Jonathan Macintyre

Rhinovirus-induced IL-25 in asthma exacerbation drives type 2 immunity and allergic pulmonary inflammation.

IL-25 critically links rhinovirus infection and allergic asthma exacerbations. IL-25 Horns in on Asthma Attacks The common cold isn’t so common in people with asthma. Rhinoviruses—the main causes of the common cold—can make asthma attacks worse. Now, Beale et al. report that one way this happens is because rhinoviruses can induce interleukin-25 (IL-25) in lung epithelial cells. They found that IL-25 is more highly expressed in people with asthma than in healthy controls. In a mouse model of allergic asthma, rhinovirus infection induced IL-25 production, and blocking the IL-25 receptor could reduce rhinovirus-induced symptom exacerbation. These data suggest that blocking IL-25 is a promising therapeutic strategy in asthmatics, something to consider as the cold season approaches. Rhinoviruses (RVs), which are the most common cause of virally induced asthma exacerbations, account for much of the burden of asthma in terms of morbidity, mortality, and associated cost. Interleukin-25 (IL-25) activates type 2–driven inflammation and is therefore potentially important in virally induced asthma exacerbations. To investigate this, we examined whether RV-induced IL-25 could contribute to asthma exacerbations. RV-infected cultured asthmatic bronchial epithelial cells exhibited a heightened intrinsic capacity for IL-25 expression, which correlated with donor atopic status. In vivo human IL-25 expression was greater in asthmatics at baseline and during experimental RV infection. In addition, in mice, RV infection induced IL-25 expression and augmented allergen-induced IL-25. Blockade of the IL-25 receptor reduced many RV-induced exacerbation-specific responses including type 2 cytokine expression, mucus production, and recruitment of eosinophils, neutrophils, basophils, and T and non-T type 2 cells. Therefore, asthmatic epithelial cells have an increased intrinsic capacity for expression of a pro–type 2 cytokine in response to a viral infection, and IL-25 is a key mediator of RV-induced exacerbations of pulmonary inflammation.

Rhinovirus 16–induced IFN-α and IFN-β are deficient in bronchoalveolar lavage cells in asthmatic patients

BACKGROUND Asthmatic patients have defective rhinovirus-induced IFN-β and IFN-λ production from bronchial epithelial cells and IFN-λ from bronchoalveolar lavage (BAL) cells. Whether bronchoalveolar lavage cells have defective type I interferon responses to rhinovirus is unknown, as are mechanisms explaining defective rhinovirus interferon induction in asthmatic patients. OBJECTIVE We sought to investigate rhinovirus induction of type I interferons in BAL and blood mononuclear cells from asthmatic patients and healthy subjects and to investigate mechanisms of any deficiency observed. METHODS BAL and blood mononuclear cells from atopic asthmatic patients and healthy subjects were infected with rhinovirus ex vivo. Interferon proteins were analyzed by using ELISA. mRNA expression of key components of interferon induction pathways were analyzed by using quantitative PCR. RESULTS Rhinovirus induction of type I interferon protein was delayed and deficient in BAL cells from asthmatic patients, and lower interferon levels were associated with greater airway hyperresponsiveness and skin prick test response positivity. Expression of Toll-like receptor (TLR) 3, TLR7, TLR8, retinoic acid-inducible gene I (RIG-I), melanoma differentiation-associated gene 5 (MDA-5), TIR domain-containing adapter-inducing IFN-β (TRIF), myeloid differentiation primary response gene 88 (MyD88), caspase recruitment domain adaptor inducing IFN-β (CARDIF), IL-1 receptor-associated kinase 4 (IRAK4), IκB kinase β (IKKB), IκB kinase ι (IKKI), interferon regulatory factors 3 and 7, and rhinovirus induction of expression of the virus-inducible molecules TLR3, TLR7, RIG-I, and MDA-5 were not impaired in these interferon-deficient BAL cells in asthmatic patients. Defective rhinovirus interferon induction was not observed in blood mononuclear cells. CONCLUSIONS Rhinovirus induction of type I interferons in BAL cells is delayed and deficient and might be a marker of more severe asthma. Defective rhinovirus interferon induction in asthmatic patients was not accompanied by differences in the expression or induction of key molecules implicated in viral induction of interferons.

