Severe Preservation Injury Induces Il-6/STAT3 Activation with Lack of Cell Cycle Progression After Partial Liver Graft Transplantation

Partial liver graft transplantation is a surgical advance developed to overcome severe donor shortage. Survival of these grafts involves recovery from cold ischemia and reperfusion (CIR) injury, immediate regeneration and maintenance of function. Here we examined the outcome of partial liver grafts in comparison to whole grafts following CIR injury. Lewis rats subjected to orthotopic liver transplantation (OLT) with whole grafts preserved in Viaspan were compared to rats receiving 50% and 30% grafts. Outcome was analyzed by survival and regeneration. Transplantation was associated with 100% survival for all grafts, whereas 16 h preservation resulted in 100%, 20% and 0% survival in animals receiving whole, 50% and 30% grafts, respectively. CIR induced increased IL-6 levels in 50% and 30% grafts, and activation of STAT3. Cell cycle progression (cyclin D1) and regeneration (BrdU) was initiated in all livers preserved for 1 or 8 h, but not in partial grafts preserved for 16 h. In conclusion, partial grafts recover from CIR injury through similar molecular pathways to whole grafts. Partial grafts with severe injury fail to achieve cellular proliferation despite the early initiating signals. This failure could be attributed to the impaired ability of the parenchyma to respond to initiating signals for regeneration.     

Impaired hepatic regeneration by ischemic preconditioning in a rat model of small-for-size liver transplantation

OBJECTIVE: Graft size is one of the major risk factors in adult-to-adult living donor liver transplantation and rapid regeneration is an essential post-operative requirement. Ischemic preconditioning (IPC) has been shown to be an effective strategy in the reduction of hepatic ischemia-reperfusion injury and stimulation of liver regeneration. This study was designed to evaluate the effects of IPC on liver regeneration in small-for-size liver grafts. METHODS: We employed a rat orthotopic liver transplantation model using small-for-size (30%) grafts, in the presence or absence (control) of IPC (10 min of ischemia followed by 15 min of reperfusion). Survival rate, graft injury, hepatocellular proliferation, cell cycle progression, Stat3 activation, as well as TNF-alpha and IL-6 expression were assessed. RESULTS: IPC significantly enhanced the extent of graft injury and hindered hepatic regeneration in small-for-size liver grafts. The 7-day survival rate was also reduced by IPC, but failed to reach statistical significance. IPC did not affect TNF-alpha levels, but significantly decreased the elevation of IL-6 after reperfusion. These findings were correlated with down-regulation of cyclin E and cyclin D1, and decreased numbers of PCNA-positive nuclei in IPC grafts. These results were inconsistent with Stat3 activation, as P-Stat3 exhibited a stronger and prolonged pattern of expression in the IPC group, compared to controls. CONCLUSIONS: Ischemic preconditioning may impair liver regeneration in small-for-size liver grafts by decreasing IL-6 and blunting cell cycle progression, through a mechanism at least partially independent of Stat3.     

IL-6/STAT3通路在冷缺血-再灌注损伤后胆管上皮细胞再生中的意义

目的 探讨白介素6/信号转导及转录激活因子3(IL-6/STAT3)通路在冷缺血-再灌注损伤诱导的胆管上皮细胞(BEC)再生过程中的意义.方法 将大鼠随机分为4组:对照组、CP 1 h组、CP12 h组(供肝分别冷保存1、12 h后行原位肝移植术)和anti-IL-6组(CP12 h组术前1 h给予抗IL-6中和抗体0.5 ms/kg,术后每日给予相同剂量直至观察结束).术后1、3、7、14 d,分别采用ELISA法、免疫组织化学法测定肝组织IL-6浓度及BEC再生情况;实时荧光定量PER法、Western blot法检测各组BEC内IL-6 mRNA以及磷酸化STAT3(p-STAT3)、细胞周期蛋白(cyclin)D1表达水平,测定血清碱性磷酸酶(ALP)、谷氨酰转肽酶(GGT)浓度,并进行肝脏组织学检查.结果 与对照组相比,CP1 h组术后IL-6、p-STAT3及cyclin D1表达水平略增加,血清GGT、ALP仅有轻度、短暂的升高,BEC损伤及再生均不明显.CP 12 h组术后BEC损伤严重,血清GGT、AIP明显升高,至术后14 d恢复正常,肝组织及BEC内IL-6含量增加、BEC内p-STA13和cyclin D1蛋白表达上调,BEC再生明显.经anti-IL-6中和抗体处理后,CP 12 h组IL-6以及p-STAT3和cyelin D1表达降低,BEG再生明显抑制,术后14 d仍可见细胞损伤及ALP、GGT的升高.结论 IL-6/STAT3信号转导通路可能参与缺血-再灌注损伤后胆管上皮细胞的再生过程,对肝移植术后的胆道功能恢复有利.     

