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TGF-β sensitivity restrains CD8+ T cell homeostatic proliferation by enforcing sensitivity to IL-7 and IL-15.

Johnson LD, Jameson SC - PLoS ONE (2012)

Bottom Line: Previous studies found that impairing TGF-β responsiveness (through expression of a dominant-negative TGF-β RII [DNRII] transgene) leads to accumulation of memory phenotype CD8 T cells, and it was proposed that this resulted from enhanced IL-15 sensitivity.DNRII transgenic CD8 T cells still require access to self Class I MHC for homeostatic proliferation, arguing against generalized dysregulation of homeostatic cues.These findings suggest TGF-β responsiveness is critical for enforcing sensitivity to homeostatic cytokines that limit maintenance and composition of the CD8 T cell pool. (154 words).

View Article: PubMed Central - PubMed

Affiliation: Lab Medicine and Pathology, Center for Immunology, University of Minnesota, Minneapolis, Minnesota, United States of America.

ABSTRACT
The pleiotropic cytokine TGF-β has been implicated in the regulation of numerous aspects of the immune response, including naïve T cell homeostasis. Previous studies found that impairing TGF-β responsiveness (through expression of a dominant-negative TGF-β RII [DNRII] transgene) leads to accumulation of memory phenotype CD8 T cells, and it was proposed that this resulted from enhanced IL-15 sensitivity. Here we show naïve DNRII CD8 T cells exhibit enhanced lymphopenia-driven proliferation and generation of "homeostatic" memory cells. However, this enhanced response occurred in the absence of IL-15 and, unexpectedly, even in the combined absence of IL-7 and IL-15, which were thought essential for CD8 T cell homeostatic expansion. DNRII transgenic CD8 T cells still require access to self Class I MHC for homeostatic proliferation, arguing against generalized dysregulation of homeostatic cues. These findings suggest TGF-β responsiveness is critical for enforcing sensitivity to homeostatic cytokines that limit maintenance and composition of the CD8 T cell pool. (154 words).

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Attenuated TGF-β sensitivity alters homeostasis of OT-I CD8 T cells.(A) Analysis of intact OT-I and OT-I/DNRII mice. Spleen and lymph node cells from OT-I/DNRII mice exhibit an elevated frequency of CD44hiCD122hi CD8+ T cells compared to normal OT-I controls (upper panels, gated on CD8+Kb-OVA+). The percentage of CD44hiCD122hi is indicated in each dot plot. CD122 express within the CD44lo population is equivalent in OT-I and OT-I/DNRII (lower panels, gated on CD8+ Kb-OVA+CD44lo. (B) CFSE labeled CD44lo OT-I or OT-I/DNRII TCD8 cells were adoptively transferred into sublethally irradiated B6 recipients. Host animals were sacrificed at the indicated timepoints and donor cells analyzed. Expression of CFSE, CD44 and CD122 levels on donor OT-I or OT-I/DNRII cells recovered from the spleen at 7, 14, and 20 days after transfer. (C) Mean number of splenic OT-I and OT-I/DNRII cells recovered from the spleen of host animals (n = 3 per group). (D) The mean number of donor cells recovered from single or cotransfer of OT-I and OT-I/DNRII CD8 T cells in the lymph nodes 18 days after transfer into sublethally irradiated B6 (n = 3 per group). All data are representative of at least 3 independent experiments.
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pone-0042268-g001: Attenuated TGF-β sensitivity alters homeostasis of OT-I CD8 T cells.(A) Analysis of intact OT-I and OT-I/DNRII mice. Spleen and lymph node cells from OT-I/DNRII mice exhibit an elevated frequency of CD44hiCD122hi CD8+ T cells compared to normal OT-I controls (upper panels, gated on CD8+Kb-OVA+). The percentage of CD44hiCD122hi is indicated in each dot plot. CD122 express within the CD44lo population is equivalent in OT-I and OT-I/DNRII (lower panels, gated on CD8+ Kb-OVA+CD44lo. (B) CFSE labeled CD44lo OT-I or OT-I/DNRII TCD8 cells were adoptively transferred into sublethally irradiated B6 recipients. Host animals were sacrificed at the indicated timepoints and donor cells analyzed. Expression of CFSE, CD44 and CD122 levels on donor OT-I or OT-I/DNRII cells recovered from the spleen at 7, 14, and 20 days after transfer. (C) Mean number of splenic OT-I and OT-I/DNRII cells recovered from the spleen of host animals (n = 3 per group). (D) The mean number of donor cells recovered from single or cotransfer of OT-I and OT-I/DNRII CD8 T cells in the lymph nodes 18 days after transfer into sublethally irradiated B6 (n = 3 per group). All data are representative of at least 3 independent experiments.

