Chemokine receptor-mediated delivery directs self-tumor antigen efficiently into the class II processing pathway in vitro and induces protective immunity in vivo

Abstract

Nonimmunogenic antigens can be efficiently rendered immunogenic by targeting them to antigen-presenting cells via differentially expressed chemokine receptors. For example, self-tumor or HIV antigens genetically fused with proinflammatory chemoattractants elicit potent immune responses and protective antitumor immunity in mice. Herein we demonstrate that the mechanism by which chemokine fusions elicit responses is efficient uptake, processing, and presentation of antigens via the major histocompatibility complex class II pathway. Experiments with inhibitors of intracellular trafficking suggest that chemoattractant fusion proteins, but not antigen alone, were processed and presented through early/late endosomal and Golgi compartments and stimulated antigen-specific CD4 ؉ T cells both in vitro and in vivo. IntroductionCell trafficking is regulated by differential expression of heterotrimeric Gi protein coupled 7-transmembrane-domain chemokine receptors (GPCRs). 1 Sentinel antigen-presenting cells (APCs), the immature dendritic cells (DCs), preferentially express CCR1, CCR2, CCR5, and CCR6. [2][3][4] Upon ligand binding the receptor is phosphorylated and endocytosed through clathrin-coated vesicles using ␤-arrestin adaptors, [5][6][7] although some viral chemokine receptors, such as US28, are endocytosed independently of ␤-arrestins. 8 The internalized receptors may then be dephosphorylated and recycled back to the cell surface or targeted for degradation. 5,9 CCR5 is transported to early endosomes and subsequently recycled to the cell surface, bypassing the Golgi apparatus and late endosomes, and this process does not involve protein synthesis. 5 Upon chemokine receptor binding, the chemokine ligand is also internalized although its fate is not known and presumed to be degraded. Moreover, the fate of the internalized receptor and the bound ligand may be regulated by the strength of the ligandinduced signaling or the nature of the ligand itself. For example, CCR5 is endocytosed through clathrin-coated vesicles on binding to RANTES or AOP-RANTES (aminooxypentane regulated-onactivation normal T-expressed and secreted), although the latter drives CCR5 to a degradation pathway, whereas RANTES-bound CCR5 is recycled to the cell surface. 5,10 The internalized receptors are degraded by proteosomes, which are considered as major regulators of cytokine receptor expression. [11][12][13] Active immunotherapy based on the targeting of idiotypic antigen (Id), expressed by malignant B cells, is one of the most promising human cancer vaccine approaches. 14 Recently, we have demonstrated that effective adaptive immunity against weakly immunogenic tumor antigens could be induced by targeted delivery of such antigens to chemokine receptors on professional APCs by linkage to their chemoattractant ligands (␤-defensins or chemokines). Mice immunized with chemoattractants fused with nonimmunogenic lymphoma Id or sFv elicited potent anti-idiotypic responses and were protected from challenge with a lethal dose of syngeneic lymphoma cells...

Manipulating the chemokine‐chemokine receptor network to treat cancer

“…Genetic fusion of a model nonimmunogenic tumor antigen with inflammatory chemokines generated antigen-specific, humoral, and cellular protective antitumor immunity in 2 different syngeneic mouse models. 97 Generation of immunity depended on chemokine-mediated antigen delivery to chemokine receptors on DCs to induce receptor-mediated uptake and subsequent processing and presentation of the antigen to both CD41 98 and CD81 99 T lymphocytes ( Fig. 2A).…”

A vaccine directed to B cells and produced by cell-free protein synthesis generates potent antilymphoma immunity

“…A common approach is to produce fusions of Id sequences to targeting moieties that direct the construct to cytokine receptors or to other activating receptors on dendritic cells, macrophages, and other antigen-presenting cells (APCs) (19,22,23). The peptides derived from Id proteins would then be presented to T cells (24,25).…”

Tumor-Associated Embryonic Antigen-Expressing Vaccines that Target CCR6 Elicit Potent CD8+ T Cell-Mediated Protective and Therapeutic Antitumor Immunity

“…Generation of DNA vaccine constructs expressing murine MIP3␣/CCL20, murine ␤-defensin 2 (mDF2␤), and Hsp70 fused with tumor Ags (OFAiLRP or sFv20) was previously described (14). Mycobacterium Hsp70 cDNA was a gift from Dr. T. Lehner (Guy's Hospital, London, U.K.).…”

“…Murine bone marrow-derived DC preparation was previously described (21). Cells used on day 4 -5 of cultivation usually yield iDCs (14,15). Surface expression of OFA-iLRP was evaluated using anti-OFA-iLRP mAb 43515 (gift from Drs.…”

“…Mice immunized with chemokine fused to Id elicited potent protective and therapeutic antitumor responses when challenged with a lethal dose of syngeneic tumor cells. The vaccine required that Id was physically fused with a functionally active chemokine to be efficiently taken up, processed, and presented by APCs both in an MHC class I (MHC-I)-and class II-restricted fashion (14,15). Therefore, we wanted to test whether the same simple vaccine strategy could also induce antitumor immunity against murine B cell lymphomas when OFA-iLRP would be used.…”