A comprehensive analysis of the cellular and EBV-specific microRNAome in primary CNS PTLD identifies different patterns among EBV-associated tumors.

Primary central nervous system (pCNS) posttransplant lymphoproliferative disorder (PTLD) is a complication of solid organ transplantation characterized by poor outcome. In contrast to systemic PTLD, Epstein-Barr virus (EBV)-association of pCNS PTLD is almost universal, yet viral and cellular data are limited. To identify differences in the pattern of EBV-association of pCNS and systemic PTLD, we analyzed the expression of latent and lytic EBV transcripts and the viral and cellular microRNAome in nine pCNS (eight EBV-associated) and in 16 systemic PTLD samples (eight EBV-associated). Notably although 15/16 EBV-associated samples exhibited a viral type III latency pattern, lytic transcripts were also strongly expressed. Members of the ebv-miR-BHRF1 and ebv-miR-BART clusters were expressed in virtually all EBV-associated PTLD samples. There were 28 cellular microRNAs differentially expressed between systemic and pCNS PTLD. pCNS PTLD expressed lower hsa-miR-199a-5p/3p and hsa-miR-143/145 (implicated in nuclear factor kappa beta and c-myc signaling) as compared to systemic PTLD. Unsupervised nonhierarchical clustering of the viral and cellular microRNAome distinguished non-EBV-associated from EBV-associated samples and identified a separate group of EBV-associated pCNS PTLD that displayed reduced levels of B cell lymphoma associated oncomiRs such as hsa-miR-155, -21, -221 and the hsa-miR-17-92 cluster. EBV has a major impact on viral and cellular microRNA expression in EBV-associated pCNS PTLD.

The presence of KIR2DS5 confers protection against adult immune thrombocytopenia.

Immune thrombocytopenia (ITP) is an autoimmune disorder of unknown aetiology, characterised by an isolated low platelet count in the absence of other identifiable causes. Genes influencing activation of the immune system have been identified as influencing predisposition. Killer cell immunoglobulin-like receptors (KIR) control T-cell and natural killer (NK) cell function via inhibitory and activating signalling pathways. The inhibitory KIR2DL3, KIR3DL2 and KIR3DL1 are up-regulated in the T-cells of patients with ITP in remission relative to those with active disease, and an association of KIR2DS2 and KIR2DL2 with ITP has also been reported. No comprehensive KIR analysis in ITP has been reported. We performed genotyping of all currently known KIR genes using sequence specific primer polymerase chain reaction (SSP-PCR) on a cohort of 83 adult patients with ITP (chronic/persistent or relapsed primary ITP identified by defined criteria) and 106 age matched healthy white volunteers. Non-white patients were not included in the analysis. There was an over-representation of KIR2DS3 (known to be in linkage disequilibrium with KIR2DS2 and 2DL2) and under-representation of KIR2DS5 (also protective against other immune mediated disorders) in adult ITP [odds ratio (OR) = 0.16, confidence interval (CI) 0.08-0.32, P < 0.001]. By multivariable binary logistic regression to adjust for age, sex and the effects of other KIR genes, the presence of KIR2DS2/2DL2 with KIR2DS5 abrogated the risk of KIR2DS2/2DL2 and the protective benefit of KIR2DS5. Further studies are required to establish the mechanistic basis for these observations and their potential impact on ITP therapy.

Homozygous FCGR3A-158V alleles predispose to late onset neutropenia after CHOP-R for diffuse large B-cell lymphoma.