Pattern of ischemia reperfusion injury in a mouse orthotopic liver transplant model

BACKGROUND: The molecular pathways of ischemic injury after liver transplantation are complex and difficult to dissect because of the presence of many variables. Transgenic and genetically deficient strains of mice provide ideal models for the study of the contribution of a single gene product in biological processes in vivo. Although well described in rats, prolonged preservation has not been studied in a mouse model of orthotopic liver transplantation (mOLT). The aim of this study was to establish a model of cold ischemia and reperfusion injury in mOLT and describe the pattern of the regenerative response to various lengths of cold storage. MATERIALS AND METHODS: mOLT was performed using a syngeneic combination. Grafts were preserved at 4 degrees C in University of Wisconsin (Viaspan) solution for increasing periods of cold preservation. After cold storage, the liver grafts were transplanted and recipient survival was monitored. Hepatocellular injury was determined by histology, and the regenerative response was quantitated by interleukin 6 upregulation and DNA replication. RESULTS: Long-term survival was 100%, 100%, 88%, and 0% for cold preservation of 1, 4, 8, and 16 h, respectively. Grafts with short preservation times (1 and 4 h) demonstrated limited injury and a weak regenerative response, with slight IL-6 early upregulation and minimal cell division. Eight hours of cold ischemia resulted in prominent injury and an intense regenerative response accompanied by significant IL-6 upregulation and DNA synthesis. Sixteen hours of storage resulted in all recipients succumbing to liver failure, with histology showing extensive hepatic necrosis. CONCLUSIONS: This study demonstrated the feasibility of using the mOLT model for the study of molecular mechanisms associated with recovery from cold ischemia and reperfusion injury. Increasing lengths of cold ischemia correlate with progressive tissue damage whereas recovery is associated with a regenerative response that correlates with the severity of injury.     

FK330, a Novel Inducible Nitric Oxide Synthase Inhibitor, Prevents Ischemia and Reperfusion Injury in Rat Liver Transplantation

Nitric oxide (NO), produced via inducible NO synthase (iNOS), is implicated in the pathophysiology of liver ischemia/reperfusion injury (IRI). We examined the effects of a novel iNOS inhibitor, FK330 (FR260330), in well-defined rat liver IRI models. In a model of liver cold ischemia followed by ex vivo reperfusion, treatment with FK330 improved portal venous flow, increased bile production and decreased hepatocellular damage. FK330 prevented IRI in rat model of 40-h cold ischemia followed by syngeneic orthotopic liver transplantation (OLT), as evidenced by: (1) increased OLT survival (from 20% to 80%); (2) decreased hepatocellular damage (serum glutamic oxaloacetic transaminase/glutamic pyruvic transaminase levels); (3) improved histological features of IRI; (4) reduced intrahepatic leukocyte infiltration, as evidenced by decreased expression of P-selectin/intracellular adhesion molecule 1, ED-1/CD3 cells and neutrophils; (5) depressed lymphocyte activation, as evidenced by expression of pro-inflammatory cytokine (TNF-alpha, IL-1beta, IL-6) and chemokine (IP-10, MCP-1, MIP-2) programs; (6) prevented hepatic apoptosis and down-regulated Bax/Bcl-2 ratio. Thus, by modulating leukocyte trafficking and cell activation patterns, treatment of rats with FK330, a specific iNOS inhibitor, prevented liver IRI. These results provide the rationale for novel therapeutic approaches to maximize organ donor pool through the safer use of liver grafts despite prolonged periods of cold ischemia.     

