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
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.
ILC2; infection; Th2; virus
The nature of bronchial mucosal inflammation and its physiologic and clinical significance in rhinovirus-induced asthma exacerbations is unclear. We investigated bronchial mucosal inflammatory response and its association with physiologic and clinical outcomes in an experimental model of rhinovirus-induced asthma exacerbations.
We used immunohistochemistry methods to detect phenotypes of inflammatory cells infiltrating the bronchial mucosa before and after experimental rhinovirus infection in 10 subjects with asthma and 15 normal subjects.
Compared with baseline, rhinovirus infection significantly increased the number of epithelial (P = .005) and subepithelial (P = .017) neutrophils in subjects with asthma only and subepithelial CD68+ macrophages in both subjects with asthma (P = .009) and normal subjects (P = .018) but more so in those with asthma (P = .021). Numbers of CD45+, CD68+, and CD20+ cells; neutrophils; and eosinophils at day 4 postinfection were positively associated with virus load (r = 0.50-0.72, P = .016-0.03). At acute infection in subjects with asthma, CD4+ cells correlated with chest symptom scores (r = 0.69, P = .029), the fall in the 10% fall in FEV1 (PC10) correlated with neutrophils (r = −0.89, P = .029), the PC10 correlated inversely with CD4+ (r = −0.67, P = .023) and CD8+ cells (r = −0.65, P = .03), the 20% fall in FEV1 was inversely associated with CD20+ cells (r = −0.65, P = .03), and higher epithelial CD8+ cell counts were significantly associated with a greater maximum fall in FEV1 (r = −0.72, P = .03), whereas higher subepithelial mast cell counts were significantly associated with a lower maximum percent fall in peak expiratory flow (r = 0.8, P = .024).
In subjects with asthma, rhinovirus infection induces bronchial mucosal neutrophilia and more severe monocyte/macrophage infiltration than in normal subjects. Airway neutrophils, eosinophils, and T and B lymphocytes during infection are related to virus load and physiologic and clinical severity, whereas mast cells are related to greater lung function.
Rationale: Chronic obstructive pulmonary disease (COPD) exacerbations are associated with virus (mostly rhinovirus) and bacterial infections, but it is not known whether rhinovirus infections precipitate secondary bacterial infections.
Objectives: To investigate relationships between rhinovirus infection and bacterial infection and the role of antimicrobial peptides in COPD exacerbations.
Methods: We infected subjects with moderate COPD and smokers and nonsmokers with normal lung function with rhinovirus. Induced sputum was collected before and repeatedly after rhinovirus infection and virus and bacterial loads measured with quantitative polymerase chain reaction and culture. The antimicrobial peptides secretory leukoprotease inhibitor (SLPI), elafin, pentraxin, LL-37, α-defensins and β-defensin-2, and the protease neutrophil elastase were measured in sputum supernatants.
Measurements and Main Results: After rhinovirus infection, secondary bacterial infection was detected in 60% of subjects with COPD, 9.5% of smokers, and 10% of nonsmokers (P < 0.001). Sputum virus load peaked on Days 5–9 and bacterial load on Day 15. Sputum neutrophil elastase was significantly increased and SLPI and elafin significantly reduced after rhinovirus infection exclusively in subjects with COPD with secondary bacterial infections, and SLPI and elafin levels correlated inversely with bacterial load.
Conclusions: Rhinovirus infections are frequently followed by secondary bacterial infections in COPD and cleavage of the antimicrobial peptides SLPI and elafin by virus-induced neutrophil elastase may precipitate these secondary bacterial infections. Therapy targeting neutrophil elastase or enhancing innate immunity may be useful novel therapies for prevention of secondary bacterial infections in virus-induced COPD exacerbations.
rhinovirus; chronic obstructive pulmonary disease; disease exacerbation; bacteria
Respiratory syncytial virus (RSV) is a major cause of bronchiolitis in infants. It is also responsible for high morbidity and mortality in the elderly. Programmed death ligands (PD-Ls) on antigen-presenting cells interact with receptors on T cells to regulate immune responses. The programmed death receptor-ligand 1/programmed death receptor 1 (PD-L1-PD-1) pathway is inhibitory in chronic viral infections, but its role in acute viral infections is unclear. We hypothesized that bronchial epithelial cell (BEC) expression of PD-Ls would inhibit local effector CD8+ T cell function. We report that RSV infection of primary human BECs strongly induces PD-L1 expression. In a co-culture system of BECs with purified CD8+ T cells, we demonstrated that RSV-infected BECs increased CD8+ T cell activation, proliferation, and antiviral function. Blocking PD-L1 on RSV-infected BECs co-cultured with CD8+ T cells enhanced CD8+ T cell IFN-γ, IL-2, and granzyme B production. It also decreased the virus load of the BECs. Based on our findings, we believe therapeutic strategies that target the PD-L1-PD-1 pathway might increase antiviral immune responses to RSV and other acute virus infections.