BACKGROUND: Recent reports suggest genetic polymorphisms influence susceptibility to rituximab-induced late-onset neutropenia (LON), which in turn may be a predictor of good outcome in B-cell lymphoma. AIMS: We report the largest study to date assessing FCGR3A-V158F polymorphisms in diffuse large B-cell lymphoma (DLBCL) treated with cyclophosphamide/hydroxydaunorubicin/Oncovin (vincristine)/prednisone/rituximab (CHOP-R). The influence of C1qA-A276G polymorphisms in DLBCL, and the impact of both polymorphisms on susceptibility to LON and outcome were also examined. METHODS: 115 DLBCL patients treated with CHOP-R were compared with 105 healthy White people controls with regards to FCGR3A-V158F and C1qA-A276G polymorphisms. LON incidence and event-free and overall survival (EFS and OS) were analysed for linkage to either polymorphism. RESULTS: The FCGR3A-V158F but not the C1qA-A276G polymorphism influenced the risk of developing LON. 50% of FCGR3A-158V/V patients experienced LON. In contrast, only 7% V/F and 2% F/F experienced LON. The FCGR3A-158V/V genotype was associated with LON compared with V/F (P = 0.028) and F/F genotypes (P = 0.005). Although no patients with either LON or FCGR3A-158V homozygosity relapsed compared with 33% FCGR3A-158F/F and 21% non-LON, this did not translate into improved EFS or OS. CONCLUSIONS: Polymorphic analysis may be a predictive tool to identify those at high risk of LON. Prospective studies are required to establish definitively if LON or FCGR3A-158V/V genotype influences outcome.

Epstein-Barr Virus-related post-transplant lymphoproliferative disorders: pathogenetic insights for targeted therapy.

Post-transplant lymphoproliferative disorder (PTLD) is a spectrum of major, life-threatening lymphoproliferative diseases occurring in the post-transplant setting. The majority of PTLD is of B-cell origin and is associated with several risk factors, the most significant being Epstein-Barr virus (EBV) infection. EBV's in vitro transforming abilities, distinctive latency, clonality within the malignant cells and response to targeted therapies implicate a critical role in the biology of PTLD. This minireview focuses on EBV-related PTLD pathogenesis, in particular the interplay between aspects of the EBV life cycle and latency with nonviral factors resulting in the wide spectrum of histology and clinical presentations encountered in PTLD. With the increased prevalence of transplantation a rise in the incidence of PTLD may be expected. Therefore the importance of laboratory and animal models in the understanding of PTLD and the development of novel therapeutic approaches is discussed.

CgT1: a non-LTR retrotransposon with restricted distribution in the fungal phytopathogen Colletotrichum gloeosporioides.

Two genetically distinct biotypes (A and B) of Colletotrichum gloeosporioides that cause different anthracnose diseases on the legumes Stylosanthes spp. have been identified in Australia. A DNA sequence that was present in biotype B and absent in biotype A was isolated by differential hybridisation of a genomic library using total genomic DNA of each biotype as hybridisation probes. This sequence also failed to hybridise to DNA of three biotypes of C. gloeosporioides from other host species and to DNA of three other species of Colletotrichum. This clone was used to isolate two cosmid clones of biotype B. Sequence analysis of these clones revealed a repetitive element of approximately 5.7 kb in length. This element, termed CgT1, was dispersed in the genome and present in about 30 copies. The element contained open reading frames encoding deduced sequence motifs homologous to gag-like proteins, reverse transcriptase and RNase H domains of non-LTR retrotransposons. The termini of CgT1 lacked long terminal repeats (LTRs) but contained a 3' A-rich domain. The insertion site of one copy of the element was flanked by short 13-bp direct repeats. These characteristics of the termini, taken together with the overall structure and sequence homologies, indicate that CgT1 belongs to the non-LTR, LINE-like retrotransposon class of elements that are present in many eukaryotes. PCR primers designed to amplify regions of CgT1 can be used to distinguish biotypes A and B in Australia. DNA fingerprinting analysis of genomic DNA using hybridisation probes derived from the terminal regions of CgT1 revealed that Australian isolates of biotype B are monomorphic. CgT1 was not detected in some isolates causing Type B disease from other countries and when CgT1 was present there was considerable polymorphism in CgT1 organisation in the genome. CgT1 is the first transposon-like element to be identified in the genus Colletotrichum and has considerable potential as a tool for the study of population structure, genome dynamics and evolution in C. gloeosporioides.