Salvianolic acid A protects RPE cells against oxidative stress through activation of Nrf2/HO-1 signaling

Activation of Akt by SC79 protects myocardiocytes from oxygen and glucose deprivation (OGD)/re-oxygenation

SC79 is a novel Akt activator. The current study tested its potential effect against oxygen and glucose deprivation (OGD)/re-oxygenation-induced myocardial cell death. We showed that SC79 activated Akt and protected H9c2 myocardial cells and primary murine myocardiocytes from OGD/re-oxygenation. Reversely, Akt inhibitor MK-2206 or Akt1 shRNA knockdown almost completely abolished SC79-mediated myocardial cytoprotection. SC79 treatment in H9c2 cells inhibited OGD/re-oxygenation-induced programmed necrosis pathway, evidenced by mitochondrial depolarization and cyclophilin D-p53-ANT-1 (adenine nucleotide translocator 1) association. Further, SC79 activated Akt downstream NF-E2-related factor 2 (NRF2) signaling to suppress OGD/re-oxygenation-induced reactive oxygen species (ROS) production. Reversely, NRF2 shRNA knockdown in H9c2 cells largely attenuated SC79-induced ROS scavenging ability and cytoprotection against OGD/re-oxygenation. Together, we conclude that activation of Akt by SC79 protects myocardial cells from OGD/re-oxygenation.

WITHDRAWN: JIP3 deficiency protects mice from high fat diet-induced liver injury

This article has been withdrawn at the request of the author(s) and/or editor. The Publisher apologizes for any inconvenience this may cause. The full Elsevier Policy on Article Withdrawal can be found at https://www.elsevier.com/about/our-business/policies/article-withdrawal.

MIND4-17 protects retinal pigment epithelium cells and retinal ganglion cells from UV

Nrf2 activation would efficiently protect retinal cells from UV radiation (UVR). Recent studies have developed a Nrf2-targeting thiazole-containing compound MIND4-17, which activates Nrf2 through blocking its association with Keap1. In the current study, we demonstrated that pretreatment with MIND4-17 efficiently protected retinal pigment epithelium (RPE) cells (RPEs) and retinal ganglion cells (RGCs) from UVR. UVR-induced apoptosis in the retinal cells was also largely attenuated by MIND4-17 pretreatment. MIND4-17 presumably separated Nrf2 from Keap1, allowing its stabilization and accumulation in retinal cells, which then translocated to cell nuclei and promoted transcription of ARE-dependent anti-oxidant genes, including HO1, NQO1 and GCLM. Significantly, shRNA-mediated knockdown of Nrf2 almost completely abolished MIND4-17-induced cytoprotection against UVR. Further studies showed that MIND4-17 largely ameliorated UVR-induced ROS production, lipid peroxidation and DNA damages in RPEs and RGCs. Together, MIND4-17 protects retinal cells from UVR by activating Nrf2 signaling.

MHY1485 ameliorates UV-induced skin cell damages via activating mTOR-Nrf2 signaling

Ultra Violet (UV)-caused skin cell damage is a main cause of skin cancer. Here, we studied the activity of MHY1485, a mTOR activator, in UV-treated skin cells. In primary human skin keratinocytes, HaCaT keratinocytes and human skin fibroblasts, MHY1485 ameliorated UV-induced cell death and apoptosis. mTOR activation is required for MHY1485-induced above cytoprotective actions. mTOR kinase inhibitors (OSI-027, AZD-8055 and AZD-2014) or mTOR shRNA knockdown almost abolished MHY1485-induced cytoprotection. Further, MHY1485 treatment in skin cells activated mTOR downstream NF-E2-related factor 2 (Nrf2) signaling, causing Nrf2 Ser-40 phosphorylation, stabilization/upregulation and nuclear translocation, as well as mRNA expression of Nrf2-dictated genes. Contrarily, Nrf2 knockdown or S40T mutation almost nullified MHY1485-induced cytoprotection. MHY1485 suppressed UV-induced reactive oxygen species production and DNA single strand breaks in skin keratinocytes and fibroblasts. Together, we conclude that MHY1485 inhibits UV-induced skin cell damages via activating mTOR-Nrf2 signaling.

Activation of Nrf2 Attenuates Pulmonary Vascular Remodeling via Inhibiting Endothelial-to-Mesenchymal Transition: an Insight from a Plant Polyphenol

The endothelial-to-mesenchymal transition (EndMT) has been demonstrated to be involved in pulmonary vascular remodeling. It is partly attributed to oxidative and inflammatory stresses in endothelial cells. In current study, we conducted a series of experiments to clarify the effect of salvianolic acid A (SAA), a kind of polyphenol compound, in the process of EndMT in human pulmonary arterial endothelial cells and in vivo therapeutic efficacy on vascular remodeling in monocrotaline (MCT)-induced EndMT. EndMT was induced by TGFβ1 in human pulmonary arterial endothelial cells (HPAECs). SAA significantly attenuated EndMT, simultaneously inhibited cell migration and reactive oxygen species (ROS) formation. In MCT-induced pulmonary arterial hypertension (PAH) model, SAA improved vascular function, decreased TGFβ1 level and inhibited inflammation. Mechanistically, SAA stimulated Nrf2 translocation and subsequent heme oxygenase-1 (HO-1) up-regulation. The effect of SAA on EndMT in vitro was abolished by ZnPP, a HO-1 inhibitor. In conclusion, this study indicates a deleterious impact of oxidative stress on EndMT. Polyphenol antioxidant treatment may provide an adjunctive action to alleviate pulmonary vascular remodeling via inhibiting EndMT.

Salvianolic Acid A Inhibits OX-LDL Effects on Exacerbating Choroidal Neovascularization via Downregulating CYLD

Backgrounds

Age-related macular degeneration is closely related to lipid oxidation, while relationship between OX-LDL and choroidal neovascularization is unclear. Recently, cylindromatosis is proved to regulate angiogenesis. However, its role in CNV progression remained unclear. Salvianolic acid A is widely used in vascular diseases. We investigated the relationship between OX-LDL and CNV and explore antineovascularization mechanism of Sal A.

Methods

C57BL6/J mice were randomized into four groups and injected with PBS or OX-LDL, together with Sal A for one week. CNV was induced by laser; CNV severity was analyzed by fundus fluorescein angiography, H&E staining, and choroid flat mount after 1 week. In in vitro experiments, ARPE-19 and HUVECs were cultured with OX-LDL (with or without Sal A) for 48 hours. Angiogenic proteins, cell junction integrity, and tube formation were measured. CYLD siRNA and specific inhibitors were used to explore mechanisms of CYLD in promoting OX-LDL-induced CNV progression.

Results

OX-LDL promoted laser-induced CNV volume by increasing VEGF, PDGF, and CYLD levels. Sal A antagonized OX-LDL effects and restrained CNV progression by decreasing VEGF/PDGF/CYLD, increasing antiangiostatin levels, and promoting P62-CYLD-TRAF6 interaction.

Conclusions

We demonstrated oxidation damage exacerbates CNV progression, and Sal A could be a clinical therapeutic reagent to exudative AMD.

