Fibrinogen-like protein 2/fibroleukin prothrombinase contributes to tumor hypercoagulability via IL-2 and IFN-γ

AIM： To examine the role of Fibrinogen-like protein 2 （fgl2）/fibroleukin in tumor development. Fgl2 has been reported to play a vital role in the pathogenesis in MHV-3 （mouse hepatitis virus） induced fulminant and severe hepatitis, spontaneous abortion, allo- and xenograft rejection by mediating ＂immune coagulation＂.METHODS： Tumor tissues from 133 patients with six types of distinct cancers and the animal tumor tissues from human hepatocellular carcinoma （HCC） model on nude mice （established from high metastasis HCC cell line MHCC97LM6） were obtained. RESULTS： HfgI2 was detected in tumor tissues from 127 out of 133 patients as well as tumor tissues collected from human HCC nude mice. Hfgl2 was highly expressed both in cancer cells and interstitial inflammatory cells including macrophages, NK cells, and CD8^＋ T lymphocytes and vascular endothelial cells. HfgI2 mRNA was localized in cells that expressed hfgI2 protein. Fibrin （nogen） colocalization with hfgl2 expression was determined by dual immunohistochemical staining. In vitro, IL-2 and IFN-γ, increased hfgl2 mRNA by 10-100 folds and protein expression in both THP-1 and HUVEC cell lines. One-stage clotting assays demonstrated that THP-1 and HUVEC cells expressing hfgl2 had increased procoagulant activity following cytokines stimulation. CONCLUSION： The hfgI2 contributes to the hypercoagulability in cancer and may induce tumor angiogenesis and metastasis via cytokine induction.

Fibrinogen-like protein 2 expression correlates with microthrombosis in rats with type 2 diabetic nephropathy

Fibrinogen-like protein 2 （fgl2）, a novel prothrombinase, is involved in microthrombosis. We examined fgl2 expression in the glomerular and tubulointerstitial capillaries and its correlation with microthromsis in rats with streptozocin-induced type 2 diabetic nephropathy. Our RT-PCR and immunoblotting analysis showed that fgl2 mRNA and protein levels were increased in microvascular endothelial cells of the glomeruli and renal interstitia at week 19 and became significantly elevated with the development of diabetic nephropathy （P 〈 0.01）. Fgl2 was not or only weakly expressed in the renal tissues of normal rats. Furthermore, a direct significant correlation （r = 0.543, P 〈 0.01） was found between fgl2 expression and microthrombotic capillaries in the renal tissues. Enzyme linked immunosorbent assays （ELISA） additionally showed that circulating TNF-α levels in rats with type 2 diabetes were significantly elevated and closely correlated with fgl2 expression （r = 0.871, P 〈 0.01）. Our results suggest that fgl2 may activate renal microthrombosis, thus contributing to glomerular hypertension and renal ischemia.

Correlation of fibrinogen-like protein 2 with progression of acute pancreatitis in rats

