Binding requirements for latent transforming growth factor Beta2 activation.

Although the mechanism for activation of latent TGFß1 and TGFß3 is understood to involve the binding of the TGFß propeptide (LAP) to both an integrin and an insoluble substrate, the activation of latent TGFß2 has been unclear because the TGFß2 LAP does not have the classical integrin binding sequence found in the other two TGFß isoform LAPs. To assess the potential requirement for covalent linkage with a matrix or cell surface protein for the activation of latent TGFß2, we generated mice in which the TGFß2 Cys residue predicted to be involved in binding was mutated to Ser (Tgfb2C24S). We reasoned that, if covalent interaction with a second molecule is required for latent TGFß2 activation, mutant mice should display a Tgfb2 null (Tgfb2-/-)-like phenotype. Tgfb2C24S mice closely phenocopy Tgfb2-/- mice with death in utero between E18 and P1 and with congenital heart and kidney defects similar to those described for Tgfb2-/- mice. The mutant latent TGFß2 is secreted at levels similar to WT, yet TGFß signaling monitored as nuclear pSmad2 is suppressed. We conclude that, like latent TGFß1, latent TGFß2 activation requires binding to an immobilized matrix or plasma membrane molecule.

Evidence That Anemia Accelerates AS Progression Via Shear-Induced TGF-ß1 Activation: Heyde's Syndrome Comes Full Circle.

The severity of aortic stenosis (AS) is associated with acquired von Willebrand syndrome (AVWS) and gastrointestinal bleeding, leading to anemia (Heyde's syndrome). We investigated how anemia is linked with AS and AVWS using the LA100 mouse model and patients with AS. Induction of anemia in LA100 mice increased transforming growth factor (TGF)-ß1 activation, AVWS, and AS progression. Patients age >75 years with severe AS had higher plasma TGF-ß1 levels and more severe anemia than AS patients age <75 years, and there was a correlation between TGF-ß1 and anemia. These data are compatible with the hypothesis that the blood loss anemia of Heyde's syndrome contributes to AS progression via WSS-induced activation of platelet TGF-ß1 and additional gastrointestinal bleeding via WSS-induced AVWS.

Intervention in COVID-19 linked hypercoaguable states characterized by circuit thrombosis utilizing a direct thrombin inhibitor.

•Circuit thrombosis complicates CRRT in COVID-19 despite standard heparin-based anticoagulation regimens.•5 cases of CRRT thrombosis despite heparin-based anticoagulation resolved using a direct thrombin inhibitor, argatroban.•Changes in fibrinogen levels better reflected response to anticoagulation than did changes in D-dimer levels.•High fibrinogen levels and decreased anti-thrombin III activity may relate to argatroban superiority in these cases.