Renal neutrophil gelatinase associated lipocalin expression in lipopolysaccharide-induced acute kidney injury in the rat

Cordyceps sinensis extract protects against acute kidney injury by inhibiting perforin expression in NK cells via the STING/IRF3 pathway

Acute kidney injury (AKI) is associated with immune cell activation and inflammation. However, the putative pathogenic mechanisms of this injury have not been thoroughly investigated. Natural killer (NK) cells play an important role in immune regulation; however, whether NK cells regulate AKI remains unclear. Cordyceps sinensis (CS), a modern Chinese patented medicine preparation, has been widely used in treating patients with chronic kidney disease (CKD) owing to its anti-inflammatory effects and maintenance of immune homeostasis. Whether 2'-deoxyadenosine, a major active component in CS, can ameliorate renal AKI by regulating immunity, particularly in NK cells, has not been reported. This study is the first to demonstrate how NK cells promote AKI by releasing perforin, interferon-gamma (IFN-γ) and other inflammatory factors in vivo and in vitro. Differential gene expression between AKI and normal tissues was assessed using bioinformatic analyses. Quantitative real-time PCR, western blotting, and immunohistochemical staining were used to detect target protein mRNA and protein expression. Levels of inflammatory factors were measured using enzyme-linked immunosorbent assay. We found the high doses of the 2'-deoxyadenosine treatment significantly alleviated FA-induced renal damage in vivo, and alleviated the NK cells of renal injury by activating the STING/IRF3 pathway to inhibit perforin release in vitro. The results showed that 2'-deoxyadenosine could mitigate AKI by downregulating the activity of NK cells (by decreasing the expressions of perforin and IFN-γ) and inhibiting the stimulator of interferon genes and phosphorylated IFN regulatory factor 3. This may provide valuable evidence supporting the clinical use of CS in treating patients with AKI.

Calcium trafficking and gastrointestinal physiology following an acute lipopolysaccharide challenge in pigs

The influence of systemic immune activation on whole-body calcium (Ca) trafficking and gastrointestinal tract (GIT) physiology is not clear. Thus, the study objectives were to characterize the effects of lipopolysaccharide (LPS) on Ca pools and GIT dynamics to increase understanding of immune-induced hypocalcemia, ileus, and stomach hemorrhaging. Twelve crossbred pigs [44 ± 3 kg body weight (BW)] were randomly assigned to 1 of 2 intramuscular treatments: (1) control (CON; 2 mL saline; n = 6) or (2) LPS (40 µg LPS/kg BW; n = 6). Pigs were housed in metabolism stalls to collect total urine and feces for 6 h after treatment administration, at which point they were euthanized, and various tissues, organs, fluids, and digesta were weighed, and analyzed for Ca content. Data were analyzed with the MIXED procedure in SAS 9.4. Rectal temperature and respiration rate increased in LPS relative to CON pigs (1.4 °C and 32%, respectively; P ≤ 0.05). Inflammatory biomarkers such as circulating alkaline phosphatase, aspartate aminotransferase, and total bilirubin increased in LPS compared with CON pigs whereas albumin decreased (P ≤ 0.02). Plasma glucose and urea nitrogen decreased and increased, respectively, after LPS (43% and 80%, respectively; P < 0.01). Pigs administered LPS had reduced circulating ionized calcium (iCa) compared to CON (15%; P < 0.01). Considering estimations of total blood volume, LPS caused an iCa deficit of 23 mg relative to CON (P < 0.01). Adipose tissue and urine from LPS pigs had reduced Ca compared to CON (39% and 77%, respectively; P ≤ 0.05). There did not appear to be increased Ca efflux into GIT contents and no detectable increases in other organ or tissue Ca concentrations were identified. Thus, while LPS caused hypocalcemia, we were unable to determine where circulating Ca was trafficked. LPS administration markedly altered GIT dynamics including stomach hemorrhaging, diarrhea (increased fecal output and moisture), and reduced small intestine and fecal pH (P ≤ 0.06). Taken together, changes in GIT physiology suggested dyshomeostasis and alimentary pathology. Future research is required to fully elucidate the etiology of immune activation-induced hypocalcemia and GIT pathophysiology.

Mercuric Chloride Induced Nephrotoxicity: Ameliorative Effect of Carica papaya Leaves Confirmed by Histopathology, Immunohistochemistry, and Gene Expression Studies

The present study analyzes the efficacy of the ethanolic extract of C. papaya leaves (ECP) against HgCl₂-induced nephrotoxicity. The effects on the biochemical and percentage of body and organ weight against HgCl₂-induced nephrotoxicity in female Wistar rats were studied. Wistar rats were divided into five groups with six animals in each group: control, HgCl₂ (2.5 mg/kg b.w.), N-acetylcysteine (NAC 180 mg/kg) + HgCl₂, ECP (300 mg/kg b.w.) + HgCl₂, and ECP (600 mg/kg) + HgCl₂ groups. After 28 days of study, animals were sacrificed on the 29th day to harvest the blood and kidneys for further analysis. The effect ECP was analyzed by immunohistochemistry (NGAL) and real-time PCR (KIM-1 and NGAL mRNA) in HgCl₂-induced nephrotoxicity. The results revealed that the HgCl₂ group showed prominent damage in the proximal tubules and glomerulus of nephrons and enormous expression of NGAL in immunohistochemistry and KIM-1 and NGAL in real-time PCR compared to the control group. The simultaneous pretreatment with NAC (180 mg/kg) and ECP (600 and 300 mg/kg) reduced renal damage and expression of NGAL in immunohistochemistry and KIM-1 and NGAL gene in real-time PCR. This study attests to the nephroprotective effect of ECP against HgCl₂-induced toxicity.

Dietary docosahexaenoic acid reduces fat deposition and alleviates liver damage induced by D-galactosamine and lipopolysaccharides in Nile tilapia (Oreochromis niloticus)

Liver health is important to maintain survival and growth of fish. Currently, the role of dietary docosahexaenoic acid (DHA) in improving fish liver health is largely unknown. This study investigated the role of DHA supplementation in fat deposition and liver damage caused by D-galactosamine (D-GalN) and lipopolysaccharides (LPS) in Nile tilapia (Oreochromis niloticus). Four diets were formulated as control diet (Con), Con supplemented with 1 % DHA, 2 % DHA and 4 % DHA diets, respectively. The diets were fed to 25 Nile tilapia (2.0 ± 0.1 g, average initial weight) in triplicates for four weeks. After the four weeks, 20 fish in each treatment were randomly selected and injected with a mixture of 500 mg D-GalN and 10 μL LPS per mL to induce acute liver injury. The results showed that the Nile tilapia fed on DHA diets decreased visceral somatic index, liver lipid content and serum and liver triglyceride concentrations than those fed on the Con diet. Moreover, after D-GalN/LPS injection, the fish fed on DHA diets decreased alanine aminotransferase and aspartate transaminase activities in the serum. The results of liver qPCR and transcriptomics assays together showed that the DHA diets feeding improved liver health by downregulating the expression of the genes related to toll-like receptor 4 (TLR4) signaling pathway, inflammation and apoptosis. This study indicates that DHA supplementation in Nile tilapia alleviates the liver damage caused by D-GalN/LPS through increasing lipid catabolism, decreasing lipogenesis, TLR4 signaling pathway, inflammation, and apoptosis. Our study provides novel knowledge on the role of DHA in improving liver health in cultured aquatic animals for sustainable aquaculture.

The Role of Urinary NGAL in the Management of Primary Vesicoureteral Reflux in Children

Vesicoureteral reflux (VUR) is the most frequent congenital urinary tract malformation and an important risk factor for urinary tract infections (UTIs). Up to 50% of children with VUR may develop reflux nephropathy (RN), and the diagnosis and monitoring of renal scars are invasive and costly procedures, so it is paramount to find a non-invasive and accurate method to predict the risk of renal damage. Neutrophil gelatinase-associated lipocalin (NGAL) has already proven to be a good predictive biomarker in acute kidney injuries, but there are few studies that have investigated the role of NGAL in primary VUR in children. Our aim is to review the predictive value of urine NGAL (uNGAL) as a non-invasive biomarker of RN in children with primary VUR, as well as its ability to predict the evolution of chronic kidney disease (CKD). Based on our analysis of the available original studies, uNGAL can be an accurate and reliable biomarker of RN and its progression to CKD. Some studies suggested a good correlation between VUR severity and uNGAL levels, but other studies found no significant correlation. The relationship between VUR severity and uNGAL levels is likely complex and influenced by factors such as UTIs, the timing of the urine sample collection, and the age and overall health of the patient.

