Withaferin A protects against endoplasmic reticulum stress-associated apoptosis, inflammation, and fibrosis in the kidney of a mouse model of unilateral ureteral obstruction

Imperatorin ameliorates ferroptotic cell death, inflammation, and renal fibrosis in a unilateral ureteral obstruction mouse model

BACKGROUND

Imperatorin is a naturally occurring furocoumarin derivative found in traditional Chinese medicine Angelica dahurica for its anticancer, antihypertensive, and antidiabetic properties. Chronic kidney disease (CKD) is a global health issue, characterized by a high prevalence, significant morbidity and mortality, and a range of related complications.

OBJECTIVE

This study aims to investigate the protective effects of imperatorin treatment and the specific underlying mechanisms in progressive CKD.

METHODS

Imperatorin was orally administrated for 14 consecutive days to mice with unilateral ureteral obstruction (UUO) to investigate the renal pathological alternations, pro-inflammatory mediators, antioxidant response, and ferroptotic death signaling. Imperatorin was also tested in the erastin-induced injury of renal proximal tubular cells (NRK-52E). Cell viability, ferroptosis protein markers, erastin-induced oxidative stress, and lipid peroxidation were assessed.

RESULTS

In vivo, imperatorin treatment alleviated kidney histology alternations and attenuated the protein expression of fibrotic markers. Furthermore, imperatorin administration reduced inflammatory cell infiltration, and alleviated the oxidative stress burden by downregulating protein markers such as catalase, superoxide dismutase 2 (SOD-2), NADPH oxidase 4 (NOX-4), and thioredoxin reductase 1 (Trxr-1). It also mitigated ferroptosis markers such as glutathione peroxidase 4 (GPX4), solute carrier family 7 member 11/cystine transporter (SLC7A11/xCT), and transferrin receptor 1 (TFR-1), and attenuated renal cell apoptosis. In vitro, imperatorin treatment effectively decreased erastin-induced feroptotic cell death, restored the antioxidant enzyme levels, and mitigated lipid peroxidation as well as the expression of ferroptosis-related markers (XCT, GPX4, and p-p53) in a dose-dependent manner.

CONCLUSION

Our finding demonstrated for the first time, that imperatorin treatment holds therapeutic potential in a UUO mouse model of CKD and inhibits the erastin-induced oxidative stress, ferroptosis, and subsequent lipid peroxidation in vitro. This highlights the potential of imperatorin as a future therapeutic target for ferroptosis to improve the progression of CKD.

Natural products derived from traditional Chinese medicines targeting ER stress for the treatment of kidney diseases

Various factors, both internal and external, can disrupt endoplasmic reticulum (ER) homeostasis and increase the burden of protein folding, resulting in ER stress. While short periods of ER stress can help cells return to normal function, excessive or prolonged ER stress triggers a complex signaling network that negatively affects cells. Numerous studies have demonstrated the significant role of ER stress in various kidney diseases, such as immune-related kidney injury, diabetic kidney diseases, renal ischemia reperfusion injury, and renal fibrosis. To date, there is a severe shortage of medications for the treatment of acute and chronic kidney diseases of all causes. Natural products derived from various traditional Chinese medicines (TCM), which are a major source of new drugs, have garnered considerable attention. Recent research has revealed that many natural products have renoprotective effects by targeting ER stress-mediated events, such as apoptosis, oxidative stress, inflammation, autophagy, and epithelial-mesenchymal transition. This article provides a comprehensive review of the current research progress on natural products targeting ER stress for the treatment of kidney diseases.

