Renoprotective mechanisms of Astragaloside IV in cisplatin-induced acute kidney injury

Nephrotoxicity remains a serious adverse effect of cisplatin chemotherapy, limiting its clinical usage. Numerous studies show that oxidative stress and inflammation are closely associated with cisplatin-induced renal damage. Astragaloside IV (AS-IV) has been found to possess antioxidant and anti-inflammation functions. Therefore, we investigated the potential curative effects of AS-IV against cisplatin-induced renal injury and the possible cellular mechanism for activity, both in vitro and in vivo. We found that pretreatment of HK-2 cells with AS-IV could mitigate cisplatin-induced cell damage caused by oxygen-free radicals and the inflammatory response, as evidenced by reduced formation of reactive oxygen species (ROS) and inflammatory cytokines. AS-IV improved cisplatin-induced renal dysfunction and histopathological injury in mice. Additionally, AS-IV enhanced the activities of total superoxide dismutase (T-SOD), glutathione peroxidase (GSH-Px), and catalase (CAT). It also inhibited cisplatin-induced overproduction of kidney injury molecule-1 (KIM-1), malondialdehyde (MDA), tumour necrosis factor-α (TNF???α), and interleukin-1β (IL-1β) in kidney tissues. We found that the protective effects of AS-IV occurred via activation of the nuclear factor-erythroid 2-related factor 2 (Nrf2) and heme oxygenase-1 (HO-1) proteins and inhibition of nuclear factor-κappaB (NF-κB) activation. Further, small interfering RNA (siRNA) knockdown of Nrf2 abrogated the protective effects of AS-IV against cisplatin-induced oxidative stress and blocked the inhibitory effects of AS-IV on cisplatin-induced NF-κB activation and inflammatory cytokine production. In conclusion, our data suggested that AS-IV attenuated cisplatin-mediated renal injury, and these protective effects might be due to inhibition of both oxidative damage and inflammatory response via activation of Nrf2 system and suppression of NF-κB activation.     

Dose-dependent deleterious and salutary actions of the Nrf2 inducer dh404 in chronic kidney disease

Oxidative stress and inflammation play a central role in the progression and complications of chronic kidney disease (CKD) and are, in part, due to impairment of the Nrf2 system, which regulates the expression of antioxidant and detoxifying molecules. Natural Nrf2-inducing phytochemicals have been shown to ameliorate kidney disease in experimental animals. However, owing to adverse outcomes a clinical trial of a synthetic Nrf2 activator, bardoxolone methyl (BARD), in CKD patients was terminated. BARD activates Nrf2 via covalent modification of reactive cysteine residues in the Nrf2 repressor molecule, Keap1. In addition to Nrf2, Keap1 suppresses IKKB, the positive regulator of NF-κB. Treatment with a BARD analog, dh404, at 5–20 mg/kg/day in diabetic obese Zucker rats exacerbates, whereas its use at 2 mg/kg/day in 5/6 nephrectomized rats attenuates, CKD progression. We, therefore, hypothesized that deleterious effects of high-dose BARD are mediated by the activation of NF-κB. CKD (5/6 nephrectomized) rats were randomized to receive dh404 (2 or 10 mg/kg/day) or vehicle for 12 weeks. The vehicle-treated group exhibited glomerulosclerosis; interstitial fibrosis and inflammation; activation of NF-κB; upregulation of oxidative, inflammatory, and fibrotic pathways; and suppression of Nrf2 activity and its key target gene products. Treatment with low-dose dh404 restored Nrf2 activity and expression of its target genes, attenuated activation of NF-κB and fibrotic pathways, and reduced glomerulosclerosis, interstitial fibrosis, and inflammation. In contrast, treatment with a high dh404 dosage intensified proteinuria, renal dysfunction, and histological abnormalities; amplified upregulation of NF-κB and fibrotic pathways; and suppressed the Nrf2 system. Thus therapy with BARD analogs exerts a dose-dependent dimorphic impact on CKD progression.     