AIM: To examine fibrinogen-like protein 2 (fgl2) expression during taurocholate-induced acute pancreatitis progression in rats and its correlation with pancreatic injury severity. METHODS: Forty-eight male Sprague-Dawley rats were randomly divided into the severe acute pancreatitis (SAP) group (n = 24) and the sham operation (SO) group (n = 24). Sodium taurocholate (4% at doses of 1 mL/kg body weight) was retrogradely injected into the biliopancreatic ducts of the rats to induce SAP. Pancreatic tissues were prepared immediately after sacrifice. At the time of sacrifice, blood was obtained for determination of serum amylase activity and isolation of peripheral blood mononuclear cells (PBMCs). Pancreatic tissue specimens were obtained for routine light microscopy including hematoxylin and eosin staining, and the severity of pancreatic injury was evaluated 1, 4 and 8 h after induction. Expression of fgl2 mRNA was measured in the pancreas and PBMCs using reverse transcription polymerase chain reaction. Expression of fgl2 protein was evaluated in pancreatic tissues using Western blotting and immunohistochemical staining. Masson staining was also performed to observe microthrombosis. RESULTS: At each time point, levels of fgl2 mRNAs in pancreatic tissues and PBMCs were higher (P < 0.05) in the SAP group than in the SO group. For pancreatic tissue in SAP vs SO, the levels were: after 1 h, 3.911 ± 1.277 vs 1.000 ± 0.673; after 4 h, 9.850 ± 3.095 vs 1.136 ± 0.609; and after 8 h, 12.870 ± 3.046 vs 1.177 ± 0.458. For PBMCs in SAP vs SO, the levels were: after 1 h, 2.678 ± 1.509 vs 1.000 ± 0.965; after 4 h, 6.922 ± 1.984 vs 1.051 ± 0.781; and after 8 h, 13.533 ± 6.575 vs 1.306 ± 1.179. Levels of fgl2 protein expression as determined by Western blotting and immunohistochemical staining were markedly up-regulated (P < 0.001) in the SAP group compared with those in the SO group. For Western blotting in SAP vs SO, the results were: after 1 h, 2.183 ± 0.115 vs 1.110 ± 0.158; after 4 h, 2.697 ± 0.090 vs 0.947 ± 0.361; and after 8 h, 3.258 ± 0.094 vs 1.208 ± 0.082. For immunohistochemical staining in SAP vs SO, the results were: after 1 h, 1.793 ± 0.463 vs 0.808 ± 0.252; after 4 h, 4.535 ± 0.550 vs 0.871 ± 0.318; and after 8 h, 6.071 ± 0.941 vs 1.020 ± 0.406. Moreover, we observed a positive correlation in the pancreas (r = 0.852, P < 0.001) and PBMCs (r = 0.735, P < 0.001) between fgl2 expression and the severity of pancreatic injury. Masson staining showed that microthrombosis (%) in rats with SAP was increased (P < 0.001) compared with that in the SO group and it was closely correlated with fgl2 expression in the pancreas (r = 0.842, P < 0.001). For Masson staining in SAP vs SO, the results were: after 1 h, 26.880 ± 9.031 vs 8.630 ± 3.739; after 4 h, 53.750 ± 19.039 vs 8.500 ± 4.472; and after 8 h, 80.250 ± 12.915 vs 10.630 ± 7.003.CONCLUSION: Microthrombosis due to fgl2 overexpression contributes to pancreatic impairment in rats with SAP, and fgl2 level may serve as a biomarker during early stages of disease.

Fibrinogen-like protein 2 deficiency inhibits virus-induced fulminant hepatitis through abrogating inflammatory macrophage activation

BACKGROUND Heterogeneous macrophages play an important role in multiple liver diseases,including viral fulminant hepatitis(VFH).Fibrinogen-like protein 2(FGL2)is expressed on macrophages and regulates VFH pathogenesis;however,the underlying mechanism remains unclear.AIM To explore how FGL2 regulates macrophage function and subsequent liver injury during VFH.METHODS Murine hepatitis virus strain 3(MHV-3)was used to induce VFH in FGL2-deficient(Fgl2-/-)and wild-type(WT)mice.The dynamic constitution of hepatic macrophages was examined.Adoptive transfer of Fgl2-/-or WT bone marrowderived macrophages(BMDMs)into WT recipients with macrophages depleted prior to infection was carried out and the consequent degree of liver damage was compared.The signaling cascades that may be regulated by FGL2 were detected in macrophages.RESULTS Following MHV-3 infection,hepatic macrophages were largely replenished by proinflammatory monocyte-derived macrophages(MoMFs),which expressed high levels of FGL2.In Fgl2-/-mice,the number of infiltrating inflammatory MoMFs was reduced compared with that in WT mice after viral infection.Macrophage depletion ameliorated liver damage in WT mice and further alleviated liver damage in Fgl2-/-mice.Adoptive transfer of Fgl2-/-BMDMs into macrophage-removed recipients significantly reduced the degree of liver damage.Inhibition of monocyte infiltration also significantly ameliorated liver damage.Functionally,Fgl2 deletion impaired macrophage phagocytosis and the antigen presentation potential and attenuated the proinflammatory phenotype.At the molecular level,FGL2 deficiency impaired IRF3,IRF7,and p38 phosphorylation,along with NF-κB activation in BMDMs in response to viral infection.CONCLUSION Infiltrated MoMFs represent a major source of hepatic inflammation during VFH progression,and FGL2 expression on MoMFs maintains the proinflammatory phenotype via p38-dependent positive feedback,contributing to VFH pathogenesis.

