Biological activity of interleukins-28 and -29: comparison with type I interferons

A possible anticancer agent, type III interferon, activates cell death pathways and produces antitumor effects

Recently identified interleukin-28 and -29 belong to a novel type III interferon (IFN) family, which could have distinct biological properties from type I and II IFNs. Type I IFNs, IFN-α/β, have been clinically applied for treating a certain kind of malignancies for over 30 years, but a wide range of the adverse effects hampered the further clinical applications. Type III IFNs, IFN-λs, have similar signaling pathways as IFN-α/β and inhibits proliferation of tumor cells through cell cycle arrest or apoptosis. Restricted patterns of type III IFN receptor expression in contrast to ubiquitously expressed IFN-α/β receptors suggest that type III IFNs have limited cytotoxicity to normal cells and can be a possible anticancer agent. In this paper, we summarize the current knowledge on the IFN-λs-mediated tumor cell death and discuss the functional difference between type I and III IFNs.

IFN-λs

For decades, type I IFNs have been considered indispensable and unique antiviral mediators for the activation of rapid innate antiviral protection. However, the recent discovery of type III IFNs is challenging this paradigm. Since their identification in 2002/2003 by two independent groups, type III IFNs or IFN-λs, also known as IL-28/29, have been the subject of increased study with consequent recognition of their importance in virology and immunology. Initial reports suggested that IFN-λs functionally resemble type I IFNs. Although IFN-λs and classical type I IFNs (IFN-α/β) utilize distinct receptor complexes for signaling, both types of IFNs activate similar intracellular signaling pathways and biological activities, including the ability to induce antiviral state in cells, and both type I and type III IFNs are induced by viral infection. However, different antiviral potency, pattern of their induction and differential tissue expression of their corresponding receptor subunits suggest that the type I and type III IFN antiviral systems do not merely duplicate each other. Recent studies have started to reveal unique biological activities of IFN-λs in and beyond innate antiviral immunity.

Impact of aging on dendritic cell functions in humans

Aging is a paradox of reduced immunity and chronic inflammation. Dendritic cells are central orchestrators of the immune response with a key role in the generation of immunity and maintenance of tolerance. The functions of DCs are compromised with age. There is no major effect on the numbers and phenotype of DC subsets in aged subjects; nevertheless, their capacity to phagocytose antigens and migrate is impaired with age. There is aberrant cytokine secretion by various DC subsets with CDCs secreting increased basal level of pro-inflammatory cytokines but the response on stimulation to foreign antigens is decreased. In contrast, the response to self-antigens is increased suggesting erosion of peripheral self tolerance. PDC subset also secretes reduced IFN-α in response to viruses. The capacity of DCs to prime T cell responses is also affected. Aging thus has a profound affect on DC functions. Present review summarizes the effect of advancing age on DC functions in humans in the context of both immunity and tolerance.

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

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

Identifying innate immune pathways of the chicken may lead to new antiviral therapies

Zoonotic viruses, such as highly pathogenic avian influenza (HPAI), present a significant threat to both the poultry industry and public health. The present method of controlling avian influenza (AI) relies on good farming practice with limited use of vaccination in some countries. However, new ways to control disease outbreaks might be possible with additional knowledge of the natural host response to virus. Moreover, manipulation of the innate immune system in mammals improves the outcomes following viral infection. A similar approach might be applied to the chicken, nevertheless, a greater knowledge of the chicken innate immune system is required. This review outlines important mammalian antiviral mechanisms that have been modulated to strengthen viral immunity and highlights the potential application of these strategies in the chicken, especially in regards, to AI.

IL-28B rs12979860 C/T allele distribution in patients with liver cirrhosis: role in the course of chronic viral hepatitis and the development of HCC

BACKGROUND & AIMS

A single nucleotide polymorphism (rs12979860 C/T) 3kb upstream of the interleukin 28B (IL-28B) gene was shown to be associated with hepatitis C clearance. We verified whether this association also translates into a different genotype distribution at the end of the disease trajectory.

METHODS

A RFLP-PCR technique was used to genotype 412 patients with cirrhosis due to hepatitis C (n=199), hepatitis B (n=75), alcohol (n=110), and other causes (n=28), of whom 256 underwent liver transplantation (OLT). Hepatocellular carcinoma (HCC) was demonstrated in the native liver of 85 OLT patients, 52 with viral cirrhosis, and 33 with non-viral cirrhosis respectively. A group of 292 patients (235 HCV and 57 HBV positive) with mild chronic hepatitis and 344 healthy subjects served as controls.

RESULTS

A significant difference (p=0.0005) was observed in IL-28B rs12979860 genotype frequencies between patients with viral cirrhosis (C/C=99, C/T=137, T/T=38) and those with non-viral cirrhosis (C/C=72, C/T=58, T/T=8). Patients with HCV related cirrhosis carried more frequently the T/T genotype in comparison to mild hepatitis C or HBV-related cirrhosis. IL-28B rs12979860 genotype frequencies were C/C=23, C/T=50, T/T=12 among OLT patients with cirrhosis complicated by HCC, and C/C=79, C/T=78, T/T=14 among patients with cirrhosis not complicated by HCC (p<0.005).

CONCLUSIONS

IL-28B rs12979860 C/T polymorphism T allele is more prevalent in patients with viral cirrhosis due to HCV in comparison to other aetiologies and to patients with mild chronic hepatitis C. Among OLT patients, carriage of this allele seems to augment the risk of developing HCC.

Interferon-lambda: a new addition to an old family

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

Interferon-lambda in the immune response to hepatitis B virus and hepatitis C virus

Approximately 500 million people worldwide are chronically infected with the hepatitis B virus (HBV) or hepatitis C virus (HCV), and are therefore at an increased risk for developing fatal liver diseases such as cirrhosis and hepatocellular carcinoma. The intracellular antiviral responses induced by interferon (IFN)-alpha/-beta and/or IFN-gamma play critical roles in the pathogenesis of HBV and HCV infection, and the function of IFN-lambda in the host immune response to these viruses is beginning to be revealed. A better understanding of how IFN-lambda influences HBV or HCV persistence is not only important for understanding the mechanisms of chronic virus infection, but also may lead to new approaches for improved antiviral therapies.

