B7-H1 (CD274) inhibits the development of herpetic stromal keratitis (HSK)

The co-signaling molecule B7-H1 (CD274) functions as both a co-inhibitor through programmed death-1 (PD-1) receptor and a co-stimulator via an as-yet-unidentified receptor on T cells. We investigated the physiological role of endogenous B7-H1 in the pathogenesis of herpetic stromal keratitis (HSK) caused by herpes simplex virus type 1 (HSV-1). Following HSV-1 infection of the cornea of mice, B7-H1 expression was up-regulated in the CD11b+ macrophage population in the draining lymph nodes (dLN) and in the inflamed cornea. In addition, HSV-1 infection significantly increased PD-1 expression on CD4+ T cells in the dLN and inflamed cornea. The administration of antagonistic B7-H1 monoclonal antibody resulted in the proliferation of HSV-specific CD4+ T cells that secreted interferon (INF)-gamma, and inhibited the apoptosis of HSV-specific CD4+ T cells, which exaggerated HSK. These results strongly suggest that the B7-H1 may be involved in suppression of the development of HSK.     

乙型肝炎、肝硬变和肝癌中HBxAg的表达及其在肝癌发生中的作用

对３７９例良、恶性肝组织进行的免疫组织化学研究显示,３３％的慢性迁延性肝炎（６／１８）、７６％的慢性活动性肝炎（２６／３４）、９２％的肝硬变（５７／６２）和９７％的肝细胞性肝癌（ＨＣＣ）（５８／６０）中有ＨＢｘＡｇ表达,阳性率高于ＨＢｓＡｇ或ＨＢｃＡｇ。癌周肝中的ＨＢｘＡｇ阳性率显著高于非癌周肝。与其它２种ＨＢＶ抗原不同,ＨＢｘＡｇ表达在细胞类型上有较明显的选择性,在肝小多角细胞（ＳＰＬＣ）、小细胞性不典型增生（ＳＣＤ）及ＨＣＣ中较强。与ＩＧＦⅡ、ｃ－ｅｒｂＢ－２、ｃ－ｍｙｃ和ＥＧＦ－Ｒ表达进行的对照研究表明ＨＢｘＡｇ与ＩＧＦⅡ和ｃ－ｅｒｂＢ－２这２种ＨＣＣ发生相关基因的表达关系密切。ＰＣＮＡ染色结果显示ＨＢｘＡｇ阳性组织的细胞增殖活性显著高于ＨＢｘＡｇ阴性组织。我们的结果还表明ＨＢｘＡｇ表达与肝细胞不典型增生的发生和进展有关、提出ＨＢＶＸ基因可能通过其表达产物（ＨＢｘＡｇ）首先激活ＩＧＦⅡ、ｃ－ｅｒｂＢ－２基因,继而引起显著的ＳＰＬＣ增生和ＳＣＤ而参与ＨＣＣ发生的．     

Upregulation of B7-H1 expression is associated with macrophage infiltration in hepatocellular carcinomas

The overexpression of B7-H1 in hepatocellular carcinoma (HCC) mediates HCC immune escape and obstructs the immunotherapy based on tumor-specific CD8+ T cells. Tumor-associated macrophages (TAM) are a major component of cancer-related inflammation and play a central role in tumor promotion. To classify the mechanism underlying the overexpression of B7-H1 in HCC, we examined B7-H1 expression and TAM infiltration in 63 cases of human HCC samples using immunohistochemistry method and found that B7-H1 overexpression was associated with TAM infiltration in HCC tissues. Furthermore, B7-H1 expression was upregulated at both mRNA level and protein level in HCC cells (BEL-7402 and SMMC-7721) cocultured with macrophages in a transwell system. The upregulation of B7-H1 expression induced by macrophage was inhibited by blocking NF-κB or STAT3 signal pathways. These results suggest that overexpression of B7-H1 in HCC may be induced by inflammatory microenvironment involving macrophages and imply that anti-inflammation therapy might be preventive for immune escape and assistant for immunotherapy of HCC.     

