PubMed Health⌕ Search

Biomedical subjects

Qin Ning

Publications and source records attributed to Qin Ning.

At least 19 recordsLinked to original sources
PubMed2006

Cytokine-induced hepatic apoptosis is dependent on FGL2/fibroleukin: the role of Sp1/Sp3 and STAT1/PU.1 composite cis elements.

Previous studies from our laboratory have shown that fulminant hepatitis caused by the mouse hepatitis virus, MHV-3, is dependent on production of the novel immune coagulant fgl2/fibroleukin. In this study, we investigate the role of IFN-gamma and TNF-alpha in the induction of fgl2 expression and fgl2-dependent hepatic apoptosis. Infusion of IFN-gamma in combination with TNF-alpha through the portal vein of fgl2+/+ mice led to widespread hepatic apoptosis and fibrin deposition. Livers from fgl2-/- mice were normal, although strong expression of the fgl2 knockout reporter gene Lac Z was seen in both resident hepatic macrophages and endothelial cells. In vitro, IFN-gamma and TNF-alpha induced fgl2 expression in a macrophage and endothelial cell-specific manner. In macrophages (peritoneal and RAW 264.7 cells), IFN-gamma, but not IFN-alpha, LPS, TNF-alpha, or IL-1 induced fgl2 mRNA transcription and protein expression, while in endothelial cells TNF-alpha, but not IFN-gamma, induced fgl2 transcription. In addition, while TNF-alpha enhanced IFN-gamma-induced macrophage fgl2 transcription, IFN-gamma also enhanced TNF-alpha-induced endothelial cell fgl2 transcription. The induction of fgl2 by IFN-gamma in macrophages involved a STAT1-dependent pathway, involving the composite cis elements Sp1/Sp3 and GAS/PU.1. The latter interacted with IFN-gamma-dependent Sp1/Sp3, STAT1, and the ETS family of transcription factors member PU.1. The interaction of PU.1 with the IFN-gamma-activated sequence/ETS family of transcription factors site determined the macrophage-specific induction of fgl2 by IFN-gamma. Overall, this study demonstrates that IFN-gamma and TNF-alpha induce hepatocyte apoptosis in vivo, which is dependent on induction of fgl2, and defines the molecular basis of transcription of fgl2 in vitro.

Animals↗
PubMed2006

Novel mfgl2 antisense plasmid inhibits murine fgl2 expression and ameliorates murine hepatitis virus type 3-induced fulminant hepatitis in BALB/cJ mice.

Our previous reports, both experimental and human studies, have shown the importance of fibrinogen-like protein-2 (fgl2) prothrombinase in the development of fulminant viral hepatitis, a disease with a mortality of more than 80% in cases lacking immediate organ transplantation. To interfere with this potentially effective target, a 322-bp mouse fgl2 (mfgl2) antisense plasmid complementary to the exon 1 sequence of the gene, including the translation initiation site AUG, was successfully constructed. A dose-dependent inhibitory effect on mfgl2 expression by mfgl2 antisense plasmid was observed in interferon-gamma-treated RAW 264.7 cells. On hydrodynamic delivery, mfgl2 antisense plasmid significantly reduced mfgl2 expression in vivo; markedly ameliorated inflammatory cell infiltration, fibrin deposition, and hepatocyte necrosis; prolonged the survival time period; and elevated the survival rate among BALB/cJ mice with murine hepatitis virus type 3-induced fulminant hepatitis. This study may provide an effective way to interfere with the potential therapeutic target fgl2 gene for fulminant viral hepatitis and other diseases with similar pathological characteristics of microcirculation disorders, including acute rejection of xeno- or allograft transplantation and fetal loss syndrome, in which studies show fgl2 plays an important role.

Animals↗
PubMed2006

CXCR2 blockade reduces radical formation in hyperoxia-exposed newborn rat lung.

Inflammation contributes greatly to the pathogenesis of bronchopulmonary dysplasia. In previous studies, we showed that blocking neutrophil influx by treatment with SB265610, a selective CXCR2 antagonist, could partly reduce superoxide accumulation and preserve alveolar development in 60% O(2)-exposed newborn rats. The purpose of this study was to further investigate the role of neutrophils in the formation of reactive oxygen and nitrogen species mediating hyperoxia-impaired lung development. We found that hydroxyl radical formation and lipid peroxidation in rat lungs were significantly increased during 60% O(2) exposure. These increases were attenuated by the administration of SB265610. In addition, SB265610 largely inhibited protein nitration induced by hyperoxia. SB265610 partly prevented the hyperoxia-enhanced bronchoalveolar lavage (BAL) protein content in 60% O(2)-exposed animals. Our results demonstrate that neutrophils have a pivotal role in hydroxyl radical formation, lipid peroxidation and protein nitration. Taken together with our previous studies, the present findings show that blocking neutrophil influx protects alveolar development and improves lung function in part by preventing reactive oxygen/nitrogen species accumulation.

