Aflatoxin B1 and Epstein-Barr virus-induced CCL22 expression stimulates B cell infection.

Epstein-Barr Virus (EBV) infects more than 90% of the adult population worldwide. EBV infection is associated with Burkitt lymphoma (BL) though alone is not sufficient to induce carcinogenesis implying the involvement of co-factors. BL is endemic in African regions faced with mycotoxins exposure. Exposure to mycotoxins and oncogenic viruses has been shown to increase cancer risks partly through the deregulation of the immune response. A recent transcriptome profiling of B cells exposed to aflatoxin B1 (AFB1) revealed an upregulation of the Chemokine ligand 22 (CCL22) expression although the underlying mechanisms were not investigated. Here, we tested whether mycotoxins and EBV exposure may together contribute to endemic BL (eBL) carcinogenesis via immunomodulatory mechanisms involving CCL22. Our results revealed that B cells exposure to AFB1 and EBV synergistically stimulated CCL22 secretion via the activation of Nuclear Factor-kappa B pathway. By expressing EBV latent genes in B cells, we revealed that elevated levels of CCL22 result not only from the expression of the latent membrane protein LMP1 as previously reported but also from the expression of other viral latent genes. Importantly, CCL22 overexpression resulting from AFB1-exposure in vitro increased EBV infection through the activation of phosphoinositide-3-kinase pathway. Moreover, inhibiting CCL22 in vitro and in humanized mice in vivo limited EBV infection and decreased viral genes expression, supporting the notion that CCL22 overexpression plays an important role in B cell infection. These findings unravel new mechanisms that may underpin eBL development and identify novel pathways that can be targeted in drug development.

Burkitt lymphoma risk shows geographic and temporal associations with Plasmodium falciparum infections in Uganda, Tanzania, and Kenya.

Endemic Burkitt lymphoma (eBL) is a pediatric cancer coendemic with malaria in sub-Saharan Africa, suggesting an etiological link between them. However, previous cross-sectional studies of limited geographic areas have not found a convincing association. We used spatially detailed data from the Epidemiology of Burkitt Lymphoma in East African Children and Minors (EMBLEM) study to assess this relationship. EMBLEM is a case-control study of eBL from 2010 through 2016 in six regions of Kenya, Uganda, and Tanzania. To measure the intensity of exposure to the malaria parasite, Plasmodium falciparum, among children in these regions, we used high-resolution spatial data from the Malaria Atlas Project to estimate the annual number of P. falciparum infections from 2000 through 2016 for each of 49 districts within the study region. Cumulative P. falciparum exposure, calculated as the sum of annual infections by birth cohort, varied widely, with a median of 47 estimated infections per child by age 10, ranging from 4 to 315 infections. eBL incidence increased 39% for each 100 additional lifetime P. falciparum infections (95% CI: 6.10 to 81.04%) with the risk peaking among children aged 5 to 11 and declining thereafter. Alternative models using estimated annual P. falciparum infections 0 to 10 y before eBL onset were inconclusive, suggesting that eBL risk is a function of cumulative rather than recent cross-sectional exposure. Our findings provide population-level evidence that eBL is a phenotype related to heavy lifetime exposure to P. falciparum malaria and support emphasizing the link between malaria and eBL.

CD4 + T cells are found within endemic Burkitt lymphoma and modulate Burkitt lymphoma precursor cell viability and expression of pathogenically relevant Epstein-Barr virus genes.

