The Immune Response to Epstein Barr Virus and Implications for Posttransplant Lymphoproliferative Disorder. Transplantation. 2017;101:2009-2016. [PMID: 28376031 DOI: 10.1097/tp.0000000000001767]

Epstein-Barr virus-associated post-transplant lymphoproliferative disorders in pediatric transplantation: A prospective multicenter study in the United States

BACKGROUND

Epstein-Barr virus (EBV)-associated post-transplant lymphoproliferative disorders (PTLD) is the most common malignancy in children after transplant; however, difficulties for early detection may worsen the prognosis.

METHODS

The prospective, multicenter, study enrolled 944 children (≤21 years of age). Of these, 872 received liver, heart, kidney, intestinal, or multivisceral transplants in seven US centers between 2014 and 2019 (NCT02182986). In total, 34 pediatric EBV+ PTLD (3.9%) were identified by biopsy. Variables included sex, age, race, ethnicity, transplanted organ, EBV viral load, pre-transplant EBV serology, immunosuppression, response to chemotherapy and rituximab, and histopathological diagnosis.

RESULTS

The uni-/multivariable competing risk analyses revealed the combination of EBV-seropositive donor and EBV-naïve recipient (D+R-) was a significant risk factor for PTLD development (sub-hazard ratio: 2.79 [1.34-5.78], p = .006) and EBV DNAemia (2.65 [1.72-4.09], p < .001). Patients with D+R- were significantly more associated with monomorphic/polymorphic PTLD than those with the other combinations (p = .02). Patients with monomorphic/polymorphic PTLD (n = 21) had significantly more EBV DNAemia than non-PTLD patients (p < .001) and an earlier clinical presentation of PTLD than patients with hyperplasias (p < .001), within 6-month post-transplant. Among non-liver transplant recipients, monomorphic/polymorphic PTLD were significantly more frequent than hyperplasias in patients ≥5 years of age at transplant (p = .01).

CONCLUSIONS

D+R- is a risk factor for PTLD and EBV DNAemia and associated with the incidence of monomorphic/polymorphic PTLD. Intensive follow-up of EBV viral load within 6-month post-transplant, especially for patients with D+R- and/or non-liver transplant recipients ≥5 years of age at transplant, may help detect monomorphic/polymorphic PTLD early in pediatric transplant.

Deciphering the Role of Epstein-Barr Virus Latent Membrane Protein 1 in Immune Modulation: A Multifaced Signalling Perspective

The disruption of antiviral sensors and the evasion of immune defences by various tactics are hallmarks of EBV infection. One of the EBV latent gene products, LMP1, was shown to induce the activation of signalling pathways, such as NF-κB, MAPK (JNK, ERK1/2, p38), JAK/STAT and PI3K/Akt, via three subdomains of its C-terminal domain, regulating the expression of several cytokines responsible for modulation of the immune response and therefore promoting viral persistence. The aim of this review is to summarise the current knowledge on the EBV-mediated induction of immunomodulatory molecules by the activation of signal transduction pathways with a particular focus on LMP1-mediated mechanisms. A more detailed understanding of the cytokine biology molecular landscape in EBV infections could contribute to the more complete understanding of diseases associated with this virus.

The impact of induction therapy on the risk of posttransplant lymphoproliferative disorder in adult kidney transplant recipients with donor-recipient serological Epstein-Barr virus mismatch

Posttransplant lymphoproliferative disorder (PTLD) poses a significant concern in Epstein-Barr virus (EBV)-negative patients transplanted from EBV-positive donors (EBV R-/D+). Previous studies investigating the association between different induction agents and PTLD in these patients have yielded conflicting results. Using the Organ Procurement and Transplant Network database, we identified EBV R-/D+ patients >18 years of age who underwent kidney-alone transplants between 2016 and 2022 and compared the risk of PTLD with rabbit antithymocyte globulin (ATG), basiliximab, and alemtuzumab inductions. Among the 6620 patients included, 64.0% received ATG, 23.4% received basiliximab, and 12.6% received alemtuzumab. The overall incidence of PTLD was 2.5% over a median follow-up period of 2.9 years. Multivariable analysis demonstrated that the risk of PTLD was significantly higher with ATG and alemtuzumab compared with basiliximab (adjusted subdistribution hazard ratio [aSHR] = 1.98, 95% confidence interval [CI] 1.29-3.04, P = .002 for ATG and aSHR = 1.80, 95% CI 1.04-3.11, P = .04 for alemtuzumab). However, PTLD risk was comparable between ATG and alemtuzumab inductions (aSHR = 1.13, 95% CI 0.72-1.77, P = .61). Therefore, the risk of PTLD must be taken into consideration when selecting the most appropriate induction therapy for this patient population.

The IPTA Nashville Consensus Conference on Post-Transplant lymphoproliferative disorders after solid organ transplantation in children: III - Consensus guidelines for Epstein-Barr virus load and other biomarker monitoring

The International Pediatric Transplant Association convened an expert consensus conference to assess current evidence and develop recommendations for various aspects of care relating to post-transplant lymphoproliferative disorders after solid organ transplantation in children. In this report from the Viral Load and Biomarker Monitoring Working Group, we reviewed the existing literature regarding the role of Epstein-Barr viral load and other biomarkers in peripheral blood for predicting the development of PTLD, for PTLD diagnosis, and for monitoring of response to treatment. Key recommendations from the group highlighted the strong recommendation for use of the term EBV DNAemia instead of "viremia" to describe EBV DNA levels in peripheral blood as well as concerns with comparison of EBV DNAemia measurement results performed at different institutions even when tests are calibrated using the WHO international standard. The working group concluded that either whole blood or plasma could be used as matrices for EBV DNA measurement; optimal specimen type may be clinical context dependent. Whole blood testing has some advantages for surveillance to inform pre-emptive interventions while plasma testing may be preferred in the setting of clinical symptoms and treatment monitoring. However, EBV DNAemia testing alone was not recommended for PTLD diagnosis. Quantitative EBV DNAemia surveillance to identify patients at risk for PTLD and to inform pre-emptive interventions in patients who are EBV seronegative pre-transplant was recommended. In contrast, with the exception of intestinal transplant recipients or those with recent primary EBV infection prior to SOT, surveillance was not recommended in pediatric SOT recipients EBV seropositive pre-transplant. Implications of viral load kinetic parameters including peak load and viral set point on pre-emptive PTLD prevention monitoring algorithms were discussed. Use of additional markers, including measurements of EBV specific cell mediated immunity was discussed but not recommended though the importance of obtaining additional data from prospective multicenter studies was highlighted as a key research priority.

Chronic Epstein-Barr viral load carriage after pediatric organ transplantation

Epstein-Barr virus (EBV) infection and EBV-associated post-transplant lymphoproliferative disorder (EBV/PTLD) is one of the most devastating complications occurring in pediatric solid organ transplant (SOT) recipients. Observations of SOT recipients undergoing serial EBV monitoring to inform reduction of immune suppression to prevent EBV-/PTLD has identified patients who maintain chronic high EBV load (CHL) in their blood. The CHL carrier state has been seen more commonly in pediatric compared to adult transplant recipients. Some but not all CHL may progress to EBV/PTLD. However, little is known regarding the biology of this CHL carrier state and the optimal clinical approach to CHL has not been established. This review summarizes the current knowledge and evidence of chronic high EBV load and introduces commonly adopted approaches from experts in this field.

