Rhinovirus replication causes RANTES production in primary bronchial epithelial cells

Antiviral roles of eosinophils in asthma and respiratory viral infection

Eosinophils are immune cells that are crucial for the pathogenesis of allergic diseases, such as asthma. These cells play multifunctional roles in various situations, including infection. They are activated during viral infections and exert antiviral activity. Pattern recognition receptors, toll-like receptor 7 and retinoic acid inducible gene-I, are important for the recognition and capture of RNA viruses. In addition, intracellular granule proteins (eosinophil cationic protein and eosinophil-derived neurotoxin) and intracellular nitric oxide production inactivate and/or degrade RNA viruses. Interestingly, eosinophil-synthesizing specialized pro-resolving mediators possess antiviral properties that inhibit viral replication. Thus, eosinophils may play a protective role during respiratory virus infections. Notably, antiviral activities are impaired in patients with asthma, and eosinophil activities are perturbed in proportion with the severity of asthma. The exact roles of eosinophils in RNA virus (rhinovirus, respiratory syncytial virus, and influenza virus)-induced type 2 inflammation-based asthma exacerbation remain unclear. Our research demonstrates that interferons (IFN-α and IFN-γ) stimulate human eosinophils to upregulate antiviral molecules, including guanylate-binding proteins and tripartite motifs. Furthermore, IFN-γ specifically increases the expression of IL5RA, ICAM-1, and FCGR1A, potentially enhancing cellular responsiveness to IL-5, ICAM-1-mediated adhesion to rhinoviruses, and IgG-induced inflammatory responses, respectively. In this review, we have summarized the relationship between viral infections and asthma and the mechanisms underlying the development of antiviral functions of human and mouse eosinophils in vivo and in vitro.

Cilomilast Modulates Rhinovirus-Induced Airway Epithelial ICAM-1 Expression and IL-6, CXCL8 and CCL5 Production

Background: Cilomilast, a phosphodiesterase-4 (PDE4) selective inhibitor, has anti-inflammatory effects in vitro and in vivo and reduces COPD exacerbations. We tested the hypothesis that cilomilast inhibits virus-induced airway epithelial intercellular adhesion molecule-1 (ICAM-1) expression and inflammatory cytokine/chemoattractants, IL-6, CXCL8, and CCL5 production in vitro. Methods: BEAS-2B bronchial epithelial cells were incubated with 0.5-2 MOI (multiplicity of infection-infectious units/cell) of rhinovirus 16 (RV16). Then, 0.1-10 μM cilomilast or 10 nM dexamethasone, as inhibition control, were added pre- or post-1 h RV16 infection. Supernatant and cells were sampled at 8, 24, 48, and 72 h after infection. Cell surface ICAM-1 expression was detected by immunogold labelling and visualised by high-resolution scanning electron microscopy (HR-SEM), while IL-6, CXCL8, and CCL5 protein release and mRNA expression were measured using an ELISA and RT-PCR. Results: Cilomilast significantly decreased RV16-induced ICAM-1 expression to approximately 45% (p < 0.01). CXCL8 protein/mRNA production was reduced by about 41% (p < 0.05), whereas IL-6 protein/mRNA production was increased to between 41-81% (p < 0.001). There was a trend to reduction by cilomilast of RV16-induced CCL5. Conclusions: Cilomilast has differential effects on RV16-induced ICAM-1 and interleukins, inhibiting virus-induced ICAM-1 expression and CXCL8 while increasing IL-6 production. These in vitro effects may help to explain the beneficial actions of this PDE4 inhibitor in vivo.

Lactobacillus rhamnosus dampens cytokine and chemokine secretion from primary human nasal epithelial cells infected with rhinovirus

AIMS

To investigate the effect of Lactobacillus rhamnosus on viral replication and cellular response to human rhinovirus (HRV) infection, including the secretion of antiviral and inflammatory mediators from well-differentiated nasal epithelial cells (WD-NECs).

METHODS AND RESULTS

The WD-NECs from healthy adult donors (N = 6) were cultured in vitro, exposed to different strains of L. rhamnosus (D3189, D3160, or LB21), and infected with HRV (RV-A16) after 24 h. Survival and adherence capacity of L. rhamnosus in a NEC environment were confirmed using CFSE-labelled isolates, immunofluorescent staining, and confocal microscopy. Shed virus and viral replication were quantified using TCID50 assays and RT-qPCR, respectively. Cytotoxicity was measured by lactate dehydrogenase (LDH) activity. Pro-inflammatory mediators were measured by multiplex immunoassay, and interferon (IFN)-λ1/3 was measured using a standard ELISA kit. Lactobacillus rhamnosus was able to adhere to and colonize WD-NECs prior to the RV-A16 infection. Lactobacillus rhamnosus did not affect shed RV-A16, viral replication, RV-A16-induced IFN-λ1/3 production, or LDH release. Pre-exposure to L. rhamnosus, particularly D3189, reduced the secretion of RV-A16-induced pro-inflammatory mediators by WD-NECs.

CONCLUSIONS

These findings demonstrate that L. rhamnosus differentially modulates RV-A16-induced innate inflammatory immune responses in primary NECs from healthy adults.

Viral Infection and Airway Epithelial Immunity in Asthma

Viral respiratory tract infections are associated with asthma development and exacerbation in children and adults. In the course of immune responses to viruses, airway epithelial cells are the initial platform of innate immunity against viral invasion. Patients with severe asthma are more vulnerable than those with mild to moderate asthma to viral infections. Furthermore, in most cases, asthmatic patients tend to produce lower levels of antiviral cytokines than healthy subjects, such as interferons produced from immune effector cells and airway epithelial cells. The epithelial inflammasome appears to contribute to asthma exacerbation through overactivation, leading to self-damage, despite its naturally protective role against infectious pathogens. Given the mixed and complex immune responses in viral-infection-induced asthma exacerbation, this review examines the diverse roles of airway epithelial immunity and related potential therapeutic targets and discusses the mechanisms underlying the heterogeneous manifestations of asthma exacerbations.

Targeting intercellular adhesion molecule-1 (ICAM-1) to reduce rhinovirus-induced acute exacerbations in chronic respiratory diseases

The chronic respiratory non-communicable diseases, asthma and chronic obstructive pulmonary disease (COPD) are among the leading causes of global mortality and morbidity. Individuals suffering from these diseases are particularly susceptible to respiratory infections caused by bacterial and/or viral pathogens, which frequently result in exacerbation of symptoms, lung function decline, frequent hospital emergency visits and increased socioeconomic burden. Human rhinoviruses (HRV) remain the major viral pathogen group implicated in exacerbations of both asthma and COPD. The rhinoviral entry into the host lung epithelium is facilitated primarily by the adhesion site (“receptor”) intercellular adhesion molecule-1 (ICAM-1), coincidentally expressed on the respiratory epithelium in these conditions. Multiple observations of increased airway ICAM-1 protein in asthmatics, smokers and smoking-related COPD have been recorded in the literature. However, the lack of robust therapies for COPD in particular has triggered a renewed interest in assessing receptor antagonism-based anti-viral strategies for treatment of intercurrent viral infections in those with pre-existing chronic lung diseases. Given the crucial role ICAM-1 plays in facilitating HRV adhesion and, thus, transmissibility to the host respiratory system, as well as the up-regulation of ICAM-1 by smoking, we summarize the role of HRV in smoking-induced COPD and especially highlight the role of ICAM-1 in epithelial viral adhesion and chronic lung disease progression. Further, the review also sheds light specifically on evolving precision therapeutic strategies in blocking ICAM-1 for preventing viral adhesion and exacerbations of COPD.

