Important note: Information in this article was accurate in June 2002. The state of the art may have changed since the publication date.AIDSWEEKLY Plus; June 24, 2002
Michael Greer, Senior Medical Writer
"Dendritic cell-specific ICAM-3 grabbing nonintegrin (DC-SIGN) is a monocyte-derived dendritic cell (MDDC)-specific lectin which participates in dendritic cell (DC) migration and DC-T lymphocyte interactions at the initiation of immune responses and enhances trans-infection of T cells through its HIV gp120-binding ability," explained Dr. Miguel Relloso and colleagues at Gregorio Maranon General University Hospital in Madrid.
DC-SIGN expression relies on the activity of a few cytokines, whose suppression could help protect T cells from HIV infection, Relloso and coauthors say.
The Th2 cytokine interleukin (IL)-4 is responsible for inducing DC-SIGN expression during DC differentiation from monocytes, they found. The combination of IL-4 and granulocyte-macrophage colony-stimulating factor (GM-CSF) strongly upregulated DC-SIGN on immature cells.
Archetypical Th1 cytokines such as interferon-(gamma), and negative autocrine regulators like transforming growth factor-(beta) profoundly inhibited IL-4 activity, which prevented undifferentiated monocytes from expressing DC-SIGN mRNA. The anti-inflammatory drug dexamethasone also blocked DC-SIGN expression, by shutting down the process of monocyte differentiation, study data showed.
It is important to note agents that suppressed DC-SIGN expression also prevented HIV gp120 from efficiently binding to differentiating cells (DC-SIGN (CD209) expression is IL-4 dependent and is negatively regulated by IFN, TGF-beta, and anti-inflammatory agents, J Immunol 2002 Mar 15;168(6):2634-43.
"These results demonstrate that DC-SIGN...is a molecule specifically expressed on IL-4-treated monocytes, and whose expression is subjected to a tight regulation by numerous cytokines and growth factors," Relloso and colleagues concluded. "This feature might help in the development of strategies to modulate the DC-SIGN-dependent cell surface attachment of HIV for therapeutic purposes."
The corresponding author for this report is Dr. Angel L. Corbi, Consejo Superior de Investigaciones Cientificas, Centro de Investigaciones Biologicas, Velazquez 144, E-28006 Madrid, Spain.
A search at www.NewsRx.net using the search term "AIDS and HIV therapy" yielded 1101 articles in 27 specialized reports.
Key points reported in this study include:
This article was prepared by AIDS Weekly editors from staff and other reports.
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