Endoplasmic Reticulum Stress-Mediated Cell Death in Renal Fibrosis

The endoplasmic reticulum (ER) is indispensable for maintaining normal life activities. Dysregulation of the ER function results in the accumulation of harmful proteins and lipids and the disruption of intracellular signaling pathways, leading to cellular dysfunction and eventual death. Protein misfolding within the ER disrupts its delicate balance, resulting in the accumulation of misfolded or unfolded proteins, a condition known as endoplasmic reticulum stress (ERS). Renal fibrosis, characterized by the aberrant proliferation of fibrotic tissue in the renal interstitium, stands as a grave consequence of numerous kidney disorders, precipitating a gradual decline in renal function. Renal fibrosis is a serious complication of many kidney conditions and is characterized by the overgrowth of fibrotic tissue in the glomerular and tubular interstitium, leading to the progressive failure of renal function. Studies have shown that, during the onset and progression of kidney disease, ERS causes various problems in the kidneys, a process that can lead to kidney fibrosis. This article elucidates the underlying intracellular signaling pathways modulated by ERS, delineating its role in triggering diverse forms of cell death. Additionally, it comprehensively explores a spectrum of potential pharmacological agents and molecular interventions aimed at mitigating ERS, thereby charting novel research avenues and therapeutic advancements in the management of renal fibrosis.

Emerging Vistas for the Nutraceutical Withania somnifera in Inflammaging

Inflammaging, a coexistence of inflammation and aging, is a persistent, systemic, low-grade inflammation seen in the geriatric population. Various natural compounds have been greatly explored for their potential role in preventing and treating inflammaging. Withania somnifera has been used for thousands of years in traditional medicine as a nutraceutical for its numerous health benefits including regenerative and adaptogenic effects. Recent preclinical and clinical studies on the role of Withania somnifera and its active compounds in treating aging, inflammation, and oxidative stress have shown promise for its use in healthy aging. We discuss the chemistry of Withania somnifera, the etiology of inflammaging and the protective role(s) of Withania somnifera in inflammaging in key organ systems including brain, lung, kidney, and liver as well as the mechanistic underpinning of these effects. Furthermore, we elucidate the beneficial effects of Withania somnifera in oxidative stress/DNA damage, immunomodulation, COVID-19, and the microbiome. We also delineate a putative protein-protein interaction network of key biomarkers modulated by Withania somnifera in inflammaging. In addition, we review the safety/potential toxicity of Withania somnifera as well as global clinical trials on Withania somnifera. Taken together, this is a synthetic review on the beneficial effects of Withania somnifera in inflammaging and highlights the potential of Withania somnifera in improving the health-related quality of life (HRQoL) in the aging population worldwide.

Ivermectin Inhibits Bladder Cancer Cell Growth and Induces Oxidative Stress and DNA Damage

BACKGROUND

Bladder cancer is the most common malignant tumor of the urinary system. Nevertheless, current therapies do not provide satisfactory results. It is imperative that novel strategies should be developed for treating bladder cancer.

OBJECTIVES

To evaluate the effect of a broad-spectrum anti-parasitic agent, Ivermectin, on bladder cancer cells in vitro and in vivo.

METHODS

CCK-8 and EdU incorporation assays were used to evaluate cell proliferation. Apoptosis was detected by flow cytometry, TUNEL assay, and western blotting. Flow cytometry and DCFH-DA assay were used to analyze the reactive oxygen species (ROS) levels. DNA damage was determined by Neutral COMET assay and γ H2AX expression. Proteins related to apoptosis and DNA damage pathways were determined by WB assay. Xenograft tumor models in nude mice were used to investigate the anti-cancer effect of Ivermectin in vivo.

RESULTS

Our study showed that in vitro and in vivo, Ivermectin inhibited the growth of bladder cancer cells. In addition, Ivermectin could induce apoptosis, ROS production, DNA damage, and activate ATM/P53 pathwayrelated proteins in bladder cancer cells.

CONCLUSIONS

According to these findings, Ivermectin may be a potential therapeutic candidate against bladder cancer due to its significant anti-cancer effect.

Research progress on the mechanism of renal interstitial fibrosis in obstructive nephropathy

Renal fibrosis is a common result for various chronic kidney diseases developing to the end stage. It is a pathological process characterized by the destruction of normal kidney structure and the subsequent replacement with fibrous tissue, which primarily involves fibroblast proliferation and extracellular matrix deposition. Obstruction is a common cause of renal fibrosis, and obstructive renal fibrosis is a common disease in urology. Obstructive renal fibrosis, characterized by its insidious onset, is the result of a complex interplay of multiple factors. These factors encompass renal tubular epithelial cell injury, the presence of a hypoxic microenvironment in affected kidney tissue, inflammatory cell infiltration, release of inflammatory mediators, and the release of renal fibrosis growth factors, among others. This paper reviews the research progress on the mechanism and treatment of renal interstitial fibrosis.

