Characterization of the shear stress regulation of CD18 surface expression by HL60-derived neutrophil-like cells

• Published in: Biomechanics and modeling in mechanobiology 2014-08, Vol.13 (4), p.861-870
• Main Authors: Akenhead, M. L., Zhang, X., Shin, H. Y.
• Format: Article
• Language: English
• Subjects: Biological and Medical Physics; Biomechanics; Biomedical engineering; Biomedical Engineering and Bioengineering; Biophysics; Cathepsin B - chemistry; CD11a Antigen - metabolism; CD18 Antigens - metabolism; Cell adhesion & migration; Cleavage; Cysteine; Doxycycline - chemistry; Engineering; Exposure; Flow Cytometry; HL-60 Cells; Humans; Inflammation; Microscopy, Fluorescence; Molecular dynamics; N-Formylmethionine Leucyl-Phenylalanine - chemistry; Neutrophils - cytology; Neutrophils - drug effects; Neutrophils - metabolism; Original Paper; Protease; Shear; Shear Strength; Shear stress; Space life sciences; Stress, Mechanical; Surface chemistry; Theoretical and Applied Mechanics
• ISSN: 1617-7959; 1617-7940
• DOI: 10.1007/s10237-013-0541-9

Shear stress-induced cleavage of cell surface CD18 integrins is reported to be part of an anti-inflammatory control mechanism that minimizes neutrophil activity in the blood under physiologic conditions. The cysteine protease, cathepsin B (catB), has been implicated in this mechanoregulatory mechanism, but its molecular dynamics remain to be elucidated. Moreover, attempts to do so using molecular approaches are hindered by the limited ex vivo life span of primary neutrophils. As an alternative, we explored the potential use of HL60-derived neutrophilic cells as a transfectable culture model that exhibits a shear-induced CD18 cleavage response comparable to primary neutrophils. HL60 cells were differentiated into neutrophil-like cells (dHL60-NCs) and exposed to laminar shear stress ( 5 dynes / cm 2 for 10 min). Based on cytometric analyses, sheared cells cleaved CD18 and CD11a, but not CD11b, integrins. Treatment of cells with E64 or doxycycline prior to and during shear exposure inhibited CD18, but only attenuated CD11a, cleavage. Neither aprotinin nor pepstatin affected shear-induced CD18 or CD11a cleavage. Notably, dHL60-NCs expressed minimal catB. Thus, multiple cysteine proteases in addition to catB may cleave CD18 on sheared leukocytes. In fact, our findings indicate that multiple non-cysteine proteases also participate in the shear-related cleavage of CD11/CD18 heterodimers. Finally, shear-induced cleavage of CD18 and CD11a by dHL60-NCs was inhibited by fMLP concentrations of at least 1 μ M . Collectively, our findings indicate that shear-induced CD11/CD18 cleavage is phenotypic of neutrophilic cells, including those derived from HL60 cells. Moreover, our results verify shear stress as a key anti-inflammatory stimulus for neutrophils under physiologic conditions.