Expression Of IFN-λ1 Research Articles

Expression of IFN-λ1 from Congjiang pigs and its effect on anti-PRRSV proliferation.

An eukaryotic expression system of Congjiang pigs IFN-λ1 was constructed to obtain its expression in CHO-K1 cells and the inhibition effect of Congjiang pig IFN-λ1 on PRRSV proliferation was verified. The eukaryotic expression plasmid pEGFP-PoIFN-λ1 was constructed from the pig IFN-λ1 gene fragment and transfected into CHO-K1 cells. Expression was detected by fluorescence microscopy and Western blotting. The influence on the proliferation of PRRSV was assessed. The results of the study showed that the recombinant plasmid pEGFP-PoIFN-λ1 was constructed correctly. After transfection, green fluorescent signal was detected in CHO-K1 cells by fluorescence microscopy. Western blot analysis revealed that in cells at different time periods after transfection, porcine IFN-λ1 was expressed, with the highest expression observed 36 h after transfection. The antiviral activity of the supernatant after 36 h of transfection was determined by the micro cytopathic inhibition method, and the biological activity was 2.1×103 U/mL. Quantitative PCR was used to detect the proliferation of PRRSV, and the results showed that Congjiang pigs IFN-λ1 significantly inhibited the mRNA expression of PRRSV and viral proliferation in a dose- and time-dependent manner. This study established a Congjiang pig IFN-λ1 eukaryotic expression system, and the quantitative PCR method showed that it has a significant inhibitory effect on the proliferation of PRRSV, which lays a foundation for the future production of antiviral drugs and clinical application.

Dendritic cells-derived interferon-\u03bb1 ameliorated inflammatory bone destruction through inhibiting osteoclastogenesis

Bone infection contributing to inflammatory osteolysis is common in orthopedic surgery. The dynamic balance between bone formation and bone resorption is destroyed due to excessive osteoclast fusion and differentiation, which results in severe bone matrix loss. Many therapeutic approaches that restrain osteoclast formation and function act as efficient ways to prevent inflammatory bone erosion. We have demonstrated for the first time that dendritic cells-derived interferon-λ1 (IFN-λ1) inhibited inflammatory bone destruction in vivo and explored its underlying mechanisms on osteoclast formation in vitro. We found that IFN-λ1 was highly expressed in infectious bone tissue compared with that of non-infectious bone tissue. Additionally, dendritic cells marker genes such as CD80, CD86, and CD1a were higher expressed in infectious bone tissue than that of non-infectious bone tissue. Dendritic cells that were pretreated with LPS showed high expression of IFN-λ1. Moreover, conditioned medium of LPS-pretreated dendritic cells significantly inhibited osteoclast differentiation, as determined by TRAP staining assay. This suppressive effect was reversed by adding an IFN-λ1 monoclonal antibody. It was also investigated whether exogenous IFN-λ1 restrained osteoclastogenesis, bone resorption, F-actin ring formation, osteoclast-specific gene expression, release of pro-inflammatory cytokines, and translocation of p65 and NFATc1 by preventing the NF-κB signaling pathway and NLRP3 inflammasome formation, as well as by inducing the JAK-STAT signaling pathways in vitro. In vivo study indicated that IFN-λ1 prevents lipopolysaccharide (LPS)-induced inflammatory bone destruction by inhibiting excessive osteoclast fusion and bone resorption activity. In conclusion, our findings confirmed that dendritic cells-derived IFN-λ1 could attenuate osteoclast formation and bone resorptive activity in vitro and in vivo. These novel findings pave the way for the use of exogenous IFN-λ1 as a potential therapeutic treatment for excessive osteoclast-related diseases, such as inflammatory osteolysis, by regulating osteoclastogenesis to maintain the dynamic balance between bone formation and bone resorption.

