Transgenic expression of a CD83-immunoglobulin fusion protein impairs the development of immune-competent CD4-positive T cells

Cytomegalovirus mediates expansion of IL-15-responsive innate-memory cells with SIV killing function

Interindividual immune variability is driven predominantly by environmental factors, including exposure to chronic infectious agents such as cytomegalovirus (CMV). We investigated the effects of rhesus CMV (RhCMV) on composition and function of the immune system in young macaques. Within months of infection, RhCMV was associated with impressive changes in antigen presenting cells, T cells, and NK cells-and marked expansion of innate-memory CD8+ T cells. These cells express high levels of NKG2A/C and the IL-2 and IL-15 receptor beta chain, CD122. IL-15 was sufficient to drive differentiation of the cells in vitro and in vivo. Expanded NKG2A/C+CD122+CD8+ T cells in RhCMV-infected macaques, but not their NKG2-negative counterparts, were endowed with cytotoxicity against class I-deficient K562 targets and prompt IFN-γ production in response to stimulation with IL-12 and IL-18. Because RhCMV clone 68-1 forms the viral backbone of RhCMV-vectored SIV vaccines, we also investigated immune changes following administration of RhCMV 68-1-vectored SIV vaccines. These vaccines led to impressive expansion of NKG2A/C+CD8+ T cells with capacity to inhibit SIV replication ex vivo. Thus, CMV infection and CMV-vectored vaccination drive expansion of functional innate-like CD8 cells via host IL-15 production, suggesting that innate-memory expansion could be achieved by other vaccine platforms expressing IL-15.

CD83, a Novel MAPK Signaling Pathway Interactor, Determines Ovarian Cancer Cell Fate

Ovarian cancer is a leading cause of death from gynecologic malignancies worldwide. Although CD83 is widely described as a solid marker for mature dendritic cells, emerging pieces of evidence indicate the expression of membrane protein CD83 by various tumor cells, including ovarian cancer cells. However, the potential role of CD83 in ovarian cancer cell properties and development remains absolutely unknown. By using human CD83 stable overexpression and knockdown sublines of several ovarian cancer cells, we observed that CD83 advanced the growth proliferation, colony formation ability, spheroid formation, and in vivo tumorigenicity of ovarian cancer cells; surprisingly, CD83 limited their migration and invasion potentials. Positive regulation of proliferation/stemness factors (e.g., cyclin-CDKs and KIT/CD44) but negative regulation of matrix metallopeptidases (e.g., MMP1 and 7) by CD83 were revealed by the integrated analysis of transcriptome and proteome. Furthermore, immunoprecipitation-mass spectrometry (IP-MS) and co-immunoprecipitation (Co-IP) first identified the association of CD83 with MAP3K7 (also known as TAK1) and MAP3K7-binding protein TAB1 on the cell membrane. Moreover, CD83 functions through the activation of MAP3K7-MEK1/2-ERK1/2 cascades to further regulate downstream FOXO1/p21/CDK2/CCNB1 and STAT3/DKK1 signaling pathways, thus activating proliferation and spheroid formation of ovarian cancer cells, respectively. Collectively, our findings define a CD83-MAPK pathway in the regulation of proliferation and stemness in ovarian cancer cells, with potential therapeutic applications in blocking their progression.

Expression of soluble CD83 in plasma from early-stage rheumatoid arthritis patients is not modified by anti-TNF-α therapy

