A single amino acid determines the immunostimulatory activity of interleukin 10

Ciita Regulates Local and Systemic Immune Responses in a Combined rAAV-α-synuclein and Preformed Fibril-Induced Rat Model for Parkinson's Disease

Background

Parkinson's disease (PD) is characterized by alpha-synuclein (α-Syn) pathology, neurodegeneration and neuroinflammation. Human leukocyte antigen (HLA) variants associated with PD and α-Syn specific CD4+ T lymphocytes in PD patients highlight the importance of antigen presentation in PD etiology. The class II transactivator (CIITA) regulates major histocompatibility complex class II (MHCII) expression. Reduced Ciita levels significantly increase α-Syn pathology, nigrostriatal neurodegeneration and behavioral deficits in α-Syn-induced rat PD models.

Objective

Characterize immune profiles associated with enhanced PD-like pathology observed in rats expressing lower Ciita levels (DA.VRA4) compared to the background strain (DA).

Methods

To model PD, we combined rAAV-mediated α-Syn overexpression in the substantia nigra with striatal injection of α-Syn preformed fibrils. Immune profiles in brain and blood were analyzed by flow cytometry and multiplexed ELISA in naïve rats, 4- and 8 weeks post rAAV injection.

Results

Flow cytometry showed Ciita-dependent regulation of MHCII on microglia, brain macrophages and circulating myeloid cells. The MHCII-dependent microglial response was highest at 4 weeks post rAAV injection, whereas the MHCII levels in circulating myeloid cells was highest at 8 weeks. There was no major infiltration of macrophages or T lymphocytes into the CNS in response to α-Syn and only subtle Ciita- and/or α-Syn-dependent changes in the T lymphocyte compartment. Lower Ciita levels were consistently associated with higher TNF levels in serum.

Conclusions

Ciita regulates susceptibility to PD-like pathology through minor but detectable changes in resident and peripheral immune cells and TNF levels, indicating that mild immunomodulatory therapies could have therapeutic effects in PD.

Molecular and cellular factors determining the functional pleiotropy of cytokines

Cytokines are soluble factors vital for mammalian physiology. Cytokines elicit highly pleiotropic activities, characterized by their ability to induce a wide spectrum of functional responses in a diverse range of cell subsets, which makes their study very challenging. Cytokines activate signalling via receptor dimerization/oligomerization, triggering activation of the JAK (Janus kinase)/STAT (signal transducer and activator of transcription) signalling pathway. Given the strong crosstalk and shared usage of key components of cytokine signalling pathways, a long-standing question in the field pertains to how functional diversity is achieved by cytokines. Here, we discuss how biophysical - for example, ligand-receptor binding affinity and topology - and cellular - for example, receptor, JAK and STAT protein levels, endosomal compartment - parameters contribute to the modulation and diversification of cytokine responses. We review how these parameters ultimately converge into a common mechanism to fine-tune cytokine signalling that involves the control of the number of Tyr residues phosphorylated in the receptor intracellular domain upon cytokine stimulation. This results in different kinetics of STAT activation, and induction of specific gene expression programs, ensuring the generation of functional diversity by cytokines using a limited set of signalling intermediaries. We describe how these first principles of cytokine signalling have been exploited using protein engineering to design cytokine variants with more specific and less toxic responses for immunotherapy.

Individualized Dosage of Tacrolimus for Renal Transplantation Patients Based on Pharmacometabonomics

The clinical pharmacodynamics of tacrolimus in renal transplant patients has significant interindividual variability. T lymphocytes were selected to study the pharmacodynamic response of tacrolimus, which was significantly correlated with renal function and the outcome of renal transplant patients. Ultra-performance liquid chromatography-quadrupole time-of-flight mass spectroscopy (UPLC/Q-TOF-MS) was performed to obtain the metabolic profiles of 109 renal transplant patients. A partial least squares (PLS) model was constructed to screen potential biomarkers that could predict the efficacy of tacrolimus. Multinomial logistic regression analysis established a bridge that could quantify the relationship between the efficacy of tacrolimus and biomarkers. The results showed a good correlation between endogenous molecules and the efficacy of tacrolimus. Metabolites such as serum creatinine, mesobilirubinogen, L-isoleucine, 5-methoxyindoleacetate, eicosapentaenoic acid, N₂-succinoylarginine, tryptophyl-arginine, and butyric acid were indicated as candidate biomarkers. In addition, the key biomarkers could correctly predict the efficacy of tacrolimus with an accuracy of 82.5%. Finally, we explored the mechanism of individual variation by pathway analysis, which showed that amino acid metabolism was significantly related to the efficacy of tacrolimus. Moreover, orthogonal partial least squares discriminant analysis (OPLS-DA) showed that there was no difference in key metabolites among different pharmacodynamic groups at 1 month and 3 months after dose adjustment, suggesting that pharmacometabonomics is a useful tool to predict individual differences in pharmacodynamics and thus to facilitate individualized drug therapy.

Parapoxvirus Interleukin-10 Homologues Vary in Their Receptor Binding, Anti-Inflammatory, and Stimulatory Activities

Homologues of interleukin (IL)-10, a pleiotropic immunomodulatory cytokine, have been identified in the Parapoxvirus genus. The first identified, Orf virus (ORFV) IL-10, greatly enhanced infection of its host, exhibiting immune modulatory effects equivalent to human IL-10. IL-10-like genes were then identified in Bovine papular stomatitis virus (BPSV), Pseudocowpox virus (PCPV), Red deerpox virus (RDPV) and Grey sealpox virus (GSPV). This study aimed to produce and characterise recombinant parapoxvirus IL-10s, then quantitatively compare their receptor binding and immunomodulatory activities. Recombinant IL-10s were expressed, purified, then characterised using bioinformatic, biochemical and enzymatic analyses. Anti-inflammatory effects were assessed in lipoteichoic acid-activated THP-1 monocytes, and stimulatory effects in MC/9 mast cells. IL-10 receptor (IL-10R)1 binding was detected in a competitive displacement assay. BPSV IL-10 inhibited production of monocyte chemoattractant protein (MCP)-1, IL-8 and IL-1β, induced mast cell proliferation, and bound IL-10R1 similarly to ORFV IL-10. PCPV IL-10 showed reduced MCP-1 inhibition, mast cell proliferation, and IL-10R1 binding. RDPV IL-10 displayed reduced inhibition of IL-8 and MCP-1 production. GSPV IL-10 showed limited inhibition of IL-1β production and stimulation of mast cell proliferation. These findings provide valuable insight into IL-10 receptor interactions, and suggest that the parapoxvirus IL-10s play similar pathogenic roles during infection of their hosts.