IFN-λ1 enhances Staphylococcus aureus clearance in healthy nasal mucosa but not in nasal polyps

Chronic rhinosinusitis with nasal polyps (CRSwNP) is characterized by TH2-skewed inflammation and increased colonization by Staphylococcus aureus. IFN-λ1 is known for its antiviral activity, but there is little information on its antibacterial role. We sought to determine the expression and release of IFN-λ1 from nasal mucosal tissue of healthy subjects and patients with CRSwNP on exposure to S aureus and assess its potential role in antibacterial defense mechanisms. Nasal tissue from healthy subjects and patients with CRSwNP was exposed to S aureus, and we assessed expression of IFN-λ1, MUC5AC, and MUC5B. THP1-derived macrophages incubated with or without IFN-λ1 were assessed for uptake and killing of S aureus and expression of lysosomal-associated membrane protein 1 and intracellular reactive oxidase substrate (ROS), the IFN-λ1 receptor IL-28 receptor (IL-28R), and the Janus kinase/signal transducer and activator of transcription (STAT) 1 pathway by means of immunofluorescence staining. S aureus infection increased IFN-λ1 expression in tissue from patients with CRSwNP. IFN-λ1 (10ng/mL) significantly decreased the number of S aureus colony-forming units in healthy control tissue but not in tissue from patients with CRSwNP and upregulated MUC5AC and MUC5B expression in control tissue on S aureus infection. IFN-λ1 stimulation increased intracellular killing of S aureus in THP1-derived macrophages and substantially increased lysosomal-associated membrane protein 1, IL-28R, ROS, and STAT signaling in macrophages incubated with S aureus. All of these effects were attenuated by blocking IL-28R and ROS activities. IFN-λ1 favors clearance of S aureus in healthy nasal mucosa and enhances antibacterial function of macrophages through IFN-λ1-IL-28R-ROS-Janus kinase-STAT signaling pathways.

MRNA expression of IFN-λs in the gingival tissue of patients with chronic or aggressive periodontitis: A polymerase chain reaction study.

Several studies have proven the existence of herpesviruses in periodontal pockets of patients with chronic or aggressive periodontitis. Recently discovered interferon lambda (IFN-λ) has antiviral properties and is induced by herpesviruses. The present study was a quantitative analysis of messenger RNA (mRNA) expression of IFN-λs (IFN-λ1, IFN-λ2, IFN-λ3) in the gingival tissues of patients with chronic or aggressive periodontitis. A total of 90 participants (50 men and 40 women; age range 19-50 years, mean age 31.50 ± 7.8) were categorized into three groups: healthy participants, patients with chronic periodontitis, and patients with aggressive periodontitis. mRNA expression of IFN-λs in gingival tissues was estimated using reverse transcriptase polymerase chain reaction and was correlated with clinical parameters such as gingival index (GI), probing pocket depth (PPD), and clinical attachment level (CAL). mRNA of IFN-λ1, IFN-λ2, and IFN-λ3 was expressed in gingival tissues of healthy participants and in patients with chronic or aggressive periodontitis. The highest level of IFN-λ1 was observed in patients with aggressive periodontitis (3.049 ± 9.793), whereas IFN-λ2 (4.322 ± 11.310) and IFN-λ3 (11.932 ± 27.479) were highest in patients with chronic periodontitis. The difference in mRNA expression of IFN-λ1 (P=0.008) and IFN-λ3 (P=0.043) among three groups was statistically significant CONCLUSION: Increased quantity of IFN-λs in patients with chronic and patients with aggressive periodontitis suggests a role in periodontitis. Variation in the expression of IFN-λ1 and IFN-λ3 in patients with periodontitis needs to be further evaluated. The mRNA expression of antiviral IFN-λs in gingival tissues might enhance our understanding related to viral pathogenesis of periodontal diseases.

HERP Binds TBK1 To Activate Innate Immunity and Repress Virus Replication in Response to Endoplasmic Reticulum Stress.