Viral Induced Effects on a Vulnerable Epithelium; Lessons Learned From Paediatric Asthma and Eosinophilic Oesophagitis

The epithelium is integral to the protection of many different biological systems and for the maintenance of biochemical homeostasis. Emerging evidence suggests that particular children have epithelial vulnerabilities leading to dysregulated barrier function and integrity, that resultantly contributes to disease pathogenesis. These epithelial vulnerabilities likely develop in utero or in early life due to various genetic, epigenetic and environmental factors. Although various epithelia are uniquely structured with specific function, prevalent allergic-type epithelial diseases in children potentially have common or parallel disease processes. These include inflammation and immune response dysregulation stemming from atypical epithelial barrier function and integrity. Two diseases where aetiology and pathogenesis are potentially linked to epithelial vulnerabilities include Paediatric Asthma and Eosinophilic Oesophagitis (EoE). For example, rhinovirus C (RV-C) is a known risk factor for paediatric asthma development and is known to disrupt respiratory epithelial barrier function causing acute inflammation. In addition, EoE, a prevalent atopic condition of the oesophageal epithelium, is characterised by similar innate immune and epithelial responses to viral injury. This review examines the current literature and identifies the gaps in the field defining viral-induced effects on a vulnerable respiratory epithelium and resulting chronic inflammation, drawing from knowledge generated in acute wheezing illness, paediatric asthma and EoE. Besides highlighting the importance of epithelial structure and barrier function in allergic disease pathogenesis regardless of specific epithelial sub-types, this review focuses on the importance of examining other parallel allergic-type disease processes that may uncover commonalities driving disease pathogenesis. This in turn may be beneficial in the development of common therapeutics for current clinical management and disease prevention in the future.

In Vitro Modelling of Respiratory Virus Infections in Human Airway Epithelial Cells - A Systematic Review

Respiratory tract infections (RTI) are a major cause of morbidity and mortality in humans. A large number of RTIs is caused by viruses, often resulting in more severe disease in infants, elderly and the immunocompromised. Upon viral infection, most individuals experience common cold-like symptoms associated with an upper RTI. However, in some cases a severe and sometimes life-threatening lower RTI may develop. Reproducible and scalable in vitro culture models that accurately reflect the human respiratory tract are needed to study interactions between respiratory viruses and the host, and to test novel therapeutic interventions. Multiple in vitro respiratory cell culture systems have been described, but the majority of these are based on immortalized cell lines. Although useful for studying certain aspects of viral infections, such monomorphic, unicellular systems fall short in creating an understanding of the processes that occur at an integrated tissue level. Novel in vitro models involving primary human airway epithelial cells and, more recently, human airway organoids, are now in use. In this review, we describe the evolution of in vitro cell culture systems and their characteristics in the context of viral RTIs, starting from advances after immortalized cell cultures to more recently developed organoid systems. Furthermore, we describe how these models are used in studying virus-host interactions, e.g. tropism and receptor studies as well as interactions with the innate immune system. Finally, we provide an outlook for future developments in this field, including co-factors that mimic the microenvironment in the respiratory tract.

CCR5 inhibition in critical COVID-19 patients decreases inflammatory cytokines, increases CD8 T-cells, and decreases SARS-CoV2 RNA in plasma by day 14

OBJECTIVE

Infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is now a global pandemic. Emerging results indicate a dysregulated immune response. Given the role of CCR5 in immune cell migration and inflammation, we investigated the impact of CCR5 blockade via the CCR5-specific antibody leronlimab on clinical, immunological, and virological parameters in severe COVID-19 patients.

METHODS

In March 2020, 10 terminally ill, critical COVID-19 patients received two doses of leronlimab via individual emergency use indication. We analyzed changes in clinical presentation, immune cell populations, inflammation, as well as SARS-CoV-2 plasma viremia before and 14 days after treatment.

RESULTS

Over the 14-day study period, six patients survived, two were extubated, and one discharged. We observed complete CCR5 receptor occupancy in all donors by day 7. Compared with the baseline, we observed a concomitant statistically significant reduction in plasma IL-6, restoration of the CD4/CD8 ratio, and resolution of SARS-CoV2 plasma viremia (pVL). Furthermore, the increase in the CD8 percentage was inversely correlated with the reduction in pVL (r = -0.77, p = 0.0013).

CONCLUSIONS

Our study design precludes clinical efficacy inferences but the results implicate CCR5 as a therapeutic target for COVID-19 and they form the basis for ongoing randomized clinical trials.

A Microengineered Airway Lung Chip Models Key Features of Viral-induced Exacerbation of Asthma

Viral-induced exacerbation of asthma remains a major cause of hospitalization and mortality. New human-relevant models of the airways are urgently needed to understand how respiratory infections may trigger asthma attacks and to advance treatment development. Here, we describe a new human-relevant model of rhinovirus-induced asthma exacerbation that recapitulates viral infection of asthmatic airway epithelium and neutrophil transepithelial migration, and enables evaluation of immunomodulatory therapy. Specifically, a microengineered model of fully differentiated human mucociliary airway epithelium was stimulated with IL-13 to induce a T-helper cell type 2 asthmatic phenotype and infected with live human rhinovirus 16 (HRV16) to reproduce key features of viral-induced asthma exacerbation. We observed that the infection with HRV16 replicated key hallmarks of the cytopathology and inflammatory responses observed in human airways. Generation of a T-helper cell type 2 microenvironment through exogenous IL-13 stimulation induced features of asthmatic airways, including goblet cell hyperplasia, reduction of cilia beating frequency, and endothelial activation, but did not alter rhinovirus infectivity or replication. High-resolution kinetic analysis of secreted inflammatory markers revealed that IL-13 treatment altered IL-6, IFN-λ1, and CXCL10 secretion in response to HRV16. Neutrophil transepithelial migration was greatest when viral infection was combined with IL-13 treatment, whereas treatment with MK-7123, a CXCR2 antagonist, reduced neutrophil diapedesis in all conditions. In conclusion, our microengineered Airway Lung-Chip provides a novel human-relevant platform for exploring the complex mechanisms underlying viral-induced asthma exacerbation. Our data suggest that IL-13 may impair the hosts' ability to mount an appropriate and coordinated immune response to rhinovirus infection. We also show that the Airway Lung-Chip can be used to assess the efficacy of modulators of the immune response.

Rhinovirus-Induced Modulation of Epithelial Phenotype: Role in Asthma

Human rhinoviruses have been linked both to the susceptibility of asthma development and to the triggering of acute exacerbations. Given that the human airway epithelial cell is the primary site of human rhinovirus (HRV) infection and replication, the current review focuses on how HRV-induced modulation of several aspects of epithelial cell phenotype could contribute to the development of asthma or to the induction of exacerbations. Modification of epithelial proinflammatory and antiviral responses are considered, as are alterations in an epithelial barrier function and cell phenotype. The contributions of the epithelium to airway remodeling and to the potential modulation of immune responses are also considered. The potential interactions of each type of HRV-induced epithelial phenotypic changes with allergic sensitization and allergic phenotype are also considered in the context of asthma development and of acute exacerbations.

Orosomucoid-like 3 Supports Rhinovirus Replication in Human Epithelial Cells

Polymorphism at the 17q21 gene locus and wheezing responses to rhinovirus (RV) early in childhood conspire to increase the risk of developing asthma. However, the mechanisms mediating this gene-environment interaction remain unclear. In this study, we investigated the impact of one of the 17q21-encoded genes, ORMDL3 (orosomucoid-like 3), on RV replication in human epithelial cells. ORMDL3 knockdown inhibited RV-A16 replication in HeLa, BEAS-2B, A549, and NCI-H358 epithelial cell lines and primary nasal and bronchial epithelial cells. Inhibition varied by RV species, as both minor and major group RV-A subtypes RV-B52 and RV-C2 were inhibited but not RV-C15 or RV-C41. ORMDL3 siRNA did not affect expression of the major group RV-A receptor ICAM-1 or initial internalization of RV-A16. The two major outcomes of ORMDL3 activity, SPT (serine palmitoyl-CoA transferase) inhibition and endoplasmic reticulum (ER) stress induction, were further examined: silencing ORMDL3 decreased RV-induced ER stress and IFN-β mRNA expression. However, pharmacologic induction of ER stress and concomitant increased IFN-β inhibited RV-A16 replication. Conversely, blockade of ER stress with tauroursodeoxycholic acid augmented replication, pointing to an alternative mechanism for the effect of ORMDL3 knockdown on RV replication. In comparison, the SPT inhibitor myriocin increased RV-A16 but not RV-C15 replication and negated the inhibitory effect of ORMDL3 knockdown. Furthermore, lipidomics analysis revealed opposing regulation of specific sphingolipid species (downstream of SPT) by myriocin and ORMDL3 siRNA, correlating with the effect of these treatments on RV replication. Together, these data revealed a requirement for ORMDL3 in supporting RV replication in epithelial cells via SPT inhibition.