Mentions: A transgene encoding a dominant negative form of the TGF-β RII receptor (“DNRII”) was crossed to the OT-I TCR transgenic background. Polyclonal DNRII mice are characterized by a massive expansion of memory phenotype (CD44hi) CD8 T cells [13], but Lucas et al. reported that introduction of the H-Y or 2C TCR transgenes corrected the over-representation of memory-like cells [14], leading to the interpretation that the DNRII memory-like pool arose from immune responses to environmental antigens. In contrast to those findings, we found a high frequency of memory phenotype (CD44high/CD122high) CD8 T cells in intact OT-I/DNRII mice (Fig. 1a and S1a), although the total numbers of OT-I CD8+ T cells were similar between OT-I and OT-I/DNRII animals (Fig. S1b). The elevated percentage of memory phenotype CD8 T cells in OT-I/DNRII was apparent as early as 3 weeks of age (Fig. S1c), suggesting that DNRII expression leads to dysregulated normal CD8 T cell homeostasis soon after the peripheral T cell pool is established. Adult OT-I/DNRII Rag−/− animals also showed greater frequencies of memory phenotype CD8 T cells, indicating that these results are not a consequence of endogenous TCR rearrangements (Fig. S1d). In order to accurately compare the response of naïve OT-I and OT-I/DNRII cells, all subsequent experiments were conducted using MACS purified CD8+CD44loCD122lo T cells (Fig. S1a) in adoptive transfer studies.


TGF-β sensitivity restrains CD8+ T cell homeostatic proliferation by enforcing sensitivity to IL-7 and IL-15.

Johnson LD, Jameson SC - PLoS ONE (2012)

Attenuated TGF-β sensitivity alters homeostasis of OT-I CD8 T cells.(A) Analysis of intact OT-I and OT-I/DNRII mice. Spleen and lymph node cells from OT-I/DNRII mice exhibit an elevated frequency of CD44hiCD122hi CD8+ T cells compared to normal OT-I controls (upper panels, gated on CD8+Kb-OVA+). The percentage of CD44hiCD122hi is indicated in each dot plot. CD122 express within the CD44lo population is equivalent in OT-I and OT-I/DNRII (lower panels, gated on CD8+ Kb-OVA+CD44lo. (B) CFSE labeled CD44lo OT-I or OT-I/DNRII TCD8 cells were adoptively transferred into sublethally irradiated B6 recipients. Host animals were sacrificed at the indicated timepoints and donor cells analyzed. Expression of CFSE, CD44 and CD122 levels on donor OT-I or OT-I/DNRII cells recovered from the spleen at 7, 14, and 20 days after transfer. (C) Mean number of splenic OT-I and OT-I/DNRII cells recovered from the spleen of host animals (n = 3 per group). (D) The mean number of donor cells recovered from single or cotransfer of OT-I and OT-I/DNRII CD8 T cells in the lymph nodes 18 days after transfer into sublethally irradiated B6 (n = 3 per group). All data are representative of at least 3 independent experiments.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC3412850&req=5