Polysaccharides from Dicliptera chinensis ameliorate liver disturbance by regulating TLR-4/NF-κB and AMPK/Nrf2 signalling pathways

The purpose of this study was to alleviate liver disturbance by applying polysaccharides from Dicliptera chinensis (DCP) to act on the adenosine monophosphate–activated protein kinase/ nuclear factor erythroid 2-related factor 2 (AMPK/ Nrf2) oxidative stress pathway and the Toll-like receptor 4 (TLR-4)/ nuclear factor kappa-B (NF-κB) inflammatory pathway and to establish an in vivo liver disturbance model using male C57BL/6J and TLR-4 knockout (^−/−) mice. For this, we evaluated the expression levels of SREBP-1 and Nrf2 after silencing the expression of AMPK using siRNA technology. Our results show that with regard to the TLR-4/ NF-κB inflammatory pathway, DCP inhibits TLR-4, up-regulates the expression of peroxisome proliferator-activated receptor-γ (PPAR-γ), reduces the expression of phospho(p)-NF-κB and leads to the reduction of downstream inflammatory factors, such as tumour necrosis factor-α (TNF-α), interleukin (IL)-6 and IL-1β, thereby inhibiting the inflammatory response. Regarding the AMPK/ Nrf2 oxidative stress pathway, DCP up-regulates the expression of p-AMPK and Nrf2, in addition to regulating glucose and lipid metabolism, oxidative stress and ameliorating liver disturbance symptoms. In summary, our study shows that DCP alleviates liver disturbances by inhibiting mechanisms used during liver inflammation and oxidative stress depression, which provides a new strategy for the clinical treatment of liver disturbance.     

Klotho protects the heart from hyperglycemia-induced injury by inactivating ROS and NF-κB-mediated inflammation both in vitro and in vivo

Cardiac inflammation and oxidative stress play a key role in the pathogenesis of diabetic cardiomyopathy (DCM). The anti-aging protein Klotho has been found to protect cells from inflammation and oxidative stress. The current study aimed to explore the cardioprotective effects of Klotho on DCM and the underlying mechanisms. H9c2 cells and neonatal cardiomyocytes were incubated with 33 mM glucose in the presence or absence of Klotho. Klotho pretreatment effectively inhibited high glucose-induced inflammation, ROS generation, apoptosis, mitochondrial dysfunction, fibrosis and hypertrophy in both H9c2 cells and neonatal cardiomyocytes. In STZ-induced type 1 diabetic mice, intraperitoneal injection of Klotho at 0.01 mg/kg per 48 h for 3 months completely suppressed cardiac inflammatory cytokines and oxidative stress and prevented cardiac cell death and remodeling, which subsequently improved cardiac dysfunction without affecting hyperglycemia. This study revealed that Klotho may exert its protective effects by augmenting nuclear factor erythroid 2-related factor 2 (Nrf2) expression and inactivating nuclear factor κB (NF-κB) activation both in vitro and in vivo. Thus, this work demonstrated for the first time that the anti-aging protein Klotho may be a potential therapeutic agent to treat DCM by inhibiting oxidative stress and inflammation. We also demonstrated the critical roles of the Nrf2 and NF-κB pathways in diabetes-stimulated cardiac injuries and indicated that they may be key therapeutic targets for diabetic complications.     

Epigallocatechin-3-gallate prevents lupus nephritis development in mice via enhancing the Nrf2 antioxidant pathway and inhibiting NLRP3 inflammasome activation

