Characterization of the secreted form of endothelial-cell-specific molecule 1 by specific monoclonal antibodies.
Endothelial-cell-specific molecule 1 (ESM-1) is a recently identified endothelial cell molecule. As ESM-1 mRNA is preferentially expressed in human lung and kidney tissues, and as ESM-1 mRNA expression is regulated by inflammatory cytokines, ESM-1 is thought to play a role in the vascular contribution to organ-specific inflammation. In order to define its behavior, mouse anti-ESM-1 monoclonal antibodies were developed, and three distinct epitopes were mapped, which allowed development of a specific ELISA assay, immunohistological staining and immunoblot analysis. Here, we demonstrate that ESM-1 is present in cell lysates of human endothelial cells (human umbilical vein endothelial cells) with an apparent molecular weight of 20 kD. In contrast, the secreted form of ESM-1 is shifted to an apparent molecular weight of 50 kD, indicating that the secreted form of ESM-1 is posttranslationally modified. By ELISA, we show that the secretion of ESM-1 is significantly enhanced in the presence of TNFalpha. In contrast, the spontaneous as well as TNFalpha-induced secretion of ESM-1 is strongly inhibited by IFNgamma. Moreover, ESM-1 was detected in the serum of healthy subjects at an average concentration of 1.08 ng/ml, and we demonstrated that the serum level of ESM-1 is dramatically increased in patients presenting a septic shock. Analysis of ESM-1 expression in normal human tissues by immunohistochemistry showed that ESM-1 is localized in the vascular network, but also in the bronchial and renal epithelia. Our results demonstrate that ESM-1 is mainly expressed in the vascular endothelium both in vitro and in vivo, but also by different epithelia. ESM-1 may represent a new marker of endothelial cell activation, and may have a functional role in endothelium-dependent pathological disorders.
Bechard
D
D
INSERM U416, Institut Pasteur de Lille, Lille, France.
Meignin
V
V
Scherpereel
A
A
Oudin
S
S
Kervoaze
G
G
Bertheau
P
P
Janin
A
A
Tonnel
A
A
Lassalle
P
P
D000328:Adult; D000818:Animals; D000911:Antibodies, Monoclonal; D000918:Antibody Specificity; D015153:Blotting, Western; D004730:Endothelium, Vascular / Q000737:chemistry; D004797:Enzyme-Linked Immunosorbent Assay; D004848:Epithelium / Q000737:chemistry; D018604:Epitope Mapping; D005260:Female; D006084:Graft Rejection; D006801:Humans; D007163:Immunosorbent Techniques; D007668:Kidney / Q000098:blood supply; D016030:Kidney Transplantation; D008297:Male; D051379:Mice; D008875:Middle Aged; D009363:Neoplasm Proteins; D011506:Proteins / Q000032:analysis* / Q000276:immunology; D011509:Proteoglycans; D018805:Sepsis / Q000097:blood; D014471:Umbilical Veins
D000911:Antibodies, Monoclonal; C101134:ESM1 protein, human; D009363:Neoplasm Proteins; D011506:Proteins; D011509:Proteoglycans