High molecular weight complex analysis of Epstein–Barr virus Latent Membrane Protein 1 (LMP-1): Structural insights into LMP-1's homo-oligomerization and lipid raft association

LMP-1 is a constitutively active Tumor Necrosis Factor Receptor analog encoded by Epstein–Barr virus. LMP-1 activation correlates with oligomerization and raft localization, but direct evidence of LMP-1 oligomers is limited. We report that LMP-1 forms multiple high molecular weight native LMP-1 complexes when analyzed by BN-PAGE, the largest of which are enriched in detergent resistant membranes. The largest of these high molecular weight complexes are not formed by purified LMP-1 or by loss of function LMP-1 mutants. Consistent with these results we find a dimeric form of LMP-1 that can be stabilized by disulfide crosslinking. We identify cysteine 238 in the C-terminus of LMP-1 as the crosslinked cysteine. Disulfide crosslinking occurs post-lysis but the dimer can be crosslinked in intact cells with membrane permeable crosslinkers. LMP-1/C238A retains wild type LMP-1 NF-κB activity. LMP-1's TRAF binding, raft association and oligomerization are associated with the dimeric form of LMP-1. Our results suggest the possibility that the observed dimeric species results from inter-oligomeric crosslinking of LMP-1 molecules in adjacent core LMP-1 oligomers.     

Infections and SLE

Viral and bacterial infections may serve as an environmental trigger for the development or exacerbation of systemic lupus erythematosus (SLE) in the genetically predetermined individual. In addition, SLE patients are more prone to develop common (pneumonia, urinary tract infection, cellulitis, sepsis), chronic (tuberculosis), and opportunistic infections possibly due to inherit genetic and immunologic defects (complement deficiencies, mannose-binding lectin [MBL] polymorphisms, elevated Fcgamma III and GM-CSF levels, osteopontion polymorphism), but also due to the broad spectrum immunosuppressive agents that are part of therapy for severe manifestations of the disease. Hence, SLE patients are considered a high-risk population, where identification and treatment of chronic infections such as tuberculosis, hepatitis B or human immunodeficiency virus, are important prior to the institution of immunosuppression so as to prevent reactivation or exacerbation of the infection. Infections in SLE patients remain a source of morbidity and mortality. A caveat often encountered is to distinguish between a lupus flare and an acute infection; in such cases parameters including elevated CRP (and adhesion molecules) may aid in the diagnosis of infection. Recent research has provided convincing evidence that EBV infection may play a major role not only in molecular mimicry but also in aberrations of B cells and apoptosis leading to a state of perpetual heightened immune response in SLE.     

Epstein–Barr virus-positive nodal peripheral T cell lymphomas: Clinicopathologic and gene expression profiling study

Epstein–Barr virus-positive peripheral T cell lymphoma, not otherwise specified (EBV+ PTCL-NOS), in which virtually all neoplastic T cells harbor EBV, is a very rare disease with poor prognosis. To analyze the clinicopathologic characteristics and gene expression profile, we retrospectively collected six cases of EBV+ PTCL-NOS with no known primary immunodeficiency. The patients were 5 men and 1 woman, their age ranging from 48 years to 88 years (median 61.5 years). Lymphadenopathy was the most common presentation. Four patients had underlying disease, including HBV carrier, HCV infection, diabetes mellitus, and prostate cancer. All patients showed fatal clinical course in spite of chemotherapy. Histopathologically, monotonous infiltration of atypical lymphocytes of small to medium size was shown in four patients and medium to large tumor cells in two patients. Five patients showed CD4−/CD8+/bF-1+ phenotype with TIA-1 expression. In gene expression analysis using mRNA microarray, genes differentially expressed in EBV+ PTCL-NOS compared to normal reactive lymph nodes included 1515 genes (Mann–Whitney U-test p < 0.05, folder change ≥4 times). Enriched functional annotation terms by DAVID were mostly related to immune response, defense response, cell-to-cell signaling, and membrane signaling. Especially, the genes involved in B cell differentiation or activation were mostly down-regulated, and T cell activation was mostly suppressed by down-regulation of activation genes and up-regulation of regulatory genes. Genes associated with cytotoxic activity were mostly up-regulated. Based on its peculiar clinical, histopathologic, and gene expression findings in EBV+ PTCL-NOS, we suggest EBV+ PTCL-NOS as a distinct disease entity from PTCL-NOS. In this study, the finding that most significantly enriched the functional term was immune response, suggesting a specific relation between EBV infection and alteration of immune response in the patients with EBV+ PTCL-NOS.     

