Renoprotective Effects of Valproic Acid and Dexamethasone in Acute Kidney Ischemia-Reperfusion Injury
ABSTRACT: Introduction: Renal ischemia-reperfusion (IR) causes acute kidney injury (AKI) with high mortality and morbidity. The objective of this study was to ameliorate kidney IR injury and identify novel biomarkers for kidney injury and repair. Methods: Left renal ischemia was induced in rats by clamping renal artery for 45 minutes, followed by reperfusion and right nephrectomy. Thirty minutes prior to ischemia, rats (n=8/group) received Valproic Acid (150 mg/kg; VPA), Dexamethasone (3 mg/kg; Dex) or Vehicle (Saline) intraperitoneally. Animals were sacrificed at 3h, 24h or 120h post- IR and blood, urine and kidney were collected. Results: Serum creatinine (mg/dL) at 24 h IR in VPA (2.7±1.8) and Dex (2.3±1.2) was reduced (P<0.05) compared to Vehicle (3.8±0.5). At 3h post-IR, urine albumin (mg/ml) was higher in Vehicle (1.47±0.10), VPA (0.84±0.62) and Dex (1.04±0.73) compared to uninjured/untreated control (0.14±0.26) group. At 24h post-IR urine Lipocalin-2 (µg/ml) was significantly higher (P<0.05) in VPA, Dex and Vehicle groups (9.61-11.36) compared to uninjured/untreated control (0.67±o.29); also, Kidney Injury Molecule-1 (KIM-1; ng/ml) was significantly higher in VPA, Dex and Vehicle groups (13.7-18.7) compared uninjured/untreated control (1.7±1.9). KIM-1 levels were significantly (P<0.05) higher in all groups compared to uninjured/untreated control levels. Histopathology at 3h post IR demonstrated (P<0.05) reduction in ischemic injury in the renal cortex in VPA (Grade 1.6± 1.5) compared to Vehicle (Grade 2.9±1.1) group. Inflammatory cytokines IL1β and IL6 were down-regulated in VPA and Dex groups. BCL2 was higher in VPA group. DNA microarray analysis demonstrated reduced stress response and injury, and improved recovery related gene expression in the kidneys of VPA treated animals. Conclusions: VPA administration reduced kidney IR injury and improved regeneration. KIM-1 and Lipocalin-2 appear to be promising early urine biomarkers of acute ischemic kidney injury. We had three experimental groups. Group A, VPA treatment; Group B, Dexamethasone treatment; and Group C, No treatment (vehicle saline control). Treatments were administered prior to the induction of left renal ischemia. Animals underwent 45 minutes of left renal ischemia, followed by reperfusion, and right nephrectomy as described above. Following reperfusion, animals were sacrificed at 3, 24 or 120 hours (n=8/group). In the 3 hour group, rats were maintained under anesthesia after surgery until sacrifice. In the 24 and 120 hour groups, the rats were recovered and returned to the cages for normal housing. Analgesic buprenorphine (0.05mg/kg) was administered every 12 h for three days post-operatively. After animal sacrifice, urine, blood, and kidney were collected for kidney functional biomarker assays, histology and / or molecular analyses. Urine was obtained via cystocentesis and blood was obtained via the left renal vein. Tissue and urine samples collected from normal (naïve) animals (n=5) were used for baseline measurements. A subset of 46 animals (n = 4-5 per group) were selected for microarray analysis.
Project description:Transcriptome analysis was done after warm renal ischemia-reperfusion injury (IRI) in a rat model. Earlier studies have shown a protective effect of prior unilateral nephrectomy (UNx) against IRI in the remaining, contralateral kidney compared to a non-neprectomized control group. We aimed at identifying the underlying molecular mechanisms. We used the Affymetrix Clariom D array (formerly known as RTA 1.0 st.) Array data was processed in the Affymetrix Console Software. Overall design: We analysed kidney tissue (left) from male Wistar rats. Number of animals from each group, n = 3. Wistar rats were randomized to either UNx or sham UNx immediately prior to 37 minutes of unilateral renal artery clamping or sham operation under sevoflurane anesthesia. Groups: sham (2 normal kidneys), UNx (1 remaining kidney), IR (1 ischemic kidney, 1 normal kidney), IR+UNx (1 ischemic kidney). MRI was performed 24 hours after reperfusion. Blood and renal tissue were harvested. RNA was isolated for microarray analysis.
