Epstein-Barr virus and lymphoproliferative disease

Association of Crohn's disease, thiopurines, and primary epstein-barr virus infection with hemophagocytic lymphohistiocytosis

OBJECTIVE

To assess the incidence of hemophagocytic lymphohistiocytosis (HLH) in a well-defined population of children with inflammatory bowel disease (IBD) and evaluate the common clinical and laboratory characteristics of individuals with IBD who developed HLH.

STUDY DESIGN

We conducted a retrospective study of all children who developed HLH over an 8-year period. The incidence of HLH in patients with IBD was calculated using US census data and a statewide project examining the epidemiology of pediatric IBD.

RESULTS

Among children in Wisconsin, 20 cases of HLH occurred during the study period; 5 cases occurred in children with IBD. Common characteristics include: Crohn's disease (CD), thiopurine administration, fever lasting more than 5 days, lymphadenopathy, splenomegaly, anemia, lymphopenia, and elevated serum triglycerides and ferritin. Of the patients, 4 had primary Epstein-Barr virus infections. The incidence of HLH among all children in Wisconsin was 1.5 per 100 000 per year. The risk was more than 100-fold greater for children with CD (P < .00001).

CONCLUSIONS

Pediatric patients with CD are at increased risk for developing HLH; primary Epstein-Barr virus infection and thiopurine administration may be risk factors.

Effect of prophylactic valacyclovir on the presence of human herpesvirus DNA in saliva of healthy individuals after dental treatment

Human herpesviruses (HHVs) are ubiquitous pathogens that intermittently reactivate from latency. Transmission is believed to be facilitated by their frequent appearance in saliva. This study sought to understand the factors that influence the appearance of these viruses in saliva by examining the prevalence, pattern, and quantity of all eight HHVs in saliva of immunocompetent adults with a history of recurrent oral herpes simplex virus (HSV) infections following dental treatment and antiviral therapy. Valacyclovir or matched placebo was given (2 g twice on the day of treatment and 1 g twice the following day) to 125 patients in a randomized, double-blind controlled trial. Saliva, collected on the day of dental treatment and 3 and 7 days later, was analyzed using real-time quantitative PCR. At all visits, HHVs coinfected saliva. Over the course of the week, the DNAs of HHV-6 and HHV-7 were detected significantly more often (97% to 99% of patients) than Epstein-Barr virus (EBV; 64.8%), HSV-1 (13.0%), HHV-8 (3.2%), cytomegalovirus (2.4%), HSV-2 (0%), and varicella-zoster virus (0%), irrespective of drug treatment (P < 0.002). Mean genome copy numbers were highest for HSV-1 and HHV-6. Dental treatment did not influence asymptomatic viral shedding patterns. However, valacyclovir treatment resulted in significantly fewer patients shedding EBV at both postoperative visits compared with placebo (P < 0.008). These results suggest that HHVs are simultaneously present in the saliva of healthy adults at levels that could facilitate transmission, and valacyclovir therapy decreases the prevalence of EBV in saliva but has little effect on HHV-6 and HHV-7.

Plasmocytomes cutanés associés au virus Epstein-Barr chez les transplantés d’organes

BACKGROUND

Post-transplantation lymphoproliferative disorders develop in 1 to 10p. 100 of organ transplant recipients and are frequently associated with Epstein-Barr virus (EBV). Among post-transplantation lymphoproliferative disorders, plasmacytoma with cutaneous involvement is exceptional. Association with EBV has been rarely reported in post-transplantation plasmacytomas and the latency type of EBV has never been characterized. We report 2 new cases of cutaneous monotype EBV-related plasmacytomas.

CASE-REPORTS

Clinical presentation was a sub-cutaneous tumor on the thigh in the first case and an ulcerated nodule of the leg in the second case, occurring respectively 7 and 8 years after organ transplantation (liver transplantation and heart transplantation). In both lesions, tumor cells exhibited lambda light chain restriction and the association with EBV was confirmed using immunohistochemistry and in situ hybridization. The expression of EBV genes in tumor cells demonstrated type III latency.