Rationale: Respiratory virus infections are associated with chronic obstructive pulmonary disease (COPD) exacerbations, but a causative relationship has not been proven. Studies of naturally occurring exacerbations are difficult and the mechanisms linking virus infection to exacerbations are poorly understood. We hypothesized that experimental rhinovirus infection in subjects with COPD would reproduce the features of naturally occurring COPD exacerbations and is a valid model of COPD exacerbations.
Objectives: To evaluate experimental rhinovirus infection as a model of COPD exacerbation and to investigate the mechanisms of virus-induced exacerbations.
Methods: We used experimental rhinovirus infection in 13 subjects with COPD and 13 nonobstructed control subjects to investigate clinical, physiologic, pathologic, and antiviral responses and relationships between virus load and these outcomes.
Measurements and Main Results: Clinical data; inflammatory mediators in blood, sputum, and bronchoalveolar lavage; and viral load in nasal lavage, sputum, and bronchoalveolar lavage were measured at baseline and after infection with rhinovirus 16. After rhinovirus infection subjects with COPD developed lower respiratory symptoms, airflow obstruction, and systemic and airway inflammation that were greater and more prolonged compared with the control group. Neutrophil markers in sputum related to clinical outcomes and virus load correlated with inflammatory markers. Virus load was higher and IFN production by bronchoalveolar lavage cells was impaired in the subjects with COPD.
Conclusions: We have developed a new model of COPD exacerbation that strongly supports a causal relationship between rhinovirus infection and COPD exacerbations. Impaired IFN production and neutrophilic inflammation may be important mechanisms in virus-induced COPD exacerbations.
disease exacerbation; respiratory tract infections; COPD; rhinovirus
Influenza is a disease with global impact that causes enormous morbidity and mortality on an annual basis. It primarily infects the respiratory tract and causes a broad range of illness ranging from symptomless infection to fulminant primary viral and secondary bacterial pneumonia. The severity of infection depends on both the virus strain and a number of host factors, primarily age and the presence of comorbid conditions such as cardiopulmonary disease. The mortality and utilization of healthcare resources associated with influenza is concentrated in the elderly and those with coexisting disease such as chronic obstructive pulmonary disease (COPD). Increasing use of vaccination and the development of new antiviral drugs hold out hope that the burden of disease associated with influenza can be reduced. However the constant emergence of new influenza strains and the current risk of avian influenza pandemic serve as warnings that influenza will remain a serious pathogen for the foreseeable future.
COPD; influenza; exacerbations
Rationale: Idiopathic pulmonary fibrosis (IPF) is a progressive lung
disease of unknown cause that leads to respiratory failure and death within 5 years
of diagnosis. Overt respiratory infection and immunosuppression carry a high
morbidity and mortality, and polymorphisms in genes related to epithelial integrity
and host defense predispose to IPF.
Objectives: To investigate the role of bacteria in the pathogenesis and
progression of IPF.
Methods: We prospectively enrolled patients diagnosed with IPF according
to international criteria together with healthy smokers, nonsmokers, and subjects
with moderate chronic obstructive pulmonary disease as control subjects. Subjects
underwent bronchoalveolar lavage (BAL), from which genomic DNA was isolated. The
V3–V5 region of the bacterial 16S rRNA gene was amplified, allowing
quantification of bacterial load and identification of communities by 16S rRNA
quantitative polymerase chain reaction and pyrosequencing.
Measurements and Main Results: Sixty-five patients with IPF had double
the burden of bacteria in BAL fluid compared with 44 control subjects. Baseline
bacterial burden predicted the rate of decline in lung volume and risk of death and
associated independently with the rs35705950 polymorphism of the MUC5B mucin gene, a
proven host susceptibility factor for IPF. Sequencing yielded 912,883 high-quality
reads from all subjects. We identified Haemophilus,
Streptococcus, Neisseria, and
Veillonella spp. to be more abundant in cases than control
subjects. Regression analyses indicated that these specific operational taxonomic
units as well as bacterial burden associated independently with IPF.
