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T cells at the site of autoimmune inflammation show increased potential for trogocytosis.

Haastert B, Mellanby RJ, Anderton SM, O'Connor RA - PLoS ONE (2013)

Bottom Line: During inflammation a locally elevated rate of trogocytosis (seen in both effector and regulatory T cells isolated from the inflamed CNS) precludes the use of trogocytosis as a measure of antigenic reactivity among cells taken from inflammatory sites.Our results indicate trogocytosis detection can enrich for Ag-reactive conventional T cells in the periphery but is limited in its ability to identify Ag-reactive Treg or T effector cells at sites of inflammation.Increased trogocytosis potential at inflammatory sites also draws into the question the biological significance of this phenomenon during inflammation, in Treg mediated suppression and for the maintenance of tolerance in health and disease.

View Article: PubMed Central - PubMed

Affiliation: Medical Research Council/University of Edinburgh Centre for Inflammation Research, Queen's Medical Research Institute, Edinburgh, United Kingdom.

ABSTRACT
CD4+ T cells acquire membrane fragments from antigen-presenting-cells via a process termed trogocytosis. Identifying which CD4+ T cells undergo trogocytosis in co-culture with Ag-loaded APC can enrich for antigen-reactive T cells without knowledge of their fine specificity or cytokine-production profiles. We sought to assess the suitability of this method to identify disease relevant effector and regulatory T cells during autoimmune inflammation. Trogocytosis efficiently identified MBP-reactive T cells in vitro and ex-vivo following immunization. However, Foxp3+ regulatory T cells constitutively displayed a higher rate of trogocytosis than their Foxp3- counterparts which limits the potential of trogocytosis to identify antigen-reactive Treg cells. During inflammation a locally elevated rate of trogocytosis (seen in both effector and regulatory T cells isolated from the inflamed CNS) precludes the use of trogocytosis as a measure of antigenic reactivity among cells taken from inflammatory sites. Our results indicate trogocytosis detection can enrich for Ag-reactive conventional T cells in the periphery but is limited in its ability to identify Ag-reactive Treg or T effector cells at sites of inflammation. Increased trogocytosis potential at inflammatory sites also draws into the question the biological significance of this phenomenon during inflammation, in Treg mediated suppression and for the maintenance of tolerance in health and disease.

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Increased membrane acquisition among CNS derived CD4+ T cells from mice with EAE.(A–C) EAE was induced in Foxp3GFP mice by immunization with pMOG in CFA. CNS and spleens were harvested from mice with EAE during recovery at d20 and CD4+ T cells were purified and co-cultured with biotinylated BMDC in the presence or absence of pMOG. B) Membrane acquisition by GFP− (B) and GFP+ (C) CD4+ T cells in the presence (closed bars) or absence (open bars) of pMOG error bars show SD. *p<0.05 Data shown is from one experiment representative of 2 similar experiments.
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pone-0081404-g005: Increased membrane acquisition among CNS derived CD4+ T cells from mice with EAE.(A–C) EAE was induced in Foxp3GFP mice by immunization with pMOG in CFA. CNS and spleens were harvested from mice with EAE during recovery at d20 and CD4+ T cells were purified and co-cultured with biotinylated BMDC in the presence or absence of pMOG. B) Membrane acquisition by GFP− (B) and GFP+ (C) CD4+ T cells in the presence (closed bars) or absence (open bars) of pMOG error bars show SD. *p<0.05 Data shown is from one experiment representative of 2 similar experiments.

Mentions: While various studies have shown an accumulation of FoxP3+ regulatory T cells in the CNS during the resolution phase of EAE[14], [19], [22], reviewed in [23], the antigens these Treg cells respond to remain largely unknown. Having observed antigen-specific membrane acquisition by naive T cells and Treg cells in vitro, and having demonstrated that trogocytosis can be used to identify activated T cells ex-vivo following immunization, we sought to determine the rate of membrane acquisition among effector and regulatory T cells in the CNS during autoimmune inflammation. EAE was induced in FoxP3 GFP reporter mice by immunization with pMOG35–55 CNS and spleens were harvested during recovery from disease. CD4+ T cells from naïve mice were included as steady state controls. CD4+ T cells purified from CNS or spleen were co-cultured with peptide-pulsed biotinylated BMDCs (Schematic Fig. 5A). Increased membrane uptake by CNS derived versus spleen derived cells was clearly apparent in GFP− cells (Fig. 5B). FoxP3− CD4+ T cells from naïve spleen showed no increased membrane transfer in response to pMOG35–55 (Fig. 5B). This was in agreement with our expectations, as the number of MOG auto-reactive cells is very low in non-immunized mice. In contrast to this, FoxP3− T cells derived from EAE spleen acquired membrane patches with significantly higher uptake in the presence of antigenic stimulation (Fig. 5B). However CNS-derived FoxP3− CD4+ T cells exhibited significantly enhanced membrane transfer in the absence of antigen, when compared to splenic Foxp3- cells from the same mice, indicative of the heightened activation status of effector T cells derived from a site of auto-immune inflammation (Fig. 3B). No antigen-driven trogocytosis was detected above this background level (Fig. 5B).


T cells at the site of autoimmune inflammation show increased potential for trogocytosis.

