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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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Comparison of the survival of pre-RTEs and naïve T cells in tissue culture.(A) Phenotypic comparison of freshly isolated SP4 thymocytes and CD4+ naïve T cells. SP3 thymocytes were used as a control. (B) Comparsion of Bim (Bcl2l11) expression among SP3, SP4 thymocytes, and CD4+ naïve T cells. Total RNAs were extracted from the three purified T cell populations. Reverse transcription and quantitative PCR was performed using Bim-specific primers. Asterisks indicate significant (*, p < 0.05; **, P<0.01) changes compared between the two subsets by unpaired Student t test. (C) Purified SP4 thymocytes, RTEs and CD4+ naïve T cells from lymph nodes of C57BL/6 mice were incubated without or with indicated concentrations of IL-7. Annexin V and PI staining of these T cells were analyzed 24 hours later. The numbers in the plot represent the percentage of Annexin V+PI+ or Annexin V+PI- cells. The results were obtained from one of the three similar experiments. (D) Various concentrations of LY294002 and JAK inhibitor 1 were added to the T cell culture described in C. Annexin V and PI staining of these T cells were analyzed 24 hours later. The differences in the increase of Annexin V positive cells at 50 ng/ml of LY294002 and 100 ng/ml of JAK inhibitor I was significant (P<0.05) when SP4 and naïve T cells were compared by unpaired Student t test.
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pone-0056378-g003: Comparison of the survival of pre-RTEs and naïve T cells in tissue culture.(A) Phenotypic comparison of freshly isolated SP4 thymocytes and CD4+ naïve T cells. SP3 thymocytes were used as a control. (B) Comparsion of Bim (Bcl2l11) expression among SP3, SP4 thymocytes, and CD4+ naïve T cells. Total RNAs were extracted from the three purified T cell populations. Reverse transcription and quantitative PCR was performed using Bim-specific primers. Asterisks indicate significant (*, p < 0.05; **, P<0.01) changes compared between the two subsets by unpaired Student t test. (C) Purified SP4 thymocytes, RTEs and CD4+ naïve T cells from lymph nodes of C57BL/6 mice were incubated without or with indicated concentrations of IL-7. Annexin V and PI staining of these T cells were analyzed 24 hours later. The numbers in the plot represent the percentage of Annexin V+PI+ or Annexin V+PI- cells. The results were obtained from one of the three similar experiments. (D) Various concentrations of LY294002 and JAK inhibitor 1 were added to the T cell culture described in C. Annexin V and PI staining of these T cells were analyzed 24 hours later. The differences in the increase of Annexin V positive cells at 50 ng/ml of LY294002 and 100 ng/ml of JAK inhibitor I was significant (P<0.05) when SP4 and naïve T cells were compared by unpaired Student t test.

Mentions: The better persistence of pre-RTEs and RTEs than naïve T cells indicates that these young T cells either have intrinsic advantage in survival or have better responses to homeostatic signals such as IL-7. Thus, we first examined the expression of antiapoptotic molecule B cell lymphoma 2 (Bcl-2) and proapoptotic molecule Bim by flow cytometry and real time PCR, respectively. Pre-RTEs displayed higher Bcl-2 and lower Bim levels as compared to peripheral naïve T cells, indicating an autonomous survival advantage of pre-RTEs (Fig. 3A and 3B). In agreement with this result, less apoptotic cells were found in pre-RTEs and RTEs cells in the absence of IL-7 in vitro (Fig. 3C).


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)

Comparison of the survival of pre-RTEs and naïve T cells in tissue culture.(A) Phenotypic comparison of freshly isolated SP4 thymocytes and CD4+ naïve T cells. SP3 thymocytes were used as a control. (B) Comparsion of Bim (Bcl2l11) expression among SP3, SP4 thymocytes, and CD4+ naïve T cells. Total RNAs were extracted from the three purified T cell populations. Reverse transcription and quantitative PCR was performed using Bim-specific primers. Asterisks indicate significant (*, p < 0.05; **, P<0.01) changes compared between the two subsets by unpaired Student t test. (C) Purified SP4 thymocytes, RTEs and CD4+ naïve T cells from lymph nodes of C57BL/6 mice were incubated without or with indicated concentrations of IL-7. Annexin V and PI staining of these T cells were analyzed 24 hours later. The numbers in the plot represent the percentage of Annexin V+PI+ or Annexin V+PI- cells. The results were obtained from one of the three similar experiments. (D) Various concentrations of LY294002 and JAK inhibitor 1 were added to the T cell culture described in C. Annexin V and PI staining of these T cells were analyzed 24 hours later. The differences in the increase of Annexin V positive cells at 50 ng/ml of LY294002 and 100 ng/ml of JAK inhibitor I was significant (P<0.05) when SP4 and naïve T cells were compared by unpaired Student t test.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC3569422&req=5

pone-0056378-g003: Comparison of the survival of pre-RTEs and naïve T cells in tissue culture.(A) Phenotypic comparison of freshly isolated SP4 thymocytes and CD4+ naïve T cells. SP3 thymocytes were used as a control. (B) Comparsion of Bim (Bcl2l11) expression among SP3, SP4 thymocytes, and CD4+ naïve T cells. Total RNAs were extracted from the three purified T cell populations. Reverse transcription and quantitative PCR was performed using Bim-specific primers. Asterisks indicate significant (*, p < 0.05; **, P<0.01) changes compared between the two subsets by unpaired Student t test. (C) Purified SP4 thymocytes, RTEs and CD4+ naïve T cells from lymph nodes of C57BL/6 mice were incubated without or with indicated concentrations of IL-7. Annexin V and PI staining of these T cells were analyzed 24 hours later. The numbers in the plot represent the percentage of Annexin V+PI+ or Annexin V+PI- cells. The results were obtained from one of the three similar experiments. (D) Various concentrations of LY294002 and JAK inhibitor 1 were added to the T cell culture described in C. Annexin V and PI staining of these T cells were analyzed 24 hours later. The differences in the increase of Annexin V positive cells at 50 ng/ml of LY294002 and 100 ng/ml of JAK inhibitor I was significant (P<0.05) when SP4 and naïve T cells were compared by unpaired Student t test.
Mentions: The better persistence of pre-RTEs and RTEs than naïve T cells indicates that these young T cells either have intrinsic advantage in survival or have better responses to homeostatic signals such as IL-7. Thus, we first examined the expression of antiapoptotic molecule B cell lymphoma 2 (Bcl-2) and proapoptotic molecule Bim by flow cytometry and real time PCR, respectively. Pre-RTEs displayed higher Bcl-2 and lower Bim levels as compared to peripheral naïve T cells, indicating an autonomous survival advantage of pre-RTEs (Fig. 3A and 3B). In agreement with this result, less apoptotic cells were found in pre-RTEs and RTEs cells in the absence of IL-7 in vitro (Fig. 3C).

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