Inflammation in AKI: Current Understanding, Key Questions, and Knowledge Gaps

Prognostic value of neutrophil-to-lymphocyte ratio dynamics in patients with septic acute kidney injury: a cohort study

BACKGROUND

Neutrophil-to-lymphocyte ratio (NLR) has been suggested to be a prognostic marker for various diseases, but whether NLR dynamics (ΔNLR) is related to mortality and disease severity in patients with septic acute kidney injury (AKI) has not been determined.

METHODS

Between August 2013 and August 2021, septic AKI patients at our center were retrospectively enrolled. ΔNLR was defined as the difference between the NLR at septic AKI diagnosis and at hospital admission. The relationship between the ΔNLR and mortality was evaluated by Kaplan-Meier curves, Cox proportional hazards, and cubic spline analyses. The prediction values were compared by area under the receiver-operating characteristic curve (AUROC), net reclassification improvement (NRI), and integrated discrimination improvement (IDI) analyses.

RESULTS

Of the 413 participants, the mean age was 63 ± 17 years, and 134 were female (32.4%). According to the median value, patients in the high-ΔNLR group had significantly greater 90-d mortality (74.4% vs. 46.6%, p < 0.001). After adjustment for potential confounders, high ΔNLR remained an independent predictor of 90-d mortality (HR = 2.80; 95% CI = 1.74-4.49, p < 0.001). Furthermore, ΔNLR had the highest AUROC for 90-d mortality (0.685) among the various biomarkers and exhibited an improved NRI (0.314) and IDI (0.027) when incorporated with PCT and CRP. For secondary outcomes, patients with high ΔNLR had increased risk of 30-d mortality (p = 0.004), need for renal replacement therapy (p = 0.011), and developing stage-3 AKI (p = 0.040) according to the adjusted models.

CONCLUSIONS

High ΔNLR is independently associated with increased risk of patient mortality and adverse outcomes. ΔNLR might be utilized to facilitate risk stratification and optimize septic AKI management.

Monocytes to lymphocytes multiplying platelets ratio as an early indicator of acute kidney injury in cardiac surgery with cardiopulmonary bypass: a retrospective analysis

OBJECTIVE

The monocyte-to-lymphocyte multiplying platelets ratio (MLPR) is a novel systemic inflammatory marker, deriving from the monocyte-to-lymphocyte ratio (MLR). However, the link between MLPR and acute kidney injury following cardiac surgery (CSA-AKI) with cardiopulmonary bypass (CPB) has not been investigated yet. We comprehensively explored the potential linear and nonlinear relationship between MLPR or MLR and CSA-AKI.

METHODS

Data of patients who underwent cardiac surgery with CPB between December 2018 and April 2021 were retrospectively collected at Fuwai Hospital, Beijing, China. MLPR was defined as monocyte count (×109/L) × 1000/(lymphocyte count (×109/L) × platelets (×109/L)). MLR was defined as monocyte count (×109/L)/lymphocyte count (×109/L). Logistic regression and restricted cubic spline (RCS) were used for linear and nonlinear analysis. The primary outcome was postoperative AKI within 48 h of after cardiac surgery.

RESULTS

Of the 2420 patients screened, 2387 eligible patients were enrolled in the final analysis; the mean age was 54.7 years, and 1501 [62.9%] were men. The incidence of AKI was 25.8%. Logistic regression showed that MLPR (odds ratio [OR] = 1.31, 95% confidence interval [CI]: 1.16-1.48, p < .001) and MLR (OR = 3.06, 95% CI: 1.29-7.29, p = .012) were independent risk factors for AKI. Moreover, in the RCS model with adjustment for age (median: 56), female sex, and history of diabetes, a significant statistical difference was detected between preoperative MLPR, MLR, and AKI (p for non-linearity <.001). The subgroup analyses revealed similar results.

CONCLUSIONS

The study revealed a nonlinear relationship between MLPR and MLR with AKI. MLPR exhibited a J-shaped curve, and MLR showed a favorable S-shaped curve in relation to AKI. Particularly, MLPR emerges as a promising clinical composite index for early CSA-AKI prediction. These findings emphasize the significance of MLPR as a valuable tool in clinical practice for timely identification and management of CSA-AKI.

Association Between Inflammatory Biomarkers and Contrast-induced Acute Kidney Injury in ACS Patients Undergoing Percutaneous Coronary Intervention: A Cross-sectional Study

The present study aimed to evaluate the predictive role of inflammatory biomarkers in the development of contrast-induced acute kidney injury (CI-AKI) in acute coronary syndrome (ACS) patients undergoing percutaneous coronary intervention (PCI). The inflammatory biomarkers assessed were: platelet-to-lymphocyte ratio (PLR), monocyte-to-lymphocyte ratio (MLR), neutrophil-to-lymphocyte ratio (NLR), derived neutrophil-to-lymphocyte ratio (dNLR), neutrophil-to-lymphocyte*platelet ratio (NLPR), systemic inflammatory index (SII), and systemic inflammation response index (SIRI). Overall, 950 patients undergoing PCI were enrolled. The frequency of CI-AKI was 15.2% (n = 144). The levels of NLR, MLR, NLPR, SII, and SIRI were higher in the CI-AKI group than in the Non-CI-AKI group (P < .05). The addition of NLR ≥2.96, dNLR ≥2.08, NLPR ≥.012, SII ≥558.04, and SIRI ≥1.13 to the Mehran score model significantly increased the area under the curve (P < .05). Multivariable logistic regression analyses indicated that inflammatory biomarkers were significantly associated with CI-AKI, including NLR ≥2.96 (OR = 1.588, P = .017), dNLR ≥2.08 (OR = 1.686, P = .007), SII ≥558.04 (OR = 1.521, P = .030), and SIRI ≥1.13 (OR = 1.601, P = .017). Therefore, inflammation is associated with the development of CI-AKI, and preoperative hematological inflammatory markers could predict the risk of CI-AKI in ACS patients undergoing PCI.

Natural polysaccharides as promising reno-protective agents for the treatment of various kidney injury

Renal injury, a prevalent clinical outcome with multifactorial etiology, imposes a substantial burden on society. Currently, there remains a lack of effective management and treatments. Extensive research has emphasized the diverse biological effects of natural polysaccharides, which exhibit promising potential for mitigating renal damage. This review commences with the pathogenesis of four common renal diseases and the shared mechanisms underlying renal injury. The renoprotective roles of polysaccharides in vivo and in vitro are summarized in the following five aspects: anti-oxidative stress effects, anti-apoptotic effects, anti-inflammatory effects, anti-fibrotic effects, and gut modulatory effects. Furthermore, we explore the structure-activity relationship and bioavailability of polysaccharides in relation to renal injury, as well as investigate their utility as biomaterials for alleviating renal injury. The clinical experiments of polysaccharides applied to patients with chronic kidney disease are also reviewed. Broadly, this review provides a comprehensive perspective on the research direction of natural polysaccharides in the context of renal injury, with the primary aim to serve as a reference for the clinical development of polysaccharides as pharmaceuticals and prebiotics for the treatment of kidney diseases.

Association between lactate dehydrogenase to albumin ratio and acute kidney injury in patients with sepsis: a retrospective cohort study

BACKGROUND

Serum lactate dehydrogenase to albumin ratio (LAR) is associated with poor outcomes in malignancy and pneumonia. However, there are few studies suggesting that LAR is associated with the occurrence of acute kidney injury (AKI) in patients with sepsis, which was investigated in this study.

METHODS

We conducted a retrospective cohort study based on the Medical Information Mart for Intensive Care (MIMIC)-IV database. The primary outcome was the occurrence of AKI within 2 days and 7 days. Multivariable logistic regression models were used to calculate odds ratios to validate the association between LAR and AKI, in-hospital mortality, RRT use, and recovery of renal function, respectively.

RESULTS

A total of 4010 participants were included in this study. The median age of the participants was 63.5 years and the median LAR was 10.5. After adjusting for confounding variables, patients in the highest LAR quartile had a higher risk of AKI than those in the lowest LAR quartile within 2 days and 7 days, with odds ratios of 1.37 (95% confidence interval [CI]: 1.23-1.52) and 1.95 (95% CI: 1.72-2.22), respectively. The adjusted odds of AKI within 2 and 7 days were 1.16 (95% CI: 1.12-1.20) and 1.29 (95% CI: 1.24-1.35) for each 1 unit increase in LAR(log2), respectively.

CONCLUSION

This study demonstrated that elevated LAR was associated with poor prognosis in patients with sepsis. The risk of AKI and in-hospital mortality increased, the need for RRT increased, and the chance of recovery of renal function decreased with the increase of LAR.

Metabolic reprogramming in septic acute kidney injury: pathogenesis and therapeutic implications

Acute kidney injury (AKI) is a frequent and severe complication of sepsis and is characterized by significant mortality and morbidity. However, the pathogenesis of septic acute kidney injury (S-AKI) remains elusive. Metabolic reprogramming, which was originally referred to as the Warburg effect in cancer, is strongly related to S-AKI. At the onset of sepsis, both inflammatory cells and renal parenchymal cells, such as macrophages, neutrophils and renal tubular epithelial cells, undergo metabolic shifts toward aerobic glycolysis to amplify proinflammatory responses and fortify cellular resilience to septic stimuli. As the disease progresses, these cells revert to oxidative phosphorylation, thus promoting anti-inflammatory reactions and enhancing functional restoration. Alterations in mitochondrial dynamics and metabolic reprogramming are central to the energetic changes that occur during S-AKI. In this review, we summarize the current understanding of the pathogenesis of metabolic reprogramming in S-AKI, with a focus on each cell type involved. By identifying relevant key regulatory factors, we also explored potential metabolic reprogramming-related therapeutic targets for the management of S-AKI.