Patients with lupus nephritis show an impaired oxidative status and increased levels of interleukin (IL)-1β and IL-18, which are closely linked to inflammation and correlated with disease activity. Although epigallocatechin-3-gallate (EGCG), the major bioactive polyphenol present in green tea with antioxidant and free radical scavenging activities, has been reported to have anti-inflammatory effects by inhibiting nuclear factor-kappa B (NF-κB)-mediated inflammatory responses in vivo, its effectiveness for the treatment of lupus nephritis is still unknown. In the present study, 12-week-old New Zealand black/white (NZB/W) F1 lupus-prone mice were treated daily with EGCG by gavage until sacrificed at 34 weeks old for clinical, pathological, and mechanistic evaluation. We found that the administration (1) prevented proteinuria, renal function impairment, and severe renal lesions; (2) increased renal nuclear factor E2-related factor 2 (Nrf2) and glutathione peroxidase activity; (3) reduced renal oxidative stress, NF-κB activation, and NLRP3 mRNA/protein expression and protein levels of mature caspase-1, IL-1β, and IL-18; and (4) enhanced splenic regulatory T (Treg) cell activity. Our data clearly demonstrate that EGCG has prophylactic effects on lupus nephritis in these mice that are highly associated with its effects of enhancing the Nrf2 antioxidant signaling pathway, decreasing renal NLRP3 inflammasome activation, and increasing systemic Treg cell activity.     

Mefunidone ameliorates renal inflammation and tubulointerstitial fibrosis via suppression of IKKβ phosphorylation

Mefunidone is a new pyridone agent that attenuates renal tubulointerstitial fibrosis. However, the signaling pathways involved in the effect of mefunidone on renal tubulointerstitial fibrosis have not been well explained. Inflammatory response initiates and promotes renal tubulointerstitial fibrosis, and the inhibitor of nuclear factor kappa-B kinase beta (IKKβ) is a master regulator of inflammation. This study is determined to clarify the influence of mefunidone on renal inflammation and the phosphorylation of IKKβ. Experimental renal tubulointerstitial fibrosis was induced by unilateral ureteral obstruction (UUO) for 3, 7 and 14 days in sprague dawley rat. Treatment with mefunidone was conducted simultaneously. Obstructed kidneys were harvested for the assessment. Our results showed that treatment with mefunidone ameliorated renal inflammatory injury, renal tubular lesions and interstitial fibrosis. Further studies indicated that treatment with mefunidone mitigated the expressions of tumor necrosis factorα (TNFα) and interleukin-1β (IL-1β) in the kidney. The phosphorylation of IKKβ and inhibitor of kappa-B (IκB) and the expression of NOD-like receptor family, pyrin domain containing 3 (NALP3) were also reduced in vivo after treatment with mefunidone. In vitro, peritoneal macrophages were incubated with necrotic cells or lipopolysaccharide in the presence or absence of mefunidone. Mefunidone markedly decreased necrotic cell or LPS induced IL-1β production and LPS induced TNFα production in primary peritoneal macrophages. Furthermore, mefunidone significantly inhibited the phosphorylation of IKKβ/IκB and nuclear transition of NF-κB p65 in peritoneal macrophages stimulated by necrotic cell or lipopolysaccharide. In conclusion, mefunidone serves as a novel anti-inflammatory agent that attenuates UUO-induced renal interstitial inflammation and fibrosis, possibly through suppressing IKKβ phosphorylation.     

Osthole improves an accelerated focal segmental glomerulosclerosis model in the early stage by activating the Nrf2 antioxidant pathway and subsequently inhibiting NF-κB-mediated COX-2 expression and apoptosis

Inflammatory reactions and oxidative stress are implicated in the pathogenesis of focal segmental glomerulosclerosis (FSGS), a common chronic kidney disease with relatively poor prognosis and unsatisfactory treatment regimens. Previously, we showed that osthole, a coumarin compound isolated from the seeds of Cnidium monnieri, can inhibit reactive oxygen species generation, NF-κB activation, and cyclooxygenase-2 expression in lipopolysaccharide-activated macrophages. In this study, we further evaluated its renoprotective effect in a mouse model of accelerated FSGS (acFSGS), featuring early development of proteinuria, followed by impaired renal function, glomerular epithelial cell hyperplasia lesions (a sensitive sign that precedes the development of glomerular sclerosis), periglomerular inflammation, and glomerular hyalinosis/sclerosis. The results show that osthole significantly prevented the development of the acFSGS model in the treated group of mice. The mechanisms involved in the renoprotective effects of osthole on the acFSGS model were mainly a result of an activated Nrf2-mediated antioxidant pathway in the early stage (proteinuria and ischemic collapse of the glomeruli) of acFSGS, followed by a decrease in: (1) NF-κB activation and COX-2 expression as well as PGE₂ production, (2) podocyte injury, and (3) apoptosis. Our data support that targeting the Nrf2 antioxidant pathway may justify osthole being established as a candidate renoprotective compound for FSGS.     