Overexpression of fibrinogen-like protein 2 protects against T cell-induced colitis

AIMTo determine the effect of overexpression of fibrinogen-like protein 2 (FGL2) on regulatory T cell (Treg) and effector T (Teff) cell function on T cell-induced colitis in Rag1-/- mice.METHODSTreg and Teff cells from fgl2-/-, fgl2+/+, and fgl2Tg mice were purified by FACS. They were studied in vitro for immunosuppressive activity and cell proliferation and in vivo for their effects on the development and prevention of T cell-induced colitis in Rag1-/- mice.RESULTSIn vitro, fgl2Tg Treg had enhanced immunosuppressive activity, and fgl2Tg Teff had reduced proliferation to alloantigen stimulation. Transfer of Teff from C57Bl/6J mice (fgl2+/+) into Rag1-/- mice produced both clinical and histologic colitis with dense infiltrates of CD3+ T cells, crypt abscesses and loss of goblet cells. Fgl2Tg Treg prevented the development of T cell-induced colitis, whereas fgl2+/+ and fgl2-/- Treg were only partially protective. In mice that received fgl2Tg Treg, the ratio of Foxp3+ to CD3+ cells was increased both in the colon and in mesenteric lymph nodes, and Teff cell proliferation as determined by staining with Ki67 was reduced. Teff cells from fgl2Tg mice did not produce colitis.CONCLUSIONHere we show that fgl2Tg Teff are hypoproliferative and do not induce colitis. We further demonstrate that fgl2Tg Treg prevent colitis in contrast to fgl2+/+ Treg, which were only partially protective. These studies collectively provide a rationale for exploring the use of FGL2 or Treg expressing high levels of FGL2 in the treatment of inflammatory bowel disease.

Molecular cloning of promoter in human fibrinogenlike protein 2 (hfgl2) gene and functional analysis of its sequence

The aim of this study is to investigate the important regulative elements region which plays an important role on the activation of transcription exerted by the 5' noncoding region of hfgl2 gene in response to HBc and HBx. A series of promoter luciferase report plasmids, in which the hfgl2 gene has been deleted of the 5' and retained the common 3', were constructed. All the plasmids constructed were subjected to electrophoretic analysis and DNA sequencing. A eukaryotic construct expressing HBc or HBx, a luciferase reporter construct containing hfgl2 promoter and aβ-galactosidase (β-gal) plasmid were co-transfected into Chinese hamster ovary (CHO) cells and hepG2 cells, respectively. Luciferase report plasmids containing hfgl2 promoter were successfully constructed, and a serial assays of deletion of hfgl2 gene promoter showed that a strong regulatory region from -817 to -467 (relative to the transcription start site) was responsible for transcription and expression regulation of hfgl2 gene. The important regulative elements region in the promoter of hfgl2 gene was in response to HBc and HBx. which contributes to further pursuit of cis-acting elements and transcriptional factors involved in the transcription of hfgl2 gene.

FGL2在肾透明细胞癌中的表达及其临床意义

目的探讨纤维蛋白原样蛋白2(FGL2)在肾透明细胞癌(ccRCC)中的表达及临床意义。方法采用免疫组织化学法检测103例ccRCC患者肿瘤组织及40例癌旁组织中FGL2的表达,分析FGL2的表达与患者临床病理参数及预后的关系。结果FGL2在肾癌组织中呈阳性表达,高表达率明显高于癌旁组织,差异具有统计学意义(62.1%vs.0.0%,χ~2=44.990,P<0.01);FGL2的表达与肿瘤大小(P=0.039)、T分期(P=0.049)、TNM临床分期(P=0.043)显著相关;高表达FGL2患者的总体生存期(OS)及无病生存期(DFS)短于低表达患者(P<0.05);在早期患者(Ⅰ~Ⅱ期)中同样观察到高表达FGL2者的OS及DFS短于低表达患者(P<0.05)。单因素及多因素COX回归分析显示FGL2是患者预后的独立危险因素。结论 FGL2与肾癌的发生发展密切相关,癌组织中FGL2高水平表达提示不良预后,有可能作为肾癌患者判断预后的一种生物标记物,对肾癌提供新的治疗靶点。