FK409对大鼠肝脏移植缺血再灌注损伤后JAK2/STAT3信号通路的影响

目的 探讨FK409对人鼠肝脏移植缺血再灌注损伤后细胞凋亡及JAK2,STAT3表达的影响.方法雄性SD 大鼠60只,随机分为假于术组、牛理盐水干预组、FK409干预组,采用Kamada's袖套法建立大鼠原位肝移植模型.干预组于新肝开放前分别鼠尾静脉注射FK409 2 mg/kg或等量生理盐水,于24 h后RT-PCR及免疫组织化学方法检测JAK2,STAT3表达水平的变化;利用原位缺口未端标记法(TUNEL法)研究肝细胞凋亡的变化.结果 与生理盐水干预组相比,FK409干预组JAK2,STAT3表达明显减少(P＜0.05);凋亡细胞也减少(P＜0.05).结论 FK409尚能通过抑制与炎性细胞因子及氧化应激有密切关系的JAK2/STAT3信号转导通路显著减轻大鼠肝移植缺血再灌注损伤后组织损伤.     

Selective neutralization of the chemokine TCA3 reduces the increased injury of partial versus whole liver transplants induced by cold preservation

BACKGROUND: Given the shortage of liver donors and the development of techniques for partial liver transplantation, we compared chemokine expression and inflammatory cell infiltration of partial versus whole grafts in a mouse syngeneic liver transplant model. METHODS: Orthotopic liver transplantation, using whole or partial murine liver grafts, was performed following cold preservation in ViaSpan solution for periods of one to eight hours. RESULTS: Partial grafts showed more severe cold ischemia/reperfusion injury and greater inflammatory cell infiltration than whole grafts, and was accompanied by the marked intrahepatic upregulation of multiple chemokines. Quantitative analysis showed that compared with expression in whole grafts harvested after the same period of cold ischemia, partial grafts had eightfold more T-cell activation gene (TCA)-3 (CCL1) chemokine messenger RNA (mRNA) expression (P<0.01) and sixfold more inducible protein (IP)-10 chemokine (CCL10) mRNA expression (P<0.01), as well as increased expression of the chemokine receptors CCR8 (receptor for TCA3) and CXCR3 (receptor for IP-10; P<0.01). Blockade of TCA3 by neutralizing monoclonal antibody significantly decreased intragraft IP-10 expression (P<0.05) but not tumor necrosis factor-alpha or interleukin-6 expression in partial grafts, and significantly decreased cold ischemia/reperfusion injury (P<0.05) and associated neutrophil and T-cell infiltration (P<0.01). CONCLUSIONS: These data demonstrate that the chemokine TCA3/CCL1 is important to the pathogenesis of ischemic injury of experimental partial liver grafts, and that its therapeutic targeting within such grafts can overcome the deleterious effects of prolonged cold preservation and restore liver function to the level achieved using whole liver grafts.     

Carbon monoxide inhalation ameliorates cold ischemia/reperfusion injury after rat liver transplantation

BACKGROUND: Carbon monoxide (CO), a product of heme degradation by heme oxygenase, induces cytoprotection against ischemia/reperfusion (I/R) injury in a variety of organs such as the heart, lung, kidney, and small intestine. We examined whether CO would protect liver grafts against cold I/R injury associated with transplantation. METHODS: Orthotopic liver transplantation (OLT) was performed in syngeneic Lewis rats with 18 hours preservation in cold University of Wisconsin solution. Recipients were exposed to air or CO (100 ppm) for 1 hour before and 24 hours after OLT. Recipients were sacrificed 0.5 to 48 hours post-transplant. RESULTS: CO inhalation significantly decreased serum aspartate aminotransferase and alanine aminotransferase levels and suppressed hepatic necrosis formation and neutrophil accumulation at 6 to 48 hours after OLT, compared with air control. The expressions of tumor necrosis factor alpha, intercellular adhesion molecule 1, and inducible nitric oxide synthase messenger RNA in the liver graft were significantly inhibited in the CO-treated group at 1 hour after reperfusion. Hepatic nuclear factor-kappaB activation did not differ between the groups. CONCLUSIONS: The results demonstrate that exogenous CO treatment suppresses early proinflammatory gene expression and neutrophil infiltration, and efficiently ameliorates hepatic I/R injury. The possible mechanism by which CO protects the liver against cold I/R does not seem to be associated with downregulation of the nuclear factor-kappaB-signaling pathway.     

