Inhibition of concanavalin A-induced acute T cell dependent hepatic damage in mice by hypothyroidism.

AIMS/BACKGROUND: Concanavalin A (Con A) activates T lymphocytes and causes acute T-cell-mediated hepatic injury in mice. Decreased thyroid hormonal production is associated with a variety of immunological manifestations, including inactivation of macrophages with reduced TNF production and reduced soluble IL-2 receptors in the serum. We have recently shown that hypothyroidism prevents the development of cirrhosis and also minimizes hepatic damage in rats with fulminant hepatic failure. In the present study we examined the effects of hypothyroidism on a mouse model of Con A induced T cell-mediated acute hepatitis. METHODS: Hypothyroidism was induced both medically (MMI, PTU) and surgically. Eight groups of 10 mice each were studied: euthyroid controls (2 groups: water, Con A) and hypothyroid (6 groups: MMI, PTU, Surgical, MMI-Con A, PTU-Con A, Surgical-Con A). RESULTS: Hepatic inflammation was significantly decreased in each of the Con A treated hypothyroid groups of mice. The serum transaminases, TNF-alpha and IL-6 levels were significantly elevated in the Con A treated group while near normal levels were found in the hypothyroid Con A treated groups (mean+/-SE AST: 1499+/-18 vs 78+/-10 IU/l, p<0.001; TNF: 2500+/-250 vs 135+/-15 pg/ml, p<0.001, IL-6: 12,200+/-300 vs 1260+/-140 pg/ml, p<0.001, respectively). CONCLUSIONS: Hypothyroidism, independent of the mode of induction, can effectively inhibit the development of acute T cell-mediated liver damage in mice. These results suggest that some decrease in thyroid function might have a role in the prevention of immune mediated liver diseases.     

ConA诱发昆明小鼠T细胞依赖性肝脏损害

目的制作ConA引发昆明小鼠T细胞介导的肝损害方法参考Tiegsetal工作的基础上，本文经尾静脉将ConA2mL（10，20，40mg／Kg）注入昆明小鼠（n＝6）体内．8h后测定血清ALT及肝组织MDA，并作肝组织HE染色，病理学检查．对照组（n＝6）仅采用溶剂PBS2mL另外，用环胞素A（CSA）130mg／kg预处理（－15h，－1h），并作同样检查，观察预防效果．结果成功地诱发了T细胞介导的特异性肝脏损害，其肝脏损害为ConA剂量依赖性；肝组织病理示，门管区大量淋巴细胞浸润，并可见点片状肝细胞坏死．以CSA预先抑制T细胞活化，则未见肝脏损害，肝组织病理也未发现淋巴细胞的浸润．结论ConA诱发的肝损害为无种属特异性的T细胞介导的肝损害，他为深入研究病毒性与自身免疫性肝损害的病理机制提供了又一方便理想的实验动物模型．     

Effects of intravenous immunoglobulins on T-cell mediated,concanavalin A-induced hepatitis in mice

Abstract: Concanavalin A (ConA) activates T lymphocytes and causes T-cell mediated hepatic injury in mice. The intravenous administration of human immunoglobulins has beneficial effects in T-cell mediated diseases such as experimental autoimmune encephalomyelitis and adjuvant arthritis. In the present study, we examined the effects of intravenous immunoglobulins in a mouse model of T-cell mediated, acute liver injury induced by concanavalin A. Balb/c mice were inoculated with 12 mg/kg concanavalin A with or without intravenous immunoglobulins at doses of 0.4, 0.6, 0.8 g/kg body wt. The serum levels of liver enzymes, tumor necrosis factor-α, interferon-γ and interleukin-6 were assayed 2, 6 and 24 h after concanavalin A administration. Intravenous immunoglobulins did not prevent concanavalin A-induced hepatitis, as manifested by elevation of serum aminotransferases and histopathological evaluation. The serum levels of tumor necrosis factor-α in mice pretreated with immunoglobulins, measured 2 h after ConA treatment were reduced, while interferon-γ levels measured 6 h after ConA inoculation were 5-fold higher than control levels. There was no effect of intravenous immunoglobulins on the release of interleukin 6. In conclusion, these results indicate that intravenous immunoglobulin is not effective in preventing T-cell mediated concanavalin A-induced hepatitis. The increased secretion of interferon-γ and the incomplete suppression of tumor necrosis factor-α release may explain the lack of efficacy of intravenous immunoglobulin in this experimental model.     

