Comparative genomic analysis of the interferon/interleukin-10 receptor gene cluster.
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Interferons and interleukin-10 are involved in key aspects of the host defence mechanisms. Human chromosome 21 harbors the interferon/interleukin-10 receptor gene cluster linked to the GART gene. This cluster includes both components of the interferon alpha/beta-receptor (IFNAR1 and IFNAR2) and the second components of the interferon gamma-receptor (IFNGR2) and of the IL-10 receptor (IL10R2). We report here the complete gene content of this GART-cytokine receptor gene cluster and the use of comparative genomic analysis to identify chicken IFNAR1, IFNAR2, and IL10R2. We show that the large-scale structure of this locus is conserved in human and chicken but not in the pufferfish Fugu rubripes. This establishes that the receptor components of these host defense mechanisms were fixed in an ancestor of the amniotes. The extraordinary diversification of the interferon ligand family during the evolution of birds and mammals has therefore occurred in the context of a fixed receptor structure. (+info)
Human glioma-induced immunosuppression involves soluble factor(s) that alters monocyte cytokine profile and surface markers.
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Patients with gliomas exhibit deficient in vitro and in vivo T cell immune activity, and human glioblastoma culture supernatants (GCS) inhibit in vitro T lymphocyte responses. Because APC are essential for initiating and regulating T cell responses, we investigated whether GCS would affect cytokines produced by monocytes and T cells from healthy donors of PBMC. Incubation of PBMC with GCS decreased production of IL-12, IFN-gamma, and TNF-alpha, and increased production of IL-6 and IL-10. The GCS-induced changes in IL-12 and IL-10 occurred in monocytes, and involved changes in IL-12 p40 and IL-10 mRNA expression. Incubation with GCS also resulted in reduced expression of MHC class II and of CD80/86 costimulatory molecules on monocytes. The immunosuppressive effects were not the result of IL-6 or TGF-beta1 that was detected in GCS. However, it was due to a factor(s) that is resistant to pH extremes, differentially susceptible to temperature, susceptible to trypsin, and has a minimum molecular mass of 40 kDa. Our findings show that glioblastoma-generated factors that are known to suppress T cell responses alter the cytokine profiles of monocytic APC that, in turn, inhibit T cell function. This model indicates that monocytes can serve as an intermediate between tumor-generated immune-suppressive factors and the T cell responses that are suppressed in gliomas. (+info)
Purification of receptor complexes of interleukin-10 stoichiometry and the importance of deglycosylation in their crystallization.
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Interleukin-10 (IL-10) is a pleiotropic immunosuppressive cytokine that has a wide range of effects in controlling inflammatory responses. Viral IL-10 (vIL-10) is a homologue of human IL-10 (hIL-10) produced by Epstein-Barr virus (EBV). Both hIL-10 and vIL-10 bind to the soluble extracellular fragment of the cytokine receptor IL-10R1 (shIL-10R1). The stoichiometry of the vIL-10 : shIL-10R1 complex has been found to be the same as hIL-10 : shIL-10R1, with two vIL-10 dimers binding to four shIL-10R1 monomers. Complexes of both hIL-10 and vIL-10 with glycosylated shIL-10R1 could not be crystallized. Controlled deglycosylation using peptide : N-glycosidase F and endo-beta-N-acetylglucosaminidase F3 resulted in the formation of crystals of both hIL-10 : shIL-10R1 and vIL-10 : shIL-10R1 complexes, indicating that the difficulty in the crystal formation was largely due to the presence of complex carbohydrate side chains. The availability of the structure of the ligand-receptor complexes should facilitate our understanding of the basis of the interaction between IL-10 and the IL-10 receptor. (+info)
Interleukin-4 regulation of human monocyte and macrophage interleukin-10 and interleukin-12 production. Role of a functional interleukin-2 receptor gamma-chain.