Rhinovirus-induced interferon production is not deficient in well controlled asthma

Background Defective rhinovirus (RV)-induced interferon (IFN)-β and IFN-λ production and increased RV replication have been reported in primary human bronchial epithelial cells (HBECs) from subjects with asthma. How universal this defect is in asthma is unknown. Additionally, the IFN subtypes induced by RV infection in primary HBECs have not been comprehensively investigated. Objective To study RV induction of IFN-α, IFN-β and IFN-λ and RV replication in HBECs from subjects with atopic asthma and healthy controls. Methods HBECs were obtained from subjects with asthma and healthy controls and infected with RV16 and RV1B, and cells and supernatants harvested at 8, 24 and 48h. IFN proteins were analysed by ELISA and IFN mRNA and viral RNA expression by quantitative PCR. Virus release was assessed in cell supernatants. Results IFN-β and IFN-λ were the only IFNs induced by RV in HBECs and IFN-λ protein induction was substantially greater than IFN-β. Induction of IFN-λ1 mRNA by RV16 at 48h was significantly greater in HBECs from subjects with asthma; otherwise there were no significant differences between subjects with asthma and controls in RV replication, or in induction of type I or III IFN protein or mRNA. Conclusions IFN-λ and, to a lesser degree, IFN-β are the major IFN subtypes induced by RV infection of HBECs. Neither defective IFN induction by RV nor increased RV replication was observed in the HBECs from subjects with well controlled asthma reported in this study.

Increased nuclear suppressor of cytokine signaling 1 in asthmatic bronchial epithelium suppresses rhinovirus induction of innate interferons

Background Rhinovirus infections are the dominant cause of asthma exacerbations, and deficient virus induction of IFN-α/β/λ in asthmatic patients is important in asthma exacerbation pathogenesis. Mechanisms causing this interferon deficiency in asthmatic patients are unknown. Objective We sought to investigate the expression of suppressor of cytokine signaling (SOCS) 1 in tissues from asthmatic patients and its possible role in impaired virus-induced interferon induction in these patients. Methods We assessed SOCS1 mRNA and protein levels in vitro, bronchial biopsy specimens, and mice. The role of SOCS1 was inferred by proof-of-concept studies using overexpression with reporter genes and SOCS1-deficient mice. A nuclear role of SOCS1 was shown by using bronchial biopsy staining, overexpression of mutant SOCS1 constructs, and confocal microscopy. SOCS1 levels were also correlated with asthma-related clinical outcomes. Results We report induction of SOCS1 in bronchial epithelial cells (BECs) by asthma exacerbation–related cytokines and by rhinovirus infection in vitro. We found that SOCS1 was increased in vivo in bronchial epithelium and related to asthma severity. SOCS1 expression was also increased in primary BECs from asthmatic patients ex vivo and was related to interferon deficiency and increased viral replication. In primary human epithelium, mouse lung macrophages, and SOCS1-deficient mice, SOCS1 suppressed rhinovirus induction of interferons. Suppression of virus-induced interferon levels was dependent on SOCS1 nuclear translocation but independent of proteasomal degradation of transcription factors. Nuclear SOCS1 levels were also increased in BECs from asthmatic patients. Conclusion We describe a novel mechanism explaining interferon deficiency in asthmatic patients through a novel nuclear function of SOCS1 and identify SOCS1 as an important therapeutic target for asthma exacerbations.

TLR3, TLR4 and TLRs7–9 Induced Interferons Are Not Impaired in Airway and Blood Cells in Well Controlled Asthma

Defective Rhinovirus induced interferon-β and interferon-λ production has been reported in bronchial epithelial cells from asthmatics but the mechanisms of defective interferon induction in asthma are unknown. Virus infection can induce interferon through Toll like Receptors (TLR)3, TLR7 and TLR8. The role of these TLRs in interferon induction in asthma is unclear. This objective of this study was to measure the type I and III interferon response to TLR in bronchial epithelial cells and peripheral blood cells from atopic asthmatics and non-atopic non-asthmatics. Bronchial epithelial cells and peripheral blood mononuclear cells from atopic asthmatic and non-atopic non-asthmatic subjects were stimulated with agonists to TLR3, TLR4 & TLRs7–9 and type I and III interferon and pro-inflammatory cytokine, interleukin(IL)-6 and IL-8, responses assessed. mRNA expression was analysed by qPCR. Interferon proteins were analysed by ELISA. Pro-inflammatory cytokines were induced by each TLR ligand in both cell types. Ligands to TLR3 and TLR7/8, but not other TLRs, induced interferon-β and interferon-λ in bronchial epithelial cells. The ligand to TLR7/8, but not those to other TLRs, induced only type I interferons in peripheral blood mononuclear cells. No difference was observed in TLR induced interferon or pro-inflammatory cytokine production between asthmatic and non-asthmatic subjects from either cell type. TLR3 and TLR7/8,, stimulation induced interferon in bronchial epithelial cells and peripheral blood mononuclear cells. Interferon induction to TLR agonists was not observed to be different in asthmatics and non-asthmatics.

Sarcoidosis and tuberculosis cytokine profiles: indistinguishable in bronchoalveolar lavage but different in blood.