DISCUSSION

The classification of post-transplantation lymphoproliferative disorders is not well defined and some authors retain 3 categories. Among the latter, plasmacytomas have been rarely described. Cutaneous involvement is reported in 4 cases and an association with EBV in only 2 cases without description of viral latency. Clinical and histological features of post-transplantation plasmacytomas appear polymorphic. We report EBV-association in both cases, with a type III latency clearly demonstrated in one case, as has been reported in other lymphoproliferative diseases in patients with congenital or acquired immunodeficiency. We also discuss various possible therapeutic strategies for post-transplantation lymphoproliferative disorders.

Regulation of TIMP-1 phenotypic expression in Epstein--Barr virus-immortalized B lymphocytes

Normal B lymphocytes as well as malignant B cells extravasate from blood circulation during physiological and pathological processes and require matrix metalloproteinases (MMPs) to facilitate trafficking through the subendothelial basal lamina and the extracellular matrix. We have previously shown that Epstein-Barr virus (EBV)-immortalized B lymphocytes constitutively synthesized low levels of MMP-9 and huge amounts of its preferential inhibitor, tissue inhibitor of matrix metalloproteinase-1 (TIMP-1). In the present study, TIMP-1 phenotypic expression was extensively investigated in response to various mediators including interleukins, chemokines, growth factors and tumor promotor, and was compared to MMP-9 synthesis. Results showed a roughly constitutive TIMP-1 expression opposed to an inducible MMP-9 synthesis. Nevertheless, further analysis of TIMP-1 synthesis showed the existence of regulation mechanisms: modulation of intracellular Ca(2+) concentration as well as cation ionophore monensin were demonstrated to influence TIMP-1 production and secretion. The precise pathways implicated in these regulation mechanisms are currently under survey.

High incidence of Epstein-Barr virus, cytomegalovirus and human herpesvirus 6 infections in children with cancer

BACKGROUND

A prospective single-center study was performed to study infection with lymphotropic herpesviruses (LH) Epstein-Barr virus (EBV), cytomegalovirus (CMV) and human herpesvirus 6 (HHV-6) in children with cancer.

METHODS

The group of 186 children was examined for the presence of LH before, during and 2 months after the end of anticancer treatment. Serology of EBV and CMV was monitored in all children, serology of HHV-6 and DNA analysis of all three LH was monitored in 70 children.

RESULTS

At the time of cancer diagnosis (pre-treatment), there was no difference between cancer patients and age-matched healthy controls in overall IgG seropositivity for EBV (68.8% vs. 72.0%; p = 0.47) and CMV (37.6% vs. 41.7%; p = 0.36). During anticancer therapy, primary or reactivated EBV and CMV infection was present in 65 (34.9%) and 66 (35.4%) of 186 patients, respectively, leading to increased overall post-treatment IgG seropositivity that was significantly different from controls for EBV (86.6% vs. 72.0%; p = 0.0004) and CMV (67.7% vs. 41.7%; p < 0.0001). Overall pre-treatment IgG seropositivity for HHV-6 was significantly lower in patients than in controls (80.6% vs. 91.3%; p = 0.0231) which may be in agreement with Greaves hypothesis of protective effect of common infections in infancy to cancer development. Primary or reactivated HHV-6 infection was present in 23 (32.9%) of 70 patients during anticancer therapy leading to post-treatment IgG seropositivity that was not significantly different from controls (94.3% vs. 91.3%; p = 0.58). The LH infection occurred independently from leukodepleted blood transfusions given. Combination of serology and DNA analysis in detection of symptomatic EBV or CMV infection was superior to serology alone.

CONCLUSION

EBV, CMV and HHV-6 infections are frequently present during therapy of pediatric malignancy.

