In Vivo CD40-CD154 (CD40 Ligand) Interaction Induces Integrated HIV Expression by APC in an HIV-1-Transgenic Mouse Model

Abstract

Because of their relative resistance to viral cytopathic effects, APC can provide an alternative reservoir for latently integrated HIV. We used an HIV-transgenic mouse model in which APC serve as the major source of inducible HIV expression to study mechanisms by which integrated virus can be activated in these cells. When admixed with transgenic APC, activated T lymphocytes provided a major contact-dependent stimulus for viral protein expression in vitro. Using blocking anti-CD154 mAb as well as CD154-deficient T cells, the HIV response induced by activated T lymphocytes was demonstrated to require CD40-CD154 interaction. The role of this pathway in the induction of HIV expression from APC in vivo was further studied in an experimental model involving infection of the HIV-transgenic mice with Plasmodium chabaudi parasites. Enhanced viral production by dendritic cells and macrophages in infected mice was associated with up-regulated CD40 expression. More importantly, in vivo treatment with blocking anti-CD154 mAb markedly reduced viral expression in P. chabaudi-infected animals. Together, these findings indicate that immune activation of integrated HIV can be driven by the costimulatory interaction of activated T cells with APC. Because chronic T cell activation driven by coinfections as well as HIV-1 itself is a characteristic of HIV disease, this pathway may be important in sustaining viral expression from APC reservoirs.

Failure of HIV-exposed CD4+ T cells to activate dendritic cells is reversed by restoration of CD40/CD154 interactions

“…Functional inhibition in AT-2 HIV-exposed or anti-CD154-treated T cells was defined by comparison with untreated cells. As expected on the basis of our previous results, 35 anti-CD154 Ab resulted in incomplete DC maturation and activation, as evidenced by a 60% to 75% decreased induction of CD86, CD83, and CD40, as well as decreased IL-12 p40 production ( Figure 4A). IL-12 p40 production, and expression of CD40 and CD83 were significantly decreased in anti-CD154-treated cultures (condition 3) compared with control cultures (condition 1) (all P Ͻ .02).…”

“…22 Similarly, production of IL-12 p40 by mouse DCs stimulated in a very similar experimental system as the one used herein (ie, in vitro coculture of mouse DCs with autologous activated T cells) was not inhibited by the control Ab. 35 On the basis of consistent results for these controls in past experiments, the isotype-matched control Ab for the anti-CD154 Ab was not included again in the present study.…”

“…Of note, we have previously used the appropriate isotype-matched control Abs for the CD154 Abs from Immunex. 22,35 In particular, human PBMCs stimulated in the presence of such control Abs exhibited normal production of IL-12. 22 Similarly, production of IL-12 p40 by mouse DCs stimulated in a very similar experimental system as the one used herein (ie, in vitro coculture of mouse DCs with autologous activated T cells) was not inhibited by the control Ab.…”

Macrophages and HIV-1: dangerous liaisons

“…As discussed above, the activation of macrophages through CD40L upregulates the expression of co-stimulatory molecules and leads to the production of inflammatory cytokines and chemokines that contribute to T cell activation at the site of inflammation. As a consequence, the CD40/CD40L interaction can activate X4 HIV-1 replication in CD4+ T cells (Chougnet et al, 2001;Kutsch et al, 2003;Swingler et al, 2003).…”

CD4-Specific Transgenic Expression of Human Cyclin T1 Markedly Increases Human Immunodeficiency Virus Type 1 (HIV-1) Production by CD4+T Lymphocytes and Myeloid Cells in Mice Transgenic for a Provirus Encoding a Monocyte-Tropic HIV-1 Isolate

“…The failure of HIV-1 to penetrate mouse cells can be circumvented by constructing mice transgenic for an infectious provirus derived from HIV-1, such as the X4 laboratory isolate NL4-3 (1,37). These transgenic mice have been used to investigate in vivo activation of HIV-1 in monocytes by pathogens (10,14,21,25), the efficacy of treatments that block proviral expression (55,56), and the role of Toll-like receptors in the pathogen-induced activation of the HIV LTR (2,16). To enable study of the behavior of primary HIV-1 isolates, we expanded upon this approach by developing a different mouse line that is transgenic for HIV-1 JR-CSF , a full-length HIV-1 provirus derived from the well-characterized primary R5-tropic clinical isolate (9,49).…”