Heme triggers TLR4 signaling leading to endothelial cell activation and vaso-occlusion in murine sickle cell disease

Treatment of sickle cell disease (SCD) is hampered by incomplete understanding of pathways linking hemolysis to vaso-occlusion. We investigated these pathways in transgenic sickle mice. Infusion of hemoglobin or heme triggered vaso-occlusion in sickle, but not normal, mice. Methemoglobin, but not heme-stabilized cyanomethemoglobin, induced vaso-occlusion, indicating heme liberation is necessary. In corroboration, hemoglobin-induced vaso-occlusion was blocked by the methemoglobin reducing agent methylene blue, haptoglobin, or the heme-binding protein hemopexin. Untreated HbSS mice, but not HbAA mice, exhibited ∼10% vaso-occlusion in steady state that was inhibited by haptoglobin or hemopexin infusion. Antibody blockade of adhesion molecules P-selectin, von Willebrand factor (VWF), E-selectin, vascular cell adhesion molecule 1, intercellular adhesion molecule 1, platelet endothelial cell (EC) adhesion molecule 1, α4β1, or αVβ3 integrin prevented vaso-occlusion. Heme rapidly (5 minutes) mobilized Weibel-Palade body (WPB) P-selectin and VWF onto EC and vessel wall surfaces and activated EC nuclear factor κB (NF-κB). This was mediated by TLR4 as TAK-242 blocked WPB degranulation, NF-κB activation, vaso-occlusion, leukocyte rolling/adhesion, and heme lethality. TLR4(-/-) mice transplanted with TLR4(+/+) sickle bone marrow exhibited no heme-induced vaso-occlusion. The TLR4 agonist lipopolysaccharide (LPS) activated ECs and triggered vaso-occlusion that was inhibited by TAK-242, linking hemolysis- and infection-induced vaso-occlusive crises to TLR4 signaling. Heme and LPS failed to activate VWF and NF-κB in TLR4(-/-) ECs. Anti-LPS immunoglobulin G blocked LPS-induced, but not heme-induced, vaso-occlusion, illustrating LPS-independent TLR4 signaling by heme. Inhibition of protein kinase C, NADPH oxidase, or antioxidant treatment blocked heme-mediated stasis, WPB degranulation, and oxidant production. We conclude that intravascular hemolysis in SCD releases heme that activates endothelial TLR4 signaling leading to WPB degranulation, NF-κB activation, and vaso-occlusion.

Medienart:

E-Artikel

Erscheinungsjahr:

2014

Erschienen:

2014

Enthalten in:

Zur Gesamtaufnahme - volume:123

Enthalten in:

Blood - 123(2014), 3 vom: 16. Jan., Seite 377-90

Sprache:

Englisch

Beteiligte Personen:

Belcher, John D [VerfasserIn]
Chen, Chunsheng [VerfasserIn]
Nguyen, Julia [VerfasserIn]
Milbauer, Liming [VerfasserIn]
Abdulla, Fuad [VerfasserIn]
Alayash, Abdu I [VerfasserIn]
Smith, Ann [VerfasserIn]
Nath, Karl A [VerfasserIn]
Hebbel, Robert P [VerfasserIn]
Vercellotti, Gregory M [VerfasserIn]

Links:

Volltext

Themen:

147257-52-1
42VZT0U6YR
9013-71-2
Haptoglobins
Heme
Hemoglobins
Hemopexin
Journal Article
Lipopolysaccharides
NF-kappa B p50 Subunit
Nfkb1 protein, mouse
Research Support, N.I.H., Extramural
Research Support, Non-U.S. Gov't
Tlr4 protein, mouse
Toll-Like Receptor 4
Von Willebrand Factor

Anmerkungen:

Date Completed 18.03.2014

Date Revised 21.10.2021

published: Print-Electronic

Citation Status MEDLINE

doi:

10.1182/blood-2013-04-495887

funding:

Förderinstitution / Projekttitel:

PPN (Katalog-ID):

NLM23307726X