Experimental Study On The Mechanism Of Dexmedetomidine To Promote Liver Regeneration In Mice After Hepatectomy

Liver regeneration after hepatectomy and protection of liver function are important factors to determine the prognosis of the patients.Therefore,hepatic ischemia reperfusion injury in the perioperative period of hepatectomy is of particular concern.Tissue ischemia and reperfusion injury repair and regeneration process is complex,a large number of molecular pathways have been shown to play an important role in inflammasome activation is mediated by NOD-like receptors(NLRs)that play important role in cellular proliferation.NLRP3 senses the widest array of stimuli.But its role in the liver regeneration after partial hepatectomy(PHx)is still unknown.Dexmedetomidine(Dex)has been documented to protect the liver against ischemia-reperfusion injury via the suppression of the TLR4/NF-κB pathway which is important for NLRP3 inflammasome activation and liver regeneration.We tested whether Dex controbutes to liver regeneration,and investigated its consequent effect on inflammasome activation.Part Ⅰ: Experimental study on the effect of Dexmedetomidine on human L02 hepatocytes in vitroBackground: We aimed to investigate the effect of Dexmedetomidine on human L02 hepatocytes in vitro.Materials and Methods: In vitro,L02 human liver cells were treated with Dex at different concentrations.MTT examined the viability of L02 cells.Western blot was used to detect the expression level of TLR4/NF-kappa B protein.Results: Dex significantly inhibited the proliferation of L02 cells in vitro,but it does not have dose dependence.Dex significantly decreased the expression levels of TLR4/NF-κB in L02 human liver cells.Conclusions:Dex could significantly inhibit the proliferation of L02 cells in vitro and decrease the expression of TLR4/NF-κB which may be associated with suppressed expression levels of TLR4/NF-κB pathway.Part Ⅱ: Experimental study on the effect of dexmedetomidine promoting liver regeneration after liver resection in miceBackground: Dexmedetomidine(Dex)has been documented to protect the liver against ischemia-reperfusion injury and inflammation is important for liver regeneration.We tested whether Dex controbutes to liver regeneration and investigated its consequent effect on imflammation and TLR4/NF-κB pathway.Materials and Methods: The 70% PHx was performed in C57 BL/6 mice as PHx group and sham-operated animals as Sham group.Dex-treated animals were assigned into two groups: Dex+PHx which received single intraperitoneal injections of Dex(25μg/kg)before PHx 30 mins;Dex+PHx+Dex which received additional Dex(25μg/kg)after PHx for 3 days.Serum levels of aminotransferase(ALT)and aspartate aminotransferase(AST)were measured.H&E staining was performed to identify the histopathological changes in livers.IL-1β and TNF-α were measured by ELISA kits.Western blotting examined the expression levels of NF-κB,TLR4 and so on.Results: In vivo,Dex+PHx exhibited promotion effect on liver regeneration and liver function recovery via inhibiting inflammation.Dex+PHx+Dex inhibited the liver regeneration which may be associated with the over-suppressed inflammation mediated by TLR4/NF-κB pathway.Conclusions:Though Dex pretreatment contributed to liver regeneration and function recovery via inflammation suppression,excessive inflammation suppression could inhibit liver regeneration which could be associated with the inhibition effect of Dex on TLR4/NF-κB pathway,suggesting that Dex+PHx might be a useful therapeutic strategy to promote liver regeneration in clinical.Part Ⅲ: Molecular Mechanism of Dexmedetomidine in Promoting and Inhibiting Hepatic Regeneration after Hepatectomy in MiceBackground:Inflammasome activation is mediated by NOD-like receptors(NLRs)that play important role in cellular proliferation.NLRP3 senses the widest array of stimuli.But its role in the liver regeneration after partial hepatectomy(PHx)is still unknown.Dexmedetomidine(Dex)has been documented to protect the liver against ischemia-reperfusion injury via the suppression of the TLR4/NF-κB pathway which is important for NLRP3 inflammasome activation and liver regeneration.We tested whether Dex controbutes to liver regeneration and investigated its consequent effect on inflammasome activation.Materials and Methods: The 70% PHx was performed in C57 BL/6 mice as PHx group,and sham-operated animals as Sham group,Dex-treated animals were assigned into two groups: Dex+PHx which received single intraperitoneal injections of Dex(25μg/kg)before PHx 30 mins;Dex+PHx+Dex which received additional Dex(25μg/kg)after PHx for 3 days.Western blotting examined the expression levels of NLRP3,ACS,Caspase-1 and so on.Results: In vivo,Dex+PHx exhibited promotion effect on liver regeneration and liver function recovery via inhibiting NLRP3 inflammasome activation.Dex+PH+Dex inhibited the liver regeneration which may be associated with suppressed expression levels of TLR4/NF-κB pathway.Conclusions:Though Dex pretreatment contributed to liver regeneration and function recovery via inflammation suppression,excessive inflammation suppression accompanied with TLR4 suppression could inhibit liver regeneration,suggesting that TLR4/NF-κB was essential for liver regeneration and Dex+PHx might be a useful therapeutic strategy to promote liver regeneration in clinical.