Animals↗
PubMed2006

[Construction of the p-mfgl2shRNA and its effect on mfgl2 expression in vitro].

OBJECTIVE: To construct the siRNA plasmid for mfgl2 gene, which has been reported to be involved in a variety of disease developments including fulminant viral hepatitis, acute rejection of allo/zero transplantation and fetal loss syndrome, and to investigate its inhibitory effects on mfgl2 expression in vitro. METHODS: A plasmid p-mfgl2shRNA complimentary to the sequence responsible for the functional domain of mouse fgl2 (mfgl2) was constructed. The pcDNA3.1 mfgl2 expression construct was able to show a satisfactory fgl2 protein expression. The plasmid expression pEGFP and a construct expressing irrelevant shRNA with a random combination of the p-mfgl2shRNA sequence were used as controls. A pEGFP-mfgl2 expressing mfgl2-EGFP fusion protein was also constructed for screening of the effect of p-mfgl2shRNA on the mfgl2 expression. RESULTS: Cotransfection of p-mfgl2shRNA with pEGFP-mfgl2 decreased green fluorescent cells and the lightness of fluorescence within the cells at the 24 h, 48 h and 72 h post-transfection when compared with that in the control groups which were solely transfected with pEGFP-mfgl2. Furthermore the mfgl2 expression was significantly reduced when the pcDNA3.1 mfgl2 expression construct was cotransfected with p-mfgl2shRNA both at mRNA level by RT-PCR and protein level by RT-PCR, immunohistochemistry staining and FACS in both CHO cell and Hela cell lines. CONCLUSIONS: The study demonstrated that the construct of p-mfgl2shRNA successfully interfered in the mfgl2 expression in vitro. It provides a basis for a further investigation of effect in vivo.

Animals↗
PubMed2005

Fibrinogen-like protein 2 fibroleukin expression and its correlation with disease progression in murine hepatitis virus type 3-induced fulminant hepatitis and in patients with severe viral hepatitis B.

AIM: To evaluate the expression of fibrinogen-like protein 2 (fgl2) and its correlation with disease progression in both mice and patients with severe viral hepatitis. METHODS: Balb/cJ or A/J mice were infected intraperitoneally (ip) with 100 PFU of murine hepatitis virus type 3 (MHV-3), liver and serum were harvested at 24, 48, and 72 h post infection for further use. Liver tissues were obtained from 23 patients with severe acute chronic (AOC) hepatitis B and 13 patients with mild chronic hepatitis B. Fourteen patients with mild chronic hepatitis B with cirrhosis and 4 liver donors served as normal controls. In addition, peripheral blood mononuclear cells (PBMC) were isolated from 30 patients (unpaired) with severe AOC hepatitis B and 10 healthy volunteers as controls. Procoagulant activity representing functional prothrombinase activity in PBMC and white blood cells was also assayed. A polyclonal antibody against fgl2 was used to detect the expression of both mouse and human fgl2 protein in liver samples as well as in PBMC by immunohistochemistry staining in a separate set of studies. Alanine aminotransferase (ALT) and total bilirubin (TBil) in serum were measured to assess the severity of liver injury. RESULTS: Histological changes were found in liver sections 12-24 h post MHV-3 infection in Balb/cJ mice. In association with changes in liver histology, marked elevations in serum ALT and TBil were observed. Mouse fgl2 (mfgl2) protein was detected in the endothelium of intrahepatic veins and hepatic sinusoids within the liver 24 h after MHV-3 infection. Liver tissues from the patients with severe AOC hepatitis B had classical pathological features of acute necroinflammation. Human fgl2 (hfgl2) was detected in 21 of 23 patients (91.30%) with severe AOC hepatitis B, while only 1 of 13 patients (7.69%) with mild chronic hepatitis B and cirrhosis had hfgl2 mRNA or protein expression. Twenty-eight of thirty patients (93.33%) with severe AOC hepatitis B and 1 of 10 with mild chronic hepatitis B had detectable hfgl2 expression in PBMC. No hfgl2 expression was found either in the liver tissue or in the PBMC from normal donors. There was a positive correlation between hfgl2 expression and the severity of the liver disease as indicated by the levels of TBil. PCA significantly increased in PBMC in patients with severe AOC hepatitis B. CONCLUSION: The molecular and cellular results reported here in both mice and patients with severe viral hepatitis suggest that virus-induced hfgl2 prothrombinase/fibroleukin expression and the coagulation activity associated with the encoded fgl2 protein play a pivotal role in initiating severe hepatitis. The measurement of hfgl2/fibroleukin expression in PBMC may serve as a useful marker to monitor the severity of AOC hepatitis B and a target for therapeutic intervention.

