Department of Hematology of Anhui Provincial Hospital, Anhui Medical University, Hefei, Anhui, China.
Exp Cell Res. 2012 Feb 1;318(3):196-206. doi: 10.1016/j.yexcr.2011.11.001. Epub 2011 Nov 10.
Bone marrow derived-mesenchymal stromal cells (BM-MSCs) are multipotent, nonhematopoietic progenitors in a hematopoietic microenvironment and indispensable for regulating hematopoiesis. Several studies have reported that toll-like receptors (TLRs) are expressed in mesenchymal stromal cells (MSCs) to modulate their biological functions. In this study, we investigated the possible role(s) of TLRs in mediating the hematopoiesis-supporting role of human BM-MSCs. Human BM-MSCs were analyzed for mRNA expression of TLR1-10 by reverse transcription-polymerase chain reaction. TLR1-6, but not TLR7-10 were expressed by BM-MSCs. The protein expression of TLR2 and TLR4 was also confirmed by flow cytometry. We further explored the role of TLR2 and TLR4 in mediating the capacity of BM-MSCs to support the proliferation and differentiation of CD34(+) hematopoietic stem/progenitor cells obtained from cord blood. BM-MSCs increased proliferation of CD34(+) cells and promoted the differentiation towards the myeloid lineage 7 or 14days after co-culture, as well as colony formation by those cells and the production of interleukin 1 (IL-1), IL-8, IL-11, stem cell factor (SCF), granulocyte colony-stimulating factor (CSF), macrophage CSF and granulocyte-macrophage CSF, if MSCs had been stimulated with TLR2 agonist (PAM(3)CSK(4)) or TLR4 agonist (LPS). Interestingly, although these effects were elevated in a different degree, a synergistic effect was not observed in BM-MSCs co-stimulated with PAM(3)CSK(4) and LPS. Together, our findings suggest that TLR2 and TLR4 signaling may indirectly regulate hematopoiesis by modulating BM-MSCs' functions. The increased hematopoietic proliferation and differentiation could be mediated, at least in part, by augmented hematopoiesis-related cytokine production of BM-MSCs.
骨髓间充质基质细胞（BM-MSCs）是造血微环境中的多能非造血祖细胞，对于调节造血至关重要。有几项研究报道，Toll 样受体（TLRs）在间充质基质细胞（MSCs）中表达，以调节其生物学功能。在这项研究中，我们研究了 TLRs 是否在介导人 BM-MSCs 支持造血的作用中发挥作用。通过逆转录-聚合酶链反应分析 BM-MSCs 中 TLR1-10 的 mRNA 表达。TLR1-6 而不是 TLR7-10 被 BM-MSCs 表达。TLR2 和 TLR4 的蛋白表达也通过流式细胞术得到证实。我们进一步探讨了 TLR2 和 TLR4 在介导 BM-MSCs 介导 CD34(+)造血干细胞/祖细胞增殖和分化中的作用，这些细胞来自脐血。BM-MSCs 增加 CD34(+)细胞的增殖，并在共培养后 7 或 14 天促进向髓系分化，以及这些细胞的集落形成和白细胞介素 1（IL-1）、IL-8、IL-11、干细胞因子（SCF）、粒细胞集落刺激因子（CSF）、巨噬细胞 CSF 和粒细胞-巨噬细胞 CSF 的产生，如果 MSCs 已被 TLR2 激动剂（PAM(3)CSK(4))或 TLR4 激动剂（LPS）刺激。有趣的是，尽管这些作用在不同程度上提高，但在共刺激 PAM(3)CSK(4)和 LPS 的 BM-MSCs 中没有观察到协同作用。总之，我们的研究结果表明，TLR2 和 TLR4 信号可能通过调节 BM-MSCs 的功能间接调节造血。BM-MSCs 造血相关细胞因子产生的增加可能介导造血的增殖和分化，至少部分如此。