Project description:characterization of fibrinogen expression in the kidney, excretion in the urine following kidney damage and evaluating the therapeutic potential of fibrinogen in acute kidney injury. Overall design: Total RNA was isolated of renal cortex and medulla from rats subjected to 20 min of bilateral ischemia followed by 6, 24 120, hr of reperfusion compared to sham rats.
Project description:characterization of fibrinogen expression in the kidney, excretion in the urine following kidney damage and evaluating the therapeutic potential of fibrinogen in acute kidney injury. Total RNA was isolated of renal cortex and medulla from rats subjected to 20 min of bilateral ischemia followed by 6, 24 120, hr of reperfusion compared to sham rats.
Project description:Ten-Elven Translocation (TET) proteins oxidize 5-methylcytosine (5mC) to 5-hydroxymethylcytonsie (5hmC). Our recent work found a decline in global 5hmC level in mouse kidney insulted by ischemia reperfusion (IR). However, the genomic distribution of 5hmC in mouse kidney and its relationship with gene expression remain elusive. Here, we profiled the DNA hydroxymethylome of mouse kidney by hMeDIP-seq and revealed that 5hmC is enriched in genic regions but depleted from intergenic regions. Correlation analyses showed that 5hmC enrichment in gene body is positively associated with gene expression level in mouse kidney. Moreover, IR injury-associated genes (both up- and down-regulated genes during renal IR injury) in mouse kidney exhibit significantly higher 5hmC enrichment in their gene body regions when compared to those un-changed genes. Collectively, our study not only provides the first DNA hydroxmethylome of kidney tissues but also suggests that DNA hyper-hydroxymethylation in gene body may be a novel epigenetic mark of IR injury-associated genes. Eamination of the genome-wide distribution of 5-hydroxymethylcytosine in mouse kidney tissues
Project description:Renal recovery following injury relies on cellular regeneration. In the mouse kidney following injury, injured epithelial cells undergoes de-differentiate, proliferate and re-differentiate into functional cells, following a a tightly controlled genetic programme where specific sets of genes are up-regulated. We used microarrays to detail the global programme of gene expression underlying cellular regeneration following injury with or without a HDAC inhibitor, m4PTB, treatment and identified distinct classes of up-regulated genes during this process. Male BALB/c mice underwent 26 minute unilateral ischemia-reperfusion (IR) with contralateral nephrectomy treated with vehicle or 100 mg/kg m4PTB 24 h after inducing renal injury, and kidneys harvested for RNA extraction 12 h later. We sought to obtain kidneys within a similar degree of injury in order to carefully evaluate the effect of m4PTB on expression profiles. To that end, we selected kidneys according to three different criteria of injury: (1) level of serum creatinine at Day1, (2) the level of blood urea nitrogen (BUN) (3) Kim1 expression by qPCR at Day1.5 using haevested kidneys
Project description:Fibroblasts are present in every organ. While the role fibroblasts in chronic diseases such as fibrosis or tumor expression has been extensively explored, little is known about their physiological role. The kidney possesses a unique capacity to recover from even severe acute injury. We study molecular mechanisms of this intrinsic repair capacity in the mouse model of ischemia-reperfusion (IR). In this model, the renal artery and vein are clamped for 45 min, leading to acute kidney injury. The kidney spontaneously recovers from such IR injury within 14 days. IR kidney