Regulatory effects of ribosomal S6 kinase 1 (RSK1) in IFNλ signaling

Although the mechanisms of generation of signals that control transcriptional activation of Type III IFN (IFNλ)-regulated genes have been identified, very little is known about the mechanisms by which the IFNλ receptor generates signals for mRNA translation of IFNλ-activated genes. We provide evidence that IFNλ activates the p90 ribosomal protein S6 kinase 1 (RSK1) and its downstream effector, initiation factor eIF4B. Prior to its engagement by the IFNλ receptor, the non-active form of RSK1 is present in a complex with the translational repressor 4E-BP1 in IFNλ-sensitive cells. IFNλ-inducible phosphorylation/activation of RSK1 results in its dissociation from 4E-BP1 at the same time that 4E-BP1 dissociates from eIF4E to allow formation of eIF4F and initiation of cap-dependent translation. Our studies demonstrate that such IFNλ-dependent engagement of RSK1 is essential for up-regulation of p21(WAF1/CIP1) expression, suggesting a mechanism for generation of growth-inhibitory responses. Altogether, our data provide evidence for a critical role for the activated RSK1 in IFNλ signaling.

Interferons as potential adjuvants in prophylactic vaccines

IMPORTANCE OF THE FIELD

Vaccines are still one of the best approaches to manage infectious diseases. Despite the advances in drug therapies, prophylactic medicine is still more cost efficient and minimizes the burden in the heath system. Despite all the research in vaccine development, many infectious diseases are still without an effective vaccine. The use of adjuvants in vaccines has been one successful strategy to increase efficacy. IFNs are widely expressed cytokines that have potent antiviral effects. These cytokines are the first line of defense against viral infections and have important roles in immuno surveillance for malignant cells. One of the most promising uses of IFNs is as adjuvants that are co-applied with antigen in vaccines.

AREAS COVERED IN THIS REVIEW

In this review, a cumulative analysis of many of the studies that have used IFN-α, -β, -γ and -λ as adjuvants between 1987 and the present suggests that many do possess the capacity to serve as potent immunoadjuvants for vaccination.

WHAT THE READER WILL GAIN

This review provides a very large collection of studies involving all types of IFNs used as adjuvants in vaccines using different vaccination strategies and various animal models.

TAKE HOME MESSAGE

It is clear that the use of IFNs not only improved the efficacy and safety of most vaccines, but also had important immunomodulatory effect directing T(H)1 immune responses.

Crystal structure of human interferon-λ1 in complex with its high-affinity receptor interferon-λR1

Interferon (IFN)-λ1 [also known as interleukin (IL)-29] belongs to the recently discovered group of type III IFNs. All type III IFNs initiate signaling processes through formation of specific heterodimeric receptor complexes consisting of IFN-λR1 and IL-10R2. We have determined the structure of human IFN-λ1 complexed with human IFN-λR1, a receptor unique to type III IFNs. The overall structure of IFN-λ1 is topologically similar to the structure of IL-10 and other members of the IL-10 family of cytokines. IFN-λR1 consists of two distinct domains having fibronectin type III topology. The ligand-receptor interface includes helix A, loop AB, and helix F on the IFN site, as well as loops primarily from the N-terminal domain and inter-domain hinge region of IFN-λR1. Composition and architecture of the interface that includes only a few direct hydrogen bonds support an idea that long-range ionic interactions between ligand and receptor govern the process of initial recognition of the molecules while hydrophobic interactions finalize it.

An assessment of biological potency and molecular characteristics of different innovator and noninnovator interferon-beta products

Approved innovator products and their noninnovator "copy" versions are likely to vary in their quality, eg, physicochemical characteristics and biological activity, with important implications for clinical efficacy and safety. Therefore, it is important to study and thoroughly evaluate the noninnovator products in comparison with approved products at the preclinical and clinical stages. We have obtained 4 noninnovator interferon (IFN)-β-1a products currently marketed in Latin America and Iran and compared these with approved IFN-β-1a products (Avonex and Rebif) obtained from the same geographical regions with respect to biological potency, estimated by in vitro bioassays, and molecular characteristics, assessed by immunoblotting and high-performance liquid chromatography. In this article, we present our data showing that the noninnovator IFN-β-1a products can vary considerably in their biological potency. In addition, we showed that all IFN-β-1a products formulated with human serum albumin contained variable amounts of higher-molecular-weight aggregates of IFN-β-1a and adducts with human serum albumin, these being more prevalent in 2 noninnovator IFN-β-1a products where biological potency was reduced compared with approved IFN-β-1a products. Additionally, significant lot-to-lot variability was observed for one of the noninnovator products. Taken together, the results of this study highlight the need for not only thorough in vitro characterization, but also preclinical and clinical assessment to ensure patient safety and efficacy.

Influenza A virus replication is inhibited in IFN-λ2 and IFN-λ3 transfected or stimulated cells

Interferons lambda (IFN-λ) are the most recently defined members of the class III cytokine family. To investigate whether IFN-λ2 and IFN-λ3 displayed antiviral activity against influenza A virus (IAV), a number of cell lines induced with IFNs - as well as two established cell lines (A549-IFN-λ2 and A549-IFN-λ3) - were infected with IAV. Our results indicate that IFN-λ2 has statistically significant antiviral activity in A549-IFN-λ2 (P=0.0028) although less so than IFN-λ3, which reduced viral titer to 10% (P<0.0001). The reverse was observed for cells treated with IFNs, with IFN-λ2-treated A549 cells inhibiting IAV infection more efficiently than IFN-λ3-treated A549 cells. The antiviral effect on IFN-stimulated cells was most apparent on Vero cells (compared with MDCK and HeLa). Both IFNs significantly inhibited IAV replication and inhibition was observed in a dose-dependent manner, with an optimal IFN concentration of 20 ng/ml. IFN-λ2 was more potent than IFN-λ3 on Vero cells while IFN-λ3 appeared more efficient than IFN-λ2 on MDCK and HeLa cells.

