Fluid shear-induced activation and cleavage of CD18 during pseudopod retraction by human neutrophils

Hainsworth Y. Shin, Scott I. Simon, Geert W. Schmid-Schönbein

Research output: Contribution to journalArticle

21 Citations (Scopus)

Abstract

Surface membrane expression and conformational activation of CD18 integrins into an open molecular configuration play critical roles in neutrophil ligand binding, membrane attachment, spreading on the endothelium, and cell migration to sites of inflammation. Previously, we observed pseudopod retraction and concomitant cleavage of CD18 by human neutrophils upon exposure to fluid shear stress. But the underlying cellular mechanism(s) linking these phenomena remains unknown. We hypothesize here that activation of CD 18 under the influence of fluid shear stress leads to its increased susceptibility to proteolytic cleavage by lysosomal proteases such as cathepsin B and is a requirement for CD18 cleavage and subsequent pseudopod retraction. Specifically, we report conformational changes in the CD18 extracellular domain on neutrophils exposed to physiological fluid shear stresses. Western blot analysis using a CD 18 antibody targeted against the intracellular domain revealed reduced levels of full-length CD18 after stimulation of neutrophils with either fluid shear stress or with the Ca2+ ionophore phorbol 12-myristate 13-acetate (PMA; 100 nM) in the presence of exogenous cathepsin B (0.5 U/ml). Moreover, we identified cathepsin B as one protease that may be released by neutrophils under flow and required for shear-induced pseudopod retraction. These results suggest that a putative mechanotransduction mechanism involving shear-induced changes in the conformation of CD18 and its subsequent cleavage from the cell surface serves to regulate pseudopod activity of neutrophils under physiologic shear stress.

Original languageEnglish (US)
Pages (from-to)528-536
Number of pages9
JournalJournal of Cellular Physiology
Volume214
Issue number2
DOIs
StatePublished - Feb 2008

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Pseudopodia
Shear stress
Neutrophils
Chemical activation
Cathepsin B
Fluids
Peptide Hydrolases
Membranes
Ionophores
Molecular Conformation
Integrins
Conformations
Acetates
Endothelium
Cell Movement
Ligands
Western Blotting
Antibodies
Inflammation

ASJC Scopus subject areas

  • Clinical Biochemistry
  • Cell Biology
  • Physiology

Cite this

Fluid shear-induced activation and cleavage of CD18 during pseudopod retraction by human neutrophils. / Shin, Hainsworth Y.; Simon, Scott I.; Schmid-Schönbein, Geert W.

In: Journal of Cellular Physiology, Vol. 214, No. 2, 02.2008, p. 528-536.

Research output: Contribution to journalArticle

Shin, Hainsworth Y. ; Simon, Scott I. ; Schmid-Schönbein, Geert W. / Fluid shear-induced activation and cleavage of CD18 during pseudopod retraction by human neutrophils. In: Journal of Cellular Physiology. 2008 ; Vol. 214, No. 2. pp. 528-536.
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