Modulation of the human cytokine response by interferon lambda-1 (IFN-lambda1/IL-29)

Type III interferons in innate and adaptive immunity in the respiratory tract

Lambda interferons (IFNλs), also termed type III interferons (IFNs) or interleukins-28/29, have been in the shadow of type I IFNs for a long time. Their common induction mechanisms and signalling cascades with type I IFNs have made difficult the unwinding of their unique nonredundant functions. However, this is now changing with mounting evidence supporting a major role of IFNλs as a specialized antiviral defense system in the body, mediating protection at mucosal barrier surfaces while limiting immunopathology. Here, we review the latest progress on the complex activities of IFNλs in the respiratory tract, focusing on their multiple effects in IFNλ receptor-expressing cells, the modulation of innate and adaptive immune responses in the context of infections and respiratory diseases, and their similarities and differences with type I IFNs. We also discuss their potential in therapeutic applications and the most recent developments in that direction.

The role and application of three IFN-related reactions in psoriasis

The pathophysiology of psoriasis is a highly complicated one. Due to the disease's specificity, it not only affects the patient's skin negatively but also manifests systemic pathological changes. These clinical symptoms seriously harm the patient's physical and mental health. IFN, a common immunomodulatory factor, has been increasingly demonstrated to have a significant role in the development of psoriatic skin disease. Psoriasis is connected with a variety of immunological responses. New targets for the therapy of autoimmune skin diseases may emerge from further research on the mechanics of the associated IFN upstream and downstream pathways. Different forms of IFNs do not behave in the same manner in psoriasis, and understanding how different types of IFNs are involved in psoriasis may provide a better notion for future research. This review focuses on the involvement of three types of IFNs in psoriasis and related therapeutic investigations, briefly describing the three IFNs' production and signaling, as well as the dual effects of IFNs on the skin. It is intended that it would serve as a model for future research.

A stimulus-contingent positive feedback loop enables IFN-β dose-dependent activation of pro-inflammatory genes

Type I interferons (IFN) induce powerful antiviral and innate immune responses via the transcription factor, IFN-stimulated gene factor (ISGF3). However, in some pathological contexts, type I IFNs are responsible for exacerbating inflammation. Here, we show that a high dose of IFN-β also activates an inflammatory gene expression program in contrast to IFN-λ3, a type III IFN, which elicits only the common antiviral gene program. We show that the inflammatory gene program depends on a second, potentiated phase in ISGF3 activation. Iterating between mathematical modeling and experimental analysis, we show that the ISGF3 activation network may engage a positive feedback loop with its subunits IRF9 and STAT2. This network motif mediates stimulus-specific ISGF3 dynamics that are dependent on ligand, dose, and duration of exposure, and when engaged activates the inflammatory gene expression program. Our results reveal a previously underappreciated dynamical control of the JAK-STAT/IRF signaling network that may produce distinct biological responses and suggest that studies of type I IFN dysregulation, and in turn therapeutic remedies, may focus on feedback regulators within it.

Enhanced production of interleukin-29 and related genes are associated with T helper 1 cell parameters in patients with type 2 diabetes mellitus

OBJECTIVE

The production of interleukin (IL)-29 andthe genes related to IL-29 signaling pathway (STAT1, NF-κB, and NFATc1), and T helper (Th) 1 cells (T-bet, IFN-γ, TNF-α, and IL-2) were evaluated in type 2 diabetes mellitus (T2DM). Correlations between IL-29 and diabetes parameters, and between gene expression in IL-29 pathway and Th1 cells were also examined.

MATERIALS AND METHODS

41 newly diagnosed patients with T2DM and 41 healthy controls were recruited. CD4⁺ T cells were purifed and the production of IL-29 in the supernatant of anti- CD3 and anti- CD28 activated Th cells was detected using ELISA. The expression of IL-29- and Th1- related genes was determined with real-time PCR.

RESULTS

The secretion of IL-29 and the expression levels of NF-κB, NFATc1, IFN-γ, and TNF-α in Th cells were seen to be increased in diabetes persons compared to controls. Positive connections between IL-29 with hemoglobin A1c (HbA1c) and fasting plasma glucose (FPG) were found in diabetes persons. IL-29 was positively correlated with NFATc1 and TNF-α. NFATc1 was positively related to TNF-α.

CONCLUSION

Abnormal expression levels of IL-29- and Th1- related genes are linked with T2DM pathogenesis. IL-29 may amplify the expression of Th1-specific genes especially TNF-α by upregulating NFATc1 expression.

The Priming Potential of Interferon Lambda-1 for Antiviral Defense in the Oral Mucosa

The oral mucosa is one of the first lines of the innate host defense system against microbial invasion. Interferon (IFN) lambda-1 (IFN-λ1), a type III IFN, exhibits type I IFN-like antiviral activity. In contrast to ubiquitously expressed type I IFN receptors, IFN-λ receptor 1 (IFN-λR1), which has higher affinity for type III IFNs than low-affinity interleukin (IL)-10 receptor 2, is mainly expressed on epithelial cells. Although IFN-λ1 has been shown to exert antiviral effects in the respiratory tract, gastrointestinal tract, and skin, the regulation of type III IFN receptor expression and its functions in the oral mucosa remain unclear. We herein showed the expression of IFN-λR1 in human gingival keratinocytes. The expression of IL-6, angiotensin-converting enzyme 2 (a critical molecule for severe acute respiratory syndrome coronavirus 2 infection), and IL-8 in human primary gingival keratinocytes (HGK) were significantly higher following treatments with either type I IFN (IFN-β) or type II IFN (IFN-γ) than with IFN-λ1. However, the IFN-λ1 treatment strongly induced toll-like receptor (TLR) 3 and retinoic acid-inducible gene I (RIG-I), which mainly recognize viral nucleic acids, via the STAT1-mediated pathway. Furthermore, a stimulation with a RIG-I or TLR3 agonist promoted the production of IL-6, IL-8, and IFN-λ in HGK, which was significantly enhanced by a pretreatment with IFN-λ1. These results suggest that IFN-λ1 may contribute to the activation of innate immune responses to oral viral infections by up-regulating the expression of RIG-I and TLR3 and priming their functions in keratinocytes.

Association Between IL28B, IL29 Gene Polymorphisms and Clinical Manifestations of Behçet's Disease

BACKGROUND

Behçet's disease (BD) is a chronic, multisystemic, inflammatory disease characterized by relapsing episodes of a wide spectrum of clinical findings. The role and mechanism of IFN-λs in BD remain unknown. The aim of this study was to investigate the relationship between IL29 and IL28B gene polymorphisms and BD or clinical manifestations.

METHODS

Using the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method, single-nucleotide polymorphisms of IL28B rs8099917 (IL28 G/T), rs12979860 (IL28 C/T) and IL29 rs30461 (IL29 T/C) were studied in 94 patients with BD and 90 healthy controls.

RESULTS

Our study did not show any relationship between Behçet Disease and genotype or allele frequencies of IL28B (rs8099917, rs12979860) and IL29 (rs30461) gene polymorphisms (p > .05). We found that the TT genotype of rs12979860 (IL28 C/T) polymorphism is higher in healthy controls and patients without central nervous system (CNS) involvement compared to patients with CNS involvement (p = .014 and p = .022).

CONCLUSIONS

As a result, although the relationship was found between IL28 and IL29 gene polymorphisms with some clinical manifestations of BD, it was not directly related to the predisposition of the disease. The relationship between IL-28 and IL-29 which act as regulators in inflammatory processes, with Behçet disease, needs to be investigated in further studies.

