Xanthohumol protect against acetaminophen-induced hepatotoxicity via Nrf2 activation through the AMPK/Akt/GSK3ß pathway.

OBJECTIVE: Acetaminophen (APAP) is one of the world's popular and safe painkillers, and overdose can cause severe liver damage and even acute liver failure. The effect and mechanism of the xanthohumol on acetaminophen-induced hepatotoxicity remains unclear. METHODS: The hepatoprotective effects of xanthohumol were studied using APAP-induced HepG2 cells and acute liver injury of mouse, seperately. RESULTS: In vitro, xanthohumol inhibited H2O2- and acetaminophen-induced cytotoxicity and oxidative stress. Xanthohumol up-regulated the expression of Nrf2. Further mechanistic studies showed that xanthohumol triggered Nrf2 activation via the AMPK/Akt/GSK3ß pathway to exert a cytoprotective effect. In vivo, xanthohumol significantly ameliorated acetaminophen-induced mortality, the elevation of ALT and AST, GSH depletion, MDA formation and histopathological changes. Xanthohumol effectively suppressed the phosphorylation and mitochondrial translocation of JNK, mitochondrial translocation of Bax, the activation o cytochrome c, AIF secretion and Caspase-3. In vivo, xanthohumol increased Nrf2 nuclear transcription and AMPK, Akt and GSK3ß phosphorylation in vivo. In addition, whether xanthohumol protected against acetaminophen-induced liver injury in Nrf2 knockout mice has not been illustated. CONCLUSION: Thus, xanthohumol exerted a hepatoprotective effect by inhibiting oxidative stress and mitochondrial dysfunction through the AMPK/Akt/GSK3ß/Nrf2 antioxidant pathway.

Daphnetin ameliorates PM2.5-induced airway inflammation by inhibiting NLRP3 inflammasome-mediated pyroptosis in CS-exposed mice.

Epidemiologic studies have shown that fine particulate matter 2.5 (PM2.5) exaggerates airway inflammation associated with acute exacerbation of chronic obstructive pulmonary disease (AECOPD). Daphnetin (Daph) is a natural compound with a variety of biological activities. At present, there are limited data on whether Daph can protect against cigarette smoke (CS)-induced chronic obstructive pulmonary disease (COPD) and PM2.5-CS-induced AECOPD. Therefore, this study systematically evaluated the effects of Daph on CS-induced COPD and PM2.5-CS-induced AECOPD and determined its mechanism of action. First, in vitro studies showed that PM2.5 exacerbated cytotoxicity and NLRP3 inflammasome-mediated pyroptosis induced by low-dose cigarette smoke extracts (CSE). However, the effect was reversed by si-NLRP3 and MCC950. Similar results were obtained in PM2.5-CS-induced AECOPD mice. The results of the mechanistic studies suggested that blocking NLRP3 abolished PM2.5 combined with cigarette induced cytotoxicity, lung damage, NLRP3 inflammasome activation and pyroptosis in vitro and in vivo. Second, Daph suppressed the expression of NLRP3 inflammasome and pyroptosis in BEAS-2B cells. Third, Daph significantly protected against CS-induced COPD and PM2.5-CS-induced AECOPD by inhibiting the NLRP3 inflammasome and pyroptosis in mice. Our findings identified the NLRP3 inflammasome as a critical contributor to PM2.5-CS-induced airway inflammation, and Daph as a negative regulator of NLRP3-mediated pyroptosis, which has implications for the pathophysiology of AECOPD.

Activation of Nrf2 signalling pathway by tectoridin protects against ferroptosis in particulate matter-induced lung injury.

