Protect Kidney Cells Research Articles

Protective effect of pomegranate seed oil against salt toxicity in rat kidneys

Consuming too much salt can have a negative impact on your kidneys. The kidneys play an important role in regulating sodium levels in the body, and excess salt can lead to water retention and increased blood pressure, which in turn can have a negative impact on the kidneys. Excess salt in the diet can contribute to the formation of kidney stones. This is because excess sodium can lead to increased calcium excretion in the urine, which in turn increases the risk of stone formation. An experiment was conducted on rats to study the effect of salt on kidney function. During the experiment, a group of rats received a high dose of salt for a certain period of time, while another group received a regular amount of salt. The results showed that rats that consumed more salt had increased blood pressure and negative changes in kidney function. They also faced problems with fluid retention and the formation of kidney stones. This experiment confirmed that excess salt consumption can negatively affect kidney function and lead to the development of various diseases. Therefore, controlling your salt intake is an important aspect of maintaining a healthy kidney system. Kidney contamination from salt can lead to various diseases such as kidney stones, kidney failure and other genitourinary problems. One way to correct this problem may be to use pomegranate oil. Pomegranate oil contains antioxidants that help reduce inflammation and protect kidney cells from damage. It also improves blood circulation and helps cleanse the kidneys of toxins and waste. Research has shown that consuming pomegranate oil may help improve kidney function, reduce inflammation, and prevent the formation of kidney stones. It can also help lower blood pressure and improve the overall health of the kidney system.

Roles of Reactive Oxygen Species and Autophagy in the Pathogenesis of Cisplatin-Induced Acute Kidney Injury

Cisplatin-induced acute kidney injury (AKI) is the main factor restraining the clinical application of cisplatin. The AKI is associated with high mortality and morbidity, but no effective pharmacological treatment is available at present. As increased levels of reactive oxygen species (ROS) may promote the progression of the injury, the elimination of ROS has been considered as an effective method to prevent the cisplatin-induced AKI. In addition, it has been revealed that an inducer of autophagy could protect kidney cells in the autophagy dependent manner. Induction of autophagy could also modulate the production of ROS in cases of renal injury. Therefore, kidney-targeted antioxidants and/or autophagy are urgently required for the better treatment of AKI. Accumulating evidence has indicated the important roles of gut microbiota in the pathogenesis of AKI. In addition, there is a scientific basis for considering future clinical applications of probiotics and/or prebiotics to treat cisplatin-induced AKI. Thus, gut microbiota might be a promising therapeutic target via the alteration of autophagy for the cancer therapy-induced nephrotoxicity.

Plk2-mediated phosphorylation and translocalization of Nrf2 activates anti-inflammation through p53/Plk2/p21cip1 signaling in acute kidney injury

The Plk2 is a cellular stress-responsive factor that is induced in response to oxidative stress. However, the roles of Plk2 in acute kidney injury (AKI) have not been clarified. We previously found that Plk2 is an interacting factor of Nrf2 in response to cellular stress, since Plk2 is upregulated in the Nrf2-dependent network. Here, we show that the levels of p53, Plk2, p21cip1, and chromatin-bound Nrf2 were all upregulated in kidney tissues of mice or NRK52E cells treated with either cisplatin or methotrexate. Upregulation of Plk2 by p53 led to an increase of Nrf2 in both soluble and chromatin fractions in cisplatin-treated NRK52E cells. Consistently, depletion of Plk2 suppressed the levels of Nrf2. Of note, Plk2 directly phosphorylated Nrf2 at Ser40, which facilitated its interaction with p21cip1 and translocation into the nuclei for the activation of anti-oxidative and anti-inflammatory factors in response to AKI. Together, these findings suggest that Plk2 may serve as an anti-oxidative and anti-inflammatory regulator through the phosphorylation and activation of Nrf2 to protect kidney cells from kidney toxicants and that Plk2 and Nrf2 therefore work cooperatively for the protection and survival of kidney cells from harmful stresses.