Monocytes differentiated into macrophages and dendritic cells in the presence of human IFN-λ3 or IFN-λ4 show distinct phenotypes

Human IFN-λ4 is expressed by only a subset of individuals who possess the ΔG variant allele at the dinucleotide polymorphism rs368234815. Recent genetic studies have shown an association between rs368234815 and different infectious and inflammatory disorders. It is not known if IFN-λ4 has immunomodulatory activity. The expression of another type III IFN, IFN-λ3, is also controlled by genetic polymorphisms that are strongly linked to rs368234815. Therefore, it is of interest to compare these two IFNs for their effects on immune cells. Herein, using THP-1 cells, it was confirmed that IFN-λ4 could affect the differentiation status of macrophage-like cells and dendritic cells (DCs). The global gene expression changes induced by IFN-λ4 were also characterized in in vitro generated primary macrophages. Next, human PBMC-derived CD14+ monocytes were used to obtain M1 and M2 macrophages and DCs in the presence of IFN-λ3 or IFN-λ4. These DCs were cocultured with CD4+ Th cells derived from allogenic donors and their in vitro cytokine responses were measured. The specific activity of recombinant IFN-λ4 was much lower than that of IFN-λ3, as shown by induction of IFN-stimulated genes. M1 macrophages differentiated in the presence of IFN-λ4 showed higher IL-10 secretion than those differentiated in IFN-λ3. Coculture experiments suggested that IFN-λ4 could confer a Th2-biased phenotype to allogenic Th cells, wherein IFN-λ3, under similar circumstances, did not induce a significant bias toward either a Th1 or Th2 phenotype. This study shows for the first time that IFN-λ4 may influence immune responses by immunomodulation.

Enhanced serum interferon-lambda 1 interleukin-29 levels in patients with psoriasis vulgaris

BACKGROUND

Interferon (IFN)-λ1, also named Interleukin (IL)-29, is a new member of the Type III IFN or IFN-λ family. IL-29 plays an important role in the pathogenesis of many types of autoimmune and inflammatory diseases.

OBJECTIVE

To study the role of IL-29 in the pathogenesis of psoriasis vulgaris.

METHODS

The authors detected the serum levels of IL-29 in forty-one patients with psoriasis vulgaris, twenty-three patients with atopic dermatitis and thirty-eight age and gender-matched controls by sandwich Enzyme-Linked Immunosorbent Assay (ELISA). The effects of IL-29 on the expression of cytokines, such as IL-6, IL-17, IL-8, IL-4, IL10, Interferon (IFN-γ) and Tumor Necrosis Factor-α (TNF-α), in PBMCs and HaCat cells were determined by real-time quantitative PCR.

RESULTS

Our data indicated that serum IL-29 levels were significantly elevated in patients with psoriasis vulgaris when compared with atopic dermatitis patients and the control group. Moreover, Serum levels of IL-29 were closely associated with the severity of psoriasis vulgaris. Furthermore, IL-29 up-regulated the mRNA expression levels of IL-6, IL-17 and TNF-α in PBMCs from psoriasis vulgaris patients. In addition, IL-29 enhanced the IL-6 and IL-8 expression from the HaCat cells.

CONCLUSION

This study provides the first observations on the association of IL-29 and psoriasis vulgaris and showed elevated IL-29 serum levels. The authors suggest that IL-29 may play a role in the pathogenesis of psoriasis vulgaris.

Evaluation of interleukin-29 in autoimmune and inflammatory thyroid diseases

OBJECTIVE

Interleukins play an important role in the development of autoimmune disorders. The aim of this study was to compare the concentration of interleukin-29 (IL-29) between healthy controls (CS) and patients with selected thyroid disorders: Graves' disease (GD), Hashimoto's thyroiditis (HT) and subacute thyroiditis (SAT).

DESIGN AND METHODS

The following parameters were examined in the group of 95 individuals (45 with GD, 22 with HT, 28 with SAT) and 72 CS: thyroid hormones and autoantibodies, inflammatory markers and the concentration of IL-29 in serum.

RESULTS

The concentration of IL-29 in the GD subgroup was higher than that in the CS subgroup [264.0 (62.5-1018.0) vs. 62.5 (62.5-217.0) pg/mL, P = .001]. We found no differences in IL-29 concentrations between the CS and HT or SAT subgroups. Multivariable linear regression analysis indicated that IL-29 was a statistically significant independent predictor of GD presence (r = 0.24; P = .003) after adjustment for TRAb (R2  = 0.45; P < .001). The ROC analysis of IL-29 at GD diagnosis revealed an IL-29 cut-off of 123 pg/mL (sensitivity: 0.689 and specificity: 0.625) as the best value, which significantly indicated the presence of GD [area under the ROC curve (AUC): 0.676; 95% confidence interval (CI): 0.574-0.778, P < .001].

CONCLUSION

This is the first study to demonstrate elevated IL-29 serum levels in patients with GD. Our results suggest that IL-29 might be engaged in one of the pathogenetic pathways of GD, but no HT and SAT. Future studies are required to evaluate the potential of the protein as a therapeutic target in GD.

Interferon lambda in inflammation and autoimmune rheumatic diseases

Interferons are potent antiviral cytokines that modulate immunity in response to infection or other danger signals. In addition to their antiviral functions, type I interferons (IFNα and IFNβ) are important in the pathogenesis of autoimmune diseases. Type III interferons (IFNλs) were initially described as a specialized system that inhibits viral replication at epithelial barrier surfaces while limiting inflammatory damage. However, evidence now suggests that type III interferons have complex effects on both innate and adaptive immune responses and might also be pathogenic in systemic autoimmune diseases. Concentrations of IFNλs are increased in blood and tissues in a number of autoimmune rheumatic diseases, including systemic lupus erythematosus, and are further associated with specific clinical and laboratory parameters. This Review is aimed at providing a critical evaluation of the current literature on IFNλ biology and how type III interferons might contribute to immune dysregulation and tissue damage in autoimmunity. The potential effects of type III interferons on treatment strategies for autoimmune rheumatic diseases, such as interferon blockade, are also considered.

Interferon-Lambda 1 Inhibits Staphylococcus aureus Colonization in Human Primary Keratinocytes

Atopic dermatitis (AD) is a common inflammatory skin disease. Staphylococcus aureus (S. aureus) colonization in skin lesions occurs in approximately 70% of AD patients. It has been found that IFN-λ1 can inhibit the colonization of S. aureus in normal human nasal mucosa. IFN-λ1 can increase IL-28RA in infected human keratinocytes. In this study, we found that IFN-λ1 can increase mRNA expression of FLG and antimicrobial peptides (AMPs) and inhibit TSLP mRNA expression in infected human keratinocytes. IFN-λ1 can increase intracellular ROS level, decrease STAT1 phosphorylation, and inhibit the colonization of S. aureus in human primary keratinocytes. These effects were attenuated by knocking-down IL-28R and NADPH oxidase inhibitor, suggesting that this function was mediated by JAK-STAT1 signaling pathway. These results suggest that IFN-λ1 might have an inhibitory effect on S. aureus colonization in AD lesions. Our findings might have potential value in the treatment for AD.

Symmetric Arginine Dimethylation Is Selectively Required for mRNA Splicing and the Initiation of Type I and Type III Interferon Signaling

Alternative splicing is well understood to enhance proteome diversity as cells respond to stimuli. However, mechanistic understanding for how the spliceosome processes precursor messenger RNA (mRNA) transcripts to achieve template diversification is incomplete. We use recently developed enzymatic inhibitors of protein arginine methyltransferase 5 (PRMT5) and human naive T lymphocyte activation as a model system to uncover a precise set of mRNA transcripts that require symmetric arginine dimethylation. This methylation-dependent splicing selectivity is associated with a limited set of signaling pathways that are affected when PRMT5 is inhibited. Specifically, we identify a conserved role for symmetric arginine dimethylation in the induction of antiviral type I and type III interferon signaling following T cell receptor and pattern recognition receptor stimulation in human T lymphocytes and undifferentiated human THP-1 monocytes. Altogether, these findings reveal a mechanism by which cells may be enabled to precisely modulate transcript heterogeneity to orchestrate specific functional outcomes.