Molecular characterization and antiviral analyses of porcine type III interferons

Type III interferons (IFNs) are a family of recently identified antiviral cytokines. One to 3 paralogs have been identified in several species; however, little information is available about type III IFNs in pigs. We have identified 2 porcine type III IFNs, Sus scrofa IFN-λ1 (SsIFN-λ1) and SsIFN-λ3, and determined their tissue expression profile and antiviral activities. Open reading frames of SsIFN-λ1 and SsIFN-λ3 are 576 and 588 bp, encoding 191 and 195 amino acid preproteins, respectively. In healthy pigs, SsIFN-λ3 was primarily expressed in mesenteric lymph nodes and intestine, whereas expression of SsIFN-λ1 was found in all tested tissues and was high in mesenteric lymph nodes, intestine, and liver. Porcine cells treated with the viral mimic, dsRNA, robustly increased SsIFN-λ3 expression, with epithelial cells generally displaying the greatest response. Conversely, dsRNA-induced mRNA expressions of SsIFN-λ1, SsIFN-α1, and SsIFN-β were relatively weaker and delayed compared with SsIFN-λ3. SsIFN-λ1 and SsIFN-λ3 peptides exerted similar but lower antiviral potency than SsIFN-α1 and SsIFN-β against a porcine arterivirus and an adenovirus. These findings indicate that pigs have 2 type III IFN paralogs, which have antiviral activity and may serve as targets for modulation of the porcine host-pathogen interaction.

Alpha/beta interferon (IFN-alpha/beta)-independent induction of IFN-lambda1 (interleukin-29) in response to Hantaan virus infection

Type III interferons ([IFNs] IFN-lambda and interleukin-28 and -29 [IL-28/29]) are recently recognized cytokines with innate antiviral effects similar to those of type I IFNs (IFN-alpha/beta). Like IFN-alpha/beta, IFN-lambda-expression can be induced by viruses, and it is believed that type I and III IFNs are regulated in the same manner. Hantaviruses are weak IFN-alpha/beta inducers and have surprisingly been shown to activate IFN-alpha/beta-independent IFN-stimulated gene (ISG) expression. Here, we show that in Hantaan virus (HTNV)-infected human epithelial A549 cells, induction of IFN-lambda1 preceded induction of MxA and IFN-beta by 12 and 24 h, respectively, and IFN-alpha was not induced at all. Furthermore, induction of IFN-lambda1 and MxA was observed in HTNV-infected African green monkey epithelial Vero E6 cells, a cell line that cannot produce type I IFNs, clearly showing that HTNV can induce IFN-lambda1 and ISGs in the complete absence of IFN-alpha/beta. In HTNV-infected human fibroblast MRC-5 cells, which lack the IFN-lambda receptor, induction of MxA coincided in time with IFN-beta-induction. UV-inactivated HTNV did not induce any IFNs or MxA in any cell line, showing that activation of IFN-lambda1 is dependent on replicating virus. Induction of both IFN-beta and IFN-lambda1 in A549 cells after poly(I:C)-stimulation was strongly inhibited in HTNV-infected cells, suggesting that HTNV can inhibit signaling pathways used to simultaneously activate types I and III IFNs. In conclusion, we show that HTNV can cause type I IFN-independent IFN-lambda1 induction and IFN-lambda1-specific ISG induction. Importantly, the results suggest the existence of specific signaling pathways that induce IFN-lambda1 without simultaneous type I IFN induction during virus infection.

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

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

Inhibition of type III interferon activity by orthopoxvirus immunomodulatory proteins

The type III interferon (IFN) family elicits an antiviral response that is nearly identical to that evoked by IFN-alpha/beta. However, these cytokines (known as IFN-lambda1, 2, and 3) signal through a distinct receptor, and thus may be resistant to the evasion strategies used by some viruses to avoid the IFN-alpha/beta response. Orthopoxviruses are highly resistant to IFN-alpha/beta because they encode well-characterized immunomodulatory proteins that inhibit IFN activity. These include a secreted receptor (B18R) that neutralizes IFN-alpha/beta, and a cytoplasmic protein (E3L) that blocks IFN-alpha/beta effector functions in infected cells. We therefore determined the ability of these immunomodulators to abrogate the IFN-lambda-induced antiviral response. We found that (i) vaccinia virus (VACV) replication is resistant to IFN-lambda antiviral activity; (ii) neither VACV B18R nor the variola virus homolog B20R neutralizes IFN-lambda; (iii) VACV E3L inhibits the IFN-lambda-mediated antiviral response through a PKR-dependent pathway; (iv) VACV infection inhibits IFN-lambdaR-mediated signal transduction and gene expression. These results demonstrate differential sensitivity of IFN-lambda to multiple distinct evasion mechanisms employed by a single virus.

Interferon-λ in HCV Infection and Therapy

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

Interferon-lambda as a potential therapeutic agent in cancer treatment

The discovery that type I interferon (IFN-alpha/beta) inhibited tumor cell growth was welcomed initially with great excitement as it rapidly became a U.S. Food and Drug Administration-approved drug to treat several forms of cancer. In time, this enthusiasm diminished as severe toxicity associated with IFN-alpha administration, resistance to the therapy, or less than optimal responses became evident in cancer patients, thus restricting its clinical use and reducing its potential as an anticancer drug. The recent discovery of a third type of IFN [IFN-lambda/interleukin (IL)-29/IL-28], which shares the same biological properties of type I IFNs, opens the door for evaluating the therapeutic potential of IFN-lambda as it uses a distinct receptor complex whose expression, unlike type I IFN receptors, is restricted to cells of specific lineage. It is unclear whether the mechanism by which type III IFNs restrict tumor cell proliferation is different or the same from the one utilized by type I IFN. Nevertheless, accumulating evidence as described in this review suggests that, in contrast to IFN-alpha therapy, IFN-lambda therapy could be less toxic and suitable for certain types of malignancies as not all cells are responsive to this cytokine.