Natural killer T cell dysfunction in CD39-null mice protects against concanavalin A-induced hepatitis

Concanavalin A (Con A)-induced injury is an established natural killer T (NKT) cell-mediated model of inflammation that has been used in studies of immune liver disease. Extracellular nucleotides, such as adenosine triphosphate, are released by Con A-stimulated cells and bind to specific purinergic type 2 receptors to modulate immune activation responses. Levels of extracellular nucleotides are in turn closely regulated by ectonucleotidases, such as CD39/NTPDase1. Effects of extracellular nucleotides and CD39 on NKT cell activation and upon hepatic inflammation have been largely unexplored to date. Here, we show that NKT cells express both CD39 and CD73/ecto-5'-nucleotidase and can therefore generate adenosine from extracellular nucleotides, whereas natural killer cells do not express CD73. In vivo, mice null for CD39 are protected from Con A-induced liver injury and show substantively lower serum levels of interleukin-4 and interferon-gamma when compared with matched wild-type mice. Numbers of hepatic NKT cells are significantly decreased in CD39 null mice after Con A administration. Hepatic NKT cells express most P2X and P2Y receptors; exceptions include P2X3 and P2Y11. Heightened levels of apoptosis of CD39 null NKT cells in vivo and in vitro appear to be driven by unimpeded activation of the P2X7 receptor. CONCLUSION: CD39 and CD73 are novel phenotypic markers of NKT cells. In turn, CD39 expression [corrected] modulates nucleotide-mediated cytokine production by, and limits apoptosis of, hepatic NKT cells. Deletion of CD39 is protective in [corrected] Con A-induced hepatitis. This study illustrates a [corrected] role for purinergic signaling in NKT-mediated mechanisms that result in liver immune injury.     

Allicin, the active component of garlic, prevents immune-mediated, concanavalin A-induced hepatic injury in mice.

BACKGROUND/AIM: Allicin, the immunologically active component of garlic, has been found to affect oxidative stress and immune response in several experimental systems. In the present study, we examined the ability of allicin to prevent immune-mediated, concanavalin A (Con A)-induced liver damage in mice. METHODS: Mice were pretreated with allicin for 7 days before their inoculation with Con A (15 mg/kg). The serum levels of liver enzymes and liver histology were examined 24 h after Con A administration. The effect of Con A and allicin on serum levels of tumor necrosis factor-alpha (TNF-alpha) and nuclear factor-kappaB (NF-kappaB) activation in the liver were examined 2 h after Con A administration, in a separate group of rats, and the effect of allicin on Con A-induced expression of inducible nitric oxide synthase (iNOS) was determined by western blot analysis 24 h after Con A injection. RESULTS: The histopathologic damage in the mouse livers, and the Con A-induced increase of aminotransferases and TNF-alpha were markedly inhibited in the mice pretreated with allicin before Con A injection (P < 0.01). NF-kappaB binding activity to the nucleus, which increased 2 h after Con A administration, was attenuated by allicin. The expression of iNOS protein which was induced following Con A administration was significantly attenuated by allicin. In vitro studies showed that allicin inhibited TNF-alpha-mediated T cell adhesion to extracellular matrix components and to endothelial cells. Allicin also inhibited TNF-alpha-mediated intercellular adhesion molecule-1 and vascular cell adhesion molecule-1 expression on human vascular endothelial cells. CONCLUSIONS: This study demonstrates that immune-mediated liver damage in mice can be prevented by allicin, probably because of its immunomodulatory effects on T cells and adhesion molecules and inhibition of NF-kappaB activation.     