Early T-cell reconstitution predicts risk of EBV reactivation after allogeneic hematopoietic stem cell transplantation

The quality of immune reconstitution (IR) is crucial for the outcome of patients who received allogeneic hematopoietic stem cell transplantation (allo-HSCT), and is closely connected with infection, relapse and graft-versus-host disease (GvHD) which are the most important causes for transplantation failure. However, the IR pattern in the early stage after allo-HSCT, particularly haploidentical (HID) HSCT, remains unclear. In this retrospective study, we examined the T cell reconstitution of patients within the initial 30 days (n = 173) and 100 days (n = 122) after allo-HSCT with myeloablative condition (MAC), of which > 70% were HID HSCT, to assess the influence of IR on the transplant outcomes. By comparing 78 patients with good IR (GIR) to 44 patients with poor IR (PIR), we observed that GIR was associated with lower risk for Epstein-Barr virus (EBV) reactivation and cytomegalovirus (CMV) reactivation, but had no significant impacts on the survival outcomes (i.e., overall survival, event-free survival) and cumulative incidences of GvHD. Importantly, we found lymphocyte reconstitution pattern at day 30 after allo-HSCT would be a surrogate for IR evaluated at day 100. In the Cox proportional hazard model, early reconstitution of CD4+, CD4+CD25+, CD4+CD45RO+, CD4+CD25+CD27low, and CD8+ T cells at day 30 was reversely correlated with risk of EBV reactivation. Finally, we constructed a predictive model for EBV reactivation with CD8+ and CD4+CD45RO+ T cell proportions of the training cohort (n = 102), which was validated with a validation cohort (n = 37). In summary, our study found that the quality of IR at day 30 had a predictive value for the risk of EBV reactivation, and might provide guidance for close monitoring for EBV reactivation.

Post-Transplant Lymphoproliferative Disorders

Post-transplant lymphoproliferative disorders (PTLDs) are a heterogenous set of unregulated lymphoid cell proliferations after organ or tissue transplant. A majority of cases are associated with the Epstein-Barr virus and higher intensity of pharmacologic immunosuppression. The clinical presentations are numerous. The diagnosis is ideally by histology, except in cases where the tumor is inaccessible to biopsy. While some pre-emptive therapies and treatment strategies are available have reasonable success are available, they do not eliminate the high morbidity and significant mortality after PTLD.

Mechanisms of T cell evasion by Epstein-Barr virus and implications for tumor survival

Epstein-Barr virus (EBV) is a prevalent oncogenic virus estimated to infect greater than 90% of the world's population. Following initial infection, it establishes latency in host B cells. EBV has developed a multitude of techniques to avoid detection by the host immune system and establish lifelong infection. T cells, as important contributors to cell-mediated immunity, make an attractive target for these immunoevasive strategies. Indeed, EBV has evolved numerous mechanisms to modulate T cell responses. For example, it can augment expression of programmed cell death ligand-1 (PD-L1), which inhibits T cell function, and downregulates the interferon response, which has a strong impact on T cell regulation. It also modulates interleukin secretion and can influence major histocompatibility complex (MHC) expression and presentation. In addition to facilitating persistent EBV infection, these immunoregulatory mechanisms have significant implications for evasion of the immune response by tumor cells. This review dissects the mechanisms through which EBV avoids detection by host T cells and discusses how these mechanisms play into tumor survival. It concludes with an overview of cancer treatments targeting T cells in the setting of EBV-associated malignancy.

Upregulation of IQGAP2 by EBV transactivator Rta and its influence on EBV life cycle

Epstein-Barr virus (EBV) is a human oncogenic γ-herpesvirus that establishes persistent infection in more than 90% of the world's population. EBV has two life cycles, latency and lytic replication. Reactivation of EBV from latency to the lytic cycle is initiated and controlled by two viral immediate-early transcription factors, Zta and Rta, encoded by BZLF1 and BRLF1, respectively. In this study, we found that IQGAP2 expression was elevated in EBV-infected B cells and identified Rta as a viral gene responsible for the IQGAP2 upregulation in both B cells and nasopharyngeal carcinoma cell lines. Mechanistically, we showed that Rta increases IQGAP2 expression through direct binding to the Rta-responsive element in the IQGAP2 promoter. We also demonstrated the direct interaction between Rta and IQGAP2 as well as their colocalization in the nucleus. Functionally, we showed that the induced IQGAP2 is required for the Rta-mediated Rta promoter activation in the EBV lytic cycle progression and may influence lymphoblastoid cell line clumping morphology through regulating E-cadherin expression. IMPORTANCE Elevated levels of antibodies against EBV lytic proteins and increased EBV DNA copy numbers in the sera have been reported in patients suffering from Burkitt's lymphoma, Hodgkin's lymphoma, and nasopharyngeal carcinoma, indicating that EBV lytic cycle progression may play an important role in the pathogenesis of EBV-associated diseases and highlighting the need for a more complete mechanistic understanding of the EBV lytic cycle. Rta acts as an essential transcriptional activator to induce lytic gene expression and thus trigger EBV reactivation. In this study, scaffolding protein IQGAP2 was found to be upregulated prominently following EBV infection via the direct binding of Rta to the RRE in the IQGAP2 promoter but not in response to other biological stimuli. Importantly, IQGAP2 was demonstrated to interact with Rta and promote the EBV lytic cycle progression. Suppression of IQGAP2 was also found to decrease E-cadherin expression and affect the clumping morphology of lymphoblastoid cell lines.

Distinct association between chronic Epstein-Barr virus infection and T cell compartments from pediatric heart, kidney, and liver transplant recipients

Chronic Epstein-Barr virus (EBV) infection after pediatric organ transplantation (Tx) accounts for significant morbidity and mortality. The risk of complications, such as posttransplant lymphoproliferative disorders, in high viral load (HVL) carriers is the highest in heart Tx recipients. However, the immunologic signatures of such a risk have been insufficiently defined. Here, we assessed the phenotypic, functional, and transcriptomic profiles of peripheral blood CD8+/CD4+ T cells, including EBV-specific T cells, in 77 pediatric heart, kidney, and liver Tx recipients and established the relationship between memory differentiation and progression toward exhaustion. Unlike kidney and liver HVL carriers, heart HVL carriers displayed distinct CD8+ T cells with (1) up-regulation of interleukin-21R, (2) decreased naive phenotype and altered memory differentiation, (3) accumulation of terminally exhausted (TEX PD-1+T-bet-Eomes+) and decrease of functional precursors of exhausted (TPEX PD-1intT-bet+) effector subsets, and (4) transcriptomic signatures supporting the phenotypic changes. In addition, CD4+ T cells from heart HVL carriers displayed similar changes in naive and memory subsets, elevated Th1 follicular helper cells, and plasma interleukin-21, suggesting an alternative inflammatory mechanism that governs T cell responses in heart Tx recipients. These results may explain the different incidences of EBV complications and may help improve the risk stratification and clinical management of different types of Tx recipients.

Mutations in latent membrane protein 1 of Epstein-Barr virus are associated with increased risk of posttransplant lymphoproliferative disorder in children

Epstein-Barr virus (EBV)-positive posttransplant lymphoproliferative disorder (PTLD) results in significant morbidity and mortality in pediatric transplant recipients. Identifying individuals at an increased risk of EBV-positive PTLD could influence clinical management of immunosuppression and other therapies, improving posttransplant outcomes. A 7-center prospective, observational clinical trial of 872 pediatric transplant recipients evaluated the presence of mutations at positions 212 and 366 of EBV latent membrane protein 1 (LMP1) as an indicator of risk of EBV-positive PTLD (clinical trials: NCT02182986). DNA was isolated from peripheral blood of EBV-positive PTLD case patients and matched controls (1:2 nested case:control), and the cytoplasmic tail of LMP1 was sequenced. Thirty-four participants reached the primary endpoint of biopsy-proven EBV-positive PTLD. DNA was sequenced from 32 PTLD case patients and 62 matched controls. Both LMP1 mutations were present in 31 of 32 PTLD cases (96.9%) and in 45 of 62 matched controls (72.6%) (P = .005; OR = 11.7; 95% confidence interval, 1.5, 92.6). The presence of both G212S and S366T carries a nearly 12-fold increased risk of development of EBV-positive PTLD. Conversely, transplant recipients without both LMP1 mutations carry a very low risk of PTLD. Analysis of mutations at positions 212 and 366 of LMP1 can be informative in stratifying patients for risk of EBV-positive PTLD.