Conclusions: IPF is characterized by an increased bacterial burden in
BAL that predicts decline in lung function and death. Trials of antimicrobial therapy
are needed to determine if microbial burden is pathogenic in the disease.
idiopathic pulmonary fibrosis; Muc5b; bacteria; microbiome
The replication of picornaviruses has been described to cause fragmentation of the Golgi apparatus that blocks the secretory pathway. The inhibition of major histocompatibility complex class I upregulation and cytokine, chemokine and interferon secretion may have important implications for host defense. Previous studies have shown that disruption of the secretory pathway can be replicated by expression of individual nonstructural proteins; however the situation with different serotypes of human rhinovirus (HRV) is unclear. The expression of 3A protein from HRV14 or HRV2 did not cause Golgi apparatus disruption or a block in secretion, whereas other studies showed that infection of cells with HRV1A did cause Golgi apparatus disruption which was replicated by the expression of 3A. HRV16 is the serotype most widely used in clinical HRV challenge studies; consequently, to address the issue of Golgi apparatus disruption for HRV16, we have systematically and quantitatively examined the effect of HRV16 on both Golgi apparatus fragmentation and protein secretion in HeLa cells. First, we expressed each individual nonstructural protein and examined their cellular localization and their disruption of endoplasmic reticulum and Golgi apparatus architecture. We quantified their effects on the secretory pathway by measuring secretion of the reporter protein Gaussia luciferase. Finally, we examined the same outcomes following infection of cells with live virus. We demonstrate that expression of HRV16 3A and 3AB and, to a lesser extent, 2B caused dispersal of the Golgi structure, and these three nonstructural proteins also inhibited protein secretion. The infection of cells with HRV16 also caused significant Golgi apparatus dispersal; however, this did not result in the inhibition of protein secretion.
IMPORTANCE The ability of replicating picornaviruses to influence the function of the secretory pathway has important implications for host defense. However, there appear to be differences between different members of the family and inconsistent results when comparing infection with live virus to expression of individual nonstructural proteins. We demonstrate that individual nonstructural HRV16 proteins, when expressed in HeLa cells, can both fragment the Golgi apparatus and block secretion, whereas viral infection fragments the Golgi apparatus without blocking secretion. This has major implications for how we interpret mechanistic evidence derived from the expression of single viral proteins.
Rhinoviruses are the most common cause of virally-induced asthma exacerbations which continue to account for the greatest burden in terms of morbidity, mortality and cost associated with this disease. IL-25 activates type-2-driven inflammation and is potentially important in virally-induced asthma exacerbations. Rhinovirus-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 rhinovirus infection. In mice rhinovirus 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, T and non-T type-2 cells. We have identified that asthmatic epithelial cells possess increased intrinsic capacity for expression of a pro-type-2 cytokine in response to a viral infection and identify IL-25 as a key mediator in RV-induced exacerbations of pulmonary inflammation.
Rhinoviruses are the most common virus to infect man causing a range of serious respiratory diseases including exacerbations of asthma and COPD. Type I IFN and IL-15 are thought to be required for antiviral immunity however their function during rhinovirus infection in vivo is undefined. In RV infected human volunteers, IL-15 protein expression in fluid from the nasal mucosa and in bronchial biopsies was increased. In mice, RV induced type I IFN-dependent expression of IL-15 and IL-15Rα which in turn were required for NK- and CD8+ T-cell responses. Treatment with IL-15-IL-15Rα complexes (IL-15c) boosted RV-induced expression of IL-15, IL-15Rα, IFN-γ, CXCL9 and CXCL10 followed by recruitment of activated, IFN-γ expressing NK, CD8+ and CD4+ T cells. Treating infected IFNAR1−/− mice with IL-15c similarly increased IL-15, IL-15Rα, IFN-γ and CXCL9 (but not CXCL10) expression also followed by NK-, CD8+- and CD4+-T cell recruitment and activation. We have demonstrated that type I IFN induced IFN-γ and cellular immunity to RV was mediated by IL-15 and IL-15Rα. Importantly we also show that IL-15 could be induced via a type I IFN-independent mechanism by IL-15 complex treatment which in turn was sufficient to drive IFN-γ expression and lymphocyte responses.
Ex vivo, bronchial epithelial cells from people with asthma are more
susceptible to rhinovirus infection caused by deficient induction of the antiviral
protein, IFN-β. Exogenous IFN-β restores antiviral activity.
Objectives: To compare the efficacy and safety of inhaled IFN-β
with placebo administered to people with asthma after onset of cold symptoms to
prevent or attenuate asthma symptoms caused by respiratory viruses.
