Animal Models Of Kidney Injury Research Articles

Protective Effect of Silymarin on Attenuating of Rhabdomyolysis -induced Acute Kidney Injury in Animal Models

Acute kidney injury is one of the most serious complications of rhabdomyolysis characterized by an acute loss of renal function. The study aims to investigate the renoprotective effect of silymarin against rhabdomyolysis-induced acute kidney injury in rats. Twenty-four healthy rats were equally divided into three groups: control, induction, and treatment groups. Rats in the control and induction groups received distilled water, while rats in the treatment group received silymarin (50 mg /kg/day p.o) for three consecutive days. On the first day, all rats (except rats of control group) received a single intramuscular injection of glycerol (10 mL/kg, 50% v/v in sterile saline) divided equally into each hind leg for induction of acute kidney injury. On the fourth day of experiment, blood and kidney,s were collected from all rats for biochemical and histopathological assay. Silymarin efficiently attenuated acute kidney injury caused by rhabdomyolysis evidenced by a significant decrease in serum creatinine and blood urea nitrogen(BUN), along with a significant reduction in renal homogenate levels of TNF-α, IL-6, NF-κB, caspase-3, and MDA with a significant increase in GSH level, which was further confirmed by improving renal histological changes when compared to that of induction group. This study found that silymarin has a potential attenuating effect on acute kidney injury due to its antioxidant, anti-inflammatory and antiapoptotic actions.

Enhanced fatty acid oxidation through metformin and baicalin as therapy for COVID-19 and associated inflammatory states in lung and kidney

Progressive respiratory failure is the primary cause of death in the coronavirus disease 2019 (COVID-19) pandemic. It is the final outcome of the acute respiratory distress syndrome (ARDS), characterized by an initial exacerbated inflammatory response, metabolic derangement and ultimate tissue scarring. A positive balance of cellular energy may result crucial for the recovery of clinical COVID-19. Hence, we asked if two key pathways involved in cellular energy generation, AMP-activated protein kinase (AMPK)/acetyl-CoA carboxylase (ACC) signaling and fatty acid oxidation (FAO) could be beneficial. We tested the drugs metformin (AMPK activator) and baicalin (CPT1A activator) in different experimental models mimicking COVID-19 associated inflammation in lung and kidney. We also studied two different cohorts of COVID-19 patients that had been previously treated with metformin. These drugs ameliorated lung damage in an ARDS animal model, while activation of AMPK/ACC signaling increased mitochondrial function and decreased TGF-β-induced fibrosis, apoptosis and inflammation markers in lung epithelial cells. Similar results were observed with two indole derivatives, IND6 and IND8 with AMPK activating capacity. Consistently, a reduced time of hospitalization and need of intensive care was observed in COVID-19 patients previously exposed to metformin. Baicalin also mitigated the activation of pro-inflammatory bone marrow-derived macrophages (BMDMs) and reduced kidney fibrosis in two animal models of kidney injury, another key target of COVID-19. In human epithelial lung and kidney cells, both drugs improved mitochondrial function and prevented TGF-β-induced renal epithelial cell dedifferentiation. Our results support that favoring cellular energy production through enhanced FAO may prove useful in the prevention of COVID-19-induced lung and renal damage.

Renal-Protective Roles of Lipoic Acid in Kidney Disease

The kidney is a crucial organ that eliminates metabolic waste and reabsorbs nutritious elements. It also participates in the regulation of blood pressure, maintenance of electrolyte balance and blood pH homeostasis, as well as erythropoiesis and vitamin D maturation. Due to such a heavy workload, the kidney is an energy-demanding organ and is constantly exposed to endogenous and exogenous insults, leading to the development of either acute kidney injury (AKI) or chronic kidney disease (CKD). Nevertheless, there are no therapeutic managements to treat AKI or CKD effectively. Therefore, novel therapeutic approaches for fighting kidney injury are urgently needed. This review article discusses the role of α-lipoic acid (ALA) in preventing and treating kidney diseases. We focus on various animal models of kidney injury by which the underlying renoprotective mechanisms of ALA have been unraveled. The animal models covered include diabetic nephropathy, sepsis-induced kidney injury, renal ischemic injury, unilateral ureteral obstruction, and kidney injuries induced by folic acid and metals such as cisplatin, cadmium, and iron. We highlight the common mechanisms of ALA's renal protective actions that include decreasing oxidative damage, increasing antioxidant capacities, counteracting inflammation, mitigating renal fibrosis, and attenuating nephron cell death. It is by these mechanisms that ALA achieves its biological function of alleviating kidney injury and improving kidney function. Nevertheless, we also point out that more comprehensive, preclinical, and clinical studies will be needed to make ALA a better therapeutic agent for targeting kidney disorders.

