Identification of specific Tie2 cleavage sites and therapeutic modulation in experimental sepsis

Abstract

Endothelial Tie2 signaling plays a pivotal role in vascular barrier maintenance at baseline and after injury. We previously demonstrated that a sharp drop in Tie2 expression observed across various murine models of critical illnesses is associated with increased vascular permeability and mortality. Matrix metalloprotease (MMP)−14-mediated Tie2 ectodomain shedding has recently been recognized as a possible mechanism for Tie2 downregulation in sepsis. Here, we identified the exact MMP14-mediated Tie2 ectodomain cleavage sites and could show that pharmacological MMP14 blockade in experimental murine sepsis exerts barrier protective and anti-inflammatory effects predominantly through the attenuation of Tie2 cleavage to improve survival both in a pre-treatment and rescue approach. Overall, we show that protecting Tie2 shedding might offer a new therapeutic opportunity for the treatment of septic vascular leakage.

Tie2 activation protects against prothrombotic endothelial dysfunction in COVID-19

“…We also investigated levels of the anti-thrombotic endothelial proteins, EPCR, TFPI, and thrombomodulin, which are cleaved from inflamed endothelium. Finally, given its role linking vascular inflammation and thrombosis, we investigated components of the Tie2-angiopoietin pathway, specifically Tie2-activating cytoprotective Angpt-1, Tie2-inhibiting proinflammatory Angpt-2, and soluble Tie2, which is also cleaved from endothelial cells during inflammatory states (25). Several thromboinflammatory proteins were significantly higher in severe versus mild disease: tissue factor (P < 0.0001), VWF (P < 0.001), P-selectin (P < 0.001), Angpt-2 (P < 0.0001), VEGFR-1 (P < 0.0001), thrombomodulin (P < 0.001), and TFPI (P < 0.001).…”

“…Angpt-2 levels are even further elevated in the plasma of patients with sepsis with disseminated intravascular coagulation compared with those with sepsis alone, and high Angpt-2 levels potentiate endothelial dysfunction of critical illness ( 23 , 24 ). Loss of constitutive Tie2 signaling is mediated through Angpt-2 antagonism or by Tie2 cleavage from the endothelial surface ( 25 , 26 ). Inhibition of Tie2 results in loss of barrier function and anti-inflammatory transcriptional machinery, most notably characterized by upregulation of Angpt-2 itself, leading to a positive feedback loop and further Tie2 suppression.…”

Tie2 activation protects against prothrombotic endothelial dysfunction in COVID-19

“…We also investigated levels of the anti-thrombotic endothelial proteins, endothelial protein C receptor (EPCR), TFPI, and thrombomodulin, which are cleaved from inflamed endothelium. Finally, given its role linking vascular inflammation and thrombosis, we investigated components of the Tie2-angiopoietin pathway, specifically Tie2-activating cytoprotective Angpt-1, Tie2-inhibiting proinflammatory Angpt-2, and soluble Tie2, which is also cleaved from endothelial cells during inflammatory states 26 .…”

“…We also investigated levels of the anti-thrombotic endothelial proteins, endothelial protein C receptor (EPCR), TFPI, and thrombomodulin, which are cleaved from inflamed endothelium. Finally, given its role linking vascular inflammation and thrombosis, we investigated components of the Tie2-angiopoietin pathway, specifically Tie2-activating cytoprotective Angpt-1, Tie2-inhibiting proinflammatory Angpt-2, and soluble Tie2, which is also cleaved from endothelial cells during inflammatory states 26 . Several thromboinflammatory proteins were significantly higher in severe versus mild disease: tissue factor (P < 0.0001), VWF (P < 0.001), P-selectin (P < 0.001), Angpt-2 (P < 0.0001), VEGFR-1 (P < 0.0001), thrombomodulin (P < 0.001), and TFPI (P < 0.001).…”

“…Angpt-2 levels are even further elevated in the plasma of septic patients with disseminated intravascular coagulation (DIC) compared to those with sepsis but without DIC, and high Angpt-2 levels potentiate endothelial dysfunction of critical illness 23,24 . Loss of constitutive Tie2 signaling is mediated through Angpt-2 antagonism or by Tie2 cleavage from the endothelial surface 26,27 . Inhibition of Tie2 results in loss of barrier function and anti-inflammatory transcriptional machinery, most notably characterized by upregulation of Angpt-2 itself, leading to a positive feedback loop and further Tie2 suppression.…”