Inhibiting Transglutaminase 2 Mediates Kidney Fibrosis via Anti-Apoptosis

Transglutaminase 2 (TG2) is a calcium-dependent transamidating acyltransferase enzyme of the protein-glutamine γ-glutamyltransferase family implicated in kidney injury. In this study, we identified associations between TG2 and chronic kidney disease (CKD) identified by visualizing TG2 in kidney biopsy samples derived from CKD patients using immunohistochemistry and measuring the plasma TG2 concentrations. Our study revealed a connection between TG2 and the pathological markers of kidney disease. We showed high plasma TG2 levels in samples from patients with advanced CKD. In addition, we observed an increase in TG2 expression in tissues concomitant with advanced CKD in human samples. Moreover, we investigated the effect of TG2 inhibition on kidney injury using cystamine, a well-known competitive inhibitor of TG2. TG2 inhibition reduced apoptosis and accumulation of extracellular molecules (ECM) such as fibronectin and pro-inflammatory cytokine IL-8. Collectively, the increased expression of TG2 that was observed in advanced CKD, hence inhibiting TG2 activity, could protect kidney cells from ECM molecule accumulation, apoptosis, and inflammatory responses, thereby preventing kidney fibrosis.

Peptides GWN and GW protect kidney cells against Dasatinib induced mitochondrial injury in a SIRT1 dependent manner

Dasatinib, a small-molecule drug used as a treatment for chronic myeloid leukemia induces mitochondrial damage in embryonic kidney (293 T) cells (p < 0.05). This dasatinib induced mitochondrial injury in kidney cells was mitigated by H3K36me3 activating ovotransferrin-derived peptides GWN and GW. Pre-treatment of kidney cells with GWN and GW lead to elevation of cytoprotective sirtuins, SIRT1 and SIRT3, in response to dasatinib injury (p < 0.01)in vitro. Both peptides, GWN and GW, also reversed dasatinib induced the loss of mitochondria in kidney cells and promoted the protein expression of COX4 (p < 0.01). Mechanistically, loss of SIRT1 in kidney cells abolished the ability of GWN and GW to protect embryonic kidney cells against dasatinib injuryin vitro. Overall, we provide cell based evidence showing that GWN and GW exhibit the ability to protect mitochondria against dasatinib-induced mitochondrial damage in a SIRT1 dependent manner.

Akt Inhibition as Preconditioning Treatment to Protect Kidney Cells against Anoxia.

Lesions issued from the ischemia/reperfusion (I/R) stress are a major challenge in human pathophysiology. Of human organs, the kidney is highly sensitive to I/R because of its high oxygen demand and poor regenerative capacity. Previous studies have shown that targeting the hypusination pathway of eIF5A through GC7 greatly improves ischemic tolerance and can be applied successfully to kidney transplants. The protection process correlates with a metabolic shift from oxidative phosphorylation to glycolysis. Because the protein kinase B Akt is involved in ischemic protective mechanisms and glucose metabolism, we looked for a link between the effects of GC7 and Akt in proximal kidney cells exposed to anoxia or the mitotoxic myxothiazol. We found that GC7 treatment resulted in impaired Akt phosphorylation at the Ser473 and Thr308 sites, so the effects of direct Akt inhibition as a preconditioning protocol on ischemic tolerance were investigated. We evidenced that Akt inhibitors provide huge protection for kidney cells against ischemia and myxothiazol. The pro-survival effect of Akt inhibitors, which is reversible, implied a decrease in mitochondrial ROS production but was not related to metabolic changes or an antioxidant defense increase. Therefore, the inhibition of Akt can be considered as a preconditioning treatment against ischemia.

BCRP/ABCG2 Transporter Regulates Accumulation of Cadmium in Kidney Cells: Role of the Q141K Variant in Modulating Nephrotoxicity.