Inflammation in Cerebral Venous Thrombosis

Cerebral venous thrombosis (CVT) is a rare form of cerebrovascular disease that impairs people’s wellbeing and quality of life. Inflammation is considered to play an important role in CVT initiation and progression. Several studies have reported the important role of leukocytes, proinflammatory cytokines, and adherence molecules in the CVT-related inflammatory process. Moreover, inflammatory factors exacerbate CVT-induced brain tissue injury leading to poor prognosis. Based on clinical observations, emerging evidence shows that peripheral blood inflammatory biomarkers—especially neutrophil-to-lymphocyte ratio (NLR) and lymphocyte count—are correlated with CVT [mean difference (MD) (95%CI), 0.74 (0.11, 1.38), p = 0.02 and −0.29 (−0.51, −0.06), p = 0.01, respectively]. Moreover, increased NLR and systemic immune-inflammation index (SII) portend poor patient outcomes. Evidence accumulated since the outbreak of coronavirus disease-19 (COVID-19) indicates that COVID-19 infection and COVID-19 vaccine can induce CVT through inflammatory reactions. Given the poor understanding of the association between inflammation and CVT, many conundrums remain unsolved. Further investigations are needed to elucidate the exact relationship between inflammation and CVT in the future.

Il-10 signaling reduces survival in mouse models of synucleinopathy

Parkinson's disease (PD) and related synucleinopathies are characterized by chronic neuroinflammation leading to the premise that anti-inflammatory therapies could ameliorate synucleinopathy and associated sequelae. To test this idea, we used recombinant adeno-associated viruses (AAV) to express the anti-inflammatory cytokine, Interleukin (Il)-10, in Line M83 transgenic mice that expresses the PD-associated A53T mutant human α-synuclein (αSyn). Contrary to our expectations, we observed that intraspinal Il-10 expression initiated at birth upregulated microgliosis and led to early death in homozygous M83+/+ mice. We further observed that Il-10 preconditioning led to reduced lifespan in the hemizygous M83+/- mice injected with preformed αSyn aggregates in hindlimb muscles. To determine the mechanistic basis for these adverse effects, we took advantage of the I87A variant Il-10 (vIl-10) that has predominantly immunosuppressive properties. Sustained intraspinal expression of vIl-10 in preformed αSyn-aggregate seeded M83+/- mice resulted in earlier death, accelerated αSyn pathology, pronounced microgliosis, and increased apoptosis compared to control mice. AAV-vIl-10 expression robustly induced p62 and neuronal LC3B accumulation in these mice, indicating that Il-10 signaling mediated preconditioning of the neuraxis can potentially exacerbate αSyn accumulation through autophagy dysfunction in the neurons. Together, our data demonstrate unexpected adverse effects of both Il-10 and its immunosuppressive variant, vIl-10, in a mouse model of PD, highlighting the pleiotropic functions of immune mediators and their complex role in non-cell autonomous signaling in neurodegenerative proteinopathies.

SARS-CoV-2 infection: The role of cytokines in COVID-19 disease

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A wide range of cytokines are involved in the development of COVID-19 disease.

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Some of these biomolecules are related to the progression and even to the prognosis of the infection.

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Findings on the role of cytokine storm associated with SARS-CoV-2 infection can be useful in order to manage this highly virulent disease.

COVID-19 disease, caused by infection with SARS-CoV-2, is related to a series of physiopathological mechanisms that mobilize a wide variety of biomolecules, mainly immunological in nature. In the most severe cases, the prognosis can be markedly worsened by the hyperproduction of mainly proinflammatory cytokines, such as IL-1, IL-6, IL-12, IFN-γ, and TNF-α, preferentially targeting lung tissue. This study reviews published data on alterations in the expression of different cytokines in patients with COVID-19 who require admission to an intensive care unit. Data on the implication of cytokines in this disease and their effect on outcomes will support the design of more effective approaches to the management of COVID-19.

Gut microbiota-dependent modulation of innate immunity and lymph node remodeling affects cardiac allograft outcomes

We hypothesized that the gut microbiota influences survival of murine cardiac allografts through modulation of immunity. Antibiotic pretreated mice received vascularized cardiac allografts and fecal microbiota transfer (FMT), along with tacrolimus immunosuppression. FMT source samples were from normal, pregnant (immune suppressed), or spontaneously colitic (inflammation) mice. Bifidobacterium pseudolongum (B. pseudolongum) in pregnant FMT recipients was associated with prolonged allograft survival and lower inflammation and fibrosis, while normal or colitic FMT resulted in inferior survival and worse histology. Transfer of B. pseudolongum alone resulted in reduced inflammation and fibrosis. Stimulation of DC and macrophage lines with B. pseudolongum induced the antiinflammatory cytokine IL-10 and homeostatic chemokine CCL19 but induced lesser amounts of the proinflammatory cytokines TNFα and IL-6. In contrast, LPS and Desulfovibrio desulfuricans (D. desulfuricans), more abundant in colitic FMT, induced a more inflammatory cytokine response. Analysis of mesenteric and peripheral lymph node structure showed that B. pseudolongum gavage resulted in a higher laminin α4/α5 ratio in the lymph node cortical ridge, indicative of a suppressive environment, while D. desulfuricans resulted in a lower laminin α4/α5 ratio, supportive of inflammation. Discrete gut bacterial species alter immunity and may predict graft outcomes through stimulation of myeloid cells and shifts in lymph node structure and permissiveness.

Viral manipulation of STAT3: Evade, exploit, and injure

Signal transducer and activator of transcription 3 (STAT3) is a key regulator of numerous physiological functions, including the immune response. As pathogens elicit an acute phase response with concerted activation of STAT3, they are confronted with two evolutionary options: either curtail it or employ it. This has important consequences for the host, since abnormal STAT3 function is associated with cancer development and other diseases. This review provides a comprehensive outline of how human viruses cope with STAT3-mediated inflammation and how this affects the host. Finally, we discuss STAT3 as a potential target for antiviral therapy.

IL-10: A Multifunctional Cytokine in Viral Infections

The anti-inflammatory master regulator IL-10 is critical to protect the host from tissue damage during acute phases of immune responses. This regulatory mechanism, central to T cell homeostasis, can be hijacked by viruses to evade immunity. IL-10 can be produced by virtually all immune cells, and it can also modulate the function of these cells. Understanding the effects of this multifunctional cytokine is therefore a complex task. In the present review we discuss the factors driving IL-10 production and the cellular sources of the cytokine during antiviral immune responses. We particularly focus on the IL-10 regulatory mechanisms that impact antiviral immune responses and how viruses can use this central regulatory pathway to evade immunity and establish chronic/latent infections.

Mechanisms of immunomodulation by mammalian and viral decoy receptors: insights from structures

Immune responses are regulated by effector cytokines and chemokines that signal through cell surface receptors. Mammalian decoy receptors - which are typically soluble or inactive versions of cell surface receptors or soluble protein modules termed binding proteins - modulate and antagonize signalling by canonical effector-receptor complexes. Viruses have developed a diverse array of molecular decoys to evade host immune responses; these include viral homologues of host cytokines, chemokines and chemokine receptors; variants of host receptors with new functions; and novel decoy receptors that do not have host counterparts. Over the past decade, the number of known mammalian and viral decoy receptors has increased considerably, yet a comprehensive curation of the corresponding structure-mechanism relationships has not been carried out. In this Review, we provide a comprehensive resource on this topic with a view to better understanding the roles and evolutionary relationships of mammalian and viral decoy receptors, and the opportunities for leveraging their therapeutic potential.

