Epstein-Barr virus-associated gastric carcinoma: a newly defined entity

Epstein-Barr virus (EBV)-associated gastric carcinoma (EBVaGC) is a recently recognized entity, which is defined by the presence of EBV in the gastric carcinoma cells. EBVaGC represents about 10% of gastric carcinoma worldwide, and >80,000 patients are estimated to develop EBVaGC annually. EBVaGC shows some distinct clinicopathologic characteristics, such as male predominance, predisposition to the proximal stomach, and a high proportion in diffuse-type gastric carcinomas. Besides, EBVaGC also shows characteristic molecular abnormality, that is, global and nonrandom CpG-island methylation of the promoter region of many cancer-related genes, which causes downregulation of their expression. Moreover, EBVaGC has a relative favorable prognosis. The uniform presence of EBV-encoded small RNA in tumor cells but not in the surrounding normal epithelial cells, and the detection of monoclonal EBV episomes in EBVaGC, strongly suggests that EBV play an etiological role in gastric carcinogenesis. Therefore, EBVaGC should be regarded as a distinct entity of gastric carcinoma, although it only accounts for a relatively small fraction of total gastric carcinomas. In this review, the epidemiological and clinicopathologic features of EBVaGC and the genetic abnormalities of EBVaGC cell including chromosomal and epigenetic abnormalities are described. The roles of EBV in gastric carcinogenesis are discussed. We make an emphasis on the EBV latency pattern and genome polymorphisms as well as local immunity in EBVaGC. In addition, the treatment of EBVaGC is also briefly discussed. Taken together, this review aims to give the reader a full understanding of a newly defined entity of gastric carcinoma, EBVaGC.     

Immunosuppression for inflammatory bowel disease does not influence Epstein–Barr viral load in the short-term

IntroductionImmunomodulators and biologics are two of the main drugs used for the treatment of inflammatory bowel disease (IBD). Some of these agents have been associated with certain infections and lymphoproliferative disorders, including Epstein–Barr virus (EBV) infection. Our aim was to determine the influence of immunosuppression in the EBV viral load in patients with IBD.Materials and methodsWe prospectively included naïve patients with IBD who were starting immunosuppressive therapy in four IBD Units. All patients were assessed at baseline and four months after starting immunosuppression for clinical disease activity, biomarkers, EBV serology (IgM VCA, IgG VCA and IgG EBNA) and viral load.ResultsThirty-two patients were included. At baseline, all patients showed positive results for IgG VCA or IgG EBNA with undetectable EBV viral load. No patient showed detectable EBV viral load after starting the immunosuppressive therapy.ConclusionImmunosuppression did not influence on EBV viral load in the short-term in naïve IBD patients.     

Deiminated Epstein‐Barr virus nuclear antigen 1 is a target of anti–citrullinated protein antibodies in rheumatoid arthritis

Objective

To test the hypothesis that deimination of viral sequences containing Arg–Gly repeats could generate epitopes recognized by anti–citrullinated protein antibodies (ACPAs) that are present in rheumatoid arthritis (RA) sera.

Methods

Multiple antigen peptides derived from Epstein‐Barr virus (EBV)–encoded Epstein‐Barr nuclear antigen 1 (EBNA‐1) were synthesized, substituting the arginines with citrulline, and were used to screen RA sera. Anti–cyclic citrullinated peptide antibodies were purified by affinity chromatography and tested on a panel of in vitro deiminated proteins. Their ability to bind in vivo deiminated proteins was evaluated by immunoprecipitation, using EBV‐infected cell lines.

Results

Antibodies specific for a peptide corresponding to the EBNA‐1^35–58 sequence containing citrulline in place of arginine (viral citrullinated peptide [VCP]) were detected in 50% of RA sera and in <5% of normal and disease control sera. In addition, affinity‐purified anti‐VCP antibodies from RA sera reacted with filaggrin‐derived citrullinated peptides, with deiminated fibrinogen, and with deiminated recombinant EBNA‐1. Moreover, anti‐VCP antibodies immunoprecipitated, from the lysate of calcium ionophore–stimulated lymphoblastoid cell lines, an 80‐kd band that was reactive with a monoclonal anti–EBNA‐1 antibody and with anti–modified citrulline antibodies.

Conclusion

These data indicate that ACPAs react with a viral deiminated protein and suggest that EBV infection may play a role in the induction of these RA‐specific antibodies.

