Abstract

Slit proteins have been reported to act as axonal repellents in Drosophila; however, their role in the placental microenvironment has not been explored. In this study, we found that human placental multipotent mesenchymal stromal cells (hPMSCs) constitutively express Slit2. Therefore, we hypothesized that Slit2 expressed by hPMSCs could be involved in macrophage migration during placental inflammation through membrane cognate Roundabout (Robo) receptor signaling. In order to develop a preclinical in vitro mouse model of hPMSCs in treatment of perinatal infection, RAW 264.7 cells were used in this study. Slit2 interacted with Robo4 that was highly expressed in RAW 264.7 macrophages: their interaction increased the adhesive ability of RAW 264.7 cells and inhibited migration. Lipopolysaccharide (LPS)-induced CD11bCD18 expression could be inhibited by Slit2 and by hPMSC-conditioned medium (CM). LPS-induced activation of p38 and Rap1 was also attenuated by Slit2 and by hPMSC-CM. Noticeably, these inhibitory effects of hPMSC-CM decreased after depletion of Slit2 from the CM. Furthermore, we found that p38 siRNA inhibited LPS-induced Rap1 expression in RAW 264.7 cells, indicating that Rap1 functions downstream of p38 signaling. p38 siRNA increased cell adhesion and inhibited migration through reducing LPS-stimulated CD11bCD18 expression in RAW 264.7 cells. Thus, hPMSC-derived Slit2 may inhibit LPS-induced CD11bCD18 expression to decrease cell migration and increase adhesion through modulating the activity and motility of inflammatory macrophages in placenta. This may represent a novel mechanism for LPS-induced placental infection.

中文翻译：

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胎盘多能间充质基质细胞衍生的 Slit2 可能在胎盘感染期间调节巨噬细胞运动

摘要

据报道，狭缝蛋白在果蝇中可作为轴突驱避剂；然而，尚未探索它们在胎盘微环境中的作用。在这项研究中，我们发现人胎盘多能间充质基质细胞 (hPMSCs) 组成型表达 Slit2。因此，我们假设 hPMSCs 表达的 Slit2 可能通过膜同源环岛 (Robo) 受体信号参与胎盘炎症期间的巨噬细胞迁移。为了开发临床前体外hPMSCs 治疗围产期感染的小鼠模型，本研究使用 RAW 264.7 细胞。Slit2 与在 RAW 264.7 巨噬细胞中高度表达的 Robo4 相互作用：它们的相互作用增加了 RAW 264.7 细胞的粘附能力并抑制了迁移。Slit2 和 hPMSC 条件培养基 (CM) 可以抑制脂多糖 (LPS) 诱导的 CD11bCD18 表达。LPS 诱导的 p38 和 Rap1 激活也被 Slit2 和 hPMSC-CM 减弱。值得注意的是，从 CM 中耗尽 Slit2 后，hPMSC-CM 的这些抑制作用降低。此外，我们发现 p38 siRNA 在 RAW 264.7 细胞中抑制 LPS 诱导的 Rap1 表达，表明 Rap1 在 p38 信号传导的下游起作用。p38 siRNA 通过降低 RAW 264 中 LPS 刺激的 CD11bCD18 表达来增加细胞粘附并抑制迁移。7个细胞。因此，hPMSC 衍生的 Slit2 可能通过调节胎盘中炎性巨噬细胞的活性和运动来抑制 LPS 诱导的 CD11bCD18 表达，从而减少细胞迁移并增加粘附。这可能代表了 LPS 诱导的胎盘感染的新机制。