Endemic Burkitt lymphoma (eBL) is an aggressive B cell cancer characterized by an IgH/c-myc translocation and the harboring of Epstein-Barr virus (EBV). Evidence accumulates that CD4 + T cells might contribute to eBL pathogenesis. Here, we investigate the presence of CD4 + T cells in primary eBL tissue and their potential dichotomous impact on an EBV-infected pre-eBL cell model using ex vivo material and in vitro co-cultures. In addition, we establish a novel method to study the effect of IgH/c-myc translocation in primary B cells by employing a CRISPR/Cas9 knock-in approach to introduce and tag de novo translocation. We unprecedently document that CD4 + T cells are present in primary eBL tumor tissue. Furthermore, we demonstrate that CD4 + T cells on the one hand suppress eBL development by killing pre-eBL cells lacking IgH/c-myc translocation in vitro and on the other hand indirectly promote eBL development by inducing crucial EBV Latency III to Latency I switching in pre-eBL cells. Finally, we show that while the mere presence of an IgH/c-myc translocation does not suffice to escape CD4 + T-cell-mediated killing in vitro, the CD4 + T-cell-mediated suppression of EBV's Latency III program in vivo may allow cells harboring an IgH/c-myc translocation and additional mutations to evade immune control and proliferate by means of deregulated c-myc activity, resulting in neoplasia. Thus, our study highlights the dichotomous effects of CD4 + T cells and the mechanisms involved in eBL pathogenesis, suggests mechanisms of their impact on eBL progression, and provides a novel in vitro model for further investigation of IgH/c-myc translocation.

Profiling genome-wide recombination in Epstein Barr virus reveals type-specific patterns and associations with endemic-Burkitt lymphoma.

BACKGROUND: Endemic Burkitt lymphoma (eBL) is potentiated through the interplay of Epstein Barr virus (EBV) and holoendemic Plasmodium falciparum malaria. To better understand EBV's biology and role in eBL, we characterized genome-wide recombination sites and patterns as a source of genetic diversity in EBV genomes in our well-defined population of eBL cases and controls from Western Kenya. METHODS: EBV genomes representing 54 eBL cases and 32 healthy children from the same geographic region in Western Kenya that we previously sequenced were analyzed. Whole-genome multiple sequence alignment, recombination analyses, and phylogenetic inference were made using multiple alignment with fast Fourier transform, recombination detection program 4, and molecular evolutionary genetics analysis. RESULTS: We identified 28 different recombination events and 71 (82.6%) of the 86 EBV genomes analyzed contained evidence of one or more recombinant segments. Associated recombination breakpoints were found to occur in a total of 42 different genes, with only 7 (16.67%) being latent genes. Recombination events were major drivers of clustering within genome-wide phylogenetic trees. The occurrence of recombination segments was comparable between genomes from male and female participants and across age groups. More recombinant segments were found in EBV type 1 genomes (p = 6.4e - 06) and the genomes from the eBLs (p = 0.037). Two recombination events were enriched in the eBLs; event 47 (OR = 4.07, p = 0.038) and event 50 (OR = 14.24, p = 0.012). CONCLUSIONS: EBV genomes have extensive evidence of recombination likely acquired progressively and cumulatively over time. Recombination patterns display a heterogeneous occurrence rate across the genome with enrichment in lytic genes. Overall, recombination appears to be a major evolutionary force impacting EBV diversity and genome structure with evidence of the association of specific recombinants with eBL.

Epstein-Barr Virus Genomes Reveal Population Structure and Type 1 Association with Endemic Burkitt Lymphoma.

Endemic Burkitt lymphoma (eBL), the most prevalent pediatric cancer in sub-Saharan Africa, is distinguished by its inclusion of Epstein-Barr virus (EBV). In order to better understand the impact of EBV variation in eBL tumorigenesis, we improved viral DNA enrichment methods and generated a total of 98 new EBV genomes from both eBL cases (n = 58) and healthy controls (n = 40) residing in the same geographic region in Kenya. Using our unbiased methods, we found that EBV type 1 was significantly more prevalent in eBL patients (74.5%) than in healthy children (47.5%) (odds ratio = 3.24, 95% confidence interval = 1.36 to 7.71, P = 0.007), as opposed to similar proportions in both groups. Controlling for EBV type, we also performed a genome-wide association study identifying six nonsynonymous variants in the genes EBNA1, EBNA2, BcLF1, and BARF1 that were enriched in eBL patients. In addition, viruses isolated from plasma of eBL patients were identical to their tumor counterparts consistent with circulating viral DNA originating from the tumor. We also detected three intertypic recombinants carrying type 1 EBNA2 and type 2 EBNA3 regions, as well as one novel genome with a 20-kb deletion, resulting in the loss of multiple lytic and virion genes. Comparing EBV types, viral genes displayed differential variation rates as type 1 appeared to be more divergent, while type 2 demonstrated novel substructures. Overall, our findings highlight the complexities of the EBV population structure and provide new insight into viral variation, potentially deepening our understanding of eBL oncogenesis.IMPORTANCE Improved viral enrichment methods conclusively demonstrate EBV type 1 to be more prevalent in eBL patients than in geographically matched healthy controls, which previously underrepresented the prevalence of EBV type 2. Genome-wide association analysis between cases and controls identifies six eBL-associated nonsynonymous variants in EBNA1, EBNA2, BcLF1, and BARF1 genes. Analysis of population structure reveals that EBV type 2 exists as two genomic subgroups and was more commonly found in female than in male eBL patients.