Host innate immunity is crucial for cellular responses against viral infection sensed by distinct pattern recognition receptors and endoplasmic reticulum (ER) stress. Enterovirus 71 (EV71) is a causative agent of hand, foot, and mouth disease and neurological diseases. However, the exact mechanism underlying the link between ER stress induced by EV71 infection and host innate immunity is largely unknown. In this study, we demonstrated that EV71 infection induces the homocysteine-induced ER protein (HERP), a modulator of the ER stress response which is dependent on the participation of MAVS. Virus-induced HERP subsequently stimulates host innate immunity to repress viral replication by promoting type-I IFNs (IFN-α and IFN-β) and type-III IFN (IFN-λ1) expression. Through interacting with TANK-binding kinase 1, HERP amplifies the MAVS signaling and facilitates the phosphorylation and nuclear translocation of IFN regulatory factor 3 and NF-κB to enhance the expression of IFNs, which leads to a broad inhibition of the replication of RNA viruses, including EV71, Sendai virus, influenza A virus, and vesicular stomatitis virus. Therefore, we demonstrated that HERP plays an important role in the regulation of host innate immunity in response to ER stress during the infection of RNA viruses. These findings provide new insights into the mechanism underlying the replication of RNA viruses and the production of IFNs, and also demonstrate a new role of HERP in the regulation of host innate immunity in response to viral infection.

An IFIH1 gene polymorphism associated with risk for autoimmunity regulates canonical antiviral defence pathways in Coxsackievirus infected human pancreatic islets.

The IFIH1 gene encodes the pattern recognition receptor MDA5. A common polymorphism in IFIH1 (rs1990760, A946T) confers increased risk for autoimmune disease, including type 1-diabetes (T1D). Coxsackievirus infections are linked to T1D and cause beta-cell damage in vitro. Here we demonstrate that the rs1990760 polymorphism regulates the interferon (IFN) signature expressed by human pancreatic islets following Coxsackievirus infection. A strong IFN signature was associated with high expression of IFNλ1 and IFNλ2, linking rs1990760 to the expression of type III IFNs. In the high-responding genotype, IRF-1 expression correlated with that of type III IFN, suggesting a positive-feedback on type III IFN transcription. In summary, our study uncovers an influence of rs1990760 on the canonical effector function of MDA5 in response to an acute infection of primary human parenchymal cells with a clinically relevant virus linked to human T1D. It also highlights a previously unrecognized connection between the rs1990760 polymorphism and the expression level of type III IFNs.

(-)-Epigallocatechin-3-Gallate Enhances Hepatitis C Virus Double-Stranded RNA Intermediates-Triggered Innate Immune Responses in Hepatocytes.

(−)-Epigallocatechin-3-gallate (EGCG), a major polyphenol component of green tea, has recently been identified as an inhibitor of hepatitis C virus (HCV) entry. Here, we examined whether EGCG can enhance hepatocyte-mediated intracellular innate immunity against HCV. HCV dsRNAs (Core, E1-P7, NS-3′NTR and NS5A) induced interferon-λ1 (IFN-λ1) expression in human hepatocytes. These HCV dsRNAs also induced the expression of Toll-like receptor 3 (TLR3), retinoic acid-inducible gene I (RIG-I) and several antiviral IFN-stimulated genes (ISGs) expression. Although EGCG treatment of hepatocytes alone had little effect on TLR3 and RIG-I signaling pathways, EGCG significantly enhanced HCV dsRNAs-induced the expression of IFN-λ1, TLR3, RIG-I and antiviral ISGs in hepatocytes. Furthermore, treatment of HCV-infected hepatocytes with EGCG and HCV dsRNAs inhibited viral replication. Given that EGCG has the ability to enhance HCV dsRNAs-induced intracellular antiviral innate immunity against HCV, suggesting the potential application of EGCG as a new anti-HCV agent for HCV therapy.

Elevated Plasma Level of Interferon-λ1 in Chronic Spontaneous Urticaria: Upregulated Expression in CD8(+) and Epithelial Cells and Induction of Inflammatory Cell Accumulation.

