Identification and functional characterization of a second chain of the interleukin-10 receptor complex

CD82 regulates STAT5/IL-10 and supports survival of acute myelogenous leukemia cells

We recently reported that adhesion molecule CD82 is aberrantly expressed in CD34(+) /CD38(-) leukemia stem cells (LSCs). Here, we report the results of a functional analysis of CD82 in CD34(+) /CD38(-) acute myelogenous leukemia (AML) cells. Short hairpin (sh)RNA-mediated downregulation of CD82 resulted in a decrease in the level of IL-10. In contrast, forced expression of CD82 in CD34(+)/CD38(+) AML cells by transduction with CD82-expressing lentiviral particles resulted in an increase in the levels of IL-10. Notably, exposure of CD34(+)/CD38(-) AML cells to IL-10 stimulated clonogenic growth of these cells. Moreover, downregulation of CD82 by a shRNA dephosphorylated STAT5 in CD34(+)/CD38(-) AML cells. On the other hand, forced expression of CD82 resulted in increase in the levels of p-STAT5 in CD34(+)/CD38(+) AML cells. Chromatin immunoprecipitation (ChIP) assay results indicated that STAT5A binds to the promoter region of the IL-10 gene, while reporter gene assay results indicated stimulation of IL-10 expression at the transcriptional level. These results suggest that CD82 positively regulates the STAT5/IL-10 signaling pathway. Moreover, shRNA-mediated downregulation of CD82 expression in CD34(+)/CD38(-) AML cells dephosphorylated STAT5 in immunodeficient mice. Taken together, our data suggest that the CD82/STAT5/IL-10 signaling pathway is involved in the survival of CD34(+)/CD38(-) AML cells and may thus be a promising therapeutic target for eradication of AML LSCs.

Pegylated IL-10 induces cancer immunity: the surprising role of IL-10 as a potent inducer of IFN-γ-mediated CD8(+) T cell cytotoxicity

Recently, the development of several strategies based on immunotherapy has raised hopes for a more promising way to treat cancer patients. Here, we describe how interleukin (IL)-10, a seemingly unlikely candidate, stimulates the immune system in a particularly efficacious way. IL-10, an omnipotent anti-inflammatory cytokine, delivers an equally potent immune stimulation in the context of CD8(+) T cells and tumor immunity. By activation of tumor-resident, tumor-specific CD8(+) T cells, pegylated IL-10 can induce rejection of large and metastasizing tumors in mice. Here, we summarize the mechanisms of action of IL-10, the reasons why the mechanisms may be crucial for the treatment of cancer patients, and the rationale for applying pegylated IL-10 in the clinic.

Interleukin-10 down-regulates voltage gated sodium channels in rat dorsal root ganglion neurons

The over-expression of voltage-gated sodium channels (VGSCs) in dorsal root ganglion (DRG) neurons following peripheral nerve injury contributes to neuropathic pain by generation of the ectopic discharges of action potentials. However, mechanisms underlying the change in VGSCs' expression are poorly understood. Our previous work has demonstrated that the pro-inflammatory cytokine TNF-α up-regulates VGSCs. In the present work we tested if anti-inflammatory cytokine IL-10, which had been proven to be effective for treating neuropathic pain, had the opposite effect. Western blot and immunofluorescence results showed that IL-10 receptor was localized in DRG neurons. Recombinant rat IL-10 (200 pg/ml) not only reduced the densities of TTX-sensitive and Nav1.8 currents in control DRG neurons, but also reversed the increase of the sodium currents induced by rat recombinant TNF-α (100 pg/ml), as revealed by patch-clamp recordings. Consistent with the electrophysiological results, real-time PCR and western blot revealed that IL-10 (200 pg/ml) down-regulated VGSCs in both mRNA and protein levels and reversed the up-regulation of VGSCs by TNF-α. Moreover, repetitive intrathecal administration of rrIL-10 for 3 days (4 times per day) attenuated mechanical allodynia in L5 spinal nerve ligation model and profoundly inhibited the excitability of DRG neurons. These results suggested that the down-regulation of the sodium channels in DRG neurons might contribute to the therapeutic effect of IL-10 on neuropathic pain.

The Pekin duck IL-10R2 common chain: cDNA cloning, genomic structure, molecular characterization and mRNA expression analysis

The interleukin-10 receptor 2 (IL-10R2, IL-10Rβ) is required for the signalling of the class 2 cytokines IL-10, IL-22, IL-26 and IFN-λ1-3 . Here, we describe the identification of the Pekin duck IL-10R2 (duIL-10R2) common chain and its gene structure. The duIL-10R2 cDNA encodes a 343 amino acid protein that has an amino acid identity of 76% and 42% with chicken and human IL-10R2, respectively. Binding residues of human IL-10R2 for IL-10 and IL-22 were mostly conserved in the avian IL-10R2 proteins within loops L3 and L5, but not within loops L2 and L6. Homology modelling of the duIL-10R2 extracellular domain structure using soluble human IL-10R2 (shIL-10R2, PDB ID: 3LQM) as a template revealed a protruding loop L5 and two distinct clefts between loops L2/L3 and L3/L5, similar to shIL-10R2. However, in contrast to the three amino acid β-hairpin loop L2 of shIL-10R2, loop L2 of duIL-10R2 is five residues longer. Residues within a putative Tyk2 binding site were highly conserved across all vertebrate IL-10R2 proteins examined. The duIL-10R2 gene shares a seven exon-six intron structure with chicken and human IL-10R2 genes, but avian genes are more compact. DuIL-10R2 mRNA was constitutively expressed in all tissues. Mitogen stimulation of duck peripheral blood mononuclear cells (PBMC) did not alter transcript levels. Our observations suggest that genomic organization and structural features implicated in multiple cytokine-binding properties of human IL-10R2 are conserved in duck IL-10R2, but the evolutionary changes that appear to have lead to low-affinity cytokine interaction within loop L2 are distinct to mammalian species.

[Population genetics and human immunity: the interferon paradigm]

The evolutionary genetics dissection of immunity-related genes provides insights into immunological defence mechanisms and highlight host pathways playing an important role in pathogen resistance. Recent population genetic data have increased knowledge of the biological relevance of human interferons (IFN), cytokines released by host cells in response to pathogen presence or tumour cells. Some IFN-α subtypes as well as IFN-γ are strongly evolutionarily constrained, suggesting that the functions they fulfil are essential and non redundant. Other IFN, the most extreme cases being IFN-α10 and IFN-ε, can accumulate missense or nonsense mutations at high population frequencies, suggesting higher redundancy. Furthermore, genetic variation at some IFN genes can be advantageous for the host and increase in frequency by positive selection. This has been shown for type III IFN, where mutations at IL28A, IL28B and IL29 have been positively selected in Europeans and Asians, most likely by increasing resistance to viral infection. This review uses the IFN paradigm to illustrate the value of the evolutionary approach in highlighting important determinants of host immune responsiveness in the natural setting.

