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Homeostatic properties and phenotypic maturation of murine CD4+ pre-thymic emigrants in the thymus.

Dong J, Chen Y, Xu X, Jin R, Teng F, Yan F, Tang H, Li P, Sun X, Li Y, Wu H, Zhang Y, Ge Q - PLoS ONE (2013)

Bottom Line: Qa2, the expression of which indicates the phenotypic maturation of SPs and RTEs, was found to be upregulated in CD4(+) pre-RTEs in thymic perivascular space.Migratory dendritic cells that surround this region contribute to Qa2 expression in pre-RTEs.The dendritic cell-driven Qa2 induction of CD4(+) pre-RTEs is independent of MHC class II and Aire molecules.

View Article: PubMed Central - PubMed

Affiliation: Key Laboratory of Medical Immunology, Ministry of Health, Department of Immunology, Peking University Health Science Center, Beijing, China.

ABSTRACT
After a tightly regulated developmental program in the thymus, "mature" single positive (SP) thymocytes leave the thymus and enter the periphery. These newly arrived recent thymic emigrants (RTEs) are phenotypically and functionally immature, and will complete a dynamic maturation in the peripheral lymphoid organs before being licensed to be resident naïve T cells. To study the early events occurring in the RTE maturation process, we identified the phenotype of CD4(+) pre-RTEs, a population of CD4(+) SP thymocytes that have acquired the thymus egress capability. Compared to peripheral naïve T cells, CD4(+) pre-RTEs displayed superior survival capability in lymphoreplete mice and faster proliferation under lymphopenic condition. The differences in Bcl2/Bim expression and/or heightened IL-7 signaling pathway may account for the pre-RTEs' better responsiveness to homeostatic signals. Qa2, the expression of which indicates the phenotypic maturation of SPs and RTEs, was found to be upregulated in CD4(+) pre-RTEs in thymic perivascular space. Migratory dendritic cells that surround this region contribute to Qa2 expression in pre-RTEs. The dendritic cell-driven Qa2 induction of CD4(+) pre-RTEs is independent of MHC class II and Aire molecules.

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pre-RTEs in the perivascular space upregulate their Qa2 expression.(A) Phenotype of RTEs in Aire-/- mice. FITC intrathymic injection of Aire-/- mice was used to analyze the phenotype of RTEs (FITC+CD4+CD8- cells) at 2, 4, and 6 weeks of age. The data from the littermate Aire+/+ control mice were shown in Fig. 1A. (B) Phenotype of GFPhiCD4+CD8- T cells in RAG2p-GFP and RAG-GFP-Aire-/- mice. GFPhiCD4+CD8- T cells from thymus, peripheral blood, lymph nodes, spleen were gated and the expressions of Qa2 and CD69 were analyzed. T cells in the PVS were analyzed by gating at GFPhiPE+CD8-TCRβ+ thymocytes 5 minutes after tail vein injection of PE-conjugated CD4 antibody into mice. The numbers in the plot represent the mean and standard deviation of the ratios of Qa2+CD69- cells in FITC+, Qa2+CD69- cells or Qa2-CD69- cells in GFPhiCD4+CD8- T cells. Three to five mice were analyzed. (C) Mean fluorescence intensity of Qa2 in GFPhiCD4+CD8- T cells from various places was compared. T: thymus (GFPhiCD4+CD8-Qa2+CD69- cells); P: PVS; B: blood; L: lymph nodes; S: spleen. The data represent the analysis of three mice.
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pone-0056378-g006: pre-RTEs in the perivascular space upregulate their Qa2 expression.(A) Phenotype of RTEs in Aire-/- mice. FITC intrathymic injection of Aire-/- mice was used to analyze the phenotype of RTEs (FITC+CD4+CD8- cells) at 2, 4, and 6 weeks of age. The data from the littermate Aire+/+ control mice were shown in Fig. 1A. (B) Phenotype of GFPhiCD4+CD8- T cells in RAG2p-GFP and RAG-GFP-Aire-/- mice. GFPhiCD4+CD8- T cells from thymus, peripheral blood, lymph nodes, spleen were gated and the expressions of Qa2 and CD69 were analyzed. T cells in the PVS were analyzed by gating at GFPhiPE+CD8-TCRβ+ thymocytes 5 minutes after tail vein injection of PE-conjugated CD4 antibody into mice. The numbers in the plot represent the mean and standard deviation of the ratios of Qa2+CD69- cells in FITC+, Qa2+CD69- cells or Qa2-CD69- cells in GFPhiCD4+CD8- T cells. Three to five mice were analyzed. (C) Mean fluorescence intensity of Qa2 in GFPhiCD4+CD8- T cells from various places was compared. T: thymus (GFPhiCD4+CD8-Qa2+CD69- cells); P: PVS; B: blood; L: lymph nodes; S: spleen. The data represent the analysis of three mice.

