人類CD8+CD127hi及CD127lo的TEM與TEMRA次群 T細胞受體庫分析與特異性基因表現

Abstract

CD127 (IL-7R)介白素七號α鏈受體蛋白之表現與CD8記憶型Ｔ細胞表現型與功能有顯著的關係。在先前研究中顯示口腔癌病人的周邊血與腫瘤環境中，CD127 (IL-7R)介白素七號α鏈受體蛋白在CD8記憶型Ｔ細胞表現高低，亦可代表記憶型細胞功能性差異。在目前研究中並無人類介白素七號α鏈受體蛋白差異性表現CD8記憶型Ｔ細胞次群與T細胞受體庫之間的關聯之研究。此外，維持介白素七號α鏈受體蛋白差異性表現CD8記憶型Ｔ細胞次群所需的基因表現亦未全然知曉。在本研究中，我們分析CD127 (IL-7R)介白素七號α鏈受體蛋白之表現高低之記憶型細胞其T細胞受體庫特性與基因微陣列分析表現之差異。 我們透過T細胞受體庫分析發現CD127 (IL-7R)介白素七號α鏈受體蛋白高表現之T細胞相較於低表現者，具有較高的T細胞受體庫多樣性。而如此現象並不受傳統CD8記憶型Ｔ細胞表現型之CD45RO+ TEM 或 CD45RA+TEMRA之細胞型所限制。介白素七號α鏈受體蛋白高表現之T細胞受體庫多樣性高同時代表著較低的株落增值現象。在基因微陣列分析中，介白素七號α鏈受體蛋白低表現之T細胞相較於高表現者表現更多的活化態功能性基因，包含顆粒酶B、穿孔酶、顆粒酶H與泛抑制性殺傷免疫球蛋白樣受體。此外，介白素七號α鏈受體蛋白低表現之T細胞相較於高表現者其經T細胞受器激活和細胞因子驅動的增殖相比，表現出較低的表現型可塑性。在受體庫分析上，介白素七號α鏈受體蛋白高表現之T細胞和介白素七號α鏈受體蛋白低表現之T細胞之間的T細胞受體庫共享顯著高於TEM 和 TEMRA群體之間，並且介白素七號α鏈受體蛋白低表現之T細胞可以在體外穩態細胞因子刺激下從介白素七號α鏈受體蛋白高表現之T細胞細胞誘導。在腫瘤浸潤CD8 T細胞受體庫中也保留了類似的介白素七號α鏈受體蛋白低表現之T細胞明顯株落增殖。這些功能性基因表現的結果是與小鼠相似的。人類記憶CD8 T 細胞的功能可以僅基於介白素七號α鏈受體蛋白進行唯一有效區分。並且無論在週邊血或局部腫瘤微環境中，介白素七號α鏈受體蛋白高表現亞群和低表現亞群之間的維持平衡是無論在TEM 或 TEMRA CD8 記憶T細胞分群都適用的。

We reported and hypothesized that CD127 (IL-7R) expression as either high or low could identify human CD8+ T memory cell subsets with distinct functionalities regardless of their CD45RO+ TEM or CD45RA+TEMRA phenotypes. Here, we further analyzed CD127hi or CD127lo TEM and TEMRA cells for their Vβ-CDR3 repertoire and gene expression profiles to validate our hypothesis. The CD127hi subsets exhibited higher TCR diversity coupled with lower frequency of clonal expansion compared to CD127lo populations within either TEM or TEMRA. Both TEM and TEMRA CD127lo populations showed higher gene expression associated with activated functionality, including perforin, granzyme B, granzyme H, and pan-inhibitory killer immunoglobulin-like receptors, exhibited lower phenotype plasticity upon TCR activation and cytokine-driven proliferation, when compared to their CD127hi counterparts. TCR repertoire sharing is significantly higher between CD127hi and CD127lo than between TEM and TEMRA populations, and CD127lo cells can be induced from CD127hi cells upon in vitro homeostatic cytokines stimulation, suggesting differentiation from CD127hi into CD127lo CD8+ T cell. Similar repertoire sharing with pronounced clonal expansion is also preserved in the tumor infiltrated CD8+ T cell. These results suggested that the functionality of human memory CD8+ T cell, similar to mouse, can be uniquely distinguished based on CD127 alone, and homeostasis mediated through IL-7R between CD127 high and low subsets is maintained within either TEM or TEMRA CD8+ memory T cell peripheral or local microenvironment.