Streng-Ouwehand I, Ho NI, Litjens M, Kalay H, Boks MA, Cornelissen LAM, Kaur Singh S, Saeland E, Garcia-Vallejo JJ, Ossendorp FA, Unger WWJ, van Kooyk Y. Glycan modification of antigen alters its intracellular routing in dendritic cells, promoting priming of T cells.
eLife 2016;
5. [PMID:
26999763 PMCID:
PMC4811763 DOI:
10.7554/elife.11765]
[Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2015] [Accepted: 02/23/2016] [Indexed: 01/04/2023] Open
Abstract
Antigen uptake by dendritic cells and intracellular routing of antigens to specific compartments is regulated by C-type lectin receptors that recognize glycan structures. We show that the modification of Ovalbumin (OVA) with the glycan-structure LewisX (LeX) re-directs OVA to the C-type lectin receptor MGL1. LeX-modification of OVA favored Th1 skewing of CD4+ T cells and enhanced cross-priming of CD8+ T cells. While cross-presentation of native OVA requires high antigen dose and TLR stimuli, LeX modification reduces the required amount 100-fold and obviates its dependence on TLR signaling. The OVA-LeX-induced enhancement of T cell cross-priming is MGL1-dependent as shown by reduced CD8+ effector T cell frequencies in MGL1-deficient mice. Moreover, MGL1-mediated cross-presentation of OVA-LeX neither required TAP-transporters nor Cathepsin-S and was still observed after prolonged intracellular storage of antigen in Rab11+LAMP1+ compartments. We conclude that controlled neo-glycosylation of antigens can crucially influence intracellular routing of antigens, the nature and strength of immune responses and should be considered for optimizing current vaccination strategies.
DOI:http://dx.doi.org/10.7554/eLife.11765.001
Immune cells called dendritic cells play a crucial role in defending the body against tumor cells and invading viruses. The dendritic cells take up molecules called antigens from these threats and then display them on their surface. This enables the antigens to be identified by other immune cells that are capable of killing the viruses and the tumor cells. The dendritic cells recognize the antigens with the help of receptor proteins called C-type lectin receptors (CLRs). These receptors can bind to sugar molecules that are naturally found on many antigens. For example, a C-type lectin receptor called MGL1 can bind to sugars known as LewisX and Lewisa on tumor and virus proteins. However, it is not clear how important these receptors are in triggering immune responses.
An antigen called Ovalbumin – which is found in chicken egg white – can trigger immune responses in mammals and so researchers often use it to study the immune system. Although this antigen has several sugar molecules attached to it, quite a large amount of Ovalbumin is needed to trigger strong immune responses. Now, Streng-Ouwehand et al. examine whether attaching LewisX to Ovalbumin can results in stronger immune responses in mice.
The experiments show that injecting mice with Ovalbumin-LewisX triggers a much stronger immune response than normal Ovalbumin does. This enhanced response was not observed in mice that lacked the MGL1 receptor, which suggests that this receptor is involved in detecting Ovalbumin-LewisX. Furthermore, the dendritic cells store the altered Ovalbumin for longer than they store normal Ovalbumin, which gives the cells more time to present the altered Ovalbumin to other immune cells.
Vaccines and some other therapies help to boost immune responses to viruses and tumors by exposing the body to antigens. However, these therapies often use antigens that don’t have sugar molecules attached to them, or are missing the sugar molecules they would normally have. Streng-Ouwehand et al.’s findings suggest that adding specific sugars to antigens in immune therapies might help to make these therapies more effective.
DOI:http://dx.doi.org/10.7554/eLife.11765.002
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