Cloning of interleukin-10 from African clawed frog (Xenopus tropicalis), with the Finding of IL-19/20 homologue in the IL-10 locus

Interleukin-10 (IL-10) is a pleiotropic cytokine that plays an important role in immune system. In the present study, the IL-10 gene of African clawed frog (Xenopus tropicalis) was first cloned, and its expression pattern and 3D structure were also analyzed. The frog IL-10 mRNA encoded 172 amino acids which possessed several conserved features found in IL-10s from other species, including five-exon/four-intron genomic structure, conserved four cysteine residues, IL-10 family motif, and six α-helices. Real-time PCR showed that frog IL-10 mRNA was ubiquitous expressed in all examined tissues, highly in some immune related tissues including kidney, spleen, and intestine and lowly in heart, stomach, and liver. The frog IL-10 mRNA was upregulated at 24 h after LPS stimulation, indicating that it plays a part in the host immune response to bacterial infection. Another IL, termed as IL-20, was identified from the frog IL-10 locus, which might be the homologue of mammalian IL-19/20 according to the analysis results of the phylogenetic tree and the sequence identities.

Sequence variation of Epstein-Barr virus (EBV) BCRF1 in lymphomas in non-endemic areas of nasopharyngeal carcinoma

To characterize the sequence variation and the potential implication of the Epstein-Barr virus (EBV) oncogene in lymphoma, BamHI-C fragment rightward reading frame 1 (BCRF1) was sequenced in different types of EBV-positive lymphoma in northern China, and polymorphisms were compared with previous variation data from other malignancies. The dominate subtype of BCRF1 in EBV-positive lymphoma was the B95-8 prototype, and a mutation in the signal peptide was more strongly associated with Hodgkin's lymphoma. The high conservation of BCRF1 in EBV-positive lymphoma suggests its important role in maintaining the basic biological activity and immunosuppressive functions of the virus.

Epstein-Barr virus IL-10 gene expression by a recombinant murine gammaherpesvirus in vivo enhances acute pathogenicity but does not affect latency or reactivation

Background

Many viral genes affect cytokine function within infected hosts, with interleukin 10 (IL-10) as a commonly targeted mediator. Epstein-Barr virus (EBV) encodes an IL-10 homologue (vIL-10) expressed during productive (lytic) infection and induces expression of cellular IL-10 (cIL-10) during latency. This study explored the role of vIL-10 in a murine gammaherpesvirus (MHV) model of viral infection.

Methods

The EBV vIL-10 gene was inserted into MHV-76, a strain which lacks the ability to induce cIL-10, by recombination in transfected mouse cells. Mice were infected intranasally with the recombinant, vIL-10-containing MHV-76 or control virus strains and assayed at various days post infection for lung virus titer, spleen cell number, percentage of latently infected spleen cells and ability to reactivate virus from spleen cells.

Results

Recombinant murine gammaherpesvirus expressing EBV vIL-10 rose to significantly higher titers in lungs and promoted an increase in spleen cell number in infected mice in comparison to MHV strains lacking the vIL-10 gene. However, vIL-10 expression did not alter the quantity of latent virus in the spleen or its ability to reactivate.

Conclusions

In this mouse model of gammaherpesvirus infection, EBV vIL-10 appears to influence acute-phase pathogenicity. Given that EBV and MHV wild-type strains contain other genes that induce cIL-10 expression in latency (e.g. LMP-1 and M2, respectively), vIL-10 may have evolved to serve the specific role in acute infection of enlarging the permissive host cell population, perhaps to facilitate initial survival and dissemination of viral-infected cells.

Targeting of viral interleukin-10 with an antibody fragment specific to damaged arthritic cartilage improves its therapeutic potency

INTRODUCTION

We previously demonstrated that a single-chain fragment variable (scFv) specific to collagen type II (CII) posttranslationally modified by reactive oxygen species (ROS) can be used to target anti-inflammatory therapeutics specifically to inflamed arthritic joints. The objective of the present study was to demonstrate the superior efficacy of anti-inflammatory cytokines when targeted to inflamed arthritic joints by the anti-ROS modified CII (anti-ROS-CII) scFv in a mouse model of arthritis.

METHODS

Viral interleukin-10 (vIL-10) was fused to anti-ROS-CII scFv (1-11E) with a matrix-metalloproteinase (MMP) cleavable linker to create 1-11E/vIL-10 fusion. Binding of 1-11E/vIL-10 to ROS-CII was determined by enzyme-linked immunosorbent assay (ELISA), Western blotting, and immune-staining of arthritic cartilage, whereas vIL-10 bioactivity was evaluated in vitro by using an MC-9 cell-proliferation assay. Specific in vivo localization and therapeutic efficacy of 1-11E/vIL-10 was tested in the mouse model of antigen-induced arthritis.

RESULTS

1-11E/vIL-10 bound specifically to ROS-CII and to damaged arthritic cartilage. Interestingly, the in vitro vIL-10 activity in the fusion protein was observed only after cleavage with MMP-1. When systemically administered to arthritic mice, 1-11E/vIL-10 localized specifically to the arthritic knee, with peak accumulation observed after 3 days. Moreover, 1-11E/vIL-10 reduced inflammation significantly quicker than vIL-10 fused to the control anti-hen egg lysozyme scFv (C7/vIL10).

CONCLUSIONS

Targeted delivery of anti-inflammatory cytokines potentiates their anti-arthritic action in a mouse model of arthritis. Our results further support the hypothesis that targeting biotherapeutics to arthritic joints may be extended to include anti-inflammatory cytokines that lack efficacy when administered systemically.

Immune escape of γ-herpesviruses from adaptive immunity

Epstein-Barr virus (EBV) and Kaposi's sarcoma-associated herpesvirus (KSHV) are two γ-herpesviruses identified in humans and are strongly associated with the development of malignancies. Murine γ-herpesvirus (MHV-68) is a naturally occurring rodent pathogen, representing a unique experimental model for dissecting γ-herpesvirus infection and the immune response. These γ-herpesviruses actively antagonize the innate and adaptive antiviral responses, thereby efficiently establishing latent or persistent infections and even promoting development of malignancies. In this review, we summarize immune evasion strategies of γ-herpesviruses. These include suppression of MHC-I-restricted and MHC-II-restricted antigen presentation, impairment of dendritic cell functions, downregulation of costimulatory molecules, activation of virus-specific regulatory T cells, and induction of inhibitory cytokines. There is a focus on how both γ-herpesvirus-derived and host-derived immunomodulators interfere with adaptive antiviral immunity. Understanding immune-evasive mechanisms is essential for developing future immunotherapies against EBV-driven and KSHV-driven tumors.

The molecular basis of IL-10 function: from receptor structure to the onset of signaling

Assembly of the cell surface IL-10 receptor complex is the first step in initiating IL-10 signaling pathways that regulate intestinal inflammation, viral persistence and even tumor surveillance. The discovery of IL-10 homologs in the genomes of herpes viruses suggests IL-10 signaling pathways can be manipulated at the level of the receptor complex. This chapter will describe our current molecular understanding of IL-10 receptor assembly based on crystal structures and biochemical analyses of cellular and viral IL-10 receptor complexes.