Animals↗
PubMed2005

Role of fibrinogen-like protein 2 prothrombinase/fibroleukin in experimental and human allograft rejection.

Immune coagulation is a major contributor to the pathogenesis of xenograft rejection, viral-induced hepatocellular injury and cytokine-induced fetal loss syndrome. In this study, we investigated the contribution of the novel gene product, fibrinogen-like protein 2 (fgl2) prothrombinase, in mediating immune injury in experimental and human acute allograft rejection. Using a mouse heterotopic cardiac transplant model, mouse fgl2(mfgl2)/fibroleukin mRNA transcripts and protein were highly expressed in macrophages, CD4- and CD8-positive T lymphocytes, and endothelial cells in rejecting cardiac allografts in association with deposits of fibrin. Although mfgl2-deficient mice rejected allografts at similar rates to littermate controls, survival of grafts from mfgl2-deficient mice were prolonged and deposition of intravascular fibrin was diminished. Treatment of wild-type mice with a neutralizing anti-fgl2 Ab ameliorated histological evidence for allorejection and intravascular fibrin deposition, and resulted in an increase in graft survival. To address further the relevance of fgl2 in acute allograft rejection, we examined kidney biopsies from patients who had undergone renal transplantation. Human fgl2 mRNA transcripts and protein were markedly expressed mainly in renal tubule cells, infiltrating lymphoid cells including macrophages, CD8(+) T cells, mature B cells (plasma cells), and endothelial cells. Dual staining showed fibrin deposition was localized mainly to blood vessels, in the glomerulus and interstitium and the lumen of tubules, and occurred in association with human fgl2 expression. These data collectively suggest that fgl2 accounts for the fibrin deposition seen in both experimental and human allograft rejection and provide a rationale for targeting fgl2 as adjunctive therapy to treat allograft rejection.

Adult↗
PubMed2005

[Apoptosis in neonatal rat lung exposed to hyperoxia].

OBJECTIVE: Exposure to high concentrations of oxygen in the neonatal period may impair lung growth and is a major contributing factor to the development of bronchopulmonary dysplasia (BPD). Cell death from hyperoxic injury may occur through either an apoptotic or nonapoptotic pathway. The aim of the present study was to investigate the effect of hyperoxia on caspase-3 and p53 gene expression and apoptosis in the lungs of neonatal rats, so as to determine the type of cell death that occurs in the lungs of neonatal rats exposed to hyperoxia. METHODS: Hyperoxic lung injury model was established by exposing to 95% O(2) in the neonatal period of Spraque-Dawley rats. The levels of caspase-3 mRNA and p53 mRNA expression in the lungs of neonatal rats exposed to 95% hyperoxia or room air were detected by RT-PCR. To quantify PCR products, PCR products were electrophoretically separated with 1.5% agarose gels. The optical density (A) values of the DNA bands were quantified by complete gel documentation and analysis system. The A ratios of p53/beta-actin denoted the relative content of p53 mRNA, results were showed as mean +/- standard deviation. The specific positive or negative bands of caspase-3 in electrophoresis gels were counted, Fisher's exact test of propabilities was used to determined statistically significant differences between two groups. We determined the extent of apoptosis taking place in the lungs of neonatal rats exposed to 95% hyperoxia using terminal deoxyribonucleotide transferase-mediated deoxyuridine triphosphate-fluorescence nick-end labeling (TUNEL) in 7-d-old neonatal lung. Under light microscope, five areas of lung parenchyma were systematically and randomly photographed from each animal and positive cells among 500 lung cells were calculated. Results were showed as mean +/- standard deviation. RESULTS: We found increased levels of p53 messenger RNA, a gene associated with apoptosis, in the lungs of neonatal rat born and raised in 95% hyperoxia. Moderate increase in the level of p53 mRNA was found in the hyperoxic-treated group at 24 h (q = 3.2305, P > 0.05). Significant increase in the level of p53 mRNA was found in the hyperoxic-treated group at 48 h (q = 7.2941, P < 0.01). The levels of p53 mRNA expression in neonatal rat lungs exposed to 95% O(2) for 72 h or 96 h returned to normal level. The levels of caspase-3 mRNA expression were very low or absent in the hyperoxic-treated groups at 12 h, 24 h, 48 h, 72 h and 96 h or in the air-breathing groups at 12 h, 24 h, 48 h, 72 h and 96 h. An increase in the number of cells undergoing apoptosis was found in the hyperoxic-treated group at 7 d (F = 56.5010, P < 0.001) which was significantly greater than the number of apoptotic cells found in the lungs of rats of the same age exposed to room air. CONCLUSION: Our results suggested that 95% hyperoxia could temporarily up-regulate the gene expression of p53, which induced the transcription of p21(WAF/CIP1) mRNA. Furthermore, p21(WAF/CIP1) could lead to cell cycle arrest and inhibit proliferation of lung cells. Meanwhile, p53 could also promote apoptosis of lung cells. Therefore, exposure to high concentrations of oxygen in the neonatal period may impair lung growth and is a major contributing factor to the development of bronchopulmonary dysplasia (BPD), and hyperoxia may affect the future lung growth and lead to barrier of lung development. The treatments of anti-apoptosis and promoting alveoli growth hold a promising perspective in hyperoxic lung injury. The level and ratio of caspase-3 gene expression were very low or absent in the lungs of neonatal rats exposed to 95% O(2) or room air. We speculated that caspase-3 gene expression was not essential in the hyperoxia induced lung cell apoptosis in neonatal rats.