Exposure to the environmental pollutant cadmium is ubiquitous, as it is present in cigarette smoke and the food supply. Over time, cadmium enters and accumulates in the kidneys, where it causes tubular injury. The breast cancer resistance protein (BCRP, ATP-Binding Cassette G2 ABCG2) is an efflux transporter that mediates the urinary secretion of pharmaceuticals and toxins. The ABCG2 genetic variant Q141K exhibits altered membrane trafficking that results in reduced efflux of BCRP substrates. Here, we sought to 1) evaluate the in vitro and in vivo ability of BCRP to transport cadmium and protect kidney cells from toxicity and 2) determine whether this protection is impaired by the Q141K variant. Cadmium concentrations, cellular stress, and toxicity were quantified in human embryonic kidney 293 cells expressing an empty vector (EV), BCRP wild-type (WT), or variant (Q141K) gene. Treatment with CdCl2 resulted in greater accumulation of cadmium and apoptosis in EV cells relative to WT cells. Exposure to CdCl2 induced expression of stress-related genes and proteins including MT-1A/MT-2A, NAD(P)H quinone dehydrogenase 1, and heme oxygenase-1 to a higher extent in EV cells compared with WT cells. Notably, the Q141K variant protected against CdCl2-induced activation of stress genes and cytotoxicity, but this protection was to a lesser magnitude than observed with WT BCRP. Lastly, concentrations of cadmium in the kidneys of Bcrp knockout mice were 40% higher than in WT mice, confirming that cadmium is an in vivo substrate of BCRP. In conclusion, BCRP prevents the accumulation of cadmium and protects against toxicity, a response that is impaired by the Q141K variant. SIGNIFICANCE STATEMENT: The breast cancer resistance protein transporter lowers cellular accumulation of the toxic heavy metal cadmium. This protective function is partially attenuated by the Q141K genetic variant in the ABCG2 gene.

Pyrroloquinoline Quinone Inhibits Oxidative Stress in Rats with Diabetic Nephropathy.

BackgroundDiabetic nephropathy (DN) is one of the chronic microvascular complications of diabetes. This study focused on the protective effects of pyrroloquinoline quinone (PQQ) on oxidative stress (OS) in DN.Material/MethodsThirty Sprague Dawley rats were randomly selected for this study; 10 rats were randomly selected as the control group. The other 20 rats were established for the DN model. After establishment of the successful model, the DN model rats were randomly divided into a DN group and a PQQ group. The PQQ group was fed with a PQQ diet. Blood urea nitrogen (BUN), serum creatinine (SCr), and blood glucose levels were measured in each group, and OS-related protein expression and AMPK pathway were detected by western blot and quantitative real-time polymerase chain reaction (qRT-PCR). At the same time, we constructed a DN model by culturing NRK-52E cells with high glucose to detect the molecular mechanisms.ResultsThe kidney function of the DN group was significantly decreased, SCr and BUN levels were significantly increased, and the renal structure under the microscope was disordered, and interstitial edema was obvious. The expression of SOD1, SOD2, GPX1, and GPX3 were significantly decreased, and the level of reactive oxygen species (ROS) was significantly increased. PQQ treatment can effectively alleviate renal function, improve structural damage, and inhibit OS. In vivo, PQQ can effectively inhibit high glucose-induced OS damage and activate the AMPK/FOXO3a signaling pathway.ConclusionsPQQ improves renal structural damage and functional damage, and protects kidney cells in DN by inhibiting OS, which may be related to activating the AMPK/FOXO3a pathway.

Ursolic acid alleviates inflammation and against diabetes‑induced nephropathy through TLR4‑mediated inflammatory pathway.

