The evolution of the type I interferons

Links between innate and adaptive immunity via type I interferon

Type I interferon (IFN-alpha/beta) is expressed rapidly following exposure to a wide variety of infectious agents and plays a key role in innate control of virus replication. Recent studies have demonstrated that dendritic cells both produce IFN-alpha/beta and undergo maturation in response to IFN-alpha/beta. Moreover, IFN-alpha/beta has been shown to potently enhance immune responses in vivo through the stimulation of dendritic cells. These findings indicate that IFN-alpha/beta serves as a signal linking innate and adaptive immunity.

Selective expression of type I IFN genes in human dendritic cells infected with Mycobacterium tuberculosis

Type I IFN regulates different aspects of the immune response, inducing a cell-mediated immunity. We have recently shown that the infection of dendritic cells (DC) with Mycobacterium tuberculosis (Mtb) induces IFN-alpha. In this work we have monitored a rapid induction of IFN-beta followed by the delayed production of the IFN-alpha1 and/or -alpha13 subtypes. The Mtb infection rapidly activates the NF-kappaB complex and stimulates the phosphorylation of IFN regulatory factor (IRF)-3, events known to induce IFN-beta expression in viral infection. In turn, the autocrine production of IFN-beta induces the IFN-stimulated genes that contain binding sites for activated STATs in their promoters. Among the IFN-stimulated genes induced in DC through STAT activation are IRF-1 and IRF-7. The expression of IRF-1 appears to be dependent on the sequential activation of NF-kappaB and STAT-1. Once expressed, IRF-1 may further stimulate the transcription of IFN-beta. Induction of IRF-7 is also regulated at the transcriptional level through the binding of phosphorylated STAT-1 and STAT-2, forming the IFN-stimulated gene factor-3 complex. In turn, the IRF-1 and IRF-7 expression appears to be required for the delayed induction of the IFN-alpha1/13 genes. Although correlative, our results strongly support the existence of a cascade of molecular events in Mtb-infected DC. Upon infection, constitutively expressed NF-kappaB and IRF-3 are activated and likely contribute to the rapid IFN-beta expression. In turn, IFN-beta-induced IRF-1 and IRF-7 may cooperate toward induction of IFN-alpha1/13 if infection persists and these factors are activated.

Biological assays for interferons

Interferons (IFN) are potent biologically active proteins synthesised and secreted by somatic cells of all mammalian species. They have been well characterised, especially those of human origin, with respect to structure, biological activities, and clinical therapeutic effects. While structural differences are known to exist among the IFN species that constitute the "IFN family" and despite the existence of different receptors for type I and type II IFN, all species have been shown to exert a similar spectrum of in vitro biological activities in responsive cells. Principal among the biological activities induced by IFN is antiviral activity, the activity used to originally define IFN. Antiviral activity of IFN is mediated via cell receptors and is dependent on the activation of signalling pathways, the expression of specific gene products, and the development of antiviral mechanisms. Sensitivity of cells to IFN-mediated antiviral activity is variable, and depends on a number of factors including cell type, expression of IFN receptors and downstream effector response elements, effectiveness of antiviral mechanisms, and the type of virus used to infect cells. Nevertheless, by the judicious use of sensitive cell lines in combination with appropriate cytopathic viruses, effective assays to measure the antiviral activity have been developed. Historically, "antiviral assays" (AVA) were the first type of biological assays that were developed to measure the relative activity or potency of IFN preparations. However, the subsequent discoveries of several other biological activities of IFN has opened the way to the development of assays based on one or other of these activities. The latter include inhibition of cell proliferation, regulation of functional cellular activities, regulation of cellular differentiation and immunomodulation. More recently, the cloning of IFN responsive genes has led to the development of "reporter gene assays". In this case, the promoter region of IFN responsive genes is linked with a heterologous reporter gene, for example, firefly luciferase or alkaline phosphatase, and transfected into an IFN-sensitive cell line. Stably transfected cell lines exposed to IFN increase expression of the reporter gene product in direct relation to the dose of IFN, the readout being a measure of this product's enzymic action. The current review aims to give a critical overview of the development, specificity, standardisation and present use of the various biological assay methods now available for the quantification of IFN activity.

