Interaction between the CCR5 chemokine receptors and microbial HSP70

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Abstract
Evidence is presented that the microbial 70‐kD heat shock protein (HSP70) binds to CCR5 chemokine receptors in CCR5‐transfected cell lines and in primary human cells. Significant CCR5‐mediated calcium mobilization was stimulated by HSP70 and inhibited with TAK 779, which is a specific CCR5 antagonist. HSP70‐mediated activation of the p38 MAPK phosphorylation signaling pathway was also demonstrated in CCR5‐transfected HEK 293 cells. Direct binding of three extracellular peptides of CCR5 to HSP70 was demonstrated by surface plasmon resonance. Functional evidence of an interaction between HSP70, CCR5 and CD40 was shown by enhanced production of CCL5 by HEK 293 cells transfected with both CD40 and CCR5. Primary monocyte‐derived immature DC stimulated with HSP70 produced IL‐12 p40, which showed dose‐dependent inhibition of >90% on treatment with both TAK 779 and anti‐CD40 mAb. Stimulation of IL‐12 p40 or TNF‐α by HSP70 was related to the differential cell surface expression of CCR5 in primary human immature and mature DC, and those with the homozygous ▵▵32 CCR5 mutation. These findings may be of significance in the interaction between HSP70 and immune responses of CCR5+ T cells in HIV‐1 infection, as well as in inflammatory bowel disease. See accompanying commentary: http://dx.doi.org/10.1002/eji.200636551

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