Interferon- (IFN-) λ1 is regarded as a potent bio-active molecule in innate immunity. However, little is known about its role in chronic spontaneous urticaria (CSU). We therefore investigated expression of IFN-λ1 in CSU, its cellular location, and its influence on inflammatory cell accumulation by using flow cytometry analysis, skin tissue dispersion, immunohistochemical stain, and a mouse peritoneal inflammation model. The results showed that level of IFN-λ1 was 2.0-fold higher in plasma of the patients with CSU than the level in healthy control (HC) subjects. Among leukocytes examined, only CD8+ T cells expressed more IFN-λ1 in CSU blood. Double labeling immunohistochemical staining revealed that IFN-λ1+ inflammatory cells such as mast cells, eosinophils, B cells, neutrophils, and macrophages were mainly located in dermis, whereas epidermis tissue highly expressed IFN-λ1. IFN-λ1 induced a dose-dependent increase in number of eosinophils, lymphocytes, mast cells, macrophages, and neutrophils in the peritoneum of mice at 6 h following injection, which was inhibited by pretreatment of the animals with anti-intercellular adhesion molecule- (ICAM-) 1 and/or anti-L-selectin antibodies. In conclusion, IFN-λ1 is likely to play a role in the pathogenesis of CSU. Blocking IFN-λ1 production may help to reduce the accumulation of inflammatory cells in the involved CSU skin.

Activation of Toll-like receptor 7 regulates the expression of IFN-λ1, p53, PTEN, VEGF, TIMP-1 and MMP-9 in pancreatic cancer cells.

Toll-like receptors (TLRs) are critical in the induction of the immune response in tumor development. TLR7 has previously been demonstrated to be associated with the development of pancreatic cancer, and the release of cytokines and chemokines from other types of cancer cell; however, the specific expression induced by TLR7 agonists in pancreatic cancer cells remains to be elucidated. The present study aimed to investigate the effects of the TLR7 agonist, gardiquimod, on ERK1/2 signaling pathway, and on the expression of genes involved in the pathogenesis of cancer, including phosphatase and tensin homolog deleted on chromosome 10 (PTEN), p53, type Ⅲ interferon (IFN-λ1), vascular endothelial growth factor (VEGF), matrix metalloproteinase 9 (MMP-9) and tissue inhibitor of metalloproteinase 1 (TIMP-1). The results demonstrated that activation of TLR7 upregulated the expression levels of certain genes to varying degrees; the expression levels of IFN-λ1 and MMP-9 were increased by ~3 fold, whereas other genes (p53, PTEN, TIMP-1) were upregulated by ~2 fold, and VEGF was marginally upregulated after 10 min. Furthermore, gardiquimod increased the expression levels of phosphorylated-extracellular signal-regulated kinase (ERK)1/2. In addition, PD98059, a specific inhibitor of ERK phosphorylation, inhibited the ability of gardiquimod to activate ERK1/2; consequently weakening the effect of gardiquimod on gene regulation. These findings indicated that the effect of TLR7 agonists, including gardiquimod, on gene expression in BxPC-3 pancreatic cancer cells was partly associated with the mitogen-activated protein kinase-ERK1/2 signaling pathway.

Immunostimulatory Defective Viral Genomes from Respiratory Syncytial Virus Promote a Strong Innate Antiviral Response during Infection in Mice and Humans.

Human respiratory syncytial virus (RSV) is a major cause of severe respiratory illness in children and susceptible adults. RSV blocks the development of the innate antiviral immune response and can grow to high titers in the respiratory tract. Here we demonstrate that immunostimulatory defective viral genomes (iDVGs) that are naturally generated during RSV replication are strong inducers of the innate antiviral response to RSV in mice and humans. In mice, RSV iDVGs stimulated the expression of antiviral genes, restricted viral replication, and prevented weight loss and lung inflammation. In human cells, the antiviral response to RSV iDVGs was dominated by the expression of IFN-λ1 over IFN-β and was driven by rapid intranuclear accumulation of the transcription factor IRF1. RSV iDVGs were detected in respiratory secretions of hospitalized patients, and their amount positively correlated with the level of expression of antiviral genes in the samples. Infection of explanted human lung tissue from different donors revealed that most humans can respond to RSV iDVGs and that the rate of accumulation of iDVGs during infection directly correlates with the quality of the antiviral response. Taken together, our data establish iDVGs as primary triggers of robust antiviral responses to RSV and provide the first evidence for an important biological role for naturally occurring iDVGs during a paramyxovirus infection in humans.