Rheumatoid arthritis (RA) is an autoimmune disease which may lead to severe disabilities due to structural joint damage and extraarticular manifestations The dendritic cell marker CD83 belongs to the immunoglobulin superfamily and has previously been associated with autoimmune diseases. In RA the levels of soluble CD83 (sCD83) are elevated in synovial fluid, however little is known about CD83 expression and regulation in RA. Therefore, we studied how CD83 is expressed in RA and further evaluated the effect of anti-TNF-α therapy hereon. Early RA patients were randomized to conventional disease modifying anti-rheumatic drugs with or without additional anti-TNF-α therapy. Rheumatoid arthritis patients had increased levels of sCD83 in plasma compared with healthy volunteers. The increase in sCD83 plasma levels were unaffected by anti-TNF-α therapy. In chronic RA patients the levels of sCD83 were higher in synovial fluid than in plasma, and only a limited amount of membrane bound CD83 expression was detected on the surface of cells from peripheral blood and synovial fluid. Finally, confocal microscopy of RA synovial membranes revealed that CD83 was mainly localized intracellularly in a group of cells with diverse morphology including both antigen-presenting cells and non-antigen-presenting cells. Our findings demonstrate that early-stage RA patients have elevated levels of sCD83 in plasma and that anti-TNF-α treatment has no effect on the sCD83 plasma level. This suggest that in RA patients sCD83 regulation is beyond control of TNF-α.

Thymic CD4 T cell selection requires attenuation of March8-mediated MHCII turnover in cortical epithelial cells through CD83

Deficiency of CD83 in thymic epithelial cells (TECs) dramatically impairs thymic CD4 T cell selection. CD83 can exert cell-intrinsic and -extrinsic functions through discrete protein domains, but it remains unclear how CD83's capacity to operate through these alternative functional modules relates to its crucial role in TECs. In this study, using viral reconstitution of gene function in TECs, we found that CD83's transmembrane domain is necessary and sufficient for thymic CD4 T cell selection. Moreover, a ubiquitination-resistant MHCII variant restored CD4 T cell selection in Cd83(-/-) mice. Although during dendritic cell maturation CD83 is known to stabilize MHCII through opposing the ubiquitin ligase March1, regulation of March1 did not account for CD83's TEC-intrinsic role. Instead, we provide evidence that MHCII in cortical TECs (cTECs) is targeted by March8, an E3 ligase of as yet unknown physiological substrate specificity. Ablating March8 in Cd83(-/-) mice restored CD4 T cell development. Our results identify CD83-mediated MHCII stabilization through antagonism of March8 as a novel functional adaptation of cTECs for T cell selection. Furthermore, these findings suggest an intriguing division of labor between March1 and March8 in controlling inducible versus constitutive MHCII expression in hematopoietic antigen-presenting cells versus TECs.

CD83 is required for the induction of protective immunity by a DNA vaccine in a teleost model

In mammals, CD83 is a surface marker on mature dendritic cells and vital to lymphocyte activation. In teleost, studies on the function of CD83 are very limited. In this study, we examined the potential involvement of turbot (Scophthalmus maximus) CD83, SmCD83, in vaccine-induced immunity. For this purpose, turbot were immunized with pORF75, a DNA vaccine against megalocytivirus, in the presence or absence of pSmCD83, a plasmid that constitutively expresses SmCD83. Immune response and protection analysis showed that the presence of pSmCD83 significantly (i) enhanced the activation of head kidney macrophages (HKM) and immune gene expression, (ii) inhibited viral replication in fish tissues following megalocytivirus challenge and increased the survival of the vaccinated fish, and (iii) stimulated production of specific serum antibody and the cytotoxicity of peripheral blood leukocytes. To further examine the effect of SmCD83, pORF75 was administered into turbot in which SmCD83 was knocked down. Subsequent analysis showed that in fish with SmCD83 knockdown, vaccine-induced HKM activation and antibody production were severely reduced, and, consistently, the protectivity of pORF75 was drastically decreased. Taken together, these results indicate for the first time that teleost CD83 is required for the induction of protective immune response by DNA vaccine.

Glycodendropeptides stimulate dendritic cell maturation and T cell proliferation: a potential influenza A virus immunotherapy

A GDP displaying the NP_366–374 influenza A virus epitope induces an immunostimulatory effect, emerging as a potential flu vaccine.