IL-10 encoded by viruses: a remarkable example of independent acquisition of a cellular gene by viruses and its subsequent evolution in the viral genome

Many viruses have evolved strategies to deregulate the host immune system. These strategies include mechanisms to subvert or recruit the host cytokine network. IL-10 is a pleiotropic cytokine that has both immunostimulatory and immunosuppressive properties. However, its key features relate mainly to its capacity to exert potent immunosuppressive effects. Several viruses have been shown to upregulate the expression of cellular IL-10 (cIL-10) with, in some cases, enhancement of infection by suppression of immune functions. Other viruses encode functional orthologues of cIL-10, called viral IL-10s (vIL-10s). The present review is devoted to these virokines. To date, vIL-10 orthologues have been reported for 12 members of the family Herpesviridae, two members of the family Alloherpesviridae and seven members of the family Poxviridae. Study of vIL-10s demonstrated several interesting aspects on the origin and the evolution of these viral genes, e.g. the existence of multiple (potentially up to nine) independent gene acquisition events at different times during evolution, viral gene acquisition resulting from recombination with cellular genomic DNA or cDNA derived from cellular mRNA and the evolution of cellular sequence in the viral genome to restrict the biological activities of the viral orthologues to those beneficial for the virus life cycle. Here, various aspects of the vIL-10s described to date are reviewed, including their genetic organization, protein structure, origin, evolution, biological properties and potential in applied research.

Secretory expression of biologically active human Herpes virus interleukin-10 analogues in Escherichia coli via a modified Sec-dependent transporter construct

Background

Interleukin-10 homologues encoded by Herpes viruses such as Epstein-Barr virus (EBV) and human cytomegalovirus (HCMV) hold interesting structural and biological characteristics compared to human interleukin-10 (hIL-10) that render these proteins promising candidates for therapeutic application in inflammatory bowel disease (IBD). Intestinal delivery of cytokines using bacterial carriers as chassis represents a novel approach for treatment of IBD patients. For proof of concept, a Sec-dependent transporter construct was designed for secretory expression of recombinant viral IL-10 proteins in the periplasm of Escherichia coli laboratory strain BL21 (DE3), which might serve as part of a prospective lysis based delivery and containment system.

Results

The signal peptide of E. coli outer membrane protein F fused to the mature form of the viral IL-10 proteins enabled successful transport into the periplasm, a compartment which seems crucial for proper assembly of the dimeric configuration of the cytokines. Cytokine concentrations in different bacterial compartments were determined by ELISA and achieved yields of 67.8 ng/ml ± 24.9 ng/ml for HCMV IL-10 and 1.5 μg/ml ± 841.4 ng/ml for EBV IL-10 in the periplasm. Immunoblot analysis was used to confirm the correct size of the E. coli-derived recombinant cytokines. Phosphorylation of signal transducer and activator of transcription 3 (STAT3) as part of the signal transduction cascade after IL-10 receptor interaction, as well as suppression of tumor necrosis factor α (TNF-α) release of lipopolysaccharide-stimulated mouse macrophages were used as read-out assays for proving in vitro biological activity of the E. coli derived, recombinant viral IL-10 counterparts.

Conclusions

In this study, proof of principle is provided that E. coli cells are a suitable chassis for secretory expression of viral IL-10 cytokines encoded by codon-optimized synthetic genes fused to the E. coli ompF signal sequence. In vitro biological activity evidenced by activation of transcription factor STAT3 and suppression of TNF-α in mammalian cell lines was shown to be strictly dependent on export of viral IL-10 proteins into the periplasmic compartment. E. coli might serve as carrier system for in situ delivery of therapeutic molecules in the gut, thus representing a further step in the development of novel approaches for treatment of IBD.

Cloning and characterization of bottlenose dolphin (Tursiops truncatus) interleukin-10

The function of cytokines in cetaceans has so far only been determined for the proinflammatory cytokines. In this study, we cloned bottlenose dolphin (Tursiops truncatus) interleukin-10 (IL-10) cDNA from concanavalin A (Con A)-stimulated peripheral blood mononuclear cells (PBMC), and investigated the mRNA expression levels in various tissues and the bioactivity of recombinant dolphin (rd) IL-10. The gene encodes a polypeptide of 178 amino acids which encompasses the mature protein sequence of 158 amino acids. Quantitative expression analysis of dolphin IL-10 revealed that the highest mRNA levels are found in the spleen. To assess its function, rdIL-10 was produced in human embryonic kidney 293 cells and its bioactivity was demonstrated through IL-10-induced inhibition of proinflammatory cytokine mRNA expression IFN-γ, TNF-α, and IL-2 of Con A-stimulated PBMC. These results indicated that the structure and function of bottlenose dolphin IL-10 is similar to that of other animals. This is the first report of the characterization of an anti-inflammatory cytokine in cetaceans.

Effects of IL-10 haplotype and atomic bomb radiation exposure on gastric cancer risk

Gastric cancer (GC) is one of the cancers that reveal increased risk of mortality and incidence in atomic bomb survivors. The incidence of gastric cancer in the Life Span Study cohort of the Radiation Effects Research Foundation (RERF) increased with radiation dose (gender-averaged excess relative risk per Gy = 0.28) and remains high more than 65 years after exposure. To assess a possible role of gene-environment interaction, we examined the dose response for gastric cancer incidence based on immunosuppression-related IL-10 genotype, in a cohort study with 200 cancer cases (93 intestinal, 96 diffuse and 11 other types) among 4,690 atomic bomb survivors participating in an immunological substudy. Using a single haplotype block composed of four haplotype-tagging SNPs (comprising the major haplotype allele IL-10-ATTA and the minor haplotype allele IL-10-GGCG, which are categorized by IL-10 polymorphisms at -819A>G and -592T>G, +1177T>C and +1589A>G), multiplicative and additive models for joint effects of radiation and this IL-10 haplotyping were examined. The IL-10 minor haplotype allele(s) was a risk factor for intestinal type gastric cancer but not for diffuse type gastric cancer. Radiation was not associated with intestinal type gastric cancer. In diffuse type gastric cancer, the haplotype-specific excess relative risk (ERR) for radiation was statistically significant only in the major homozygote category of IL-10 (ERR = 0.46/Gy, P = 0.037), whereas estimated ERR for radiation with the minor IL-10 homozygotes was close to 0 and nonsignificant. Thus, the minor IL-10 haplotype might act to reduce the radiation related risk of diffuse-type gastric cancer. The results suggest that this IL-10 haplotyping might be involved in development of radiation-associated gastric cancer of the diffuse type, and that IL-10 haplotypes may explain individual differences in the radiation-related risk of gastric cancer.

Subversion of cytokine networks by virally encoded decoy receptors

During the course of evolution, viruses have captured or created a diverse array of open reading frames, which encode for proteins that serve to evade and sabotage the host innate and adaptive immune responses that would otherwise lead to their elimination. These viral genomes are some of the best textbooks of immunology ever written. The established arsenal of immunomodulatory proteins encoded by viruses is large and growing, and includes specificities for virtually all known inflammatory pathways and targets. The focus of this review is on herpes and poxvirus-encoded cytokine and chemokine-binding proteins that serve to undermine the coordination of host immune surveillance. Structural and mechanistic studies of these decoy receptors have provided a wealth of information, not only about viral pathogenesis but also about the inner workings of cytokine signaling networks.