MicroRNA-200a activates Nrf2 signaling to protect osteoblasts from dexamethasone

Treatment with dexamethasone in human osteoblasts leads to oxidative stress and cell injures. NF-E2-related factor 2 (Nrf2) is a key anti-oxidant signaling. We want to induce Nrf2 activation via microRNA-mediated silencing its suppressor Keap1. Our results show that microRNA-200a ("miR-200a") expression depleted Keap1, causing Nrf2 protein stabilization in OB-6 osteoblastic cells. Reversely, the miR-200a anti-sense led to Keap1 upregulation and Nrf2 degradation. miR-200a expression activated Nrf2 signaling, which inhibited dexamethasone-induced reactive oxygen species production and OB-6 cell death/apoptosis. Keap1 shRNA also activated Nrf2 and protected OB-6 cells from dexamethasone. Importantly, miR-200a was in-effective in Keap1-silenced (by shRNA) OB-6 cells. In the primary human osteoblasts, Keap1 silence by targeted-shRNA or miR-200a protected cells from dexamethasone. Significantly, miR-200a level was decreased in necrotic femoral head tissues, which was correlated with Keap1 mRNA upregulation. Together, miR-200a expression activates Nrf2 signaling and protects human osteoblasts from dexamethasone.

miRNA-141 attenuates UV-induced oxidative stress via activating Keap1-Nrf2 signaling in human retinal pigment epithelium cells and retinal ganglion cells

Activation of NF-E2-related factor 2 (Nrf2) signaling could protect cells from ultra violet (UV) radiation. We aim to provoke Nrf2 activation via downregulating its inhibitor Keap1 by microRNA-141 (“miR-141”). In both human retinal pigment epithelium cells (RPEs) and retinal ganglion cells (RGCs), forced-expression of miR-141 downregulated Keap1, causing Nrf2 stabilization, accumulation and nuclear translocation, which led to transcription of multiple antioxidant-responsive element (ARE) genes (HO1, NOQ1 and GCLC). Further, UV-induced reactive oxygen species (ROS) production and cell death were significantly attenuated in miR-141-expressing RPEs and RGCs. On the other hand, depletion of miR-141 via expressing its inhibitor antagomiR-141 led to Keap1 upregulation and Nrf2 degradation, which aggravated UV-induced death of RPEs and RGCs. Significantly, Nrf2 shRNA knockdown almost abolished miR-141-mediated cytoprotection against UV in RPEs. These results demonstrate that miR-141 targets Keap1 to activate Nrf2 signaling, which protects RPEs and RGCs from UV radiation.

Involvement of Nrf2 in Ocular Diseases

The human body harbors within it an intricate and delicate balance between oxidants and antioxidants. Any disruption in this checks-and-balances system can lead to harmful consequences in various organs and tissues, such as the eye. This review focuses on the effects of oxidative stress and the role of a particular antioxidant system—the Keap1-Nrf2-ARE pathway—on ocular diseases, specifically age-related macular degeneration, cataracts, diabetic retinopathy, and glaucoma. Together, they are the major causes of blindness in the world.

Anthocyanins encapsulated by PLGA@PEG nanoparticles potentially improved its free radical scavenging capabilities via p38/JNK pathway against Aβ1-42-induced oxidative stress

BACKGROUND

In order to increase the bioavailability of hydrophilic unstable drugs like anthocyanins, we employed a polymer-based nanoparticles approach due to its unique properties such as high stability, improved bioavailability and high water-soluble drug loading efficiency. Anthocyanins constitute a subfamily of flavonoids that possess anti-oxidative, anti-inflammatory and neuroprotective properties. However, anthocyanins are unstable because their phenolic hydroxyl groups are easily oxidized into quinones, causing a reduced biological activity. To overcome this drawback and improve the free radical scavenging capabilities of anthocyanins, in the current study we for the first time encapsulated the anthocyanins in biodegradable nanoparticle formulation based on poly (lactide-co-glycolide) (PLGA) and a stabilizer polyethylene glycol (PEG)-2000. The biological activity and neuroprotective effect of anthocyanin loaded nanoparticles (An-NPs) were investigated in SH-SY5Y cell lines.

RESULTS

Morphological examination under transmission electron microscopy (TEM) showed the formation of smooth spherically shaped nanoparticles. The average particle size and zeta potential of An-NPs were in the range of 120-165 nm and -12 mV respectively, with a low polydispersity index (0.4) and displayed a biphasic release profile in vitro. Anthocyanins encapsulation in PLGA@PEG nanoparticles (NPs) did not destroy its inherent properties and exhibit more potent neuroprotective properties. An-NPs were nontoxic to SH-SY5Y cells and increased their cell viability against Aβ_1-42 by its free radical scavenging characteristics and abrogated ROS generation via the p38-MAPK/JNK pathways accompanied by induction of endogenous nuclear factor erythroid 2-related factor 2 (Nrf2) and heme oxygenase 1 (HO-1). Comparative to native bulk anthocyanins, An-NPs effectively attenuated Alzheimer's markers like APP (amyloid precursor protein), BACE-1 (beta-site amyloid precursor protein cleaving enzyme 1), neuroinflammatory markers such as p-NF-kB (phospho-nuclear factor kappa B), TNF-α (tumor necrosis factor) and iNOS (inducible nitric oxide synthase) and neuroapoptotic markers including Bax, Bcl₂, and Caspase-3 protein expressions accompanied by neurodegeneration against Aβ_1-42 in SH-SY5Y cell lines.

CONCLUSIONS

Overall, this data not only confirmed the therapeutic potential of anthocyanins in reducing AD pathology but also offer an effective way to improve the efficiency of anthocyanins through the use of nanodrug delivery systems.

Hesperetin protects against H2O2-triggered oxidative damage via upregulation of the Keap1-Nrf2/HO-1 signal pathway in ARPE-19 cells

Age-related macular degeneration (AMD) is an irreversible vision loss disease that primarily results from oxidative stress that causes oxidative damage to the retinal pigment epithelial (RPE) cells. Hesperetin (Hesp) is a common flavanone glycoside compound that has been demonstrated to exhibit a variety of biological and pharmacological properties that include anti-inflammatory and antioxidant properties. The aim of this study is to explore the ability of Hesp to attenuate oxidative damage in hydrogen peroxide (H₂O₂)-stimulated ARPE-19 cells. The results indicated that Hesp treatment not only increased cell survival but also decreased reactive oxygen species (ROS) generation, whereas these roles were effectively enhanced the superoxide dismutase (SOD) and glutathione (GSH) levels, and reduced malondialdehyde (MDA) formation. Importantly, the level of heme oxygenase-1 (HO-1) expression was increased by Hesp exposure, which resulted in a decrease after the transfection of cells with Nrf2-siRNA. Additionally, further results revealed that Hesp treatment significantly elevated Keap-1 protein expression, Nrf2 nuclear translocation and ARE activities. These observations indicated that Hesp treatment effectively protected against H₂O₂-induced oxidative damage in ARPE-19 cells by inhibiting cell apoptosis, ROS overproduction and MDA formation as well as enhancing the SOD and GSH levels. The underlying mechanisms may be related to the activation of the Keap1-Nrf2/HO-1 signal pathway, which may provide biological evidence to further encourage the investigation of the protective effect of Hesp in AMD disease.

Gremlin inhibits UV-induced skin cell damages via activating VEGFR2-Nrf2 signaling

Ultra Violet (UV) radiation induces reactive oxygen species (ROS) production, DNA oxidation and single strand breaks (SSBs), which will eventually lead to skin cell damages or even skin cancer. Here, we tested the potential activity of gremlin, a novel vascular endothelial growth factor (VEGF) receptor 2 (VEGFR2) agonist, against UV-induced skin cell damages. We show that gremlin activated VEGFR2 and significantly inhibited UV-induced death and apoptosis of skin keratinocytes and fibroblasts. Pharmacological inhibition or shRNA-mediated knockdown of VEGFR2 almost abolished gremlin-mediated cytoprotection against UV in the skin cells. Further studies showed that gremlin activated VEGFR2 downstream NF-E2-related factor 2 (Nrf2) signaling, which appeared required for subsequent skin cell protection. Nrf2 shRNA knockdown or S40T dominant negative mutation largely inhibited gremlin-mediated skin cell protection against UV. At last, we show that gremlin dramatically inhibited UV-induced ROS production and DNA SSB formation in skin keratinocytes and fibroblasts. We conclude that gremlin protects skin cells from UV damages via activating VEGFR2-Nrf2 signaling. Gremlin could be further tested as a novel anti-UV skin protectant.

