Sean Doyle

Interleukin-29 uses a type 1 interferon-like program to promote antiviral responses in human hepatocytes†

Interleukin‐28A (IL‐28A), IL‐28B and IL‐29 are a family of class II cytokines that stimulate antiviral responses through a heterodimeric receptor that is distinct from the type I interferon (IFN) receptor. To better understand how this newly described family of cytokines regulates the antiviral state, we compared various cellular responses elicited by IL‐29 and IFN‐α. Here we show that these cytokines stimulate similar patterns of signal transducer and activator of transcription 1 (STAT‐1), ‐2, ‐3, and ‐5 phosphorylation and nearly identical patterns of gene expression when analyzed in two distinct cell types by microarray analysis. Interestingly, the IL‐29 receptor is preferentially expressed on primary hepatocytes within normal liver and pegylated forms of IL‐29 and IFN‐α induced equivalent 2′5′ oligoadenylate synthetase (OAS) and MX1 gene expression in this cell type. Pegylated IL‐29 also produced a significant reduction in human hepatitis B and hepatitis C viral load in vitro and reduced the cytopathic effect caused by the fully replicating flavivirus, West Nile virus. In conclusion, IL‐29 and IFN‐α stimulate identical antiviral responses despite their utilization of different receptors. This fact, combined with significant receptor expression in hepatitis virus‐infected livers, suggests that IL‐29 may have therapeutic value against chronic viral hepatitis in human patients. (HEPATOLOGY 2006;44:896–906.)

IL‐28A (IFN‐λ2) modulates lung DC function to promote Th1 immune skewing and suppress allergic airway disease

IL‐28 (IFN‐λ) cytokines exhibit potent antiviral and antitumor function but their full spectrum of activities remains largely unknown. Recently, IL‐28 cytokine family members were found to be profoundly down‐regulated in allergic asthma. We now reveal a novel role of IL‐28 cytokines in inducing type 1 immunity and protection from allergic airway disease. Treatment of wild‐type mice with recombinant or adenovirally expressed IL‐28A ameliorated allergic airway disease, suppressed Th2 and Th17 responses and induced IFN‐γ. Moreover, abrogation of endogenous IL‐28 cytokine function in IL‐28Rα−/− mice exacerbated allergic airway inflammation by augmenting Th2 and Th17 responses, and IgE levels. Central to IL‐28A immunoregulatory activity was its capacity to modulate lung CD11c+ dendritic cell (DC) function to down‐regulate OX40L, up‐regulate IL‐12p70 and promote Th1 differentiation. Consistently, IL‐28A‐mediated protection was absent in IFN‐γ−/− mice or after IL‐12 neutralization and could be adoptively transferred by IL‐28A‐treated CD11c+ cells. These data demonstrate a critical role of IL‐28 cytokines in controlling T cell responses in vivo through the modulation of lung CD11c+ DC function in experimental allergic asthma.

Type III IFNs Are Produced by and Stimulate Human Plasmacytoid Dendritic Cells

Plasmacytoid dendritic cells (pDC) are rare cells found in peripheral blood and lymphoid tissues. pDC are considered to be “professional” type I IFN-producing cells and produce 10- to 100-fold more IFN-α than other cell types in response to enveloped viruses or synthetic TLR7 and TLR9 agonists. In this study, purified pDC were found to express high levels of IFN-λ receptor mRNA, as well as cell-surface IFN-λ receptor. We have developed intracellular flow cytometry assays using Abs to IFN-λ1/3 or -λ2 to assess the expression of IFN-λ proteins by pDC. We observed that a subset of human pDC expresses only intracellular IFN-α, whereas another subset produces both IFN-α and IFN-λ after stimulation with virus or the TLR9 agonist, CpG A; the cells that coexpressed IFN-α and IFN-λ were the cells with the highest levels of IFN-α expression. Ab cross-linking of CD4 or CD303 molecules on pDC inhibited both HSV-induced IFN-λ and IFN-α production. Like the production of IFN-α, the HSV-induced IFN-λ production in pDC was mediated through TLR9 and independent of virus replication. Exogenous IFN-λ treatment of pDC resulted in increased virus-induced expression of both IFN-α and IFN-λ. In addition, both exogenous IFN-λ and -α inhibited dexamethasone-induced apoptosis of pDC. We conclude that pDC are major producers of IFN-λ1 and -λ2 in response to viral stimulation and also express functional receptors for this cytokine. Thus, IFN-λ can serve as an autocrine signal to strengthen the antiviral response of pDC by increasing IFN-α and IFN-λ production, resulting in prolonged pDC survival.

