Evangelos Andreakos

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

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

Amphoteric liposomes enable systemic antigen‐presenting cell–directed delivery of CD40 antisense and are therapeutically effective in experimental arthritis

OBJECTIVEnMediation of RNA interference by oligonucleotides constitutes a powerful approach for the silencing of genes involved in the pathogenesis of inflammatory disease, but in vivo application of this technique requires effective delivery to immune cells and/or sites of inflammation. The aim of the present study was to develop a new carrier system to mediate systemic administration of oligonucleotides to rheumatoid arthritis (RA) joints, and to develop an antisense oligonucleotide (ASO)-based approach to interfere with CD40-CD154 interactions in an experimental model of RA.nnnMETHODSnA novel liposomal carrier with amphoteric properties, termed Nov038, was developed and assessed for its ability to systemically deliver an ASO directed against CD40 (CD40-ASO). Male DBA/1 mice with collagen-induced arthritis were treated with Nov038-encapsulated CD40-ASO, and the effects of treatment on various parameters of disease activity, including clinical score, paw swelling, lymph node responses, and inflammatory cytokine production in the joints, were assessed.nnnRESULTSnNov038 was well tolerated, devoid of immune-stimulatory effects, and efficacious in mediating systemic oligonucleotide delivery to sites of inflammation. In mice with collagen-induced arthritis, Nov038 enabled the therapeutic administration of CD40-ASO and improved established disease, while unassisted CD40-ASO was ineffective, and anti-tumor necrosis factor alpha (anti-TNFalpha) treatment was less effective in this model. Nov038/CD40-ASO efficacy was attributed to its tropism for monocyte/macrophages and myeloid dendritic cells (DCs), resulting in rapid down-regulation of CD40, inhibition of DC antigen presentation, and reduction in collagen-specific T cell responses, as well as decreased levels of TNFalpha, interleukin-6 (IL-6), and IL-17 in arthritic joints.nnnCONCLUSIONnAmphoteric liposomes represent a novel carrier concept for systemic and antigen-presenting cell-targeted oligonucleotide delivery with clinical applicability and numerous potential applications, including target validation in vivo and inflammatory disease therapeutics. Moreover, Nov038/CD40-ASO constitutes a potent alternative to monoclonal antibody-based approaches for interfering with CD40-CD40L interactions.

Interferon-λ Mediates Non-redundant Front-Line Antiviral Protection against Influenza Virus Infection without Compromising Host Fitness

Summary Lambda interferons (IFN&lgr;s) or type III IFNs share homology, expression patterns, signaling cascades, and antiviral functions with type I IFNs. This has complicated the unwinding of their unique non‐redundant roles. Through the systematic study of influenza virus infection in mice, we herein show that IFN&lgr;s are the first IFNs produced that act at the epithelial barrier to suppress initial viral spread without activating inflammation. If infection progresses, type I IFNs come into play to enhance viral resistance and induce pro‐inflammatory responses essential for confronting infection but causing immunopathology. Central to this are neutrophils which respond to both cytokines to upregulate antimicrobial functions but exhibit pro‐inflammatory activation only to type I IFNs. Accordingly, Ifnlr1−/− mice display enhanced type I IFN production, neutrophilia, lung injury, and lethality, while therapeutic administration of PEG‐IFN&lgr; potently suppresses these effects. IFN&lgr;s therefore constitute the front line of antiviral defense in the lung without compromising host fitness. Graphical Abstract Figure. No Caption available. HighlightsIFN&lgr;s are the first IFNs produced that suppress initial viral spreadIFN&lgr;s exhibit potent antiviral functions without activating inflammationType I IFNs come up later to enhance antiviral and pro‐inflammatory responsesIFN&lgr;s and type I IFNs ensure optimal viral clearance with minimal collateral damage &NA; The importance of IFN&lgr;s in the respiratory tract remains puzzling. Galani and colleagues show that IFN&lgr;s provide front‐line antiviral protection without activating inflammation. When infection escapes IFN&lgr; control, type I IFNs come into play to enhance antiviral defenses and trigger pro‐inflammatory responses essential for confronting infection but causing immunopathology.