Targeting CD83 for the treatment of graft-versus-host disease

Graft-versus-host disease (GVHD) is a common and often fatal complication of bone marrow transplantation. Antigen-presenting cells from donor and recipient play a critical role in the initiation and maintenance of GVHD. CD83, which is expressed in activated lymphocytes and dendritic cells, is regarded as a marker of mature dendritic cells. Targeting CD83 using soluble CD83 molecules or antibodies has been demonstrated to have therapeutic effects against GVHD in preclinical models. Understanding the biological function of CD83 and the underlying mechanisms through which targeting CD83 attenuates GVHD is likely to greatly improve current treatments and provide new methods for the treatment of GVHD.

Podoplanin-Fc reduces lymphatic vessel formation in vitro and in vivo and causes disseminated intravascular coagulation when transgenically expressed in the skin

Podoplanin is a small transmembrane protein required for development and function of the lymphatic vascular system. To investigate the effects of interfering with its function, we produced an Fc fusion protein of its ectodomain. We found that podoplanin-Fc inhibited several functions of cultured lymphatic endothelial cells and also specifically suppressed lymphatic vessel growth, but not blood vessel growth, in mouse embryoid bodies in vitro and in mouse corneas in vivo. Using a keratin 14 expression cassette, we created transgenic mice that overexpressed podoplanin-Fc in the skin. No obvious outward phenotype was identified in these mice, but surprisingly, podoplanin-Fc-although produced specifically in the skin-entered the blood circulation and induced disseminated intravascular coagulation, characterized by microthrombi in most organs and by thrombocytopenia, occasionally leading to fatal hemorrhage. These findings reveal an important role of podoplanin in lymphatic vessel formation and indicate the potential of podoplanin-Fc as an inhibitor of lymphangiogenesis. These results also demonstrate the ability of podoplanin to induce platelet aggregation in vivo, which likely represents a major function of lymphatic endothelium. Finally, keratin 14 podoplanin-Fc mice represent a novel genetic animal model of disseminated intravascular coagulation.

Engagement of CD83 on B cells modulates B cell function in vivo

The transmembrane glycoprotein CD83 is an important regulator of both thymic T cell maturation and peripheral T cell response. Recent studies suggested that CD83 is also involved in the regulation of B cell maturation, activation, and homeostasis. In this study, we show that in vivo overexpression of CD83 dose dependently interfered with the Ig response to thymus-dependent and thymus-independent model Ag immunization. CD83 deficiency, in contrast, which was restricted to B cells in mixed bone marrow chimeras, led to unchanged or even slightly increased Ig responses. Strikingly, the engagement of CD83 that is naturally up-regulated on wild-type B cells by injection of anti-CD83 mAb in vivo induced a 100-fold increase in the IgG1 response to immunization. Kinetic analysis revealed that CD83 had to be engaged simultaneously or shortly after the B cell activation through injection of Ag, to modulate the IgG1 secretion. Furthermore, using mixed bone marrow chimeras in which either selectively the B cells or the dendritic cells were CD83 deficient, we demonstrate that anti-CD83 mAb mediated its biologic effect by engaging CD83 on B cells and not on CD11c(+) dendritic cells. Taken together, we provide strong evidence that CD83 transduces regulatory signals into the very B cell on which it is expressed.

The CD83 reporter mouse elucidates the activity of the CD83 promoter in B, T, and dendritic cell populations in vivo