Evaluation of host cellular responses to Epstein-Barr virus (EBV) in adult lung transplant patients with EBV-associated diseases

Epstein-Barr virus (EBV) reactivation is commonly observed in lung transplant recipients (LTRs). However, cellular immune responses to EBV in adult LTRs have not been well described. We aimed to study CD4/CD8 ratio, EBV-specific T cells polyfunctional responses and phenotypic changes in natural killer (NK) cells in adult LTRs presenting with EBV-associated diseases. The CD4/CD8 ratio was significantly decreased in LTRs with EBV DNAemia compared with LTRs without EBV DNAemia and healthy controls (HCs). Stimulation with EBV lytic antigen BZLF1 peptide pools induced significant individual and polyfunctional responses from CD8+ CD69+ T cells. Frequencies of CD8+ CD69+ T cells expressing CD107a were significantly higher in LTRs without EBV DNAemia than in LTRs with DNAemia. Frequencies of CD8+ CD69+ T cells concurrently expressing CD107a, IFN-γ, and TNF-α were significantly greater in LTRs with and without EBV DNAemia than in HCs. Finally, BZLF1 induced significantly higher frequencies of CD8+ CD69+ T cells expressing CD107a and IFN-γ in LTRs without EBV DNAemia when compared with EBNA3B. Frequency of more differentiated CD56dim CD16pos NK cells was significantly decreased in LTRs with EBV DNAemia and PTLD compared with HCs. In conclusion, we noted the presence of significant changes in circulating cellular immune responses to EBV in adult LTRs.

HLA-E-restricted immune responses are crucial for the control of EBV infections and the prevention of PTLD

Primary Epstein-Barr virus (EBV) infections may cause infectious mononucleosis (IM), whereas EBV reactivations in solid organ and hematopoietic stem cell transplant recipients are associated with posttransplantation lymphoproliferative disorders (PTLDs). It is still unclear why only a minority of primary EBV-infected individuals develop IM, and why only some patients progress to EBV+PTLD after transplantation. We now investigated whether nonclassic human leukocyte antigen E (HLA-E)-restricted immune responses have a significant impact on the development of EBV diseases in the individual host. On the basis of a large study cohort of 1404 patients and controls as well as on functional natural killer (NK) and CD8+ T-cell analyses, we could demonstrate that the highly expressed HLA-E∗0103/0103 genotype is protective against IM, due to the induction of potent EBV BZLF1-specific HLA-E-restricted CD8+ T-cell responses, which efficiently prevent the in vitro viral dissemination. Furthermore, we provide evidence that the risk of symptomatic EBV reactivations in immunocompetent individuals as well as in immunocompromised transplant recipients depends on variations in the inhibitory NKG2A/LMP-1/HLA-E axis. We show that EBV strains encoding for the specific LMP-1 peptide variants GGDPHLPTL or GGDPPLPTL, presented by HLA-E, elicit strong inhibitory NKG2A+ NK and CD8+ T-cell responses. The presence of EBV strains encoding for both peptides was highly associated with symptomatic EBV reactivations. The further progression to EBV+PTLD was highly associated with the presence of both peptide-encoding EBV strains and the expression of HLA-E∗0103/0103 in the host. Thus, HLA-E-restricted immune responses and the NKG2A/LMP-1/HLA-E axis are novel predictive markers for EBV+PTLD in transplant recipients and should be considered for future EBV vaccine design.

Infection, Rejection, and the Connection

Solid organ transplantation is a life-saving treatment for people with end-stage organ disease. Immune-mediated transplant rejection is a common complication that decreases allograft survival. Although immunosuppression is required to prevent rejection, it also increases the risk of infection. Some infections, such as cytomegalovirus and BK virus, can promote inflammatory gene expression that can further tip the balance toward rejection. BK virus and other infections can induce damage that resembles the clinical pathology of rejection, and this complicates accurate diagnosis. Moreover, T cells specific for viral infection can lead to rejection through heterologous immunity to donor antigen directly mediated by antiviral cells. Thus, viral infections and allograft rejection interact in multiple ways that are important to maintain immunologic homeostasis in solid organ transplant recipients. Better insight into this dynamic interplay will help promote long-term transplant survival.

Epstein-Barr virus-associated posttransplant lymphoproliferative disorders: new insights in pathogenesis, classification and treatment

PURPOSE OF REVIEW

Posttransplant lymphoproliferative disorder (PTLD) is a serious complication following transplantation from an allogeneic donor. Epstein-Barr Virus (EBV) is involved in a substantial number of cases. In this review, we aim to summarize recent knowledge on pathogenesis, classification and treatment of EBV + PTLD.

RECENT FINDINGS

New insights in the complex oncogenic properties of EBV antigens noncoding Ribonucleic acids (RNAs), especially EBV MicroRNA (miRNAs), have increased our knowledge of the pathogenesis of EBV + PTLD. In addition the potential influence of EBV on the tumor microenvironment is becoming clearer, paving the way for new types of immunotherapy. Currently PTLD is classified according to the World Health Organization classification together with other lymphoproliferative disorders, based on the specific immunosuppression. However, a new framework integrating all types of lymphoproliferative disorders in all different settings of immune deficiency and dysregulation is needed. Although treatment of EBV + and EBV - PTLD was largely similar in the past, EBV-directed therapies are currently increasingly used.

SUMMARY

The use of EBV-directed therapies and new agents, based on better understanding of pathogenesis and classification of PTLD, will change the treatment landscape of EBV + PTLD in the next era.

Mutations in JAK/STAT and NOTCH1 Genes Are Enriched in Post-Transplant Lymphoproliferative Disorders

Post-transplant lymphoproliferative disorders (PTLD) are diseases occurring in immunocompromised patients after hematopoietic stem cell transplantation (HCT) or solid organ transplantation (SOT). Although PTLD occurs rarely, it may be associated with poor outcomes. In most cases, PTLD is driven by Epstein-Barr virus (EBV) infection. Few studies have investigated the mutational landscape and gene expression profile of PTLD. In our study, we performed targeted deep sequencing and RNA-sequencing (RNA-Seq) on 16 cases of florid follicular hyperplasia (FFH) type PTLD and 15 cases of other PTLD types that include: ten monomorphic (M-PTLD), three polymorphic (P-PTLD), and two classic Hodgkin lymphoma type PTLDs (CHL-PTLD). Our study identified recurrent mutations in JAK3 in five of 15 PTLD cases and one of 16 FFH-PTLD cases, as well as 16 other genes that were mutated in M-PTLD, P-PTLD, CHL-PTLD and FFH-PTLD. Digital image analysis demonstrated significant differences in single cell area, major axis, and diameter when comparing cases of M-PTLD and P-PTLD to FFH-PTLD. No morphometric relationship was identified with regards to a specific genetic mutation. Our findings suggest that immune regulatory pathways play an essential role in PTLD, with the JAK/STAT pathway affected in many PTLDs.

Non-invasive monitoring associated with B lymphoma cells in post-transplant lymphoproliferative disorder (PTLD) patients: Systematic review

BACKGROUND

One of the most severe side effects of solid-organ transplantation is posttransplant lymphoproliferative disease (PTLD). People with human immunodeficiency virus infection (HIV), an immunosuppressive disease comparable to HIV, have a higher chance of developing lymphoma when their peripheral blood contains elevated levels of the immunoglobulins kappa and lambda free light chains (FLCs).