Neutrophils in viral infections: Current concepts and caveats

Neutrophils are the first immune cell population recruited to sites of infection, including viral infections, and exhibit both protective and pathologic functions. In antibacterial and antifungal immunity, the role of neutrophils is well defined. However, in antiviral immunity, much less is known. Conventional wisdom suggests that neutrophils enhance antiviral defenses, yet evidence for that is limited. Interaction with other immune cell populations, virus internalization and killing, the release of cytokines, chemokines, and antimicrobial components are all mechanisms by which neutrophils can contribute to pathogen clearance. NET formation, extensively studied during bacterial infection, can further mediate antiviral defense by trapping and inactivating virus. In the present review, we discuss the current understanding of the complex role of neutrophil immunity in viral infections and disease pathogenesis and the potential mechanisms identified to date. We pinpoint the importance of a finely tuned neutrophilic response for achieving effective immune protection while avoiding detrimental tissue damage that can form the basis for the development of novel therapeutics.

Toll-like receptor 7 stimulates production of specialized pro-resolving lipid mediators and promotes resolution of airway inflammation

Although specialized pro‐resolving mediators (SPMs) biosynthesized from polyunsaturated fatty acids are critical for the resolution of acute inflammation, the molecules and pathways that induce their production remain elusive. Here, we show that TLR7, a receptor recognizing viral ssRNA and damaged self‐RNA, mobilizes the docosahexaenoic acid (DHA)‐derived biosynthetic pathways that lead to the generation of D‐series SPMs. In mouse macrophages and human monocytes, TLR7 activation triggered production of DHA‐derived monohydroxy metabolome markers and generation of protectin D1 (PD1) and resolvin D1 (RvD1). In mouse allergic airway inflammation, TLR7 activation enhanced production of DHA‐derived SPMs including PD1 and accelerated the catabasis of Th2‐mediated inflammation. D‐series SPMs were critical for TLR7‐mediated resolution of airway inflammation as this effect was lost in Alox15−/− mice, while resolution was enhanced after local administration of PD1 or RvD1. Together, our findings reveal a new previously unsuspected role of TLR7 in the generation of D‐series SPMs and the resolution of allergic airway inflammation. They also identify TLR stimulation as a new approach to drive SPMs and resolution of inflammatory diseases.

Therapeutic human monoclonal antibodies in inflammatory diseases.

Monoclonal antibodies (mAbs) are antibodies of a single antigen specificity produced by identical immune cells, i.e., clones of a common germ cell. They offer unprecedented opportunities to drug development because of their ability to target almost any cell surface or secreted molecule with remarkable efficacy and safety. In this chapter, the application of human mAbs in the treatment of inflammatory diseases is reviewed. We discuss in detail several mAb-based drugs such as anti-tumor necrosis factor (anti-TNF), anti-interleukin-1 (anti-IL-1) receptor, anti-IL-6 receptor, anti-α4 integrin subunit, and anti-CD20 agents, all of which have been documented by clinical trials to be efficacious and have been approved for the therapy of several inflammatory and immune diseases, including rheumatoid arthritis, Crohns disease, ulcerative colitis, spondyloarthropathies, juvenile arthritis, psoriasis, psoriatic arthritis, and others. These novel drugs can be used either as a monotherapy or in combination with other conventional therapeutic modalities, particularly if the disease under treatment is refractory to therapy using solely conventional techniques. As a large variety of mAb-based agents targeting a plethora of cytokines, chemokines, adhesion and co-stimulatory molecules, receptors, as well as diverse cell types, are presently under investigation, the therapeutic armamentarium of the clinician is expected to greatly broaden in the near future, providing improved patient care for a wide range of devastating diseases of our times.

Activation of the canonical bone morphogenetic protein (BMP) pathway during lung morphogenesis and adult lung tissue repair.

