Search

Simple Summary: The Epstein–Barr virus (EBV) is a γ-herpes virus that primarily infects human B cells, and more than 90% of adults have experienced infection. EBV+ B cells express several viral proteins, transmitting signals important for the transformation and tumorigenesis of the infected B cells. Immune surveillance by the host immune system is important to suppress such abnormal expansion of EBV-infected B cells. Here we found that both CD4+ T cells and CD8+ T cells show similar gene expression patterns relating to cytotoxicity towards EBV-infected B cells. EBV-specific cytotoxic CD4+ T cells markedly expressed T-bet, Granzyme B, and Perforin alongside killing activity, which could reflect mechanisms shared with cytotoxic CD8+ T cells. Our findings support the concept that, upon EBV and perhaps other viral infections, T cells of different subsets can be drawn into common pathways mediating immune surveillance through cytotoxicity. Most people infected by EBV acquire specific immunity, which then controls latent infection throughout their life. Immune surveillance of EBV-infected cells by cytotoxic CD4+ T cells has been recognized; however, the molecular mechanism of generating cytotoxic effector T cells of the CD4+ subset remains poorly understood. Here we compared phenotypic features and the transcriptome of EBV-specific effector-memory CD4+ T cells and CD8+ T cells in mice and found that both T cell types show cytotoxicity and, to our surprise, widely similar gene expression patterns relating to cytotoxicity. Similar to cytotoxic CD8+ T cells, EBV-specific cytotoxic CD4+ T cells from human peripheral blood expressed T-bet, Granzyme B, and Perforin and upregulated the degranulation marker, CD107a, immediately after restimulation. Furthermore, T-bet expression in cytotoxic CD4+ T cells was highly correlated with Granzyme B and Perforin expression at the protein level. Thus, differentiation of EBV-specific cytotoxic CD4+ T cells is possibly controlled by mechanisms shared by cytotoxic CD8+ T cells. T-bet-mediated transcriptional regulation may explain the similarity of cytotoxic effector differentiation between CD4+ T cells and CD8+ T cells, implicating that this differentiation pathway may be directed by environmental input rather than T cell subset. [ABSTRACT FROM AUTHOR]

Germinal centers (GC) are the predominant origin of human B cell lymphomagenesis. Transgenic mice in which gene expression is altered specifically in GC B cells have broadened our knowledge about the mechanisms of malignant transformation. However, extensive resources are needed due to the genetic complexity of these mouse models. Thus, bone marrow (BM)-derived chimerism is an attractive approach to study GC B cell derived lymphomagenesis, as it allows for an efficient allocation of resources and reduces the number of animals used.

Background: MicroRNAs are regulators of gene expression, which act mainly by decreasing mRNA levels of their multiple targets. Deregulated microRNA expression has been shown for acute myeloid leukemia, a disease also characterized by altered gene expression associated with distinct genomic aberrations such as nucleophosmin (NPM1) mutations. To shed further light on the role of deregulated microRNA and gene expression in cytogenetically normal acute myeloid leukemia with NPM1 mutation we performed an integrative analysis of microRNA and mRNA expression data sets., Design and Methods: Both microRNA and gene expression profiles were investigated in samples from a cohort of adult cytogenetically normal acute myeloid leukemia patients (n=43; median age 46 years, range 23-60 years) with known NPM1 mutation status (n=23 mutated, n=20 wild-type) and the data were integratively analyzed. Putative microRNA-mRNA interactions were validated by quantitative reverse transcriptase polymerase chain reaction, western blotting and luciferase reporter assays. For selected microRNAs, sensitivity of microRNA-overexpressing cells to cytarabine treatment was tested by FACS viability and cell proliferation assays., Results: Our integrative approach of analyzing both microRNA- and gene expression profiles in parallel resulted in a refined list of putative target genes affected by NPM1 mutation-associated microRNA deregulation. Of 177 putative microRNA - target mRNA interactions we identified and validated 77 novel candidates with known or potential involvement in leukemogenesis, such as IRF2-miR-20a, KIT-miR-20a and MN1-miR-15a. Furthermore, our data showed that deregulated expression of tumor suppressor microRNAs, such as miR-29a and miR-30c, might contribute to sensitivity to cytarabine, which is observed in NPM1 mutated acute myeloid leukemia., Conclusions: Overall, our observations highlight that integrative data analysis approaches can improve insights into leukemia biology, and lead to the identification of novel microRNA - target gene interactions of potential relevance for acute myeloid leukemia treatment.