Animals↗
PubMed2004

[Expression of human fibrinogen-like protein 2/fibroleukin in renal acute allograft rejection and its potential clinical implication].

OBJECTIVE: To investigate the expression of human fibrinogen-like protein 2 (hfgl2)/fibroleukin in renal acute allograft rejection and its correlation with the course of the disease. METHODS: Thirty-one samples of aspiration biopsy of renal acute allograft rejection were collected. Histological sections were stained with hemotoxylin and eosin. Polyclonal antibody against hfgl2 was used to detect the expression of hfgl2 protein by immunohistochemistry. Anti-CD68 and anti-CD8 monoclonal antibodies were used to detect the macrophages activation and lymphocyte respectively in serial sections to identify the cell types that express hfgl2. Anti-fibrinogen monoclonal antibody and thrombus staining were used to detect the fibrin deposition and the formation of thrombus. Double staining with anti-hfgl2 antibody and anti-fibrinogen antibody was performed to clarify the correlation between hfgl2 expression and fibrin deposition. RESULTS: Twenty-nine cases showed hfgl2 expression, mainly displayed in tubule cells, infiltrative cells (macrophages, CD8+ T cells and plasmacytes), and part of the adherent cells or infiltrative cells in tubules and vessels, whereas no hfgl2 protein was detected in glomerulus and endothelium of vessels. Double staining displayed that the fibrin deposition was mainly in the vessels, glomeruli and interstitium, and the lumen of tubule in association with hfgl2 expression. No thrombus was found in all the sections. CONCLUSION: The abnormal expression of hfgl2 in renal acute allograft rejection in human beings activates the thrombosin inside and outside the vessels that causes fibrin deposition and microcirculatory disturbances, thus further exacerbating the pathological injuries of tissues. hfgl2 protein may serve as a new target for therapeutic intervention for acute allograft rejection.

Acute Disease↗
PubMed2004

Methylmalonic acid in amniotic fluid and maternal urine as a marker for neural tube defects.

To evaluate the implication of methymalonic acid (MMA) in the early diagnosis of neural tube defects (NTD), a quantitative assay for MMA was established by using gas chromatography-mass spectrometry with stable isotope of MMA as an internal standard. Amniotic fluid and maternal urine MMA concentration, maternal serum folate, red blood cell folate and vitamin B12 levels were measured in the middle term of NTD-affected and normal pregnancies. Amniotic fluid and maternal urine MMA concentrations in the middle term of NTD affected pregnancies (1.4 +/- 0.9 micromol/L, and 22.1 +/- 12.6 nmol/micromol creatinine) were significantly higher than that of normal pregnancies (1.0 +/- 0. 4 micromol/L, and 2.5 +/- 1.1 nmol/micromol creatinine). There was no significant difference between normal and NTD pregnancies for serum folate, red blood cell folate and vitamin B12 levels. The results suggested that MMAs in amniotic fluid and maternal urine are sensitive markers for early diagnosis of NTD. Vitamin B12 is an active cofactor involved in the remethylation of homocycteine and its deficiency is an independent risk factor for NTD. MMA is a specific and sensitive marker for intracellular vitamin B12 deficiency. This study suggests that it is necessary to monitor the vitamin B12 deficiency and advocates vitamin B12 supplementation with folate prevention program.