HIV-1 Treated Patients with Undetectable Viral Loads have Lower Levels of Innate Immune Responses via Cytosolic DNA Sensing Systems Compared with Healthy Uninfected Controls.

ObjectivesAfter DNA or RNA virus infection, cytosolic foreign DNA or RNA derived from the infecting viruses is recognized by intracellular pathogen recognition receptors (PRRs) and induces activation of the innate immune system. Transfection of DNA has been used as an experimental model for DNA virus-mediated innate responses. We have previously reported that DNA transfection preferentially induces Type-III IFN (IFN-λ1) rather than Type-I IFN (IFN-β). In this study, we compared the DNA-mediated immune response between healthy controls and HIV-1 infected patients with undetectable viral loads and assessed potential innate immune responses in these patients.MethodsThe study consisted of 50 HIV-1 negative healthy donors, 46 patients on combination antiretroviral therapy with HIV-1 viral loads <50 copies/ml and 7 long term non-progressors (LTNPs). PBMCs were isolated from whole blood using Ficoll-Paque. DNA transfection was performed using Lipofectamine 2000. After 22 hours incubation, total cellular RNA was extracted and real time RT-PCR was performed to determine gene expression level of IFN-λ1, IFN-β and RANTES. Gene induction was compared by fold change.ResultsBaseline levels of endogenous gene expression of IFN-λ1, IFN-β and RANTES in HIV-1 patients were higher than in controls. Following DNA transfection, both HIV infected patients and healthy controls induced gene induction, however, the induction in HIV-1 patients was at a significantly lower level compared to uninfected controls.ConclusionHIV-1 treated patients with undetectable viral loads have lower levels of innate immune responses via cytosolic DNA sensing systems. This may be caused by persistent immune activation.

Inducible Interleukin 32 (IL-32) Exerts Extensive Antiviral Function via Selective Stimulation of Interferon λ1 (IFN-λ1)

Interleukin (IL)-32 has been recognized as a proinflammatory cytokine that participates in responses to viral infection. However, little is known about how IL-32 is induced in response to viral infection and the mechanisms of IL-32-mediated antiviral activities. We discovered that IL-32 is elevated by hepatitis B virus (HBV) infection both in vitro and in vivo and that HBV induced IL-32 expression at the level of both transcription and post-transcription. Furthermore, microRNA-29b was found to be a key factor in HBV-regulated IL-32 expression by directly targeting the mRNA 3'-untranslated region of IL-32. Antiviral analysis showed that IL-32 was not sufficient to alter HBV replication in HepG2.2.15 cells. To mimic the viremic phase of viral infection, freshly isolated peripheral blood mononuclear cells were treated with IL-32γ, the secretory isoform, and the supernatants were used for antiviral assays. Surprisingly, these supernatants exhibited extensive antiviral activity against multiplex viruses besides HBV. Thus, we speculated that the IL-32γ-treated peripheral blood mononuclear cells produced and secreted an unknown antiviral factor. Using antibody neutralization assays, we identified the factor as interferon (IFN)-λ1 and not IFN-α. Further studies indicated that IL-32γ effectively inhibited HBV replication in a hydrodynamic injection mouse model. Clinical data showed that elevated levels of IFN-λ1 both in serum and liver tissue of HBV patients were positively correlated to the increased levels of IL-32. Our results demonstrate that elevated IL-32 levels during viral infection mediate antiviral effects by stimulating the expression of IFN-λ1.