More Than Just a Barrier: The Immune Functions of the Airway Epithelium in Asthma Pathogenesis

Allergic bronchial asthma is a chronic disease of the airways that is characterized by symptoms like respiratory distress, chest tightness, wheezing, productive cough, and acute episodes of broncho-obstruction. This symptom-complex arises on the basis of chronic allergic inflammation of the airway wall. Consequently, the airway epithelium is central to the pathogenesis of this disease, because its multiple abilities directly have an impact on the inflammatory response and thus the formation of the disease. In turn, its structure and functions are markedly impaired by the inflammation. Hence, the airway epithelium represents a sealed, self-cleaning barrier, that prohibits penetration of inhaled allergens, pathogens, and other noxious agents into the body. This barrier is covered with mucus that further contains antimicrobial peptides and antibodies that are either produced or specifically transported by the airway epithelium in order to trap these particles and to remove them from the body by a process called mucociliary clearance. Once this first line of defense of the lung is overcome, airway epithelial cells are the first cells to get in contact with pathogens, to be damaged or infected. Therefore, these cells release a plethora of chemokines and cytokines that not only induce an acute inflammatory reaction but also have an impact on the alignment of the following immune reaction. In case of asthma, all these functions are impaired by the already existing allergic immune response that per se weakens the barrier integrity and self-cleaning abilities of the airway epithelium making it more vulnerable to penetration of allergens as well as of infection by bacteria and viruses. Recent studies indicate that the history of allergy- and pathogen-derived insults can leave some kind of memory in these cells that can be described as imprinting or trained immunity. Thus, the airway epithelium is in the center of processes that lead to formation, progression and acute exacerbation of asthma.

Asthmatic Bronchial Smooth Muscle Increases CCL5-Dependent Monocyte Migration in Response to Rhinovirus-Infected Epithelium

Asthma exacerbations, a major concern in therapeutic strategies, are most commonly triggered by viral respiratory infections, particularly with human rhinovirus (HRV). Infection of bronchial epithelial (BE) cells by HRV triggers inflammation, notably monocyte recruitment. The increase of bronchial smooth muscle (BSM) mass in asthma, a hallmark of bronchial remodeling, is associated with the annual rate of exacerbations. The aim of the present study was to assess whether or not BSM could increase monocyte migration induced by HRV-infected BE. We used an advanced in vitro model of co-culture of human BE cells in air-liquid interface with human BSM cells from control and asthmatic patients. Inflammation triggered by HRV infection (HRV-16, MOI 0.1, 1 h) was assessed at 24 h with transcriptomic analysis and multiplex ELISA. In vitro CD14⁺ monocyte migration was evaluated with modified Boyden chamber. Results showed that HRV-induced monocyte migration was substantially increased in the co-culture model with asthmatic BSM, compared with control BSM. Furthermore, the well-known monocyte migration chemokine, CCL2, was not involved in this increased migration. However, we demonstrated that CCL5 was further increased in the asthmatic BSM co-culture and that anti-CCL5 blocking antibody significantly decreased monocyte migration induced by HRV-infected BE. Taken together, our findings highlight a new role of BSM cells in HRV-induced inflammation and provide new insights in mucosal immunology which may open new opportunities for prevention and/or treatment of asthma exacerbation.

Identification of a Novel Inhibitor of Human Rhinovirus Replication and Inflammation in Airway Epithelial Cells

Human rhinovirus (RV), the major cause of the common cold, triggers the majority of acute airway exacerbations in patients with asthma and chronic obstructive pulmonary disease. Nitric oxide, and the related metabolite S-nitrosoglutathione, are produced in the airway epithelium via nitric oxide synthase (NOS) 2 and have been shown to function in host defense against RV infection. We hypothesized that inhibitors of the S-nitrosoglutathione-metabolizing enzyme, S-nitrosoglutathione reductase (GSNOR), might potentiate the antiviral properties of airway-derived NOS2. Using in vitro models of RV-A serotype 16 (RV-A16) and mNeonGreen-H1N1pr8 infection of human airway epithelial cells, we found that treatment with a previously characterized GSNOR inhibitor (4-[[2-[[(3-cyanophenyl)methyl]thio]-4-oxothieno-[3,2-d]pyrimidin-3(4H)-yl]methyl]-benzoic acid; referred to as C3m) decreased RV-A16 replication and expression of downstream proinflammatory and antiviral mediators (e.g., RANTES [regulated upon activation, normal T cell expressed and secreted], CXCL10, and Mx1), and increased Nrf2 (nuclear factor erythroid 2-related factor 2)-dependent genes (e.g., SQSTM1 and TrxR1). In contrast, C3m had no effect on influenza virus H1N1pr8 replication. Moreover, a structurally dissimilar GSNOR inhibitor (N6022) did not alter RV replication, suggesting that the properties of C3m may be specific to rhinovirus owing to an off-target effect. Consistent with this, C3m antiviral effects were not blocked by either NOS inhibition or GSNOR knockdown but appeared to be mediated by reduced intercellular adhesion molecule 1 transcription and increased shedding of soluble intercellular adhesion molecule 1 protein. Collectively these data show that C3m has novel antirhinoviral properties that may synergize with, but are unrelated to, its GSNOR inhibitor activity.

Airway Epithelial Derived Cytokines and Chemokines and Their Role in the Immune Response to Respiratory Syncytial Virus Infection

The airway epithelium is the primary target of respiratory syncytial virus infection. It is an important component of the antiviral immune response. It contributes to the recruitment and activation of innate immune cells from the periphery through the secretion of cytokines and chemokines. This paper provides a broad review of the cytokines and chemokines secreted from human airway epithelial cell models during respiratory syncytial virus (RSV) infection based on a comprehensive literature review. Epithelium-derived chemokines constitute most inflammatory mediators secreted from the epithelium during RSV infection. This suggests chemo-attraction of peripheral immune cells, such as monocytes, neutrophils, eosinophils, and natural killer cells as a key function of the epithelium. The reports of epithelium-derived cytokines are limited. Recent research has started to identify novel cytokines, the functions of which remain largely unknown in the wider context of the RSV immune response. It is argued that the correct choice of in vitro models used for investigations of epithelial immune functions during RSV infection could facilitate greater progress in this field.

Rhinovirus replication and innate immunity in highly differentiated human airway epithelial cells

Background

Human rhinovirus (HRV) infections are the primary cause of the common cold and are a major trigger for exacerbations of lower airway diseases, such as asthma and chronic obstructive pulmonary diseases. Although human bronchial epithelial cells (HBE) are the natural host for HRV infections, much of our understanding of how HRV replicates and induces host antiviral responses is based on studies using non-airway cell lines (e.g. HeLa cells). The current study examines the replication cycle of HRV, and host cell responses, in highly differentiated cultures of HBE.

Methods

Highly differentiated cultures of HBE were exposed to initial infectious doses ranging from 10⁴ to 10¹ 50% tissue culture-infective dose (TCID₅₀) of purified HRV-16, and responses were monitored up to 144 h after infection. Viral genomic RNA and negative strand RNA template levels were monitored, along with levels of type I and II interferons and selected antivirals.

Results

Regardless of initial infectious dose, relatively constant levels of both genomic and negative strand RNA are generated during replication, with negative strand copy numbers being10,000-fold lower than those of genomic strands. Infections were limited to a small percentage of ciliated cells and did not result in any overt signs of epithelial death. Importantly, regardless of infectious dose, HRV-16 infections were cleared by HBE in the absence of immune cells. Levels of type I and type III interferons (IFNs) varied with initial infectious dose, implying that factors other than levels of double-stranded RNA regulate IFN induction, but the time-course of HRV-16 clearance HBE was the same regardless of levels of IFNs produced. Patterns of antiviral viperin and ISG15 expression suggest they may be generated in an IFN-independent manner during HRV-16 infections.