High sodium intake does not worsen low potassium-induced kidney damage.

High sodium and low potassium intake have both been linked to poor cardiovascular health outcomes and increased mortality rates. A combination of the two is thought to be particularly detrimental. While mechanisms are multiple, the kidney is an important target of harmful effects and low potassium influences on both proximal and distal nephron segments are especially potent. We recently reported that a combined high sodium/low potassium diet causes kidney injury and that low potassium in isolation can have similar effects. However, how sodium intake alters this process is not well-understood. Here we tested the hypothesis that a high sodium intake amplifies effects of low dietary potassium on kidney injury. We observed adding high sodium to low potassium caused an expected increase in blood pressure, but did not worsen markers of kidney injury, inflammation, and fibrosis. It also did not increase abundance or phosphorylation of the sodium chloride cotransporter or its regulatory kinases, SPAK and OxSR1, known renal targets of low potassium. Findings support the claim that dietary potassium deficiency, and not high sodium, is a dominant factor affecting kidney injury in animal models of high sodium/low potassium intake. This suggests further investigation is required to identify optimal ranges of sodium and potassium intake in both healthy populations and in those with kidney disease.

Transcription Factor Sox9 Exacerbates Kidney Injury through Inhibition of MicroRNA-96-5p and Activation of the Trib3/IL-6 Axis

Introduction: Our study investigated the possible mechanisms of the role of the transcription factor Sox9 in the development and progression of kidney injury through regulation of the miR-96-5p/Trib3/IL-6 axis. Methods: Bioinformatics analysis was performed to identify differentially expressed genes in kidney injury and normal tissues. An in vivo animal model of kidney injury and an in vitro cellular model of kidney injury were constructed using LPS induction in 8-week-old female C57BL/6 mice and human normal renal tubular epithelial cells HK-2 for studying the possible roles of Sox9, miR-96-5p, Trib3, and IL-6 in kidney injury. Results: Sox9 was highly expressed in both mouse and cellular models of kidney injury. Sox9 was significantly enriched in the promoter region of miR-96-5p and repressed miR-96-5p expression. Trib3 was highly expressed in both mouse and cellular models of kidney injury and promoted inflammatory responses and kidney injury. In addition, Trib3 promoted IL-6 expression, which was highly expressed in kidney injury, and promoted the inflammatory response and extent of injury in kidney tissue. In vivo and in vitro experiments confirmed that the knockdown of Sox9 improved the inflammatory response and fibrosis of mouse kidney tissues and HK-2 cells, while the ameliorative effect of silencing Sox9 was inhibited by overexpression of IL-6. Conclusion: Collectively, Sox9 up-regulates miR-96-5p-mediated Trib3 and activates the IL-6 signaling pathway to exacerbate the inflammatory response, ultimately promoting the development and progression of kidney injury.

The Role and Mechanism of Lysine Methyltransferase and Arginine Methyltransferase in Kidney Diseases.

Methylation can occur in both histones and non-histones. Key lysine and arginine methyltransferases under investigation for renal disease treatment include enhancer of zeste homolog 2 (EZH2), G9a, disruptor of telomeric silencing 1-like protein (DOT1L), and protein arginine methyltransferases (PRMT) 1 and 5. Recent studies have shown that methyltransferases expression and activity are also increased in several animal models of kidney injury, such as acute kidney injury(AKI), obstructive nephropathy, diabetic nephropathy and lupus nephritis. The inhibition of most methyltransferases can attenuate kidney injury, while the role of methyltransferase in different animal models remains controversial. In this article, we summarize the role and mechanism of lysine methyltransferase and arginine methyltransferase in various kidney diseases and highlight methyltransferase as a potential therapeutic target for kidney diseases.

Renoprotective Effect of Vardenafil and Avanafil in Contrast-Induced Nephropathy: Emerging Evidence from an Animal Model.

