Da-wei Li

Strategy to Suppress Oxidative Damage-Induced Neurotoxicity in PC12 Cells by Curcumin: the Role of ROS-Mediated DNA Damage and the MAPK and AKT Pathways

Oxidative damage plays a key role in causation and progression of neurodegenerative diseases. Inhibition of oxidative stress represents one of the most effective ways in treating human neurologic diseases. Herein, we evaluated the protective effect of curcumin on PC12 cells against H2O2-induced neurotoxicity and investigated its underlying mechanism. The results indicated that curcumin pre-treatment significantly suppressed H2O2-induced cytotoxicity, inhibited the loss of mitochondrial membrane potential (Δψm) through regulation of Bcl-2 family expression, and ultimately reversed H2O2-induced apoptotic cell death in PC12 cells. Attenuation of caspase activation, poly(ADP-ribose) polymerase (PARP) cleavage, DNA damage, and accumulation of reactive oxygen species (ROS) all confirmed its protective effects. Moreover, curcumin markedly alleviated the dysregulation of the MAPK and AKT pathways induced by H2O2. Taken together, our findings suggest that the strategy of using curcumin could be a highly effective way in combating oxidative damage-mediated human neurodegenerative diseases.

Enhanced Therapeutic Potential of Nano-Curcumin Against Subarachnoid Hemorrhage-Induced Blood-Brain Barrier Disruption Through Inhibition of Inflammatory Response and Oxidative Stress

Curcumin and nano-curcumin both exhibit neuroprotective effects in early brain injury (EBI) after experimental subarachnoid hemorrhage (SAH). However, the mechanism that whether curcumin and its nanoparticles affect the blood–brain barrier (BBB) following SAH remains unclear. This study investigated the effect of curcumin and the poly(lactide-co-glycolide) (PLGA)-encapsulated curcumin nanoparticles (Cur-NPs) on BBB disruption and evaluated the possible mechanism underlying BBB dysfunction in EBI using the endovascular perforation rat SAH model. The results indicated that Cur-NPs showed enhanced therapeutic effects than that of curcumin in improving neurological function, reducing brain water content, and Evans blue dye extravasation after SAH. Mechanically, Cur-NPs attenuated BBB dysfunction after SAH by preventing the disruption of tight junction protein (ZO-1, occludin, and claudin-5). Cur-NPs also up-regulated glutamate transporter-1 and attenuated glutamate concentration of cerebrospinal fluid following SAH. Moreover, inhibition of inflammatory response and microglia activation both contributed to Cur-NPs’ protective effects. Additionally, Cur-NPs markedly suppressed SAH-mediated oxidative stress and eventually reversed SAH-induced cell apoptosis in rats. Our findings revealed that the strategy of using Cur-NPs could be a promising way in improving neurological function in EBI after experimental rat SAH.

Attenuation of Cisplatin-Induced Neurotoxicity by Cyanidin, a Natural Inhibitor of ROS-Mediated Apoptosis in PC12 Cells

Cisplatin-based chemotherapy in clinic is severely limited by its adverse effect, including neurotoxicity. Oxidative damage contributes to cisplatin-induced neurotoxicity, but the mechanism remains unclearly. Cyanidin, a natural flavonoid compound, exhibits powerful antioxidant activity. Hence, we investigated the protective effects of cyanidin on PC12 cells against cisplatin-induced neurotoxicity and explored the underlying mechanisms. The results showed that cisplatin-induced cytotoxicity was completely reversed by cyanidin through inhibition of PC12 cell apoptosis, as proved by the attenuation of Sub-G1 peak, PARP cleavage, and caspases-3 activation. Mechanistically, cyanidin significantly inhibited reactive oxygen species (ROS)-induced DNA damage in cisplatin-treated PC12 cells. Our findings revealed that cyanidin as an apoptotic inhibitor effectively blocked cisplatin-induced neurotoxicity through inhibition of ROS-mediated DNA damage and apoptosis, predicating its therapeutic potential in prevention of chemotherapy-induced neurotoxicity.Graphical AbstractCisplatin caused DNA damage, activated p53, and subsequently induced PC12 cells apoptosis by triggering ROS overproduction. However, cyanidin administration effectively inhibited DNA damage, attenuated p53 phosphorylation, and eventually reversed cisplatin-induced PC12 cell apoptosis through inhibition ROS accumulation.