Adult↗
PubMed2004

[Effects of U74389G on pulmonary macrophage influx and lung development in 95% O2 exposed newborn rats].

OBJECTIVE: Oxygen toxicity is believed to play a critical role in the pathogenesis of bronchopulmonary dysplasia (BPD). U74389G, a potent 21-aminosteroid antioxidant, was applied to the 95% O(2) induced acute lung injury in newborn rat model. The present study aimed to investigate the mechanism of hyperoxic lung injury and the interaction of possible mediators, and to explore the effect of antioxidant intervention. METHODS: Newborn Sprague-Dawley rats were randomly divided into four groups: air-exposed control, air-exposed treated with U74389G, hyperoxia-exposed control, hyperoxia-exposed treated with U74389G. Hydroxyl radical formation (2,3-DHBA and 2,5-DHBA) was assessed by an aromatic hydroxylation assay using GC/MS with salicylate as the probe. The 8-isoprostane, a specific marker for in vivo lipid peroxidation, was quantitated by enzyme immunoassay. Pulmonary macrophage influx and nitrotyrosine formation were measured by means of immunohistochemistry. (3)H-TdR (autoradiography) incorporation was assessed as an index of active lung cell growth. RESULTS: Exposure to 95% O(2) for 7 days induced significant lung injury and mortality. The contents of hydroxyl radical in the hyperoxia-exposed lungs were dramatically increased [(2,3-DHBA 49.2 +/- 3.5 pmol/mg), (2,5-DHBA 55.8 +/- 2.3 pmol/mg), P < 0.05) and were decreased by treatment with U74389G [(2,3-DHBA 37.9 +/- 2.4 pmol/mg), (2,5-DHBA 31.3 +/- 1.9 pmol/mg), P < 0.05). The level of 8-isoprostane in the lungs of 95% O(2)-exposed newborn rats was significantly raised (546.6 +/- 32.2 pg/mg, P < 0.05) and lowered down by U74389G (358.5 +/- 24.1 pg/mg, P < 0.05). This phenomenon was also observed in the air-exposed animals. Remarkable pulmonary macrophage infiltration was evident in hyperoxia-exposed newborn rats and was attenuated by U74389G treatment. Nitrotyrosine distributed in the lung parenchyma and epithelial cells of large airway of hyperoxia-exposed newborn rats. The extent of protein nitration was reduced by U74389G, but the oxygen induced morphological change was not significantly improved by U74389G treatment. Exposure to 95% O(2) induced lung growth arrest as shown by (3)H-TdR incorporation. U74389G partially preserved active lung cell growth in hyperoxia-exposed rats, but showed an inhibitory effect on normal lung cell growth. CONCLUSION: Through scavenging hydroxyl radical and lipid peroxides, U74389G could block pulmonary macrophage influx and partly avert alveolar development arrest in hyperoxia-exposed newborn rats. Antioxidant intervention holds promising in hyperoxic lung injury though cautions should be taken as possible interference on normal cell development.

Animals↗
PubMed2004

[Hfgl2/fibroleukin expression in liver and peripheral blood mononuclear cells (PBMC) and its correlation with disease severity].

