The Endothelial Tyrosine Phosphatase SHP-1 Plays an Important Role for Vascular Haemostasis in TNFα-Induced Inflammation In Vivo

Abstract EN

Introduction.

Inflammation and endothelium-derived superoxides are important pathomechanisms in atherothrombotic diseases.

We could previously show that the tyrosine phosphatase SHP-1 acts as a negative regulator in endothelial superoxide production.

In this study we investigated the influence of SHP-1 on platelet-endothelium interaction and arterial thrombosis in TNFα-induced endothelial inflammation in vivo.

Methods.

Arteriolar thrombosis and platelet rolling in vivo were investigated in C57BL/6 mice using intravital microscopy in the dorsal skinfold chamber microcirculation model.

Results.

Inhibition of SHP-1 by the specific pharmacological inhibitor sodium stibogluconate did not significantly enhance platelet-endothelium interaction in vivo under physiological conditions but led to an augmented fraction of rolling platelets in TNFα-induced systemic inflammation.

Accordingly, ferric-chloride-induced arteriolar thrombus formation, which was already increased by SHP-1 inhibition, was further enhanced in the setting of TNFα-induced inflammation.

Platelet aggregation in vitro as well as ex vivo was not influenced by SHP-1-inhibition.

In cultured endothelial cells, sodium stibogluconate increased TNFα-induced surface expression of p-selectin and von Willebrand factor.

Additionally, TNFα increased SHP-1 activity and protein expression.

Conclusions.

The endothelial tyrosine phosphatase SHP-1 plays an important role for vascular hemostasis in vivo, which is crucial in TNFα-induced endothelial inflammation where it may serve as an autoinhibitory molecule to prevent excess inflammatory response and thrombus formation.