Renal Neutrophil Research Articles

SARS-CoV-2 infection causes a decline in renal megalin expression and affects vitamin D metabolism in the kidney of K18-hACE2 mice

Patients with coronavirus disease 2019 (COVID-19) often experience acute kidney injury, linked to disease severity or mortality, along with renal tubular dysfunction and megalin loss in proximal tubules. Megalin plays a crucial role in kidney vitamin D metabolism. However, the impact of megalin loss on vitamin D metabolism during COVID-19 is unclear. This study investigated whether severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection reduces megalin expression in proximal tubules and its subsequent effect on vitamin D metabolism in mice expressing human angiotensin converting enzyme 2 (K18-hACE2 mice). Histological and immunohistochemical staining analyses revealed glomerular and capillary congestion, and elevated renal neutrophil gelatinase-associated lipocalin levels, indicative of acute kidney injury in K18-hACE2 mice. In SARS-CoV-2-infected mice, immunohistochemical staining revealed suppressed megalin protein levels. Decreased vitamin D receptor (VDR) localization in the nucleus and increased mRNA expression of VDR, CYP27B1, and CYP24A1 were observed by quantitative PCR in SARS-CoV-2-infected mice. Serum vitamin D levels remained similar in infected and vehicle-treated mice, but an increase in tumor necrosis factor-alpha and a decrease in IL-4 mRNA expression were observed in the kidneys of the SARS-CoV-2 group. These findings suggest that megalin loss in SARS-CoV-2 infection may impact the local role of vitamin D in kidney immunomodulation, even when blood vitamin D levels remain unchanged.

Sivelestat Sodium Alleviates Ischemia-Reperfusion-Induced Acute Kidney Injury via Suppressing TLR4/Myd88/NF-κB Signaling Pathway in Mice.

We aim to detect the effects of sivelestat on renal ischemia-reperfusion associated with AKI and also explore the underlying mechanism. Mice, aged between 8 and 12weeks, were randomly allocated among four distinct groups, respectively normal saline sham group(C), normal saline surgery group(I), sivelestat (50 mg/kg) sham group(S), sivelestat (50 mg/kg) surgery group(SI) (n=6, each group). In the surgical groups, the renal pedicles of mice were clamped withnon-traumatic micro-aneurysm clamps, resulting in ischemia of the kidneys for 45minutes. This was followed by a period of reperfusion lasting 24hours. Sham group mice underwent the identical surgery produced without clamping renal pedicles. Mice blood was obtained from eyeballs, and Serum creatinine and blood urea nitrogen levels were measured. After a 24-hour period of reperfusion, the mice were euthanized, and their kidneys were gathered for various analyses, including Western Blot (WB) analysis, RT-PCR, immunofluorescence (IF), hematoxylin and eosin (H&E) staining, and Tunel assay. Pretreatments with sivelestat decreased renal Neutrophil elastase (NE), serum creatinine, and blood urea nitrogen levels after renal ischemia-reperfusion. Sivelestat also reduced histological damage and cell apoptosis in kidneys following ischemia-reperfusion injury (IRI). In addition, thesivelestat administrationdiminished the levels of mRNA expression of interleukin 6 (IL-6), Macrophage inflammatory protein-2 (MIP-2), monocyte chemoattractant protein-1 (MCP-1), and tumor necrosis factor (TNF)-α in the kidneys during IRI.The kidney tissues of the SI group had significantly mitigated TLR4, Myd88, and NF-κB p-p65 protein expression levels compared to the I group (all P<0.05). We demonstrated a previously unidentified mechanism that sivelestat effectively attenuates AKI-induced renal dysfunction, possibly through suppressing the TLR4/Myd88/ NF-κB pathway.

Abstract P184: Increased Granulopoiesis, Kidney Neutrophil Infiltration, and Renal Damage in a Mouse Model of Psoriasis