Kaposi Sarcoma-Associated Herpesvirus Infection and Endemic Burkitt Lymphoma.

BACKGROUND: Endemic Burkitt lymphoma (eBL) is associated with Epstein-Barr virus (EBV) and Plasmodium falciparum malaria coinfections. However, the role of Kaposi sarcoma-associated herpesvirus (KSHV), also endemic in Africa, has not been evaluated as a cofactor in eBL pathogenesis. METHODS: Multiplexed seroprofiles for EBV, malaria, and KSHV were generated for 266 eBL patients, 78 non-eBL cancers, and 202 healthy children. KSHV and EBV loads were quantified by PCR. RESULTS: KSHV seroprevalence did not differ by study group but was associated with age. Seropositivity, defined by K8.1/LANA or in combination with 5 other KSHV antigens (ORF59, ORF65, ORF61, ORF38, and K5) was associated with antimalarial antibody levels to AMA1 (odds ratio [OR], 2.41, P < .001; OR, 2.07, P < .001) and MSP1 (OR, 2.41, P = .0006; OR, 5.78, P < .001), respectively. KSHV loads did not correlate with antibody levels nor differ across groups but were significantly lower in children with detectable EBV viremia (P = .014). CONCLUSIONS: Although KSHV-EBV dual infection does not increase eBL risk, EBV appears to suppress reactivation of KSHV while malaria exposure is associated with KSHV infection and/or reactivation. Both EBV and malaria should, therefore, be considered as potential effect modifiers for KSHV-associated cancers in sub-Saharan Africa.

Reliable cell and tissue morphology-based diagnosis of endemic Burkitt lymphoma in resource-constrained settings in Ghana.

BACKGROUND: Endemic Burkitt lymphoma (eBL) is an aggressive B-cell lymphoma, which is a common childhood cancer in areas with intense transmission of Plasmodium falciparum parasites. Early and accurate diagnosis is a prerequisite for successful therapy, but it optimally involves advanced laboratory investigations. These are technologically demanding, expensive, and often difficult to implement in settings where eBL is prevalent. Diagnosis is thus generally based on clinical assessment and morphological examination of tumour biopsies or fine-needle aspirates (FNAs). METHODS: The purpose of the present study was to assess the accuracy of eBL diagnosis at two tertiary hospitals in Ghana. To that end, we studied FNAs from 29 eBL patients and 21 non-eBL lymphoma patients originally diagnosed in 2018. In addition, we examined 111 archival formalin-fixed and paraffin-embedded (FFPE) biopsies from Ghanaian patients originally diagnosed as eBL (N = 55) or non-eBL (N = 56) between 2010 and 2017. Availability-based subsets of samples were subjected to haematoxylin-eosin or Giemsa staining, C-MYC immunohistochemistry, and fluorescence in situ hybridisation (FISH) analysis of c-myc rearrangements. RESULTS: We found a good correlation between original diagnosis and subsequent retrospective assessment, particularly for FNA samples. However, evidence of intact c-myc genes and normal C-MYC expression in samples from some patients originally diagnosed as eBL indicates that morphological assessment alone can lead to eBL over-diagnosis in our study area. In addition, several FFPE samples could not be assessed retrospectively, due to poor sample quality. Therefore, the simpler FNA method of obtaining tumour material is preferable, particularly when careful processing of biopsy specimens cannot be guaranteed. CONCLUSION: We conclude that the accuracy of eBL diagnostic tools available in Ghana is generally adequate, but could be improved by implementation of additional pathology laboratory investigations. Improved attention to adequate preservation of archival samples is recommended.