The X protein of hepatitis B virus activates hepatoma cell proliferation through repressing melanoma inhibitory activity 2 gene

Hepatocellular carcinoma (HCC) is the fourth leading cause of cancer deaths globally. Chronic hepatitis B virus (HBV) infection accounts for over 75% of all HCC cases; however, the molecular pathogenesis of HCC is not well understood. In this study, we found that the expression of the newly identified gene melanoma inhibitory activity 2 (MIA2) was reduced by HBV infection in vitro and in vivo, and that HBV X protein (HBx) plays a major role in this regulation. Recent studies have revealed that MIA2 is a potential tumor suppressor, and that, in most HCCs, MIA2 expression is down-regulated or lost. We found that the knock-down of MIA2 in HepG2 cells activated cell growth and proliferation, suggesting that MIA2 inhibits HCC cell growth and proliferation. In addition, the over-expression of HBx alone induced cell proliferation, whereas MIA2 over-expression impaired the HBx-mediated induction of proliferation. Taken together, our results suggest that HBx activates hepatoma cell growth and proliferation through repression of the potential tumor suppressor MIA2.     

Hepatitis B Virus HBx Activates Notch Signaling via Delta-Like 4/Notch1 in Hepatocellular Carcinoma

Hepatitis virus B (HBV) infection is one of the major causes of hepatocellular carcinomas (HCC). HBx protein encoded in HBV genome is one of the key viral factors leading to malignant transformation of infected cells. HBx functions by interfering with cellular functions, causing aberration in cellular behaviour and transformation. Notch signalling is a well-conserved pathway involved in cellular differentiation, cell survival and cell death operating in various types of cells. Aberration in the Notch signalling pathways is linked to various tumors, including HCC. The role of HBx on the Notch signalling in HCC, however, is still controversial. In this study, we reported that HBV genome-containing HCC cell line HepG2 (HepG2.2.15) expressed higher Notch1 and Delta-like 4 (Dll4), compared to the control HepG2 without HBV genome. This upregulation coincided with increased appearance of the cleavage of Notch1, indicating constitutively activated Notch signalling. Silencing of HBx specifically reduced the level of Dll4 and cleaved Notch1. The increase in Dll4 level was confirmed in clinical specimens of HCC lesion, in comparison with non-tumor lesions. Using specific signalling pathway inhibitors, we found that MEK1/2, PI3K/AKT and NF-κB pathways are critical for HBx-mediated Dll4 upregulation. Silencing of HBx clearly decreased the level of phosphorylation of Akt and Erk1/2. Upon silencing of Dll4 in HepG2.2.15, decreased cleaved Notch1, increased apoptosis and cell cycle arrest were observed, suggesting a critical role of HBx-Dll4-Notch1 axis in regulating cell survival in HCC. Furthermore, clonogenic assay confirmed the important role of Dll4 in regulating cell survival of HBV-genome containing HCC cell line. Taken together, we reported a link between HBx and the Notch signalling in HCC that affects cell survival of HCC, which can be a potential target for therapy.     

HBV影响XRN2基因在HepG2-H7细胞中表达的机制研究

目的利用稳定表达HBV的HepG2-H7细胞,研究HBV对XRN2基因表达的调控,并对其作用机制进行初步探讨。方法用RT—PCR和Real-time PCR的方法检测HepG2细胞及稳定表达HBV的HepG2-H7细胞中XRN2在mRNA水平的表达差异。构建XRN2启动子的萤火虫荧光素酶报告质粒,分别转染HepG2细胞及HepG2-H7细胞,检测HBV对XRN2启动子的影响。将XRN2启动子质粒与HBV4种蛋白的真核表达质粒共转染HepG2细胞,寻找对启动子影响较大的HBV蛋白。结果RT—PCR和Real-time PCR的结果显示XRN2在HepG2-H7细胞中的表达较HepG2细胞有所下降。荧光素酶活性分析显示HBV能抑制XRN2启动子的活性,且HBx和HBp蛋白在这一过程中起主要作用。结论HBV蛋白可以通过抑制XRN2启动子活性调节其在HepG2-H7细胞中的表达。     

KLF6 transcription factor protects hepatocellular carcinoma-derived cells from apoptosis

