Rotenone ameliorates chronic renal injury caused by acute ischemia/reperfusion

Mitochondrial quality control in acute kidney disease

Acute kidney disease (AKD) involves multiple pathogenic mechanisms,  including maladaptive repair of renal cells that are rich in mitochondria. Maintenance of mitochondrial homeostasis and quality control is crucial for normal kidney function. Mitochondrial quality control serves to maintain mitochondrial function under various conditions, including mitochondrial bioenergetics, mitochondrial biogenesis, mitochondrial dynamics (fusion and fission) and mitophagy. To date, increasing evidence indicates that mitochondrial quality control is disrupted when acute kidney disease develops. This review describes the mechanisms of mitochondria quality control in acute kidney disease, aiming to provide clues to help design new clinical treatments.

Mitochondrial dysfunction and oxidative stress: Role in chronic kidney disease

Chronic kidney disease (CKD) is associated with a variety of distinct disease processes that permanently change the function and structure of the kidney across months or years. CKD is characterized as a glomerular filtration defect or proteinuria that lasts longer than three months. In most instances, CKD leads to end-stage kidney disease (ESKD), necessitating kidney transplantation. Mitochondrial dysfunction is a typical response to damage in CKD patients. Despite the abundance of mitochondria in the kidneys, variations in mitochondrial morphological and functional characteristics have been associated with kidney inflammatory responses and injury during CKD. Despite these variations, CKD is frequently used to define some classic signs of mitochondrial dysfunction, including altered mitochondrial shape and remodeling, increased mitochondrial oxidative stress, and a marked decline in mitochondrial biogenesis and ATP generation. With a focus on the most significant developments and novel understandings of the involvement of mitochondrial remodeling in the course of CKD, this article offers a summary of the most recent advances in the sources of procured mitochondrial dysfunction in the advancement of CKD. Understanding mitochondrial biology and function is crucial for developing viable treatment options for CKD.

Fate and PPARγ and STATs-driven effects of the mitochondrial complex I inhibitor tebufenpyrad in liver cells revealed with multi-omics

The biological effects of the pesticide and mitochondrial complex I inhibitor tebufenpyrad (TEBU) on liver cells were investigated by combining proteomics and metabolomics. Both cell culture media and cellular lysates were analyzed in dose-response and kinetic experiments on the HepaRG cell line. Responses were compared with those obtained on primary human and rat hepatocytes. A multitude of phase I and II metabolites (>80) mainly common to HepaRG cells and primary hepatocytes and an increase in metabolization enzymes were observed. Synthesis of mitochondrion and oxidative phosphorylation complex constituents, fatty acid oxidation, and cellular uptake of lipids were induced to compensate for complex I inhibition and the decrease in ATP intracellular contents caused by TEBU. Secretion of the 20 S circulating proteasome and overall inhibition of acute inflammation followed by IL-6 secretion in later stages were observed in HepaRG cells. These effects were associated with a decrease in STAT1 and STAT3 transcription factor abundances, but with different kinetics. Based on identified TEBU targets, docking experiments, and nuclear receptor reporter assays, we concluded that liver cell response to TEBU is mediated by its interaction with the PPARγ transcription factor.

Glomerular proteomic profiling of kidney biopsies with hypertensive nephropathy reveals a signature of disease progression

