Intrahepatic MxA and PKR protein expression in chronic hepatitis C virus infection

The therapeutic effect of interferon-alpha and ribavirin in the treatment of chronic hepatitis C viral infection is limited. To identify patient characteristics that may predict responsiveness to treatment, the intrahepatic protein expression of two directly induced IFN-alpha effector proteins, MxA and PKR, were studied. Forty liver biopsy samples from patients with a variety of chronic liver diseases were stained for MxA and PKR protein using immunohistochemical techniques. In a HCV patient cohort, 30 liver biopsies were stained for MxA and PKR protein prior to treatment with IFN-alpha and ribavirin. PKR protein expression was not upregulated in viral liver disease. In contrast, MxA protein expression was significantly upregulated in viral liver disease (P = 0.005). In chronic HCV liver disease, moderate to strong cytoplasmic expression of MxA protein was observed in hepatocytes and monocytes, indicating endogenous hepatocellular IFN-alpha pathway activation. In the HCV patient cohort treated with combination therapy, strong pre-treatment MxA hepatocyte expression was predictive of a non-response to treatment (odds ratio 9.33; P = 0.01; 95% confidence interval 1.63-53.2). This effect was independent of HCV genotype and viral load. It is concluded that pretreatment hepatocellular MxA expression may become a useful predictor of response to combination treatment with IFN-alpha and ribavirin.     

Intrahepatic MxA expression is correlated with interferon-alpha expression in chronic and fulminant hepatitis

Interferon-alpha (IFN-alpha) has potent pro-inflammatory and anti-viral functions. It exerts its effects by inducing intracellular proteins such as MxA. To analyse the role of intrahepatic interferon activation, IFN-alpha and MxA expression was studied by immunohistochemistry in explant livers of 20 patients with fulminant hepatic failure (FHF), 41 patients with chronic liver disease (CLD), and ten normal controls (NCs). In NCs only small numbers of Kupffer cells, but no hepatocytes, showed IFN-alpha and MxA expression. In contrast, significantly enhanced numbers of IFN-alpha- and MxA-positive Kupffer cells, along with small numbers of MxA-positive and larger numbers of IFN-alpha-positive lymphocytes, were found in CLD and in FHF. MxA protein was also expressed on hepatocytes and bile ducts in the vicinity of IFN-alpha-positive inflammatory infiltrates (hepatocytes: NCs: 0%, CLD: 8%, FHF: 68%; bile ducts: NCs: 19%, CLD: 46%, FHF: 83%). A significant correlation was found between the numbers of IFN-alpha- and MxA-positive cells (r=0.67, p<0.001). Thus, large amounts of IFN-alpha are released in the livers of patients with FHF, which is likely to contribute to immune-mediated liver cell damage. Intrahepatic MxA expression corresponds to IFN-alpha produced particularly by infiltrating inflammatory cells, rather than by hepatocytes themselves.     

Expression of the interferon-inducible proteins MxA and IFI16 in liver allografts

Aims:  To test the hypothesis that the activation of the interferon (IFN) system pathways might link hepatitis C virus (HCV) recurrence in the liver allograft with acute cellular rejection.
Methods and results:  In this retrospective study, allograft biopsy specimens from 28 adult patients (14 HCV+ and 14 HCV−) who had undergone their first liver transplantation were analysed. Eleven biopsy specimens showed acute cellular rejection (Banff rejection activity index score ≥3). Specimens were immunostained for two IFN-inducible proteins, MxA and IFI16, and for CD45. The predominant MxA reactivity pattern was hepatocytic, whereas IFI16 was expressed in both the hepatocellular and inflammatory compartments. Moderate to strong MxA expression in hepatocytes was associated positively with rejection score ( P  < 0.01), donor's age ≤45 years ( P  < 0.05) and aspartate aminotransferase levels >40 U/l on the day of biopsy ( P  < 0.05), and inversely with infiltration of portal triads by IFI16+/CD45+ cells ( P  < 0.005) and time to progression beyond Ishak stage 2 of recurrent hepatitis C ( P  < 0.01). On multivariate analysis, MxA expression in hepatocytes was independently associated with allograft rejection and donor's age.
Conclusions:  Acute allograft rejection and recurrence of HCV infection in the liver allograft appear to intersect in the IFN system pathways.     