Hepatocellular carcinoma (HCC) is a major public health concern because of the absence of early diagnosis and effective treatments. Efficient diagnosis modalities and therapies to treat HCC are needed. Kruppel-like factor (KLF) family members, such as KLF6, are involved in cell proliferation and differentiation. KLF6 is inactivated in solid tumors, which may contribute to pathogenesis. However, KLF6 status in HCC is controversial. Thus, we undertook the characterization of KLF6 expression and function in HCC and HCC-derived cell lines. We found that HCC, HepG2 and HuH7 cells expressed KLF6 messenger ribonucleic acid and protein. Next, using RNA interference, we demonstrated that inhibiting KLF6 expression in vitro strongly impaired cell proliferation-induced G1-phase arrest, inhibited cyclin-dependent kinase 4 and cyclin D1 expression, and subsequent retinoblastoma phosphorylation. Finally, KLF6 silencing caused p53 upregulation and inhibited Bcl-xL expression, to induce cell death by apoptosis. Taken together, these data demonstrated that KLF6 is essential for HCC-derived cells to evade apoptosis.     

HBV X基因的表达及在真核细胞中对内质网压力的作用

运用PCR技术获得HBx基因,分别克隆到原核表达载体pET-his和真核表达载体pcDNA3.1(-)上。重组质粒pET-his-HBx转化大肠杆菌BL21(DE3)后,IPTG诱导表达,利用Ni柱纯化后的蛋白免疫家兔,获得特异性的抗-HBx兔抗血清。重组质粒pcDNA3.1(-)-HBx分别转染HepG2和Hep3B细胞系后,经RT-PCR和Westernblot检测,证明HBx可以在这两种细胞系中表达。通过报告基因的表达研究了HBx对XBP1和GRP78启动子的激活活性,结果表明瞬时转染HBx的细胞系中,XBP1和GRP78启动子介导的荧光素酶活性比相应的对照细胞增加了3～7倍。通过RT-PCR分析证明,转染了HBx的细胞中XBP1mRNA发生了剪切。因此,可以初步推断HBx在HepG2和Hep3B细胞中的表达可以引起内质网压力反应,为进一步阐明HBx表达对内质网的影响和肝脏病原发生机制奠定了基础。     

乙肝病毒感染对细胞基本自噬的影响

【目的】慢性乙肝病毒(Hepatitis B virus,HBV)感染在肝硬化和肝癌的发生过程中起着重要的作用,通过研究HBV感染对细胞基本自噬的影响,为HBV感染诱发肝癌以及HBV的免疫逃逸机理研究提供新的思路。【方法】本研究利用乙肝病毒表达质粒瞬时或稳定转染不同肝细胞,通过计数绿色荧光蛋白(greenfluorescent protein,GFP)聚集数目检测自噬小体形成,western blot检测LC3(microtubule-associated proteinlight chain 3,微管相关蛋白质轻链3)脂酰化和p62的降解,通过构建HBV B型和C型X蛋白(HBx)的表达质粒并瞬时转染肝癌细胞和正常肝细胞,对不同基因型X蛋白对细胞自噬的影响进行了分析。【结果】乙肝病毒感染后促进了LC3的脂酰化和p62的降解,增加了自噬小体的形成,增强了细胞的基本自噬。进一步研究发现,HBV感染增强的细胞基本自噬水平由HBx所引发,且C型HBx比B型对细胞基本自噬的增加更加显著。【结论】HBV通过HBx增强细胞的基本自噬,且不同基因型HBx对细胞基本自噬的增强程度不同,为进一步阐明HBV感染机理奠定了基础。     

Characterization of a Soluble B7-H3 (sB7-H3) Spliced from the Intron and Analysis of sB7-H3 in the Sera of Patients with Hepatocellular Carcinoma

B7-H3 is a recently discovered member of the B7 superfamily molecules and has been found to play a negative role in T cell responses. In this study, we identified a new B7-H3 isoform that is produced by alternative splicing from the forth intron of B7-H3 and encodes the sB7-H3 protein. Protein sequence analysis showed that sB7-H3 contains an additional four amino acids, encoded by the intron sequence, at the C-terminus compared to the ectodomain of 2Ig-B7-H3. We further found that this spliced sB7-H3 plays a negative regulatory role in T cell responses and serum sB7-H3 is higher in patients with hepatocellular carcinoma (HCC) than in healthy donors. Furthermore, we found that the expression of the spliced sb7-h3 gene is higher in carcinoma and peritumor tissues than in PBMCs of both healthy controls and patients, indicating that the high level of serum sB7-H3 in patients with HCC is caused by the increased expression of this newly discovered spliced sB7-H3 isoform in carcinoma and peritumor tissues.     