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Interleukin-4 (IL-4) is the prototypic type 2 immunoregulatory cytokine that can suppress the production of many monocyte and macrophage pro-inflammatory mediators. In this study we investigated the regulation by IL-4 of IL-12 and IL-10 production. While IL-4 suppressed lipopolysaccharide (LPS)-induced IL-12 and IL-10 production by human peripheral blood monocytes, IL-4 suppressed LPS-induced IL-12, but not IL-10, production by synovial fluid mononuclear cells from patients with rheumatoid arthritis. IL-4 also suppressed IL-12, but not IL-10 production, by LPS-stimulated in vitro monocyte-derived macrophages. Similarly, IL-4 cannot suppress LPS-induced tumour necrosis factor-alpha (TNF-alpha) production by synovial fluid cells and monocyte-derived macrophages. The failure of IL-4 to regulate IL-10 production is not due to the failure of IL-4 to suppress TNF-alpha, and vice versa. The data suggest that the IL-4 receptor subunit, gammac, is essential for IL-4 regulation of LPS-induced IL-10 production and that a correlation exists between duration of monocyte culture, reduction in gammac mRNA in cultured cells and hyporesponsiveness of monocyte-derived macrophages to IL-4 for regulation of LPS-induced IL-10 production. This study highlights the importance of investigating responses to IL-4, as a potential therapeutic anti-inflammatory agent, by cells isolated from inflammatory sites and not by the more easily accessible blood monocytes. This study emphasizes the involvement of signalling from gammac in IL-4 regulation of LPS-induced IL-10 production by monocytes and macrophages. (+info)
Interleukin-10 receptor signaling through the JAK-STAT pathway. Requirement for two distinct receptor-derived signals for anti-inflammatory action.
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Interleukin-10 (IL-10) is a cytokine that has pleiotropic effects on a variety of different cell types. Although many of the biologic responses induced by IL-10 are also induced by other cytokines, such as IL-6, IL-10 is relatively unique in its ability to potently inhibit production of pro-inflammatory cytokines in macrophages. In this study, we have used gain-of-function and loss-of-function genetic approaches to define the intracellular components involved in the different biologic actions of IL-10. Herein, we demonstrate that the ability of IL-10 to inhibit tumor necrosis factor alpha (TNFalpha) production in lipopolysaccharide-stimulated macrophages requires the presence of Stat3, Jak1, and two distinct regions of the IL-10 receptor intracellular domain. Macrophages deficient in Stat3 or Jak1 were unable to inhibit lipopolysaccharide-induced TNFalpha production following treatment with murine IL-10. Structure-function analysis of the intracellular domain of the IL-10 receptor alpha chain showed that whereas two redundant Stat3 recruitment sites (427YQKQ430 and 477YLKQ480) were required for all IL-10-dependent effects on either B cells or macrophages, expression of IL-10-dependent anti-inflammatory function required the presence on the intracellular domain of the IL-10 receptor of a carboxyl-terminal sequence containing at least one functionally critical serine. These results thus demonstrate that IL-10-induced inhibition of TNFalpha production requires two distinct regions of the IL-10 receptor intracellular domain and thereby establish a distinctive molecular basis for the developmental versus the anti-inflammatory actions of IL-10. (+info)
Involvement of interleukin-10 (IL-10) and viral IL-6 in the spontaneous growth of Kaposi's sarcoma herpesvirus-associated infected primary effusion lymphoma cells.
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Primary effusion lymphoma (PEL) is a distinct type of lymphoma associated with Kaposi's sarcoma-associated herpesvirus (KSHV) infection. To determine the factors responsible for the unrestrained proliferation of PEL, we have studied the growth factor requirements of the PEL-derived BCBL-1 and BC-1 cell lines. Both cell lines were found to be autocrine growth factor dependent and to release human interleukin-6 (IL-6), viral IL-6 (vIL-6), and human IL-10 in the culture supernatant. To establish whether these cytokines contribute to autocrine growth, neutralizing antibodies against human IL-6, vIL-6, human IL-10, and soluble IL-10 receptor were used. These experiments showed that human IL-10 and, to a lesser degree, vIL-6 serve as autocrine growth factors for BCBL-1 and BC-1 cells. Thus, human IL-10 and vIL-6 are growth factors released and used by PEL cells for autonomous proliferation and may be critical to the development and progression of PEL. (+info)
Interaction of Mycobacterium tuberculosis-induced transforming growth factor beta1 and interleukin-10.