刀豆蛋白A诱导的急性肝损伤小鼠血浆细胞外组蛋白的变化及意义

目的研究细胞外组蛋白在刀豆蛋白A(Con A)诱导的小鼠急性肝损伤时的水平变化及干预价值。方法小鼠经尾静脉注射Con A(35 mg·kg-1)建立急性肝损伤模型,同时给予特异性抗组蛋白中和抗体进行干预,比较两组小鼠的存活率、肝功能以及相关细胞因子水平的变化。结果给予小鼠Con A后,染毒3 h、9 h、16 h和24h时血清ALT水平升高为(106.5±25.5)IU/L、(769.1±138.2)IU/L、(1340.2±205.9)IU/L和(1304.7±300.7)IU/L,均明显高于对照组[(35.5±3.165)IU/L,P0.01];肝组织病理学检查显示有大量肝细胞发生变性、坏死;Con A染毒小鼠血浆细胞外组蛋白水平亦呈时间依赖方式明显增高,染毒3 h、9 h、16 h和24 h时,细胞外组蛋白相对水平分别为(1.199±0.1087)、(2.467±0.197)、(2.655±0.2295)和(2.631±0.3014),显著高于对照组水平[(0.206±0.024),P0.001];染毒小鼠经特异性抗组蛋白中和抗体干预后,死亡率明显下降,病理学显示肝损伤程度亦得到减轻,其血清IL-6和TNF-α水平分别为(16.98±3.67)pg/ml和(3.25±0.67)pg/ml,较模型组水平显著降低[分别为(238.10±48.56)pg/ml和(16.52±2.43)pg/ml,P0.01]。结论细胞外组蛋白是Con A所致急性肝损伤发病过程中的重要炎性介质,以细胞外组蛋白为靶点进行干预能减轻肝脏炎症反应。     

Kupffer cells contribute to concanavalin A-induced hepatic injury through a Th1 but not Th17 type response-dependent pathway in mice

BACKGROUND:Increasing evidence suggests that a close interaction of Kupffer cells with T cells plays a central role in concanavalin A-induced hepatic injury in mice,but the underlying mechanisms remain obscure.The present study aimed to determine the relative roles of Th1 and Th17 type responses in concanavalin A-induced hepatic injury in mice, and to investigate whether or not Kupffer cells contribute to hepatic injury via a Th1 or Th17 type response-dependent pathway. METHODS:Immune-mediated hepatic injur...     

Colgalt2敲除对刀豆蛋白A诱导的自身免疫性肝炎小鼠CD4 T细胞记忆和归巢的影响

目的 初步探索糖基转移酶Colgalt2基因敲除对刀豆蛋白A(concanavalin A,Con A)诱导的自身免疫性肝炎(autoimmunehepatitis,AIH)小鼠模型中CD4 T细胞记忆和归巢的影响。方法 随机抽取无特定病原体(specific pathogen free,SPF)级6～8周的基因敲除(Colgalt2^-/-)小鼠与野生型Colgalt2^+/+小鼠各18只,建立Con A诱导的AIH小鼠模型。检测小鼠血浆中丙氨酸氨基转移酶(alanine aminotransferase,ALT)和天门冬氨酸氨基转移酶(aspartate aminotransferase,AST)水平,采用HE染色观察肝组织病理变化,采用体外磁珠分选脾脏CD4⁺T细胞,采用流式细胞术检测小鼠外周血、脾脏及分选后CD4⁺T细胞亚型比例。结果 与Colgalt2^+/+小鼠相比,Con A刺激12 h Colgalt2^-/-小鼠血清ALT [(15610±286...     

Inhibition of Fas／FasL mRNA expression and TNF-a release in concanavalin A-induced liver injury in mice by bicyclol