Background The clinical, radiological and pathological similarities between sarcoidosis and tuberculosis can make disease differentiation challenging. A complicating factor is that some cases of sarcoidosis may be initiated by mycobacteria. We hypothesised that immunological profiling might provide insight into a possible relationship between the diseases or allow us to distinguish between them. Methods We analysed bronchoalveolar lavage (BAL) fluid in sarcoidosis (n = 18), tuberculosis (n = 12) and healthy volunteers (n = 16). We further investigated serum samples in the same groups; sarcoidosis (n = 40), tuberculosis (n = 15) and healthy volunteers (n = 40). A cross-sectional analysis of multiple cytokine profiles was performed and data used to discriminate between samples. Results We found that BAL profiles were indistinguishable between both diseases and significantly different from healthy volunteers. In sera, tuberculosis patients had significantly lower levels of the Th2 cytokine interleukin-4 (IL-4) than those with sarcoidosis (p = 0.004). Additional serum differences allowed us to create a linear regression model for disease differentiation (within-sample accuracy 91%, cross-validation accuracy 73%). Conclusions These data warrant replication in independent cohorts to further develop and validate a serum cytokine signature that may be able to distinguish sarcoidosis from tuberculosis. Systemic Th2 cytokine differences between sarcoidosis and tuberculosis may also underly different disease outcomes to similar respiratory stimuli.

Experimental rhinovirus 16 infection in moderate asthmatics on inhaled corticosteroids

To the Editor : The majority of asthma exacerbations are associated with respiratory virus infections, mostly rhinoviruses (RVs) [1], due to enhanced inflammation in the airways [2]. These occur despite symptom control with inhaled corticosteroids (ICS) [3]. Experimental RV infection is a valuable tool for studying virus-induced exacerbations [2, 4], but has, to date, involved only corticosteroid-naive asthmatics. We have, therefore, modified a validated infection protocol [4] to inoculate 11 subjects whose asthma was well controlled with ICS. As this was the first experimental infection in patients at risk of severe exacerbations, a cautious study design was implemented. All subjects were followed-up twice daily by SMS text messages during the study. We used RV16, a strain used safely in previous studies, which replicates in vitro to a similar extent but induces less inflammation and cell death than other strains [5]. We also chose a 10-fold lower inoculation dose of the same stock used in previous studies [6]. The design allowed for dose escalation if necessary (this proved to be unnecessary as all subjects developed cold symptoms at this dose). As a final precaution, the delivery device generated particles of 30–100 μm, restricting delivery to the nose (aerosols ≥16 μm are deposited in the upper respiratory tract (URT) [7]), thus closely mimicking natural infection, i.e. limiting direct lung exposure during inoculation. Symptoms of URT infection, asthma, and measurements of lower respiratory tract (LRT) function were recorded post-inoculation. Infection was confirmed by quantitative (q)PCR for RV16 in nasal lavage and sputum and by determining serum anti-RV16 titres. At least a ≥four-fold increase in titres in convalescent serum or shedding of RV16 in the airways was evidence of successful infection. We also studied innate immune responses …

Rhinovirus induction of fractalkine (CX3CL1) in airway and peripheral blood mononuclear cells in asthma

Rhinovirus infection is associated with the majority of asthma exacerbations. The role of fractalkine in anti-viral (type 1) and pathogenic (type 2) responses to rhinovirus infection in allergic asthma is unknown. To determine whether (1) fractalkine is produced in airway cells and in peripheral blood leucocytes, (2) rhinovirus infection increases production of fractalkine and (3) levels of fractalkine differ in asthmatic compared to non-asthmatic subjects. Fractalkine protein and mRNA levels were measured in bronchoalveolar lavage (BAL) cells and peripheral blood mononuclear cells (PBMCs) from non-asthmatic controls (n = 15) and mild allergic asthmatic (n = 15) subjects. Protein levels of fractalkine were also measured in macrophages polarised ex vivo to give M1 (type 1) and M2 (type 2) macrophages and in BAL fluid obtained from mild (n = 11) and moderate (n = 14) allergic asthmatic and non-asthmatic control (n = 10) subjects pre and post in vivo rhinovirus infection. BAL cells produced significantly greater levels of fractalkine than PBMCs. Rhinovirus infection increased production of fractalkine by BAL cells from non-asthmatic controls (P<0.01) and in M1-polarised macrophages (P<0.05), but not in BAL cells from mild asthmatics or in M2 polarised macrophages. Rhinovirus induced fractalkine in PBMCs from asthmatic (P<0.001) and healthy control subjects (P<0.05). Trends towards induction of fractalkine in moderate asthmatic subjects during in vivo rhinovirus infection failed to reach statistical significance. Fractalkine may be involved in both immunopathological and anti-viral immune responses to rhinovirus infection. Further investigation into how fractalkine is regulated across different cell types and into the effect of stimulation including rhinovirus infection is warranted to better understand the precise role of this unique dual adhesion factor and chemokine in immune cell recruitment.