Session 46Poster Presentations DC-SIGN and Related Molecules Session Day and Time: Thursday 1:30 - 3:30 pm Room: Hall D
369 Cytokine Regulation of DC-SIGN Expression in Human Monocytes and Effect on HIV-1 Transmission J. Chehimi, L. Azzoni*, Q. Luo, L. Shawver, N. Ngoubilly, R. June, G. Jerandi, E. Papasavvas, L. Montaner Wistar Inst, Philadelphia, PA
Background: Originally described by its binding properties to HIV envelope glycoproteins, Dendritic Cell Specific ICAM3 Grabbing Nonintegrin (DC-SIGN) plays a key role in the initiation of immune responses through DC-T-lymphocytes clustering. In addition, DC-SIGN, expressed in a variety of DC mediates efficient HIV trans-infection of T-cells. To gain further insights into the regulation of DC-SIGN in monocytes, we performed a detailed analysis of its expression in primary monocytes upon exposure to Th1 or Th2 cytokines and examined its role in viral transmission to T-cells.
Methods: Blood-derived monocytes (adherence or elutriation: 1 x 106/well) were cultured with IL-4 (10 ng/ml), IL-13 (10 ng/ml) or IFN-gamma (10 ng/ml). DC-SIGN expression was evaluated at day 1, 3, 5, and 7 by RT-PCR, immunofluorescence, and Western blot (using CD209 antibody). HIV-1-X4 transmission from untreated or cytokine-treated monocytes was evaluated. Monocytes were pulsed with an X 4 strain for 3 hrs, extensively washed, and co-cultured with SUP-T1 cells. HIV p24 Ag contents were determined at day 1, 5, and 7.
Results: Untreated 7-day-old monocyte-derived macrophages had higher DC-SIGN levels than fresh blood-derived monocytes, as determined by RT-PCR and Western blot. IL-4 and IL-13 treatment resulted in a significant increase of DC-SIGN mRNA surface expression and total protein after 1 day when compared to untreated cells. This increase was observed in all donors tested (n = 10). Treatment with IFN-gamma resulted in lower induction of DC-SIGN surface expression as compared to IL-4 and IL-13; however, total protein and mRNA levels were similar with IFN-gamma, IL-4, and IL-13. Transmission of H IV-X4 strain from 7-day treated monocytes to T-cells was found to be variable and did not correlate with DC-SIGN expression levels.
Conclusions: Type-2 cytokines (IL-4 and IL-13) induced high levels of DC-SIGN expression in monocytes. IFN-gamma induced lower levels of DC-SIGN expression at the cell surface than IL-4 and IL-13, but resulted in similar induction of DC-SIGN mRNA and total protein levels. Viral transmission of X4 HIV-1 from monocytes to T-cells was variable and independent of DC-SIGN expression.