Macrophage autophagy protects against acute kidney injury by inhibiting renal inflammation through the degradation of TARM1

Macroautophagy/autophagy activation in renal tubular epithelial cells protects against acute kidney injury (AKI). However, the role of immune cell autophagy, such as that involving macrophages, in AKI remains unclear. In this study, we discovered that macrophage autophagy was an adaptive response during AKI as mice with macrophage-specific autophagy deficiency (atg5-/-) exhibited higher serum creatinine, more severe renal tubule injury, increased infiltration of ADGRE1/F4/80+ macrophages, and elevated expression of inflammatory factors compared to WT mice during AKI induced by either LPS or unilateral ischemia-reperfusion. This was further supported by adoptive transfer of atg5-/- macrophages, but not WT macrophages, to cause more severe AKI in clodronate liposomes-induced macrophage depletion mice. Similar results were also obtained in vitro that bone marrow-derived macrophages (BMDMs) lacking Atg5 largely increased pro-inflammatory cytokine expression in response to LPS and IFNG. Mechanistically, we uncovered that atg5 deletion significantly upregulated the protein expression of TARM1 (T cell-interacting, activating receptor on myeloid cells 1), whereas inhibition of TARM1 suppressed LPS- and IFNG-induced inflammatory responses in atg5-/- RAW 264.7 macrophages. The E3 ubiquitin ligases MARCHF1 and MARCHF8 ubiquitinated TARM1 and promoted its degradation in an autophagy-dependent manner, whereas silencing or mutation of the functional domains of MARCHF1 and MARCHF8 abolished TARM1 degradation. Furthermore, we found that ubiquitinated TARM1 was internalized from plasma membrane into endosomes, and then recruited by the ubiquitin-binding autophagy receptors TAX1BP1 and SQSTM1 into the autophagy-lysosome pathway for degradation. In conclusion, macrophage autophagy protects against AKI by inhibiting renal inflammation through the MARCHF1- and MARCHF8-mediated degradation of TARM1.

Total Synthesis and Anti-inflammatory Activity of Asperjinone and Asperimide C

Total syntheses of two γ-butenolide natural products, asperjinone (1) and asperimide C (2) in both racemic and chiral forms have been accomplished utilizing Basavaiah's one-pot Friedel-Crafts/maleic anhydride formation protocol as a key strategy. Our syntheses verified the revised structure of 1 proposed by Williams et al. and the structure and absolute configuration of 2 reported by the Li group. This work also discloses the unprecedented anti-inflammatory activity of 1. Synthetic 1 exhibited significant anti-inflammatory activity in renal proximal tubular epithelial cells (RPTEC) by suppression of gene expression of pro-inflammatory cytokines TNF-α, IL-1β and IL-6 under LPS-induced renal inflammation condition and was superior to (S)-1, rac-2, 2, and a positive drug control, indomethacin. Moreover, compound 1 inhibited downstream signaling of inflammation by significantly reducing iNOS and COX-2 gene expression and total NO production. The anti-inflammatory activity of asperjinone (1) renders it a potential and promising candidate for developing novel anti-inflammatory agents against inflammation worsening acute kidney injury.

Identification of a Novel ECM Remodeling Macrophage Subset in AKI to CKD Transition by Integrative Spatial and Single-Cell Analysis

The transition from acute kidney injury (AKI) to chronic kidney disease (CKD) is a critical clinical issue. Although previous studies have suggested macrophages as a key player in promoting inflammation and fibrosis during this transition, the heterogeneity and dynamic characterization of macrophages are still poorly understood. Here, we used integrated single-cell RNA sequencing and spatial transcriptomic to characterize the spatiotemporal heterogeneity of macrophages in murine AKI-to-CKD model of unilateral ischemia-reperfusion injury. A marked increase in macrophage infiltration at day 1 was followed by a second peak at day 14 post AKI. Spatiotemporal profiling revealed that injured tubules and macrophages co-localized early after AKI, whereas in late chronic stages had spatial proximity to fibroblasts. Further pseudotime analysis revealed two distinct lineages of macrophages in this transition: renal resident macrophages differentiated into the pro-repair subsets, whereas infiltrating monocyte-derived macrophages contributed to chronic inflammation and fibrosis. A novel macrophage subset, extracellular matrix remodeling-associated macrophages (EAMs) originating from monocytes, linked to renal fibrogenesis and communicated with fibroblasts via insulin-like growth factors (IGF) signalling. In sum, our study identified the spatiotemporal dynamics of macrophage heterogeneity with a unique subset of EAMs in AKI-to-CKD transition, which could be a potential therapeutic target for preventing CKD development.

Single-Cell Analysis Provides New Insights into the Roles of Tertiary Lymphoid Structures and Immune Cell Infiltration in Kidney Injury and Chronic Kidney Disease

Chronic kidney disease (CKD) is a global health concern with high morbidity and mortality. Acute kidney injury (AKI) is a pivotal risk factor for the progression of CKD, and the rate of AKI-to-CKD progression increases with aging. Intrarenal inflammation is a fundamental mechanism underlying AKI-to-CKD progression. Tertiary lymphoid structures (TLSs), ectopic lymphoid aggregates formed in nonlymphoid organs, develop in aged injured kidneys, but not in young kidneys, with prolonged inflammation and maladaptive repair, which potentially exacerbates AKI-to-CKD progression in aged individuals. Dysregulated immune responses are involved in the pathogenesis of various kidney diseases, such as IgA nephropathy, lupus nephritis, and diabetic kidney diseases, thereby deteriorating kidney function. TLSs also develop in several kidney diseases, including transplanted kidneys and renal cell carcinoma. However, the precise immunologic mechanisms driving AKI-to-CKD progression and development of these kidney diseases remain unclear, which hinders the development of novel therapeutic approaches. This review aims to describe recent findings from single-cell analysis of cellular heterogeneity and complex interactions among immune and renal parenchymal cells, which potentially contribute to the pathogenesis of AKI-to-CKD progression and other kidney diseases, highlighting the mechanisms of formation and pathogenic roles of TLSs in aged injured kidneys.

Lymphocytes and innate immune cells in acute kidney injury and repair

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

Sirtuin 3 in renal diseases and aging: From mechanisms to potential therapies

The longevity protein sirtuins (SIRTs) belong to a family of nicotinamide adenine dinucleotide (NAD+)-dependent deacetylases. In mammals, SIRTs comprise seven members (SIRT1-7) which are localized to different subcellular compartments. As the most prominent mitochondrial deacetylases, SIRT3 is known to be regulated by various mechanisms and participate in virtually all aspects of mitochondrial homeostasis and metabolism, exerting significant impact on multiple organs. Notably, the kidneys possess an abundance of mitochondria that provide substantial energy for filtration and reabsorption. A growing body of evidence now supports the involvement of SIRT3 in several renal diseases, including acute kidney injury, chronic kidney disease, and diabetic nephropathy; notably, these diseases are all associated with aging. In this review, we summarize the emerging role of SIRT3 in renal diseases and aging, and highlights the intricate mechanisms by which SIRT3 exerts its effects. In addition, we highlight the potential therapeutic significance of modulating SIRT3 and provide valuable insights into the therapeutic role of SIRT3 in renal diseases to facilitate clinical application.

Galectin-8 counteracts folic acid-induced acute kidney injury and prevents its transition to fibrosis

Acute kidney injury (AKI), characterized by a sudden decline in kidney function involving tubular damage and epithelial cell death, can lead to progressive tissue fibrosis and chronic kidney disease due to interstitial fibroblast activation and tissue repair failures that lack direct treatments. After an AKI episode, surviving renal tubular cells undergo cycles of dedifferentiation, proliferation and redifferentiation while fibroblast activity increases and then declines to avoid an exaggerated extracellular matrix deposition. Appropriate tissue recovery versus pathogenic fibrotic progression depends on fine-tuning all these processes. Identifying endogenous factors able to affect any of them may offer new therapeutic opportunities to improve AKI outcomes. Galectin-8 (Gal-8) is an endogenous carbohydrate-binding protein that is secreted through an unconventional mechanism, binds to glycosylated proteins at the cell surface and modifies various cellular activities, including cell proliferation and survival against stress conditions. Here, using a mouse model of AKI induced by folic acid, we show that pre-treatment with Gal-8 protects against cell death, promotes epithelial cell redifferentiation and improves renal function. In addition, Gal-8 decreases fibroblast activation, resulting in less expression of fibrotic genes. Gal-8 added after AKI induction is also effective in maintaining renal function against damage, improving epithelial cell survival. The ability to protect kidneys from injury during both pre- and post-treatments, coupled with its anti-fibrotic effect, highlights Gal-8 as an endogenous factor to be considered in therapeutic strategies aimed at improving renal function and mitigating chronic pathogenic progression.

