Yuan-Yen Chang

Oxidative stress is a major contributor to the development of age-related macular degeneration (AMD), and excessive oxidative stress can induce retinal pigment epithelium (RPE) dysfunction, apoptosis, and retinal degeneration. Nicotinamide adenine dinucleotide phosphate (NADPH) oxidase 2 (NOX2) is a major enzymatic source of reactive oxygen species (ROS); however, its mechanistic role in sodium iodate (NaIO₃)-induced oxidative injury remains unclear. Tetrahydrocurcumin (THC), the major metabolite of curcumin, exhibits potent antioxidant and cytoprotective activities, but its protective effects against AMD-associated retinal degeneration have not been fully elucidated. In the present study, we investigated whether THC protects against NaIO₃-induced ROS-mediated apoptosis in RPE cells through regulation of NOX2 signaling. In vitro, THC significantly attenuated NaIO₃-induced cytotoxicity and prevented apoptosis by suppressing hydrogen peroxide (H₂O₂) production and intracellular ROS accumulation in ARPE-19 cells. THC also preserved mitochondrial membrane potential by inhibiting the Src/p47^phox/NOX2 signaling pathway and subsequently attenuated mitochondria-mediated apoptotic signaling. Furthermore, THC markedly reduced the expression of apoptotic proteins, including Bax, cleaved caspase-3, and cleaved PARP, concomitantly with suppression of Ras/Raf/MEK/ERK signaling. Mechanistically, treatment with the selective NOX2 inhibitor GSK2795039 significantly attenuated NaIO₃-induced ROS accumulation and mitochondrial depolarization, while co-treatment with THC further enhanced these protective effects. In vivo, THC ameliorated NaIO₃-induced retinal structural abnormalities by preserving the outer nuclear layer (ONL), reducing caspase-3 expression, and improving pupillary light responses in mice. Collectively, these findings demonstrate that THC protects against NaIO₃-induced retinal degeneration through suppressing NOX2-dependent oxidative stress and downstream Ras/Raf/MEK/ERK-mediated apoptotic signaling, highlighting its potential as a therapeutic candidate for AMD and other oxidative stress-related retinal disorders.

Age-related macular degeneration (AMD) is a leading cause of blindness in the elderly, with oxidative stress a major causative factor. Orange peel, rich in polyphenols and flavonoids, possesses potent antioxidant and anti-inflammatory activities. This study evaluated the protective effects of an ultrasound-assisted aqueous extract (OPWE) of orange peel and its major components, hesperidin and hesperetin, against sodium iodate (NaIO₃)-induced retinal damage. Component identification was performed using 3D-HPLC and LC/MS, and the antioxidant capacity was determined using the DPPH and ABTS assays. In vitro, OPWE reduced oxidative stress, mitochondrial dysfunction, and apoptosis in NaIO₃-treated ARPE-19 cells through the PI3K/Akt and HIF-1α/BNIP3 pathways. Notably, hesperetin exhibited comparable protective effects to OPWE, restoring cell viability and inhibiting ROS production. In vivo, oral administration of OPWE maintained retinal morphology and function in mice induced by NaIO₃. These findings suggest that OPWE, especially hesperetin, is a promising natural candidate for preventing oxidative stress-related retinal degeneration and maintaining retinal health.

