丹参对原位肝移植大鼠供肝冷保存再灌注损伤的保护作用

目的:研究表明,丹参对心、脑、肝等重要器官的缺血再灌注损伤有保护作用.制备大鼠异体原位肝移植模型,验证丹参对大鼠肝移植缺血再灌流损伤的保护作用.方法:实验于2006-10/2007-08在南方医院中心实验室及动物实验中心完成,动物实验方法符合动物伦理学要求.①实验材料及分组:选用SD大鼠40只,按随机数字表法分为假手术组、模型对照组和丹参注射液组,假手术组8只,模型对照组、丹参注射液组各8对(供体与受体).②实验方法:建立原位肝移植模型,在供肝灌注冷保存时,以4 ℃乳酸林格氏液为基液,丹参注射液组灌注保存液中加60 mL/L丹参注射液;模型对照组不加丹参.③实验评估:移植术后6 h处死各组大鼠取样,检测血清谷草转氨酶、谷丙转氨酶及乳酸脱氢酶活性;测定肝组织中丙二醛含量及超氧化物歧化酶、谷胱甘肽过氧化物酶活性,并对比观察移植肝病理形态学改变.结果:模型对照组和丹参注射液组16只受体大鼠及假手术组8只大鼠全部进入结果分析,无脱失.①丹参注射液组和模型对照组移植肝再灌注后血清谷丙转氨酶、谷草转氨酶及乳酸脱氢酶活性均高于假手术组(P < 0.01);丹参注射液组低于模型对照组(P < 0.01).②丹参注射液组肝组织中丙二醛含量较模型对照组明显下降(P < 0.01),超氧化物歧化酶和谷胱甘肽过氧化物酶的活性则明显升高 (P < 0.01).③丹参注射液组较模型对照组肝组织肝细胞坏死程度减轻,炎性细胞浸润减少,肝组织再灌注损害程度减轻.结论:丹参对原位肝移植肝脏的缺血再灌注损伤有保护作用,从而减轻氧自由基及脂质过氧化,保护细胞膜,改善肝功能.     

前列腺素E1对大鼠供肝灌注冷保存的保护作用

目的应用高渗构橼酸盐腺嘌呤液（HCA液）加前列腺素E1（PGE1）对大鼠供肝进行灌注,探讨PGE。在供肝灌注冷保存中对肝脏的保护作用。方法采用雄性SD大鼠肝脏单纯冷保存离体灌注模型,随机分为实验组和对照组。每组30只。实验组是HCA灌注液中加入PGE．加器官保存液（UW液）注取肝,对照组则单纯使用HCA液加UW液灌注取肝。经不同冷保存时间后,检测丙氨酸转氨酶（ALT）、乳酸脱氢酶（LDH）、髓过氧化物酶（MPO）以及丙二醛（MDA）、超氧化物歧化酶（SOD）及病理学变化。结果在10h和20h保存时间点,实验组ALT和LDH以及MDA和MPO均明显低于对照组,且酶值水平均随冷保存时间延长增高（P〈0．01）;实验组SOD高于对照组,且随时间延长降低（P〈0．01）。病理变化可见实验组肝窦、肝细胞索结构清晰,肝轻度肿胀,无细胞坏死。结论HCA液中加入PGE1后对肝脏冷保存损伤具有一定的保护作用,其机制可能与PGE1在灌注过程中通过改善微循环提高组织的抗氧化能力,减少中性粒细胞与肝窦库普弗细胞及内皮细胞的黏附,减轻多种组织和细胞损伤等因素有关。     

Involvement of Kupffer cells in the interaction between neutrophils and sinusoidal endothelial cells in rats

During endotoxic liver injury, large numbers of neutrophils infiltrate the liver, and serum levels of tumor necrosis factor-alpha (TNF-alpha) become elevated. The object of this study was to assess the roles of TNF-alpha secreted by Kupffer cells in the interaction between neutrophils and sinusoidal endothelial cells (SECs). Rat neutrophils were perfused onto SECs that were stimulated with either TNF-alpha or supernatant from lipopolysaccharide (LPS)-stimulated Kupffer cells using an in vitro flow system. Numbers of adhered or migrated neutrophils were counted, and the effect of an antibody against intercellular adhesion molecule-1 (ICAM-1) was studied. Compared with controls (200 +/- 21 cells/mm2), neutrophil adhesion to SECs was significantly increased by both TNF-alpha (342 +/- 26 cells/mm2; P < 0.05) and LPS-stimulated Kupffer cell supernatant (331 +/- 29 cells/mm2; P < 0.05). Anti-ICAM-1 significantly inhibited neutrophil adhesion (139 +/- 10 cells/mm2; P < 0.05) and decreased the migration rate of neutrophils on SECs treated with LPS-stimulated Kupffer cell supernatant (P < 0.05). LPS-stimulated Kupffer cells secreted TNF-alpha in an LPS dose-dependent manner, and they significantly enhanced ICAM-1 expression on SECs (P < 0.05 vs. control). In addition, dexamethasone suppressed TNF-alpha production by LPS-stimulated Kupffer cells and decreased ICAM-1 expression and neutrophil adhesion on SECs. These findings suggest that Kupffer cells are involved in neutrophil adhesion and migration in hepatic sinusoids via TNF-alpha production and induction of ICAM-1 expression on SECs during liver injury associated with endotoxemia.     

