited an injury signature similar to that of AKI which was not identified in minimal change disease samples. The transcriptomic signature of human AKI was enriched in pathways involved in cell adhesion, epithelial-to-mesenchymal transition, and cell cycle arrest (eg, CDH6, ITGB6, CDKN1A). In AKI, up-regulation of miR-146a, miR-155, miR-142, and miR-122 was associated with pathways involved in immune cell recruitment, inflammation, and epithelial-to-mesenchymal transition. miR-122 and miR-146 were associated with down-regulation of DDR2 and IGFBP6, which are genes involved in the recovery and progression of kidney disease. These data provide integrated miRNA signatures that complement mRNA and other epigenetic data available in kidney atlases.

Nrf2 inhibits M1 macrophage polarization to ameliorate renal ischemia-reperfusion injury through antagonizing NF-κB signaling

Renal ischemia-reperfusion injury (IRI) is a condition that arises from a sudden interruption of the blood flow to the kidney for a period of time followed by restoration of the blood supply. This process contributes to acute kidney injury (AKI), increases morbidity and mortality, and is a major risk factor for chronic kidney disease (CKD). Nuclear factor erythroid-derived 2-like 2 (Nrf2) has been shown to exhibit strong anti-oxidative and anti-inflammatory effects, which are reciprocally regulated by the pro-inflammatory actions of nuclear factor-kappa B (NF-κB) signaling. In this study, we established a model of AKI caused by renal IRI in mice lacking the Nrf2 gene (KO-Nrf2) and mice pre-injected with ML385 (Nrf2 inhibitor). In addition, LPS- or IL-4-induced M1- or M2-type polarized macrophages (RAW264.7), respectively, were also treated with Nrf2 activation and inhibition. The results demonstrated a more pronounced activation of the NF-κB signaling pathway in the Nrf2 inhibition model, accompanied by a more severe inflammatory effect. In cultured macrophages and renal IRI mice, Nrf2 inhibition activated M1 macrophage polarization, thereby increasing the release of proinflammatory cell factors (iNOS and TNF-α) and aggravating renal IRI. Notably, the inhibitory effect of Nrf2 on M1 macrophage polarization was related to the downregulation of the NF-κB signaling pathway activity, resulting in partial relief of renal IRI. Consequently, our findings indicated that Nrf2 inhibits M1 macrophage polarization to ameliorate renal IRI through antagonizing NF-κB signaling. Targeted activation of Nrf2 may be one of the important strategies for renal IRI treatment.

Endothelial-specific deletion of connexin 43 improves renal function and structure after acute kidney injury

BACKGROUND

We have previously reported that the gap junction protein connexin 43 (Cx43) was upregulated in chronic renal disease in humans and rodents and plays a crucial role in the progression of experimental nephropathy. In this study, we investigated its role after renal ischemia/reperfusion (rIR), which is a major mechanism of injury in acute renal injury (AKI) and renal transplant graft dysfunction.

METHODS

Wild-type mice (WT) and mice in which Cx43 expression was genetically reduced by half (Cx43 ±) were unilaterally nephrectomized. The left renal artery was subsequently clamped, with reperfusion of varying duration. Mice with tubular- or endothelial-specific deletion of Cx43 were also used to assess the effect of this connexin in each cell type after rIR. Kidneys were assessed for histological evaluation, immunohistochemistry, and RT-PCR.

RESULTS

Blood urea nitrogen and creatininemia were progressively elevated in WT mice and picked up 48 h after rIR. At the same time point, severe tubular necrosis and dilation occurred in the cortico-medullary junction of the injured kidneys with accompanying massive neutrophil infiltration. Interestingly, Cx43 expression was progressively increased within the tubulointerstitial compartment during kidney damage progression and was paralleled closely by that of markers of renal dysfunction. Cx43 ± mice showed fewer tubular lesions, less inflammation, and further improved renal function. Similar results were observed in mice where Cx43 was specifically deleted within the vascular endothelium. In contrast, Cx43 deletion in renal tubules did not significantly improve renal structure and function after rIR.

CONCLUSION

Our findings suggest that endothelial Cx43 plays a crucial role in AKI.