BACKGROUND AND PURPOSE: Our previous research showed that ferroptosis plays a crucial role in the pathophysiology of PM2.5-induced lung injury. The present study aimed to investigate the protective role of the Nrf2 signalling pathway and its bioactive molecule tectoridin in PM2.5-induced lung injury by regulating ferroptosis. EXPERIMENTAL APPROACH: We examined the regulatory effect of Nrf2 on ferroptosis in PM2.5-induced lung injury and Beas-2b cells using Nrf2-knockout (KO) mice and Nrf2 siRNA transfection. The effects and underlying mechanisms of tectoridin on PM2.5-induced lung injury were evaluated in vitro and in vivo. KEY RESULTS: Nrf2 deletion increased iron accumulation and ferroptosis-related protein expression in vivo and vitro, further exacerbating lung injury and cell death in response to PM2.5 exposure. Tectoridin activated Nrf2 target genes and ameliorated cell death caused by PM2.5. In addition, tectoridin prevented lipid peroxidation, iron accumulation and ferroptosis in vitro, but in siNrf2-treated cells, these effects almost disappeared. In addition, tectoridin effectively mitigated PM2.5-induced respiratory system damage, as evaluated by HE, PAS, and inflammatory factors. Tectoridin also augmented the antioxidative Nrf2 signalling pathway and prevented changes in ferroptosis-related morphological and biochemical indicators, including MDA levels, GSH depletion and GPX4 and xCT downregulation, in PM2.5-induced lung injury. However, the effects of tectoridin on ferroptosis and respiratory injury were almost abolished in Nrf2-KO mice. CONCLUSION AND IMPLICATIONS: Our data proposed the protective effect of Nrf2 activation on PM2.5-induced lung injury by inhibiting ferroptosis-mediated lipid peroxidation and highlight the potential of tectoridin as a PM2.5-induced lung injury treatment.

PM2.5 increases susceptibility to acute exacerbation of COPD via NOX4/Nrf2 redox imbalance-mediated mitophagy.

The increasing abundance of fine particulate matter (PM2.5) in the environment has increased susceptibility to acute exacerbation of COPD (AECOPD). During PM2.5 exposure, excessive reactive oxygen species (ROS) production triggers a redox imbalance, which contributes to damage to organelles and disruption of homeostasis. At present, there are limited data on whether NOX4/Nrf2 redox imbalance increases susceptibility to acute exacerbation of COPD (AECOPD), and the underlying mechanism is unclear. Therefore, the current study was aimed to evaluate the role of NOX4/Nrf2 redox balance on AECOPD induced by PM2.5-CS-exposure. Here, we report that PM2.5 exacerbates cytotoxicity by enhancing NOX4/Nrf2 redox imbalance-mediated mitophagy. First, exposure to a low-dose of PM2.5 (200 µg/ml) significantly exacerbated oxidative stress and mitochondrial damage by increasing the ROS overproduction, enhancing the excessive NOX4/Nrf2 redox imbalance, decreasing the mitochondrial membrane potential (MMP), and enhancing the mitochondrial fragmentation that were caused by a low-dose of CSE (2.5%). Second, coexposure to PM2.5 and CSE (PM2.5-CSE) induced excessive mitophagy. Third, PM2.5 exacerbated CS-induced COPD, as shown by excessive inflammatory cell infiltration, inflammatory cytokine production and mucus hypersecretion, goblet cell hyperplasia, NOX4/Nrf2 redox imbalance, and mitophagy, these effects triggered excessive ROS production and mitochondrial damage in mice. Mechanistically, PM2.5-CS-induced excessive levels of mitophagy by triggering redox imbalance, leading to greater cytotoxicity and AECOPD; however, reestablishing the NOX4/Nrf2 redox balance via NOX4 blockade or mitochondria-specific ROS inhibitor treatment alleviated this cytotoxicity and ameliorated AECOPD. PM2.5 may exacerbate NOX4/Nrf2 redox imbalance and subsequently enhance mitophagy by increasing the ROS and mito-ROS levels, thereby increasing susceptibility to AECOPD.

Leonurine alleviates ferroptosis in cisplatin-induced acute kidney injury by activating the Nrf2 signalling pathway.