METHODS

This systematic review's objective was to monitor associated B lymphoma cells in PTLD patients. In order to find relevant studies published between 1/1/2000 and 1/9/2022, two independent researchers conducted searches (MT, AJ). A literature search of English language publications was conducted using MEDLINE through PubMed, EMBASETM through Ovid, the Cochrane Library, and Trip. In addition to Magiran and SID, we searched KoreaMed and LILACS for literature published in other languages. sFLC or PTLD, transplant, or Electrophoresis are terms used in the search strategy.

RESULTS

A total of 174 studies were selected. After analyzing their correspondence with the required criteria, a final review of five studies was conducted. The manuscript presents current findings on the potential benefits of the clinical applicability of sFLCs in PTLD. While the preliminary results appear promising, the only consistent result is that early-onset PTLD is predicted within the first two years after transplant, a biomarker that could be used to diagnose the condition.

CONCLUSIONS

Therefore, PTLD has been predicted by using the sFLCs. There have been contradictory results to date. Future research could include assessing the quantity of sFLCs and their quality in transplant recipients. In addition to PTLD and complications after transplantation, sFLCs may provide insight into other diseases. To confirm the validity of sFLCs, more studies are needed.

Epstein-Barr Virus-Encoded BILF1 Orthologues From Porcine Lymphotropic Herpesviruses Display Common Molecular Functionality

Infection of immunosuppressed transplant patients with the human γ-herpesvirus Epstein-Barr virus (EBV) is associated with post-transplant lymphoproliferative disease (PTLD), an often fatal complication. Immunosuppressed miniature pigs infected with γ-herpesvirus porcine lymphotropic herpesvirus 1 (PLHV1) develop a similar disease, identifying pigs as a potential preclinical model for PTLD in humans. BILF1 is a G protein-coupled receptor (GPCR) encoded by EBV with constitutive activity linked to tumorigenesis and immunoevasive function downregulating MHC-I. In the present study, we compared BILF1-orthologues encoded by the three known PLHVs (PLHV1-3) with EBV-BILF1 to determine pharmacological suitability of BILF1 orthologues as model system to study EBV-BILF1 druggability. Cell surface localization, constitutive internalization, and MHC-I downregulation as well as membrane proximal constitutive Gα_i signaling patterns were conserved across all BILFs. Only subtle differences between the individual BILFs were observed in downstream transcription factor activation. Using Illumina sequencing, PLHV1 was observed in lymphatic tissue from PTLD-diseased, but not non-diseased pigs. Importantly, these tissues showed enhanced expression of PLHV1-BILF1 supporting its involvement in PTLD infection.

Stress-Induced Epstein-Barr Virus Reactivation

Epstein-Barr virus (EBV) is typically found in a latent, asymptomatic state in immunocompetent individuals. Perturbations of the host immune system can stimulate viral reactivation. Furthermore, there are a myriad of EBV-associated illnesses including various cancers, post-transplant lymphoproliferative disease, and autoimmune conditions. A thorough understanding of this virus, and the interplay between stress and the immune system, is essential to establish effective treatment. This review will provide a summary of the interaction between both psychological and cellular stressors resulting in EBV reactivation. It will examine mechanisms by which EBV establishes and maintains latency and will conclude with a brief overview of treatments targeting EBV.

Distinct immunopathological mechanisms of EBV-positive and EBV-negative posttransplant lymphoproliferative disorders

EBV-positive and EBV-negative posttransplant lymphoproliferative disorders (PTLDs) arise in different immunovirological contexts and might have distinct pathophysiologies. To examine this hypothesis, we conducted a multicentric prospective study with 56 EBV-positive and 39 EBV-negative PTLD patients of the K-VIROGREF cohort, recruited at PTLD diagnosis and before treatment (2013-2019), and compared them to PTLD-free Transplant Controls (TC, n = 21). We measured absolute lymphocyte counts (n = 108), analyzed NK- and T cell phenotypes (n = 49 and 94), and performed EBV-specific functional assays (n = 16 and 42) by multiparameter flow cytometry and ELISpot-IFNγ assays (n = 50). EBV-negative PTLD patients, NK cells overexpressed Tim-3; the 2-year progression-free survival (PFS) was poorer in patients with a CD4 lymphopenia (CD4⁺ <300 cells/mm³ , p <  .001). EBV-positive PTLD patients presented a profound NK-cell lymphopenia (median = 60 cells/mm³ ) and a high proportion of NK cells expressing PD-1 (vs. TC, p = .029) and apoptosis markers (vs. TC, p < .001). EBV-specific T cells of EBV-positive PTLD patients circulated in low proportions, showed immune exhaustion (p = .013 vs. TC) and poorly recognized the N-terminal portion of EBNA-3A viral protein. Altogether, this broad comparison of EBV-positive and EBV-negative PTLDs highlight distinct patterns of immunopathological mechanisms between these two diseases and provide new clues for immunotherapeutic strategies and PTLD prognosis.

The role of Epstein–Barr virus-encoded latent membrane proteins in host immune escape

Epstein–Barr virus (EBV) is a type IV herpesvirus that widely infects the vast majority of adults, and establishes a latent infection pattern in host cells to escape the clearance of immune system. The virus is intimately associated with the occurrence and progression of lymphomas and epithelial cell cancers. EBV latent membrane proteins (LMPs) can assist its immune escape by downregulating host immune response. Besides EBV, LMPs have important effects on the functions of exosomes and autophagy, which also help EBV to escape immune surveillance. These escape mechanisms may provide conditions for further development of EBV-associated tumors. In this article, we discussed the potential functions of EBV-encoded LMPs in promoting immune escape.

Current Practices on Diagnosis, Prevention and Treatment of Post-Transplant Lymphoproliferative Disorder in Pediatric Patients after Solid Organ Transplantation: Results of ERN TransplantChild Healthcare Working Group Survey

(1) Background: Post-transplant lymphoproliferative disease (PTLD) is a significant complication of solid organ transplantation (SOT). However, there is lack of consensus in PTLD management. Our aim was to establish a present benchmark for comparison between international centers and between various organ transplant systems and modalities; (2) Methods: A cross-sectional questionnaire of relevant PTLD practices in pediatric transplantation was sent to multidisciplinary teams from 17 European center members of ERN TransplantChild to evaluate the centers’ approach strategies for diagnosis and treatment and how current practices impact a cross-sectional series of PTLD cases; (3) Results: A total of 34 SOT programs from 13 European centers participated. The decision to start preemptive treatment and its guidance was based on both EBV viremia monitoring plus additional laboratory methods and clinical assessment (61%). Among treatment modalities the most common initial practice at diagnosis was to reduce the immunosuppression (61%). A total of 126 PTLD cases were reported during the period 2012–2016. According to their histopathological classification, monomorphic lesions were the most frequent (46%). Graft rejection after PTLD remission was 33%. Of the total cases diagnosed with PTLD, 88% survived; (4) Conclusions: There is still no consensus on prevention and treatment of PTLD, which implies the need to generate evidence. This might successively allow the development of clinical guidelines.