The potential renoprotective effects of vardenafil (VAR) have been evaluated in a very limited number of studies using acute kidney injury animal models other than contrast-induced nephropathy (CIN) with promising results, while avanafil (AVA) has not been evaluated in this respect before. The purpose of this study was to evaluate for the first time the potential renoprotective effect of VAR and AVA in a rat model of CIN. Twenty-five male Wistar rats were equally assigned into five groups: control, CIN, CIN+N-acetyl cysteine (NAC) (100 mg/kg/day) as a positive control, CIN+VAR (10 mg/kg/day) and CIN+AVA (50 mg/kg/day). CIN was induced by dehydration, inhibition of prostaglandin and nitric oxide synthesis as well as exposure to the contrast medium (CM). Serum Cr (sCr) levels were measured at 24 and 48 h after CIN induction. At 48 h of CM exposure, animals were sacrificed. Matrix metalloproteinase (MMP) 2 (MMP-2) and MMP-9, kidney injury molecule 1 (KIM-1) and cystatin-C (Cys-C) were measured on renal tissue. Histopathological findings were evaluated on kidney tissue. All treatment groups had close to normal kidney appearance. sCr levels subsided in all treatment groups compared to CIN group at 48 h following CIN induction. A significant decline in the levels of MMP-2, MMP-9, KIM-1 and Cys-C compared to CIN group was observed. These results provide emerging evidence that VAR and AVA may have the potential to prevent CIN.

Effect of Mineral-Balanced Deep-Sea Water on Kidney Function and Renal Oxidative Stress Markers in Rats Fed a High-Salt Diet.

This study investigated the effect of mineral-balanced deep-sea water (DSW) on kidney health using an animal model of kidney injury due to a high-sodium diet. High magnesium/low sodium (HMLS) and high magnesium/high calcium (HMHC) DSW samples with different mineral contents were prepared. Sprague–Dawley rats were fed an 8% sodium chloride (NaCl) diet for four weeks to induce kidney injury, and each group was supplied with purified water or mineral water. Kidney injury was observed in the NaCl group according to increased kidney injury markers and malondialdehydes, providing evidence of oxidative stress. However, the kidney injury was repaired by the intake of mineral-balanced DSW. It was confirmed that the HMLS and HMHC groups showed improved Na+ excretion through the urine. Kidney injury markers in urine decreased and upregulation of low-density lipoprotein receptor-related protein2 mRNA expression was observed in the HMLS and HMHC groups. In addition, superoxide dismutase activity was increased in the HMHC groups. The gene expression patterns of the RNA sequencing were similar between the CON and HMLS groups. These results suggest that DSW has beneficial effects on kidney health due to the balanced magnesium and calcium levels in models of kidney injury caused by excessive sodium intake.

Secretory Leukocyte Proteinase Inhibitor Protects Acute Kidney Injury Through Immune and Non-Immune Pathways.

Acute kidney injury (AKI) is characterized by rapid loss of excretory function and is the clinical manifestation of several disorders affecting the kidney. The aim of the present study was to investigate the mechanism of action of Secretory Leukocyte Proteinase Inhibitor (SLPI) that protects the kidneys form AKI. In vivo and in vitro experiments were performed to assess the effect of SLPI on kidney injury. Animal models of kidney injury was generated by 40 min obstruction of kidney artery and vein (ischemia-reperfusion injury model) or daily administration of 60 mg/kg/day of gentamicine for 5 day (gentamicin-associated AKI model). For in vitro assessment, human renal epithelium HK-2 cells were cultured under serum starvation conditions or with tacrolimus. The administration of SLPI (250 μg/kg, i.p.) reduced elevated plasma creatinine and blood urea nitrogen levels, tissue myeloperoxidase content, and acute tubular necrosis induced by kidney damage. Furthermore, SLPI treatment reduced CD86, CD68, CD14, CCL2, TNFα, and IL-10 transcripts in kidney biopsies. To further analyze a direct effect of SLPI on renal epithelial cells, HK-2 cells from human renal epithelium were cultured under serum starvation conditions or with tacrolimus. Both conditions induced apoptosis of HK-2 cells which was reduced when SLPI was present in the culture medium. Furthermore, SLPI favored the proliferation and migration of HK-2 cells. An analysis of the gene profiles of HK-2 cells treated with calcineurin inhibitors affected inflammatory and non-inflammatory pathways that were reversed by SLPI. Among them, SLPI down modulated the expression of CCL2, SLC5A3, and BECN1 but up-regulated the expression of TLR4, ATF4, ATF6, HSP90B, BBC3 SLC2A1, and TNFRSF10B. Overall, these results suggest that SLPI, in addition to its activity on immune cells, may directly target tubular epithelial cells of the kidney to mediate the nephroprotective activity in AKI.