Bacterial clearance and anti-inflammatory effect of Withaferin A against human pathogen of Staphylococcus aureus in infected zebrafish

The emergence of antibiotic resistance is the most challenging factor for developing a proper drug to treat S. aureus infection. These bacterial pathogens can survive in fresh water and spread to various environments. Plant sources, especially pure compounds, are the material of interest amongst researchers for developing drugs of therapeutic value. Here, we report the bacterial clearance and anti-inflammatory potential of the plant compound Withaferin A, using the zebrafish infection model. The minimum inhibitory concentration of the Withaferin A was calculated as 80 µM against S. aureus. The DAPI/PI staining and scanning electron microscopy analysis showed the pore-forming mechanism of Withaferin A on the bacterial membrane. Along with the antibacterial activity, the results from the tube adherence test reveal the antibiofilm property of Withaferin A. In vivo studies were demonstrated to determine the effect of Withaferin A on survival, inflammatory response and behavioural changes during S. aureus infection. Staining zebrafish larvae with neutral red and Sudan black indicates a substantial decrease in the number of localized macrophages and neutrophils. The gene expression analysis showed the downregulation of inflammatory marker genes. Additionally, we observed the improvement in locomotory behaviour among Withaferin A treatment adult zebrafish. In conclusion, S. aureus can infect zebrafish and induces toxicological effect. In comparison, the results from in vitro and in vivo experiments suggest that Withaferin A can be used for synergistic antibacterial, antibiofilm and anti-inflammatory activity to treat infections due S. aureus.

PRE-084 ameliorated kidney injury by reducing endoplasmic reticulum stress in the rat model of adenine-induced chronic kidney disease

BACKGROUND

Endoplasmic reticulum (ER) stress plays an important role in the development of chronic kidney disease (CKD). Sigma-1 receptors (σ1Rs) are novel chaperone proteins that regulate ER stress. However, effect of σ1R activation on renal ER stress is yet unexplored. So, in the present study we investigated the effects of PRE-084, a σ1R agonist on renal injury and ER stress in the rat model of CKD.

METHODS

CKD group rats were fed adenine for 28 days and CKD treatment group rats were additionally administered PRE-084 intraperitoneally at 1, 3 and 10 mg/kg body weight dose from Day 22-28. ER stress markers were evaluated using molecular biology techniques such as immunohistochemistry and Western blot.

RESULTS

Marked kidney injury was observed in CKD rats as revealed by biochemical and histological findings. Expression of ER stress proteins such as phosphorylated protein kinase R-like ER kinase (p-PERK), cleaved activating transcription factor-6 (ATF-6f), phosphorylated inositol requiring enzyme1α (p-IRE1α) and caspase-12 were higher in CKD rats. Nevertheless, CKD rats treated with PRE-084 particularly at 10 mg/kg dose showed considerably lesser kidney injury along with higher expression of σ1R and marked reduction of all the ER stress proteins studied.

CONCLUSION

Results reveal that PRE-084 likely ameliorated the adenine-induced kidney injury by lowering ER stress through increased σ1R expression.

The Development of Dyslipidemia in Chronic Kidney Disease and Associated Cardiovascular Damage, and the Protective Effects of Curcuminoids

Chronic kidney disease (CKD) is a health problem that is constantly growing. This disease presents a diverse symptomatology that implies complex therapeutic management. One of its characteristic symptoms is dyslipidemia, which becomes a risk factor for developing cardiovascular diseases and increases the mortality of CKD patients. Various drugs, particularly those used for dyslipidemia, consumed in the course of CKD lead to side effects that delay the patient's recovery. Therefore, it is necessary to implement new therapies with natural compounds, such as curcuminoids (derived from the Curcuma longa plant), which can cushion the damage caused by the excessive use of medications. This manuscript aims to review the current evidence on the use of curcuminoids on dyslipidemia in CKD and CKD-induced cardiovascular disease (CVD). We first described oxidative stress, inflammation, fibrosis, and metabolic reprogramming as factors that induce dyslipidemia in CKD and their association with CVD development. We proposed the potential use of curcuminoids in CKD and their utilization in clinics to treat CKD-dyslipidemia.