AIM: Bicyclol, 4,4‘-dimethoxy-5,6,5‘,6‘-dimethylene-dioxy-2-hydroxymethy1-2‘-carbonyl biphenyl, is a new anti-hepatitis drug. The aim of the present study was to investigate the protective effect of bicyclol on concanavalin A (Con A)-induced immunological liver injury in mice and its mechanism. METHODS: Liver injury was induced by injection of Con A via tail vein of mice and assessed biochemically and histologically. Serum transaminase and tumor necrosis factor alpha (TNF-a were determined. Liver lesions were observed by light microscope. Expressions of TNF-a, interferon gamma (IFN-y), Fas and Fas ligand (FasL) mRNA in the livers were measured by RT-PCR. RESULTS: Serum transaminase level and liver lesions in Con A-induced mice were markedly reduced by oral administration of 100, 200 mg/kg of bicyclol. TNF-a level inserum was also reduced by bicyclol. Con A injection in ducedup-regulation of TNF-a, IFN-7, Fas and FasL mRNA expression in liver tissues. Bicyclol significantly down-regulated the expression of IFN-y, Fas and FasL mRNA, but only slightly affected TNF-a mRNA expression in liver tissues. CONCLUSION: Bicyclol protects against Con A-induced liver injury mainly through inhibition of Fas/FasL mRNA expression in liver tissues and TNF-a release in mice.     

诱导型一氧化氮合酶在ConA诱发T细胞介导的小鼠肝损害中的表达

目的观察诱导型一氧化氮合酶（ｉＮＯＳ）在刀豆素Ａ（ＣｏｎＡ）诱发Ｔ细胞介导的小鼠肝损害中的表达及意义。方法应用黄递酶染色（ＮＡＤＰＨ－ｄ）技术观察ｉＮＯＳ表达。结果ＣｏｎＡ造成肝损害后，血浆中亚硝酸盐（ＮＯ－２）较正常对照组（ＰＢＳ组）显著升高，以Ｌ－ＮＡＭＥ抑制ＮＯ合成，肝细胞损害反而加重，且肝组织内丙二醛（ＭＤＡ）增加，肝窦内血细胞聚集加重；在ＣｏｎＡ造成肝损害时可见肝实质细胞表达ｉＮＯＳ，且越靠近中央静脉的肝细胞表达越多，推测这是肝细胞对缺血缺氧而产生的一种自身反映；用环孢霉素Ａ（ＣＳＡ）预先抑制Ｔ细胞活化，则未发现肝细胞表达ｉＮＯＳ。结论在ＣｏｎＡ性肝损害中，肝实质细胞通过启动自身的ＮＯ生物合成机制参与了炎症应答，并通过消除氧自由基和抑制血细胞在肝窦内聚集而起一定的保护作用，这一生物过程很可能是肝细胞参与机体免疫应答的一部分。     

Efficacy of adipose tissue-derived mesenchymal stem cells for fulminant hepatitis in mice induced by concanavalin A

Background and Aim: Fulminant hepatitis is mainly caused by excessive immune response‐mediated liver injury and its definitive therapy is liver transplantation. Mesenchymal stem cells, one of the adult stem cells, have an immunomodulatory effect on immune cells and reside in various tissues. The aim of this study was to investigate a therapeutic effect of adipose tissue‐derived mesenchymal stem cells (ASCs) on fulminant hepatitis induced by concanavalin A (ConA). Methods: The ASCs were isolated from adipose tissues of BALB/c mice and confirmed by detection of cell surface markers and induction of multi‐lineage differentiation. BALB/c mice were injected with ConA and treated with ASCs, phosphate buffered saline (PBS) or splenocytes (SPLCs). Survival rates, levels of serum liver enzymes, titers of serum cytokines, histopathology and localization of ASCs were investigated. Result: The survival rate of ASC‐injected mice significantly increased compared to PBS or SPLC‐injected mice. This effect was dependent on doses and timing of ASCs injected. Improvement of liver enzyme levels, histopathological changes and suppression of inflammatory cytokine production were observed in ASC‐injected mice. Fluorescent stained ASCs were detected in inflammatory liver, but not in normal liver. Conclusion: These results suggest that ASC treatment has a high potential to be an innovative therapy for fulminant hepatitis.     