New experimental model of kidney injury: Photothrombosis-induced kidney ischemia

Acute kidney injury (AKI) is a frequent pathology with a high mortality rate after even a single AKI episode and a great risk of chronic kidney disease (CKD) development. To get insight into mechanisms of the AKI pathogenesis, there is a need to develop diverse experimental models of the disease. Photothrombosis is a widely used method for inducing ischemia in the brain. In this study, for the first time, we described photothrombosis-induced kidney ischemia as an appropriate model of AKI and obtained comprehensive characteristics of the photothrombotic lesion using micro-computed tomography (micro-CT) and histological techniques. In the ischemic area, we observed destruction of tubules, the loss of brush border and nuclei, connective tissue fibers disorganization, leukocyte infiltration, and hyaline casts formation. In kidney tissue and urine, we revealed increased levels in markers of proliferation and injury. The explicit long-term consequence of photothrombosis-induced kidney ischemia was renal fibrosis. Thus, we establish a new low invasive experimental model of AKI, which provides a reproducible local ischemic injury lesion. We propose our model of photothrombosis-induced kidney ischemia as a useful approach for investigating AKI pathogenesis, studying the mechanisms of kidney regeneration, and development of therapy against AKI and CKD.

Exosomes Derived from BM-MSCs Mitigate the Development of Chronic Kidney Damage Post-Menopause via Interfering with Fibrosis and Apoptosis

The rate of chronic kidney disease (CKD) is increasing globally, and it is caused by continuous damage to kidney tissue. With time the renal damage becomes irreversible, leading to CKD development. In females, post-menopause lack of estrogen supply has been described as a risk factor for CKD development, and studies targeting post-menopause CKD are scarce. In the present study, we used exosomes isolated from bone marrow mesenchymal stem/stromal cells (BM-MSCs) to test their therapeutic potential against the development of CKD. At first, the menopause model was achieved by surgical bilateral ovariectomy in female albino rats. After that, 100 µg of exosomes was given to ovariectomized rats, and the study continued for 2 months. Changes in urine volume, urine protein content, kidney function biochemical parameters (creatinine and BUN), kidney antioxidant parameters (SOD, GPx and CAT), histological changes, immunohistochemical levels of caspase 3, and the gene expression of NGAL (related to kidney damage), TGFβ1 and αSMA (related to fibrosis and EMT), and caspase 3 (related to apoptosis) were studied. After the ovariectomy, the occurrence of CKD was confirmed in the rats by the drastic reduction of serum estrogen and progesterone levels, reduced urine output, increased urinary protein excretion, elevated serum creatinine and BUN, reduced GPx SOD, and CAT in kidney tissue, degenerative and fibrotic lesions in the histopathological examination, higher immunohistochemical expression of caspase 3 and increased expression of all studied genes. After exosomes administration, the entire chronic inflammatory picture in the kidney was corrected, and a near-normal kidney structure and function were attained. This study shows for the first time that BM-MSCs exosomes are potent for reducing apoptosis and fibrosis levels and, thus, can reduce the chronic damage of the kidneys in females that are in their menopause period. Therefore, MSCs-derived exosomes should be considered a valuable therapy for preserving postmenopausal kidney structure and function and, subsequently, could improve the quality of females’ life during menopause.

Universal Accessible Biomarkers of Drug-Induced Tissue Injury and Systemic Inflammation in Rat: Performance Assessment of TIMP-1, A2M, AGP, NGAL and Albumin

The ability to monitor for general drug-induced tissue injury (DITI) or systemic inflammation in any tissue using blood-based accessible biomarkers would provide a valuable tool in early exploratory animal studies to understand potential drug liabilities. Here we describe the evaluation of four biomarkers of tissue remodeling and inflammation [α2-macroglobin (A2M), α1-acid glycoprotein (AGP), neutrophil gelatinase-associated lipocalin (NGAL) and tissue inhibitor of metalloproteinases (TIMP-1)] as well as the traditional serum parameter albumin as potential blood-based biomarkers of DITI and systemic inflammatory response (SIR). Biomarker performance was assessed in 51 short-term rat in vivo studies with various end-organ toxicities or SIR and receiver operator characteristic (ROC) curves were generated to compare relative performances. All four biomarkers performed well in their ability to detect DITI and SIR with an area under the curve (AUC) of 0.82 - 0.78, however TIMP-1 achieved the best sensitivity (at 95% specificity) of 61%; AGP, NGAL, and A2M sensitivity was 51-52%. AUC for albumin was 0.72 with sensitivity of 39%. A2M was the best performer in studies with only SIR (AUC 0.91). In the subset of studies with drug-induced vascular injury, TIMP-1 performed best with an AUC of 0.96. Poor performance of all tested biomarkers was observed in samples with CNS toxicity. In summary, TIMP-1, A2M, AGP and NGAL demonstrated performance as sensitive accessible biomarkers of DITI and SIR, supporting their potential application as universal accessible tissue toxicity biomarkers to quickly identify dose levels associated with drug-induced injury in early exploratory rat safety and other studies.

The Proximal Tubule as the Pathogenic and Therapeutic Target in Acute Kidney Injury

BACKGROUND

In 2004, the term acute kidney injury (AKI) was introduced with the intention of broadening our understanding of rapid declines in renal function and to replace the historical terms of acute renal failure and acute tubular necrosis (ATN). Despite this evolution in terminology, the mechanisms of AKI have stayed largely elusive with the pathophysiological concepts of ATN remaining the mainstay in our understanding of AKI.

SUMMARY

The proximal tubule (PT), having the highest mitochondrial content in the kidney and relying heavily on oxidative phosphorylation to generate ATP, is vulnerable to ischaemic insults and mitochondrial dysfunction. Histologically, pathological changes in the PT are more consistent than changes to the glomeruli or the loop of Henle in AKI. Physiologically, activation of tubuloglomerular feedback due to PT dysfunction leads to an increase in preglomerular afferent arteriole resistance and a reduction in glomerular filtration. Pharmacologically, frusemide - a drug commonly used in the setting of oliguric AKI - is actively secreted by the PT and its diuretic effect is compromised by its failure to be secreted into the urine and thus be delivered to its site of action at the loop of Henle in AKI. Increases in the urinary, but not plasma biomarkers, of PT injury within 1 h of shock suggest that the PT as the initiation pathogenic target of AKI.

KEY MESSAGE

Therapeutic agents targeting specifically the PT epithelial cells, in particular its mitochondria - including amino acid ergothioneine and superoxide scavenger MitoTEMPO - show great promises in ameliorating AKI.

Kidney Cancer and Chronic Kidney Disease: Too Close for Comfort

Kidney cancer and chronic kidney disease are two renal pathologies with very different clinical management strategies and therapeutical options. Nonetheless, the cellular and molecular mechanisms underlying both conditions are closely related. Renal physiology is adapted to operate with a limited oxygen supply, making the kidney remarkably equipped to respond to hypoxia. This tightly regulated response mechanism is at the heart of kidney cancer, leading to the onset of malignant cellular phenotypes. Although elusive, the role of hypoxia in chronic kidney diseases is emerging as related to fibrosis, a pivotal factor in decaying renal function. The present review offers a perspective on the common biological traits shared between kidney cancer and chronic kidney disease and the available and prospective therapies for both conditions.

Neutrophil Gelatinase-Associated Lipocalin Contributes to Increased Risk of Cardiovascular Death After Acute Coronary Syndrome

Background

Neutrophil gelatinase-associated lipocalin (NGAL) has been suggested to reflect early renal dysfunction. We investigated the predictive significance of serum NGAL in predicting cardiovascular (CV) death in an old-age population with coronary heart disease (CHD).

Methods

In total, 633 CHD patients with a stable clinical condition were enrolled. The measurements of serum NGAL and other laboratory indices were performed within 24 hours after admission. Adjusted analysis was used to assess relationships between serum NGAL and CV death during the 10-year follow-up period.

Results

Multivariate logistic regression analysis demonstrated that elevated NGAL levels were related to a higher prevalence of CV disease history [quartile 4, 2.41 (1.60–4.59), P-trend <0.001]. The Kaplan–Meier curve indicated that patients with high NGAL levels tended to have a higher rate of CV death than patients with low NGAL levels. A multivariate Cox model suggested that increased levels of NGAL were independently linked with elevated risk of CV death (HR=2.62, 95% CI 1.51–4.96, P<0.001) during the 10-year follow-up period, after adjusting for related confounding factors using sensitivity analysis. Furthermore, the receiver operating characteristics (ROC) curve demonstrated that serum NGAL (AUC=0.917, 95% CI 0.895–0.940, P<0.001) had an ideal predictive value in predicting CV death.

Conclusion

Serum levels of NGAL were elevated in patients with CHD and may be a new parameter that could independently predict CV death in these patients, which may strengthen its potential application in clinical practice.