Hypertensive nephropathy (HN) requires a kidney biopsy as diagnostic gold-standard but histological findings are unspecific and specific prognostic markers are missing. We aimed at identifying candidate prognostic markers based on glomerular protein signatures. We studied adult patients (n = 17) with eGFR >30 ml/min/1.73m² and proteinuria <3 g/d from the Norwegian Kidney Biopsy Registry, including subjects non progressing (NP, n = 9), or progressing (P, n = 8) to end-stage renal disease (ESRD) within an average follow-up of 22 years. Glomerular cross-sections from archival kidney biopsy sections were microdissected and processed for protein extraction. Proteomic analyses were performed using Q-exactive HF mass spectrometer and relative glomerular protein abundances were compared between P and NP patients. Immunohistochemistry (IHC) was used to validate selected data. Amongst 1870 quality filtered proteins, 58 were differentially expressed in P and NP patients' glomeruli, with absolute fold changes (FC) ≥1.5, p ≤ 0.05. Supervised classifier analysis (K nearest neighbor) identified a set of five proteins, including Gamma-butyrobetaine dioxygenase (BBOX1, O75936) and Cadherin 16 (CDH16, O75309), overexpressed in P, and Eosinophil peroxidase (EPX, P11678), DnaJ homolog subfamily B member 1 (DNAJB1, P25685) and Alpha-1-syntrophin (SNTA1, Q13424), overexpressed in NP glomeruli, correctly classifying 16/17 kidney biopsy samples. Geneset Enrichment Analysis (GSEA), showed that metabolic pathways were generally enriched in P, and structural cell pathways in NP. Pathway analysis identified Epithelial Adherens Junction Signaling as most affected canonical pathway. IHC analysis confirmed overexpression of BBOX1 and Cadherin 16 in glomeruli from P patients. In conclusion, glomerular proteomic profiling can be used to discriminate P from NP HN patients.

Integrated proteomic and metabolomic profile analyses of cardiac valves revealed molecular mechanisms and targets in calcific aortic valve disease

Background

This study aimed to define changes in the metabolic and protein profiles of patients with calcific aortic valve disease (CAVD).

Methods and results

We analyzed cardiac valve samples of patients with and without (control) CAVD (n = 24 per group) using untargeted metabolomics and tandem mass tag-based quantitative proteomics. Significantly different metabolites and proteins between the CAVD and control groups were screened; then, functional enrichment was analyzed. We analyzed co-expressed differential metabolites and proteins, and constructed a metabolite-protein-pathway network. The expression of key proteins was validated using western blotting. Differential analysis identified 229 metabolites in CAVD among which, 2-aminophenol, hydroxykynurenine, erythritol, carnosine, and choline were the top five. Proteomic analysis identified 549 differentially expressed proteins in CAVD, most of which were localized in the nuclear, cytoplasmic, extracellular, and plasma membranes. Levels of selenium binding protein 1 (SELENBP1) positively correlated with multiple metabolites. Adenosine triphosphate-binding cassette transporters, starch and sucrose metabolism, hypoxia-inducible factor 1 (HIF-1) signaling, and purine metabolism were key pathways in the network. Ectonucleotide pyrophosphatase/phosphodiesterase 1 (ENPP1), calcium²⁺/calmodulin-dependent protein kinase II delta (CAMK2D), and ATP binding cassette subfamily a member 8 (ABCA8) were identified as hub proteins in the metabolite-protein-pathway network as they interacted with ADP, glucose 6-phosphate, choline, and other proteins. Western blotting confirmed that ENPP1 was upregulated, whereas ABCA8 and CAMK2D were downregulated in CAVD samples.

Conclusion

The metabolic and protein profiles of cardiac valves from patients with CAVD significantly changed. The present findings provide a holistic view of the molecular mechanisms underlying CAVD that may lead to the development of novel diagnostic biomarkers and therapeutic targets to treat CAVD.

Identifying of miRNA–mRNA Regulatory Networks Associated with Acute Kidney Injury by Weighted Gene Co-Expression Network Analysis

Background

Acute kidney injury (AKI) is a clinical emergency characterized by a dramatic decline in renal function and the accumulation of metabolic waste products in the body, with a high morbidity and mortality rate. The pathogenesis of AKI remains unclear and there are no effective treatment options.

Methods

We aimed to identify critical genes involved in the pathogenesis of AKI and construct a miRNA–mRNA regulatory network using gene expression data downloaded from Gene Expression Omnibus (GSE85957) for 38 kidneys of AKI and 19 control rats and cisplatin treated kidneys of 3 AKI and 3 control rats. Data in GSE85957 were processed using weighted gene co-expression network analysis (WGCNA), and biological function analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis were used to analyze the functions associated with critical genes.

