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

Abstract

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.

Role of CD40 and ADAMTS13 in von Willebrand factor-mediated endothelial cell–platelet–monocyte interaction

“…Cremaster muscles of ADAMSTS13-knockout mice (stock: 007235; Jackson Laboratories) and C57BL/6J as wild-type control mice were prepared for intravital microscopy as described before (70). The endothelium of arterioles and venules was labeled by topical application of Alexa Fluor 647-labeled CD31 antibody (BD Biosciences) for 1 h. Platelets from C57/BL6 donor animals were washed and labeled ex vivo with carboxyfluorescein diacetate (CFDA) as described earlier (71). Two hundred-microliter platelet suspensions corresponding to 8 × 10 6 platelets were injected into the circulation.…”

TNF-induced endothelial barrier disruption: beyond actin and Rho

“…SHP phosphatases are candidates for regulating PECAM-1 localisation in response to TNF because they are involved in TNF-mediated signalling: SHP-2 is associated with IKK and mediates NF-κB activation in response to TNF (183); SHP-1 and SHP-2 associate with the death domain of TNFR1 in response to TNF, thereby modulating cytokine-mediated survival (184). TNF also induces SHP-2 activity in HUVECs (185) as well a moderate increment in SHP-1 expression and activity (186,187). To date, however, the effect of TNF-mediated activation of SHPs on the localisation of PECAM-1 has not been investigated.…”

Shp-1 dephosphorylates TRPV1 in dorsal root ganglion neurons and alleviates CFA-induced inflammatory pain in rats

“…This compensatory mechanism was also reported when Shp-1 served as an autoinhibitory molecule and protected against TNF-a-induced endothelial inflammation; TNF-a increased Shp-1 activity and protein expression, while Shp-1 inhibited TNF-a-induced inflammation. 13 It may imply a universal auto-balancing system when phosphatases like Shp-1 respond to microenvironmental changes, including that in nociception.…”