Biochemical strategies of E3 ubiquitin ligases target viruses in critical diseases.

Viruses are known to cause various diseases in human and also infect other species such as animal plants, fungi, and bacteria. Replication of viruses depends upon their interaction with hosts. Human cells are prone to such unwanted viral infections. Disintegration and reconstitution require host machinery and various macromolecules like DNA, RNA, and proteins are invaded by viral particles. E3 ubiquitin ligases are known for their specific function, that is, recognition of their respective substrates for intracellular degradation. Still, we do not understand how ubiquitin proteasome system-based enzymes E3 ubiquitin ligases do their functional interaction with different viruses. Whether E3 ubiquitin ligases help in the elimination of viral components or viruses utilize their molecular capabilities in their intracellular propagation is not clear. The first time our current article comprehends fundamental concepts and new insights on the different viruses and their interaction with various E3 Ubiquitin Ligases. In this review, we highlight the molecular pathomechanism of viruses linked with E3 Ubiquitin Ligases dependent mechanisms. An enhanced understanding of E3 Ubiquitin Ligase-mediated removal of viral proteins may open new therapeutic strategies against viral infections.

Kaposi's sarcoma-associated herpesvirus promotes mesenchymal-to-endothelial transition by resolving the bivalent chromatin of PROX1 gene.

Increasing evidence suggests that Kaposi's sarcoma (KS) arises from Kaposi's sarcoma-associated herpesvirus (KSHV)-infected mesenchymal stem cells (MSCs) through mesenchymal-to-endothelial transition (MEndT). KSHV infection promotes MSC differentiation of endothelial lineage and acquisition of tumorigeneic phenotypes. To understand how KSHV induces MEndT and transforms MSCs to KS cells, we investigated the mechanism underlying KSHV-mediated MSC endothelial lineage differentiation. Like embryonic stem cells, MSC differentiation and fate determination are under epigenetic control. Prospero homeobox 1 (PROX1) is a master regulator that controls lymphatic vessel development and endothelial differentiation. We found that the PROX1 gene in MSCs harbors a distinctive bivalent epigenetic signature consisting of both active marker H3K4me3 and repressive marker H3K27me3, which poises expression of the genes, allowing timely activation upon differentiation signals or environmental stimuli. KSHV infection effectively resolves the bivalent chromatin by decreasing H3K27me3 and increasing H3K4me3 to activate the PROX1 gene. vIL-6 signaling leads to the recruitment of MLL2 and SET1 complexes to the PROX1 promoter to increase H3K4me3, and the vGPCR-VEGF-A axis is responsible for removing PRC2 from the promoter to reduce H3K27me3. Therefore, through a dual signaling process, KSHV activates PROX1 gene expression and initiates MEndT, which renders MSC tumorigenic features including angiogenesis, invasion and migration.

The ability of post-chemoradiotherapy DWI ADCmean and 18F-FDG SUVmax to predict treatment outcomes in head and neck cancer: impact of human papilloma virus oropharyngeal cancer status.

OBJECTIVES: To evaluate the ability of post-chemo-radiotherapy (CRT) diffusion-weighted-MRI apparent diffusion coefficient (ADCmean) and 18F-FDG PET maximum standardized uptake value (SUVmax) to predict disease-free survival (DFS) in head and neck squamous cell carcinoma (HNSCC), and to determine whether this ability is influenced by human papillomavirus oropharyngeal cancer (HPV-OPC) status. METHODS: This prospective cohort observational study included 65 participants (53 male, mean ± SD age 59.9 ± 7.9 years, 46 HPV-OPC) with stage III or IV HNSCC. Primary tumour and nodal ADCmean (pre-treatment, 6- and 12-weeks post-CRT) and SUVmax (12-weeks post-CRT) were measured. Variables were compared with 2-year DFS (independent t-test/Mann-Whitney test) and overall DFS (Cox regression), before and after accounting for HPV-OPC status. Variables were also compared between HPV-OPC and other HNSCC subgroups after stratifying for DFS. RESULTS: Absolute post-CRT ADCmean values predicted 2-year DFS and overall DFS for all participants (p = 0.03/0.03, 6-week node; p = 0.02/0.03 12-week primary tumour) but not in the HPV-OPC subgroup. In participants with DFS, percentage interval changes in primary tumour ADCmean at 6- and 12-weeks were higher in HPV-OPC than other HNSCC (p = 0.01, 6 weeks; p = 0.005, 12 weeks). The 12-week post-CRT SUVmax did not predict DFS. CONCLUSION: Absolute post-CRT ADCmean values predicted DFS in HNSCC but not in the HPV-OPC subgroup. Amongst participants with DFS, post-CRT percentage interval changes in primary tumour ADCmean were significantly higher in HPV-OPC than in other HNSCC. Knowledge of HPV-OPC status is crucial to the clinical utilisation of post-CRT DWI-MRI for the prediction of outcomes.