Cytoprotective and Antiapoptotic Effects of IL-13 in Hepatic Cold Ischemia/Reperfusion Injury Are Heme Oxygenase-1 Dependent

Liver injury caused by ischemia/reperfusion (I/R) insult represents the major problem following orthotopic liver transplantation (OLT). I/R damage has been linked to Th1-like cytokine producers. This study evaluates putative cytoprotective effects/mechanisms of Th2-type IL-13 gene transfer. IL-13 overexpression prevented hepatic insult in a rat model of 24 h cold ischemia followed by OLT, as assessed: (i) profoundly decreased hepatocellular damage (sGOT levels), and ameliorated histological signs of I/R injury (Suzuki criteria), consistent with long-term OLT survival; (ii) prevented hepatic apoptosis (TUNEL stains) and up-regulated expression of antiapoptotic (A20, Bcl-2/Bcl-xl)/antioxidant (HO-1) genes. However, inhibition of HO-1 with tin protoporphyrin reversed cytoprotective/antiapoptotic effects of IL-13. In conclusion, cytoprotection rendered by virally induced IL-13 against hepatic I/R injury in this clinically relevant rat hepatic cold I/R injury model was accomplished via decreased apoptosis and induction of antiapoptotic/antioxidant molecules. HO-1 neutralization studies suggest that HO-1 represents one of putative IL-13 downstream effectors. This study provides the rationale for novel approaches to maximize organ donor pool through the safer use of OLTs despite prolonged periods of cold ischemia.     

药物预处理和缺血预处理对供肝保护作用的比较研究

目的 寻找有效的砬轻供肝缺血再灌注损伤的途径。方法 建立大鼠肝脏原位隔离冷灌注模型模拟整个肝移植过程,对供肝分别作药物预处理和缺血预处理,比较正常肝,预处理供肝,末预处理供肝的ＰＣＮＡ,ＡＳＴ,ＡＬＴ,ＬＤＨ值。结果 与正常肝相比,药物预处理供肝、缺血预处理供肝、未预处理供肝肝损害程度依次加重。结论 预处理确实对供肝缺血再灌注损伤有保护作用;药物预处理的效果可能优于缺血预处理。     

保存不同时间的大鼠部分肝脏移植后的肝细胞再生

目的 探讨保存不同时间的大鼠部分肝脏移植后的肝细胞再生及其可能机制.方法 采用近交系雄性Lewis大鼠为供、受者,按照实验设计分别将供肝于4℃UW液中保存1 h(冷缺血1 h组)、8 h(冷缺血8 h组)和16 h(冷缺血16 h组).然后进行原位肝移植.移植肝恢复血流前,用3-0丝线结扎供肝左侧中央叶、左外叶及尾状叶,保留右侧的肝叶.即可制成大鼠50%体积肝脏(以下简称"半肝")原位移植模型.术后观察各组移植肝的存活情况和肝细胞再生情况;采用逆转录聚合酶链反应测定肝组织中自细胞介素-6(IL-6)和肿瘤坏死因子α(TNF_n)的表达情况;采用Western印迹法检测肝组织中信号传导与转录因子-3(STAT-3)表达情况;采用免疫组织化学染色检测移植肝组织中细胞周期素DI(Cyelin D1)的表达和肝细胞摄取溴脱氧尿核苷(BrdU)情况.结果 各组手术成功率均为100%.与冷缺血1 h组相比,冷缺血8 h组和冷缺血16 h组移植肝组织中TNF-a(F=67.45,P<0.05)和IL-6(F=287.73,P<0.05)的表达明显增加.STAT-3的表达也明显增强.肝移植后24 h.冷缺血8 h组在胞浆和细胞核内均有Cyclin D1的表达.而冷缺血16 h组移植肝组织中未见明显的Cyclin D1表达.移植后24 h.冷缺血16 h组的BrdU染色阳性的肝细胞数无明显增多,而在冷缺血8 h组可见BrdU染色阳性的肝细胞明显增多(t=19.40,P<0.05).结论冷保存一定时限的大鼠部分肝脏在移植后可获得肝细胞再生,此过程可能通过TNF-α/IL,16/sTAT-3/Cyclin D1/DNA合成的途径进行调节;当冷保存时间达16 h后,肝细胞不能对肝脏再生早期信号起反应.     