Methods: A total of 147 people with asthma on inhaled corticosteroids
(British Thoracic Society Steps 2–5), with a history of virus-associated
exacerbations, were randomized to 14-day treatment with inhaled IFN-β (n =
72) or placebo (n = 75) within 24 hours of developing cold symptoms and were
assessed clinically, with relevant samples collected to assess virus infection and
Measurements and Main Results: A total of 91% of randomized patients
developed a defined cold. In this modified intention-to-treat population, asthma
symptoms did not get clinically significantly worse (mean change in six-item Asthma
Control Questionnaire <0.5) and IFN-β treatment had no significant effect
on this primary endpoint, although it enhanced morning peak expiratory flow recovery
(P = 0.033), reduced the need for additional treatment, and
boosted innate immunity as assessed by blood and sputum biomarkers. In an exploratory
analysis of the subset of more difficult-to-treat, Step 4-5 people with asthma (n
= 27 IFN-β; n = 31 placebo), Asthma Control Questionnaire-6 increased
significantly on placebo; this was prevented by IFN-β (P
Conclusions: Although the trial did not meet its primary endpoint, it
suggests that inhaled IFN-β is a potential treatment for virus-induced
deteriorations of asthma in difficult-to-treat people with asthma and supports the
need for further, adequately powered, trials in this population.
Clinical trial registered with www.clinicaltrials.gov (NCT
innate immunity; treatment; respiratory virus
Rhinoviruses (RVs) are a major cause of common colds and induce exacerbations of asthma and chronic inflammatory lung diseases.
We expressed and purified recombinant RV coat proteins VP1-4, non-structural proteins as well as N-terminal fragments of VP1 from four RV strains (RV14, 16, 89, C) covering the three known RV groups (RV-A, RV-B and RV-C) and measured specific IgG-subclass-, IgA- and IgM-responses by ELISA in subjects with different severities of asthma or without asthma before and after experimental infection with RV16.
Before infection subjects showed IgG1 > IgA > IgM > IgG3 cross-reactivity with N-terminal fragments from the representative VP1 proteins of the three RV groups. Antibody levels were higher in the asthmatic group as compared to the non-asthmatic subjects. Six weeks after infection with RV16, IgG1 antibodies showed a group-specific increase towards the N-terminal VP1 fragment, but not towards other capsid and non-structural proteins, which was highest in subjects with severe upper and lower respiratory symptoms.
Our results demonstrate that increases of antibodies towards the VP1 N-terminus are group-specific and associated with severity of respiratory symptoms and suggest that it may be possible to develop serological tests for identifying causative RV groups.
•Increases of rhinovirus-specific antibodies are surrogate markers for severity of rhinovirus-induced respiratory symptoms.•Serological tests based on recombinant rhinovirus coat protein fragments identify the culprit rhinovirus strain.•Identification of the most relevant RV strains by serology should allow the rational design of RV vaccines.
RV, Rhinovirus; COPD, Chronic obstructive pulmonary disease; ICAM-1, Intercellular adhesion molecule 1; LDL-R, Low density lipoprotein receptor; ICS, Inhaled corticosteroids; SABA, Short-acting β2 agonists; PEF, Peak expiratory flow; MALDI–TOF, Matrix-assisted laser desorption/ionization–time-of-flight mass spectrometry; ELISA, Enzyme-linked immunosorbent assay; HRP, Horseradish peroxidase; O.D, Optical density; HSA, Human serum albumin; MBP, Maltose binding protein; TCID50, Tissue culture 50% infective dose; Rhinovirus; Asthma; Recombinant rhinovirus coat protein; Antibody response; Serological test
Bacterial infection of the lower respiratory tract in chronic obstructive pulmonary disease (COPD) patients is common both in stable patients and during acute exacerbations. The most frequent bacteria detected in COPD patients is Haemophilus influenzae, and it appears this organism is uniquely adapted to exploit immune deficiencies associated with COPD and to establish persistent infection in the lower respiratory tract. The presence of bacteria in the lower respiratory tract in stable COPD is termed colonization; however, there is increasing evidence that this is not an innocuous phenomenon but is associated with airway inflammation, increased symptoms, and increased risk for exacerbations. In this review, we discuss host immunity that offers protection against H. influenzae and how disturbance of these mechanisms, combined with pathogen mechanisms of immune evasion, promote persistence of H. influenzae in the lower airways in COPD. In addition, we examine the role of H. influenzae in COPD exacerbations, as well as interactions between H. influenzae and respiratory virus infections, and review the role of treatments and their effect on COPD outcomes. This review focuses predominantly on data derived from human studies but will refer to animal studies where they contribute to understanding the disease in humans.
chronic obstructive pulmonary disease; Haemophilus influenzae; nontypeable Haemophilus influenzae; respiratory viruses; vaccination
Rationale: Rhinovirus infection is followed by significantly increased frequencies of positive, potentially pathogenic sputum cultures in chronic obstructive pulmonary disease (COPD). However, it remains unclear whether these represent de novo infections or an increased load of organisms from the complex microbial communities (microbiome) in the lower airways.