Conclusions

These data challenge a number of aspects of dogma generated from studies in HeLa cells and emphasize the importance of appropriate cell context when studying HRV infections.

HRV16 Impairs Macrophages Cytokine Response to a Secondary Bacterial Trigger

Human rhinovirus is frequently seen as an upper respiratory tract infection but growing evidence proves the virus can cause lower respiratory tract infections in patients with chronic inflammatory lung diseases including chronic obstructive pulmonary disease (COPD). In addition to airway epithelial cells, macrophages are crucial for regulating inflammatory responses to viral infections. However, the response of macrophages to HRV has not been analyzed in detail. We used in vitro monocyte-derived human macrophages to study the cytokine secretion of macrophages in response to the virus. Our results showed that macrophages were competent at responding to HRV, as a robust cytokine response was detected. However, after subsequent exposure to non-typeable Haemophilus influenzae (NTHi) or to LPS, HRV-treated macrophages secreted reduced levels of pro-inflammatory or regulatory cytokines. This “paralyzed” phenotype was not mimicked if the macrophages were pre-treated with LPS or CpG instead of the virus. These results begin to deepen our understanding into why patients with COPD show HRV-induced exacerbations and why they mount a defective response toward NTHi.

Adrenergic Signaling at the Interface of Allergic Asthma and Viral Infections

Upper respiratory viral infections are a major etiologic instigator of allergic asthma, and they drive severe exacerbations of allergic inflammation in the lower airways of asthma sufferers. Rhinovirus (RV), in particular, is the main viral instigator of these pathologies. Asthma exacerbations due to RV infections are the most frequent reasons for hospitalization and account for the majority of morbidity and mortality in asthma patients. In both critical care and disease control, long- and short-acting β2-agonists are the first line of therapeutic intervention, which are used to restore airway function by promoting smooth muscle cell relaxation in bronchioles. While prophylactic use of β2-agonists reduces the frequency and pathology of exacerbations, their role in modulating the inflammatory response is only now being appreciated. Adrenergic signaling is a component of the sympathetic nervous system, and the natural ligands, epinephrine and norepinephrine (NE), regulate a multitude of autonomic functions including regulation of both the innate and adaptive immune response. NE is the primary neurotransmitter released by post-ganglionic sympathetic neurons that innervate most all peripheral tissues including lung and secondary lymphoid organs. Thus, the adrenergic signaling pathways are in direct contact with both the central and peripheral immune compartments. We present a perspective on how the adrenergic signaling pathway controls immune function and how β2-agonists may influence inflammation in the context of virus-induced asthma exacerbations.

Randomised controlled trial of rhinothermy for treatment of the common cold: a feasibility study

OBJECTIVE

To determine the feasibility of a randomised controlled trial (RCT) of rhinothermy for the common cold.

DESIGN

Open label, randomised, controlled feasibility study.

SETTING

Single-centre research institute in New Zealand recruiting participants from the community.

PARTICIPANTS

30 adult participants with symptoms of a common cold, presenting within 48 hours of the onset of symptoms.

INTERVENTIONS

Participants were randomly assigned 2:1 to receive either 35 L/min of 100% humidified air at 41°C via high flow nasal cannulae, 2 hours per day for up to 5 days (rhinothermy), or vitamin C 250 mg daily for 5 days (control).

PRIMARY AND SECONDARY OUTCOME MEASURES

The primary outcome was the proportion of screened candidates who were randomised. Secondary outcomes included: proportion of randomised participants who completed the study; modified Jackson scores from randomisation to 10 days after initiation of randomised regimen; time until feeling 'a lot better' compared with study entry; time until resolution of symptoms or symptom score at 10 days postrandomisation; proportion of organisms identified by PCR analysis of nasal swabs taken at baseline; the patterns of use of the rhinothermy device; estimated adherence of the control group; and rhinothermy device tolerability.

RESULTS

In all 30/79 (38%, 95% CI 27% to 50%) of potential participants screened for eligibility were randomised. Rhinothermy was well tolerated, and all randomised participants completed the study (100%, 95% CI 88% to 100%). The reduction from baseline in the modified Jackson score was greater with rhinothermy compared with control at days 2, 3, 4, 5 and 6, with the maximum difference at day 4 (-6.4, 95% CI -9.4 to -3.3). The substantial clinical benefit threshold for modified Jackson score was a 5-unit change.

CONCLUSIONS

This study shows that an RCT of rhinothermy compared with low-dose vitamin C in the treatment of the common cold is feasible.

TRIAL REGISTRATION NUMBER

ACTRN12616000470493; Results.

Validation of the Nasal Mucus Index, a novel measurement of acute respiratory infection severity

BACKGROUND

To assess the concurrent and predictive validity of the Nasal Mucus Index (NMI), a novel measurement of acute respiratory infection (ARI) severity.

OBJECTIVE

ARI, including the common cold and influenza, imposes a great burden on individuals and society. Previous research has attempted to assess the severity of ARI with self-reported and laboratory-based measurements. Self-reported measurements may introduce bias. Laboratory-based metrics are often expensive. Therefore, there is a need for non-self-reported, affordable, and validated ARI severity tests.

METHODS

Participants (N = 719) with an ARI episode underwent nasal lavage on days 1 and 3. The samples were visually assessed for the amount of mucus present in the sample and were given a subsequent NMI score. Collected samples were further assessed for interleukin (IL) 8 values (in pg/mL) and polymorphonuclear neutrophils (PMN) per high-power field. The participants rated episode severity and nasal symptoms daily by using the validated Wisconsin Upper Respiratory Symptom Survey-21 (WURSS-21). A subset of nasal symptoms was used as an additional comparator. NMI scores were compared with same-day IL-8 level, PMN count, and WURSS-21 scores for concurrent validation purposes by using the Spearman ρ as the index of correlation. NMI scores were correlated with overall episode severity measurements to assess predictive validity. Overall episode severity was measured as the WURSS-21 area under the curve, nasal symptoms area under the curve, and episode duration.

RESULTS

The NMI score correlated significantly with the same-day IL-8 level (ρ = 0.443, p < 0.001), PMN count (ρ = 0.498, p < 0.001), WURSS-21 score (ρ = 0.098, p = 0.004), and nasal symptom score (ρ = 0.162, p < 0.001). No significant predictive correlations were found.

CONCLUSION

Associations with inflammatory biomarkers and self-reported severity measurements provided evidence of concurrent validity for the novel NMI score. The NMI can be used in future research as a simple, inexpensive, non-self-reported indicator of ARI severity.

Mutations in VP1 and 3A proteins improve binding and replication of rhinovirus C15 in HeLa-E8 cells

Viruses in the rhinovirus C species (RV-C) can cause severe respiratory illnesses in children including pneumonia and asthma exacerbations. A transduced cell line (HeLa-E8) stably expressing the CDHR3-Y529 receptor variant, supports propagation of RV-C after infection. C15 clinical or recombinant isolates replicate in HeLa-E8, however progeny yields are lower than those of related strains of RV-A and RV-B. Serial passaging of C15 in HeLa-E8 resulted in stronger cytopathic effects and increased (≥10-fold) virus binding to cells and progeny yields. The adaptation was acquired by two mutations which increased binding (VP1 T125K) and replication (3A E41K), respectively. A similar 3A mutation engineered into C2 and C41 cDNAs also improved viral replication (2-8 fold) in HeLa but the heparan sulfate mediated cell-binding enhancement by the VP1 change was C15-specific. The findings now enable large-scale cost-effective C15 production by infection and the testing of RV-C infectivity by plaque assay.