Lactobacillus rhamnosus (LGG) regulates IL-10 signaling in the developing murine colon through upregulation of the IL-10R2 receptor subunit

The intestinal microflora is critical for normal development, with aberrant colonization increasing the risk for necrotizing enterocolitis (NEC). In contrast, probiotic bacteria have been shown to decrease its incidence. Multiple pro- and anti-inflammatory cytokines have been identified as markers of intestinal inflammation, both in human patients with NEC and in models of immature intestine. Specifically, IL-10 signaling attenuates intestinal responses to gut dysbiosis, and disruption of this pathway exacerbates inflammation in murine models of NEC. However, the effects of probiotics on IL-10 and its signaling pathway, remain poorly defined. Real-time PCR profiling revealed developmental regulation of MIP-2, TNF-α, IL-12, IL-10 and the IL-10R2 subunit of the IL-10 receptor in immature murine colon, while the expression of IL-6 and IL-18 was independent of postnatal age. Enteral administration of the probiotic Lactobacillus rhamnosus GG (LGG) down-regulated the expression of TNF-α and MIP-2 and yet failed to alter IL-10 mRNA and protein expression. LGG did however induce mRNA expression of the IL-10R2 subunit of the IL-10 receptor. IL-10 receptor activation has been associated with signal transducer and activator of transcription (STAT) 3-dependent induction of members of the suppressors of cytokine signaling (SOCS) family. In 2 week-old mice, LGG also induced STAT3 phosphorylation, increased colonic expression of SOCS-3, and attenuated colonic production of MIP-2 and TNF-α. These LGG-dependent changes in phosphoSTAT3, SOCS3, MIP-2 and TNF-α were all inhibited by antibody-mediated blockade of the IL-10 receptor. Thus LGG decreased baseline proinflammatory cytokine expression in the developing colon through upregulation of IL-10 receptor-mediated signaling, most likely due to the combined induction of phospho-STAT3 and SOCS3. Furthermore, LGG-dependent increases in IL-10R2 were associated with reductions in TNF-α, MIP-2 and disease severity in a murine model of intestinal injury in the immature colon.

Genetic polymorphisms in IL10RA and TNF modify the association between blood transfusion and risk of non-Hodgkin lymphoma

We conducted a population-based case-control study in Connecticut women to test the hypothesis that genetic variations in Th1 and Th2 cytokine genes may modify the association between blood transfusion and risk of non-Hodgkin lymphoma (NHL). Compared with women without blood transfusion, women with a history of transfusion had an increased risk of NHL if they carried IL10RA (rs9610) GG genotype [odds ratio (OR) = 1.9, 95% confidence interval (CI): 1.1-3.2] or TNF (rs1800629) AG/AA genotypes (OR = 1.6, 95% CI: 0.9-2.7). We also found women with a history of transfusion had a decreased risk of NHL if they carried IL10RA (rs9610) AG/AA genotypes (OR = 0.6, 95% CI: 0.4-0.9) or TNF (rs1800629) GG genotype (OR = 0.7, 95% CI: 0.5-1.0). A similar pattern was also observed for B-cell lymphoma but not for T-cell lymphoma. Statistically significant interactions with blood transfusion were observed for IL10RA (rs9610) (P(forinteraction) = 0.003) and TNF (rs1800629) (P(forinteraction) = 0.012) for NHL overall and IL10RA (rs9610) (P(forinteraction) = 0.001) and TNF (rs1800629) (P(forinteraction) = 0.019) for B-cell lymphoma. The results suggest that genetic polymorphisms in TNF and IL10RA genes may modify the association between blood transfusion and NHL risk.

Epstein-Barr virus IL-10 engages IL-10R1 by a two-step mechanism leading to altered signaling properties

Human interleukin-10 (hIL-10) is a pleiotropic cytokine that is able to suppress or activate cellular immune responses to protect the host from invading pathogens. Epstein-Barr virus (EBV) encodes a viral IL-10 (ebvIL-10) in its genome that has retained the immunosuppressive activities of hIL-10 but lost the ability to induce immunostimulatory activities on some cells. These functional differences are at least partially due to the ∼1000-fold difference in hIL-10 and ebvIL-10 binding affinity for the IL-10R1·IL-10R2 cell surface receptors. Despite weaker binding to IL-10R1, ebvIL-10 is more active than hIL-10 in inducing B-cell proliferation. To explore this counterintuitive observation further, a series of monomeric and dimeric ebvIL-10·hIL-10 chimeric proteins were produced and characterized for receptor binding and cellular proliferation on TF-1/hIL-10R1 cells that express high levels of the IL-10R1 chain. On this cell line, monomeric chimeras elicited cell proliferation in accordance with how tightly they bound to the IL-10R1 chain. In contrast, dimeric chimeras exhibiting the highest affinity for IL-10R1 exhibited reduced proliferative activity. These distinct activity profiles are correlated with kinetic analyses that reveal that the ebvIL-10 dimer is impaired in its ability to form a 1:2 ebvIL-10·IL-10R1 complex. As a result, the ebvIL-10 dimer functions like a monomer at low IL-10R1 levels, which prevents efficient signaling. At high IL-10R1 levels, the ebvIL-10 dimer is able to induce signaling responses greater than hIL-10. Thus, the ebvIL-10 dimer scaffold is essential to prevent activation of cells with low IL-10R1 levels but to maintain or enhance activity on cells with high IL-10R1 levels.

Cot/tpl2-MKK1/2-Erk1/2 controls mTORC1-mediated mRNA translation in Toll-like receptor-activated macrophages

Macrophages require rapid fine control of translation to provide an accurate and not self-damaging response to host infection. Cot/tpl2-MKK1/2-Erk1/2 controls 5´TOP and inflammatory mediator–gene encoding mRNA translation in TLR-activated macrophages.

Cot/tpl2 is the only MAP3K that activates MKK1/2-Erk1/2 in Toll-like receptor–activated macrophages. Here we show that Cot/tpl2 regulates RSK, S6 ribosomal protein, and 4E-BP phosphorylation after stimulation of bone marrow–derived macrophages with lipopolysaccharide (LPS), poly I:C, or zymosan. The dissociation of the 4E-BP–eIF4E complex, a key event in the cap-dependent mRNA translation initiation, is dramatically reduced in LPS-stimulated Cot/tpl2-knockout (KO) macrophages versus LPS-stimulated wild-type (Wt) macrophages. Accordingly, after LPS activation, increased cap-dependent translation is observed in Wt macrophages but not in Cot/tpl2 KO macrophages. In agreement with these data, Cot/tpl2 increases the polysomal recruitment of the 5´ TOP eEF1α and eEF2 mRNAs, as well as of inflammatory mediator gene–encoding mRNAs, such as tumor necrosis factor α (TNFα), interleukin-6 (IL-6), and KC in LPS-stimulated macrophages. In addition, Cot/tpl2 deficiency also reduces total TNFα, IL-6, and KC mRNA expression in LPS-stimulated macrophages, which is concomitant with a decrease in their mRNA half-lives. Macrophages require rapid fine control of translation to provide an accurate and not self-damaging response to host infection, and our data show that Cot/tpl2 controls inflammatory mediator gene–encoding mRNA translation in Toll-like receptor–activated macrophages.

Spinal interleukin-10 therapy to treat peripheral neuropathic pain

INTRODUCTION

  Current research indicates that chronic peripheral neuropathic pain includes a role for glia and the actions of proinflammatory factors. This review briefly discusses the glial and cytokine responses that occur following peripheral nerve damage in support of utilizing anti-inflammatory cytokine interleukin-10 (IL-10) therapy to suppress chronic peripheral neuropathic pain. SPINAL NONVIRAL INTERLEUKIN-10 GENE THERAPY:  IL-10 is one of the most powerful endogenous counter-regulators of proinflammatory cytokine function that acts in the nervous system. Subarachnoid (intrathecal) spinal injection of the gene encoding IL-10 delivered by nonviral vectors has several advantages over virally mediated gene transfer methods and leads to profound pain relief in several animal models. NONVIRAL GENE DELIVERY:  Lastly, data are reviewed that nonviral deoxyribonucleic acid (DNA) encapsulated by a biologically safe copolymer, poly(lactic-co-glycolic) acid (PLGA), thought to protect DNA, leads to significantly improved therapeutic gene transfer in animal models, which additionally and significantly extends pain relief.

CONCLUSIONS

  The impact of these early studies exploring anti-inflammatory genes emphasizes the exceptional therapeutic potential of new biocompatible intrathecal nonviral gene delivery approaches such as PLGA microparticles. Ultimately, ongoing expression of therapeutic genes is a viable option to treat chronic neuropathic pain in the clinic.