Results

Twenty-eight modules in the GSE85957 dataset were identified by WGCNA, of which 103 genes in the orange module and 30 genes in the black module were closely associated with AKI and dose. Biological function analysis of genes in the orange and black modules revealed that skeletal muscle cell differentiation, tissue development and organ development were involved in the pathological changes of AKI. Combining with our experimentally processed AKI rat kidney data, eight genes (Atf3, Egr1, Egr2, Fos, Fosb, Gdf15, Serpine1 and Nr1d1) were identified as potential biomarkers of AKI, and miRNA–mRNA regulatory networks were constructed based on the above eight critical genes. Further tissue validation revealed that Egr1 and Fos were highly expressed in AKI.

Conclusion

Our study identified potential biomarkers of AKI and constructed an associated miRNA–mRNA regulatory network, which may provide new insights into the molecular pathogenesis of AKI.

Hypoxia Induces Renal Epithelial Injury and Activates Fibrotic Signaling Through Up-Regulation of Arginase-II

The ureohydrolase, type-II arginase (Arg-II), is a mitochondrial enzyme metabolizing L-arginine into urea and L-ornithine and is highly expressed in renal proximal tubular cells (PTC) and upregulated by renal ischemia. Recent studies reported contradictory results on the role of Arg-II in renal injury. The aim of our study is to investigate the function of Arg-II in renal epithelial cell damage under hypoxic conditions. Human renal epithelial cell line HK2 was cultured under hypoxic conditions for 12–48 h. Moreover, ex vivo experiments with isolated kidneys from wild-type (WT) and genetic Arg-II deficient mice (Arg-II^–/–) were conducted under normoxic and hypoxic conditions. The results show that hypoxia upregulates Arg-II expression in HK2 cells, which is inhibited by silencing both hypoxia-inducible factors (HIFs) HIF1α and HIF2α. Treatment of the cells with dimethyloxaloylglycine (DMOG) to stabilize HIFα also enhances Arg-II. Interestingly, hypoxia or DMOG upregulates transforming growth factor β1 (TGFβ1) levels and collagens Iα1, which is prevented by Arg-II silencing, while TGFβ1-induced collagen Iα1 expression is not affected by Arg-II silencing. Inhibition of mitochondrial complex-I by rotenone abolishes hypoxia-induced reactive oxygen species (mtROS) and TGFβ1 elevation in the cells. Ex vivo experiments show elevated Arg-II and TGFβ1 expression and the injury marker NGAL in the WT mouse kidneys under hypoxic conditions, which is prevented in the Arg-II^–/– mice. Taking together, the results demonstrate that hypoxia activates renal epithelial HIFs-Arg-II-mtROS-TGFβ1-cascade, participating in hypoxia-associated renal injury and fibrosis.

Sirtuin 5 depletion impairs mitochondrial function in human proximal tubular epithelial cells

Ischemia is a major cause of kidney damage. Proximal tubular epithelial cells (PTECs) are highly susceptible to ischemic insults that frequently cause acute kidney injury (AKI), a potentially life-threatening condition with high mortality. Accumulating evidence has identified altered mitochondrial function as a central pathologic feature of AKI. The mitochondrial NAD⁺-dependent enzyme sirtuin 5 (SIRT5) is a key regulator of mitochondrial form and function, but its role in ischemic renal injury (IRI) is unknown. SIRT5 expression was increased in murine PTECs after IRI in vivo and in human PTECs (hPTECs) exposed to an oxygen/nutrient deprivation (OND) model of IRI in vitro. SIRT5-depletion impaired ATP production, reduced mitochondrial membrane potential, and provoked mitochondrial fragmentation in hPTECs. Moreover, SIRT5 RNAi exacerbated OND-induced mitochondrial bioenergetic dysfunction and swelling, and increased degradation by mitophagy. These findings suggest SIRT5 is required for normal mitochondrial function in hPTECs and indicate a potentially important role for the enzyme in the regulation of mitochondrial biology in ischemia.