Objectives: To investigate the effect of rhinovirus infection on the airway bacterial microbiome.
Methods: Subjects with COPD (n = 14) and healthy control subjects with normal lung function (n = 17) were infected with rhinovirus. Induced sputum was collected at baseline before rhinovirus inoculation and again on Days 5, 15, and 42 after rhinovirus infection and DNA was extracted. The V3–V5 region of the bacterial 16S ribosomal RNA gene was amplified and pyrosequenced, resulting in 370,849 high-quality reads from 112 of the possible 124 time points.
Measurements and Main Results: At 15 days after rhinovirus infection, there was a sixfold increase in 16S copy number (P = 0.007) and a 16% rise in numbers of proteobacterial sequences, most notably in potentially pathogenic Haemophilus influenzae (P = 2.7 × 10-20), from a preexisting community. These changes occurred only in the sputum microbiome of subjects with COPD and were still evident 42 days after infection. This was in contrast to the temporal stability demonstrated in the microbiome of healthy smokers and nonsmokers.
Conclusions: After rhinovirus infection, there is a rise in bacterial burden and a significant outgrowth of Haemophilus influenzae from the existing microbiota of subjects with COPD. This is not observed in healthy individuals. Our findings suggest that rhinovirus infection in COPD alters the respiratory microbiome and may precipitate secondary bacterial infections.
rhinovirus; chronic obstructive pulmonary disease; bacteria; microbiome
Human embryonic stem cell-derived endothelial cells (hESC-EC), as well as other stem cell derived endothelial cells, have a range of applications in cardiovascular research and disease treatment. Endothelial cells sense Gram-negative bacteria via the pattern recognition receptors (PRR) Toll-like receptor (TLR)-4 and nucleotide-binding oligomerisation domain-containing protein (NOD)-1. These pathways are important in terms of sensing infection, but TLR4 is also associated with vascular inflammation and atherosclerosis. Here, we have compared TLR4 and NOD1 responses in hESC-EC with those of endothelial cells derived from other stem cells and with human umbilical vein endothelial cells (HUVEC). HUVEC, endothelial cells derived from blood progenitors (blood outgrowth endothelial cells; BOEC), and from induced pluripotent stem cells all displayed both a TLR4 and NOD1 response. However, hESC-EC had no TLR4 function, but did have functional NOD1 receptors. In vivo conditioning in nude rats did not confer TLR4 expression in hESC-EC. Despite having no TLR4 function, hESC-EC sensed Gram-negative bacteria, a response that was found to be mediated by NOD1 and the associated RIP2 signalling pathways. Thus, hESC-EC are TLR4 deficient but respond to bacteria via NOD1. This data suggests that hESC-EC may be protected from unwanted TLR4-mediated vascular inflammation, thus offering a potential therapeutic advantage.
Surface major histocompatibility complex class I-related chain (MIC) A and B molecules are increased by IL-15 and have a role in the activation of natural killer group 2 member D-positive natural killer and CD8 T cells. MICA and MICB also exist in soluble forms (sMICA and sMICB). Rhinoviruses (RVs) are the major cause of asthma exacerbations, and IL-15 levels are decreased in the airways of subjects with asthma. The role of MIC molecules in immune responses in the lung has not been studied. Here, we determine the relationship between MICA and MICB and RV infection in vitro in respiratory epithelial cells and in vivo in healthy subjects and subjects with asthma.
Surface MICA and MICB, as well as sMICA and sMICB, in respiratory epithelial cells were measured in vitro in response to RV infection and exposure to IL-15. Levels of sMICA and sMICB in serum, sputum, and BAL were measured and correlated with blood and bronchoalveolar immune cells in healthy subjects and subjects with asthma before and during RV infection.