Psoriasis is an autoimmune skin disease marked by T cell-mediated hyperproliferation of epidermal keratinocytes. Most psoriasis-related morbidity and mortality stems from an elevated risk of renal and cardiovascular disease, but mechanisms remain unclear. Although neutrophils are not directly targeted with current psoriasis therapies, neutrophils are increased in the skin and circulation of these patients. We hypothesized that excess skin inflammation in psoriasis drives increased G-CSF-dependent granulopoiesis leading to renal neutrophil infiltration and dysfunction. Employing a KC-Tie2 mouse model of psoriasis with keratinocyte-specific overexpression of the angiopoietin receptor Tie2 (KC-Tie2), we observed 2-3-fold elevations in multiple indices of renal damage including urine albumin, urine NGAL, and glomerulosclerosis in KC-Tie2 mice compared to littermate controls (all P&lt;0.05). KC-Tie2 mice also demonstrated 13 mm Hg higher daytime systolic blood pressure compared to littermate controls (P&lt;0.05). Using flow cytometry, we found that KC-Tie2 mice had an increase not only in cutaneous neutrophils but also an approximate 10-fold increase in renal neutrophils (P&lt;0.001). KC-Tie2 kidneys also exhibited increased vital and suicidal neutrophil extracellular trap (NET) formation, representing a potential mechanism for the observed renal damage. Interestingly, the increase in renal neutrophils was selective relative to other major immune cell populations such as dendritic cells, lymphocytes, monocytes, and macrophages. Similar selective increases in neutrophils were noted in the circulation, aorta, and spleen. We thus examined neutrophil production in the bone marrow, and observed significant increases in immature Ly6g low and Ly6g intermediate neutrophils (P&lt;0.0001) as well as total Ly6g + neutrophils (P&lt;0.05), with no change in mature Ly6g high neutrophils in the bone marrow of KC-Tie2 mice. These findings are consistent with increased granulopoiesis, prompting an examination of the key mediator of granulopoiesis, granulocyte colony-stimulating factor (G-CSF). KC-Tie2 mice exhibited marked increases in G-CSF in both the skin and plasma (P&lt;.001 for both). In conclusion, our findings demonstrate increased renal damage in a mouse model of psoriasis, concomitant with increases in granulopoiesis and total and NETotic renal neutrophils, potentially unveiling a novel link between skin inflammation and renal damage via enhanced G-CSF-mediated granulopoiesis.

Personalized prediction of mortality in patients with acute ischemic stroke using explainable artificial intelligence

BackgroundResearch into the acute kidney disease (AKD) after acute ischemic stroke (AIS) is rare, and how clinical features influence its prognosis remain unknown. We aim to employ interpretable machine learning (ML) models to study AIS and clarify its decision-making process in identifying the risk of mortality.MethodsWe conducted a retrospective cohort study involving AIS patients from January 2020 to June 2021. Patient data were randomly divided into training and test sets. Eight ML algorithms were employed to construct predictive models for mortality. The performance of the best model was evaluated using various metrics. Furthermore, we created an artificial intelligence (AI)-driven web application that leveraged the top ten most crucial features for mortality prediction.ResultsThe study cohort consisted of 1633 AIS patients, among whom 257 (15.74%) developed subacute AKD, 173 (10.59%) experienced AKI recovery, and 65 (3.98%) met criteria for both AKI and AKD. The mortality rate stood at 4.84%. The LightGBM model displayed superior performance, boasting an AUROC of 0.96 for mortality prediction. The top five features linked to mortality were ACEI/ARE, renal function trajectories, neutrophil count, diuretics, and serum creatinine. Moreover, we designed a web application using the LightGBM model to estimate mortality risk.ConclusionsComplete renal function trajectories, including AKI and AKD, are vital for fitting mortality in AIS patients. An interpretable ML model effectively clarified its decision-making process for identifying AIS patients at risk of mortality. The AI-driven web application has the potential to contribute to the development of personalized early mortality prevention.

PSTPIP2 ameliorates aristolochic acid nephropathy by suppressing interleukin-19-mediated neutrophil extracellular trap formation.

Aristolochic acid nephropathy (AAN) is a progressive kidney disease caused by herbal medicines. Proline-serine-threonine phosphatase-interacting protein 2 (PSTPIP2) and neutrophil extracellular traps (NETs) play important roles in kidney injury and immune defense, respectively, but the mechanism underlying AAN regulation by PSTPIP2 and NETs remains unclear. We found that renal tubular epithelial cell (RTEC) apoptosis, neutrophil infiltration, inflammatory factor, and NET production were increased in a mouse model of AAN, while PSTPIP2 expression was low. Conditional knock-in of Pstpip2 in mouse kidneys inhibited cell apoptosis, reduced neutrophil infiltration, suppressed the production of inflammatory factors and NETs, and ameliorated renal dysfunction. Conversely, downregulation of Pstpip2 expression promoted kidney injury. In vivo, the use of Ly6G-neutralizing antibody to remove neutrophils and peptidyl arginine deiminase 4 (PAD4) inhibitors to prevent NET formation reduced apoptosis, alleviating kidney injury. In vitro, damaged RTECs released interleukin-19 (IL-19) via the PSTPIP2/nuclear factor (NF)-κB pathway and induced NET formation via the IL-20Rβ receptor. Concurrently, NETs promoted apoptosis of damaged RTECs. PSTPIP2 affected NET formation by regulating IL-19 expression via inhibition of NF-κB pathway activation in RTECs, inhibiting RTEC apoptosis, and reducing kidney damage. Our findings indicated that neutrophils and NETs play a key role in AAN and therapeutic targeting of PSTPIP2/NF-κB/IL-19/IL-20Rβ might extend novel strategies to minimize Aristolochic acid I-mediated acute kidney injury and apoptosis.