Investigation of microRNA expression changes in HepG2 cell line in presence of URG4/URGCP and in absence of URG4/URGCP suppressed by RNA interference

Hepatocellular carcinoma (HCC) originates from liver cells and is one of the most common malignant cancers in the world. microRNAs (miRNA), are single strand non-coding RNA molecules with the length of 18–25 nucleotides. miRNAs play an important role in the development of HCC, i.e., miRNAs have a significant impact on multistep hepatocellular carcinogenesis including cellular migration and invasion. URG4/URGCP (up-regulated gene-4/upregulator of cell proliferation) is up-regulated in the presence of HBxAg and has been identified and characterized by Satiroglu-Tufan et al. The full-length URG4/URGCP is 3.607?kb. Overexpression of URG4/URGCP in the presence of HBV X protein may function as a putative oncogene that significantly contributes to multi-step hepatocarcinogenesis. In this study, we aimed to investigate potential miRNA expression changes in HepG2 cell line model system in the presence of URG4/URGCP and in the absence of URG4/URGCP, which was suppressed by RNA interference. To functionally characterize URG4/URGCP, independent cultures of HepG2 cells were stably transfected with pcDNA3 or pcDNA3-URG4/URGCP. Relative quantification of whole genome miRNAs was analyzed by RT-PCR using human whole genome miRNA qPCR profiling kits. Among the 1,034 human miRNAs investigated by the arrays, 77 miRNAs were up-regulated and nine miRNAs were down-regulated in the presence of URG4/URGCP. In conclusion, we have analyzed miRNA profiles in HepG2 cells in presence or absence of URG4/URGCP gene using RNA interference. Some of these miRNAs may play roles in URG4/URGCP gene related disease development through the regulation of different signaling pathways.     

肝癌中HBV和HCV基因和抗原的分布及意义

采用原位分子杂交方法检测HCV RNA及HBV X基因;采用免疫组织化学方法研究HCV核心抗原,非结构区C33c抗原及HBxAg在肝细胞肝癌中的定位及分布。结果表明（1）HCV RNA、HBV X基因在肝细胞肝癌组织检出率分别为40％（55／136）和82％（112／136）。HCV RNA定位于癌细胞的胞浆内,阳性细胞呈散在、灶状及弥漫分布三种形式;HBV X基因在肝癌细胞中的分布呈胞浆型、核型及核浆型,阳性细胞也呈上述三种分布形式;（2）HCV C33c抗原、核心抗原在肝细胞肝癌中的阳性率为81％（133／164）及86％（141／164）。C33c抗原定位于癌细胞及肝细胞的浆内;核心抗原毁定位于癌细胞核中,又可定位于胞浆中。C33c抗原阳性细胞以灶状分布为主;而核心抗原阳性细胞在癌组织以弥漫核阳性常见,在癌旁肝组织以胸浆阳性为主;（3）HBxAg在肝细胞肝 癌中的检出率为75％（123／164）,C33c和HBxAg二者同时阳性占63％（103／164）。HCV感染在我国肝细胞肝癌中比较普遍,HCV和HBV重叠感染占相当比例,可能在肝细胞肝癌的发生中起着重要作用。     

ShRNA-Targeted COMMD7 Suppresses Hepatocellular Carcinoma Growth

Background

COMMD7 is a newly identified gene overexpressed in hepatocellular carcinoma (HCC) and associated with tumor invasion and poor prognosis. We aim to examine the biological function of COMMD7 in HCC by shRNA silencing.

Methods

COMMD7 expressions were examined in human HCC cell lines HepG2, Huh7, Hep3B, HLE, HLF, SK-Hep-1 and PLC/PRF/5 cells. Recombinant pGenesil-COMMD7-shRNA was transfected into COMMD7-abundant HepG2 cells to silence COMMD7 expression. The effects of COMMD7 silencing on HepG2 cell proliferation in vitro and xenograft tumor growth in vivo were evaluated. Flow cytometry profiling was used to detect the presence of apoptosis in COMMD7-silenced HepG2 cells and to differentiate cell cycle distribution. Electrophoretic mobility shift assay and luciferase reporter assays to examine the activities of nuclear factor-kappaB (NF-κB) signaling pathways in response to tumor necrosis factor (TNF)-α in COMMD7-silenced HepG2 cells.

