4D intravital microscopy uncovers critical strain differences for the roles of PECAM and CD99 in leukocyte diapedesis

• Published in: American journal of physiology. Heart and circulatory physiology Vol. 311; no. 3; pp. H621 - H632
• Main Authors: Sullivan, David P, Watson, Richard L, Muller, William A
• Format: Journal Article
• Language: English
• Published: United States American Physiological Society 01.09.2016
• Subjects: 12E7 Antigen - antagonists & inhibitors; 12E7 Antigen - metabolism; Abdominal Muscles - metabolism; Abdominal Muscles - pathology; Animals; Antibodies, Blocking - pharmacology; Basement Membrane; Blood platelets; Cell Adhesion; Cell adhesion & migration; Croton Oil - adverse effects; Dermatitis, Contact - etiology; Dermatitis, Contact - metabolism; Dermatitis, Contact - pathology; Dermatologic Agents - adverse effects; Endothelium; Flow Cytometry; Intravital Microscopy; Leukocytes; Leukocytes - pathology; Mice; Mice, Inbred C57BL; Microscopy, Fluorescence; Neutrophils; Physiology; Platelet Endothelial Cell Adhesion Molecule-1 - metabolism; Transendothelial and Transepithelial Migration; Vascular Biology and Microcirculation; intravital microscopy; diapedesis; inflammation; platelet/endothelial cell adhesion molecule; CD99
• ISSN: 0363-6135; 1522-1539
• DOI: 10.1152/ajpheart.00289.2016

Leukocyte transendothelial migration (TEM) is an essential component of the inflammatory response. In vitro studies with human cells have demonstrated that platelet/endothelial cell adhesion molecule (PECAM) functions upstream of CD99 during TEM; however, results in vivo with mice have been apparently contradictory. In this study we use four-dimensional (4D) intravital microscopy to demonstrate that the site and order of function of PECAM and CD99 in vivo are dependent on the strain of mice. In FVB/n mice, PECAM functions upstream of CD99, as in human cells in vitro, and blocking antibodies against either molecule arrest neutrophils before they traverse the endothelium. However, in C57BL/6 mice, PECAM and CD99 appear to function at a different step, as the same antibodies arrest leukocyte migration through the endothelial basement membrane. These results are the first direct comparison of PECAM and CD99 function in different murine strains as well as the first demonstration of the sequential function of PECAM and CD99 in vivo.