BACKGROUND AND PURPOSE: Evidence indicates that ferroptosis plays a key role in acute kidney injury induced by cisplatin. The Nrf2/NRF2 pathway regulates oxidative stress, lipid peroxidation and positively regulates cisplatin-induced acute kidney injury, but its effect along with the alkaloid leonurine, found in motherwort, on ferroptosis after such acute kidney injury remains unclear. EXPERIMENTAL APPROACH: The anti-ferroptotic effects of Nrf2 and leonurine were assessed in a mouse model of cisplatin-induced acute kidney injury. In vitro, the effects of leonurine on erastin- and RSL3-induced HK-2 human PTEC ferroptosis were examined. KEY RESULTS: Nrf2 deletion induced ferroptosis-related protein expression and iron accumulation in vivo, aggravating cisplatin-induced acute kidney injury. Leonurine activated Nrf2 and prevented iron accumulation, lipid peroxidation and ferroptosis in vitro, being abolished in siNrf2-treated cells. Moreover, leonurine potently inhibited cisplatin-induced renal damage, as assessed by of serum creatinine, blood urea nitrogen, kidney injury molecule-1 and NGAL. Importantly, leonurine activated the Nrf2 antioxidative pathway and preventing changes in ferroptosis-related morphological and biochemical indicators, malondialdehyde level, SOD and GSH depletion, and GPX4 and xCT down-regulation, in cisplatin-induced acute kidney injury. Nrf2 KO mice were more susceptible to ferroptosis after cisplatin-induced acute kidney injury than control mice. The protective effects of leonurine on acute kidney injury and ferroptosis were largely abolished in Nrf2 KO mice. CONCLUSION AND IMPLICATIONS: These data suggest that renal protective effects of Nrf2 activation on cisplatin-induced acute kidney injury are achieved, at least partially, by inhibiting lipid peroxide-mediated ferroptosis, highlighting the potential of leonurine in acute kidney injury treatment.

Amentoflavone Ameliorates Carrageenan-Induced Pleurisy and Lung Injury by Inhibiting the NF-κB/STAT3 Pathways via Nrf2 Activation.

Many natural flavonoids can activate nuclear factor erythroid 2-related factor 2 (Nrf2), which is pivotal for alleviating various diseases related to inflammation and oxidative stress, including pleurisy. Amentoflavone (AMF), a biflavonoid extracted from many plants, has some beneficial bioactivities, especially anti-inflammatory and antioxidative activities. We aimed to investigate whether AMF protects against pleurisy and lung injury induced by carrageenan (Car) by activating Nrf2. Pleurisy was induced in wild-type (WT) and Nrf2-deficient (Nrf2-/-) mice. Then, pleural exudate and lung tissue were collected for biochemical analysis, H&E staining, immunocytochemistry and western blotting. Our results indicated that AMF protected against Car-induced pleurisy and lung injury. The Wright-Giemsa and H&E staining results showed that AMF alleviated inflammatory effusion and pathological injury. In addition, AMF decreased SOD and GSH depletion and MDA and MPO generation in the lung tissue of mice. AMF activated Nrf2 through keap-1 dissociation and subsequently increased heme oxygenase-1 (HO-1), NAD(P)H-quinone oxidoreductase 1 (NQO1), and γ-glutamylcysteine ligase (GCL) levels. Furthermore, AMF suppressed IL-1ß and TNF-α levels and increased IL-10 levels in pleural exudate by blocking the proinflammatory NF-κB, signal transducer and activator of transcription 3 (STAT3) and extracellular signal-regulated kinase (ERK) pathways induced by Car. However, these antioxidative and anti-inflammatory effects were weakened in Nrf2-/- mice. Moreover, AMF failed to suppress the NF-κB and STAT3 pathways in Nrf2-/- mice. Our results demonstrated that AMF exerted anti-inflammatory and antioxidative effects in Car-induced lung injury and pleurisy in a Nrf2-dependent manner.

Daphnetin ameliorated GM-induced renal injury through the suppression of oxidative stress and apoptosis in mice.

Gentamicin (GM), an aminoglycoside antibiotic, is one of the most effective drugs used in the treatment of various types of bacterial infections, but the major adverse effect and drug-induced nephrotoxicity of GM limit its clinical applications. Daphnetin (Daph) is a natural coumarin derivative that is clinically used to treat rheumatoid arthritis and coagulopathy and exhibits antioxidant effects. However, the effect of Daph on GM-induced nephrotoxicity has not yet been elucidated. This study investigated Daph-mediated protection against GM-induced nephrotoxicity in mice and explored the underlying mechanisms of GM-induced renal dysfunction in mice. We found that Daph treatment significantly reduced GM-induced nephrotoxicity mainly by ameliorating renal injury in mice and attenuating cell damage in vitro. Mechanistically, we found that Daph upregulated the expression level of Nrf2 and its regulated antioxidant enzymes HO-1, NQO1, GCLC and GCLM in vivo and in vitro. GM upregulated the expression levels of NOX4, cleaved Caspase-3 and p53 and the BAX/BCL2 ratio in vivo to stimulate oxidative stress and apoptosis. However, Daph treatment significantly improved the oxidative stress and apoptosis caused by GM, thereby exerting antioxidative and antiapoptotic effects. Our study was the first to suggest that the natural product Daph protects against GM-induced nephrotoxicity through the activation of Nrf2 which regulates oxidative stress and apoptosis. The pharmacological activation of Nrf2 may be useful as a novel therapy to prevent renal injury.