Endoplasmic Reticulum Stress-Activated PERK-eIF2α-ATF4 Signaling Pathway is Involved in the Ameliorative Effects of Ginseng Polysaccharides against Cisplatin-Induced Nephrotoxicity in Mice.

Although previous studies have reported that saponins (ginsenosides, the major active and most representative ingredients in Panax ginseng C.A. Meyer) exerted a good ameliorative effect on cisplatin (CP)-induced acute kidney injury in animal models, little attention has been paid to a large number of polysaccharides isolated and purified from ginseng. This work aimed to investigate the protective effect and the possible molecular mechanism of ginseng polysaccharide (WGP) on CP-induced kidney toxicology in mice. The results from biomarker analysis including serum creatinine (CRE) and blood urea nitrogen (BUN) confirmed the protective effect of WGP at 200 and 400 mg/kg on CP-induced renal-toxicology. We found that WGP reduces the apoptosis of kidney cells by inhibiting endoplasmic reticulum (ER) stress caused by CP, which is manifested by increased phosphorylation of PERK. In addition, the apoptosis-associated with caspase 3 activation in renal cells induced by CP was inhibited after administration of WGP, and the phosphorylation levels of PI3K and AKT were also reduced significantly. We also demonstrated that after exposure to CP, the unfolded protein response signaling pathway PERK-eIF2α-ATF4 axis was significantly activated, manifested by increased phosphorylation of eIF2α and increased expression of ATF4 and CHOP. Interestingly, the WGP administration improves this situation. Furthermore, the supplement of WGP inhibited the overexpression of nuclear factor-kappa B p65 (NF-κB p65) and tumor necrosis factor-α (TNF-α) caused by CP exposure. In short, for the first time, our findings indicated that WGP could effectively prevent CP-induced ER stress, inflammation, and apoptosis in renal cells, in part, by regulating the PI3K/AKT and PERK-eIF2α-ATF4 signaling pathways.

Histone Methyltransferase EZH2: A Potential Therapeutic Target for Kidney Diseases.

Enhancer of zeste homolog 2 (EZH2) is a histone-lysine N-methyltransferase enzyme that catalyzes the addition of methyl groups to histone H3 at lysine 27, leading to gene silencing. Mutation or over-expression of EZH2 has been linked to many cancers including renal carcinoma. Recent studies have shown that EZH2 expression and activity are also increased in several animal models of kidney injury, such as acute kidney injury (AKI), renal fibrosis, diabetic nephropathy, lupus nephritis (LN), and renal transplantation rejection. The pharmacological and/or genetic inhibition of EZH2 can alleviate AKI, renal fibrosis, and LN, but potentiate podocyte injury in animal models, suggesting that the functional role of EZH2 varies with renal cell type and disease model. In this article, we summarize the role of EZH2 in the pathology of renal injury and relevant mechanisms and highlight EZH2 as a potential therapeutic target for kidney diseases.

Analysis Protocol for the Quantification of Renal pH Using Chemical Exchange Saturation Transfer (CEST) MRI.

The kidney plays a major role in maintaining body pH homeostasis. Renal pH, in particular, changes immediately following injuries such as intoxication and ischemia, making pH an early biomarker for kidney injury before the symptom onset and complementary to well-established laboratory tests. Because of this, it is imperative to develop minimally invasive renal pH imaging exams and test pH as a new diagnostic biomarker in animal models of kidney injury before clinical translation. Briefly, iodinated contrast agents approved by the US Food and Drug Administration (FDA) for computed tomography (CT) have demonstrated promise as novel chemical exchange saturation transfer (CEST) MRI agents for pH-sensitive imaging. The generalized ratiometric iopamidol CEST MRI analysis enables concentration-independent pH measurement, which simplifies in vivo renal pH mapping. This chapter describes quantitative CEST MRI analysis for preclinical renal pH mapping, and their application in rodents, including normal conditions and acute kidney injury.This publication is based upon work from the COST Action PARENCHIMA, a community-driven network funded by the European Cooperation in Science and Technology (COST) program of the European Union, which aims to improve the reproducibility and standardization of renal MRI biomarkers. This analysis protocol chapter is complemented by two separate chapters describing the basic concepts and experimental procedure.