Interferon lambda 4 can directly activate human CD19+ B cells and CD8+ T cells

Compared with the ubiquitous expression of type I (IFNα and IFNβ) interferon receptors, type III (IFNλ) interferon receptors are mainly expressed in epithelial cells of mucosal barriers of the of the intestine and respiratory tract. Consequently, IFNλs are important for innate pathogen defense in the lung and intestine. IFNλs also determine the outcome of hepatitis C virus (HCV) infections, with IFNλ4 inhibiting spontaneous clearance of HCV. Because viral clearance is dependent on T cells, we explored if IFNλs can directly bind to and regulate human T cells. We found that human B cells and CD8+ T cells express the IFNλ receptor and respond to IFNλs, including IFNλ4. IFNλs were not inhibitors but weak stimulators of B- and T-cell responses. Furthermore, IFNλ4 showed neither synergistic nor antagonistic effects in co-stimulatory experiments with IFNλ1 or IFNα. Multidimensional flow cytometry of cells from liver biopsies of hepatitis patients from IFNλ4-producers showed accumulation of activated CD8+ T cells with a central memory-like phenotype. In contrast, CD8+ T cells with a senescent/exhausted phenotype were more abundant in IFNλ4-non-producers. It remains to be elucidated how IFNλ4 promotes CD8 T-cell responses and inhibits the host immunity to HCV infections.

The Key Roles of Interferon Lambda in Human Molecular Defense against Respiratory Viral Infections

Interferons (IFN) are crucial for the innate immune response. Slightly more than two decades ago, a new type of IFN was discovered: the lambda IFN (type III IFN). Like other IFN, the type III IFN display antiviral activity against a wide variety of infections, they induce expression of antiviral, interferon-stimulated genes (MX1, OAS, IFITM1), and they have immuno-modulatory activities that shape adaptive immune responses. Unlike other IFN, the type III IFN signal through distinct receptors is limited to a few cell types, primarily mucosal epithelial cells. As a consequence of their greater and more durable production in nasal and respiratory tissues, they can determine the outcome of respiratory infections. This review is focused on the role of IFN-λ in the pathogenesis of respiratory viral infections, with influenza as a prime example. The influenza virus is a major public health problem, causing up to half a million lethal infections annually. Moreover, the virus has been the cause of four pandemics over the last century. Although IFN-λ are increasingly being tested in antiviral therapy, they can have a negative influence on epithelial tissue recovery and increase the risk of secondary bacterial infections. Therefore, IFN-λ expression deserves increased scrutiny as a key factor in the host immune response to infection.

Bovine Interferon Lambda Is a Potent Antiviral Against SARS-CoV-2 Infection in vitro

Interferon lambda (IFN-λ) is an antiviral naturally produced in response to viral infections, with activity on cells of epithelial origin and located in the mucosal surfaces. This localized activity results in reduced toxicity compared to type I IFNs, whose receptors are ubiquitously expressed. IFN-λ has been effective in the therapy of respiratory viral infections, playing a crucial role in potentiating adaptive immune responses that initiate at mucosal surfaces. Human IFN-λ has polymorphisms that may cause differences in the interaction with the specific receptor in the human population. Interestingly, bovine IFN-λ3 has an in silico-predicted higher affinity for the human receptor than its human counterparts, with high identity with different human IFN-λ variants, making it a suitable antiviral therapeutic candidate for human health. Here, we demonstrate that a recombinant bovine IFN-λ (rbIFN-λ) produced in HEK-293 cells is effective in preventing SARS-CoV-2 infection of VERO cells, with an inhibitory concentration 50% (IC50) between 30 and 50 times lower than that of human type I IFN tested here (α2b and β1a). We also demonstrated the absence of toxicity of rbIFN-λ in human PBMCs and the lack of proinflammatory activity on these cells. Altogether, our results show that rbIFN-λ is as an effective antiviral potentially suitable for COVID-19 therapy. Among other potential applications, rbIFN-λ could be useful to preclude virus dispersion to the lungs and/or to reduce transmission from infected people. Moreover, and due to the non-specific activity of this IFN, it can be potentially effective against other respiratory viruses that may be circulating together with SARS-CoV-2.

Activation of NOTCH1 by Shear Force Elicits Immediate Cytokine Expression in Human Chondrocytes

Osteoarthritis is caused by overloading of joints and is characterized by inflammation-induced disruption of cartilage structure. Current treatment strategy aims to relieve inflammation and prevent further deterioration of joint function. However, how mechanical force leads to inflammation and deterioration of chondrocyte function still remains incompletely understood. To explore the force-regulated molecular mechanism, an in vitro hydraulic shear force experiment to simulate the condition of force loading was required. The result demonstrated that multiple cytokines and immune regulators, including interleukin 8, interferon β, TRAF1 and TNFAIP3, were significantly increased by shear force within two hours of treatment. Moreover, JAG1 and HES1 were drastically upregulated as well, suggesting that NOTCH1 signaling is activated by shear force. Short-term expression of NOTCH1 intracellular domain activated a similar set of cytokines, indicating that NOTCH1 responds to shear force and activates downstream genes. When incubated under the medium conditioned by NOTCH1-activated chondrocyte, osteoblasts expressed higher levels of interferon β and interferon λ. Together, our results indicated that NOTCH1 functions as a force sensor and promotes expression of cytokines and immune regulators from shear-force bearing chondrocytes.

Evaluation of IL-29 in Euthyroid Patients with Graves' Orbitopathy: A Preliminary Study

BACKGROUND

The most frequent cause of hyperthyroidism is Graves' disease (GD). Orbitopathy is the most prevalent and recognizable extrathyroidal manifestation of Graves' disease with unrevealed pathogenesis. Interleukin 29 (IL-29) is a relatively newly discovered inflammatory cytokine. Thus, the aim of this study was to evaluate the relationship between IL-29 and Graves' orbitopathy (GO) in euthyroid patients.

METHODS

Thirty-one euthyroid patients with Graves' disease and with active GO [clinical activity score (CAS) ≥ 3/7], seventeen euthyroid patients with GD but without GO, and seventy-two healthy control subjects (CS) matched for age and gender were enrolled in the study. The following parameters were evaluated in every participant: thyroid-related hormones and autoantibodies and inflammatory markers (white blood cells, hsCRP). ELISA assay was applied to measure the concentration of IL-29.

RESULTS

We found higher level of IL-29 in GO group in comparison with CS [165 (133-747) vs. 62 (62-217) pg/mL, p < 0.001]. Furthermore, participants in the subgroup with GD with GO as compared with GD without GO had higher concentration of IL-29 [165 (133-747) vs. 62 (62-558) pg/mL, p = 0.031]. The ROC analysis for IL-29 revealed IL-29 cut-off of 105 pg/mL (sensitivity 1.000 and specificity 0.597) as the best value significantly indicating the presence of GO in GD [area under the ROC curve (AUC): 0.739, 95% confidence interval (CI): 0.646-0.833, p < 0.001].

CONCLUSIONS

The present study revealed for the first time an elevated level of IL-29 in the serum of patients with GD and GO that might suggest its involvement in the pathogenesis of GD ocular complications.