Effect of human rhinovirus infection on airway epithelium tight junction protein disassembly and transepithelial permeability

RATIONALE

No studies have assessed the effects of human rhinovirus (HRV) infection on epithelial tight junctions (TJs) and resultant barrier function.

AIM OF THE STUDY

To correlate viral infection with TJ disassembly, epithelial barrier integrity, and function.

MATERIALS AND METHODS

Human airway epithelial cells were infected with HRV minor serotype 1B (HRV-1B) at various 50% tissue culture infectivity doses (TCID₅₀) over 72 hours. HRV replication was assessed by quantitative-polymerase chain reaction (qPCR) while cell viability and apoptosis were assessed by proliferation and apoptotic assays, respectively. Protein expression of claudin-1, occludin, and zonula occludens protein-1 (ZO-1) was assessed using In-Cell™ Western assays. Transepithelial permeability assays were performed to assess effects on barrier functionality. RT² Profiler focused qPCR arrays and pathway analysis evaluating associations between human TJ and antiviral response were performed to identify potential interactions and pathways between genes of interests.

RESULTS

HRV-1B infection affected viability that was both time and TCID₅₀ dependent. Significant increases in apoptosis and viral replication post-infection correlated with viral titer. Viral infection significantly decreased claudin-1 protein expression at the lower TCID₅₀, while a significant decrease in all three TJ protein expressions occurred at higher TCID₅₀. Decrease in protein expression was concomitant with significant increases in epithelial permeability of fluorescein isothiocynate labeled-dextran 4 and 20 kDa. Analysis of focused qPCR arrays demonstrated a significant decrease in ZO-1 gene expression. Furthermore, network analysis between human TJ and antiviral response genes revealed possible interactions and regulation of TJ genes via interleukin (IL)-15 in response to HRV-1B infection.

CONCLUSION

HRV-1B infection directly alters human airway epithelial TJ expression leading to increased epithelial permeability potentially via an antiviral response of IL-15.

Is the role of rhinoviruses as causative agents of pediatric community-acquired pneumonia over-estimated?

The role that rhinoviruses, enteroviruses, parainfluenza viruses, coronaviruses and human bocavirus play in pediatric pneumonia is insufficiently studied. We used polymerase chain reaction (PCR) to study 9 virus groups, including 16 different viruses or viral strains, in 56 ambulatory children with radiologically confirmed community-acquired pneumonia (CAP). The same tests were carried out on 474 apparently healthy control children of the same age and sex. The mean age of children with CAP was 6.5 years (SD 4.2). Respiratory syncytial virus (RSV) was found in 19.6 % of 56 cases and in 2.1 % of 474 controls. Adenoviruses were present in 12.5 % of cases (0.2 % controls) and metapneumovirus and influenza A virus each in 10.7 % of cases (0.2 % controls). Interestingly, rhinoviruses were less common in cases (10.7 %) than in controls (22.4 %): odds ratio 0.36 (95%CI) 0.15-0.87) in conditional logistic regression including 56 cases and 280 controls matched for age, sex and sampling month. The prevalence of parainfluenza viruses, enteroviruses, coronaviruses and human bocavirus were similar in both groups.

CONCLUSION

We conclude that the role of rhinoviruses as an etiology of pediatric CAP has been over-estimated, mainly due to the non-controlled designs of previous studies. What is Known: • In non-controlled studies, rhinovirus detection has been common, next to respiratory syncytial virus, in children with viral community-acquired pneumonia (CAP). • Enteroviruses, coronaviruses and the human bocavirus have been found less frequently. What is New: • In this controlled study, rhinoviruses were detected more often in healthy controls than in children with CAP, and enteroviruses, coronaviruses and human bocavirus were detected equally often in cases and controls. • We conclude that previous studies have over-estimated the role of rhinoviruses in the etiology of CAP in children.

Kinetic Differences and Synergistic Antiviral Effects Between Type I and Type III Interferon Signaling Indicate Pathway Independence

The spread of acute respiratory viral infections is controlled by type I and III interferon (IFN) signaling. While the mechanisms of type I IFN signaling have been studied in detail, features that distinguish type III IFN signaling remain poorly understood. Type III IFNs play an essential role in limiting infections of intestinal and respiratory epithelial surfaces; however, type III IFNs have been shown to activate similar genes to type I IFNs, raising the question of how these IFNs differ and their signals interact. We measured the kinetics of type I and III IFN activation, functional stability, and downstream antiviral responses on A549 human lung epithelial cells. Similar kinetics were found for transcriptional upregulation and secretion of type I and III IFNs in response to infection by an RNA virus, peaking at 12 h postinfection, and both protein types had similar stabilities with functional half-lives extending beyond 2 days. Both IFNs activated potent cellular antiviral responses; however, responses to type III IFNs were delayed by 2-6 h relative to type I IFN responses. Combined treatments with type I and III IFNs produced enhanced antiviral effects, and quantitative analysis of these data with a Bliss interaction model provides evidence for independence of type I and III IFN downstream signaling pathways. This novel synergistic interaction has therapeutic implications for treatment of respiratory virus infections.

Human parainfluenza virus type 3 (HPIV3) induces production of IFNγ and RANTES in human nasal epithelial cells (HNECs)

Background

Human parainfluenza virus type 3 (HPIV3), while infecting lower airway epithelial cells induces pneumonia and bronchiolitis in infants and children, and may lead to asthma exacerbations in children and adults. Respiratory viruses invading the airway epithelium activate innate immune response and induce inflammatory cytokine release contributing to the pathophysiology of upper and lower airway disorders. However, the effects of HPIV3 infection on nasal epithelial cells have not been well defined.

The aim of this study was to evaluate the effect of the HPIV3 infection on cultured human nasal epithelial cells (HNECs) and the release of interferon gamma and other cytokines.

Methods

RPMI 2650, a human nasal epithelial cell line was cultured into confluence and was infected with HPIV3 (MOI of 0.1, 0.01 and 0.001). The protein release into supernatants and mRNA expression of selected cytokines were assessed 24, 48 and 72 h after infection. Cytokine concentrations in supernatants were measured by ELISA and expression of cytokine mRNA in RPMI 2650 cells confirmed by real time RT-PCR analysis.

Results

HNECs infection with HPIV3 did not induce cytotoxicity for at least 48 hours, but significantly increased IFN-γ protein concentration in the cell supernatants at 24 h and 48 h post infection (by 387% and 485% respectively as compared to mock infected cells). At 24 h a significant increase in expression of mRNA for IFNγ was observed. RANTES protein concentration and mRNA expression were significantly increased at 72 h after infection (mean protein concentration: 3.5 ± 1.4 pg/mL for 0.001 MOI, 10.8 ± 4.6 pg/mL for 0.01 MOI and 61.5 ± 18.4 pg/mL for 0.1 MOI as compared to 2.4 ± 1.3 pg/mL for uninfected cells). No measurable concentrations of TNF-α, IL-10, TSLP, IL-8, GM-CSF or eotaxin, were detected in virus infected cells supernatants.

Conclusions

HPIV3 effectively infects upper airway epithelial cells and the infection is associated with induction of IFN-γ and generation of RANTES.

Interferon gene expression in sputum cells correlates with the Asthma Index Score during virus-induced exacerbations

Background

The majority of asthma exacerbations are related to viral respiratory infections. Some, but not all, previous studies have reported that low interferon responses in patients with asthma increase the risk for virus‐induced exacerbations.

Objective

We sought to determine the relationship between lower airway inflammatory biomarkers, specifically interferon gene expression, and the severity or presence of an exacerbation in asthmatics experiencing a naturally occurring viral infection.

Methods

Sputum samples were analysed from subjects in an asthma exacerbation study who experienced a confirmed viral infection. Subjects were monitored for daily symptoms, medication use and peak expiratory flow rate until baseline. Sputum samples were assessed for cell counts and gene expression.