Tetrahydrocurcumin (THC), a major curcuminoid metabolite known for its antioxidant and anti-inflammatory properties, has potential for reducing brain inflammation. This study investigated THC's anti-inflammatory responses and molecular mechanisms against Pseudomonas aeruginosa LPS (P.a. LPS)-induced NLRP3 inflammasome and ROS-producing cell pyroptosis. In the current study, we showed that THC significantly attenuated P.a. LPS-induced inflammasome factor IL-18 production through lysosomal dysfunction and leakage of cathepsin B. Importantly, THC reduced the levels of NLRP3 inflammasome and pyroptosis-related proteins, including NLRP3, active caspase-1, ASC, N-GSDMD, and IL-18. We also demonstrate that the inhibition of NLRP3 inflammasome activation by THC is ROS-dependent, via inhibition of H₂O₂ production, SOD activity, and enhancement of GSH activity. Subsequently, we demonstrated that THC treatment significantly reduced LPS-induced phosphorylation of c-Jun N-terminal kinase (JNK), p38 mitogen-activated protein kinase (MAPK), and increased heme oxygenase-1 (HO-1) expression in BV-2 cells. Furthermore, we used MAPKs (SB203580, SP600125, and U0126) and HO-1 (SnPP) inhibitors to demonstrate that THC modulated inflammasome-mediated pyroptosis may be related to p38 and JNK MAPK and HO-1-dependent inflammatory signaling. Overall, THC can inhibit ROS-triggered NLRP3 inflammasome-mediated pyroptosis by promoting GSH activity and HO-1 expression via modulating the p38 and JNK signaling pathways in P.a. LPS-treated BV-2 cells.

Age‐related macular degeneration (AMD), a leading cause of blindness, is characterized by mitochondrial dysfunction of retinal pigment epithelium (RPE) cells. EUK‐134 is a mimetic of SOD2 and catalase, widely used for its antioxidant properties in models of light‐induced damage or oxidative stress. However, its effects on the retina are not yet clear. Here, we investigated the capability of EUK‐134 in averting AMD using sodium iodate (NaIO₃)‐induced Balb/c mouse and ARPE‐19 cells (adult RPE cell line). In vivo, EUK‐134 effectively antagonized NaIO₃‐induced retinal deformation and prevented outer and inner nuclear layer thinning. In addition, it was found that the EUK‐134‐treated group significantly down‐regulated the expression of cleaved caspase‐3 compared with the group treated with NaIO₃ alone. Our results found that EUK‐134 notably improved cell viability by preventing mitochondrial ROS accumulation‐induced membrane potential depolarization‐mediated apoptosis in NaIO₃‐inducted ARPE‐19 cells. Furthermore, we found that EUK‐134 could inhibit p‐ERK, p‐p38, p‐JNK, p‐p53, Bax, cleaved caspase‐9, cleaved caspase‐3, and cleaved PARP by increasing Bcl‐2 protein expression. Additionally, we employed MAPK pathway inhibitors by SB203580 (a p38 inhibitor), U0126 (an ERK inhibitor), and SP600125 (a JNK inhibitor) to corroborate the aforementioned observation. The results support that EUK‐134 may effectively prevent mitochondrial oxidative stress‐mediated retinal apoptosis in NaIO₃‐induced retinopathy.

Previous studies showed that NaIO₃ can induce oxidative stress-mediated retinal pigment epithelium (RPE) damage to simulate age-related macular degeneration (AMD). Lemon peel is rich in antioxidants and components that can penetrate the blood–retinal barrier, but their role in retinal oxidative damage remains unexplored. Here, we explore the protection of lemon peel ultrasonic-assisted water extract (LUWE), containing large amounts of flavonoids and polyphenols, against NaIO₃-induced retinal degeneration. We initially demonstrated that LUWE, orally administered, prevented retinal distortion and thinning on the inner and outer nuclei layers, downregulating cleaved caspase-3 protein expression in RPE cells in NaIO₃-induced mice. The effect of LUWE was achieved through the suppression of apoptosis and the associated proteins, such as cleaved PARP and cleaved caspase-3, as suggested by NaIO₃-induced ARPE-19 cell models. This is because LUWE reduced reactive oxygen species-mediated mitochondrial fission via regulating p-Drp-1 and Fis1 expression. We further confirmed that LUWE suppresses the expression of p-MEK-1/2 and p-ERK-1/2 in NaIO₃-induced ARPE-19 cells, thereby providing the protection described above, which was confirmed using PD98059 and U0126. These results indicated that LUWE prevents mitochondrial oxidative stress-mediated RPE damage via the MEK/ERK pathway. Elucidation of the molecular mechanism may provide a new protective strategy against retinal degeneration.