Epigenetic Plasticity Enables CNS-Trafficking of EBV-infected B Lymphocytes.

Subpopulations of B-lymphocytes traffic to different sites and organs to provide diverse and tissue-specific functions. Here, we provide evidence that epigenetic differences confer a neuroinvasive phenotype. An EBV+ B cell lymphoma cell line (M14) with low frequency trafficking to the CNS was neuroadapted to generate a highly neuroinvasive B-cell population (MUN14). MUN14 B cells efficiently infiltrated the CNS within one week and produced neurological pathologies. We compared the gene expression profiles of viral and cellular genes using RNA-Seq and identified one viral (EBNA1) and several cellular gene candidates, including secreted phosphoprotein 1/osteopontin (SPP1/OPN), neuron navigator 3 (NAV3), CXCR4, and germinal center-associated signaling and motility protein (GCSAM) that were selectively upregulated in MUN14. ATAC-Seq and ChIP-qPCR revealed that these gene expression changes correlated with epigenetic changes at gene regulatory elements. The neuroinvasive phenotype could be attenuated with a neutralizing antibody to OPN, confirming the functional role of this protein in trafficking EBV+ B cells to the CNS. These studies indicate that B-cell trafficking to the CNS can be acquired by epigenetic adaptations and provide a new model to study B-cell neuroinvasion associated CNS lymphoma and autoimmune disease of the CNS, including multiple sclerosis (MS).

[Lymphomas in immunocompromised patients]. / Lymphomes de l'immunodéprimé.

Immunosuppression is a well known risk factor for the development of lymphoid pathologies. The classification of these neoplasias is becoming more precise and complex, some features being common to all immunocompromised patients, primarily the important influence of Epstein-Barr virus. Whatever the origin of the immunodepression, these lymphoid proliferations are very heterogeneous, constituting a wide range between polymorphic aspects and clearly lymphomatous morphologies indistinguishable from those observed in immunocompetent subjects. It is important to detect precisely these different categories of proliferation within each group of immunosuppression, to better individualize the prognosis and the management of patients.

Estimating the Natural History of Cervical Carcinogenesis Using Simulation Models: A CISNET Comparative Analysis.

BACKGROUND: The natural history of human papillomavirus (HPV)-induced cervical cancer (CC) is not directly observable, yet the age of HPV acquisition and duration of preclinical disease (dwell time) influences the effectiveness of alternative preventive policies. We performed a Cancer Intervention and Surveillance Modeling Network (CISNET) comparative modeling analysis to characterize the age of acquisition of cancer-causing HPV infections and implied dwell times for distinct phases of cervical carcinogenesis. METHODS: Using four CISNET-cervical models with varying underlying structures but fit to common US epidemiological data, we estimated the age of acquisition of causal HPV infections and dwell times associated with three phases of cancer development: HPV, high-grade precancer, and cancer sojourn time. We stratified these estimates by HPV genotype under both natural history and CC screening scenarios, because screening prevents cancer development that affects the mix of detected cancers. RESULTS: The median time from HPV acquisition to cancer detection ranged from 17.5 to 26.0 years across the four models. Three models projected that 50% of unscreened women acquired their causal HPV infection between ages 19 and 23 years, whereas one model projected these infections occurred later (age 34 years). In the context of imperfect compliance with US screening guidelines, the median age of causal infection was 4.4-15.9 years later compared with model projections in the absence of screening. CONCLUSIONS: These validated CISNET-CC models, which reflect some uncertainty in the development of CC, elucidate important drivers of HPV vaccination and CC screening policies and emphasize the value of comparative modeling when evaluating public health policies.

Thirty years of Epstein-Barr virus-associated gastric carcinoma.