Background: The genetic hallmark of mantle cell lymphoma is a t(11;14)(q13;q32). However, additional genomic alterations are likely involved in the pathogenesis of this lymphoma., Design and Methods: To determine the incidence and clinical relevance of these aberrations, we analyzed 103 well-characterized samples of mantle cell lymphoma by fluorescence in situ hybridization for the most common recurrent additional genomic findings., Results: Screening 16 different regions we detected additional genomic aberrations in 92% of the cases of mantle cell lymphoma. Common gains included 3q26, 8q24, 15q23, 7p15, and common losses 13q14, 11q22-q23, 9p21, 1p22, 17p13, 6q27, and 8p22. Deletions 8p22, 9p21, 13q14, and gain of 7p15 were associated with evidence of clonal heterogeneity. While there was no correlation of additional genomic aberrations and VH-mutation status, gain of 15q23 and deletion 6q27 were associated with lower disease stage (p=0.01 and p=0.04, respectively). Patients with deletion 13q14 had shorter overall survival times (p=0.01), and there was a strong trend towards inferior outcome in patients with deletion 9p21 (p=0.07). In multivariable analysis, loss of 13q14 and an International Prognosis Index score >/= 3 turned out to be significantly associated with inferior clinical outcome (p=0.002 and p<0.001, respectively)., Conclusions: The comprehensive analysis of additional genomic aberrations in mantle cell lymphoma provided further evidence for the prognostic relevance of loss of 13q14, which warrants evaluation within prospective trials. Furthermore, our analysis gave novel insights into the pathogenesis of mantle cell lymphoma with regard to the detection of clonal heterogeneity, possibly indicating clonal evolution in this type of lymphoma.

In chronic lymphocytic leukemia (CLL), the acquisition of new genomic aberrations during the disease course (clonal evolution) is thought to be an infrequent phenomenon but comprehensive analyses are limited. Genomic aberrations were analyzed by fluorescence in situ hybridization (FISH) at various time points during the disease course of 64 CLL patients. Results were correlated with the mutation status of the immunoglobulin heavy-chain variableregion genes (VH) and clinical characteristics. Following a median observation time of 42.3 months (range 23.2-73) after first genetic study, 11 out of the 64 (17%) patients showed clonal evolution with the following newly acquired aberrations: del(17p13) (n=4), del(6q21) (n=3), del(11q23) (n=2), +(8q24) (n=1), and evolution from monoallelic to biallelic del(13q14) (n=3). Interestingly, clonal evolution only occurred among cases with unmutated VH status. The group with clonal evolution showed a higher rate of progression in Binet stage (82% vs. 28%), a possibly greater need for treatment (91% vs. 62% previously untreated patients received their first therapy), and a higher hazard risk of death (HR = 2.97, 95% CI 1.40-6.27, p=0.004) in multivariable analysis. The estimated median survival time after the occurrence of clonal evolution was 21.7 months. Expansion of the clone with del(17p13) was observed in all patients during treatment, indicating in vivo resistance to therapy. In multivariable Andersen-Gill regression analysis, clonal evolution was identified as an independent prognostic factor for overall survival. Clonal evolution only occurred in CLL with unmutated VH indicating to karyotypic instability as a pathomechanism. Acquisition of genomic aberrations was associated with poor outcome based on multivariable analysis. In vivo resistance to chemotherapy of CLL clones with del(17p13) emphasizes the need for alternative treatment approaches in these patients.