Haastert B, Mellanby RJ, Anderton SM, O'Connor RA - PLoS ONE (2013)

Increased membrane acquisition among CNS derived CD4+ T cells from mice with EAE.(A–C) EAE was induced in Foxp3GFP mice by immunization with pMOG in CFA. CNS and spleens were harvested from mice with EAE during recovery at d20 and CD4+ T cells were purified and co-cultured with biotinylated BMDC in the presence or absence of pMOG. B) Membrane acquisition by GFP− (B) and GFP+ (C) CD4+ T cells in the presence (closed bars) or absence (open bars) of pMOG error bars show SD. *p<0.05 Data shown is from one experiment representative of 2 similar experiments.
© Copyright Policy
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC3852262&req=5

pone-0081404-g005: Increased membrane acquisition among CNS derived CD4+ T cells from mice with EAE.(A–C) EAE was induced in Foxp3GFP mice by immunization with pMOG in CFA. CNS and spleens were harvested from mice with EAE during recovery at d20 and CD4+ T cells were purified and co-cultured with biotinylated BMDC in the presence or absence of pMOG. B) Membrane acquisition by GFP− (B) and GFP+ (C) CD4+ T cells in the presence (closed bars) or absence (open bars) of pMOG error bars show SD. *p<0.05 Data shown is from one experiment representative of 2 similar experiments.
Mentions: While various studies have shown an accumulation of FoxP3+ regulatory T cells in the CNS during the resolution phase of EAE[14], [19], [22], reviewed in [23], the antigens these Treg cells respond to remain largely unknown. Having observed antigen-specific membrane acquisition by naive T cells and Treg cells in vitro, and having demonstrated that trogocytosis can be used to identify activated T cells ex-vivo following immunization, we sought to determine the rate of membrane acquisition among effector and regulatory T cells in the CNS during autoimmune inflammation. EAE was induced in FoxP3 GFP reporter mice by immunization with pMOG35–55 CNS and spleens were harvested during recovery from disease. CD4+ T cells from naïve mice were included as steady state controls. CD4+ T cells purified from CNS or spleen were co-cultured with peptide-pulsed biotinylated BMDCs (Schematic Fig. 5A). Increased membrane uptake by CNS derived versus spleen derived cells was clearly apparent in GFP− cells (Fig. 5B). FoxP3− CD4+ T cells from naïve spleen showed no increased membrane transfer in response to pMOG35–55 (Fig. 5B). This was in agreement with our expectations, as the number of MOG auto-reactive cells is very low in non-immunized mice. In contrast to this, FoxP3− T cells derived from EAE spleen acquired membrane patches with significantly higher uptake in the presence of antigenic stimulation (Fig. 5B). However CNS-derived FoxP3− CD4+ T cells exhibited significantly enhanced membrane transfer in the absence of antigen, when compared to splenic Foxp3- cells from the same mice, indicative of the heightened activation status of effector T cells derived from a site of auto-immune inflammation (Fig. 3B). No antigen-driven trogocytosis was detected above this background level (Fig. 5B).

Bottom Line: During inflammation a locally elevated rate of trogocytosis (seen in both effector and regulatory T cells isolated from the inflamed CNS) precludes the use of trogocytosis as a measure of antigenic reactivity among cells taken from inflammatory sites.Our results indicate trogocytosis detection can enrich for Ag-reactive conventional T cells in the periphery but is limited in its ability to identify Ag-reactive Treg or T effector cells at sites of inflammation.Increased trogocytosis potential at inflammatory sites also draws into the question the biological significance of this phenomenon during inflammation, in Treg mediated suppression and for the maintenance of tolerance in health and disease.

View Article: PubMed Central - PubMed

Affiliation: Medical Research Council/University of Edinburgh Centre for Inflammation Research, Queen's Medical Research Institute, Edinburgh, United Kingdom.

ABSTRACT
CD4+ T cells acquire membrane fragments from antigen-presenting-cells via a process termed trogocytosis. Identifying which CD4+ T cells undergo trogocytosis in co-culture with Ag-loaded APC can enrich for antigen-reactive T cells without knowledge of their fine specificity or cytokine-production profiles. We sought to assess the suitability of this method to identify disease relevant effector and regulatory T cells during autoimmune inflammation. Trogocytosis efficiently identified MBP-reactive T cells in vitro and ex-vivo following immunization. However, Foxp3+ regulatory T cells constitutively displayed a higher rate of trogocytosis than their Foxp3- counterparts which limits the potential of trogocytosis to identify antigen-reactive Treg cells. During inflammation a locally elevated rate of trogocytosis (seen in both effector and regulatory T cells isolated from the inflamed CNS) precludes the use of trogocytosis as a measure of antigenic reactivity among cells taken from inflammatory sites. Our results indicate trogocytosis detection can enrich for Ag-reactive conventional T cells in the periphery but is limited in its ability to identify Ag-reactive Treg or T effector cells at sites of inflammation. Increased trogocytosis potential at inflammatory sites also draws into the question the biological significance of this phenomenon during inflammation, in Treg mediated suppression and for the maintenance of tolerance in health and disease.

Show MeSH
Related in: MedlinePlus