Type I interferon inhibits Crimean-Congo hemorrhagic fever virus in human target cells

Crimean-Congo hemorrhagic fever virus (CCHFV) is a causative agent of severe hemorrhagic fever occurring sporadically in parts of Africa, Asia, Southeast Europe, and the Middle East. Its recent recognition as a potential agent of bioterrorism/biowarfare highlights the need for effective antiviral therapy. In this study, it is shown that human endothelial cells are permissive to CCHFV. It is also shown that interferon-alpha inhibits the growth of CCHFV in human endothelial and hepatoma cells, reducing virus yields by a factor of 100-1,000. By using a siRNA approach, it was demonstrated that the interferon-induced MxA GTPase is a major factor mediating the antiviral effect against CCHFV, in agreement with previous findings showing that recombinant MxA inhibits CCHFV replication by interacting with the viral nucleocapsid protein. The identification of intrinsic cellular resistance factors that block CCHFV replication may help in designing novel antiviral agents.     

MxA gene expression in juvenile dermatomyositis peripheral blood mononuclear cells: association with muscle involvement

Juvenile dermatomyositis (JDM), a systemic vasculopathy, is characterized by inflammation of skin and muscle. Muscle biopsies from untreated JDM patients show upregulation of type I interferon (IFN)-inducible genes, including myxovirus resistance protein A (MxA). The present study examines whether MxA mRNA expression in peripheral blood mononuclear cells (PBMC) from JDM patients: (1) is elevated compared to healthy controls, (2) reflects disease activity, and (3) changes with the onset of clinically effective treatment. MxA mRNA expression in JDM PBMC obtained at the initial clinic visit was elevated compared to controls and was positively correlated with Disease Activity Score (DAS) for muscle, but not with DAS for skin, suggesting that damage to skin and muscle in JDM may each have a discrete pathophysiology. During the course of clinically effective treatment, decrease in muscle symptoms was associated with a decrease in PBMC MxA mRNA expression.     

Blood MxA protein as a marker for respiratory virus infections in young children

BackgroundType I interferon induced MxA response can differentiate viral from bacterial infections, but MxA responses in rhinovirus or asymptomatic virus infections are not known.ObjectiveTo study MxA protein levels in healthy state and during respiratory virus infection of young children in an observational prospective cohort.Study designBlood samples and nasal swabs were collected from 153 and 77 children with and without symptoms of respiratory infections, respectively. Blood MxA protein levels were measured by an enzyme immunoassay and PCR methods were used for the detection of respiratory viruses in nasal swabs.ResultsRespiratory viruses were detected in 81% of symptomatic children. They had higher blood MxA protein levels (median [interquartile range]) than asymptomatic virus-negative children (695 [345–1370] μg/L vs. 110 [55–170] μg/L; p < 0.001). Within asymptomatic children, no significant difference was observed in MxA responses between virus-positive and virus-negative groups. A cut-off level of 175 μg/L had 92% sensitivity and 77% specificity for a symptomatic respiratory virus infection. Rhinovirus, respiratory syncytial virus, parainfluenza virus, influenza virus, coronavirus, and human metapneumovirus infections were associated with elevated MxA responses. Asymptomatic virus-negative children vaccinated with a live virus vaccine had elevated MxA protein levels (240 [120–540] μg/L), but significantly lower than children with an acute respiratory infection, who had not received vaccinations (740 [350–1425] μg/L; p < 0.001).ConclusionBlood MxA protein levels are increased in young children with symptomatic respiratory virus infections, including rhinovirus infections. MxA is an informative general marker for the most common acute virus infections.     

Increased lymphoid MxA expression in acute asthma exacerbation in children

BACKGROUND: Although the association between acute asthma exacerbation and viral infection has been well documented, virus identification rates vary. It has recently been reported that the expression of MxA protein in lymphocytes, inducible by type I interferons, can serve as a sensitive marker for viral infection in the host. The objective was to determine the contribution of viral infection to precipitation of asthma attacks in children. METHODS: We studied 186 asthmatic children, aged 0-12 years, over a 1-year period to evaluate MxA protein levels in peripheral blood lymphocytes by using a flow cytometric analysis in whole blood. RESULTS: Of all the subjects, 80 (47%) exhibited significantly elevated levels of MxA expression in lymphocytes, presumably indicating the states of viral infection. The association of viral infections with acute asthma exacerbation seemed to be marked in younger children: enhanced MxA expression was seen in 73.3% of infants (aged 0-1 year), 49.5% of toddlers (aged 2-5 years), and 26% of schoolchildren (aged 6-12 years). Seasonal changes in the frequency of viral infection associated with deterioration were also observed. CONCLUSIONS: Flow cytometric assay of MxA protein expression in whole blood appears to be an easy and useful method to evaluate viral infections in acute asthma exacerbation.     

