RESUMO
Lymphoproliferative diseases (LPDs) associated with Epstein-Barr virus (EBV) infection cause significant morbidity and mortality in bone marrow and solid organ transplant recipients. To gain insight into LPD pathogenesis and to identify potential effective therapeutic approaches, we investigated early molecular events leading to B-cell transformation by gene expression profiling of EBV-infected B-cells from tonsils by Affymetrix microarray 72 hr postinfection when the B-cells hyperproliferation phase starts. Cell cycle and apoptosis were the most significantly affected pathways and enriched gene sets. In particular, we found significantly increased expression of cyclin-dependent kinase (CDK)1 and CCNB1 (cyclin B1) and of one of their downstream targets BIRC5 (survivin). Importantly, the strong upregulation of the antiapoptotic protein survivin was confirmed in lymphoblastoid cell lines (LCLs) and 71% of EBV-positive post-transplant EBV-LPD lesions scored positive for survivin. The validity of early transforming events for the identification of therapeutic targets for EBV-LPD was confirmed by the marked antiproliferative effect of the CDK inhibitor flavopiridol on LCLs and by the strong induction of apoptosis by survivin inhibition with YM155 or terameprocol. Our results suggest that targeting of CDKs and/or survivin in post-transplant EBV-LPD by specific inhibitors might be an important approach to control and eliminate EBV-transformed B-cells that should be further considered.
Assuntos
Linfócitos B/metabolismo , Linfócitos B/virologia , Proteína Quinase CDC2/genética , Infecções por Vírus Epstein-Barr/genética , Proteínas Inibidoras de Apoptose/genética , Transtornos Linfoproliferativos/genética , Transplante de Órgãos/efeitos adversos , Apoptose/genética , Proteína Quinase CDC2/metabolismo , Ciclo Celular/genética , Ciclina B1/genética , Ciclina B1/metabolismo , Infecções por Vírus Epstein-Barr/etiologia , Infecções por Vírus Epstein-Barr/metabolismo , Infecções por Vírus Epstein-Barr/virologia , Expressão Gênica , Herpesvirus Humano 4 , Humanos , Proteínas Inibidoras de Apoptose/metabolismo , Leucócitos Mononucleares/metabolismo , Leucócitos Mononucleares/virologia , Transtornos Linfoproliferativos/etiologia , Transtornos Linfoproliferativos/metabolismo , Survivina , Transformação Genética , Regulação para CimaRESUMO
Epstein-Barr virus (EBV) uses nasal mucosa-associated lymphoid tissue (NALT) as a portal of entry to establish life-long persistence in memory B cells. We previously showed that naïve and memory B cells from NALT are equally susceptible to EBV infection. Here we show that memory B cells from NALT are significantly more susceptible to EBV infection than those from remote lymphatic organs. We identify beta(1) integrin, which is expressed the most by naïve B cells of distinct lymphoid origin and by memory B cells from NALT, as a mediator of increased susceptibility to infection by EBV. Furthermore, we show that BMRF-2-beta(1) integrin interaction and the downstream signal transduction pathway are critical for postbinding events. An increase of beta(1) integrin expression in peripheral blood memory B cells provoked by CD40 stimulation plus B-cell receptor cross-linking increased the susceptibility of non-NALT memory B cells to EBV infection. Thus, EBV seems to utilize the increased activation status of memory B cells residing in the NALT to establish and ensure persistence.
