Megalin receptor-mediated endocytosis participates a crucial role in gentamicin (GM) uptake, accumulation, and toxicity. In this study, we investigated the potential effects of montelukast (MLK) on megalin expression/endocytic function against GM nephrotoxicity. Male Wistar rats were administered GM (120 mg/kg; i.p.) daily in divided doses along 4 hr; 30 mg/kg/hr; for 7 days. MLK (30 mg/kg/day) was orally administered 7 days before and then concurrently with GM. The protein expressions of megalin and chloride channel-5 (ClC-5); one of the essential regulators of megalin endocytic function; were determined by Western blotting. Besides, the endocytic function of megalin was evaluated by the uptake of bovine serum albumin labeled with fluorescein isothiocyanate (FITC-BSA) into proximal tubular epithelial cells. Moreover, kidney function biomarkers (Cr, BUN, GFR, KIM-1, cystatin-C) and apoptosis markers (p-AKT1, cleaved caspase-3) were estimated. Co-treatment with MLK downregulated ClC-5 expression leading to reduced recycling of megalin to the plasma membrane, reduced expression, and so impaired endocytic function that was evidenced by reduced uptake of FITC-BSA in proximal tubular epithelial cells. The protein expression of the apoptotic executioner cleaved caspase-3 was significantly reduced, while that of the antiapoptotic p-AKT1 was elevated. These results were confirmed by the improvement of kidney functions and histological findings. Our data suggest that MLK could interfere with megalin expression/endocytic function that could be attributed to downregulation of ClC-5 protein expression. That eventually reduces renal cell apoptosis and improves kidney functions after GM administration without affecting the antibacterial activity of GM. Therefore, reduced expression of ClC-5 and interference with megalin expression/endocytic function by MLK could be an effective strategy against GM nephrotoxicity.

BACKGROUND: Cardiac surgery-associated acute kidney injury (AKI) can increase the mortality and morbidity, and the incidence of chronic kidney disease, in critically ill survivors. The purpose of this research was to investigate possible links between urinary metabolic changes and cardiac surgery-associated AKI.
METHODS: Using ultra-high-performance liquid chromatography coupled with Q-Exactive Orbitrap mass spectrometry, non-targeted metabolomics was performed on urinary samples collected from groups of patients with cardiac surgery-associated AKI at different time points, including Before_AKI (uninjured kidney), AKI_Day1 (injured kidney) and AKI_Day14 (recovered kidney) groups. The data among the three groups were analyzed by combining multivariate and univariate statistical methods, and urine metabolites related to AKI in patients after cardiac surgery were screened. Altered metabolic pathways associated with cardiac surgery-induced AKI were identified by examining the Kyoto Encyclopedia of Genes and Genomes database.
RESULTS: The secreted urinary metabolome of the injured kidney can be well separated from the urine metabolomes of uninjured or recovered patients using multivariate and univariate statistical analyses. However, urine samples from the AKI_Day14 and Before_AKI groups cannot be distinguished using either of the two statistical analyses. Nearly 4000 urinary metabolites were identified through bioinformatics methods at Annotation Levels 1-4. Several of these differential metabolites may also perform essential biological functions. Differential analysis of the urinary metabolome among groups was also performed to provide potential prognostic indicators and changes in signalling pathways. Compared with the uninjured kidney group, the patients with cardiac surgery-associated AKI displayed dramatic changes in renal metabolism, including sulphur metabolism and amino acid metabolism.
CONCLUSIONS: Urinary metabolite disorder was observed in patients with cardiac surgery-associated AKI due to ischaemia and medical treatment, and the recovered patients\' kidneys were able to return to normal. This work provides data on urine metabolite markers and essential resources for further research on AKI.

UNASSIGNED: Cisplatin (CDDP) nephrotoxicity is one of the most significant complications limiting its use in cancer therapy.
UNASSIGNED: This study investigated the pivotal role played by thrombin in CDDP-mediated nephrotoxicity. This work also aimed to clarify the possible preventive effect of Dabigatran (Dab), a direct thrombin inhibitor, on CDDP nephrotoxicity.
UNASSIGNED: Animals were grouped as follow; normal control group, CDDP nephrotoxicity group, CDDP + Dab 15, and CDDP + Dab 25 groups. Four days following CDDP administration, blood and urine samples were collected to evaluate renal function. Moreover, tissue samples were collected from the kidney to determine apoptosis markers, oxidative stress and histopathological evaluation. An immunofluorescence analysis of tissue factor (TF), thrombin, protease-activated receptor-2 (PAR2), fibrin, pERK1/2 and P53 proteins expression was also performed.
UNASSIGNED: Thrombin, pERK, cleaved caspase-3, and oxidative stress markers were significantly elevated in CDDP-treated group. However, pretreatment of animals with either low or high doses of Dab significantly improved kidney function and decreased oxidative stress and apoptotic markers.
UNASSIGNED: We conclude that thrombin is an important factor in the pathogenesis of CDDP kidney toxicity via activation of ERK1/2, P53 and caspase-3 pathway, which can be effectively blocked by Dab.