Identification and molecular characterization of the interleukin-10 receptor 1 of the zebrafish (Danio rerio) and the goldfish (Carassius auratus L.)

This is the first report of the identification and molecular characterization of an interleukin-10 receptor 1 in bony fish. By gene synteny analysis, we identified the zebrafish interleukin-10 receptor 1 (IL10R1) and using this IL10R1 sequence, we cloned the goldfish IL10R1 cDNA transcript. The identified fish IL10R1 protein sequences had a putative JAK1 binding site, only one of the two STAT3 binding sites, that are present in all other vertebrates IL10R1 proteins as well as C-terminal serine rich areas, believed to be responsible for the anti-inflammatory properties of IL10R1. Phylogenetically, the fish IL10R1 proteins grouped independently of the amphibian, avian and mammalian IL10R1s. Quantitative gene expression analysis of the IL10R1 of zebrafish and goldfish revealed highest mRNA levels in the spleen tissues. High mRNA levels were also observed in the zebrafish muscle in contrast to low mRNA levels in the muscle of the goldfish. Moderate IL10R1 mRNA levels were seen in most other tissues examined and lowest gene expression was in the liver of both fish species. Goldfish monocytes stimulated with a recombinant goldfish interleukin-10 (rgIL-10) or with heat killed fish pathogens, Aeromonas salmonicida or Trypanosoma carassii, exhibited significantly reduced mRNA levels of the IL10R1. Furthermore, we produced a recombinant form of the goldfish IL10R1 (rgIL10R1) and using in vitro binding studies, demonstrated that the dimerized rgIL-10 specifically interacted with rgIL10R1. Our results suggest that interleukin-10 system has been highly conserved throughout evolution.

Inflammatory bowel disease: is it a primary immunodeficiency?

Inflammatory bowel diseases (IBD) such as ulcerative colitis and Crohn's disease are chronic and relapsing conditions, characterized by abdominal pain, diarrhea, bleeding and malabsorption. IBD has been considered a hyperinflammatory state due to disturbed interactions between the immune system and the commensal bacterial flora of the gut. However, there is evidence that Crohn's disease might be the consequence of a reduced release of pro-inflammatory cytokines and an impaired acute inflammatory response, thereby suggesting that IBD might be an immunodeficiency rather than an excessive inflammatory reaction. This theory has been supported by observations in patients with primary immunodeficiencies such as the Wiskott-Aldrich syndrome and IPEX (immunodysregulation, polyendocrinopathy, enteropathy, X-linked syndrome). In contrary, defects in the anti-inflammatory down-regulation of the immune response as they are seen in patients with Mendelian defects in the IL10 signaling pathway support the hyper-inflammatory theory. In this review, we describe and discuss primary immunodeficiencies associated with IBD and show that the bowel is a highly sensitive indicator of dysregulations, making IBD a model disease to study and identify key regulators required to balance the human mucosal immune system.

Evolutionary genetic dissection of human interferons

As revealed by population genetic analyses, different human interferon genes evolved under distinct selective constraints and signatures of positive selection vary according to geographic region, suggesting that some sequence changes may have conferred an advantage by increasing resistance to viral infection.

Interferons (IFNs) are cytokines that play a key role in innate and adaptive immune responses. Despite the large number of immunological studies of these molecules, the relative contributions of the numerous IFNs to human survival remain largely unknown. Here, we evaluated the extent to which natural selection has targeted the human IFNs and their receptors, to provide insight into the mechanisms that govern host defense in the natural setting. We found that some IFN-α subtypes, such as IFN-α6, IFN-α8, IFN-α13, and IFN-α14, as well as the type II IFN-γ, have evolved under strong purifying selection, attesting to their essential and nonredundant function in immunity to infection. Conversely, selective constraints have been relaxed for other type I IFNs, particularly for IFN-α10 and IFN-ε, which have accumulated missense or nonsense mutations at high frequencies within the population, suggesting redundancy in host defense. Finally, type III IFNs display geographically restricted signatures of positive selection in European and Asian populations, indicating that genetic variation at these genes has conferred a selective advantage to the host, most likely by increasing resistance to viral infection. Our population genetic analyses show that IFNs differ widely in their biological relevance, and highlight evolutionarily important determinants of host immune responsiveness.

The alloherpesviral counterparts of interleukin 10 in European eel and common carp

Viral interleukin 10 (IL-10) like open reading frames have been identified in several pox- and herpesviruses, including the fish herpesviruses Anguillid herpesvirus 1 (AngHV-1) and Cyprinid herpesvirus 3 (CyHV-3). European eel (Anguilla anguilla) IL-10 was sequenced, in order to compare European eel and common carp (Cyprinus carpio) IL-10 with their alloherpesviral counterparts. Homology between the virus and host IL-10 amino acid sequences is low, which is confirmed by phylogenetic analysis. However, the three dimensional structures of the fish and alloherpesviral IL-10 proteins as predicted by modeling are highly similar to human IL-10. Closely related AngHV-1 and CyHV-3 are expected to have obtained their viral IL-10 genes independently in the course of coexistence with their respective hosts. The presence and structural conservation of these alloherpesviral IL-10 genes suggest that they might play an important role in the evolution of pathogenesis.

cDNA cloning, genomic structure, molecular characterization and mRNA expression analysis of the Pekin duck interleukin-10 receptor 1

Interleukin-10 (IL-10) mediates its broad anti-inflammatory and immunoregulatory effects through two cell surface receptors by which binding to the IL-10 receptor 1 (IL-10R1) is the initial step that leads to recruitment of IL-10R2 and initiation of the ternary complex signal transduction cascade. The duck IL-10R1 (duIL-10R1) cDNA was obtained by using RT-PCR and 5'RACE. The deduced 574 amino acid protein has an amino acid identity of 62%, 27% and 28% with chicken, mouse and human IL-10R1, respectively. Comparison of the duIL-10R1 cDNA with duck genomic sequences revealed a seven exon-six intron structure of the duck IL-10R1 gene that shares a similar size with the respective exons 1-7 of the chicken and human IL-10R1 genes, but the avian genes are more compact. Promoter analysis identified putative binding sites for regulatory elements such as CCAAT enhancer binding protein-α, specificity protein 1 (Sp1), nuclear factor 1 (NF1), transcriptional regulatory protein Oct-1, nuclear factor (NF) κB and interferon-stimulated gene factor-3 (ISGF-3). A canonical TATA box was absent in proximity of the transcription initiation site, but a CpG island was present. Sequence analysis of the predicted duIL-10R1 protein revealed characteristic features of class-II cytokine receptors (CFR2) family members and a considerable degree of conservation of residues implicated in ligand binding across higher vertebrates. The predicted secondary structure of the duIL-10R1 extracellular domain is compatible with the two-subdomain structure of the human IL-10R1 protein established by its crystal structure. The 3D model structure shows conservation of the positions of conserved contact residues within four of the five ligand-binding loops. Within the cytoplasmic domain, residues implicated in signal transduction were conserved including two redundant peptide motifs GYXXQ essential for recruitment and activation of STAT3. DuIL-10R1 mRNA expression was most abundant in spleen, thymus, peripheral blood mononuclear cells (PBMCs) and lung. Mitogen stimulation of PBMCs transiently increased duIL-10R1 mRNA expression. Our observations suggest significant evolutionary conservation of the IL-10R1 genomic organization, protein structure and receptor function through the JAK/STAT signalling pathway across higher vertebrates.

