Kazuyo Yamaji

Endocannabinoid, anandamide in gingival tissue regulates the periodontal inflammation through NF-κB pathway inhibition

Anandamide (AEA) exhibits anti‐inflammatory effects. However, its role in the periodontal field remains unknown. Here, we found that gingival crevicular fluid contained a detectable level of AEA. The cannabinoid receptors CB1 and CB2 were expressed by human gingival fibroblasts (HGFs), and markedly upregulated under pathological conditions. AEA significantly reduced the production of pro‐inflammatory mediators (IL‐6, IL‐8 and MCP‐1) induced by Porphyromonas gingivalis LPS in HGFs, and this effect was attenuated by AM251 and SR144528, selective antagonists of CB1 and CB2, respectively. Moreover, AEA completely blocked LPS‐triggered NF‐κB activation, implying that AEA may regulate hyperinflammatory reactions in periodontitis.

Ebselen inhibits NO-induced apoptosis of differentiated PC12 cells via inhibition of ASK1-p38 MAPK-p53 and JNK signaling and activation of p44/42 MAPK and Bcl-2

Ebselen, a selenium‐containing heterocyclic compound, prevents ischemia‐induced cell death. However, the molecular mechanism through which ebselen exerts its cytoprotective effect remains to be elucidated. Using sodium nitroprusside (SNP) as a nitric oxide (NO) donor, we show here that ebselen potently inhibits NO‐induced apoptosis of differentiated PC12 cells. This was associated with inhibition of NO‐induced phosphatidyl Serine exposure, cytochrome c release, and caspase‐3 activation by ebselen. Analysis of key apoptotic regulators during NO‐induced apoptosis of differentiated PC12 cells showed that ebselen blocks the activation of the apoptosis signaling‐regulating kinase 1 (ASK1), and inhibits phosphorylation of p38 mitogen‐activated protein kinase (MAPK) and c‐jun N‐terminal protein kinase (JNK). Moreover, ebselen inhibits NO‐induced p53 phosphorylation at Ser15 and c‐Jun phosphorylation at Ser63 and Ser73. It appears that inhibition of p38 MAPK and p53 phosphorylation by ebselen occurs via a thiol‐redox‐dependent mechanism. Interestingly, ebselen also activates p44/42 MAPK, and inhibits the downregulation of the antiapoptotic protein Bcl‐2 in SNP‐treated PC12 cells. Together, these findings suggest that ebselen protects neuronal cells from NO cytotoxicity by reciprocally regulating the apoptotic and antiapoptotic signaling cascades.

Effect of Leptin in Platelet and Endothelial Cells: Obesity and Arterial Thrombosis

We demonstrated that leptin showed effects on both platelets and endothelial cells through its functional receptor. These effects are the vector to inducing thrombotic tendency. Leptin concentrations used in our experiments correspond to that of leptin in the circulation of obese individuals. Thus we suggest that increased leptin may act as a risk factor for thrombosis in obese individuals.

Inhibition of Thrombin-Induced Vascular Endothelial Growth Factor Production in Human Neuroblastoma (NB-1) Cells by Argatroban

Thrombin, a serine protease that plays a pivotal role in blood coagulation, wound healing, and angiogenesis, has also been implicated in the mitogenesis of various cell types. Previously, we showed that thrombin and the thrombin receptor agonist peptide (TRAP-14; SFLLRNPNDKYEPF) for protease-activated receptor 1 (PAR1) induce vascular endothelial growth factor (VEGF) secretion in PC-12 cells. In this study, we show that thrombin and TRAP-14 also stimulate VEGF secretion in the human NB-1 neuroblastoma cells. In these cells, we further show that thrombin-induced VEGF secretion was blocked by cycloheximide and actinomycin D, indicating that de novo protein synthesis is essential for this process. Reduced thrombin-induced VEGF secretion upon treatment with LY294002, calphostin C, or BAPTA, further suggests that the process is dependent on phosphatidyl-inositol-3-kinase, protein kinase C, and calcium. However, the complete loss of thrombin-induced VEGF production upon treatment with argatroban, a derivative of arginine and a potent anticoagulant/antithrombin agent, supports the notion that argatroban serves as a useful therapeutic tool for thrombin-associated pathologic conditions. Here, it appears that argatroban may be effective in controlling disorders linked to thrombin-induced VEGF production in neuronal cells.

Anti-atherogenic effects of an egg yolk-enriched garlic supplement

It has been suggested that oxidation of low-density lipoprotein (LDL) plays an important role in the initiation and progression of atherosclerosis. In the present study, we determined the anti-atherogenic effects of egg yolk-enriched garlic powder (EGP), which has been used as a traditional health-promoting food in southern Japan since ancient times, on LDL oxidation and oxidant stress-induced cell injury models. We confirmed that EGP inhibits copper-induced LDL oxidation in a dose-dependent manner. We also observed that pretreatment of EGP significantly suppressed the production of peroxides in HL60 cells and protected endothelial cells from hydrogen peroxide-induced cell injury. These findings might, in part, be ascribed to the biodistribution of garlic compounds and egg yolk interaction, and suggest that EGP might be useful in the prevention of atherosclerosis.

Radical Scavenging Activity of Kurozu (Brewed Rice Vinegar) on 1,1-Diphenyl-2-picrylhydrazyl and Its Antioxidant Effect on Human Low-density Lipoprotein.

くろずは鹿児島県に伝わる独特の製法による米酢であり, 健康食品として長期間用いられてきた。本研究においてわれわれはくろずのDPPHラジカル消去活性と, ヒトLDLにおける抗酸化作用について検討した。われわれはくろずがDPPHラジカルを直接消去することを明らかにし, また, 銅イオン惹起LDL酸化反応を濃度依存的に抑制することを明らかにした。これらの結果ば, くろずの摂取が生体内酸化を抑制し, 動脈硬化の発症を抑制しうることを示唆していると考えられる。