RA-XII exerts anti-oxidant and anti-inflammatory activities on lipopolysaccharide-induced acute renal injury by suppressing NF-κB and MAPKs regulated by HO-1/Nrf2 pathway

Acute kidney injury (AKI) is an abrupt loss of kidney function and severe AKI needs renal replacement therapeutic strategy and has high mortality. RA-XII is a natural cyclopeptide, isolated from the traditional Chinese medicine Rubia yunnanensis, exerting anti-inflammatory and anti-tumor activities. The present study aimed to explore the effects of RA-XII on LPS-induced ACI and the underlying molecular mechanism in TCMK-1?cells in vitro. The results indicated that RA-XII delayed the animal death caused by LPS in mice. The kidney histological changes were markedly attenuated by RA-XII. RA-XII also reduced the serum uric acid, creatinine, BUN and renal 8-OHdG. In addition, RA-XII suppressed LPS-induced oxidative stress in kidney, as evidenced by the up-regulation of superoxide dismutase (SOD), catalase (CAT) and glutathione (GSH) levels, and the down-regulation of malondialdehyde (MDA) levels. Additionally, RA-XII enhanced heme oxygenase (HO)-1 and nuclear factor erythroid 2-related factor 2 (Nrf2) expressions in renal tissue sections. Further, RA-XII reduced the release of pro-inflammatory cytokines, including tumor necrosis factor-alpha (TNF-α), interleukin-1β (IL-1β), IL-6 and IL-18, in renal, which was linked to the inhibition of inhibitor of alpha/nuclear factor kappa B (IκBα/NF-κB) and mitogen-activated protein kinases (MAPKs) pathways. The in vitro study illustrated that the anti-inflammatory effects of RA-XII were partially reversed following Nrf2 and HO-1 inhibition. Together, these findings strongly suggested that RA-XII is a potential agent against acute kidney injury.     

Intermittent Hypoxia-Induced NF-κB and HO-1 Regulation in Human Endothelial EA.hy926 Cells

Intermittent hypoxia (IH) is a hallmark feature in obstructive sleep apnea (OSA) which is increasingly recognized as an independent risk factor for atherosclerosis. Oxidative stress, inflammation, and cell apoptosis are major pathological events initiating or accelerating atherogenesis. This study addressed whether IH would affect these proatherogenic factors in endothelial cells and the mechanistic pathways involved. EA.hy926 cells were exposed to intermittent normoxia or IH for different numbers of cycles (32, 64, or 96). IH exposure time-dependently raised cellular GSSG/GSH ratio, increased production of IL-6 and IL-8, and accelerated cell apoptosis and death, concurrent with activation of NF-κB and inhibition of Nrf2/HO-1 pathways. At 64 cycles, inhibition of NF-κB attenuated IH-induced cellular oxidative stress and accumulation of inflammatory cytokines in cell culture medium but aggravated IH-induced cell apoptosis, while stimulation of HO-1 suppressed IH-induced cellular oxidative stress and cell apoptosis without affecting accumulation of inflammatory cytokines in cell culture medium. We demonstrated that early stage of exposure to IH-induced oxidative and inflammatory stresses leading to acceleration of cell apoptosis via NF-κB and Nrf2/HO-1 pathways in endothelial cells, suggesting the potential mechanisms for IH-induced vascular pathogenesis, in resemblance to OSA.     