Fgl2-shRNA基因沉默对糖尿病大鼠心功能的改善及心肌病理形态变化

目的探讨慢病毒介导的纤维介素(fgl2)基因沉默对糖尿病(DM)大鼠心功能的影响及其在心肌组织中的表达。方法雄性SD大鼠腹腔注射STZ建立DM模型,随机分组为fgl2基因沉默组、GFP空载体组、DM模型组(DM组),基因沉默及GFP空载体组分别尾静脉注射慢病毒载体1×109 IU,DM组注射生理盐水;另设对照组(各组8只)。14周后超声检测左室射血分数(LVEF)、左室短轴缩短率(即缩短分数,FS)、心率(HR)等,心肌组织进行HE染色观察病理形态及免疫组化染色检测fgl2表达。结果 DM组大鼠LVEF、FS降低,HR减少;HE染色示心肌纤维排列紊乱、纵横纹模糊、部分区域变性等;免疫组化fgl2染色示微血管内及周围大量棕黄色絮状染色。fgl2基因沉默组LVEF、FS、HR较DM组提高,差异有统计学意义(P<0.05);病理形态学表现为心肌纤维排列稍紊乱;免疫组化结果显示微血管内少量棕黄色絮状染色,较DM组明显减少,灰度值差异有统计学意义(P<0.05)。结论 Fgl2基因沉默下调DM大鼠心肌fgl2表达,改善病理形态,抑制心室重构,保护心脏功能。

Expression and Significance of fgl2 Prothrombinase in Cardiac Microvascular Endothelial Cells of Rats with Type 2 Diabetes

Microthrombosis may be involved in the pathogenesis of cardiac microangiopathy due to diabetes.Recent studies have shown that fibrinogen-like protein 2 (fgl2) plays a pivotal role in microthrombosis in viral hepatitis, acute vascular xenograft rejection and cytokine-induced fetal loss syndrome.The current study was designed to examine the expression of fgl2 in microvascular endothelial cells and investigate the effects of microthrombi due to fgl2 on cardiac function and structure in rats with type 2 diabetes.Following induction of type 2 diabetes, 24 rats were observed dynamically.Fgl2 expression and related cardiac microthrombosis were examined.Local or circulating TNF-α was measured.Coronary flow (CF) per min was calculated as an index of cardiac microcirculation.Cardiac function and morphology were evaluated.It was found that Fgl2 was highly expressed in cardiac microvascular endothelial cells of rats with type 2 diabetes, which was promoted by local or circulating TNF-α.The Fgl2 expression was associated with cardiac hyaline microthrombosis.In parallel with the fgl2 expression, CF per min, cardiac diastolic or systolic function and cardiac morphology were aggravated to some extent.It was concluded that in rats with type 2 diabetes, microthrombosis due to fgl2 contributes to the impairment of cardiac diastolic or systolic function and morphological changes.

Inhibitory Function of Tregs via Soluble FGL2 in Chronic Hepatitis B

CD4 + CD25 + CD127 dim/regulatory T cells(Tregs) have been implicated in suppressing T cell immune responses to hepatitis B virus(HBV),but the inhibition mechanism has not being clear yet.This study investigated the effects of soluble FGL2(sFGL2) secreted by Tregs on immune suppression in chronic HBV-infected patients.We verified that sFGL2 protein and mRNA were highly expressed in Tregs.The separated Tregs by using magnetic beads from peripheral blood mononuclear cells(PBMCs) in 20 patients with chronic hepatitis B were co-cultured with PBMCs at a ratio of 1:3 with anti-CD3 stimulating antibody or FGL2 blocking antibody.The proliferation index of CD8 + T cells after blocking FGL2 was higher than that in blank group(3.58±0.18 vs.3.28±0.17,P=0.034) in 18 of 20 samples,and lower than that in CD3 stimulation group(3.82±0.19,P=0.026) in 16 of 20 samples.The IFN-γ secreted in the mixed culture in the absence of Tregs was higher than that in the culture in the presence of Tregs,but it could be abolished by FGL2 blocking antibody.These results suggest that sFGL2 protein secreted by Tregs suppresses the proliferation and function of CD8 + T cells in chronic hepatitis B.

