Helminths express various carbohydrate-containing glycoconjugates on their surface, and they release glycan-rich excretion/secretion products that can be very important in their life cycles, infection and pathology. Recent evidence suggests that parasite glycoconjugates could play a role in the evasion of the immune response, leading to a modified Th2-polarized immune response that favors parasite survival in the host. Nevertheless, there is limited information about the nature or function of glycans produced by the trematode Fasciola hepatica, the causative agent of fasciolosis. In this paper, we investigate whether glycosylated molecules from F. hepatica participate in the modulation of host immunity. We also focus on dendritic cells, since they are an important target of immune-modulation by helminths, affecting their activity or function. Our results indicate that glycans from F. hepatica promote the production of IL-4 and IL-10, suppressing IFNγ production. During infection, this parasite is able to induce a semi-mature phenotype of DCs expressing low levels of MHCII and secrete IL-10. Furthermore, we show that parasite glycoconjugates mediate the modulation of LPS-induced maturation of DCs since their oxidation restores the capacity of LPS-treated DCs to secrete high levels of the pro-inflammatory cytokines IL-6 and IL-12/23p40 and low levels of the anti-inflammatory cytokine IL-10. Inhibition assays using carbohydrates suggest that the immune-modulation is mediated, at least in part, by the recognition of a mannose specific-CLR that signals by recruiting the phosphatase Php2. The results presented here contribute to the understanding of the role of parasite glycosylated molecules in the modulation of the host immunity and might be useful in the design of vaccines against fasciolosis.

In vivo targeting of C-type lectin receptors is an effective strategy for increasing antigen uptake and presentation by den-dritic cells (DCs). To induce efficient immune response, glycosylated tumor-associated Tn antigens were used to target DCs through binding to macrophage galactose-type lectin (MGL). The capacity of Tn-glycosylated antigens-and the multiple antigenic glycopeptide Tn3 therapeutic candidate vaccine-to target mouse and human MGL DCs are demonstrated, especially regarding dermal DCs. In mice, MGL CD103 dermal DCs efficiently captured and processed glycosylated Tn an-tigen in vivo, inducing a potent major histocompatibility complex (MHC) class II-restricted T-cell response. Intradermal immunization with Tn-glycopeptides induced high levels of Th2 cytokines-even in the presence of unmethylated cytosine-phosphate-guanosine-and was associated with increased expansion of the germinal center B-cell population. Therefore, MGL acts as an efficient endo-cytic antigen receptor on dermal DCs in vivo, able to prime Tn-specific T-and B-cell responses. Moreover, even in the absence of adjuvant, immunization with this glycosidic Tn-based vaccine induced high levels of anti-Tn antibody responses, recognizing human tumor cells. In vivo DC-targeting strategies, based on Tn-MGL interactions, constitute a promising strategy for enhancing anti-gen presentation and inducing potent antibody response. (Blood. 2010;116(18): 3526-3536)

Trypanosoma cruzi, the protozoan parasite that causes Chagas' disease, has anticancer effects mediated, at least in part, by parasitederived products which inhibit growth of tumor cells. We investigated whether immunity to T. cruzi antigens could induce antitumor activity, using two rat models which reproduce human carcinogenesis: colon cancer induced by 1,2-dimethylhydrazine (DMH), and mammary cancer induced by N-nitroso-N-methylurea (NMU). We found that vaccination with T. cruzi epimastigote lysates strongly inhibits tumor development in both animal models. Rats immunized with T. cruzi antigens induce activation of both CD4 1 and CD8 1T cells and splenocytes from these animals showed higher cytotoxic responses against tumors as compared to rats receiving adjuvant alone. Tumor-associated immune responses included increasing number of CD11b/c 1 His48 2 MHC II 1 cells corresponding to macrophages and/or dendritic cells, which exhibited augmented NADPH-oxidase activity. We also found that T. cruzi lysate vaccination developed antibodies specific for colon and mammary rat cancer cells, which were capable of mediating antibody-dependent cellular cytotoxicity (ADCC) in vitro. Anti-T. cruzi antibodies cross-reacted with human colon and breast cancer cell lines and recognized 41/60 (68%) colon cancer and 38/63 (60%) breast cancer samples in a series of 123 human tumors. Our results suggest that T. cruzi antigens can evoke an integrated antitumor response involving both the cellular and humoral components of the immune response and provide novel insights into the understanding of the intricate relationship between parasite infection and tumor growth.