Effects of virtual reality-based motor control training on inflammation, oxidative stress, neuroplasticity and upper limb motor function in patients with chronic stroke: a randomized controlled trial.

BACKGROUND: Immersive virtual reality (VR)-based motor control training (VRT) is an innovative approach to improve motor function in patients with stroke. Currently, outcome measures for immersive VRT mainly focus on motor function. However, serum biomarkers help detect precise and subtle physiological changes. Therefore, this study aimed to identify the effects of immersive VRT on inflammation, oxidative stress, neuroplasticity and upper limb motor function in stroke patients. METHODS: Thirty patients with chronic stroke were randomized to the VRT or conventional occupational therapy (COT) groups. Serum biomarkers including interleukin 6 (IL-6), intracellular adhesion molecule 1 (ICAM-1), heme oxygenase 1 (HO-1), 8-hydroxy-2-deoxyguanosine (8-OHdG), and brain-derived neurotrophic factor (BDNF) were assessed to reflect inflammation, oxidative stress and neuroplasticity. Clinical assessments including active range of motion of the upper limb and the Fugl-Meyer Assessment for upper extremity (FMA-UE) were also used. Two-way mixed analyses of variance (ANOVAs) were used to examine the effects of the intervention (VRT and COT) and time on serum biomarkers and upper limb motor function. RESULTS: We found significant time effects in serum IL-6 (p = 0.010), HO-1 (p = 0.002), 8-OHdG (p = 0.045), and all items/subscales of the clinical assessments (ps < 0.05), except FMA-UE-Coordination/Speed (p = 0.055). However, significant group effects existed only in items of the AROM-Elbow Extension (p = 0.007) and AROM-Forearm Pronation (p = 0.048). Moreover, significant interactions between time and group existed in item/subscales of FMA-UE-Shoulder/Elbow/Forearm (p = 0.004), FMA-UE-Total score (p = 0.008), and AROM-Shoulder Flexion (p = 0.001). CONCLUSION: This was the first study to combine the effectiveness of immersive VRT using serum biomarkers as outcome measures. Our study demonstrated promising results that support the further application of commercial and immersive VR technologies in patients with chronic stroke.

NADPH oxidase 4 is involved in the triethylene glycol dimethacrylate-induced reactive oxygen species and apoptosis in human embryonic palatal mesenchymal and dental pulp cells.

OBJECTIVES: Triethylene glycol dimethacrylate (TEGDMA) is a common component of resin-based dental composites and endodontic sealers. TEGDMA induces apoptosis in several types of cells. However, the mechanisms are not completely understood. The aim of this study was to investigate the mechanisms underlying TEGDMA-induced apoptosis in human embryonic palatal mesenchymal (HEPM) pre-osteoblasts and primary human dental pulp (HDP) cells. MATERIAL AND METHODS: Cell viability was examined after TEGDMA treatment. Cell cycle progression was checked by flow cytometry. Apoptotic cells were evaluated using terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick end labeling assay and visualized by fluorescence microscopy. Western blot analyses were performed to determine expressions of apoptosis-related proteins. The production of reactive oxygen species (ROS) was detected using flow cytometry. NADPH oxidase 4 (NOX4) expression levels were investigated using real-time quantitative polymerase chain reaction and Western blot analyses. RESULTS: TEGDMA increased cytosol cytochrome c levels and activated caspase-9 in HEPM and HDP cells. TEGDMA decreased the expression of anti-apoptotic protein Bcl-XL. TEGDMA-induced apoptosis was inhibited by caspase-9-specific inhibitor, anti-oxidants, NOX inhibitor, NOX4 inhibitor, and NOX4 small interfering RNA (siRNA). TEGDMA increased ROS production and upregulated NOX4 mRNA and protein expression. TEGDMA-induced intracellular ROS production was inhibited by NOX inhibitor and NOX4 inhibitor. CONCLUSIONS: We demonstrate significant involvement of NOX4 in the TEGDMA-induced ROS. NOX4-derived ROS subsequently induces mitochondrial cytochrome c release leading to apoptosis through activation of the intrinsic apoptotic pathway. CLINICAL RELEVANCE: NOX4 may be a potential target for strategies to prevent or ameliorate the TEGDMA-induced toxicity in HEPM and HDP cells.