Clinical profile analysis and nomogram for predicting in-hospital mortality among elderly severe community-acquired pneumonia patients: a retrospective cohort study

BackgroundSevere community-acquired pneumonia is one of the most lethal forms of CAP with high mortality. For rapid and accurate decisions, we developed a mortality prediction model specifically tailored for elderly SCAP patients.MethodsThe retrospective study included 2365 elderly patients. To construct and validate the nomogram, we randomly divided the patients into training and testing cohorts in a 70% versus 30% ratio. The primary outcome was in-hospital mortality. Univariate and multivariate logistic regression analyses were used in the training cohort to identify independent risk factors. The robustness of this model was assessed using the C index, ROC and AUC. DCA was employed to evaluate the predictive accuracy of the model.ResultsSix factors were used as independent risk factors for in-hospital mortality to construct the prediction model, including age, the use of vasopressor, chronic renal disease, neutrophil, platelet, and BUN. The C index was 0.743 (95% CI 0.719–0.768) in the training cohort and 0.731 (95% CI 0.694–0.768) in the testing cohort. The ROC curves and AUC for the training cohort and testing cohort (AUC = 0.742 vs. 0.728) indicated a robust discrimination. And the calibration plots showed a consistency between the prediction model probabilities and observed probabilities. Then, the DCA demonstrated great clinical practicality.ConclusionsThe nomogram incorporated six risk factors, including age, the use of vasopressor, chronic renal disease, neutrophil, platelet and BUN, which had great predictive accuracy and robustness, while also demonstrating clinical practicality at ICU admission.

Transition from acute kidney injury to chronic kidney disease in a long-term murine model of Shiga toxin-induced hemolytic-uremic syndrome.

Up to 40% of patients with typical hemolytic-uremic syndrome (HUS), characterized by microangiopathic hemolytic anemia and acute kidney injury (AKI), develop long-term consequences, most prominently chronic kidney disease (CKD). The transition from AKI to CKD, particularly in the context of HUS, is not yet fully understood. The objective of this study was to establish and characterize a Shiga toxin (Stx)-induced long-term HUS model to facilitate the study of mechanisms underlying the AKI-to-CKD transition. C57BL/6J mice were subjected to 5, 10, 15, or 20 ng/kg Stx on days 0, 3, and 6 of the experiment and were sacrificed on day 14 or day 21 to identify the critical time of turnover from the acute to the chronic state of HUS disease. Acute disease, indicated by weight loss, plasma neutrophil gelatinase-associated lipocalin (NGAL) and urea, and renal neutrophils, diminished after 14 days and returned to sham level after 21 days. HUS-associated hemolytic anemia transitioned to non-hemolytic microcytic anemia along with unchanged erythropoietin levels after 21 days. Renal cytokine levels indicated a shift towards pro-fibrotic signaling, and interstitial fibrosis developed concentration-dependently after 21 days. While Stx induced the intrarenal invasion of pro-inflammatory M1 and pro-fibrotic M2 macrophages after 14 days, pro-fibrotic M2 macrophages were the dominant phenotype after 21 days. In conclusion, we established and characterized the first Stx-induced long-term model of HUS. This tool facilitates the study of underlying mechanisms in the early AKI-to-CKD transition following HUS and allows the testing of compounds that may protect patients with AKI from developing subsequent CKD.