Targeting Nrf2/HO-1 and NF-κB/TNF-α signaling pathways with empagliflozin protects against atrial fibrillation-induced acute kidney injury in rats

A bidirectional relationship exists between atrial fibrillation (AF) and kidney function. Uncontrolled AF may lead to kidney injury, whereas renal dysfunction may contribute to AF initiation and maintenance. This study aimed to investigate the protective effect of the sodium glucose cotransporter-2 inhibitor empagliflozin (EMPA) on acute kidney injury (AKI) associated with AF induced by acetylcholine and calcium chloride (ACh/CaCl2) in rats and elucidate the potential underlying mechanism. Rats were randomly divided as follows: control (CTRL) group: administered vehicles only; AF group: intravenously injected 1 ml/kg of an ACh/CaCl2 mixture for seven days to induce AF; EMPA group: orally administered EMPA (30 mg/kg) for seven days; AF+EMPA10 and AF+EMPA30 groups: co-administered the induction mixture and EMPA (10 and 30 mg/kg, respectively) for seven days. Our results showed that EMPA (10 and 30 mg/kg) effectively maintained kidney function and demonstrated a significant antioxidant potential. EMPA also suppressed AF-induced renal tubulointerstitial injury and fibrotic changes concurrently with reducing renal levels of the pro-inflammatory cytokines tumour necrosis factor-α (TNF-α) and interleukin-6, as well as the pro-fibrotic marker transforming growth factor beta-1 and collagen type I. Mechanistically, EMPA boosted nuclear factor erythroid 2-related factor 2 (Nrf2) and heme oxygenase-1 (HO-1) renal tissue expression while repressing nuclear factor kappa B (NF-κB) activation. In addition, these beneficial effects of EMPA on kidneys were concurrent with its ability to effectively inhibit AF-related electrocardiographic changes, reduce incidence and duration of AF episodes, and markedly suppress serum B-type natriuretic peptide and C-reactive protein levels. In conclusion, EMPA protected against AKI associated with AF induced by ACh/CaCl2 in rats through simultaneous modulation of the Nrf2/HO-1 and the NF-κB/TNF-α signaling pathways, exerting antioxidant, anti-inflammatory, and anti-fibrotic effects.

Pseudogene GSTM3P1 derived long non-coding RNA promotes ischemic acute kidney injury by target directed microRNA degradation of kidney-protective mir-668

Long non-coding RNAs (lncRNAs) are a group of epigenetic regulators that have been implicated in kidney diseases including acute kidney injury (AKI). However, very little is known about the specific lncRNAs involved in AKI and the mechanisms underlying their pathologic roles. Here, we report a new lncRNA derived from the pseudogene GSTM3P1, which mediates ischemic AKI by interacting with and promoting the degradation of mir-668, a kidney-protective microRNA. GSTM3P1 and its mouse orthologue Gstm2-ps1 were induced by hypoxia in cultured kidney proximal tubular cells. In mouse kidneys, Gstm2-ps1 was significantly upregulated in proximal tubules at an early stage of ischemic AKI. This transient induction of Gstm2-ps1 depends on G3BP1, a key component in stress granules. GSTM3P1 overexpression increased kidney proximal tubular apoptosis after ATP depletion, which was rescued by mir-668. Notably, kidney proximal tubule-specific knockout of Gstm2-ps1 protected mice from ischemic AKI, as evidenced by improved kidney function, diminished tubular damage and apoptosis, and reduced kidney injury biomarker (NGAL) induction. To test the therapeutic potential, Gstm2-ps1 siRNAs were introduced into cultured mouse proximal tubular cells or administered to mice. In cultured cells, Gstm2-ps1 knockdown suppressed ATP depletion-associated apoptosis. In mice, Gstm2-ps1 knockdown ameliorated ischemic AKI. Mechanistically, both GSTM3P1 and Gstm2-ps1 possessed mir-668 binding sites and downregulated the mature form of mir-668. Specifically, GSTM3P1 directly bound to mature mir-668 to induce its decay via target-directed microRNA degradation. Thus, our results identify GSTM3P1 as a novel lncRNA that promotes kidney tubular cell death in AKI by binding mir-668 to inducing its degradation.

Nucleic acid-based nanotherapeutics for treating sepsis and associated organ injuries

In recent years, gene therapy has been made possible with the success of nucleic acid drugs against sepsis and its related organ dysfunction. Therapeutics based on nucleic acids such as small interfering RNAs (siRNAs), microRNAs (miRNAs), messenger RNAs (mRNAs), and plasmid DNAs (pDNAs) guarantee to treat previously undruggable diseases. The advantage of nucleic acid-based therapy against sepsis lies in the development of nanocarriers, achieving targeted and controlled gene delivery for improved efficacy with minimal adverse effects. Entrapment into nanocarriers also ameliorates the poor cellular uptake of naked nucleic acids. In this study, we discuss the current state of the art in nanoparticles for nucleic acid delivery to treat hyperinflammation and apoptosis associated with sepsis. The optimized design of the nanoparticles through physicochemical property modification and ligand conjugation can target specific organs-such as lung, heart, kidney, and liver-to mitigate multiple sepsis-associated organ injuries. This review highlights the nanomaterials designed for fabricating the anti-sepsis nanosystems, their physicochemical characterization, the mechanisms of nucleic acid-based therapy in working against sepsis, and the potential for promoting the therapeutic efficiency of the nucleic acids. The current investigations associated with nanoparticulate nucleic acid application in sepsis management are summarized in this paper. Noteworthily, the potential application of nanotherapeutic nucleic acids allows for a novel strategy to treat sepsis. Further clinical studies are required to confirm the findings in cell- and animal-based experiments. The capability of large-scale production and reproducibility of nanoparticle products are also critical for commercialization. It is expected that numerous anti-sepsis possibilities will be investigated for nucleic acid-based nanotherapeutics in the future.

Immune profiling of critically ill patients with acute kidney injury during the first week after various types of injuries: the REALAKI study

BACKGROUND

Acute kidney injury (AKI) is common in hospitalized patients and results in significant morbidity and mortality. The objective of the study was to explore the systemic immune response of intensive care unit patients presenting with AKI, especially the association between immune profiles and persistent AKI during the first week after admission following various types of injuries (sepsis, trauma, surgery, and burns).

METHODS

REALAKI is an ancillary analysis of the REAnimation Low Immune Status Marker (REALISM) cohort study, in which 359 critically ill patients were enrolled in three different intensive care units. Patients with end-stage renal disease were excluded from the REALAKI study. Clinical samples and data were collected three times after admission: at day 1 or 2 (D1-2), day 3 or 4 (D3-4) and day 5, 6 or 7 (D5-7). Immune profiles were compared between patients presenting with or without AKI. Patients with AKI at both D1-2 and D5-7 were defined as persistent AKI. A multivariable logistic regression model was performed to determine the independent association between AKI and patients' immunological parameters.

RESULTS

Three hundred and fifty-nine patients were included in this analysis. Among them, 137 (38%) were trauma patients, 103 (29%) post-surgery patients, 95 (26%) sepsis patients, and 24 (7%) were burn patients. One hundred and thirty-nine (39%) patients presented with AKI at D1-2 and 61 (20%) at D5-7. Overall, 94% presented with persistent AKI at D5-7. Patients with AKI presented with increased pro and anti-inflammatory cytokines and altered innate and adaptive immune responses. The modifications observed in the immune profiles tended to be more pronounced with increasing KDIGO stages. In the logistic regression model, a statistically significant association was observed at D1-2 between AKI and CD10lowCD16low immature neutrophils (OR 3.03 [1.7-5.5]-p < 0.001). At D5-7, increased interleukin-10 (IL-10) levels and reduced ex vivo TNF-α production after LPS stimulation were significantly associated with the presence of AKI (OR 1.38 [1.12-1.71]-p = 0.001 and 0.51 [0.27-0.91]-p = 0.03, respectively). Patients who recovered from AKI between D1-2 and D5-7 compared to patients with persistent AKI at D5-7, tended to correct these alterations.

CONCLUSION

Following various types of severe injuries, early AKI is associated with the initial inflammatory response. Presence of AKI at the end of the first week after injury is associated with injury-induced immunosuppression.

Crosstalk among proximal tubular cells, macrophages, and fibroblasts in acute kidney injury: single-cell profiling from the perspective of ferroptosis

The link between ferroptosis, a form of cell death mediated by iron and acute kidney injury (AKI) is recently gaining widespread attention. However, the mechanism of the crosstalk between cells in the pathogenesis and progression of acute kidney injury remains unexplored. In our research, we performed a non-negative matrix decomposition (NMF) algorithm on acute kidney injury single-cell RNA sequencing data based specifically focusing in ferroptosis-associated genes. Through a combination with pseudo-time analysis, cell-cell interaction analysis and SCENIC analysis, we discovered that proximal tubular cells, macrophages, and fibroblasts all showed associations with ferroptosis in different pathways and at various time. This involvement influenced cellular functions, enhancing cellular communication and activating multiple transcription factors. In addition, analyzing bulk expression profiles and marker genes of newly defined ferroptosis subtypes of cells, we have identified crucial cell subtypes, including Egr1 + PTC-C1, Jun + PTC-C3, Cxcl2 + Mac-C1 and Egr1 + Fib-C1. All these subtypes which were found in AKI mice kidneys and played significantly distinct roles from those of normal mice. Moreover, we verified the differential expression of Egr1, Jun, and Cxcl2 in the IRI mouse model and acute kidney injury human samples. Finally, our research presented a novel analysis of the crosstalk of proximal tubular cells, macrophages and fibroblasts in acute kidney injury targeting ferroptosis, therefore, contributing to better understanding the acute kidney injury pathogenesis, self-repairment and acute kidney injury-chronic kidney disease (AKI-CKD) progression.

