The function of activatable cell-penetrating peptides in human intrahepatic bile duct epithelial cells.

This study aimed to investigate the function of Activatable Cell-Penetrating Peptides (ACPP) in detecting the changes of human intrahepatic bile duct epithelial cell(hIBDEC). ACPP, which target matrix metalloproteinases, were constructed. All were labeled with FITC and Gd-DTPA at the N-terminal. Fluorescence microscopy was used to observe the fluorescence intensity inside hIBDEC after stimulating with different concentrations of LPS and incubating with different concentrations of ACPP to determine the optimal concentration range for LPS stimulation and the optimal concentration for FITC-ACPP effect. Flow cytometry and magnetic resonance imaging were used to detect fluorescence signal intensity and nuclear magnetic resonance signal intensity, respectively, after stimulating with different concentrations of LPS. LPS stimulation time and ACPP incubation time were also evaluated, and variance analysis was conducted to analyze intracellular signal change characteristics for every group. Activatable Cell-Penetrating Peptides (ACPP), which were marked with FITC and Gd-DTPA had target-penetrating activity. The intracellular signal intensity gradually increased with the increase in LPS stimulation time and ACPP incubation time within a certain range; however, it did not increase with the increase of LPS concentration. ACPP can be used for imaging hIBDEC with epithelial-mesenchymal transition.

Toll-like receptor 4 shRNA attenuates lipopolysaccharide-induced epithelial-mesenchymal transition of intrahepatic biliary epithelial cells in rats.

BACKGROUND AND AIM: Intrahepatic biliary epithelial cells (IBECs) of the bile duct in liver tissue of patients with hepatolithiasis promoted the development of diseases through epithelial-mesenchymal transition (EMT). This study investigated whether lipopolysaccharide (LPS), a cell-wall constituent of gram-negative bacteria, could induce EMT of IBECs and toll-like receptor 4 (TLR4) had a regulatory role via activating the nuclear factor-κB (NF-κB)/Snail signaling pathway during this process in vivo. METHODS: TLR4 short hairpin RNA (shRNA) adenovirus or negative control shRNA (NC shRNA) adenovirus (1 × 109 plaque-forming unit (PFU), respectively) was injected into the caudal vein of rats. After 96 h, 1 mg/kg LPS was infused retrogradely into the common bile duct for 48 h per rat. The effects of TLR4 shRNA on LPS-induced EMT were determined by evaluating the histopathological changes in IBECs using hematoxylin and eosin staining and the changes in the levels of EMT markers, TLR4, NF-κB p65, pNF-κB p65, and Snail using real-time polymerase chain reaction and Western blot analysis. RESULTS: Compared with normal saline treatment, a loss of epithelial cell markers (E-cadherin and cytokeratin 7) and a gain of mesenchymal cell markers (N-cadherin and matrix metalloproteinase 2) were revealed. The levels of TLR4, NF-κB phosphorylation, and Snail significantly increased after LPS treatment, whereas pretreatment with TLR4 shRNA inhibited the LPS-induced EMT by downregulating the NF-κB/Snail signaling pathway. CONCLUSIONS: LPS induced the EMT of IBECs by activating TLR4. The RNAi-mediated knockdown of TLR4 suppressed EMT occurrence via downregulating the NF-κB/Snail signaling pathway, implicating TLR4 as a new target for human hepatolithiasis.