Thirty years have passed since a possible association of Epstein-Barr virus (EBV) with gastric carcinoma was reported. We now know EBV-associated gastric carcinoma to be a specific subtype of gastric carcinoma. Global epigenetic methylation and counteraction of the antitumour microenvironment are two major characteristics of this subtype of gastric carcinoma. Recent development of therapeutic modalities for gastric carcinoma, such as endoscopic mucosal dissection and immune checkpoint inhibitor therapy, has made the presence of EBV infection a biomarker for the treatment of gastric carcinoma. This review presents a portrait of EBV-associated gastric carcinoma from initiation to maturity that we define as the 'gastritis-infection-cancer sequence', followed by its molecular abnormalities and interactions with immune checkpoint molecules and the microenvironment. EBV non-coding RNAs (microRNA and circular RNA) and exosomes derived from EBV-infected cells that were previously behind the scenes are now recognized for their roles in EBV-associated gastric carcinoma. The virus utilizes cellular machinery skilfully to control infected cells and their microenvironment. We should thus strive to understand virus-host interactions more fully in the following years to overcome this virus-driven subtype of gastric carcinoma.

Novel replisome-associated proteins at cellular replication forks in EBV-transformed B lymphocytes.

Epstein-Barr virus (EBV) is an oncogenic herpesvirus and WHO class 1 carcinogen that resides in B lymphocytes of nearly all humans. While silent in most, EBV can cause endemic Burkitt lymphoma in children and post-transplant lymphoproliferative disorders/lymphomas in immunocompromised hosts. The pathogenesis of such lymphomas is multifactorial but to a large extent depends on EBV's ability to aggressively drive cellular DNA replication and B cell proliferation despite cell-intrinsic barriers to replication. One such barrier is oncogenic replication stress which hinders the progression of DNA replication forks. To understand how EBV successfully overcomes replication stress, we examined cellular replication forks in EBV-transformed B cells using iPOND (isolation of Proteins on Nascent DNA)-mass spectrometry and identified several cellular proteins that had not previously been linked to DNA replication. Of eight candidate replisome-associated proteins that we validated at forks in EBV-transformed cells and Burkitt lymphoma-derived cells, three zinc finger proteins (ZFPs) were upregulated early in B cells newly-infected with EBV in culture as well as expressed at high levels in EBV-infected B blasts in the blood of immunocompromised transplant recipients. Expressed highly in S- and G2-phase cells, knockdown of each ZFP resulted in stalling of proliferating cells in the S-phase, cleavage of caspase 3, and cell death. These proteins, newly-identified at replication forks of EBV-transformed and Burkitt lymphoma cells therefore contribute to cell survival and cell cycle progression, and represent novel targets for intervention of EBV-lymphomas while simultaneously offering a window into how the replication machinery may be similarly modified in other cancers.

Epstein-Barr virus infection in gliomas.

PURPOSE OF THE STUDY: Epstein-Barr virus (EBV) has been involved in the development of some tumors, including Burkitt's lymphoma and Hodgkin's lymphoma. However, its potential role in glioma tumorigenesis remains debated. In this study, we investigated the EBV infection in gliomas from Tunisian patients. PATIENTS AND METHODS: We conducted a retrospective study of 112 gliomas on archival material. The EBV DNA sequence was analyzed by polymerase chain reaction (PCR). Latent membrane protein 1 (LMP1) was detected by immunohistochemistry. In situ hybridization was used to detect EBV encoded small RNA (EBER). Clinicopathological features were recorded. Survival analysis was carried out using the Kaplan-Meier method and the Log-Rank test to compare EBV-positive and EBV-negative patients. RESULTS: Overall, there were twenty-four EBV-positive gliomas (21.4%). EBV DNA was identified in 24 cases. LMP1 and EBER were detected in four EBV DNA-positive cases. All EBV-positive cases were glioblastomas multiforme (GBM). Median overall survival and recurrence-free survival of EBV-negative patients were better than those of EBV-positive patients (Log Rank p = 0.006). CONCLUSION: Altogether, these findings support the occurrence of EBV infection in Tunisian GBM. Furthermore, when compared to EBV-negative tumors, EBV infection seems to be associated with the worst patient prognosis. Advanced molecular studies are recommended to confirm these results and to shed further light on the potential role of EBV in these devastating tumors.

Evaluating the Utility and Prevalence of HPV Biomarkers in Oral Rinses and Serology for HPV-related Oropharyngeal Cancer.