Ursolic acid (UA) is a triterpenoid isolated from Chinese herbal medicine. It is extensively distributed in the plant kingdom in at least 63Chinese herbal medicines of 26families. UA has multiple bioactivities, including anti‑viral hepatitis, antitumor, anti‑oxidation, anti‑bacterium and anti‑inflammation. The aim of this invitro study was to examine the effects of UA on diabetes‑induced nephropathy and its possible mechanism. In mice with diabetes‑induced nephropathy, UA increased the body weight, reduced kidney/body weight index, protected kidney cells, alleviated inflammation [tumor necrosis factor (TNF)‑α, interleukin (IL)‑1β, IL‑6 and IL‑18 levels] and kidney cell damage. It was also indicated that UA suppressed Toll‑like receptor 4 (TLR4), myeloid differentiation factor 88 and nuclear factor‑κB protein expression in mice with diabetes‑induced nephropathy. The inhibition of TLR4 increased the anti‑inflammation of UA on inflammation in rat with diabetes‑induced nephropathy through the TLR4 signaling pathway. In conclusion, UA alleviates inflammation and inhibits diabetes‑induced nephropathy through a TLR4‑mediated inflammatory pathway. The present findings indicated that UA may be a possible therapeutic agent against diabetic nephropathy.

Exogenous pentraxin-3 inhibits the reactive oxygen species-mitochondrial and apoptosis pathway in acute kidney injury.

Pentraxin-3 (PTX3) is a long-form member of the pentraxin family of proteins that has been studied in inflammatory diseases and in various organs. We found that PTX3 protects kidney cells during ischemia and proinflammatory acute kidney injury. The aim of this study was to develop an in vitro experimental model of acute kidney injury and to analyze the protective mechanism of exogenous recombinant PTX3. In this study, cells of the HK-2 renal tubular cell line were treated with a calcium ionophore (A23187), which induced injury by increasing intracellular calcium concentrations and inducing calpain activity and the generation of reactive oxygen species. Exposure of cells to PTX3 significantly attenuated these effects. In addition, the activity of caspase-3 and PARP-1 were decreased in ischemic cells exposed to exogenous recombinant PTX3. PTX3 stabilized the mitochondrial membrane potential and suppressed apoptosis, resulting in the protection of renal tubular cells from ischemic injury.

Alpha lipoic acid attenuates cadmium-induced nephrotoxicity via the mitochondrial apoptotic pathways in rat

Alpha lipoic acid (α-LA), a potent antioxidant, is protective against acute nephrotoxicity. In the present study, the attenuation of cadmium (Cd)-induced kidney injury by α-LA on was investigated in a rat model. Exposure to 50 mg/L Cd for 12 weeks increased kidney index and Cd content, malondialdehyde (MDA) levels, and histological damage to the renal cortex, and decreased the activities of glutathione peroxidase (GSH-Px), superoxide dismutase (SOD), catalase (CAT), and glutathione (GSH). Treatment with 50 mg/L Cd also damaged renal cell mitochondria and nuclei, and activated the mitochondrial apoptosis pathway, indicated by increased gene and protein expression/activation of caspase-9, caspase-3, poly ADP-ribose polymerase (PARP) and Bcl-2 adenovirus E1a nineteen kilodalton interacting protein 3 (BNIP3), and translocation of cytochrome c (cyt c), apoptosis-inducing factor (AIF), and endonuclease G (Endo G). However, simultaneous supplementation with α-LA (50 mg/kg·bw) protected kidney cells from Cd-induced cytotoxicity by reducing MDA levels and Cd content, restoring endogenous enzyme activities, renewing mitochondrial function, and preventing activation of the mitochondria apoptosis pathway.