裸鼠肝窦内皮细胞的分离、培养及鉴定

背景:建立裸鼠肝窦内皮细胞的原代分离培养方法,进一步研究其生长特点及生物学特性。目的:建立裸鼠肝窦内皮细胞的原代分离、培养方法,并鉴定其纯度及观察其生物学特性。方法:无菌下摘除裸鼠肝脏,剪成1mm3大小,Ⅳ型胶原酶在37℃恒温下消化,应用CD146免疫磁珠分选肝窦内皮细胞,在倒置显微镜观察内皮细胞形态及生长特性,用von-Willebrand因子免疫细胞化学验证分选细胞的表面蛋白表达,鉴定肝窦内皮细胞的纯度,Hochest33342测定凋亡。结果与结论:分离的肝窦内皮细胞纯度达95%以上,活力好,光镜下可以看到典型的铺路石样形态,von-Willebrand因子免疫细胞化学染色阳性。肝窦内皮细胞在体外培养3周后凋亡。提示Ⅳ型胶原酶消化加CD146免疫磁珠分选肝窦内皮细胞纯度高,方法可靠。     

Liver sinusoidal endothelial cell progenitor cells promote liver regeneration in rats

The ability of the liver to regenerate is crucial to protect liver function after injury and during chronic disease. Increases in hepatocyte growth factor (HGF) in liver sinusoidal endothelial cells (LSECs) are thought to drive liver regeneration. However, in contrast to endothelial progenitor cells, mature LSECs express little HGF. Therefore, we sought to establish in rats whether liver injury causes BM LSEC progenitor cells to engraft in the liver and provide increased levels of HGF and to examine the relative contribution of resident and BM LSEC progenitors. LSEC label-retaining cells and progenitors were identified in liver and LSEC progenitors in BM. BM LSEC progenitors did not contribute to normal LSEC turnover in the liver. However, after partial hepatectomy, BM LSEC progenitor proliferation and mobilization to the circulation doubled. In the liver, one-quarter of the LSECs were BM derived, and BM LSEC progenitors differentiated into fenestrated LSECs. When irradiated rats underwent partial hepatectomy, liver regeneration was compromised, but infusion of LSEC progenitors rescued the defect. Further analysis revealed that BM LSEC progenitors expressed substantially more HGF and were more proliferative than resident LSEC progenitors after partial hepatectomy. Resident LSEC progenitors within their niche may play a smaller role in recovery from partial hepatectomy than BM LSEC progenitors, but, when infused after injury, these progenitors engrafted and expanded markedly over a 2-month period. In conclusion, LSEC progenitor cells are present in liver and BM, and recruitment of BM LSEC progenitors is necessary for normal liver regeneration.     

Hydrogen peroxide induces midzonal heat shock protein 72 and apoptosis in sinusoidal endothelial cells of hypoxic rat liver

OBJECTIVE: To investigate the heat shock protein (HSP) 72 expression and apoptosis induced by hydrogen peroxide in hypoxic rat liver. DESIGN: Prospective control study using the isolated rat liver. SETTING: Animal research facility. SUBJECTS: Fasted, pathogen-free specific, male Sprague-Dawley rats. INTERVENTIONS: A low-flow hypoxia model was made by reducing an afferent pressure from 10 to 2.5 cm H2O, and by perfusing the isolated rat liver for 2 hrs. MEASUREMENT AND MAIN RESULTS: We investigated the hydrogen peroxide production by using the 2'-7' dichlorofluorescein image, the induction of HSP 72 by using immunohistochemistry, and apoptosis by using terminal deoxynucleotidyl transferase-mediated dUTP-digoxigenin nick end-labeling method in the low flow hypoxic rat liver. In low-flow hypoxia, hydrogen peroxide production, HSP 72 expression, and apoptosis were induced in the midzone of rat liver. Prevalence of HSP 72 expression was higher in the sinusoidal endothelial cells (SEC) than in the hepatocytes. All apoptotic cells were SEC with expression of HSP 72. Hydrogen peroxide was derived from hepatocytes. Pretreatment with the specific xanthine oxidase inhibitor, sodium(-)-8-(3-methoxy-phenylsulfinylphenyl) pyrazolo [1,5-a]-1,3,5-triazine-4-olate monohydrate significantly attenuated hydrogen peroxide production, HSP 72 expression, and apoptosis of SEC in the midzone. CONCLUSION: Xanthine oxidase-dependent hydrogen peroxide induces midzonal and SEC-dominant HSP 72 expression and apoptosis in hypoxic rat liver.     