Inhibition of Fas/FasL mRNA expression and TNF-α release in concanavalin A-induced liver injury in mice by bicyclol

AIM: Bicyclol, 4,4'-dimethoxy-5,6,5',6'-dimethylene-dioxy-2-hydroxymethyl-2'-carbonyl biphenyl, is a new anti-hepatitis drug. The aim of the present study was to investigate the protective effect of bicyclol on concanavalin A (Con A)-induced immunological liver injury in mice and its mechanism.METHODS: Liver injury was induced by injection of Con A via tail vein of mice and assessed biochemically and histologically. Serum transaminase and tumor necrosis factor alpha (TNF-α) were determined. Liver lesions were observed by light microscope. Expressions of TNF-α, interferon gamma (IFN-γ), Fas and Fas ligand (FasL) mRNA in the livers were measured by RT-PCR.RESULTS: Serum transaminase level and liver lesions in Con A-induced mice were markedly reduced by oral administration of 100, 200 mg/kg of bicyclol. TNF-α level in serum was also reduced by bicyclol. Con A injection induced up-regulation of TNF-α, IFN-γ, Fas and FasL mRNA expression in liver tissues. Bicyclol significantly down-regulated the expression of IFN-γ, Fas and FasL mRNA, but only slightly affected TNF-α mRNA expression in liver tissues.CONCLUSION: Bicyclol protects against Con A-induced liver injury mainly through inhibition of Fas/FasL mRNA expression in liver tissues and TNF-α release in mice.     

Transient hepatic fibrin-ring granulomas in a patient with acute hepatitis A

Abstract: A case of acute hepatitis A associated with fibrin-ring granulomas in the liver is presented. Because a relationship between acute hepatitis A infection and granuloma formation had not previously been established, liver specimens were examined from both the hepatitic and recovery phases. Numerous fibrin-ring granulomas were observed in the parenchyma during the hepatitic phase. The cellular components of the granulomas were largely macrophages and CD4-positive T-cells. Granulomas had disappeared completely by the recovery phase. These results suggest that fibrin-ring granulomas were caused by hepatitis A virus infection. This virus may activate macrophages and CD4-positive T-cells through an as-yet undetermined mechanism.     

Inhibition of concanavalin A-induced hepatic injury of mice by bacterial lipopolysaccharide via the induction of IL-6 and the subsequent reduction of IL-4: the cytokine milieu of concanavalin A hepatitis.

BACKGROUND/AIMS: Liver natural killer 1.1 antigen (NK1)+ T cells and IL-4 play a crucial role in concanavalin-A (Con-A)-induced hepatic injury in mice, and a T helper (Th) 2 immune response was thus suggested to be involved. This study was designed to examine the effect of bacterial lipopolysaccharide (LPS), a strong inducer of a Th 1 immune response, on Con-A hepatic injury and also to clarify further the cytokine milieu of Con-A hepatitis. Methods: LPS were injected into mice before Con-A injection to evaluate the effect on hepatic injury. The effect of the pretreatment with various T1 and Th2 cytokines or anti-cytokine antibodies on Con-A hepatitis was also examined. Results: LPS in quantities > or = 500 ng/mouse, when injected 24 h before Con-A injection, abrogated the Con-A-induced elevation of transaminases, hepatocyte destruction and serum IL-4 elevation. This LPS inhibitory effect was blocked when the mice were injected with either anti-IL-6 antibody before LPS injection or IL-4 before Con-A injection. IL-6, but neither IL-10 nor IL-12 pretreatment suppressed Con-A-induced IL-4 production and hepatitis. NK1+ T cells produced IL-4 while both NK1+ T cells and NK1- T cells produced IFN-gamma. Not only anti-IL-4 antibody but also the anti-IFN-gamma antibody pretreatment inhibited Con-A hepatitis. However, although the anti-IL4 antibody suppressed IL-4 alone, the anti-IFN-gamma Ab unexpectedly inhibited both IFN-gamma and IL-4 elevation, while IL-4 injection evoked a moderate Con-A hepatitis even in the anti-IFN-gamma antibody-treated mice. Furthermore, the IL-4 mutant mice did not develop Con-A hepatitis. CONCLUSION: LPS inhibited Con-A hepatitis by inducing IL-6 and thereby inhibited IL-4 synthesis from NK1+ T cells. Although both IL-4 and IFN-gamma were required for the full induction of Con-A hepatic injury, exogenous IL-4 evoked a moderate Con-A hepatitis, even in the absence of IFN-gamma.     