Ashwagandha-loaded nanocapsules improved the behavioral alterations, and blocked MAPK and induced Nrf2 signaling pathways in a hepatic encephalopathy rat model

Ashwagandha (ASH), a vital herb in Ayurvedic medicine, demonstrated potent preclinical hepato- and neuroprotective effects. However, its efficacy is limited due to low oral bioavailability. Accordingly, we encapsulated ASH extract in chitosan-alginate bipolymeric nanocapsules (ASH-BPNCs) to enhance its physical stability and therapeutic effectiveness in the gastrointestinal tract. ASH-BPNC was prepared by emulsification followed by sonication. The NCs showed small particle size (< 220 nm), zeta-potential of 25.2 mV, relatively high entrapment efficiency (79%), physical stability at acidic and neutral pH, and in vitro release profile that extended over 48 h. ASH-BPNC was then investigated in a thioacetamide-induced hepatic encephalopathy (HE) rat model. Compared with free ASH, ASH-BPNC improved survival, neurological score, general motor activity, and cognitive task-performance. ASH-BPNC restored ALT, AST and ammonia serum levels, and maintained hepatic and brain architecture. ASH-BPNC also restored GSH, MDA, and glutathione synthetase levels, and Nrf2 and MAPK signaling pathways in liver and brain tissues. Moreover, ASH-BPNC downregulated hepatic NF-κB immunohistochemical expression. Moreover, the in vivo biodistribution studies demonstrated that most of the administered ASH-BPNC is accumulated in the brain and hepatic tissues. In conclusion, chitosan-alginate BPNCs enhanced the hepatoprotective and neuroprotective effects of ASH, thus providing a promising therapeutic approach for HE.

Inhibition of RIP1-RIP3-mediated necroptosis attenuates renal fibrosis via Wnt3α/β-catenin/GSK-3β signaling in unilateral ureteral obstruction

Renal fibrosis represents the final common outcome of chronic kidney disease of virtually any etiology. However, the mechanism underlying the evolution of renal fibrosis remains to be addressed. This study sought to clarify whether RIP1-RIP3-mediated necroptosis is involved in renal fibrosis via Wnt3α/β-catenin/GSK-3β signaling in vitro and in a rat model of unilateral ureteral obstruction (UUO). Rats with UUO were administered RIP inhibitors (necrostatin-1 or GSK872) or β-catenin/TCF inhibitor ICG-001 daily for 7 consecutive days. UUO caused significant renal tubular necrosis and overexpression of RIP1-RIP3-MLKL axis proteins, and was accompanied by activation of the NLRP3 inflammasome and renal fibrosis. Oxidative stress caused by UUO was closely associated with endoplasmic reticulum stress and mitochondrial dysfunction, which resulted in apoptotic cell death via Wnt3α/β-catenin/GSK-3β signaling. All of these effects were abolished by an RIP inhibitor (necrostatin-1 or GSK872) or ICG-001. In H2O2-treated HK-2 cells, both RIP inhibitor and ICG-001 decreased intracellular reactive oxygen species production and apoptotic cells, but increased cell viability. Activated Wnt3α/β-catenin/GSK-3β signaling was decreased by either RIP inhibitor or ICG-001. Our findings suggest that RIP1-RIP3-mediated necroptosis contributes to the development of renal fibrosis via Wnt3α/β-catenin/GSK-3β signaling in UUO and may be a therapeutic target for protection against renal scarring of other origins.

Coenzyme Q10 attenuates renal fibrosis by inhibiting RIP1-RIP3-MLKL-mediated necroinflammation via Wnt3α/β-catenin/GSK-3β signaling in unilateral ureteral obstruction

OBJECTIVE

Coenzyme Q10 (CoQ10) protects against various types of injury, but its role in preventing renal scarring in chronic kidney disease remains an open question. Herein, we evaluated whether CoQ10 attenuates renal fibrosis by interfering with necroinflammation in a rat model of unilateral ureteral obstruction (UUO) and in vitro.

METHODS

Rats with UUO were treated daily with CoQ10 or an RIP inhibitor (necrostatin-1 or GSK872) for 7 days. The influence of CoQ10 on renal injury caused by UUO was evaluated by histopathology and analysis of gene expression, oxidative stress, intracellular organelles, apoptosis, and Wnt3α/β-catenin/GSK-3β signaling·H2O2-exposed human kidney (HK-2) cells were also examined after treatment with CoQ10 or an RIP inhibitor.