A systematic review of epigenetic interplay in kidney diseases: Crosstalk between long noncoding RNAs and methylation, acetylation of chromatin and histone

The intricate crosstalk between long noncoding RNAs (lncRNAs) and epigenetic modifications such as chromatin/histone methylation and acetylation offer new perspectives on the pathogenesis and treatment of kidney diseases. lncRNAs, a class of transcripts longer than 200 nucleotides with no protein-coding potential, are now recognized as key regulatory molecules influencing gene expression through diverse mechanisms. They modulate the epigenetic modifications by recruiting or blocking enzymes responsible for adding or removing methyl or acetyl groups, such as DNA, N6-methyladenosine (m6A) and histone methylation and acetylation, subsequently altering chromatin structure and accessibility. In kidney diseases such as acute kidney injury (AKI), chronic kidney disease (CKD), diabetic nephropathy (DN), glomerulonephritis (GN), and renal cell carcinoma (RCC), aberrant patterns of DNA/RNA/histone methylation and acetylation have been associated with disease onset and progression, revealing a complex interplay with lncRNA dynamics. Recent studies have highlighted how lncRNAs can impact renal pathology by affecting the expression and function of key genes involved in cell cycle control, fibrosis, and inflammatory responses. This review will separately address the roles of lncRNAs and epigenetic modifications in renal diseases, with a particular emphasis on elucidating the bidirectional regulatory effects and underlying mechanisms of lncRNAs in conjunction with DNA/RNA/histone methylation and acetylation, in addition to the potential exacerbating or renoprotective effects in renal pathologies. Understanding the reciprocal relationships between lncRNAs and epigenetic modifications will not only shed light on the molecular underpinnings of renal pathologies but also present new avenues for therapeutic interventions and biomarker development, advancing precision medicine in nephrology.

Ultrasmall Polyphenol-NAD+ Nanoparticle-Mediated Renal Delivery for Mitochondrial Repair and Anti-Inflammatory Treatment of AKI-to-CKD Progression

As a central metabolic molecule, nicotinamide adenine dinucleotide (NAD+) can potentially treat acute kidney injury (AKI) and chronic kidney disease (CKD); however, its bioavailability is poor due to short half-life, instability, the deficiency of targeting, and difficulties in transmembrane transport. Here a physiologically adaptive gallic acid-NAD+ nanoparticle is designed, which has ultrasmall size and pH-responsiveness, passes through the glomerular filtration membrane to reach injured renal tubules, and efficiently delivers NAD+ into the kidneys. With an effective accumulation in the kidneys, it restores renal function, immune microenvironment homeostasis, and mitochondrial homeostasis of AKI mice via the NAD+-Sirtuin-1 axis, and exerts strong antifibrotic effects on the AKI-to-CKD transition by inhibiting TGF-β signaling. It also exhibits excellent stability, biodegradable, and biocompatible properties, ensuring its long-term safety, practicality, and clinical translational feasibility. The present study shows a potential modality of mitochondrial repair and immunomodulation through nanoagents for the efficient and safe treatment of AKI and CKD.

Expanding landscape of coronary microvascular disease in co-morbid conditions: Metabolic disease and beyond

Coronary microvascular disease (CMD) and impaired coronary blood flow control are defects that occur early in the pathogenesis of heart failure in cardiometabolic conditions, prior to the onset of atherosclerosis. In fact, recent studies have shown that CMD is an independent predictor of cardiac morbidity and mortality in patients with obesity and metabolic disease. CMD is comprised of functional, structural, and mechanical impairments that synergize and ultimately reduce coronary blood flow in metabolic disease and in other co-morbid conditions, including transplant, autoimmune disorders, chemotherapy-induced cardiotoxicity, and remote injury-induced CMD. This review summarizes the contemporary state-of-the-field related to CMD in metabolic and these other co-morbid conditions based on mechanistic data derived mostly from preclinical small- and large-animal models in light of available clinical evidence and given the limitations of studying these mechanisms in humans. In addition, we also discuss gaps in current understanding, emerging areas of interest, and opportunities for future investigations in this field.

Proteomics coupled transcriptomics reveals Slc34a1 and Slc34a3 downregulation as potential features of nephrotoxin-induced acute kidney injury

Acute kidney injury (AKI) stands as a prevalent and economically burdensome condition worldwide, yet its complex molecular mechanisms remain incompletely understood. To address this gap, our study employs a multifaceted approach, combining mass spectrometry and RNA sequencing technologies, to elucidate the intricate molecular landscape underlying nephrotoxin-induced AKI in mice by cisplatin- and LPS-induced. By examining the protein and RNA expression profiles, we aimed to uncover novel insights into the pathogenesis of AKI and identify potential diagnostic and therapeutic targets. Our results demonstrate significant down-regulation of Slc34a1 and Slc34a3, shedding light on their crucial roles in AKI pathology and highlighting their promise as actionable targets for diagnosis and treatment. This comprehensive analysis not only enhances our understanding of AKI pathophysiology but also offers valuable avenues for the development of targeted interventions to mitigate its clinical impact. SIGNIFICANCE: Nephrotoxicity acute kidney injury (AKI) is a common clinical condition whose pathogenesis is the process by which some drugs, chemicals or other factors cause damage to the kidneys, resulting in impaired kidney function. Although it has been proved that different nephrotoxic substances can affect the kidney through different pathways, whether they have a commonality has not been registered. Here, we combined transcriptomics and proteomics to study the molecular mechanism of LPS and cisplatin-induced nephrotoxic acute kidney injury finding that the down-regulation of Slc34a1 and Slc34a3 may be a critical link in nephrotoxic acute kidney injury, which can be used as a marker for its early diagnosis.

Neutrophil-Mediated Nanozyme Delivery System for Acute Kidney Injury Therapy

Reactive oxygen species (ROS) scavenging of nanozymes toward acute kidney injury (AKI) is a current promising strategy, however, the glomerular filtration barrier (GFB) limits their application for treating kidney related diseases. Here, a neutrophil-mediated delivery system able to hijack neutrophil to transport nanozyme-loaded cRGD-liposomes to inflamed kidney for AKI treatment by cRGD targeting integrin αvβ1 is reported. The neutrophil-mediated nanozyme delivery system demonstrated great antioxidant and anti-apoptosis ability in HK-2 and NRK-52E cell lines. Moreover, in ischemia-reperfusion (I/R) induced AKI mice, a single dose of LM@cRGD-LPs 12 h post-ischemia significantly reduces renal function indicators, alleviates renal pathological changes, and inhibits apoptosis of renal tubular cells and the expression of renal tubular injured marker, thus remarkably reducing the damage of AKI. Mechanistically, the treatment of LM@cRGD-LPs markedly inhibits the process of Nrf2 to the nucleus and reduces the expression of the downstream HO-1, achieves a 99.51% increase in renal tissue Nrf2 levels, and an 86.31% decrease in HO-1 levels after LM@cRGD-LPs treatment. In short, the strategy of neutrophil-mediated nanozyme delivery system hold great promise as a potential therapy for AKI or other inflammatory diseases.

Imaging kidney inflammation using an oxidatively activated MRI probe

Imaging tools for kidney inflammation could improve care for patients suffering inflammatory kidney diseases by lessening reliance on percutaneous biopsy or biochemical tests alone. During kidney inflammation, infiltration of myeloid immune cells generates a kidney microenvironment that is oxidizing relative to normal kidney. Here, we evaluated whether magnetic resonance imaging (MRI) using the redox-active iron (Fe) complex Fe-PyC3A as an oxidatively activated probe could serve as a marker of kidney inflammation using mouse models of unilateral ischemia-reperfusion injury (IRI) and lupus nephritis (MRL-lpr mice). We imaged unilateral IRI in gp91phox knockout mice, which are deficient in the nicotinamide oxidase II (NOX2) enzyme required for myeloid oxidative burst, as loss of function control, and imaged MRL/MpJ mice as non-kidney involved lupus control. Gadoterate meglumine was used as a non-oxidatively activated control MRI probe. Fe-PyC3A safety was preliminarily examined following a single acute dose. Fe-PyC3A generated significantly greater MRI signal enhancement in the IRI kidney compared to the contralateral kidney in wild-type mice, but the effect was not observed in the NOX2-deficient control. Fe-PyC3A also generated significantly greater kidney enhancement in MRL-lpr mice compared to MRL/MpJ control. Gadoterate meglumine did not differentially enhance the IRI kidney over the contralateral kidney and did not differentially enhance the kidneys of MRL-lpr over MRL/MpJ mice. Fe-PyC3A was well tolerated at the highest dose evaluated, which was a 40-fold greater than required for imaging. Thus, our data indicate that MRI using Fe-PyC3A is specific to an oxidizing kidney environment shaped by activity of myeloid immune cells and support further evaluation of Fe-PyC3A for imaging kidney inflammation.