Performance of commercially available human papillomavirus (HPV) assays (approved for cervical HPV detection) is unknown for detecting HPV-related oropharyngeal cancer (HPV-OPC). Assays for detection of HPV DNA [ELISA (DEIA) and Cobas], and RNA (Aptima) in oral rinse samples, and serum HPV oncogene antibodies were evaluated. Sensitivity and specificity of each test was explored among HPV-OPC cases and controls. Biomarker prevalence was evaluated among 294 "at-risk" people (screening) and 133 "high-risk" people [known to previously have oral oncogenic HPV (oncHPV) DNA and/or HPV16 E6/E7 antibodies detected]. HPV16 E6 antibodies had the best overall test performance with sensitivity of 88%, compared with oral HPV16 DNA sensitivity of 51% by DEIA and 43% by Cobas (each P < 0.001). Specificity was comparable in each of these tests (≥98%). When positivity for any oncHPV type was compared with HPV16 for the same test, sensitivity was comparable (60% vs. 51%, 40% vs. 43%, and 92% vs. 88% for DEIA, Cobas, and E6 antibodies, respectively), but specificity was reduced (93%-97%). Aptima had poor sensitivity (23%). Sensitivity decreased when cotesting HPV16 oral rinse DNA and E6 antibodies (37%-48%), or multiple E antibodies (69%-72%). HPV16 DNA were detected in ∼2% of the at-risk by either DEIA or Cobas and up to 15% of the high-risk population. HPV16 E6 seroprevalence was 2.3% and 2.4% in the at-risk and high-risk populations, respectively. Oral rinse HPV testing had moderate-to-poor sensitivity for HPV-OPC, suggesting many true positives would be missed in a potential screening scenario. HPV16 E6 serum antibody was the most promising biomarker evaluated.

Repression of Death Receptor-Mediated Apoptosis of Hepatocytes by Hepatitis B Virus e Antigen.

Hepatitis B virus (HBV) e antigen (HBeAg) is associated with viral persistence and pathogenesis. Resistance of HBV-infected hepatocytes to apoptosis is seen as one of the primary promotors for HBV chronicity and malignancy. Fas receptor/ligand (Fas/FasL) and the tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) system plays a key role in hepatic death during HBV infection. We found that HBeAg mediates resistance of hepatocytes to FasL or TRAIL-induced apoptosis. Introduction of HBeAg into human hepatocytes rendered resistance to FasL or TRAIL cytotoxicity in a p53-dependent manner. HBeAg further inhibited the expression of p53, total Fas, membrane-bound Fas, TNF receptor superfamily member 10a, and TNF receptor superfamily member 10b at both mRNA and protein levels. In contrast, HBeAg enhanced the expression of soluble forms of Fas through facilitation of Fas alternative mRNA splicing. In a mouse model, expression of HBeAg in mice injected with recombinant adenovirus-associated virus 8 inhibited agonistic anti-Fas antibody-induced hepatic apoptosis. Xenograft tumorigenicity assay also found that HBeAg-induced carcinogenesis was resistant to the proapoptotic effect of TRAIL and chemotherapeutic drugs. These results indicate that HBeAg may prevent hepatocytes from FasL and TRAIL-induced apoptosis by regulating the expression of the proapoptotic and antiapoptotic forms of death receptors, which may contribute to the survival and persistence of infected hepatocytes during HBV infection.

[HPV: Carcinogenic implications and preventive measures]. / Le papillomavirus : implications carcinologiques et mesures préventives.

Human oncogenic papillomaviruses (HPV) have an increasingly prominent role in the genesis of many cancers. The oncogenic mechanisms associated with HPV are now better known and make it possible to explain the etiopathogenesis of the association. HPV status is now sought for certain cancers and conditions both prognosis and management of patients. Preventive antiviral vaccination has become a real public health issue and aims to effectively reduce the prevalence of cervical, anal and oropharynx cancer, HPV-associated. However, vaccination against HPV still lags behind. The purpose of this review is to redefine the involvement of HPV in several cancers as well as current therapeutic challenges of HPV-related cancers, notably in term of prevention.

Increased association between Epstein-Barr virus EBNA2 from type 2 strains and the transcriptional repressor BS69 restricts EBNA2 activity.

