Musa Khaitov

IL-33–Dependent Type 2 Inflammation during Rhinovirus-induced Asthma Exacerbations In Vivo

RATIONALE Rhinoviruses are the major cause of asthma exacerbations; however, its underlying mechanisms are poorly understood. We hypothesized that the epithelial cell-derived cytokine IL-33 plays a central role in exacerbation pathogenesis through augmentation of type 2 inflammation. OBJECTIVES To assess whether rhinovirus induces a type 2 inflammatory response in asthma in vivo and to define a role for IL-33 in this pathway. METHODS We used a human experimental model of rhinovirus infection and novel airway sampling techniques to measure IL-4, IL-5, IL-13, and IL-33 levels in the asthmatic and healthy airways during a rhinovirus infection. Additionally, we cultured human T cells and type 2 innate lymphoid cells (ILC2s) with the supernatants of rhinovirus-infected bronchial epithelial cells (BECs) to assess type 2 cytokine production in the presence or absence of IL-33 receptor blockade. MEASUREMENTS AND MAIN RESULTS IL-4, IL-5, IL-13, and IL-33 are all induced by rhinovirus in the asthmatic airway in vivo and relate to exacerbation severity. Further, induction of IL-33 correlates with viral load and IL-5 and IL-13 levels. Rhinovirus infection of human primary BECs induced IL-33, and culture of human T cells and ILC2s with supernatants of rhinovirus-infected BECs strongly induced type 2 cytokines. This induction was entirely dependent on IL-33. CONCLUSIONS IL-33 and type 2 cytokines are induced during a rhinovirus-induced asthma exacerbation in vivo. Virus-induced IL-33 and IL-33-responsive T cells and ILC2s are key mechanistic links between viral infection and exacerbation of asthma. IL-33 inhibition is a novel therapeutic approach for asthma exacerbations.

Respiratory virus induction of alpha-, beta- and lambda-interferons in bronchial epithelial cells and peripheral blood mononuclear cells.

Background:  Respiratory viruses, predominantly rhinoviruses are the major cause of asthma exacerbations. Impaired production of interferon‐β in rhinovirus infected bronchial epithelial cells (BECs) and of the newly discovered interferon‐λs in both BECs and bronchoalveolar lavage cells, is implicated in asthma exacerbation pathogenesis. Thus replacement of deficient interferon is a candidate new therapy for asthma exacerbations. Rhinoviruses and other respiratory viruses infect both BECs and macrophages, but their relative capacities for α‐, β‐ and λ‐interferon production are unknown.

An anti-human ICAM-1 antibody inhibits rhinovirus-induced exacerbations of lung inflammation.

Human rhinoviruses (HRV) cause the majority of common colds and acute exacerbations of asthma and chronic obstructive pulmonary disease (COPD). Effective therapies are urgently needed, but no licensed treatments or vaccines currently exist. Of the 100 identified serotypes, ∼90% bind domain 1 of human intercellular adhesion molecule-1 (ICAM-1) as their cellular receptor, making this an attractive target for development of therapies; however, ICAM-1 domain 1 is also required for host defence and regulation of cell trafficking, principally via its major ligand LFA-1. Using a mouse anti-human ICAM-1 antibody (14C11) that specifically binds domain 1 of human ICAM-1, we show that 14C11 administered topically or systemically prevented entry of two major groups of rhinoviruses, HRV16 and HRV14, and reduced cellular inflammation, pro-inflammatory cytokine induction and virus load in vivo. 14C11 also reduced cellular inflammation and Th2 cytokine/chemokine production in a model of major group HRV-induced asthma exacerbation. Interestingly, 14C11 did not prevent cell adhesion via human ICAM-1/LFA-1 interactions in vitro, suggesting the epitope targeted by 14C11 was specific for viral entry. Thus a human ICAM-1 domain-1-specific antibody can prevent major group HRV entry and induction of airway inflammation in vivo.

CXC chemokines and antimicrobial peptides in rhinovirus‐induced experimental asthma exacerbations

Rhinoviruses (RVs) are the major triggers of asthma exacerbations. We have shown previously that lower respiratory tract symptoms, airflow obstruction, and neutrophilic airway inflammation were increased in experimental RV‐induced asthma exacerbations.

RSV infection modulates IL-15 production and MICA levels in respiratory epithelial cells

The cytokine interleukin (IL)-15, major histocompatibility complex (MHC) class I molecules and MHC class I chain-related proteins (MIC) A and B are involved in cellular immune responses to virus infections but their role in respiratory syncytial virus (RSV) infection has not been studied. We aimed to determine how RSV infection modulates IL-15 production, MHC class I and MICA expression in respiratory epithelial cells, the molecular pathways implicated in virus-induced IL-15 production and how interferon (IFN)-&ggr; alters RSV-induced IL-15 production and MHC class I and MICA expression. We infected respiratory epithelial cell lines (A549 and BEAS-2B cells) and primary bronchial epithelial cells with RSV and measured production of IL-15, expression of MHC I and MICA and the role of the transcription factor nuclear factor (NF)-&kgr;B. We report here that RSV increases IL-15 in respiratory epithelial cells via virus replication and NF-&kgr;B-dependent mechanisms. Furthermore, RSV infection of epithelial cells upregulated cell surface expression of MICA and levels of soluble MICA. IFN-&ggr; upregulated RSV induction of soluble IL-15 but inhibited induction of MICA. Upregulation of IL-15, MHC I and MICA are likely to be important mechanisms in activating immune responses to RSV by epithelial cells.