Differential expression of interferon-lambda receptor 1 splice variants determines the magnitude of the antiviral response induced by interferon-lambda 3 in human immune cells

Type III interferons (IFN-lambdas(λ)) are important cytokines that inhibit viruses and modulate immune responses by acting through a unique IFN-λR1/IL-10RB heterodimeric receptor. Until now, the primary antiviral function of IFN-λs has been proposed to be at anatomical barrier sites. Here, we examine the regulation of IFN-λR1 expression and measure the downstream effects of IFN-λ3 stimulation in primary human blood immune cells, compared with lung or liver epithelial cells. IFN-λ3 directly bound and upregulated IFN-stimulated gene (ISG) expression in freshly purified human B cells and CD8+ T cells, but not monocytes, neutrophils, natural killer cells, and CD4+ T cells. Despite similar IFNLR1 transcript levels in B cells and lung epithelial cells, lung epithelial cells bound more IFN-λ3, which resulted in a 50-fold greater ISG induction when compared to B cells. The reduced response of B cells could be explained by higher expression of the soluble variant of IFN-λR1 (sIFN-λR1), which significantly reduced ISG induction when added with IFN-λ3 to peripheral blood mononuclear cells or liver epithelial cells. T-cell receptor stimulation potently, and specifically, upregulated membrane-bound IFNLR1 expression in CD4+ T cells, leading to greater antiviral gene induction, and inhibition of human immunodeficiency virus type 1 infection. Collectively, our data demonstrate IFN-λ3 directly interacts with the human adaptive immune system, unlike what has been previously shown in published mouse models, and that type III IFNs could be potentially utilized to suppress both mucosal and blood-borne viral infections.

Sensitivity and specificity of Interleukin 29 in patients with rheumatoid arthritis and other rheumatic diseases

BACKGROUND

Rheumatoid arthritis (RA) is a systemic autoimmune disease characterized by chronic and progressive inflammation that can cause a high degree of disability in affected individuals. Proinflammatory cytokines play central roles in the development of degradative and inflammatory responses in RA. IL-29 has been identified in RA and reported as a biomarker of the disease.

OBJECTIVE

To analyze serum levels and accuracy of IL-29 in RA patients compared to healthy subjects and patients with other rheumatic diseases.

METHODS

IL-29 serum levels were measured in 121 patients with RA, 53 patients with systemic lupus erythematosus (SLE), 60 patients with systemic sclerosis (SSc), 29 patients with fibromyalgia (FM), 50 patients with osteoarthritis (OA) and 68 healthy individuals as controls. IL-29 levels in serum were investigated by ELISA. Sensitivity, specificity and likelihood ratios (LR) for having RA were calculated.

RESULTS

Serum levels of IL-29 were increased in RA patients 113.6 (IQR = 31.25-308.5) pg/ml compared to non-RA patients (SLE, SSc, OA, and FM) (31.25 pg/ml) and healthy controls (31.25 pg/ml, p < 0.001). The IL-29 cut-off values to distinguish patients with RA from non-RA patients were 61.11 pg/ml (sensitivity 57.02, specificity 92.71, LR: 7.82) and for all subjects 32.96 pg/ml (sensitivity 64.46, specificity 87.31, LR: 5.08). Additionally, IL-29 correlated negatively with age (r=-0189, p = 0.038) and disease duration (-0.192, p = 0.037). Interestingly, IL-29 correlated positively with neutrophil count in RA patients positive for rheumatoid factor (r = 0.259, p = 0.022).

CONCLUSION

IL-29 is higher in the serum of patients with RA compared to non-RA subjects and may have potential for use as a biological marker.

The pattern of antiviral protein expression induced by interferon λ1 in peripheral blood mononuclear cells of patients with chronic hepatitis C virus infection

Interferon lambda was discovered in recent years to be an antiviral agent, and research on different aspects of this antiviral factor in viral infection and investigations of its effectiveness are also progressing. The immunological effects of interferon lambda on different cell populations is not precisely known, which may be due to its use of a heterodimeric receptor consisting of IL-10R2 and IFN-λR1, which are not broadly expressed in all types of cells. In the present study, signaling by interferon lambda and its effect on the expression of hepatitis C virus (HCV) proteins were measured, and the expression pattern of some antiviral proteins and IL-10 levels were investigated in peripheral blood mononuclear cells (PBMCs). PBMCs were isolated from 50 patients with chronic genotype 1a HCV infection and 10 healthy individuals as controls. The PBMCs were treated with various doses of interferon lambda at different times of cultivation. Real-time PCR was used for relative quantification of Mxa, PKR, OAS, ISG15 and HCV core mRNAs. Expression of the NS5A protein was measured by flow cytometry, and IL-10 production was assessed by ELISA. A significant increase in the expression of mRNA encoding antiviral proteins and a decrease in the expression of mRNAs encoding the HCV core protein were observed when cells were treated with interferon lambda in an intermittent manner. The expression of HCV NS5A protein and interleukin 10 levels were also lower than in the control group. It was shown that the maximum antiviral effect of interferon lambda in PBMCs is dependent on the dose and treatment time.

Type III Interferons (Lambda Interferons) in Rheumatic Autoimmune Diseases

The last 2 decades have witnessed the discovery and characterization of a new family of cytokines with immunological characteristics similar to those described for type I interferons, type III or lambda interferons. Unraveling the molecular mechanisms underlying each type of interferon has allowed us to understand how some autoimmune diseases can be considered as interferonopathies. Under normal conditions, type III interferons play a key role in the defense against viruses by modulating the functioning of several types of innate and adaptive immune cells. These effects include upregulation of major histocompatibility complex molecules by myeloid dendritic cells, increased functioning of pattern recognition receptors by plasmacytoid dendritic cells, decreased activity of regulatory T cells, enhanced production of antibodies by plasmatic cells and increased expression of chemokines and adhesion molecules by leukocytes and endothelial cells. Notably, all these mechanisms have been described to boost autoimmunity, and type III interferons pathway activation has been related to the pathogenesis of autoimmune conditions such as systemic lupus erythematosus, systemic sclerosis and Sjögren's syndrome. This review provides an overview of the current evidence on the contribution of type III interferons in the pathogenesis of rheumatic autoimmune diseases in humans.

Insights into IL-29: Emerging role in inflammatory autoimmune diseases

Interleukin-29 (IL-29) is a newly discovered member of type III interferon. It mediates signal transduction via binding to its receptor complex and activates downstream signalling pathways, and therefore induces the generation of inflammatory components. Recent studies reported that expression of IL-29 is dysregulated in inflammatory autoimmune diseases, such as rheumatoid arthritis, systemic lupus erythematosus, osteoarthritis, Sjögren's syndrome, psoriasis and systemic sclerosis. Furthermore, functional analysis revealed that IL-29 may involve in the pathogenesis of the inflammatory autoimmune disorders. In this review, we will systematically review the current knowledge about IL-29. The information collected revealed the regulatory role of IL-29 and may give important implications for its potential in clinical treatment.

[Expression of interferon-λ1 in respiratory epithelial cells in children with human rhinovirus infection]

OBJECTIVE

To study the expression of interferon-λ1 (IFN-λ1) in respiratory epithelial cells in children with human rhinovirus (HRV) infection.

METHODS

Sputum samples and nasopharyngeal swabs were collected from the children who were hospitalized due to acute respiratory infection from February to October, 2017. Bacterial culture was performed, and nucleic acid test was performed for 11 respiratory pathogens. A total of 90 children with positive HRV alone were enrolled as the HRV infection group, and 95 children with positive respiratory syncytial virus (RSV) alone were enrolled as the RSV infection group. A total of 50 healthy children who underwent outpatient physical examination during the same period of time and had negative results for all pathogen tests were enrolled as the healthy control group. Nasopharyngeal swabs were collected from all groups, and quantitative real-time PCR was used to measure viral load and the mRNA expression of IFN-λ1.

RESULTS

In the HRV infection group, there was no significant difference in the mRNA expression of IFN-λ1 between boys and girls and across all age groups (P>0.05). In the HRV infection group, there was no correlation between the mRNA expression of IFN-λ1 and HRV load (P>0.05). The mRNA expression of IFN-λ1 in the HRV infection group was significantly higher than that in the healthy control group (P<0.05), but significantly lower than that in the RSV infection group (P<0.05).