纤维介素蛋白2在小鼠自身免疫性肝炎中的作用分析

目的:探讨可溶性纤维介素蛋白2(soluble fgl2,sfgl2)在小鼠自身免疫性肝炎中的作用。方法:将S-100肝抗原与弗氏完全佐剂经腹腔注入到C57BL/6小鼠体内。通过肝脏病理改变和血清ALT和AST水平观察肝脏的损伤程度。用免疫组织化学方法检测肝脏和脾脏组织中纤维素介素蛋白2(fgl2)的表达;免疫印迹方法检测脾脏混合淋巴细胞培养的上清液和细胞中fgl2的表达;免疫组化双染检测小鼠肝脏中fgl2与纤维蛋白的表达,肝脏连续切片中用免疫组化法分别检测fgl2与纤维蛋白的表达。结果:ALT和AST明显升高,肝脏组织中可见大量炎性细胞浸润和坏死形成。免疫组化观测模型组肝脏非实质细胞和脾脏中有fgl2的明显高表达。Western-blot方法发现脾脏淋巴细胞培养的上清液中有fgl2的表达,而沉淀的细胞则没有;免疫组化双染观测到fgl2与纤维蛋白的沉积无关,在连续切片同一部位中,只有fgl2的表达而没有纤维蛋白的表达。结论:Sfgl2是由脾脏的T淋巴细胞所分泌的,在肝抗原诱导的自身免疫性肝炎小鼠模型中发挥了重要的作用。

Expression of Prothrombinase/fibroleukin Gene fg12 in Lung Impairment in a Murine Severe Acute Respiratory Syndrome Model

To evaluate the role of murine fibrinogen like protein 2 (mfgl2) /fibroleukin in lung impairment in Severe acute respiratory syndrome (SARS), a murine SARS model induced by Murine hepatitis virus strain 3 (MHV-3) through trachea was established. Impressively, all the animals developed interstitial pneumonia with extensive hyaline membranes formation within alveoli, and presence of micro-vascular thrombosis in the pulmonary vessels. MHV-3 nucleocapsid gene transcripts were identified in multiple organs including lungs, spleen etc. As a representative proinflammatory gene, mfgl2 prothrombinase expression was evident in terminal and respiratory bronchioles, alveolar epithelia and infiltrated cells in the lungs associated with fibrin deposition and micro-vascular thrombosis. In summary, the established murine SARS model could mimic the pathologic characteristics of lungs in patients with SARS. Besides the physical damages due to virus replication in organs, the up-regulation of novel gene mfgl2 in lungs may play a vital role in the development of SARS associated lung damage.

Roles of Regulatory T Cells in Pathogenesis of Endometriosis

Numerous studies have shown aberrant immune cell function in endometriosis,including T cells,B cells,natural killer cells,and macrophages(MΦ).These alterations are thought to be induced by various mechanisms that promote the disease.Regulatory T cells(Tregs)may account for a decreased ability of newly recruited leukocytes to initiate effective immune responses against viable endometrial fragments,permitting their survival.Tregs differentiate during the development of endometriosis,which confer immunosuppression or play other roles in disease progression.In this review,we provide an overview of the regulation and roles of Tregs in endometriosis.These data provide further scientific evidence for the altered immune response in endometriosis,which could be a potential target in the treatment of endometriosis.This review could create new diagnostic strategies and effective immune-targeted therapies for this highly prevalent disease.Recent progress in the field indicates that these goals may be achieved in the future.