IL-28A, IL-28B, and IL-29: promising cytokines with type I interferon-like properties

IL-28A, IL-28B and IL-29 (also designated type III interferons) constitute a new subfamily within the IL-10-interferon family. They are produced by virtually any nucleated cell type, particularly dendritic cells, following viral infection or activation with bacterial components, and mediate their effects via the IL-28R1/IL-10R2 receptor complex. Although IL-28/IL-29 are closer to the IL-10-related cytokines in terms of gene structure, protein structure, and receptor usage, they display type I interferon-like anti-viral and cytostatic activities. Unlike type I interferons, the target cell populations of IL-28/IL-29 are restricted and mainly include epithelial cells and hepatocytes. These properties suggest that IL-28/IL-29 are potential therapeutic alternatives to type I interferons in terms of viral infections and tumors. This review describes the current knowledge about these cytokines.

The lambda interferons: guardians of the immune-epithelial interface and the T-helper 2 response

The type-III interferons (IFNs) are the most recently discovered IFNs in the human immune system and have important, but as yet poorly characterized, functions in innate and adaptive immunity that complement their antiviral functions. It is now becoming clear that these type-III IFNs have a functional niche where epithelial surfaces interact with the adaptive immune system, that their antiviral capability is not as highly developed as that of the type-I IFNs, and that they have their own profile of immunomodulatory functions; specifically, they are key modulators of the T-helper (Th)2 response.

The effect of IL-28A on human cord blood CD4+ T cells

BACKGROUND AND AIM

The utilization of umbilical cord blood transplantation (UCBT) has been increasing because of the potential advantage of rapid accessibility and the lesser risk of graft-versus-host disease (GVHD), thus allowing less strict HLA matching. IL-28A, also known as IFN-lambda2, has been regarded as a member of a new cytokine family that shares some features with type I interferon (IFN) and was shown to have antiviral activity. The aim of this study was to identify biological activity of IL-28 on cord blood CD4(+) T cells.

MATERIALS AND METHODS

In this study, we cultured CD4(+) T cells with IL-28A (20 ng/ml), IL-2 (20 ng/ml) and 5microg/ml MACS Anti-Biotin MACSiBead Particles (bead-to-cell ratio 1:2) for 2 weeks.

RESULTS

Flow cytometry analyses showed that IL-28A cannot be effective on CD25 and Foxp3 expression on cord blood CD4(+) T cells, and it is not involved in proliferation of these cells. Treg suppression assay also showed that this cytokine cannot induce production of regulatory T cells.

CONCLUSION

We showed that IL-28A is not involved in expression of CD25 and Foxp3 markers and proliferation of CD4(+)CD25(-) T cells, and that our findings also suggest that induction of Foxp3 in T cells activated by anti-CD3/anti-CD28 does not result in the regulatory activity in these cells.

IL-4 enhances IFN-lambda1 (IL-29) production by plasmacytoid DCs via monocyte secretion of IL-1Ra

The type-III interferon (IFN) family is composed of 3 molecules in humans: IFN-lambda1 (interleukin-29 [IL-29]), IFN-lambda2 (IL-28A), and IFN-lambda3 (IL-28B), each of which signals through the same receptor complex. Plasmacytoid dendritic cells (pDCs) are major IFN-lambda producers among peripheral lymphocytes. Recently, it has been shown that IFN-lambda1 exerts a powerful inhibitory effect over the T-helper 2 (Th2) response by antagonizing the effect of IL-4 on CD4(+) T cells and inhibiting the production of Th2-associated cytokines. Here, we asked whether Th2 cytokines exert reciprocal control over IFN-lambda production. IL-4 treatment during stimulation of human peripheral lymphocytes significantly elevated IFN-lambda1 transcription and secretion. However, pDCs were not directly responsive to IL-4. Using depletion and reconstitution experiments, we showed that IL-4-responsive monocytes are an intermediary cell, responding to IL-4 by elevating their secretion of IL-1 receptor antagonist (IL-Ra); this IL-1Ra acts on pDCs to elevate their IFN-lambda1 output. Thus, our experiments revealed a novel mechanism for regulation of both IFN-lambda1 production and pDC function, and suggests an expanded immunomodulatory role for Th2-associated cytokines.

lambda-Interferons and the single nucleotide polymorphisms: A milestone to tailor-made therapy for chronic hepatitis C

Type III interferons (IFN) (IFN-lambda1, -lambda2, -lambda3/interleukin [IL]-29, -28A, -28B) are cytokines with type I IFN-like antiviral activities. Most cells have expressed both type I and III IFN following Toll-like receptor (TLR) stimulation or viral infection, whereas the ability of cells to respond to IFN-lambda was restricted to a specific subset of cells. It was reported that signal transduction pathway of IFN-lambda was similar to that of IFN-alpha/beta although a receptor adapted by IFN-lambda were distinct from that of IFN-alpha/beta. However, the clinical significance and the role of each IFN-lambda were unclear. Recent genome-wide association studies (GWAS) of the human whole genome revealed several single nucleotide polymorphism sites (SNP) strongly associated with the response to pegylated IFN-alpha (PEG-IFN) plus ribavirin (RBV) treatment in chronic hepatitis C patients. The SNP, which are located near the IL-28B gene of chromosome 19, were discovered simultaneously by three independent studies opening a new prospective in hepatitis C research. The present review highlights significant insights that can be derived from the GWAS approach, and summarizes current knowledge of in vitro and in vivo study on the role of IFN-lambda in antiviral effect.