Insulin-like growth factor-1 effects on kidney development in preterm piglets

BACKGROUND

Preterm birth disrupts fetal kidney development, potentially leading to postnatal acute kidney injury. Preterm infants are deficient in insulin-like growth factor 1 (IGF-1), a growth factor that stimulates organ development. By utilizing a preterm pig model, this study investigated whether IGF-1 supplementation enhances preterm kidney maturation.

METHODS

Cesarean-delivered preterm pigs were treated systemically IGF-1 or vehicle control for 5, 9 or 19 days after birth. Blood, urine, and kidney tissue were collected for biochemical, histological and gene expression analyses. Age-matched term-born pigs were sacrificed at similar postnatal ages and served as the reference group.

RESULTS

Compared with term pigs, preterm pigs exhibited impaired kidney maturation, as indicated by analyses of renal morphology, histopathology, and inflammatory and injury markers. Supplementation with IGF-1 reduced signs of kidney immaturity, particularly in the first week of life, as indicated by improved morphology, upregulated expression of key developmental genes, reduced severity and incidence of microscopic lesions, and decreased levels of inflammatory and injury markers. No association was seen between the symptoms of necrotizing enterocolitis and kidney defects.

CONCLUSION

Preterm birth in pigs impairs kidney maturation and exogenous IGF-1 treatment partially reverses this impairment. Early IGF-1 supplementation could support the development of preterm kidneys.

IMPACT

Preterm birth may disrupt kidney development in newborns, potentially leading to morphological changes, injury, and inflammation. Preterm pigs have previously been used as models for preterm infants, but not for kidney development. IGF-1 supplementation promotes kidney maturation and alleviates renal impairments in the first week of life in preterm pigs. IGF-1 may hold potential as a supportive therapy for preterm infants sensitive to acute kidney injury.

Mincle receptor in macrophage and neutrophil contributes to the unresolved inflammation during the transition from acute kidney injury to chronic kidney disease

Background

Recent studies have demonstrated a strong association between acute kidney injury (AKI) and chronic kidney disease (CKD), while the unresolved inflammation is believed to be a driving force for this chronic transition process. As a transmembrane pattern recognition receptor, Mincle (macrophage-inducible C-type lectin, Clec4e) was identified to participate in the early immune response after AKI. However, the impact of Mincle on the chronic transition of AKI remains largely unclear.

Methods

We performed single-cell RNA sequencing (scRNA-seq) with the unilateral ischemia-reperfusion (UIR) murine model of AKI at days 1, 3, 14 and 28 after injury. Potential effects and mechanism of Mincle on renal inflammation and fibrosis were further validated in vivo utilizing Mincle knockout mice.

Results

The dynamic expression of Mincle in macrophages and neutrophils throughout the transition from AKI to CKD was observed. For both cell types, Mincle expression was significantly up-regulated on day 1 following AKI, with a second rise observed on day 14. Notably, we identified distinct subclusters of Minclehigh neutrophils and Minclehigh macrophages that exhibited time-dependent influx with dual peaks characterized with remarkable pro-inflammatory and pro-fibrotic functions. Moreover, we identified that Minclehigh neutrophils represented an "aged" mature neutrophil subset derived from the "fresh" mature neutrophil cluster in kidney. Additionally, we observed a synergistic mechanism whereby Mincle-expressing macrophages and neutrophils sustained renal inflammation by tumor necrosis factor (TNF) production. Mincle-deficient mice exhibited reduced renal injury and fibrosis following AKI.

Conclusion

The present findings have unveiled combined persistence of Minclehigh neutrophils and macrophages during AKI-to-CKD transition, contributing to unresolved inflammation followed by fibrosis via TNF-α as a central pro-inflammatory cytokine. Targeting Mincle may offer a novel therapeutic strategy for preventing the transition from AKI to CKD.

Heart failure subtype after acute kidney injury

INTRODUCTION

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Fibroblast expression of transmembrane protein smoothened governs microenvironment characteristics after acute kidney injury

The smoothened (Smo) receptor facilitates hedgehog signaling between kidney fibroblasts and tubules during acute kidney injury (AKI). Tubule-derived hedgehog is protective in AKI, but the role of fibroblast-selective Smo is unclear. Here, we report that Smo-specific ablation in fibroblasts reduced tubular cell apoptosis and inflammation, enhanced perivascular mesenchymal cell activities, and preserved kidney function after AKI. Global proteomics of these kidneys identified extracellular matrix proteins, and nidogen-1 glycoprotein in particular, as key response markers to AKI. Intriguingly, Smo was bound to nidogen-1 in cells, suggesting that loss of Smo could affect nidogen-1 accessibility. Phosphoproteomics revealed that the 'AKI protector' Wnt signaling pathway was activated in these kidneys. Mechanistically, nidogen-1 interacted with integrin β1 to induce Wnt in tubules to mitigate AKI. Altogether, our results support that fibroblast-selective Smo dictates AKI fate through cell-matrix interactions, including nidogen-1, and offers a robust resource and path to further dissect AKI pathogenesis.

Early Identification of Sepsis-Induced Acute Kidney Injury by Using Monocyte Distribution Width, Red-Blood-Cell Distribution, and Neutrophil-to-Lymphocyte Ratio

Sepsis-induced acute kidney injury (AKI) is a common complication in patients with severe illness and leads to increased risks of mortality and chronic kidney disease. We investigated the association between monocyte distribution width (MDW), red-blood-cell volume distribution width (RDW), neutrophil-to-lymphocyte ratio (NLR), sepsis-related organ-failure assessment (SOFA) score, mean arterial pressure (MAP), and other risk factors and sepsis-induced AKI in patients presenting to the emergency department (ED). This retrospective study, spanning 1 January 2020, to 30 November 2020, was conducted at a university-affiliated teaching hospital. Patients meeting the Sepsis-2 consensus criteria upon presentation to our ED were categorized into sepsis-induced AKI and non-AKI groups. Clinical parameters (i.e., initial SOFA score and MAP) and laboratory markers (i.e., MDW, RDW, and NLR) were measured upon ED admission. A logistic regression model was developed, with sepsis-induced AKI as the dependent variable and laboratory parameters as independent variables. Three multivariable logistic regression models were constructed. In Model 1, MDW, initial SOFA score, and MAP exhibited significant associations with sepsis-induced AKI (area under the curve [AUC]: 0.728, 95% confidence interval [CI]: 0.668-0.789). In Model 2, RDW, initial SOFA score, and MAP were significantly correlated with sepsis-induced AKI (AUC: 0.712, 95% CI: 0.651-0.774). In Model 3, NLR, initial SOFA score, and MAP were significantly correlated with sepsis-induced AKI (AUC: 0.719, 95% CI: 0.658-0.780). Our novel models, integrating MDW, RDW, and NLR with initial SOFA score and MAP, can assist with the identification of sepsis-induced AKI among patients with sepsis presenting to the ED.

Identification of Differentially Expressed Genes in Cold Storage-associated Kidney Transplantation

BACKGROUND

Although it is acknowledged that ischemia-reperfusion injury is the primary pathology of cold storage-associated kidney transplantation, its underlying mechanism is not well elucidated.

METHODS

To extend the understanding of molecular events and mine hub genes posttransplantation, we performed bulk RNA sequencing at different time points (24 h, day 7, and day 14) on a murine kidney transplantation model with prolonged cold storage (10 h).

RESULTS

In the present study, we showed that genes related to the regulation of apoptotic process, DNA damage response, cell cycle/proliferation, and inflammatory response were steadily elevated at 24 h and day 7. The upregulated gene profiling delicately transformed to extracellular matrix organization and fibrosis at day 14. It is prominent that metabolism-associated genes persistently took the first place among downregulated genes. The gene ontology terms of particular note to enrich are fatty acid oxidation and mitochondria energy metabolism. Correspondingly, the key enzymes of the above processes were the products of hub genes as recognized. Moreover, we highlighted the proximal tubular cell-specific increased genes at 24 h by combining the data with public RNA-Seq performed on proximal tubules. We also focused on ferroptosis-related genes and fatty acid oxidation genes to show profound gene dysregulation in kidney transplantation.

CONCLUSIONS

The comprehensive characterization of transcriptomic analysis may help provide diagnostic biomarkers and therapeutic targets in kidney transplantation.

Blood Cell Ratios Unveiled: Predictive Markers of Myocardial Infarction Prognosis

BACKGROUND

Even if the management and treatment of patients with non-ST-elevation myocardial infarction (NSTEMI) have significantly evolved, it is still a burgeoning disease, an active volcano with very high rates of morbidity and mortality. Therefore, novel management and therapeutic strategies for this condition are urgently needed. Lately, theories related to the role of various blood cells in NSTEMI have emerged, with most of this research having so far been focused on correlating the ratios between various leukocyte types (neutrophil/lymphocyte ratio-NLR, neutrophil/monocyte ratio-NMR). But what about erythrocytes? Is there an interaction between these cells and leukocytes, and furthermore, can this relationship influence NSTEMI prognosis? Are they partners in crime?

