Protective mechanisms of Taiwanese green propolis toward high glucose-induced inflammation via NLRP3 inflammasome signaling pathway in human gingival fibroblasts.

OBJECTIVE: To investigate protective effects of Taiwanese green propolis (TGP) against high glucose-induced inflammatory responses in human gingival fibroblasts (HGFs) through NLRP3 inflammasome signaling pathway. BACKGROUND: NLRP3 inflammasome has been implicated in the progression of both diabetes mellitus and periodontitis, suggesting a common potential therapeutic target for these diseases. Propolis is renowned for various biological activities, particularly anti-inflammation and antioxidant, representing a promising therapy for many conditions. However, underlying mechanisms remain unclear. METHODS: The cytotoxicity of TGP was evaluated by cell viability assay. The mRNA levels and protein expression or secretion of various inflammatory molecules and NLRP3 inflammasome-related molecules in high glucose-exposed HGFs with or without pretreatment of TGP (5 µg/ml) were determined by real-time PCR and western blot or specific kits, respectively. Intracellular and mitochondrial ROS measurements, NADPH oxidase activity determination, and subcellular fractions were performed to assess ROS generation. The transcriptional activity of NF-κB was measured by luciferase reporter kit. The signaling components were further differentiated using pharmacological inhibitors of ROS and small interfering RNAs of TLR2, TLR4, or NF-κB. RESULTS: High glucose could induce IL-1ß-driven inflammatory responses in HGFs via the activation of NLRP3 inflammasome regulated by TLR2/TLR4 coupled ROS in NF-κB-dependent manner. TGP had no adverse impact on the cell viability of HGFs at concentrations no greater than 10 µg/ml, and could exert inhibitory effects on high glucose-induced inflammatory responses via the interruption of NLRP3 inflammasome signaling pathway. CONCLUSION: Taiwanese green propolis could elicit protective effects against IL-1ß-driven inflammation in high glucose-exposed HGFs through TLR2/TLR4 combined ROS/NF-κB/NLRP3 inflammasome pathway.

Exposure to polystyrene microplastics impairs hippocampus-dependent learning and memory in mice.

Microplastics (MPs) pollution has become a serious environmental issue worldwide, but its potential effects on health remain unknown. The administration of polystyrene MPs (PS-MPs) to mice for eight weeks impaired learning and memory behavior. PS-MPs were detected in the brain especially in the hippocampus of these mice. Concurrently, the hippocampus had decreased levels of immediate-early genes, aberrantly enhanced synaptic glutamate AMPA receptors, and elevated neuroinflammation, all of which are critical for synaptic plasticity and memory. Interestingly, ablation of the vagus nerve, a modulator of the gut-brain axis, improved the memory function of PS-MPs mice. These results indicate that exposure to PS-MPs in mice alters the expression of neuronal activity-dependent genes and synaptic proteins, and increases neuroinflammation in the hippocampus, subsequently causing behavioral changes through the vagus nerve-dependent pathway. Our findings shed light on the adverse impacts of PS-MPs on the brain and hippocampal learning and memory.

Preparation, characterizations and anti-pollutant activity of 7,3',4'-trihydroxyisoflavone nanoparticles in particulate matter-induced HaCaT keratinocytes.

BACKGROUND: 7,3',4'-Trihydroxyisoflavone (734THI), a secondary metabolite derived from daidzein in soybean, possesses several biological activities, including antioxidant, skin whitening and anti-atopic dermatitis properties, but the poor aqueous solubility of 734THI has limited its application in medicine and cosmetic industry. METHODS: The aim of the present study was to improve the physicochemical properties of 734THI using planetary ball mill preparation under a solvent-free process to improve its solubility and anti-pollutant activity. RESULTS: 734THI nanoparticle powder (734THIN) was successfully prepared by the planetary ball mill technique using polyvinylpyrrolidone K30 as the excipient. 734THIN effectively increased the aqueous solubility and cellular uptake of 734THI by improving its physicochemical properties, including particle size reduction, crystalline-amorphous transformation and intermolecular hydrogen bonding with polyvinylpyrrolidone K30. In addition, 734THIN inhibited the overexpression of COX-2 and MMP-9 by downregulating MAPK pathway signaling in particulate matter-exposed HaCaT keratinocytes, while raw 734THI in PBS with low aqueous solubility did not show any anti-inflammatory or antiaging activity. CONCLUSION: 734THIN may be used as an additive in anti-pollutant skin care products for preventing particulate matter-induced inflammation and aging in skin.

Dysregulated expression of antioxidant enzymes in polyethylene particle-induced periprosthetic inflammation and osteolysis.