Regulation of interleukin-10 receptor ubiquitination and stability by beta-TrCP-containing ubiquitin E3 ligase

Interleukin-10 (IL-10) initiates potent anti-inflammatory effects via activating its cell surface receptor, composed of IL-10R1 and IL-10R2 subunits. The level of IL-10R1 is a major determinant of the cells' responsiveness to IL-10. Here, via a series of biochemical analyses using 293T cells reconstituted with IL-10R1, we identify the latter as a novel substrate of βTrCP-containing ubiquitin E3 ligase. Within the intracellular tail of IL-10R1, a canonical (³¹⁸DpSGFGpS) and a slightly deviated (³⁶⁹DpSGICLQEP) βTrCP recognition motif can additively recruit βTrCP in a phosphorylation-dependent manner. βTrCP recruitment leads to ubiquitination, endocytosis and degradation of IL-10R1, subsequently reducing the cellular responsiveness to IL-10. Our study uncovers a novel negative regulatory mechanism that may potentially affect IL-10 function in target cells under physiological or pathological conditions.

Role of interleukin-10 in breast cancer

Cytokines are low molecular weight regulatory proteins or glycoprotein that modulates the intensity and duration of immune response by stimulating or inhibiting the activation, proliferation, and/or differentiation of target cells. Different cytokines are known to have diverse role in breast cancer initiation and progression. Interleukin-10 (IL-10), a pleiotropic anti-inflammatory cytokine, induces immunosuppression and assists in escape from tumor immune surveillance. Like several other cytokines, IL-10 also can exert dual proliferative and inhibitory effect on breast tumor cells indicating a complex role of IL-10 in breast cancer initiation and progression. In this review, we tried to put together a comprehensive current view on significance of IL-10 in promotion, inhibition, and importance as prognosticator in breast cancer based on in vitro, in vivo, and clinical evidences. For literature collection, we conducted PubMed search with keywords "IL-10" and "breast cancer".

Multiple CD4+ T cell subsets produce immunomodulatory IL-10 during respiratory syncytial virus infection

The host immune response is believed to contribute to the severity of pulmonary disease induced by acute respiratory syncytial virus (RSV) infection. Because RSV-induced pulmonary disease is associated with immunopathology, we evaluated the role of IL-10 in modulating the RSV-specific immune response. We found that IL-10 protein levels in the lung were increased following acute RSV infection, with maximum production corresponding to the peak of the virus-specific T cell response. The majority of IL-10-producing cells in the lung during acute RSV infection were CD4(+) T cells. The IL-10-producing CD4(+) T cells included Foxp3(+) regulatory T cells, Foxp3(-) CD4(+) T cells that coproduce IFN-γ, and Foxp3(-) CD4(+) T cells that do not coproduce IFN-γ. RSV infection of IL-10-deficient mice resulted in more severe disease, as measured by increased weight loss and airway resistance, as compared with control mice. We also observed an increase in the magnitude of the RSV-induced CD8(+) and CD4(+) T cell response that correlated with increased disease severity in the absence of IL-10 or following IL-10R blockade. Interestingly, IL-10R blockade during acute RSV infection altered CD4(+) T cell subset distribution, resulting in a significant increase in IL-17A-producing CD4(+) T cells and a concomitant decrease in Foxp3(+) regulatory T cells. These results demonstrate that IL-10 plays a critical role in modulating the adaptive immune response to RSV by limiting T-cell-mediated pulmonary inflammation and injury.

Regulation and functions of the IL-10 family of cytokines in inflammation and disease

The IL-10 family of cytokines consists of nine members: IL-10, IL-19, IL-20, IL-22, IL-24, IL-26, and the more distantly related IL-28A, IL-28B, and IL-29. Evolutionarily, IL-10 family cytokines emerged before the adaptive immune response. These cytokines elicit diverse host defense mechanisms, especially from epithelial cells, during various infections. IL-10 family cytokines are essential for maintaining the integrity and homeostasis of tissue epithelial layers. Members of this family can promote innate immune responses from tissue epithelia to limit the damage caused by viral and bacterial infections. These cytokines can also facilitate the tissue-healing process in injuries caused by infection or inflammation. Finally, IL-10 itself can repress proinflammatory responses and limit unnecessary tissue disruptions caused by inflammation. Thus, IL-10 family cytokines have indispensable functions in many infectious and inflammatory diseases.

Cot/tpl2 activity is required for TLR-induced activation of the Akt p70 S6k pathway in macrophages: Implications for NO synthase 2 expression

LPS stimulation activates IKK and different MAP kinase pathways, as well as the PI3K-Akt-mTOR-p70 S6k pathway, a negative regulator of these MyD88-dependent intracellular signals. Here, we show that Cot/tpl2, a MAP3K responsible for the activation of the MKK1-Erk1/2, controls P-Ser473 Akt and P-Thr389 p70 S6k phosphorylation in LPS-stimulated macrophages. Analysis of the intracellular signalling in Cot/tpl2 KO macrophages versus WT macrophages reveals lower IκBα recovery and higher phosphorylation of JNK and p38α after 1 h of LPS stimulation. Moreover, Cot/tpl2 deficiency increases LPS-induced NO synthase 2 (NOS2) expression in macrophages. Inhibition of the PI3K pathway abolishes the differences in IκBα and NOS2 expression between Cot/tpl2 KO and WT macrophages following LPS administration. Furthermore, in zymosan- and polyI:C-stimulated macrophages, Cot/tpl2 mediates P-Ser473 Akt phosphorylation, increases IκBα levels and decreases NOS2 expression. In conclusion, these data reveal a novel role for the Cot/tpl2 pathway in mediating TLR activation of the Akt-mTOR-p70 S6k pathway, allowing Cot/tpl2 to fine-control the activation state of other signalling pathways.

Interleukin-10 and immunity against prokaryotic and eukaryotic intracellular pathogens

The generation of an effective immune response against an infection while also limiting tissue damage requires a delicate balance between pro- and anti-inflammatory responses. Interleukin-10 (IL-10) has potent immunosuppressive effects and is essential for regulation of immune responses. However, the immunosuppressive properties of IL-10 can also be exploited by pathogens to facilitate their own survival. In this minireview, we discuss the role of IL-10 in modulating intracellular bacterial, fungal, and parasitic infections. Using information from several different infection models, we bring together and highlight some common pathways for IL-10 regulation and function that cannot be fully appreciated by studies of a single pathogen.

IL-10R1 S138G loss-of-function polymorphism is associated with extrapulmonary tuberculosis risk development in Tunisia

There is considerable evidence that host genetic factors are important in determining susceptibility to mycobacterial infections. More recently, functional genetic mutations affecting IL-10 receptor 1 (IL-10R1) were described. In this study, we investigated the relationship of IL-10R1 S138G loss-of-function polymorphism (A536G: rs3135932) with susceptibility to active tuberculosis (TB) in Tunisian patients. A total of 168 patients with pulmonary TB, 55 with extrapulmonary TB, and 150 control subjects were studied. Genomic DNA samples were extracted from leukocytes and used to investigate S138G polymorphism in IL-10R1 gene by multiplex allele-specific polymerase chain reaction. Associations between G allele [odds ratio OR=5.01; 95% confidence intervals CI=2.58-9.77; P=10(-7)], GG genotypes [OR=9.06; 95% CI (1.58-67.33); correcting P-values using the Bonferroni method for multiple tests Pc=0.015] and AG genotype [OR=3.75; 95% CI (1.62-8.7); Pc=0.0012] with the risk development of active extrapulmonary TB were found. In contrast, the AA genotype was found to be associated with resistance to extrapulmonary TB [OR=0.19; 95% CI (0.09-0.42); Pc=6.10(-6)]. No association was found between S138G SNP and pulmonary TB. In conclusion, our study suggested the possible role of IL-10R1 S138G loss-of-function polymorphism in extrapulmonary TB susceptibility-resistance in Tunisia.