Highly efficient magnetic labelling allows MRI tracking of the homing of stem cell-derived extracellular vesicles following systemic delivery.

Human stem‐cell‐derived extracellular vesicles (EVs) are currently being investigated for cell‐free therapy in regenerative medicine applications, but the lack of noninvasive imaging methods to track EV homing and uptake in injured tissues has limited the refinement and optimization of the approach. Here, we developed a new labelling strategy to prepare magnetic EVs (magneto‐EVs) allowing sensitive yet specific MRI tracking of systemically injected therapeutic EVs. This new labelling strategy relies on the use of ‘sticky’ magnetic particles, namely superparamagnetic iron oxide (SPIO) nanoparticles coated with polyhistidine tags, to efficiently separate magneto‐EVs from unencapsulated SPIO particles. Using this method, we prepared pluripotent stem cell (iPSC)‐derived magneto‐EVs and subsequently used MRI to track their homing in different animal models of kidney injury and myocardial ischemia. Our results showed that iPSC‐derived EVs preferentially accumulated in the injury sites and conferred substantial protection. Our study paves a new pathway for preparing highly purified magnetic EVs and tracking them using MRI towards optimized, systemically administered EV‐based cell‐free therapies.

Paricalcitol Attenuates Contrast-Induced Acute Kidney Injury by Regulating Mitophagy and Senescence

Contrast-induced acute kidney injury (CI-AKI) is the third most common cause of hospital-acquired renal failure, with an incidence of 11%. However, the disease mechanism remains unclear, and no effective treatment is available. Paricalcitol has been reported to be effective in animal models of kidney injury. We hypothesized that paricalcitol could play a renoprotective role against CI-AKI. Rats were divided into control, paricalcitol, contrast, and paricalcitol-plus-contrast groups. We used a previously published protocol to produce CI-AKI. Paricalcitol (0.3 μg/kg) was administered intraperitoneally before 24 h and 30 min before indomethacin. We used HK-2 cells to evaluate the effects of paricalcitol on mitophagy and senescence. Ioversol triggered renal dysfunction, increasing blood urea nitrogen and serum creatinine. Significant tubular damage, increased 8-OHdG expression, and apoptosis were apparent. Ioversol injection induced high expression levels of the mitophagy markers Pink1, Parkin, and LC3 and the senescence markers β-galactosidase and p16INK4A. Paricalcitol pretreatment prevented renal dysfunction and reduced tissue damage by reducing both mitophagy and senescence. Cellular morphological changes were found, and expression of LC3B and HMGB1 was increased by ioversol in HK-2 cells. Paricalcitol countered these effects. This study showed that mitochondria might drive injury phenotypes in CI-AKI, and that paricalcitol protects against CI-AKI by decreasing mitochondrial damage.

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.

Nicotine‐Induced Glomerular Injury is Ameliorated in NLRP3 Gene Knockout Mice

Nicotine, a major compound of tobacco and the key component of the vapor inhaled via electronic cigarettes, has been shown to worsen kidney injury in animal models of acute kidney injury, diabetes, subtotal nephrectomy. However, it remains unknown how nicotine‐induced glomerular injury. Hence, the present study tested whether NLRP3 inflammasome mediates the nicotine‐induced glomerular injury. Uninephrectomized Nlrp3 knockout (Nlrp3−/−) and wild type (Nlrp3+/+) mice were fed a normal chow for 5 weeks with or without nicotine treatment to produce glomerular injury. Nicotine treatment significantly increased the colocalization of Nlrp3 (Nod‐like receptor protein 3) with ASC (apoptosis‐associated speck‐like protein) or Caspase‐1 in glomeruli of Nlrp3+/+ mice than in vehicle treated mice. However, such nicotine‐induced increases in colocalization of Nlrp3 with ASC or Caspase‐1 was attenuated in Nlrp3−/− mice. In consistency with decreased inflammasome formation, the caspase‐1 activity and IL‐1β production was significantly attenuated in glomeruli of Nlrp3−/− mice. Morphological examinations showed that nicotine‐induced profound injury in glomeruli of Nlrp3+/+ mice which was markedly attenuated in Nlrp3−/− mice. The decreased glomerular damage index in Nlrp3−/− mice was accompanied by attenuated proteinuria. Immunofluorescence analysis showed that the nicotine treatment significantly decreased the expression of podocin but increased desmin levels in glomeruli from Nlrp3+/+ mice but not in those from Nlrp3−/− mice. Furthermore the nicotine‐induced hypertension was significantly attenuated in Nlrp3−/− mice. In conclusion, these observations disclose a pivotal role of Nlrp3 inflammasomes in mediating the glomerular sclerosis associated with smoking.Support or Funding InformationR01DK104031 and R56HL143809