Induction of blood 2',5'-oligoadenylate synthetase activity in mice by gastric administration of ovine IFN-tau

Interferon-tau (IFN-tau) is a member of the type I IFN family. Although its distribution is restricted to ruminants, IFN-tau is active against cells of humans and mice. It has been reported that oral administration of ovine IFN-tau (OvIFN-tau) prevents both acute and chronic relapsing forms of murine experimental allergic encephalomyelitis (EAE). Here, we examined the effect in mice of peroral gastric administration of OvIFN-tau on the induction of 2',5'-oligoadenylate synthetase (OAS) activity in whole blood. Before administration, mice were deprived of food and drink for 6 h, and IFN was given by either intraperitoneal (i.p.) injection or per-oral gastric administration. When administered gastrically, IFN was introduced directly into the upper part of the stomach using an oral feeding needle. OAS activity in whole blood increased dependent on dose (0-105 U) and time (0-24 h), with no significant difference in the level of activity between the two routes. An increase in the activity of OAS in blood following administration of OvIFN-tau was observed in ICR, BALB/c, C57BL/6, NZW/N, and SJL/J mice, although the extent of the increase varied with the strain. Blood OAS levels also increased on administration of murine IFN-alpha (MuIFN-alpha). However, higher levels were detected after i.p. injection than after gastric administration.

Comparison of gene expression patterns induced by treatment of human umbilical vein endothelial cells with IFN-alpha 2b vs. IFN-beta 1a: understanding the functional relationship between distinct type I interferons that act through a common receptor

We analyzed whether interferon-alpha 2b (IFN-alpha 2b) and IFN-beta 1a engage their common receptor to generate activated receptor complexes possessing distinct signaling properties. Human vascular endothelial cells (HUVEC) are 100-1000-fold more sensitive to IFN-beta 1a than to IFN-alpha 2b in in vitro assays. An nonarray-based expression profiling (GeneCalling) technology was employed to compare the patterns and levels of gene expression induced by these IFN as the broadest means by which signaling events could be measured. To distinguish subtype-related differences from dose-related effects, RNA was prepared from HUVEC treated with 50-5000 pg/ml of each IFN. The results showed that at 50 pg/ml IFN, only a subset of the genes induced by IFN-beta 1a were also induced by IFN-alpha 2b and that individual genes were induced to higher levels by IFN-beta 1a. In contrast, at 5000 pg/ml, both subtypes induced essentially identical sets of genes to similar levels of expression. No genes were seen to be induced uniquely by IFN-alpha 2b but not by IFN-beta 1a. The results show that the two IFN are intrinsically capable of inducing similar gene induction responses and do not provide evidence that they generate activated receptor complexes possessing distinct signaling properties. In contrast, the two IFN generate gene induction patterns that are both qualitatively and quantitatively distinct at subsaturating and potentially physiologically more relevant concentrations.

Biology of mammalian L1 retrotransposons

L1 retrotransposons comprise 17% of the human genome. Although most L1s are inactive, some elements remain capable of retrotransposition. L1 elements have a long evolutionary history dating to the beginnings of eukaryotic existence. Although many aspects of their retrotransposition mechanism remain poorly understood, they likely integrate into genomic DNA by a process called target primed reverse transcription. L1s have shaped mammalian genomes through a number of mechanisms. First, they have greatly expanded the genome both by their own retrotransposition and by providing the machinery necessary for the retrotransposition of other mobile elements, such as Alus. Second, they have shuffled non-L1 sequence throughout the genome by a process termed transduction. Third, they have affected gene expression by a number of mechanisms. For instance, they occasionally insert into genes and cause disease both in humans and in mice. L1 elements have proven useful as phylogenetic markers and may find other practical applications in gene discovery following insertional mutagenesis in mice and in the delivery of therapeutic genes.

Repression of Ets-2-induced transactivation of the tau interferon promoter by Oct-4