Intranasal Delivery of Granulocyte Colony-Stimulating Factor Enhances Its Neuroprotective Effects Against Ischemic Brain Injury in Rats

Granulocyte colony-stimulating factor (G-CSF) is a hematopoietic growth factor with strong neuroprotective properties. However, it has limited capacity to cross the blood-brain barrier and thus potentially limiting its protective capacity. Recent studies demonstrated that intranasal drug administration is a promising way in delivering neuroprotective agents to the central nervous system. The current study therefore aimed at determining whether intranasal administration of G-CSF increases its delivery to the brain and its neuroprotective effect against ischemic brain injury. Transient focal cerebral ischemia in rat was induced with middle cerebral artery occlusion. Our resulted showed that intranasal administration is 8–12 times more effective than subcutaneous injection in delivering G-CSF to cerebrospinal fluid and brain parenchyma. Intranasal delivery enhanced the protective effects of G-CSF against ischemic injury in rats, indicated by decreased infarct volume and increased recovery of neurological function. The neuroprotective mechanisms of G-CSF involved enhanced upregulation of HO-1 and reduced calcium overload following ischemia. Intranasal G-CSF application also promoted angiogenesis and neurogenesis following brain ischemia. Taken together, G-CSF is a legitimate neuroprotective agent and intranasal administration of G-CSF is more effective in delivery and neuroprotection and could be a practical approach in clinic.

Induction of G1 Cell Cycle Arrest in Human Glioma Cells by Salinomycin Through Triggering ROS-Mediated DNA Damage In Vitro and In Vivo

Chemotherapy has always been one of the most effective ways in combating human glioma. However, the high metastatic potential and resistance toward standard chemotherapy severely hindered the chemotherapy outcomes. Hence, searching effective chemotherapy drugs and clarifying its mechanism are of great significance. Salinomycin an antibiotic shows novel anticancer potential against several human tumors, including human glioma, but its mechanism against human glioma cells has not been fully elucidated. In the present study, we demonstrated that salinomycin treatment time- and dose-dependently inhibited U251 and U87 cells growth. Mechanically, salinomycin-induced cell growth inhibition against human glioma was mainly achieved by induction of G1-phase arrest via triggering reactive oxide species (ROS)-mediated DNA damage, as convinced by the activation of histone, p53, p21 and p27. Furthermore, inhibition of ROS accumulation effectively attenuated salinomycin-induced DNA damage and G1 cell cycle arrest, and eventually reversed salinomycin-induced cytotoxicity. Importantly, salinomycin treatment also significantly inhibited the U251 tumor xenograft growth in vivo through triggering DNA damage-mediated cell cycle arrest with involvement of inhibiting cell proliferation and angiogenesis. The results above validated the potential of salinomycin-based chemotherapy against human glioma.

Cyanidin suppresses amyloid beta-induced neurotoxicity by inhibiting reactive oxygen species-mediated DNA damage and apoptosis in PC12 cells

Amyloid beta (Aß)-induced oxidative stress is a major pathologic hallmark of Alzheimer′s disease. Cyanidin, a natural flavonoid compound, is neuroprotective against oxidative damage-mediated degeneration. However, its molecular mechanism remains unclear. Here, we investigated the effects of cyanidin pretreatment against Aß-induced neurotoxicity in PC12 cells, and explored the underlying mechanisms. Cyanidin pretreatment significantly attenuated Aß-induced cell mortality and morphological changes in PC12 cells. Mechanistically, cyanidin effectively blocked apoptosis induced by Aß, by restoring the mitochondrial membrane potential via upregulation of Bcl-2 protein expression. Moreover, cyanidin markedly protected PC12 cells from Aß-induced DNA damage by blocking reactive oxide species and superoxide accumulation. These results provide evidence that cyanidin suppresses Aß-induced cytotoxicity, by preventing oxidative damage mediated by reactive oxide species, which in turn inhibits mitochondrial apoptosis. Our study demonstrates the therapeutic potential of cyanidin in the prevention of oxidative stress-mediated Aß neurotoxicity.

Adoptive Regulatory T-cell Therapy Attenuates Subarachnoid Hemor-rhage-induced Cerebral Inflammation by Suppressing TLR4/NF-B Signaling Pathway

Inflammation is one major cause of poor outcomes of subarachnoid hemorrhage (SAH). The recent evidence suggested that adoptive regulatory T-cell (Treg) therapy conferred potential neuroprotection by suppressing cerebral inflammation against cerebral ischemia. Therefore, we proposed that Treg transfer might protect the brain against SAH by decreasing cerebral inflammation. In this study, we injected the autologous blood into cisterna magna twice to make the SAH model and administrated Tregs by vein to SAH rats. Intriguingly, adoptive transfer of Tregs significantly ameliorated SAH-induced brain edema and increased cerebral blood flow. Moreover, Treg-afforded cerebral protection was accompanied by suppressing SAH-induced cerebral inflammation. Concurrently, administration of Tregs attenuated the activation of the toll-like receptor 4 and nuclear factor-kappa B (TLR4/NF-κB) signaling pathway, which should be involved in the suppression of SAH-induced cerebral inflammation. Altogether, our study suggested that Treg adoptive transfer could attenuate SAH-induced cerebral inflammation by suppressing the activation of the TLR4/NF-κB signaling pathway, and thus provided new insights into the potent Treg cells-based therapy specifically targeting on post-SAH inflammatory dysregulation.