MicroRNA-548 down-regulates host antiviral response via direct targeting of IFN-λ1

Interferon (IFN)-mediated pathways are a crucial part of the cellular response against viral infection. Type III IFNs, which include IFN-λ1, 2 and 3, mediate antiviral responses similar to Type I IFNs via a distinct receptor complex. IFN-λ1 is more effective than the other two members. Transcription of IFN-λ1 requires activation of IRF3/7 and nuclear factor-kappa B (NF-κB), similar to the transcriptional mechanism of Type I IFNs. Using reporter assays, we discovered that viral infection induced both IFN-λ1 promoter activity and that of the 3'-untranslated region (UTR), indicating that IFN-λ1 expression is also regulated at the post-transcriptional level. After analysis with microRNA (miRNA) prediction programs and 3'UTR targeting site assays, the miRNA-548 family, including miR-548b-5p, miR-548c-5p, miR-548i, miR-548j, and miR-548n, was identified to target the 3'UTR of IFN-λ1. Further study demonstrated that miRNA-548 mimics down-regulated the expression of IFN-λ1. In contrast, their inhibitors, the complementary RNAs, enhanced the expression of IFN-λ1 and IFN-stimulated genes. Furthermore, miRNA-548 mimics promoted infection by enterovirus-71 (EV71) and vesicular stomatitis virus (VSV), whereas their inhibitors significantly suppressed the replication of EV71 and VSV. Endogenous miRNA-548 levels were suppressed during viral infection. In conclusion, our results suggest that miRNA-548 regulates host antiviral response via direct targeting of IFN-λ1, which may offer a potential candidate for antiviral therapy.

Epigenetic Changes Mediated by MicroRNA miR29 Activate Cyclooxygenase 2 and Lambda-1 Interferon Production during Viral Infection

Lambda-1 interferon (IFN-λ1) and cyclooxygenase-2 (COX-2) were reported to play an important role in host antiviral defense. However, the mechanism by which IFN-λ1 and COX2 are activated and modulated during viral infection remains unclear. In this study, we found that expression of both circulating IFN-λ1 and COX2-derived prostaglandin E2 (PGE2) was coordinately elevated in a cohort of influenza patients compared to healthy individuals. Expression of IFN-λ1 was blocked by a selective COX2 inhibitor during influenza A virus infection in A549 human lung epithelial cells but enhanced by overexpression of COX2, indicating that the production of IFN-λ1 is COX2 dependent. COX2 was able to increase IFN-λ1 expression by promoting NF-κB binding to the enhancer in the IFN-λ1 promoter. We found that epigenetic changes activate COX2 expression and PGE2 accumulation during viral infection. The expression of DNA methyltransferase 3a (DNMT3a) and DNMT3b, but not that of DNMT1, was downregulated following influenza A virus infection in both A549 cells and peripheral blood mononuclear cells (PBMCs). We showed that microRNA miR29 suppresses DNMT activity and thus induces expression of COX2 and PGE2. Furthermore, miR29 expression was elevated 50-fold in virally infected A549 cells and 10-fold in PBMCs from influenza patients, compared to expression after mock infection of A549 cells or in healthy individuals, respectively. Activation of the protein kinase A signaling pathway and phosphorylation of CREB1 also contributed to COX2 expression. Collectively, our work defines a novel proinflammatory cascade in the control of influenza A virus infection.

Induction of interferon‐λ contributes to toll‐like receptor 3‐mediated herpes simplex virus type 1 inhibition in astrocytes

Toll-like receptor 3 (TLR3) recognizes double-stranded RNA and induces type I interferon (IFN)-mediated antiviral immunity against a number of viral infections. Type III IFN (IFN-λ) is a newly identified antiviral cytokine that has biological functions similar to those of type I IFNs. We thus investigated the role of IFN-λ in TLR3 activation-mediated inhibition of herpes simplex virus type 1 (HSV-1) in human primary astrocytes. Human astrocytes express endogenous IFN-λ1 and IFN-λ receptor complex, interleukin-28 receptor α subunit (IL-28Rα), and IL-10Rβ. The activation of TLR3 by poly-I:C treatment significantly induced the expression of IFN-λ1 and IFN-λ2/3 in astrocytes. The induction of IFN-λ contributed to TLR3 activation-mediated HSV-1 inhibition in astrocytes. Investigation of the mechanisms showed that treatment of astrocytes with specific antibody against IFN-λ receptor attenuated the anti-HSV-1 activity of poly-I:C, indicating that endogenous IFN-λ contributes to the anti-HSV-1 effect of TLR3 activation. The anti-HSV-1 effect of endogenous IFN-λ was also confirmed by the finding that recombinant IFN-λ treatment inhibited HSV-1 infection of astrocytes. These results provide direct and compelling evidence that endogenous IFN-λ participates in TLR3-mediated antiviral activity, which may have important implications in host cell innate immunity against HSV-1 infection in the CNS.

