Inhibition of Epidermal Growth Factor Receptor (EGFR) Reduces Lipopolysaccharide (LPS)-Induced Activation and Inflammatory Cytokines in Hepatic Stellate Cells In Vitro.

Abstract

BackgroundEpidermal growth factor receptor (EGFR) expression is associated with hepatic fibrogenesis. Activated hepatic stellate cells (HSCs) release inflammatory cytokines and extracellular matrix (ECM). The aim of this in vitro study was to investigate HSCs, activated by lipopolysaccharide (LPS), and the role of EGFR using the small molecule EGFR inhibitor, AG1478, and using knockdown of the EGFR gene using small interfering RNA (siRNA) cell transfection.Material/MethodsHSCs, isolated from male Sprague-Dawley rats, were cultured and treated with and without LPS (100 ng/mL), with and without AG1478 (2.5 μM and 5.0 μM) Cell survival and proliferation were studied using an MTT assay. Western blot was used to measure levels of tumor necrosis factor (TNF)-α, interleukin (IL)-6, IκBα, cytoplasm and nuclear NFκB and EGFR in the cell lysates before and after small interfering RNA (siRNA) transfection. Quantitative reverse transcription polymerase chain reaction (RT-qPCR) was used to measure the mRNA levels of transforming growth factor (TGF)-β, Col-1, and α-smooth muscle actin (SMA). The Toll-like receptor 4 (TLR4) antagonist TAK-242 and the selective c-Src inhibitor, PP2 in LPS induced-EGFR phosphorylation was evaluated using Western blot.ResultsInhibition of EGFR decreased LPS-induced HSC proliferation and inflammatory cytokines. The TLR4 antagonist TAK-242, and the c-Src inhibitor, PP2 reduced EGFR activation of HSCs, indicating a possible role for the TLR4/c-Src signaling cascade in LPS-induced HSC activation.ConclusionsActivation of HSCs by LPS in vitro, including the expression of inflammatory cytokines and mediators of fibrogenesis, were shown to be dependent on the expression of EGFR.