Hyperoside relieves particulate matter-induced lung injury by inhibiting AMPK/mTOR-mediated autophagy deregulation.

Autophagy-mediated cell death plays a critical role in the pathogenesis of PMs-induced lung injury. Hyperoside (Hyp), a flavonoid glycosides, is known to exert protective effects on many diseases by inhibiting autophagic activity. The current study aimed to explore the protective effect and mechanism of Hyp against PMs-induced lung injury in PM2.5 challenged Beas-2b cells in vitro and BALB/C mice in vivo. In vitro, we found that the organic solvent-extractable fraction of SRM1649b (O-PMs) caused more severe cytotoxicity in Beas-2b cells than the water solvent-extractable fraction of SRM1649b (W-PMs). O-PMs treatment dose-dependently upregulated the expression of autophagy markers (beclin-1, p62, atg3 and LC3II) and apoptotic proteins. This cytotoxicity of O-PMs was attenuated by Hyp pretreatment in parallel with downregulation of the expression of autophagy markers, apoptotic proteins, and p-AMPK and upregulation of p-mTOR expression. Notably, the therapeutic effect of Hyp was attenuated by pretreated with AICAR (an AMPK inducer), but enhanced by CC and 3-MA treatment. In vivo, Hyp reduced pathological lung injury and decreased the levels of PMs-induced inflammatory cytokines (TNF-α and IL-6), and the number of total cells in the BALF by inhibiting AMPK/mTOR signaling. Furthermore, cotreatment with AICAR (500 mg/kg) reduced but did not abrogate the pulmonary protective effect of Hyp. These findings indicate that Hyp protects against PMs-induced lung injury by suppressing autophagy deregulation and apoptosis through regulation of the AMPK/mTOR pathway.

Daphnetin triggers ROS-induced cell death and induces cytoprotective autophagy by modulating the AMPK/Akt/mTOR pathway in ovarian cancer.

BACKGROUND: Ovarian cancer is one of the most common gynecological malignancies in the world. Daphnetin (Daph) was previously reported to possess antitumor potential, but its potential and molecular mechanisms in ovarian cancer remain poorly understood. PURPOSE: In the current study, we aimed to explore the antitumor effect and detailed mechanisms of Daph in ovarian cancer cells. METHODS: The cytotoxic effect of Daph on ovarian cells was determined in vitro and in vivo. Cell growth, proliferation, apoptosis and ROS generation were measured by CCK8 assays, colony formation assays and flow cytometry. Western blotting was used to evaluate the related signal proteins. Immunofluorescence and transmission electron microscopy were used to evaluate markers of autophagy and autophagic flux. The antitumor effects were observed in the A2780 xenograft model. Moreover, Daph-induced autophagy was observed by enhanced LC3-II accumulation and endogenous LC3 puncta, and an autophagy inhibitor further enhanced the antitumor efficacy of Daph, which indicated that the cytoprotective role of autophagy in ovarian cancer. RESULTS: We found that Daph exhibited antitumor effects by inducing ROS-dependent apoptosis in ovarian cancer, which could be reversed by N-acetyl cysteine (NAC). The AMPK/Akt/mTOR pathway was involved in Daph-mediated cytoprotective autophagy, and when Daph-mediated the expression level of AMPK and autophagy were blocked, there was robust inhibition of cell proliferation and induction of apoptosis. In addition, in the A2780 xenograft model, combined treatment with Daph and an autophagy inhibitor showed obvious synergetic effects on the inhibition of cell viability and promotion of apoptosis, without any side effects. CONCLUSION: Our results suggest that Daph triggers ROS-induced cell apoptosis and induces cytoprotective autophagy by modulating the AMPK/Akt/mTOR pathway. Moreover, the combination of Daph and autophagy inhibitor may be a potential therapeutic strategy for ovarian cancer.