Impaired interferon induction of human MxA protein in chronic hepatitis B virus infection

MxA protein is interferon inducible, and its role as an antiviral mediator is being studied in various viral diseases. Several cytokines, including type I interferons (α and B), interleukins 2 and 12, and granulocyte, macrophage, and granulocyte-macrophage colony-stimulating factors, were tested for their ability to induce human MxA protein synthesis in peripheral blood mononuclear cells from 15 chronic hepatitis B virus-infected patients and 6 healthy subjects as controls. Constitutive MxA expression was scarce in patients and controls but increased significantly in response to type I interferons. MxA responsiveness to interferon α was diminished significantly in chronic hepatitis B patients, compared with healthy donors (P < 0.05); this effect was more marked in patients with high viremia levels. Interleukins 2 and 12, and none of the colony-stimulating factors tested, induced low, but detectable, MxA protein levels. These results indicate that chronic infection by hepatitis B virus may impair activation of the immune cells and their capacity to respond to type I interferons. J. Med. Virol. 51:332–337, 1997. © 1997 Wiley-Liss, Inc.     

Synthetic double-stranded RNA stimulates the expression of interferon-inducible protein 10 in human mesothelial cells

Interferon-inducible protein 10 (IP-10) is a chemokine playing an important role in the restriction of viral spread. A time- and dose-dependent increase in IP-10 is found upon activation of viral receptors expressed on mesothelial cells, which provides novel evidence for a link between viral infections and inflammation of serous membranes.     

Difference in susceptibility to MxA protein between a coxsackievirus B1 isolate and prototype,impact of serial cell culture passage

Human enteroviruses (EVs) cause a broad spectrum of acute and chronic diseases including meningitis and myocarditis. The type I interferon‐induced MxA protein has been shown to inhibit the replication of an EV, coxsackievirus B4 (CVB4), but not cardioviruses such as encephalomyocarditis virus and mengo virus, members of the Picornaviridae family. EVs consist of more than 60 distinct serotypes against which the antiviral activity of MxA was not investigated yet. The main aim of this study was to explore the antiviral activity of MxA protein against a clinical CVB1 isolate and other EV prototypes. Vero cells expressing constituvely MxA protein were infected with EVs, and the percentage of inhibiton of expression of enteroviral RNA and capsid VP1 protein was determined. Following infection of MxA‐transfected Vero cells with EVs, the expression of enteroviral RNA was inhibited by up to 99%, and that of VP1 protein by up to 85%. However, there was a difference in the percentage of MxA inhibition of EV replication between the different EV prototypes. This difference in MxA sensitivity was not due to a difference in the viral replication rates. The MxA protein was inactive against the clinical CVB1 isolate, and the replication rate of CVB1 isolate in MxA‐transfected Vero cells was higher than that in mock‐transfected Vero cells. A serial passage of the clinical CVB1 isolate and other EV prototypes resulted in an increase in their susceptibility to MxA protein. These results suggest the presence of MxA‐resistant EV variants that may escape innate immunity and cause disease. J. Med. Virol. 82:424–432, 2010. © 2010 Wiley‐Liss, Inc.     

鸡MxA基因的克隆、表达及生物学活性检测

目的：克隆鸡MxA基因，构建其原核表达质粒，并诱导其在大肠杆菌中表达融合蛋白。方法：采用RT-PCR方法从鸡成纤维细胞（CEF）中扩增MxA，将其克隆至克隆载体pMD18-T中，筛选阳性克隆后回收目的片段，将其克隆人原核表达质粒pGEX-6p—1，构建其重组表达质粒pGEX—MxA，以IPTG诱导表达，经SDS—PAGE、鸡胚新城疫病毒干扰试验和VSV-CEF微量细胞抑制试验进行分析、鉴定。结果：经RT—PCR扩增获得的MxA序列与GeneBank报道的序列一致，SDS—PAGE和干扰试验证实重组质粒可以表达出相应分子量为45000的蛋白，与GST—MxA融合蛋白分子量一致。结论：成功完成了鸡MxA基因的克隆及其原核表达质粒的构建，在大肠杆菌DIL5ct中经IPTG诱导表达了融合蛋白GST—MxA，为进一步探讨MxA的生物学活性，探索抗病毒药物的研发奠定了基础。     