injury is associated with a transient accumulation of fibroblasts in the diseased tissue. We hypothesized that fibroblasts aid the repair of acute IR injury in the kidney. To elucidate how FSP1+ fibroblasts may contribute to the repair of kidney injury, we undertook a global unbiased approach to compare gene expression profiles of fibroblasts isolated from kidneys post-IRI and from control kidneys by FACS sorting. To investigate the role fibroblasts may play in the repair of kidney inhury, we performed ischemia reperfusion injury surgery on transgenic mice in which the FSP-1 promoter drives EGFP expression. Kidney injury peaks at day 3 post-IRI, followed by spontaneous regeration that restores nearly perfect kidney architecture and health by day 10. Fibroblasts are thought to possibly play a role in this process, as they are normally rare in the healthy kidney, acute kidney injury is associated with a transient accumulation of interstitial fibroblasts, but whether they may help repair the acute kidney injury or in fact could contribute to the damage is not known. To compare the gene expression profiles of normal fibroblasts and those from post-ischemic kidneys, we sacrificed control FSP1-GFP mice and the FSP1-GFP mice three days post-IRI. We generated single-cell suspensions from both the post-IRI and control kidneys, and then isolated FSP1-GFP+ cells by FACS sorting that, when cultured on plastic, displayed typical fibroblast morphology. Total RNA was immediately extracted from the sorted cells and amplified to produce enough for a array. We biotinylated five of the samples from post-ischemic kidneys and three of the control (non-ischemic) kidneys and used Affymetrix 3' Arrays to examine differences in gene expression profiles between the two groups that may she some light on what role, if any, fibroblasts play in the spontaneous healing of the kidney after acute kidney injury. We performed ischemia reperfusion surgery in FSP1-GFP mice, and at day 3, we sacrificed the mice, isolated FSP1-GFP positive cells from both IR and normal control kidneys by FACS sorting, extracted total RNA from the isolated FSP1-GFP cells and used Affymetrix Mouse Expression Array 430 2.0 microarrays to perform gene expression profiling of the samples. All told, we performed the FACS Sorting, RNA extration, and hybridization with 5 ischemic kidneys and 3 normal kidneys. Fibroblasts, acute kidney injury, repair, comparative gene expression profiling, microarrays, FACS sorting, role in healing
Project description:Macrophages are a heterogeneous cell type implicated in injury, repair, and fibrosis after AKI, but the macrophage population associated with each phase is unclear.results of this study in a renal ischemia-reperfusion injury model allow phenotype and function to be assigned to CD11b+/Ly6C+ monocyte/macrophage populations in the pathophysiology of disease after AKI. we used a renal bilateral ischemia-reperfusion injury mouse model to identify unique monocyte/macrophage populations by differential expression of Ly6C in CD11b+ cells and to define the function of these cells in the pathophysiology of disease on the basis of microarray gene signatures and reduction strategies Macrophage populations were sorted by Flow Cytometry into low and intermediate populations by Itgam(Cd11b) and Ly6c markers. The cells obtained in 5 weeks sham, 5 weeks IR, 9 day sham, and 9 day IR with 6 samples per group (3 int and 3 low). Cells were sorted in 350ul of RLT lysing buffer and kept at -80c until RNA extraction.Sample amplification, fragmentation, hybridization,washing and scanning were performed according to validated Affymetrix protocol in a CLIA certified lab.