Miltirone protects human EA.hy926 endothelial cells from oxidized low-density lipoprotein-derived oxidative stress via a heme oxygenase-1 and MAPK/Nrf2 dependent pathway

BACKGROUND

Oxidized low-density lipoprotein (ox-LDL) is an underlying cause of endothelial dysfunction, which is an early event in the pathogenesis of atherosclerosis. In our previous study, we established an ARE-driven luciferase reporter system and screened out several potential Nrf2 activators from Salvia miltiorrhiza Bunge.

PURPOSE

Since miltirone showed the most potent ARE-driven luciferase activity, the aim of this study was to test the protective role of miltirone against oxidative stress in endothelial cell and to investigate the underlying mechanistic signaling pathways.

STUDY DESIGN/METHOD

In the present study, miltirone increased the expression of nuclear translocation and transcriptional activities of NF-E2-related factor 2 (Nrf2), which led to augmented expression of antioxidant-response element (ARE)-dependent heme oxygenase-1 (HO-1) and NAD(P)H-quinone oxidoreductase 1 (NQO1). Inhibition of Nrf2/HO-1 by RNA interference abolished miltirone-induced cytoprotective effects against ox-LDL, which suggested that Nrf2 and the downstream expression of HO-1 are required for the functional effects of miltirone. Ox-LDL-stimulated mitogen-activated protein kinase activation, ROS production, and miltirone dramatically inhibited synthesis of ROS, as well as decreased SOD and glutathione S-transferase (GST) in human EA.hy926 endothelial cells.

RESULTS

Miltirone-induced Nrf2 and HO-1 expression was related to mitogen-activated protein kinase (MAPK) pathways. The activation of MAPK was partially dependent on the phosphorylation of the c-Jun NH2-terminal kinase (JNK) and extracellular signal-regulated kinase (ERK) pathways, but not P38 MAPK signaling. However, miltirone-induced Nrf2/HO-1 expression can only be effectively blocked by JNK inhibitor SP600125.

CONCLUSION

Our findings reveal that miltirone exerts protective functions on endothelial cells in response to ox-LDL-induced oxidative stress, and does so via Nrf2/HO-1, which provides novel insights into the antioxidant capacity of miltirone.

Inhibition of heme oxygenase-1 enhances the chemosensitivity of laryngeal squamous cell cancer Hep-2 cells to cisplatin

It has been previously reported that cisplatin is a well-known anticancer drug being used against a wide range of malignancies including head and neck, ovarian and non-small cell lung carcinoma, and demonstrated its anticancer activity by reacting with DNA or changing cell structure, immune response, reactive oxygen species level (ROS). In this research we proved that cisplatin induced cell injuries and heme oxygenase-1 (HO-1) expression in laryngeal squamous cell cancer Hep-2 cells through ROS generation. The induction of HO-1 clearly protected Hep-2 cells from cisplatin-induced cell death and ROS reaction, and the inhibitor of HO-1 enhanced the cell death and ROS generation induced by cisplatin. Furthermore, the HO-1 expression induced by cisplatin was strongly inhibited by the knockdown of nuclear factor-erythroid-2-related factor-2 (Nrf-2), and the oxidative damages induced by cisplatin were significantly enhanced. Therefore, it may be concluded that the inhibition of HO-1 or the knockdown of Nrf-2 significantly enhanced cisplatin's anticancer effects on Hep-2 cells. In clinic, with the overexpression of HO-1 in laryngeal squamous cancer tissues, the combination of cisplatin with the inhibitor of HO-1 or Nrf-2 siRNA may act as a new method to the treatment of laryngeal squamous cancer.

Nuclear Factor (Erythroid-Derived)-Related Factor 2-Associated Retinal Pigment Epithelial Cell Protection under Blue Light-Induced Oxidative Stress

Purpose. It is a matter of increasing concern that exposure to light-emitting diodes (LED), particularly blue light (BL), damages retinal cells. This study aimed to investigate the retinal pigment epithelium (RPE) damage caused by BL and to elucidate the role of nuclear factor (erythroid-derived)-related factor 2 (Nrf2) in the pathogenesis of BL-induced RPE damage. Methods. ARPE-19, a human RPE cell line, and mouse primary RPE cells from wild-type and Nrf2 knockout (Nrf2^-/-) mice were cultured under blue LED exposure (intermediate wavelength, 450 nm). Cell death rate and reactive oxygen species (ROS) generation were measured. TUNEL staining was performed to detect apoptosis. Real-time polymerase chain reaction was performed on NRF2 mRNA, and western blotting was performed to detect Nrf2 proteins in the nucleus or cytoplasm of RPE cells. Results. BL exposure increased cell death rate and ROS generation in ARPE-19 cells in a time-dependent manner; cell death was caused by apoptosis. Moreover, BL exposure induced NRF2 mRNA upregulation and Nrf2 nuclear translocation in RPE. Cell death rate was significantly higher in RPE cells from Nrf2^-/- mice than from wild-type mice. Conclusions. The Nrf2 pathway plays an important role in protecting RPE cells against BL-induced oxidative stress.

Small Molecular TRAIL Inducer ONC201 Induces Death in Lung Cancer Cells: A Preclinical Study

Tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) selectively targets cancer cells. The present preclinical study investigated the anti-cancer efficiency of ONC201, a first-in-class small molecule TRAIL inducer, in lung cancer cells. We showed that ONC201 was cytotoxic and anti-proliferative in both established (A549 and H460 lines) and primary human lung cancer cells. It was yet non-cytotoxic to normal lung epithelial cells. Further, ONC201 induced exogenous apoptosis activation in lung cancer cells, which was evidenced by TRAIL/death receptor-5 (DR5) induction and caspase-8 activation. The caspase-8 inhibitor or TRAIL/DR5 siRNA knockdown alleviated ONC201's cytotoxicity against lung cancer cells. Molecularly, ONC201 in-activated Akt-S6K1 and Erk signalings in lung cancer cells, causing Foxo3a nuclear translocation. For the in vivo studies, intraperitoneal injection of ONC201 at well-tolerated doses significantly inhibited xenografted A549 tumor growth in severe combined immunodeficient (SCID) mice. Further, ONC201 administration induced TRAIL/DR5 expression, yet inactivated Akt-S6K1 and Erk in tumor tissues. These results of the study demonstrates the potent anti-lung cancer activity by ONC201.

SC79 rescues osteoblasts from dexamethasone though activating Akt-Nrf2 signaling

Dexamethasone (Dex) causes osteoblast cell injuries. In the present research, we tested the potential effect of SC79, a novel and specific Akt activator, against Dex in osteoblasts. In primary murine osteoblasts and osteoblastic MC3T3-E1 cells, pretreatment with SC79 significantly attenuated Dex-induced cell death. Further, Dex-induced mitochondrial permeability transition pore (mPTP) opening, cytochrome C release and apoptosis activation were dramatically alleviated with SC79 pretreatment in above cells. At the molecular level, SC79 activated Akt, which was indispensable for subsequent osteoblast protection against Dex. Akt inhibitors (LY294002, perifosine and MK-2206) blocked SC79-induced Akt activation and abolished its anti-Dex actions in osteoblasts. Further, SC79 activated Akt downstream Nrf2 (NF-E2-related factor 2) signaling and attenuated Dex-induced oxidative stress in osteoblasts. Nrf2 shRNA knockdown or S40T mutation almost reversed SC79-mediated anti-oxidant and cytoprotective activities in osteoblasts. Together, these results suggest that SC79 activates Akt-Nrf2 signaling to protect osteoblasts from Dex.