CONCLUSIONS

HRV can induce the expression of IFN-λ1 in respiratory epithelial cells, suggesting that IFN-λ1 may play an important role in anti-HRV infection in children.

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

BACKGROUND

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.

METHODS

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).

RESULTS

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.

Macrophage Coordination of the Interferon Lambda Immune Response

Lambda interferons (IFN-λs) are a major component of the innate immune defense to viruses, bacteria, and fungi. In human liver, IFN-λ not only drives antiviral responses, but also promotes inflammation and fibrosis in viral and non-viral diseases. Here we demonstrate that macrophages are primary responders to IFN-λ, uniquely positioned to bridge the gap between IFN-λ producing cells and lymphocyte populations that are not intrinsically responsive to IFN-λ. While CD14⁺ monocytes do not express the IFN-λ receptor, IFNLR1, sensitivity is quickly gained upon differentiation to macrophages in vitro. IFN-λ stimulates macrophage cytotoxicity and phagocytosis as well as the secretion of pro-inflammatory cytokines and interferon stimulated genes that mediate immune cell chemotaxis and effector functions. In particular, IFN-λ induced CCR5 and CXCR3 chemokines, stimulating T and NK cell migration, as well as subsequent NK cell cytotoxicity. Using immunofluorescence and cell sorting techniques, we confirmed that human liver macrophages expressing CD14 and CD68 are highly responsive to IFN-λ ex vivo. Together, these data highlight a novel role for macrophages in shaping IFN-λ dependent immune responses both directly through pro-inflammatory activity and indirectly by recruiting and activating IFN-λ unresponsive lymphocytes.

The Influence of the rs30461 Single Nucleotide Polymorphism on IFN-λ1 Activity and Secretion

Genetic variation within the IFNL loci is associated with several diseases and evidence indicates that the IFNL genes have been subjects of strong selection during recent human evolution. The nonsynonymous rs30461 single nucleotide polymorphism (SNP), generating interferon (IFN)-λ1 D188N, shows a strong signature of positive selection in European and Asian populations. Nevertheless, genetic association studies have failed to show any coupling of rs30461 to diseases such as psoriasis and periodontitis. Based on these observations, we purified IFN-λ1 N188 and IFN-λ1 D188 to compare the biological activity of these 2 IFN-λ1 versions. Furthermore, we evaluated the secretion of the 2 different IFN-λ1 versions. We were unable to observe any differences between IFN-λ1 N188 and IFN-λ1 D188 based on biological activity or secretion that could account for the positive selection.

Differential Regulation of Type I and Type III Interferon Signaling

Interferons (IFNs) are very powerful cytokines, which play a key role in combatting pathogen infections by controlling inflammation and immune response by directly inducing anti-pathogen molecular countermeasures. There are three classes of IFNs: type I, type II and type III. While type II IFN is specific for immune cells, type I and III IFNs are expressed by both immune and tissue specific cells. Unlike type I IFNs, type III IFNs have a unique tropism where their signaling and functions are mostly restricted to epithelial cells. As such, this class of IFN has recently emerged as a key player in mucosal immunity. Since the discovery of type III IFNs, the last 15 years of research in the IFN field has focused on understanding whether the induction, the signaling and the function of these powerful cytokines are regulated differently compared to type I IFN-mediated immune response. This review will cover the current state of the knowledge of the similarities and differences in the signaling pathways emanating from type I and type III IFN stimulation.

Contribution of Cytokines to Tissue Damage During Human Respiratory Syncytial Virus Infection

The human respiratory syncytial virus (hRSV) remains one of the leading pathogens causing acute respiratory tract infections (ARTIs) in children younger than 2 years old, worldwide. Hospitalizations during the winter season due to hRSV-induced bronchiolitis and pneumonia increase every year. Despite this, there are no available vaccines to mitigate the health and economic burden caused by hRSV infection. The pathology caused by hRSV induces significant damage to the pulmonary epithelium, due to an excessive inflammatory response at the airways. Cytokines are considered essential players for the establishment and modulation of the immune and inflammatory responses, which can either be beneficial or harmful for the host. The deleterious effect observed upon hRSV infection is mainly due to tissue damage caused by immune cells recruited to the site of infection. This cellular recruitment takes place due to an altered profile of cytokines secreted by epithelial cells. As a result of inflammatory cell recruitment, the amounts of cytokines, such as IL-1, IL-6, IL-10, and CCL5 are further increased, while IL-10 and IFN-γ are decreased. However, additional studies are required to elicit the mediators directly associated with hRSV damage entirely. In addition to the detrimental induction of inflammatory mediators in the respiratory tract caused by hRSV, reports indicating alterations in the central nervous system (CNS) have been published. Indeed, elevated levels of IL-6, IL-8 (CXCL8), CCL2, and CCL4 have been reported in cerebrospinal fluid from patients with severe bronchiolitis and hRSV-associated encephalopathy. In this review article, we provide an in-depth analysis of the role of cytokines secreted upon hRSV infection and their potentially harmful contribution to tissue damage of the respiratory tract and the CNS.

IL28B, IL29 and micro-RNA 548 in subacute sclerosing panencephalitis as a rare disease

Subacute sclerosing panencephalitis (SSPE) is a progressive neurodegenerative disease which affects children and young adults, caused by a persistent infection of defective measles virus. IFN-λs (IL-28A, IL-28B and IL-29) are a group of cytokines mediating antiviral responses. It has been shown that IL-29 levels are significantly higher in infected cells with defective measles virus. IL-29 expression is thought to be regulated at post-transcriptional level and miRNA-548 family targets the 3'UTR of the IFNL1 gene. Impaired immune system has an important role as well as viral factors in SSPE. The aim of our study investigates whether IL-28B, IL-29 levels and gene polymorphisms contribute to the damaged immune response leading to the development of SSPE. Also possible association of miR-548 family with IL-29 and SSPE is explored. Frequencies of rs12979860, rs8099917, rs30461, serum levels of IL-28B, IL-29 and expression levels of miR-548b, miR-548c, miR-548i are determined at 64 SSPE patients and 68 healthy controls. Serum IL-29 levels are statistically significant higher in SSPE patients. Allele frequencies of rs8099917 are statistically significant higher in SSPE patients and resulted G allele is found to increase 2.183-fold risk of SSPE. The expression levels of miR-548b-5p, miR-548c-5p and miR-548i are found to be statistically significant higher in SSPE patients. Dramatically increased level of IL-29 seen in patient group indicates that the elevated miR-548 expression is compensatory result of the over-activated immune system response. Further studies referred to IL28, IL29 and related miRNA's will be enlightened the pathogenesis of SSPE.

Lambda interferons come to light: dual function cytokines mediating antiviral immunity and damage control

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IFNλs are dual function cytokines mediating antiviral activity and damage control.

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IFNλs confer initial antimicrobial protection at anatomical barriers without provoking unnecessary inflammation.

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IFNλs exhibit immune regulatory and host protective actions reminiscent of IL-10.

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IFNλs form novel therapeutics with the beneficial actions of type I IFNs but lacking their pro-inflammatory side effects.

Lambda interferons (IFNλs, type III IFNs or interleukins-28/29) were described fifteen years ago as novel cytokines sharing structural and functional homology with IL-10 and type I IFNs, respectively. IFNλs engage a unique receptor complex comprising IFNLR1 and IL10R2, nevertheless they share signaling cascade and many functions with type I IFNs, questioning their possible non-redundant roles and overall biological importance. Here, we review the latest evidence establishing the primacy of IFNλs in front line protection at anatomical barriers, mediating antiviral immunity before type I IFNs. We also discuss their emerging role in regulating inflammation and limiting host damage, a major difference to type I IFNs. IFNλs come thus to light as dual function cytokines mediating antiviral immunity and damage control.