大鼠小体积肝脏移植后早期肝内细胞因子的变化

目的 研究不同冷缺血条件下大鼠小体积肝移植(30%标准体积)后早期肿瘤坏死因子α(TNF-α)及白细胞介素6(IL-6)的变化,及其与肝脏再生的关系.方法 建立Lewis大鼠30%标准体积的原位肝移植模型.根据供肝在UW液中冷保存时间的不同,将受者分为3组:冷缺血1 h组、冷缺血8 h组和冷缺血16 h组,每组均为20只.观察受者存活情况至术后第7天,并分别在移植肝恢复血流后90 min、1 h、2 h、4 h和7 d收集样本,检测移植肝组织中TNF-α和IL-6表达情况,肝细胞DNA的合成情况,进行移植肝的形态学观察.结果 大鼠肝移植手术成功率均为100%.移植后第7天,冷缺血1 h和8 h组受鼠的存活率均为100%.冷缺血16 h组受鼠的存活率较低,移植后第7天无受鼠存活.冷缺血1 h组TNF-α和IL-6的表达水平较低,冷缺血8 h组和冷缺血16 h组TNF-α和IL-6的表达则高于冷缺血1 h组(F=58.81和F=184.12,P<0.05).冷缺血8 h组和冷缺血16 h组间TNF-α和IL-6的表达的差异无统计学意义.冷缺血1 h组增殖细胞数目明显高于冷缺血8 h组,差异有统计学意义(t=5.59,P<0.05).移植术后24h,冷缺血1 h组移植肝有轻度的组织学损伤;冷缺血8 h组移植肝有轻度的窦状隙扩张和轻度的炎症;冷缺血16 h组移植肝有局部淤血,存在肝细胞崩解和坏死等改变.结论 在小体积肝移植后早期,TNF-α和IL-6的上调表达对肝脏再生有重要意义.不同冷缺血时间的小体积肝脏移植物内存在早期启动肝脏再生的信号.     

Sotrastaurin, a protein kinase C inhibitor, ameliorates ischemia and reperfusion injury in rat orthotopic liver transplantation

Sotraustaurin (STN), a small molecule, targeted protein kinase C (PKC) inhibitor that prevents T-lymphocyte activation via a calcineurin-independent pathway, is currently being tested in Phase II renal and liver transplantation clinical trials. We have documented the key role of activated T cells in the inflammation cascade leading to liver ischemia/reperfusion injury (IRI). This study explores putative cytoprotective functions of STN in a clinically relevant rat model of hepatic cold ischemia followed by orthotopic liver transplantation (OLT). Livers from Sprague-Dawley rats were stored for 30 h at 4°C in UW solution, and then transplanted to syngeneic recipients. STN treatment of liver donors/recipients or recipients only prolonged OLT survival to >90% (vs. 40% in controls), decreased hepatocellular damage and improved histological features of IRI. STN treatment decreased activation of T cells, and diminished macrophage/neutrophil accumulation in OLTs. These beneficial effects were accompanied by diminished apoptosis, NF-κB/ERK signaling, depressed proapoptotic cleaved caspase-3, yet upregulated antiapoptotic Bcl-2/Bcl-xl and hepatic cell proliferation. In vitro, STN decreased PKCθ/IκBα activation and IL-2/IFN-γ production in ConA-stimulated spleen T cells, and diminished TNF-α/IL-1β in macrophage-T cell cocultures. This study documents positive effects of STN on liver IRI in OLT rat model that may translate as an additional benefit of STN in clinical liver transplantation.     