Sulforaphane protects against rotenone-induced neurotoxicity in vivo: Involvement of the mTOR, Nrf2, and autophagy pathways

Sulforaphane, a naturally occurring compound found in cruciferous vegetables, has been shown to be neuroprotective in several neurological disorders. In this study, we sought to investigate the potential protective effects and associated molecular mechanisms of sulforaphane in an in vivo Parkinson's disease (PD) model, based on rotenone-mediated neurotoxicity. Our results showed that sulforaphane inhibited rotenone-induced locomotor activity deficiency and dopaminergic neuronal loss. Additionally, sulforaphane treatment inhibited the rotenone-induced reactive oxygen species production, malondialdehyde (MDA) accumulation, and resulted in an increased level of total glutathione and reduced glutathione (GSH): oxidized glutathione (GSSG) in the brain. Western blot analysis illustrated that sulforaphane increased the expression of nuclear factor (erythroid-derived 2)-like 2 (Nrf2), heme oxygenase-1 (HO-1), and NAD(P)H quinone oxidoreductase (NQO1), the latter two of which are anti-oxidative enzymes. Moreover, sulforaphane treatment significantly attenuated rotenone-inhibited mTOR-mediated p70S6K and 4E-BP1 signalling pathway, as well as neuronal apoptosis. In addition, sulforaphane rescued rotenone-inhibited autophagy, as detected by LC3-II. Collectively, these findings demonstrated that sulforaphane exert neuroprotective effect involving Nrf2-dependent reductions in oxidative stress, mTOR-dependent inhibition of neuronal apoptosis, and the restoration of normal autophagy. Sulforaphane appears to be a promising compound with neuroprotective properties that may play an important role in preventing PD.

Cellular and Molecular Pathology of Age-Related Macular Degeneration: Potential Role for Proteoglycans

Age-related macular degeneration (AMD) is a retinal disease evident after the age of 50 that damages the macula in the centre of retina. It leads to a loss of central vision with retained peripheral vision but eventual blindness occurs in many cases. The initiation site of AMD development is Bruch's membrane (BM) where multiple changes occur including the deposition of plasma derived lipids, accumulation of extracellular debris, changes in cell morphology, and viability and the formation of drusen. AMD manifests as early and late stage; the latter involves cell proliferation and neovascularization in wet AMD. Current therapies target the later hyperproliferative and invasive wet stage whilst none target early developmental stages of AMD. In the lipid deposition disease atherosclerosis modified proteoglycans bind and retain apolipoproteins in the artery wall. Chemically modified trapped lipids are immunogenic and can initiate a chronic inflammatory process manifesting as atherosclerotic plaques and subsequent artery blockages, heart attacks, or strokes. As plasma derived lipoprotein deposits are found in BM in early AMD, it is possible that they arise by a similar process within the macula. In this review we consider aspects of the pathological processes underlying AMD with a focus on the potential role of modifications to secreted proteoglycans being a cause and therefore a target for the treatment of early AMD.

Effects of the Nrf2 Protein Modulator Salvianolic Acid A Alone or Combined with Metformin on Diabetes-associated Macrovascular and Renal Injury

Nuclear factor E2-related factor 2 (Nrf2) is considered a promising target against diabetic complications such as cardiovascular diseases and diabetic nephropathy. Herein, we investigated the effects of a potential Nrf2 modulator, salvianolic acid A (SAA), which is a natural polyphenol, on diabetes-associated macrovascular and renal injuries in streptozotocin-induced diabetic mice. Given that lowering glucose is the first objective of diabetic patients, we also examined the effects of SAA combined with metformin (MET) on both complications. Our results showed that SAA significantly increased the macrovascular relaxation response to acetylcholine and sodium nitroprusside in diabetic mice. Interestingly, treatment with SAA alone only provided minor protection against renal injury, as reflected by minor improvements in impaired renal function and structure, despite significantly reduced oxidative stress observed in the diabetic kidney. We demonstrated that decreased oxidative stress and NF-κB p65 expression were associated with SAA-induced expression of Nrf2-responsive antioxidant enzymes heme oxygenase-1 (HO-1), NAD(P)H dehydrogenase (quinone) 1 (NQO-1), and glutathione peroxidase-1 (GPx-1) in vivo or in vitro, which suggested that SAA was a potential Nrf2 modulator. More significantly, compared with treatment with either SAA or MET alone, we found that their combination provided further protection against the macrovascular and renal injury, which was at least partly due to therapeutic activation of both MET-mediated AMP-activated protein kinase and SAA-mediated Nrf2/antioxidant-response element pathways. These findings suggested that polyphenol Nrf2 modulators, especially combined with drugs activating AMP-activated protein kinase, including hypoglycemic drugs, are worthy of further investigation to combat diabetic complications.

New insights into salvianolic acid A action: Regulation of the TXNIP/NLRP3 and TXNIP/ChREBP pathways ameliorates HFD-induced NAFLD in rats

Salvianolic acid A (SalA), one of the most efficacious polyphenol compounds extracted from Radix Salvia miltiorrhiza (Danshen), has been shown to possess many potential pharmacological activities. This study aimed to investigate whether SalA has hepatoprotective effects against high-fat diet (HFD)-induced non-alcoholic fatty liver disease (NAFLD) and to further explore the mechanism underlying this process. SalA treatment significantly attenuated HFD-induced obesity and liver injury, and markedly decreased lipid accumulation in HFD-fed rat livers. Moreover, SalA treatment ameliorated HFD-induced hepatic inflammation and oxidative stress by decreasing hepatotoxic levels of cytokines, suppressing the overproduction of reactive oxygen species (ROS) and methane dicarboxylic aldehyde (MDA) and preventing the decreased expression of superoxide dismutase (SOD). Importantly, SalA reversed the HFD- or palmitic acid (PA)-induced activation of the NLRP3 inflammasome, the nuclear translocation of ChREBP and the up-regulation of FAS, and these effects were accompanied by TXNIP down-regulation. However, TXNIP siRNA treatment partially abrogated the above-mentioned effects of SalA in PA-treated HepG2 cells. Together, our results demonstrated, for the first time, that SalA protects against HFD-induced NAFLD by ameliorating hepatic lipid accumulation and inflammation, and these protective effects may partially due to regulation of the TXNIP/NLRP3 and TXNIP/ChREBP pathways.

Paeoniflorin protects Schwann cells against high glucose induced oxidative injury by activating Nrf2/ARE pathway and inhibiting apoptosis

ETHNOPHARMACOLOGICAL RELEVANCE

Paeoniflorin (PF) is the principal bioactive component of Paeonia lactiflora Pall., which an included in Tang Luo Ning recipe, a traditional Chinese herbal medicine based on Huangqi Guizhi Wuwu decoction. PF is also widely used in Traditional Chinese Medicine for the treatment of blood-arthralgia disease including diabetic peripheral neuropathy (DPN), but its underlying molecular mechanism of neuroprotective effects is not yet well understood. Diabetic hyperglycemia induced oxidative stress in Schwann cells, an important component of the peripheral nervous system, has been proposed as a unifying mechanism for DPN. The objective of this study is to determine the effects of PF on Schwann cells oxidative stress and apoptosis induced by high glucose.

MATERIALS AND METHODS

RSC96 cells, a Schwann cell line, were treated with high glucose (150mM) and PF (1, 10 and 100μM). Subsequently, MTT assay was performed. The level of apoptosis was examined by flow cytometry and the oxidative stress was reflected by reactive oxygen species (ROS), malondialdehyde (MDA), glutathione S-transferases (GST) and glutathione peroxidase (GPX) levels. The mRNA expressions of Nuclear factor-E2-related factor 2 (Nrf2) and heme oxygenase 1 (HO-1) were detected by qRT-PCR. The levels of Kelch-like ECH-associating protein 1 (Keap1), Nrf2, HO-1, γ-glutamylcysteine synthetase (γGCS), B-cell CLL/lymphoma 2 (Bcl-2), Bax and Caspase 3 were detected by High content analysis and/or Western blot.

RESULTS

The role of PF markedly suppressed high glucose induced Schwann cells oxidative stress by decreasing ROS and MDA levels and increasing GST and GPX activity. Western blot analysis showed that PF induced nuclear translocation of Nrf2. High content analysis showed that PF promoted Nrf2 dissociation from Keap1 and upregulating the Nrf2/ antioxidant response element (ARE) pathway. Furthermore, PF reduced Schwann cells apoptosis by increasing Bcl-2 and inhibiting Bax and Caspase-3 expressions.