Gentamicin Nephrotoxicity in Animal Model: Study of Kidney Histopathology and Physiological Functions

The purpose of this study was to analyze abnormal changes in kidney histology and physiology in acute kidney injury animal models with multiple doses of gentamicin. Induction of experimental animals was carried out on 20 rats (Rattus norvegicus) Wistar strain which were divided into 4 groups, group I was a negative control group, groups II, III and IV are gentamicin-induced groups at doses of 30 mg/kg, 40 mg/kg, and 50 mg/kg, respectively. Kidney histopathology were stained with Hematoxylin Eosin (HE), while analysis of serum BUN and creatinine by spectrophotometric method. Data analysis for kidney histopathology was descriptively while for BUN and Creatinine were statistically tested with one way ANOVA. The results of this study showed there was a kidney damage in all gentamicin-induced groups, which is necrosis in the contortus tubule and the Bowman’s capsule compared to the negative control group. The group of rats with the higher doses of gentamicin showed a more severe level of histopathological changes, however, BUN and creatinine levels were not significantly different (p> 0.05). This study concludes that gentamicin induction could cause kidney histopathological changes but not kidney physiology.

Cordyceps cicadae Mycelia Ameliorate Cisplatin-Induced Acute Kidney Injury by Suppressing the TLR4/NF-κB/MAPK and Activating the HO-1/Nrf2 and Sirt-1/AMPK Pathways in Mice.

Acute kidney injury (AKI) is a common clinical problem, characterized by a sudden loss of renal function, a high risk of death, and the eventual development of renal fibrosis and renal failure. Cordyceps cicadae is a traditional Chinese medicine with the potential function of kidney protection. We analyze two sputum extracts, a water extract (WCC), and an ethanol extract (ECC), to assess the potential of treating AKI in an animal model of kidney injury induced by cisplatin. A nephrotoxic mouse model was first established by intraperitoneal injection of cisplatin. Subsequently, WCC and ECC were orally administered in these mice. The results show that WCC and ECC significantly alleviated cisplatin-induced AKI renal histological changes, serum creatinine (CRE) and blood urea nitrogen (BUN) production, and the levels of NO, TNF-α, IL-1β, and IL-6. The levels of malondialdehyde (MDA) and glutathione (GSH) were suppressed by administration of WCC and ECC. However, WCC treatment prevented these changes significantly better than ECC treatment. In addition, Western blot data showed that WCC attenuated the cisplatin-induced protein expression of cyclooxygenase-2 (COX-2) and inducible NO synthase (iNOS), as well as inhibiting nuclear factor-kappa B (NF-κB) and mitogen-activated protein kinase (MAPK) activation in the kidney tissues. Furthermore, WCC greatly inhibited the expression of Toll-like receptor 4 (TLR4) and cisplatin-induced NF-κB activation, as well as dramatically increasing the production of antioxidative enzymes (i.e., superoxide dismutase (SOD), glutathione peroxidase (GPx), catalase, nuclear factor erythroid 2-related factor 2 (Nrf2), and heme oxygenase 1 (HO-1)), silent information regulator T1 (Sirt1), and p-AMP-activated protein kinase (AMPK) in the kidney tissues. In addition, we found that WCC increased the expression levels of the autophagy-related proteins LC3B and Beclin-1; proapoptotic proteins, including cleaved caspase-3 and cleaved poly (ADP-ribose) polymerase (PARP) 1; and organic anion transporters 1 (OAT1) and 3 (OAT3) in the kidney tissues. Finally, WCC, ECC, and two bioactive compounds—adenosine and N6-(2-hydroxyethyl) adenosine (HEA)—inhibited the production of nitrite oxide (NO) and intracellular reactive oxygen species (ROS) triggered by lipopolysaccharide- (LPS-) stimulated RAW264.7 macrophages in vitro. Collectively, WCC could provide a potential therapeutic candidate for the prevention of cisplatin-induced kidney injury through the inhibition of oxidative stress and inflammation.