Influence of cold ischemia time on complement activation, neopterin, and cytokine release in liver transplantation

OBJECTIVES: The aim of this study was to determine whether a cold ischemia time (CIT) of >12 hours influences the activation of complement as well as the plasma concentrations of neopterin, interleukin (IL)-6, or IL-8 in orthotopic liver transplantation (OLT). PATIENTS AND METHODS: Eighteen consecutive patients undergoing OLT using a veno-venous bypass technique were divided into 2 groups: duration of CIT >12 hours (group 1; n = 11), and CIT <12 hours (group 2; n = 7). Blood samples were drawn preoperatively, 1 minute before, and 120 minutes after reperfusion. RESULTS: Preoperatively, complement split products, neopterin, IL-6, and IL-8 levels did not differ between the groups. At 120 minutes after reperfusion, the concentrations of C3a, SC5b-9, neopterin, IL-6, and IL-8 were significantly increased in both groups compared with the preoperative values or the levels determined 1 minute before reperfusion (P < .05). Patients in group 1 showed significantly higher IL-8 levels at 120 minutes after reperfusion (P < .05). CONCLUSION: Complement is activated and pro-inflammatory cytokines released after reperfusion in OLT using a veno-venous bypass technique, but only IL-8 plasma levels were influenced by the duration of CIT. Therefore, alterations following prolonged CIT seem to not be complement-mediated.     

Recipient levels and function of von Willebrand factor prior to liver transplantation and its consumption in the course of grafting correlate with hepatocellular damage and outcome.

Von Willebrand factor (vWF) is a major platelet adhesion molecule at sites of vascular injury, such as observed in ischemia/reperfusion injury following orthotopic liver transplantation (OLT). Thirty-three OLT patients were divided into groups with elevated or low markers of hepatocellular damage (high and low-HD). Whole-blood aggregometry was performed to evaluate platelet function. Multimeric analysis was utilized to evaluate functional vWF levels in the course of OLT. Donor and recipient demographics were comparable among groups. Low-HD patients demonstrated better preserved coagulation parameters on POD 1-6 if contrasted to high-HD patients. One year graft survival for the high-HD group was lower than low-HD patients (P = 0.037). Preoperative vWF-dependent platelet aggregation and functional vWF plasma levels correlated directly with alanine transaminase levels early after OLT as did the decrease of functional vWF to reperfusion. In summary, these data suggest that vWF may serve as a significant mediator of platelet recruitment and hepatocellular injury in the graft following reperfusion.     

Ex vivo carbon monoxide prevents cytochrome P450 degradation and ischemia/reperfusion injury of kidney grafts

Renal ischemia/reperfusion injury is a major complication of kidney transplantation. We tested if ex vivo delivery of carbon monoxide (CO) to the kidney would ameliorate the renal injury of cold storage that can complicate renal transplantation. Orthotopic syngeneic kidney transplantation was performed in Lewis rats following 24 h of cold preservation in University of Wisconsin solution equilibrated without or with CO (soluble CO levels about 40 microM). Ischemia/reperfusion injury in control grafts resulted in an early upregulation of inflammatory mediator mRNAs and progressive deterioration of graft function. In contrast, the grafts preserved with CO had significantly less oxidative injury and this was associated with improved recipient survival compared to the control group. Renal injury in the control group showed considerable degradation of cytochrome P450 heme proteins, active heme metabolism and increased detrimental intracellular free heme levels. Kidney grafts preserved in CO-equilibrated solution maintained their cytochrome P450 protein levels, had normal intracellular heme levels and had less lipid peroxidation. Our results show that CO-mediated suppression of injurious heme-derived redox reactions offers protection of kidney grafts from cold ischemia/reperfusion injury.