Hemin Causes Lung Microvascular Endothelial Barrier Dysfunction by Necroptotic Cell Death

Area of Science:

• Vascular Biology
• Hematology
• Cellular Pathology

Background:

• Hemin, derived from hemoglobin, is linked to acute chest syndrome in sickle cell disease due to its endothelial-activating effects.
• Understanding hemin's role in endothelial dysfunction is crucial for developing targeted therapies.

Purpose of the Study:

• To investigate if hemin induces lung microvascular endothelial barrier dysfunction.
• To elucidate the cellular mechanisms underlying hemin-induced endothelial damage.

Main Methods:

• Electrical cell impedance sensing to measure transendothelial electrical resistance.
• Fluorescein isothiocyanate-dextran flux assays to assess monolayer permeability.
• Cell death assays including Trypan blue staining, TUNEL assay, and Western blotting.

Main Results:

• Hemin caused a concentration-dependent endothelial barrier dysfunction.
• This dysfunction was abrogated by Toll-like receptor 4 inhibition and antioxidant pretreatment.
• Endothelial barrier dysfunction was associated with programmed cell death via necroptosis.

Conclusions:

• Hemin induces lung microvascular endothelial barrier dysfunction and necroptosis.
• Targeting Toll-like receptor 4 or oxidative stress may be beneficial in acute chest syndrome.
• Further research into endothelial cell necroptosis could reveal novel treatment avenues for this condition.