METHODS

Through the present study, we sought, over a period of sixteen months, to evaluate the neutrophil/red blood cell ratio (NRR), monocyte/red blood cell ratio (MRR) and lymphocyte/red blood cell ratio (LRR), assessing their potential role as novel prognostic markers in patients with NSTEMI.

RESULTS

There was a statistically significant correlation between the NRR, LRR, MRR and the prognosis of NSTEMI patients.

CONCLUSIONS

These new predictive markers could represent the start of future innovative therapies that may influence crosstalk pathways and have greater benefits in terms of cardiac repair and the secondary prevention of NSTEMI.

Dihydroartemisinin abolishes cisplatin-induced nephrotoxicity in vivo

Dihydroartemisinin (DHA), a derivative of artemisinin which is primarily used to treat malaria in clinic, also confers protective effect on lipopolysaccharide-induced nephrotoxicity. While, the activities of DHA in cisplatin (CDDP)-caused nephrotoxicity are elusive. To investigate the role and underlying mechanism of DHA in CDDP-induced nephrotoxicity. Mice were randomly separated into four groups: normal, CDDP, and DHA (25 and 50 mg/kg were orally injected 1 h before CDDP for consecutive 10 days). All mice except the normal were single injected intraperitoneally with CDDP (22 mg/kg) for once on the 7th day. Combined with quantitative proteomics and bioinformatics analysis, the impact of DHA on renal cell apoptosis, oxidative stress, biochemical indexes, and inflammation in mice were investigated. Moreover, a human hepatocellular carcinoma cells xenograft model was established to elucidate the impact of DHA on tumor-related effects of CDDP. DHA reduced the levels of creatinine (CREA) (p < 0.01) and blood urea nitrogen (BUN) (p < 0.01), reversed CDDP-induced oxidative, inflammatory, and apoptosis indexes (p < 0.01). Mechanistically, DHA attenuated CDDP-induced inflammation by inhibiting nuclear factor κB p65 (NFκB p65) expression, and suppressed CDDP-induced renal cell apoptosis by inhibiting p63-mediated endogenous and exogenous apoptosis pathways. Additionally, DHA alone significantly decreased the tumor weight and did not destroy the antitumor effect of CDDP, and did not impact AST and ALT. In conclusion, DHA prevents CDDP-triggered nephrotoxicity via reducing inflammation, oxidative stress, and apoptosis. The mechanisms refer to inhibiting NFκB p65-regulated inflammation and alleviating p63-mediated mitochondrial endogenous and Fas death receptor exogenous apoptosis pathway.

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

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

Urinary Concentration of Renal Biomarkers in Healthy Term Neonates: Gender Differences in GST-pi Excretion

BACKGROUND Serum creatinine, the criterion standard in assessment of renal function, is not reliable for the neonatal period because of its dependence on renal immaturity and maternal creatinine levels. Thus, it is important to study other biomarkers of renal function in neonates. The present study aimed to measure the urinary concentration of renal biomarkers: calbindin, clusterin, GST-pi (glutathione-S-transferase-alpha), KIM-1 (kidney injury molecule 1), MCP-1 (monocyte chemoattractant protein-1), and B2M (beta 2-microglobulin) in healthy term neonates. MATERIAL AND METHODS In the study, we included 80 healthy term neonates - 40 females and 40 males. We collected the neonates' urine on their first day of life. Urinary concentrations of calbindin, clusterin, KIM-1, MCP-1, and B2M were assessed using an immunoassay for kidney toxicology research. Because dilution of the urine affects the concentrations of urinary biomarkers, we normalized them to the concentration of urinary creatinine (Cr) and present them as biomarker/Cr ratios. RESULTS We obtained the following values of the assessed biomarker/Cr ratios (median [Q1-Q3]): calbindin/Cr.: 197.04 (56.25-595.17), KIM-1/Cr: 0.09 (0.04-0.18), MCP-1/Cr: 0.05 (0.02-0.14), B2M/Cr: 126.12 (19.03-342.48), GST-pi/Cr in boys: 1.28 (0.46-3.77), GST-pi/Cr in girls: 8.66 (2.51-27.82), clusterin/Cr: 4.55 (1.79-12.97) ng/mg Cr. CONCLUSIONS We showed the urinary levels of calbindin, clusterin, GST-pi, KIM-1, MCP-1, B2M in white, West Slavic, healthy term neonates. We found that in there is an association between female sex and a higher urinary GST-pi excretion, but urinary excretion of calbindin, clusterin, KIM-1, MCP-1, and B2M is sex-independent. The urinary levels of the assessed biomarkers do not depend on the method of delivery.

The intervention of cannabinoid receptor in chronic and acute kidney disease animal models: a systematic review and meta-analysis

AIM

Cannabinoid receptors are components of the endocannabinoid system that affect various physiological functions. We aim to investigate the effect of cannabinoid receptor modulation on kidney disease.

METHODS

PubMed, Web of Science databases, and EMBASE were searched. Articles selection, data extraction and quality assessment were independently performed by two investigators. The SYRCLE's RoB tool was used to assess the risk of study bias, and pooled SMD using a random-effect model and 95% CIs were calculated. Subgroup analyses were conducted in preselected subgroups, and publication bias was evaluated. We compared the effects of CB1 and CB2 antagonists and/or knockout and agonists and/or genetic regulation on renal function, blood glucose levels, body weight, and pathological damage-related indicators in different models of chronic and acute kidney injury.

RESULTS

The blockade or knockout of CB1 could significantly reduce blood urea nitrogen [SMD,- 1.67 (95% CI - 2.27 to - 1.07)], serum creatinine [SMD, - 1.88 (95% CI - 2.91 to - 0.85)], and albuminuria [SMD, - 1.60 (95% CI - 2.16 to - 1.04)] in renal dysfunction animals compared with the control group. The activation of CB2 group could significantly reduce serum creatinine [SMD, - 0.97 (95% CI - 1.83 to - 0.11)] and albuminuria [SMD, - 2.43 (95% CI - 4.63 to - 0.23)] in renal dysfunction animals compared with the control group.

CONCLUSIONS

The results suggest that targeting cannabinoid receptors, particularly CB1 antagonists and CB2 agonists, can improve kidney function and reduce inflammatory responses, exerting a renal protective effect and maintaining therapeutic potential in various types of kidney disease.

High resolution spatial profiling of kidney injury and repair using RNA hybridization-based in situ sequencing

Emerging spatially resolved transcriptomics technologies allow for the measurement of gene expression in situ at cellular resolution. We apply direct RNA hybridization-based in situ sequencing (dRNA HybISS, Cartana part of 10xGenomics) to compare male and female healthy mouse kidneys and the male kidney injury and repair timecourse. A pre-selected panel of 200 genes is used to identify cell state dynamics patterns during injury and repair. We develop a new computational pipeline, CellScopes, for the rapid analysis, multi-omic integration and visualization of spatially resolved transcriptomic datasets. The resulting dataset allows us to resolve 13 kidney cell types within distinct kidney niches, dynamic alterations in cell state over the course of injury and repair and cell-cell interactions between leukocytes and kidney parenchyma. At late timepoints after injury, C3+ leukocytes are enriched near pro-inflammatory, failed-repair proximal tubule cells. Integration of snRNA-seq dataset from the same injury and repair samples also allows us to impute the spatial localization of genes not directly measured by dRNA HybISS.

Huangqi Jiuni decoction prevents acute kidney injury induced by severe burns by inhibiting activation of the TNF/NF-κB pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Huangqi Jiuni decoction (HQJND) is a prescription for the treatment of severe burns provided based on traditional Chinese and Western medicine, which is created by the First Affiliated Hospital of Anhui Medical University. It consists of 12 herbs and has been used clinically for decades. It has greatly shortened the course of the disease, but the mechanism by which HQJND treats the disease still remains unclear.

AIM OF THE STUDY

Hence, the objective of this investigation was to utilize modern pharmacological tools to demonstrate the efficacy and mechanism of HQJND in the treatment of acute kidney injury (AKI) caused by severe burns.

MATERIALS AND METHODS

In this study, the chemical constituents in HQJND were first examined using liquid chromatography tandem mass spectrometry (LC-MS/MS). Then, by using network pharmacology, we screened the targets of drug and disease action, and predicted the signaling pathways acting in the course of drug treatment of disease. Finally, we attempted to verify the efficacy of the drug and explored its therapeutic mechanism after the establishment of an animal model, herbal gavage treatment, collection of rat kidneys and serum for renal function, quantitative real-time Polymerase Chain Reaction (RT-qPCR), Western Blotting (WB), Hematoxylin and eosin (HE) staining and Immunohistochemistry (IHC).

RESULTS

The 14 important active ingredients in HQJND was analyzed by liquid chromatography tandem mass spectrometry, while network pharmacology screening was performed to identify 353 disease-associated marker genes and 286 drug targets, finally identifying the TNF/NF-κB (tumor necrosis factor/nuclear factor kappa-B) signaling site: the key pathway of burn-induced acute kidney injury when HQJND intervened. The serum renal function and histopathology of rats demonstrated that the use of HQJND significantly improved the renal function in severe burns. RT-qPCR and WB confirmed that the TNF/NF-κB signaling pathway was activated in the Model group of rats, and HQJND could curb the signaling pathway because it moderated the expressions of key proteins in the process.

