LPS-induced epithelial-mesenchymal transition of intrahepatic biliary epithelial cells.
BACKGROUND
Recent studies have revealed that the epithelial-mesenchymal transition (EMT) of bile duct epithelial cells is engaged in hepatic fibrogenesis. However, the association between etiological factors of liver disease such as virus or bacterial infection and EMT remains to be investigated. The present study focuses on the inductive role of endotoxin, the main component of the cell wall's ectoblast of gram-negative bacteria, in the EMT of human intrahepatic biliary epithelial cells (HIBEpiCs).


METHODS
The expressions of E-cadherin, S100A4, α-SMA, TGF-β1, and Smad2/3 in HIBEpiCs cultured with or without lipopolysaccharide LPS, were detected by real-time PCR and Western blotting. We blocked the expression of TGF-β1 using paclitaxel and knocked down Smad2/3 by siRNA to explore the role of TGF-β1/Smad2/3 pathway in the EMT of HIBEpiCs.


RESULTS
Resting HIBEpiCs showed epithelioid cobblestone morphology, and underwent a phenotypic change to produce bipolar cells with a fibroblastic morphology when co-cultured with LPS. After LPS stimulation and the up-regulation of mRNA and protein expression of TGF-β1 and Smad2/Smad3, the mRNA and protein expression of mesenchymal markers (S100A and α-SMA) increased significantly. Paclitaxel inhibited the mRNA and protein expression of TGF-β1 in vitro. Knock-down of Smad2/3 by siRNA led to up-regulation of epithelial markers E-cadherin and down-regulation of S100A and α-SMA, indicating a reversal of the EMT.


CONCLUSIONS
LPS can induce the expression of TGF-ß1 and a subsequent EMT in HIBEpiCs, and the inhibition of TGF-ß1 or Smad 2/3 could reverse this EMT, suggesting that LPS may play a potential role in the EMT of HIBEpiCs.
Zhao
Lijin
L
Hepatobiliary Surgery Institute, Southwest Hospital, Third Military Medical University, Chongqing, China.
Yang
Rigao
R
Cheng
Long
L
Wang
Maijian
M
Jiang
Yan
Y
Wang
Shuguang
S
D000199:Actins / Q000235:genetics / Q000378:metabolism; D000972:Antineoplastic Agents, Phytogenic / Q000494:pharmacology; D001659:Biliary Tract / Q000166:cytology*; D015820:Cadherins / Q000235:genetics / Q000378:metabolism; D002460:Cell Line; D004847:Epithelial Cells / Q000166:cytology* / Q000187:drug effects* / Q000378:metabolism; D058750:Epithelial-Mesenchymal Transition / Q000187:drug effects* / Q000502:physiology; D006801:Humans; D008070:Lipopolysaccharides / Q000494:pharmacology*; D017239:Paclitaxel / Q000494:pharmacology; D012333:RNA, Messenger / Q000378:metabolism; D034741:RNA, Small Interfering / Q000494:pharmacology; D009418:S100 Proteins / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D051899:Smad2 Protein / Q000235:genetics / Q000378:metabolism; D051900:Smad3 Protein / Q000235:genetics / Q000378:metabolism; D053773:Transforming Growth Factor beta1 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism
C541116:ACTA2 protein, human; D000199:Actins; D000972:Antineoplastic Agents, Phytogenic; D015820:Cadherins; D008070:Lipopolysaccharides; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D009418:S100 Proteins; C110294:S100A1 protein; C497782:SMAD2 protein, human; C497790:SMAD3 protein, human; D051899:Smad2 Protein; D051900:Smad3 Protein; D053773:Transforming Growth Factor beta1; D017239:Paclitaxel