Daphnetin Attenuated Cisplatin-Induced Acute Nephrotoxicity With Enhancing Antitumor Activity of Cisplatin by Upregulating SIRT1/SIRT6-Nrf2 Pathway.

Cisplatin (CDDP) is a widely used drug for cancer treatment that exhibits major side effects in normal tissues, such as nephrotoxicity in kidneys. The Nrf2 signaling pathway, a regulator of mitochondrial dysfunction, oxidative stress and inflammation, is a potential therapeutic target in CDDP-induced nephrotoxicity. We explored the underlying mechanisms in wild-type (WT) and Nrf2-/- mice on CDDP-induced renal dysfunction in vivo. We found that Nrf2 deficiency aggravated CDDP-induced nephrotoxicity, and Daph treatment significantly ameliorated the renal injury characterized by biochemical markers in WT mice and reduced the CDDP-induced cell damage. In terms of the mechanism, Daph upregulated the SIRT1 and SIRT6 expression in vivo and in vitro. Furthermore, Daph inhibited the expression level of NOX4, whereas it activated Nrf2 translocation and antioxidant enzymes HO-1 and NQO1, and alleviated oxidative stress and mitochondrial dysfunction. Moreover, Daph suppressed CDDP-induced NF-κB and MAPK inflammation pathways, as well as p53 and cleaved caspase-3 apoptosis pathways. Notably, the protective effects of Daph in WT mice were completely abrogated in Nrf2-/- mice. Moreover, Daph enhanced, rather than attenuated, the tumoricidal effect of CDDP.

The role of Nrf2 in acute kidney injury: Novel molecular mechanisms and therapeutic approaches.

Acute kidney injury (AKI) is a common clinical syndrome that is related to high morbidity and mortality. Oxidative stress, including the production of reactive oxygen species (ROS), appears to be the main element in the occurrence of AKI and the cause of the progression of chronic kidney disease (CKD) into end-stage renal disease (ESRD). Nuclear factor erythroid 2 related factor 2 (Nrf2) is a significant regulator of redox balance that has been shown to improve kidney disease by eliminating ROS. To date, researchers have found that the use of Nrf2-activated compounds can effectively reduce ROS, thereby preventing or retarding the progression of various types of AKI. In this review, we summarized the molecular mechanisms of Nrf2 and ROS in AKI and described the latest findings on the therapeutic potential of Nrf2 activators in various types of AKI.

Pterostilbene prevents LPS-induced early pulmonary fibrosis by suppressing oxidative stress, inflammation and apoptosis in vivo.

Early pulmonary fibrosis after acute lung injury leads to poor prognosis and high mortality. Pterostilbene (Pts), a bioactive component in blueberries, possesses anti-inflammatory, antioxidative and antifibrotic properties. However, the effects of Pts on lipopolysaccharide (LPS)-induced pulmonary fibrosis are still unknown. In our study, the Pts group showed lower lung injury and fibrosis scores, and lower levels of hydroxyproline and protein (collagen I and transforming growth factor-ß) than the scores and levels in mice treated with LPS. MMP-1 was the degrading enzyme of collagen I and LPS caused the inhibition of MMP-1, disturbing the degradation of collagen. Additionally, Pts remarkably reversed the LPS-induced inhibition of interleukin-10 and the release of tumor necrosis factor-α, interleukin-6 and interleukin-1ß. In terms of cellular pathways, Pts treatment ameliorated LPS-activated nuclear factor kappa B (NF-κB) and NOD-like receptor NLRP3 signaling. Besides, LPS-induced low levels of A20 could be activated by Pts. In addition, Pts treatment reversed the high levels of Caspase-3, poly ADP-ribose polymerase (PARP) and Bcl2-associated X protein (Bax) expression and the low levels of B cell lymphoma/lewkmia-2 (Bcl2) that had been induced by LPS. Moreover, oxidative stress is also involved in the pathogenesis of fibrosis. Our findings indicate that LPS injection triggered the production of myeloperoxidase (MPO) and malondialdehyde (MDA) and the depletion of superoxide dismutase (SOD) and glutathione (GSH), and that these effects were notably reversed by treatment with Pts. In addition, Pts induced the dissociation of Kelch-like epichlorohydrin-associated protein-1 (Keap-1) and NF-E2 related factor-2 (Nrf2) and the activation of downstream genes (heme oxygenase-1, NAD(P)H:quinine oxidoreductase, glutamate-cysteine ligase catalytic subunit and glutamate-cysteine ligase modifier). In conclusion, oxidative stress, apoptosis and inflammation are involved in early pulmonary fibrosis and Pts exerts a protective effect by activating Keap-1/Nrf2, inhibiting caspase-dependent A20/NF-κB and NLRP3 signaling pathways.