     

DNA methyltransferase3a expression is an independent poor prognostic indicator in gastric cancer

AIM: To explore the alteration of DNA methyltransferase expression in gastric cancer and to assess its prognostic value.METHODS: From April 2000 to December 2010, 227 men and 73 women with gastric cancer were enrolled in the study. The expression of DNA methyltransferases (DNMTs), including DNMT1, DNMT3a and DNMT3b, in the 300 cases of gastric carcinoma, of which 85 had paired adjacent normal gastric mucus samples, was evaluated by immunohistochemistry using a tissue microarray. Serum anti-Helicobacter pylori (H. pylori) IgG was detected by enzyme-linked immunosorbent assay (ELISA). The relationships between the above results and the clinicopathological characteristics were analyzed. Their prognostic value was evaluated using the Cox proportional hazards model.RESULTS: In gastric cancer, expression of DNMTs was mainly seen in the nucleus. Weak staining was also observed in the cytoplasm. Expression of DNMT1, DNMT3a and DNMT3b in gastric cancer was significantly higher compared to that in the paired control samples (60.0% vs 37.6%, 61.2% vs 4.7%, and 94.1% vs 71.8%, P < 0.01). The overall survival rate was significantly higher in the DNMT3a negative group than in the DNMT3a positive group in gastric cancer patients (Log-rank test, P = 0.032). No significant correlation was observed between DNMT1 and DNMT3b expression and the overall survival time (Log-rank test, P = 0.289, P = 0.347). Multivariate regression analysis indicated that DNMT3a expression (P = 0.025) and TNM stage (P < 0.001), but not DNMT1 (P = 0.54) or DNMT3b (P = 0.62), were independent prognostic factors in gastric cancer. H. pylori infection did not induce protein expression of DNMTs.CONCLUSION: The results suggest that expression of DNMT3a is an independent poor prognostic indicator in gastric cancer. DNMT3a might play an important role in gastric carcinogenesis.     

An altered immune response to Epstein‐Barr nuclear antigen 1 in pediatric systemic lupus erythematosus

Objective

New examples support the concept that host immune responses to pathogenic organisms can act as the nidus for autoimmunity. Two such examples implicate the Epstein‐Barr virus (EBV) in systemic lupus erythematosus (SLE), i.e., data consistent with SLE anti‐Sm and anti–60‐kd Ro autoantibodies emerging from distinct humoral immune responses to Epstein‐Barr nuclear antigen 1 (EBNA‐1). We undertook this study to further test whether the humoral immune response to EBNA‐1 is a risk factor for pediatric SLE.

Methods

Sera from pediatric lupus patients and healthy matched controls were tested for anti–EBNA‐1 by Western blotting and enzyme‐linked immunosorbent assay (ELISA). To define the fine specificity of their anti–EBNA‐1 humoral immune response, fragments of EBNA‐1 and the maximally overlapping unique octapeptides of EBNA‐1 were tested by modified ELISAs.

Results

All 36 pediatric SLE patient sera tested recognized EBNA‐1, while sera from only 25 of 36 matched EBV‐positive controls targeted EBNA‐1 (P < 0.005). Epitope mapping revealed that the humoral anti–EBNA‐1 response in pediatric SLE was distinct from and less restricted than that in matched normal individuals. Meanwhile, no significant differences between SLE patient sera and control sera were observed in the responses to other herpesviruses or in binding to sequential epitopes from cytomegalovirus immediate‐early antigen or EBNA‐2.

Conclusion

Anti–EBNA‐1 antibodies are associated with pediatric‐onset SLE. Furthermore, an altered humoral immune response to EBNA‐1, characteristic of SLE, has been found and may be an important SLE susceptibility factor.

     

Epstein–Barr virus (EBV) genotypes among human immunodeficiency virus (HIV)‐related B‐cell Lymphomas and B‐cell post‐transplant lymphoproliferative disorders (B‐PTLD) – late‐onset lymphomas,especially in the HIV setting,are associated with type‐B‐EBV

We investigated 26 B‐cell post‐transplant lymphoproliferative disorders (B‐PTLD) and 15 human immunodeficiency virus‐related aggressive B‐cell lymphomas (HIV‐BCL) from England that were associated with Epstein–Barr virus (EBV) for the polymorphic sequences of the EBV‐encoded nuclear antigen 3C (EBNA3C) gene to distinguish the two different EBV strains. Type‐A‐EBV was identified in 92% of B‐PTLDS and in 53% of HIV‐BCL (P = 0.003). Among HIV‐BCL, patients associated with type‐B‐EBV had been HIV positive for significantly longer when compared to those associated with type‐A (P = 0.037) although there were no correlations with ethnicity, CD4 cell counts or plasma HIV viral load.     