Small wear particles (0.1-10 µm) in total joint replacement are generally considered as the major causative agent leading to periprosthetic inflammation and osteolysis. However, little is known about the roles of larger wear particles (10-100 µm) in periprosthetic inflammation and osteolysis. Additionally, although ample studies demonstrated that increased oxidative stress is critically involved in particle-induced inflammation and osteolysis, detailed changes in antioxidant enzymes expression in the disease development remain largely unclear. Herein, we used a rat knee prosthesis model to assess effects of polyethylene (PE) particles (20-60 µm) on the levels of oxidative stress markers such as malondialdehyde (MDA) and total antioxidant capacity (TAC) in blood plasma, and on the expression profiles of antioxidant enzymes in knee joint tissues. In combination with a forced-exercise intervention for all surgical rats, we found that the rat groups treated with both artificial joint and PE particles exhibited higher MDA levels and lower TAC levels, together with lower levels of physical activity and higher levels of inflammatory markers, than the sham group and the groups receiving artificial joint or PE particles alone at weeks 20-24 post-operatively. Dose-response relationships between the exposure to PE particles and the induction of oxidative stress and inflammation were also observed in the artificial joint/PE groups. Under such conditions, we unexpectedly found that most of antioxidant enzymes displayed pronounced up-regulation, with concomitant induction of inflammatory and osteoclast-inducing factors (including IL-1ß, NF-κB and RANKL), in the artificial joint/PE groups as compared to the sham, artificial joint only, or PE only group. Only a few antioxidant enzymes including SOD2 and GPx2 showed down-regulation. Collectively, our findings demonstrate that implantation of artificial joint along with large PE particles synergistically trigger the induction of oxidative stress; however, down-regulation of many antioxidant enzymes may not necessarily occur during the disease development.

Design of acid-responsive polymeric nanoparticles for 7,3',4'-trihydroxyisoflavone topical administration.

7,3',4'-Trihydroxyisoflavone (734THIF) is a secondary metabolite of daidzein and has been recently found to possess antioxidant, melanin inhibition, and skin cancer chemopreventive activities. However, the poor water solubility of 734THIF impedes its absorption and skin penetration and, therefore, limits its pharmacological effects when applied topically to the skin. We seek to use the nanoprecipitation method to prepare optimal eudragit E100 (EE)-polyvinyl alcohol (PVA)-loaded 734THIF nanoparticles (734N) to improve its physicochemical properties and thereby increase its water solubility, skin penetration, and biological activities. EE-PVA-loaded 734THIF nanoparticles (734N) were prepared, and their morphology and particle size were evaluated using a particle size analyzer and by electron microscopy. The drug loading and encapsulation efficiencies and in vitro solubility were determined using high-performance liquid chromatography. Hydrogen-bond formation was evaluated by (1)H-nuclear magnetic resonance and Fourier transform infrared spectroscopy, and crystalline-to-amorphous transformation was determined by differential scanning calorimetry and X-ray diffractometry. In vitro skin penetration was analyzed using fresh pig skin mounted on Franz diffusion cells, and cytotoxicity against human keratinocyte HaCaT cells was evaluated using the MTT assay. Antioxidant activity was determined by 2,2-diphenyl-1-picrylhydrazyl-free radical scavenging ability. EE-PVA-loaded 734THIF nanoparticles showed good drug loading and encapsulation efficiencies and were characterized by improved physicochemical properties, including reduction in particle size, amorphous transformation, and intermolecular hydrogen-bond formation. This is associated with increased water solubility and enhanced in vitro skin penetration, with no cytotoxicity toward HaCaT cells. In addition, 734THIF nanoparticles retained their antioxidant activity. In conclusion, 734THIF nanoparticles are characterized by improved physicochemical properties, increased water solubility, and enhanced skin penetration, and these may have potential use in the future as a topical delivery formulation for the treatment of skin diseases.

Curcumin nanoparticles ameliorate ICAM-1 expression in TNF-α-treated lung epithelial cells through p47 (phox) and MAPKs/AP-1 pathways.

Upregulation of intercellular adhesion molecule-1 (ICAM-1) involves adhesions between both circulating and resident leukocytes and the human lung epithelial cells during lung inflammatory reactions. We have previously demonstrated that curcumin-loaded polyvinylpyrrolidone nanoparticles (CURN) improve the anti-inflammatory and anti-oxidative properties of curcumin in hepatocytes. In this study, we focused on the effects of CURN on the expression of ICAM-1 in TNF-α-treated lung epithelial cells and compared these to the effects of curcumin water preparation (CURH). TNF-αinduced ICAM-1 expression, ROS production, and cell-cell adhesion were significantly attenuated by the pretreatment with antioxidants (DPI, APO, or NAC) and CURN, but not by CURH, as revealed by western blot analysis, RT-PCR, promoter assay, and ROS detection and adhesion assay. In addition, treatment of TNF-α-treated cells with CURN and antioxidants also resulted in an inhibition of activation of p47 (phox) and phosphorylation of MAPKs, as compared to that using CURH. Our findings also suggest that phosphorylation of MAPKs may eventually lead to the activation of transcription factors. We also observed that the effects of TNF-α treatment for 30 min, which includes a significant increase in the binding activity of AP-1 and phosphorylation of c-jun and c-fos genes, were reduced by CURN treatment. In vivo studies have revealed that CURN improved the anti-inflammation activities of CURH in the lung epithelial cells of TNF-α-treated mice. Our results indicate that curcumin-loaded polyvinylpyrrolidone nanoparticles may potentially serve as an anti-inflammatory drug for the treatment of respiratory diseases.