Disrupting the vicious cycle created by NOX activation in sickle erythrocytes exposed to hypoxia/reoxygenation prevents adhesion and vasoocclusion.
Abstract
In sickle cell disease (SCD), recurrent painful vasoocclusive crisis are likely caused
by repeated episodes of hypoxia and reoxygenation. The sickle erythrocyte (SSRBC)
adhesion plays an active role in vasoocclusion. However, the effect of prolonged reoxygenation
after hypoxic stress on the molecular mechanisms in SSRBCs involved in onset of episodic
vasoocclusion remain unclear. Exposure of human SSRBCs to hypoxia followed by 2 h
reoxygenation, increased reactive oxygen species (ROS) production. Using specific
pharmacological inhibitors, we show that excess ROS production in both reticulocytes
and mature SSRBCs is regulated by NADPH oxidases (NOXs), the mitogen-activated protein
kinase (ERK1/2), and G-protein coupled-receptor kinase 2 (GRK2). Consequently, SSRBC
ROS create an intracellular positive feedback loop with ERK1/2 and GRK2 to mediate
SSRBC adhesion to endothelium in vitro, and vasoocclusion in a mouse model of vasoocclusion
in vivo. Importantly, reducing ROS levels in SSRBCs with redox-active manganese (Mn)
porphyrins, commonly known as mimics of superoxide dismutase (SOD), disrupted the
cycle created by ROS by affecting NOX and GRK2 activities and ERK1/2 phosphorylation,
thus abrogating RBC-endothelial interactions. Inhibition adhesion assays show that
LW (ICAM-4, CD242) blood group glycoprotein and CD44 are the RBC adhesion molecules
mediating endothelial binding. Conversely, hypoxia/reoxygenation of normal RBCs failed
to activate this feedback loop, and adhesion. These findings provide novel insights
into the pathophysiological significance of the deleterious cycle created by NOX-dependent
ROS, GRK2 and ERK1/2 within SSRBCs activated by hypoxia/reoxygenation, and involved
in SSRBC adhesion and vasoocclusion. Thus, this loop in SSRBCs, which can be disrupted
by Mn porphyrins, likely drives the profound SCD vasculopathy, and may point to new
therapeutic targets to prevent chronic vasoocclusive events.
Type
Journal articleSubject
ErythrocytesEndothelial Cells
Humans
Vascular Diseases
Anemia, Sickle Cell
Oxygen
Reactive Oxygen Species
Extracellular Signal-Regulated MAP Kinases
Cell Adhesion Molecules
Cell Adhesion
Signal Transduction
Cell Hypoxia
Enzyme Activation
Nitrosation
G-Protein-Coupled Receptor Kinase 2
Feedback, Physiological
NADPH Oxidases
Permalink
https://hdl.handle.net/10161/22408Published Version (Please cite this version)
10.1016/j.redox.2019.101097Publication Info
MacKinney, Anson; Woska, Emily; Spasojevic, Ivan; Batinic-Haberle, Ines; & Zennadi,
Rahima (2019). Disrupting the vicious cycle created by NOX activation in sickle erythrocytes exposed
to hypoxia/reoxygenation prevents adhesion and vasoocclusion. Redox biology, 25. pp. 101097. 10.1016/j.redox.2019.101097. Retrieved from https://hdl.handle.net/10161/22408.This is constructed from limited available data and may be imprecise. To cite this
article, please review & use the official citation provided by the journal.
Collections
More Info
Show full item recordScholars@Duke
Ines Batinic-Haberle
Professor Emeritus of Radiation Oncology
A major interest of mine has been in the design and synthesis of Mn porphyrin(MnP)-based
powerful catalytic antioxidants which helped establish structure-activity relationship
(SAR). It relates the redox property of metalloporphyrins to their ability to remove
superoxide. SAR has facilitated the design of redox-active therapeutics and served
as a tool for mechanistic considerations. Importantly SAR parallels the magnitu
Ivan Spasojevic
Associate Professor in Medicine
Rahima Zennadi
Associate Professor in Medicine
My research in Hematology addresses three areas of investigation: disorders associated
with sickle cell disease pathophysiology, venous thrombosis/thromboembolism (VT/E)
associated with aging, and cerebrovascular injury.
In sickle cell disease, vaso-occlusion leads to serious life-threatening complications,
including acute pain crises and irreversible organ damage. Vaso-occlusion is caused
largely by sickle red blood cell adhesion to the vascular endothelium. Prevention
of
Alphabetical list of authors with Scholars@Duke profiles.

Articles written by Duke faculty are made available through the campus open access policy. For more information see: Duke Open Access Policy
Rights for Collection: Scholarly Articles
Works are deposited here by their authors, and represent their research and opinions, not that of Duke University. Some materials and descriptions may include offensive content. More info