Natural variation separates Epstein-Barr virus (EBV) into type 1 and type 2 strains. Type 2 EBV is less transforming in vitro due to sequence differences in the EBV transcription factor EBNA2. This correlates with reduced activation of the EBV oncogene LMP1 and some cell genes. Transcriptional activation by type 1 EBNA2 can be suppressed through the binding of two PXLXP motifs in its transactivation domain (TAD) to the dimeric coiled-coil MYND domain (CC-MYND) of the BS69 repressor protein (ZMYND11). We identified a third conserved PXLXP motif in type 2 EBNA2. We found that type 2 EBNA2 peptides containing this motif bound BS69CC-MYND efficiently and that the type 2 EBNA2TAD bound an additional BS69CC-MYND molecule. Full-length type 2 EBNA2 also bound BS69 more efficiently in pull-down assays. Molecular weight analysis and low-resolution structures obtained using small-angle X-ray scattering showed that three BS69CC-MYND dimers bound two molecules of type 2 EBNA2TAD, in line with the dimeric state of full-length EBNA2 in vivo. Importantly, mutation of the third BS69 binding motif in type 2 EBNA2 improved B-cell growth maintenance and the transcriptional activation of the LMP1 and CXCR7 genes. Our data indicate that increased association with BS69 restricts the function of type 2 EBNA2 as a transcriptional activator and driver of B cell growth and may contribute to reduced B-cell transformation by type 2 EBV.

[BK-virus and pathophysiology of associated diseases]. / Le virus BK et physiopathologie des maladies associées.

BK virus (BKV) is a widely distributed polyomavirus in the world population. It is the causative agent of BKV-associated nephropathy in kidney transplant recipients and hemorrhagic cystitis in bone marrow transplant patients. To date, there is no specific antiviral treatment against BKV. A better understanding of the pathophysiology of BKV-associated diseases, especially in immunocompromised patients, may contribute to the development of novel preventive and therapeutic strategies. After a detailed description of the genomic characteristics of the virus, its replication cycle and available model systems, the pathophysiological and immune mechanisms involved in BKV infection are developed and discussed in this review.

mTORC2-mediated PDHE1α nuclear translocation links EBV-LMP1 reprogrammed glucose metabolism to cancer metastasis in nasopharyngeal carcinoma.

EBV infection of preinvasive nasopharyngeal epithelium is believed to be an initiation step during pathogenesis of nasopharyngeal carcinoma (NPC), but the mechanisms remain poorly understood. Here we report a novel mechanism driving NPC metastasis through the EBV-encoded LMP1-mediated metabolic reprogramming, via activation of IGF1-mTORC2 signaling and nuclear acetylation of the Snail promoter by the PDHE1α, an enzyme involved in glucose metabolism. Mechanistically, EBV-LMP1 increases the cellular secretion of IGF1 which promotes phosphorylation of IGF1R to activate mTORC2/AKT signaling linking glucose metabolism to cell motility. LMP1 expression facilitates translocation of mitochondrial PDHE1α into the nucleus in a phosphorylation-dependent manner at Ser293 residue. Functionally, nuclear PDHE1α promotes H3K9 acetylation on the Snail promoter to enhance cell motility, thereby driving cancer metastasis. Importantly, the IGF1/mTORC2/PDHE1α/Snail axis correlates significantly with disease progression and poor prognosis in NPC patients. This study highlights the functional importance of IGF1-mTORC2-PDHE1α signaling mediated by EBV-LMP1 in NPC pathogenesis.

Hepatitis B Virus Deregulates the Cell Cycle To Promote Viral Replication and a Premalignant Phenotype.

Hepatitis B virus (HBV) infection is a major health problem worldwide, and chronically infected individuals are at high risk of developing cirrhosis and hepatocellular carcinoma (HCC). The molecular mechanisms whereby HBV causes HCC are largely unknown. Using a biologically relevant system of HBV infection of primary human hepatocytes (PHHs), we studied how HBV perturbs gene expression and signaling pathways of infected hepatocytes and whether these effects are relevant to productive HBV infection and HBV-associated HCC. Using a human growth factor antibody array, we first showed that HBV infection induced a distinct profile of growth factor production by PHHs, marked particularly by significantly lower levels of the transforming growth factor ß (TGF-ß) family of proteins in the supernatant. Transcriptome profiling next revealed multiple changes in cell proliferation and cell cycle control pathways in response to HBV infection. A human cell cycle PCR array validated deregulation of more than 20 genes associated with the cell cycle in HBV-infected PHHs. Cell cycle analysis demonstrated that HBV-infected PHHs are enriched in the G2/M phase compared to the predominantly G0/G1 phase of cultured PHHs. HBV proviral host factors, such as PPARA, RXRA, and CEBPB, were upregulated upon HBV infection and particularly enriched in cells in the G2/M phase. Together, these results support the notion that HBV deregulates cell cycle control to render a cellular environment that is favorable for productive HBV infection. By perturbing cell cycle regulation of infected cells, HBV may coincidently induce a premalignant phenotype that predisposes infected hepatocytes to subsequent malignant transformation.IMPORTANCE Hepatitis B virus (HBV) infection is a major health problem with high risk of developing hepatocellular carcinoma (HCC). By using a biologically relevant system of HBV infection of primary human hepatocytes (PHHs), we studied how HBV perturbs gene expression and whether these effects are relevant to HBV-associated HCC. HBV induced a distinct profile of growth factor production, marked particularly by significantly lower levels of the transforming growth factor ß (TGF-ß) family of proteins. Transcriptome profiling revealed multiple changes in cell proliferation and cell cycle control pathways. Cell cycle analysis demonstrated that HBV-infected PHHs are enriched in the G2/M phase. HBV proviral host factors were upregulated upon infection and particularly enriched in cells in the G2/M phase. Together, these results support the notion that HBV deregulates cell cycle control to render a cellular environment that is favorable for productive infection. This may coincidently induce a premalignant phenotype that predisposes infected hepatocytes to subsequent malignant transformation.