CD83 is the major surface marker identifying mature dendritic cells (DCs). In this study, we report the generation of reporter mice expressing EGFP under the control of the CD83 promoter. We have used these mice to characterize CD83 expression by various immune system cell types both in vivo and ex vivo and under steady-state conditions and in response to stimulation with a Toll-like receptor (TLR) ligand. With those mice we could prove in vivo that the CD83 promoter is highly active in all DCs and B cells in lymphoid organs. Interestingly, this promoter activity in B cells mainly depended on the stage of development, is up-regulated in the late pre-B cell stage, and was maintained on a high level in all peripheral B cells. We also confirmed that CD83 in those cells is mainly intracellular but is up-regulated after TLR stimulation. Otherwise, CD83 promoter activity in T cells seemed to depend on stimulation and could be found mainly in CD4(+)CD25(+) and CD8(+)CD25(+) T cells and in CD4(+) and CD8(+) memory cells. In addition, we identified the murine homologues of the human CD83 splice variants. In contrast to those in human, those extremely rare short transcripts were never found without the expression of the highly dominant full-length form. So, the murine CD83 surface expression is mainly regulated posttranslationally in vivo. Our CD83 reporter mice represent a useful mouse model for monitoring the activation status and migration of DCs and lymphocytes under various conditions, and our results provide much needed clarification of the true nature of CD83 promoter activity.

CD83 regulates splenic B cell maturation and peripheral B cell homeostasis

The central function of murine CD83 that is expressed on thymic epithelial cells is to induce the progression of double-positive thymocytes to single CD4-positive T cells. Several lines of evidence suggest an additional role for CD83 in the regulation of peripheral T and B cell responses. Here we show that CD83 is expressed by immature B cells and regulates their further maturation and survival in the periphery. Employing mixed bone marrow chimeras, we compare wild-type, CD83 over-expressing and CD83-deficient B cells within the same host. CD83 over-expression on the immature B cells themselves led to an accumulation of transitional B cells and a reciprocally reduced maturation of follicular B cells that was strictly correlated to the intensity of CD83 over-expression. The absence of CD83 on B cells resulted in a decreased maturation of marginal zone B cells and conferred a mild selection advantage for B cell survival in the periphery. Consenting with these findings, the over-expression of CD83 specifically and dose dependently interfered with homeostasis of B cells while T cell survival was not affected by CD83 over-expression over a period of 30 weeks. Taken together, our data suggest that CD83 negatively regulates B cell maturation and survival.

Clinical isolates of dengue virus with distinctive susceptibility to nitric oxide radical induce differential gene responses in THP-1 cells

In the present study, 10 clinical isolates of dengue virus were selected according to their susceptibility to the inhibitory effect of nitric oxide radical, NO. Five of them are nitric oxide-susceptible viruses while the other five are nitric oxide-resistant viruses. These isolates were investigated to identify genetic factors that are responsible for the different phenotypes. Due to the evidence showing that NO suppresses DENV RNA polymerase activity, we, therefore, hypothesized that the RdRp domain of NS5 may responsible for NO inhibition. To answer this question, sequences of NS5 gene of NO-susceptible viruses and NO-resistant viruses were compared. We found that these two groups of viruses contain different amino acid sequence at position 621 to 646 in the active site of NS5. These data suggested that response to the inhibitory effect of nitric oxide radical may, at least in part, be regulated by NS5. The effect of these two different phenotypes of viruses on host cells was studied using cDNA array screening. The cDNA array analysis demonstrated that the nitric oxide-resistant group had a stronger influence on host cells since it induced changes in the expression of a greater number of genes than did the nitric oxide-susceptible group, 97 genes versus 71 genes, respectively. The NO-resistant virus also stimulated cytokines known to be virulent factors, such as IL 6, IL 8, RANTES, and the inflammatory factors. In conclusion, our data demonstrated that dengue viruses isolated from patients show genotypic and phenotypic differences which may correlate with virulence.

CD83 regulates lymphocyte maturation, activation and homeostasis

The transmembrane CD83 molecule, a conserved member of the immunoglobulin superfamily, is known as one of the most characteristic cell surface markers for fully matured dendritic cells (DCs) in the peripheral circulation. An essential role for CD83 on murine DCs has not been found; however, evidence shows that its function primarily lies in the regulation of T- and B-lymphocyte maturation and in the regulation of their peripheral responses. Here, we review evidence for a role of CD83 in central lymphocyte maturation and novel, sometimes contradictory findings, regarding the function of CD83 in peripheral immune responses.

