VLA-4 blockade by natalizumab inhibits sickle reticulocyte and leucocyte adhesion during simulated blood flow.
Very Late Antigen-4 (VLA-4, α4β1-integrin, ITGA4) orchestrates cell-cell and cell-endothelium adhesion. Given the proposed role of VLA-4 in sickle cell disease (SCD) pathophysiology, we evaluated the ability of the VLA-4 blocking antibody natalizumab to inhibit SCD blood cell adhesion. Natalizumab recognized surface VLA-4 on leucocytes and reticulocytes in whole blood from SCD subjects. SCD reticulocytes were positive for VLA-4, while VLA-4 staining of non-SCD reticulocytes was undetectable. Titrations with natalizumab revealed the presence of saturable levels of VLA-4 on both SCD reticulocytes and leucocytes similar to healthy subject leucocytes. Under physiological flow conditions, the adhesion of SCD whole blood cells and isolated SCD leucocytes to immobilized vascular cell adhesion molecule 1 (VCAM-1) was blocked by natalizumab in a dose-dependent manner, which correlated with cell surface receptor binding. Natalizumab also inhibited >50% of whole blood cell binding to TNF-α activated human umbilical vein endothelial cell monolayers under physiological flow at clinically relevant concentrations (10 to 100 μg/ml). This indicates that VLA-4 is the dominant receptor that drives SCD reticulocyte and mononuclear cell adhesion to VCAM-1 and that the VLA-4 adhesion to VCAM-1 is a significant contributor to SCD blood cell adhesion to endothelium. Thus, VLA-4 blockade may be beneficial in sickle cell disease.
Carman and Ann Adams Department of Pediatrics, Wayne State University School of Medicine, Detroit, MI, USA.
Jennell
J
White
Biogen, Cambridge, MA, USA.
Sriram
S
Krishnamoorthy
Biogen, Cambridge, MA, USA.
Dipti
D
Gupta
Division of Hematology/Oncology, Children's Hospital of Michigan, Detroit, MI, USA.
Moira
M
Lancelot
Biogen, Cambridge, MA, USA.
Nancy
N
Moore
Division of Hematology/Oncology, Children's Hospital of Michigan, Detroit, MI, USA.
Sharada
S
Sarnaik
Biogen, Cambridge, MA, USA.
William E
WE
Hobbs
Biogen, Cambridge, MA, USA.
David R
DR
Light
Carman and Ann Adams Department of Pediatrics, Wayne State University School of Medicine, Detroit, MI, USA.|Division of Critical Care Medicine, Children's Hospital of Michigan, Detroit, MI, USA.|Department of Physiology, Wayne State University School of Medicine, Detroit, MI, USA.
Patrick
P
Hines
D000293:Adolescent; D000328:Adult; D000755:Anemia, Sickle Cell / Q000097:blood* / Q000175:diagnosis / Q000188:drug therapy; D015415:Biomarkers; D002448:Cell Adhesion / Q000187:drug effects*; D002462:Cell Membrane / Q000378:metabolism; D002648:Child; D002675:Child, Preschool; D003198:Computer Simulation; D042783:Endothelial Cells / Q000187:drug effects / Q000378:metabolism; D005260:Female; D005434:Flow Cytometry; D006439:Hemodynamics; D006801:Humans; D007074:Immunoglobulin G / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology; D007223:Infant; D039041:Integrin alpha4beta1 / Q000037:antagonists & inhibitors*; D007962:Leukocytes / Q000187:drug effects* / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D000069442:Natalizumab / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*; D011485:Protein Binding; D055503:Protein Multimerization; D012156:Reticulocytes / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology*; D019010:Vascular Cell Adhesion Molecule-1 / Q000378:metabolism; D055815:Young Adult
D015415:Biomarkers; D007074:Immunoglobulin G; D039041:Integrin alpha4beta1; D000069442:Natalizumab; D019010:Vascular Cell Adhesion Molecule-1
adhesion; microfluidics; natalizumab; sickle cell; very late antigen-4