Human CCR6+ Th cells show both an extended stable gradient of Th17 activity and imprinted plasticity [Spsingh-10xTCR-CMV]. Human CCR6+ Th cells show both an extended stable gradient of Th17 activity and imprinted plasticity [Spsingh-10xTCR-CMV]

Th17 cells have been investigated in mice primarily for their contributions to autoimmune diseases. However, the pathways of differentiation of Th17 and related Th cells (type 17 cells) and the structure of the type 17 memory population in humans are not well understood; such understanding is critical for manipulating these cells in vivo. By exploiting differences in levels of surface CCR6, we found that human type 17 memory cells, including individual T cell clonotypes, form an elongated continuum of type 17 character along which cells can be driven by increasing RORt. This continuum includes cells preserved within the memory pool with potentials that reflect the early preferential activation of multiple over single lineages. The CCR6+ cells’ phenotypes and epigenomes are stable across cell divisions under homeostatic-like conditions. Nonetheless, activation in polarizing and non-polarizing conditions can yield additional functionalities, revealing, respectively, both environmentally induced and imprinted mechanisms that contribute differentially across the continuum to yield the unusual plasticity ascribed to type 17 cells. Overall design: Single cell TCR V-d-J sequencing of 4 T-cell subsets with graded levels of CCR6. Independent replicates from two donors. This experiment utilizes an enrichment of an anti-CMV sub-population of T-cells ,which decreases the TCR diversity such that shared clonotypes can be detected and tracked across the CCR6 subsets.

Th17细胞（Th17 cells）最初主要在小鼠模型中被研究，以阐明其在自身免疫性疾病中的致病贡献。然而，目前人类体内Th17细胞及相关Th细胞（即17型细胞，type 17 cells）的分化通路、17型记忆细胞群的结构仍不甚明确；此类认知对于在体操控此类细胞至关重要。
本研究借助表面CCR6（CCR6）表达水平的差异，发现人类17型记忆细胞（包括单个T细胞克隆型）可形成一条反映17型细胞特性的延伸连续谱系，且通过升高RORγt（RORγt）的表达可驱动细胞沿该谱系发生变化。该连续谱系包含留存于记忆库中的细胞，其潜能体现了多谱系相较于单谱系的早期优先激活特性。
在稳态样培养条件下，CCR6阳性（CCR6+）细胞的表型与表观基因组在细胞分裂过程中保持稳定。尽管如此，在极化与非极化培养条件下的活化过程可赋予细胞额外的功能特性，分别揭示了环境诱导型与印记型调控机制——这类机制在该连续谱系中发挥差异化作用，最终赋予17型细胞所特有的可塑性。
实验整体设计：对4个CCR6表达水平呈梯度分布的T细胞亚群进行单细胞TCR V-D-J测序，样本来自2名供体的独立重复实验。本实验通过富集抗巨细胞病毒（CMV）T细胞亚群以降低TCR多样性，从而能够在不同CCR6亚群中检测并追踪共享的T细胞克隆型。