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Mycobacterium tuberculosis is associated with the activation of cytokine circuits both at sites of active tuberculosis in vivo and in cultures of mononuclear cells stimulated by M. tuberculosis or its components in vitro. Interactive stimulatory and/or inhibitory pathways are established between cytokines, which may result in potentiation or attenuation of the effects of each molecule on T-cell responses. Here we examined the interaction of transforming growth factor beta1 (TGF-beta1) and interleukin-10 (IL-10) in purified protein derivative (PPD)-stimulated human mononuclear cell cultures in vitro. TGF-beta1 induced monocyte IL-10 (but not tumor necrosis factor alpha) production (by 70-fold, P < 0.02) and mRNA expression in the absence but not in the presence of PPD. Both exogenous recombinant (r) IL-10 and rTGF-beta1 independently suppressed the production of PPD-induced gamma interferon (IFN-gamma) in mononuclear cells from PPD skin test-positive individuals. Synergistic suppression of IFN-gamma in cultures containing both rTGF-beta1 and rIL-10 was only seen when the responder cell population were peripheral blood mononuclear cells (PBMC) and not monocyte-depleted mononuclear cells and when PBMC were pretreated with rTGF-beta1 but not with rIL-10. Suppression of PPD-induced IFN-gamma in PBMC containing both rTGF-beta1 (1 ng/ml) and rIL-10 (100 pg/ml) was 1.5-fold higher (P < 0.05) than cultures containing TGF-beta1 alone and 5.7-fold higher (P < 0.004) than cultures containing IL-10 alone. Also, neutralization of endogenous TGF-beta1 and IL-10 together enhanced PPD-induced IFN-gamma in PBMC in a synergistic manner. Thus, TGF-beta1 and IL-10 together potentiate the downmodulatory effect on M. tuberculosis-induced T-cell production of IFN-gamma, and TGF-beta1 alone enhances IL-10 production. At sites of active M. tuberculosis infection, these interactions may be conducive to the suppression of mononuclear cell functions. (+info)
Interleukin-10 receptors are expressed by basement membrane anchored, alpha(6) integrin(+) cytotrophoblast cells in early human placenta.
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Cytotrophoblast cells produce interleukin (IL)-10 and express IL-10 receptor mRNA in culture. Furthermore, IL-10 dramatically reduces the synthesis of matrix metalloproteinase (MMP)-9 and the invasivity of cytotrophoblast cells in vitro, suggesting that an autocrine regulatory role in vivo is also possible. To test this hypothesis we investigated the expression of IL-10 receptor protein by first trimester cytotrophoblasts both in vitro and in situ, using flow cytometry and immunohistochemistry. Flow cytometric analyses demonstrated that 75-80% of cytotrophoblasts are able to bind labelled IL-10, suggesting that these cells possess IL-10 receptors in vitro. Serial sections of early human placentae stained for either alpha(5) and alpha(6) integrin subunits, or for IL-10 receptors respectively, revealed that placental cytotrophoblasts possess cell surface IL-10 receptors not only in vitro, but also in vivo. IL-10 receptors were present mainly on alpha(6) integrin expressing villous cytotrophoblast cells and on alpha(6)-positive cells of invasive cell columns located nearest the villous stroma. Differentiated trophoblasts (i.e. alpha(5)-positive cells and villous syncytiotrophoblasts) showed no reactivity. This differential expression of IL-10 receptors suggests that IL-10 might suppress the invasivity of undifferentiated cytotrophoblast cells, in vivo, preserving their non-invasive state in an autocrine manner. The possible involvement in cytotrophoblast proliferation and/or differentiation is also discussed. (+info)