【作者】 尹辉；

【导师】 龚非力；

【作者基本信息】 华中科技大学 ， 免疫学， 2007， 博士

【摘要】 一、ST2与缺血/再灌注损伤相关缺血/再灌注损伤(I/R, Ischemia and reperfusion)是指缺血缺氧的组织器官重新获得血液供应后,往往并不能使损伤减轻或恢复,反而加重组织器官功能障碍、结构损伤和细胞死亡的现象。在肝脏移植、外伤、休克以及部分肝切除手术过程中,通常会发生短时间肝脏缺血、缺氧。肝脏缺血/再灌注损伤所引发的复杂病理生理学改变包括缺血直接导致的细胞损伤,以及相关炎症信号通路激活所致组织器官失功和破坏。肝脏缺血/再灌注损伤发生机制十分复杂,尚未完全明确,近年来,与组织器官损伤相关的炎症反应引起广泛关注。目前已知,肝脏巨噬细胞(Kupffer细胞)激活后产生ROS,可诱导肝细胞NOS活性上升、活化JNK信号途径、上调炎性细胞因子表达并伴随中性粒细胞局部浸润等,由此促进炎症反应相关的组织细胞损伤。初始细胞损伤导致炎症反应扩大,继而促进组织细胞损伤加重,其确切机制尚未完全明确。近年对此提出新观点:组织细胞起始破坏及炎症信号途径激活,可能与局部缺血组织或细胞间基质损伤所释放(内源性)损伤/危险相关分子模式信号(damage/danger associated molecular pattern,DAMP)有关。天然免疫细胞表面Toll样受体(Toll like receptor, TLR)是脊柱动物识别病原体感染最原始的一种方式,其通过识别、结合特异性分子模式而启动胞内信号转导途径,进而激活核转录因子NF-κB,诱导炎性细胞因子表达和多种生物学效应。TLR在天然免疫和适应性免疫应答间发挥重要的桥梁作用。现已发现,TLR识别的分子模式不仅包括病原微生物(及其产物)所共有的某些非特异性、高度保守的病原相关分子模式(Pathogen associated molecular pattern,PAMP),如脂多糖(LPS)、磷壁酸(LTA)、肽聚糖、细菌DNA、双链RNA等,还包括组织细胞损伤破坏时所释放的一系列内源性“危险信号”,如热休克蛋白(HSP)、氧自由基、核甘酸、神经介质、白介素等。肝脏由实质细胞(肝细胞)和非实质细胞(包括Kupffer细胞、DC、内皮细胞和星状细胞)组成。近年报道,肝细胞和肝脏非实质细胞表面普遍表达低水平TLR4。相对其他TLR,TLR4处于病原微生物感染和无菌性炎症反应的交界面,更易接受细菌内毒素(LPS)和内源性配体信号的刺激。Billiar等证实,肝脏缺血/再灌注过程中,肝脏非实质细胞表面TLR4可识别损伤/坏死细胞所释放的多种内源性配体,如HSP 60/70、纤维蛋白原、纤粘连蛋白、肝磷脂硫酸盐和高迁移率家族蛋白(high-mobility group box-1,HMGB1)等,并在介导肝脏再灌注损伤中发挥重要作用。ST2(又命名为T1、DER4)最初被发现是由小鼠成纤维细胞所分泌,属IL-1受体超家族。st2基因定位于小鼠1号染色体和人类2号染色体并与IL-1R区基因紧密相邻。ST2分子结构类似于IL-1受体,但其不与IL-1家族成员(如IL- 1α、IL- 1β或IL- 1R拮抗剂)结合。st2基因在mRNA转录水平经不同方式剪接修饰,生成(2.7 kb和5kb)两种mRNA序列,翻译后生成相应蛋白分子,即短序列分泌型ST2(可溶性ST2或sST2)和长序列跨膜型ST2(ST2L)。可溶性ST2与跨膜型ST2胞外段序列基本一致,仅在C末端存在9个氨基酸序列差异。可溶性ST2由成纤维细胞分泌,跨膜型ST2表达于肥大细胞和Th2型细胞表面,参与Th2型应答。近年在胃、小肠、结肠等组织发现一种新的剪接体,编码一类新的跨膜型ST2蛋白,但其功能特征有待进一步研究。ST2参与细胞生长调控和胚胎发育,其在造血细胞系中表达并与Toll/IL-1受体结构相似,提示可能参与免疫应答及其调控。应用抗ST2抗体处理BABL/C小鼠,能诱导Th2型应答向Th1型应答偏移,从而抑制利什曼原虫感染;胶原质诱导的小鼠关节炎主要为Th1型应答,经抗ST2抗体处理可加重炎性细胞浸润和关节炎损伤;抗ST2抗体、ST2融合蛋白处理过敏性肺炎、血吸虫卵感染和呼吸道合胞病毒感染等动物模型,以及ST2基因敲除小鼠体内,均发现ST2L可促进Th2型应答,主要表现为特征性嗜酸粒细胞局部浸润和Th2型细胞因子IL-4、IL- 5和IL- 13表达水平上升。Xu等探讨可溶性ST2-IgG融合蛋白对LPS激活巨噬细胞的影响,发现可溶性ST2可下调巨噬细胞所介导炎症反应,显著降低炎性细胞因子TNF-α、IL- 6和IL- 12等分泌,其机制是ST2与细胞表面相应ST2配体(ST2 BP)结合,向胞内传递抗炎信号,进而抑制炎性细胞因子产生;体内实验发现,给予ST2融合蛋白可降低小鼠内毒素休克死亡率。可溶性ST2通过与相应配体结合而下调炎性信号的分子机制尚未明确,但其抗炎作用涉及细胞表面受体识别LPS和相应炎性信号通路。TLR 4是LPS特异性受体,可通过胞内转接蛋白MyD88依赖性和非依赖性途径传递炎性信号,在激活巨噬细胞中发挥关键作用,并参与识别组织细胞损伤/破坏而释放的多种内源性配体。上述研究进展提示:肝脏缺血/再灌注所引发无菌性炎症反应和组织细胞损伤过程中,ST2可能对肝脏Kupffer细胞活性发挥重要调节作用,该效应可能涉及TLR4信号转导途径。本课题研究目标为:克隆小鼠可溶性ST2基因,构建其真核表达载体,制备可溶性ST2-Fc融合蛋白;体外观察sST2-Fc融合蛋白对LPS激活巨噬细胞释放炎性细胞因子的影响;体内转染sST2-Fc真核表达载体,观察sST2-Fc对小鼠肝脏缺血/再灌注损伤的影响,并探讨其机制,为今后应用于临床治疗组织器官缺血/再灌注损伤和相关炎症性疾病提供实验依据。二、小鼠可溶性ST2和人IgG Fc基因的克隆及真核表达载体的构建分别从小鼠脾脏和人外周血单个核细胞提取总RNA。利用RT-PCR技术获得编码小鼠可溶性ST2和人IgG Fc的cDNA,克隆入真核表达载体pcDNA 3.1,构建重组载体pcDNA 3.1- sST2- IgG Fc(psST2-Fc)。经酶切鉴定及测序分析证实,所克隆和构建的sST2-Fc cDNA阅读框及连接部位序列正确,表明小鼠可溶性ST2和人IgG Fc融合基因的重组真核表达质粒构建成功。三、可溶性ST2-Fc融合蛋白的制备及其体外效应的研究1.可溶性ST2-Fc基因表达和鉴定采用Lipofectamine TM 2000将psST2-Fc载体转染CHO细胞,稳定表达可溶性ST2-Fc融合蛋白;采用Western blot、ELISA检测CHO细胞培养上清中所表达sST2-Fc融合蛋白,用人IgG作为标准品对sST2-Fc进行定量检测;采用RT-PCR检测psST2-Fc融合基因mRNA表达。结果显示:转染psST2-Fc的CHO细胞可表达sST2-Fc融合基因mRNA,在约929 bp处呈现一明显条带,与预期结果一致;收集转染psST2-Fc的CHO细胞培养上清液,借助Protein A sepharose CL-4B亲和层析柱纯化sST2-Fc融合蛋白,可与抗小鼠ST2单克隆抗体特异性结合形成一明显条带,其分子量约100 kDa,与预期结果相一致。2. FACS检测sST2-Fc融合蛋白与相应配体结合为检测sST2-Fc融合蛋白与相应配体结合能力,小鼠腹腔巨噬细胞和sST2-Fc融合蛋白作用后,用FITC标记的羊抗人IgG Fc抗体染色。