Oct-4 is a POU family transcription factor associated with potentially totipotent cells. Genes expressed in the trophectoderm but not in embryos prior to blastocyst formation may be targets for silencing by Oct-4. Here, we have tested this hypothesis with the tau interferon genes (IFNT genes), which are expressed exclusively in the trophectoderm of bovine embryos. IFNT promoters contain an Ets-2 enhancer, located at -79 to -70, and are up-regulated about 20-fold by the overexpression of Ets-2 in human JAr choriocarcinoma cells, which are permissive for IFNT expression. This enhancement was reversed in a dose-dependent manner by coexpression of Oct-4 but not either Oct-1 or Oct-2. When cells were transfected with truncated bovine IFNT promoters designed to eliminate potential octamer sites sequentially, luciferase reporter expression from each construct was still silenced by Oct-4. Full repression required both the N-terminal and POU domains of Oct-4, but neither domain used alone was an effective silencer. Oct-4 and Ets-2 formed a complex in vitro in the absence of DNA through binding of the POU domain of Oct-4 to a site located between the "pointed" and DNA binding domains of Ets-2. The two transcription factors were also coimmunoprecipitated after being expressed together in JAr cells. Oct-4, therefore, silences IFNT promoters by quenching Ets-2 transactivation. The POU domain most probably binds to Ets-2 directly, while the N-terminal domain inhibits transcription. These findings provide further evidence that the developmental switch to the trophectoderm is accompanied by the loss of Oct-4 silencing of key genes.

Antiviral actions of interferons

Tremendous progress has been made in understanding the molecular basis of the antiviral actions of interferons (IFNs), as well as strategies evolved by viruses to antagonize the actions of IFNs. Furthermore, advances made while elucidating the IFN system have contributed significantly to our understanding in multiple areas of virology and molecular cell biology, ranging from pathways of signal transduction to the biochemical mechanisms of transcriptional and translational control to the molecular basis of viral pathogenesis. IFNs are approved therapeutics and have moved from the basic research laboratory to the clinic. Among the IFN-induced proteins important in the antiviral actions of IFNs are the RNA-dependent protein kinase (PKR), the 2',5'-oligoadenylate synthetase (OAS) and RNase L, and the Mx protein GTPases. Double-stranded RNA plays a central role in modulating protein phosphorylation and RNA degradation catalyzed by the IFN-inducible PKR kinase and the 2'-5'-oligoadenylate-dependent RNase L, respectively, and also in RNA editing by the IFN-inducible RNA-specific adenosine deaminase (ADAR1). IFN also induces a form of inducible nitric oxide synthase (iNOS2) and the major histocompatibility complex class I and II proteins, all of which play important roles in immune response to infections. Several additional genes whose expression profiles are altered in response to IFN treatment and virus infection have been identified by microarray analyses. The availability of cDNA and genomic clones for many of the components of the IFN system, including IFN-alpha, IFN-beta, and IFN-gamma, their receptors, Jak and Stat and IRF signal transduction components, and proteins such as PKR, 2',5'-OAS, Mx, and ADAR, whose expression is regulated by IFNs, has permitted the generation of mutant proteins, cells that overexpress different forms of the proteins, and animals in which their expression has been disrupted by targeted gene disruption. The use of these IFN system reagents, both in cell culture and in whole animals, continues to provide important contributions to our understanding of the virus-host interaction and cellular antiviral response.

Polymorphic forms of expressed bovine interferon-tau genes: relative transcript abundance during early placental development, promoter sequences of genes and biological activity of protein products

Multiple interferon (IFN)-tau genes exist in cattle, but it has remained unclear how many are expressed, the extent of their variation, and whether different genes exhibit similar patterns of expression and code for proteins with similar biological activities. A total of 118 complementary DNA (cDNA) were bi-directionally sequenced from reverse-transcribed bovine (bo) conceptus RNA over the period from blastocyst formation until day 25 of pregnancy. Fourteen different cDNAs, encoding eight different IFN-tau, were confirmed unique. All showed high sequence conservation (>98% nucleotide identity; >96% amino acid identity). The cDNA fell into three, recently evolved, phylogenetic groups (tau1, 2, and 3). Mean concentrations of IFN-tau messenger RNA were greater at day 17 and day 19 than at day 14 and day 25, with different genes showing comparable expression patterns, although there appeared to be a major bias in expression of two genes (for boIFN-tau1c and tau3a) in blastocysts. Genes representing members of the three boIFN-tau groups were cloned. Their promoter regions were conserved over regions considered important for transcriptional activation. Recombinant protein generated in Escherichia coli from representative genes in the three groups had similar but not identical antiviral activities. In summary, many IFN-tau genes, which are probably under similar transcriptional control, are expressed in bovine trophoblast during the peri-implantation period of development.