A synthetic peptide homologous to IL-10 functional domain induces monocyte differentiation to TGF-β+ tolerogenic dendritic cells

We have previously demonstrated that IT9302, a nonameric peptide homologous to the C-terminal domain of human IL-10, mimics several effects of the cytokine including down-regulation of the antigen presentation machinery and increased sensitivity of tumor cells to NK-mediated lysis. In the present report, we have explored a potential therapeutic utility for IT9302 related to the ex vivo production of tolerogenic dendritic cells (DCs). Our results indicate that IT9302 impedes human monocyte response to differentiation factors and reduces antigen presentation and co-stimulatory capacity by DCs. Additionally, peptide-treated DCs show impaired capacity to stimulate T-cell proliferation and IFN-γ production. IT9302 exerts its effect through mechanisms, in part, distinct from IL-10, involving STAT3 inactivation and NF-κB intracellular pathway. IT9302-treated DCs display increased expression of membrane-associated TGF-β, linked to a more effective induction of foxp3+ regulatory T cells. These results illustrate for the first time that a short synthetic peptide can promote monocytes differentiation to tolerogenic DCs with therapeutic potential for the treatment of autoimmune and transplantation-related immunopathologic disease.

Interferon-lambda: a new addition to an old family

The discovery and initial description of the interferon-lambda (IFN-lambda) family in early 2003 opened an exciting new chapter in the field of IFN research. There are 3 IFN-lambda genes that encode 3 distinct but highly related proteins denoted IFN-lambda1, -lambda2, and -lambda3. These proteins are also known as interleukin-29 (IL-29), IL-28A, and IL-28B, respectively. Collectively, these 3 cytokines comprise the type III subset of IFNs. They are distinct from both type I and type II IFNs for a number of reasons, including the fact that they signal through a heterodimeric receptor complex that is different from the receptors used by type I or type II IFNs. Although type I IFNs (IFN-alpha/beta) and type III IFNs (IFN-lambda) signal via distinct receptor complexes, they activate the same intracellular signaling pathway and many of the same biological activities, including antiviral activity, in a wide variety of target cells. Consistent with their antiviral activity, expression of the IFN-lambda genes and their corresponding proteins is inducible by infection with many types of viruses. Therefore, expression of the type III IFNs (IFN-lambdas) and their primary biological activity are very similar to the type I IFNs. However, unlike IFN-alpha receptors which are broadly expressed on most cell types, including leukocytes, IFN-lambda receptors are largely restricted to cells of epithelial origin. The potential clinical importance of IFN-lambda as a novel antiviral therapeutic agent is already apparent. In addition, preclinical studies by several groups indicate that IFN-lambda may also be useful as a potential therapeutic agent for other clinical indications, including certain types of cancer.

Regulation of STAT signaling in mouse bone marrow derived dendritic cells by respiratory syncytial virus

BACKGROUND/AIMS

Dendritic cells (DCs) act as a portal for virus invasion as well as potent antigen-presenting cells (APCs) involved in the antiviral host response. Interferons (IFNs) are produced in response to bacterial and viral infection and activate innate immune responses to efficiently counteract and remove pathogenic invaders. Respiratory syncytial virus (RSV) could inhibit IFN-mediated signaling pathway in epithelial cells; however, the effects of RSV on IFN signaling in the dendritic cells (DCs) are still unknown.

METHODS

Mouse bone marrow derived DCs (BMDCs) were mock or infected with RSV at different multiplicity of infection (MOI) for 24h, and then treated with different cytokines such as interferon-β (IFN-β), IFN-γ or interleukin-10 (IL-10). The mRNA expression of RSV nonstructural protein-1 (NS-1) and NS-2 was detected by RT-PCR. The expression of Janus family kinase-signal transducer and activator of transcription (JAK/STAT) signaling proteins was assessed by immunoblotting assays. The nuclear localization of specific signaling proteins was determined by immunofluorescence assay.

RESULTS

Increasing amounts of NS-1 or NS-2 mRNA expression in BMDCs were observed with infected RSV at increasing MOI, suggesting BMDCs were permissive for viral gene expression. Further examination of the IFN-β signaling cascade showed RSV infection increased the total cellular levels of STAT1 and STAT2 in BMDCs, but impaired the IFN-β-dependent phosphorylation and nuclear localization of STAT1 and STAT2. The inhibitory effects of RSV on STAT1 and STAT2 phosphorylation and translocation were abolished by UV inactivation. In contrast, RSV did not inhibit the IFN-γ-stimulated STAT1 phosphorylation and nuclear localization. IL-10-stimulated STAT3 phosphorylation was also unaffected by RSV.

CONCLUSIONS

As well as RSV inhibiting STAT protein levels through degradation mechanisms in epithelial cells, these findings demonstrate that RSV also can specifically inhibit the type I interferon response in BMDCs through regulation of STAT1 and STAT2 phosphorylation and nuclear translocation.

Structural analysis of cytokines comprising the IL-10 family

Interleukin-10 (IL-10) family of cytokines includes a number of its viral homologs and eight cellular cytokines (IL-19, IL-20, IL-22, IL-24, IL-26, IL-28A, IL-28B, and IL-29). The latter three proteins are also known as IFN-λ2, IFN-λ3, and IFN-λ1, and are recognized as type III (or λ) interferons. Most of the cellular homologs of IL-10 are monomeric in solution, whereas IL-10 and its viral homologs are intercalated dimers consisting of two helical bundle domains topologically similar to the monomeric members of the family. A classical four-helix bundle, a signature element of all helical cytokines, is always found as part of the domain of each member of the IL-10 family. The only crystal structures of these cytokine receptors that have been determined to date are for their extracellular domains (ECDs). Each ECD consists of two β-sandwich domains connected in the middle by a linkage. Signal transduction occurs when a cytokine binds to its two appropriate receptor chains. IL-10 and its viral homologs use the same IL-10 receptor system, whereas the cellular homologs of IL-10 use their own receptors, which in some cases may overlap and be used in different pairwise combinations. The known structures of binary complexes allowed for marking of the receptor binding site, which always includes helix A, loop AB and helix F (IL-10 notations) on the side of a ligand, loops of the N-terminal and C-terminal domains directed toward the ligand, and the interdomain linkage of the ECD. An analysis of the published structures of both the binary and ternary complexes of all helical cytokines allowed for the generation of a model of the signaling complex of IL-10. The receptor binding site I of the high affinity receptor IL-10R1 is exactly the same as in the crystal structure of the binary IL-10/sIL-10R1 complex, whereas the receptor binding site II is located on the surface of the first and the third helices of the four-helix bundle. The receptor/receptor interface, or site III, is formed between the C-terminal domains of IL-10R1 and IL-10R2.

Endogenous IL-10 attenuates cisplatin nephrotoxicity: role of dendritic cells

Sterile inflammation is associated with tissue injury and organ failure. Recent studies indicate that certain endogenous cytokines and immune cells may limit tissue injury by reducing immune-mediated inflammatory responses. Cisplatin is a commonly used anticancer chemotherapeutic agent but causes acute kidney injury and dysfunction. In a recent study, we showed that renal dendritic cells attenuate cisplatin-induced kidney injury by reducing inflammation. In this study, we investigated the effect of endogenous IL-10 and dendritic cell IL-10 in cisplatin-mediated kidney injury. Cisplatin treatment caused increases in renal IL-10R1 expression and STAT3 phosphorylation. In response to cisplatin treatment, IL-10 knockout mice showed more rapid and greater increases in blood urea nitrogen and serum creatinine compared with wild-type mice, indicating that endogenous IL-10 ameliorates kidney injury in cisplatin nephrotoxicity. Renal infiltration of IFN-γ-producing neutrophils was markedly increased in IL-10 knockout mice compared with wild-type mice. However, IFN-γ neutralization had no impact on renal dysfunction, suggesting IFN-γ-independent mechanisms of tissue injury in cisplatin nephrotoxicity. Renal dendritic cells showed high expression of IL-10 in response to cisplatin treatment. We further investigated the effect of dendritic cell-derived IL-10 in cisplatin nephrotoxicity using a conditional cell ablation approach. Mixed bone marrow chimeric mice lacking IL-10 in dendritic cells showed moderately greater renal dysfunction than chimeric mice positive for IL-10 in dendritic cells. These data demonstrate that endogenous IL-10 reduces cisplatin nephrotoxicity and associated inflammation. Moreover, IL-10 produced by dendritic cells themselves accounts for a portion of the protective effect of dendritic cells in cisplatin nephrotoxicity.