Improving health from the inside: Use of engineered intestinal microorganisms as in situ cytokine delivery system

The anti-inflammatory cytokine interleukin-10 and its viral homologs were chosen as model proteins for the development of drug delivery systems based on probiotic carriers like E. coli Nissle 1917, E. coli G3/10, and Saccharomyces boulardii. Exterior cytokine secretion was achieved by a modified E. coli hemolysin transporter. Release of interleukin-10 transported to the periplasm via the OmpF signal peptide was enabled by a T4 phage lysis system under control of the araC PBAD activator-promoter. The yield of interleukin-10 delivered by the phage lysis system was too low for functional analysis whereas the fusion protein secreted by the hemolysin transporter proved to be biologically inactive. Moreover, partial processing of the fusion protein by the E. coli membrane protease OmpT had no effect on the protein’s functionality. Using the α-mating factor signal sequence, the yeast S. boulardii proved to be suitable for secretory expression of biologically active viral interleukin-10.

Koi herpesvirus encodes and expresses a functional interleukin-10

Koi herpesvirus (KHV) (species Cyprinid herpesvirus 3) ORF134 was shown to transcribe a spliced transcript encoding a 179-amino-acid (aa) interleukin-10 (IL-10) homolog (khvIL-10) in koi fin (KF-1) cells. Pairwise sequence alignment indicated that the expressed product shares 25% identity with carp IL-10, 22 to 24% identity with mammalian (including primate) IL-10s, and 19.1% identity with European eel herpesvirus IL-10 (ahvIL-10). In phylogenetic analyses, khvIL-10 fell in a divergent position from all host IL-10 sequences, indicating extensive structural divergence following capture from the host. In KHV-infected fish, khvIL-10 transcripts were observed to be highly expressed during the acute and reactivation phases but to be expressed at very low levels during low-temperature-induced persistence. Similarly, KHV early (helicase [Hel] and DNA polymerase [DNAP]) and late (intercapsomeric triplex protein [ITP] and major capsid protein [MCP]) genes were also expressed at high levels during the acute and reactivation phases, but only low-level expression of the ITP gene was detected during the persistent phase. Injection of khvIL-10 mRNA into zebrafish (Danio rerio) embryos increased the number of lysozyme-positive cells to a similar degree as zebrafish IL-10. Downregulation of the IL-10 receptor long chain (IL-10R1) using a specific morpholino abrogated the response to both khvIL-10 and zebrafish IL-10 transcripts, indicating that, despite the structural divergence, khvIL-10 functions via this receptor. This is the first report describing the characteristics of a functional viral IL-10 gene in the Alloherpesviridae.

Herpesvirus exploitation of host immune inhibitory pathways

Herpesviruses employ a plethora of mechanisms to circumvent clearance by host immune responses. A key feature of mammalian immune systems is the employment of regulatory pathways that limit immune responsiveness. The primary functions of these mechanisms are to control autoimmunity and limit exuberant responses to harmless antigen in mucosal surfaces. However, such pathways can be exploited by viral pathogens to enable acute infection, persistence and dissemination. Herein, we outline the current understanding of inhibitory pathways in modulating antiviral immunity during herpesvirus infections in vivo and discuss strategies employed by herpesviruses to exploit these pathways to limit host antiviral immunity.

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.

Adenovirus-mediated viral interleukin-10 gene transfer prevents concanavalin A-induced liver injury

BACKGROUND AND AIM

Liver injury is closely associated with immune inflammation. Lacking immunostimulatory functions, viral interleukin-10 (vIL-10), a cellular IL-10 homologue, has been an attractive molecule for immunomodulatory therapy. We aimed to reveal a protective effect of the gene transfer of an adenoviral vector encoding vIL-10 on liver injury induced by concanavalin A.

METHODS

C57BL/6J mice were intravenously injected with adenoviral vector encoding vIL-10 before concanavalin A challenge. Liver injury was assessed. Interferon-γ and interleukin-4 levels were measured by ELISA. The activation of splenic and hepatic immune cells was analysed using an MTT assay.

RESULTS

Adenoviral vector encoding vIL-10 pretreatment significantly decreased concanavalin A-mediated elevations in serum alanine aminotransaminase and aspartate aminotransaminase activity, and necrotic area in liver tissues. The protective effect of adenoviral vector encoding vIL-10 was attributed to its inhibition of T cell activation, and production of interferon-γ and interleukin-4 by the immune cells. Recombinant mouse IL-10, a high homologous cytokine to vIL-10, effectively downregulated interferon-γ and interleukin-4 release by hepatic mononuclear cells.

CONCLUSION

Adenovirus vector-mediated vIL-10 gene transfer can prevent concanavalin A-induced hepatic injury, minimise pro-inflammatory cytokine release, and inhibit the activation of T lymphocytes.

Cytokine homologs of human gammaherpesviruses

Gammaherpesviruses such as Epstein-Barr virus (EBV, human herpesvirus 4) and Kaposi sarcoma-associated herpesvirus (KSHV, human herpesvirus 8) establish lifelong infection in the host. To further this lifestyle, they encode homologs of cellular cytokines and cytokine receptors with the overarching goal to escape from or to blunt host antiviral defenses. EBV encodes mimics of human interleukin (hIL)-10 and a G protein-coupled receptor protein with sequence similarity to CXCR, whereas KSHV encodes homologs of hIL-6, 3 CC chemokine ligands, and a G protein-coupled receptor with sequence similarity to IL8 receptor alpha. This review focuses on the EBV IL-10 homolog and the KSHV IL-6 homolog with respect to virus biology and pathogenesis of the virus-associated diseases.

Conservation and mutation of viral interleukin-10 gene in gastric carcinomas and nasopharyngeal carcinomas

The Epstein-Barr virus (EBV) BamHI-C fragment rightward reading frame 1 (BCRF1)-coded viral interleukin-10 (vIL-10), exhibits high homology with human interleukin-10 (hIL-10) gene. The protein product vIL-10, which shares some functional properties with hIL-10, primarily mediates immunosuppressive functions. To characterize the variations of the vIL-10 gene and to explore the association between vIL-10 gene variations and EBV associated diseases, the vIL-10 gene was analyzed (using direct sequencing) in 41 cases of EBV-associated gastric carcinoma (EBVaGC), 83 nasopharyngeal carcinoma biopsies, and 40 throat washing samples from healthy donors in Northern China. One silent mutation (c9980a) was observed in the majority of EBVaGC, nasopharyngeal carcinoma and throat washing samples (134/164, 81.7%). Two consensus mutations (V6M and G23S) were identified in the signal peptide region in some nasopharyngeal carcinoma and throat washing isolates. These results indicate that the pattern B95-8 (identical sequence to B95-8) is the dominant type among the EBV isolates from Northern China, while the pattern SPM (mutation in the signal peptide present only in nasopharyngeal carcinoma and throat washing isolates) seems more relevant with the EBV-positive nasopharyngeal and laryngopharyngeal epithelial cells. The conservation of vIL-10, with a few variations, suggests the critical role of the vIL-10 gene for EBV in gaining an advantage over the host's immune system.