Eriodictyol alleviates lipopolysaccharide-triggered oxidative stress and synaptic dysfunctions in BV-2 microglial cells and mouse brain

Oxidative stress takes part in the development of the neurodegenerative disease. Eriodictyol, a flavonoid, commonly presents in citrus fruits, which was well-known for its various bioactivities. The purpose of this study was to investigate the neuroprotective effects of eriodictyol on lipopolysaccharide (LPS)-induced neuroinflammation, oxidative stress, synaptic dysfunctions, and the potential mechanisms involved. We found that eriodictyol explicitly restored LPS-triggered the decrease of cell viability and the mitochondrial potential as well as inflammation responses via mitogen-activated protein kinases (MAPKs) and nuclear factor κB (NF-κB) pathways regulated by reactive oxygen species (ROS). Besides, eriodictyol alleviated LPS-induced oxidative stress via NF-E2-Related factor2/Kelch-like ECH-associated protein 1 (Nrf2/Keap1) pathway in vivo and in vitro. Furthermore, eriodictyol reduced LPS-elicited synaptic dysfunctions via increasing the expression of silent information regulator 1 (Sirt1). Overall, eriodictyol protects LPS-triggered oxidative stress, neuroinflammation, and synaptic dysfunctions partially through MAPKs, NF-κB mediated by ROS, Sirt1, and Nrf2/Keap1 signal pathways, which further supports that eriodictyol is a potentially nutritional preventive strategy for oxidative stress-related neurodegenerative diseases.     

Novel poricoic acids attenuate renal fibrosis through regulating redox signalling and aryl hydrocarbon receptor activation

BackgroundRenal fibrosis is the final manifestation of chronic kidney disease (CKD). Renal fibrosis is largely driven by oxidative stress and inflammation.PurposeThe aim of the current study was to identify novel poricoic acids from Poria cocos and investigated their antifibrotic effects and the underlying mechanism.MethodsIn this study, we identified six novel poricoic acids from Poria cocos and examined their antifibrotic effect using transforming growth factor-β1- (TGF-β1-) induced cultured human kidney proximal tubular epithelial cells (HK-2) and mice with unilateral ureteral obstruction (UUO).ResultsTreatment with six poricoic acids significantly inhibited TGF-β1-induced α-smooth muscle actin expression at both mRNA and protein levels in HK-2 cells. Three compounds with an intact carboxyl group at C-3 position showed a stronger inhibitory effect than that of other three compounds with esterified carboxyl group at the C-3 position. Mechanistically, poricoic acid ZM (PZM) and poricoic acid ZP (PZP) attenuate renal fibrosis through the modulation of redox signalling including the inhibition of proinflammatory nuclear factor kappa B (NF-κB) signalling and its target genes as well as the activation of antioxidative nuclear factor-erythroid-2-related factor 2 (Nrf2) signalling and its downstream target gene in both TGF-β1-induced HK-2 cells and UUO mice. PZM treatment and PZP treatment inhibit the upregulated aryl hydrocarbon receptor and they target the gene expression in UUO mice. Intriguingly, PZM treatment exhibits a stronger inhibitory effect than that of the PZP treatment. Structure–function relationship reveals that the carboxyl group at C-3 position is the most important bioactive function group in secolanostane tetracyclic triterpenoids against renal fibrosis.ConclusionsPZM and PZP attenuated renal fibrosis through the modulation of redox signalling and the aryl hydrocarbon receptor signalling pathway. Our findings will provide several promising leading compounds against renal fibrosis.     

Mindin deficiency alleviates renal fibrosis through inhibiting NF-κB and TGF-β/Smad pathways

Renal fibrosis acts as a clinical predictor in patients with chronic kidney disease and is characterized by excessive extracellular matrix (ECM) accumulation. Our previous study suggested that mindin can function as a mediator for liver steatosis pathogenesis. However, the role of mindin in renal fibrosis remains obscure. Here, tumour necrosis factor (TGF)-β-treated HK-2 cells and global mindin knockout mouse were induced with renal ischaemia reperfusion injury (IRI) to test the relationship between mindin and renal fibrosis. In vitro, mindin overexpression promoted p65—the hub subunit of the NF-κB signalling pathway—translocation from the cytoplasm into the nucleus, resulting in NF-κB pathway activation in TGF-β-treated HK-2 cells. Meanwhile, mindin activated the TGF-β/Smad pathway, thereby causing fibrotic-related protein expression in vitro. Mindin^−/− mice exhibited less kidney lesions than controls, with small renal tubular expansion, inflammatory cell infiltration, as well as collagen accumulation, following renal IRI. Mechanistically, mindin^−/− mice suppressed p65 translocation and deactivated NF-κB pathway. Simultaneously, mindin disruption inhibited the TGF-β/Smad pathway, alleviating the expression of ECM-related proteins. Hence, mindin may be a novel target of renal IRI in the treatment of renal fibrogenesis.     