Structure and function of interleukin-22 and other members of the interleukin-10 family

The IL-10 family of cytokines is comprised of IL-10, IL-19, IL-20, IL-22, IL-24, IL-26, and IFN-lambdas (IL-28A, IL-28B, and IL-29). The IL-10 family members bind to shared class II cytokine receptor chains that associate in various combinations in heterodimeric complexes. Upon interleukin/receptor complex formation, these proteins switch on the Jak/STAT pathway and elicit pleiotropic biological responses whose variety sharply contrasts with their structural similarities. IL-10 family members are involved in several human diseases and health conditions and hence their structural analyses may provide valuable information to design specific therapeutic strategies. In this review, we describe the human interleukin-10 family of cytokines, focusing on their structures and functions, with particular attention given to IL-22 and IL-10. We report on the recently published structures of IL-10 cytokine family members and their complexes with cognate transmembrane and soluble receptors as well as on interleukin physiology and physiopathology.

Effect of host genetics on the development of cytomegalovirus retinitis in patients with AIDS

BACKGROUND

Cytomegalovirus (CMV) retinitis is a common opportunistic infection among patients with AIDS and still causes visual morbidity despite the wide spread usage of highly active antiretroviral therapy (HAART). The ubiquitous CMV pathogen contains a human interleukin-10 (IL-10) homolog in its genome and utilizes it to evade host immune reactions through an IL-10 receptor mediated immune-suppression pathway.

METHODS

Effects of IL-10R1, IL-10 and previously described AIDS restriction gene variants are investigated on the development of CMV retinitis in the Longitudinal Study of the Ocular Complications of AIDS (LSOCA) cohort (N = 1284).

RESULTS

In European Americans (n = 750), a haplotype carrying an amino acid changing variation in the cytoplasmic domain (S420L) of IL-10R1 can be protective (OR, 0.14; 95% CI, 0.02-0.94; P = .04) against, whereas another haplotype carrying an amino acid changing variation in the extracellular domain (I224V) of IL-10R1 can be more susceptible (OR, 6.21; 95% CI, 1.22- 31.54; P = .03) to CMV retinitis. In African Americans (n = 534), potential effects of IL-10 variants are observed.

CONCLUSION

Host genetics may have a role in the occurrence of CMV retinitis in patients infected with HIV.

Interferon-λ in HCV Infection and Therapy

Chronic infection with hepatitis C virus (HCV) is associated with significant liver disease and is therefore an important public health problem. The current standard-of-care therapy for chronic HCV infection consists of a combination of pegylated (PEG) interferon (IFN)-α and ribavirin. Although this therapy effectively generates a sustained viral response in approximately half of treated individuals, it is associated with significant hematological and neurological side effects. A new family of IFN-related proteins (IFN-λ1, 2, and 3; or alternately, IL-29, 28A, 28B, respectively) possesses properties that may make these cytokines superior to PEG-IFN-α for HCV therapy. Genetic studies have also implicated these proteins in both the natural and therapy-induced resolution of HCV infection. This review summarizes the basic aspects of IFN-λ biology, the potential role of these cytokines in HCV infection, and the outlook for their therapeutic application.

The structure of human interferon lambda and what it has taught us

Type III interferon (IFN) or IFN-lambda is a novel family of class II cytokines that induces antiviral activities both in vitro and in vivo through its own distinctive receptor complex. The recent crystal structure of human IFN-lambda3 revealed a cytokine with structural similarity to the interleukin-10 family, despite functionally being an IFN. Here, we review the structure of IFN-lambda and its relation to the other members of the class II cytokines. Further, we analyze the structural differences between the tree human isoforms of IFN-lambda and relate this to the observed differences in potency.

Structure and mechanism of receptor sharing by the IL-10R2 common chain

IL-10R2 is a shared cell surface receptor required for the activation of five class 2 cytokines (IL-10, IL-22, IL-26, IL-28, and IL-29) that play critical roles in host defense. To define the molecular mechanisms that regulate its promiscuous binding, we have determined the crystal structure of the IL-10R2 ectodomain at 2.14 A resolution. IL-10R2 residues required for binding were identified by alanine scanning and used to derive computational models of IL-10/IL-10R1/IL-10R2 and IL-22/IL-22R1/IL-10R2 ternary complexes. The models reveal a conserved binding epitope that is surrounded by two clefts that accommodate the structural and chemical diversity of the cytokines. These results provide a structural framework for interpreting IL-10R2 single nucleotide polymorphisms associated with human disease.

Association of genetic variants, ethnicity and preterm birth with amniotic fluid cytokine concentrations

We examined the association of 166 single nucleotide polymorphisms (SNPs) in cytokines and cytokine related genes with cytokine concentrations (IL-1beta, IL-8, and IL-10) in the amniotic fluid (AF). These cytokines have been associated with spontaneous preterm birth (PTB) and their genetic regulation may play a role in disease risk. These associations were studied in both PTB and term births in African Americans and Caucasians; maternal and fetal genotypes were studied separately. Analyses modeled genotype, pregnancy status, and marker by pregnancy status (case/control) interaction with cytokine concentration as outcome. Our results indicate that AF cytokines (IL-1beta and IL-10) were associated with interactions between pregnancy status and both maternal and fetal SNPs, with the most significant interactions being observed for African Americans with IL-1beta concentration (maternal at IL1RAP rs1024941 p < 10(-3), fetal IL1RAP rs3773953 p < 10(-3)). AF IL-10 concentrations also showed evidence for association with SNPs in both ethnicities with the most significant interaction in Caucasian maternal samples (IL10 rs1800896 p < 10(-3)). Our data indicate that the genetic regulation of cytokine concentrations in PTB likely differs by ethnicity. AF cytokine concentrations were associated with interactions between genotype and PTB in African Americans, but less so in Caucasians.

The role of IL-10 in regulating immunity to persistent viral infections

The immune system has evolved multipronged responses that are critical to effectively defend the body from invading pathogens and to clear infection. However, the same weapons employed to eradicate infection can have caustic effects on normal bystander cells. Therefore, tight regulation is vital and the host must balance engendering correct and sufficient immune responses to pathogens while limiting errant and excessive immunopathology. To accomplish this task, a complex network of positive and negative immune signals are delivered, which in most instances successfully eliminate the pathogen. However, in response to some viral infections, immune function is rapidly suppressed leading to viral persistence. Immune suppression is a critical obstacle to the control of many persistent viral infections such as HIV, hepatitis C, and hepatitis B virus, which together affect more than 500 million individuals worldwide. Thus, the ability to therapeutically enhance immunity is a potentially powerful approach to resolve persistent infections. The host-derived cytokine IL-10 is a key player in the establishment and perpetuation of viral persistence. This chapter discusses the role of IL-10 in viral persistence and explores the exciting prospect of therapeutically blocking IL-10 to increase antiviral immunity and vaccine efficacy.