Sulfide:quinone oxidoreductase alleviates ferroptosis in acute kidney injury via ameliorating mitochondrial dysfunction of renal tubular epithelial cells

Ferroptosis is iron-dependent and regulates necrosis caused by lipid peroxidation and mitochondrial damage. Recent evidence has revealed an emerging role for ferroptosis in the pathophysiology of acute kidney injury (AKI). Sulfide:quinone oxidoreductase (SQOR) is a mitochondrial inner membrane protein highly expressed in the renal cortex. However, the effects of SQOR on ferroptosis and AKI have not been elucidated. In this study, we evaluated the effects of SQOR in several AKI models. We observed a rapid decrease in SQOR expression after cisplatin stimulation in both in vivo and in vitro models. SQOR-deletion mice exhibit exacerbated kidney impairment and ferroptosis in renal tubular epithelial cells following cisplatin injury. Additionally, our results showed that the overexpression of SQOR or ADT-OH (the slow-releasing H2S donor) preserved renal function in the three AKI mouse models. These effects were evidenced by lower levels of serum creatinine (SCr), blood urea nitrogen (BUN), renal neutrophil gelatinase-associated lipocalin (NGAL), and kidney injury molecule 1 (KIM-1). Importantly, SQOR knockout significantly aggravates cisplatin-induced ferroptosis by promoting mitochondrial dysfunction in renal tubular epithelial cells (RTECs). Moreover, online database analysis combined with our study revealed that SYVN1, an upregulated E3 ubiquitin ligase, may mediate the ubiquitin-mediated degradation of SQOR in AKI. Consequently, our results suggest that SYVN1-mediated ubiquitination degradation of SQOR may induce mitochondrial dysfunction in RTECs, exacerbating ferroptosis and thereby promoting the occurrence and development of AKI. Hence, targeting the SYVN1-SQOR axis could be a potential therapeutic strategy for AKI treatment.

Increased renal dysfunction and neutrophil infiltration in a mouse model of psoriasis

Psoriasis is a chronic inflammatory skin disease affecting 2-5% of the global population. As an autoimmune disease, psoriasis is characterized by T cell-mediated hyperproliferation of epidermal keratinocytes. Interestingly, most of the morbidity and mortality from psoriasis is related to increased risk of cardiovascular and renal disease. For example, moderate to severe psoriasis is associated with an approximately 1.5-fold increased risk of chronic kidney disease. Neutrophils are increased in the skin and circulation of patients with psoriasis, and markers of neutrophil activation are associated with extra-cutaneous manifestations of psoriasis including vascular inflammation. However, the molecular mechanisms linking psoriasis and kidney disease remain unclear. We hypothesized that increased neutrophil infiltration of the kidney through enhanced granulopoiesis promotes renal dysfunction in psoriasis. Using a KC-Tie2 mouse model of psoriasis with keratinocyte-specific overexpression of the angiopoietin receptor Tie2, we found that KC-Tie2 mice compared to littermate controls exhibit significantly increased urine albumin, suggestive of renal dysfunction. KC-Tie2 mice also exhibit significantly increased kidney/body weight and heart/body weight ratios compared to littermate controls. To determine a mechanism for the increased renal dysfunction in these mice, we assessed skin and renal immune cell content using flow cytometry. KC-Tie2 mice had increased neutrophils in the skin, as well as an approximately 10-fold increase in neutrophils in the kidneys. This increase in renal neutrophils in KC-Tie2 mice was relatively selective as there were no differences in the number of renal dendritic cells, lymphocytes, or monocytes and a modest but significant increase in macrophages. We also observed a selective increase in neutrophils in the spleen of KC-Tie2 mice. Given these findings and prior reports of increased circulating neutrophils in KC-Tie2 mice, we assessed mediators of granulopoiesis in the serum and found a significant increase in granulocyte colony stimulating factor (GCSF) in KC-Tie2 mice. Taken together, these results provide evidence for increased renal dysfunction in a mouse model of psoriasis coincident with marked increases in renal neutrophils that may represent a novel mechanism linking skin inflammation to renal dysfunction through enhanced granulopoiesis. MRA is funded by NIH K08HL153786-01. JM is funded by 2T32GM007569. NW is funded by NIH R01 AR075777, NIH R01 AR073196, NIH P50 CORT AR070590, and National Psoriasis Foundation. This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

THE DIAGNOSTIC VALUE OF URINE GELATINASE-ASSOCIATED LIPOCALIN AS A BIOMARKER FOR ACUTE KIDNEY INJURY IN PRETERM INFANTS WITH HEMODYNAMICALLY SIGNIFICANT PATENT DUCTUS ARTERIOSUS

