OBJECTIVE The importance of human host defense peptide LL-37 in vascular innate immunity is not understood. Here, we assess the impact of LL-37 on double-stranded RNA (dsRNA) signaling in human vascular smooth muscle cells. MATERIALS AND METHODS Cellular import of LL-37 and synthetic dsRNA (poly I:C) were investigated by immunocytochemistry and fluorescence imaging. Transcript and protein expression were determined by qPCR, ELISA and Western blot. Knockdown of TLR3 was performed by siRNA. RESULTS LL-37 was rapidly internalized, suggesting that it has intracellular actions. Co-stimulation with poly I:C and LL-37 enhanced pro-inflammatory IL-6 and MCP-1 transcripts several fold compared to treatment with poly I:C or LL-37 alone. Poly I:C increased IL-6 and MCP-1 protein production, and this effect was potentiated by LL-37. LL-37-induced stimulation of poly I:C signaling was not associated with enhanced import of poly I:C. Treatment with poly I:C and LL-37 in combination increased expression of dsRNA receptor TLR3 compared to stimulation with poly I:C or LL-37 alone. In TLR3 knockdown cells, treatment with poly I:C and LL-37 in combination had no effect on IL-6 and MCP-1 expression, showing loss of function. CONCLUSIONS LL-37 potentiates dsRNA-induced cytokine production through up-regulation of TLR3 expression representing a novel pro-inflammatory mechanism.

中文翻译：

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人类宿主防御肽LL-37通过上调血管平滑肌细胞中TLR3的表达来促进双链RNA促炎信号转导。

目的还不清楚人类宿主防御肽LL-37在血管先天免疫中的重要性。在这里，我们评估LL-37对人血管平滑肌细胞中双链RNA（dsRNA）信号的影响。材料与方法通过免疫细胞化学和荧光成像研究了LL-37和合成dsRNA（poly I：C）的细胞导入。通过qPCR，ELISA和Western印迹测定转录物和蛋白质表达。通过siRNA敲低TLR3。结果LL-37被快速内在化，表明它具有细胞内作用。与单独使用poly I：C或LL-37的治疗相比，与poly I：C和LL-37的共刺激可增强促炎性IL-6和MCP-1转录本数倍。Poly I：C增加了IL-6和MCP-1蛋白的产生，而LL-37增强了这种作用。LL-37诱导的poly I：C信号传导刺激与poly I：C的增强进口无关。与单独用poly I：C或LL-37刺激相比，用poly I：C和LL-37联合治疗可提高dsRNA受体TLR3的表达。在TLR3敲低的细胞中，聚I：C和LL-37联合处理对IL-6和MCP-1表达无影响，显示功能丧失。结论LL-37通过上调代表新的促炎机制的TLR3表达来增强dsRNA诱导的细胞因子的产生。C和LL-37组合对IL-6和MCP-1表达没有影响，显示功能丧失。结论LL-37通过上调代表新的促炎机制的TLR3表达来增强dsRNA诱导的细胞因子的产生。C和LL-37组合对IL-6和MCP-1表达没有影响，显示功能丧失。结论LL-37通过上调代表新的促炎机制的TLR3表达来增强dsRNA诱导的细胞因子的产生。