Determination of brain injury biomarkers by surface-enhanced Raman scattering using hollow gold nanospheres

The development of rapid, highly sensitive detection methods for neuron-specific enolase (NSE) and S100-β protein is very important as the levels of NSE and S100-β protein in the blood are closely related to brain injury. Therefore, we can use NSE and S100-β protein concentration detection to realize the preliminary judgment of brain injury. In this paper, we report that a simple label-free three dimensional hierarchical plasmonic nano-architecture has been designed for the sensitive surface-enhanced Raman scattering immunosensor detection of NSE and S100-β. Owing to the active group of the hollow gold nanospheres (HAuNPs), the redox molecules 4-mercaptobenzoic acid (4-MBA) and Nile blue A (NBA) absorb antibodies and provide signal generation. The prepared HAuNPs@4-MBA and HAuNPs@NBA are used as probes to easily construct a surface-enhanced Raman scattering immunosensor. When protein biomarkers are present, the sandwich nanoparticles are captured over the substrate, forming a confined plasmonic field, leading to an enhanced electromagnetic field in intensity and in space. As a result, the Raman reporter molecules are exposed to a high density of “hot spots”, which remarkably amplify the Raman signal, improving the sensitivity of the surface-enhanced Raman scattering immunosensor. Under the optimized conditions, the linear range of the proposed immunosensor is from 0.2 to 22 ng mL−1 for both NSE and S100-β. The lowest detectable concentration is 0.1 and 0.06 ng mL−1 for NSE and S100-β, respectively. The assay results for serum samples with the proposed method were in a good agreement with the standard enzyme-linked immunosorbent assay method. The proposed immunosensor is promising in clinical diagnosis. This method, which utilizes the surface-enhanced Raman scattering of HAuNPs, has great potential in the detection of biomarkers, which are vital in medical diagnoses and disease monitoring.

SERS Based protocol Flow Glass-hemostix for Detection of Neuron-Specific Enolase in Blood Plasma

An inexpensive and disposable lateral flow glass-hemostix (FGH) has been developed as an immunoassay, in which surface-enhanced Raman scattering (SERS) is utilized for sensing signal transduction. Gold nanocage@Raman reporter nanoparticles are developed as SERS tags, which is the key to the high sensitivity of the device. Compared with ELISA, the SERS-FGH exhibits superior performance in terms of sensitivity and limit of detection (LOD) in a blood plasma-containing sample matrix. In addition, the SERS-FGH has been successfully used for the detection of neuron-specific enolase (NSE), a traumatic brain injury (TBI) protein biomarker, in diluted blood plasma samples, achieving a LOD of 0.74 ng mL−1. Moreover, the SERS-FGH was successfully employed to measure the NSE level in clinical blood plasma samples taken from identified TBI patients. This work demonstrates that the SERS-FGH has great potential in assisting screening of TBI patients in the point-of-care setting.

Combined Strategy of Radioactive 125I Seeds and Salinomycin for Enhanced Glioma Chemo-radiotherapy: Evidences for ROS-Mediated Apoptosis and Signaling Crosstalk

Radioactive 125I seeds-based radiotherapy has achieved great success in treatment of human cancers. However, radioresistance and severe side effects badly limited its clinic application. Recently, chemoradiotherapy as a superior strategy has been rapidly developed and widely used in clinic. However, the underlying mechanism remains elusive. Herein, in the present study, a combined chemoradiation model of 125I seeds and salinomycin (SAL) in vitro and in vivo was designed, and the enhanced anticancer efficiency and mechanism were also evaluated in human glioma. The results showed that combined treatment of 125I seeds and SAL induced enhanced growth inhibition against human glioma cells through induction of cell apoptosis. Further investigation revealed that combined treatment of 125I seeds and SAL triggered enhanced DNA damage through inducing reactive oxide species (ROS) generation. Additionally, enhanced dysfunction of MAPKs and AKT pathways both contributed to combined treatment-induced growth inhibition against human glioma cells. Importantly, the U251 human glioma xenograft growth was effectively inhibited by combined treatment of 125I seeds and SAL by induction of cell apoptosis with involvement of inhibiting cell proliferation and angiogenesis. Taken together, our results indicated that combined treatment of 125I seeds and SAL achieved enhanced growth inhibition and apoptosis in human glioma in vitro and in vivo through triggering ROS-mediated DNA damage and regulation of MAPKs and AKT pathways, which validated that the combined strategy of using 125I seeds and SAL could be a highly efficient way to achieve enhanced glioma chemo-radiotherapy.