Knockout of NGAL aggravates tubulointerstitial injury in a mouse model of diabetic nephropathy by enhancing oxidative stress and fibrosis

Neutrophil gelatinase-associated lipocalin (NGAL), also called lipocalin 2, is considered a promising biomarker for acute and chronic kidney injuries. Several studies have demonstrated that its levels increase in plasma and urine in diabetic nephropathy (DN), and its urine concentration increases upon kidney function deterioration. However, its role in DN progression remains unclear. The current study used in vitro gene expression knockdown in human proximal tubular cell line human kidney (HK)2 to investigate the role of NGAL in oxidation and extracellular matrix secretion under high-glucose (HG) incubation. In addition, type 1 diabetes was induced in vivo in knockout NGAL^-/- and wild-type mice in order to investigate role of NGAL in the progression of DN. The results demonstrated that NGAL knockdown in HK2 cells significantly increased oxidative stress under HG stimulation tested by flow cytometry, and increased the secretion of interleukin-6, fibronectin (FN) and collagen IV examined by ELISA. Western blotting demonstrated that the phosphorylation of Smad2/3 also increased in HK2 cells under transforming growth factor-β1 stimulation. In vivo experiments demonstrated that diabetic NGAL^-/- mice showed deteriorated renal function compared with that of diabetic wild-type mice. Histopathological analysis suggests that diabetic NGAL^-/- mice had more serious glomerulosclerosis and tubular vascular degeneration than wild-type mice. Immunohistochemistry suggested that the absence of NGAL lead to increased FN deposition in glomeruli in a mouse model of DN. In conclusion, NGAL appears to have renal protective effects by slowing down the progression of DN, and its effect may be associated with a reduction in oxidation, fibrosis and inflammation.

Neutrophil Gelatinase-associated Lipocalin as a Marker of Postoperative Acute Kidney Injury Following Cardiac Surgery in Patients with Preoperative Kidney Impairment

INTRODUCTION

Acute kidney injury (AKI) is a serious complication of cardiac surgery. The current 'gold standard' for determining AKI is change in serum creatinine and urine output, however, this change occurs relatively late after the actual injury occurs. Identification of new biomarkers that detect early AKI is required. Recently, new biomarkers, such as the NephroCheck® Test and AKIRisk have also been tested and found to be good indicators of AKI. Neutrophil gelatinase-associated lipocalin (NGAL) has shown promise in paediatric patients but has displayed varied results in adult populations, particularly post cardiac surgery. The aim of this study was to assess the value of urinary NGAL as a biomarker of AKI in patients with pre-existing renal impairment (eGFR >15ml/min to eGFR<60ml/min).

METHODS

A post-hoc analysis of urinary NGAL concentrations from 125 patients with pre-existing kidney impairment, who participated in a randomised trial of haemofiltration during cardiac surgery, was undertaken. Urinary NGAL was measured using ELISA at baseline, post-operatively and 24 and 48 hours after surgery, and serum creatinine was measured pre and postoperatively and then at 24, 48, 72 and 96 hours as routine patient care. NGAL concentrations were compared in patients with and without AKI determined by changes in serum creatinine concentrations. A Kaplan-Meier plot compared survival for patients with or without AKI and a Cox proportional hazards analysis was performed to identify factors with the greatest influence on survival.

RESULTS

Following surgery, 43% of patients developed AKI (based on KDIGO definition). Baseline urinary NGAL was not found to be significantly different between patients that did and did not develop AKI. Urinary NGAL concentration was increased in all patients following surgery, regardless of whether they developed AKI and was also significant between groups at 24 (p=0.003) and 48 hours (p<0.0001). Urinary NGAL concentrations at 48 hours correlated with serum creatinine concentrations at 48 hours (r=0.477, p<0.0001), 72 hours (r=0.488, p<0.0001) and 96 hours (r=0.463, p<0.0001). Urinary NGAL at 48 hours after surgery strongly predicted AKI (AUC=0.76; P=0.0001). A Kaplan- Meier plot showed that patients with postoperative AKI had a significantly lower 7-year survival compared with those without AKI. Postoperative urinary NGAL at 48 hours >156ng/mL also strongly predicted 7-year survival. However, additive EuroSCORE, age, current smoking and post-operative antibiotics usage were distinctly significantly more predictive of 7-year survival as compared with postoperative urinary NGAL at 48 hours >156ng/mL.

CONCLUSIONS

Our study demonstrated that postoperative urinary NGAL levels at 48 hours postsurgery strongly predicts the onset or severity of postoperative AKI based on KDIGO classification in patients with preoperative kidney impairment and were also strongly related to 7-year survival.

Local anesthetic articaine ameliorates LPS-induced acute kidney injury via inhibition of NF-ĸB activation and the NLRP3 inflammasome pathway

The present study was conducted to determine the protective effect of articaine (ART) in an lipopolysaccharide (LPS)-induced acute kidney injury (AKI) animal model. The results suggest ART causes a significant decrease in serum blood urea nitrogen, creatinine, and serum cystatin C level, showing a protective effect against LPS-induced AKI. This has been further supported by histopathological findings of kidney tissues. The level of tumor necrosis factor-α, interleukin (IL)-6, and IL-1β in serum and kidney tissues was remarkably inhibited by ART in a dose-dependent manner. ART causes a significant reduction of malondialdehyde and increases the activities of glutathione and superoxide dismutase with an increase in dose as compared to the LPS-treated group. Moreover, the ART-treated group showed dose-dependent inhibition of LPS-induced nuclear factor-κB activation and TLR4 expression as confirmed by Western blot analysis. The level of Bcl-2 family genes (Bcl-2 and Bax) was restored near to normal by ART. Collectively, all the above results indicated that ART had protective effects against LPS-induced AKI by blocking inflammatory and oxidative responses.

Prediction Value of Serum NGAL in the Diagnosis and Prognosis of Experimental Acute and Chronic Kidney Injuries

Sensitive and accurate serum biomarkers for monitoring acute and chronic kidney disease progression are more convenient and can better evaluate drug efficiency in pharmacological research. Neutrophil Gelatinase-associated Lipocalin (NGAL) is considered a hopeful early biomarker of acute kidney injury (AKI), but its utility in early prediction and prognosis of diabetic nephropathy (DN) and immune-mediated glomerulonephritis is still not clear. Moreover, detailed prognosis studies of NGAL in AKI are lacking, and most studies use a urine source. In the current study, through two experimental AKI and two chronic kidney injury animal models, serum NGAL (sNGAL) prediction values on diagnosis and prognosis of kidney injuries in animal disease models have been investigated thoroughly. Four experimental kidney disease models include cisplatin-induced and lipopolysaccharide (LPS)-induced AKI, streptozocin-induced diabetic nephropathy (DN), and cationized-bovine serum albumin (c-BSA)-induced membranous nephropathy (MN), respectively. The sNGAL concentration was measured at different stages of kidney injury (KI) in each experimental model, and receiver operating characteristic (ROC) analyses were performed to investigate the diagnosis efficiency of sNGAL for KI. Western blot and immunohistochemistry were used to measure the protein levels in the kidneys, and pathological analysis was used as the gold standard to confirm KI. Results suggest that sNGAL can predict early diagnosis of cisplatin-induced AKI accurately but is less powerful in later stages compared to blood urea nitrogen (BUN) and serum creatinine (Scr). sNGAL is sensitive but lacks specificity to evaluate early kidney injury for LPS-induced AKI under low-dosage LPS challenge. sNGAL is not an efficient biomarker for early diagnosis of STZ-induced DN, but sNGAL is an efficient predictor for the early diagnosis and prognosis of immune-mediated MN. In conclusion, application of sNGAL as a kidney injury biomarker to determine the diagnosis and prognosis in pharmacological studies is dependent on experimental animal models.

Spirogyra neglecta Aqueous Extract Attenuates LPS-Induced Renal Inflammation

Spirogyra neglecta (SN), commonly named "Tao" in Thai, is a genus of filamentous green macroalgae. SN contains polyphenols such as isoquercetin, catechin, hydroquinone and kaempferol. These constituents exhibit beneficial effects including anti-oxidant, anti-gastric ulcer, anti-hyperglycaemia and anti-hyperlipidaemia in both in vitro and in vivo models. Whether SN extract (SNE) has an anti-inflammatory effect in vivo remains unclear. This study examined the effect of SNE on renal function and renal organic transport in lipopolysaccharide (LPS)-induced renal inflammation in rats. Rats were randomised and divided into normal saline (NS), NS supplemented with 1000 mg/kg body weight (BW) of SNE (NS + SNE), intraperitoneally injected with 12 mg/kg BW of LPS and LPS treated with 1000 mg/kg BW of SNE (LPS + SNE). Biochemical parameters in serum and urine, lipid peroxidation concentration, kidney function and renal organic anion and cation transports were determined. LPS-injected rats developed renal injury and inflammation by increasing urine microalbumin, total malondialdehyde (MDA) and inflammatory cytokines, tumor necrosis factor (TNF)-α and interleukin (IL)-1β protein expression, respectively. In addition, uptake of renal organic anion, [³H]-oestrone sulphate (ES), was reduced in LPS-injected rats together with increased expression of organic anion transporter 3 (Oat3). However, the renal injury and inflammation, as well as impaired Oat3 function and protein expression, were restored in LPS + SNE rats. Accordingly, SNE could be developed as nutraceutical product to prevent inflammation-induced nephrotoxicity.