High numbers of programmed cell death-1-positive tumor infiltrating lymphocytes correlate with early onset of post-transplant lymphoproliferative disorder

Post-transplant lymphoproliferative disorder (PTLD) is a life-threatening complication of transplantation. In addition to reactivation of Epstein-Barr virus in immunocompromised patients, impaired tumor immunity is suggested to be a risk factor for PTLD. However, it remains unclear whether immune suppressive tumor-infiltrating lymphocytes (TILs) correlate with the occurrence or prognosis of PTLD. We analyzed TILs in 26 patients with PTLD to elucidate the clinicopathological significance of the expression of PD-1 and FoxP3, which are associated with exhausted T-cells and regulatory T-cells (Tregs), respectively. Numbers of PD-1⁺ TILs in the PTLD specimens were significantly higher in patients who developed PTLD early after transplantation (P = 0.0040), while numbers of FoxP3⁺ TILs were not (P = 0.184). There was no difference in overall response rate regardless of the expression of PD-1 or FoxP3. FoxP3^high patients tended to have a shorter time to progression compared with FoxP3^low patients, especially in the case of FoxP3^high patients with diffuse large B-cell lymphoma-subtype PTLD (P = 0.011), while PD-1^high patients did not. These results suggest that T-cell exhaustion may be mainly associated with PTLD development, while immune suppression by Tregs may be dominant in enhanced progression of PTLD following disease occurrence.

Natural Killer Cells in Post-Transplant Lymphoproliferative Disorders

Post-transplant lymphoproliferative disorders (PTLDs) are life-threatening complications arising after solid organ or hematopoietic stem cell transplantations. Although the majority of these lymphoproliferations are of B cell origin, and are frequently associated with primary Epstein-Barr virus (EBV) infection or reactivation in the post-transplant period, rare cases of T cell and natural killer (NK) cell-originated PTLDs have also been described. A general assumption is that PTLDs result from the impairment of anti-viral and anti-tumoral immunosurveillance due to the long-term use of immunosuppressants in transplant recipients. T cell impairment is known to play a critical role in the immune-pathogenesis of post-transplant EBV-linked complications, while the role of NK cells has been less investigated, and is probably different between EBV-positive and EBV-negative PTLDs. As a part of the innate immune response, NK cells are critical for protecting hosts during the early response to virus-induced tumors. The complexity of their function is modulated by a myriad of activating and inhibitory receptors expressed on cell surfaces. This review outlines our current understanding of NK cells in the pathogenesis of PTLD, and discusses their potential implications for current PTLD therapies and novel NK cell-based therapies for the containment of these disorders.

Non-Hodgkin Lymphomas: Malignancies Arising from Mature B Cells

Non-Hodgkin lymphomas (NHLs) are a diverse group of entities, both clinically and molecularly. Here, we review the evolution of classification schemes in B-cell lymphoma, noting the now standard WHO classification system that is based on immune cell-of-origin and molecular phenotypes. We review how lymphomas arise throughout the B-cell development process as well as the molecular and clinical features of prominent B-cell lymphomas. We provide an overview of the major progress that has occurred over the past decade in terms of our molecular understanding of these diseases. We discuss treatment options available and focus on a number of the diverse research tools that have been employed to improve our understanding of these diseases. We discuss the problem of heterogeneity in lymphomas and anticipate that the near future will bring significant advances that provide a measurable impact on NHL outcomes.

Innate and Adaptive Immune Correlates of Chronic and Self-limiting EBV DNAemia in Solid-organ Transplant Recipients

BACKGROUND

Epstein-Barr virus (EBV) DNAemia is a major risk factor for posttransplant lymphoproliferative disorder; however, immune correlates of EBV DNAemia in the transplant setting are limited.

METHODS

Peripheral blood mononuclear cells were collected from 30 transplant recipients with self-limiting EBV DNAemia (SLD; n = 11) or chronic EBV DNAemia (CD; n = 19) at enrollment and 4-8 weeks later. Mass cytometry was used to characterize innate and T-cell immune correlates of EBV DNAemia. Furthermore, flow cytometry was used to measure the frequency of EBV-specific T-cell responses between groups following stimulation with an EBV-infected cell lysate.

RESULTS

Unsupervised analysis of the innate compartment (CD3CD19 cells) identified 5 CD11c clusters at higher abundance in the SLD group (false discovery rate ≤ 1%). These clusters expressed CD11b, CD45RO, CD14, CD123, CD127, and CD38, among others. Unsupervised profiling of the T-cell compartment (CD3CD19) revealed 2 CD4 T-cell clusters at higher frequency among those with SLD (false discovery rate ≤ 1%), which expressed CD45RA, CCR7, CD27, CD28, and CD40L-suggestive of a naive T cell (TN). Manual biaxial gating confirmed increased frequencies of conventional dendritic cells (3.1% versus 2.1%; P = 0.023) and CD4 TN (4.4% versus 1.9%; P = 0.018) among those with SLD. Last, frequencies of interferon-γ-producing EBV-specific CD4 T cells were significantly lower in the CD group relative to those with SLD (4243 versus 250 cells/10 cells; P = 0.015).

CONCLUSIONS

CD is associated with a reduction of CD11c cells, CD4 TN, and interferon-γ-producing EBV-specific CD4 T cells, suggesting an interplay between innate and adaptive immune compartments may be important for regulating EBV DNAemia.

Post-transplantation lymphoproliferative disorder after haematopoietic stem cell transplantation

Post-transplantation lymphoproliferative disorder (PTLD) is a severe complication of haematopoietic stem cell transplantation (HSCT), occurring in a setting of immune suppression and dysregulation. The disease is in most cases driven by the reactivation of the Epstein-Barr virus (EBV), which induces B cell proliferation through different pathomechanisms. Beyond EBV, many factors, variably dependent on HSCT-related immunosuppression, contribute to the disease development. PTLDs share several features with primary lymphomas, though clinical manifestations may be different, frequently depending on extranodal involvement. According to the WHO classification, histologic examination is required for diagnosis, allowing also to distinguish among PTLD subtypes. However, in cases of severe and abrupt presentation, a diagnosis based on a combination of imaging studies and EBV-load determination is accepted. Therapies include prophylactic and pre-emptive interventions, aimed at eradicating EBV proliferation before symptoms onset, and targeted treatments. Among them, rituximab has emerged as first-line option, possibly combined with a reduction of immunosuppression, while EBV-specific cytotoxic T lymphocytes are effective and safe alternatives. Though prognosis remains poor, survival has markedly improved following the adoption of the aforementioned treatments. The validation of innovative, combined approaches is the future challenge.

The Fate of Speckled Protein 100 (Sp100) During Herpesviruses Infection

The constitutive expression of Speckled-100 (Sp100) is known to restrict the replication of many clinically important DNA viruses. This pre-existing (intrinsic) immune defense to virus infection can be further upregulated upon interferon (IFN) stimulation as a component of the innate immune response. In humans, Sp100 is encoded by a single gene locus, which can produce alternatively spliced isoforms. The widely studied Sp100A, Sp100B, Sp100C and Sp100HMG have functions associated with the transcriptional regulation of viral and cellular chromatin, either directly through their characteristic DNA-binding domains, or indirectly through post-translational modification (PTM) and associated protein interaction networks. Sp100 isoforms are resident component proteins of promyelocytic leukemia-nuclear bodies (PML-NBs), dynamic nuclear sub-structures which regulate host immune defenses against many pathogens. In the case of human herpesviruses, multiple protein antagonists are expressed to relieve viral DNA genome transcriptional silencing imposed by PML-NB and Sp100-derived proteinaceous structures, thereby stimulating viral propagation, pathogenesis, and transmission to new hosts. This review details how different Sp100 isoforms are manipulated during herpesviruses HSV1, VZV, HCMV, EBV, and KSHV infection, identifying gaps in our current knowledge, and highlighting future areas of research.

Infectious complications during immunochemotherapy of post-transplantation lymphoproliferative disease–can we decrease the risk? Two case reports and review of literature

BACKGROUND

Post-transplant lymphoproliferative disease (PTLD) is a heterogeneous group of diseases that develop after solid organ and hematopoietic stem cells transplantation related to intensive immunosuppression regimen, T-cell depletion and Epstein-Barr virus infection. Despite the improvement in the management of PTLD, the prognosis remains poor. Here we report the management of two transplanted patients with PTLD and infections during immunochemotherapy (ICTH).