Failed efficacy of soluble human CD83-Ig in allogeneic mixed lymphocyte reactions and experimental autoimmune encephalomyelitis: implications for a lack of therapeutic potential

Soluble forms of CD83, a dendritic cell-specific surface glycoprotein, have been strongly proposed to be of therapeutic utility in inflammatory conditions such as multiple sclerosis and transplantation. We demonstrate here, however, that eukaryotically expressed, recombinant soluble human CD83-Ig molecules fail to achieve efficacy in model systems for those conditions: mouse experimental autoimmune encephalomyelitis models in vivo or in mixed lymphocyte reactions in vitro. These results raise concern as to the viability of a eukaryotically expressed soluble CD83 strategy for clinical therapeutic use.

Dendritic cell CD83: a therapeutic target or innocent bystander?

CD83 represents an intriguing target for immunotherapy due to its preferential expression on mature DCs, the most efficient of antigen presenting cells. Based on its restricted expression pattern, structure, and the paucity of CD4+ T cells in CD83-deficient mice, multiple immunologically important functions for CD83 during immune responses have been proposed. Indeed, several studies have reported that CD83 blockade using soluble receptor constructs inhibits T cell responses in vitro and in vivo, can affect autoimmune disease development and progression, and can inhibit transplant rejection. However, others have not been able to reproduce some of these findings, and antigen presenting cells deficient in CD83 expression or expressing a mutated form of CD83 induce normal T cell responses in vitro. This review examines the controversy surrounding CD83 function, alleged CD83 ligands, the potential therapeutic utility of recombinant proteins targeting CD83 function, and the importance of soluble serum CD83. While the validity of multiple previous studies needs to be confirmed, CD83 remains a fascinating cell surface molecule with a unique pattern of expression that has multiple confirmed functions in regulating immune system development and function.

CD83 gene polymorphisms increase susceptibility to human invasive cervical cancer

We previously mapped a nonrandom frequent loss of heterozygosity (LOH) region in cervical cancers to 1 Mb of 6p23. Here, we describe the identification of a novel cervical cancer susceptibility gene, CD83. The gene was identified by several complementary approaches, including a family-based association study, comparison of transcript expression in normal and cancerous tissue, and genomic sequencing of candidate. CD83 encodes an inducible glycoprotein in the immunoglobulin superfamily and is a marker for mature dendritic cells. The association study that includes 377 family trios showed that five single nucleotide polymorphisms (SNP) within 8 kb of its 3'-end showed significant allelic association that was strengthened in a subgroup of women with invasive cancers infected by high-risk human papillomavirus type 16 and 18 (rs9296925, P = 0.0193; rs853360, P = 0.0035; rs9230, P = 0.0011; rs9370729, P = 0.0012; rs750749, P = 0.0133). Investigation of CD83 uncovered three alternative transcripts in cervical tissue and cell lines, with variant 3 (lacking exons 3 and 4) being more frequent in cervical cancer than in normal cervical epithelium (P = 0.0181). Genomic sequencing on 36 paired normal and cervical tumors revealed several somatic mutations and novel SNPs in the promoter, exons, and introns of CD83. LOH was confirmed in >90% of cervical cancer specimens. Immunofluorescence colocalized CD83 protein to the Golgi apparatus and cell membrane of cervical cancer cell lines. None of seven nearby genes was differentially expressed in cervical cancer. The importance of CD83 in epithelial versus dendritic cells needs to be determined, as does its role in promoting cervical cancer.

