Antimicrobial peptide LL‐37 promotes bacterial phagocytosis by human macrophages

[摘要] LL‐37/hCAP‐18istheonlyhumanmemberofthecathelicidinfamilyandplaysanimportantroleinkillingvariouspathogens,aswellasinimmunemodulation.Inthisstudy,weinvestigatedtheeffectofLL‐37onbacterialphagocytosisbymacrophagesanddemonstratethatLL‐37enhancesphagocytosisofIgG‐opsonizedGram‐negativeandGram‐positivebacteriainadose‐andtime‐dependentmannerbydTHP‐1cells.Inaddition,LL‐37enhancedphagocytosisofnonopsonizedEscherichiacolibyhumanmacrophages.Consistently,LL‐37elevatedtheexpressionofFcγRsonmacrophagesbutnotthecomplementreceptorsCD11band‐c.FurtherstudiesrevealedthattheexpressionofTLR4andCD14isalsoincreasedonLL‐37‐treatedmacrophages.SeverallinesofevidenceindicatedthattheFPR2/ALXreceptormediatedLL‐37‐inducedphagocytosis.However,TLR4signalingwasalsocoupledtothephagocyticresponse,asaspecificTLR4antibodysignificantlysuppressedphagocytosisofIgG‐opsonizedE.coliandnonopsonizedE.colibydTHP‐1cells.Finally,macrophagesfromCnlp−/−miceexhibiteddiminishedbacterialphagocytosiscomparedwithmacrophagesfromtheirWTlittermates.Inconclusion,wedemonstrateanovel,immune‐modulatorymechanismofLL‐37,whichmaycontributetobacterialclearance...

[学科分类] 生理学

[关键词] cathelicidin;FcγR;TLR;innate immunity;infection