THE DIAGNOSTIC VALUE OF URINE GELATINASE-ASSOCIATED LIPOCALIN AS A BIOMARKER FOR ACUTE KIDNEY INJURY IN PRETERM INFANTS WITH HEMODYNAMICALLY SIGNIFICANT PATENT DUCTUS ARTERIOSUS

Mineralocorticoid Receptor Antagonism Attenuates Multiple Organ Failure after Renal Ischemia and Reperfusion in Mice

Renal ischemia reperfusion (IR) injury is a major cause of acute kidney injury (AKI) that is often complicated by multiple organ failure of the liver and intestine. The mineralocorticoid receptor (MR) is activated in patients with renal failure associated with glomerular and tubular damage. We thus investigated whether canrenoic acid (CA), a mineralocorticoid receptor (MR) antagonist, protects against AKI-induced hepatic and intestinal injury, suggesting the underlying mechanisms. Mice were divided into five groups: sham mice, mice subjected to renal IR, and mice pretreated with canrenoic acid (CA; 1 or 10 mg/kg) 30 min prior to renal IR. At 24 h after renal IR, the levels of plasma creatinine, alanine aminotransferase and aldosterone were measured, and structural changes and inflammatory responses of the kidney, liver, and intestine were analyzed. We found that CA treatment reduced plasma creatinine levels, tubular cell death and oxidative stress induced by renal IR. CA treatment also decreased renal neutrophil infiltration and inflammatory cytokine expression and inhibited the release of high-mobility group box 1 induced by renal IR. Consistently, CA treatment reduced renal IR-induced plasma alanine transaminase, hepatocellular injury and neutrophil infiltration, and inflammatory cytokine expression. CA treatment also decreased small intestinal cell death, neutrophil infiltration and inflammatory cytokine expression induced by renal IR. Taken together, we conclude that MR antagonism by CA treatment protects against multiple organ failure in the liver and intestine after renal IR.

Naringin administration mitigates oxidative stress, anemia, and hypertension in lead acetate-induced cardio-renal dysfunction in cockerel chicks.

Lead is one of the major pollutants that is harmful to both animals and humans. It is found in every aspect of the environment such as the air, water, and soil. This pollutant affects both wild and domestic birds. Naringin has an active principle called flavonoid that has been found to have medicinal properties, mostly because of its antioxidant and metal chelating properties. This study was carried out to investigate the protective effect of naringin as an antioxidant against lead-induced anemia, cardio and nephrotoxicity, and hypertension. This study also aimed at elucidating the use of naringin as a heavy metal binder in poultry feed. Thirty-six cockerel chicks were used for this study, and randomly grouped into six groups per group; group A served as the control, group B received Pb-only (300ppm), group C (Pb and naringin; 80mg/kg), group D (Pb and naringin; 160mg/kg), group E (naringin 80mg/kg), and group F (naringin 160mg/kg), respectively, for 8weeks. Lead (Pb) was administered via drinking water, while naringin was administered via oral gavage. Lead acetate intoxication precipitated anemia as indicated by significant reductions in the values of PCV, RBC, and Hb concentration in lead-treated chicks when compared with the controls. Also, lead administration induced hypertension together with increased oxidative stress, depletion of the antioxidant defense system, reduced nitric oxide production, and an increase in high blood pressure. Immunohistochemistry indicated high expressions of cardiac troponin, renal angiotensin-converting enzymes, and renal neutrophil gelatinase-associated lipocalin. Treatment with naringin corrected anemia, reduced oxidative stress, improved antioxidant system, reduced high blood pressure, and offered protection against lead acetate-induced cardio-renal dysfunction in cockerel chicks. We recommend that naringin should be incorporated poultry feeds as a metal binder.

Abstract 128: Loss Of Gstm1 Augments Kidney Neutrophil Population In Angii-induced Hypertension