Lambda Interferons: New Cytokines with Old Functions

Interferon lambda (IFN-λ) is a member of the class II cytokine family, and like the other members of this family, they are small helical proteins. Since their discovery significant efforts have been made to determine their role in innate and adaptive immunity. Their strong antiviral activity, both in vitro and in vivo, has firmly established their interferon status. However, in contrast to type I interferon, only a very limited subset of cells/tissues responds to interferon lambda. In addition to inducing an antiviral state in responsive cells, recent data suggest that IFN-l plays a role in shaping the adaptive immune response. However, the data is not in complete agreement regarding the effect of IFN-λ on the adaptive immune system. Recently IFN-l has entered clinical trials against hepatitis C Virus and IFN-l is a promising future therapeutic, against different viruses replicating in responsive tissues, like that of the airway epithelia. In this review we describe the knowledge acquired during the past six years about the structure and function of interferon lambda.

Antitumor activity of type I and type III interferons in BNL hepatoma model

Hepatocellular carcinoma (HCC) occurs most commonly secondary to cirrhosis due to chronic hepatitis C or B virus (HCV/HBV) infections. Type I interferon (IFN-alpha) treatment of chronic HCV/HBV infections reduces the incidence of HCC in cirrhotic patients. However, IFN-alpha toxicity limits its tolerability and efficacy highlighting a need for better therapeutic treatments. A recently discovered type III IFN (IFN-lambda) has been shown to possess antiviral properties against HCV and HBV in vitro. In phase I clinical trials, IFN-lambda treatment did not cause significant adverse reactions. Using a gene therapy approach, we compared the antitumor properties of IFN-alpha and IFN-lambda in a transplantable hepatoma model of HCC. BALB/c mice were inoculated with syngeneic BNL hepatoma cells, or BNL cells expressing IFN-lambda (BNL.IFN-lambda cells) or IFN-alpha (BNL.IFN-alpha cells). Despite the lack of antiproliferative activity of IFNs on BNL cells, both BNL.IFN-lambda and BNL.IFN-alpha cells displayed retarded growth kinetics in vivo. Depletion of NK cells from splenocytes inhibited splenocyte-mediated cytotoxicity, demonstrating that NK cells play a role in IFN-induced antitumor responses. However, isolated NK cells did not respond directly to IFN-lambda. There was also a marked NK cell infiltration in IFN-lambda producing tumors. In addition, IFN-lambda and, to a lesser extent, IFN-alpha enhanced immunocytotoxicity of splenocytes primed with irradiated BNL cells. Splenocyte cytotoxicity against BNL cells was dependent on IL-12 and IFN-gamma, and mediated by dendritic cells. In contrast to NK cells, isolated from spleen CD11c+ and mPDCA+ dendritic cells responded directly to IFN-lambda. The antitumor activities of IFN-lambda against hepatoma, in combination with HCV and HBV antiviral activities warrant further investigation into the clinical use of IFN-lambda to prevent HCC in HCV/HBV-infected cirrhotic patients, as well as to treat liver cancer.

Establishment of an IFN-gamma specific reporter cell line in fish

An interferon (IFN)-gamma responsive stable cell line RTG-3F7 has been developed for rainbow trout by modifying the RTG-2 cell line through transfection with a plasmid construct (pGL4.14[luc2/hygro]-PrTAP2) containing a promoter element from the IFN-gamma responsive gene TAP2 linked to a luciferase reporter gene and a hygromycin resistance gene. Following transfection single clones were selected in 96 well plates using hygromycin B, and those showing specific activation after rIFN-gamma stimulation were maintained. Five clones that showed the highest reporter activity to rIFN-gamma were incubated with different stimuli to examine specificity. No significant induction of luciferase was observed following exposure to recombinant type I IFN, LPS, PHA or poly I:C. The cell line was responsive to rIFN-gamma at concentrations between 150 pg and 20 ng ml(-1). Supernatants of primary cultures of head kidney leucocytes stimulated with PHA, known to induce IFN-gamma gene expression, were also used to assess the reporter activity of the stable cell line. A dose-dependent induction of the promoter activity was observed with these supernatants indicating the presence of IFN-gamma. These results indicate that the stable cell line RTG-3F7 is an excellent tool for monitoring the presence of trout IFN-gamma in biological samples, and in addition, enables the study of intracellular signalling pathways of IFNs, their receptor interactions, and other closely related signalling networks.

Interleukin-29 binds to melanoma cells inducing Jak-STAT signal transduction and apoptosis

Interleukin-29 (IL-29) is a member of the type III IFN family that has been shown to have antiviral activity and to inhibit cell growth. Melanoma cell lines were tested for expression of the IL-29 receptor (IL-29R) and their response to IL-29. Expression of IL-28R1 and IL-10R2, components of IL-29R, was evaluated using reverse transcription-PCR. A combination of immunoblot analysis and flow cytometry was used to evaluate IL-29-induced signal transduction. U133 Plus 2.0 Arrays and real-time PCR were used to evaluate gene expression. Apoptosis was measured using Annexin V/propridium iodide staining. In situ PCR for IL-29R was done on paraffin-embedded melanoma tumors. Both IL-28R1 and IL-10R2 were expressed on the A375, 1106 MEL, Hs294T, 18105 MEL, MEL 39, SK MEL 5, and F01 cell lines. Incubation of melanoma cell lines with IL-29 (10-1,000 ng/mL) led to phosphorylation of signal transducer and activator of transcription 1 (STAT1) and STAT2. Microarray analysis and quantitative reverse transcription-PCR showed a marked increase in transcripts of IFN-regulated genes after treatment with IL-29. In the F01 cell line, bortezomib-induced and temozolomide-induced apoptosis was synergistically enhanced following the addition of IL-29. In situ PCR revealed that IL-10R2 and IL-28R1 were present in six of eight primary human melanoma tumors but not in benign nevi specimens. In conclusion, IL-29 receptors are expressed on the surface of human melanoma cell lines and patient samples, and treatment of these cell lines with IL-29 leads to signaling via the Jak-STAT pathway, the transcription of a unique set of genes, and apoptosis.