Genomic characterization of clonal evolution during oropharyngeal carcinogenesis driven by human papillomavirus 16.

Secondary prevention via earlier detection would afford the greatest chance for a cure in premalignant lesions. We investigated the exomic profiles of non-malignant and malignant changes in head and neck squamous cell carcinoma (HNSCC) and the genomic blueprint of human papillomavirus (HPV)-driven carcinogenesis in oropharyngeal squamous cell carcinoma (OPSCC). Whole-exome (WES) and whole-genome (WGS) sequencing were performed on peripheral blood and adjacent non-tumor and tumor specimens obtained from eight Korean HNSCC patients from 2013 to 2015. Next-generation sequencing yielded an average coverage of 94.3× for WES and 35.3× for WGS. In comparative genomic analysis of non-tumor and tumor tissue pairs, we were unable to identify common cancer-associated early mutations and copy number alterations (CNA) except in one pair. Interestingly, in this case, we observed that non-tumor tonsillar crypts adjacent to HPV-positive OPSCC appeared normal under a microscope; however, this tissue also showed weak p16 expression. WGS revealed the infection and integration of high-risk type HPV16 in this tissue as well as in the matched tumor. Furthermore, WES identified shared and tumor-specific genomic alterations for this pair. Clonal analysis enabled us to infer the process by which this transitional crypt epithelium (TrCE) evolved into a tumor; this evolution was accompanied by the subsequent accumulation of genomic alterations, including an ERBB3 mutation and large-scale CNAs, such as 3q27-qter amplification and 9p deletion. We suggest that HPV16-driven OPSCC carcinogenesis is a stepwise evolutionary process that is consistent with a multistep carcinogenesis model. Our results highlight the carcinogenic changes driven by HPV16 infection and provide a basis for the secondary prevention of OPSCC. [BMB Reports 2018; 51(11): 584-589].

Switching and loss of cellular cytokine producing capacity characterize in vivo viral infection and malignant transformation in human T- lymphotropic virus type 1 infection.

Adult T-cell leukaemia/lymphoma (ATL) arises from chronic non-malignant human T lymphotropic virus type-1 (HTLV-1) infection which is characterized by high plasma pro-inflammatory cytokines whereas ATL is characterized by high plasma anti-inflammatory (IL-10) concentrations. The poor prognosis of ATL is partly ascribed to disease-associated immune suppression. ATL cells have a CD4+CCR4+CD26-CD7- immunophenotype but infected cells with this immunophenotype ('ATL-like' cells) are also present in non-malignant HTLV-1 infection. We hypothesized that 'ATL-like' and ATL cells have distinct cytokine producing capacity and a switch in the cytokines produced occurs during leukemogenesis. Seventeen asymptomatic carriers (ACs), 28 patients with HTLV-1-associated myelopathy (HAM) and 28 with ATL were studied. Plasma IL-10 concentration and the absolute frequency of IL-10-producing CD4+ T cells were significantly higher in patients with ATL compared to AC. IL-10-producing ATL cells were significantly more frequent than 'ATL-like' cells. The cytokine-producing cells were only a small fraction of ATL cells. Clonality analysis revealed that even in patients with ATL the ATL cells were composed not only of a single dominant clone (putative ATL cells) but also tens of non-dominant infected clones ('ATL-like' cells). The frequency of cytokine-producing cells showed a strong inverse correlation with the relative abundance of the largest clone in ATL cells suggesting that the putative ATL cells were cytokine non-producing and that the 'ATL-like' cells were the primary cytokine producers. These findings were confirmed by RNAseq with cytokine mRNA expression in ATL cells in patients with ATL (confirmed to be composed of both putative ATL and 'ATL-like' cells by TCR analysis) significantly lower compared to 'ATL-like' cells in patients with non-malignant HTLV-1 infection (confirmed to be composed of hundreds of non-dominant clones by TCR analysis). A significant inverse correlation between the relative abundance of the largest clone and cytokine mRNA expression was also confirmed. Finally, 'ATL-like' cells produced less pro- and more anti-inflammatory cytokines than non 'ATL-like' CD4+ cells (which are predominantly HTLV uninfected). In summary, HTLV-1 infection of CD4+ T cells is associated with a change in cytokine producing capacity and dominant malignant clonal growth is associated with loss of cytokine producing capacity. Non-dominant clones with 'ATL-like' cells contribute to plasma cytokine profile in patients with non-malignant HTLV-1 infection and are also present in patient with ATL.