Empagliflozin attenuates acute kidney injury after myocardial infarction in diabetic rats

Acute kidney injury (AKI) predicts poor prognosis in patients with acute myocardial infarction (MI) and diabetes mellitus (DM) is an independent risk factor of AKI. Recent clinical studies have shown the beneficial effects of sodium-glucose cotransporter 2 (SGLT2) inhibitors on cardiovascular and renal outcomes in patients with DM. We recently reported that canagliflozin normalized susceptibility of diabetic rats to AKI after acute MI via β-hydroxybutyrate-mediated suppression of NOX expression. Here we examined whether the same renoprotective effect is shared by empagliflozin. Serum creatinine levels were not changed by MI induced by coronary artery occlusion in LETO, non-diabetic control rats, and OLETF, obese type 2 diabetic rats. However, immunohistochemistry revealed that MI increased renal expression of NGAL and KIM-1, early markers of tubular injury, by 3.2-fold and 2.6-fold, respectively, in OLETF. These increases in injury markers were not observed in LETO. Pretreatment with empagliflozin of OLETF for 2 weeks improved hyperglycemia, increased blood β-hydroxybutyrate level, and suppressed MI-induced expression of NGAL and KIM-1. Empagliflozin suppressed upregulation of NOX2 and NOX4 in the kidney of OLETF. Taken together with the results of our previous study, it was concluded that treatment with the SGLT2 inhibitor protects the diabetic kidney from MI-induced AKI.

Tissue deconjugation of urolithin A glucuronide to free urolithin A in systemic inflammation

Urolithin A (Uro-A) is an anti-inflammatory and cancer chemopreventive metabolite produced by the gut microbiota from the polyphenol ellagic acid. However, in vivo conjugation of Uro-A to Uro-A glucuronide (Uro-A glur) dramatically hampers its activity. We describe here for the first time the tissue deconjugation of Uro-A glur to Uro-A after lipopolysaccharide (LPS)-induced inflammation, which could explain the systemic in vivo activity of free Uro-A in microenvironments subjected to inflammatory stimuli.

Evaluation of Neutrophil Gelatinase-Associated Lipocalin as a Predictor of Glomerular Filtration Rate and Amikacin Clearance During Early Rat Endotoxemia: Comparison with Traditional Endogenous and Exogenous Biomarkers

BACKGROUND AND OBJECTIVES

Renal elimination of amikacin and other aminoglycosides is slowed down in sepsis-induced acute kidney injury increasing the risk of adverse effects. Since neutrophil gelatinase-associated lipocalin (NGAL) and aminoglycosides share the mechanisms for renal excretion, the predictive power of NGAL was examined towards the changes in amikacin pharmacokinetics during early endotoxemia in anesthetized Wistar rats.

METHODS

Endogenous biomarkers of inflammation and acute kidney injury were assessed including NGAL in saline-injected controls and two groups of rats challenged with an intravenous injection of bacterial lipopolysaccharide (5 mg/kg)-a fluid-resuscitated group (LPS) and a fluid-resuscitated group infused intravenously with 8 μg/kg/h terlipressin (LPS-T). Sinistrin and amikacin were infused to measure glomerular filtration rate (GFR) and amikacin clearance (CL_am). The investigations included blood gas analysis, chemistry and hematology tests and assessment of urine output, creatinine clearance (CL_cr) and sinistrin clearance (CL_sini).

RESULTS

Within 3 h of injection, systemic and renal inflammatory responses were induced by lipopolysaccharide. Gene and protein expression of NGAL was increased in the kidneys and the concentrations of NGAL in the plasma (pNGAL) and urine rose 4- to 38-fold (P < 0.01). The decreases in CL_am and the GFR markers (CL_cr, CL_sini) were proportional, reflecting the extent to which endotoxemia impaired the major elimination mechanism for the drug. Terlipressin attenuated lipopolysaccharide-induced renal dysfunction (urine output, CL_cr, CL_sini) and accelerated CL_am. The pNGAL showed a strong association with the CL_sini (rs = - 0.77, P < 0.0005). Concerning prediction of CL_am, pNGAL was comparable to CL_cr (mean error - 24%) and inferior to CL_sini (mean error - 6.4%), while the measurement of NGAL in urine gave unsatisfactory results.

CONCLUSIONS

During early endotoxemia in the rat, pNGAL has a moderate predictive ability towards CL_am. Clinical studies should verify whether pNGAL can support individualized dosing of aminoglycosides to septic patients.

Antagonism of major histocompatibility complex class II invariant chain peptide during chronic lipopolysaccharide treatment rescues autoregulatory behavior

Toll-like receptor 4 (TLR4) activation contributes to vascular dysfunction in pathological conditions such as hypertension and diabetes, but the role of chronic TLR4 activation on renal autoregulatory behavior is unknown. We hypothesized that subclinical TLR4 stimulation with low-dose lipopolysaccharide (LPS) infusion increases TLR4 activation and blunts renal autoregulatory behavior. We assessed afferent arteriolar autoregulatory behavior in male Sprague-Dawley rats after prolonged LPS (0.1 mg·kg^-1·day^-1 sq) infusion via osmotic minipump for 8 or 14 days. Some rats also received daily cotreatment with either anti-TLR4 antibody (1 μg ip), competitive antagonist peptide (CAP; 3 mg/kg ip) or tempol (2 mmol/l, drinking water) throughout the 8-day LPS treatment period. Autoregulatory behavior was assessed using the in vitro blood-perfused juxtamedullary nephron preparation. Selected physiological measures, systolic blood pressure and baseline diameters were normal and similar across groups. Pressure-dependent vasoconstriction averaged 72 ± 2% of baseline in sham rats, indicating intact autoregulatory behavior. Eight-day LPS-treated rats exhibited significantly impaired pressure-mediated vasoconstriction (96 ± 1% of baseline), whereas it was preserved in rats that received anti-TLR4 antibody (75 ± 3%), CAP (84 ± 2%), or tempol (82 ± 2%). Using a 14-day LPS (0.1 mg·kg^-1·day^-1 sq) intervention protocol, CAP treatment started on day 7, where autoregulatory behavior is already impaired. Systolic blood pressures were normal across all treatment groups. Fourteen-day LPS treatment retained the autoregulatory impairment (95 ± 2% of baseline). CAP intervention starting on day 7 rescued pressure-mediated vasoconstriction with diameters decreasing to 85 ± 1% of baseline. These data demonstrate that chronic subclinical TLR4 activation impairs afferent arteriolar autoregulatory behavior through mechanisms involving reactive oxygen species and major histocompatibility complex class II activation.

Role of Hemorrhagic Shock in Experimental Polytrauma

Hemorrhagic shock (HS) after tissue trauma increases the complication and mortality rate of polytrauma (PT) patients. Although several murine trauma models have been introduced, there is a lack of knowledge about the exact impact of an additional HS. We hypothesized that HS significantly contributes to organ injury, which can be reliably monitored by detection of specific organ damage markers. Therefore we established a novel clinically relevant PT plus HS model in C57BL/6 mice which were randomly assigned to control, HS, PT, or PT+HS procedure (n = 8 per group). For induction of PT, anesthetized animals received a blunt chest trauma, head injury, femur fracture, and soft tissue injury. HS was induced by pressure-controlled blood drawing (mean arterial blood pressure of 30 mmHg for 60 min) and mice then resuscitated with ionosterile (4 × volume drawn), monitored, and killed for blood and organ harvesting 4 h after injury. After HS and resuscitation, PT+HS mice required earlier and overall more catecholamine support than HS animals to keep their mean arterial blood pressure. HS significantly contributed to the systemic release of interleukin-6 and high mobility group box 1 protein. Furthermore, the histological lung injury score, pulmonary edema, neutrophil influx, and plasma clara cell protein 16 were all significantly enhanced in PT animals in the presence of an additional HS. Although early morphological changes were minor, HS also contributed functionally to remote acute kidney injury but not to early liver damage. Moreover, PT-induced systemic endothelial injury, as determined by plasma syndecan-1 levels, was significantly aggravated by an additional HS. These results indicate that HS adds to the systemic inflammatory reaction early after PT. Within hours after PT, HS seems to aggravate pulmonary damage and to worsen renal and endothelial function which might overall contribute to the development of early multiple organ dysfunction.