A hemodynamic response to intravenous adenovirus vector particles is caused by systemic Kupffer cell-mediated activation of endothelial cells

Intravascular injection of adenoviral vectors may result in a toxic and potentially lethal reaction, the mechanism of which is poorly understood. We noted that mice demonstrated a transient change in behavior that was characterized by inactivity and lethargy within minutes after intravenous injection of relatively low doses of adenoviral vectors (including high-capacity gutless vectors). Moreover, immediately after vector injection a significant drop in blood pressure was measured that most probably was caused by the systemic activation of endothelial cells as monitored by detection of phosphorylated Akt/PKB kinase, activated endothelial nitric oxide synthase (eNOS), and nitrotyrosine. The activation of the endothelium was the result of the interaction of viral particles with Kupffer cells, which are resident macrophages of the liver representing the first line of defense of the innate immune system. Surprisingly, the uptake of vector particles by Kupffer cells not only resulted in their strong activation, but also in their nearly complete disappearance from the liver. Our results suggest that the toxicity of intravenously injected adenoviral vectors may be directly linked to the activation and destruction of Kupffer cells.     

Differential regulation of protein S expression in hepatocytes and sinusoidal endothelial cells in rats with cirrhosis

Summary.  Background: Liver dysfunction caused by intrasinusoidal microthrombi is frequently observed in patients with cirrhosis after hepatectomy, but the mechanistic pathway remains unknown. Objective: In the present study, we evaluated the expression of protein S (PS) in hepatocytes and sinusoidal endothelial cells (SECs) from rats with dimethylnitrosoamine-induced cirrhosis before and after hepatectomy. Results: The plasma level of PS antigen was significantly decreased in cirrhotic rats as compared to control rats treated with vehicle. PS expression was significantly decreased in hepatocytes isolated from cirrhotic rats as compared to controls. In contrast, PS expression was significantly increased in SECs isolated from rats with cirrhosis as compared to controls. Interkeukin-6 (IL-6) upregulated the expression of PS in hepatocytes, and tumor necrosis factor- α (TNF- α ) decreased its expression in SECs from both cirrhotic and normal rats. The production of IL-6 and TNF- α by Kupffer cells and SECs was decreased in rats with cirrhosis as compared to controls. After hepatectomy, microthrombus formation was markedly enhanced in sinusoids from rats with cirrhosis, and the plasma levels of IL-6 and TNF- α were significantly increased in rats with cirrhosis as compared to controls. Furthermore, PS production in SECs was decreased, whereas that in hepatocytes was significantly increased in cirrhotic rats as compared to controls. Conclusions: These findings suggest that PS expression is differently regulated in hepatocytes and SECs of rats with cirrhosis before and after hepatectomy, that the expression of PS is regulated by locally released inflammatory cytokines, and that decreased expression of PS in SECs may cause liver microthrombus formation, which is frequently observed in patients with cirrhosis after hepatectomy.     

Differential effect of anti-TNF-alpha antibody on proinflammatory cytokine release by Kupffer cells following liver ischemia and reperfusion.

To study the role of tumor necrosis factor-alpha (TNF-alpha) for induction of the proinflammatory cytokine cascade after liver ischemia and reperfusion (I/R), rats were injected intraperitoneally with anti-TNF-alpha monoclonal antibodies (mAb) or placebo (IgG1) 30 min prior to global hepatic ischemia. Blood levels of TNF-alpha, interleukin (IL)-1alpha and -6 were determined. In addition, Kupffer cells (KC) were harvested after 60 min of reperfusion and spontaneous cytokine release was measured. Sham-operated animals were used as controls. Levels of proinflammatory cytokines in serum and KC supernatants were detected using specific bioassays and ELISA. Liver I/R resulted in increased (p < .01) serum levels of TNF-alpha, IL-1alpha, and IL-6, which was associated with an enhanced (p < .05) release of these cytokines by KC. In vivo pretreatment with anti-TNF-alpha mAb led to complete neutralization of TNF-alpha serum levels and decreased (p < .01) IL-6 levels (-62%). Moreover, anti-TNF-alpha mAb markedly (p < .05) decreased the release of TNF-alpha (-69%) and IL-6 (-56%) by KC, while IL-1alpha was not affected. These data indicate that TNF-alpha produced early after liver I/R triggers both its own secretion as well as IL-6 release by KC during reperfusion while the release of IL-1alpha occurs independent from TNF-alpha.