Bodahl Sara, Cerps Samuel, Uller Lena, Nilsson Bengt-Olof
Department of Experimental Medical Science, Lund University, BMC D12, SE-22184 Lund, Sweden.
Biomedicines. 2022 Feb 19;10(2):492. doi: 10.3390/biomedicines10020492.
The human host defense peptide LL-37 influences double-stranded RNA signaling, but this process is not well understood. Here, we investigate synergistic actions of LL-37 and synthetic double-stranded RNA (poly I:C) on toll-like receptor 3 (TLR3) expression and signaling, and examine underlying mechanisms. In bronchial epithelial BEAS-2B cells, LL-37 potentiated poly I:C-induced TLR3 mRNA and protein expression demonstrated by qPCR and Western blot, respectively. Interestingly, these effects were associated with increased uptake of rhodamine-tagged poly I:C visualized by immunocytochemistry. The LL-37/poly I:C-induced upregulation of TLR3 mRNA expression was prevented by the endosomal acidification inhibitor chloroquine, indicating involvement of downstream TLR3 signaling. The glucocorticoid dexamethasone reduced LL-37/poly I:C-induced TLR3 expression on both mRNA and protein levels, and this effect was associated with increased IκBα protein expression, suggesting that dexamethasone acts via attenuation of NF-κB activity. We conclude that LL-37 potentiates poly I:C-induced upregulation of TLR3 through a mechanism that may involve enhanced import of poly I:C and that LL-37/poly I:C-induced TLR3 expression is associated with downstream TLR3 signaling and sensitive to inhibition of NF-κB activity.
人源宿主防御肽LL-37影响双链RNA信号传导，但这一过程尚未完全明确。在此，我们研究LL-37与合成双链RNA（聚肌胞苷酸）对Toll样受体3（TLR3）表达及信号传导的协同作用，并探究其潜在机制。在支气管上皮BEAS-2B细胞中，LL-37增强了聚肌胞苷酸诱导的TLR3 mRNA和蛋白表达，分别通过定量聚合酶链反应（qPCR）和蛋白质印迹法得以证实。有趣的是，这些效应与免疫细胞化学观察到的罗丹明标记的聚肌胞苷酸摄取增加有关。内体酸化抑制剂氯喹可阻止LL-37/聚肌胞苷酸诱导的TLR3 mRNA表达上调，表明下游TLR3信号传导参与其中。糖皮质激素地塞米松在mRNA和蛋白水平均降低了LL-37/聚肌胞苷酸诱导的TLR3表达，且这一效应与IκBα蛋白表达增加有关，提示地塞米松通过减弱核因子κB（NF-κB）活性发挥作用。我们得出结论，LL-37通过一种可能涉及增强聚肌胞苷酸导入的机制增强聚肌胞苷酸诱导的TLR3上调，且LL-37/聚肌胞苷酸诱导的TLR3表达与下游TLR3信号传导相关，并对NF-κB活性抑制敏感。