登革病毒感染对人血管内皮细胞PGIS表达及PGI2分泌的影响

目的：研究登革病毒感染对人血管内皮细胞分泌血管活性物质前列环素（PGI2）的影响,以了解登革出血热/登革休克综合征（DHF/DSS）的发病机制。方法：用登革病毒Ⅱ型感染人脐静脉内皮细胞（HUVEC）,于感染后6、12、24、48、72、96h,分别收集病毒感染的HUVEC,用RT-PCR检测细胞内前列环素合酶（PGIS） mRNA的水平;分别收集病毒感染的上清液,用放射免疫检测法测定PGI2的含量。结果：登革病毒感染可使PGIS mRNA的水平增高,导致HUVEC分泌PGI2的量明显升高。在病毒感染后48、72、96h,与对照组比较HUVEC表达PGISmRNA的水平和HUVEC分泌PGI2的量明显升高（P〈0.05）。结论：DV2感染可显著上调HUVEC中PGIS mRNA转录及PGI2的分泌,导致登革病毒所致血管内皮细胞的功能障碍,可能与DHF/DSS的发病机制有关。     

Alterations in the activity and expression of endothelial NO synthase in aged human endothelial cells

This study was to investigate factors underlying the age-related decrease in NO production in vascular endothelial cells. The age-related changes in NO production, the activity and expression level of eNOS, and eNOS binding proteins, were studied in HUVECs.NO production in HUVECs significantly decreased in an age-dependent manner. The potentiation of NO production by l-Arg was significantly suppressed by L-NIO (eNOS-specific inhibitor) in young HUVECs and was suppressed by 1400W (iNOS-specific inhibitor) in aged HUVECs. The aged HUVECs had lower eNOS protein levels than young cells. eNOS phosphorylation at Ser-1177 (active) decreased gradually from PDL 23 through 40, and eNOS phosphorylation at Thr-495 (inactive) increased in aged cells. Changes of intracellular eNOS binding proteins, such as caveolin-1, pAkt, and Hsp90, as well as interaction between eNOS and eNOS binding proteins, indicated decreasing enzyme activity in aged HUVECs.Aging might decrease the activity as well as expression level of eNOS in HUVECs. And the decrease in eNOS activity probably implicated to the alterations in the regulatory binding proteins. For further study, it needs to be confirmed that the age-related change in the intracellular distribution of eNOS and the relative contribution of eNOS and iNOS on vascular dysfunction in aged endothelial cells.     

Hydrogen peroxide stimulates endocytosis in cultured bovine aortic endothelial cells

Fluid-phase uptake of macromolecules by cultured bovine aortic endothelial cells was measured using FITC-dextran (70000 Da). Low doses of hydrogen peroxide added extracellularly stimulated the uptake of macromolecules by the endothelial cells. There was no general increase in the passive permeation or the transport across the cell layer. Moreover, when endothelial cells were stimulated with phorbol myristate acetate (PMA), macromolecules uptake was also enhanced. The PMA effect was blocked with superoxide dismutase (SOD) and catalase, suggesting a pivotal role of oxygen metabolites in fluid phase uptake of macromolecules by endothelial cells.     

Circulating endothelial cells in Kawasaki disease

Recent reports have demonstrated that circulating endothelial cells (CECs) are observed in several diseases with vascular injury. Because Kawasaki disease (KD) is one type of systemic vasculitis, we hypothesized that an increased number of CECs may be associated with the appearance of complicated coronary artery lesions (CAL). In the present study we investigated the enumeration and origin of CECs in 20 patients with KD, using an immunohistochemical method with monoclonal antibodies: clone P1H12 against ECs and clone AC133 against endothelial progenitor cells (EPCs), which were derived from the bone marrow. The mean number of CECs increased significantly (P < 0.05) from the acute through the subacute phases of KD compared with both the convalescent phase of KD and healthy children. The mean number of CECs was significantly (P < 0.05) higher in six KD patients with CAL than in 14 KD patients without CAL. The population of EPCs in the total CECs in KD was 4.4 +/- 1.2% (range 0-18%). The number of EPCs during the subacute phase was also significantly higher (P < 0.05) in KD patients with CAL than in those without CAL. Our findings indicate that the number of CECs increase in KD vasculitis and suggest that the increased numbers of CECs and EPCs may reflect the EC damage of this disease.     

