Induced expression of PD-L1 in spermatogonial stem cells by self-renewal division allows allogeneic offspring production [Sequencing]

Testis immune privilege is thought to be mediated by somatic cells. However, it is not strong enough to protect allogeneic spermatogonial stem cells (SSCs) transplanted into the seminiferous tubules. Here we report successful production of allogeneic offspring by inducing PD-L1 in SSCs. Activation of self-renewal division induced PD-L1 and B7-H3 expression in cultured SSCs, which produced sperm after allogeneic transplantation. While B7-H3 depletion did not influence colonization, PD-L1 depletion prevented donor-derived spermatogenesis. PD-L1 expression was induced by BCL6B via reactive oxygen species (ROS) generation, suggesting that self-renewal stimulation confers immune privilege by ROS. In contrast, reduced ROS or Mapk14 deficiency downregulated PD-L1 expression. Allogeneic offspring were produced by SSC transplantation into congenitally infertile mice and busulfan-treated wild-type mice. Therefore, SSCs can escape rejection when their self-renewal division is stimulated. Analysis of expression profiles during establishment (0weeks, 1weeks, 2weeks, 3weeks, established cultured SSCs) of cultured spermatogonial stem cells, in duplicate, using illumina NextSeq 500.

睾丸免疫豁免（Testis immune privilege）被认为由体细胞介导。然而其免疫保护能力不足以保护移植至曲细精管内的同种异体精原干细胞（spermatogonial stem cells, SSCs）。本研究首次报道，通过在SSCs中诱导程序性死亡受体配体1（PD-L1）的表达，成功获得了同种异体子代。培养的SSCs在自我更新分裂被激活后，会表达PD-L1与B7同源物3（B7-H3），这类细胞在同种异体移植后可产生精子。敲除B7-H3并不会影响SSCs的定植能力，而敲除PD-L1则会阻断供体来源的精子发生过程。PD-L1的表达由BCL6B通过活性氧（reactive oxygen species, ROS）的产生所诱导，提示自我更新刺激可通过ROS介导的途径赋予SSCs免疫豁免特性。与之相反，降低细胞内ROS水平或丝裂原活化蛋白激酶14（Mapk14）缺陷均会下调PD-L1的表达。将SSCs移植至先天性不育小鼠以及经白消安（busulfan）处理的野生型小鼠体内后，成功获得了同种异体子代。由此可见，当SSCs的自我更新分裂受到刺激时，其可逃逸免疫排斥反应。本研究采用Illumina NextSeq 500测序平台，对培养的精原干细胞建系过程中的不同时间点（0周、1周、2周、3周、已建系的培养SSCs）设置双重复，开展了转录组表达谱分析。