Results

COMMD7 expression level was abundance in HepG2 and SK-Hep-1 cells. COMMD7 was aberrantly overexpressed in HepG2 cells, whilst pGenesil-COMMD7-shRNA exhibited a maximal inhibition rate of 75%. COMMD7 silencing significantly reduced HepG2 cell proliferation and colony formation. The knockdown of COMMD7 resulted in an increased apoptosis and cell cycle arrest at S-phase. COMMD7 knockdown also exhibited an antineoplastic effect in vivo, which manifested as tumor xenograft growth retardation. COMMD7 silencing also suppressed the responsiveness of NF-κB signaling pathway to the stimulation with TNF-α in vitro. Moreover, the similar suppressive effects of COMMD7 silence on SK-Hep-1 cells were also observed.

Conclusions

COMMD7 contributes to HCC progression by reducing cell apoptosis and overcoming cell cycle arrest. The proliferative and antiapoptotic effects of COMMD7 may be mediated by NF-κB signaling pathway.     

B7-H1 Expression Is Associated with Poor Prognosis in Colorectal Carcinoma and Regulates the Proliferation and Invasion of HCT116 Colorectal Cancer Cells

Background And Objective

The investigation concerning the B7-H1 expression in colorectal cancer cells is at an early stage. It is unclear whether B7-H1 expression may have diagnostic or prognostic value in colorectal carcinoma. Additionally, how B7-H1 is associated with the clinical features of colorectal carcinoma is not known. In order to investigate the relationship between B7-H1 and colorectal cancer, we analyzed B7-H1 expression and its effect in clinical specimens and HCT116 cells.

Methods

Paraffin-embedded specimens from 143 eligible patients were used to investigate the expression of CD274 by immunohistochemistry. We also examined whether B7-H1 itself may be related to cell proliferation, apoptosis, migration and invasion in colon cancer HCT116 cells.

Results

Our results show that B7-H1 was highly expressed in colorectal carcinoma and was significantly associated with cell differentiation status and TNM (Tumor Node Metastasis) stage. Patients with positive B7-H1 expression showed a trend of shorter survival time. Using multivariate analysis, we demonstrate that positive B7-H1 expression is an independent predictor of colorectal carcinoma prognosis. Our results indicate that B7-H1 silencing with siRNA inhibits cell proliferation, migration and invasion. Furthermore, cell apoptosis was also increased by B7-H1 inhibition.

Conclusions

Positive B7-H1 expression is an independent predictor for colorectal carcinoma prognosis. Moreover, knockdown of B7-H1 can inhibit cell proliferation, migration and invasion.     

Glucose-regulated Protein 78 Is an Intracellular Antiviral Factor against Hepatitis B Virus

