Sato Yohei, Osada Erika, Manome Yoshinobu
Project Research Unit, Laboratory of Immune Cell Therapy, The Jikei University School of Medicine, Tokyo 105-8461, Japan.
Core Research Facilities, Research Center for Medical Sciences, The Jikei University School of Medicine, Tokyo 105-8461, Japan.
Int J Mol Sci. 2025 Jun 30;26(13):6302. doi: 10.3390/ijms26136302.
FOXP3+ regulatory T cells (Tregs) play a central role in the regulation of the immune system. Human Tregs preferentially express a FOXP3 isoform known as delta 2, which lacks exon 2. In addition to FOXP3, Tregs also express isoforms of other Treg-related molecules, such as CTLA-4 and IKZF-2. It is hypothesized that Tregs possess a unique isoform repertoire based on their unique gene and isoform expression profiles, which include FOXP3. Here, we identified a Treg-specific unique isoform repertoire confirmed by long-read high-throughput isoform sequencing called Iso-seq, which is uniquely capable of providing data on genome-wide isoform usage. Notably, while conventional T cells (Tconvs) do not exhibit this pattern, Tregs preferentially express the full-length FOXP3 isoform. Interestingly, the preferential expression of ICOS and PD-L1 upon T-cell receptor (TCR) stimulation was noted in activated Tregs but not in Tconvs or non-activated Tregs. Moreover, using a PD-L1 antibody blockade on Tregs did not diminish FOXP3 expression; however, it significantly reduced the suppressive function. Therefore, Tregs may have a unique isoform repertoire, which becomes pronounced upon polyclonal TCR stimulation.
FOXP3+调节性T细胞（Tregs）在免疫系统调节中发挥核心作用。人类Tregs优先表达一种名为δ2的FOXP3异构体，该异构体缺少外显子2。除FOXP3外，Tregs还表达其他Treg相关分子的异构体，如CTLA-4和IKZF-2。据推测，Tregs基于其独特的基因和异构体表达谱（包括FOXP3）拥有独特的异构体库。在此，我们通过长读长高通量异构体测序（称为Iso-seq）鉴定了一种Treg特异性独特异构体库，Iso-seq能够独特地提供全基因组异构体使用的数据。值得注意的是，虽然传统T细胞（Tconvs）没有表现出这种模式，但Tregs优先表达全长FOXP3异构体。有趣的是，在活化的Tregs中，而不是在Tconvs或未活化的Tregs中，观察到T细胞受体（TCR）刺激后ICOS和PD-L1的优先表达。此外，对Tregs使用PD-L1抗体阻断并没有降低FOXP3的表达；然而，它显著降低了抑制功能。因此，Tregs可能有一个独特的异构体库，在多克隆TCR刺激时变得明显。