Background: Glutathione-S-transferase Mu1( Gstm1 ) gene, a member of Glutathione-S-transferases (GST) superfamily, encodes an enzyme that functions in the detoxification of electrophilic compounds. The common GSTM1 deletion variant in humans is associated with increased risks of chronic kidney disease (CKD) progression and incident end stage kidney failure. We reported that deletion of Gstm1 increases oxidative stress, kidney inflammation and injury in angiotensin II induced hypertension (Ang II-HTN) in mice. At 4 weeks of Ang II-HTN, neutrophils, CD4+T cells, and F4/80+ cells were significantly increased in Gstm1 knockout (KO) kidney. While a link between oxidative stress and immune activation in hypertension has been well documented, the molecular mechanism by which Gstm1 regulates immune cell activation in hypertension is unknown. Methods: To further characterize the inflammatory response in GSTM1 deficiency, Gstm1 KO and wild-type (WT) male mice at ~ 12 weeks of age were subjected to Angiotensin II at 1000 ng/kg per minute for 4 days via a mini osmotic pump. The kidney cells and bone marrow cells were isolated for flow cytometry analysis. Results: At baseline, there were no differences in inflammatory cell populations including neutrophils between WT and Gstm1 KO mice. At Day 4 of Ang II-HTN, Gstm1 KO kidneys exhibited about a 2.3 fold increase in neutrophil population (CD45 + Ly6G + CD11b + ), compared to WT control mice (10 WT and 8 Gstm1 KO mice, p=0.0075). Interestingly, CD45+ bone marrow cells isolated from both Gstm1 KO and WT mice have similar percentile of neutrophil populations ; however, neutrophils in Gstm1 KO bone marrow express relatively higher levels of CXCR2. Unlike at 4 weeks, there was no difference in other inflammatory cells at Day 4. Conclusion: Deletion of Gstm1 increases renal neutrophil population early in Ang II-HTN and CXCR2 expression in bone marrow neutrophils. Gstm1 may play a role in regulating neutrophil migration and recruitment. Further studies are needed to delineate whether GSTM1 deficiency drives kidney injury via early neutrophil migration, which could shed light on potential therapeutic target for CKD progression in those genetically susceptible.

Electrochemical detection of acute renal disease biomarker by Galinstan nanoparticles interfaced to bilayer polymeric structured dirhenium heptoxide film

This work describes a facile fabrication of an efficient electrochemical sensor utilizing sonication-derived Galinstan nanoparticles (Galinstan NPs) interfaced to annealed dirhenium heptoxide (Re2O7) thin-film on Silicon (Si) for the quantitative detection of the most promising acute renal disease biomarker Neutrophil Gelatinase Associated Lipocalin (NGAL). Under optimized preconditions, the anti-NGAL antibodies were immobilized on the Galinstan NPs/Re2O7/Si electrode by carbodiimide crosslinking to detect NGAL. The composition, morphology, and structural properties of the electrode were elucidated by various physical characterizations. The sensor obtained a high sensitivity (0.018 µA-1ng-1ml−1, R2 = 0.99) in differential pulse voltammetry and a minimum detection limit (2.14 ng ml−1) in electrochemical impedance spectroscopy for a wide range of NGAL concentrations (25–650 ng ml−1) with high selectivity and stability. The intensified performance of the sensor was achieved by the summed-up electron transfer from the Re2O7 film to Galinstan NPs and Galinstan NPs to the electroactive reactants. Additionally, the outer 2D gallium oxide (Ga2O3) layer of Galinstan Nps enhanced the redox activities, whereas the metallic core contributed to the magnificent conductivity. The excellent recovery rates of the sensor for different concentrations of NGAL measured in commercial human serum by the standard addition method assured the feasibility of the sensor.

Therapeutic effect of lycopene in lipopolysaccharide nephrotoxicity through alleviation of mitochondrial dysfunction, inflammation, and oxidative stress.

Sepsis-associated acute kidney injury (AKI) accompanies a higher mortality in intensive care patients. High-dose lipopolysaccharides (LPS) as an endotoxin is usually used to model AKI in rodents. Lycopene is a fat-soluble carotenoid with proved protective effects in different condition. Rationale and purpose of the study. This research work was designed to assess the effect of lycopene in LPS murine AKI. LPS was injected (intraperitoneally) at 10mg/kg to induce AKI and lycopene was given (orally) at 5 or 20mg/kg. Pretreatment of LPS group with lycopene (20mg/kg) lowered serum BUN, creatinine, and cystatin C and alleviated renal indices of oxidative stress consisting of malondialdehyde and reactive oxygen species and elevated level of catalase activity, superoxide dismutase activity, and glutathione peroxidase activity. In addition, lycopene (20mg/kg) attenuated renal neutrophil infiltration and reduced renal inflammation, improved mitochondrial membrane potential, and increased gene expression for PGC1-α as a key regulator of mitochondrial biogenesis. In addition, lycopene appropriately reduced level and gene expression of inflammation-related transcription factors including NF-kB and TLR4 and improved level and gene expression of Nrf2 as an important transcription factor related to antioxidant system. Besides, lycopene prevented histopathological changes following LPS in periodic acid-Schiff staining. Collectively, this study revealed that lycopene has favorable effects by means of amelioration of mitochondrial dysfunction, oxidative stress, and inflammation and accordingly could protect against LPS-induced AKI.