RESULTS

UUO induced marked renal tubular necrosis, upregulation of RIP1-RIP3-MLKL axis proteins, activation of the NLRP3 inflammasome, and evolution of renal fibrosis. UUO-induced oxidative stress evoked excessive endoplasmic reticulum stress and mitochondrial dysfunction, which triggered apoptotic cell death through Wnt3α/β-catenin/GSK-3β signaling. All of these effects were mitigated by CoQ10 or an RIP inhibitor. In H2O2-treated HK-2 cells, CoQ10 or an RIP inhibitor suppressed the expression of RIP1-RIP3-MLKL proteins and pyroptosis-related cytokines, and hindered the production of intracellular reactive oxygen species as shown by MitoSOX Red staining and apoptotic cell death but increased cell viability. The CoQ10 or Wnt/β-catenin inhibitor ICG-001 deactivated H2O2-stimulated activation of Wnt3α/β-catenin/GSK-3β signaling.

CONCLUSION

These findings suggest that CoQ10 attenuates renal fibrosis by inhibiting RIP1-RIP3-MLKL-mediated necroinflammation via Wnt3α/β-catenin/GSK-3β signaling in UUO.

Withaferin A Inhibits Neutrophil Adhesion, Migration, and Respiratory Burst and Promotes Timely Neutrophil Apoptosis

Neutrophils play a major role in many equine conditions, including equine asthma, laminitis, and intestinal ischemia and reperfusion injury, and therefore represent an attractive target for innovative therapeutic approaches. Novel strategies for reducing neutrophilic inflammation include modulation of neutrophil functions and lifespan. Withaferin A (WFA) is a phytochemical with well-established in vitro and in vivo anti-inflammatory properties, but its direct effects on neutrophils are largely unknown. We hypothesized that WFA would inhibit adhesion, migration, and respiratory burst by equine neutrophils and promote timely apoptosis of primed equine neutrophils. Consistent with this hypothesis, our data show that WFA causes a significant, concentration-dependent inhibition of equine neutrophil adhesion, migration, and respiratory burst in response to diverse stimuli. Further, WFA treatment increased apoptosis of equine neutrophils exposed to GM-CSF for 24 h. This pro-apoptotic effect of WFA was not observed in unprimed neutrophils, nor at the 2-h time point relevant to our functional neutrophil experiments. Our data demonstrate that WFA may reduce neutrophil-mediated inflammation through multiple mechanisms, including suppression of inflammatory responses and promotion of apoptosis. Additional research is needed to elucidate the molecular mechanisms for these effects and evaluate the potential clinical use of WFA in veterinary and human patients.

Therapeutic Implications of Ferroptosis in Renal Fibrosis

Renal fibrosis is a common feature of chronic kidney disease (CKD), and can lead to the destruction of normal renal structure and loss of kidney function. Little progress has been made in reversing fibrosis in recent years. Ferroptosis is more immunogenic than apoptosis due to the release and activation of damage-related molecular patterns (DAMPs) signals. In this paper, the relationship between renal fibrosis and ferroptosis was reviewed from the perspective of iron metabolism and lipid peroxidation, and some pharmaceuticals or chemicals associated with both ferroptosis and renal fibrosis were summarized. Other programmed cell death and ferroptosis in renal fibrosis were also firstly reviewed for comparison and further investigation.

Therapeutic effect of quercetin polymeric nanoparticles on ischemia/reperfusion-induced acute kidney injury in mice