Are there multiple cells of origin of Merkel cell carcinoma?

Merkel cell carcinoma (MCC) is a rare but lethal cancer with the highest case-by-case fatality rate among all skin cancers. Eighty percent of cancers are associated with the Merkel cell polyomavirus (MCPyV). Twenty percent of MCCs are virus negative. Recent epidemiological data suggest that there are important, clinically relevant differences between these two subtypes of MCC. Recent studies in cancer genomics, mouse genetics, and virology experiments have transformed our understanding of MCC pathophysiology. Importantly, dramatic differences in the genetics of these two MCC subtypes suggest fundamental differences in their pathophysiology. We review these recent works and find that they provocatively suggest that MCPyV-positive and MCPyV-negative MCCs arise from two different cells of origin: the MCPyV-negative MCC from epidermal keratinocytes and the MCPyV-positive MCC from dermal fibroblasts. If true, this would represent the first cancer that we are aware of that evolves from cells of origin from two distinct germ layers: MCPyV-negative MCCs from ectodermal keratinocytes and MCPyV-positive MCCs from mesodermal fibroblasts. Future epigenetic experiments may prove valuable in confirming these distinct lineages for these MCC subtypes, especially for the clinical importance the cell of origin has on MCC treatment and prevention.

Association of Marek's Disease induced immunosuppression with activation of a novel regulatory T cells in chickens.

Marek's Disease Virus (MDV) is an alphaherpesvirus that infects chickens, transforms CD4+ T cells and causes deadly lymphomas. In addition, MDV induces immunosuppression early during infection by inducing cell death of the infected lymphocytes, and potentially due to activation of regulatory T (Treg)-cells. Furthermore, immunosuppression also occurs during the transformation phase of the disease; however, it is still unknown how the disease can suppress immune response prior or after lymphoma formation. Here, we demonstrated that chicken TGF-beta+ Treg cells are found in different lymphoid tissues, with the highest levels found in the gut-associated lymphoid tissue (cecal tonsil: CT), fostering an immune-privileged microenvironment exerted by TGF-beta. Surprisingly, significantly higher frequencies of TGF-beta+ Treg cells are found in the spleens of MDV-susceptible chicken lines compared to the resistant line, suggesting an association between TGF-beta+ Treg cells and host susceptibility to lymphoma formation. Experimental infection with a virulent MDV elevated the levels of TGF-beta+ Treg cells in the lungs as early as 4 days post infection, and during the transformation phase of the disease in the spleens. In contrast to TGF-beta+ Treg cells, the levels of CD4+CD25+ T cells remained unchanged during the infection and transformation phase of the disease. Furthermore, our results demonstrate that the induction of TGF-beta+ Treg cells is associated with pathogenesis of the disease, as the vaccine strain of MDV did not induce TGF-beta+ Treg cells. Similar to human haematopoietic malignant cells, MDV-induced lymphoma cells expressed high levels of TGF-beta but very low levels of TGF-beta receptor I and II genes. The results confirm that COX-2/ PGE2 pathway is involved in immunosuppression induced by MDV-lymphoma cells. Taken together, our results revealed a novel TGF-beta+ Treg subset in chickens that is activated during MDV infection and tumour formation.