Exploring Aquaporins in Human Studies: Mechanisms and Therapeutic Potential in Critical Illness

Aquaporins (AQPs) are membrane proteins facilitating water and other small solutes to be transported across cell membranes. They are crucial in maintaining cellular homeostasis by regulating water permeability in various tissues. Moreover, they regulate cell migration, signaling pathways, inflammation, tumor growth, and metastasis. In critically ill patients, such as trauma, sepsis, and patients with acute respiratory distress syndrome (ARDS), which are frequently encountered in intensive care units (ICUs), water transport regulation is crucial for maintaining homeostasis, as dysregulation can lead to edema or dehydration, with the latter also implicating hemodynamic compromise. Indeed, AQPs are involved in fluid transport in various organs, including the lungs, kidneys, and brain, where their dysfunction can exacerbate conditions like ARDS, acute kidney injury (AKI), or cerebral edema. In this review, we discuss the implication of AQPs in the clinical entities frequently encountered in ICUs, such as systemic inflammation and sepsis, ARDS, AKI, and brain edema due to different types of primary brain injury from a clinical perspective. Current and possible future therapeutic implications are also considered.

Chronic undernutrition impairs renal mitochondrial respiration accompanied by intense ultrastructural damage in juvenile rats

This study investigated whether chronic undernutrition alters the mitochondrial structure and function in renal proximal tubule cells, thus impairing fluid transport and homeostasis. We previously showed that chronic undernutrition downregulates the renal proximal tubules (Na++K+)ATPase, the main molecular machine responsible for fluid transport and ATP consumption. Male rats received a multifactorial deficient diet, the so-called Regional Basic Diet (RBD), mimicking those used in impoverished regions worldwide, from weaning to a juvenile age (3 months). The diet has a low content (8 %) of poor-quality proteins, low lipids, and no vitamins compared to control (CTR). We investigated citrate synthase activity, mitochondrial respiration (oxygraphy) in phosphorylating and non-phosphorylating conditions with different substrates/inhibitors, potential across the internal membrane (Δψ), and anion superoxide/H2O2 formation. The data were correlated with ultrastructural alterations evaluated using transmission electron microscopy (TEM) and focused ion beam scanning electron microscopy (FIB-SEM). Citrate synthase activity decreased (∼50 %) in RBD rats, accompanied by a similar reduction in respiration in non-phosphorylating conditions, maximum respiratory capacity, and ATP synthesis. The Δψ generation and its dissipation after carbonyl cyanide-4-(trifluoromethoxy) phenylhydrazone remained unmodified in the survival mitochondria. H2O2 production increased (∼100 %) after Complex II energization. TEM demonstrated intense matrix vacuolization and disruption of cristae junctions in a subpopulation of RBD mitochondria, which was also demonstrated in the 3D analysis of FIB-SEM tomography. In conclusion, chronic undernutrition impairs mitochondrial functions in renal proximal tubules, with profound alterations in the matrix and internal membrane ultrastructure that culminate with the compromise of ATP supply for transport processes.

Metabolic Syndrome Components and Its Impact on Acute Kidney Injury After Total Joint Arthroplasty

BACKGROUND

Metabolic syndrome (MetS) is an independent risk factor for postoperative complications. This study aimed to evaluate the associated risk of MetS for perioperative complications, especially urinary complications, in patients who underwent primary total knee arthroplasty (TKA) or total hip arthroplasty (THA).

METHODS

We used a publicly available all-payer administrative database to identify patients undergoing TKA and THA from 2016 to 2020. The primary exposure of interest was MetS. Multivariable adjusted models based on propensity score matching were used to evaluate the association of MetS components with acute kidney injury (AKI), urinary tract infection (UTI), and acute posthemorrhagic anemia (APHA) in patients who underwent TKA and THA. A counterfactual-based mediation analysis was conducted to investigate the mediating effect of APHA on the relationship between MetS and AKI.

RESULTS

The analysis included 2,097,940 (16.4% with MetS) THA and 3,073,310 (24.0% with MetS) TKA adult hospitalizations. Multivariable adjustment analysis indicated MetS was associated with an increased risk of AKI (odds ratio [OR] 1.78, 95% confidence interval [CI] 1.69 to 1.89 for THA; OR 1.88, 95% CI 1.79 to 1.96 for TKA), UTI (OR 1.13, 95% CI 1.03 to 1.23 for THA; OR 1.26, 95% CI 1.17 to 1.35 for TKA), and APHA (OR 1.17, 95% CI 1.14 to 1.20 for THA; OR 1.7, 95% CI 1.15 to 1.19 for TKA). The risk of AKI increased with the number of MetS components, with ORs ranging from 2.58 to 9.46 in TKA patients and from 2.22 to 5.75 in THA patients. This increase was particularly associated with diabetes and hypertension, which were the most significant associated risk factors. Furthermore, APHA mediated the association between MetS and AKI.

CONCLUSIONS

The prevalence of MetS is increasing in TKA and THA patients. Metabolic syndrome was associated with increased risk of AKI, UTI, and APHA. The risk of AKI increased with each additional MetS component, with diabetes and hypertension contributing most. In addition, APHA may play a partial mediating role in MetS-induced AKI.