A comparative analysis of gene expression patterns and cell phenotypes between cervical and peripheral blood mononuclear cells

Studies of the immunological environment in the female genital tract (FGT) are critical for the development of vaccines or microbicides to halt the spread of sexually transmitted infections. Challenges arise due to the difficulties of sampling from this site, and the majority of studies have been conducted utilising peripheral blood mononuclear cells. Identifying functional differences between immune cells of the FGT and peripheral blood would aid in our understanding of mucosal immunology. We compared the gene expression profile of mononuclear cells at these two sites. Messenger RNA expression analysis was performed using gene expression arrays on matched cervical mononuclear cells and peripheral blood mononuclear cells. Further cellular phenotyping was done by 10 colour flow cytometry. Of the 22,185 genes expressed by these samples, 5345 genes were significantly differentially expressed between the cell populations. Most differences can be explained by significantly lower levels of T and B cells and higher levels of macrophages and dendritic cells in the FGT compared with peripheral blood. Several immunologically relevant pathways such as apoptosis and innate immune signalling, and a variety of cytokines and cytokine receptors were differentially expressed. This study highlights the importance of the unique immunological environment of the FGT and identifies important differences between systemic and mucosal immune compartments.

Inflammatory bowel disease and mutations affecting the interleukin-10 receptor

BACKGROUND

The molecular cause of inflammatory bowel disease is largely unknown.

METHODS

We performed genetic-linkage analysis and candidate-gene sequencing on samples from two unrelated consanguineous families with children who were affected by early-onset inflammatory bowel disease. We screened six additional patients with early-onset colitis for mutations in two candidate genes and carried out functional assays in patients' peripheral-blood mononuclear cells. We performed an allogeneic hematopoietic stem-cell transplantation in one patient.

RESULTS

In four of nine patients with early-onset colitis, we identified three distinct homozygous mutations in genes IL10RA and IL10RB, encoding the IL10R1 and IL10R2 proteins, respectively, which form a heterotetramer to make up the interleukin-10 receptor. The mutations abrogate interleukin-10-induced signaling, as shown by deficient STAT3 (signal transducer and activator of transcription 3) phosphorylation on stimulation with interleukin-10. Consistent with this observation was the increased secretion of tumor necrosis factor alpha and other proinflammatory cytokines from peripheral-blood mononuclear cells from patients who were deficient in IL10R subunit proteins, suggesting that interleukin-10-dependent "negative feedback" regulation is disrupted in these cells. The allogeneic stem-cell transplantation performed in one patient was successful.

CONCLUSIONS

Mutations in genes encoding the IL10R subunit proteins were found in patients with early-onset enterocolitis, involving hyperinflammatory immune responses in the intestine. Allogeneic stem-cell transplantation resulted in disease remission in one patient.

Human interleukin 10 receptor 1/IgG1-Fc fusion proteins: immunoadhesins for human IL-10 with therapeutic potential

Interleukin 10 (IL-10) is produced by various types of human cancer, including malignant melanoma, and plays an important role in negative regulation of cell-mediated immune responses against tumors. We have developed chimeric molecules (immunoadhesins), combining the extracellular domain of human interleukin 10 receptor 1 (IL-10R1) with the Fc regions of human IgG1 heavy chain and investigated their capability of blocking the biological activities of human IL-10. Monomeric and dimeric immunoadhesins (IL-10R1/IgG1) constructs were tested for capturing human IL-10 and blocking its biological activities. Plasmid vectors that contained the IL-10 immunoadhesin constructs were directly transfected into human melanoma cell lines. Transfection of plasmid vectors into melanoma cell lines resulted in capturing of exogenously added as well as endogeneously produced IL-10. The supernatants obtained from an IL-10 non-producing melanoma cell line transfected with monomeric IL-10 immunoadhesin plasmids most efficiently captured exogenously added IL-10, compared to those obtained with the dimeric IL-10R1/IgG1 plasmid vector. Transfection of IL-10-producing melanoma cells with the monomeric IL-10 immunoadhesin plasmids totally captured endogenously produced IL-10 and enhanced T cell responses against allogeneic melanoma cells. Furthermore, purified monomeric IL-10 immunoadhesin protein showed IL-10 capturing efficacy compatible with that of IL-10-specific monoclonal antibodies. Collectively, these studies indicate that IL-10 immunoadhesins, especially in monomeric form, are potent inhibitors of biological activities of IL-10 and suggest that these molecules, alone or in conjunctions with other immunotherapeutic approaches, can be utilized for the immuno-targeting of IL-10 producing tumors.

Differential signaling of cmvIL-10 through common variants of the IL-10 receptor 1

Human IL-10 (hIL-10) signaling is mediated by receptors consisting of two subunits, IL-10 receptor 1 (IL-10R1) and IL-10 receptor 2. Two common variants of the IL-10R1 (Ser 138 Gly (single-nucleotide polymorphism 3, SNP3) and Gly 330 Arg (SNP4)) are associated with diverse disease phenotypes. Viral homologs to hIL-10, such as cmvIL-10, utilize the same IL-10 receptor complex as part of viral immune evasion strategies. For the present study we hypothesized that IL-10R1 variants alter the ability of viral IL-10 to utilize the IL-10R1 signaling pathway. HeLa cell clones expressing different IL-10R1 haplotypes (WT or any variant) were incubated with hIL-10 or cmvIL-10. In cells expressing IL-10R1-WT, cmvIL-10 (both non-glycosylated- and HeLa-expressed) resulted in equal or slightly stronger STAT3 phosphorylation compared with hIL-10. In clones expressing IL-10R1-SNP3, IL-10R1-SNP4 or IL-10R1-SNP3+4, the cmvIL-10 showed significantly less STAT3 phosphorylation, especially when HeLa-expressed cytokines were used. Time course experiments demonstrated a slower kinetic of cmvIL-10 STAT3 activation through the variant IL-10R1. Similarly, IL-10R1 variants decreased the cmvIL-10-induced SOCS3 and signaling lymphocytic activation molecule mRNA expression. These data suggest that the IL-10R1 variants differentially reduce the signaling activity of cmvIL-10 and thereby may affect CMV's ability to escape from the host's immune surveillance.

Regulation of apoptosis by type III interferons

OBJECTIVE

Two types of interferons (IFNs), type I (IFN-alpha/beta) and type III (IFN-lambdas), utilize distinct receptor complexes to induce similar signalling and biological activities, including recently demonstrated for IFN-lambdas antitumour activity. However, ability of type III IFNs to regulate cell population growth remains largely uncharacterized.

MATERIALS AND METHODS

Intact and modified human colorectal adenocarcinoma HT29 cells were used to study regulation of apoptosis by IFN-lambdas.

RESULTS AND CONCLUSIONS

We report that the IFN-lambdaR1 chain of the type III IFN receptor complex possesses an intrinsic ability to trigger apoptosis in cells. Signalling induced through the intracellular domain of IFN-lambdaR1 resulted in G(1)/G(0) phase cell cycle arrest, phosphatidylserine surfacing and chromosomal DNA fragmentation. Caspase-3, caspase-8 and caspase-9 were activated; however, pancaspase inhibitor Z-VAD-FMK did not prevent apoptosis. In addition, the extent of apoptosis correlated with the level of receptor expression and was associated with prolonged IFN-lambda signalling. We also demonstrated that the ability to trigger apoptosis is a unique intrinsic function of all IFN receptors. However, more robust apoptosis was induced by signalling through type III IFN receptor than through type I or type II (IFN-gamma) receptors, suggesting higher cytotoxic potential of type III IFNs. In addition, we observed that IFN-gamma treatment sensitized HT29 cells to IFN-lambda-mediated apoptosis. These results provide evidence that type III IFNs, alone or in combination with other stimuli, have the potential to induce apoptosis.