Tacrolimus restores the high- and low-pressure baroreflex control of renal sympathetic nerve activity in cisplatin-induced renal injury rats.

What is the central question of this study? Does immunosuppression restore the baroreflex control of renal sympathetic nerve activity (RSNA) in an animal model of kidney injury? What is the main finding and its importance? Tacrolimus, a calcineurin inhibitor, restored the high- and low-pressure baroreflex control of RSNA following cisplatin-induced renal injury. Cisplatin administration causes depression of renal haemodynamic and excretory function and is associated with renal sympatho-excitation and loss of baroreflex regulation of renal sympathetic nerve activity (RSNA). This study investigated whether administration of the immunosuppressant tacrolimus in this cisplatin-mediated renal injury model could restore, or the acute intra-renal infusion of tumour necrosis factor α (TNF-α) could blunt, the high- or low-pressure baroreflex control of RSNA. Groups of control and cisplatin-treated (5mgkg-1 , i.p. on day 0) rats received either saline or tacrolimus (0.25mgkg-1 day-1 , i.p.) for 7days prior to study. Rats were anaesthetised and prepared for measurement of mean arterial pressure (MAP), heart rate (HR) and RSNA. Baroreflex gain curves were generated and the degree of renal sympatho-inhibition determined (area under the curve (AUC) reported as %RSNAmin) during acute volume expansion. Intrarenal TNF-α infusion (0.3µgkg-1 h-1 ) in control rats decreased baroreflex gain by 32% (P<0.05) compared to intra-renal saline infusion. In the cisplatin group (MAP: 98±14mmHg; HR: 391±24beatsmin-1 ), the baroreflex gain for RSNA was 39% (P<0.05) lower than that for the control group (MAP: 91±7mmHg; HR: 382±29beatsmin-1 ). In cisplatin-treated rats given daily tacrolimus (MAP: 84±12mmHg; HR: 357±30beatsmin-1 ), the baroreflex gain and renal sympatho-inhibition (AUC, 2440±1071vs. 635±498%min) were restored to normal values. These findings provide evidence for the view that cisplatin administration initiates an injury involving inflammation which may contribute to the deranged baroreflex regulation of RSNA. This phenomenon appears mediated in part via the renal innervation.

Lithium ameliorates tubule-interstitial injury through activation of the mTORC2/protein kinase B pathway.

Tubule-interstitial injury (TII) is a critical step in the progression of renal disease. It has been proposed that changes in proximal tubule (PT) albumin endocytosis plays an important role in the development of TII. Some reports have shown protective effects of lithium on kidney injury animal models that was correlated to proteinuria. We tested the hypothesis that lithium treatment ameliorates the development of TII due to changes in albumin endocytosis. Two experimental models were used: (1) TII induced by albumin overload in an animal model; (2) LLC-PK1 cells, a PT cell line. Lithium treatment ameliorates TII induced by albumin overload measured by (1) proteinuria; (2) collagen deposition; (3) area of tubule-interstitial space, and (4) macrophage infiltration. Lithium treatment increased mTORC2 activity leading to the phosphorylation of protein kinase B (PKB) at Ser473 and its activation. This mechanism enhanced albumin endocytosis in PT cells, which decreased the proteinuria observed in TII induced by albumin overload. This effect did not involve changes in the expression of megalin, a PT albumin receptor. In addition, activation of this pathway decreased apoptosis in LLC-PK1 cells, a PT cell line, induced by higher albumin concentration, similar to that found in pathophysiologic conditions. Our results indicate that the protective role of lithium treatment on TII induced by albumin overload involves an increase in PT albumin endocytosis due to activation of the mTORC2/PKB pathway. These results open new possibilities in understanding the effects of lithium on the progression of renal disease.