dsRNA activation of endothelin-1 and markers of vascular activation in endothelial cells and fibroblasts.
BACKGROUND
In patients with systemic sclerosis (SSc), the relationship between innate immune activation, represented by increased expression of interferon (IFN)-regulated genes, and vascular injury/activation, manifest by increased endothelin-1 (ET-1), endothelin converting enzyme-1 (ECE1) and intercellular adhesion molecule-1, is uncertain.


OBJECTIVE
To investigate the potential roles of innate immune ligands in both these pathogenic pathways.


METHODS
The effect of known Toll-like receptor (TLR) ligands was tested in vitro on dermal microvascular and pulmonary arterial endothelial cells, and on dermal fibroblasts cultured from healthy controls and patients with SSc. To test the effect of double-stranded RNA (dsRNA) on vascular activation/injury in vivo, polyinosinic/polycytidylic acid (poly(I:C)) was administered continuously over 7 days by subcutaneous osmotic pump.


RESULTS
dsRNA/poly(I:C), but not other TLR ligands, highly stimulated ET-1 protein and mRNA (EDN1), as well as intercellular adhesion molecule-1 (ICAM-1) and IFN-regulated MX2, by endothelial cells and dermal fibroblasts. Poly(I:C) induced EDN1, ECE1, and ICAM-1 mRNA expression in poly(I:C) treated skin. Poly(I:C)-induced EDN1, ECE1 and MX2 was not blocked in mice with the type I IFN receptor deleted. However, poly(I:C)-induced EDN1 and ECE1, but not poly(I:C)-induced ICAM-1 expression was blocked in mice with the TLR3 signalling protein TRIF/TICAM-1 deleted.


CONCLUSIONS
Together these data show that the dsRNA can regulate genes associated with vascular activation, as seen in SSc, that type I IFNs do not mediate these effects, and that EDN1 and ECE1 but not ICAM-1 activation is mediated by TLR3.
Boston University School of Medicine, Arthritis Center, E5, 72 E Concord Street, Boston, MA 02118, USA.
Giuseppina
G
Farina
Michael
M
York
Cindy
C
Collins
Robert
R
Lafyatis
D000818:Animals; D002478:Cells, Cultured; D042783:Endothelial Cells / Q000187:drug effects / Q000378:metabolism; D019332:Endothelin-1 / Q000096:biosynthesis* / Q000235:genetics; D004730:Endothelium, Vascular / Q000187:drug effects / Q000378:metabolism; D005347:Fibroblasts / Q000378:metabolism*; D019204:GTP-Binding Proteins / Q000096:biosynthesis / Q000235:genetics; D005786:Gene Expression Regulation; D006801:Humans; D007113:Immunity, Innate; D008024:Ligands; D051379:Mice; D008810:Mice, Inbred C57BL; D064547:Myxovirus Resistance Proteins; D011070:Poly I-C / Q000494:pharmacology; D011651:Pulmonary Artery / Q000187:drug effects / Q000378:metabolism; D012330:RNA, Double-Stranded / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics; D012595:Scleroderma, Systemic / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D012867:Skin / Q000378:metabolism; D051196:Toll-Like Receptor 3 / Q000378:metabolism
D019332:Endothelin-1; D008024:Ligands; C579067:Mx2 protein, mouse; D064547:Myxovirus Resistance Proteins; D012330:RNA, Double-Stranded; D012333:RNA, Messenger; C495344:TLR3 protein, human; D051196:Toll-Like Receptor 3; D019204:GTP-Binding Proteins; D011070:Poly I-C