Interferon-lambda1 (interleukin-29) preferentially down-regulates interleukin-13 over other T helper type 2 cytokine responses in vitro

Interferon (IFN)-lambda1 [interleukin (IL)-29] is a member of the interferon lambda family (also known as type III interferons), whose members are distantly related to both the type I interferons and members of the IL-10 family. While IFN-lambda1 has significant antiviral activity, it is also becoming apparent that it has important immunoregulatory properties, especially with regard to the T helper type 2 (Th2) response. Previously, we have shown that IFN-lambda1 is capable of down-regulating IL-13 production in an IFN-gamma-independent manner and that this is mediated in part via monocyte-derived dendritic cells. Here, we have extended our knowledge of IFN-lambda1 regulation of the human in vitro Th2 response by examining the regulation of three major Th2 cytokines, IL-4, IL-5 and IL-13, by IFN-lambda1. Our results reveal that IFN-lambda1 preferentially inhibits IL-13 production, compared with IL-4 or IL-5. Levels of IL-13 mRNA, the amount of secreted IL-13 protein and numbers of IL-13-positive CD3(+) CD4(+) cells were all significantly diminished by IFN-lambda1. IFN-lambda1 significantly decreased some aspects of IL-4 and IL-5 production, but its effects were not as consistent as those seen on IL-13. IFN-lambda1 was also effective at decreasing IL-13 secretion under conditions designed to support the generation of Th2 cells. Irrespective of whether Concanavalin-A or T-cell-stimulatory microbeads were used, IFN-lambda1 markedly diminished IL-13 secretion in cultures where IL-4 had been added. Thus, IFN-lambda1 appears to be an inhibitor of human Th2 responses whose action is primarily directed towards IL-13 but which may also affect Th2 responses generally and does not invoke a complementary elevation of IFN-gamma secretion.

Structure of IL-22 bound to its high-affinity IL-22R1 chain

IL-22 is an IL-10 family cytokine that initiates innate immune responses against bacterial pathogens and contributes to immune disease. IL-22 biological activity is initiated by binding to a cell-surface complex composed of IL-22R1 and IL-10R2 receptor chains and further regulated by interactions with a soluble binding protein, IL-22BP, which shares sequence similarity with an extracellular region of IL-22R1 (sIL-22R1). IL-22R1 also pairs with the IL-20R2 chain to induce IL-20 and IL-24 signaling. To define the molecular basis of these diverse interactions, we have determined the structure of the IL-22/sIL-22R1 complex. The structure, combined with homology modeling and surface plasmon resonance studies, defines the molecular basis for the distinct affinities and specificities of IL-22 and IL-10 receptor chains that regulate cellular targeting and signal transduction to elicit effective immune responses.

Interleukin-10 attenuates TNF-alpha-induced interleukin-6 production in endometriotic stromal cells

OBJECTIVE

To determine whether high levels of interleukin (IL)-10 can attenuate the production of tumor necrosis factor (TNF)-alpha-induced proinflammatory cytokines in endometriotic stromal cells.

DESIGN

Prospective study.

SETTING

Department of Ob/Gyn, Tottori University, Japan.

PATIENT(S)

Thirty-five patients with ovarian endometrioma and ten patients with uterine myoma.

INTERVENTION(S)

Endometriotic stromal cells were obtained from chocolate cyst linings of ovaries. Endometrial stromal cells obtained from patient with uterine myoma.

MAIN OUTCOME MEASURE(S)

Expression of IL-10 gene in endometriotic or endometrial stromal cells was determined by real-time reverse-transcriptase polymerase chain reaction (RT-PCR). We performed immunohistochemical staining to find the presence of IL-10 and IL-10 receptors 1 and 2. We examined the effects of TNF-alpha and IL-10 on the expression of IL-6 or IL-8 by real-time RT-PCR and ELISA. We examined the activation of intracellular signal transduction molecules in endometriotic stromal cells by Western blotting.

RESULT(S)

Addition of IL-10 suppressed the expressions of IL-6 induced by TNF-alpha and IL-10 induced the phosphorylation of STAT3 in endometriotic stromal cells. TNF-alpha induced the expression of phosphorylated ERK1/2, JNK1/2, and I kappaB. Adding IL-10 suppressed the phosphorylation of these signal molecules.

CONCLUSION(S)

Interleukin-10 attenuates TNF-alpha-induced IL-6 synthesis via NF-kappaB and MAPK pathways in endometriotic cells.. Interleukin-10 may play a significant role in the pathogenesis of endometriosis.

Mesenchymal stem cells in early entry of breast cancer into bone marrow

Background

An understanding of BC cell (BCC) entry into bone marrow (BM) at low tumor burden is limited when compared to highly metastatic events during heavy tumor burden. BCCs can achieve quiescence, without interfering with hematopoiesis. This occurs partly through the generation of gap junctions with BM stroma, located close to the endosteum. These events are partly mediated by the evolutionary conserved gene, Tac1.

Methodogy/Principal Findings

This study focuses on the role of mesenchymal stem cells (MSCs), Tac1, SDF-1 and CXCR4 in BCC entry into BM. The model is established in studies with low numbers of tumor cells, and focuses on cancer cells with low metastatic and invasion potential. This allowed us to recapitulate early event, and to study cancer cells with low invasive potential, even when they are part of larger numbers of highly metastatic cells. A novel migration assay showed a facilitating role of MSCs in BCC migration across BM endothelial cells. siRNA and ectopic expression studies showed a central role for Tac1 and secondary roles for SDF-1α and CXCR4. We also observed differences in the mechanisms between low invasive and highly metastatic cells. The in vitro studies were verified in xenogeneic mouse models that showed a preference for low invasive BCCs to BM, but comparable movement to lung and BM by highly metastatic BCCs. The expressions of Tac1 and production of SDF-1α were verified in primary BCCs from paired samples of BM aspirates and peripheral blood.

Conclusions/Significance

MSC facilitate BCC entry into BM, partly through Tac1-mediated regulation of SDF-1α and CXCR4. We propose a particular population of BCC with preference for BM could be isolated for characterization. This population might be the subset that enter BM at an early time period, and could be responsible for cancer resurgence and resistance to current therapies.

Crystallization and preliminary X-ray diffraction analysis of human IL-22 bound to the extracellular IL-22R1 chain

Interleukin-22 (IL-22) is a potent mediator of cellular inflammatory responses. Crystals of IL-22 bound to the extracellular high-affinity cell-surface receptor sIL-22R1 have been grown from polyethylene glycol solutions. Crystals suitable for X-ray diffraction analysis were only obtained with mutants of IL-22 and sIL-22R1 that removed the N-linked glycosylation sites found in the wild-type amino-acid sequences. The crystals belonged to space group P2(1), with unit-cell parameters a = 50.43, b = 76.33, c = 114.92 A, beta = 92.45 degrees , and diffracted X-rays to 3.2 A resolution. The crystallographic asymmetric unit contained two IL-22-sIL-22R1 complexes, corresponding to a solvent content of approximately 52%.

Historical developments in the research of interferon receptors

Interferons (IFNs) were discovered 50 years ago independently by Isaacs and Lindemann and by Nagata and Kojima. When it was later realized that IFNs are active at very low concentrations, research began to determine how their powerful effects were generated from such a small initial signal. It has since been established that interferons, as well as all other cytokines, employ cell surface receptors to translate their presence in the serum to a potent cellular response to a viral infection. These receptor complexes are composed of multiple distinct glycosylated transmembrane polypeptides, a number of protein tyrosine kinases, and interact transiently with a large variety of other proteins including transcription factors, phosphatases, signaling repressors, and adaptor proteins coupling the receptor to alternative signaling pathways. Three major receptor complexes exist that are exclusive to each of three major classes of interferon. Even though the effects of each major class of interferon vary physiologically, each receptor complex interacts with its ligand in similar ways and activates similar signaling cascades. In this mini-review, we take a historical perspective at the major events in the characterization of interferon receptors, discussing interesting results that still need to be explained.