The role of gamma interferon in antimicrobial immunity

Gamma interferon (IFN-gamma) is an important cytokine in the host defense against infection by viral and microbial pathogens. IFN-gamma induces a variety of physiologically significant responses that contribute to immunity. Treatment of animal cells with IFN-gamma or infection with viral or microbial pathogens leads to changes in the level of expression of several target genes as revealed by DNA microarray analyses. The signaling pathways leading to the induction of IFN-gamma-regulated gene products and, in some cases, their biochemical functions have been defined in exquisite detail. Studies of transgenic mutant mice deficient in proteins of the IFN-gamma response pathway firmly establish the importance of IFN-gamma in immunity.

Validation of an Mx/CAT reporter gene assay for the quantification of bovine type-I interferon

We describe here a specific and sensitive assay for biologically active bovine type-I interferon (IFN) in an Mx/CAT reporter gene assay. The assay is based on Madin-Darby Bovine Kidney cells transfected with a plasmid, containing a human MxA promoter driving a chloramphenicol acetyltransferase (CAT) cDNA. CAT expression was quantified in a commercially available enzyme linked immunosorbant assay. The response to recombinant bovine INF-alpha(1) was dose dependent between 0.25 and 125.0 iu/ml and was shown to be specific for type-I IFN as no significant effect was seen with a number of other cytokines, including IFN-gamma. This Mx/CAT reporter assay also has advantages in terms of simplicity and reliability over conventional cytopathic effect reduction assays used to quantify the IFN activity in bovine samples. The Mx/CAT reporter assay was used successfully to measure trophoblast derived type-1 IFN activity (IFN-tau) in uterine flushings collected from pregnant cows. IFN-tau is the pregnancy recognition signal produced in ruminants by pre-implantation embryos and was shown to increase markedly between the 12th (0.7+/-0.14 iu/ml) and 18th (44085.0+/-14414.2 iu/ml) day of pregnancy. In contrast, IFN-tau activity remained basal (0.5-0.7 iu/ml) in inseminated non-pregnant animals. Duplicate samples analysed using a cytopathic effect reduction assay correlated well (P<0.001; r(2)=0.945) with IFN levels obtained using the Mx/CAT reporter assay, confirming the reporter assay as a reliable substitute for the standard anti-viral IFN assay.

Differences in lymphocyte-regulatory activity among variants of ovine IFN-tau

Interferon-tau (IFN-tau) is secreted from trophectoderm of the ruminant preimplantation conceptus and functions during pregnancy to prevent luteolysis. In addition, IFN-tau can inhibit proliferation of peripheral blood lymphocytes (PBL) and other cells. Several distinct ovine IFN-tau (OvIFN-tau) gene variants exist; three of these (IFN-tau4, IFN-tau6d, IFN-tau11) differ in their ability to prevent luteolysis (IFN-tau4 > IFN-tau6d > IFN-tau11), inhibit growth of Daudi cells (IFN-tau4 > IFN-tau6d > IFN-tau11), and induce an antiviral state (IFN-tau4 > IFN-tau6d = IFN-tau11). The present objective was to compare variants for differences in ability to inhibit proliferation of phytohemagglutinin-stimulated PBL. At equal concentrations, IFN-tau4 was more inhibitory than IFN-tau6d, IFN-tau11, or an IFN-omega control. Similar differences in potency were seen when IFN-tau variants were tested at equal antiviral concentrations. Thus, the sheep trophectoderm secretes variants of IFN-tau that differ in ability to regulate lymphocyte function. The nature of the effect of the trophectoderm on endometrial lymphocytes may depend on the relative amount of each variant produced.

A classification for the interferon-tau

An attempt has been made to provide a rational organization for the many interferon-tau (IFN-tau) sequences entered in GenBank based on phylogenetic analysis and common amino acid substitutions, which might form the basis for a universal nomenclature scheme. Over the 13 years since these genes were first discovered, large numbers of cDNA and gene sequences have been reported, and there is reason to suspect that representatives of all the major ovine and bovine forms have now been described. The data are consistent with the presence of many genes and also allelic variants in sheep and cattle analogous to what has been observed for the IFN-alpha in the human. Future variants should be easily accommodated into the scheme outlined here. A flexible system of nomenclature, based on that used for HuIFN, is needed to provide a common base for comparison between research done in different laboratories and to assign relative biologic potencies to these molecules.