Metabolic acidosis inhibits AMPK function in kidney cells

The metabolic sensor AMP‐activated protein kinase (AMPK) is stimulated by cellular metabolic depletion. We have shown that AMPK activation inhibits kidney membrane transport proteins. AMPK‐activated processes protect kidney cells from further metabolic depletion and damage. AMPK is tightly regulated, and its pharmacological activation can protect kidneys from superimposed injury, such as acute kidney injury (AKI). Conversely, AMPK is inhibited in chronic kidney disease (CKD). Therefore, pharmacologic AMPK activators are proposed as therapies to slow CKD progression. However, the mechanisms by which AMPK may promote kidney survival are unclear. CKD results in metabolic acidosis (MA) due to the inability of kidneys to excrete non‐volatile acid. MA, if untreated, has severe health sequelae such as worsening of kidney function. We hypothesized that there is cross‐talk between acid‐base status and AMPK signaling, and that dysregulation of AMPK function by MA disrupts kidney regeneration in the setting of CKD. We used kidney epithelial cell lines in culture and adult male C57BL/6 mice (WT) and AMPKβ1‐KO mice for our experiments. Cells were exposed to media at either pH 7.3–7.4 (control) or 6.9–7.0 (acidic) for 3 d ± an AMPK activator (last 16 h). We found that, as compared to cells grown at pH 7.4, kidney cells grown in acidic media have reduced baseline AMPK activity and blunted pharmacologic AMPK activation. We then evaluated changes in AMPK function in WT mice fed a normal diet vs. WT mice given 1.5% saccharin ± 0.28 M NH4Cl in drinking water for 2 mo. To evaluate the AMPK pathway in kidney tissue, we examined levels of phosphorylation of acetyl CoA carboxylase (pACC) by immunoblot. Mice on the acidogenic diet developed MA without significant weight loss compared to mice on the control diet (blood pH 7.2 vs 7.3 ± 0.01). In mice after UNX, the superimposed MA induced a statistically significant decrease in pACC, compared to mice with UNX on a control diet. We also evaluated differences in BUN in WT vs. AMPKβ1‐KO mice 3 mos. after sham surgery or UNX, a model for reduced kidney mass. Both WT and KO mice post‐UNX had significant worsening of kidney function (higher BUN) compared to sham‐operated mice of the same genotype. However, we did not observe any significant differences in BUN between WT and KO mice following sham or UNX. Our results point to worsening in kidney function post‐UNX and to a direct inhibition of the AMPK pathway in the setting of reduced kidney mass and MA. This AMPK inhibition may be detrimental to kidney regeneration in these settings.Support or Funding InformationKeck School of Medicine of USC; USC/UKRO Kidney Research CenterThis abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Methionine Sulfoxide Reductase A Deficiency Exacerbates Cisplatin-Induced Nephrotoxicity via Increased Mitochondrial Damage and Renal Cell Death.

Methionine sulfoxide reductase A (MsrA), which is abundantly localized in the mitochondria, reduces methionine-S-sulfoxide, scavenging reactive oxygen species (ROS). Cisplatin, an anticancer drug, accumulates at high levels in the mitochondria of renal cells, causing mitochondrial impairment that ultimately leads to nephrotoxicity. Here, we investigated the role of MsrA in cisplatin-induced mitochondrial damage and kidney cell death using MsrA gene-deleted (MsrA-/-) mice. Cisplatin injection resulted in increases of ROS production, methionine oxidation, and oxidative damage in the kidneys. This oxidative stress was greater in MsrA-/- mouse kidneys than in wild-type (MsrA+/+) mouse kidneys. MsrA gene deletion exacerbated cisplatin-induced reductions in the expression and activity of MsrA and MsrBs, and the expression of thioredoxin 1, glutathione peroxidase 1 and 4, mitochondrial superoxide dismutase, cystathionine-β-synthase, and cystathionine-γ-lyase. Cisplatin induced swelling, cristae loss, and fragmentation of mitochondria with increased lipid peroxidation, more so in MsrA-/- than in MsrA+/+ kidneys. The ratio of mitochondrial fission regulator (Fis1) to fusion regulator (Opa1) was higher in MsrA-/- than MsrA+/+ mice. MsrA deletion exacerbated cisplatin-induced increases in Bax to Bcl-2 ratio, cleaved caspase-3 level, and apoptosis, whereas MsrA overexpression attenuated cisplatin-induced oxidative stress and apoptosis. MsrA gene deletion in mice exacerbates cisplatin-induced renal injury through increases of mitochondrial susceptibility, whereas MsrA overexpression protects cells against cisplatin. This study demonstrates that MsrA protects kidney cells against cisplatin-induced methionine oxidation, oxidative stress, mitochondrial damage, and apoptosis, suggesting that MsrA could be a useful target protein for the treatment of cisplatin-induced nephrotoxicity. Antioxid. Redox Signal. 27, 727-741.

