Abstract
Objective: The role of collagen receptor complex GPVI-FcR γ-chain, PLCγ2 and LAT in laser-induced thrombosis is unclear. Controversy surrounds whether collagen is exposed in this model or whether thrombosis is dependent on thrombin. This study hypothesized that collagen exposure plays a critical role in thrombus formation in this model, which was tested by investigating contributions of FcR γ-chain, LAT, PLCγ2 and thrombin.
Methods: Thrombi were monitored using intravital microscopy in anesthetized wild-type and FcR γ-chain, LAT and PLCγ2 knockout mice. Hirudin (thrombin inhibitor) was administered to wild-type and FcR γ-chain knockout mice.
Results: Significantly reduced thrombus formation was observed in FcR γ-chain and PLCγ2 knockouts with a greater decrease observed in LAT knockouts. Dramatic reduction was observed in wild-types treated with hirudin, with abolished thrombus formation only observed in FcR γ-chain knockouts treated with hirudin.
Conclusions: GPVI-FcR γ-chain, LAT and PLCγ2 are essential for thrombus generation and stability in this laser-induced model of injury. More importantly, a greater role for LAT was identified, which may reflect a role for it downstream of a second matrix protein receptor. However, inhibition of platelet activation by matrix proteins and thrombin generation are both required to maximally prevent thrombus formation.
This work was supported by the Wellcome Trust and British Heart Foundation SPW holds a BHF Chair.