Integrative microRNA and mRNA deep-sequencing expression profiling in endemic Burkitt lymphoma.

BACKGROUND: Burkitt lymphoma (BL) is characterized by overexpression of the c-myc oncogene, which in the vast majority of cases is a consequence of an IGH/MYC translocation. While myc is the seminal event, BL is a complex amalgam of genetic and epigenetic changes causing dysregulation of both coding and non-coding transcripts. Emerging evidence suggest that abnormal modulation of mRNA transcription via miRNAs might be a significant factor in lymphomagenesis. However, the alterations in these miRNAs and their correlations to their putative mRNA targets have not been extensively studied relative to normal germinal center (GC) B cells. METHODS: Using more sensitive and specific transcriptome deep sequencing, we compared previously published small miRNA and long mRNA of a set of GC B cells and eBL tumors. MiRWalk2.0 was used to identify the validated target genes for the deregulated miRNAs, which would be important for understanding the regulatory networks associated with eBL development. RESULTS: We found 211 differentially expressed (DE) genes (79 upregulated and 132 downregulated) and 49 DE miRNAs (22 up-regulated and 27 down-regulated). Gene Set enrichment analysis identified the enrichment of a set of MYC regulated genes. Network propagation-based method and correlated miRNA-mRNA expression analysis identified dysregulated miRNAs, including miR-17~95 cluster members and their target genes, which have diverse oncogenic properties to be critical to eBL lymphomagenesis. Central to all these findings, we observed the downregulation of ATM and NLK genes, which represent important regulators in response to DNA damage in eBL tumor cells. These tumor suppressors were targeted by multiple upregulated miRNAs (miR-19b-3p, miR-26a-5p, miR-30b-5p, miR-92a-5p and miR-27b-3p) which could account for their aberrant expression in eBL. CONCLUSION: Combined loss of p53 induction and function due to miRNA-mediated regulation of ATM and NLK, together with the upregulation of TFAP4, may be a central role for human miRNAs in eBL oncogenesis. This facilitates survival of eBL tumor cells with the IGH/MYC chromosomal translocation and promotes MYC-induced cell cycle progression, initiating eBL lymphomagenesis. This characterization of miRNA-mRNA interactions in eBL relative to GC B cells provides new insights on miRNA-mediated transcript regulation in eBL, which are potentially useful for new improved therapeutic strategies.

Endemic Burkitt Lymphoma: Long-term Outcome in 87 Patients Who Presented With Paraplegia in Cameroon.

The reported long-term outcome of endemic Burkitt lymphoma (eBL) patients who present with paraplegia is largely unknown. Records of BL patients treated with comparable short-interval cyclophosphamide chemotherapy schedules between 2004 and 2014 at three Baptist mission hospitals in Cameroon were reviewed. Survivors were followed up and examined at home or in hospital. Eighty-seven of 948 (9.2%) patients had paraplegia at diagnosis. The survival rate in eBL patients with paraplegia at diagnosis was 33% (n = 29) after follow-up of between 2 and 96 (median 40) months. Seven patients (24%) had neurological sequelae and needed rehabilitation. There was no relationship between the duration of symptoms (<2, 2-4, >4 weeks) and the survival rate or the risk to have neurological sequelae. The survival rate and risk for sequelae were similar in patients with confirmed St. Jude stage III and IV diseases.

Sickle cell trait is not associated with endemic Burkitt lymphoma: an ethnicity and malaria endemicity-matched case-control study suggests factors controlling EBV may serve as a predictive biomarker for this pediatric cancer.