CONCLUSIONS

PF in the management of Schwann cells oxidative stress induced by high glucose may be associated with activation of Nrf2/ARE pathway and Bcl-2-related apoptotic pathway.

CEMTDD: The database for elucidating the relationships among herbs, compounds, targets and related diseases for Chinese ethnic minority traditional drugs

China has different ethnic minorities that establish their own medical systems and practice experience for thousand years, thereafter named Chinese Ethnic Minority Traditional Drugs (CEMTDs) (http://www.cemtdd.com/index.html). Since many compounds from CEMTDs have been reported to perturb human's dysfunction network and restore human normal physiological conditions, the relationships amongst a series of compounds from specific herbs, their targets and relevant diseases have become our main focus in CEMTD modernization. Herein, we have constructed the first Chinese Ethnic Minority Traditional Drug Database (CEMTDD) mainly from Xinjiang Uygur Autonomous Region (XUAR), retrieving CEMTD-related information from different resources. CEMTDD contains about 621 herbs, 4, 060 compounds, 2, 163 targets and 210 diseases, among which most of herbs can be applied into gerontology therapy including inflammation, cardiovascular disease and neurodegenerative disease. Gerontology is highly occurred in XUAR, and has abundant experience in treating such diseases, which may benefit for developing a new gerontology therapeutic strategy. CEMTDD displays networks for intricate relationships between CEMTDs and treated diseases, as well as the interrelations between active compounds and action targets, which may shed new light on the combination therapy of CEMTDs and further understanding of their herb molecular mechanisms for better modernized utilizations of CEMTDs, especially in gerontology.

3H-1,2-dithiole-3-thione protects retinal pigment epithelium cells against Ultra-violet radiation via activation of Akt-mTORC1-dependent Nrf2-HO-1 signaling

Excessive UV radiation and reactive oxygen species (ROS) cause retinal pigment epithelium (RPE) cell injuries. Nrf2 regulates transcriptional activation of many anti-oxidant genes. Here, we tested the potential role of 3H-1,2-dithiole-3-thione (D3T) against UV or ROS damages in cultured RPE cells (both primary cells and ARPE-19 line). We showed that D3T significantly inhibited UV-/H₂O₂-induced RPE cell death and apoptosis. UV-stimulated ROS production was dramatically inhibited by D3T pretreatment. D3T induced Nrf2 phosphorylation in cultured RPE cells, causing Nrf2 disassociation with KEAP1 and its subsequent nuclear accumulation. This led to expression of antioxidant response elements (ARE)-dependent gene heme oxygenase-1 (HO-1). Nrf2-HO-1 activation was required for D3T-mediated cytoprotective effect. Nrf2 shRNA knockdown or S40T dominant negative mutation as well as the HO-1 inhibitor Zinc protoporphyrin (ZnPP) largely inhibited D3T’s RPE cytoprotective effects against UV radiation. Yet, exogenous overexpression Nrf2 enhanced D3T’s activity in RPE cells. Further studies showed that D3T activated Akt/mTORC1 in cultured RPE cells. Akt-mTORC1 inhibitors, or Akt1 knockdown by shRNA, not only inhibited D3T-induced Nrf2-HO-1 activation, but also abolished the RPE cytoprotective effects. In vivo, D3T intravitreal injection protected from light-induced retinal dysfunctions in mice. Thus, D3T protects RPE cells from UV-induced damages via activation of Akt-mTORC1-Nrf2-HO-1 signaling axis.

Isotetrandrine ameliorates tert-butyl hydroperoxide-induced oxidative stress through upregulation of heme oxygenase-1 expression

1R, 1'S-isotetrandrine, a naturally occurring plant alkaloid found in Mahonia of Berberidaceae, possesses anti-inflammatory, antibacterial, and antiviral properties, but the antioxidative activity and mechanism action remain unclear. In this study, we demonstrated the antioxidative effect and mechanism of 1R, 1'S-isotetrandrine against tert-butyl hydroperoxide-induced oxidative damage in HepG2 cells. We found that 1R, 1'S-isotetrandrine suppressed cytotoxicity, reactive oxygen species generation, and glutathione depletion. Additionally, our study confirmed that 1R, 1'S-isotetrandrine significantly increased the antioxidant enzyme heme oxygenase-1 expression and nuclear translocation of factor-erythroid 2 p45-related factor 2 (Nrf2). Specifically, the nuclear translocation of Nrf2 induced by 1R, 1'S-isotetrandrine was associated with Nrf2 negative regulatory protein Keap1 inactivation and phosphorylation of both extracellular signal-regulated protein kinase and c-Jun NH2-terminal kinase. Preincubation with thiol-reducing agents reduced 1R, 1'S-isotetrandrine-induced heme oxygenase-1 expression, and treatment with either extracellular signal-regulated protein kinase or c-Jun NH2-terminal kinase inhibitors attenuated the levels of 1R, 1'S-isotetrandrine-induced Nrf2 activation and heme oxygenase-1 expression. Furthermore, the cytoprotective effect of 1R, 1'S-isotetrandrine was abolished by heme oxygenase-1, extracellular signal-regulated protein kinase, and c-Jun NH2-terminal kinase inhibitors. These results indicated that the 1R, 1'S-isotetrandrine ameliorated tert-butyl hydroperoxide-induced oxidative damage through upregulation of heme oxygenase-1 expression by the dissociation of Nrf2 from Nrf2-Keap1 complex via extracellular signal-regulated protein kinase and c-Jun NH2-terminal kinase activation and Keap1 inactivation.

Polyphenols: Potential source of drugs for the treatment of ischaemic heart disease

Polyphenols, which are naturally present in plants, have been studied for their chemical and pharmacological properties. Polyphenols have been found to exhibit various bioactivities such as antioxidant, free radical scavenging and anti-inflammatory effects, in addition to regulating the intracellular free calcium levels. These bioactivities are related to the underlying mechanisms of ischaemic heart diseases. Pharmacological studies have proven polyphenols to be effective in treating cardiovascular diseases in various ways, particularly ischaemic heart diseases. Based on their mode of action, we propose that some polyphenols can be developed as drugs to treat ischaemic heart diseases. For this purpose, a strategy to evaluate the therapeutic value of drugs for ischaemic heart diseases is needed. Despite several advances in percutaneous coronary intervention (PCI), the incidence of myocardial infarction and deaths due to cardiovascular diseases has not decreased markedly in China. Due to their pleiotropic properties and structural diversity, polyphenols have been of great interest in pharmacology. In the present review, we summarize the pharmacological effects and mechanisms of polyphenols reported after 2000, and we analyse the benefits or druggability of these compounds for ischaemic heart diseases.

Salvia miltiorrhiza: Traditional medicinal uses, chemistry, and pharmacology

Salvia miltiorrhiza Bunge (SM) is a very popular medicinal plant that has been extensively applied for many years to treat various diseases, especially coronary heart diseases and cerebrovascular diseases, either alone or in combination with other Chinese plant-based medicines. Although a large number of studies on SM have been performed, they are scattered across a variety of publications. The present review is an up-to-date summary of the published scientific information about the traditional uses, chemical constituents, pharmacological effects, side effects, and drug interactions with SM, in order to lay the foundation for further investigations and better utilization of SM. SM contains diverse chemical components including diterpenoid quinones, hydrophilic phenolic acids, and essential oils. Many pharmacological studies have been done on SM during the last 30 years, focusing on the cardiovascular and cerebrovascular effects, and the antioxidative, neuroprotective, antifibrotic, anti-inflammatory, and antineoplastic activities. The research results strongly support the notion that SM has beneficial therapeutic properties and has a potential of being an effective adaptogenic remedy.