Previous studies have indicated that NaIO ₃ induces intracellular reactive oxygen species (ROS) production and has been used as a model for age-related macular degeneration (AMD) due to the selective retinal pigment epithelium (RPE) cell damage it induces.

Lead (Pb) is nonbiodegradable and toxic to the lungs. To investigate the potential mechanisms of Pb‐induced reactive oxygen species (ROS) accumulation and cell death in the lungs, human non‐small lung carcinoma H460 cells were stimulated with Pb(NO ₃ ) ₂ in this study. The results showed that Pb(NO ₃ ) ₂ stimulation increased cell death by inducing cell apoptosis which showed a reduced Bcl‐2 expression and an enhanced caspase 3 activation. Pb(NO ₃ ) ₂ also caused the production of H ₂ O ₂ in H460 cells that triggering the buildup of ROS and mitochondrial membrane potential loss. We found that Pb(NO ₃ ) ₂ modulates oxidoreductive activity through reduced the glutathione‐disulfide reductase and glutathione levels in Pb(NO ₃ ) ₂ ‐exposed H460 cells. Furthermore, the superoxide dismutase (SOD) upstream molecule sirtuin 3 (SIRT3) was increased with Pb(NO ₃ ) ₂ dose. Collectively, these results demonstrate that Pb(NO ₃ ) ₂ promotes lung cell death through SIRT3/SOD‐mediated ROS accumulation and mitochondrial dysfunction.

Fine particulate matter (PM2.5) is the critical cause of lung cancer and can further promote tumor cell migration and invasion. This study investigated the effects of luteolin, an antiangiogenic flavonoid agent, on blocking aqueous extract PM2.5-prompted cancer progression. We observed that luteolin reduced cell migration and the expression of pro-metastatic factors pro-matrix metalloproteinase (MMP)-2 and intercellular adhesion molecule (ICAM)-1 in PM2.5-exposed H460 lung cancer cells. Luteolin treatment also reduced the transduction of PM2.5-induced epidermal growth factor receptor (EGFR)-phosphatidylinositol 3-kinase (PI3K)-protein kinase B (AKT) cascade signaling. Furthermore, the reduction of MMP-2 expression and ICAM-1 production by luteolin in PM2.5-stimulated H460 cells is EGFR-PI3K-AKT pathway dependent. These results suggest that luteolin exhibits antitumor progression by inhibiting EGFR-PI3K-AKT pathway.

Encephalitis is a rare brain inflammation that is most commonly caused by a viral infection. In this study, we first use an in vivo imaging system (IVIS) to determine whether NF-κBp-luciferase expression could be detected in the brain of pseudorabies virus (PRV)-infected NF-κBp-luciferase mice and to evaluate proinflammatory mediators in a well-described mouse model of PRV encephalitis. In in vitro studies, we used murine microglia (BV-2) cells to demonstrate the PRV-induced encephalitis model entailing the activation of microglia cells. The results indicate that PRV-induced neuroinflammation responses through the induction of IL-6, TNF-α, COX-2, and iNOS expression occurred via the regulation of NF-κB expression in BV-2 cells. In in vivo studies, compared with MOCK controls, the mice infected with neurovirulent PRV exhibited significantly elevated NF-κB transcription factor activity and luciferase protein expression only in the brain by IVIS. Mild focal necrosis was also observed in the brain. Further examination revealed biomarkers of inflammation, including inducible cyclooxygenase (COX)-2, inducible nitric oxide synthase (iNOS), and tumor necrosis factor (TNF)-α and interleukin (IL)-6, both of which constituted proinflammatory cytokines. PRV infection stimulated inflammation and COX-2 and iNOS expression of IL-6 and TNF-α. The presented results herein suggest that PRV induces iNOS and COX-2 expression in the brain of NF-κBp–luciferase mice via NF-κB activation. In conclusion, we used NF-κBp-luciferase mice to establish a specific virus-induced encephalitis model via PRV intranasal infection. In the future, this in vivo model will provide potential targets for the development of new therapeutic strategies focusing on NF-κB inflammatory biomarkers and the development of drugs for viral inflammatory diseases.