CONCLUSION

Based on modern pharmacology, we explored an effective herbal preparation to ameliorate the impairment of renal function after severe burns, which is most likely to function through the TNF/NF-κB signaling pathway.

Bone marrow stromal cell antigen-1 deficiency protects from acute kidney injury

This study aimed to investigate the role of bone marrow stromal cell antigen-1 (Bst1; also known as CD157) in acute kidney injury (AKI). Bst1 is a cell surface molecule with various enzymatic activities and downstream intracellular signaling pathways that modulate the immune response. Previous research has linked Bst1 to diseases such as ovarian cancer, Parkinson's disease, and rheumatoid arthritis. We used bilateral ischemia-reperfusion injury (IRI) as an AKI model and created bone marrow chimeric mice to evaluate the role of Bst1 in bone marrow-derived cells. We also used flow cytometry to identify Bst1/CD157 expression in hematopoietic cells and evaluate immune cell dynamics in the kidney. The findings showed that Bst1-deficient (Bst1-/-) mice were protected against renal bilateral IRI. Bone marrow chimera experiments revealed that Bst1 expression on hematopoietic cells, but not parenchymal cells, induced renal IRI. Bst1 was mainly found in B cells and neutrophils by flow cytometry of the spleen and bone marrow. In vitro, migration of neutrophils from Bst1-/- mice was suppressed, and adoptive transfer of neutrophils from wild-type Bst1+/+ mice abolished the renal protective effect in Bst1 knockout mice. In conclusion, the study demonstrated that Bst1-/- mice are protected against renal IRI and that Bst1 expression in neutrophils plays a crucial role in inducing renal IRI. These findings suggest that targeting Bst1 in neutrophils could be a potential therapeutic strategy for AKI.NEW & NOTEWORTHY Acute kidney injury (AKI), a serious disease for which there is no effective Federal Drug Administration-approved treatment, is associated with high mortality rates. Bone marrow stromal cell antigen-1 (Bst1) is a cell surface molecule that can cause kidney fibrosis, but its role in AKI is largely unknown. Our study showed that Bst1-/- mice revealed a protective effect against renal bilateral ischemia-reperfusion injury (IRI). Adoptive transfer studies confirmed that Bst1 expression in hematopoietic cells, especially neutrophils, contributed to renal bilateral IRI.

CU06-1004 alleviates oxidative stress and inflammation on folic acid-induced acute kidney injury in mice

PURPOSE

Acute kidney injury (AKI) is characterized by reduced renal function, oxidative stress, inflammation, and renal fibrosis. CU06-1004, an endothelial cell dysfunction blocker, exhibits anti-inflammatory effects by reducing vascular permeability in pathological conditions. However, the potential effects of CU06-1004 on AKI have not been investigated. We investigated the renoprotective effect of CU06-1004 against oxidative stress, inflammation, and fibrotic changes in a folic acid-induced AKI model.

METHODS

AKI was induced by intraperitoneal injection of high dose (250 mg/kg) folic acid in mice. CU06-1004 was orally administered a low (10 mg/kg) or high dose (20 mg/kg).

RESULTS

CU06-1004 ameliorated folic acid-induced AKI by decreasing serum blood urea nitrogen and creatinine levels, mitigating histological abnormalities, and decreasing tubular injury markers such as kidney injury molecule-1 and neutrophil gelatinase-associated lipocalin in folic acid-induced AKI mice. Additionally, CU06-1004 alleviated folic acid-induced oxidative stress by reducing 4-hydroxynonenal and malondialdehyde levels. Furthermore, it attenuated macrophage infiltration and suppressed the expression of the proinflammatory factors, including tumor necrosis factor-α, intercellular adhesion molecule-1, and vascular cell adhesion protein-1. Moreover, CU06-1004 mitigated folic acid-induced tubulointerstitial fibrosis by decreasing α-smooth muscle actin and transforming growth factor-β expression.

CONCLUSION

These findings suggest CU06-1004 as a potential therapeutic agent for folic acid-induced AKI.

Corin protects against acute kidney injury in mice through anti-inflammatory effects

Corin is a type II transmembrane serine protease mainly expressed in the heart. Recently, corin was detected in the kidney and was reported to be associated with multiple kidney diseases. To date, its effect on acute kidney injury (AKI) has not been clarified. Here, we found that corin was constitutively expressed in renal tubules, especially in proximal and distal tubular epithelial cells. The expression of corin was dramatically reduced in ischemia/reperfusion injury (IRI)-induced AKI mouse model and oxygen-glucose deprivation (OGD)-induced human proximal tubular epithelial (HK-2) cells injury model, suggesting a potential role of corin in AKI. Corin deficient mice exhibited aggravated renal injury in AKI, as indicated by higher elevation of serum creatinine (SCr) and blood urea nitrogen (BUN), more severe tubular damage, and increased cell death versus wild type mice, demonstrating a protective effect of corin on AKI. In vitro overexpression of corin didn't directly alleviate hypoxia-induced HK-2 cells death, revealing that the protective effect of corin against AKI is not due to direct protection of tubular epithelial cells but may be through indirect protection. Microarray analysis showed enhanced inflammatory chemokines signaling and leukocyte chemotaxis in corin-/- mice after AKI, identifying an important role of corin in halting leukocyte chemotaxis and inflammatory response. Consistently, corin-/- mice after AKI displayed increased tubulointerstitial neutrophils and macrophages infiltration, as well as higher inflammatory mediators in kidneys. Taken together, our study indicates that tubular corin exerts a protective effect against AKI through negative regulation of chemotaxis signaling and inflammation in the kidney.

Recombinant antithrombin attenuates acute kidney injury associated with rhabdomyolysis: an in vivo animal study

BACKGROUND

Rhabdomyolysis is characterized by the destruction and necrosis of skeletal muscle tissue, resulting in acute kidney injury (AKI). Recombinant antithrombin (rAT) has DNA repair and vascular endothelial-protection properties. Herein, we investigated whether rAT therapy has beneficial effects against rhabdomyolysis-induced AKI. Ten-week-old male B6 mice were injected with 5 mL/kg of 50% glycerol intramuscularly in the left thigh after 24 h of fasting to create a rhabdomyolysis mouse model. Further, 750 IU/kg rAT was injected intraperitoneally at 24 and 72 h after the rhabdomyolysis model was established. The mice were euthanized after 96 h for histological analysis. Saline was administered to mice in the control group.

RESULTS

Blood tests show elevated serum creatinine, urea nitrogen, and neutrophil gelatinase-associated lipocalin levels in rhabdomyolysis. Loss of tubular epithelial cell nuclei and destruction of the tubular luminal surface structure was observed in the untreated group, which improved with rAT treatment. Immunostaining for Ki-67 showed increased Ki-67-positive nuclei in the tubular epithelial cells in the rAT group, suggesting that rAT may promote tubular epithelial cell regeneration. The microvilli of the brush border of the renal tubules were shed during rhabdomyolysis, and rAT treatment reduced this injury. The vascular endothelial glycocalyx, which is usually impaired by rhabdomyolysis, became functional following rAT treatment.

CONCLUSIONS

Treatment with rAT suppressed rhabdomyolysis-induced AKI, suggesting that rAT therapy may be a novel therapeutic approach.

Mitochondrial Signaling, the Mechanisms of AKI-to-CKD Transition and Potential Treatment Targets

Acute kidney injury (AKI) is increasing in prevalence and causes a global health burden. AKI is associated with significant mortality and can subsequently develop into chronic kidney disease (CKD). The kidney is one of the most energy-demanding organs in the human body and has a role in active solute transport, maintenance of electrochemical gradients, and regulation of fluid balance. Renal proximal tubular cells (PTCs) are the primary segment to reabsorb and secrete various solutes and take part in AKI initiation. Mitochondria, which are enriched in PTCs, are the main source of adenosine triphosphate (ATP) in cells as generated through oxidative phosphorylation. Mitochondrial dysfunction may result in reactive oxygen species (ROS) production, impaired biogenesis, oxidative stress multiplication, and ultimately leading to cell death. Even though mitochondrial damage and malfunction have been observed in both human kidney disease and animal models of AKI and CKD, the mechanism of mitochondrial signaling in PTC for AKI-to-CKD transition remains unknown. We review the recent findings of the development of AKI-to-CKD transition with a focus on mitochondrial disorders in PTCs. We propose that mitochondrial signaling is a key mechanism of the progression of AKI to CKD and potential targeting for treatment.

Preclinical evidence of reno-protective effect of quercetin on acute kidney injury: a meta-analysis of animal studies

Objective: This study evaluated the reno-protective effects of quercetin in animal models of acute kidney injury (AKI). Methods: We conducted a systematic search of literature published before April 2023 in PubMed, Web of Science, and EMBASE databases. Methodological quality was assessed by SYRCLE's RoB tool. Funnel plot, Egger's test, and Begg's test were used to determine publication bias. Results: A total of 19 studies with 288 animals were included in this meta-analysis. The methodology quality scores of the included studies ranged from 4 to 7. The results indicated that quercetin reduced blood urea nitrogen (SMD = -4.78; 95% CI: 6.45, -3.12; p < 0.01; I2 = 84%) and serum creatinine (SMD: 2.73, 95% CI: 3.66, -1.80; p < 0.01; I2 = 80%) in AKI models. The result of sensitivity analysis was stable, while the results of funnel plot indicated asymmetric. In addition, we further analyzed inflammatory cytokines, oxidative stress levels, and kidney injury scores, and found that quercetin treatment had antioxidant and anti-inflammatory effects and improved kidney injury scores in animal models of AKI. Conclusion: Quercetin exhibited a promising reno-protective effect in AKI animal models. Systematic Review Registration: PROSPERO (CRD42023433333).