RV increased MICA and MICB in vitro in epithelial cells. Exogenous IL-15 upregulated sMICB levels in RV-infected epithelial cells. Levels of sMICB molecules in serum were increased in healthy subjects compared with subjects with stable asthma. Following RV infection, airway levels of sMIC are upregulated, and there are positive correlations between sputum MICB levels and the percentage of bronchoalveolar natural killer cells in healthy subjects but not subjects with asthma.
RV infection induces MIC molecules in respiratory epithelial cells in vitro and in vivo. Induction of MICB molecules is impaired in subjects with asthma, suggesting these molecules may have a role in the antiviral immune response to RV infections.
Asthma exacerbations are frequently triggered by rhinovirus infections. Both asthma and respiratory tract infection can activate haemostasis. Therefore we hypothesized that experimental rhinovirus-16 infection and asthmatic airway inflammation act in synergy on the haemostatic balance.
28 patients (14 patients with mild allergic asthma and 14 healthy non-allergic controls) were infected with low-dose rhinovirus type 16. Venous plasma and bronchoalveolar lavage fluid (BAL fluid) were obtained before and 6 days after infection to evaluate markers of coagulation activation, thrombin-antithrombin complexes, von Willebrand factor, plasmin-antiplasmin complexes, plasminogen activator inhibitor type-1, endogenous thrombin potential and tissue factor-exposing microparticles by fibrin generation test, in plasma and/or BAL fluid. Data were analysed by nonparametric tests (Wilcoxon, Mann Whitney and Spearman correlation).
13 patients with mild asthma (6 females, 19-29 y) and 11 healthy controls (10 females, 19-31 y) had a documented Rhinovirus-16 infection. Rhinovirus-16 challenge resulted in a shortening of the fibrin generation test in BAL fluid of asthma patients (t = -1: 706 s vs. t = 6: 498 s; p = 0.02), but not of controls (t = -1: 693 s vs. t = 6: 636 s; p = 0.65). The fold change in tissue factor-exposing microparticles in BAL fluid inversely correlated with the fold changes in eosinophil cationic protein and myeloperoxidase in BAL fluid after virus infection (r = -0.517 and -0.528 resp., both p = 0.01).
Rhinovirus-16 challenge led to increased plasminogen activator inhibitor type-1 levels in plasma in patients with asthma (26.0 ng/mL vs. 11.5 ng/mL in healthy controls, p = 0.04). Rhinovirus-16 load in BAL showed a linear correlation with the fold change in endogenous thrombin potential, plasmin-antiplasmin complexes and plasminogen activator inhibitor type-1.
Experimental rhinovirus infection induces procoagulant changes in the airways of patients with asthma through increased activity of tissue factor-exposing microparticles. These microparticle-associated procoagulant changes are associated with both neutrophilic and eosinophilic inflammation. Systemic activation of haemostasis increases with Rhinoviral load.
This trial was registered at the Dutch trial registry (http://www.trialregister.nl): NTR1677.
Rhinovirus; Coagulation; Fibrinolysis; Asthma; Microparticles; Inflammation
COPD is associated with increased numbers of T cells in the lungs, particularly CD8+ T cells. The mechanisms of increased T cells are unknown but may be related to repeated virus infections in COPD patients. We analysed lymphocyte subsets in blood and bronchoalveolar lavage in smokers and COPD subjects during experimental rhinovirus infections.
Lymphocytes were isolated from blood and bronchoalveolar lavage from COPD subjects and non-obstructed smokers prior to, and following experimental rhinovirus infection. Lymphocyte surface markers and intracellular cytokines were analysed using flow cytometry.
Following rhinovirus infection CD4+ and CD8+ T cell numbers in the COPD subjects were significantly reduced in blood and CD3+ and CD8+ T cells increased in bronchoalveolar lavage compared to baseline. T cells did not increase in BAL in the control subjects. CD3+ T cells correlated with virus load.
Following rhinovirus infection T cells move from the circulation to the lung. Repeated virus infections may contribute to T cell accumulation in COPD patients.
Chronic obstructive pulmonary disease; Acute exacerbations of COPD; Respiratory viruses; T lymphocytes
Lysosomes play important roles in multiple aspects of physiology, but the problem of how the transcription of lysosomal genes is coordinated remains incompletely understood. The goal of this study was to illuminate the physiological contexts in which lysosomal genes are coordinately regulated and to identify transcription factors involved in this control.