Kidney Injury Biomarkers in an Academic Hospital Setting: Where Are We Now?

Acute kidney injury (AKI) is a frequent complication in hospitalised patients and is diagnosed by urinary output and serum creatinine. Serum creatinine is an indirect marker for renal glomerular filtration, but lacks specificity for damage to kidney tissue and the relatively late response to injury precludes early recognition of AKI. Timely diagnosis of kidney injury using biomarkers that provide information about the aetiology of kidney injury is an unmet clinical need. To overcome the suboptimal performance of serum creatinine, injury biomarkers have been proposed that predict AKI in diverse clinical settings. The clinical performance of these markers is considered moderate due to the lack of specificity for kidney tissue or the underlying injury mechanisms, poor test specificity and confounding by interventions or comorbidities. Hence, it is not unequivocally beneficial to implement current kidney injury biomarkers in the clinical laboratory for diagnostic purposes. In this article we review biomarkers that might fulfil AKI-related unmet clinical needs in the academic hospital setting.

Neutrophil gelatinase-associated lipocalin: An early biomarker for predicting acute kidney injury and severity in patients with acute pancreatitis

Background and Aim

Acute kidney injury (AKI) in severe acute pancreatitis (SAP) has a high mortality rate. Traditionally used serum creatinine is an insensitive biomarker for the early detection of AKI. We aimed to study the role of plasma and urinary neutrophil gelatinase‐associated lipocalin (NGAL) in predicting AKI and a severe course in patients with acute pancreatitis (AP).

Methods

Consecutive patients of AP who presented within 72 h of symptom onset and age‐ and gender‐matched healthy controls were included. Urinary and serum NGAL levels [enzyme‐linked immunosorbent assay (ELISA)] were evaluated within 24 h of and 72 h after admission and once in controls. Urine and serum NGAL levels were correlated with development of AKI, severity, and outcomes of AP.

Results

Fifty patients with AP and 30 controls were enrolled. The mean serum and urine NGAL levels in patients on day 1 were significantly higher than the serum and urine NGAL levels in controls (P < 0.001). After excluding patients with AKI on day 1 (n = 10), both serum and urinary NGAL levels on days 1 and 3 were significantly higher in patients who subsequently developed AKI (n = 11) compared to those who did not (n = 29) (P = 0.02, 0.01 and P < 0.001, 0.03). A urinary NGAL level of 221.03 ng/mL on day 1 predicted AKI with a sensitivity and specificity of 82 and 80%, respectively (AUC = 0.9). Mean serum and urinary NGAL levels on day 1 were significantly elevated in patients with SAP compared to those without SAP (P = 0.04 and <0.001).

Conclusion

NGAL levels in urine and serum can predict severity of AP and development of AKI.

Propofol attenuates sepsis-induced acute kidney injury by regulating miR-290-5p/CCL-2 signaling pathway

Previous studies have indicated that propofol has immunomodulatory and antioxidative properties. However, the renoprotection effect and the precise mechanisms of propofol in sepsis-induced renal injury remain unclear. The purpose of the present study was to investigate the role of miR-290-5p/CCL-2 signaling in septic mice treatment with propofol. Mice were treated with propofol (50 mg/kg) twice within 24 h. Survival outcome was monitored within 48 h. The mRNA and protein levels were assayed by qRT-PCR and western blotting, respectively. Mouse podocytes (MPC5) were treated with lipopolysaccharide (LPS) to establish the cell model in vitro. The proliferation of MPC5 was monitored using the MTS assay. Cell apoptosis was analyzed by flow cytometry. Propofol improved survival outcome and alleviated acute kidney injury in cecal ligation and puncture-operated mice. Propofol increased miR-290-5p expression and decreased CCL-2 and inflammatory cytokines levels in the kidney for septic mice. We found that miR-290-5p was a direct regulator of CCL-2 in MPC5. Propofol could abrogate LPS-induced growth inhibition and apoptosis in MPC5. Meanwhile, propofol inhibited CCL-2 expression in LPS-treated MPC5, however, knockdown of miR-290-5p abrogated the inhibitory effect propofol on the mRNA and protein expressions of CCL-2. Propofol could serve as an effective therapeutic medication to suppress sepsis-induced renal injury in vivo and in vitro by regulating the miR-290-5p/CCL-2 signaling pathway.

Mineralocorticoid Receptor and Aldosterone-Related Biomarkers of End-Organ Damage in Cardiometabolic Disease

The mineralocorticoid receptor (MR) was first identified as a blood pressure regulator, modulating renal sodium handling in response to its principal ligand aldosterone. The mineralocorticoid receptor is also expressed in many tissues other than the kidney, such as adipose tissue, heart and vasculature. Recent studies have shown that MR plays a relevant role in the control of cardiovascular and metabolic function, as well as in adipogenesis. Dysregulation of aldosterone/MR signaling represents an important cause of disease as high plasma levels of aldosterone are associated with hypertension, obesity and increased cardiovascular risk. Aldosterone displays powerful vascular effects and acts as a potent pro-fibrotic agent in cardiovascular remodeling. Mineralocorticoid receptor activation regulates genes involved in vascular and cardiac fibrosis, calcification and inflammation. This review focuses on the role of novel potential biomarkers related to aldosterone/MR system that could help identify cardiovascular and metabolic detrimental conditions, as a result of altered MR activation. Specifically, we discuss: (1) how MR signaling regulates the number and function of different subpopulations of circulating and intra-tissue immune cells; (2) the role of aldosterone/MR system in mediating cardiometabolic diseases induced by obesity; and (3) the role of several MR downstream molecules as novel potential biomarkers of cardiometabolic diseases, end-organ damage and rehabilitation outcome.

Telluric Acid Ameliorates Endotoxemic Kidney Injury in Mice: Involvement of TLR4, Nrf2, and PI3K/Akt Signaling Pathways

Being one of the most abundant trace elements in the human body, the therapeutic potential of tellurium-based compounds has been a target of interest. Recent reports denoted their redox-modulating and anti-inflammatory activities in experimental endotoxemia. However, their potential nephroprotective effect against endotoxemic kidney injury is yet to be elucidated. This study investigated the possible renoprotective effect of telluric acid (TEL) against lipopolysaccharide (LPS)-induced acute kidney injury (AKI) in mice, targeting toll-like receptor 4 (TLR4), phosphoinositide 3-kinase (PI3K)/Akt, and nuclear factor-erythroid 2-related factor-2 (Nrf2) pathways as possible mechanistic contributors to TEL's effect. AKI was induced by LPS (2 mg/kg). TEL (60 μg/kg; i.p.) was administered once daily for seven consecutive days before LPS injection. Pretreatment with TEL alleviated LPS-induced AKI as evidenced by the hampered serum levels of creatinine and cystatin C. TEL also opposed LPS-induced elevation in renal kidney injury molecule-1, neutrophil gelatinase-associated lipocalin, nuclear factor-kappa B p65, interleukin-1β, and thiobarbituric acid-reactive substance contents. This was accompanied by a replenishment of renal glutathione, transcriptional upregulation of Nrf2, enhancement of heme oxygenase-1 activity, and a marked upregulation of phospho-PI3K and phospho-Akt protein expressions. Histopathological findings corroborated with the amendment of biochemical parameters. In view of these findings, we may conclude that TEL pretreatment purveyed novel nephroprotective effects against endotoxemic kidney injury, which might be partly attributed to the modulation of TLR4, PI3K/Akt, and Nrf2 signaling pathways and may hence provide a valuable asset for the management of endotoxemic renal complications.

NGAL protects against endotoxin-induced renal tubular cell damage by suppressing apoptosis

Background

We sought to confirm that neutrophil gelatinase-associated lipocalin (NGAL) protects against apoptosis during endotoxemia.

Methods

Endotoxemia was induced in rats with lipopolysaccharide (LPS; 3.5 mg/kg) and serum creatinine (SCr), urinary NGAL (uNGAL), renal histopathology confirmed acute kidney injury (AKI). Renal caspase 3 and NGAL were assayed with immunohistochemistry 6 h later. A HK-2 cell model was used in which NGAL and caspase 3 mRNA were evaluated by qRT-PCR within 6 h after LPS (50 μM) treatment, and correlations were studied. NGAL and caspase 3 mRNA expression were measured after delivering NGAL siRNA in HK-2 cells and apoptosis was measured with TUNEL and flow cytometry.