Allergen-Specific Immunotherapy with Monomeric Allergoid in a Mouse Model of Atopic Dermatitis

Atopic dermatitis (AD) is a widespread and difficult to treat allergic skin disease and is a tough challenge for healthcare. In this study, we investigated whether allergen-specific immunotherapy (ASIT) with a monomeric allergoid obtained by succinylation of ovalbumin (sOVA) is effective in a mouse model of atopic dermatitis. An experimental model of AD was reproduced by epicutaneous sensitization with ovalbumin (OVA). ASIT was performed with subcutaneous (SC) administration of increasing doses of OVA or sOVA. The levels of anti-OVA antibodies, as well as cytokines, were detected by ELISA. Skin samples from patch areas were taken for histologic examination. ASIT with either OVA or sOVA resulted in a reduction of both the anti-OVA IgE level and the IgG1/IgG2a ratio. Moreover, ASIT with sOVA increased the IFN-γ level in supernatants after splenocyte stimulation with OVA. Histologic analysis of skin samples from the sites of allergen application showed that ASIT improved the histologic picture by decreasing allergic inflammation in comparison with untreated mice. These data suggest that ASIT with a succinylated allergen represents promising approach for the treatment of AD.

Molecular Aspects of Allergens and Allergy

Immunoglobulin E (IgE)-associated allergy is the most common immune disorder. More than 30% of the population suffer from symptoms of allergy which are often severe, disabling, and life threatening such as asthma and anaphylaxis. Population-based birth cohort studies show that up to 60% of the world population exhibit IgE sensitization to allergens, of which most are protein antigens. Thirty years ago the first allergen-encoding cDNAs have been isolated. In the meantime, the structures of most of the allergens relevant for disease in humans have been solved. Here we provide an update regarding what has been learned through the use of defined allergen molecules (i.e., molecular allergology) and about mechanisms of allergic disease in humans. We focus on new insights gained regarding the process of sensitization to allergens, allergen-specific secondary immune responses, and mechanisms underlying allergic inflammation and discuss open questions. We then show how molecular forms of diagnosis and specific immunotherapy are currently revolutionizing diagnosis and treatment of allergic patients and how allergen-specific approaches may be used for the preventive eradication of allergy.

Next-Generation of Allergen-Specific Immunotherapies: Molecular Approaches

Purpose of ReviewThe aim of this article is to discuss how allergen-specific immunotherapy (AIT) can be improved through molecular approaches. We provide a summary of next-generation molecular AIT approaches and of their clinical evaluation. Furthermore, we discuss the potential of next generation molecular AIT forms for the treatment of severe manifestations of allergy and mention possible future molecular strategies for the secondary and primary prevention of allergy.Recent FindingsAIT has important advantages over symptomatic forms of allergy treatment but its further development is limited by the quality of the therapeutic antigen preparations which are derived from natural allergen sources. The field of allergy diagnosis is currently undergoing a dramatic improvement through the use of molecular testing with defined, mainly recombinant allergens which allows high-resolution diagnosis. Several studies demonstrate that molecular testing in early childhood can predict the development of symptomatic allergy later on in life.SummaryClinical studies indicate that molecular AIT approaches have the potential to improve therapy of allergic diseases and may be used as allergen-specific forms of secondary and eventually primary prevention for allergy.

The potential of anti-infectives and immunomodulators as therapies for asthma and asthma exacerbations

Asthma is responsible for approximately 25,000 deaths annually in Europe despite available medicines that maintain asthma control and reduce asthma exacerbations. Better treatments are urgently needed for the control of chronic asthma and reduction in asthma exacerbations, the major cause of asthma mortality. Much research spanning >20 years shows a strong association between microorganisms including pathogens in asthma onset, severity and exacerbation, yet with the exception of antibiotics, few treatments are available that specifically target the offending pathogens. Recent insights into the microbiome suggest that modulating commensal organisms within the gut or lung may also be a possible way to treat/prevent asthma. The European Academy of Allergy & Clinical Immunology Task Force on Anti‐infectives in Asthma was initiated to investigate the potential of anti‐infectives and immunomodulators in asthma. This review provides a concise summary of the current literature and aimed to identify and address key questions that concern the use of anti‐infectives and both microbe‐ and host‐based immunomodulators and their feasibility for use in asthma.