Independent origin of IFN-alpha and IFN-beta in birds and mammals

Phylogenetic analysis of type I interferon (IFN) from birds and mammals strongly supported the hypothesis that the gene duplication giving rise to the alpha and beta families of mammalian IFN occurred after the divergence of birds from mammals, whereas the bird IFN that have been designated alpha and beta duplicated independently in the avian lineage. Therefore, IFN designated alpha and beta in birds are not orthologous to those similarly designated in mammals.

The function of type I interferons in antimicrobial immunity

Type I interferons (IFN-alpha and IFN-beta) were originally described as potent antiviral substances, which are produced upon infection of animal cells with viruses. Despite a large body of literature that has accumulated during the past 25 years, their regulatory function in the immune system is still much less appreciated. Recent studies have highlighted the production of type I IFNs, their function in the immune response to infectious agents and the target cells of these interferons. Type I IFNs clearly affect the release of proinflammatory cytokines or nitric oxide by dendritic cells and macrophages, the capacity of type II interferon (IFN-gamma) to activate phagocytes, the differentiation of T helper cells and the innate control of non-viral pathogens.

Marsupial cytokines. Structure, function and evolution

The cytokines are an important group of molecules involved in coordinating the many and varied components of the immune system. These molecules have been extensively studied in model eutherian mammals such as mice but comparatively little is known about the cytokine network of marsupials. Such information will be invaluable in elucidating fundamental aspects of the marsupial immune system and will also highlight parallels and differences between the immune systems of marsupials and eutherians. Given the importance of these goals, our groups have recently begun to tackle this lack of knowledge of the marsupial cytokine system and have met with considerable success in the face of the rapid rate of change of these proteins. This has led to the isolation of the full-length sequences encoding marsupial orthologues of tumour necrosis factor (TNF), lymphotoxins alpha and beta (LT-alpha and beta), interleukin-1 beta (IL-1beta), and interleukin-10 (IL-10). Here we review what has been learnt about structural, functional and evolutionary aspects of these marsupial cytokines as well as briefly describing more recent work in progress and future directions in this field.

Orthologs, paralogs and genome comparisons

During the past decade, ancient gene duplications were recognized as one of the main forces in the generation of diverse gene families and the creation of new functional capabilities. New tools developed to search data banks for homologous sequences, and an increased availability of reliable three-dimensional structural information led to the recognition that proteins with diverse functions can belong to the same superfamily. Analyses of the evolution of these superfamilies promises to provide insights into early evolution but are complicated by several important evolutionary processes. Horizontal transfer of genes can lead to a vertical spread of innovations among organisms, therefore finding a certain property in some descendants of an ancestor does not guarantee that it was present in that ancestor. Complete or partial gene conversion between duplicated genes can yield phylogenetic trees with several, apparently independent gene duplications, suggesting an often surprising parallelism in the evolution of independent lineages. Additionally, the breakup of domains within a protein and the fusion of domains into multifunctional proteins makes the delineation of superfamilies a task that remains difficult to automate.

The cross-species antiviral activities of different IFN-tau subtypes on bovine, murine, and human cells: contradictory evidence for therapeutic potential

It is claimed that interferon-tau (IFN-tau) has broad cross-species reactivity and less cytotoxicity than other type I IFN when used at high concentration either in vitro or in living animals. It can also amelioriate the development of experimental allergic encephalomyelitis (EAE) without the usual side effects of IFN therapy in mice autoimmunized with myelin basic protein. For these reasons, IFN-tau may have therapeutic potential in humans. Here, the antiviral (AV) activities of eight different recombinant IFN-tau were compared with those of several bovine, human, and murine type I IFN on bovine MDBK cells, murine L929 cells, and human WISH cells. The data show that only one of the IFN-tau, OvIFN-tau4, has broad cross-species reactivity. It was comparable in this respect to HuIFN-omega1 and HuIFN-alpha1. The other IFN-tau, including the variant form (OvIFN-tau1mod) tested by others in cytotoxicity experiments and for its ability to protect mice against EAE, had relatively weak AV activity on mouse and human cells. It is possibly because this particular bioengineered form of IFN-tau binds the common type I receptor of these two species with such low affinity that it lacks cytotoxic effects. The basis for its potent anti-EAE activity is unclear, but it seems possible that it does not involve the type I IFN receptor.