Results

SCr and uNGAL were significantly increased after LPS treatment and renal morphology data indicated AKI and renal tubular epithelial cell apoptosis. Caspase 3 and NGAL were predominantly expressed in the tubular epithelial cells and there was a correlation between caspase 3 and NGAL protein (r = 0.663, p = 0.01). In vitro, there was a strong correlation between caspase 3 and NGAL mRNA in LPS-injured HK-2 cells within 24 h (r = 0.448, p < 0.05). Suppressing the NGAL gene in HK-2 cells increased caspase 3 mRNA 4.5-fold and apoptosis increased 1.5-fold after LPS treatment.

Conclusions

NGAL is associated with caspase 3 in renal tubular cells with endotoxin-induced kidney injury, and may regulate its expression and inhibit apoptosis.

Differences in acute kidney injury ascertainment for clinical and preclinical studies

Background

Acute kidney injury (AKI) is a common clinical condition directly associated with adverse outcomes. Several AKI biomarkers have been discovered, but their use in clinical and preclinical studies has not been well examined. This study aims to investigate the differences between clinical and preclinical studies on AKI biomarkers.

Methods

We performed a systematic review of clinical and preclinical interventional studies that considered AKI biomarkers in enrollment criteria and/or outcome assessment and described the main differences according to their setting, the inclusion of biomarkers in the definition of AKI and the use of biomarkers as primary or secondary end points.

Results

In the 151 included studies (76 clinical, 75 preclinical), clinical studies have prevalently focused on cardiac surgery (38.1%) and contrast-associated AKI (17.1%), while the majority of preclinical studies have focused on ether ischemia-reperfusion injury or drug-induced AKI (42.6% each). A total of 57.8% of clinical studies defined AKI using the standard criteria and only 19.7% of these studies used AKI biomarkers in the definition of renal injury. Conversely, the majority of preclinical studies defined AKI according to the increase in serum creatinine and blood urea nitrogen, and 32% included biomarkers in that definition. The percentage of both clinical and preclinical studies with biomarkers as a primary end point has not significantly increased in the last 10 years; however, preclinical studies are more likely to use AKI biomarkers as a primary end point compared with clinical studies [odds ratio 2.31 (95% confidence interval 1.17-4.59); P  =  0.016].

Conclusion

Differences between clinical and preclinical studies are evident and may affect the translation of preclinical findings in the clinical setting.

More than a simple biomarker: the role of NGAL in cardiovascular and renal diseases

Neutrophil gelatinase-associated lipocalin (NGAL) is a small circulating protein that is highly modulated in a wide variety of pathological situations, making it a useful biomarker of various disease states. It is one of the best markers of acute kidney injury, as it is rapidly released after tubular damage. However, a growing body of evidence highlights an important role for NGAL beyond that of a biomarker of renal dysfunction. Indeed, numerous studies have demonstrated a role for NGAL in both cardiovascular and renal diseases. In the present review, we summarize current knowledge concerning the involvement of NGAL in cardiovascular and renal diseases and discuss the various mechanisms underlying its pathological implications.

N-acetylcysteine decreases urinary level of neutrophil gelatinase-associated lipocalin in deceased-donor renal transplant recipients: a randomized clinical trial

CONTEXT

Acute kidney injury (AKI) is a common complication after kidney transplantation (KT), especially in recipients from deceased donors. Urinary neutrophil gelatinase-associated lipocalin (u-NGAL) is an early and sensitive marker of AKI after transplantation.

OBJECTIVES

We assessed the renoprotective effect of N-acetylcysteine (NAC) on u-NGAL levels as an early prognostic marker of graft function immediately after transplantation.

MATERIALS AND METHODS

A double-blind, randomized, placebo-controlled trial was conducted on 70 deceased-donor KT recipients ( www.irct.ir , trial registration number: IRCT2014090214693N4). Patients received 600 mg oral NAC or placebo twice daily from day 0 to 5 and urine samples were taken before, and on the first and fifth days after transplantation. U-NGAL and early graft function were compared between the two groups.

RESULTS

NAC significantly reduced u-NGAL levels compared to placebo (p value = 0.02), while improvement in early graft function with NAC did not reach statistical significance.

CONCLUSIONS

This study showed that NAC administration in deceased-donor KT recipients can reduce tubular kidney injury, evidenced by u-NGAL measurements. Improvement in early graft function needs a larger sample size to reach a statistical conclusion.

A cold-inducible RNA-binding protein (CIRP)-derived peptide attenuates inflammation and organ injury in septic mice

Cold-inducible RNA-binding protein (CIRP) is a novel sepsis inflammatory mediator and C23 is a putative CIRP competitive inhibitor. Therefore, we hypothesized that C23 can ameliorate sepsis-associated injury to the lungs and kidneys. First, we confirmed that C23 dose-dependently inhibited TNF-α release, IκBα degradation, and NF-κB nuclear translocation in macrophages stimulated with CIRP. Next, we observed that male C57BL/6 mice treated with C23 (8 mg/kg BW) at 2 h after cecal ligation and puncture (CLP) had lower serum levels of LDH, ALT, IL-6, TNF-α, and IL-1β (reduced by ≥39%) at 20 h after CLP compared with mice treated with vehicle. C23-treated mice also had improved lung histology, less TUNEL-positive cells, lower serum levels of creatinine (34%) and BUN (26%), and lower kidney expression of NGAL (50%) and KIM-1 (86%). C23-treated mice also had reduced lung and kidney levels of IL-6, TNF-α, and IL-1β. E-selectin and ICAM-1 mRNA was significantly lower in C23-treated mice. The 10-day survival after CLP of vehicle-treated mice was 55%, while that of C23-treated mice was 85%. In summary, C23 decreased systemic, lung, and kidney injury and inflammation, and improved the survival rate after CLP, suggesting that it may be developed as a new treatment for sepsis.

Usefulness of urinary biomarkers for nephrotoxicity in cynomolgus monkeys treated with gentamicin, cisplatin, and puromycin aminonucleoside

The objective of this study was to investigate the availability of novel urinary biomarkers (BMs) such as total protein, albumin, β₂-microglobulin, clusterin, cystatin C, neutrophil gelatinase-associated lipocalin (NGAL) for the detection of acute nephrotoxicity in cynomolgus monkeys. Animals (total 9 males/3 groups) were administered gentamicin (GM) subcutaneously at 40 mg/kg for 7 days, cisplatin (CDDP) intravenously at 3 mg/kg once and puromycin aminonucleoside (PAN) intravenously at 20 mg/kg for 7 days. Two-hr urine on Days 0, 3, and 6, and 16-hr urine and blood on Days 1, 4, and 7 were collected. Novel urinary BMs and conventional clinical pathology parameters were evaluated in parallel to histopathological and electron microscopic examinations on the kidneys at termination. Urinary BMs and enzymes increased earlier than serum creatinine and blood urea nitrogen, particularly in 2-hr urine after dosing on Day 0, urinary albumin was increased in all groups and urinary NGAL with the highest magnitude of change rate among urinary BMs was observed in the GM and CDDP groups. Degeneration/necrosis and hyaline droplet of renal tubule, cellular cast and dilatation of renal tubule, and hypertrophy of podocytes were observed in the GEN, CDDP, and PAN groups, respectively. These results showed that the increases of urinary BMs reflected the agent-specific renal damages and these urinary BMs could be useful for the detection of segment-specific nephrotoxicity. Urinary albumin and NGAL are the most useful BMs to estimate glomerular and distal tubular damages, respectively, as well as proximal tubular damage in cynomolgus monkeys.

Total Coumarins from Hydrangea paniculata Show Renal Protective Effects in Lipopolysaccharide-Induced Acute Kidney Injury via Anti-inflammatory and Antioxidant Activities

Background: Septic acute kidney injury (AKI) causes high mortality in critical care units, and no effective therapy exists in clinical treatment. In the current study, water and ethanol extracts of Hydrangea paniculata (HP), a traditional Chinese medicinal plant, were used to test its renoprotective effects in a lipopolysaccharide (LPS)-induced murine model of septic AKI.

Methods: C57BL/6 mice were orally pretreated with HP three times, and then intraperitoneal LPS injection was used to induce septic AKI. Blood from animals was collected for biochemical analysis and kidneys were obtained for pathological analysis. Kidney tissue homogenates were used to investigate the effect of HP on inflammation and oxidative stress. Immunohistochemistry was used to investigate tubular cell apoptosis. Flow cytometry was conducted to analyze leukocyte infiltration into the kidneys. Blood cell counts were used to analyze changes in peripheral leukocytes. In vitro studies with Ana1 and HK-2 cells stimulated by LPS were used to investigate the anti-inflammatory effects and inhibition of signaling pathways by HP.