Hepatitis B virus (HBV) infection is a global public health problem that plays a crucial role in the pathogenesis of chronic hepatitis, cirrhosis, and hepatocellular carcinoma. However, the pathogenesis of HBV infection and the mechanisms of host-virus interactions are still elusive. In this study, two-dimensional gel electrophoresis and mass spectrometry-based comparative proteomics were applied to analyze the host response to HBV using an inducible HBV-producing cell line, HepAD38. Twenty-three proteins were identified as differentially expressed with glucose-regulated protein 78 (GRP78) as one of the most significantly up-regulated proteins induced by HBV replication. This induction was further confirmed in both HepAD38 and HepG2 cells transfected with HBV-producing plasmids by real time RT-PCR and Western blotting as well as in HBV-infected human liver biopsies by immunohistochemistry. Knockdown of GRP78 expression by RNA interference resulted in a significant increase of both intracellular and extracellular HBV virions in the transient HBV-producing HepG2 cells concomitant with enhanced levels of hepatitis B surface antigen and e antigen in the culture medium. Conversely overexpression of GRP78 in HepG2 cells led to HBV suppression concomitant with induction of the positive regulatory circuit of GRP78 and interferon-β1 (IFN-β1). In this connection, the IFN-β1-mediated 2′,5′-oligoadenylate synthetase and RNase L signaling pathway was noted to be activated in GRP78-overexpressing HepG2 cells. Moreover GRP78 was significantly down-regulated in the livers of chronic hepatitis B patients after effective anti-HBV treatment (p = 0.019) as compared with their counterpart pretreatment liver biopsies. In conclusion, the present study demonstrates for the first time that GRP78 functions as an endogenous anti-HBV factor via the IFN-β1-2′,5′-oligoadenylate synthetase-RNase L pathway in hepatocytes. Induction of hepatic GRP78 may provide a novel therapeutic approach in treating HBV infection.Hepatitis B virus infection is a global public health problem. An estimated 2 billion (one-third of the world''s population) people are infected with HBV¹ worldwide, and more than 400 million are chronic hepatitis B (CHB) carriers (1). Epidemiological studies have shown that HBV infection is one of the major risk factors for chronic hepatitis, liver fibrosis, and hepatocellular carcinoma (HCC). Every year, over 1 million people die of HBV-related liver diseases, 30–50% of which are attributed to HCC (2). In China, more than 130 million (10% of the national population) people are suffering from CHB (3), and HCC has been ranked as the second major cause of cancer-related death since 1990 (4). However, the limited efficacy of antiviral therapies, high rates of post-treatment HBV relapse, and the emergence of drug-resistant viral mutants have greatly hindered the effective management of CHB infection. Therefore, it is of prime importance to understand the mechanisms of HBV-host interactions during malignant transformation in CHB infection to identify novel therapeutic anti-HBV targets.Because human HBV is incapable of infecting hepatocytes in vitro efficiently and the availability of reliable in vitro culture systems that favor HBV replication is limited, the pathogenetic studies of HBV and the development of anti-HBV drugs have long been hampered. HepAD38 and HepG2.2.15, both of which are derived from HepG2 cells and integrated with a greater than 1-unit-length HBV genome, have been widely accepted and are well established cell lines for the study of the HBV life cycle and screening potential HBV inhibitors since the late 1990s (5, 6). Recently comparative proteomics analysis of the HBV-expressing HepG2.2.15 cells and the parental HepG2 cells has been performed in two independent laboratories to characterize the altered proteome profile induced by HBV (7, 8). However, the different genetic backgrounds of HepG2.2.15 and HepG2 may lead to an inaccurate evaluation of the impact of HBV replication on host genes. When compared with HepG2.2.15 cells, which produce HBV particles in a continuous manner, HepAD38 cells produce higher levels of HBV DNA in a controllable and inducible way (5). HBV production in HepAD38 is under the strict control of a tetracycline-responsive promoter; therefore, a direct comparison of cellular characteristics with or without HBV replication in HepAD38 is easily achieved. To date, changes in the proteome profile of HepAD38 induced by HBV replication have not been reported. In this study, we performed comparative proteomics to globally analyze the host response to HBV by using an inducible HBV-producing cell line, HepAD38. The combination of two-dimensional gel electrophoresis (2-DE) and MALDI-TOF MS revealed that 23 cellular proteins were differentially expressed when HBV replicated. Among them, GRP78, which was one of the most highly up-regulated proteins, was further selected for functional assessment.     

Expression of programmed death 1 ligands by murine T cells and APC

Programmed death 1 (PD-1) is a new member of the CD28/CTLA-4 family, which has been implicated in the maintenance of peripheral tolerance. Two ligands for PD-1, namely, B7-H1 (PD-L1) and B7-DC (PD-L2), have recently been identified as new members of the B7 family but their expression at the protein level remains largely unknown. To characterize the expression of B7-H1 and B7-DC, we newly generated an anti-mouse B7-H1 mAb (MIH6) and an anti-mouse B7-DC mAb (TY25). MIH6 and TY25 immunoprecipitated a single molecule of 43 and 42 kDa from the lysate of B7-H1 and B7-DC transfectants, respectively. Flow cytometric analysis revealed that B7-H1 was broadly expressed on the surface of mouse tumor cell lines while the expression of B7-DC was rather restricted. PD-1 was expressed on anti-CD3-stimulated T cells and anti-IgM plus anti-CD40-stimulated B cells at high levels but was undetectable on activated macrophages or DCs. B7-H1 was constitutively expressed on freshly isolated splenic T cells, B cells, macrophages, and dendritic cells (DCs), and up-regulated on T cells by anti-CD3 stimulation on macrophages by LPS, IFN-gamma, GM-CSF, or IL-4, and on DCs by IFN-gamma, GM-CSF, or IL-4. In contrast, B7-DC expression was only inducible on macrophages and DCs upon stimulation with IFN-gamma, GM-CSF, or IL-4. The inducible expression of PD-1 ligands on both T cells and APCs may suggest new paradigms of PD-1-mediated immune regulation.     