The novel triterpenoid RTA 408 protects human retinal pigment epithelial cells against H2O2-induced cell injury via NF-E2-related factor 2 (Nrf2) activation

Oxidative stress-induced retinal pigment epithelial (RPE) cell damage is an important factor in the pathogenesis of age-related macular degeneration (AMD). Previous studies have shown that RTA 408, a synthetic triterpenoid compound, potently activates Nrf2. This study aimed to investigate the protective effects of RTA 408 in cultured RPE cells during oxidative stress and to determine the effects of RTA 408 on Nrf2 and its downstream target genes. Primary human RPE cells were pretreated with RTA 408 and then incubated in 200μM H2O2 for 6h. Cell viability was measured with the WST-8 assay. Apoptosis was quantitatively measured by annexin V/propidium iodide (PI) double staining and Hoechst 33342 fluorescent staining. Reduced (GSH) and oxidized glutathione (GSSG) were measured using colorimetric assays. Nrf2 activation and its downstream effects on phase II enzymes were examined by Western blot. Treatment of RPE cells with nanomolar ranges (10 and 100nM) of RTA 408 markedly attenuated H2O2-induced viability loss and apoptosis. RTA 408 pretreatment significantly protected cells from oxidative stress-induced GSH loss, GSSG formation and decreased ROS production. RTA 408 activated Nrf2 and increased the expression of its downstream genes, such as HO-1, NQO1, SOD2, catalase, Grx1, and Trx1. Consequently, the enzyme activities of NQO1, Grx1, and Trx1 were fully protected by RTA 408 pretreatment under oxidative stress. Moreover, knockdown of Nrf2 by siRNA significantly reduced the cytoprotective effects of RTA 408. In conclusion, our data suggest that RTA 408 protect primary human RPE cells from oxidative stress-induced damage by activating Nrf2 and its downstream genes.

Novel role of TRPV2 in promoting the cytotoxicity of H2O2-mediated oxidative stress in human hepatoma cells

Oxidative stress is important for the initiation and progression of cancers, which confers the cells with a survival advantage by inducing oxidative adaption and drug resistance. Therefore, developing strategies to promote oxidative stress-induced cytotoxicity could be important for cancer therapy. Herein, we found that H2O2-mediated oxidative stress increases TRPV2 expression in human hepatoma (HepG2 and Huh-7) cells. This occurred at the mRNA and protein levels in a dose-dependent manner. The significance of TRPV2 in promoting H2O2-induced cell death was demonstrated in gain and loss of function studies with overexpression and knockdown of TRPV2, respectively. Mechanistically, H2O2-induced cell death involves inhibition of pro-survival signaling proteins (Akt, Nrf2) and activation of pro-death signaling proteins (p38, JNK1). Overexpression of TRPV2 in H2O2-treated hepatoma cells aggravates the inhibition of Akt and Nrf2, while it enhances the activation of p38 and JNK1 at the early stage of cell death. Interestingly, increased expression of TRPV2 in HepG2 cells improved the efficacy of stress-associated chemicals to induce cell death. Our findings suggest that TRPV2 acts as an important enhancer for H2O2-induced cytotoxicity. This process occurred by the inhibition of Akt and Nrf2 as well as the early activation of p38 and JNK1. These findings have important implications for inhibition of oxidative adaption and drug resistance.

4-Acetoxyphenol Prevents RPE Oxidative Stress-Induced Necrosis by Functioning as an NRF2 Stabilizer

PURPOSE

Oxidative stress has been suggested to be a major risk factor for the pathogenesis of AMD. Retinal pigment epithelial (RPE) cells are essential for maintaining the homeostasis of the retina, and RPE cell death and the resultant photoreceptor apoptosis have been observed in dry AMD, especially in geographic atrophy. The purpose of this article was to identify and repurpose the Food and Drug Administration-approved natural compound 4-Acetoxyphenol (4-AC), and to evaluate its effect and mechanism in protecting against oxidative stress-induced RPE necrosis.

METHODS

We exposed ARPE-19 cells to tert-Butyl hydroperoxide (tBHP) after pretreatment with 4-AC, and measured cell viability by MTT assay. Aggregation of RIPK3 and HMGB1 nuclear release were analyzed by transfected reporter genes. Reactive oxygen species (ROS) were measured using a commercially available ROS detection system. The importance of the NRF2/NQO1/HO-1 pathway in mediating 4-AC function was corroborated by siRNA studies, qRT-PCR, and immunostaining.

RESULTS

We have identified a natural antioxidant, 4-AC, which demonstrates strong abilities to protect RPE cells from oxidative stress-induced necrosis. Mechanistically, 4-AC blocked the increase of cellular ROS induced by oxidative stress, and upregulated NQO1 and HO-1 genes by stabilizing and inducing the nuclear translocation of NRF2 transcription factor. The NQO1, HO-1, and NRF2 were further shown to be required for 4-AC protection of RPE cells from death induced by tBHP. The tBHQ, an NRF2 stabilizer, consistently mimicked the protective effect of 4-AC against tBHP-induced RPE death.

CONCLUSIONS

The compound 4-AC protects ARPE-19 cells from oxidative stress-induced necrosis through upregulation of NQO1 and HO-1 genes by stabilization of NRF2.

Escin activates AKT-Nrf2 signaling to protect retinal pigment epithelium cells from oxidative stress

Here we explored the anti-oxidative and cytoprotective potentials of escin, a natural triterpene-saponin, against hydrogen peroxide (H2O2) in retinal pigment epithelium (RPE) cells. We showed that escin remarkably attenuated H2O2-induced death and apoptosis of established (ARPE-19) and primary murine RPE cells. Meanwhile, ROS production and lipid peroxidation by H2O2 were remarkably inhibited by escin. Escin treatment in RPE cells resulted in NF-E2-related factor 2 (Nrf2) signaling activation, evidenced by transcription of anti-oxidant-responsive element (ARE)-regulated genes, including HO-1, NQO-1 and SRXN-1. Knockdown of Nrf2 through targeted shRNAs/siRNAs alleviated escin-mediated ARE gene transcription, and almost abolished escin-mediated anti-oxidant activity and RPE cytoprotection against H2O2. Reversely, escin was more potent against H2O2 damages in Nrf2-over-expressed ARPE-19 cells. Further studies showed that escin-induced Nrf2 activation in RPE cells required AKT signaling. AKT inhibitors (LY294002 and perifosine) blocked escin-induced AKT activation, and dramatically inhibited Nrf2 phosphorylation, its cytosol accumulation and nuclear translocation in RPE cells. Escin-induced RPE cytoprotection against H2O2 was also alleviated by the AKT inhibitors. Together, these results demonstrate that escin protects RPE cells from oxidative stress possibly through activating AKT-Nrf2 signaling.

Retino-protective effect of Bucida buceras against oxidative stress induced by H2O2 in human retinal pigment epithelial cells line

BACKGROUND

Reactive Oxygen Species (ROS) impair the physiological functions of Retinal Pigment Epithelial (RPE) cells, which are known as one major cause of age-related macular degeneration and retinopathy diseases. The purpose of this study is to explore the cytoprotective effects of the antioxidant Bucida buceras extract in co-treatment with hydrogen peroxide (H2O2) delivery as a single addition or with continuous generation using glucose oxidase (GOx) in ARPE-19 cell cultures. The mechanism of Bucida buceras extract is believed to be associated with their antioxidant capacity to protect cells against oxidative stress.

METHODS

A comparative oxidative stress H2O2-induced was performed by addition and enzymatic generation using glucose oxidase on human retinal pigment epithelial cells line. H2O2-induced injury was measured by toxic effects (cell death and apoptotic pathway) and intracellular redox status: glutathione (GSH), antioxidant enzymes (catalase and glutathione peroxidase) and reducing power (FRAP). The retino-protective effect of co-treatment with Bucida buceras extract on H2O2-induced human RPE cell injury was investigated by cell death (MTT assay) and oxidative stress biomarkers (H2O2, GSH, CAT, GPx and FRAP).

RESULTS

Bucida buceras L. extract is believed to be associated with the ability to prevent cellular oxidative stress. When added as a pulse, H2O2 is rapidly depleted and the cytotoxicity analyses show that cells can tolerate short exposure to high peroxide doses delivered as a pulse but are susceptible to lower chronic doses. Co-treatment with Bucida buceras was able to protect the cells against H2O2-induced injury. In addition to preventing cell death treatment with antioxidant plant could also reverse the significant decrease in GSH level, catalase activity and reducing power caused by H2O2.

