Regulation of Gene Expression of Murine MD-1 Regulates Subsequent T Cell Activation and Cytokine Production

Abstract

The immunoadhesin (OX2:Fc) comprising the extracellular domain of murine OX2 linked to IgG2aFc, inhibits production of IL-2 and IFN-γ by activated T cells and increases allograft and xenograft survival in vivo. Increased expression of OX2 on dendritic cells (DC) in vivo following preimmunization via the portal vein is also associated with elevated expression of MD-1. We have used antisense oligodeoxynucleotides (ODNs) to MD-1 to investigate the effect of inhibition of expression of MD-1 by DC on their function as allostimulatory cells. We also investigated by FACS analysis the cell surface expression of OX2, CD80, and CD86 on DC incubated with ODN-1 blocking MD-1 expression. Blocking MD-1 gene expression inhibits surface expression of CD80 and CD86, but not of OX2. DC incubated with ODN-1 to MD-1 did not stimulate IL-2 or IFN-γ production, but generated cells able to suppress, in a second culture of fresh DC plus allogeneic T cells, production of IL-2 and IFN-γ. This inhibition was blocked by anti-OX2 mAb. Infusion of DC preincubated with ODN-1 prolonged renal allograft survival, an effect also reversed by anti-OX2 mAb. By FACS, incubation of DC with anti-MD-1 Ab to promote capping eliminated cell surface expression of MD-1 and CD14 without altering DEC205, DC26, CD80, CD86, or OX2 expression. Thus OX2 and MD-1 are independent surface molecules on DC that may reciprocally regulate T cell stimulation. MD-1 is linked to CD14, a “danger receptor complex,” and activation of this complex can regulate cell surface expression of CD80/CD86, which signal T cells.

Immune Modulation by Silencing IL-12 Production in Dendritic Cells Using Small Interfering RNA

“…We and others have used DC-modifying approaches for induction of tolerance or treatment of autoimmunity (22,41). Although antisense manipulation of DC has previously been reported (42), low transfection efficacy of DNA into DC presents a problem for widespread use of this approach (43). In contrast, transfection of DC with siRNA is quite efficient and therefore may offer the possibility of treating immune-based diseases in a specific and effective manner.…”

Requirement for MD-1 in cell surface expression of RP105/CD180 and B-cell responsiveness to lipopolysaccharide

“…B cells, on the other hand, have an additional recognition or signaling pathway through RP105/MD-1. Gorczynski et al 29 showed that MD-1 down-regulation with the antisense oligodeoxynucleotides led to impairment in LPS-induced CD80/CD86 up-regulation on bone marrow-derived dendritic cells. The antisense treatment is likely to result in the down-regulation of RP105/MD-1.…”

MD‐1 expression regulates direct and indirect allorecognition

“…Previous work from this and other laboratories suggested that the molecule MD‐1 was involved in the transmission of activation signals within lymphoid cells (12, 13). The molecule is thought to act by stabilizing expression of cell‐surface coreceptors which transmit signals leading to the activation of nuclear factor‐κB (NF‐κB) in APCs, which in turn can result in enhanced expression of the costimulatory molecules CD80/CD86 (12–15).…”

“…Previous work from this and other laboratories suggested that the molecule MD‐1 was involved in the transmission of activation signals within lymphoid cells (12, 13). The molecule is thought to act by stabilizing expression of cell‐surface coreceptors which transmit signals leading to the activation of nuclear factor‐κB (NF‐κB) in APCs, which in turn can result in enhanced expression of the costimulatory molecules CD80/CD86 (12–15). We have shown in addition that functional blockade of MD‐1 expression results in decreased expression of these costimulatory molecules, prolongs both allogeneic and xenogeneic skin graft survival in mice, and prevents type‐1 cytokine‐induced fetal loss (12, 14, 16).…”