Project description:The early events that signal renal dysfunction in presymptomatic heart failure are unclear. To evaluate this, we performed RNA-seq on kidneys from transgenic mice with cardiac-specific overexpression of mutant alpha-B-crystallin, which develop slowly progressive cardiomyopathy. Presymptomatic transgenic mice display an increase in serum creatinine and in urinary neutrophil gelatinase-associated lipocalin (NGAL), but lack chronic interstitial fibrosis. Presymptomatic transgenic mouse kidneys exhibited a worsened response to ischemia-reperfusion injury based on serum creatinine, urine NGAL, tubule dilation and cast score, and apoptosis. Our findings demonstrate functional renal impairment, urinary biomarker elevations, and gene expression changes that occur in early presymptomatic heart failure, which dramatically increase the susceptibility to subsequent acute kidney injury. Overall design: mRNA profiles were generated by performing RNA-seq on adult kidney tissue from transgenic mice (FVB/N mice that overexpress CryAB containing the R120G missense mutation driven by the cardiomyocyte-specific α-myosin heavy chain promoter. We performed analysis in triplicate of kidneys from transgenic animals (prior to the onset of heart failure) vs. age-matched, sex-matched (male) control mice by deep sequencing using Illumina Hi-Seq 2500.
Project description:The mechanistic target of rapamycin mTORC1 is a key regulator of cell metabolism and autophagy. Despite widespread clinical use of mTOR inhibitors, the role of mTORC1 in renal tubular function and kidney homeostasis remains elusive. By utilizing constitutive and inducible deletion of conditional Raptor alleles in renal tubular epithelial cells, we discovered that mTORC1 deficiency caused a marked concentrating defect, loss of tubular cells and slowly progressive renal fibrosis. Transcriptional profiling revealed that mTORC1 maintains renal tubular homeostasis by controlling mitochondrial metabolism and biogenesis as well as transcellular transport processes involved in counter-current multiplication and urine concentration. Although mTORC2 partially compensated the loss of mTORC1, exposure to ischemia and reperfusion injury exaggerated the tubular damage in mTORC1-deficient mice, and caused pronounced apoptosis, diminished proliferation rates and delayed recovery. These findings identify mTORC1 as an essential regulator of tubular energy metabolism and as a crucial component of ischemic stress responses. Pharmacological inhibition of mTORC1 likely affects tubular homeostasis, and may be particularly deleterious if the kidney is exposed to acute injury. Furthermore, the combined inhibition of mTORC1 and mTORC2 may increase the susceptibility to renal damage. Raptor fl/fl*KspCre and Raptor fl/fl animals were sacrificed at P14 before the development of an overt functional phenotype. Kidneys were split in half and immediately snap frozen in liquid nitrogen.
Project description:NF-κB is a key regulator of innate and adaptive immunity and is implicated in the pathogenesis of acute kidney injury (AKI). The cell type-specific functions of NF-κB in the kidney are unknown; however, the pathway serves distinct functions in immune and tissue-parenchymal cells. We analyzed tubular epithelial-specific NF-κB signaling in a mouse model of ischemia-reperfusion injury (IRI)-induced AKI. NF-κB reporter activity and nuclear localization of phosphorylated NF-κB subunit p65 analyses in mice revealed widespread NF-κB activation in renal tubular epithelia and in interstitial cells following IRI that peaked at 2-3 days after injury. To genetically antagonize tubular epithelial NF-κB activity, we generated mice expressing the human NF-κB super-repressor IκBα∆N in renal proximal, distal, and collecting duct epithelial cells. These mice were protected from IRI-induced AKI, as indicated by improved renal function, reduced tubular apoptosis, and attenuated neutrophil and macrophage infiltration. Tubular NF-κB-dependent gene expression profiles revealed temporally distinct functional gene clusters for apoptosis, chemotaxis, and morphogenesis. Primary proximal tubular cells isolated from IκBα∆N-expressing mice exposed to hypoxia-mimetic agent cobalt chloride were protected from apoptosis and expressed reduced levels of chemokines. Our results indicate that postischemic NF-κB activation in renal-tubular epithelia aggravates tubular injury and exacerbates a maladaptive inflammatory response. Overall design: Expression profiling was performed by Illumina Mouse WG6 v2.0 Expression Bead Chip microarray analysis. Differentially expressed genes of ischemic wild-type vs. Emx1-ΔN kidneys were analyzed at 24 hours following ischemia reperfusion injury, compare to Sham control kidneys. 6 biological replicates were used per group.