Enhanced expression of matrix metalloproteinase-9 by hepatitis B virus infection in liver cells

The hepatitis B virus (HBV) is a major cause of human liver disease, including hepatocellular carcinoma (HCC). The prognosis for HCC is largely dependent on the clinicopathological characteristics regarding invasion and metastasis. Enhanced matrix metalloproteinase-9 (MMP-9) expression has been implicated as playing an important role in metastasis and invasion of HCC. However, the relationship between HBV infection and MMP-9 expression in HCC is currently poorly understood. We report here on a study of the levels of MMP-9 and MMP-2 expression in human fetal liver tissue, rat liver tissue, and Chang, HepG2, and Hep3B cells by gelatin zymography. Among these sources, Hep3B cells, which contain the integrated hepatitis B viral genome, continuously secrete the hepatitis B viral surface antigen, and express HBV genomic RNA, expressed high levels of proMMP-9, and a small amount of active MMP-9 was detected in Hep3B cells as assayed by zymography. We investigated the issue of whether HBV infection affects MMP-9 expression, which is known to play an important role in HCC invasion and metastasis. As a first step, human fetal hepatocyte (HFH) and HepG2 (HCC origin, HBV not detected) cells were subjected to infection with HBV, and the resulting infected cells successfully established are hereafter referred to as HFH-T2 and HepG2-HBV. The expression of MMP-9 was upregulated by the infected HBV in HFH-T2 and HepG2-HBV cells, as assayed by zymography, Northern blot, and Western blot analysis, and small amounts of active MMP-9 were detected in HFH-T2 and HepG2-HBV cells as assayed by zymography. The activation of the immature proMMP-9 to the mature MMP-9 could be induced by plasmin treatment. The activation of proMMP-9 was increased to a greater extent with plasmin treatment than without plasmin in HFH-T2 and HepG2-HBV cells but the addition of recombinant TIMP-1 inhibited the activation of proMMP-9. Finally, the addition of plasmin to the invasion assay using Matrigel resulted in an increase in invasiveness of HFH-T2 and HepG2-HBV cells, as well as MMP-9 activation, but the treatment with TIMP-1 inhibited the invasiveness of HFH-T2 and HepG2-HBV cells as well as MMP-9 activation. We conclude from these findings that HBV infection of hepatocytes and HepG2 cells affected the upregulation of MMP-9 expression and MMP-9 activation and, thus, increased the invasion potential by plasmin. To our knowledge, this is a first report showing that an HBV infection is linked to the upregulation of MMP-9 in HCC.     

Blockade of B7-H1 suppresses the development of chronic intestinal inflammation

A newly identified costimulatory molecule, programmed death-1 (PD-1), provides a negative signal that is essential for immune homeostasis. However, it has been suggested that its ligands, B7-H1 (PD-L1) and B7-dendritic cells (B7-DC; PD-L2), could also costimulate T cell proliferation and cytokine secretion. Here we demonstrate the involvement of PD-1/B7-H1 and B7-DC interaction in the development of colitis. We first examined the expression profiles of PD-1 and its ligands in both human inflammatory bowel disease and a murine chronic colitis model induced by adoptive transfer of CD4(+)CD45RB(high) T cells to SCID mice. Second, we assessed the therapeutic potential of neutralizing anti-B7-H1 and/or B7-DC mAbs using this colitis model. We found significantly increased expression of PD-1 on T cells and of B7-H1 on T, B, and macrophage/DCs in inflamed colon from both inflammatory bowel disease patients and colitic mice. Unexpectedly, the administration of anti-B7-H1, but not anti-B7-DC, mAb after transfer of CD4(+)CD45RB(high) T cells suppressed wasting disease with colitis, abrogated leukocyte infiltration, and reduced the production of IFN-gamma, IL-2, and TNF-alpha, but not IL-4 or IL-10, by lamina propria CD4(+) T cells. These data suggest that the interaction of PD-1/B7-H1, but not PD-1/B7-DC, might be involved in intestinal mucosal inflammation and also show a possible role of interaction between B7-H1 and an as yet unidentified receptor for B7-H1 in inducing T cell activation.