CD8+ T-cell lymphoproliferative disorder associated with Epstein–Barr virus in a patient with rheumatoid arthritis during methotrexate therapy

Abstract

A 75-year-old woman with rheumatoid arthritis (RA) who was receiving methotrexate (MTX) therapy developed Epstein–Barr virus (EBV)-associated CD8⁺ T-cell lymphoproliferative disorder (LPD) and meningoencephalitis. She was successfully treated with acyclovir and corticosteroids plus MTX cessation. T-cell LPD is relatively rare in RA patients receiving MTX. To our knowledge, this is the first report of CD8⁺ T-cell LPD with EBV genome occurring during MTX therapy for RA. EBV infection should be carefully monitored to assess severe EBV-associated complications.     

The Expression and Clinical Significance of DNA Methyltransferase Proteins in Human Gastric Cancer

This study investigates the varied expression of DNA methyltransferase (DNMT) proteins in gastric cancer (GC) and their relationship with the biological behavior of the tissues. Immunohistochemistry was used to detect the expression of the 3 DNMTs in gastric tissues. We discovered that the positive rates of DNMT1, DNMT3a, and DNMT3b expression in GC tissues were 81.6%, 81.6%, and 68.4%, respectively, and they were significantly higher than those of both para-cancerous (39.5%, 50%, and 44.7%) and normal tissues (10.5%, 10.5%, and 7.9%). DNMT1 was well distributed in the cytoplasm and nuclei of tumor cells or glands, while DNMT3a and 3b were well distributed only in the cytoplasm, as shown by staining a dark brown color. A significant correlation between the DNMT1 and DNMT3a proteins (P < 0.01), a low correlation between DNMT3a and DNMT3b (P < 0.05), and no correlation between DNMT1 and DNMT3b (P > 0.05) were observed. DNMT1 protein expression exhibited no correlation with age, lymphnode metastasis, and also tumor differentiation, but it may have had a correlation with gender. The DNMT3 family was not associated with these factors. Therefore, DNMT overexpression is involved in gastric tumorigenesis, but there is no correlation between the DNMTs and the biological behaviors of tissues.     

Clinicopathological and molecular characteristics of Epstein–Barr virus-associated gastric carcinoma: A meta-analysis

There is conflicting data regarding the clinicopathological significance of the risk factors associated with Epstein–Barr virus (EBV)-associated gastric carcinoma (EBVaGC). To address this controversy, we performed a meta-analysis for the clinicopathological and molecular characteristics of EBVaGC. The relevant published studies were reviewed according to the defined selection criteria. The effect sizes of the outcome parameters were estimated by an odds ratio or a weighted mean difference. This meta-analysis included 48 studies that encompassed a total of 9738 patients. The frequency of EBVaGC was 8.8%, and EBVaGC was significantly associated with ethnicity. It was more predominant in men and in younger individuals. Interestingly, EBVaGC was more prevalent in Caucasian and Hispanic patients than in Asian ones. EBVaGC developed most often in the cardia and body, and it generally showed the diffuse histological type. EBV was highly prevalent in the patients with lymphoepithelial carcinoma. EBVaGC was closely associated with remnant cancer and a CpG island methylator-high status, but not with Helicobacter pylori infection, a TP53 expression, and p53 mutation. In addition, EBVaGC was not significantly associated with the depth of invasion, lymph node metastasis, or the clinical stage. The clinicopathological and molecular characteristics of EBVaGC are quite different from those of conventional gastric adenocarcinoma. However, further study is needed to determine the effect of EBV on the survival of EBVaGC patients.     

Propagation and recovery of intact, infectious Epstein–Barr virus from prokaryotic to human cells

With current techniques, genetic alterations of herpesviruses are difficult to perform, mostly because of the large size of their genomes. To solve this problem, we have designed a system that allows the cloning of any γ-herpesvirus in Escherichia coli onto an F factor-derived plasmid. Immortalized B cell lines were readily established with recombinant Epstein–Barr virus (EBV), demonstrating that the F factor-cloned EBV genome has all the characteristics of wild-type EBV. Because any genetic modification is possible in E. coli, this experimental approach opens the way to the genetic analysis of all EBV functions. Moreover, it is now feasible to generate attenuated EBV strains in vitro such that vaccine strains can be designed. Because we incorporated the genes for hygromycin resistance and green fluorescent protein onto the E. coli cloned EBV genome, the still open question of the EBV target cells other than B lymphocytes will be addressed.