BACKGROUND: Wounds with embedded metal fragments are an unfortunate consequence of armed conflicts. In many cases the exact identity of the metal(s) and their long-term health effects, especially on the kidney, are not known.
OBJECTIVE: The aim of this study was to quantitate the urinary levels of metals solubilized from surgically implanted metal pellets and to assess the effect of these metals on the kidney using a battery of biomarker assays.
METHODS: Using a rodent model system developed in our Institute to simulate embedded fragment injuries, eight metals considered likely components of an embedded fragment wound were individually implanted into the gastrocnemius muscle of male Sprague-Dawley rats. The rats were followed for 12 months post-implantation with urine collected prior to surgery then at 1-, 3-, 6-, 9-, and 12-months post-implantation to provide a within-subjects cohort for examination. Urinary metal levels were determined using inductively coupled plasma-mass spectrometry and urinary biomarkers assessed using commercially available kits to determine metal-induced kidney effects.
RESULTS: With few exceptions, most of the implanted metals rapidly solubilized and were found in the urine at significantly higher levels than in control animals as early as 1-month post-implantation. Surprisingly, many of the biomarkers measured were decreased compared to control at 1-month post-implantation before returning to normal at the later time points. However, two metals, iron and depleted uranium, showed increased levels of several markers at later time points, yet these levels also returned to normal as time progressed.
CONCLUSIONS: This study showed that metal pellets surgically implanted into the leg muscle of Sprague-Dawley rats rapidly solubilized with significant levels of the implanted metal found in the urine. Although kidney biomarker results were inconsistent, the changes observed along with the relatively low amounts of metal implanted, suggest that metal-induced renal effects need to be considered when caring for individuals with embedded metal fragment wounds.

This study examined the changes in haematological and biochemical variables in response to gastric mucosa injury in male Wistar rats divided into four groups according to their ages (3, 6, 12, and 18 months). 0.2 ml of acetic acid was injected intraluminal into the stomach glandular portion of each rat for 45 seconds under anaesthesia. Collection of blood and stomach samples occurred on days 3, 7, 14 and 21 post-induction of gastric ulcer. The results obtained from this study showed 100 % area of gastric mucosa healed in 3-month old rats, 91.72 %, 68.52 % and 62.81 % area of mucosa treated in 6, 12 and 18-month old rats respectively on day 21 post-induction of gastric ulcer. Increased circulation of blood cells in younger rats occurred, neutrophil-lymphocyte ratio (NLR) was decreased in younger rats (3 and 6 months) significantly (p < 0.05) when compared to older rats (12 and 18 months). Lipid peroxidation and glutathione (GSH) levels were elevated in older rats (12 and 18 months) significantly (p < 0.05) when compared to younger rats (3 and 6 months). In comparison, superoxide dismutase (SOD) and catalase levels were decreased in older rats (12 and 18 months) significantly (p < 0.05) when compared to younger rats (3 and 6 months). Histological evaluation showed evidence of early healing with re-epithelialisation and angiogenesis in younger rats, but older rats showed delayed healing. The study showed that the slower rate of healing of gastric ulcer with advancing age in rats might be due to reducing circulating blood cells and anti-inflammatory activities during healing via a lipid peroxidation-dependent mechanism.