Results: HP significantly decreased blood urea nitrogen and plasma neutrophil gelatinase-associated lipocalin concentrations, as well as tubulointerstitium injuries in septic AKI mice. Moreover, HP administration improved animal survival following lethal LPS injections. HP ameliorated apoptosis of tubular cells by inhibiting the cleavage of caspase 3 and caspase 7. HP also showed pronounced antioxidant activity in AKI kidneys. HP showed anti-inflammatory effects by inhibiting the infiltration of neutrophils and macrophages into kidney tissues induced by LPS, as well as inhibiting the production of cytokines and chemokines. Possible molecular mechanisms included HP inhibition of NF-κB nuclear translocation in LPS-induced macrophages and tubular cells, and reduction of STAT3, STAT1, and ERK1/2 phosphorylation stimulated by LPS in vitro. Single acute toxicity tests confirmed that HP, even at 5 g/kg dosage, does not cause animal death. Pharmacokinetics also showed that coumarins from HP could be metabolized into two bioactive compounds, umbelliferone, and esculetin.

Conclusions: HP extract may protect renal function in LPS-induced AKI by anti-inflammatory and antioxidant activities, and has potential in the critical care of AKI.

Physiological aspects of Toll-like receptor 4 activation in sepsis-induced acute kidney injury

Sepsis‐induced acute kidney injury (SI‐AKI) is common and associated with high mortality. Survivors are at increased risk of chronic kidney disease. The precise mechanism underlying SI‐AKI is unknown, and no curative treatment exists. Toll‐like receptor 4 (TLR4) activates the innate immune system in response to exogenous microbial products. The result is an inflammatory reaction aimed at clearing a potential infection. However, the consequence may also be organ dysfunction as the immune response can cause collateral damage to host tissue. The purpose of this review is to describe the basis for how ligand binding to TLR4 has the potential to cause renal dysfunction and the mechanisms by which this may take place in gram‐negative sepsis. In addition, we highlight areas for future research that can further our knowledge of the pathogenesis of SI‐AKI in relation to TLR4 activation. TLR4 is expressed in the kidney. Activation of TLR4 causes cytokine and chemokine release as well as renal leucocyte infiltration. It also results in endothelial and tubular dysfunction in addition to altered renal metabolism and circulation. From a physiological standpoint, inhibiting TLR4 in large animal experimental SI‐AKI significantly improves renal function. Thus, current evidence indicates that TLR4 has the ability to mediate SI‐AKI by a number of mechanisms. The strong experimental evidence supporting a role of TLR4 in the pathogenesis of SI‐AKI in combination with the availability of pharmacological tools to target TLR4 warrants future human studies.

NGAL expression during cardiopulmonary bypass does not predict severity of postoperative acute kidney injury

BACKGROUND

Renal injury is a serious complication after cardiac surgery and therefore, early detection and much more prediction of postoperative kidney injury is desirable. Neutrophil gelatinase-associated lipocalin (NGAL) is a predictive biomarker of acute kidney injury and may increase after cardiopulmonary bypass (CPB). However, time correlation of NGAL expression and severity of renal injury is still unclear. The aim of our study was to investigate CPB-related urine NGAL (uNGAL) secretion in correlation to postoperative renal function.

METHODS

Data of NGAL expression along with clinical data of 81 patients (52 male and 29 female) were included in this study. Mean age of the patients was 66.8 ± 12.8 years. Urine NGAL was measured at seven time points (T₀: baseline; T₁: start CPB, T₂: 40 min on CPB; T₃: 80 min on CPB; T₄: 120 min on CPB; T_p1: 15 min after CPB; T_p2: 4 h after admission to the intensive care unit) and renal function in the postoperative period was classified daily according to Acute Kidney Injury Network (Ronco et al, Int J Artif Organs 30(5): 373-6) criteria (AKIN).

RESULTS

Expression of uNGAL increased at T₄ (120 min on CPB) and post-CPB (T_p1 and T_p2; p < 0.01 vs. baseline) but there was no correlation between uNGAL level and duration of CPB nor between uNGAL expression and occurrence of postoperative kidney injury. The renal function over 10 days after surgery remained normal in 50 patients (AKIN level 0), 18 patients (22%) developed mild and insignificant renal injury (AKIN level 1), eight patients (10%) developed moderate renal failure (AKIN level 2), and five patients (6%) severe kidney failure (AKIN level 3). Twenty-four out of 31 patients developed renal failure within the first 48 h after surgery. However, there was no correlation between uNGAL expression and severity of acute renal failure.

CONCLUSION

Although uNGAL expression increased after CPB, the peak values neither predict acute postoperative kidney injury, nor severity of the injury.

Nephroprotection of punicalagin in rat model of endotoxemic acute kidney injury

The potential nephroprotection of punicalagin (PNG) against lipopolysaccharide (LPS)-induced acute kidney injury in rats was investigated. Rats received a single i.v. dose of LPS (5 mg/kg), and treated with PNG (50 mg/kg, i.p.), 1 h before, and 1 h following LPS administration. LPS caused significant increases of serum creatinine and neutrophil gelatinase-associated lipocalin. LPS also resulted in significant increases in interleukin-18, tumor necrosis factor-α, interleukin-6, malondialdehyde, nitric oxide, Bax/Bcl-2 ratio and myeloperoxidase, inducible nitric oxide synthase, caspases 3, 8 and 9 activities, and a significant decrease in total antioxidant capacity in kidney tissues. PNG significantly ameliorated the alterations in the measured parameters. Additionally, PNG attenuated the histopathological injury and reduced kidney injury molecule-1 expression in kidneys of rats that received LPS. It was concluded that PNG ameliorated endotoxemic acute kidney injury in rats by counteracting inflammation, oxidative/nitrative stress and apoptosis.

Neutrophil gelatinase-associated lipocalin attenuates injury in the rat cecal ligation and puncture model of sepsis via apoptosis inhibition

AIM

The aim of this study was to investigate the effect of neutrophil gelatinase-associated lipocalin (NGAL) on the rat cecal ligation and puncture (CLP)-induced sepsis and the possible mechanism.

METHODS

Thirty male Sprague-Dawley rats underwent CLP as sepsis models and were randomized into three groups including the sham-operated group (sham, n = 10), which only underwent a laparotomy; the sepsis group (sepsis, n = 10), which underwent CLP and subcutaneous injection of normal saline; and the sepsis + NGAL group (sepsis + NGAL, n = 10), which underwent CLP and subcutaneous injection of NGAL. Urine, blood and kidney tissue samples were collected for the determination of urine NGAL (uNGAL), plasma NGAL (pNGAL), serum creatinine (Scr), blood urea nitrogen (BUN), histomorphological and immunohistochemical examination, lipid peroxidation product malondialdehyde (MDA) and superoxide dismutase (SOD), and expression of heme oxygenase-1 (HO)-1.

RESULTS

The levels of uNGAL, pNGAL, Scr, BUN, kidney injury score, positive TUNEL staining, activated Caspase-3 and Bax, and kidney tissue MDA levels in the sepsis group were significantly increased compared with those in the sham-operated group and the sepsis + NGAL group (P < 0.05). SOD level and HO-1 expression in sepsis + NGAL group were significantly higher than those in the sham-operated group and the sepsis group (P < 0.05).

CONCLUSION

NGAL can attenuate kidney injury and apoptosis in the rat CLP model of sepsis. And the protective effect of NGAL was probably due to the inhibition of apoptosis and lipid peroxidation, and increased expression of HO-1.

Lipopolysaccharide-induced inflammation or unilateral ureteral obstruction yielded multiple types of glycosylated Lipocalin 2

Background

The amount of urinary glycoprotein lipocalin 2 (LCN2) has been known to increase after kidney injury because of failed reabsorption by the proximal tubules or direct secretion from injured tissues. However, the relationship between urinary tract obstruction and the isoform diversity of LCN2 has not been examined.

Methods

The urinary levels of LCN2 isoforms were examined in male mice after an intraperitoneal injection of lipopolysaccharide (LPS) or in a mouse model of unilateral ureter obstruction (UUO). The LCN2 levels in sera, bladder urine, renal pelvic urine, and tissue samples were also analyzed. Endo- and exoglycosidases were used to investigate the different N-glycan patterns of LCN2.

Results

Two isoforms of urinary LCN2 with different molecular weights were identified in an immunoblotting analysis, and the levels of both isoforms were increased 6 h after LPS administration. The primary LCN2 isoform was the lower molecular weight 22-kDa isoform, which was detected in the serum, urine, liver and kidney. In contrast, the 24-kDa LCN2 isoform was detected only in urine. In the UUO experiments, the levels of the 24-kDa LCN2 were increased in the bladder urine but not in the urine accumulated in the renal pelvis due to UUO. The 22-kDa LCN2 was identified in the renal pelvic urine from UUO mice. The peptide-N glycosidase F digestion of the two urinary LCN2 isoforms generated a single protein. Moreover, the two urinary LCN2 proteins were sensitive to neuraminidase and resistant to endoglycosidase H (Endo H). The LCN2 in the serum, lung and kidney was resistant to Endo H, as observed in urine, whereas the LCN2 in the liver and the ureter were degraded by this enzyme.