OBJECTIVE: Viral hepatitis remains a major public health problem and the most common type of liver disease worldwide. There are an increasing number of patients with chronic hepatitis B who develop acute hepatitis on chronic condition (AOC) and die of acute hepatic failure both as a result of lack of understanding of the pathogenesis of the disease and lack of effective treatment. The hallmark of AOC is the extreme rapidity of the necromicroinflammatory process resulting in widespread or total hepatocellular necrosis in weeks or even days. Our previous studies have shown in an experimental animal model of fulminant viral hepatitis caused by murine hepatitis virus strain 3, the importance of macrophage activation, and expression of a unique gene mfgl 2 which encodes a serine protease capable of directly cleaving prothrombin to thrombin, resulting in widespread fibrin deposition within the liver and hepatocyte necrosis. The undergoing study in this report is designed to identify the role of hfgl 2 (human fibrinogen like protein 2) /fibroleukin in patients with viral hepatitis. METHODS: Liver tissues were obtained from 23 patients with AOC hepatitis B, and from 13 patients with inactive chronic hepatitis B (CHB) and 14 patients with chronic hepatitis B with cirrhosis during the year of 1995 to the end of 2001. Liver biopsies were performed within 30 min after the patients were diagnosed with death as a result of acute hepatic failure. Liver samples were also obtained from 4 liver donors as normal controls. In addition, peripheral blood mononuclear cells (PBMC) were isolated from 30 patients (unpaired) with AOC hepatitis B and 10 patients with CHB during the May of 2001 to March of 2002 and 10 healthy volunteer as negative control. PBMCs were freshly isolated and smeared on slides and kept at -80 degree C for further use. Histological sections were stained with hemotoxylin and eosin. A 169 bp of hfgl 2 cDNA probe and a polyclonal or monoclonal antibody against hfgl 2 were used to detect the expression of hfgl 2 mRNA and protein in liver samples as well as PBMC by immune histochemistry separately. RESULTS: Liver tissues from the patients with acute on chronic hepatitis had classical pathological features of acute necroinflammation. Hfgl 2 was detected by immune histochemistry in 21 of 23 patients (91.3%) in liver sections from patients with acute on CHB, while only 1 of 13 patients (7.7%) with CHB and cirrhosis and no evidence of active disease had hfgl 2 mRNA or protein expression. 28 of 30 patients (93.3%) with acute on CHB and 1 of 10 with CHB were detected with hfgl 2 expression in PBMC. There was no hfgl 2 expression in either the liver tissue or the PBMC from the normal donors. There was positive correlation of hfgl 2 expression and the severity of the disease displayed by the value of bilirubin and PT. CONCLUSION: The molecular and cellular results reported here in patients with acute on chronic hepatitis and who died of acute hepatic failure correlates with previous report in 8 patients with fulminant hepatic failure (FHF) and mimic closely the changes observed in the murine model of fulminant viral hepatitis in which the pathogenesis of the disease has been studied in a stepwise fashion. This study further suggests that virus induced hfgl 2 prothrombinase/fibroleukin expression and the potent function of the protein it encodes plays a pivotal role in initiating acute severe hepatitis on the baseline of chronic hepatitis. The measurement of hfgl 2/fibroleukin expression in PBMC may serve as a useful marker to monitor the severity of disease in patients with the AOC hepatitis B and a target for therapeutic intervention.

Adolescent↗
PubMed2003

[The study of cis-element HNF4 in the regulation of mfg12 prothrombinase/fibroleukin gene expression in response to nucleocapsid protein of MHV-3].

OBJECTIVE: To identify the transcription factor(s) that is essential for activation of mfgl2 prothrombinase/fibroleukin gene in response to nucleocapsid protein of murine hepatitis virus type 3 (MHV-3). METHODS: Western blotting was performed to investigate whether HNF4 is expressed in macrophages of Ba1b/c mice where mfgl2 is expressed. Confocus microscope immunofluorescence was performed to show whether N protein of MHV enters into the nucleus of infected cells, which is a critical step for the N protein to facilitate its transactivation property. To facilitate the identification of three candidate factor(s) including hepatocyte nuclear factor 4 (HNF4)/liver factor A1 (LF-A1), cytomegalovirus immediate early gene 1.2 (IE1.2) regulatory element and granulocyte- macrophage colony stimulating factor (GM-CSF) in response to mfgl2 activation upon the stimulation of MHV-A59 N protein, gel mobility shift assay (GMSA), competition experiments and site directed mutagenesis were performed. RESULTS: Western blotting displayed that HNF4 was constitutively expressed in macrophages and did not show significant change under the stimulation of different MHV. Confocus microscope immunofluorescence clearly showed that N protein of MHV entered into the nucleus of infected cells. GMSA and competition experiments demonstrated binding to both HNF4 and IE1.2 fragments could be competed with the cold specific oligonucleotides but not with the same amount of non-specific oligos nucleotides. A super shift band was observed when HNF4 antibody was pre-incubated with the nuclear extracts indicating the interaction between the HNF4 element and mfgl2 promoter. Site directed mutagenesis of cis-elements HNF4 (pfgl2HNF4mut) and HNF4/IE1.2 (pfgl2HNF4/IE1.2mut) mutations abolished over 75% of transcription from wild-type mfgl2 promoter. However the pfgl2IE1.2mut displayed almost wild-type promoter activity (75% approximately 80%). CONCLUSIONS: The factor HNF4 binds to mfgl2 promoter and serves as an essential transcription factor for mfgl2/fibroleukin expression in response to MHV-3 N protein.

