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Premature CD4+ T cell aging and its contribution to lymphopenia-induced proliferation of memory cells in autoimmune-prone non-obese diabetic mice.

Sheu TT, Chiang BL, Yen JH, Lin WC - PLoS ONE (2014)

Bottom Line: This was accompanied by an increase in the percentage of memory cells, leading to a reduced naïve/memory ratio.This process preferentially contributed to LIP of memory cells.Given that CD28 and IL-2 play important roles in Treg function, the relationships between premature CD4(+) T cell aging and lymphopenia as well as Treg defects in autoimmune-prone NOD mice are proposed.

View Article: PubMed Central - PubMed

Affiliation: Department of Immunology, Tzu Chi University, Hualien, Taiwan, Republic of China ; Institute of Microbiology, Immunology and Biochemistry, Tzu Chi University, Hualien, Taiwan, Republic of China.

ABSTRACT
Lymphopenia-induced proliferation (LIP), a mechanism to maintain a constant number of T cells in circulation, occurs in both normal aging and autoimmune disease. The incidence of most autoimmune diseases increases with age, and premature CD4(+) T cell aging has been reported in several autoimmune diseases. In this study, we tested the hypothesis that premature CD4(+) T cell aging can cause autoimmune disease by examining whether premature CD4(+) T cell aging exists and causes LIP in our mouse model. Non-obese diabetic (NOD) mice were used because, in addition to Treg defects, the LIP of T cells has been shown to plays a causative role in the development of insulin-dependent diabetes mellitus (IDDM) in these mice. We found that with advancing age, NOD mice exhibited an accelerated decrease in the number of CD4(+) T cells due to the loss of naïve cells. This was accompanied by an increase in the percentage of memory cells, leading to a reduced naïve/memory ratio. In addition, both the percentage of CD28(+) cells in CD4(+) T cells and IL-2 production decreased, while the percentage of FAS(+)CD44(+) increased, suggesting that NOD mice exhibit premature CD4(+) T cell aging. This process preferentially contributed to LIP of memory cells. Therefore, our results suggest that premature CD4(+) T cell aging underlies the development of IDDM in NOD mice. Given that CD28 and IL-2 play important roles in Treg function, the relationships between premature CD4(+) T cell aging and lymphopenia as well as Treg defects in autoimmune-prone NOD mice are proposed.

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Correlation between the percentage of Ki-67-positive cells in naïve, memory, or naïve plus memory CD4+ T cells and the percentage of naïve cells in CD4+ T cells.Splenocytes isolated from Balb/c and NOD mice were stained with APC-conjugated anti-CD4, FITC-conjugated anti-CD44, PE-conjugated anti-CD45RB, and Per-CP-conjugated anti-Ki-67, and then 30,000 cells were analyzed with flow cytometry with gating performed on live CD4+ T cells, naïve (CD45RB+CD44−) CD4+ T cells, and memory (CD45RB−CD44+) CD4+ T cells (A). (B, C) The dot plots represent correlation between the percentage of Ki-67-positive cells in naïve, memory, and naïve plus memory CD4+ T cells and the percentage of naïve cells in CD4+ T cells of Balb/c (B) and NOD (C) mice. Data for each experiment were pooled for 2 spleens (Balb/c: n = 66 mice; NOD: n = 46 mice). Pearson correlation coefficients (rp), P values, and the regression equation are shown in each panel. (D) The bar plots show the percentage of Ki-67-positive cells in naïve, memory, and naïve plus memory CD4+ T cells in each age group. Each point represents the mean ± SEM for data obtained from 3 to 7 experiments (age group I: Balb/c: n = 12 mice; NOD: n = 8 mice; age group II: Balb/c: n = 10 mice; NOD: n = 14 mice; age group III: Balb/c: n = 12 mice; NOD: n = 10 mice; age group IV: Balb/c: n = 6 mice; NOD: n = 8 mice). *The values for NOD mice were significantly different from the values for the Balb/c mice at P<0.05. (E) The bar plots show the percentage of Ki-67-positive cells in naïve and memory CD4+ T cells in each age group of NOD mice. Each point represents the mean ± SEM. *The values for memory cells were significantly different from the values for naïve cells at P<0.05.
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pone-0089379-g006: Correlation between the percentage of Ki-67-positive cells in naïve, memory, or naïve plus memory CD4+ T cells and the percentage of naïve cells in CD4+ T cells.Splenocytes isolated from Balb/c and NOD mice were stained with APC-conjugated anti-CD4, FITC-conjugated anti-CD44, PE-conjugated anti-CD45RB, and Per-CP-conjugated anti-Ki-67, and then 30,000 cells were analyzed with flow cytometry with gating performed on live CD4+ T cells, naïve (CD45RB+CD44−) CD4+ T cells, and memory (CD45RB−CD44+) CD4+ T cells (A). (B, C) The dot plots represent correlation between the percentage of Ki-67-positive cells in naïve, memory, and naïve plus memory CD4+ T cells and the percentage of naïve cells in CD4+ T cells of Balb/c (B) and NOD (C) mice. Data for each experiment were pooled for 2 spleens (Balb/c: n = 66 mice; NOD: n = 46 mice). Pearson correlation coefficients (rp), P values, and the regression equation are shown in each panel. (D) The bar plots show the percentage of Ki-67-positive cells in naïve, memory, and naïve plus memory CD4+ T cells in each age group. Each point represents the mean ± SEM for data obtained from 3 to 7 experiments (age group I: Balb/c: n = 12 mice; NOD: n = 8 mice; age group II: Balb/c: n = 10 mice; NOD: n = 14 mice; age group III: Balb/c: n = 12 mice; NOD: n = 10 mice; age group IV: Balb/c: n = 6 mice; NOD: n = 8 mice). *The values for NOD mice were significantly different from the values for the Balb/c mice at P<0.05. (E) The bar plots show the percentage of Ki-67-positive cells in naïve and memory CD4+ T cells in each age group of NOD mice. Each point represents the mean ± SEM. *The values for memory cells were significantly different from the values for naïve cells at P<0.05.