Isoorientin Attenuates Cisplatin-Induced Nephrotoxicity Through the Inhibition of Oxidative Stress and Apoptosis via Activating the SIRT1/SIRT6/Nrf-2 Pathway.

Cisplatin (CDDP) is a widely used chemotherapeutic agent for various solid tumors, but its severe side effects, particularly nephrotoxicity, limit its clinical application. Isoorientin (Iso) is a flavonoid-like compound known to have antioxidant effects. As oxidative injury plays a vital role in CDDP-induced acute kidney injury (AKI), the effect of Iso on CDDP-induced nephrotoxicity has not yet been researched. We assessed the effects of Iso against CDDP-induced nephrotoxicity in vitro using mTEC cells and further explored the mechanisms underlying CDDP-induced renal dysfunction in vivo in WT and Nrf2-/- mice. The results showed that Iso treatment significantly reduced CDDP-induced nephrotoxicity via attenuating cell damage in vitro and via ameliorating renal injury, as determined by biochemical markers, in mice. The molecular mechanism underlying this protection was also investigated. Iso up-regulated the expression levels of SIRT1 and SIRT6 in vivo and in vitro. In addition, Iso activated Nrf2 translocation and the expression levels of its downstream antioxidant enzymes, such as HO-1 and NQO1, whereas it inhibited the expression level of NOX4, thus decreasing oxidative stress. Notably, the protective effects of Iso observed in WT mice were completely abolished in Nrf2-/- mice. Collectively, these data indicate that the protective effect of Iso on CDDP-induced nephrotoxicity by SIRT1- and SIRT6-mediated Nrf2 activation regulates oxidative stress, inflammation and apoptosis. The absence of Nrf2 exacerbates CDDP-induced renal damage, and the pharmacological activation of Nrf2 may represent a novel therapy to prevent kidney injury.

Farrerol Attenuates Cisplatin-Induced Nephrotoxicity by Inhibiting the Reactive Oxygen Species-Mediated Oxidation, Inflammation, and Apoptotic Signaling Pathways.

Cisplatin is a chemotherapy drug that is often used in clinical practice, but its frequent use often leads to nephrotoxicity. Therefore, we urgently need a drug that reduces the nephrotoxicity induced by cisplatin. Farrerol reportedly has antioxidant potential, but its renal protective effects and potential mechanisms remain unclear. In this study, we used both cell and mouse models to determine the mechanism of farrerol in cisplatin-induced nephrotoxicity. The in vitro experiments revealed that farrerol improved cisplatin-induced nephrotoxicity and reactive oxygen species (ROS) production via nuclear factor erythrocyte 2-related factor 2 (Nrf2) activation. Moreover, farrerol effectively activated Nrf2 and subsequently increased the expression of Nrf2-targeted antioxidant enzymes, including heme oxygenase-1 (HO-1) and NAD(P)H quinone oxidoreductase-1 (NQO1), but inhibited Kelch-like ECH-associated protein 1 (Keap1) and NADPH oxidase type 4 (NOX4). Furthermore, farrerol attenuated the phosphorylation of C-Jun N-terminal kinase (JNK), extracellular signal-regulated kinase (ERK), and p38 mitogen-activated protein kinase (p38); the activation of phosphorylated nuclear factor-κB (p-NF-κB) and nucleotide-binding domain (NOD)-like receptor protein 3 (NLRP3); and the expression of phosphorylated p53 (p-p53), Bax, and cleaved caspase-3. In vivo, farrerol significantly improved cisplatin-induced renal damage, as demonstrated by the recovery of blood urea nitrogen (BUN), serum creatinine (SCr), kidney injury molecule-1 (KIM-1), neutrophil gelatinase-associated lipocalin (NGAL), and pathological damage. Moreover, farrerol inhibited inflammatory and apoptotic protein expression in vivo. Notably, farrerol exerted slight protection in Nrf2-knockout mice compared with wild-type mice. These findings indicate that farrerol can effectively activate Nrf2 and can serve as a therapeutic target in the treatment of acute kidney injury (AKI).