Microarray-based IgE serology improves management of severe atopic dermatitis in two children

To the Editor, Atopic dermatitis (AD) is one of the most common manifestations of IgE-associated allergy in childhood (1). In the prospective German MAS cohort, it was shown that AD begins before the age of 2 years and that sensitization to food allergens precedes sensitization to respiratory allergens, a process called atopic march (2). AD patients are often sensitized to a variety of foodand aeroallergens and exhibit elevated levels of serum IgE. Identification of disease-triggering food allergens is important when food allergies are suspected in young children so that appropriate diets can be prescribed (3). Current approaches for the treatment of AD are based on elimination diet, topical therapies and systemic immunosuppression, while data on efficacy of AIT in AD are contradictory. In this respect, allergy diagnosis in patients with AD is highly relevant, as it allows disease management by antigenspecific forms of treatment such as allergen avoidance and AIT. Molecular allergy diagnosis, earlier termed componentresolved diagnostics (CRD), is based on determining sensitization with purified natural or recombinant allergen molecules (4). CRD allows differentiation between genuine and crosssensitizations in polysensitized patients, assessing the risk of systemic reactions in food allergies and supports accurate prescription of AIT (5). Chips containing a broad panel of allergen molecules are particularly useful early in childhood because they allow to identify IgE sensitization towards a comprehensive set of allergens with small serum volumes (6). In this article, we exemplify for two cases of severe AD in children how molecular allergy diagnosis can profoundly improve disease management. A 6-year-old boy suffering from severe AD who was treated with systemic cyclosporine came to our department in June 2015 because of an AD exacerbation and eczema herpeticum (Fig. 1a, Figure S1A). Born in 2009, he was breastfed from birth till 6 months. At the age of 3 months, he began to develop atopic dermatitis (dryness, redness, itching of skin). Before the age of one year, consumption of goat’s and cow’s milk, fresh vegetables, fruits, chicken, egg, soy and wheat led to worsening of AD. At 4 years, he experienced severe angiooedema and urticaria immediately after consumption of a small piece of pork which had been boiled in pea soup. Since 2013, the boy was on strict diet eating only pork, buckwheat and cooked vegetables. Initially, he was treated with emollients and low-dose topical corticosteroids with good efficacy. Until August 2013 (age 4 years), AD was mild but then exacerbated. Since then, the course was severe and increasing doses of topical and systemic steroids as well as antihistamines were given with only short-term efficacy. In 2014, the boy started to suffer from extremely severe symptoms of AD. At that time, the first allergy diagnosis was performed revealing strongly elevated levels of total IgE (>2000 U/ml) and polysensitization to most foodand aeroallergens as detected by a multiplexed extractbased test (MAST) comprising 35 allergen extracts from food and respiratory allergen sources. Systemic therapy with cyclosporine was initiated. From July 2014, 75 mg/day was given, yielding moderate control of AD symptoms. When the dose was reduced to 50 mg/day, treatment became ineffective, so administration of 75 mg was resumed and increased to 100 mg/day with modest improvement. In May 2015, the boy started to suffer from severe herpes simplex infection (Kaposi’s varicelliform eruption, Fig. 1a, Figure S1A) and was treated with acyclovir (800 mg 5 times per day for 7 days). In June 2015, he was again referred to our department with generalized erythrodermia, severe dryness, erythema, multiple papules, excoriations, lichenification, infiltration of widespread skin areas, multiple post-herpetic spots (Fig. 1a, Figure S1A) and a SCORAD index of 82. Peripheral lymphnodes were enlarged up to 2–4 cm, the abdomen was bloated (Figure S1B), and liver and spleen were enlarged. Extract-based testing was inconclusive because IgE antibodies to all 35 tested allergen sources were found. Molecular allergy diagnosis using ImmunoCAP ISAC (ThermoFisher, Uppsala, Sweden) (Table 1, Table S1, case 1) showed that the boy was sensitized to certain types of food (egg: Gal d 1, 2, 3; milk: Bos d 4, 5, 8; storage proteins from several nuts; peanut: Ara h 1, 2, 3, 6; soybean; Gly m 5, 6; wheat: Tri a 11, 14, 19) while marker allergens for other food (e.g. fish, beef, pork, chicken meat, shrimp) were negative. We found broad crosssensitization to lipid transfer proteins, especially from wheat which showed the highest IgE reactivity (Tri a 14: 35 ISU-E) (Table 1, Table S1). Interestingly, sensitizations towards only few clinically relevant respiratory allergens, that is Bet v 1 from birch and other PR-10 proteins, Asp f 6 from Aspergillus, Hev b 1 and 6 from latex, were found. The broad reactivity with all allergen extracts was thus most likely caused by IgE to clinically irrelevant carbohydrate epitopes because the carbohydrate marker MUXF3 was positive (Table 1, Table S1). As sensitization to birch pollen and mould was the only respiratory sensitization, the severe perennial skin symptoms could thus be only explained by sensitization to certain food allergens. It was thus decided to stop cyclosporine treatment and to continue only with topical therapy (hydrocortisone, emollients), antihistamines and amino acid nutrition (Neocate up to 200–400 g/day). Under this treatment, skin symptoms improved promptly (Fig. 1b). Based on the results from molecular allergy diagnosis, fish, chicken, pork and beef, together with rice products and cooked potatoes as carbohydrate sources could be gradually reintroduced into the diet.