As transcription factors and their target genes are often co-regulated, we performed meta-analyses of array-based expression data to identify regulators whose mRNA profiles are highly correlated with those of a core set of lysosomal genes. Among the ~50 transcription factors that rank highest by this measure, 65% are involved in differentiation or development, and 22% have been implicated in interferon signaling. The most strongly correlated candidate was Stat6, a factor commonly activated by interleukin-4 (IL-4) or IL-13. Publicly available chromatin immunoprecipitation (ChIP) data from alternatively activated mouse macrophages show that lysosomal genes are overrepresented among Stat6-bound targets. Quantification of RNA from wild-type and Stat6-deficient cells indicates that Stat6 promotes the expression of over 100 lysosomal genes, including hydrolases, subunits of the vacuolar H+ ATPase and trafficking factors. While IL-4 inhibits and activates different sets of lysosomal genes, Stat6 mediates only the activating effects of IL-4, by promoting increased expression and by neutralizing undefined inhibitory signals induced by IL-4.
The current data establish Stat6 as a broadly acting regulator of lysosomal gene expression in mouse macrophages. Other regulators whose expression correlates with lysosomal genes suggest that lysosome function is frequently re-programmed during differentiation, development and interferon signaling.
Severe asthma is associated with T helper (TH) 2 and 17 cell activation, airway neutrophilia and phosphoinositide-3-kinase (PI3K) activation. Asthma exacerbations are commonly caused by rhinovirus (RV) and also associated with PI3K-driven inflammation. Anthraquinone derivatives have been shown to reduce PI3K-mediated AKT phosphorylation in-vitro.
To determine the anti-inflammatory potential of anthraquinones in-vivo.
BALB/c mice were sensitized and challenged with crude house dust mite extract to induce allergic airways disease and treated with mitoxantrone and a novel non-cytotoxic anthraquinone derivative. Allergic mice were also infected with RV1B to induce an exacerbation.
Anthraquinone treatment reduced AKT phosphorylation, hypoxia-inducible factor-1α and vascular endothelial growth factor expression, and ameliorated allergen- and RV-induced airways hyprereactivity, neutrophilic and eosinophilic inflammation, cytokine/chemokine expression, mucus hypersecretion, and expression of TH2 proteins in the airways. Anthraquinones also boosted type 1 interferon responses and limited RV replication in the lung.
Non-cytotoxic anthraquinone derivatives may be of therapeutic benefit for the treatment of severe and RV-induced asthma by blocking pro-inflammatory pathways regulated by PI3K/AKT.
Human rhinovirus (RV) infections are the principle cause of common colds and precipitate asthma and COPD exacerbations. There is currently no RV vaccine, largely due to the existence of ∼150 strains. We aimed to define highly conserved areas of the RV proteome and test their usefulness as candidate antigens for a broadly cross-reactive vaccine, using a mouse infection model. Regions of the VP0 (VP4+VP2) capsid protein were identified as having high homology across RVs. Immunization with a recombinant VP0 combined with a Th1 promoting adjuvant induced systemic, antigen specific, cross-serotype, cellular and humoral immune responses. Similar cross-reactive responses were observed in the lungs of immunized mice after infection with heterologous RV strains. Immunization enhanced the generation of heterosubtypic neutralizing antibodies and lung memory T cells, and caused more rapid virus clearance. Conserved domains of the RV capsid therefore induce cross-reactive immune responses and represent candidates for a subunit RV vaccine.
Human rhinovirus infections cause the majority of common colds as well as asthma and chronic obstructive pulmonary disease (COPD) exacerbations. The disease burden attributable to rhinoviruses is therefore huge. Despite this and the fact that human rhinoviruses were discovered over 50 years ago, there are currently no specific antiviral therapies or vaccine available. The lack of a rhinovirus vaccine can at least in part be attributed to the fact that rhinoviruses like other pathogens have high variability in surface antibody binding regions, resulting in >100 serotypically distinct strains. We have defined areas of the rhinovirus polyprotein which are highly conserved across strains and which may therefore induce cross-reactive immune responses capable of providing broader protection. Using a mouse model, we show that immunization with a recombinant rhinovirus capsid protein induces cross-reactive cellular and humoral immune responses. After subsequent infection, immunization enhances both neutralising antibody and lung effector and memory T cell responses, expediting virus clearance. Importantly these effects were evident upon challenge with multiple heterologous rhinovirus serotypes, indicating that immunization with conserved rhinovirus capsid proteins may represent a viable strategy for producing a broadly cross-reactive vaccine.
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.
