核因子KLF6与PPARγ在大鼠非酒精性脂肪性肝炎中的动态变化

Relationship between PPARγ and KLF6 in nonalcoholic steatohepatitis rat

目的:研究核转录因子过氧化物酶体增殖物活化受体γ(peroxisome proliferation activated receptor gamma,PPARγ)和核因子KLF6(Kruppule like factor,KLF6)在非酒精性脂肪性肝炎(NASH)大鼠肝纤维化形成过程中的作用及相互关系。方法:高脂饮食建立NASH肝纤维化大鼠模型,HE和Massson染色观察肝组织病理学变化,检测血清AST、ALT、透明质酸(HA)、层粘连蛋白(LN)、Ⅵ型胶原(CⅥ)的动态变化,RT-PCR检测核转录因子KLF6、PPARγ和α-SMA mRNA的动态表达变化。结果:(1)F12～24周肝脏炎症活动度计分较对照组明显增高(P<0.05～0.01)。(2)F16、24周组肝纤维化评分与对照组比较明显升高,差异有统计学意义(P<0.05～0.01)。(3)高脂喂养12周后,血清AST、ALT水平逐步增高,与对照组比较差异有统计学意义(P<0.05～0.01)。随着高脂喂养时间的延长,血清肝纤维化指标HA、LN和CⅣ水平呈逐渐增高趋势,与对照组比较差异有统计学意义(P<0.05～0.01)。(4)RT-PCR显示模型组PPARγmRNA于高脂喂养8周单纯性脂肪肝时即明显上调(0.84±0.07 vs 0.54±0.12,P<0.05),12周达高峰(1.16±0.14),16周脂肪性肝炎明显时表达开始下调(0.73±0.05),24周下调更为明显(0.34±0.15),与对照组比较差异均有统计学意义(P<0.05);而KLF6、α-SMA mRNA于高脂喂养12周开始增高,24周达高峰,与对照组比较差异显著(P<0.01)。(5)相关分析发现,KLF6与α-SMA表达及炎症、肝纤维化分级评分之间呈显著正相关(r=0.859、0.956、0.706,P<0.01),而与PPARγ呈负相关(r=-0.536,P<0.05)。结论:单纯性脂肪肝时,PPARγ的高表达可能是机体的一种适应性反应,从而抑制促炎、促纤维生成因子KLF6的释放,当损伤因素持续存在,损伤与抗损伤动态平衡失调后PPARγ合成减弱,而KLF6则明显增加,激活HSC,共同参与NASH肝纤维化形成过程。

Objective： To study the relation between PPARγ and KLF6 in the development of nonalcoholic steatohepatitis related fibrosis in rats.Methods：Fatty liver fibrosis model of rats was established by high fat feeding.Pathological change of hepatic tissues was observed by HE and Masson staining;dynastic change of AST,ALT,hyaluronic acid（HA）,laminin（LN） and collagen Ⅵ（CⅥ） were detected,and expressions of PPARγ,KLF6 and α-SMA were determined by RT-PCR.Results：（1）The score of hepatic inflammatory activity was significantly higher in experimental group than control group during F12-24 weeks（P0.01-0.05）.（2） Score of hepatic fibrosis was significantly higher in experimental group than control group at F16 week and 24 weeks（P0.01-0.05）.（3） After high fat feeding for 12 weeks,AST and ALT were significantly increased compared with control group（P0.01-0.05）.HA,LN and CⅣwere increased as feeding time increased,and there were significant difference compared with control group（P0.01-0.05）.（4） RT-PCR showed that the expression of PPARγ mRNA of model group was significance higher as compared with that of rats with the high fat diet for 8 weeks（0.84 ± 0.07 vs.0.54 ± 0.12,P0.05）.The peak was achieved at 12th weeks（1.16± 0.14）,then decreased gradually at 16th week（0.73±0.05）.The decline was more obvious at 24 weeks（0.34±0.15）,and there was significant difference between two groups（P0.05）.While KLF6、α-SMA mRNA were increased at the 12th week.It achieved the peak at 24th week,and there was significant difference between two groups（P0.05）.（5）KLF6 was closely correlated with α-SMA and the scoring of inflammation and hepatic fibrosis（r=0.859,0.956,0.706,P0.01）,but had negative correlation with PPARγ（r=-0.536,P0.05）.Conclusions：In patients with simple fatty liver,high PPARγ expression is an adaptive response,and can inhibit release of KLF6.With the high fat-induced hepatic injury aggravated,the gradually decreased expression of PPARγ is closely related to the activation of KLF6 and hepatic stellate cells,thereby promote the development of fatty liver fibrosis.