FACS结果显示,巨噬细胞表面表达ST2的特异性配体,并在LPS刺激下表达升高。3. sST2-Fc对巨噬细胞分泌细胞因子的影响采用ELISA检测sST2-Fc融合蛋白对LPS刺激巨噬细胞分泌细胞因子的影响。结果表明,sST2-Fc融合蛋白能明显抑制LPS刺激腹腔巨噬细胞产生TNF-α和IL-6的作用。四、sST2-Fc对肝脏缺血/再灌注损伤保护作用的实验研究建立BALB/C小鼠肝脏缺血/再灌注模型,在预定时间点取材进行检测,同时设立假手术对照组。1. psST2-Fc在小鼠体内表达借助ELISA检测psST2-Fc基因在体内表达水平。psST2-Fc基因转染36小时后,sST2-Fc融合蛋白水平达84.8±11.1 ng/ml,但pcDNA 3.1基因转染对照组未检出sST2-Fc融合蛋白表达。2. sST2-Fc对小鼠肝脏缺血/再灌注损伤的影响与pcDNA 3.1和生理盐水处理组相比,psST2-Fc基因处理组肝脏缺血/再灌注损伤明显改善:血清谷丙转氨酶(ALT)、IL-6和TNF-α水平均明显降低;(HE染色显示),肝细胞水肿变性坏死和肝血窦淤血均明显较轻。3. sST2-Fc抑制肝脏巨噬细胞活性免疫组织化学检测肝脏巨噬细胞表面特异性F4/80抗原表达,分析再灌注6小时后损伤肝组织局部巨噬细胞数量变化。结果发现:sST2-Fc处理组,肝组织F4/80+细胞数量(156±30个/高倍视野)明显低于pcDNA 3.1(193±26个/高倍视野)和生理盐水(189±28个/高倍视野)组,差异有显著性(P < 0.05)。肝脏缺血/再灌注3小时后,采用荧光定量RT-PCR检测肝组织中细胞因子mRNA水平。结果发现:psST2-Fc处理组肝组织中TNF-α和IL- 6 mRNA转录水平显著低于pcDNA 3.1和生理盐水组,差异有显著性(P < 0.05)。4.缺血/再灌注肝脏组织中TLR4 mRNA表达肝脏缺血/再灌注3小时后,采用荧光定量RT-PCR检测肝组织中TLR4 mRNA水平。结果显示:与pcDNA 3.1和生理盐水组相比,psST2-Fc处理组肝组织TLR4 mRNA表达水平明显下降,差异有显著性(P < 0.05)。5.缺血/再灌注肝脏组织中NF-κB活性肝脏缺血/再灌注3小时后,提取肝组织细胞核蛋白,采用凝胶迁移率实验(EMSA)检测NF-κB转录活性。结果发现:psST2-Fc处理组肝组织中NF-κB活性明显低于pcDNA 3.1和生理盐水组。以上研究结果表明:可溶性ST2可直接与巨噬细胞表面相应受体结合,且能抑制LPS刺激巨噬细胞分泌炎性细胞因子的作用;体内转染psST2-Fc能有效表达,并明显降低肝脏缺血/再灌注所致损伤,其机制与抑制巨噬细胞活性及下调TLR4 mRNA表达有关。五、结论1.缺血/再灌注动物模型中,可溶性ST2可有效抑制肝脏巨噬细胞活化和炎性细胞因子TNF-α、IL- 6产生,此效应与其抑制TLR4信号途径及核转录因子NF-κB激活有关。2.转染psST2-Fc基因能明显改善肝脏缺血/再灌注损伤,提示sST2是一种有效的免疫抑制剂,可望在治疗组织器官缺血/再灌注损伤和相关炎症疾病中具有应用前景。更多还原

【Abstract】 1. IntroductionIschemia/reperfusion (I/R) injury is a complicated pathophysiologic process where- by hypoxic organ damage, tissue injury is accentuated following return of blood flow and oxygen delivery to the compromised tissue. Transient episodes of ischemia occur in procedures such as solid organ transplantation, trauma, shock, partial hepatectomy, and diverse surgical procedures, when inflow occlusion or total vascular exclusion is used to minimize blood loss. The pathophysiology of liver I/R injury includes direct cellular damage as the result of ischemic insult as well as delayed dysfunction and le- sion that results from activation of inflammatory pathways. The distal interaction el- ements in the cascade of inflammatory responses resulting in organ damage following hepatic I/R injury have been extensively studied. Activation of Kupffer cells with pr- oduction of reactive oxygen species, up-regulation of the inducible NOS in hepatocy- tes, activation of JNK, up-regualtion proinflammatiory cytokines, and neutrophil acc- umulation have all been identified as contributing events to the inflammation associa- ted damage. The extent to which the initial cellular injury contributes to propagation of the inflammatory response and leads to further tissue damage is poorly understood. Most recent studies show that a key link between the initial damage to cells and the subsequent activation of inflammatory signaling involves release of endogenous dan- ger signals from ischemic cells and disruption of the tissue matrix.TLRs are present on the surface of innate immune cells, including dendritic cells, macrophages, and natural killer cells in vertebrates. TLRs has been found to be the primary form of pattern recognition receptors for the recognition invasion