Viruses exploit receptors on the host cell to cause infection. Therapies aimed at blocking virus-receptor interactions have the potential to prevent viral disease. Cellular receptors are also important for normal host cell function. Therefore, new therapies targeting these receptors to block viral infection may also inadvertently alter the physiology of the host cell. Viral pathogens, such as the cold virus (rhinovirus), are believed to be the major cause of asthma attacks and exacerbations in chronic obstructive pulmonary disease (COPD). In this study, we show that it is possible to identify novel therapeutic antibodies that block infection with rhinovirus without impairing the receptors' main function of cell adhesion. We then use animal models that show that an antibody can inhibit virus-induced lung inflammation and disease. Moreover, we show that this antibody can also inhibit a virally induced asthma exacerbation. This work is relevant in that it shows that antibodies can be tailored to distinct regions of viral receptors to block infection without inhibiting the receptors' normal cellular function. This is important for the development of new treatments that will prevent diseases caused by infection with rhinovirus, such as exacerbations of asthma and COPD.
COPD exacerbations are associated with neutrophilic airway inflammation. Adhesion molecules on the surface of neutrophils may play a key role in their movement from blood to the airways. We analysed adhesion molecule expression on blood and sputum neutrophils from COPD subjects and non-obstructed smokers during experimental rhinovirus infections.
Blood and sputum were collected from 9 COPD subjects and 10 smoking and age-matched control subjects at baseline, and neutrophil expression of the adhesion molecules and activation markers measured using flow cytometry. The markers examined were CD62L and CD162 (mediating initial steps of neutrophil rolling and capture), CD11a and CD11b (required for firm neutrophil adhesion), CD31 and CD54 (involved in neutrophil transmigration through the endothelial monolayer) and CD63 and CD66b (neutrophil activation markers). Subjects were then experimentally infected with rhinovirus-16 and repeat samples collected for neutrophil analysis at post-infection time points.
At baseline there were no differences in adhesion molecule expression between the COPD and non-COPD subjects. Expression of CD11a, CD31, CD62L and CD162 was reduced on sputum neutrophils compared to blood neutrophils. Following rhinovirus infection expression of CD11a expression on blood neutrophils was significantly reduced in both subject groups. CD11b, CD62L and CD162 expression was significantly reduced only in the COPD subjects. Blood neutrophil CD11b expression correlated inversely with inflammatory markers and symptom scores in COPD subjects.
Following rhinovirus infection neutrophils with higher surface expression of adhesion molecules are likely preferentially recruited to the lungs. CD11b may be a key molecule involved in neutrophil trafficking in COPD exacerbations.
Chronic obstructive pulmonary disease; Exacerbations; Respiratory viruses; Neutrophils
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.
Rationale: Exacerbations of chronic obstructive pulmonary disease (COPD) and responses to treatment are heterogeneous.
Objectives: Investigate the usefulness of blood eosinophils to direct corticosteroid therapy during exacerbations.
Methods: Subjects with COPD exacerbations were entered into a randomized biomarker-directed double-blind corticosteroid versus standard therapy study. Subjects in the standard arm received prednisolone for 2 weeks, whereas in the biomarker-directed arm, prednisolone or matching placebo was given according to the blood eosinophil count biomarker. Both study groups received antibiotics. Blood eosinophils were measured in the biomarker-directed and standard therapy arms to define biomarker-positive and -negative exacerbations (blood eosinophil count > and ≤ 2%, respectively). The primary outcome was to determine noninferiority in health status using the chronic respiratory questionnaire (CRQ) and in the proportion of exacerbations associated with a treatment failure between subjects allocated to the biomarker-directed and standard therapy arms.
Measurements and Main Results: There were 86 and 80 exacerbations in the biomarker-directed and standard treatment groups, respectively. In the biomarker-directed group, 49% of the exacerbations were not treated with prednisolone. CRQ improvement after treatment in the standard and biomarker-directed therapy groups was similar (0.8 vs. 1.1; mean difference, 0.3; 95% confidence interval, 0.0–0.6; P = 0.05). There was a greater improvement in CRQ in biomarker-negative exacerbations given placebo compared with those given prednisolone (mean difference, 0.45; 95% confidence interval, 0.01–0.90; P = 0.04). In biomarker-negative exacerbations, treatment failures occurred in 15% given prednisolone and 2% of those given placebo (P = 0.04).
Conclusions: The peripheral blood eosinophil count is a promising biomarker to direct corticosteroid therapy during COPD exacerbations, but larger studies are required.
Clinical trial registered with www.controlled-trials.com (ISRCTN92422949).
chronic obstructive pulmonary disease; exacerbations; prednisolone; infection; eosinophils