Interferon lambda as a potential new therapeutic for hepatitis C

Interferon lambdas (IFN-lambda) are Type III interferons with biological activity, including induction of antiviral genes, similar to Type I IFNs, but signal through a distinct receptor complex. The expression pattern for the IFN-lambda receptor is more cell specific than the widely distributed IFN-alpha receptor, suggesting in vivo, IFN-lambda may have fewer side effects than IFN-alpha, such as less hematologic toxicities. A PEGylated form of IFN-lambda (PEG-rIL-29) was well tolerated in animals and did not result in hematologic toxicity. Clinical data from initial studies of PEG-rIL-29 has demonstrated antiviral effects in patients with hepatitis C without producing hematologic toxicity. These preclinical and early clinical data support PEG-rIL-29 as a potential new therapeutic agent for treatment of patients with hepatitis C.

Interferon-lambda induces G1 phase arrest or apoptosis in oesophageal carcinoma cells and produces anti-tumour effects in combination with anti-cancer agents

Signal pathways of novel type III interferons (IFN-lambdas) are similar to those of type I IFNs (IFN-alpha/beta) but their distinct functions have not been well characterised. We examined the growth suppressive activity of IFN-lambda1 with nine human oesophageal carcinoma cell lines expressing the IFN-lambda receptor complexes. Among them, three lines but not others showed IFN-lambda1-mediated growth suppression by inducing G1 phase arrest or apoptosis. The G1 phase arrest was accompanied by the up-regulation of p21 and dephosphorylation of retinoblastoma (Rb), and the apoptosis was evidenced by cleavage of caspase-3 and poly (ADP-ribose) polymerase (PARP). Similar but not identical susceptibility was found in IFN-alpha-treated oesophageal carcinoma cells. Despite the differential suppressive responses among the cells, all the cells increased the expression of the myxovirus resistance A (MxA) and 2',5'-oligoadenylate synthetase (2',5'-OAS) genes and class I antigens of the major histocompatibility complexes (MHC) with IFN-lambda1 treatment. Fibroblasts and mesenchymal stem cells, positive for IFN-alpha receptor (IFNAR), lacked one of the IFN-lambda receptor complexes and Het-1A, immortalised oesophageal epithelium cells, were insensible to the IFN-lambda1-induced growth suppression. IFN-lambda1 produced combinatory anti-tumour effects with chemotherapeutic agents, cisplatin (CDDP) and 5-fluorouracil (5-FU), in IFN-lambda1-sensitive oesophageal carcinoma cells but not in normal or Het-1A cells, while IFN-alpha achieved the combinatory suppressive effects to normal cells. These data collectively show that IFN-lambda1 responsiveness is tissue-specific due to the restricted receptors expression and is diversified even among cells of the same lineage, and suggest that IFN-lambda1 is a potential therapeutic agent for oesophageal carcinoma without damaging surrounding tissues.

Purification, crystallization and preliminary crystallographic studies of the complex of interferon-lambda1 with its receptor

Human interferon-lambda1 (IFN-lambda1(Ins)) and the extracellular domain of interferon-lambda1 receptor (IFN-lambda1R1) were expressed in Drosophila S2 cells and purified to homogeneity. Both IFN-lambda1(Ins) and interferon-lambda1 produced from Escherichia coli (IFN-lambda1(Bac)) were coupled with IFN-lambda1R1 at room temperature and the complexes were purified by gel filtration. Both complexes were crystallized; the crystals were flash-frozen at 100 K and diffraction data were collected to 2.16 and 2.1 A, respectively. Although the IFN-lambda1(Bac)-IFN-lambda1R1 and IFN-lambda1(Ins)-IFN-lambda1R1 complexes differed only in the nature of the expression system used for the ligand, their crystallization conditions and crystal forms were quite different. A search for heavy-atom derivatives as well as molecular-replacement trials are in progress.

Modulation of human plasmacytoid DC function by IFN-lambda1 (IL-29)

The type III family of IFNs displays immunomodulatory and antiviral activity. Each member (IFN-lambda1, -2, and -3) signals through the same heterodimeric receptor complex, which consists of the binding and signaling subunit (IL-28Ralpha) plus the IL-10Rbeta chain. Although the receptor has a wide tissue distribution, the direct effects of IFN-lambda on various immune cell subsets have not been fully characterized. We have identified high levels of IL-28Ralpha mRNA in pDC from peripheral blood and hypothesized that IFN-lambda plays an important role in pDC maturation and development. We show that stimulation of pDC with HSV or Imiquimod causes an increase in IL-28Ralpha mRNA. In these cells, IFN-lambda1 alters expression of the costimulatory molecules CD80 and ICOS-L and synergizes with IFN-alpha to up-regulate CD83. In addition, IFN-lambda1 has a variable effect on the homing molecule expression of pDC and mDC. IFN-lambda1-treated pDC display a marked difference in their ability to stimulate production of the signature cytokines IL-13, IFN-gamma, and IL-10 in a MLR. This work characterizes the variable effects of IFN-lambda on DC surface molecule expression and identifies a role in pDC activation and immunostimulatory potential.

IL-12 and type I IFN response of neonatal myeloid DC to human CMV infection

Following congenital human CMV (HCMV) infection, 15-20% of infected newborns develop severe health problems whereas infection in immunocompetent adults rarely causes illness. The immaturity of neonatal antigen presenting cells could play a pivotal role in this susceptibility. Neonatal myeloid DC were shown to be deficient in IFN-beta and IL-12 synthesis in response to TLR triggering. We studied the response of cord and adult blood-derived myeloid DC to HCMV infection. Neonatal and adult DC were equally susceptible to in vitro HCMV infection. Among immunomodulatory cytokines, IL-12, IFN-beta and IFN-lambda1 were produced at lower levels by neonatal as compared with adult DC. In contrast, neonatal and adult DC produced similar levels of IFN-alpha and IFN-inducible genes. Microarray analysis indicated that among the more than thousand genes up- or down-regulated by HCMV infection of myeloid DC, 88 were differently regulated between adult and neonatal DC. We conclude that neonatal and adult DC trigger a partly different response to HCMV infection. The deficient IL-12 and mature IFN-alpha production by neonatal DC exposed to HCMV are likely to influence the quality of the T lymphocyte response to HCMV infection in early life.