of pathogenic microorganisms, mediating intracellular signal transduction pathways, leading to the activation of transcriptional factors such as NF-κB, and the expression of genes related to inflammatory and immune response. To date, the TLR family at least consists of 11 members, and is found to be an important link between innate immunity and adaptive immunity. Recent evidence suggests that the innate immune system use the TLRs for the recognition of specific molecular patterns that are present in microbial products, such as LPS, LTA, peptidoglycan, bacterial DNA, dsRNA and endogenous danger signals, such as hot shock protein (HSPs), oxygen free radicals (OFR), deoxyribonucleic acid, neurotransimitters, and interleukin too. The liver consists of parenchymal cells (hepatocytes) and nonparenchymal cells (NPC), including Kupffer cells, sinusoidal endothelial cells, stellate cells, and hepatic dendritic cells. Recent studies found that TLR4 is expressed on hepatocytes and NPC, however the levels of TLR4 expression are lower in the liver than other organs.Perhaps more than any of the other TLR family members, TLR4 located on the interface of microbial and sterile inflammation by responding to both bacterial endotoxin and multiple other endogenous ligands. Billiar and his collaborators demonstrated that the NPC, not the hepatocytes, are responsible for recognizing the initial damage including HSPs, fibrinogen, fibronectin, heparin sulfate, high mobility group box 1(HMGB1) from ischemic cells and for activating TLR4-dependent signaling required for I/R- induced injury.ST2 (also known as T1 or DER4) was originally defined in murine fibroblasts as a late response gene induced by serum, and is a member of the interleukin-1 (IL-1) rec- eptor superfamily. ST2 gene is tightly linked to the IL-1R genes region on mouse chr- omosome 1 and human chromosome 2. Despite its similarity to the IL-1R, ST2 does not bind IL-1α, IL- 1β, or IL- 1R antagonist. In the mouse, differential mRNA proce- ssing within the ST2 gene produces two mRNAs of 2.7 Kb and 5 Kb, corresponding to shorter secreted form (soluble ST2 or sST2) and longer, membrane anchored form (ST2L) of the protein. Hence, sST2 is identical with the extracelluar region of ST2L except for an additional nine amino acids, which are present at the C terminus of the molecule. sST2 is expressed in embryonic tissues, mammary tumors and fibroblasts, while ST2L expressed on mast cells and on T helper 2 (Th2) cells but not on T helper 1 (Th1) cells. Recently, another alternatively spliced transcript that is expressed in the stomach, small intestine, and colon, and encodes a novel membrane form of ST2 has been identified in humans. However, its functional role remains to be identified. In addition to the proposed involvement of ST2 in cell growth regulation and embryoge- nesis, the presence of ST2 in hematopoetic cell lines and its homology with the mem- bers of Toll/IL-1 receptor family indicates its potential functional role in immune res- ponses. Treatment with anti-ST2 antibody could induce resistance to L.major infecti- on in the susceptible BABL/C mouse by