Al though the changes in tooth morphology and hardness by hydrogen peroxide(H20 z) have been r‘epor‘.ted .‘ the pαr。o야t뻐ec야tive role of heme oxygenase-l(HO-l) against the cytotoxic effects of H202 has not been clarifïed i n human pulp cells ln this st udy. we investigated whether HO-l is involved in Hz0 2-induced cytoLox icity a nd examined the production 0 1' dentin sia lophosphoprotein(DSPP) and other mineralization markers‘ in hllman pu lp cells H202 decreased cell viabi lity, but increased HO-l and DSPP expression in a concentra tion and time dependent manner . Inhibitors of gllanylate cyclase. PI3K, ERK. and p38 MAP kinase blocked H202-indllced cytotoxicity and the expression of HO-l and DSPP mRNAs in pulp cells. These data suggest that the induction of HO-l by H202 in plllp cells plays a protective role against the cytotoxic effects 0 1' HzOz and stimulates DSPP expression‘ reslllting in prematllre odontoblast dilTerentiation throllgh pathways that involve cGMP‘ p38. and ERK.

Al t hough substance P(SP) , a potent pro- inflammatory peptide, is involved in inflammation and immune responses‘ t he eff'ect of SP on t he expression of macrophage inflammatory protein 3a (MIP- 3α CCL20) in periodontal liga ment(PDL) cell s a re unknown, Equally as enigmatic is the link between SP, t he stress protein heme oxygenase- l(HO-l) ‘ and CCL20 procluction, We investigated whether SP induces the release of chemokine CCL20 from immortal ized PDL(IPDL) ceJJ s‘ and fur ther c l a꺼 SP mediated pathways, We also examined the relationship between HO-l a ncl CCL20 by t reating PDL cells with SP, Incubating IPDL cells with SP increased expression of CCL20 mRNA a nd CCL20 protein in a dose-time dependent manner Highly selective p38 and ERKl/2 inhibitors abrogated SP-induced expression of CCL20 in IPDL cell s, SP is a lso responsible for ini t iating phosphorylation of I/C B, degradation of Iκ B‘ ancl activat ion of NF'-/C B, SP induced expression of HO-l in both a concentration- and time-dependent man nel ‘ and CCL20 refl ected s imilar patterns, The inductive effects o[ SP on HO- l and CCL20 wer e enhanced by HO- j inducer hemin and the membrane-permeable cGMP analog 8-bromo-cGMP, Conversely, this pathway was inJübited by t he 1-10난 inhi bitor zinc protoporphyrin IX(ZnPP IX) and the selective inl뼈itor of guanylate cyc1ase‘ lH-[l , 2, 4Joxad iazole[4‘ 3-aJquinoxal in-l-one (ODQ) , We report herein the pathway that connects SP along with other modulators 。f neuroimmunoregulationto the induction of HO-l and t he inflammatory mediator MIP-3a /CCL20 in IPDL cell s‘ which play an important role in the development 01' periodontitis or inflamrnation during orthodontic tooth movem

This study was to taken to demonstrate the effects of exogenous nitric oxide(NO) on hu rnan pu lp cell s ‘ In volvement of cyclic 3’, 5' -monophosphate(cGMP) in p버 paJ protection induced by herne oxygenase-l (J-lO-l) against NO-induced cytotoxicity , By use of Western blotting and cell viabi lity assay, we have examined the cytotoxicity and J-lO-l induction in pulp cells that were treated with NO donor ‘ S-nitroso-N-acetyl-D, L-penici 1 lamine(SNAP) , We have assessed wheathel' HQ--l contributes the cytoprotective effect against the cytotoxicity caused by NO, and inves tigated the l'elationship between HO-l and cGMP in the s ignaling pathway, SNAP decreased cell via bility but in creased HO-l expl'ession in a concentl'ation- and time一dependent manner in hurnan pu lp cells NO-induced cyto toxicity was inhibited in the presence of the hemin(inducer of HO-l) , whel'eas was en hanced in the pl'esence zinc protoporphyrin IX(ZnPP IX, HO-l inhibitor), thus Lhe NO-induced cytoLoxicity was cOl'related with HO- l expression. R‘ etreatment with a rnemhrane-permeable cGMP analog, 8-bromo-cGMP, restored cell death and enhanced the HO-l protein expression induced by SNAP, ln contrast‘ inhibition of guanylate cyclase by lI-l -[1,2,4] ox adiazole[ 4,3 口]quinoxalin-l-one(ODQ) pretreated pulp cells to 1 mM SNAP resulting in marked cytotoxicity , These findings , demonstrating a link between J-lO-l, regulated thl'ough the cGMP system and NO-induced cytotox.icity in huma띠 p버 p ceJls , suggesti ng a protective 1'ole of HO-l in pulp infl ammatory disease