Despite IFN-lambda receptor expression, blood immune cells, but not keratinocytes or melanocytes, have an impaired response to type III interferons: implications for therapeutic applications of these cytokines

Interferon (IFN)-lambda1, -2 and -3 (also designated as interleukin (IL)-29, IL-28alpha and IL-28beta) represent a new subfamily within the class II cytokine family. They show type I IFN-like antiviral and cytostatic activities in affected cells forming the basis for IFN-lambda1 therapy currently under development for hepatitis C infection. However, many aspects of IFN-lambdas are still unknown. This study aimed at identifying the target cells of IFN-lambdas within the immune system and the skin. Among skin cell populations, keratinocytes and melanocytes, but not fibroblasts, endothelial cells or subcutaneous adipocytes turned out to be targets. In contrast to these target cells, blood immune cell populations did not clearly respond to even high concentrations of these cytokines, despite an IFN-lambda receptor expression. Interestingly, immune cells expressed high levels of a short IFN-lambda receptor splice variant (sIFN-lambdaR1/sIL-28R1). Its characterization revealed a secreted, glycosylated protein that binds IFN-lambda1 with a moderate affinity (K(D) 73 nM) and was able to inhibit IFN-lambda1 effects. Our study suggests that IFN-lambda therapy should be suited for patients with verrucae, melanomas and non-melanoma skin cancers, apart from patients with viral hepatitis, and would not be accompanied by immune-mediated complications known from type I IFN application.

Interferon-lambda is functionally an interferon but structurally related to the interleukin-10 family

Interferon-lambda (IFN-lambda) is an antiviral cytokine that signals through a distinct receptor complex, composed of the IFN-lambdaR1 and interleukin-10R2 (IL-10R2) receptor chains. We have determined the crystal structure of human IFN-lambda3 and characterized the interaction with its receptor complex through structure-based site-directed mutagenesis. The ability of IFN-lambda3 mutants to signal was determined by measuring the antiviral activity and induced STAT2 phosphorylation. In conclusion, our data show that, although IFN-lambda is functionally an interferon, it is clearly structurally related to members of the IL-10 family. In particular, we found an interesting similarity between IFN-lambda and IL-22, and we suggest that IFN-lambda and IL-22 possess parallel functions, protecting epithelial tissue against viral and bacterial infections, respectively.

Interferon-lambdas: the modulators of antivirus, antitumor, and immune responses

IFN-lambdas, including IFN-lambda1, IFN-lambda2, and IFN-lambda3, also known as IL-29, IL-28A, or IL-28B, are a newly described group of cytokines distantly related to the type I IFNs and IL-10 family members. The IFN-lambdaR complex consists of a unique ligand-binding chain, IFN-lambdaR1 (also designated IL-28Ralpha), and an accessory chain, IL-10R2, which is shared with receptors for IL-10-related cytokines. IFN-lambdas signal through the IFN-lambdaR and activate pathways of JAK-STATs and MAPKs to induce antiviral, antiproliferative, antitumor, and immune responses. In this review, we summarize recent findings about the biology of IFN-lambdas and their pathophysiological roles in viral infection, cancer, and immune responses of the innate and adaptive arms.

IFN-lambda1 (IL-29) inhibits GATA3 expression and suppresses Th2 responses in human naive and memory T cells

IFN-lambda1 (IL-29) plays a novel, emerging role in the inhibition of human Th2 responses. Here, we demonstrate that both naive and memory human CD4(+) T cells express mRNA for the IFN-lambda1-specific receptor, IL-28Ralpha, and are responsive to IFN-lambda1. Expression of Th2 cytokines (IL-4 and IL-13) was suppressed in naive and memory CD4(+) T cells by IFN-lambda1, without affecting their proliferation. Further, acquisition of IL-4Ralpha expression after stimulation was inhibited by IFN-lambda1, as was GATA3 expression. Finally, IFN-lambda1 diminished the change in cell-surface phenotype that accompanies differentiation of "central memory" T cells into "effector memory" T cells. Taken together, our data describe unique immunomodulatory effects of IFN-lambda1 and identify novel mechanisms for the reduction of existing Th2 responses and the regulation of new ones, in circulating naive and memory CD4(+) T cells.

Molecular cloning, expression, and characterization of chicken IFN -lambda

Interferons (IFN) provide a critical first line of defense against viral infection in vertebrates. Moreover, IFN-lambda, a recently identified group of mammalian IFN, has demonstrated antiviral potential in the treatment of mammalian viruses. With the growing concern over such diseases as avian influenza (AI), there is a pressing need for new antiviral strategies to manage problem viruses in poultry. Furthermore, the use of immune molecules, such as IFN-lambda, provides an attractive option for treating poultry by augmenting the host response to virus. With this in mind, we report here the first cloning, expression, and analysis of biologic activity of chicken IFN-lambda (ChIFN-lambda). We compared the similarity of ChIFN-lambda to those identified in other species and demonstrate that ChIFN-lambda has antiviral properties similar to those of human IFN-lambda (HuIFN-lambda). Our results demonstrate that in the chicken, as in human, the antiviral activity demonstrated by ChIFN-lambda supports its inclusion in therapeutic strategies directed against viral infections.

Human TRIM gene expression in response to interferons

BACKGROUND

Tripartite motif (TRIM) proteins constitute a family of proteins that share a conserved tripartite architecture. The recent discovery of the anti-HIV activity of TRIM5alpha in primate cells has stimulated much interest in the potential role of TRIM proteins in antiviral activities and innate immunity.