New approaches to acute kidney injury

Acute kidney injury (AKI) is a common and serious clinical syndrome that involves complex interplay between different cellular, molecular, metabolic and immunologic mechanisms. Elucidating these pathophysiologic mechanisms is crucial to identify novel biomarkers and therapies. Recent innovative methodologies and the advancement of existing technologies has accelerated our understanding of AKI and led to unexpected new therapeutic candidates. The aim of this review is to introduce and update the reader about recent developments applying novel technologies in omics, imaging, nanomedicine and artificial intelligence to AKI research, plus to provide examples where this can be translated to improve patient care.

Acute toxicity effects of ethylene glycol on lethal dose 50 (LD50), urine production, and histopathology change renal tubule cell in mice

Background

The LD50 (lethal dose causing 50% mortality) of ethylene glycol (EG) and its associated toxicity in mice (Mus musculus) were assessed by evaluating kidney function.

Aim

This study aimed to determine the acute toxicity of an oral lethal dose of 50% (LD50) of EG, also degeneration, necrosis, and inflammatory cell invasion in kidney tubules of male rats (Rattus norvegicus) as an animal model.

Methods

There were 66 DDG (Deutschland Denken Yoken) mice in 11 groups of six in this investigation. The daylong metabolic cage study contained one control (C) and 10 treatment groups that received different EG doses. EG's daily BW/kg dosage varied from 0.5 mg/kg to 15,000 mg/kg. The treatment group was given a single dose of EG at a dose of T1 = 0.5 mg/kg BW, T2 = 1.57 mg/kg BW, T3 = 4.94 mg/kg BW, T4 = 15.54 mg/kg BW, T5 = 48.84 mg/kg BW, T6 = 153.55 mg/kg BW, T7 = 482.74 mg/kg BW, and T8 = 1517.66 mg/kg BW T9 = 4771.24 mg/kg BW, T10 = 14999.99 ≈ 15. 000 mg/kg BW. One-way Analysis of Variance testing was used to analyze the data.

Results

The LD50 value of EG in mice was determined to be 1.598 mg/kg BW, classifying EG as "Slightly Toxic." According to renal histopathology, EG dosage increased renal tubular degeneration, necrosis, and interstitial inflammatory cell infiltration. Acute renal impairment and lower urine output were observed in the EG (4.94 mg/kg-1517.66 mg/kg BW). Histologically, EG levels are associated with renal tubular cell degeneration, necrosis, and interstitial inflammatory cell growth.

Conclusion

Acute EG exposure caused renal failure in male mice. Acute exposure to EG causes renal tubular cell degeneration and inflammation, indicating toxicity and health hazards.

Role of miRNAs in macrophage-mediated kidney injury

Macrophages, crucial components of the human immune system, can be polarized into M1/M2 phenotypes, each with distinct functions and roles. Macrophage polarization has been reported to be significantly involved in the inflammation and fibrosis observed in kidney injury. MicroRNA (miRNA), a type of short RNA lacking protein-coding function, can inhibit specific mRNA by partially binding to its target mRNA. The intricate association between miRNAs and macrophages has been attracting increasing interest in recent years. This review discusses the role of miRNAs in regulating macrophage-mediated kidney injury. It shows how miRNAs can influence macrophage polarization, thereby altering the biological function of macrophages in the kidney. Furthermore, this review highlights the significance of miRNAs derived from exosomes and extracellular vesicles as a crucial mediator in the crosstalk between macrophages and kidney cells. The potential of miRNAs as treatment applications and biomarkers for macrophage-mediated kidney injury is also discussed.

Renal implications of pneumoperitoneum in laparoscopic surgery: mechanisms, risk factors, and preventive strategies

Pneumoperitoneum, which is established for laparoscopic surgery, has systemic implications on the renal system and may contribute to acute kidney injury or postoperative renal dysfunction. Specifically, when the pressure exceeds 10 mmHg, pneumoperitoneum decreases renal blood flow, leading to renal dysfunction and temporary oliguria. The renal effects of pneumoperitoneum stem from both the direct effects of increased intra-abdominal pressure and indirect factors such as carbon dioxide absorption, neuroendocrine influences, and tissue damage resulting from oxidative stress. While pneumoperitoneum can exacerbate renal dysfunction in patients with pre-existing kidney issues, preserving the function of the remaining kidney is crucial in certain procedures such as laparoscopic live donor nephrectomy. However, available evidence on the effects of pneumoperitoneum on renal function is limited and of moderate quality. This review focuses on exploring the pathophysiological hypotheses underlying kidney damage, mechanisms leading to oliguria and kidney damage, and fluid management strategies for surgical patients during pneumoperitoneum.