Endemic Burkitt lymphoma (eBL) is associated with Epstein-Barr virus (EBV) and Plasmodium falciparum coinfections. Malaria appears to dysregulate immunity that would otherwise control EBV, thereby contributing to eBL etiology. Juxtaposed to human genetic variants associated with protection from malaria, it has been hypothesized that such variants could decrease eBL susceptibility, historically referred to as "the protective hypothesis." Past studies attempting to link sickle cell trait (HbAS), which is known to be protective against malaria, with protection from eBL were contradictory and underpowered. Therefore, using a case-control study design, we examined HbAS frequency in 306 Kenyan children diagnosed with eBL compared to 537 geographically defined and ethnically matched controls. We found 23.8% HbAS for eBL patients, which was not significantly different compared to 27.0% HbAS for controls [odds ratio (OR) = 0.85; 95% confidence interval (CI) 0.61-1.17; p-value = 0.33]. Even though cellular EBV titers, indicative of the number of latently infected B cells, were significantly higher (p-value < 0.0003) in children residing in malaria holoendemic compared to hypoendemic areas, levels were not associated with HbAS genotype. Combined, this suggests that although HbAS protects against severe malaria and hyperparasitemia, it is not associated with viral control or eBL protection. However, based on receiver operating characteristic curves factors that enable the establishment of EBV persistence, in contrast to those involved in EBV lytic reactivation, may have utility as an eBL precursor biomarker. This has implications for future human genetic association studies to consider variants influencing control over EBV in addition to malaria as risk factors for eBL.

The Rapid Growth of Burkitt Lymphoma Causing Partial Small Bowel Obstruction.

Burkitt lymphoma (BL) is a neoplasm of the lymphoid tissue and one of the most prevalent malignancies worldwide. Classically, these patients present with unregulated B-cell differentiation causing fever, chills, night sweats, and weight loss. Although more common in children, in sporadic Burkitt lymphoma, symptoms often can be present in the abdomen. These patients also additionally report nausea, vomiting, and abdominal distention, which in rare instances can cause small bowel obstruction (SBO). Early detection and the initiation of chemotherapy remain highly effective in providing adequate care. This provides better outcomes and prevents surgical management.

Lymph Node Penetration From Gastric Burkitt Lymphoma in a Patient Living With HIV/AIDS.

Non-Hodgkin's Lymphoma (NHL) in people living with Human Immunodeficiency Virus/Acquired Immunodeficiency Syndrome (HIV/AIDS) still constitutes a reality of high morbidity and mortality, sometimes not respecting the patient's degree of immunosuppression as it can even occur in those with a high CD4+ T lymphocyte count. Burkitt's lymphoma, in this sense, has been shown to be one of the main subtypes of this condition in this group of patients. This case report concerns a 32-year-old man diagnosed with metastatic gastric Burkitt's lymphoma after one month of his admission to a tertiary hospital for neurological complaints. The aim of this study is to raise an alert to suspect this diagnosis even in patients with adequate immunity, a well-done history, and a physical examination, which are the main pillars for reaching a diagnosis.

Piperlongumine inhibits LMP1/MYC-dependent mouse B-lymphoma cells.

Piperlongumine (PL), isolated from the fruit of Long pepper, Piper longum, is a cancer-inhibiting compound that selectively kills tumor cells while sparing their normal counterparts. Here we evaluated the efficacy with which PL suppresses malignant B cells derived from a newly developed, double-transgenic mouse model of human endemic Burkitt lymphoma (BL), designated mCD40-LMP1/iMyc(Eµ). PL inhibited tumor cell proliferation in a concentration-dependent manner and induced apoptosis of neoplastic but not normal B cells. Treatment with PL resulted in downregulation of EBV-encoded LMP1, cellular Myc, constitutive NF-κB activity, and a host of LMP1-Myc-NF-κB-regulated target genes including Aurka, Bcat1, Bub1b, Ccnb1, Chek1, Fancd2, Tfrc and Xrcc6. Of note, p21(Cip1)-encoding Cdkn1a was suppressed independent of changes in Trp53 mRNA levels and p53 DNA-binding activity. Considering the central role of the LMP1-NF-κB-Myc axis in B-lineage neoplasia, these findings further our understanding of the mechanisms by which PL inhibits B-lymphoma and provide a preclinical rationale for the inclusion of PL in new interventions in blood cancers.

Malaria Infection and Risk for Endemic Burkitt Lymphoma: A Systematic Review and Meta-Analysis.