Analysis of blood parameters and molecular endometrial markers during early reperfusion in two ovine models of uterus transplantation

The dissection of the veins is the trickiest step of Uterine transplantation (UTx). Performing the anastomosis of a single uterine vein could bring a therapeutic benefit and simplification of surgery and serve for managing unilateral venous thromboses. The objectives of this project were to evaluate the expression of early markers of ischemia-reperfusion and to compare findings following one or two vein anastomoses. Orthotopic uterine auto-transplantations were performed on an ovine model with anastomosis of either two (group 1) or one utero-ovarian veins (group 2). Blood gases, histology and ischemia- reperfusion markers transcripts (PTGS2, IL6, IL8, SOD2, C3, BAX/BCL2 and TLR4) were analyzed as well as PTGS2 protein expression using Western Blot and fluorescence immunolocalization on endometrial biopsies after 3h of reperfusion. Ten ewes were included in the experimentation, 4 were in group1, 3 in group 2, the others being sham operated controls. No significant differences were observed between the two phenotypes. Based on these results, the anastomosis of one single uterine vein appears to be an approach consistent with short-term graft survival. Further experiments will be needed to confirm the reliability of this approach, especially the long-term follow-up of the uterine graft including its ability to support gestation to term.

DJ-1: A promising therapeutic candidate for ischemia-reperfusion injury

DJ-1 is a multifaceted protein with pleiotropic functions that has been implicated in multiple diseases, ranging from neurodegeneration to cancer and ischemia-reperfusion injury. Ischemia is a complex pathological state arising when tissues and organs do not receive adequate levels of oxygen and nutrients. When the blood flow is restored, significant damage occurs over and above that of ischemia alone and is termed ischemia-reperfusion injury. Despite great efforts in the scientific community to ameliorate this pathology, its complex nature has rendered it challenging to obtain satisfactory treatments that translate to the clinic. In this review, we will describe the recent findings on the participation of the protein DJ-1 in the pathophysiology of ischemia-reperfusion injury, firstly introducing the features and functions of DJ-1 and, successively highlighting the therapeutic potential of the protein.

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DJ-1 has been shown to confer protection in ischemia-reperfusion injury models.

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DJ-1 protection relies on the activation of antioxidant signaling pathways.

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DJ-1 regulates mitochondrial homeostasis during ischemia and reperfusion.

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DJ-1 seems to modulate ion homeostasis during ischemia and reperfusion.

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DJ-1 may represent a promising therapeutic target for ischemia-reperfusion injury.

Mitochondrial dysfunction and the AKI-to-CKD transition

Acute kidney injury (AKI) has been widely recognized as an important risk factor for the occurrence and development of chronic kidney disease (CKD). Even milder AKI has adverse consequences and could progress to renal fibrosis, which is the ultimate common pathway for various terminal kidney diseases. Thus, it is urgent to develop a strategy to hinder the transition from AKI to CKD. Some mechanisms of the AKI-to-CKD transition have been revealed, such as nephron loss, cell cycle arrest, persistent inflammation, endothelial injury with vascular rarefaction, and epigenetic changes. Previous studies have elucidated the pivotal role of mitochondria in acute injuries and demonstrated that the fitness of this organelle is a major determinant in both the pathogenesis and recovery of organ function. Recent research has suggested that damage to mitochondrial function in early AKI is a crucial factor leading to tubular injury and persistent renal insufficiency. Dysregulation of mitochondrial homeostasis, alterations in bioenergetics, and organelle stress cross talk contribute to the AKI-to-CKD transition. In this review, we focus on the pathophysiology of mitochondria in renal recovery after AKI and progression to CKD, confirming that targeting mitochondria represents a potentially effective therapeutic strategy for the progression of AKI to CKD.

Rotenone protects against β-cell apoptosis and attenuates type 1 diabetes mellitus

Type 1 diabetes mellitus (T1DM) is caused by pancreatic β-cell dysfunction and apoptosis, with consequent severe insulin deficiency. Thus, β-cell protection may be a primary target in the treatment of T1DM. Evidence has demonstrated that defective mitochondrial function plays an important role in pancreatic β-cell dysfunction and apoptosis; however, the fundamental effect of mitochondrial complex I action on β-cells and T1DM remains unclear. In the current study, the pancreas protective effect of complex I inhibitor rotenone (ROT) and its potential mechanism were assessed in a streptozotocin (STZ)-induced mouse model of T1DM and in cultured mouse pancreatic β-cell line, Min6. ROT treatment exerted a hypoglycemic effect, restored the insulin level, and decreased inflammation and cell apoptosis in the pancreas. In vitro experiments also showed that ROT decreased STZ- and inflammatory cytokines-induced β-cell apoptosis. These protective effects were accompanied by attenuation of reactive oxygen species, increased mitochondrial membrane potential, and upregulation of transcriptional coactivator PPARα coactivator 1α (PGC-1α)-controlled mitochondrial biogenesis. These findings suggest that mitochondrial complex I inhibition may represent a promising strategy for β-cell protection in T1DM.