Caffeic Acid Phenethyl Ester Reduces Ischemia-Induced Kidney Mitochondrial Injury in Rats.

During partial nephrectomy, the avoidance of ischemic renal damage is extremely important as duration of renal artery clamping (i.e., ischemia) influences postoperative kidney function. Mitochondria (main producer of ATP in the cell) are very sensitive to ischemia and undergo damage during oxidative stress. Finding of a compound which diminishes ischemic injury to kidney is of great importance. Caffeic acid phenethyl ester (CAPE), biologically active compound of propolis, might be one of the promising therapeutic agents against ischemia-caused damage. Despite wide range of biological activities of CAPE, detailed biochemical mechanisms of its action at the level of mitochondria during ischemia are poorly described and need to be investigated. We investigated if CAPE (22 mg/kg and 34 mg/kg, injected intraperitoneally) has protective effects against short (20 min) and longer time (40 min) rat kidney ischemia in an in vitro ischemia model. CAPE ameliorates in part ischemia-induced renal mitochondrial injury, improves oxidative phosphorylation with complex I-dependent substrate glutamate/malate, increases Ca2+ uptake by mitochondria, blocks ischemia-induced caspase-3 activation, and protects kidney cells from ischemia-induced necrosis. The protective effects on mitochondrial respiration rates were seen after shorter (20 min) time of ischemia whereas reduction of apotosis and necrosis and increase in Ca2+ uptake were revealed after both, shorter and longer time of ischemia.

Protection against oxidative stress-induced apoptosis in kidney epithelium by Angelica and Astragalus

Ethnopharmacological relevanceAstragalus membranaceus either alone or in combination with Angelica sinensis has been used traditionally for kidney disease in East Asia and China for thousands of years. Previous studies using in vivo animal models have shown the benefits of these medicinal herbs in kidney diseases that involve oxidative stress. However, the mechanisms by which these medicinal herbs protect kidney cells remain largely unknown. Aim of the studyTo investigate the mechanisms by which ethanol, methanol and aqueous crude extracts of roots of A. membranaceus and A. sinensis afford protection to human kidney proximal tubular epithelial cells, using an in vitro model of oxidative stress. Materials and methodsEthanol, methanol and aqueous extracts of roots of A. membranaceus and A. sinensis were prepared by a three-solvent sequential process. HK2 human kidney proximal tubular epithelial cells were treated with H2O2 alone (0.5mM) or in combination with different concentrations of extracts. Cell mitosis and death (microscopy) and cell viability (MTT assay) were compared. Western immunoblot was used to study expression of apoptosis-related proteins (pro-apoptotic Bax andanti-apoptotic Bcl-XL), and cell survival (NFκB subunits p65 and p50), pro-inflammatory (TNF-α) and protective (TGFβ1) proteins. ResultsH2O2-induced oxidative stress significantly increased apoptosis and reduced cell survival; upregulated pro-apoptotic and down-regulated Bcl-XL; increased NFκB (p65, p50); increased TNFα and decreased TGFβ1. All changes indicated kidney damage and dysfunction. All were modulated by all extracts of both plant species, except for NFκB which was only modulated by extracts of A. membranaceus. ConclusionsIn conclusion, in a model of oxidative stress that might occur after nephrotoxicity, the plant extracts were protective via anti-apoptotic and anti-inflammatory mechanisms.

Metformin Protects Kidney Cells From Insulin-Mediated Genotoxicity In Vitro and in Male Zucker Diabetic Fatty Rats.