Background: Malaria infection is reportedly linked to endemic Burkitt lymphoma (eBL) in malaria-endemic areas. This study aimed to pool the overall risk (or odds) of eBL among children with previous or concurrent malaria infection. Methods: We searched PubMed, Web of Science, Scopus, and reference lists of publications for potentially relevant studies on malaria infection and eBL. The quality of the included studies was assessed using the Joanna Briggs Institute for case-control studies. Random-effects meta-analysis was used to summarize whether the odds of eBL can be increased by (1) malaria infection or (2) elevated titer of IgGs to malaria antigen. The level of heterogeneity was evaluated using Cochran's Q statistic and I2. The individual study data, pooled odds, and confidence interval (CI) were illustrated using the forest plot. Publication bias was assessed using funnel plots and Egger's test. Results: Ten studies were included, reporting the number of malaria cases in eBL and non-eBL (5 studied malaria infection and the odds of eBL; five studied the burden of IgGs to malarial antigens and the odds of eBL). According to the meta-analysis results, the odds of eBL was not increased by malaria infection (p = 0.562, OR: 0.87, 95% CI: 0.54-1.39, I2: 93.5%, malaria in eBL: 604/1506 cases, malaria in non-eBL: 2117/4549 cases) and the elevated titer of IgGs to malaria antigen (p = 0.051, OR: 1.50, 95% CI: 1.00-2.25, I2: 89%, increased IgG titer in eBL: 1059/1736 cases, increased IgG titer in non-eBL: 847/1722 cases). In meta-regression analysis, sex was not a confounding factor for the effect size of malaria infection and eBL (p = 0.10) and that of increased IgGs and eBL (p = 0.80). Conclusions: Malaria infection and IgG titer elevation did not increase the risk for eBL among children. However, the included studies, which are only few, do not generally agree on this point. Therefore, the risk for eBL in children diagnosed with malaria should be investigated further by longitudinal studies to confirm our evidence-based approach.

Interplay between IL-10, IFN-γ, IL-17A and PD-1 Expressing EBNA1-Specific CD4+ and CD8+ T Cell Responses in the Etiologic Pathway to Endemic Burkitt Lymphoma.

Children diagnosed with endemic Burkitt lymphoma (eBL) are deficient in interferon-γ (IFN-γ) responses to Epstein-Barr Nuclear Antigen1 (EBNA1), the viral protein that defines the latency I pattern in this B cell tumor. However, the contributions of immune-regulatory cytokines and phenotypes of the EBNA1-specific T cells have not been characterized for eBL. Using a bespoke flow cytometry assay we measured intracellular IFN-γ, IL-10, IL-17A expression and phenotyped CD4+ and CD8+ T cell effector memory subsets specific to EBNA1 for eBL patients compared to two groups of healthy children with divergent malaria exposures. In response to EBNA1 and a malaria antigen (PfSEA-1A), the three study groups exhibited strikingly different cytokine expression and T cell memory profiles. EBNA1-specific IFN-γ-producing CD4+ T cell response rates were lowest in eBL (40%) compared to children with high malaria (84%) and low malaria (66%) exposures (p < 0.0001 and p = 0.0004, respectively). However, eBL patients did not differ in CD8+ T cell response rates or the magnitude of IFN-γ expression. In contrast, eBL children were more likely to have EBNA1-specific CD4+ T cells expressing IL-10, and less likely to have polyfunctional IFN-γ+IL-10+ CD4+ T cells (p = 0.02). They were also more likely to have IFN-γ+IL-17A+, IFN-γ+ and IL-17A+ CD8+ T cell subsets compared to healthy children. Cytokine-producing T cell subsets were predominantly CD45RA+CCR7+ TNAIVE-LIKE cells, yet PD-1, a marker of persistent activation/exhaustion, was more highly expressed by the central memory (TCM) and effector memory (TEM) T cell subsets. In summary, our study suggests that IL-10 mediated immune regulation and depletion of IFN-γ+ EBNA1-specific CD4+ T cells are complementary mechanisms that contribute to impaired T cell cytotoxicity in eBL pathogenesis.

