Rodríguez Camila Sofía, Charó Nancy, Tatti Silvio, Gómez Ricardo Martín, D'Atri Lina Paola, Schattner Mirta
Laboratory of Experimental Thrombosis and Immunobiology of Inflammation, IMEX-CONICET-National Academy of Medicine, Buenos Aires, Argentina.
Clinical Hospital, Buenos Aires, Argentina.
Res Pract Thromb Haemost. 2023 May 22;7(4):100184. doi: 10.1016/j.rpth.2023.100184. eCollection 2023 May.
CD34 cells, megakaryocytes (MKs), and platelets express toll-like receptors (TLRs) that enable these cells to amplify the host innate immune response. However, the role of TLR7/TLR8 activation in megakaryopoiesis has not yet been investigated.
We evaluated the effect of coxsackievirus B3 (CVB3) and synthetic TLR7/TLR8 agonists on the development of human MKs and production of platelets.
CD34 cells from human umbilical cord were inoculated with CVB3 or stimulated with synthetic TLR7/TLR8 agonists and then cultured in the presence of thrombopoietin.
CD34 cells, MK progenitor cells, and mature MKs expressed TLR7 and TLR8, and exposure to CVB3 resulted in productive infection, as determined by the presence of viral infectious particles in culture supernatants. Cell expansion, differentiation into MKs, MK maturation, and platelet biogenesis were significantly reduced in CD34-infected cultures. The reduction in MK growth was not due to an alteration in cellular proliferation but was accompanied by an increase in cellular apoptosis and pyroptosis. Impairment of MK generation and maturation of viable cells were also associated with decreased expression of transcription factors involved in these processes. These effects were completely abrogated by TLR7 but not TLR8 antagonists and mimicked by TLR7 but not TLR8 agonists. CVB3 infection of CD34 cells increased the immunophenotype of MKs characterized as CD148/CD48 or CD41/CD53 cells.
These data suggest a novel role of TLR7 in megakaryo/thrombopoiesis that may contribute to a better understanding of the molecular basis underlying thrombocytopenia and the immunologic role of MKs in viral infection processes.
CD34细胞、巨核细胞（MKs）和血小板表达Toll样受体（TLRs），这些受体使这些细胞能够放大宿主的固有免疫反应。然而，TLR7/TLR8激活在巨核细胞生成中的作用尚未得到研究。
我们评估了柯萨奇病毒B3（CVB3）和合成的TLR7/TLR8激动剂对人巨核细胞发育和血小板生成的影响。
用人脐血中的CD34细胞接种CVB3或用合成的TLR7/TLR8激动剂刺激，然后在血小板生成素存在的情况下进行培养。
CD34细胞、巨核祖细胞和成熟巨核细胞表达TLR7和TLR8，并且通过培养上清液中病毒感染性颗粒的存在确定，暴露于CVB3会导致 productive感染。在受感染的CD34培养物中，细胞扩增、向巨核细胞的分化、巨核细胞成熟和血小板生物合成均显著减少。巨核细胞生长的减少不是由于细胞增殖的改变，而是伴随着细胞凋亡和焦亡的增加。存活细胞的巨核细胞生成和成熟受损也与参与这些过程的转录因子表达降低有关。这些作用被TLR7拮抗剂完全消除，但未被TLR8拮抗剂消除，并且被TLR7激动剂模拟，但未被TLR8激动剂模拟。CD34细胞的CVB3感染增加了以CD148/CD48或CD41/CD53细胞为特征的巨核细胞的免疫表型。
这些数据表明TLR7在巨核细胞生成/血小板生成中具有新作用，这可能有助于更好地理解血小板减少症的分子基础以及巨核细胞在病毒感染过程中的免疫作用。