血府逐瘀汤对刀豆蛋白A诱导小鼠肝纤维化的干预作用

目的：观察血府逐瘀汤对刀豆蛋白A （ Con A）诱导小鼠肝纤维化的干预作用。方法： Balb/c雄性小鼠40只,随机分为正常组（8只）,模型组（16只）和治疗组（16只）。模型组和治疗组按照1.25mg/100g小鼠体重予以尾静脉注射Con A,正常组予注射相应剂量生理盐水,1次/周,共10周。治疗组于造模同时,予血府逐瘀汤药液1ml/100g小鼠体重灌胃,正常组及模型组则予以等量饮用水,1次/d。10周后,处理各组小鼠,留取血清、肝脾标本。全自动生化仪检测血清血清丙氨酸氨基转移酶（ALT）、门冬氨酸氨基转移酶（AST）和白蛋白（Alb）; HE和天狼星红染色观察肝组织炎症和胶原沉积; RT-PCR和Western Blot法检测肝组织α-平滑肌肌动蛋白（α-SMA）和转化生长因子β1（TGF-β1）表达。结果：模型组小鼠ALT和AST活性均较正常组明显升高（P＜0.05）;肝组织HE染色可见肝细胞坏死和大量炎性细胞浸润;天狼猩红染色可见大量胶原沉积和假小叶形成;肝组织α-SMA和TGF-β1较正常组显著升高（P＜0.01）。与模型组相比,治疗组ALT、 AST水平明显降低（P＜0.05）;肝脏炎症和胶原沉积明显改善;α-SMA和TGF-β1表达显著下调（P＜0.01）。结论：血府逐瘀汤可通过减轻肝脏炎症和抑制肝星状细胞活化而改善Con A诱导的小鼠肝纤维化。     

刀豆素A诱导小鼠肝损伤增加肝脏NFκB活性

肝内病理性免疫反应参与多种肝病的发病机制,在发生病毒性肝炎时常同时有肝细胞凋亡和坏死,而且细胞凋亡的强弱与病情轻重呈明显相关性[1].     

Suppressor of cytokine signaling 1 protects mice against concanavalin A-induced hepatitis by inhibiting apoptosis

Iron overload exacerbates various liver diseases. In hepatocytes, a portion of non-heme iron is sequestered in lysosomes and endosomes. The precise mechanisms by which lysosomal iron participates in hepatocellular injury remain uncertain. Here, our aim was to determine the role of intracellular movement of chelatable iron in oxidative stress-induced killing to cultured hepatocytes from C3Heb mice and Sprague-Dawley rats. Mitochondrial polarization and chelatable iron were visualized by confocal microscopy of tetramethylrhodamine methylester (TMRM) and quenching of calcein, respectively. Cell viability and hydroperoxide formation (a measure of lipid peroxidation) were measured fluorometrically using propidium iodide and chloromethyl dihydrodichlorofluorescein, respectively. After collapse of lysosomal/endosomal acidic pH gradients with bafilomycin (50 nM), an inhibitor of the vacuolar proton-pumping adenosine triphosphatase, cytosolic calcein fluorescence became quenched. Deferoxamine mesylate and starch-deferoxamine (1 mM) prevented bafilomycin-induced calcein quenching, indicating that bafilomycin induced release of chelatable iron from lysosomes/endosomes. Bafilomycin also quenched calcein fluorescence in mitochondria, which was blocked by 20 microM Ru360, an inhibitor of the mitochondrial calcium uniporter, consistent with mitochondrial iron uptake by the uniporter. Bafilomycin alone was not sufficient to induce mitochondrial depolarization and cell killing, but in the presence of low-dose tert-butylhydroperoxide (25 microM), bafilomycin enhanced hydroperoxide generation, leading to mitochondrial depolarization and subsequent cell death. CONCLUSION: Taken together, the results are consistent with the conclusion that bafilomycin induces release of chelatable iron from lysosomes/endosomes, which is taken up by mitochondria. Oxidative stress and chelatable iron thus act as two "hits" synergistically promoting toxic radical formation, mitochondrial dysfunction, and cell death. This pathway of intracellular iron translocation is a potential therapeutic target against oxidative stress-mediated hepatotoxicity.     