Ascorbate protects human kidney organoids from damage induced by cell-free hemoglobin

Sepsis-associated acute kidney injury is associated with high morbidity and mortality in critically ill patients. Cell-free hemoglobin (CFH) is released into the circulation of patients with severe sepsis and the levels of CFH are independently associated with mortality. CFH treatment increased cytotoxicity in the human tubular epithelial cell line HK-2. To better model the intact kidney, we cultured human kidney organoids derived from induced pluripotent stem cells. We treated human kidney organoids grown using both three-dimensional and transwell protocols with CFH for 48 h. We found evidence for increased tubular toxicity, oxidative stress, mitochondrial fragmentation, endothelial cell injury and injury-associated transcripts compared to those of the untreated control group. To evaluate the protective effect of clinically available small molecules, we co-treated CFH-injured organoids with ascorbate (vitamin C) or acetaminophen for 48 h. We found significantly decreased toxicity, preservation of endothelial cells and reduced mitochondrial fragmentation in the group receiving ascorbate following CFH treatment. This study provides direct evidence that ascorbate or ascorbic acid protects human kidney cells from CFH-induced damage such as that in sepsis-associated acute kidney injury.

Acute Kidney Injury: Definition, Management, and Promising Therapeutic Target

Acute kidney injury (AKI) is caused by a sudden loss of renal function, resulting in the build-up of waste products and a significant increase in mortality and morbidity. It is commonly diagnosed in critically ill patients, with its occurrence estimated at up to 50% in patients hospitalized in the intensive critical unit. Despite ongoing efforts, the death rate associated with AKI has remained high over the past half-century. Thus, it is critical to investigate novel therapy options for preventing the epidemic. Many studies have found that inflammation and Toll-like receptor-4 (TLR-4) activation have a significant role in the pathogenesis of AKI. Noteworthy, challenges in the search for efficient pharmacological therapy for AKI have arisen due to the multifaceted origin and complexity of the clinical history of people with the disease. This article focuses on kidney injury's epidemiology, risk factors, and pathophysiological processes. Specifically, it focuses on the role of TLRs especially type 4 in disease development.

Perioperative Acute Kidney Injury: Implications, Approach, Prevention

Acute kidney injury remains a common and significant contributor to perioperative morbidity. Acute kidney injury worsens patient outcomes, and anesthesiologists should make significant efforts to prevent, assess, and treat perioperative renal injury. The authors discuss the impact of renal injury on patient outcomes and putative underlying mechanisms, evidence underlying treatments for acute kidney injury, and practices that may prevent the development of perioperative renal injury.

Supramolecular Nano-Assembly of Caffeate-Strengthened Phenylboronic Ester with Multistep ROS Scavenging Ability for Targeted Therapy of Acute Kidney Injury

Acute kidney injury (AKI) is a life-threatening complication with a considerable occurrence among patients. AKI is typically accompanied by an elevation in reactive oxidative species (ROS) in renal tissues, which is the main contributor to kidney damage. Herein, a supramolecular nano-assembly (Ser-HPEC) containing an ethyl caffeate-strengthened phenylboronic ester with ROS-triggered antioxidative ability is proposed for AKI-targeted therapy. Nano-assemblies can rapidly accumulate in the ischemia-reperfusion-injured kidney via kidney injury molecule-1 (Kim-1)-mediated homing ability of l-serine. By consuming pathological levels of ROS, two different antioxidants, ethyl caffeate and 4-hydroxybenzyl alcohol, are spontaneously released from a single module to relieve oxidative stress and diminish acute inflammation in injured renal tissue. The multistep ROS scavenging strategy combined with a precise targeting capability endows the aforementioned nano-assembly with effectiveness in preserving the integrity and functions of the injured kidney, providing new inspiration for the treatment of inflammatory diseases, including AKI.

The AKI-to-CKD Transition: The Role of Uremic Toxins

After acute kidney injury (AKI), renal function continues to deteriorate in some patients. In a pro-inflammatory and profibrotic environment, the proximal tubules are subject to maladaptive repair. In the AKI-to-CKD transition, impaired recovery from AKI reduces tubular and glomerular filtration and leads to chronic kidney disease (CKD). Reduced kidney secretion capacity is characterized by the plasma accumulation of biologically active molecules, referred to as uremic toxins (UTs). These toxins have a role in the development of neurological, cardiovascular, bone, and renal complications of CKD. However, UTs might also cause CKD as well as be the consequence. Recent studies have shown that these molecules accumulate early in AKI and contribute to the establishment of this pro-inflammatory and profibrotic environment in the kidney. The objective of the present work was to review the mechanisms of UT toxicity that potentially contribute to the AKI-to-CKD transition in each renal compartment.

The Role of Tryptophan Metabolism in the Occurrence and Progression of Acute and Chronic Kidney Diseases

Acute kidney injury (AKI) and chronic kidney disease (CKD) are common kidney diseases in clinics with high morbidity and mortality, but their pathogenesis is intricate. Tryptophan (Trp) is a fundamental amino acid for humans, and its metabolism produces various bioactive substances involved in the pathophysiology of AKI and CKD. Metabolomic studies manifest that Trp metabolites like kynurenine (KYN), 5-hydroxyindoleacetic acid (5-HIAA), and indoxyl sulfate (IS) increase in AKI or CKD and act as biomarkers that facilitate the early identification of diseases. Meanwhile, KYN and IS act as ligands to exacerbate kidney damage by activating aryl hydrocarbon receptor (AhR) signal transduction. The reduction of renal function can cause the accumulation of Trp metabolites which in turn accelerate the progression of AKI or CKD. Besides, gut dysbiosis induces the expansion of Enterobacteriaceae family to produce excessive IS, which cannot be excreted due to the deterioration of renal function. The application of Trp metabolism as a target in AKI and CKD will also be elaborated. Thus, this study aims to elucidate Trp metabolism in the development of AKI and CKD, and explores the relative treatment strategies by targeting Trp from the perspective of metabolomics to provide a reference for their diagnosis and prevention.

Effect of Glutamine Administration After Cardiac Surgery on Kidney Damage in Patients at High Risk for Acute Kidney Injury: A Randomized Controlled Trial

BACKGROUND

Acute kidney injury (AKI) is a common complication after cardiac surgery and is associated with increased morbidity and mortality. However, no specific treatment options are available, emphasizing the need for preventive measures. The aim of this study was to clarify the effect of glutamine on [TIMP2]*[IGFBP7] levels at the end of the intervention period.

METHODS

In a randomized clinical, double-blind pilot study, 64 eligible cardiac surgery patients at high risk for AKI identified by high urinary [TIMP2]*[IGFBP7] were randomized, and body weight-adapted intravenous glutamine or saline-control was administered continuously for 12 hours postoperatively. The primary outcome was urinary [TIMP2]*[IGFBP7] at the end of the 12-hour study period. Secondary outcomes included kidney injury molecule-1 (KIM-1) and neutrophil gelatinase-associated lipocalin (NGAL) at 12 hours, overall AKI rates at 72 hours, free days through day 28 of mechanical ventilation and vasoactive medication, renal recovery at day 90, requirement of renal replacement therapy and mortality each at days 30, 60, and 90, length of intensive care unit (ICU) and hospital stay, and major adverse kidney events consisting of mortality, dialysis dependency, and persistent renal dysfunction (serum creatinine ≥2× compared to baseline value) at day 90 (major adverse kidney event; MAKE 90 ).

RESULTS

Sixty-four patients (mean age, 68.38 [standard deviation {SD} ± 10.48] years; 10 of 64 women) were enrolled and randomized. Patients received coronary artery bypass graft surgery (32/64), valve surgery (18/64), coronary artery bypass graft and valve surgery (6/64), or other procedures (8/64). Mean on-pump time was 68.38 (standard deviation ± 10.48) minutes. After glutamine administration, urinary [TIMP-2]*[IGFBP7] was significantly lower in the glutamine compared to the control group (primary end point, intervention: median, 0.18 [Q1, Q3; 0.09, 0.29], controls: median, 0.44 [Q1, Q3; 0.14, 0.79]; P = .01). In addition, [KIM-1] and [NGAL] were also significantly lower in the glutamine group. The overall AKI rate within 72 hours was not different among groups: (intervention 11/31 [35.5%] versus control 8/32 [25.0%]; P = .419; relative risk [RR], 0.86% [95% confidence interval {CI}, 0.62-1.20]). There were no differences regarding secondary end points.

CONCLUSIONS

Glutamine significantly decreased markers of kidney damage in cardiac surgery patients at high risk for AKI. Future trials have to be performed to investigate whether the administration of glutamine might be able to reduce the occurrence of AKI after cardiac surgery.