CONCLUSION

These findings suggest that Bucida buceras could protect RPE against ocular pathogenesis associated with oxidative stress induced by H2O2-delivered by addition and enzymatic generation.

Inhibition of Glutathione Production Induces Macrophage CD36 Expression and Enhances Cellular-oxidized Low Density Lipoprotein (oxLDL) Uptake

The glutathione (GSH)-dependent antioxidant system has been demonstrated to inhibit atherosclerosis. Macrophage CD36 uptakes oxidized low density lipoprotein (oxLDL) thereby facilitating foam cell formation and development of atherosclerosis. It remains unknown if GSH can influence macrophage CD36 expression and cellular oxLDL uptake directly. Herein we report that treatment of macrophages with l-buthionine-S,R-sulfoximine (BSO) decreased cellular GSH production and ratios of GSH to glutathione disulfide (GSH/GSSG) while increasing production of reactive oxygen species. Associated with decreased GSH levels, macrophage CD36 expression was increased, which resulted in enhanced cellular oxLDL uptake. In contrast, N-acetyl cysteine and antioxidant enzyme (catalase or superoxide dismutase) blocked BSO-induced CD36 expression as well as oxLDL uptake. In vivo, administration of mice with BSO increased CD36 expression in peritoneal macrophages and kidneys. BSO had no effect on CD36 mRNA expression and promoter activity but still induced CD36 protein expression in macrophages lacking peroxisome proliferator-activated receptor γ expression, suggesting it induced CD36 expression at the translational level. Indeed, we determined that BSO enhanced CD36 translational efficiency. Taken together, our study demonstrates that cellular GSH levels and GSH/GSSG status can regulate macrophage CD36 expression and cellular oxLDL uptake and demonstrate an important anti-atherogenic function of the GSH-dependent antioxidant system by providing a novel molecular mechanism.

The antioxidative potential of farrerol occurs via the activation of Nrf2 mediated HO-1 signaling in RAW 264.7 cells

Farrerol, (S)-2,3-dihydro-5,7-dihydroxy-2-(4-hydroxyphenyl)-6,8-dimethyl-4-benzopyrone, isolated from rhododendron, has been shown to have antioxidative potential, but the molecular mechanism underlying this activity remains unclear. The inducible expression of heme oxygenase-1 (HO-1), a potent antioxidative and cytoprotective enzyme, is known to play an important role in cytoprotection in a variety of pathological models. In this study, we evaluated the antioxidative potential of farrerol against oxidative damage and investigated its antioxidative mechanism in RAW 264.7 cells. The molecular mechanism underlying the cytoprotective function of farrerol was determined by analyzing intracellular signaling pathways, transcriptional activation and the inhibitory effect of HO-1 on ROS production. Farrerol induced antioxidant enzymes mRNA expression, HO-1 protein expression and nuclear translocation of NF-E2-related factor 2 in RAW 264.7 macrophage cells. Farrerol down-regulated the expression of the Keap1 protein and the thiol reducing agents attenuated farrerol-induced HO-1 expression. Further investigation utilizing Western blotting and specific inhibitors of Akt, p38, JNK and ERK demonstrated that Akt, p38, and ERK axis of signaling pathway mediates HO-1 expression. Moreover, tert-butyl hydroperoxide (t-BHP)-induced oxidative damage was ameliorated by farrerol treatment in a dose-dependent manner, which was abolished by Akt, p38, ERK and HO-1 inhibitors (Snpp). It is hence likely that farrerol inactivated KEAP-1 or activated the Akt, p38 and ERK to facilitate the release of Nrf2 from Keap1 and subsequent reduced the intracellular production of reactive oxygen species via the induction of HO-1 expression. These results support the central role of HO-1 in the cytoprotective effect of farrerol.

Administration of Danhong Injection to diabetic db/db mice inhibits the development of diabetic retinopathy and nephropathy

Danhong Injection (DHI), a Chinese medicine for treatment of patients with coronary heart disease, inhibits primary abdominal aortic aneurysms in apoE deficient (apoE^−/−) mice. Formation of microaneurysms plays an important role in the development of diabetic retinopathy and nephropathy. It remains unknown if DHI can reduce these diabetic complications. In this study, diabetic db/db mice in two groups were injected with saline and DHI, respectively, for 14 weeks. Blood and tissue samples were collected to determine serum glucose, lipids and tissue structure. DHI reduced diabetes-induced body weight gain, serum cholesterol and glucose levels. In retinas, DHI blocked the shrink of whole retina and retinal sub-layers by inhibiting expression of caspase 3, matrix metalloproteinase 2 (MMP-2) and MMP-9, accumulation of carbohydrate macromolecules and formation of acellular capillaries. DHI improved renal functions by inhibiting mesangial matrix expansion, expression of vascular endothelial growth factor A, fibronectin and advanced glycation end products in kidneys. Mechanistically, DHI induced expression of glucokinase, AMPKα/phosphorylated AMPKα, insulin receptor substrate 1, fibroblast growth factor 21 and peroxisome proliferator-activated γ. Expression of genes responsible for energy expenditure was also activated by DHI. Therefore, DHI inhibits diabetic retinopathy and nephropathy by ameliorating glucose metabolism and demonstrates a potential application in clinics.

Deciphering the therapeutic mechanisms of Xiao-Ke-An in treatment of type 2 diabetes in mice by a Fangjiomics approach

AIM

Xiao-Ke-An (XKA) is a traditional Chinese medicine (TCM) formula for the treatment of type 2 diabetes (T2D), and the effective ingredients and their targets as well as the mechanisms of XKA remain to be elucidated. In this study we investigated the therapeutic mechanisms of XKA in the treatment of T2D in mice using a Fangjiomics approach.

METHODS

KKAy mice feeding on a high-fat diet were used as models of T2D, and were orally treated with XKA (0.75 or 1.5 g · kg(-1) · d(-1)) for 32 d. Microarray mRNA expression data were obtained from the livers of the mice. Differentially expressed genes (DEGs) were identified by reverse rate analysis and ANOVA analysis. The compounds in XKA were identified by LC-MS analysis or collected from TCM databases. The relationships between the compounds and targets were established by combining the DEGs with information derived from mining literature or herb target databases. Relevant pathways were identified through a Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis using WebGestalt.

RESULTS

The compound-target-pathway network based on compounds identified by LC-MS analysis (NCA) included 20 constituent compounds, 46 targets and 36 T2D-related pathways, whereas the compound-target-pathway network based on compounds collected from databases (NCD) consisted of 40 compounds, 68 targets and 21 pathways. In the treatment of T2D, XKA might act mainly by improving carbohydrate and lipid metabolism, as well as ameliorating insulin resistance, inflammation and diabetic vascular complications.

CONCLUSION

The network-based approach reveals complex therapeutic mechanisms of XKA in the treatment of T2D in mice that involve numerous compounds, targets, and signaling pathways.

Compound 13, an α1-selective small molecule activator of AMPK, inhibits Helicobacter pylori-induced oxidative stresses and gastric epithelial cell apoptosis

Half of the world's population experiences Helicobacter pylori (H. pylori) infection, which is a main cause of gastritis, duodenal and gastric ulcer, and gastric cancers. In the current study, we investigated the potential role of compound 13 (C13), a novel α1-selective small molecule activator of AMP-activated protein kinase (AMPK), against H. pylori-induced cytotoxicity in cultured gastric epithelial cells (GECs). We found that C13 induced significant AMPK activation, evidenced by phosphorylation of AMPKα1 and ACC (acetyl-CoA carboxylase), in both primary and transformed GECs. Treatment of C13 inhibited H. pylori-induced GEC apoptosis. AMPK activation was required for C13-mediated GEC protection. Inhibition of AMPK kinase activity by the AMPK inhibitor Compound C, or silencing AMPKα1 expression by targeted-shRNAs, alleviated C13-induced GEC protective activities against H. pylori. Significantly, C13 inhibited H. pylori-induced reactive oxygen species (ROS) production in GECs. C13 induced AMPK-dependent expression of anti-oxidant gene heme oxygenase (HO-1) in GECs. Zinc protoporphyrin (ZnPP) and tin protoporphyrin (SnPP), two HO-1 inhibitors, not only suppressed C13-mediated ROS scavenging activity, but also alleviated its activity in GECs against H. pylori. Together, these results indicate that C13 inhibits H. pylori-induced ROS production and GEC apoptosis through activating AMPK-HO-1 signaling.

