Related Experiment Video
Updated: May 12, 2026
Use of Single Chain MHC Technology to Investigate Co-agonism in Human CD8+ T Cell Activation
Published on: February 28, 2019
Tn-Glycoconjugates engage MGL2 to potentiate TLR9-mediated dendritic cell maturation and Th1-skewed immune responses
Carolina Chiale1, Sylvie Bay2, Christelle Ganneau2
1Laboratorio de Inmunomodulación y Vacunas, Unidad Académica de Inmunobiología, Facultad de Medicina, Universidad de la República, Montevideo, Uruguay.
Abstract:
Dendritic cells (DCs) orchestrate antitumor immunity by integrating signals from the tumor microenvironment to prime effective T cell responses. Many tumors display altered glycosylation patterns, including tumor-associated carbohydrate antigens (TACAs) such as the Tn antigen (GalNAcα1-O-Ser/Thr); yet how these structures influence DC function is not well defined. Here, we investigated how Tn-bearing glycoconjugates modulate DC activation and shape adaptive immunity. Bone marrow-derived DCs (BMDCs) efficiently internalized fluorescently labeled Tn-glycoconjugates, whereas uptake of non-glycosylated counterparts was negligible. Although Tn-glycoconjugates alone did not induce DC maturation, co-stimulation with the Toll-like receptor 9 (TLR9) agonist CpG markedly increased CD86 expression and the secretion of IL-12/23p40 and IL-6, with the multivalent construct MAG:Tn3-PV eliciting the strongest response. These conditioned BMDCs promoted strong IFN-γ production by allogeneic splenocytes, consistent with a Th1-polarizing phenotype. Mechanistically, both uptake and CpG-enhanced activation required the C-type lectin receptor MGL2, as blockade of MGL or competition with GalNAc abrogated glycoconjugate uptake and CpG-enhanced cytokine induction. Pharmacological inhibition revealed that MGL2 signaling synergizes with TLR9 through the Syk-Raf-1-NF-κB axis. In vivo, mice immunized with DCs conditioned with Tn-glycoconjugate- plus CpG displayed enhanced splenocyte proliferation, increased IFN-γ secretion, and elevated cytotoxic activity without IL-10 induction, confirming a Th1-skewed response. Collectively, these findings identify MGL2 as a critical mediator of Tn-glycoconjugate sensing and unveil a synergistic C-type lectin receptor (CLR)-TLR9 cross-talk that amplifies DC maturation and cytotoxic immunity. This study provides mechanistic insight into how specific glycan-lectin interactions fine-tune innate receptor signaling, highlighting the potential of Tn-based glycoconjugates as immunomodulatory tools for vaccine design and cancer immunotherapy.
Insights
Tumor-associated carbohydrate antigens (TACAs) like the Tn antigen can be sensed by dendritic cells (DCs) via the MGL2 receptor. This interaction enhances DC activation, promoting anti-tumor immunity and Th1-skewed responses.
Area of Science:
- Immunology
- Glycobiology
- Cancer Research
Background:
- Dendritic cells (DCs) are crucial for initiating antitumor immune responses.
- Tumor cells often exhibit altered glycosylation, presenting tumor-associated carbohydrate antigens (TACAs) like the Tn antigen.
- The impact of TACAs on DC function and adaptive immunity remains incompletely understood.
Purpose of the Study:
- To investigate how Tn-bearing glycoconjugates modulate dendritic cell activation.
- To elucidate the role of specific receptors in sensing these glycoconjugates.
- To determine the downstream effects on adaptive immune responses and their potential in cancer immunotherapy.
Main Methods:
- Bone marrow-derived dendritic cells (BMDCs) were incubated with fluorescently labeled Tn-glycoconjugates.
- DC maturation and cytokine secretion (IL-12/23p40, IL-6) were assessed upon co-stimulation with Toll-like receptor 9 (TLR9) agonist CpG.
- The role of C-type lectin receptor MGL2 was evaluated using receptor blockade and competitive inhibition.
- Signaling pathways (Syk-Raf-1-NF-κB) were investigated.
- In vivo studies involved immunizing mice with conditioned DCs and assessing splenocyte proliferation, cytokine production, and cytotoxic activity.
Main Results:
- BMDCs efficiently internalized Tn-glycoconjugates.
- Co-stimulation with CpG significantly enhanced DC activation markers (CD86) and cytokine secretion, particularly with multivalent constructs.
- Conditioned DCs induced a Th1-polarizing phenotype, promoting IFN-γ production.
- MGL2 was identified as the key receptor for glycoconjugate uptake and CpG-enhanced activation.
- MGL2 and TLR9 signaling synergize via the Syk-Raf-1-NF-κB pathway.
- In vivo immunization resulted in enhanced T cell proliferation, IFN-γ secretion, and cytotoxic activity, indicative of a Th1-skewed response.
Conclusions:
- MGL2 is essential for sensing Tn-glycoconjugates and synergizes with TLR9 to amplify DC maturation and cytotoxic immunity.
- Glycan-lectin interactions fine-tune innate receptor signaling, offering insights into cancer immunotherapy.
- Tn-based glycoconjugates hold potential as immunomodulatory agents for vaccine design and cancer treatment.
Related Concept Videos
01:22T Cell Activation and Clonal Selection
Naive T cells that have not yet encountered an antigen express two primary CD...
01:26Antigens Involved in Adaptive Immunity
Complete Antigens
Complete antigens possess both immunogenicity and reactivity.
01:31Antigen Processing Pathways
MHC Class I: Presenting Endogenous...
01:27Cytotoxic T Cells-mediated Immune Response
Immunological surveillance is the ability of immune cells to monitor and eliminate infected cells with intracellular pathogens, neoplastically transformed cells, and cells with non-self antigens. Cytotoxic T cells and NK...
01:24B Cell Activation and Differentiation
When naive B cells encounter a specific antigen that can bind to the B cell receptor (BCR) on their surface, they undergo sensitization to respond to the antigen's presence. Sensitization begins with...
01:40Cell-mediated Immune Responses