Signaling by Bone Morphogenetic Proteins (BMP) has been implicated in early lung development, adult lung homeostasis and tissue-injury repair. However, the precise mechanism of action and the spatio-temporal pattern of BMP-signaling during these processes remains inadequately described. To address this, we have utilized a transgenic line harboring a BMP-responsive eGFP-reporter allele (BRE-eGFP) to construct the first detailed spatiotemporal map of canonical BMP-pathway activation during lung development, homeostasis and adult-lung injury repair. We demonstrate that during the pseudoglandular stage, when branching morphogenesis progresses in the developing lung, canonical BMP-pathway is active mainly in the vascular network and the sub-epithelial smooth muscle layer of the proximal airways. Activation of the BMP-pathway becomes evident in epithelial compartments only after embryonic day (E) 14.5 primarily in cells negative for epithelial-lineage markers, located in the proximal portion of the airway-tree, clusters adjacent to neuro-epithelial-bodies (NEBs) and in a substantial portion of alveolar epithelial cells. The pathway becomes activated in isolated E12.5 mesenchyme-free distal epithelial buds cultured in Matrigel suggesting that absence of reporter activity in these regions stems from a dynamic cross-talk between endoderm and mesenchyme. Epithelial cells with activated BMP-pathway are enriched in progenitors capable of forming colonies in three-dimensional Matrigel cultures. As lung morphogenesis approaches completion, eGFP-expression declines and in adult lung its expression is barely detectable. However, upon tissue-injury, either with naphthalene or bleomycin, the canonical BMP-pathways is re-activated, in bronchial or alveolar epithelial cells respectively, in a manner reminiscent to early lung development and in tissue areas where reparatory progenitor cells reside. Our studies illustrate the dynamic activation of canonical BMP-pathway during lung development and adult lung tissue-repair and highlight its involvement in two important processes, namely, the early development of the pulmonary vasculature and the management of epithelial progenitor pools both during lung development and repair of adult lung tissue-injury.

Activin, neutrophils, and inflammation: just coincidence?

During the 26xa0years that have elapsed since its discovery, activin-A, a member of the transforming growth factor β super-family originally discovered from its capacity to stimulate follicle-stimulating hormone production by cultured pituitary gonadotropes, has been established as a key regulator of various fundamental biological processes, such as development, homeostasis, inflammation, and tissue remodeling. Deregulated expression of activin-A has been observed in several human diseases characterized by an immuno-inflammatory and/or tissue remodeling component in their pathophysiology. Various cell types have been recognized as sources of activin-A, and plentiful, occasionally contradicting, functions have been described mainly by in vitro studies. Not surprisingly, both harmful and protective roles have been postulated for activin-A in the context of several disorders. Recent findings have further expanded the functional repertoire of this molecule demonstrating that its ectopic overexpression in mouse airways can cause pathology that simulates faithfully human acute respiratory distress syndrome, a disorder characterized by strong involvement of neutrophils. This finding when considered together with the recent discovery that neutrophils constitute an important source of activin-A in vivo and earlier observations of upregulated activin-A expression in diseases characterized by strong activation of neutrophils may collectively imply a more intimate link between activin-A expression and neutrophil reactivity. In this review, we provide an outline of the functional repertoire of activin-A and suggest that this growth factor functions as a guardian of homeostasis, a modulator of immunity and an orchestrator of tissue repair activities. In this context, a relationship between activin-A and neutrophils may be anything but coincidental.

Type III interferons (IFNs): Emerging Master Regulators of Immunity.

Lambda interferons (IFN-λs), type III interferons or interleukins 28 and 29 are the latest addition to the class II cytokine family. They share low homology with the interferon (IFN) and IL-10 cytokine families, yet they exhibit common and unique activities, the full spectrum of which still remains incompletely understood. Although initially described for their antiviral functions, it is now appreciated that IFN-λs also mediate diverse antitumor and immune-modulatory effects, and are key determinants of innate immunity at mucosal sites such as the gastrointestinal and respiratory tracks. Here, we are reviewing the biological functions of IFN-λs, the mechanisms controlling their expression, their downstream effects and their role in the maintenance of homeostasis and disease. We are also exploring the potential application of IFN-λs as novel therapeutics.

IL-25: The Missing Link Between Allergy, Viral Infection, and Asthma?

Interleukin 25 boosts proinflammatory and proasthmatic responses in the allergic lung and emerges as a key determinant of virally induced asthma exacerbations and as a therapeutic target for asthma (Beale et al., this issue). Interleukin 25 boosts proinflammatory and proasthmatic responses in the allergic lung and emerges as a key determinant of virally induced asthma exacerbations and as a therapeutic target for asthma (Beale et al., this issue).