swithching a detrimental Th2 to a protective Th1 response. However, Anti-ST2 antibody pretreatment exacerbated murine collag- en-induced arthritis (CIA), in which Th1 responses predominate within rheumatoid arthritis synovial T cell subsets. In the conditions of allergic airway inflammation and infection with Shistosoma mansoni eggs or respiratory syncytial virus, anti-ST2 anti- bodies, ST2 fusion proteins or ST2-deficient mice were used to show that ST2L is re- quired for development of effective Th2 responses, characterised by eosinophil recru- itment and production of proinflammatory cytokines IL- 4, IL- 5, and IL-13.Basis on the study of the influence of soluble ST2-IgG fusion protein on LPS res- ponses of mouse macrophages, Xu and his collaborators found that soluble ST2 play an important role in down-regulation macrophage proinflammatory activity. Treatm- ent with ST2 fusion protein before LPS stimulation markedly suppressed the produc- tion of the proinflammatory cytokines TNF-α, IL- 6 and IL-12 from macrophages. Moreover, administration of sST2 significantly reduced LPS-mediated mortality. Re- cent studies showed that through the ST2 binding protein, ST2 was able to directly bind to the surface of murine macrophages and subsequently inhibited the production of inflammatory cytokines. The molecular mechanism of this down-regulation rema- ins to be investigated, however, it appears likely that ST2 serves as a negative regul- ation factor that acts at the cell surface. Among the well-known Toll-like receptors (TLRs), TLR4 has been found to accept LPS as a ligand and subsequently triggers LPS-mediated signaling. Moreover, it also has been found that TLR4 participates in the recognition of endogenous ligands from damaged/ stressed cells, such as heat sh- ock proteins, hyaluronic acid, heparin sulfate, and high-mobility group box 1. Increa- sing evidence shows that ischemia/reperfusion-induced liver inflammation and hepat- ocellular damage is partially dependent on TLR4 signaling.These above findings suggested that sST2 may also be an important negative regu- lation factor of sterile inflammation and cell injury in warm hepatic I/R and the action of sST2 may be also related to TLR4 signaling. To test this hypothesis, we construct- ed a recombinant eukaryotic expression plasmid encoding murine sST2- human IgG1 Fc (sST2-Fc) fusion protein, and investigated its effect on hepatic I/R injury. We de- monstrated here that the expression of this plasmid in vivo effectively prevents hepa- tocellular damage and suppresses the activation of inflammatory cascades. Furtherm- ore, we found that the protection of sST2-Fc in hepatic I/R was also involved in dow- nregulation of TLR4 mRNA expression. These studies may provide a new route for the therapy of ischemic liver injury and other clinical setting involved inflammation diseases.2. Cloning of mouse soluble ST2 and human IgG1αFc gene, and construction of expression vectorThe cDNA of mouse soluble ST2 was reverse transcribed from the total RNA of mouse spleen by RT-PCR, and human IgG1αFc gene cDNA was reverse transcribed from the total RNA of human PBMC by RT-PCR