CASE SUMMARY

Of 65-year-old woman 11 years after kidney transplantation (first case) presented with diffuse large B-cell lymphoma (DLBCL) CS III and started ICHT according to R-CHOP protocol. Despite the secondary prevention of neutropenic fever, the patient developed grade 4 neutropenia with urinary and pulmonary tract infections after the fifth cycle. ICTH was continued in reduced doses up to 7 cycles followed by involved-field radiation therapy of the residual disease. The second case presents a 49-year-old man, 8 years after liver transplantation due to cirrhosis in the course of chronic hepatitis B, who started ICTH for DLBCL Burkitt-like CS IV. The patient received four cycles of ICTH according to R-CODOX/R-IVAC protocol, with reduced doses. In both cases initially undertaken reduction of immunosuppression was ineffective to prevent infectious complications. Despite one incomplete ICHT treatment due to recurrent infections, both our patients remain in complete remission.

CONCLUSION

Reduction of immunosuppression and the doses of chemotherapeutics may be insufficient to prevent infectious complications during ICTH in PTLD patients.

Epstein-Barr Virus and Monoclonal Gammopathy of Clinical Significance in Autologous Stem Cell Transplantation for Multiple Sclerosis

INTRODUCTION

Autologous hematopoietic stem cell transplantation (AHSCT) with anti-thymocyte globulin (ATG) conditioning as treatment of active multiple sclerosis (MS) is rapidly increasing across Europe (EBMT registry data 2017). Clinically significant Epstein-Barr virus reactivation (EBV-R) following AHSCT with ATG for severe autoimmune conditions is an underrecognized complication relative to T-cell deplete transplants performed for hematological diseases. This retrospective study reports EBV-R associated significant clinical sequelae in MS patients undergoing AHSCT with rabbit ATG.

METHODS

Retrospective data were analyzed for 36 consecutive MS-AHSCT patients at Kings College Hospital, London. All patients routinely underwent weekly EBV DNA polymerase chain reaction monitoring and serum electrophoresis for monoclonal gammopathy (MG or M-protein). EBV-R with rising Epstein-Barr viral load, M-protein, and associated clinical sequelae were captured from clinical records.

RESULTS

All patients had evidence of rising EBV DNA-emia, including 7 who were lost to long-term follow-up, with a number of them developing high EBV viral load and associated lymphoproliferative disorder (LPD). Nearly 72% (n = 18/29) developed de novo MG, some with significant neurological consequences with high M-protein and EBV-R. Six patients required anti-CD20 therapy (rituximab) with complete resolution of EBV related symptoms. Receiver operating characteristics estimated a peak EBV viremia of >500 000 DNA copies/mL correlated with high sensitivity (85.5%) and specificity (82.5%) (area under the curve: 0.87; P = .004) in predicting EBV-R related significant clinical events.

CONCLUSION

Symptomatic EBV reactivation increases risk of neurological sequelae and LPD in MS-AHSCT. We recommend regular monitoring for EBV and serum electrophoresis for MG in MS patients in the first 3 months post-AHSCT.

Post Transplant Lymphoproliferative Disorder risk factors in children: Analysis of a 23-year single-institutional experience

INTRODUCTION

PTLD is the most frequent malignancy following SOT in children and the second most common SOT complication in adults. However, factors determining outcomes in children are poorly understood due to its relative rarity.

METHODS

This study was performed at the University of Florida. Univariate and multivariate analyses were used to identify prognostic factors in pediatric patients diagnosed with PTLD.

RESULTS

We reviewed records of 54 pediatric (younger than 18 years old at diagnosis) patients diagnosed with PTLD from 1994 to 2017. The median follow-up was 28.8 months. The estimated 5-year survival rate was 87.6% (95% CI 74.3-94.2%). Univariate analysis showed that organ transplanted (specifically heart transplant), poor response to initial treatment, allograft rejection, and low Karnofsky score were statistically significant for negative prognostic factors in determining survival. Multivariate analysis determined progression in response to initial treatment and presence of allograft rejection as statistically significant prognostic factors affecting overall survival. We found no statistically significant impact of EBV serological status on PTLD prognosis.

CONCLUSIONS

Disease progression and allograft rejection were strong negative prognostic indicators in our study cohort. Close attention to graft status and development of therapies that protect the graft from rejection while bolstering anti-EBV immunity will be essential to further improving PTLD outcomes in children.

Co-infection of Cytomegalovirus and Epstein-Barr Virus Diminishes the Frequency of CD56dimNKG2A+KIR- NK Cells and Contributes to Suboptimal Control of EBV in Immunosuppressed Children With Post-transplant Lymphoproliferative Disorder

Post-transplant lymphoproliferative disorder (PTLD) is a rare but potentially life-threatening complication, frequently associated with Epstein-Barr virus (EBV), which develops after solid organ or stem cell transplantation. Immunosuppression received by transplant recipients has a significant impact on the development of PTLD by suppressing the function of T cells. The preferential proliferation of NKG2A-positive natural killer (NK) cells during primary symptomatic EBV infection known as infectious mononucleosis (IM) and their reactivity toward EBV-infected B cells point to a role of NK cell in the immune control of EBV. However, NK cell-mediated immune response to EBV in immunosuppressed transplant recipients who develop PTLD remains unclear. In this study, we longitudinally analyzed the phenotype and function of different NK cell subsets in a cohort of pediatric liver transplant patients who develop PTLD and compared them to those of children with IM. We found persistently elevated plasma EBV DNA levels in the PTLD patients indicating suboptimal anti-viral immune control. PTLD patients had markedly decreased frequency of CD56^dimNKG2A⁺Killer Immunoglobulin-like receptor (KIR)⁻ NK cells from the time of diagnosis through remission compared to those of IM patients. Whilst the proliferation of CD56^dimNKG2A⁺KIR⁻ NK cells was diminished in PTLD patients, this NK cell subset maintained its ability to potently degranulate against EBV-infected B cells. Compared to cytomegalovirus (CMV)-seropositive and -negative IM patients, PTLD patients co-infected with CMV and EBV had significantly higher levels of a CMV-associated CD56^dimNKG2C^hiCD57⁺NKG2A⁻KIR⁺ NK cell subset accumulating at the expense of NKG2A⁺KIR⁻ NK cells. Taken together, our data indicate that co-infection of CMV and EBV diminishes the frequency of CD56^dimNKG2A⁺KIR⁻ NK cells and contributes to suboptimal control of EBV in immunosuppressed children with PTLD.

Comparative study between chronic immune thrombocytopenia patients and healthy population on Epstein-Barr virus infection status by polymerase chain reaction

BACKGROUND

Immune thrombocytopenia (ITP) has been known to be associated with assorted virus infections. This study aims to investigate the Epstein-Barr virus infection status in chronic ITP patients by real-time quantitative polymerase chain reaction.

METHODS

42 chronic ITP patients and 42 healthy donors were retrospectively included via propensity score matching with gender and age. EBV-DNA levels in whole blood of patients and donors were assessed by RT-qPCR, and correlations between virus load and platelet count were analyzed.

RESULTS

The positive rate of EBV-DNA in lymphocytes of chronic ITP patients was significantly higher than that in donors (52.4% vs 31.0%, p = 0.046). Platelet count [18(8-45)×10⁹/L] of patients with high virus load in lymphocytes was significantly lower than that [51(30-87)×10⁹/L] of patients with low virus load (p = 0.0001), whereas no difference was observed in platelet count between EBV-DNA-positive and negative subgroups of donors (p = 0.984). And a significant inverse correlation was observed between EBV-DNA levels in lymphocytes and platelet count (r = -0.4958, p = 0.019) in patients, which was independent from the presence of platelet-associated IgG.

