Activation of toll-like receptors 2 and 4 on CD34+ cells increases human megakaryo/thrombopoiesis induced by thrombopoietin
Activation of toll-like receptors 2 and 4 on CD34+ cells increases human megakaryo/thrombopoiesis induced by thrombopoietin
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DOI：
10.1111/jth.14605
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发表时间：
2019-09-13
影响因子：
10.4
通讯作者：
Schattner, Mirta
中科院分区：
文献类型：
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作者：
Paola D'Atri, Lina;Sofia Rodriguez, Camila;Schattner, Mirta
背景：血小板Toll样受体(TLR)2/4是放大宿主免疫反应的关键分子，但它们在人类巨噬细胞/血栓形成中的作用尚未明确。目的探讨Pam3CSK4或脂多糖(LPS)、TLR2/4配体对人巨核细胞发育和血小板生成的影响。方法用脂多糖或Pam3CSK4刺激CD34(+)细胞，并加或不加促血小板生成素(TPO)。结果CD34(+)细胞和巨核细胞均表达TLR2和TLR4，但脂多糖或Pam3CSK4直接刺激CD34(+)细胞对细胞生长无影响。有趣的是，当两种TLR配体在第0天加入时，都显著增加了TPO诱导的CD34(+)细胞的增殖、巨核细胞的数量和成熟度、血小板原和血小板的产生。相反，当TLR激动剂在加入TPO后7天加入时，没有观察到这种协同作用。CD34(+)或巨核细胞经内毒素或Pam3CSK4刺激后可释放IL-6，而TPO则无此作用，TPO联合TPO可增强这一作用。TPO+LPS或Pam3CSK4诱导的细胞增殖和IL-6分泌增加可被TLR2/4或IL-6中和抗体、PI3K/AKT和核因子-kappaB抑制剂抑制。此外，血小板原和血小板生成量的增加与核因子-E2的核转位增强有关。TPO+内毒素刺激的CD34(+)细胞上清液诱导CFU-M集落形成。结论在TPO存在下，CD34(+)细胞和巨核细胞中TLR2和TLR4的激活可能有助于在感染期间通过PI3K/NF-kappa B轴触发的自分泌IL-6环路提供血小板。
Background Platelet Toll-like receptor (TLR)2/4 are key players in amplifying the host immune response; however, their role in human megakaryo/thrombopoiesis has not yet been defined. Objectives We evaluated whether Pam3CSK4 or lipopolysaccharide (LPS), TLR2/4 ligands respectively, modulate human megakaryocyte development and platelet production. Methods CD34(+) cells from human umbilical cord were stimulated with LPS or Pam3CSK4 with or without thrombopoietin (TPO). Results CD34(+) cells and megakaryocytes express TLR2 and TLR4 at both RNA and protein level; however, direct stimulation of CD34(+) cells with LPS or Pam3CSK4 had no effect on cell growth. Interestingly, both TLR ligands markedly increased TPO-induced CD34(+) cell proliferation, megakaryocyte number and maturity, proplatelet and platelet production when added at day 0. In contrast, this synergism was not observed when TLR agonists were added 7 days after TPO addition. Interleukin-6 (IL-6) release was observed upon CD34(+) or megakaryocyte stimulation with LPS or Pam3CSK4 but not with TPO and this effect was potentiated in combination with TPO. The increased proliferation and IL-6 production induced by TPO + LPS or Pam3CSK4 were suppressed by TLR2/4 or IL-6 neutralizing antibodies, as well as by PI3K/AKT and nuclear factor-kappa B inhibitors. Additionally, increased proplatelet and platelet production were associated with enhanced nuclear translocation of nuclear factor-E2. Finally, the supernatants of CD34(+) cells stimulated with TPO+LPS-induced CFU-M colonies. Conclusions Our data suggest that the activation of TLR2 and TLR4 in CD34(+) cells and megakaryocytes in the presence of TPO may contribute to warrant platelet provision during infection episodes by an autocrine IL-6 loop triggered by PI3K/NF-kappa B axes.