Identification of the expressed forms of ovine interferon-tau in the periimplantation conceptus: sequence relationships and comparative biological activities

Interferon-tau (IFN-tau) is secreted from trophectoderm of periimplantation ruminant conceptuses and is a critical component of pregnancy recognition. Multiple genes encode IFN-tau. The objectives of this study were to identify expressed forms of ovine IFN-tau and to compare their biological activities. Sequences analyzed after cloning 36 reverse transcription-polymerase chain reaction products of ovine conceptus RNA provided seven new cDNA that were similar in sequence to previously cloned forms (p3, p6, and p8 cDNA). Phylogenetic analysis of amino acid sequence for all new and previously reported forms showed that ovine IFN-tau forms can be divided into three main groups. Equivalent amounts of mRNA for p3, p6, and p8 forms were detected in conceptuses following RNase protection. Recombinant p3 and p8 protein had similar antiviral activity on ovine and bovine cells whereas p6 protein was less active. The p3 form was the most potent of the three in its ability to extend estrous cycle length in nonpregnant ewes. In summary, there appeared to be three main groups of ovine IFN-tau, each containing several variant forms. Antiviral activity was not particularly well correlated with ability to prevent luteolysis, suggesting that distinct intracellular mechanisms are used to exert the various actions of IFN-tau.

Functional characterization of monoclonal antibodies to interferon-tau

Interferon tau (IFNtau) produces an array of biological effects, including antiluteolytic, antiviral, antiproliferative and immunomodulatory activities, without the consequent cytotoxicity associated with other type I IFNs. Four anti-IFNtau monoclonal antibodies (MAbs) have been characterized by determining regional epitopes and observation of their effects on IFNtau binding, antiviral and antiproliferative activity. Using an enzyme-linked immunoadsorbent assay (ELISA) developed against six overlapping synthetic peptides representing the entire linear sequence of IFNtau, three antibodies, HL-98, HL-100 and HL-127, were found to react with the carboxy terminal peptide, while HL-129 bound the penultimate amino terminal peptide. Binding studies indicated that MAbs directed against either region could effectively inhibit the binding of alkaline phosphatase labeled IFNtau to cells expressing type I IFN receptors. While only two of the MAbs significantly reversed IFNtau-induced growth inhibition, the antiviral activity of IFNtau was significantly inhibited by MAbs that bound the amino and carboxy termini, confirming the functional importance of these domains in the binding and subsequent activity of IFNtau.

The type I interferon receptor: structure, function, and evolution of a family business

Recent results indicate that coherent models of how multiple interferons (IFN) are recognized and signal selectively through a common receptor are now feasible. A proposal is made that the IFN receptor, with its subunits IFNAR-1 and IFNAR-2, presents two separate ligand binding sites, and this double structure is both necessary and sufficient to ensure that the different IFN are recognized and can act selectively. The key feature is the duplication of the extracellular domain of the IFNAR-1 subunit and the configurational geometry that this imposes on the intracellular domains of the receptor subunits and their associated tyrosine kinases.

Autoimmunity is a type I interferon-deficiency syndrome corrected by ingested type I IFN via the GALT system

Type I interferons (IFN-alpha/beta), products of the innate immune system, can modulate immune function whereas proinflammatory IFN-gamma (type II IFN), a product of the acquired immune system upregulates inflammation and enhances cell mediated immunity. We have proposed a unifying hypothesis of the origin of autoimmunity as a type I IFN immunodeficiency syndrome involving inadequate regulation of the acquired immune system product IFN-gamma by the IFN-alpha/beta innate immune system. The common theme of ingested type I IFNs in autoimmunity is inhibition of proinflammatory type II IFN systemically or at the target organ. In multiple sclerosis (MS) and insulin-dependent diabetes mellitus (IDDM) at the target organ, and in rheumatoid arthritis (RA) as a regulator of other proinflammatory cytokines, IFN-gamma is the nexus of inflammation in autoimmunity. Ingested type I IFNs counteract type II IFN, overcome the relative lack of type I IFN activity, and ameliorate autoimmunity. The administration of type I IFNs (IFN-alpha/beta) via the gut offers an exciting alternative to systemic application for overcoming the type I IFN immunodeficiency in autoimmunity. Successful use of ingested type I IFN in three separate prototypical autoimmune diseases suggests a broad antiinflammatory therapeutic profile for this technology.