Treatment of concanavalin A-induced hepatitis in mice with low molecular weight heparin

BACKGROUND/AIMS: Heparin has been noted to inhibit inflammation independent of its known anti-coagulant activity. In the present study, we examined the ability of heparin and low molecular weight heparin to prevent immune-mediated, concanavalin A-induced liver damage. METHODS: Mice were pretreated with either heparin or low molecular weight heparin (Fragmin) prior to their inoculation with concanavalin A (10 mg/kg). Liver enzymes, liver histology, and the serum levels of tumor necrosis factor-a, interleukin-6, and interleukin-10 were examined in the control and treated mice. RESULTS: The histopathologic damage in the liver, and the concanavalin A-induced release of aminotransferases, tumor necrosis factor-a, and interleukin-6 were significantly inhibited in mice pretreated with low molecular weight heparin, whereas the serum levels of the anti-inflammatory cytokine interleukin-10 were increased (p<0.01). Interestingly, maximal inhibition was obtained with low low molecular weight heparin doses (5 and 1 microg/mouse, p<0.001), while higher doses were less effective. Concanavalin A-induced liver injury was not prevented by pretreatment of the mice with heparan sulphate (p<0.001), which although it is structurally similar to heparin possesses neither anti-inflammatory nor anti-coagulant properties. CONCLUSIONS: This study demonstrates the efficacy of low molecular weight heparin in preventing immune-mediated liver damage in mice.     

Superoxide produced by Kupffer cells is an essential effector in concanavalin A-induced hepatitis in mice

Although concanavalin A (Con-A)-induced experimental hepatitis is thought to be induced by activated T cells, natural killer T (NKT) cells, and cytokines, precise mechanisms are still unknown. In the current study, we investigated the roles of Kupffer cells, NKT cells, FasL, tumor necrosis factor (TNF), and superoxide in Con-A hepatitis in C57BL/6 mice. Removal of Kupffer cells using gadolinium chloride (GdCl(3)) from the liver completely inhibited Con-A hepatitis, whereas increased serum TNF and IFN-gamma levels were not inhibited at all. Unexpectedly, anti-FasL antibody pretreatment did not inhibit Con-A hepatitis, whereas it inhibited hepatic injury induced by a synthetic ligand of NKT cells, alpha-galactosylceramide. Furthermore, GdCl(3) pretreatment changed neither the activation-induced down-regulation of NK1.1 antigens as well as T cell receptors of NKT cells nor the increased expression of the CD69 activation antigen of hepatic T cells. CD68(+) Kupffer cells greatly increased in proportion in the early phase after Con-A injection; this increase was abrogated by GdCl(3) pretreatment. Anti-TNF antibody (Ab) pretreatment did not inhibit the increase of Kupffer cells, but it effectively suppressed superoxide/reactive oxygen production from Kupffer cells and the resulting hepatic injury. Conversely, depletion of NKT cells in mice by NK1.1 Ab pretreatment did suppress both the increase of CD68(+) Kupffer cells and Con-A hepatitis. Consistently, the diminution of oxygen radicals produced by Kupffer cells by use of free radical scavengers greatly inhibited Con-A hepatitis without suppressing cytokine production. However, adoptive transfer experiments also indicate that a close interaction/cooperation of Kupffer cells with NKT cells is essential for Con-A hepatitis. Conclusion: Superoxide produced by Kupffer cells may be the essential effector in Con-A hepatitis, and TNF and NKT cells support their activation and superoxide production.     

Atrial tamponade causing acute ischemic hepatic injury after cardiac surgery

A patient developed late cardiac tamponade after aortic valve replacement and coronary artery bypass grafting. Nausea and dramatic elevations of serum aminotransferases were the initial clinical manifestations of cardiac tamponade. Severe acute ischemic hepatic injury secondary to isolated compression of both atrial cavities by two loculated thrombi was diagnosed.