Reduced tumorigenesis of EG7 after interleukin-10 gene transfer and enhanced efficacy in combination with intratumorally injection of adenovirus-mediated lymphotactin and the underlying mechanism

Although interleukin-10 (IL-10) is commonly regarded as an immunosuppressive cytokine, a wealth of evidence is accumulating that IL-10 also possesses some immunostimulating antitumor properties. Previous studies demonstrated that forced expression of the IL-10 gene in tumor cells could unexpectedly produce antitumor effects. In this study, we explored the tumorigenesis of EG7 cells transduced with IL-10 gene. In vivo, IL-10 gene transfer reduced tumorigenic capacity of EG7 cells and prolonged survival of the EG7 tumor-bearing mice. It was found that the cytotoxicities of cytotoxic T lymphocytes (CTL) and natural killer cells (NK cells) were enhanced. Assessment of the immune status of the animals showed prevalence of a systemic and tumor-specific Th2 response (high levels of IL-4 and IL-10). To improve the therapeutic efficacy, we combined with intratumoral injection of adenovirus-mediated lymphotactin (Ad-Lptn) into the overestablished EG7 tumor model. More significant inhibition of tumor growth were observed in EG7 tumor-bearing mice that received combined treatment with IL-10 and Lptn gene than those of mice treated with IL-10 or Lptn gene alone. The highest NK cells and CTL activity was induced in the combined therapy group, increasing the production of IL-2 and interferon-γ (IFN-γ) significantly but decreasing the expression of immune suppressive cells (CD4(+)Foxp3(+) Treg cells and Gr1(+)CD11b(+) MDSCs). The necrosis of tumor cells was markedly observed in the tumor tissues, accompanying with strongest expression of Mig (monokine induced by interferon-gamma) and IP-10 (interferon-inducible protein 10), weakest expression of vascular endothelial growth factor (VEGF) and matrix metalloproteinases-2 (MMP-2). In vivo, depletion analysis demonstrated that CD8(+) T cells and NK cells were the predominant effector cell subset responsible for the antitumor effect of IL-10 or Lptn gene. These findings may provide a potential strategy to improve the antitumor efficacy of IL-10 and Lptn.

Rapamycin generates graft-homing murine suppressor CD8(+) T cells that confer donor-specific graft protection

It has been reported that rapamycin (RPM) can induce de novo conversion of the conventional CD4(+)Foxp3(-) T cells into CD4(+)Foxp3(+) regulatory T cells (iTregs) in transplantation setting. It is not clear whether RPM can similarly generate suppressor CD8(+) T cells to facilitate graft acceptance. In this study, we investigated the ability of short-term RPM treatment in promoting long-term acceptance (LTA) of MHC-mismatched skin allografts by generating a CD8(+) suppressor T-cell population. We found that CD4 knockout (KO) mice (in C57BL/6 background, H-2(b)) can promptly reject DBA/2 (H-2(d)) skin allografts with mean survival time (MST) being 13 days (p < 0.01). However, a short course RPM treatment in these animals induced LTA with graft MST longer than 100 days. Adoptive transfer of CD8(+) T cells from LTA group into recombination-activating gene 1 (Rag-1)-deficient mice provided donor-specific protection of DBA/2 skin grafts against cotransferred conventional CD8(+) T cells. Functionally active immunoregulatory CD8(+) T cells also resided in donor skin allografts. Eighteen percent of CD8(+) suppressor T cells expressed CD28 as measured by flow cytometry, and produced reduced levels of IFN-γ, IL-2, and IL-10 in comparison to CD8(+) effector T cells as measured by ELISA. It is unlikely that CD8(+) suppressor T cells mediated graft protection via IL-10, as IL-10/Fc fusion protein impaired RPM-induced LTA in CD4 KO mice. Our data supported the notion that RPM-induced suppressor CD8(+) T cells home to the allograft and exert donor-specific graft protection.

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.

IL-10 secretion increases signal persistence of HEMA-MMA-microencapsulated luciferase-modified CHO fibroblasts in mice

Microencapsulation of cells in a polymer membrane [e.g., poly(hydroxyethyl methacrylate-co-methyl methacrylate) (HEMA-MMA)] has been proposed as a vehicle for the delivery of therapeutic biomolecules, but cells (especially xenogeneic cells) survive only for short times, limiting the utility of this approach. Murine interleukin-10 (mIL-10) has been shown to downregulate the xenogeneic immune response, and we tested the hypothesis that mIL-10 produced by microencapsulated Chinese hamster ovary (CHO) cells would modulate the transplant-site environment leading to prolonged cell function in a xenogeneic model without other immunomodulatory agents. Prior to encapsulation, CHO cells were genetically engineered to express mIL-10 and a firefly bioluminescence protein, luciferase, which allowed for noninvasive tracking of transplanted cells in vivo with the Xenogen IVIS Imaging System. This nondestructive imaging system was sufficiently sensitive to detect photon signal emitted by a single capsule containing around 800 luciferase-transduced CHO (CHO(LUC)) cells in vitro, and to track changes in luciferase expression in vivo over time. Effective modulation of the transplantation-site environment with mIL-10 secreted from capsules was evident by greater luciferase expression at 10 and 21 days after transplantation relative to encapsulated luciferase-transfected cells that did not produce mIL-10. Longer duration effects require further investigation to extend this proof-of-concept study.

Viral and murine interleukin-10 are correctly processed and retain their biological activity when produced in tobacco

BACKGROUND

Interleukin-10 (IL-10) is a potent anti-inflammatory cytokine, with therapeutic applications in several autoimmune and inflammatory diseases. Oral administration of this cytokine alone, or in combination with disease-associated autoantigens could confer protection form the onset of a specific autoimmune disease through the induction of oral tolerance. Transgenic plants are attractive systems for production of therapeutic proteins because of the ability to do large scale-up at low cost, and the low maintenance requirements. They are highly amenable to oral administration and could become effective delivery systems without extensive protein purification. We investigated the ability of tobacco plants to produce high levels of biologically-active viral and murine IL-10.

RESULTS

Three different subcellular targeting strategies were assessed in transient expression experiments, and stable transgenic tobacco plants were generated with the constructs that yielded the highest accumulation levels by targeting the recombinant proteins to the endoplasmic reticulum. The best yields using this strategy in T1 plants were 10.8 and 37.0 microg/g fresh leaf weight for viral and murine IL-10, respectively. The recombinant proteins were purified from transgenic leaf material and characterized in terms of their N-glycan composition, dimerization and biological activity in in vitro assays. Both molecules formed stable dimers, were able to activate the IL-10 signaling pathway and to induce specific anti-inflammatory responses in mouse J774 macrophage cells.