Hyperinsulinemia is thought to enhance cancer risk. A possible mechanism is induction of oxidative stress and DNA damage by insulin, Here, the effect of a combination of metformin with insulin was investigated in vitro and in vivo. The rationales for this were the reported antioxidative properties of metformin and the aim to gain further insights into the mechanisms responsible for protecting the genome from insulin-mediated oxidative stress and damage. The comet assay, a micronucleus frequency test, and a mammalian gene mutation assay were used to evaluate the DNA damage produced by insulin alone or in combination with metformin. For analysis of antioxidant activity, oxidative stress, and mitochondrial disturbances, the cell-free ferric reducing antioxidant power assay, the superoxide-sensitive dye dihydroethidium, and the mitochondrial membrane potential-sensitive dye 5,5',6,6'tetrachloro-1,1',3,3'-tetraethylbenzimidazol-carbocyanine iodide were applied. Accumulation of p53 and pAKT were analyzed. As an in vivo model, hyperinsulinemic Zucker diabetic fatty rats, additionally exposed to insulin during a hyperinsulinemic-euglycemic clamp, were treated with metformin. In the rat kidney samples, dihydroethidium staining, p53 and pAKT analysis, and quantification of the oxidized DNA base 8-oxo-7,8-dihydro-2'-deoxyguanosine were performed. Metformin did not show intrinsic antioxidant activity in the cell-free assay, but protected cultured cells from insulin-mediated oxidative stress, DNA damage, and mutation. Treatment of the rats with metformin protected their kidneys from oxidative stress and genomic damage induced by hyperinsulinemia. Metformin may protect patients from genomic damage induced by elevated insulin levels. This may support efforts to reduce the elevated cancer risk that is associated with hyperinsulinemia.

SGK-1 protects kidney cells against apoptosis induced by ceramide and TNF-α.

Ceramide regulates several different cellular responses including mechanisms leading to apoptosis. Serum- and glucocorticoid-inducible protein kinase (SGK)-1 is a serine threonine kinase, which activates survival pathways in response to stress stimuli. Recently, we demonstrated an anti-apoptotic role of SGK-1 in human umbilical endothelial cells treated with high glucose. In the present study, since ceramide induces apoptosis by multiple mechanisms in diabetes and its complication such as nephropathy, we aimed to investigate whether SGK-1 may protect even against apoptosis induced by ceramide in kidney cells. Human embryonic kidney (HEK)-293 cells stable transfected with SGK-1 wild type (SGK-1wt) and its dominant negative gene (SGK-1dn) have been used in this study. Apoptotic stimuli were induced by C2-ceramide and TNF-α to increase endogenous synthesis of ceramide. Upon activation with these stimuli, SGK-1wt transfected cells have a statistically significant reduction of apoptosis compared with SGK-1dn cells (P<0.001). This protection was dependent on activation of caspase-3 and Poly-ADP-ribose-polymerase-1 (PARP-1) cleavage. SGK-1 and AKT-1 two highly homologous kinases differently reacted to ceramide treatment, since SGK-1 increases in response to apoptotic stimulus while AKT-1 decreases. This enhancement of SGK-1 was dependent on p38-mitogen-activated-protein kinases (p38MAPK), cyclic-adenosine-monophosphate/protein kinase A (cAMP/PKA) and phosphoinositide-3-kinase (PI3K) pathways. Especially, by using selective LY294002 inhibitor, we demonstrated that the most involved pathway in the SGK-1 mediated process of protection was PI3K. Treatment with inhibitor of SGK-1 (GSK650394) significantly enhanced TNF-α-dependent apoptosis in HEK-293 cells overexpressing SGK-1wt. Caspase-3, -8 and -9 selective inhibitors confirmed that SGK-1 reduced the activation of caspase-dependent apoptosis, probably by both intrinsic and extrinsic pathways. In conclusion, we demonstrated that in kidney cells, overexpression of SGK-1 is protective against ceramide-induced apoptosis and the role of SGK-1 can be potentially explored as a therapeutic target in conditions like diabetes, where ceramide levels are increased.

Fumonisin B1 induces autophagic cell death via activation of ERN1-MAPK8/9/10 pathway in monkey kidney MARC-145 cells.

