The changes of negative-regulatory factors A20, IRF-4 and TRAF4 of toll-like receptor signal pathways in immunological pathogenesis of Kawasaki disease

Toinvestigatetheroleofnegative-regulatoryfactorsA20,IRF-4andTRAF4ofthetoll-likereceptor(TLR)signalpathwaysinimmunologicalpathogenesisofKawasakidisease(KD),48childrenwithKawasakidisease,16childrenwithinfectiousdisease(ID)and16age-matchedhealthychildrenwerestudied.Reverse-transcriptionPCR(RT-PCR)andreal-timePCRwereusedtoevaluatetheexpres-sionlevelsofnegative-regulatoryandeffectivefactorsintoll-likereceptor4(TLR4)signalpathwaysandproinflammatoryfactorsinperipheralbloodmonocyte/macrophage(MC).Inthisstudy,expressionlevelsofTLR4,MD-2,MyD88,IRAK-4,TRAF6,TAK1,andTAB2mRNAinKDgroupweredetectedtobeelevatedsignificantlyduringacutephaseofKD.Transcriptionlevelsofnegative-regulatoryfactorsA20,IRF-4andTRAF4mRNAinKDorIDpatientsincreasedremarkably.However,expressionsofIRF-4andTRAF4inKDpatientsweredetectedtobelowerthanthatinIDpatients,exceptthattran-scriptionlevelsofA20werefoundtobehigherthanthatinIDpatients.Simultaneously,expressionsofproinflammatorycytokinessuchasL-1β,IL-6andTNF-αinKDpatientsweresignificantlyelevatedcom-paredwiththoseinIDpatients.Furthermore,itwasfoundthatstimulationoflipopolysaccharide(LPS)remarkablyup-regulatedtheexpressionsofnegative-regulatoryfactorsA20,IRF-4andTRAF4inKDpa-tientsorhealthyvolunteers.ThemRNAlevelsofallthethreefactorsinKDpatientswerefoundtobelowerthanthatinthelatter.Inaddition,transcriptionlevelsofIRF-4andTRAF4inKDpatientswithcoronaryarterylesion(KD-CAL~+)weredetectedtobelowerthanthoseinKDpatientswithoutcoronaryarterylesion(KD-CAL~-)duringacutephase,whilethatofA20inKD-CAL~+groupwerelowerthanthatinthelatter.AndthelevelsofexpressionsofproinflammatorycytokinesinKD-CAL~+groupwerefoundtobehigherthanthoseinKD-CAL-group(P<0.01).Thesefindingssuggestthataberrantexpressionofnegative-regulatoryfactorsofTLRssignalpathwaysmaybeinvolved