Angiotensin II induced C reactive protein generation Inflammatory role of ...
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Atherosclerosis193(2007)292–298AngiotensinII-inducedC-reactiveproteingeneration:Inflammatoryroleofvascularsmoothmusclecellsinatherosclerosis
NingPenga,Jun-tianLiua,∗,Deng-fengGaob,RongLina,RuiLicaDepartmentofPharmacology,Xi’anJiaotongUniversitySchoolofMedicineandKeyLaboratory
ofEnvironmentandGenesRelatedtoDiseases,MinistryofEducation,PRChinabTheSecondAffiliatedHospitalofXi’anJiaotongUniversity,PRChina
cShaanxiProvincialPeople’sHospital,PRChina
Received31March2006;receivedinrevisedform21August2006;accepted2September2006Availableonline20October2006
AbstractBackground:AsthemajortargetofAngiotensinII(AngII)inthevesselwall,vascularsmoothmusclecells(VSMCs)areatentativesourcetoproduceC-reactiveprotein(CRP).However,itislargelyunknownifAngIIiscapableofinducingCRPproductioninVSMCs.Methodsandresults:AngIIinducedaconcentration-dependentreleaseofCRPinculturedratVSMCsasmeasuredbysandwichELISA.Real-timePCRrevealedthatAngIIsignificantlyupregulatedCRPmRNAlevelinvitro.AngII-inducedCRPgenerationinaorticVSMCswasalsoinvestigatedusingdouble-labeledfluorescentimmunohistochemistryandinsituhybridizationinsubchronicAngIIadministrationinrats.LosartanbutnotPD123319markedlyblockedtheAngII-inducedCRPproductioninculturedVSMCs,suggestingthatsucheffectwasmediatedviaAngIItype1receptor.Further,Westernblottinganalysisshowedthatmitogen-activatedproteinkinase(MAPK)activationwasobligatoryinAngII-inducedCRPproduction,sincespecificMAPKinhibitorPD098059almostabolishedtheaction.Conclusions:WeidentifiedthatAngIIiscapableofinducingCRPgenerationinVSMCs,inwhichAngIItype1receptorfollowedbyMAPKsignalpathwayisinvolved.ItstrengthenedtheroleofAngII-inducedCRPproductionbyVSMCsintheinflammatoryprocessinatherosclerosis.©2006ElsevierIrelandLtd.Allrightsreserved.
Keywords:Vascularsmoothmusclecells;AngiotensinII;C-reactiveprotein;Mitogen-activatedproteinkinase;Inflammation
1.IntroductionC-reactiveprotein(CRP)isasensitivesystemicindicationofinflammationandtissuedamage[1].Morespecifically,serumCRPisregardedasanimportantmarkerfortheriskofatherothromboticeventssincetheelevatedlevelofhighsen-sitiveCRPisassociatedwithriskofatherothromboticevents[2].AlargebodyofstudiessuggestedthatCRPisinvolvedinmanyprocessesofatherogenesisincludingendothelialcelldysfunction,mononuclearcelladhesion,foamcellformation,
∗Correspondingauthorat:DepartmentofPharmacology,Xi’anJiaotong
UniversitySchoolofMedicine,No.205ZhuqueSt.,Xi’an710061,PRChina.Tel.:+862982655188;fax:+862982655188.E-mailaddress:pharmacologyxjtu@yahoo.com(J.-t.Liu).
smoothmusclecellmigration,proliferationandformationofthefibrouscap[3].Hence,itisemerginglyrecognizedthatCRPisnotmerelyamarker,butalsoplaysadirectroleinatherosclerosis.AlthoughtheelevatedserumlevelofCRPispredom-inatelyproducedbyhepatocytes,growingstudieshaveexpandedthepossiblesourceforCRPtovarietyofcelltypesincludingepithelialcellsoftherespiratorytract[4],renalepithelium[5]aswellasneuronalcells[6].AlateststudyshowedthatculturedhumancoronaryarterysmoothmusclecellsynthesizesCRPinresponsetoinflammatorycytokines[7],whicharisesthepossibilitythatarterysmoothmusclecellsisasourceoflocallyproducedCRPinthearterialwall.GiventhatCRPexertsmultipleactivitiesinthepathologicalinflammationinatherosclerosis,thepotentialroleoflocally
0021-9150/$–seefrontmatter©2006ElsevierIrelandLtd.Allrightsreserved.doi:10.1016/j.atherosclerosis.2006.09.007N.Pengetal./Atherosclerosis193(2007)292–298293synthesizedCRPinthedevelopmentofatherosclerosis,thus,hasreceivedgreatinterests.AngiotensinII(AngII),animportantvasoactivepeptideoftherennin-angiotensinsystem,exertsnumerouseffectsonthecardiovascularsystem.EvidencehassuggestedtheimportantrolesofAngIIinvascularcellgrowthandtissueremodelingfollowingatherosclerosis,hypertensionandvascularinjury.Meanwhile,AngIIisalsoknowntobeapotentialproin-flammatoryfactor,sinceAngIIinducesinterleukin-6[8]andtumornecrosisfactor[9]releasefromvascularsmoothmusclecells(VSMCs).Furthermore,angiotensinconvertingenzymeinhibitors(ACEI)andangiotensinIIreceptortypeIblockers(ARB)areknowntomodulatetheinflammatorypro-cessesandpossiblytheatheroscleroticprocess[10].Thus,itisinferredthatAngIImayhavethecapabilitytoelicitinflam-matoryprocessintheatherogenesis.AlthoughthesestudieshaveuncoveredthecrucialrolesforAngIIandCRPinthepathogenesisofatherosclerosis,thecrosstalkbetweenAngIIandCRP,thetwocrucialfactorsthataredeeplyinvolvedinatheroscleroticprocess,ispoorlyrecognized.ThepresentstudywasdesignedtoinvestigatetheeffectoftheAngIIonCRPexpressioninratVSMCsandthemolecularmechanismsparticularlyinvolvingmitogen-activatedproteinkinase(MAPK)signalsinthisresponse.