Results

Interferon gamma expression was significantly greater in patients with asthma exacerbations compared to non‐exacerbating patients (P = 0.002). IFN‐α1, IFN‐β1 and IFN‐γ mRNA levels correlated with the peak Asthma Index (r = 0.58, P < 0.001; r = 0.57, P = 0.001; and r = 0.51, P = 0.004, respectively). Additionally, IL‐13, IL‐10 and eosinophil major basic protein mRNA levels were greater in patients with asthma exacerbations compared to non‐exacerbating patients (P = 0.03, P = 0.06 and P = 0.02, respectively), and IL‐13 mRNA correlated with the peak Asthma Index (P = 0.006).

Conclusions

Our findings indicate that asthma exacerbations are associated with increased rather than decreased expression of interferons early in the course of infection. These findings raise the possibility that excessive virus‐induced interferon production during acute infections can contribute to airway inflammation and exacerbations of asthma.

Proteases of human rhinovirus: role in infection

Human rhinoviruses (HRV) are the major etiological agents of the common cold and asthma exacerbations, with significant worldwide health and economic impact. Although large-scale population vaccination has proved successful in limiting or even eradicating many viruses, the more than 100 distinct serotypes mean that conventional vaccination is not a feasible strategy to combat HRV. An alternative strategy is to target conserved viral proteins such as the HRV proteases, 2A(pro) and 3C(pro), the focus of this review. Necessary for host cell shutoff, virus replication, and pathogenesis, 2A(pro) and 3C(pro) are clearly viable drug targets, and indeed, 3C(pro) has been successfully targeted for treating the common cold in experimental infection. 2A(pro) and 3C(pro) are crucial for virus replication due to their role in polyprotein processing as well as cleavage of key cellular proteins to inhibit cellular transcription and translation. Intriguingly, the action of the HRV proteases also disrupts nucleocytoplasmic trafficking, contributing to HRV cytopathic effects. Improved understanding of the protease-cell interactions should enable new therapeutic approaches to be identified for drug development.

Human rhinovirus induced cytokine/chemokine responses in human airway epithelial and immune cells

Infections with human rhinovirus (HRV) are commonly associated with acute upper and lower respiratory tract disease and asthma exacerbations. The role that HRVs play in these diseases suggests it is important to understand host-specific or virus-specific factors that contribute to pathogenesis. Since species A HRVs are often associated with more serious HRV disease than species B HRVs, differences in immune responses they induce should inform disease pathogenesis. To identify species differences in induced responses, we evaluated 3 species A viruses, HRV 25, 31 and 36 and 3 species B viruses, HRV 4, 35 and 48 by exposing human PBMCs to HRV infected Calu-3 cells. To evaluate the potential effect of memory induced by previous HRV infection on study responses, we tested cord blood mononuclear cells that should be HRV naïve. There were HRV-associated increases (significant increase compared to mock-infected cells) for one or more HRVs for IP-10 and IL-15 that was unaffected by addition of PBMCs, for MIP-1α, MIP-1β, IFN-α, and HGF only with addition of PBMCs, and for ENA-78 only without addition of PBMCs. All three species B HRVs induced higher levels, compared to A HRVs, of MIP-1α and MIP-1β with PBMCs and ENA-78 without PBMCs. In contrast, addition of CBMCs had less effect and did not induce MIP-1α, MIP-1β, or IFN-α nor block ENA-78 production. Addition of CBMCs did, however, increase IP-10 levels for HRV 35 and HRV 36 infection. The presence of an effect with PBMCs and no effect with CBMCs for some responses suggest differences between the two types of cells possibly because of the presence of HRV memory responses in PBMCs and not CBMCs or limited response capacity for the immature CBMCs relative to PBMCs. Thus, our results indicate that different HRV strains can induce different patterns of cytokines and chemokines; some of these differences may be due to differences in memory responses induced by past HRV infections, and other differences related to virus factors that can inform disease pathogenesis.

Interferon response and respiratory virus control are preserved in bronchial epithelial cells in asthma

BACKGROUND

Some investigators find a deficiency in IFN production from airway epithelial cells infected with human rhinovirus in asthma, but whether this abnormality occurs with other respiratory viruses is uncertain.

OBJECTIVE

To assess the effect of influenza A virus (IAV) and respiratory syncytial virus (RSV) infection on IFN production and viral level in human bronchial epithelial cells (hBECs) from subjects with and without asthma.

METHODS

Primary-culture hBECs from subjects with mild to severe asthma (n = 11) and controls without asthma (hBECs; n = 7) were infected with live or ultraviolet-inactivated IAV (WS/33 strain), RSV (Long strain), or RSV (A/2001/2-20 strain) with multiplicity of infection 0.01 to 1. Levels of virus along with IFN-β and IFN-λ and IFN-stimulated gene expression (tracked by 2'-5'-oligoadenylate synthetase 1 and myxovirus (influenza virus) resistance 1 mRNA) were determined up to 72 hours postinoculation.

RESULTS

After IAV infection, viral levels were increased 2-fold in hBECs from asthmatic subjects compared with nonasthmatic control subjects (P < .05) and this increase occurred in concert with increased IFN-λ1 levels and no significant difference in IFNB1, 2'-5'-oligoadenylate synthetase 1, or myxovirus (influenza virus) resistance 1mRNA levels. After RSV infections, viral levels were not significantly increased in hBECs from asthmatic versus nonasthmatic subjects and the only significant difference between groups was a decrease in IFN-λ levels (P < .05) that correlated with a decrease in viral titer. All these differences were found only at isolated time points and were not sustained throughout the 72-hour infection period.

CONCLUSIONS

The results indicate that IAV and RSV control and IFN response to these viruses in airway epithelial cells is remarkably similar between subjects with and without asthma.

Human rhinovirus-induced ISG15 selectively modulates epithelial antiviral immunity

Human rhinovirus (HRV) infections trigger exacerbations of lower airway diseases. HRV infects human airway epithelial cells and induces proinflammatory and antiviral molecules that regulate the response to HRV infection. Interferon (IFN)-stimulated gene of 15 kDa (ISG15) has been shown to regulate other viruses. We now show that HRV-16 infection induces both intracellular epithelial ISG15 expression and ISG15 secretion in vitro. Moreover, ISG15 protein levels increased in nasal secretions of subjects with symptomatic HRV infections. HRV-16-induced ISG15 expression is transcriptionally regulated via an IFN regulatory factor pathway. ISG15 does not directly alter HRV replication but does modulate immune signaling via the viral sensor protein RIG-I to impact production of CXCL10, which has been linked to innate immunity to viruses. Extracellular ISG15 also alters CXCL10 production. We conclude that ISG15 has a complex role in host defense against HRV infection, and that additional studies are needed to clarify the role of this molecule.

Human rhinovirus 16 causes Golgi apparatus fragmentation without blocking protein secretion

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.

Major and minor group rhinoviruses elicit differential signaling and cytokine responses as a function of receptor-mediated signal transduction

Major- and minor-group human rhinoviruses (HRV) enter their host by binding to the cell surface molecules ICAM-1 and LDL-R, respectively, which are present on both macrophages and epithelial cells. Although epithelial cells are the primary site of productive HRV infection, previous studies have implicated macrophages in establishing the cytokine dysregulation that occurs during rhinovirus-induced asthma exacerbations. Analysis of the transcriptome of primary human macrophages exposed to major- and minor-group HRV demonstrated differential gene expression. Alterations in gene expression were traced to differential mitochondrial activity and signaling pathway activation between two rhinovirus serotypes, HRV16 (major-group) and HRV1A (minor-group), upon initial HRV binding. Variances in phosphorylation of kinases (p38, JNK, ERK5) and transcription factors (ATF-2, CREB, CEBP-alpha) were observed between the major- and minor-group HRV treatments. Differential activation of signaling pathways led to changes in the production of the asthma-relevant cytokines CCL20, CCL2, and IL-10. This is the first report of genetically similar viruses eliciting dissimilar cytokine release, transcription factor phosphorylation, and MAPK activation from macrophages, suggesting that receptor use is a mechanism for establishing the inflammatory microenvironment in the human airway upon exposure to rhinovirus.

