Role of Telomere and telomerase In Human Lymphocyte Function and Aging

免疫老化的许多特征已经被确定，但其根本原因尚未完全了解。我们分析了三个参数（端粒长度，炎性细胞因子和CMV抗体滴度）的免疫系统老化，通过纵向分析465名受试者，年龄范围从21岁到88岁，在第一次访问，平均13年（7-19年）的后续行动。观察到PBMC的端粒长度的变化率高度可变，端粒缩短的平均速率相对较慢（约16 bp/年）。同样，有显着增加，随着年龄的增长，在体内的三个炎症相关的细胞因子（IFN-，IL-6和IL-10）和抗CMV IgG滴度，这在个体之间的差异很大，以及。虽然有不同的炎症细胞因子之间的正相关变化，我们没有观察到端粒长度，炎症细胞因子，抗CMV IgG滴度的变化率之间的显着相关性，表明端粒磨损，升高的循环炎症细胞因子，抗CMV IgG的年龄相关的轨迹是独立的。免疫老化过程是复杂的，并且个体之间存在差异，使用多种生物标志物对于评估免疫系统的生物老化至关重要。 为了了解端粒酶在T细胞分化和功能中的作用，我们分析了85名健康人（年龄17-82岁）6个T细胞亚群中人端粒酶逆转录酶（hTERT）mRNA表达和端粒酶活性。我们发现，与相应的CD 8 T细胞亚群相比，CD 4 T细胞亚群中的hTERTmRNA和端粒酶活性水平较高，并且从幼稚（TN）到记忆（中央，TCM和效应器，TEM）降低。在所有6个亚组中，用抗CD 3/CD 28抗体体外活化导致hTERTmRNA的量以及端粒酶酶活性增加，而亚组之间的hTERT量和端粒酶活性的差异保持在刺激前观察到的相同顺序。接下来，我们比较了在15天培养过程中体外激活诱导的增殖，发现CD 4 TN中的扩增和存活最稳健，CD 8 TEM中最差，与它们各自的hTERT mRNA和端粒酶活性水平相关。最后，我们直接测试端粒酶在T细胞增殖中的作用，通过用hTERT的反义DNA寡核苷酸敲低hTERTmRNA。我们发现，敲低hTERT在CD 4 TN细胞减少hTERTmRNA，端粒酶活性和细胞增殖的抗CD 3和抗CD 28刺激。这些发现表明，更高的hTERT表达和端粒酶活性促进T细胞增殖潜能，并且分化与T细胞增殖潜能的丧失相关。

A number of hallmarks of immune aging have been identified but underpinning causes are not fully understood. We analyzed three parameters (telomere length, inflammatory cytokines, and antibody titer to CMV) of immune system aging through a longitudinal analysis of 465 subjects ranging in age from 21 to 88 at the first visit, with an average of 13 years (7-19 years) follow-up. A highly variable rate of change in telomere length of PBMCs with a relatively slow average rate of telomere shortening (-16 bp/year) was observed. Similarly, there were significant increases with age in vivo in three inflammatory-related cytokines (IFN-, IL-6 and IL-10) and in anti-CMV IgG titer, which varied widely across individuals as well. Although there were positive correlative changes among different inflammatory cytokines, we did not observe significant correlations among the rate of changes in telomere length, inflammatory cytokines, and anti-CMV IgG titers, indicating age-related trajectories of telomere attrition, elevated circulating inflammatory cytokines, and anti-CMV IgG are independent. Immune aging processes are complex and vary across individuals, and the use of multiple biomarkers is essential to evaluation of biological aging of the immune system. To understand the role of telomerase in T cell differentiation and function, we analyzed human telomerase reverse transcriptase (hTERT) mRNA expression and telomerase activity in six T cell subsets from 85 healthy human donors (aged 17-82 years old). We found that levels of hTERT mRNA and telomerase activity were higher in CD4 T cell subsets as compared to corresponding CD8 T cell subsets and decreased from nave (TN) to memory (central, TCM and effector, TEM). In all six subsets, in vitro activation with anti-CD3/CD28 antibody led to increased amounts of hTERT mRNA as well as telomerase enzymatic activity, while the differences in hTERT amounts and telomerase activity among subsets remained in the same order observed prior to stimulation. Next, we compared activation-induced proliferation in vitro over the course of a 15-day culture and found that expansion and survival were most robust in CD4 TN and poorest in CD8 TEM, correlating with their respective levels of hTERT mRNA and telomerase activity. Finally, we tested directly of the role of telomerase in T cell proliferation by knock-down hTERT mRNA by an anti-sense DNA oligo of hTERT. We found that knock-down hTERT in CD4 TN cells reduced hTERT mRNA, telomerase activity and cell proliferation in response to anti-CD3 and anti-CD28 stimulation. These findings suggest that greater hTERT expression and telomerase activity promote T cell proliferative potential, and that differentiation is associated with a loss of proliferative potential in T cells.