Molecular piracy of Kaposi's sarcoma associated herpesvirus

Kaposi's Sarcoma associated Herpesvirus (KSHV) is the most recently discovered human tumor virus and is associated with the pathogenesis of Kaposi's sarcoma, primary effusion lymphoma, and Multicentric Casttleman's disease. KSHV contains numerous open reading frames with striking homology to cellular genes. These viral gene products play a variety of roles in KSHV-associated pathogenesis by disrupting cellular signal transduction pathways, which include interferon-mediated anti-viral responses, cytokine-regulated cell growth, apoptosis, and cell cycle control. In this review, we will attempt to cover our understanding of how viral proteins deregulate cellular signaling pathways, which ultimately contribute to the conversion of normal cells to cancerous cells.

Successful treatment of aggressive post transplant lymphoproliferative disorder using rituximab

A 52 year -old female developed a histologically aggressive, Epstein-Barr virus positive, lymphoproliferative disorder involving the brain and liver 4 months following a combined kidney/pancreas transplant. Following a brief trial of reduced immunosuppression, she was treated with rituximab. Despite subsequent re-intensification of immunosuppression, the lesions showed continued regression with almost complete disappearance by 5 months. Rituximab appears to be a safe, effective treatment for post transplant lymphoproliferative disorder.

Upregulation of tyrosine kinase TKT by the Epstein-Barr virus transactivator Zta

The Zta protein is a key transactivator involved in initiating the Epstein-Barr virus (EBV) lytic cascade. In addition to transactivating many viral genes, Zta has the capacity to influence host cellular signals by binding to promoter regions or by interacting with several important cellular factors. Based on the observation that tyrosine kinases play central roles in determining the fate of cells, a kinase display assay was used to investigate whether cells expressing Zta have an altered pattern of kinase expression. The assay revealed that TRK-related tyrosine kinase (TKT) is expressed at significant levels in Zta transfectants but not in control cells. Additional evidence was obtained from Northern and Western blotting. Importantly, the upregulation of phosphorylated TKT and TKT downstream effector matrix metalloproteinase 1 in Zta transfectants hinted that TKT might initiate a signaling cascade in Zta-expressing cells. In addition, deletion analysis of the Zta protein revealed that the transactivation and dimerization domains were both essential for the upregulation of TKT transcription. Moreover, correlation of expression levels of Zta and TKT transcripts in nasopharyngeal carcinoma biopsy specimens was clearly demonstrated by quantitative PCR (Q-PCR), which provides the first evidence for an effect of Zta on cellular gene expression in vivo. These findings offer insight into the virus-cell interactions and may help us elucidate the role of EBV in tumorigenesis.

Proteomic analysis of Epstein-Barr virus-transformed human B-lymphoblastoid cell lines before and after immortalization

Infection of human B lymphocytes with Epstein-Barr virus (EBV) induces proliferative B-lymphoblastoid cell lines (LCLs). However, the majority of EBV-transformed LCLs are mortal and unable to avoid cellular senescence. In our previous experiment, three immortalized LCLs were established by passages of EBV-transformed LCLs for nearly five years accompanied by strong telomerase activity. In the present study, proteomic profiles of these three LCLs were analyzed comparatively at the early and the late passages of cell culture, and a protein spot was found which most significantly decreased with the immortalization in two LCLs. The expression of the protein in the third LCL was suppressed at 17 population doubling level (PDL), already suggesting that part of the immortalization process had been initiated before 17 PDL. The protein was assigned to ssp7001 (16.3 kDa, pI 6.0) by referring to our TMIG-2DPAGE proteome database. The protein was transferred onto a polyvinylidene difluoride (PVDF) membrane and digested with lysilendopeptidase to perform peptide mass fingerprinting by nanoelectrospray ionization mass spectrometry (nano-ESI-MS). Subsequent MS-Fit database search indicated that ssp7001 is a phosphoprotein stathmin. This speculation was confirmed by the tandem MS (MS/MS) analysis in a Q-Tof system and by Edman degradation microsequencing.