Oridonin Sensitizes Cisplatin-Induced Apoptosis via AMPK/Akt/mTOR-Dependent Autophagosome Accumulation in A549 Cells.

AMPK-mediated autophagy and Akt/mTOR pathways play important roles in current cancer treatments. Oridonin (Ori), an ent-kaurane diterpenoid isolated from Isodon rubescens, exerts extensive anti-tumor potential and controversial effects on autophagy. In this study, we investigated the effect of Ori on the autophagy, apoptosis, and AMPK/Akt/mTOR pathways and determined whether Ori was related to the increased cisplatin sensitivity observed in A549 cells. First, we found that Ori suppressed Akt/mTOR, Bcl2 and autophagy flux with enhanced levels of Atg3, P62, and LC3II, which was also shown as the accumulation of autophagosomes. AMPK and pro-apoptotic proteins (caspase3, Bax, and PARP) were activated in Ori-treated cells. With the pretreatment of compound c (AMPK inhibitor), the activation of autophagosomes, apoptosis and the inhibition of Akt/mTOR pathways induced by Ori were all reversed. The Ori-activated apoptosis-related markers mentioned previously and the cell-killing effect were restrained by 3-MA (inhibitor of autophagosomes) treatment. Therefore, we hypothesized that the Ori-induced pro-apoptotic effect was mediated by AMPK/Akt/mTOR-dependent accumulation of impaired autophagosomes. Furthermore, Ori could increase the sensitivity of cisplatin through its increased cell-killing, autophagy-suppressing and apoptosis-inducing activities. In addition to sensitizing cisplatin, Ori also alleviated cisplatin-induced acute renal injury in vivo, manifested as depleted BUN, CRE, kidney index, and weight loss compared to the cisplatin group. In summary, apart from its protective effect on cisplatin-induced nephrotoxicity, Ori enhanced cisplatin sensitivity via its pro-apoptotic activity mediated by AMPK/Akt/mTOR-dependent autophagosome activation, which may be a potential therapeutic target for non-small cell lung cancer.

Isoorientin Ameliorates APAP-Induced Hepatotoxicity via Activation Nrf2 Antioxidative Pathway: The Involvement of AMPK/Akt/GSK3ß.

Oxidative stress has been highlighted as therapeutic targets for acetaminophen (APAP)-induced hepatotoxicity. Isoorientin (Iso), a well-known flavonoid-like compound, has been shown to have antioxidant potential. However, the effect of Iso on APAP-induced liver injury has not yet been elucidated. The present study investigated the hepatoprotective effect of Iso and its underlying mechanism. C57BL/6J mice were used to evaluate the hepatoprotective effect of Iso in vivo and HepG2 cells were utilized to further decipher the mechanisms of Iso -induced Nrf2 activation. We found that Iso treatment significantly reduced APAP-induced hepatotoxicity by reducing the lethality, histopathological liver changes, and alanine transaminase (ALT) and aspartate aminotransferase (AST) levels in serum. These effects were accompanied by decreased malondialdehyde (MDA) formation and myeloperoxidase level (MPO), and by decreased superoxide dismutase (SOD) and glutathione (GSH) depletion. Moreover, Iso induced Nrf2 activation and translocation as well as upstream AMPK/Akt/GSK3ß activation. Furthermore, Iso effectively alleviated mitochondrial dysfunction by reducing c-jun N-terminal kinase phosphorylation and translocation, Bax mitochondrial translocation, and apoptosis-inducing factor and cytochrome c release. Further mechanistic investigations revealed that the activation of Nrf2 by Iso via the AMPK/Akt/GSK3ß pathway contributed to the hepatoprotective activity of Iso in vitro. In addition, the Iso-mediated inhibition of APAP-induced the lethality, histopathological changes and mitochondrial dysfunction observed in WT mice was nearly absent in Nrf2-/- mice. In summary, Iso ameliorated APAP-induced hepatotoxicity by activating Nrf2 via the AMPK/Akt/GSK3ß pathway.