CONCLUSIONS

EBV infection has a potential role in the development of chronic ITP. Identification and control of this underlying infection should be emphasized in the treatment of chronic ITP.

Impact of EBV infection and immune function assay for lymphoproliferative disorder in pediatric patients after liver transplantation: A single-center experience

BACKGROUND

Post-transplant lymphoproliferative disorder (PTLD) is a lethal complication after pediatric liver transplantation, but information regarding risk factors for the development of PTLD remains unclear. This study was to identify characteristics and risk factors of PTLD.

METHODS

A total of 705 pediatric patients who underwent liver transplantation between January 2017 and October 2018 were studied. Impact of clinical characteristics and Epstein-Barr virus (EBV) infection on the development of PTLD was evaluated. In addition, ImmuKnow assay was adopted in partial patients to analyze the immune status.

RESULTS

Twenty-five (3.5%) patients suffered from PLTD with a median time of 6 months (3-14 months) after transplantation. Extremely high tacrolimus (TAC) level was found in 2 fatal cases at PTLD onset. EBV infection was found in 468 (66.4%) patients. A higher peak EBV DNA loads (>9590 copies/mL) within 3 months was a significant indicator for the onset of PTLD. In addition, the ImmuKnow assay demonstrated that overall immune response was significantly lower in patients with EBV infection and PTLD (P<0.0001). The cumulative incidence of PTLD was also higher in patients with lower ATP value (≤187 ng/mL, P<0.05).

CONCLUSIONS

A careful monitoring of EBV DNA loads and tacrolimus concentration might be supportive in prevention of PTLD in pediatric patients after liver transplantation. In addition, application of the ImmuKnow assay may provide guidance in reducing immunosuppressive agents in treatment of PTLD.

Natural killer cells as modulators of alloimmune responses

PURPOSE OF REVIEW

Natural killer (NK) cells are effector cells of the innate immune system that can lyse target cells without prior sensitization and are important in host defense to virally infected and transformed cells. Although the concept of 'missing-self' would suggest NK cells could target foreign allografts, the prevailing dogma has been that NK cells are not active participants in the rejection of solid organ allografts. This review summarizes recent studies that challenge this conclusion and instead suggest NK cells are important in outcomes posttransplant.

RECENT FINDINGS

NK cells expressing specific cell surface receptors may promote graft damage and rejection. However, recent studies suggest some NK cell subsets have tolerogenic or immunoregulatory potential and promote graft stability, suggesting a dichotomous role for NK cells after transplant. Furthermore, NK cells respond to cells infected with cytomegalovirus and Epstein-Barr virus, and studies suggest some NK cells have immune memory.

SUMMARY

Our understanding of the role of NK cells posttransplant has evolved from 'no role' to the current idea that NK cells may have 'complex interactions' that impact graft outcomes. Additional studies, using cutting edge techniques to comprehensively analyze the phenotypic and functional subsets of NK cells in transplant recipients, are clearly necessary.

Epstein-Barr virus-positive post-transplant lymphoproliferative disordepresenting as hematochezia and enterobrosis in renal transplant recipients in China: A report of two cases

BACKGROUND

Post-transplant lymphoproliferative disorder (PTLD) is a rare severe complication after renal transplantation, with an incidence of approximately 0.3%-2.0% in patients undergoing renal transplantation. The clinical manifestations of PTLD are often nonspecific, leading to tremendous challenges in the clinical diagnosis and treatment of PTLD.

CASE SUMMARY

We report two Epstein-Barr virus (EBV)-positive PTLD cases whose main clinical manifestations were digestive tract symptoms. Both of them admitted to our hospital because of extranodal infiltration symptoms and we did not suspect of PTLD until the pathology confirmation. Luckily, they responded well to the treatment of rituximab. We also discuss the virological monitoring, clinical characteristics, diagnosis, and treatment of PTLD.

CONCLUSION

PTLD is a deceptive disease and difficult to diagnose. Once patients are confirmed with PTLD, immune suppressant dosage should be immediately reduced and rituximab should be used as first-line therapy.

Epstein-Barr Virus Latent Membrane Protein 1 Regulates Host B Cell MicroRNA-155 and Its Target FOXO3a via PI3K p110α Activation

Epstein-Barr Virus (EBV) is associated with potentially fatal lymphoproliferations such as post-transplant lymphoproliferative disorder (PTLD), a serious complication of transplantation. The viral mechanisms underlying the development and maintenance of EBV+ B cell lymphomas remain elusive but represent attractive therapeutic targets. EBV modulates the expression of host microRNAs (miRs), non-coding RNAs that regulate gene expression, to promote survival of EBV+ B cell lymphomas. Here, we examined how the primary oncogene of EBV, latent membrane protein 1 (LMP1), regulates host miRs using an established model of inducible LMP1 signaling. LMP1 derived from the B95.8 lab strain or PTLD induced expression of the oncogene miR-155. However, PTLD variant LMP1 lost the ability to upregulate the tumor suppressor miR-193. Small molecule inhibitors (SMI) of p38 MAPK, NF-κB, and PI3K p110α inhibited upregulation of miR-155 by B95.8 LMP1; no individual SMI significantly reduced upregulation of miR-155 by PTLD variant LMP1. miR-155 was significantly elevated in EBV+ B cell lymphoma cell lines and associated exosomes and inversely correlated with expression of the miR-155 target FOXO3a in cell lines. Finally, LMP1 reduced expression of FOXO3a, which was rescued by a PI3K p110α SMI. Our data indicate that tumor variant LMP1 differentially regulates host B cell miR expression, suggesting viral genotype as an important consideration for the treatment of EBV+ B cell lymphomas. Notably, we demonstrate a novel mechanism in which LMP1 supports the regulation of miR-155 and its target FOXO3a in B cells through activation of PI3K p110α. This mechanism expands on the previously established mechanisms by which LMP1 regulates miR-155 and FOXO3a and may represent both rational therapeutic targets and biomarkers for EBV+ B cell lymphomas.

Post-transplant lymphoproliferative disorders, Epstein-Barr virus infection, and disease in solid organ transplantation: Guidelines from the American Society of Transplantation Infectious Diseases Community of Practice

PTLD with the response-dependent sequential use of RIS, rituximab, and cytotoxic chemotherapy is recommended. Evidence gaps requiring future research and alternate treatment strategies including immunotherapy are highlighted.

Evaluation of the Abbott RealTime quantitative CMV and EBV assays using the maxCycle protocol in a laboratory automation context

Real-time PCR are often used for the diagnosis and monitoring of Cytomegalovirus (CMV) and Epstein-Barr virus (EBV) infections in susceptible populations. In this context, we evaluated the analytical performances of the Abbott RealTime CMV/EBV maxCycle protocol automated on the m2000 platform (Abbott). It was compared to our routinely-used procedure consisting of a NucleoMag® DNA extraction automated on a STARlet platform followed by manually processed CMV and EBV quantitative real-time PCR (Diagenode). In this study, we showed that both EBV assays exhibited a similar sensitivity but with a better precision for the EBV Abbott RealTime assay. For the CMV performances, the Abbott assay was more sensitive and more precise than our routine method. The use of WHO International Standards also indicated a slight underestimation of the viral loads (-0.25 log₁₀ IU/mL and -0.21 log₁₀ IU/mL for CMV and EBV assays respectively) while these were rather overestimated with the Starlet/Diagenode method (0.48 log₁₀ IU/mL and 0.19 log₁₀ IU/mL for CMV and EBV assays respectively). These trends were confirmed using relevant whole-blood clinical samples and external quality controls. The workflows were also compared and we highlighted a significant technician hands-on time reduction (-63%) using the Abbott CMV/EBV maxCycle automated protocol.