PRINCIPAL FINDINGS

To test if TRIM genes are up-regulated during antiviral immune responses, we performed a systematic analysis of TRIM gene expression in human primary lymphocytes and monocyte-derived macrophages in response to interferons (IFNs, type I and II) or following FcgammaR-mediated activation of macrophages. We found that 27 of the 72 human TRIM genes are sensitive to IFN. Our analysis identifies 9 additional TRIM genes that are up-regulated by IFNs, among which only 3 have previously been found to display an antiviral activity. Also, we found 2 TRIM proteins, TRIM9 and 54, to be specifically up-regulated in FcgammaR-activated macrophages.

CONCLUSIONS

Our results present the first comprehensive TRIM gene expression analysis in primary human immune cells, and suggest the involvement of additional TRIM proteins in regulating host antiviral activities.

Human interferon-lambda3 is a potent member of the type III interferon family

Type III interferon (IFN) or IFN-lambda is a recently discovered family of IFNs that signal through the same downstream transcription factors as type I IFN but use a separate receptor complex composed of the IL-10R2 and the unique IFN-lambdaR1 receptor chains. We have established a simple and efficient expression system to produce highly pure and active IFN-lambda of the three human IFN-lambda isoforms (IFN-lambda1, -lambda2 and -lambda3) and used this to compare the biological activity of the different IFN-lambda subtypes. Surprisingly, we found IFN-lambda3 to possess the highest specific activity of the human IFN-lambda subtypes, exhibiting a twofold higher activity than IFN-lambda1 and a 16-fold higher activity than IFN-lambda2. Furthermore, in comparison with the commercially available preparations of IFN-lambda1 and -lambda2, we found our IFN-lambda preparation to be superior in activity.

Differentiated human alveolar type II cells secrete antiviral IL-29 (IFN-lambda 1) in response to influenza A infection

Alveolar type II epithelial cells (ATIIs) are one of the primary targets for influenza A pneumonia. The lack of a culture system for maintaining differentiated ATIIs hinders our understanding of pulmonary innate immunity during viral infection. We studied influenza A virus (IAV)-induced innate immune responses in differentiated primary human ATIIs and alveolar macrophages (AMs). Our results indicate that ATIIs, but not AMs, support productive IAV infection. Viral infection elicited strong inflammatory chemokine and cytokine responses in ATIIs, including secretion of IL-8, IL-6, MCP-1, RANTES, and MIP-1beta, but not TNF-alpha, whereas AMs secreted TNF-alpha as well as other cytokines in response to infection. Wild-type virus A/PR/8/34 induced a greater cytokine response than reassortant PR/8 virus, A/Phil/82, despite similar levels of replication. IAV infection increased mRNA expression of IFN genes IFN-beta, IL-29 (IFN-lambda1), and IL-28A (IFN-lambda2). The major IFN protein secreted by type II cells was IL-29 and ATIIs appear to be a major resource for production of IL-29. Administration of IL-29 and IFN-beta before infection significantly reduced the release of infectious viral particles and CXC and CC chemokines. IL-29 treatment of type II cells induced mRNA expression of antiviral genes MX1, OAS, and ISG56 but not IFN-beta. IL-29 induced a dose-dependent decrease of viral nucleoprotein and an increase of antiviral genes but not IFN-beta. These results suggest that IL-29 exerts IFN-beta-independent protection in type II cells through direct activation of antiviral genes during IAV infection.

Regulation of apoptosis by type III interferons

OBJECTIVE

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

MATERIALS AND METHODS

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

RESULTS AND CONCLUSIONS

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

A role for IFN-lambda1 in multiple myeloma B cell growth

Multiple myeloma (MM) is a progressive disease that results from dysregulated proliferation of plasma cells. Although, causative factors such as genetic events and altered expression of anti-apoptotic factors have been described in a number of patients, the mechanistic details that drive myeloma development and continued growth of malignant cells remain largely undefined. Numerous growth factors, including interleukin (IL)-6, Insulin-like growth factor-1 and IL-10 have been shown to promote growth of MM cells suggesting a significant role for cytokines in this disease. Interferon (IFN)-lambda1 is a new member of the Class II cytokine family that, similar to IFN-alpha, has been shown to mediate viral immunity. In light of data supporting a role for cytokines in myeloma, we investigated the significance of IFN-lambda1 on myeloma cell biology. Our studies show for the first time that myeloma cells bind to soluble IFN-lambda1, and that IFN-lambda1 induces myeloma cell growth and protects against dexamethasone-induced cell death. Our data also show that IFN-lambda1 induces phosphorylation of STAT1, STAT3 and Erk. Taken together, our results suggest that IFN-lambda1 may regulate myeloma cell biology and could prove to be therapeutically important.

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

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

Interleukin-29 functions cooperatively with interferon to induce antiviral gene expression and inhibit hepatitis C virus replication

The interferon (IFN)-related cytokine interleukin (IL)-29 (also known as IFN-lambda1) inhibits virus replication by inducing a cellular antiviral response similar to that activated by IFN-alpha/beta. However, because it binds to a unique receptor, this cytokine may function cooperatively with IFN-alpha/beta or IFN-gamma during natural infections to inhibit virus replication, and might also be useful therapeutically in combination with other cytokines to treat chronic viral infections such as hepatitis C (HCV). We therefore investigated the ability of IL-29 and IFN-alpha or IFN-gamma to cooperatively inhibit virus replication and induce antiviral gene expression. Compared with the individual cytokines alone, the combination of IL-29 with IFN-alpha or IFN-gamma was more effective at blocking vesicular stomatitis virus and HCV replication, and this cooperative antiviral activity correlated with the magnitude of induced antiviral gene expression. Although the combined effects of IL-29 and IFN-alpha were primarily additive, the IL-29/IFN-gamma combination synergistically induced multiple genes and had the greatest antiviral activity. Two different mechanisms contributed to the enhanced gene expression induced by the cytokine combinations: increased activation of ISRE promoter elements and simultaneous activation of both ISRE and GAS elements within the same promoter. These findings provide new insight into the coregulation of a critical innate immune response by functionally distinct cytokine families.