EGCG blocks TGFß1-induced CCN2 by suppressing JNK and p38 in buccal fibroblasts.

OBJECTIVES: Transforming growth factor ß (TGFß) has been suggested as the main trigger for the increased collagen production and decreased matrix degradation pathways in oral submucous fibrosis (OSF). Connective tissue growth factor (CTGF/CCN2) and cyclooxygenase-2 (COX-2) were found to overexpress in OSF. The aim of this study was to investigate the molecular mechanism underlying the TGFß-induced CCN2 expressions in human buccal mucosal fibroblasts (BMFs) to identify the potential targets for drug intervention or chemoprevention of OSF. MATERIALS AND METHODS: TGFß-induced CCN2 expression and its signaling pathways were assessed by Western blot analyses in BMFs. RESULTS: TGFß1 stimulated CCN2 synthesis in BMFs. Pretreatment with c-Jun NH(2)-terminal kinase (JNK) inhibitor SP600125, p38 mitogen-activated protein kinase (MAPK) inhibitor SB203580, and activin receptor-like kinase 5 (ALK5) inhibitor SB431542 significantly reduced TGFß1-induced CCN2 synthesis. Epigallocatechin-3-gallate (EGCG) completely blocked TGFß1-induced CCN2 synthesis by inhibiting the phosphorylation of JNK and p38 MAPK. Prostaglandin E(2) (PGE(2)) inhibited the TGFß1-induced CCN2 synthesis in human fetal lung fibroblasts IMR90 but not in BMFs. CONCLUSIONS: The TGFß1-induced CCN2 synthesis in BMFs could be mediated by the ALK5, JNK, and p38 MAPK pathways. EGCG blocks TGFß1-induced CCN2 by suppressing JNK and p38 in BMFs. CLINICAL RELEVANCE: The exceptional signal transduction pathways of TGFß1-induced CCN2 production in BMFs contribute to the resistance of PGE(2) downregulation of CCN2 expression; therefore, the CTGF/CCN2 levels are maintained in the OSF tissues in the presence of COX-2. EGCG may serve as a useful agent in controlling OSF.

Epigallocatechin-3-gallate blocks triethylene glycol dimethacrylate-induced cyclooxygenase-2 expression by suppressing extracellular signal-regulated kinase in human dental pulp and embryonic palatal mesenchymal cells.

INTRODUCTION: Methacrylate resin-based materials could release components into adjacent environment even after polymerization. The major components leached include triethylene glycol dimethacrylate (TEGDMA). TEGDMA has been shown to induce the expression of cyclooxygenase-2 (COX-2). However, the mechanisms are not completely understood. The aims of this study were to investigate the molecular mechanism underlying TEGDMA-induced COX-2 in 2 oral cell types, the primary culture of human dental pulp (HDP) cells and the human embryonic palatal mesenchymal (HEPM) pre-osteoblasts, and to propose potential strategy to prevent or ameliorate the TEGDMA-induced inflammation in oral tissues. METHODS: TEGDMA-induced COX-2 expression and its signaling pathways were assessed by Western blot analyses in HDP and HEPM cells. The inhibition of TEGDMA-induced COX-2 protein expression using various dietary phytochemicals was investigated. RESULTS: COX-2 protein expression was increased after exposure to TEGDMA at concentrations as low as 5 µmol/L. TEGDMA-induced COX-2 expression was associated with reaction oxygen species, the extracellular signal-regulated kinase 1/2, and the p38 mitogen-activated protein kinase signaling pathways in HDP and HEPM cells. The activation of p38 mitogen-activated protein kinase was directly associated with reactive oxygen species. Epigallocatechin-3-gallate suppressed TEGDMA-induced COX-2 expression by inhibiting phosphorylation of extracellular signal-regulated kinase 1/2. CONCLUSIONS: Cells exposed to low concentrations of TEGDMA may induce inflammatory responses of the adjacent tissues, and this should be taken into consideration during common dental practice. Green tea, which has a long history of safe beverage consumption, may be a useful agent for the prevention or treatment of TEGDMA-induced inflammation in oral tissues.