Update on posttransplant lymphoproliferative disease

PURPOSE OF REVIEW

Posttransplant lymphoproliferative disorder (PTLD), frequently associated with Epstein-Barr virus (EBV), is one of the most serious complications leading to worse patient and graft outcomes. Hence, we summarize in this review relevant studies published about PTLD in the last 18 months.

RECENT FINDINGS

Recent studies have improved the knowledge about epidemiology, prophylaxis, diagnosis and PTLD treatment. Special interest has developed in improving the last PTLD classification of the World Health Organization, increasing the accuracy of diagnostic tests for EBV viral load quantification and discriminating the genetic differences between PTLD types. There seems to be no real advantage in the use of antiviral drugs for prophylaxis, but better results in therapeutic approaches are being obtained mainly with the use of rituximab with or without chemotherapy, but also with the possibility of using adoptive T-cell therapy or new drugs.

SUMMARY

PTLD continues being a complication that requires continued effort of the scientific community to reduce its incidence and to develop better diagnostic tests and new strategies that improve results in prophylaxis and treatment.

The Tumor Microenvironment in Post-Transplant Lymphoproliferative Disorders

Post-transplant lymphoproliferative disorders (PTLDs) cover a broad spectrum of lymphoproliferative lesions arising after solid organ or allogeneic hematopoietic stem cell transplantation. The composition and function of the tumor microenvironment (TME), consisting of all non-malignant constituents of a tumor, is greatly impacted in PTLD through a complex interplay between 4 factors: 1) the graft organ causes immune stimulation through chronic antigen presentation; 2) the therapy to prevent organ rejection interferes with the immune system; 3) the oncogenic Epstein-Barr virus (EBV), present in 80% of PTLDs, has a causative role in the oncogenic transformation of lymphocytes and influences immune responses; 4) interaction with the donor-derived immune cells accompanying the graft. These factors make PTLDs an interesting model to look at cancer-microenvironment interactions and current findings can be of interest for other malignancies including solid tumors. Here we will review the current knowledge of the TME composition in PTLD with a focus on the different factors involved in PTLD development.

Dissecting the Multiplicity of Immune Effects of Immunosuppressive Drugs to Better Predict the Risk of de novo Malignancies in Solid Organ Transplant Patients

De novo malignancies constitute an emerging cause of morbidity after solid organ transplant (SOT), significantly affecting the long-term survival of transplant recipients. Pharmacologic immunosuppression may functionally impair the immunosurveillance in these patients, thereby increasing the risk of cancer development. Nevertheless, the multiplicity and heterogeneity of the immune effects induced by immunosuppressive drugs limit the current possibilities to reliably predict the risk of de novo malignancy in SOT patients. Therefore, there is the pressing need to better characterize the immune dysfunctions induced by the different immunosuppressive regimens administered to prevent allograft rejection to tailor more precisely the therapeutic schedule and decrease the risk of de novo malignancies. We herein highlight the impact exerted by different classes of immunosuppressants on the most relevant immune cells, with a particular focus on the effects on dendritic cells (DCs), the main regulators of the balance between immunosurveillance and tolerance.

The frequency of Epstein-Barr virus among hemodialysis patients, Ahvaz, Iran

BACKGROUND AND OBJECTIVES

Epstein-Barr virus (EBV) has infected more than 90% of adults worldwide. EBV infection is asymptomatic in healthy individuals and is controlled by a robust immune response while in individuals with weakened immunesystems including Hemodialysis (HD) patients and transplant recipients leads to serious illnesses. This study was aimed to investigate the frequency of EBV among the HD patients.

MATERIALS AND METHODS

The cross-sectional study was carried out on 84 HD patients. These sera were checked for anti-EBV (VCA) IgG Ab assessment using enzyme-linked immunosorbent assay (ELISA). The DNA was extracted from the sera samples and tested for EBV DNA using nested PCR.

RESULTS

52/84 (61.9%) of HD were males and 32/84 (38.1%) were females. The average age of participants was varying from 18 to 85 years while the mean age was 52 ± 1.57 SD years. 81 of 84 (96.42%); including 49/52 (94.23%) male and 32/32 (100%) female, were positive for anti-EBV (VCA) IgG antibody while 3 (3.58%) were negative. No significant differences were observed between the subjects regarding gender (P=0.28). EBV DNA was detected in 7 (8.33%) individuals, including 6 (11.53%) and 1 (3.12%) in male and female, respectively (P=0.24).

CONCLUSION

Our study results showed that high prevalence of anti-EBV (VCA) IgG antibody (96.42%) were observed among the HD patients. Although the status of EBV latency was not performed, but it seems many of these patients are at risk of EBV-reactivation during the organ transplantation. As a result, it is recommended that the detection of EBNA-1 gene as a marker of EBV latency should be implemented for all HD patients to prevent EBV reactivation during organ transplantation.

Improvements in intestine transplantation

Transplantation of the intestine in children has presented significant challenges even as it has become a standard to treat nutritional failure due to short gut syndrome. These challenges have been addressed in part by significant improvements in short and long-term care. Noteworthy enhancements include reduced need for intestine transplantation, drug-sparing immunosuppressive regimens, immune monitoring, and improved surveillance and management of PTLD and non-adherence.

Post-transplant lymphoproliferative disorder in pediatric intestinal transplant recipients: A literature review

Intestinal transplantation is a successful treatment for children with intestinal failure, but has many potential complications. PTLD, a clinically and histologically diverse malignancy, occurs frequently after intestinal transplantation and can be fatal. The management of this disease is particularly challenging. The rejection-prone intestinal allograft requires high levels of immunosuppression, a precondition for PTLD. While EBV infection clearly plays a role in disease pathogenesis, the relatively naïve immune system of children is another likely contributor. As a result, pediatric intestine recipients have a higher risk of developing PTLD than other solid organ recipients. Other risk factors for disease development such as molecular and genomic changes that precipitate malignant transformation are not fully understood, especially among children. Studies on adults have started to describe the molecular pathogenesis of PTLD, but the genomic landscape of the malignancy remains largely undefined in pediatric intestinal transplant patients. In this review, we describe what is known about PTLD in pediatric patients after intestinal transplant and highlight current knowledge gaps to better direct future investigations in the pediatric population.

The value of EBV DNA in early detection of post-transplant lymphoproliferative disorders among solid organ and hematopoietic stem cell transplant recipients

PURPOSE

Emerging EBV DNAemia in plasma is considered an early sign of post-transplant lymphoproliferative disorder (PTLD). The aim of this study was to quantify the extent of benefit from screening for EBV DNAemia to detect emerging PTLD among solid organ (SOT) or hematopoietic stem cell transplant recipients (HSCT).

METHODS

We used receiver operating characteristic (ROC) curves for assessing ability of models to predict PTLD. Among 2642 recipients transplanted between January 2004 and December 2014, 79 (3%) developed PTLD.

RESULTS

EBV DNAemia was observed in 331/1784 recipients (18.6%, 95% CI 16.8-20.4) with measured EBV DNA. The area under the curve (AUC) of the ROC of EBV DNAemia to identify persons with subsequent PTLD was 72% (95% CI, 64-79%) among SOT and 59% (51-68%) among HSCT. Including clinical predictors such as age, gender, transplant year and type, high-risk EBV serostatus, and routine biochemistry in addition to EBV DNAemia increased AUC to 83% (75-90%) among SOT and 84% (79-89%) among HSCT. Among HSCT, including additional factors such as T-cell-depleting treatment, acute graft vs. host disease and donor match increased AUC to 85% (78-91%).

CONCLUSIONS

We constructed a model to better predict PTLD compared to EBV DNA screening alone which could have clinical implications.