Endemic Burkitt lymphoma - an aggressive childhood cancer linked to Plasmodium falciparum exposure, but not to exposure to other malaria parasites.

Burkitt lymphoma (BL) is an aggressive non-Hodgkin lymphoma. The prevalence of BL is ten-fold higher in areas with stable transmission of Plasmodium falciparum malaria, where it is the most common childhood cancer, and is referred to as endemic BL (eBL). In addition to its association with exposure to P. falciparum infection, eBL is strongly associated with Epstein-Barr virus (EBV) infection (>90%). This is in contrast to BL as it occurs outside P. falciparum-endemic areas (sporadic BL), where only a minority of the tumours are EBV-positive. Although the striking geographical overlap in the distribution of eBL and P. falciparum was noted shortly after the first detailed description of eBL in 1958, the molecular details of the interaction between malaria and eBL remain unresolved. It is furthermore unexplained why exposure to P. falciparum appears to be essentially a prerequisite to the development of eBL, whereas other types of malaria parasites that infect humans have no impact. In this brief review, we summarize how malaria exposure may precipitate the malignant transformation of a B-cell clone that leads to eBL, and propose an explanation for why P. falciparum uniquely has this capacity.

A New Hope for CD56negCD16pos NK Cells as Unconventional Cytotoxic Mediators: An Adaptation to Chronic Diseases.

Natural Killer (NK) cells play an essential role in antiviral and anti-tumoral immune responses. In peripheral blood, NK cells are commonly classified into two major subsets: CD56brightCD16neg and CD56dimCD16pos despite the characterization of a CD56negCD16pos subset 25 years ago. Since then, several studies have described the prevalence of an CD56negCD16pos NK cell subset in viral non-controllers as the basis for their NK cell dysfunction. However, the mechanistic basis for their cytotoxic impairment is unclear. Recently, using a strict flow cytometry gating strategy to exclude monocytes, we reported an accumulation of CD56negCD16pos NK cells in Plasmodium falciparum malaria-exposed children and pediatric cancer patients diagnosed with endemic Burkitt lymphoma (eBL). Here, we use live-sorted cells, histological staining, bulk RNA-sequencing and flow cytometry to confirm that this CD56negCD16pos NK cell subset has the same morphological features as the other NK cell subsets and a similar transcriptional profile compared to CD56dimCD16pos NK cells with only 120 genes differentially expressed (fold change of 1.5, p < 0.01 and FDR<0.05) out of 9235 transcripts. CD56negCD16pos NK cells have a distinct profile with significantly higher expression of MPEG1 (perforin 2), FCGR3B (CD16b), FCGR2A, and FCGR2B (CD32A and B) as well as CD6, CD84, HLA-DR, LILRB1/2, and PDCD1 (PD-1), whereas Interleukin 18 (IL18) receptor genes (IL18RAP and IL18R1), cytotoxic genes such as KLRF1 (NKp80) and NCR1 (NKp46), and inhibitory HAVCR2 (TIM-3) are significantly down-regulated compared to CD56dimCD16pos NK cells. Together, these data confirm that CD56negCD16pos cells are legitimate NK cells, yet their transcriptional and protein expression profiles suggest their cytotoxic potential is mediated by pathways reliant on antibodies such as antibody-dependent cell cytotoxicity (ADCC), antibody-dependent respiratory burst (ADRB), and enhanced by complement receptor 3 (CR3) and FAS/FASL interaction. Our findings support the premise that chronic diseases induce NK cell modifications that circumvent proinflammatory mediators involved in direct cytotoxicity. Therefore, individuals with such altered NK cell profiles may respond differently to NK-mediated immunotherapies, infections or vaccines depending on which cytotoxic mechanisms are being engaged.

Lytic Induction Therapy against Epstein-Barr Virus-Associated Malignancies: Past, Present, and Future.

