The role of the microenvironment on the regulation of Epstein-Barr virus latent gene expression
Author: Kis, Loránd Levente
Date: 2009-06-05
Location: MTC, Föreläsningssalen, Theorells väg 1
Time: 13.00
Department: Institutionen för mikrobiologi, tumör- och cellbiologi / Department of Microbiology, Tumor and Cell Biology
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Thesis (1.185Mb)
Abstract
Epstein-Barr virus (EBV) is a human-specific gamma-herpes virus of the Lymphocryptovirus genus that has succeeded to colonize more than 90% of the adult population. EBV s coevolution with humans has established a largely harmless co-existence that depends on the variability of viral gene expression and on the immunological host response. Though infection with EBV is generally harmless, the virus is associated with multiple human tumors, such as Burkitt lymphoma, classical Hodgkin lymphoma, nasopharyngeal carcinoma, post-transplant lymphoproliferative disorders, and AIDS lymphomas. The role of EBV in the malignant transformation is still enigmatic even after more than 40 years of research on this virus.
EBV readily infects B-lymphocytes in vitro. After infection the virus establishes a latent infection and expresses 9 viral proteins. The concerted effect of these EBV proteins will be the activation and proliferation of the infected B cells. This viral gene expression pattern was named type III latency. As the EBV-infected B cells with type III latency are highly immunogenic they are readily detected and killed by the specific cytotoxic T cells. In contrast to the EBV-infected normal B cells, the majority of the EBV-carrying tumors do not express all the nine proteins; rather they express only EBNA-1 or EBNA-1 together with the latent membrane proteins (LMP-1 and LMP-2). The factors that determine what viral genes EBV will express in the different normal and malignant cells are only partially known.
Motivated by the lack of in vitro models in which to study the interaction of EBV with the malignant Hodgkin/Reed-Sternberg (HRS) cells, we infected with EBV one of the Hodgkin lymphoma-derived cell lines and studied the viral gene expression in this EBV-converted subline. In this system we identified two cytokines, IL-4 and IL-13, that could modulate the viral gene expression (specifically, induce the expression of LMP-1) and with their help we could for the first time reconstitute in vitro the EBV gene expression seen in the classical Hodgkin lymphomas in vivo. We have also studied the molecular mechanisms that are responsible for the induction of LMP-1 by IL-4 and IL-13. Through these studies we identified STAT6 as an important inducer of LMP-1 expression. As STAT6 is constitutively activated in the majority of Hodgkin lymphomas, our results not only provides an explanation how LMP-1 is expressed in the EBV-carrying HRS cells, but might also have future therapeutic implications.
Further work identified two additional cytokines, IL-10 and IL-21, which could induce the expression of LMP-1 in EBV-positive B cell and NK cell lymphoma-derived cell lines. The effect of IL-21 was pleiotropic: it could induce LMP-1 in cells that did not express it, and it induced the plasma cell differentiation and down-regulation of expression of the EBV nuclear antigens (EBNA-1 to -6) in type III lymphoblastoid and Burkitt lymphoma cell lines. Furthermore, when isolated human CD4+ T cells were co-cultured with different EBVcarrying lymphoma cell lines, we found that upon activation they were capable of inducing the expression of LMP-1, just as the recombinant cytokines did. Altogether our results provide evidence for an important role for the cytokines secreted by CD4+ T or other inflammatory cells in the modulation of EBV latent gene expression.
EBV readily infects B-lymphocytes in vitro. After infection the virus establishes a latent infection and expresses 9 viral proteins. The concerted effect of these EBV proteins will be the activation and proliferation of the infected B cells. This viral gene expression pattern was named type III latency. As the EBV-infected B cells with type III latency are highly immunogenic they are readily detected and killed by the specific cytotoxic T cells. In contrast to the EBV-infected normal B cells, the majority of the EBV-carrying tumors do not express all the nine proteins; rather they express only EBNA-1 or EBNA-1 together with the latent membrane proteins (LMP-1 and LMP-2). The factors that determine what viral genes EBV will express in the different normal and malignant cells are only partially known.
Motivated by the lack of in vitro models in which to study the interaction of EBV with the malignant Hodgkin/Reed-Sternberg (HRS) cells, we infected with EBV one of the Hodgkin lymphoma-derived cell lines and studied the viral gene expression in this EBV-converted subline. In this system we identified two cytokines, IL-4 and IL-13, that could modulate the viral gene expression (specifically, induce the expression of LMP-1) and with their help we could for the first time reconstitute in vitro the EBV gene expression seen in the classical Hodgkin lymphomas in vivo. We have also studied the molecular mechanisms that are responsible for the induction of LMP-1 by IL-4 and IL-13. Through these studies we identified STAT6 as an important inducer of LMP-1 expression. As STAT6 is constitutively activated in the majority of Hodgkin lymphomas, our results not only provides an explanation how LMP-1 is expressed in the EBV-carrying HRS cells, but might also have future therapeutic implications.