Modified chitosan for effective renal delivery of siRNA to treat acute kidney injury

Acute kidney injury (AKI) is characterized by a sudden decrease in renal function and impacts growing number of people worldwide. RNA interference (RNAi) showed potential to treat diseases with no or limited conventional therapies, including AKI. Suitable carriers are needed to protect and selectively deliver RNAi to target cells to fully explore this therapeutic modality. Here, we report on the synthesis of chitosan modified with α-cyclam-p-toluic acid (C-CS) as a novel siRNA carrier for targeted delivery to injured kidneys. We demonstrate that conjugation of the α-cyclam-p-toluic acid to chitosan imparts the C-CS polymer with targeting and antagonistic properties to cells overexpressing chemokine receptor CXCR4. In contrast, the parent α-cyclam-p-toluic acid showed no such properties. Self-assembled C-CS/siRNA nanoparticles rapidly accumulate in the injured kidneys and show long retention in renal tubules. Apoptosis and metabolic and inflammatory pathways induced by p53 are important pathological mechanisms in the development of AKI. Nanoparticles with siRNA against p53 (sip53) were formulated and intravenously injected for attenuation of IRI-AKI. Due to the favorable accumulation in injured kidneys, the treatment with C-CS/sip53 decreased renal injury, extent of renal apoptosis, macrophage and neutrophil infiltration, and improved renal function. Overall, our study suggests that C-CS/siRNA nanoparticles have the potential to effectively accumulate and deliver therapeutic siRNAs to injured kidneys through CXCR4 binding, providing a novel way for AKI therapy.

The Pathogenesis of Ischemia-Reperfusion Induced Acute Kidney Injury Depends on Renal Neutrophil Recruitment Whereas Sepsis-Induced AKI Does Not.

Acute kidney injury (AKI) may be induced by different causes, including renal ischemia-reperfusion injury and sepsis, which represent the most common reasons for AKI in hospitalized patients. AKI is defined by reduced urine production and/or increased plasma creatinine. However, this definition does not address the molecular mechanisms of different AKI entities, and uncertainties remain regarding distinct pathophysiological events causing kidney injury in the first place. In particular, sepsis-induced AKI is considered not to be associated with leukocyte infiltration into the kidney, but a direct investigation of this process is missing to this date. In this study, we used two murine AKI models induced by either renal ischemia-reperfusion injury (IRI) or cecal ligation and puncture (CLP) to investigate the contribution of neutrophils to tissue injury and kidney function. By using VEC-Y731F mice, in which neutrophil recruitment is impaired, we analyzed the specific contribution of neutrophil recruitment to the pathogenesis of IRI- and CLP-induced AKI. We observed that the degree of renal injury evaluated by plasma creatinine, urinary biomarkers and histological analyses, following IRI-induction was dependent on neutrophil migration into the kidney, whereas the pathogenesis of CLP-induced AKI was independent of neutrophil recruitment. Furthermore, plasma transfer experiments suggest that the pathogenesis of CLP-induced AKI relies on circulating inflammatory mediators. These results extend our knowledge of the AKI pathogenesis and may help in the development of prophylactic and therapeutic treatments for AKI patients.