CONCLUSION

Tobacco plants are able to correctly process viral and murine IL-10 into biologically active dimers, therefore representing a suitable platform for the production for these cytokines. The accumulation levels obtained are high enough to allow delivery of an immunologically relevant dose of IL-10 in a reasonable amount of leaf material, without extensive purification. This study paves the way to performing feeding studies in mouse models of autoimmune diseases, that will allow the evaluation the immunomodulatory properties and effectiveness of the viral IL-10 in inducing oral tolerance compared to the murine protein.

A captured viral interleukin 10 gene with cellular exon structure

We have characterized a novel, captured and fully functional viral interleukin (IL)-10 homologue ((OvHV)IL-10) from the gammaherpesvirus ovine herpesvirus 2. Unlike IL-10 homologues from other gammaherpesviruses, the (OvHV)IL-10 peptide sequence was highly divergent from that of the host species. The (OvHV)IL-10 gene is unique amongst virus captured genes in that it has precisely retained the original cellular exon structure, having five exons of similar sizes to the cellular counterparts. However, the sizes of the introns are dramatically reduced. The (OvHV)IL-10 protein was shown to be a non-glycosylated, secreted protein of M(r) 21 000 with a signal peptidase cleavage site between amino acids 26 and 27 of the nascent peptide. Functional assays showed that (OvHV)IL-10, in a similar way to ovine IL-10, stimulated mast cell proliferation and inhibited macrophage inflammatory chemokine production. This is the first example of a captured herpesvirus gene retaining the full cellular gene structure.

Epstein-Barr virus evasion of CD8(+) and CD4(+) T cell immunity via concerted actions of multiple gene products

Upon primary infection, EBV establishes a latent infection in B cells, characterized by maintenance of the viral genome in the absence of viral replication. The Epstein-Barr Nuclear Antigen 1 (EBNA1) plays a crucial role in maintenance of the viral DNA episome and is consistently expressed in all EBV-associated malignancies. Compared to other EBV latent gene products, EBNA1 is poorly recognized by CD8(+) T lymphocytes. Recent studies are discussed that shed new light on the mechanisms that underlie this unusual lack of CD8(+) T cell activation. Whereas the latent phase is characterized by the expression of a limited subset of viral gene products, the full repertoire of over 80 EBV lytic gene products is expressed during the replicative phase. Despite this abundance of potential T cell antigens, which indeed give rise to a strong response of CD4(+) and CD8(+) T lymphocytes, the virus can replicate successfully. Evidence is accumulating that this paradoxical situation is the result of actions of multiple viral gene products, inhibiting discrete stages of the MHC class I and class II antigen presentation pathways. Immediately after initiation of the lytic cycle, BNLF2a prevents peptide-loading of MHC class I molecules through inhibition of the Transporter associated with Antigen Processing, TAP. This will reduce presentation of viral antigens by the large ER-resident pool of MHC class I molecules. Synthesis of new MHC class I molecules is blocked by BGLF5. Viral-IL10 causes a reduction in mRNA levels of TAP1 and bli/LMP2, a subunit of the immunoproteasome. MHC class I molecules present at the cell surface are downregulated by BILF1. Also the antigen presenting capacity of MHC class II molecules is severely compromised by multiple EBV lytic gene products, including gp42/gH/gL, BGLF5, and vIL-10. In this review, we discuss how concerted actions of these EBV lytic proteins result in highly effective interference with CD8(+) and CD4(+) T cell surveillance, thereby providing the virus with a window for undisturbed generation of viral progeny.

Therapeutics targeting tumor immune escape: towards the development of new generation anticancer vaccines

Despite the evidence that immune effectors can play a significant role in controlling tumor growth under natural conditions or in response to therapeutic manipulation, it is clear that malignant cells evade immune surveillance in most cases. Considering that anticancer vaccination has reached a plateau of results and currently no vaccination regimen is indicated as a standard anticancer therapy, the dissection of the molecular events underlying tumor immune escape is the necessary condition to make anticancer vaccines a therapeutic weapon effective enough to be implemented in the routine clinical setting. Recent years have witnessed significant advances in our understanding of the molecular mechanisms underlying tumor immune escape. These mechanistic insights are fostering the development of rationally designed therapeutics aimed at reverting the immunosuppressive circuits that undermine an effective antitumor immune response. In this review, the best characterized mechanisms that allow cancer cells to evade immune surveillance are overviewed and the most debated controversies constellating this complex field are highlighted. In addition, the latest therapeutic strategies devised to overcome tumor immune escape are described, with special regard to those entering clinical phase investigation.

Ex vivo gene transfer of viral interleukin-10 to BB rat islets: no protection after transplantation to diabetic BB rats

Allogeneic and autoimmune islet destruction limits the success of islet transplantation in autoimmune diabetic patients. This study was designed to investigate whether ex vivo gene transfer of viral interleukin-10 (vIL-10) protects BioBreeding (BB) rat islets from autoimmune destruction after transplantation into diabetic BB recipients. Islets were transduced with adenoviral constructs (Ad) expressing the enhanced green fluorescent protein (eGFP), α-1 antitrypsin (AAT) or vIL-10. Transduction efficiency was demonstrated by eGFP-positive cells and vIL-10 production. Islet function was determined in vitro by measuring insulin content and insulin secretion and in vivo by grafting AdvIL-10-transduced islets into syngeneic streptozotocin (SZ)-diabetic, congenic Lewis (LEW.1 W) rats. Finally, gene-modified BB rat islets were grafted into autoimmune diabetic BB rats. Ad-transduction efficiency of islets increased with virus titre and did not interfere with insulin content and insulin secretion. Ad-transduction did not induce Fas on islet cells. AdvIL-10-transduced LEW.1 W rat islets survived permanently in SZ-diabetic LEW.1 W rats. In diabetic BB rats AdvIL-10-transduced BB rat islets were rapidly destroyed. Prolongation of islet culture prior to transplantation improved the survival of gene-modified islets in BB rats. Several genes including those coding for chemokines and other peptides associated with inflammation were down-regulated in islets after prolonged culture, possibly contributing to improved islet graft function in vivo. Islets transduced ex vivo with vIL-10 are principally able to cure SZ-diabetic rats. Autoimmune islet destruction in diabetic BB rats is not prevented by ex vivo vIL-10 gene transfer to grafted islets. Graft survival in autoimmune diabetic rats may be enhanced by improvements in culture conditions prior to transplantation.

Perfluorochemical (PFC) liquid enhances recombinant adenovirus vector-mediated viral interleukin-10 (AdvIL-10) expression in rodent lung

Adenovirus and cationic liposome mediated transfer of Interleukin-10 (IL-10), a potent anti-inflammatory cytokine, has been shown to decrease pro-inflammatory cytokine levels and overall lung inflammation in models of lung transplantation and injury. Limitations to current approaches of IL-10 gene therapy include poor vector delivery methods and pro-inflammatory properties of human IL-10 under certain conditions. We hypothesize that using perfluorochemical (PFC) liquid to deliver the highly homologous viral IL-10 (vIL-10), which is predominantly anti-inflammatory with minimal pro-inflammatory activities, can potentially be a more effective strategy to combat inflammatory lung diseases. In this study, we compare the use of PFC liquid versus aerosolized method to deliver adenovirus encoding the vIL-10 gene (AdvIL-10) in C57Bl6 mice. Detectable vIL-10 levels were measured from bronchoalveolar lavage fluid and lung homogenates at one, four, ten and thirty days after AdvIL-10. Furthermore, we determined if use of PFC liquid could allow for the use of a lower dose of AdvIL-10 by comparing the levels of detectable vIL-10 at different doses of AdvIL-10 delivered +/- PFC liquid. Results showed that PFC liquid enhanced detectable vIL-10 by up to ten fold and that PFC liquid allowed the use of ten-fold less vector. PFC liquid increased detectable vIL-10 in lung homogenates at all time points; however, the increase in detectable vIL-10 in BAL fluid peaked at four days and was no longer evident by thirty days after intratracheal instillation. In summary, this is the first report utilizing PFC liquid to enhance the delivery of a potentially therapeutic molecule, vIL-10. We believe this strategy can be used to perform future studies on the use of the predominantly anti-inflammatory vIL-10 to treat inflammatory lung diseases.