Chronic active Epstein‐Barr virus infection: A heterogeneous entity requiring a high index of suspicion for diagnosis

Chronic active Epstein‐Barr virus infection of T‐ and NK‐cell type, systemic form, is a rare entity within the spectrum of EBV‐driven T‐ and NK‐cell lymphoproliferative disorders. Established diagnostic criteria and a characteristic clinical course help to differentiate it from other closely related EBV‐positive neoplasms and clinical states. We present a patient and review the natural history, pathologic features, pathogenesis, and differential diagnosis of this entity.     

Xenophagy in Helicobacter pylori‐ and Epstein–Barr virus‐induced gastric cancer

Helicobacter pylori and Epstein–Barr virus (EBV) account for roughly 80% and 10%, respectively, of gastric carcinomas worldwide. Autophagy is an evolutionarily conserved and intricately regulated cellular process that involves the sequestration of cytoplasmic proteins and organelles into double‐membrane autophagosomes that eventually fuse with lysosomes for degradation of the engulfed content. Emerging evidence indicates that xenophagy, a form of selective autophagy, plays a crucial role in the pathogenesis of H. pylori‐ and EBV‐induced gastric cancer. Xenophagy specifically recognizes intracellular H. pylori and EBV and physically targets these pathogens to the autophagosomal–lysosomal pathway for degradation. In this connection, H. pylori or EBV‐induced dysregulation of autophagy may be causally linked to gastric tumourigenesis and therefore can be exploited as therapeutic targets. This review will discuss how H. pylori and EBV infection activate autophagy and how these pathogens evade recognition and degradation by the autophagic pathway. Elucidating the molecular aspects of H. pylori‐ and EBV‐induced autophagy will help us better understand the pathogenesis of gastric cancer and promote the development of autophagy modulators as antimicrobial agents. Published by John Wiley & Sons, Ltd     

Evidence of Epstein-Barr Virus Association with Gastric Cancer and Non-Atrophic Gastritis

Different lines of evidence support an association between Epstein-Barr virus (EBV) and gastric cancer (GC). The main understood risk factor to develop GC is infection by Helicobacter pylori (H. pylori), which triggers a local inflammatory response critical for progression from gastritis to GC. The role of EBV in early inflammatory gastric lesions has been poorly studied. A recent study proposed a cutoff value of 2000 EBV particles to identify patients with increased chances of infection of the gastric epithelium, which may favor the inflammatory process. To better understand the role of EBV in cancer progression, we analyzed 75 samples of GC, 147 control samples of non-tumor gastric tissue derived from GC patients and 75 biopsies from patients with non-atrophic gastritis (NAG). A first-round PCR was used for EBV detection in tumor and non-tumor controls and a more sensitive nested PCR for gastritis samples; both PCRs had lower detection limits above the proposed cutoff value. With this strategy 10.67% of GC, 1.3% of non-tumor controls and 8% of gastritis samples were found positive. An EBER1 in situ hybridization showed EBV infection of epithelial cells in GC and in a third of NAG samples, while in the other NAGs infection was restricted to the mononuclear cell infiltrate. EBV-positive GCs were enriched in lace and cribriform patterns, while these rare patterns were not observed in EBV negative samples. Our results support a role for EBV in GC and early precursor lesions, either as directly oncogenic infecting epithelial cells or indirectly as an inflammatory trigger.     

Primary Effusion Lymphoma (PEL)‐Like Lymphoma in a Child With Congenital Immunodeficiency

Primary effusion lymphoma (PEL) is a rare lymphoma that occurs more frequently in immunocompromised adults and has a poor survival. We report a 9‐year‐old female with combined immunodeficiency with an Epstein–Barr virus positive/human herpes virus 8 negative PEL‐like lymphoma. The treatment with systemic chemotherapy for non‐Hodgkin lymphoma, zidovudine, and interferon‐α failed to control disease progression. This is the first reported pediatric case of PEL‐like lymphoma. Increased diagnostic awareness and more effective treatment strategies are needed for this rare lymphoma.