Mentions: The expression level of Qa2 is an indicator for the phenotypic maturation of SP thymocytes as well as RTEs. In Aire-/- mice, very little Qa2+ thymocytes (SP4) could be found in the thymus. The RTEs in these mice were thus expected to have an immature SP3 phenotype. In an attempt to study whether the exportation of SP3 cells in adult mice results in differences in maturation of RTEs, we unexpectedly found that almost 40% of RTEs (FITC+ T cells in the periphery 24 hours after FITC intrathymic injection or GFPhiCD4+ T cells in the periphery of RAG2p-GFP-Aire-/- mice) were Qa2 positive (Fig 6A–B). This result suggests that some SP3 thymocytes may start to express this molecule during their thymus egress or during the time when RTEs enter the SLOs. To distinguish these two possibilities, PE-conjugated anti-CD4 antibody was introduced into RAG2p-GFP-Aire-/- mice via tail vein injection. The PE+TCRβ+ thymocytes were analyzed 5 minutes later. Zachariah et al. have shown that cells in the perivascular space of the thymus (PVS, a main region where pre-RTEs exit the thymus) could be labeled using this method [31]. Similar to the results obtained from the lymph nodes and spleen, about 40% of PE-labeled GFPhi T cells in the thymic PVS of RAG2p-GFP-Aire-/- mice were Qa2 positive (Fig. 6B). In addition, GFPhi T cells in the thymic PVS, peripheral blood, lymph nodes, and spleen express similar levels of Qa2 whereas GFPhi SP4 thymocytes express much lower level of Qa2 (Fig. 6C). This indicates that Qa2 upregulation was initiated around the thymic PVS region and did not significantly change after RTEs leaving the thymus and staying in the SLOs for about a week.


Homeostatic properties and phenotypic maturation of murine CD4+ pre-thymic emigrants in the thymus.

Dong J, Chen Y, Xu X, Jin R, Teng F, Yan F, Tang H, Li P, Sun X, Li Y, Wu H, Zhang Y, Ge Q - PLoS ONE (2013)

pre-RTEs in the perivascular space upregulate their Qa2 expression.(A) Phenotype of RTEs in Aire-/- mice. FITC intrathymic injection of Aire-/- mice was used to analyze the phenotype of RTEs (FITC+CD4+CD8- cells) at 2, 4, and 6 weeks of age. The data from the littermate Aire+/+ control mice were shown in Fig. 1A. (B) Phenotype of GFPhiCD4+CD8- T cells in RAG2p-GFP and RAG-GFP-Aire-/- mice. GFPhiCD4+CD8- T cells from thymus, peripheral blood, lymph nodes, spleen were gated and the expressions of Qa2 and CD69 were analyzed. T cells in the PVS were analyzed by gating at GFPhiPE+CD8-TCRβ+ thymocytes 5 minutes after tail vein injection of PE-conjugated CD4 antibody into mice. The numbers in the plot represent the mean and standard deviation of the ratios of Qa2+CD69- cells in FITC+, Qa2+CD69- cells or Qa2-CD69- cells in GFPhiCD4+CD8- T cells. Three to five mice were analyzed. (C) Mean fluorescence intensity of Qa2 in GFPhiCD4+CD8- T cells from various places was compared. T: thymus (GFPhiCD4+CD8-Qa2+CD69- cells); P: PVS; B: blood; L: lymph nodes; S: spleen. The data represent the analysis of three mice.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3569422&req=5

