Endothelin-1 regulation of intercellular adhesion molecule-1 expression in normal and sclerodermal fibroblasts.
We investigated the potential modulation of cell surface intercellular adhesion molecule-1 (ICAM-1) expression and function by ET-1 in fibroblasts grown from skin biopsies of scleroderma (SSc) patients compared with healthy controls. Surface ICAM-1 expression was quantified by cell-bound ELISA and by FACS analysis. ICAM-1 function was investigated by measuring cell adhesion, and we studied ICAM-1 gene expression using RT-PCR. Fibroblast ET-1 binding sites were measured using 125I-labeled ET-1, and the modulation of ICAM-1 function by ET-1 was determined by measuring the binding of human U937 cells to fibroblasts in the presence of a mixed ETA/B receptor antagonist (bosentan) or a neutralizing anti-ICAM-1 antibody. ICAM-1 expression was significantly higher in SSc fibroblasts compared with normal controls. ET-1 increased ICAM-1 on both normal and SSc fibroblasts to comparable levels. RT-PCR demonstrated that ICAM-1 mRNA was upregulated by ET-1, and results from binding studies showed fibroblasts exposed to ET-1 supported more U937 cells than controls, a process that could be inhibited by bosentan and ICAM-1 neutralizing antibody. Autoradiography showed ET-1 receptors on both normal and SSc fibroblasts. Our findings indicate that SSc fibroblasts express intrinsically elevated levels of surface ICAM-1 and message. ET-1 can induce normal fibroblasts to express some SSc phenotypes and may function as a potent proinflammatory mediator, similar to cytokines, and therefore may also have immunoregulatory functions for immune cells infiltrating and binding to connective tissues.
Xu
S W
SW
Academic Unit of Rheumatology, Royal Free Hospital School of Medicine, London, England.
Denton
C P
CP
Dashwood
M R
MR
Abraham
D J
DJ
Black
C M
CM
D001345:Autoradiography; D002448:Cell Adhesion; D002478:Cells, Cultured; D019332:Endothelin-1 / Q000187:drug effects / Q000502:physiology*; D005347:Fibroblasts / Q000187:drug effects / Q000378:metabolism; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D018799:Intercellular Adhesion Molecule-1 / Q000096:biosynthesis* / Q000235:genetics; D016133:Polymerase Chain Reaction; D012595:Scleroderma, Systemic / Q000378:metabolism*
D019332:Endothelin-1; D018799:Intercellular Adhesion Molecule-1