Identification of novel biomarkers of contrast-induced nephropathy (CIN) that may more accurately detect renal function changes; reflect kidney damage; assist monitoring; and elucidate pathophysiology attract considerable scientific attention nowadays. To evaluate novel biomarkers of nephrotoxicity in blood/tissue samples of a CIN model, 10 New Zealand white rabbits were divided into group 1 (n = 5; iopromide) and group 2 (n = 5; control). Blood was drawn at 0 h (immediately), 24 h and 48 h after contrast medium (CM) administration. Animals were euthanized at 48 h and kidneys were removed. Serum creatinine (sCr)/symmetric-asymmetric dimethylarginine (SDMA-ADMA) levels were measured. CM genotoxic/cytotoxic effect was investigated 48 h post-CM exposure using micronucleus assay in lymphocytes. Cytological examination was conducted using touch preparation technique (TPT). All animals in group 1 developed CIN: mean sCr levels increased by 68.2% within 48 h. Significant SDMA-ADMA level elevation was observed at 0 h and 24 h with insignificant drop at 48 h in group 1, remaining normal in group 2 at all time-points. Significant increase in bi-nucleated cells with micronuclei and micronuclei frequency was detected in group 1. Cytokinesis block proliferation index was reduced insignificantly in group 1. TPT revealed degenerative lesions/inflammation, cell degeneration, abnormal uterine tubular casts and rubella in kidneys of all animals in group 1. Group 2 presented normal cells.

Fluoride intoxication generates free radicals, causing oxidative stress that plays a critical role in the progression of nephropathy. In the present study, we hypothesized that epigallocatechin gallate (EGCG), found in green tea, protects the kidneys of rats treated with fluoride by preventing oxidative stress, inflammation, and apoptosis. Pretreatment of fluoride-treated rats with EGCG resulted in a significant normalization of creatinine clearance and levels of urea, uric acid, and creatinine. Fluoride intoxication significantly increased renal oxidative stress markers and decreased the levels of renal enzymatic and non-enzymatic antioxidants. In addition, renal NO, TNF-α, IL-6 and NF-κB were also increased in the renal tissue of fluoride-treated rats. Further, EGCG pretreatment produced a significant improvement in renal antioxidant status and reduced lipid peroxidation, protein carbonylation and the levels of inflammatory markers in fluoride-treated kidney. Similarly, mRNA and protein analyses showed that EGCG pretreatment normalized the renal expression of Nrf2/Keap1 and its downstream regulatory proteins in fluoride-treated rat kidney. EGCG also effectively attenuated fluoride-induced renal apoptosis by the up-regulation of anti-apoptotic proteins such as Bcl-2 and down-regulation of Bax, caspase-3, caspase-9 and cytochrome c. Histology and immunohistochemical observations of Kim-1 provided further evidence that EGCG effectively protects the kidney from fluoride-mediated oxidative damage. These results suggest that EGCG ameliorates fluoride-induced oxidative renal injury by activation of the Nrf2/HO-1 pathway.

Diglycolic acid (DGA) is present in trace amounts in our food supply and is classified as an indirect food additive linked with the primary GRAS food additive carboxymethyl cellulose (CMC). Carboxymethyl starches are used as a filler/binder excipient in dietary supplement tablets and a thickening ingredient in many other processed foods. We sought to utilize the human proximal tubule HK-2 cell line as an in vitro cellular model system to evaluate its acute nephrotoxicity of DGA. We found that DGA was indeed toxic to HK-2 cells in all in vitro assays in our study, including a highly sensitive Luminex assay that measures levels of an in vitro biomarker of kidney-specific toxicity, Kidney Injury Molecule 1 (KIM-1). Interestingly, in vitro KIM-1 levels also correlated with in vivo KIM-1 levels in urine collected from rats treated with DGA by daily oral gavage. The use of in vitro and in vivo models towards understanding the effectiveness of an established in vitro system to predict in vivo outcomes would be particularly useful in rapidly screening compounds that are suspected to be unsafe to consumers. The merit of the HK-2 cell model in predicting human toxicity and accelerating the process of food toxicant screening would be especially important for regulatory purposes. Overall, our study not only revealed the value of HK-2 in vitro cell model for nephrotoxicity evaluation, but also uncovered some of the mechanistic aspects of the human proximal tubule injury that DGA may cause.

Adhatoda zeylanica is a dietary supplement ingredient present in several types of dietary supplements, including weight loss, respiratory relief, and immune regulating products. Due to its reported wide range of uses in folk medicine, it was hypothesized that it may have the potential to target multiple organs and lead to a range of toxicity features. As a preliminary evaluation of the safety of this herbal ingredient, an investigation into its effects on the kidney was sought. An in vitro study of its potential nephrotoxicity using the HK-2 human proximal tubule cell line in a variety of functional indicators was performed to capture both general forms of cellular toxicity as well as ones that are specific to proximal tubules. A. zeylanica was only capable of inducing detrimental short-term toxicity to HK-2 cells at relatively high treatment concentrations when exposed directly to the cells. The lack of acute and potent toxicity of A. zeylanica under our experimental conditions calls for further studies to better define its toxicant threshold and establish safe dosage levels.