pone-0042268-g001: Attenuated TGF-β sensitivity alters homeostasis of OT-I CD8 T cells.(A) Analysis of intact OT-I and OT-I/DNRII mice. Spleen and lymph node cells from OT-I/DNRII mice exhibit an elevated frequency of CD44hiCD122hi CD8+ T cells compared to normal OT-I controls (upper panels, gated on CD8+Kb-OVA+). The percentage of CD44hiCD122hi is indicated in each dot plot. CD122 express within the CD44lo population is equivalent in OT-I and OT-I/DNRII (lower panels, gated on CD8+ Kb-OVA+CD44lo. (B) CFSE labeled CD44lo OT-I or OT-I/DNRII TCD8 cells were adoptively transferred into sublethally irradiated B6 recipients. Host animals were sacrificed at the indicated timepoints and donor cells analyzed. Expression of CFSE, CD44 and CD122 levels on donor OT-I or OT-I/DNRII cells recovered from the spleen at 7, 14, and 20 days after transfer. (C) Mean number of splenic OT-I and OT-I/DNRII cells recovered from the spleen of host animals (n = 3 per group). (D) The mean number of donor cells recovered from single or cotransfer of OT-I and OT-I/DNRII CD8 T cells in the lymph nodes 18 days after transfer into sublethally irradiated B6 (n = 3 per group). All data are representative of at least 3 independent experiments.
Mentions: A transgene encoding a dominant negative form of the TGF-β RII receptor (“DNRII”) was crossed to the OT-I TCR transgenic background. Polyclonal DNRII mice are characterized by a massive expansion of memory phenotype (CD44hi) CD8 T cells [13], but Lucas et al. reported that introduction of the H-Y or 2C TCR transgenes corrected the over-representation of memory-like cells [14], leading to the interpretation that the DNRII memory-like pool arose from immune responses to environmental antigens. In contrast to those findings, we found a high frequency of memory phenotype (CD44high/CD122high) CD8 T cells in intact OT-I/DNRII mice (Fig. 1a and S1a), although the total numbers of OT-I CD8+ T cells were similar between OT-I and OT-I/DNRII animals (Fig. S1b). The elevated percentage of memory phenotype CD8 T cells in OT-I/DNRII was apparent as early as 3 weeks of age (Fig. S1c), suggesting that DNRII expression leads to dysregulated normal CD8 T cell homeostasis soon after the peripheral T cell pool is established. Adult OT-I/DNRII Rag−/− animals also showed greater frequencies of memory phenotype CD8 T cells, indicating that these results are not a consequence of endogenous TCR rearrangements (Fig. S1d). In order to accurately compare the response of naïve OT-I and OT-I/DNRII cells, all subsequent experiments were conducted using MACS purified CD8+CD44loCD122lo T cells (Fig. S1a) in adoptive transfer studies.

Bottom Line: Previous studies found that impairing TGF-β responsiveness (through expression of a dominant-negative TGF-β RII [DNRII] transgene) leads to accumulation of memory phenotype CD8 T cells, and it was proposed that this resulted from enhanced IL-15 sensitivity.DNRII transgenic CD8 T cells still require access to self Class I MHC for homeostatic proliferation, arguing against generalized dysregulation of homeostatic cues.These findings suggest TGF-β responsiveness is critical for enforcing sensitivity to homeostatic cytokines that limit maintenance and composition of the CD8 T cell pool. (154 words).

View Article: PubMed Central - PubMed

Affiliation: Lab Medicine and Pathology, Center for Immunology, University of Minnesota, Minneapolis, Minnesota, United States of America.

ABSTRACT
The pleiotropic cytokine TGF-β has been implicated in the regulation of numerous aspects of the immune response, including naïve T cell homeostasis. Previous studies found that impairing TGF-β responsiveness (through expression of a dominant-negative TGF-β RII [DNRII] transgene) leads to accumulation of memory phenotype CD8 T cells, and it was proposed that this resulted from enhanced IL-15 sensitivity. Here we show naïve DNRII CD8 T cells exhibit enhanced lymphopenia-driven proliferation and generation of "homeostatic" memory cells. However, this enhanced response occurred in the absence of IL-15 and, unexpectedly, even in the combined absence of IL-7 and IL-15, which were thought essential for CD8 T cell homeostatic expansion. DNRII transgenic CD8 T cells still require access to self Class I MHC for homeostatic proliferation, arguing against generalized dysregulation of homeostatic cues. These findings suggest TGF-β responsiveness is critical for enforcing sensitivity to homeostatic cytokines that limit maintenance and composition of the CD8 T cell pool. (154 words).

Show MeSH
Related in: MedlinePlus