Abstract Number: PB2019
Meeting: ISTH 2020 Congress
Background: Free extracellular heme has been shown to activate several compartments of innate immunity, acting as a danger-associated molecular pattern (DAMP) in diseases associated with hemolysis. Although localized endothelial barrier (EB) disruption is an important part of innate immunity activation that allows circulating leukocytes to reach inflamed tissues, non-localized/deregulated disruption of the EB can lead to widespread microvascular hyperpermeability and secondary tissue damage, such as observed in sepsis. In mice models of sickle cell disease (SCD), EB disruption has been associated with the development of a form of acute lung injury that closely resembles acute chest syndrome (ACS), and that can be elicited by the acute infusion of heme.
Aims: Here we explored the effect of heme on EB integrity using human endothelial cell monolayers, in experimental conditions that include elements that normally trigger acute SCD complications in humans.
Methods: EB integrity was assessed by electric cell-substrate impedance sensing in the presence of varying concentrations of heme, LPS and sera from SCD patients or healthy volunteers.
Results: Heme caused a dose-dependent decrease of the electrical resistance of cell monolayers, consistent with EB disruption, which was confirmed by staining of adherens junction protein VE-cadherin. LPS further increased this effect. Sera from SCD patients, but not from healthy volunteers, were also capable to induce EB disruption. Finally, the EB-disrupting effects of heme were still observed in the presence of serum from SCD patients but not from healthy volunteers.
Conclusions: Together our results provide new information about the pathogenesis of diseases in which EB disruption occurs in association with hemolysis, such as SCD and sepsis, and reinforce the concept that heme can act as a DAMP in hemolytic conditions.
To cite this abstract in AMA style:Santaterra VAG, Fiusa MML, Hounkpe BW, Chenou F, Costa LNG, Garcia-Weber D, Domingos IDF, Araujo ADS, Lucena-Araujo AR, Bezerra MA, Santos MN, Costa FF, Millan J, De Paula EV. In Vitro Disruption of Endothelial Barrier Integrity by Heme and by Serum from Patients with Sickle Cell Disease [abstract]. Res Pract Thromb Haemost. 2020; 4 (Suppl 1). https://abstracts.isth.org/abstract/in-vitro-disruption-of-endothelial-barrier-integrity-by-heme-and-by-serum-from-patients-with-sickle-cell-disease/. Accessed January 21, 2022.
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