Acute kidney injury (AKI) is known as a sudden episode of kidney injury, which happens suddenly within a few hours or a few days. Quercetin (3,3',4',5,7-pentahydroxyflavone) is a flavonoid found in plants. Quercetin is known to have several biological activities, such as anti-oxidant, anti-inflammatory, and anti-carcinogenic effects. However, low water solubility and bioavailability are the limitations of quercetin for its clinical applications. Moreover, ischemia/reperfusion (I/R) injury is a common cause of AKI. There are no satisfactory strategies for I/R-induced AKI. Developing suitable preventive or therapeutic intervention for AKI is an important and urgent issue. We investigated the benefit effect of synthesized polyethylene glycol (PEG) conjugated polyethyleneimine (PEI) nanoparticles for targeted delivery of quercetin on AKI in a mouse model. An I/R-induced AKI mouse model was used to evaluate the therapeutic effect of quercetin polymeric nanoparticles by intravenous injection. Biochemical changes for renal function in blood samples were analyzed. Histological and immunohistochemical changes were also analyzed. The biochemical changes of blood urea nitrogen (BUN), creatinine, and cystatin C were significantly increased in I/R-induced AKI mice, which could be significantly reversed by quercetin polymeric nanoparticles. Quercetin polymeric nanoparticles could also significantly decrease the histological lesions, positive staining for 3-nitrotyrosine and cyclooxygenase-2, and lipid peroxidation in the kidneys of I/R-induced AKI mice. These results demonstrate for the first time that quercetin polymeric nanoparticles possess therapeutic potential for the treatment of I/R-induced AKI in vivo.

EPA-Enriched Phospholipids Alleviate Renal Interstitial Fibrosis in Spontaneously Hypertensive Rats by Regulating TGF-β Signaling Pathways

Hypertensive nephropathy is a chronic kidney disease caused by hypertension. Eicosapentaenoic acid (EPA) has been reported to possess an antihypertensive effect, and our previous study suggested that EPA-enriched phospholipid (EPA-PL) had more significant bioactivities compared with traditional EPA. However, the effect of dietary EPA-PL on hypertensive nephropathy has not been studied. The current study was designed to examine the protection of EPA-PL against kidney damage in spontaneously hypertensive rats (SHRs). Treatment with EPA-PL for three weeks significantly reduced blood pressure through regulating the renin–angiotensin system in SHRs. Moreover, dietary EPA-PL distinctly alleviated kidney dysfunction in SHRs, evidenced by reduced plasma creatinine, blood urea nitrogen, and 24 h proteinuria. Histology results revealed that treatment of SHRs with EPA-PL alleviated renal injury and reduced tubulointerstitial fibrosis. Further mechanistic studies indicated that dietary EPA-PL remarkably inhibited the activation of TGF-β and Smad 3, elevated the phosphorylation level of PI3K/AKT, suppressed the activation of NF-κB, reduced the expression of pro-inflammatory cytokines, including IL-1β and IL-6, and repressed the oxidative stress and the mitochondria-mediated apoptotic signaling pathway in the kidney. These results indicate that EPA-PL has potential value in the prevention and alleviation of hypertensive nephropathy.

Alternative Targets for Modulators of Mitochondrial Potassium Channels

Mitochondrial potassium channels control potassium influx into the mitochondrial matrix and thus regulate mitochondrial membrane potential, volume, respiration, and synthesis of reactive oxygen species (ROS). It has been found that pharmacological activation of mitochondrial potassium channels during ischemia/reperfusion (I/R) injury activates cytoprotective mechanisms resulting in increased cell survival. In cancer cells, the inhibition of these channels leads to increased cell death. Therefore, mitochondrial potassium channels are intriguing targets for the development of new pharmacological strategies. In most cases, however, the substances that modulate the mitochondrial potassium channels have a few alternative targets in the cell. This may result in unexpected or unwanted effects induced by these compounds. In our review, we briefly present the various classes of mitochondrial potassium (mitoK) channels and describe the chemical compounds that modulate their activity. We also describe examples of the multidirectional activity of the activators and inhibitors of mitochondrial potassium channels.

Protective Effects of Nootkatone on Renal Inflammation, Apoptosis, and Fibrosis in a Unilateral Ureteral Obstructive Mouse Model

Nootkatone is one of the major active ingredients of Alpiniae oxyphyllae, which has been used as both food and medicinal plants for the treatment of diarrhea, ulceration, and enuresis. In this study, we aimed to investigate whether nootkatone treatment ameliorated the progression of chronic kidney diseases (CKD) and clarified its underlying mechanisms in an obstructive nephropathy (unilateral ureteral obstructive; UUO) mouse model. Our results revealed that nootkatone treatment preventively decreased the pathological changes and significantly mitigated the collagen deposition as well as the protein expression of fibrotic markers. Nootkatone could also alleviate oxidative stress-induced injury, inflammatory cell infiltration, and renal cell apoptotic death in the kidneys of UUO mice. These results demonstrated for the first time that nootkatone protected against the progression of CKD in a UUO mouse model. It may serve as a potential therapeutic candidate for CKD intervention.