pone-0056378-g006: pre-RTEs in the perivascular space upregulate their Qa2 expression.(A) Phenotype of RTEs in Aire-/- mice. FITC intrathymic injection of Aire-/- mice was used to analyze the phenotype of RTEs (FITC+CD4+CD8- cells) at 2, 4, and 6 weeks of age. The data from the littermate Aire+/+ control mice were shown in Fig. 1A. (B) Phenotype of GFPhiCD4+CD8- T cells in RAG2p-GFP and RAG-GFP-Aire-/- mice. GFPhiCD4+CD8- T cells from thymus, peripheral blood, lymph nodes, spleen were gated and the expressions of Qa2 and CD69 were analyzed. T cells in the PVS were analyzed by gating at GFPhiPE+CD8-TCRβ+ thymocytes 5 minutes after tail vein injection of PE-conjugated CD4 antibody into mice. The numbers in the plot represent the mean and standard deviation of the ratios of Qa2+CD69- cells in FITC+, Qa2+CD69- cells or Qa2-CD69- cells in GFPhiCD4+CD8- T cells. Three to five mice were analyzed. (C) Mean fluorescence intensity of Qa2 in GFPhiCD4+CD8- T cells from various places was compared. T: thymus (GFPhiCD4+CD8-Qa2+CD69- cells); P: PVS; B: blood; L: lymph nodes; S: spleen. The data represent the analysis of three mice.
Mentions: The expression level of Qa2 is an indicator for the phenotypic maturation of SP thymocytes as well as RTEs. In Aire-/- mice, very little Qa2+ thymocytes (SP4) could be found in the thymus. The RTEs in these mice were thus expected to have an immature SP3 phenotype. In an attempt to study whether the exportation of SP3 cells in adult mice results in differences in maturation of RTEs, we unexpectedly found that almost 40% of RTEs (FITC+ T cells in the periphery 24 hours after FITC intrathymic injection or GFPhiCD4+ T cells in the periphery of RAG2p-GFP-Aire-/- mice) were Qa2 positive (Fig 6A–B). This result suggests that some SP3 thymocytes may start to express this molecule during their thymus egress or during the time when RTEs enter the SLOs. To distinguish these two possibilities, PE-conjugated anti-CD4 antibody was introduced into RAG2p-GFP-Aire-/- mice via tail vein injection. The PE+TCRβ+ thymocytes were analyzed 5 minutes later. Zachariah et al. have shown that cells in the perivascular space of the thymus (PVS, a main region where pre-RTEs exit the thymus) could be labeled using this method [31]. Similar to the results obtained from the lymph nodes and spleen, about 40% of PE-labeled GFPhi T cells in the thymic PVS of RAG2p-GFP-Aire-/- mice were Qa2 positive (Fig. 6B). In addition, GFPhi T cells in the thymic PVS, peripheral blood, lymph nodes, and spleen express similar levels of Qa2 whereas GFPhi SP4 thymocytes express much lower level of Qa2 (Fig. 6C). This indicates that Qa2 upregulation was initiated around the thymic PVS region and did not significantly change after RTEs leaving the thymus and staying in the SLOs for about a week.

Bottom Line: Qa2, the expression of which indicates the phenotypic maturation of SPs and RTEs, was found to be upregulated in CD4(+) pre-RTEs in thymic perivascular space.Migratory dendritic cells that surround this region contribute to Qa2 expression in pre-RTEs.The dendritic cell-driven Qa2 induction of CD4(+) pre-RTEs is independent of MHC class II and Aire molecules.

View Article: PubMed Central - PubMed

Affiliation: Key Laboratory of Medical Immunology, Ministry of Health, Department of Immunology, Peking University Health Science Center, Beijing, China.

ABSTRACT
After a tightly regulated developmental program in the thymus, "mature" single positive (SP) thymocytes leave the thymus and enter the periphery. These newly arrived recent thymic emigrants (RTEs) are phenotypically and functionally immature, and will complete a dynamic maturation in the peripheral lymphoid organs before being licensed to be resident naïve T cells. To study the early events occurring in the RTE maturation process, we identified the phenotype of CD4(+) pre-RTEs, a population of CD4(+) SP thymocytes that have acquired the thymus egress capability. Compared to peripheral naïve T cells, CD4(+) pre-RTEs displayed superior survival capability in lymphoreplete mice and faster proliferation under lymphopenic condition. The differences in Bcl2/Bim expression and/or heightened IL-7 signaling pathway may account for the pre-RTEs' better responsiveness to homeostatic signals. Qa2, the expression of which indicates the phenotypic maturation of SPs and RTEs, was found to be upregulated in CD4(+) pre-RTEs in thymic perivascular space. Migratory dendritic cells that surround this region contribute to Qa2 expression in pre-RTEs. The dendritic cell-driven Qa2 induction of CD4(+) pre-RTEs is independent of MHC class II and Aire molecules.

Show MeSH
Related in: MedlinePlus