Mycotoxins are secondary fungal metabolites that are capable of inducing a variety of toxic effects in animals and humans resulting from the consumption of the contaminated food. Understanding the mechanisms of the toxicities behind these mycotoxins is required to develop mechanism-based approach to counteract their toxic potential. Fumonisin B1 (FB1) is the most prevalent member of fumonisins that are a group of mycotoxins produced primarily by Fusarium verticillioides and Fusarium proliferatum. Kidney is one of the primary target organs for FB1 action. Using monkey kidney MARC-145 cells as an intro model, we found that FB1 induced caspase-independent programmed cell death accompanied with autophagy induction. Inhibition of autophagy by either chemical inhibitors or RNAi approach led to a significant reduction in cell death by FB1 exposure, indicating possible involvement of autophagy-mediated cell death in nephrotoxicity of FB1. Further mechanistic investigation revealed that activation of ERN1-MAPK8/9/10 axis played a critical role in autophagy induction and autophagy-mediated cell death by FB1 exposure. In addition, we demonstrated that disruption of sphingolipid metabolism was an apical event in FB1-induced ERN1-MAPK8/9/10-mediated autophagic cell death in MARC-145 cells. Lastly, we identified curcumin, a naturally occurring plant phenolic compound, as a possible anti-FB1 agent that can be used to protect kidney cells from FB1-induced cell death through inhibition of MAPK8/9/10 activation.

Cyclic adenosine monophosphate protects renal cell lines against amphotericin B toxicity in a PKA-independent manner

Amphotericin B is the “gold standard” agent in the management of serious systemic fungal infections. However, this drug can cause nephrotoxicity, which contributes up to 25% of all acute kidney injuries in critically ill patients. Cyclic adenosine monophosphate can protect kidney cells from death due to injury or drug exposure in some cases. Hence, the objective of this work was to evaluate if cAMP could prevent cell death that occurs in renal cell lines subjected to AmB treatment and, if so, to assess the involvement of PKA in the transduction of this signal. Two different renal cell lines (LLC-PK1 and MDCK) were used in this study. MTT and flow cytometry assays showed increased cell survival when cells were exposed to cAMP in a PKA-independent manner, which was confirmed by western blot. This finding suggests that cAMP (db-cAMP) may prevent cell death caused by exposure to AmB. This is the first time this effect has been identified when renal cells are exposed to AmB’s nephrotoxic potential.

Beneficial effect of lycopene on anti-diabetic nephropathy through diminishing inflammatory response and oxidative stress.

Lycopene is widely used for nutritional supplementation, but the potential benefits in diabetic nephropathy (DN) remains unknown. This study aimed to highlight the therapeutic prospect of lycopene against streptozotocin (STZ)-induced kidney injury in mice. During the process of the experiments, biochemical kits were employed to determine the diabetes-metabolic parameters in STZ-lesioned mice. Routine pathological and ultrastructural observations were screened for the histological changes of kidney tissue. Moreover, immunohistochemical staining was used to investigate the inflammatory conditions expressed in kidney tissue. Furthermore, intrarenal heme oxygenase 1 (HO-1) mRNA level was assayed via RT-PCR and Western blot analyses. The results showed that lycopene alleviated the lesioned signs of DN mice induced by STZ, accompanied with the increase in body weight, reduced serum concentrations of blood sugar and low-density lipoprotein cholesterol (LDL-C), elevated high-density lipoprotein cholesterol (HDL-C) level, and the decrease in urine protein content. In addition, oxidative defense patterns in the kidneys of DN mice were ameliorated, as shown in augmented bioactivities of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and in turn lowered malondialdehyde (MDA) content. The immunohistochemical experiment exhibited that lycopene intake contributed to attenuation of nuclear factor-kappa B (NF-κB) and tumor necrosis factor alpha (TNF-α) expressions in kidney tissue. Moreover, intrarenal HO-1 level was up-regulated in the presence of lycopene. Our findings provide the evidence that lycopene protects kidney cells from STZ-induced lesions via inhibiting NF-κB signal pathway for anti-inflammation and attenuating oxidative stress for anti-dysmetabolism.