Redox signaling pathways in unilateral ureteral obstruction (UUO)-induced renal fibrosis

Unilateral ureteral obstruction (UUO) is an experimental rodent model that mimics renal fibrosis associated with obstructive nephropathy in an accelerated manner. After UUO, the activation of the renin-angiotensin system (RAS), nicotinamide adenine dinucleotide phosphate (NADPH) oxidases (NOXs) and mitochondrial dysfunction lead to reactive oxygen species (ROS) overproduction in the kidney. ROS are secondary messengers able to induce post-translational modifications (PTMs) in redox-sensitive proteins, which activate or deactivate signaling pathways. Therefore, in UUO, it has been proposed that ROS overproduction causes changes in said pathways promoting inflammation, oxidative stress, and apoptosis that contribute to fibrosis development. Furthermore, mitochondrial metabolism impairment has been associated with UUO, contributing to renal damage in this model. Although ROS production and oxidative stress have been studied in UUO, the development of renal fibrosis associated with redox signaling pathways has not been addressed. This review focuses on the current information about the activation and deactivation of signaling pathways sensitive to a redox state and their effect on mitochondrial metabolism in the fibrosis development in the UUO model.

A Review of Traditional Chinese Medicine in Treating Renal Interstitial Fibrosis via Endoplasmic Reticulum Stress-Mediated Apoptosis

Renal interstitial fibrosis (RIF) is the main pathological manifestation of end-stage renal disease. Recent studies have shown that endoplasmic reticulum (ER) stress is involved in the pathogenesis and development of RIF. Traditional Chinese medicine (TCM), as an effective treatment for kidney diseases, can improve kidney damage by affecting the apoptotic signaling pathway mediated by ER stress. This article reviews the apoptotic pathways mediated by ER stress, including the three major signaling pathways of unfolded protein response, the main functions of the transcription factor C/EBP homologous protein. We also present current research on TCM treatment of RIF, focusing on medicines that regulate ER stress. A new understanding of using TCM to treat kidney disease by regulating ER stress will promote clinical application of Chinese medicine and discovery of new drugs for the treatment of RIF.

Withaferin A protects against hyperuricemia induced kidney injury and its possible mechanisms

The study was designed to explore the effects of Withaferin A (WFA) on hyperuricemia-induced kidney injury and its action mechanism. Potassium oxonate (PO) was employed to establish the hyperuricemic mouse model. The pathological changes of renal tissue were evaluated by hematoxylin-eosin and masson trichrome staining. The levels of creatinine, blood urea nitrogen (BUN), uric acid (UA) and xanthine oxidase (XOD) were detected using corresponding commercial kits. Expressions of collagen-related and apoptosis-associated proteins in renal tissues were, respectively, evaluated by immunofluorescence and western blotting. Cell apoptosis was detected by TUNEL assay, and transporter expressions using western blotting. Followed by WFA, NRK-52E cells were treated with UA before evaluation of apoptosis and fibrosis. Results indicated that WFA ameliorated renal damage, improved kidney function, and decreased levels of creatinine, BUN, UA, and XOD in PO-induced hyperuricemic mice. Furthermore, WFA significantly prevented renal fibrosis and increased the expression of collagen-related proteins. Similarly, WFA markedly inhibited renal apoptosis, accompanied by changes of apoptosis-related proteins. Importantly, expression of transporters responsible for the secretion of organic anion transporter 1 (OAT1), OAT3, ATP-binding cassette subfamily G member 2 (ABCG2) was remarkably enhanced whereas that of urate transporter 1 (URAT1) and glucose transporter 9 (GLUT9) was reduced in renal tissues of mice with hyperuricemia. In vitro study revealed that WFA notably ameliorated UA-induced cell fibrosis and apoptosis. Taken together, WFA improves kidney function by decreasing UA via regulation of XOD and transporter genes in renal tubular cells.