Mentions: LIP of CD4+ and CD8+ T cells in NOD mice generates IDDM [3]. Since LIP can occur in both naïve and memory cells, we investigated whether LIP is correlated with immune aging, as indicated by a reduction in the percentage of naïve CD4+ T cells. Ki-67 was used to detect proliferating cells because it is expressed intracellularly during the G1 and M phases and disappears in the G0 phase of the cell cycle [50]. In populations of naïve plus memory cells in Balb/c mice, the percentage of proliferating cells is inversely correlated with the percentage of naïve cells (P = 0.002; Figure 6B, top panel). This inverse correlation occurs in both the population with the naïve phenotype (P = 0.008; Figure 6B, middle panel) and the population with the memory phenotype (P = 0.044; Figure 6B, bottom panel). In Balb/c mice, naïve cells respond better to the reduction in naïve cells than do memory cells, given that the slope of the regression equation is −0.0207 for naïve cells (Figure 6B, middle panel) and −0.0085 for memory cells (Figure 6B, bottom panel). It has been shown that under acutely lymphopenic conditions (e.g., sublethal irradiation), LIP of most naïve cells occurs at a slow rate and the cells retain their naïve phenotype [51], [52]. This slow expansion of naïve cells is termed homeostatic proliferation (HP) and is mediated by low-affinity self-peptides/MHCs and an increased concentration of IL-7/IL-15 resulting from the reduction in T cell number [53]–[56].


Premature CD4+ T cell aging and its contribution to lymphopenia-induced proliferation of memory cells in autoimmune-prone non-obese diabetic mice.

Sheu TT, Chiang BL, Yen JH, Lin WC - PLoS ONE (2014)

Correlation between the percentage of Ki-67-positive cells in naïve, memory, or naïve plus memory CD4+ T cells and the percentage of naïve cells in CD4+ T cells.Splenocytes isolated from Balb/c and NOD mice were stained with APC-conjugated anti-CD4, FITC-conjugated anti-CD44, PE-conjugated anti-CD45RB, and Per-CP-conjugated anti-Ki-67, and then 30,000 cells were analyzed with flow cytometry with gating performed on live CD4+ T cells, naïve (CD45RB+CD44−) CD4+ T cells, and memory (CD45RB−CD44+) CD4+ T cells (A). (B, C) The dot plots represent correlation between the percentage of Ki-67-positive cells in naïve, memory, and naïve plus memory CD4+ T cells and the percentage of naïve cells in CD4+ T cells of Balb/c (B) and NOD (C) mice. Data for each experiment were pooled for 2 spleens (Balb/c: n = 66 mice; NOD: n = 46 mice). Pearson correlation coefficients (rp), P values, and the regression equation are shown in each panel. (D) The bar plots show the percentage of Ki-67-positive cells in naïve, memory, and naïve plus memory CD4+ T cells in each age group. Each point represents the mean ± SEM for data obtained from 3 to 7 experiments (age group I: Balb/c: n = 12 mice; NOD: n = 8 mice; age group II: Balb/c: n = 10 mice; NOD: n = 14 mice; age group III: Balb/c: n = 12 mice; NOD: n = 10 mice; age group IV: Balb/c: n = 6 mice; NOD: n = 8 mice). *The values for NOD mice were significantly different from the values for the Balb/c mice at P<0.05. (E) The bar plots show the percentage of Ki-67-positive cells in naïve and memory CD4+ T cells in each age group of NOD mice. Each point represents the mean ± SEM. *The values for memory cells were significantly different from the values for naïve cells at P<0.05.
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Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC3935863&req=5