Manganese Superoxide Dismutase Dysfunction and the Pathogenesis of Kidney Disease

The mitochondria are a major source of reactive oxygen species (ROS). Superoxide anion (O₂^•–) is produced by the process of oxidative phosphorylation associated with glucose, amino acid, and fatty acid metabolism, resulting in the production of adenosine triphosphate (ATP) in the mitochondria. Excess production of reactive oxidants in the mitochondria, including O₂^•–, and its by-product, peroxynitrite (ONOO^–), which is generated by a reaction between O₂^•– with nitric oxide (NO^•), alters cellular function via oxidative modification of proteins, lipids, and nucleic acids. Mitochondria maintain an antioxidant enzyme system that eliminates excess ROS; manganese superoxide dismutase (Mn-SOD) is one of the major components of this system, as it catalyzes the first step involved in scavenging ROS. Reduced expression and/or the activity of Mn-SOD results in diminished mitochondrial antioxidant capacity; this can impair the overall health of the cell by altering mitochondrial function and may lead to the development and progression of kidney disease. Targeted therapeutic agents may protect mitochondrial proteins, including Mn-SOD against oxidative stress-induced dysfunction, and this may consequently lead to the protection of renal function. Here, we describe the biological function and regulation of Mn-SOD and review the significance of mitochondrial oxidative stress concerning the pathogenesis of kidney diseases, including chronic kidney disease (CKD) and acute kidney injury (AKI), with a focus on Mn-SOD dysfunction.

Ischemia/Reperfusion Injury Revisited: An Overview of the Latest Pharmacological Strategies

Ischemia/reperfusion injury (IRI) permeates a variety of diseases and is a ubiquitous concern in every transplantation proceeding, from whole organs to modest grafts. Given its significance, efforts to evade the damaging effects of both ischemia and reperfusion are abundant in the literature and they consist of several strategies, such as applying pre-ischemic conditioning protocols, improving protection from preservation solutions, thus providing extended cold ischemia time and so on. In this review, we describe many of the latest pharmacological approaches that have been proven effective against IRI, while also revisiting well-established concepts and presenting recent pathophysiological findings in this ever-expanding field. A plethora of promising protocols has emerged in the last few years. They have been showing exciting results regarding protection against IRI by employing drugs that engage several strategies, such as modulating cell-surviving pathways, evading oxidative damage, physically protecting cell membrane integrity, and enhancing cell energetics.

Inhibition of Mitochondrial Complex I Aggravates Folic Acid-Induced Acute Kidney Injury

Background: Some researches revealed that mitochondrial dysfunction is associated with various kidney injury. However, the role of mitochondrial dysfunction in the pathogenesis of acute kidney injury (AKI) still needs evidence. Methods: We evaluated the effect of mitochondrial complex I inhibitor rotenone on folic acid (FA)-induced AKI in mice. Results: Strikingly, the mice pretreated with rotenone at a dose of 200 ppm in food showed exacerbated kidney injury as shown by higher levels of blood urea nitrogen and creatinine compared with FA alone group. Meanwhile, both renal tubular injury score and the expression of renal tubular injury marker neutrophil gelatinase-associated lipocalin were further elevated in rotenone-pretreated mice, suggesting the deteriorated renal tubular injury. Moreover, the decrements of mitochondrial DNA copy number and the expressions of mitochondrial Cytochrome c oxidase subunit 1, mitochondrial NADH dehydrogenase subunit 1, and mitochondria-specific superoxide dismutase (SOD2) in the kidneys of FA-treated mice were further reduced in rotenone-pretreated mice, indicating the aggravated mitochondrial damage. In parallel with the SOD2 reduction, the oxidative stress markers of malondialdehyde and HO-1 displayed greater increment in AKI mice with rotenone pretreatment in line with the deteriorated apoptotic response and inflammation. Conclusion: Our results suggested that the inhibition of mitochondrial complex I activity aggravated renal tubular injury, mitochondrial damage, oxidative stress, cell apoptosis, and inflammation in FA-induced AKI.