Further work identified two additional cytokines, IL-10 and IL-21, which could induce the expression of LMP-1 in EBV-positive B cell and NK cell lymphoma-derived cell lines. The effect of IL-21 was pleiotropic: it could induce LMP-1 in cells that did not express it, and it induced the plasma cell differentiation and down-regulation of expression of the EBV nuclear antigens (EBNA-1 to -6) in type III lymphoblastoid and Burkitt lymphoma cell lines. Furthermore, when isolated human CD4+ T cells were co-cultured with different EBVcarrying lymphoma cell lines, we found that upon activation they were capable of inducing the expression of LMP-1, just as the recombinant cytokines did. Altogether our results provide evidence for an important role for the cytokines secreted by CD4+ T or other inflammatory cells in the modulation of EBV latent gene expression.
List of papers:
I. Kis LL, Nagy N, Klein G, Klein E (2003). Expression of SH2D1A in five classical Hodgkins disease-derived cell lines. Int J Cancer. 104(5): 658-61
Pubmed
II. Nishikawa J, Kis LL, Liu A, Zhang X, Takahara M, Bandobashi K, Kiss C, Nagy N, Okita K, Klein G, Klein E (2004). Upregulation of LMP1 expression by histone deacetylase inhibitors in an EBV carrying NPC cell line. Virus Genes. 28(1): 121-8
Pubmed
III. Kis LL, Nishikawa J, Takahara M, Nagy N, Matskova L, Takada K, Elmberger PG, Ohlsson A, Klein G, Klein E (2005). In vitro EBV-infected subline of KMH2, derived from Hodgkin lymphoma, expresses only EBNA-1, while CD40 ligand and IL-4 induce LMP-1 but not EBNA-2. Int J Cancer. 113(6): 937-45
Pubmed
IV. Kis LL, Takahara M, Nagy N, Klein G, Klein E (2006). IL-10 can induce the expression of EBV-encoded latent membrane protein-1 (LMP-1) in the absence of EBNA-2 in B lymphocytes and in Burkitt lymphoma- and NK lymphoma-derived cell lines. Blood. 107(7): 2928-35. Epub 2005 Dec 6
Pubmed
V. Takahara M, Kis LL, Nagy N, Liu A, Harabuchi Y, Klein G, Klein E (2006). Concomitant increase of LMP1 and CD25 (IL-2-receptor alpha) expression induced by IL-10 in the EBV-positive NK lines SNK6 and KAI3. Int J Cancer. 119(12): 2775-83
Pubmed
VI. Kis LL, Salamon D, Persson EK, Nagy N, Scheeren FA, Spits H, Klein G, Klein E (2009). IL-21 imposes a type II EBV gene expression on both type III and type I B cells by the repression of the C-promoter and activation of the LMP-1 promoter. [Manuscript]
VII. Kis LL, Gerasimèik N, Salamon D, Persson EK, Nagy N, Klein G, Severinson E, Klein E (2009). A new STAT6 signaling pathway activated by the cytokines IL-4 and IL-13 induces the expression of the EBV-encoded protein LMP-1 in absence of EBNA-2: implications for the type II EBV latent gene expression in Hodgkin lymphoma. [Manuscript]
I. Kis LL, Nagy N, Klein G, Klein E (2003). Expression of SH2D1A in five classical Hodgkins disease-derived cell lines. Int J Cancer. 104(5): 658-61
Pubmed
II. Nishikawa J, Kis LL, Liu A, Zhang X, Takahara M, Bandobashi K, Kiss C, Nagy N, Okita K, Klein G, Klein E (2004). Upregulation of LMP1 expression by histone deacetylase inhibitors in an EBV carrying NPC cell line. Virus Genes. 28(1): 121-8
Pubmed
III. Kis LL, Nishikawa J, Takahara M, Nagy N, Matskova L, Takada K, Elmberger PG, Ohlsson A, Klein G, Klein E (2005). In vitro EBV-infected subline of KMH2, derived from Hodgkin lymphoma, expresses only EBNA-1, while CD40 ligand and IL-4 induce LMP-1 but not EBNA-2. Int J Cancer. 113(6): 937-45
Pubmed
IV. Kis LL, Takahara M, Nagy N, Klein G, Klein E (2006). IL-10 can induce the expression of EBV-encoded latent membrane protein-1 (LMP-1) in the absence of EBNA-2 in B lymphocytes and in Burkitt lymphoma- and NK lymphoma-derived cell lines. Blood. 107(7): 2928-35. Epub 2005 Dec 6
Pubmed
V. Takahara M, Kis LL, Nagy N, Liu A, Harabuchi Y, Klein G, Klein E (2006). Concomitant increase of LMP1 and CD25 (IL-2-receptor alpha) expression induced by IL-10 in the EBV-positive NK lines SNK6 and KAI3. Int J Cancer. 119(12): 2775-83
Pubmed
VI. Kis LL, Salamon D, Persson EK, Nagy N, Scheeren FA, Spits H, Klein G, Klein E (2009). IL-21 imposes a type II EBV gene expression on both type III and type I B cells by the repression of the C-promoter and activation of the LMP-1 promoter. [Manuscript]
VII. Kis LL, Gerasimèik N, Salamon D, Persson EK, Nagy N, Klein G, Severinson E, Klein E (2009). A new STAT6 signaling pathway activated by the cytokines IL-4 and IL-13 induces the expression of the EBV-encoded protein LMP-1 in absence of EBNA-2: implications for the type II EBV latent gene expression in Hodgkin lymphoma. [Manuscript]
Issue date: 2009-05-15
Rights:
Publication year: 2009
ISBN: 978-91-7409-531-9
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