GTPase activity is not essential for the interferon-inducible MxA protein to inhibit the replication of hepatitis B virus

Multiple studies have established that GTPase activity is critical for MxA to act against RNA viruses. Recently, it was shown that MxA can also restrict the replication of hepatitis B virus (HBV), a DNA virus, but the requirements for GTPase activity in inhibition of HBV by MxA remain unknown. Here, we report that GTPase-defective mutants (K83A, T103A, and L612K) can downregulate extracellullar HBsAg and HBeAg and reduce the expression of extra- and intracellular HBV DNA in HepG2 cells to levels similar to that achieved by wild-type MxA. Furthermore, TMxA and T103, two nuclear forms of wild-type MxA and a GTPase-defective mutant (T103A) could only slightly decrease the expression of extra- and intracellular HBV DNA in HepG2 cells. In conclusion, GTPase activity is not essential for MxA protein to inhibit HBV replication, and MxA may have only a minimal effect on the replicative cycle of HBV in the nucleus.     

VEGF真核表达载体的构建及在内皮与心肌细胞内的表达

目的：探讨外源性人VEGF165基因在内皮细胞与心肌细胞内表达的可行性。方法：构建了(vaseular endothelium growth factor,VEGF)与增强型绿色荧光蛋白(enhanced green fluorescent protein，EGFP)基因其表达载体pIRES2—FGFP—VEGF165，以脂质体法转染内皮细胞和心肌细胞，采用荧光显做镜检测内皮细胞与心肌细胞中EGFP的表达，同时利用免疫组织化学方法检测VEGF的表达。结果：成功地构建了真核表达载体pIRES2—EGFP—hVEGF165，采用脂质体法转染内皮细胞与心肌细胞后，经荧光显微镜观察，可见细胞内有EGFP的表达，同时经免疫组化证实有VEGF的表达。结论：采用脂质体法可以成功地将外源性VEGF165基因转染到内皮细胞与心肌细胞中，并进行表达。本研究为今后利用VEGF基因治疗心肌缺血等疾病提供了实验基础。     

Antibodies to endothelial cells in Kawasaki disease lyse endothelial cells without cytokine pretreatment

Kawasaki disease (KD) is characterized by diffuse vasculitis and marked immune activation. To confirm the presence of antiendothelial cell antibodies (AECA) and cytotoxicity of AECA, we investigated the presence of AECA using ELISA and cytotoxicity of AECA in KD. Sera from patients with acute KD were assessed for binding to human umbilical vein endothelial cells (HUVEC) using a cell-based ELISA, and for cytotoxicity against HUVEC as indicated by the conversion of a tetrazolium salt (MTT) into a coloured product. IgM AECA were detected in 8/19 KD sera, IgG AECA were detected in 5/19 KD sera. Significant differences in both AECA titres existed between patients and febrile and afebrile controls. Six out of 19 patients showed complement-dependent cytotoxicity against HUVEC. Cytotoxicity was significantly enhanced by pretreating HUVEC with tumour necrosis factor (TNF), and reduced by incubation with gammaglobulin. Serum titres of IgM AECA in the KD patients were positively correlated with cytotoxicity. Findings suggest that IgM AECA mediates complement-dependent cytotoxicity against endothelial cells in patients with KD, and gammaglobulin may reduce complement-dependent cytotoxicity of AECA against endothelial cells.     

汉滩病毒感染血管内皮细胞引起TLR4表达上调

目的 探讨汉滩病毒感染血管内皮细胞后,Toll样受体(TRY)分子的表达变化,为抗感染免疫和致病机制研究提供重要资料.方法 分别用LPS,CL097,Poly I:C以及汉滩病毒76-118刺激血管内皮细胞,6 h后提取总RNA,进行反转录获得cDNA,再分别用各自的引物进行PCR反应,产物用1%琼脂糖凝胶电泳分析,并用间接免疫荧光测定汉滩病毒感染血管内皮细胞后TLR4的表达.结果 汉滩病毒刺激感染后,血管内皮细胞TLR2、TLR4转录水平增高,TLR3转录水平降低,细胞膜表面的TLR4表达上调.结论汉滩病毒76-118感染血管内皮细胞后,可以引起TLRs分子转录水平发生改变,其中TLR4表达上调,固有免疫参与了汉滩病毒致病过程.