Mitochondrial activity contributes to impaired renal metabolic homeostasis and renal pathology in STZ-induced diabetic mice

Diabetic nephropathy (DN) has become the main cause of end-stage renal disease worldwide, but the efficacy of current therapeutic strategies on DN remains unsatisfactory. Recent research has reported the involvement of metabolic rearrangement in the pathological process of DN, and of all the disturbances in metabolism, mitochondria serve as key regulatory hubs. In the present study, high-resolution mass spectrometry-based nontarget metabolomics was used to uncover the metabolic characteristics of the early diabetic kidney with or without the inhibition of mitochondrial activity. At first, we observed a moderate enhancement of mitochondrial complex-1 activity in the diabetic kidney, which was completely normalized by the specific mitochondrial complex-1 inhibitor rotenone (ROT). Meanwhile, metabolomics data indicated an overactivated pentose phosphate pathway, purine and pyrimidine metabolism, hexosamine biosynthetic pathway, and tricarboxylic acid cycle, which were strikingly corrected by ROT. In addition, ROT also strikingly corrected imbalanced redox homeostasis, possibly by increasing the ratio of antioxidant metabolites glutathione and NADPH against their oxidative form. In agreement with the improved metabolic status and oxidative response, ROT attenuated glomerular and tubular injury efficiently. Fibrotic markers (fibronectin, α-smooth muscle actin, collagen type I, and collagen type III), inflammatory factors (TNF-α, IL-1β, and ICAM-1), and oxidative stress were all markedly blocked by ROT. In vitro, ROT dose dependently attenuated high glucose-induced proliferation and extracellular matrix production in mesangial cells. Collectively, these findings revealed that the overactivation of mitochondrial activity in the kidney could contribute to metabolic disorders and the pathogenesis of early DN.

miRNA‑mRNA regulatory network analysis of mesenchymal stem cell treatment in cisplatin‑induced acute kidney injury identifies roles for miR‑210/Serpine1 and miR‑378/Fos in regulating inflammation

The present study aimed to identify microRNAs (miRNAs) that may be crucial for the mechanism of mesenchymal stem cell (MSC) treatment in cisplatin-induced acute kidney injury (AKI) and to investigate other potential drugs that may have a similar function. Transcriptomics (GSE85957) and miRNA expression (GSE66761) datasets were downloaded from the Gene Expression Omnibus database. Differentially expressed genes (DEGs) and differentially expressed miRNAs (DEMs) were identified using the linear models for microarray data method and mRNA targets of DEMs were predicted using the miRWalk2.0 database. The crucial DEGs were screened by constructing a protein-protein interaction (PPI) network and module analysis. Functions of target genes were analyzed using the database for annotation, visualization and integrated discovery. Small molecule drugs were predicted using the connectivity map database. As a result, 5 DEMs were identified to be shared and oppositely expressed in comparisons between AKI model and control groups, and between MSC treatment and AKI model groups. The 103 DEGs were overlapped with the target genes of 5 common DEMs, and the resulting list was used for constructing the miRNA-mRNA regulatory network, including rno-miR-210/Serpine1 and rno-miR-378/Fos. Serpine1 (degree=17) and Fos (degree=42) were predicted to be hub genes according to the topological characteristic of degree in the PPI network. Function analysis indicated Serpine1 and Fos may be inflammation-related. Furthermore, gliclazide was suggested to be a potential drug for the treatment of AKI because the enrichment score was the closest to −1 (−0.9). In conclusion, it can be speculated that gliclazide may have a similar mechanism to MSC as a potential therapeutic agent for cisplatin-induced AKI, by regulating miR-210/Serpine1 and miR-378-/Fos-mediated inflammation and cell apoptosis.

