Anti-radiation damage effect of polyethylenimine as a toll-like receptor 5 targeted agonist

Hu, Zhiqiang; Xing, Yaling; Qian, Yuanyu; Chen, Xiaojuan; Tu, Jian; Ren, Lening; Wang, Kai; Chen, Zhongbin

Polyethylenimine (PEI) is a novel TLR5 agonist activating the hTLR5-mediated NF-κB pathway First, the cytotoxicity of PEI was assessed at concentrations ranging from 0.01 to 5 μmol/l by MTT assay. We found that there was no significant toxicity observed on HEK 293T cells as the concentrations of PEI were below 0.5 μmol/l ( Fig. 2A) . Then the above cell-based model was used to assess whether PEI is a novel TLR5 agonist that targets the hTLR5-mediated NF-κB pathway. Twenty-four hours after co-transfection of pcDNA3.1-V5/HisB-hTLR5 and NF-κB-luciferase into HEK 293T cells, these cells were treated with PEI at concentrations ranging from 0.1 to 1.0 μmol/l or flagellin at a concentration of 1 µg/ml for 6 h. We found that TLR5 was significantly activated by PEI in a dose-dependent manner as luciferase activity of the downstream NF-κB reporter was increased just like the TLR5 agonist, flagellin (Fig. 2B) . These results suggested that, similar to flagellin, PEI is a novel agonist of TLR5 that activates the hTLR5-mediated NF-κB pathway.