Department of Biomolecular Health Sciences, Faculty of Veterinary Science, Utrecht University, Utrecht, The Netherlands.
Department of Pediatrics and Center for Translational Immunology, University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands.
J Extracell Vesicles. 2024 Jul;13(7):e12457. doi: 10.1002/jev2.12457.
Seminal plasma induces immune tolerance towards paternal allogenic antigens within the female reproductive tract and during foetal development. Recent evidence suggests a role for extracellular vesicles in seminal plasma (spEVs). We isolated spEVs from seminal plasma that was donated by vasectomized men, thereby excluding any contributions from the testis or epididymis. Previous analysis demonstrated that such isolated spEVs originate mainly from the prostate. Here we observed that when isolated fluorescently labelled spEVs were mixed with peripheral blood mononuclear cells, they were endocytosed predominantly by monocytes, and to a lesser extent also by T-cells. In a mixed lymphocyte reaction, T-cell proliferation was inhibited by spEVs. A direct effect of spEVs on T-cells was demonstrated when isolated T cells were activated by anti-CD3/CD28 coated beads. Again, spEVs interfered with T cell proliferation, as well as with the expression of CD25 and the release of IFN-γ, TNF, and IL-2. Moreover, spEVs stimulated the expression of Foxp3 and IL-10 by CD4+CD25+CD127- T cells, indicating differentiation into regulatory T-cells (Tregs). Prior treatment of spEVs with proteinase K revoked their effects on T-cells, indicating a requirement for surface-exposed spEV proteins. The adenosine A2A receptor-specific antagonist CPI-444 also reduced effects of spEVs on T-cells, consistent with the notion that the development of Tregs and their immune suppressive functions are under the influence of adenosine-A2A receptor signalling. We found that adenosine is highly enriched in spEVs and propose that spEVs are targeted to and endocytosed by T-cells, after which they may release their adenosine content into the lumen of endosomes, thus allowing endosome-localized A2A receptor signalling in spEVs targeted T-cells. Collectively, these data support the idea that spEVs can prime T cells directly for differentiation into Tregs.
精浆在女性生殖道和胎儿发育过程中诱导对父系同种异体抗原的免疫耐受。最近的证据表明，细胞外囊泡在精浆（spEVs）中起作用。我们从输精管结扎男性捐献的精浆中分离 spEVs，从而排除了睾丸或附睾的任何贡献。以前的分析表明，这种分离的 spEVs 主要来源于前列腺。在这里，我们观察到，当分离的荧光标记 spEVs 与外周血单核细胞混合时，它们主要被单核细胞内吞，其次是 T 细胞。在混合淋巴细胞反应中，spEVs 抑制 T 细胞增殖。当分离的 T 细胞被抗 CD3/CD28 包被珠激活时，证明了 spEVs 对 T 细胞的直接作用。再次，spEVs 干扰 T 细胞增殖以及 CD25 的表达和 IFN-γ、TNF 和 IL-2 的释放。此外，spEVs 刺激 CD4+CD25+CD127-T 细胞表达 Foxp3 和 IL-10，表明分化为调节性 T 细胞（Tregs）。用蛋白酶 K 预先处理 spEVs 会撤销其对 T 细胞的作用，表明需要表面暴露的 spEV 蛋白。腺苷 A2A 受体特异性拮抗剂 CPI-444 也降低了 spEVs 对 T 细胞的作用，这与 Tregs 的发展及其免疫抑制功能受腺苷-A2A 受体信号影响的观点一致。我们发现腺苷在 spEVs 中高度富集，并提出 spEVs 被靶向并内吞到 T 细胞中，之后它们可能将其腺苷含量释放到内体腔中，从而允许 spEVs 靶向 T 细胞中的内体定位 A2A 受体信号。总之，这些数据支持 spEVs 可以直接诱导 T 细胞分化为 Tregs 的观点。
