Phagosomal retention of Francisella tularensis results in TIRAP/Mal-independent TLR2 signaling

Journal of Leukocyte Biology

Katherine A. Fitzgerald²  Leah E. Cole³  Kari Ann Shirey³  Stefanie N. Vogel³  Michelle H. W. Laird³  Eileen Barry¹  Araceli Santiago¹  Anna Seekatz³  Zhaozhao Jiang² 

[1] Center for Vaccine Development, University of Maryland, Baltimore, Maryland, USA; and Center for Vaccine Development, University of Maryland, Baltimore, Maryland, USA; and Center for Vaccine Development, University of Maryland, Baltimore, Maryland, USA; and;Division of Infectious Diseases and Immunology, Department of Medicine, University of Massachusetts Medical School, Worcester, Massachusetts, USA Division of Infectious Diseases and Immunology, Department of Medicine, University of Massachusetts Medical School, Worcester, Massachusetts, USA Division of Infectious Diseases and Immunology, Department of Medicine, University of Massachusetts Medical School, Worcester, Massachusetts, USA;Department of Microbiology and Immunology and Department of Microbiology and Immunology and Department of Microbiology and Immunology and

关键词: macrophage;    cytokine;    bacterial infection;    TLR2;    MyD88;   

DOI  :  10.1189/jlb.0909619

学科分类：生理学

来源: Federation of American Societies for Experimental Biology

【 摘 要 】

TLR2 plays a central role in the activation of innate immunity in response to Ft, the causative agent of tularemia. We reported previously that Ft LVS elicited strong, dose-dependent NF-κB reporter activity in TLR2-expressing human embryo kidney 293 T cells and that Ft LVS-induced murine macrophage proinflammatory cytokine gene and protein expression is TLR2-dependent. We demonstrated further that Ft can signal through TLR2 from within the phagosome and that phagosomal retention of Ft leads to greatly increased expression of a subset of proinflammatory genes. The two adaptor proteins associated with TLR2-mediated signaling are MyD88 and TIRAP. Although MyD88 is absolutely required for the Ft-induced macrophage cytokine response, the requirement for TIRAP can be overcome through retention of Ft within the phagosome. TIRAP-independent signaling was observed whether Ft was retained in the phagosome as a result of bacterial mutation (LVSΔiglC) or BFA-mediated inhibition of phagosome acidification. The requirement for TIRAP in TLR2 signaling could also be overcome by increasing the concentrations of synthetic bacterial TLR2 agonists. Taken together, these data suggest that prolonging or enhancing the interaction between TLR2 and its agonist overcomes the “bridging” function ascribed previously to TIRAP.

【 授权许可】

Unknown