Effects of rhinovirus species on viral replication and cytokine production

BACKGROUND

Epidemiologic studies provide evidence of differential virulence of rhinovirus species (RV). We recently reported that RV-A and RV-C induced more severe illnesses than RV-B, which suggests that the biology of RV-B might be different from RV-A or RV-C.

OBJECTIVE

To test the hypothesis that RV-B has lower replication and induces lesser cytokine responses than RV-A or RV-C.

METHODS

We cloned full-length cDNA of RV-A16, A36, B52, B72, C2, C15, and C41 from clinical samples and grew clinical isolates of RV-A7 and RV-B6 in cultured cells. Sinus epithelial cells were differentiated at the air-liquid interface. We tested for differences in viral replication in epithelial cells after infection with purified viruses (10(8) RNA copies) and measured virus load by quantitative RT-PCR. We measured lactate dehydrogenase (LDH) concentration as a marker of cellular cytotoxicity, and cytokine and/or chemokine secretion by multiplex ELISA.

RESULTS

At 24 hours after infection, the virus load of RV-B (RV-B52, RV-B72, or RV-B6) in adherent cells was lower than that of RV-A or RV-C. The growth kinetics of infection indicated that RV-B types replicate more slowly. Furthermore, RV-B released less LDH than RV-A or RV-C, and induced lower levels of cytokines and chemokines such as CXCL10, even after correction for viral replication. RV-B replicates to lower levels also in primary bronchial epithelial cells.

CONCLUSIONS

Our results indicate that RV-B types have lower and slower replication, and lower cellular cytotoxicity and cytokine and/or chemokine production compared with RV-A or RV-C. These characteristics may contribute to reduced severity of illnesses that has been observed with RV-B infections.

High degree of overlap between responses to a virus and to the house dust mite allergen in airway epithelial cells

BACKGROUND

Airway epithelium is widely considered to play an active role in immune responses through its ability to detect changes in the environment and to generate a microenvironment for immune competent cells. Therefore, besides its role as a physical barrier, epithelium affects the outcome of the immune response by the production of various pro-inflammatory mediators.

METHODS

We stimulated airway epithelial cells with viral double stranded RNA analogue poly(I:C) or with house dust mite in a time course of 24 hours. In order to determine cytokines production by stimulated cells, we performed multiplex enzyme linked immunosorbant assay (ELISA).

RESULTS

We demonstrate that the temporal pattern of the genes that respond to virus exposure in airway epithelium resembles to a significant degree their pattern of response to HDM. The gene expression pattern of EGR1, DUSP1, FOSL1, JUN, MYC, and IL6 is rather similar after viral (poly(I:C)) and HDM exposure. However, both triggers also induce a specific response (e.g. ATF3, FOS, and NFKB1). We confirmed these data by showing that epithelial cells produce a variety of similar mediators in response to both poly(I:C) and HDM challenge (IL1-RA, IL-17, IFN-α and MIP1-α), sometimes with a quantitative difference in response (IL2-R, IL-6, IL-8, MCP-1, MIG, and HGF). Interestingly, only four mediators (IL-12, IP-10, RANTES and VEGF) where up-regulated specifically by poly(I:C) and not by HDM. Additionally, we report that pre-exposure to HDM deregulates production of cytokines and mediators in response to poly(I:C).

CONCLUSIONS

Epithelial cells responses to the HDM-allergen and a virus strongly resemble both in gene expression and in protein level explaining why these two responses may affect each other.

Effects of vitamin D on airway epithelial cell morphology and rhinovirus replication

Vitamin D has been linked to reduced risk of viral respiratory illness. We hypothesized that vitamin D could directly reduce rhinovirus (RV) replication in airway epithelium. Primary human bronchial epithelial cells (hBEC) were treated with vitamin D, and RV replication and gene expression were evaluated by quantitative PCR. Cytokine/chemokine secretion was measured by ELISA, and transepithelial resistance (TER) was determined using a voltohmmeter. Morphology was examined using immunohistochemistry. Vitamin D supplementation had no significant effects on RV replication, but potentiated secretion of CXCL8 and CXCL10 from infected or uninfected cells. Treatment with vitamin D in the form of 1,25(OH)₂D caused significant changes in cell morphology, including thickening of the cell layers (median of 46.5 µm [35.0–69.0] vs. 30 µm [24.5–34.2], p<0.01) and proliferation of cytokeratin-5-expressing cells, as demonstrated by immunohistochemical analysis. Similar effects were seen for 25(OH)D. In addition to altering morphology, higher concentrations of vitamin D significantly upregulated small proline-rich protein (SPRR1β) expression (6.3 fold-induction, p<0.01), suggestive of squamous metaplasia. Vitamin D treatment of hBECs did not alter repair of mechanically induced wounds. Collectively, these findings indicate that vitamin D does not directly affect RV replication in airway epithelial cells, but can influence chemokine synthesis and alters the growth and differentiation of airway epithelial cells.

Detection of viral and bacterial pathogens in acute respiratory infections

OBJECTIVES

The role of bacteria in acute respiratory illnesses (ARI) of adults and interactions with viral infections is incompletely understood. This study tested the hypothesis that bacterial co-infection during ARI adds to airway inflammation and illness severity.

METHODS

Two groups of 97 specimens each were randomly selected from multiplex-PCR identified virus-positive and virus-negative nasal specimens obtained from adults with new onset ARI, and 40 control specimens were collected from healthy adults. All specimens were analyzed for Haemophilus influenzae(HI), Moraxella catarrhalis(MC) and Streptococcus pneumoniae(SP) by quantitative-PCR. General linear models tested for relationships between respiratory pathogens, biomarkers (nasal wash neutrophils and CXCL8), and ARI-severity.

RESULTS

Nasal specimens from adults with ARIs were more likely to contain bacteria (37% overall; HI = 28%, MC = 14%, SP = 7%) compared to specimens from healthy adults (5% overall; HI = 0%, MC = 2.5%, SP = 2.5%; p < 0.001). Among ARI specimens, bacteria were more likely to be detected among virus-negative specimens compared to virus-positive specimens (46% vs. 27%; p = 0.0046). The presence of bacteria was significantly associated with increased CXCL8 and neutrophils, but not increased symptoms.

CONCLUSION

Pathogenic bacteria were more often detected in virus-negative ARI, and also associated with increased inflammatory biomarkers. These findings suggest the possibility that bacteria may augment virus-induced ARI and contribute to airway inflammation.

Effect of exogenous interferons on rhinovirus replication and airway inflammatory responses

BACKGROUND

Human rhinoviruses (HRVs) are the most common cause of asthma exacerbations. In airway epithelial cells, the primary site of HRV infection, decreased production of interferons (IFNs) may result in greater susceptibility to HRV and worsened symptoms. Thus, exogenous IFN could supplement the innate immune response and provide a treatment for virus-induced asthma exacerbations. Furthermore, the effects of exogenous IFN could be type specific in part because of the cellular distribution of type 1 and type 2 IFN receptors.

OBJECTIVE

To investigate the effects of exogenous IFNs on HRV replication in bronchial epithelial cells.

METHODS

Frozen stocks of primary human bronchial epithelial cells from healthy donors were cultured in monolayers; pretreated (24 hours) with 0.1-ng/mL, 1-ng/mL, or 10-ng/mL doses of IFN-α, -β, -λ1, or -λ2; and infected with HRV-1A. Viral replication was quantified using real-time reverse transcription-polymerase chain reaction, and cytokine and chemokine secretion 24 hours after infection was measured by multiplex enzyme-linked immunosorbent assay.

RESULTS

Compared with untreated samples, IFN-α, IFN-β, IFN-λ1, and IFN-λ2 (0.1 ng/mL) significantly reduced HRV replication after high- (P < .02) and low-dose inoculation (P < .05). Similar effects were seen in 1-ng/mL and 10-ng/mL doses of IFN, where HRV replication was significantly decreased in both high- (P < .001) and low-dose inoculation (P < .001). Treatment with IFNs also enhanced HRV-induced IFN-γ-induced protein 10 secretion (P < .001). Finally, treatment with either IFN-λ1 or IFN-λ2 significantly increased HRV-induced secretion of RANTES (regulated on activation, normal T-expressed, and presumably secreted) (P < .05) but not IL-1β or vascular endothelial growth factor.