CD83 expression is a sensitive marker of activation required for B cell and CD4+ T cell longevity in vivo

CD83 is a surface marker that differentiates immature and mature human dendritic cell populations. Thymic epithelial cell expression of CD83 is also necessary for efficient CD4+ T cell development in mice. The altered phenotypes of peripheral B and CD4+ T cells, and the reduction of peripheral CD4+ T cells in CD83-/- mice, suggest additional functions for CD83. To assess this, a panel of mAbs was generated to characterize mouse CD83 expression by peripheral leukocytes. As in humans, activation of conventional and plasmacytoid murine dendritic cell subsets led to rapid up-regulation of CD83 surface expression in mice. In primary and secondary lymphoid compartments, a subset of B cells expressed low-level CD83, while CD83 was not detected on resting T cells. However, CD83 was prominently up-regulated on the majority of spleen B and T cells within hours of activation in vitro. In vivo, a low dose of hen egg lysozyme (1 microg) induced significant CD83 but not CD69 expression by Ag-specific B cells within 4 h of Ag challenge. Although B cell development appeared normal in CD83-/- mice, B and CD4+ T cell expression of CD83 was required for lymphocyte longevity in adoptive transfer experiments. Thus, the restricted expression pattern of CD83, its rapid induction following B cell and T cell activation, and its requirement for B cell and CD4+ T cell longevity demonstrate that CD83 is a functionally significant and sensitive marker of early lymphocyte activation in vivo.

CD83 modulates B cell function in vitro: increased IL-10 and reduced Ig secretion by CD83Tg B cells

The murine transmembrane glycoprotein CD83 is an important regulator for both thymic T cell maturation and peripheral T cell responses. Recently, we reported that CD83 also has a function on B cells: Ubiquitous transgenic (Tg) expression of CD83 interfered with the immunoglobulin (Ig) response to infectious agents and to T cell dependent as well as T cell independent model antigen immunization. Here we compare the function of CD83Tg B cells that overexpress CD83 and CD83 mutant (CD83mu) B cells that display a drastically reduced CD83 expression. Correlating with CD83 expression, the basic as well as the lipopolysaccharide (LPS) induced expression of the activation markers CD86 and MHC-II are significantly increased in CD83Tg B cells and reciprocally decreased in CD83mu B cells. Wild-type B cells rapidly upregulate CD83 within three hours post BCR or TLR engagement by de novo protein synthesis. The forced premature overexpression of CD83 on the CD83Tg B cells results in reduced calcium signaling, reduced Ig secretion and a reciprocally increased IL-10 production upon in vitro activation. This altered phenotype is mediated by CD83 expressed on the B cells themselves, since it is observed in the absence of accessory cells. In line with this finding, purified CD83mu B cells displayed a reduced IL-10 production and slightly increased Ig secretion upon LPS stimulation in vitro. Taken together, our data strongly suggest that CD83 is expressed by B cells upon activation and contributes to the regulation of B cell function.

CD83 is a regulator of murine B cell function in vivo

The transmembrane glycoprotein CD83 has been described as a specific maturation marker for dendritic cells and several lines of evidence suggest that CD83 regulates thymic T cell maturation as well as peripheral T cell activation. Here we show for the first time that CD83 is involved also in the regulation of B cell function. CD83 is up-regulated on activated B cells in vivo, specifically in the draining lymph nodes of Leishmania major-infected mice. The ubiquitous transgenic (Tg) expression of CD83 interferes with Leishmania-specific T cell-dependent and with T cell-independent antibody production. This defect is restricted to the B cell population since the antigen-specific T cell response of CD83Tg mice to L. major infection is unchanged. The defective immunoglobulin (Ig) response is due to Tg expression of CD83 on the B cells because wild-type B cells display normal antigen-specific responses in CD83Tg hosts and CD83Tg B cells do not respond to immunization in a mixed wild-type/CD83Tg bone marrow chimera. Finally, the treatment of non-Tg C57BL/6 mice with anti-CD83 mAb induces a dramatic increase in the antigen-specific IgG response to immunization, thus demonstrating a regulatory role for naturally induced CD83 on wild-type B cells.