A novel eCIRP/TREM-1 pathway inhibitor attenuates acute kidney injury

BackgroundExtracellular cold-inducible RNA-binding protein aggravates acute kidney injury after renal ischemia/reperfusion. Although extracellular cold-inducible RNA-binding protein activates triggering receptor expressed on myeloid cells-1, how this receptor and its antagonism with a novel peptide M3 affects acute kidney injury is poorly understood. We, therefore, hypothesize that inhibiting the extracellular cold-inducible RNA-binding protein/triggering receptor expressed on myeloid cells-1 pathway with M3 attenuates acute kidney injury. MethodsWild-type and triggering receptor expressed on myeloid cells-1-/- mice were subjected to bilateral 30-minute renal hilum clamping followed by reperfusion or sham. After 4 hours, wild-type mice received M3 (10 mg/kg BW) or normal saline intraperitoneally. After 24 hours, renal tissue and serum were collected for analysis. Additionally, wild-type mice were subjected to bilateral renal ischemia for 34 minutes and treated with M3 at 10 mg/kg BW or vehicle at the time of reperfusion. Survival was monitored for 10 days. ResultsAfter renal ischemia/reperfusion, triggering receptor expressed on myeloid cells-1 messenger ribonucleic acid expression increased by 9-fold in wild-type mice compared to sham mice. Wild-type mice also demonstrated significant increases in serum blood urea nitrogen, creatinine, and interleukin-6 and renal tissue levels of interleukin-6 and neutrophil gelatinase-associated lipocalin after renal ischemia/reperfusion compared to sham mice. Triggering receptor expressed on myeloid cells-1-/- mice demonstrated significant reductions in serum blood urea nitrogen, creatinine, and interleukin-6 compared to wild-type mice after renal ischemia/reperfusion. Levels of renal interleukin-6 and neutrophil gelatinase-associated lipocalin were also significantly decreased in the kidneys of triggering receptor expressed on myeloid cells-1-/- mice. Furthermore, treatment with M3 in wild-type mice significantly decreased serum and renal levels of interleukin-6 after renal ischemia/reperfusion. M3 treatment demonstrated significant reductions in renal messenger ribonucleic acid and protein levels of neutrophil gelatinase-associated lipocalin, serum blood urea nitrogen and creatinine, and histologic structural damage as well as apoptosis. Treatment with M3 also increased survival from 35% to 65% in mice with acute kidney injury. ConclusionTriggering receptor expressed on myeloid cells-1 mediates the deleterious effects of extracellular cold-inducible RNA-binding protein in acute kidney injury after renal ischemia/reperfusion. The novel extracellular cold-inducible RNA-binding protein/triggering receptor expressed on myeloid cells-1 pathway antagonist, M3, attenuates acute kidney injury and has the potential to be developed as a therapeutic agent for acute kidney injury.

Salidroside Protects Acute Kidney Injury in Septic Rats by Inhibiting Inflammation and Apoptosis.

PurposeTo clarify the protective effect and mechanism of salidroside (SLDS) on acute kidney injury (AKI) in septic rats.MethodsWe pretreated rats with different doses of SLDS and analyzed the impact of SLDS on the survival of septic rats. We evaluated the levels of inflammatory factors in rats, the expression of NF-ƙB p65 in the kidney, and the apoptosis of kidney tubular epithelial cells (KTECs).ResultsSLDS significantly decreased the mortality of septic rats, and it reduced the levels of TNF-α, IL-1β, and IL-17A in plasma and kidneys and decreased the levels of serum creatinine, plasma renal injury molecule-1 and plasma neutrophil gelatin-associated lipocalin. Moreover, SLDS could significantly decrease the expression of NF-ƙB p65 in kidney tissues and the apoptotic number of KETCs, while reducing the mRNA levels of Caspase-3 and Bax mRNA, and increasing the level of Bcl-2 mRNA.ConclusionSLDS pretreatment protects against AKI in septic rats by inhibiting the inflammation of kidney and the apoptosis of KTECs.

Urinary Biomarkers of Renal Injury KIM-1 and NGAL: Reference Intervals for Healthy Pediatric Population in Sri Lanka.

Emerging renal biomarkers (e.g., kidney injury molecule-1 (KIM-1) and neutrophil gelatinase-associated lipocalin (NGAL)) are thought to be highly sensitive in diagnosing renal injury. However, global data on reference intervals for emerging biomarkers in younger populations are lacking. Here, we aimed to determine reference intervals for KIM-1 and NGAL across a pediatric population in Sri Lanka; a country significantly impacted by the emergence of chronic kidney disease of unexplained etiology (CKDu). Urine samples were collected from children (10–18 years) with no prior record of renal diseases from the dry climatic zone of Sri Lanka (N = 909). Urinary KIM-1 and NGAL concentrations were determined using the enzyme-linked immunosorbent assay (ELISA) and adjusted to urinary creatinine. Biomarker levels were stratified by age and gender, and reference intervals derived with quantile regression (2.5th, 50th, and 97.5th quantiles) were expressed at 95% CI. The range of median reference intervals for urinary KIM-1 and NGAL in children were 0.081–0.426 ng/mg Cr, 2.966–4.850 ng/mg Cr for males, and 0.0780–0.5076 ng/mg Cr, 2.0850–3.4960 ng/mg Cr for females, respectively. Renal biomarkers showed weak correlations with age, gender, ACR, and BMI. Our findings provide reference intervals to facilitate screening to detect early renal damage, especially in rural communities that are impacted by CKDu.