pone-0089379-g006: Correlation between the percentage of Ki-67-positive cells in naïve, memory, or naïve plus memory CD4+ T cells and the percentage of naïve cells in CD4+ T cells.Splenocytes isolated from Balb/c and NOD mice were stained with APC-conjugated anti-CD4, FITC-conjugated anti-CD44, PE-conjugated anti-CD45RB, and Per-CP-conjugated anti-Ki-67, and then 30,000 cells were analyzed with flow cytometry with gating performed on live CD4+ T cells, naïve (CD45RB+CD44−) CD4+ T cells, and memory (CD45RB−CD44+) CD4+ T cells (A). (B, C) The dot plots represent correlation between the percentage of Ki-67-positive cells in naïve, memory, and naïve plus memory CD4+ T cells and the percentage of naïve cells in CD4+ T cells of Balb/c (B) and NOD (C) mice. Data for each experiment were pooled for 2 spleens (Balb/c: n = 66 mice; NOD: n = 46 mice). Pearson correlation coefficients (rp), P values, and the regression equation are shown in each panel. (D) The bar plots show the percentage of Ki-67-positive cells in naïve, memory, and naïve plus memory CD4+ T cells in each age group. Each point represents the mean ± SEM for data obtained from 3 to 7 experiments (age group I: Balb/c: n = 12 mice; NOD: n = 8 mice; age group II: Balb/c: n = 10 mice; NOD: n = 14 mice; age group III: Balb/c: n = 12 mice; NOD: n = 10 mice; age group IV: Balb/c: n = 6 mice; NOD: n = 8 mice). *The values for NOD mice were significantly different from the values for the Balb/c mice at P<0.05. (E) The bar plots show the percentage of Ki-67-positive cells in naïve and memory CD4+ T cells in each age group of NOD mice. Each point represents the mean ± SEM. *The values for memory cells were significantly different from the values for naïve cells at P<0.05.
Mentions: LIP of CD4+ and CD8+ T cells in NOD mice generates IDDM [3]. Since LIP can occur in both naïve and memory cells, we investigated whether LIP is correlated with immune aging, as indicated by a reduction in the percentage of naïve CD4+ T cells. Ki-67 was used to detect proliferating cells because it is expressed intracellularly during the G1 and M phases and disappears in the G0 phase of the cell cycle [50]. In populations of naïve plus memory cells in Balb/c mice, the percentage of proliferating cells is inversely correlated with the percentage of naïve cells (P = 0.002; Figure 6B, top panel). This inverse correlation occurs in both the population with the naïve phenotype (P = 0.008; Figure 6B, middle panel) and the population with the memory phenotype (P = 0.044; Figure 6B, bottom panel). In Balb/c mice, naïve cells respond better to the reduction in naïve cells than do memory cells, given that the slope of the regression equation is −0.0207 for naïve cells (Figure 6B, middle panel) and −0.0085 for memory cells (Figure 6B, bottom panel). It has been shown that under acutely lymphopenic conditions (e.g., sublethal irradiation), LIP of most naïve cells occurs at a slow rate and the cells retain their naïve phenotype [51], [52]. This slow expansion of naïve cells is termed homeostatic proliferation (HP) and is mediated by low-affinity self-peptides/MHCs and an increased concentration of IL-7/IL-15 resulting from the reduction in T cell number [53]–[56].

Bottom Line: This was accompanied by an increase in the percentage of memory cells, leading to a reduced naïve/memory ratio.This process preferentially contributed to LIP of memory cells.Given that CD28 and IL-2 play important roles in Treg function, the relationships between premature CD4(+) T cell aging and lymphopenia as well as Treg defects in autoimmune-prone NOD mice are proposed.

View Article: PubMed Central - PubMed

Affiliation: Department of Immunology, Tzu Chi University, Hualien, Taiwan, Republic of China ; Institute of Microbiology, Immunology and Biochemistry, Tzu Chi University, Hualien, Taiwan, Republic of China.

ABSTRACT
Lymphopenia-induced proliferation (LIP), a mechanism to maintain a constant number of T cells in circulation, occurs in both normal aging and autoimmune disease. The incidence of most autoimmune diseases increases with age, and premature CD4(+) T cell aging has been reported in several autoimmune diseases. In this study, we tested the hypothesis that premature CD4(+) T cell aging can cause autoimmune disease by examining whether premature CD4(+) T cell aging exists and causes LIP in our mouse model. Non-obese diabetic (NOD) mice were used because, in addition to Treg defects, the LIP of T cells has been shown to plays a causative role in the development of insulin-dependent diabetes mellitus (IDDM) in these mice. We found that with advancing age, NOD mice exhibited an accelerated decrease in the number of CD4(+) T cells due to the loss of naïve cells. This was accompanied by an increase in the percentage of memory cells, leading to a reduced naïve/memory ratio. In addition, both the percentage of CD28(+) cells in CD4(+) T cells and IL-2 production decreased, while the percentage of FAS(+)CD44(+) increased, suggesting that NOD mice exhibit premature CD4(+) T cell aging. This process preferentially contributed to LIP of memory cells. Therefore, our results suggest that premature CD4(+) T cell aging underlies the development of IDDM in NOD mice. Given that CD28 and IL-2 play important roles in Treg function, the relationships between premature CD4(+) T cell aging and lymphopenia as well as Treg defects in autoimmune-prone NOD mice are proposed.

Show MeSH
Related in: MedlinePlus