The Study Of The Apoptosis And Proliferation Of Hepatic Stellate Cell Induced By Endotoxin Via Myeloid Differentiation Factor88Signal Pathway

ObjectiveTo detect the effects of endotoxin on the changes of the mRNA and proteinexpressions of TLR4, MyD88, and relevant cytokines in MyD88-dependent signalingpathway such as TRAF6, TNF-α, NF-кÎ', and observe the apoptosis and proliferationof rat hepatic stellate cell (HSC), in order to explore the role of MyD88in the signaltransduction of the apoptosis of HSC induced by endotoxin, and investigate themechanism of endotoxin promoting hepatic fibrosis.MethodsRat HSCs (HSC-T6strain) were cultured with endotoxin in concentrations of0.1,1.0,10.0EIU/mL (endotoxin groupI，II,III) respectively. The normal HSCs withoutany intervention were treated as normal control group（group IV）. Changes of themRNA and protein expressions of TLR4, MyD88, and relevant cytokines inMyD88-dependent signaling pathway such as TRAF6, TNF-α, NF-кÎ' were detectedby RT-PCR and Western Blot respectively. Apoptosis rates of HSCs were checkedwith flow cytemetry.Results1. Expressions of mRNA and proteins of MyD88, TLR4, NF-κB in endotoxingroup I,IIand III were all stronger than that of the control group,espectively in theendotoxin group II (P <0.01).2. Expressions of mRNA and proteins of TRAF6, TNF-α in the endotoxin groupI and II were stronger than that of the control group, but there was no differencebetween endotoxin group III and the control group.(P>0.05). 3. The average absorbances of HSC in the endotoxin group I and II weresignificantly higher than that of the control group (P<0.05). There was no differencebetween endotoxin group III and the control group. It indicates that endotoxin incertain concentration could promote the proliferation of HSC.4. The rates of apoptosis of HSC in the endotoxin group I and II were lower thanthat of the control group (P<0.05), and it was more obvious in the endotoxin groupII(P <0.01), There was no difference between endotoxin group III and the controlgroup.ConclusionsCertain concentration of endotoxin could enhance expressions of TLR4,MyD88and relevant cytokines in MyD88-dependent signal pathway such as TRAF6,TNF-α，NF-κB, promote the proliferation of HSC, and inhibit the apoptosis of HSC. It maybethe mechanism of endotoxin promoting hepatic fibrosis.