Animals↗
PubMed2003

[Expression of human fibroleukin gene acute on chronic hepatitis B and its clinical significance].

OBJECTIVE: To investigate the mRNA and protein expressions of human fibroleukin gene (hfg12) in acute on chronic (AOC) hepatitis B and its clinical significance. METHODS: Liver tissues were obtained from 23 patients with AOC hepatitis B, 13 patients with chronic hepatitis, and 14 patients with cirrhosis to be examined histologically. Immunohistochemistry and in situ hybridization were used to detect the mRNA and protein expressions of hfg12 in the liver tissues. Double staining was used to the hfg12 positive samples to examine both the hfg12 and fibrin. Four specimens of liver tissue from normal donors were used as controls. RESULTS: Immunohistochemistry showed that hfg12 was expressed in the liver tissues of 21 out of the 23 patients with AOC hepatitis B (91.30%) and only one out of the 13 patients with chronic hepatitis (7.69%). In situ hybridization showed that hfg12 was expressed in the liver tissues of 13 out of he 23 patients with AOC hepatitis B and in none of the 27 patients with chronic hepatitis or cirrhosis. In patients with AOC hepatitis Kupffer's cell, CD68 positive, was numerous and big, mainly distributed in the necrosis areas. It was identified as the same of hfg12-expressing cells. CONCLUSION: High expression of hfg12 is one of the molecular mechanisms of necrosis of liver cells in AOC hepatitis.

Adolescent↗
PubMed2003

Induction of prothrombinase fgl2 by the nucleocapsid protein of virulent mouse hepatitis virus is dependent on host hepatic nuclear factor-4 alpha.

Fibrinogen-like protein 2/fibroleukin (Fgl2) plays a pivotal role in the pathogenesis of both experimental and human fulminant hepatic failure. We have reported recently that the nucleocapsid (N) protein from strains of murine hepatitis virus (MHV-3, MHV-A59), which cause massive hepatocellular necrosis but not from strains (MHV-JHM, MHV-2) which do not produce serious liver disease, induces transcription of fgl2. The purpose of the present study was to characterize both viral and host factor(s) necessary for viral induced transcription of fgl2. Mutation of residues Gly-12, Pro-38, Asn-40, Gln-41, and Asn-42 within domain 1 of the N protein of MHV-A59 to their corresponding residues found in MHV-2 abrogated fgl2 transcription, whereas mutation of other N protein domains, including a protein expressed from an internal reading frame (I protein), did not affect fgl2 gene transcription. We then examined the -372 to -306 sequence within the 1.3-kb fgl2 promoter region upstream from the transcription start site that was previously identified as necessary for N protein-induced gene transcription. We demonstrated that the -331/-325 HNF4 cis-element and its cognate transcription factor, HNF4alpha, are necessary for virus-induced fgl2 gene transcription. In uninfected macrophages and macrophages infected with MHV-2, an unidentified protein occupies the HNF4 cis-element. Following stimulation with MHV-A59, it was shown by electrophoretic mobility shift assay that HNF4alpha binds the HNF4 cis-element in the fgl2 promoter. We further report the unprecedented presence of HNF4alpha in peritoneal macrophages. Collectively, the results of this study define both viral and host factors necessary for induction of fgl2 prothrombinase gene transcription in MHV infection and may provide an explanation for the hepatotrophic nature of MHV-induced fulminant hepatic failure.

Amino Acid Sequence↗
PubMed2003

STAT1 and STAT3 alpha/beta splice form activation predicts host responses in mouse hepatitis virus type 3 infection.

