Pathological mechanisms of alcohol-induced hepatic portal hypertension in early stage fibrosis rat model

AIM： To study the role of hepatic sinusoidal capillarization and perisinusoidal fibrosis in rats with alcohol-induced portal hypertension and to discuss the pathological mechanisms of alcohol-induced hepatic portal hypertension. METHODS： Fifty SD rats were divided into control group （n=20） and model group （n=30）. Alcoholic liver fibrosis rat model was induced by intragastric infusion of a mixture containing alcohol, corn oil and pyrazole （1 000：250：3）. Fifteen rats in each group were killed at wk 16. The diameter and pressure of portal vein were measured. Plasma hyaluronic acid （HA）, type IV collagen （COW） and laminin （LN） were determined by radioimmunoassay. Liver tissue was fixed in formalin （10%） and 6-μm thick sections were routinely stained with Mallory and Sirius Red. Liver tissue was treated with rabbit polydonal antibody against LN and ColⅣ. Hepatic non-parenchymal cells were isolated, total protein was extracted and separated by SDS-PAGE. MMP-2 and TIMP-1 protein expression was estimated by Western blotting. RESULTS： The diameter （2.207 ± 0.096 vs 1.528±0.054 mm, P〈0.01） and pressure （11.014±0.395 vs 8.533±0.274 mmHg, P〈0.01） of portal vein were significantly higher in model group than those in the control group. Plasma HA （129.97±16.10 vs 73.09±2.38 ng/mL, P〈0.01）, ColⅣ （210.49±4.36 vs 89.65±4.42 ng/mL, P〈0.01） and LN （105.00±7.29 vs 55.70±4.32 ng/mL, P〈0.01） were upregulated in model group. Abundant collagen deposited around the central vein of Iobules, hepatic sinusoids and hepatocytes in model group. ColⅠ and ColⅢ increased remarkably and perisinusoids were almost surrounded by ColⅢ. Immunohistochemical staining showed that ColⅣ protein level （0.130±0.007 vs 0.032±0.004, P〈0.01） and LN protein level （0.152±0.005 vs 0.029±0.005, P〈0.01） were up-regulated remarkably in model group. MMP-2 protein expression （2.306±1.089 vs 0.612±0.081, P〈0.01） and TIMP-1 protein expression （3.015±1.364 vs 0.446±0.009, P〈0.01） in freshly isolated hepatic nonparenchymal cells were up-regulated in model group and TIMP-1 protein expression was evidently higher than MMP-2 protein expression （2.669±0.170 vs 1.695±0.008, P〈0.05）. CONCLUSION： Hepatic sinusoidal capillarization and peri-sinusoidal fibrosis are responsible for alcoholinduced portal hypertension in rats,

肝硬化时肝窦毛细血管化形成机制

目的:探讨肠源性内毒素血症在肝窦毛细血管化形成中的作用及其可能机制.方法:♂Wistar大鼠40只,完全随机分为模型组(n=32)与正常对照组(n=8),采用复合因素致肝硬化大鼠模型.模型组分别在饲养第2,4,6,8周末,正常对照组在实验开始时,经肠系膜上静脉末端穿刺测PVP,肝脏HE、VG染色,肝脏免疫组织化学染色观察α-SMA、LN、TGF-β1的动态表达,测定外周血中的内毒素、TNF-α、ALT的动态变化,采用扫描电镜观察肝窦内皮细胞失窗孔情况.结果:模型组ALT在第2周末达到高峰(57.84±7.57IU/L),随后逐渐下降;内毒素在第2、4、6周末,各点呈递增趋势,到第8周末时略有下降;TNF-α在第2、4周末呈递增趋势,到第6周末时略有下降,第8周末时又逐渐升高,但各点组均较对照组明显升高(均P<0.05);模型组PVP在第2、4周末,各点呈递增趋势,到第6周末时略有下降,第8周末时又逐渐升高;肝窦内皮细胞扫描电镜结果示随着肝纤维化及硬化程度的加重,窗孔逐渐变小、变少至消失;LN、TGF-β1免疫组织化学染色结果示随着病变的发展,与对照组和同指标前一时间组相比阳性表达逐渐增强(均P<0.05).α-SMA免疫组织化学染色在第2、4、6周末,阳性表达逐渐增强,到第8周末时略有下降.结论:肝硬化大鼠发生了肠源性内毒素血症,其可使TGF-β1、TNF-α、LN等合成增多,促进肝窦内皮细胞去窗孔化,间接参与肝窦毛细血管化的形成.

肝窦毛细血管化的形成机制研究

目的 探讨二甲基亚硝胺 (DMN)致大鼠肝纤维化过程中肝窦壁病理变化及其与门脉压力的关系。方法 雄性Wistar大鼠 4 0只用 0 .5 %DMN每周连续 3d共 4周 12次腹腔注射制作大鼠肝纤维化模型 ,分别于造模后 1d、2d、3d、1周、2周、4周、6周、8周作为动态观察时相点 ;分别取 5只模型大鼠和 3只正常大鼠肠系膜前静脉分支插管法测门脉压力 (Ppv) ;免疫组化染色观察肝组织Ⅳ型胶原(ColⅣ )、层粘连蛋白 (LM)和Ⅰ型胶原 (ColⅠ )表达 ;透射电镜观察肝组织超微结构。结果 正常大鼠肝窦壁ColⅣ阳性表达 ;模型组肝窦壁除ColⅣ阳性染色呈现为先弱后强外 ,LM和ColⅠ的沉积均随造模时间的延长而进行性增加 ,4周时表达最为明显 ,电镜下可见肝窦内皮失窗孔和内皮下完整基底膜形成 ;模型组Ppv与肝窦壁LM的表达量呈显著正相关 (P <0 .0 5 )。结论 DMN大鼠肝窦内皮下基底膜是在功能性基底膜破坏的基础上 ,随着LM与新合成ColⅣ沉积以及两者结合的增加。