Pterostilbene Reduces Acetaminophen-Induced Liver Injury by Activating the Nrf2 Antioxidative Defense System via the AMPK/Akt/GSK3ß Pathway.

BACKGROUND/AIMS: Pterostilbene (Pts), a natural dimethylated analog of resveratrol from blueberries, exerts antioxidative and anti-apoptotic effects in various diseases. This study aims to investigate the protective effects and mechanism of Pts against acetaminophen (APAP)-induced hepatotoxicity in vivo. METHODS: C57BL/6 mice were treated with APAP or APAP+Pts. HepG2 cells were used to further explore the underlying mechanisms in vitro. The effects of Pts on hepatotoxicity were measured by commercial kits, Hematoxylin and Eosin (H&E) straining, TUNEL assay, Western blot analysis, and Flow cytometry assay. RESULTS: In vivo, Pts treatment effectively protected against APAP-induced severe liver injury by decreasing the lethality rate, the serum alanine transaminase (ALT) and aspartate aminotransferase (AST) levels, liver histological injury, liver malondialdehyde (MDA) formation and myeloperoxidase (MPO) levels and by increasing liver glutathione (GSH) and superoxide dismutase (SOD) levels. Moreover, in Pts-treated mice, the nuclear factor-erythroid 2-related factor 2 (Nrf2)/heme oxygenase-1 (HO-1) pathway was activated; however, APAP-induced c-Jun NH2-terminal kinase (JNK) activation, mitochondrial Bcl-2 Associated X Protein (Bax) translocation, apoptosis-inducing factor (AIF) levels and cytochrome c release were attenuated. In vitro, Pts was found to reverse hydrogen peroxide (H2O2) -induced cytotoxicity, reactive oxygen species (ROS) production and apoptosis that depended on Nrf2 activation. Moreover, Pts induced a dose-dependent increase in the phosphorylation of AMP-activated protein kinase (AMPK), serine/threonine kinase (Akt), and glycogen synthase kinase 3ß (GSK3ß) in HepG2 cells. Moreover, Pts protect against APAP or H2O2-induced toxicity were effectively attenuated or abolished in HepG2 Nrf2-/- cells and Nrf2-/- mice. CONCLUSION: Our data suggest that Pts protects against APAP-induced toxicity by activating Nrf2 via the AMPK/Akt/GSK3ß pathway.

Daphnetin alleviates lipopolysaccharide/d-galactosamine-induced acute liver failure via the inhibition of NLRP3, MAPK and NF-κB, and the induction of autophagy.

Acute liver failure (ALF), an inflammation-mediated hepatocellular injury process, is a life-threatening and fatal clinical syndrome. Daphnetin (Daph) has been reported to exhibit various pharmacological activities, particularly its antiinflammatory property. The present study was designed to evaluate the protective effects and underlying mechanisms of Daph against lipopolysaccharide and d-galactosamine (LPS/GalN)-induced ALF in mice. Our findings suggested that Daph treatment efficiently protected against LPS/GalN-induced ALF by lessening the lethality, decreasing the alanine transaminase (ALT) and aspartate aminotransferase (AST) levels, tumor necrosis factor (TNF)-α, interleukin (IL)-1ß, and IL-6 secretion, malondialdehyde (MDA) formation and myeloperoxidase (MPO) level, inhibiting nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2) protein expression, and increasing the glutathione (GSH) and superoxide dismutase (SOD) contents. Moreover, Daph treatment effectively inhibited LPS/GalN-induced nucleotide-binding domain (NOD)-like receptor protein 3 (NLRP3), mitogen-activated protein kinase (MAPK) and nuclear factor-kappa B (NF-κB) signaling pathway activation, and significantly induced autophagy activation by enhancing the level of pro-autophagy proteins expression. Taken together, these findings suggested that Daph plays a pivotal role in liver protection by suppressing inflammatory responses which may be closely associated with the inhibition of NLRP3 inflammasome, MAPK and NF-κB activation, as well as the induction of autophagy.