Curcumin inhibits thrombin-stimulated connective tissue growth factor (CTGF/CCN2) production through c-Jun NH2-terminal kinase suppression in human gingival fibroblasts.

BACKGROUND: Connective tissue growth factor (CTGF/CCN2), associated with multiple human fibrotic diseases, is overexpressed in the tissue of gingival overgrowth. Although surgical excision is the current treatment modality for gingival overgrowth, the recurrent rate is high despite proper recall programs. Thrombin plays a key role in wound repair, remodeling, and fibrosis after injury and exerts profibrotic effects by activating protease-activated receptors (PARs). Curcumin [1,7-bis(4-hydroxy-3-methoxyphenyl)-1,6-heptadiene-3,5-dione] is a natural plant phenolic compound that possesses both anti-inflammatory and antioxidant properties. This study investigates the signaling pathway of thrombin-induced CCN2 expression and inhibition of CCN2 expression by curcumin. METHODS: The signaling pathway of thrombin-induced CCN2 expression in human gingival fibroblasts (HGFs) was studied using Western blot analysis. The CCN2 mRNA level was determined by quantitative reverse transcription-polymerase chain reaction. RESULTS: Thrombin induced CCN2 expression in HGFs by activating PAR1. Pretreatment with antioxidant N-acetyl-l-cysteine, apoptosis signal-regulating kinase 1 (ASK1) inhibitor thioredoxin, and c-Jun NH2-terminal kinase (JNK) inhibitor SP600125 (anthra[1,9-cd]pyrazol-6(2H)-one) significantly reduced thrombin-induced CCN2 expression in HGFs. Curcumin dose dependently inhibited thrombin-induced CCN2 expression through JNK suppression in HGFs. CONCLUSIONS: The results of this study suggest that thrombin-induced CCN2 expression may occur through PAR1, reactive oxygen species, ASK1, and JNK signaling in HGFs. Curcumin could effectively inhibit CCN2 expression through JNK suppression. These signaling events are important for wound healing and fibrosis. Additional research, including animal studies, is required to confirm the inhibiting role of curcumin in the development of gingival overgrowth.

Thrombin-stimulated connective tissue growth factor (CTGF/CCN2) production in human buccal mucosal fibroblasts: Inhibition by epigallocatechin-3-gallate.

BACKGROUND: Connective tissue growth factor (CTGF/CCN2) is associated with many human fibrotic disorders and was found to overexpress in oral submucous fibrosis (OSF). OSF is the result of persistent chemical irritation and microtrauma to oral mucosa from areca nut. Microtrauma could lead to the release of thrombin. METHODS: Thrombin-induced CCN2 expression and its signaling pathways were assessed by Western blot analyses in human buccal mucosal fibroblasts. RESULTS: Thrombin stimulated CCN2 synthesis in buccal mucosal fibroblasts via activation of protease-activated receptor-1. Pretreatment with antioxidant N-acetyl-L-cysteine, apoptosis signal-regulating kinase 1 inhibitor thioredoxin, and c-Jun NH(2) -terminal kinase inhibitor SP600125 significantly reduced thrombin-induced CCN2 synthesis. Epigallocatechin-3-gallate completely inhibited thrombin-induced CCN2 synthesis. CONCLUSION: Thrombin produced by microtrauma may contribute to the pathogenesis of OSF by up-regulating CCN2 expression. This effect could be mediated by protease-activated receptor-1, reactive oxygen species, apoptosis signal-regulating kinase 1, and c-Jun NH(2) -terminal kinase pathways and prevented by epigallocatechin-3-gallate.