Epstein-Barr virus: evasive maneuvers in the development of PTLD

Epstein-Barr virus (EBV) infection is linked to approximately 90% of B-cell lymphomas associated with posttransplant lymphoproliferative disease (PTLD), a serious complication for immunosuppressed transplant recipients. In this paper, we review the myriad ways by which EBV can inadvertently drive the genesis and persistence of B-cell lymphomas, particularly when the antiviral immune response is compromised. Probing the basic mechanisms by which EBV infection proceeds and contributes to malignancy in such cases will hopefully improve our understanding and treatment of PTLD and other EBV-associated malignancies.

Identification and characterization of a +1 frameshift observed during the expression of Epstein-Barr virus IL-10 in Escherichia coli

Epstein-Barr virus IL-10 (ebvIL-10) mimics the biological functions of cellular IL-10 including a number of immunoinhibitory activities on diverse immune cells. Characterization of ebvIL-10 and several mutants, expressed in Escherichia coli, by gel filtration chromatography and mass spectrometry revealed a +1 frameshift upon ebvIL-10 expression. The frameshift is caused by the rare AGG codon at ebvIL-10 Arg159, which is followed by the most inefficient stop signal, UGAC. The frameshift was corrected by substituting the rare AGG codon with an abundant arginine codon, CGU, or by enhancing the level of tRNA that decodes the AGG codon. As a result, ebvIL-10 expression levels increased by approximately 3-fold and the purity of the protein improved from 85-95% to 98-99%. The correction of the frameshift has been essential for continuing structural and biophysical studies of ebvIL-10.

Effects of local and systemic viral interleukin-10 gene transfer on corneal allograft survival

In this study, we explored the immunomodulatory effects of viral interleukin (IL) IL-10 after ex vivo and in vivo gene transfer in experimental corneal transplantation. Wistar-Furth rats were used as donors and major histocompatibility complex class I/II-disparate Lewis rats served as recipients. For ex vivo gene therapy donor corneas were either transfected with liposome/vIL-10 plasmid DNA mixtures or transduced with a vIL-10 expressing adenovirus vector (AdvIL-10). For in vivo studies, recipients were treated with AdvIL-10 intraperitoneally 1 day before transplantation. Graft survival was analysed using the Kaplan-Meier survival method. To monitor the efficacy of the therapy messenger RNA (mRNA) cytokine expression profiles in grafts and draining lymph nodes were analysed by quantitative real-time reverse transcription-polymerase chain reaction. Moreover, anti-adenovirus immunity was also investigated. Neither ex vivo liposome-mediated vIL-10 gene transfer nor ex vivo AdvIL-10 gene transfer led to prolonged corneal allograft survival. In contrast, corneal allograft survival was significantly prolonged in animals receiving systemic AdvIL-10 gene transfer. Moreover, only systemic vIL-10 gene therapy modulated the cytokine mRNA expression profile in draining lymph nodes. Interestingly, systemic AdvIL-10 gene transfer could not inhibit the generation of anti-adenovirus antibodies. Our data indicate systemic expression of the vIL-10 gene is required to modulate the cytokine expression profile in the draining lymph nodes, which might be a pre-requisite for the success of cytokine gene therapy.

Molecular characterization, 3D modelling and expression analysis of sea bass (Dicentrarchus labrax L.) interleukin-10

Interleukin-10 (IL-10) is a pleiotropic cytokine generally known for its relevance in the resolution of inflammation, but that also has immunostimulatory properties. Here is described the isolation and characterization of the sea bass IL-10 (sbIL-10) cDNA and gene. The sbIL-10 gene encodes a 187 amino acid protein and comprises a five exon-four intron structure as other known IL-10 genes. Important structural residues are maintained in the sbIL-10 protein, including the four cysteines responsible for the two intra-chain disulfide bridges reported for human IL-10. The 3D structure of sbIL-10 was predicted. This first homology model of a fish IL-10 reveals a high degree of compatibility between the dimeric quaternary architectures of sbIL-10 and its mammalian counterparts. The phylogenetic analysis clusters sbIL-10 with other IL-10s, apart from IL-10-related molecules. The involvement of IL-10 in sea bass immune responses was demonstrated by investigating the expression profiles of IL-1beta and IL-10 in the head-kidney and spleen following intraperitoneal injection of UV-killed Photobacterium damselae ssp. piscicida. Furthermore, involvement of IL-10 in the resolution of inflammation is for the first time suggested in fish, due to the delayed maximal mRNA levels of sbIL-10 compared to those of the pro-inflammatory IL-1beta.

Comparative assessment of Th1 and Th2 cytokines of swamp type buffalo and other bubaline breeds by molecular cloning, sequencing and phylogenetics

Comparative assessment of Th1 and Th2 cytokines of three bubaline breeds namely swamp buffalo, its crossbreed with riverine buffalo (CB), and the improved breed of Bulgarian Murrah buffalo (BMB), was done by molecular cloning, sequencing and phylogenetic analysis. The Th1 cytokines analyzed included IL-2, IL-12p35, IL-12p40, and IFN-gamma while Th2 cytokines included IL-4 and IL-10. Both groups showed strict conservation in the putative secondary structures and amino acid residues within the tribe Bovini, which indicated functional cross-reactivity. Nucleotide sequence homology ranged from 98.6 to 100.0% and was lowest for IL-12p35. With regard to amino acid sequence, the lowest homology was observed in IL-4 with 97.8%. This substitution was mainly due to differences in mRNA splicing. The phylogenetic relationship of the buffalo breeds was analyzed and showed them as a cluster comprised mainly of species belonging to the order Artiodactyla, including cattle and pigs. A deeper knowledge of these cytokine structures will favor understanding of water buffalo immunology and how much it differs from its closest subspecies and other animals.

Pathogen-derived immunomodulatory molecules: future immunotherapeutics?

The identification of molecules from various pathogens that modulate innate and/or adaptive immunity is a dynamic and rapidly developing area of research. These immunomodulatory molecules (IM) have been optimized during pathogen-host co-evolution, and have a potential application as novel immunotherapeutics. In this review, we illustrate the use of pathogen IM that have been produced as recombinant proteins, with different modes of modulatory activity, and discuss their potential to modulate undesirable immune responses in human diseases.