Signal transducer and activator of transcription 1alpha (STAT1 alpha) is reported to be essential for IFN-gamma and IFN-alpha regulated gene expression, while STAT1 beta, an alternate splice-form, mediates only IFN-alpha-dependent gene expression. STAT3 alpha and STAT3 beta splice forms are also differentially activated in response to cytokines including IL-6 and IL-10. The aim of this study was to investigate whether the STAT activation will predict the host immune response to viral infection and possibly a therapeutic target for the treatment of viral infection. Mouse hepatitis virus type 3 (MHV-3) resistant strain (A/J) and sensitive mouse strains (BalB/cJ) were infected intraperitoneally (i.p.) with 100 plaque form units (pfu) of MHV-3. The mice were sacrificed at the indicated times, and livers and spleens were immediately frozen in liquid nitrogen. Nuclear extracts proteins were detected by immunoblotting. STAT1 and STAT3 activation in spleen increased 24 to 72 hr following MHV-3 infections in both sensitive and resistant mouse strains. However, over this time period, the ratio of activated alpha to beta splice-form for STAT1 and STAT3 increased above 1.0 in resistant A/J mice, while the ratio fell to <0.3 in MHV-3 sensitive Balb/cJ and C3H/HeJ strains. Activated STAT1 alpha/beta and STAT3 alpha/beta ratio in liver were similar in resistant and sensitive mouse strains. Treatment of sensitive Balb/cJ mice with neutralizing anti-TGF-beta antibody could increase the STAT1 alpha/beta ratio to <1.0 in spleens, predicting enhanced rates of survival. These results suggested that ratio of activated STAT1 alpha/beta and STAT3 alpha/beta in mixed leukocytes from spleen predict the outcome to MHV-3 infection, and may be an important marker and therapeutic target for modification of host immune response to virus infection.

Alternative Splicing↗
PubMed2003

Gene transcription of fgl2 in endothelial cells is controlled by Ets-1 and Oct-1 and requires the presence of both Sp1 and Sp3.

The immune coagulant fgl2/fibroleukin has been previously shown to play a pivotal role in the pathogenesis of murine and human fulminant hepatitis and fetal loss syndrome. Constitutive expression of fgl2 transcripts at low levels are seen in cytotoxic T cells, endothelial, intestinal and trophoblast cells, while specific factors (such as virus and cytokines) are required to induce high levels of fgl2 expression in other cell types including monocytes/macrophages. To address the transcriptional mechanisms that regulate constitutive expression of fgl2, murine genomic clones were characterized and the transcription start site was defined by 5'-RACE and primer extension. A comprehensive assessment of basal fgl2 promoter activity in murine vascular endothelial cells defined a minimal 119 bp region responsible for constitutive fgl2 transcription. A complex positive regulatory domain (PRD) spanning a 39-bp sequence from -87 to -49 (relative to the transcription start site) was identified. Electrophoretic mobility shift assay studies in vascular endothelial cells revealed that the nucleoprotein complexes that form on this positive regulatory domain (PRD) contain Sp1/Sp3 family members, Oct-1, and Ets-1. Heterologous expression studies in Drosophila Schneider cells confirmed that the constitutive expression of this gene is controlled by Ets-1 and requires the presence both of the Sp1 and Sp3 transcription factors. The presence of this complex multicomponent PRD in the fgl2 proximal promoter is consistent with the observation that, in vivo, fgl2 expression is tightly regulated. Moreover, viral induced fgl2 expression also requires the presence of this PRD. These results clearly demonstrate that multiple cis DNA elements in a clustered region work cooperatively to regulate constitutive fgl2 expression and interact with inducible elements to regulate viral-induced fgl2 expression in endothelial cells.

Animals↗
PubMed2003

The Fgl2/fibroleukin prothrombinase contributes to immunologically mediated thrombosis in experimental and human viral hepatitis.

Fibrin deposition and thrombosis within the microvasculature is now appreciated to play a pivotal role in the hepatocellular injury observed in experimental and human viral hepatitis. Importantly, the pathways by which fibrin generation is elicited in viral hepatitis may be mechanistically distinct from the classical pathways of coagulation induced by mechanical trauma or bacterial lipopolysaccharide (LPS). In the setting of murine hepatitis virus strain-3 (MHV-3) infection, a member of the Coronaviridae, activated endothelial cells and macrophages express distinct cell-surface procoagulants, including a novel prothrombinase, Fgl2/fibroleukin, which are important for both the initiation and localization of fibrin deposition. To assess the role of Fgl2/fibroleukin in murine viral hepatitis we generated a Fgl2/fibroleukin-deficient mouse. Peritoneal macrophages isolated from Fgl2/fibroleukin-/- mice did not generate a procoagulant response when infected with MHV-3. Fibrin deposition and liver necrosis were markedly reduced, and survival was increased in mice infected with MHV-3. To address the relevance of Fgl2/fibroleukin in human chronic viral hepatitis we studied patients with minimal and marked chronic hepatitis B. We detected robust expression of Fgl2/fibroleukin mRNA transcripts and protein in liver tissue isolated from patients with marked chronic hepatitis B. Fibrin deposition was strongly associated with Fgl2/fibroleukin expression. Collectively, these data indicate a critical role for Fgl2/fibroleukin in the pathophysiology of experimental and human viral hepatitis.

Adult↗