Inhibition of the mitochondrial complex-1 protects against carbon tetrachloride-induced acute liver injury

Mitochondrial dysfunction has been documented to play a crucial role in the pathogenesis of liver injury. In the present study, we investigated the role of rotenone, a mitochondrial complex-1 inhibitor, in carbon tetrachloride (CCl₄) -induced acute liver injury, as well as the underlying mechanisms. Before CCl₄ administration, the mice were pretreated with rotenone at a dose of 250 ppm in food for three days. Then CCl₄ was administered to the mice for 16 h by intraperitoneal injection. The liver injury, mitochondrial status, oxidative stress, and inflammation were examined. Strikingly, CCl₄ treatment markedly induced liver injury as shown by enhanced serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) and morphological lesions (HE stating), which was significantly attenuated by rotenone treatment in line with the reduced activity of mitochondrial complex-1. Meanwhile, oxidative stress markers of malondialdehyde (MDA), 4-hydroxynonenal (HNE), and dihydroethidium (DHE) and the inflammatory markers of IL-1β, MCP-1, TNF-α, TLR-4, and IL-6 were also significantly suppressed by rotenone. More importantly, the mitochondrial abnormalities shown by the reduction of SOD2, mitochondrial transcription factor A (TFAM), mitochondrial NADH dehydrogenase subunit 1 (mtND1), and Cytb were significantly restored, indicating that rotenone protected against mitochondrial damage induced by CCl₄ in liver. Moreover, rotenone treatment alone did not significantly alter liver morphology and liver enzymes ALT and AST. CYP2E1, a metabolic enzyme of CCl₄, was also not significantly affected by rotenone. In conclusion, rotenone protected the liver from CCl₄-induced damage possibly by inhibiting the mitochondrial oxidative stress and inflammation.

Intervention of mitochondrial activity attenuates cisplatin-induced acute kidney injury

OBJECTIVES

The dysfunction of mitochondrial respiratory chain induced by cisplatin results in overproduction of reactive oxygen species (ROS) which contributes to kidney injury. The current study aimed to evaluate the effect of a mitochondrial electron transport inhibitors of rotenone (mitochondrial complex I inhibitor) and azoxystrobin (mitochondrial complex III inhibitor), in cisplatin-induced kidney injury.

METHODS

In vivo, cisplatin was administered to male C57BL/6J mice by a single intraperitoneal (i.p.) injection (20 mg/kg). Then the mice were treated with or without 200 ppm rotenone in food. Mice were sacrificed after cisplatin administration for 72 h. The serum and the kidney tissues were collected for further analysis. In vitro, mouse proximal tubular cells (mPTCs) were treated with cisplatin (5 µg/mL) and rotenone/azoxystrobin for 24 h. Flow cytometry, Western blotting, and TUNEL staining were used to evaluate the cell injury.

RESULTS

In vivo, rotenone treatment obviously ameliorated cisplatin-induced renal tubular injury evidenced by the improved histology and blocked NGAL upregulation. Meanwhile, cisplatin-induced renal dysfunction shown by the increased levels of serum creatinine (Scr), blood urea nitrogen (BUN), and cystatin C were significantly reduced by rotenone treatment. Moreover, the increments of cleaved caspase-3 and transferase dUTP nick-end labeling (TUNEL)-positive cells were markedly decreased in line with the attenuated mitochondrial dysfunction and oxidative stress after rotenone administration. In vitro, rotenone and azoxystrobin protected against mitochondrial dysfunction, oxidative stress, and renal tubular cell apoptosis induced by cisplatin.

CONCLUSIONS

Our results demonstrated that inhibition of mitochondrial activity significantly attenuated cisplatin nephrotoxicity possibly by inhibiting mitochondrial oxidative stress.