Heme oxygenase-1 enhances autophagy in podocytes as a protective mechanism against high glucose-induced apoptosis

Injury and loss of podocytes play vital roles in diabetic nephropathy progression. Emerging evidence suggests autophagy, which is induced by multiple stressors including hyperglycemia, plays a protective role. Meanwhile, heme oxygenase-1 (HO-1) possesses powerful anti-apoptotic properties. Therefore, we investigated the impact of autophagy on podocyte apoptosis under diabetic conditions and its association with HO-1. Mouse podocytes were cultured in vitro; apoptosis was detected by flow cytometry. Transmission electron microscopy and biochemical autophagic flux assays were used to measure the autophagy markers microtubule-associated protein 1 light chain 3-II (LC3-II) and beclin-1. LC3-II and beclin-1 expression peaked 12-24h after exposing podocytes to high glucose. Inhibition of autophagy with 3-methyladenine or Beclin-1 siRNAs or Atg 5 siRNAs sensitized cells to apoptosis, suggesting autophagy is a survival mechanism. HO-1 inactivation inhibited autophagy, which aggravated podocyte injury in vitro. Hemin-induced autophagy also protected podocytes from hyperglycemia in vitro and was abrogated by HO-1 siRNA. Adenosine monophosphate-activated protein kinase phosphorylation was higher in hemin-treated and lower in HO-1 siRNA-treated podocytes. Suppression of AMPK activity reversed HO-1-mediated Beclin-1 upregulation and autophagy, indicating HO-1-mediated autophagy is AMPK dependent. These findings suggest HO-1 induction and regulation of autophagy are potential therapeutic targets for diabetic nephropathy.

Heme oxygenase-1 protects corexit 9500A-induced respiratory epithelial injury across species

The effects of Corexit 9500A (CE) on respiratory epithelial surfaces of terrestrial mammals and marine animals are largely unknown. This study investigated the role of CE-induced heme oxygenase-1 (HO-1), a cytoprotective enzyme with anti-apoptotic and antioxidant activity, in human bronchial airway epithelium and the gills of exposed aquatic animals. We evaluated CE-mediated alterations in human airway epithelial cells, mice lungs and gills from zebrafish and blue crabs. Our results demonstrated that CE induced an increase in gill epithelial edema and human epithelial monolayer permeability, suggesting an acute injury caused by CE exposure. CE induced the expression of HO-1 as well as C-reactive protein (CRP) and NADPH oxidase 4 (NOX4), which are associated with ROS production. Importantly, CE induced caspase-3 activation and subsequent apoptosis of epithelial cells. The expression of the intercellular junctional proteins, such as tight junction proteins occludin, zonula occludens (ZO-1), ZO-2 and adherens junctional proteins E-cadherin and Focal Adhesion Kinase (FAK), were remarkably inhibited by CE, suggesting that these proteins are involved in CE-induced increased permeability and subsequent apoptosis. The cytoskeletal protein F-actin was also disrupted by CE. Treatment with carbon monoxide releasing molecule-2 (CORM-2) significantly inhibited CE-induced ROS production, while the addition of HO-1 inhibitor, significantly increased CE-induced ROS production and apoptosis, suggesting a protective role of HO-1 or its reaction product, CO, in CE-induced apoptosis. Using HO-1 knockout mice, we further demonstrated that HO-1 protected against CE-induced inflammation and cellular apoptosis and corrected CE-mediated inhibition of E-cadherin and FAK. These observations suggest that CE activates CRP and NOX4-mediated ROS production, alters permeability by inhibition of junctional proteins, and leads to caspase-3 dependent apoptosis of epithelial cells, while HO-1 and its reaction products protect against oxidative stress and apoptosis.

Limb ischemic preconditioning protects against contrast-induced acute kidney injury in rats via phosphorylation of GSK-3β

Contrast-induced acute kidney injury (CI-AKI) resulting from the use of intravascular iodinated contrast media for diagnostic and interventional cardiovascular procedures is associated with substantial morbidity and mortality. Despite preventative measures intended to mitigate the risk of CI-AKI, there remains a need for a novel and effective therapeutic approach. Limb ischemic preconditioning (LIPC), where short-term ischemia/reperfusion is applied to an arm prior to administration of the contrast agent, has been shown in several trials to preserve renal function in patients at high risk for CI-AKI. However, the underlying mechanism by which this procedure provides renoprotection against contrast media insults is not known. Here, we explored the molecular mechanism(s) of LIPC-induced protection of the kidneys from CI-AKI, particularly the role of phosphorylated glycogen synthase kinase-3β (GSK-3β). We used a novel CI-AKI model consisting of 5/6 nephrectomized (NE) rats at 6 weeks after the ablative surgery. LIPC- or sham-treated rats were administered iohexol (10 ml/kg, 3.5 gI) via the tail vein. The results showed that LIPC protected the kidneys against iohexol-induced injury. This protective effect was accompanied by the attenuation of renal dysfunction, tubular damage, apoptosis, mitochondrial swelling, oxidative stress, and inflammation. Furthermore, LIPC-induced renoprotection was blocked via treatment with inhibitors of PI3K (wortmannin or LY294002), but not ERK (U0126 or PD98059). LIPC also increased the protein expression levels of phospho-Akt, phospho-GSK-3β, and nuclear Nrf2, and decreased the levels of nuclear NF-κB. A specific GSK-3β inhibitor (SB216763) mimicked this effect of LIPC, by inhibiting the opening of the mitochondrial permeability transition pore and reducing the levels of oxidative stress and inflammation via activation of Nrf2 and suppression of NF-κB. The above results demonstrate that LIPC induces protection against CI-AKI, making this procedure a promising strategy for preventing CI-AKI. In particular, this renoprotective effect involves the phosphorylation of GSK-3β.

Squamosamide derivative FLZ protects retinal pigment epithelium cells from oxidative stress through activation of epidermal growth factor receptor (EGFR)-AKT signaling

Reactive oxygen species (ROS)-mediated retinal pigment epithelium (RPE) cell apoptosis is attributed to age-related macular degeneration (AMD) pathogenesis. FLZ, a novel synthetic squamosamide derivative from a Chinese herb, Annona glabra, has displayed significant cyto-protective activity. In the current study, we explored the pro-survival effect of FLZ in oxidative stressed-RPE cells and studied the underlying signaling mechanisms. Our results showed that FLZ attenuated hydrogen peroxide (H2O2)-induced viability decrease and apoptosis in the RPE cell line (ARPE-19 cells) and in primary mouse RPE cells. Western blotting results showed that FLZ activated AKT signaling in RPE cells. The AKT-specific inhibitor, MK-2206, the phosphoinositide 3-kinase (PI3K)/AKT pan inhibitor, wortmannin, and AKT1-shRNA (short hairpin RNA) depletion almost abolished FLZ-mediated pro-survival/anti-apoptosis activity. We discovered that epidermal growth factor receptor (EGFR) trans-activation mediated FLZ-induced AKT activation and the pro-survival effect in RPE cells, and the anti-apoptosis effect of FLZ against H2O2 was inhibited by the EGFR inhibitor, PD153035, or by EGFR shRNA-knockdown. In conclusion, FLZ protects RPE cells from oxidative stress through activation of EGFR-AKT signaling, and our results suggest that FLZ might have therapeutic values for AMD.