too. The fragment of hIg gene was cloned into the eukaryotic expression system pcDNA 3.1 to construct pcDNA 3.1-Fc vector, then the fragment of soluble ST2 gene was inserted into pcDNA 3.1-Fc vector upstream hIg Fc to construct eukaryotic expression vector pcDNA 3.1- sST2- Fc (psST2- Fc). The recombinant plasmid psST2-Fc is identified by restriction endoniclease digestion and sequence analysis.3. Preparation and biological function of soluble ST2-Fc fusion proteinThe expression and identification of soluble ST2-Fc fusion proteinBy using LipofectamineTM 2000, psST2-Fc plasmid was transfected into CHO cells, and the expression of soluble sST2-Fc fusion protein in CHO cells was confirmed by ELISA and Western blot analysis. The relative amount of soluble ST2-Fc was determined with ELISA. mRNA for recombinant sST2-Fc expression was analyzed by RT-PCR. The soluble ST2-Fc fusion protein from the cultural supernatants was purified by protein A-Sepharose affinity chromatography. The results showed that CHO cells transfected with psST2-Fc secreted sST2-Fc fusion protein into cultural medium. Western blot analysis using a monoclonal antibody specific for ST2 detected a 100 kDa protein, which is in agreement with the recombinant molecular weight of sST2 and hIg Fc. A 929 bp fragment was amplified from the total RNA of psST2-Fc transfected CHO cells by RT-PCR corresponding to anticipated size. The fusion protein display a single band at 100 kDa in SDS-PAGE analysis after purified by protein A Sepharose 4B affinity chromatography. The results showed that the quality of soluble ST2-Fc fusion is suitable for further experiment.Soluble ST2 binds to the surface of peritoneal macrophagesUsing sST2-Fc fusion protein, we analyzed the ability of peritoneal macrophages to bind ST2. The results show that cells incubated with sST2-Fc were markedly stained with anti-hIgG. However, cells incubated with normal hIgG had a staining pattern identical with the isotype control. Importanly, this binding activity was significantly enhanced by overnight exposure to peritoneal macrophages to LPS. Soluble ST2-Fc protein inhibits TNF-a and IL- 6 production from LPS- indu- ced macrophagesBasis on binding of sST2-Fc to peritoneal macrophages was upregulated by LPS tr- eatment, we investigated the reciprocal involvement of sST2-Fc in regulation of the LPS response. By using ELISA, we found that production of TNF-αand IL- 6 in res- pond to LPS in the peritoneal macrophages was markedly suppressed by sST2-Fc tre- atment.4. The warm hepatic I/R injury was attenuated by pretreatment with soluble ST2-FcThe expression of psST2-Fc in vivoBy using a specific ELISA, the concentration of serum sST2-Fc protein was analy- zed in pcDNA 3.1-treated mice and psST2-Fc- transfected mice. Results show that sST2-Fc fusion protein was not detected in non-transfected mice, nor detected in pcDNA3.1- treated mice. However, the serum from sST2-Fc-transfected mice showed a significant increase in the sST2-Fc level (84.8±11.1 ng/ml) at 36 h after psST2-Fc transfection.The effect of psST2-Fc on warm hepatic I/R injurySerum ALT levels and necrotic areas in liver