Conclusions

These results suggest that the difference in the molecular weights of the LCN2 proteins was due to their N-glycan structure. The high molecular weight LCN2 in urine could be detected after the inflammatory response to LPS and UUO. Furthermore, the sensitivity to Endo H identified the presence of two types of carbohydrate moieties, depending on the tissue in which the LCN2 was produced. These findings are useful for widening the clinical applicability of urinary LCN2 analyses.

Is plasma neutrophil gelatinase-associated lipocalin a predictive biomarker for acute kidney injury in sepsis patients? A systematic review and meta-analysis

PURPOSE

Neutrophil gelatinase-associated lipocalin (NGAL) is a useful biomarker for early diagnosis of acute kidney injury (AKI). However, the diagnostic value of NGAL for predicting AKI in sepsis patients is unclear.

METHODS

MEDLINE, EMBASE, and Cochrane Library databases were searched to identify research publications.

RESULTS

Twelve studies from 9 countries including a total of 1582 patients, of whom 315 (19.9%) developed AKI, were included in the study; plasma NGAL levels were significantly higher in adult sepsis patients with AKI than in those without AKI (mean difference, 274.65; 95% confidence interval [CI], 106.16-443.15; I(2) = 94%). Urine NGAL levels were not significantly different. The diagnostic odds ratio of plasma NGAL for predicting AKI in sepsis patients was 6.64 (95% CI, 3.80-11.58). The diagnostic accuracy of plasma NGAL was 0.881 (95% CI, 0.819-0.923) for sensitivity, 0.474 (95% CI, 0.367-0.582) for specificity, 0.216 (95% CI, 0.177-0.261) for positive predictive value and 0.965 (95% CI, 0.945-0.977) for negative predictive value.

CONCLUSION

Plasma NGAL has a high sensitivity and a high negative predictive value for detection of AKI in adult sepsis patients. However, its low specificity and low positive predictive value could limit its clinical utility. The usefulness of urine NGAL was not revealed in this study.

The function of miR-199a-5p/Klotho regulating TLR4/NF-κB p65/NGAL pathways in rat mesangial cells cultured with high glucose and the mechanism

Anti-aging protein Klotho may confer a renal protective effect via attenuating the nuclear factor-κB (NF-κB) p65 pathways activity. Besides, miR-199a-5p can promote gastric cancer by inhibition of Klotho protein expression. But little is known regarding to the role of miR-199a-5p/Klotho in regulating NF-κB p65 pathways in the pathogenesis of diabetic kidney disease (DKD). Thus, we explored Klotho and miR-199a-5p in terms of Toll-like receptor-4 (TLR4)/NF-κB p65/neutrophil gelatinase associated lipocalin (NGAL) signaling pathways in high glucose cultured mesangial cells (MCs). We found that high glucose increased miR-199a-5p expression, accompanied by the significantly decreased Klotho expression at both mRNA and protein. High glucose also activated TLR4/NF-κB p65/NGAL signaling pathways and promoted the downstream fibrosis and inflammatory reaction. Additionally, inhibition of miR-199a-5p or exogenous addition of Klotho restrained the activity of TLR4/NF-κB p65/NGAL signaling pathways, which in turn suppressed the inflammation and fibrosis in high glucose cultured MCs. This study provides a new basis to elucidate the protection mechanism of anti-aging protein Klotho in diabetic kidney. For the first time, our study prompts that miR-199a-5p can be used as a new therapeutic targets for DKD.

The role of neutrophil gelatinase associated lipocalin (NGAL) as biological constituent linking depression and cardiovascular disease

Depression is more common in patients with cardiovascular disease than in the general population. Conversely, depression is a risk factor for developing cardiovascular disease. Comorbidity of these two pathologies worsens prognosis. Several mechanisms have been indicated in the link between cardiovascular disease and depression, including inflammation. Systemic inflammation can have long-lasting effects on the central nervous system, which could be associated with depression. NGAL is an inflammatory marker and elevated plasma levels are associated with both cardiovascular disease and depression. While patients with depression show elevated NGAL levels, in patients with comorbid heart failure, NGAL levels are significantly higher and associated with depression scores. Systemic inflammation evokes NGAL expression in the brain. This is considered a proinflammatory effect as it is involved in microglia activation and reactive astrocytosis. Animal studies support a direct link between NGAL and depression/anxiety associated behavior. In this review we focus on the role of NGAL in linking depression and cardiovascular disease.

Plasma Neutrophil Gelatinase-Associated Lipocalin Is Primarily Related to Inflammation during Sepsis: A Translational Approach

Acute kidney injury (AKI) during sepsis is common and underestimated. Plasma neutrophil gelatinase-associated lipocalin (plasma-NGAL) is discussed as new biomarker for AKI diagnosis, but during inflammation its function and diagnostic impact remain unclear. The association between plasma-NGAL and inflammatory markers in septic patients, but also in healthy controls and patients with chronic inflammation before and after either maximum exercise test or treatment with an anti-TNF therapy were investigated. In-vitro blood stimulations with IL-6, lipopolysaccharide, NGAL or its combinations were performed to investigate cause-effect-relationship. Plasma-NGAL levels were stronger associated with inflammation markers including IL-6 (Sepsis: r=0.785 P<0.001; chronic inflammation after anti-TNF: r=0.558 P<0.001), IL-8 (Sepsis: r=0.714 P<0.004; healthy controls after exercise r=0.786 P<0.028; chronic inflammation before anti-TNF: r=0.429 P<0.041) and IL-10 (healthy controls before exercise: r=0.791 P<0.028) than with kidney injury or function. Correlation to kidney injury or function was found only in septic patients (for creatinine: r= 0.906 P<0.001; for eGFR: r= -0.686 P=0.005) and in patients with rheumatic disease after anti-TNF therapy (for creatinine: r= 0.466 P<0.025). In stimulation assays with IL-6 and lipopolysaccharide plasma-NGAL was increased. Co-stimulation of lipopolysaccharide with plasma-NGAL decreased cellular injury (P<0.05) and in trend IL-10 levels (P=0.057). Septic mice demonstrated a significantly improved survival rate after NGAL treatment (P<0.01). Plasma-NGAL seams to be strongly involved in inflammation. For clinical relevance, it might not only be useful for AKI detection during severe inflammation - indeed it has to be interpreted carefully within this setting - but additionally might offer therapeutic potential.

Low-dose carvedilol protects against acute septic renal injury in rats during the early and late phases

Recent findings from septic acute renal injury studies have implicated the mitochondrion as an important factor in kidney injury, and that increased sympathetic nerve activity may contribute to the induction of organ failure. This study investigated the impact of a nondepressor dose of carvedilol, which is a beta-adrenoreceptor antagonist with antioxidant activity, on septic renal injury induced in rats with cecal ligation and puncture (CLP). Three groups of rats were studied. The first group was the sham-operated control. The other 2 groups of rats underwent CLP, and were administered either the vehicle or carvedilol (2.0 mg/kg body mass, by intraperitoneal (i.p.) injection, daily for 2 days as well as 30 min prior to CLP). Kidney function, inflammatory parameters, mitochondrial function, and renal perfusion pressure (RPP) were investigated at 6 and 18 h after CLP. Carvedilol did not significantly induce hypotension, and it significantly improved RPP and renal dysfunction induced with CLP, together with significant reductions in serum levels of interleukin 6 and tumor necrosis factor-alpha. Septic kidney injury mediated increased levels of malondialdehyde and protein carbonyls. Carvedilol also attenuated the decrease in kidney mitochondrial glutathione and nicotinamide adenine dinucleotide phosphate dehydrogenase. Further, intracellular renal edema and inflammation induced with CLP were reduced with carvedilol. These findings suggest renoprotective effects of carvedilol in sepsis.

Evaluation of optical detection platforms for multiplexed detection of proteins and the need for point-of-care biosensors for clinical use

This review investigates optical sensor platforms for protein multiplexing, the ability to analyze multiple analytes simultaneously. Multiplexing is becoming increasingly important for clinical needs because disease and therapeutic response often involve the interplay between a variety of complex biological networks encompassing multiple, rather than single, proteins. Multiplexing is generally achieved through one of two routes, either through spatial separation on a surface (different wells or spots) or with the use of unique identifiers/labels (such as spectral separation-different colored dyes, or unique beads-size or color). The strengths and weaknesses of conventional platforms such as immunoassays and new platforms involving protein arrays and lab-on-a-chip technology, including commercially-available devices, are discussed. Three major public health concerns are identified whereby detecting medically-relevant markers using Point-of-Care (POC) multiplex assays could potentially allow for a more efficient diagnosis and treatment of diseases.