IFN-λ resolves inflammation via suppression of neutrophil infiltration and IL-1β production

Blazek et al. demonstrate that treatment with IL-28A reduces inflammation in collagen-induced arthritis by restricting the recruitment of IL-1β+ neutrophils.

Activation of Epithelial Signal Transducer and Activator of Transcription 1 by Interleukin 28 Controls Mucosal Healing in Mice With Colitis and Is Increased in Mucosa of Patients With Inflammatory Bowel Disease

BACKGROUND & AIMSnWe investigated the roles of interleukin 28A (also called IL28A or interferon λ2) in intestinal epithelial cell (IEC) activation, studying its effects in mouse models of inflammatory bowel diseases (IBD) and intestinal mucosal healing.nnnMETHODSnColitis was induced in C57BL/6JCrl mice (controls), mice with IEC-specific disruption of Stat1 (Stat1IEC-KO), mice with disruption of the interferon λ receptor 1 gene (Il28ra-/-), and mice with disruption of the interferon regulatory factor 3 gene (Irf3-/-), with or without disruption of Irf7 (Irf7-/-). We used high-resolution mini-endoscopy and inxa0vivo imaging methods to assess colitis progression. We used 3-dimensional small intestine and colon organoids, along with RNA-Seq and gene ontology methods, to characterize the effects of IL28 on primary IECs. We studied the effects of IL28 on the human intestinal cancer cell line Caco-2 in a wound-healing assay, and in mice colon wounds. Colonic biopsies and resected tissue from patients with IBD (nxa0= 62) and patients without colon inflammation (controls, nxa0= 23) were analyzed by quantitative polymerase chain rection to measure expression of IL28A, IL28RA, and other related cytokines; biopsy samples were also analyzed by immunofluorescence to identify sources of IL28 production. IECs were isolated from patient tissues and incubated with IL28; signal transducer and activator of transcription 1 (STAT1) phosphorylation was measured by immunoblots and confocal imaging.nnnRESULTSnLamina propria cells in colon tissues of patients with IBD, and mice with colitis, had increased expression of IL28 compared with controls; levels of IL28R were increased in the colonic epithelium of patients with IBD and mice with colitis. Administration of IL28 induced phosphorylation of STAT1 inxa0primary human and mouse IECs, increasing with dose. Il28ra-/-, Irf3-/-, Irf3-/-Irf7-/-, as well as Stat1IEC-KO mice, developed more severe colitis after administration of dextran sulfate sodium than control mice, with reduced epithelial restitution. Il28ra-/- and Stat1IEC-KO mice also developed more severe colitis in response to oxazolone than control mice. We found IL28 to induce phosphorylation (activation) of STAT1 in epithelial cells, leading to their proliferation in organoid culture. Administration of IL28 to mice with induced colonic wounds promoted mucosal healing.nnnCONCLUSIONSnIL28 controls proliferation of IECs in mice with colitis and accelerates mucosal healing by activating STAT1. IL28 might be developed as a therapeutic agent for patients with IBD.

Peginterferon Lambda-1a, a New Therapeutic for Hepatitis C Infection, from Bench to Clinic.

Chronic infection with hepatitis C virus (HCV) is estimated to affect approximately 3% of the worlds population and cause 350,000 deaths each year. For a number of years, the standard of care has been combination therapy with recombinant alfa interferons—originally as native proteins but more recently as polyethyleneglycol-modified derivatives—and ribavirin, with the recent addition of an NS3 protease inhibitor for HCV genotype 1. However, therapeutic alfa interferons are associated with a significant burden of treatment-limiting adverse events, including musculoskeletal and influenza-like symptoms, hematologic cytopenias, autoimmune disease, fatigue, and other neurologic events. In 2003, a team at ZymoGenetics (now a fully owned subsidiary of Bristol-Myers Squibb) and a second, independent group simultaneously identified a new class of interferons—the type III lambda interferons—with near-identical activity to the type I alfa interferons in hepatocytes but with an unrelated and less ubiquitous receptor. Subsequent evaluation of the type III interferon system demonstrated antiviral activity against HCV in vitro with limited activity in peripheral blood mononuclear cells and other nonhepatocyte cell types, supporting its development as a potentially better-tolerated therapy for viral hepatitis. Peginterferon lambda-1a (Lambda) is an investigational type III therapeutic agent originally developed at ZymoGenetics that is currently in Phase 3 studies for the treatment of HCV. In this review, we describe the selection of the Lambda molecule and its preclinical and early clinical development, and how the resulting data have helped to establish the differentiated safety profile for Lambda—with fewer influenza-like and musculoskeletal symptoms and less hematologic toxicity than the alfa interferons—that was seen in later studies.