Elevated Systemic and Parasite-Antigen Stimulated Levels of Type III IFNs in a Chronic Helminth Infection and Reversal Following Anthelmintic Treatment

Type III IFNs are important players in immunity to viral and bacterial infections. However, their association with helminth infections has not been examined. To explore the association of Type III IFNs with Strongyloides stercoralis (Ss) infection, we examined the systemic levels of IFN lambda-1, IFN lambda-2 and IFN lambda-3, IL-10, and CXCL10/IP-10 in Ss infected (INF, n = 44), helminth—uninfected (UN, n = 44) and in post-treatment INF individuals. We also examined the levels of IFN lambda-1, IFN lambda-2 and IFN lambda-3, IL-10, and CXCL10/IP-10 in whole blood culture supernatants stimulated with Ss somatic antigens, or PPD or LPS. Finally, we performed correlations of systemic Type III IFN levels with absolute numbers of dendritic cell subsets. Ss infection is characterized by elevated systemic levels of IFN lambda-1, IFN lambda-2 and IFN lambda-3, IL-10, and CXCL10/IP-10 in comparison to UN individuals and a significant reduction following anthelmintic treatment. Ss infection is also characterized by elevated levels of unstimulated or Ss antigen stimulated levels of IFN lambda-1, IFN lambda-2 and IFN lambda-3, CXCL10/IP-10 and a significant reduction following treatment. In addition, Ss infection is characterized by increased numbers of plasmacytoid and myeloid dendritic cells in comparison to UN individuals, with a significant reduction following anthelmintic treatment of INF individuals. Finally, Ss infection exhibits a significant positive correlation between the systemic levels of IFN lambda-2 and IFN lambda-3 and the numbers of plasmacytoid dendritic cells. Thus, Ss infection is characterized by elevations in systemic and antigen—induced levels of Type III IFNs, which is positively associated with the numbers of plasmacytoid dendritic cells and reversed upon anthelmintic treatment.

Interleukin 29 activates expression of tissue inhibitor of metalloproteinase 1 in macrophages via toll‑like receptor 2

Obesity and diabetes are characterized by low grade chronic inflammation status and insulin resistance in adipose tissue associated with metalloproteinase inhibitor 1 (TIMP1). Interleukin (IL)29, exhibits multiple immune regulatory activities. However, the role of IL29 and its effects on TIMP1 remain to be elucidated. The present study was designed to investigate the effects of IL29 on expression of TIMP1 in macrophages associated with inflammation in adipose tissue. IL29 and high glucose were used to activate Raw264.7 cells and primary macrophages with or without antibody‑mediated inhibition of toll like receptor (TLR) 2 and TLR4. TIMP1 was measured in culture media of Raw264.7 cells and primary macrophages by ELISA. IL29 and high glucose increased TIMP1 levels in Raw264.7 cells and primary macrophages. Antibody‑mediated inhibition of TLR2 or TLR2 gene knockout decreased TIMP1 levels activated by IL29, however not by high glucose in the medium of Raw264.7 cells and primary macrophages. Furthermore, antibody‑mediated inhibition of TLR4 or TLR4 gene knockout decreased TIMP1 levels which were stimulated by high glucose, not by IL29 in the medium of Raw264.7 cells and primary macrophages. The results of the present study indicate that TLR2 is involved in IL29‑stimulated TIMP1 expression in Raw264.7 cells and primary macrophages.

Exosomal biomarkers in Down syndrome and Alzheimer's disease

Every person with Down syndrome (DS) has the characteristic features of Alzheimer's disease (AD) neuropathology in their brain by the age of forty, and most go on to develop AD dementia. Since people with DS show highly variable levels of baseline function, it is often difficult to identify early signs of dementia in this population. The discovery of blood biomarkers predictive of dementia onset and/or progression in DS is critical for developing effective clinical diagnostics. Our recent studies show that neuron-derived exosomes, which are small extracellular vesicles secreted by most cells in the body, contain elevated levels of amyloid-beta peptides and phosphorylated-Tau that could indicate a preclinical AD phase in people with DS starting in childhood. We also found that the relative levels of these biomarkers were altered following dementia onset. Exosome release and signaling are dependent on cellular redox homeostasis as well as on inflammatory processes, and exosomes may be involved in the immune response, suggesting a dual role as both triggers of inflammation in the brain and propagators of inflammatory signals between brain regions. Based on recently reported connections between inflammatory processes and exosome release, the elevated neuroinflammatory state observed in people with DS may affect exosomal AD biomarkers. Herein, we discuss findings from studies of people with DS, people with DS and AD (DS-AD), and mouse models of DS showing new connections between neuroinflammatory pathways, oxidative stress, exosomes, and exosome-mediated signaling, which may inform future AD diagnostics, preventions, and treatments in the DS population as well as in the general population.

Interferon-λs and Plasmacytoid Dendritic Cells: A Close Relationship

Interferon lambdas (IFNλs) are recently discovered cytokines acting not only at the first line of defense against viral infections but also at the mucosal barriers. In fact, a peculiar feature of the IFNλ system is the restricted expression of the functional IFNλR, which is known to be limited to epithelial cells and discrete leukocyte subsets, including the plasmacytoid dendritic cells (pDCs). In the latter case, current data, discussed in this minireview, indicate that IFNλs positively regulate various pDC functions, including pDC expression of interferon-dependent gene (ISG) mRNAs, production of cytokines, survival, and phenotype. Although the knowledge of the effects on pDCs by IFNλs is still incomplete, we speculate that the peculiar pDC responsiveness to IFNλs provide unique advantages for these innate immune cells, not only for viral infections but also during autoimmune disorders and/or tumors, in which pDC involvement and activation variably contribute to their pathogenesis.

Peg-Interferon Lambda Treatment Induces Robust Innate and Adaptive Immunity in Chronic Hepatitis B Patients

IFN-lambda (IFNλ) is a member of the type III IFN family and is reported to possess anti-pathogen, anti-cancer, and immunomodulatory properties; however, there are limited data regarding its impact on host immune responses in vivo. We performed longitudinal and comprehensive immunosurveillance to assess the ability of pegylated (peg)-IFNλ to augment antiviral host immunity as part of a clinical trial assessing the efficacy of peg-IFNλ in chronic hepatitis B (CHB) patients. These patients were pretreated with directly acting antiviral therapy (entecavir) for 12 weeks with subsequent addition of peg-IFNλ for up to 32 weeks. In a subgroup of patients, the addition of peg-IFNλ provoked high serum levels of antiviral cytokine IL-18. We also observed the enhancement of natural killer cell polyfunctionality and the recovery of a pan-genotypic HBV-specific CD4⁺ T cells producing IFN-γ with maintenance of HBV-specific CD8⁺ T cell antiviral and cytotoxic activities. It was only in these patients that we observed strong virological control with reductions in both viral replication and HBV antigen levels. Here, we show for the first time that in vivo peg-IFNλ displays significant immunostimulatory properties with improvements in the main effectors mediating anti-HBV immunity. Interestingly, the maintenance in HBV-specific CD8⁺ T cells in the presence of peg-IFNλ is in contrast to previous studies showing that peg-IFNα treatment for CHB results in a detrimental effect on the functionality of this important antiviral T cell compartment.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov NCT01204762.