Pomegranate phytoconstituents blunt the inflammatory cascade in a chemically induced rodent model of hepatocellular carcinogenesis

Liver cancer, predominantly hepatocellular carcinoma (HCC), represents a complex and fatal malignancy driven primarily by oxidative stress and inflammation. Due to dismal prognosis and limited therapeutic intervention, chemoprevention has emerged as a viable approach to reduce the morbidity and mortality of HCC. Pomegranate fruit is a rich source of phytochemicals endowed with potent antioxidant and anti-inflammatory properties. We previously reported that pomegranate phytochemicals inhibit diethylnitrosamine (DENA)-initiated hepatocarcinogenesis in rats though nuclear factor E2-related factor 2 (Nrf2)-mediated antioxidant mechanisms. Since Nrf2 also acts as a key mediator of the nuclear factor-kappaB (NF-κB)-regulated inflammatory pathway, our present study investigated the anti-inflammatory mechanisms of a pomegranate emulsion (PE) during DENA-induced rat hepatocarcinogenesis. Rats were administered with PE (1 or 10 g/kg) 4 weeks before and 18 weeks following DENA initiation. There was a significant increase in hepatic expressions of inducible nitric oxide synthase, 3-nitrotyrosine, heat shock protein 70 and 90, cyclooxygenase-2 and NF-κB in DENA-exposed rat livers. PE dose-dependently suppressed all aforementioned elevated inflammatory markers. A conspicuous finding of this study involves lack of cardiotoxicity of PE as assessed by monitoring cardiac function using noninvasive echocardiography. Our results provide substantial evidence that suppression of the inflammatory cascade through modulation of NF-κB signaling pathway may represent a novel mechanism of liver tumor inhibitory effects of PE against experimental hepatocarcinogenesis. Data presented here coupled with those of our earlier study underline the importance of simultaneously targeting two interconnected molecular circuits, namely, Nrf2-mediated redox signaling and NF-κB-regulated inflammatory pathway, by pomegranate phytoconstituents to achieve chemoprevention of HCC.     

Forsythiaside A Exhibits Anti-inflammatory Effects in LPS-Stimulated BV2 Microglia Cells Through Activation of Nrf2/HO-1 Signaling Pathway

Inflammation and oxidative stress have been reported to play critical roles in the pathogenesis of neurodegenerative disease. Forsythiaside A, a phenylethanoside product isolated from air-dried fruits of Forsythia suspensa, has been reported to have anti-inflammatory and antioxidant effects. In this study, the anti-inflammatory effects of forsythiaside A on LPS-stimulated BV2 microglia cells and primary microglia cells were investigated. The production of inflammatory mediators TNF-α, IL-1β, NO and PGE₂ were detected in this study. NF-κB, nuclear factor-erythroid 2-related factor 2 (Nrf2), heme oxygenase-1 (HO-1) expression were detected by western blot analysis. Our results showed that forsythiaside A significantly inhibited LPS-induced inflammatory mediators TNF-α, IL-1β, NO and PGE₂ production. LPS-induced NF-κB activation was suppressed by forsythiaside A. Furthermore, forsythiaside A was found to up-regulate the expression of Nrf2 and HO-1. In conclusion, this study demonstrates that forsythiaside A inhibits LPS-induced inflammatory responses in BV2 microglia cells and primary microglia cells through inhibition of NF-κB activation and activation of Nrf2/HO-1 signaling pathway.