Inhibition of dynamin-dependent endocytosis interferes with type III IFN expression in bacteria-infected human monocyte-derived DCs.

Type I IFNs (IFN-α/βs) and type III IFNs (IFN-λ1-3) play an important role in host defense against viral infections. The induction of type I IFNs has recently been found to take place also in bacterial infections, and therefore, this study focuses on analyzing the regulation of type III IFNs in response to bacterial stimulation. We found by quantitative RT-PCR that the expression of IFN-λ1 and IFN-λ2/3 mRNAs, as well as that of IFN-β, was similarly up-regulated in response to stimulation with live Salmonella typhimurium or TLR4 agonist LPS in human moDCs. The induction of IFN-λ mRNAs did not require ongoing protein synthesis, and only IFN-λ1 was detected at the protein level. The induction of IFN-λ mRNAs was sensitive to SB202190, Ly294002, and PDTC, which inhibit p38 MAPK, PI3K, and NF-κB activation, respectively. Furthermore, we observed that blocking dynamin-dependent endocytosis pathways with dynasore led to decreased cell surface expression of CD86 and HLA class II molecules and reduced production of IFN-λ1, CXCL10, and IL-6 when the cells were infected with S. typhimurium. Cytokine production was also impaired in dynasore-treated, Streptococcus thermophilus-stimulated cells. Further, inhibition of dynamin prevented S. typhimurium-induced phosphorylation of IRF3 and the internalization of the bacteria. In summary, induction of type III IFNs in bacteria-infected human moDCs requires multiple signaling pathways and involves bacterial phagocytosis.

269 Coordinated expression of IFN-λ1 and IL-4, a novel feedback loop leading to the reduction of Th2 responses

269 Coordinated expression of IFN-λ1 and IL-4, a novel feedback loop leading to the reduction of Th2 responses

Lambda Interferon (IFN-λ), a Type III IFN, Is Induced by Viruses and IFNs and Displays Potent Antiviral Activity against Select Virus Infections In Vivo

Type III interferons (IFNs) (interleukin-28/29 or lambda interferon [IFN-lambda]) are cytokines with IFN-like activities. Here we show that several classes of viruses induce expression of IFN-lambda1 and -lambda2/3 in similar patterns. The IFN-lambdas were-unlike alpha/beta interferon (IFN-alpha/beta)-induced directly by stimulation with IFN-alpha or -lambda, thus identifying type III IFNs as IFN-stimulated genes. In vitro assays revealed that IFN-lambdas have appreciable antiviral activity against encephalomyocarditis virus (EMCV) but limited activity against herpes simplex virus type 2 (HSV-2), whereas IFN-alpha potently restricted both viruses. Using three murine models for generalized virus infections, we found that while recombinant IFN-alpha reduced the viral load after infection with EMCV, lymphocytic choriomeningitis virus (LCMV), and HSV-2, treatment with recombinant IFN-lambda in vivo did not affect viral load after infection with EMCV or LCMV but did reduce the hepatic viral titer of HSV-2. In a model for a localized HSV-2 infection, we further found that IFN-lambda completely blocked virus replication in the vaginal mucosa and totally prevented development of disease, in contrast to IFN-alpha, which had a more modest antiviral activity. Finally, pretreatment with IFN-lambda enhanced the levels of IFN-gamma in serum after HSV-2 infection. Thus, type III IFNs are expressed in response to most viruses and display potent antiviral activity in vivo against select viruses. The discrepancy between the observed antiviral activity in vitro and in vivo may suggest that IFN-lambda exerts a significant portion of its antiviral activity in vivo via stimulation of the immune system rather than through induction of the antiviral state.