The role of PAK1 in the sensitivity of kidney epithelial cells to ischemia-like conditions

Kidney ischemia, characterized by insufficient supply of oxygen and nutrients to renal epithelial cells, is the main cause of acute kidney injury and an important contributor to mortality world-wide. Earlier research implicated a G-protein coupled receptor (NK1R) in the death of kidney epithelial cells in ischemia-like conditions. P21-associated kinase 1 (PAK1) is involved in signalling by several G-proteins. We explored the consequences of PAK1 inhibition for cell survival under the conditions of reduced glucose and oxygen. Inhibition of PAK1 by RNA interference, expression of a dominant-negative mutant or treatment with small molecule inhibitors greatly reduced the death of cultured kidney epithelial cells. Similar protection was achieved by treating the cells with inhibitors of MEK1, in agreement with the prior reports on PAK1-MEK1 connection. Concomitant inhibition of NK1R and PAK1 offered no better protection than inhibition of NK1R alone, consistent with the two proteins being members of the same pathway. Furthermore, NK1R, PAK and MEK inhibitors reduced the induction of TRAIL in ischemia-like conditions. Considering the emerging role of TRAIL in ischemia-mediated cell death, this phenomenon may contribute to the protective effects of these small molecules. Our findings support further exploration of PAK and MEK inhibitors as possible agents to avert ischemic kidney injury.

Extracellular micro/nanovesicles rescue kidney from ischemia-reperfusion injury

Acute renal failure (ARF) is a clinical challenge that is highly resistant to treatment, and its high rate of mortality is alarming. Ischemia-reperfusion injury (IRI) is the most common cause of ARF. Especially IRI is implicated in kidney transplantation and can determine graft survival. Although the exact pathophysiology of renal IRI is unknown, the role of inflammatory responses has been elucidated. Because mesenchymal stromal cells (MSCs) have strong immunomodulatory properties, they are under extensive investigation as a therapeutic modality for renal IRI. Extracellular vesicles (EVs) play an integral role in cell-to-cell communication. Because the regenerative potential of the MSCs can be recapitulated by their EVs, the therapeutic appeal of MSC-derived EVs has dramatically increased in the past decade. Higher safety profile and ease of preservation without losing function are other advantages of EVs compared with their producing cells. In the current review, the preliminary results and potential of MSC-derived EVs to alleviate kidney IRI are summarized. We might be heading toward a cell-free approach to treat renal IRI.

Effects of hydrogen sulfide on acetaminophen-induced acute renal toxicity in rats

INTRODUCTION AND AIM

Hydrogen sulfide (H₂S) is an endogenously produced gas-structure mediator. It is proposed to have antioxidant, anti-inflammatory and antiapoptotic effects. Acetaminophen (N-acetyl-P-aminophenol; APAP) is an antipyretic and analgesic medication known as paracetamol. When taken at therapeutic doses there are few side-effects, but at high doses APAP can cause clear liver and kidney damage in humans and experimental animals. In this study, the effects of the H₂S donor of sodium hydrosulfide (NaHS) on acute renal toxicity induced by APAP in rats were researched in comparison with N-acetyl cysteine (NAC).

METHOD

Rats were divided into six groups (n = 7) as control. APAP, APAP + NAC, APAP + NaHS 25 µmol/kg, NaHS 50 µmol/kg and NaHS 100 µmol/kg. After oral dose of 2 g/kg APAP, NAC and NaHS were administered via the i.p. route for 7 days. In renal homogenates, KIM-1 (Kidney Injury Molecule-1), NGAL (neutrophil gelatinase-associated lipocalin), TNF-α and TGFβ levels were measured with the ELISA method for tissue injury and inflammation. In renal tissue, oxidative stress levels were identified by spectrophotometric measurement of TAS and TOS. Histopathologic investigation of renal tissue used caspase 3 staining for apoptotic changes, Masson trichrome and H&E staining for variations occurring in glomerular and tubular systems.

RESULTS

NaHS lowered KIM-1, NGAL, TNF-α, TGF-β and TOS levels elevated in renal tissue linked to APAP and increased TAS values. NaHS prevented apoptosis in the kidney and was identified to ensure histologic amelioration in glomerular and tubular structures. NaHS at 50 µmol/kg dose was more effective, with the effect reduced with 100 µmol/kg dose.

CONCLUSION

H₂S shows protective effect against acute renal injury linked to APAP. This protective effect reduces with high doses of H₂S. The anti-inflammatory and antioxidant activity of H₂S may play a role in the renoprotective effect.