tissue were measured on BALB/C mice subjected to 60 min of liver ischemia and 6 h of reperfusion. Results show that serum ALT, TNF-α, and IL- 6 levels were significantly increased in control mice treated with pcDNA 3.1 or saline underwent ischemia/reperfusion injury. In contrast, mice pretreated with psST2-Fc exhibited lower levels of serum ALT compared with control animals subjected to liver I/R. Liver histological examination was consistent with the serum ALT estimation of liver damage.In vivo expression of psST2-Fc inhibits the activation of Kupffer cells To determine the effect of sST2 on the activation of Kupffer cells in the sinusoidal space of liver after I/R, we first observed its influence on the infiltration of Kupffer cells. By staining Kupffer cells with F4/80 on liver sections, results show that the nu- mber of F4/80+ Cells in psST2-Fc- treated group (156±30 positive cells per high power field ) was significantly reduced as compared with that in pcDNA3.1- treated group (193±26) or saline group (189±28) (P < 0.05). By using real-time RT-PCR, we found that compared with pcDNA 3.1 and salined-treated animals, the expression of TNF-α, IL- 6 was significantly suppressed in treatment with psST2-Fc.TLR4 levels were suppressed in the I/R liver by sST2TLR4 mRNA levels were examined by using real-time RT-PCR in liver tissues after I/R. Compared with sham-treated animals, liver I/R in pcDNA 3.1 or saline- treated animals resulted in an enhanced expression of TLR4 mRNA 3 h after reper- fusion. However, psST2-Fc- treated mice showed minimal increase in TLR4 mRNA levels compared with sham-treated mice after I/R.sST2 modulates inflammatory signaling pathwayTo investigate the possible molecular mechanism of sST2 to down-regulate the gene expression of TNF- a and IL- 6, levels of NF-κB activation were measured by EMSA. We found that NF-κB DNA-binding activity was increased in the ischemic liver 3 h after reperfusion in pcDNA 3.1 or saline-treated control mice, when compa- red with sham- treated mice. Mice pretreated with psST2-Fc exhibited less NF-κB DNA-binding activity.All these results show that soluble ST2 could directly bind to the surface of macro- phages, and then represses the production of proinflammatory cytokine from LPS- induced macrophages. Moreover, we successfully attenuated hepatic reperfusion in- jury after short term warm ischemia by in vivo transfection of plasmid encoding sST2 gene. The protective effect is associated with inactivation of Kupffer cells and the pr- oduction of TNF- a and IL- 6, possibly through the down-regulation of TLR4 expres- sion.5. ConclusionsST2 effectively inhibit the activation of Kupffer cells and the production of TNF-a and IL- 6, possibly through the down-regulation of TLR4 expression. Furthermore, the hepatic reperfusion injury after short term warm ischemia was significantly atten- uated by in vivo transfection of plasmid encoding sST2 gene. It was suggested that pretreatment with sST2 may be effective in settings of ischemic liver injury to mini- mize organ damage and may be useful in other clinical settings related to inflamma- tion diseases.更多还原