Epstein-Barr virus (EBV) lytic induction therapy is an emerging virus-targeted therapeutic approach that exploits the presence of EBV in tumor cells to confer specific killing effects against EBV-associated malignancies. Efforts have been made in the past years to uncover the mechanisms of EBV latent-lytic switch and discover different classes of chemical compounds that can reactivate the EBV lytic cycle. Despite the growing list of compounds showing potential to be used in the lytic induction therapy, only a few are being tested in clinical trials, with varying degrees of success. This review will summarize the current knowledge on EBV lytic reactivation, the major hurdles of translating the lytic induction therapy into clinical settings, and highlight some potential strategies in the future development of this therapy for EBV-related lymphoid and epithelial malignancies.

[Retrospective study about 20 cases of ovarian Burkitt lymphoma at Yopougon teaching hospital in Côte d'Ivoire]. / Étude rétrospective rapportant 20 cas de lymphome de Burkitt de localisation ovarienne pris en charge au CHU de Yopougon en Côte d'Ivoire.

CONTEXT: The maxillo-facial attack was the first described in the Burkitt lymphoma in 1958 by Denis Pearsons Burkitt. Abdominopelvic disorders, particularly ovarian localization are observed more and more by the developments of imagery technics. Our study aimed to describe the epidemiologic, clinical, therapeutic and evolutive aspects of ovarian localization in the endemic Burkitt lymphoma. METHODOLOGY: Twenty files of ovarian Burkitt lymphoma diagnosed in the clinical service of hematology TH of Yopougon during the period August 1995-March 2015 (19 years) were retrospectively analyzed. The epidemiologic, clinical, therapeutic and evolutive parameters were studied. RESULTS: Ovarian Burkitt lymphoma accounted for 20.41% of the population with Burkitt lymphoma and 38.46% for patients with Burkitt lymphoma. The average age was 20.4 years with extremes of 6 and 38 years. The main reasons for consultation were general impairment (85%) and pelvic mass (80%). 75% were in group B clinical scalability. The ovarian mass was bilateral in 60% of cases, heterogeneous in 75% of cases. There was a clear predominance of stage III of Murphy (55%). On the evolutionary level all the patients treated by chemotherapy were in incomplete remission (100%). 10% were alive. 83.33% of the deceased patients had received less than 6 courses of chemotherapy. CONCLUSION: The diagnosis of ovarian endemic Burkitt lymphoma is most often delayed diagnosis and poor prognosis. Improving its management requires early diagnosis.

Human and Epstein-Barr Virus miRNA Profiling as Predictive Biomarkers for Endemic Burkitt Lymphoma.

Endemic Burkitt lymphoma (eBL) is an aggressive B cell lymphoma and is associated with Epstein-Barr virus (EBV) and Plasmodium falciparum malaria co-infections. Central to BL oncogenesis is the over-expression of the MYC proto-oncogene which is caused by a translocation of an Ig enhancer in approximation to the myc gene. While whole genome/transcriptome sequencing methods have been used to define driver mutations and transcriptional dysregulation, microRNA (miRNA) dysregulation and differential expression has yet to be fully characterized. We hypothesized that both human and EBV miRNAs contribute to eBL clinical presentation, disease progression, and poor outcomes. Using sensitive and precise deep sequencing, we identified miRNAs from 17 Kenyan eBL patient tumor samples and delineated the complement of both host and EBV miRNAs. One human miRNA, hsa-miR-10a-5p was found to be differentially expressed (DE), being down-regulated in jaw tumors relative to abdominal and in non-survivors compared to survivors. We also examined EBV miRNAs, which made up 2.7% of the miRNA composition in the eBL samples. However, we did not find any significant associations regarding initial patient outcome or anatomical presentation. Gene ontology analysis and pathway enrichment of previously validated targets of miR-10a-5p suggest that it can promote tumor cell survival as well as aid in evasion of apoptosis. To examine miR-10a-5p regulatory effect on gene expression in eBL, we performed a pairwise correlation coefficient analysis on the expression levels of all its validated targets. We found a significant enrichment of correlated target genes consistent with miR-10a-5p impacting expression. The functions of genes and their correlation fit with multiple target genes impacting tumor resilience. The observed downregulation of miR-10a and associated genes suggests a role for miRNA in eBL patient outcomes and has potential as a predictive biomarker that warrants further investigation.