IFN-λ Inhibits Drug-Resistant HIV Infection of Macrophages

Type III interferons (IFN-λs) have been demonstrated to inhibit a number of viruses, including HIV. Here, we further examined the anti-HIV effect of IFN-λs in macrophages. We found that IFN-λs synergistically enhanced anti-HIV activity of antiretrovirals [azidothymidine (AZT), efavirenz, indinavir, and enfuvirtide] in infected macrophages. Importantly, IFN-λs could suppress HIV infection of macrophages with the drug-resistant strains, including AZT-resistant virus (A012) and reverse transcriptase inhibitor-resistant virus (TC49). Mechanistically, IFN-λs were able to induce the expression of several important anti-HIV cellular factors, including myxovirus resistance 2 (Mx2), a newly identified HIV post-entry inhibitor and tetherin, a restriction factor that blocks HIV release from infected cells. These observations provide additional evidence to support the potential use of IFN-λs as therapeutics agents for the treatment of HIV infection.

Elevated Serum Levels of Interleukin-29 Are Associated with Disease Activity in Rheumatoid Arthritis Patients with Anti-Cyclic Citrullinated Peptide Antibodies

Rheumatoid arthritis (RA) is an inflammatory autoimmune disease that may lead to progressive joint destruction. The anti-cyclic citrullinated peptide (anti-CCP) antibody is an essential marker for the diagnosis of RA and has a crucial role in the bone destruction in RA. Recent studies have shown that interleukin (IL)-29, a vital member of type III interferon (IFN) family, could enhance proinflammatory cytokine production and might be involved in the joint destruction in RA. Therefore, in this study, we aimed to examine the role of IL-29 in RA patients with anti-CCP antibodies. The result showed that the serum IL-29 levels were higher in RA patients (n = 68) compared with healthy controls (HC, n = 68, P = 0.019). Correlation analysis demonstrated a significant positive correlation among serum IL-29 level, rheumatoid factor (RF, P < 0.001) and anti-CCP antibodies (P = 0.042). However, when RA patients were divided into two groups according to anti-CCP antibodies, the serum IL-29 levels were significantly higher in anti-CCP-antibodies positive RA patients (n = 54) than those in HC (n = 68) and anti-CCP-antibodies negative RA patients (n = 14). Furthermore, the serum IL-29 levels were positively correlated with the disease activity (P < 0.05) and significantly declined after 6 months of treatment (P < 0.01) in the anti-CCP-antibodies positive RA patients, whereas no significant change was found in the anti-CCP-antibodies negative RA patients (P > 0.05). The findings indicate that IL-29 is a potential biomarker for disease activity in anti-CCP-antibodies positive RA patients.

Type III Interferons in Hepatitis C Virus Infection

The interferon (IFN)-λ family of type III cytokines includes the closely related interleukin (IL)-28A (IFN-λ2), IL-28B (IFN-λ3), and IL-29 (IFN-λ1). They signal through the Janus kinases (JAK)-signal transducers and activators of transcription pathway and promote an antiviral state by the induction of expression of several interferon-stimulated genes (ISGs). Contrary to type I IFNs, the effect of IFN-λ cytokines is largely limited to epithelial cells due to the restricted pattern of expression of their specific receptor. Several genome-wide association studies have established a strong correlation between polymorphism in the region of IL-28B gene (encoding for IFN-λ3) and both spontaneous and therapeutic IFN-mediated clearance of hepatitis C virus (HCV) infection, but the mechanism(s) underlying this enhanced viral clearance are not fully understood. IFN-λ3 directly inhibits HCV replication, and in vitro studies suggest that polymorphism in the IFN-λ3 and its recently identified overlapping IFN-λ4 govern the pattern of ISGs induced upon HCV infection of hepatocytes. IFN-λ can also be produced by dendritic cells, and apart from its antiviral action on hepatocytes, it can regulate the inflammatory response of monocytes/macrophages, thus acting at the interface between innate and adaptive immunity. Here, we review the current state of knowledge about the role of IFN-λ cytokines in mediating and regulating the immune response during acute and chronic HCV infections.

Immune Cell Profiling of IFN-λ Response Shows pDCs Express Highest Level of IFN-λR1 and Are Directly Responsive via the JAK-STAT Pathway

The interferon lambda (IFN-λ) cytokines have well-known antiviral properties, yet their contribution to immune regulation is not well understood. Epithelial cells represent the major target cell of IFN-λ; peripheral blood mononuclear cells are generally considered nonresponsive, with the exception of plasmacytoid dendritic cells (pDCs). In this study we aimed to define the potential for discrete subpopulations of cells to directly respond to IFN-λ. Analysis of peripheral blood leukocytes reveals that, while pDCs uniformly express the highest levels of IFN-λ receptor, a small proportion of B cells and monocytes also express the receptor. Nevertheless, B cells and monocytes respond poorly to IFN-λ stimulation in vitro, with minimal STAT phosphorylation and interferon-stimulated gene (ISG) induction observed. We confirm that pDCs respond to IFN-λ in vitro, upregulating their expression of pSTAT1, pSTAT3, and pSTAT5. However, we found that pDCs do not upregulate pSTAT6 in response to IFN-λ treatment. Our results highlight unique aspects of the response to IFN-λ and confirm that while the IFN-λ receptor is expressed by a small proportion of several different circulating immune cell lineages, under normal conditions only pDCs respond to IFN-λ stimulation with robust STAT phosphorylation and ISG induction. The difference in STAT6 responsiveness of pDCs to type I and type III interferons may help explain the divergence in their biological activities.

IFNλ is a potent anti-influenza therapeutic without the inflammatory side effects of IFNα treatment

Influenza A virus (IAV)‐induced severe disease is characterized by infected lung epithelia, robust inflammatory responses and acute lung injury. Since type I interferon (IFNαβ) and type III interferon (IFNλ) are potent antiviral cytokines with immunomodulatory potential, we assessed their efficacy as IAV treatments. IFNλ treatment of IAV‐infected Mx1‐positive mice lowered viral load and protected from disease. IFNα treatment also restricted IAV replication but exacerbated disease. IFNα treatment increased pulmonary proinflammatory cytokine secretion, innate cell recruitment and epithelial cell death, unlike IFNλ‐treatment. IFNλ lacked the direct stimulatory activity of IFNα on immune cells. In epithelia, both IFNs induced antiviral genes but no inflammatory cytokines. Similarly, human airway epithelia responded to both IFNα and IFNλ by induction of antiviral genes but not of cytokines, while hPBMCs responded only to IFNα. The restriction of both IFNλ responsiveness and productive IAV replication to pulmonary epithelia allows IFNλ to limit IAV spread through antiviral gene induction in relevant cells without overstimulating the immune system and driving immunopathology. We propose IFNλ as a non‐inflammatory and hence superior treatment option for human IAV infection.

Interleukin-29 Enhances Synovial Inflammation and Cartilage Degradation in Osteoarthritis

We have recently shown that IL-29 was an important proinflammatory cytokine in pathogenesis of rheumatoid arthritis (RA). Inflammation also contributes to the pathogenesis of osteoarthritis (OA). The aim of this study was to investigate the effect and mechanism of IL-29 on cytokine production and cartilage degradation in OA. The mRNA levels of IL-29 and its specific receptor IL-28Ra in peripheral blood mononuclear cells (PBMCs) were significantly increased in OA patients when compared to healthy controls (HC). In the serum, IL-29 protein levels were higher in OA patients than those in HC. Immunohistochemistry revealed that both IL-29 and IL-28Ra were dramatically elevated in OA synovium compared to HC; synovial fibroblasts (FLS) and macrophages were the main IL-29-producing cells in OA synovium. Furthermore, recombinant IL-29 augmented the mRNA expression of IL-1β, IL-6, IL-8, and matrix-metalloproteinase-3 (MMP-3) in OA FLS and increased cartilage degradation when ex vivo OA cartilage explant was coincubated with OA FLS. Finally, in OA FLS, IL-29 dominantly activated MAPK and nuclear factor-κB (NF-κB), but not Jak-STAT and AKT signaling pathway as examined by western blot. In conclusion, IL-29 stimulates inflammation and cartilage degradation by OA FLS, indicating that this cytokine is likely involved in the pathogenesis of OA.

Type I and III IFNs Produced by Plasmacytoid Dendritic Cells in Response to a Member of the Flaviviridae Suppress Cellular Immune Responses

The pestivirus noncytopathic bovine viral diarrhea virus (BVDV) can suppress IFN production in the majority of cell types in vitro. However, IFN is detectable in serum during acute infection in vivo for ∼5-7 d, which correlates with a period of leucopoenia and immunosuppression. In this study, we demonstrate that a highly enriched population of bovine plasmacytoid dendritic cells (DCs) produced IFN in response to BVDV in vitro. We further show that the majority of the IFN produced in response to infection both in vitro and in vivo is type III IFN and acid labile. Further, we show IL-28B (IFN-λ3) mRNA is induced in this cell population in vitro. Supernatant from plasmacytoid DCs harvested postinfection with BVDV or recombinant bovine IFN-α or human IL-28B significantly reduced CD4(+) T cell proliferation induced by tubercle bacillus Ag 85-stimulated monocyte-derived DCs. Furthermore, these IFNs induced IFN-stimulated gene expression predominantly in monocyte-derived DCs. IFN-treated immature DCs derived from murine bone marrow also had a reduced capacity to stimulate T cell proliferative responses to tubercle bacillus Ag 85. Immature DCs derived from either source had a reduced capacity for Ag uptake following IFN treatment that is dose dependent. Immunosuppression is a feature of a number of pestivirus infections; our studies suggest type III IFN production plays a key role in the pathogenesis of this family of viruses. Overall, in a natural host, we have demonstrated a link between the induction of type I and III IFN after acute viral infection and transient immunosuppression.

Microbial pathogenesis and type III interferons

The innate immune system possesses a multitude of pathways to sense and respond to microbial pathogens. One such family are the interferons (IFNs), a family of cytokines that are involved in several cellular functions. Type I IFNs are appreciated to be important in several viral and bacterial diseases, while the recently identified type III IFNs (IFNL1, IFNL2, IFNL3, IFNL4) have been studied primarily in the context of viral infection. Viral and bacterial infections however are not mutually exclusive, and often the presence of a viral pathogen increases the pathogenesis of bacterial infection. The role of type III IFN in bacterial and viral-bacterial co-infections has just begun to be explored. In this mini review we discuss type III IFN signaling and its role in microbial pathogenesis with an emphasis on the work that has been conducted with bacterial pathogens.

The roles of interferons in osteoclasts and osteoclastogenesis

Interferons (IFNs) play essential roles in regulating osteoclast differentiation and bone resorption. Over the last decade, we have seen tremendous developments in our understanding of the mechanisms by which interferons regulate osteoclastogenesis. Of the type I interferons, IFN-β inhibits osteoclastogenesis via autoregulatory or exogenous regulatory mechanisms, while IFN-α was recently shown to participate in regulating osteoclast formation. And the only member of type II interferons, IFN-γ, has biphasic effects on osteoclastogenesis. Type III interferons have also been shown to be involved in osteoclast bone resorption, although no direct regulatory mechanism has been demonstrated. In this review, we provide an update account of the current knowledge on these recently revealed novel roles of interferons in the regulation of a variety of signaling pathways in osteoclast differentiation and function. The potential clinical applications are also discussed.

Dexamethasone decreases IL-29 expression in house dust mite-stimulated human bronchial epithelial cells

The aim of this study was to explore the effect of IL-29 on the progression of airway allergic disease by detecting the level of IL-29 in airway allergic cell models stimulated by house dust mite (HDM) in the presence or absence of dexamethasone (DEX). The same batch of human bronchial epithelial cells in exponential growth phase was randomly divided into five groups: blank group (A), 300 ng/mL HDM group (B), 1000 ng/mL HDM group (C), 3000 ng/mL HDM group (D), and 300 ng/mL HDM+100 ng/mL DEX group (E). The IL-29 mRNA expression was detected by quantitative reverse transcription polymerase chain reaction (qRT-PCR). The IL-29 protein expression in cell suspension was detected by ELISA. The results showed that after stimulation with HDM for 24 h, the expression of IL-29 was increased significantly, and after co-stimulation with HDM and DEX for 24 h, the expression of IL-29 in group E was significantly lower than that in the groups stimulated by HDM alone but higher than that in the group A. The differences between the different groups were significant (F=132.957, P<0.01). Additionally, the higher the concentration of HDM was, the more significant the increase in the IL-29 expression was. In conclusion, IL-29 may play a role in the progression of airway allergic disease including asthma.

Interferon-λ: Immune Functions at Barrier Surfaces and Beyond

When type III interferon (IFN-λ; also known as interleukin-28 [IL-28] and IL-29) was discovered in 2003, its antiviral function was expected to be analogous to that of type I IFNs (IFN-α and IFN-β) via the induction of IFN-stimulated genes (ISGs). Although IFN-λ stimulates expression of antiviral ISGs preferentially in cells of epithelial origin, recent studies have defined additional antiviral mechanisms in other cell types and tissues. Viral infection models using mice lacking IFN-λ signaling and SNP associations with human disease have expanded our understanding of the contribution of IFN-λ to the antiviral response at anatomic barriers and the immune response beyond these barriers. In this review, we highlight recent insights into IFN-λ functions, including its ability to restrict virus spread into the brain and to clear chronic viral infections in the gastrointestinal tract. We also discuss how IFN-λ modulates innate and adaptive immunity, autoimmunity, and tumor progression and its possible therapeutic applications in human disease.

Viral Load in Infants Hospitalized for Respiratory Syncytial Virus Bronchiolitis Correlates with Recurrent Wheezing at Thirty-Six-Month Follow-Up

The relationship between viral infection, host immune response in infants with respiratory syncytial virus (RSV) bronchiolitis and subsequent wheezing is discussed. We measured RSV-RNA load and interferon-λ1-3 expression in the nasopharyngeal washings from 68 infants hospitalized for RSV bronchiolitis, and wheezing was assessed 36 months after the first episode of bronchiolitis. Higher RSV-RNA load and higher interferon-λ2/3 levels were found in children with recurrent wheezing at 36-month follow-up.

Interferons and systemic sclerosis: correlation between interferon gamma and interferon-lambda 1 (IL-29)

BACKGROUND

Interferon (IFN)-λ1 is a newly described cytokine, member of type III interferons family, which is known for its antiviral, anti-proliferative and antitumor activity. Recent studies indicated that this cytokine has also immune-regulatory function, but its role in the pathogenesis of autoimmune diseases is not established yet. We evaluated serum levels of IFN-λ1 in systemic sclerosis (SSc) patients and healthy controls and its association with IFN-γ and clinical manifestations.

METHODS

IFN-λ1 and IFN-γ serum levels were measured by ELISA from 52 patients with SSc and 53 healthy controls. Association of cytokines serum levels was sought with clinical parameters.

RESULTS

IFN-λ1 and IFN-γ levels in SSc patients were significantly higher than those in healthy individuals (24.82 ± 8.78 and 11.04 ± 3.04 pg/ml, p < 0.0001; 34.11 ± 8.11 and 10.73 ± 2.77 pg/ml, p < 0.0001, respectively). We found a positive correlation between IFN-λ1 and IFN-γ levels in SSc patients (p = 0.0103, r = 0.3526). IFN-γ levels were associated with muscle involvement (p = 0.0483).

CONCLUSION

We first showed raised IFN-λ1 levels in SSc patients. Furthermore, we found a correlation between IFN-λ1 and IFN-γ levels and an association between IFN-γ and myositis. Additional in vitro and in vivo studies are needed to understand IFN-λ1 role in SSc.