CONCLUSION

These findings suggest that exogenous IFNs, IFN-λ1 in particular, warrant further study as a potential therapy for virus-induced asthma exacerbations.

Budesonide and formoterol effects on rhinovirus replication and epithelial cell cytokine responses

Background

Combination therapy with budesonide and formoterol reduces exacerbations of asthma, which are closely associated with human rhinovirus (RV) infections in both children and adults. These data suggest that budesonide and formoterol inhibit virus-induced inflammatory responses of airway epithelial cells.

Methods

To test this hypothesis, bronchial epithelial (BE) cells were obtained from airway brushings of 8 subjects with moderate-to-severe allergic asthma and 9 with neither asthma nor respiratory allergies. Cultured BE cells were incubated for 24 hours with budesonide (1.77 μM), formoterol (0.1 μM), both, or neither, and then inoculated with RV-16 (5×10⁶ plaque forming units [PFU]/mL). After 24 hours, viral replication (RV RNA), cytokine secretion (CXCL8, CXCL10, TNFα, IFN-β, IL-28) and mRNA expression (CXCL8, CXCL10, TNF, IFNB1, IL28A&B) were analyzed.

Results

RV infection induced CXCL10 protein secretion and IFNB1 and IL28 mRNA expression. Drug treatments significantly inhibited secretion of CXCL10 in mock-infected, but not RV-infected, BE cells, and inhibited secretion of TNFα under both conditions. Neither budesonide nor formoterol, alone or in combination, significantly affected viral replication, nor did they inhibit RV-induced upregulation of IFNB1 and IL28 mRNA. Overall, RV replication was positively related to CXCL10 secretion and induction of IFNB1 and IL28 mRNA, but the positive relationship between RV RNA and CXCL10 secretion was stronger in normal subjects than in subjects with asthma.

Conclusions

Budesonide and formoterol can inhibit BE cell inflammatory responses in vitro without interfering with viral replication or production of interferons. These effects could potentially contribute to beneficial effects of budesonide/formoterol combination therapy in preventing RV-induced asthma exacerbations.

Molecular epidemiology of respiratory viruses in virus-induced asthma

Acute respiratory illness (ARI) due to various viruses is not only the most common cause of upper respiratory infection in humans but is also a major cause of morbidity and mortality, leading to diseases such as bronchiolitis and pneumonia. Previous studies have shown that respiratory syncytial virus (RSV), human rhinovirus (HRV), human metapneumovirus (HMPV), human parainfluenza virus (HPIV), and human enterovirus infections may be associated with virus-induced asthma. For example, it has been suggested that HRV infection is detected in the acute exacerbation of asthma and infection is prolonged. Thus it is believed that the main etiological cause of asthma is ARI viruses. Furthermore, the number of asthma patients in most industrial countries has greatly increased, resulting in a morbidity rate of around 10-15% of the population. However, the relationships between viral infections, host immune response, and host factors in the pathophysiology of asthma remain unclear. To gain a better understanding of the epidemiology of virus-induced asthma, it is important to assess both the characteristics of the viruses and the host defense mechanisms. Molecular epidemiology enables us to understand the pathogenesis of microorganisms by identifying specific pathways, molecules, and genes that influence the risk of developing a disease. However, the epidemiology of various respiratory viruses associated with virus-induced asthma is not fully understood. Therefore, in this article, we review molecular epidemiological studies of RSV, HRV, HPIV, and HMPV infection associated with virus-induced asthma.

Progressive changes in inflammatory and matrix adherence of bronchial epithelial cells with persistent respiratory syncytial virus (RSV) infection (progressive changes in RSV infection)

In addition to the acute manifestations of respiratory syncytial virus (RSV), persistent infection may be associated with long-term complications in the development of chronic respiratory diseases. To understand the mechanisms underlying RSV-induced long-term consequences, we established an in vitro RSV (strain A2) infection model using human bronchial epithelial (16HBE) cells that persists over four generations and analyzed cell inflammation and matrix adherence. Cells infected with RSV at multiplicity of infection (MOI) 0.0067 experienced cytolytic or abortive infections in the second generation (G2) or G3 but mostly survived up to G4. Cell morphology, leukocyte and matrix adherence of the cells did not change in G1 or G2, but subsequently, leukocyte adherence and cytokine/chemokine secretion, partially mediated by intercellular adhesion molecule-1 (ICAM-1), increased drastically, and matrix adherence, partially mediated by E-cadherin, decreased until the cells died. Tumor necrosis factor-α (TNF-α) secretion was inhibited by ICAM-1 antibody in infected-16HBE cells, suggesting that positive feedback between TNF-α secretion and ICAM-1 expression may be significant in exacerbated inflammation. These data demonstrate the susceptibility of 16HBE cells to RSV and their capacity to produce long-term progressive RSV infection, which may contribute to inflammation mobilization and epithelial shedding.

Mutation tryptophan to leucine at position 222 of haemagglutinin could facilitate H3N2 influenza A virus infection in dogs

An avian-like H3N2 influenza A virus (IAV) has recently caused sporadic canine influenza outbreaks in China and Korea, but the molecular mechanisms involved in the interspecies transmission of H3N2 IAV from avian to canine species are not well understood. Sequence analysis showed that residue 222 in haemagglutinin (HA) is predominantly tryptophan (W) in the closely related avian H3N2 IAV, but was leucine (L) in canine H3N2 IAV. In this study, reassortant viruses rH3N2-222L (canine-like) and rH3N2-222W (avian-like) with HA mutation L222W were generated using reverse genetics to evaluate the significance of the L222W mutation on receptor binding and host tropism of H3N2 IAV. Compared with rH3N2-222W, rH3N2-222L grew more rapidly in MDCK cells and had significantly higher infectivity in primary canine tracheal epithelial cells. Tissue-binding assays demonstrated that rH3N2-222L had a preference for canine tracheal tissues rather avian tracheal tissues, whereas rH3N2-222W favoured slightly avian rather canine tracheal tissues. Glycan microarray analysis suggested both rH3N2-222L and rH3N2-222W bound preferentially to α2,3-linked sialic acids. However, the rH3N2-222W had more than twofold less binding affinity than rH3N2-222L to a set of glycans with Neu5Aca2-3Galb1-4(Fuca-)-like or Neu5Aca2-3Galb1-3(Fuca-)-like structures. These data suggest the W to L mutation at position 222 of the HA could facilitate infection of H3N2 IAV in dogs, possibly by increasing the binding affinities of the HA to specific receptors with Neu5Aca2-3Galb1-4(Fuca-) or Neu5Aca2-3Galb1-3(Fuca-)-like structures that are present in dogs.

Human rhinovirus infections of the lower respiratory tract in hematopoietic stem cell transplant recipients

BACKGROUND

Human rhinoviruses (HRVs) are a common cause of upper respiratory infection (URI) in hematopoietic stem cell transplant (HSCT) recipients; yet, their role in lower respiratory illness is not well understood.

METHODS

We performed a retrospective chart review of HSCT recipients with HRV infection from the time molecular detection methods were implemented at our institution in 2008. Factors associated with proven or possible HRV pneumonia at the first HRV detection were evaluated by univariate and multivariate analysis. We then characterized all episodes of proven and possible HRV pneumonia from the initial HRV infection through a 1-year follow-up period.

RESULTS

Between 2008 and 2011, 63 HSCT recipients had ≥1 documented HRV infections. At first HRV detection, 36 (57%) patients had HRV URI and 27 (43%) had proven or possible HRV pneumonia; in multivariate analysis, hypoalbuminemia (odds ratio [OR] 9.5, 95% confidence interval [CI] 1.3-71.7; P = 0.03) and isolation of respiratory co-pathogen(s) (OR 24.2, 95% CI 2.0-288.4; P = 0.01) were independently associated with pneumonia. During the study period, 22 patients had 25 episodes of proven HRV pneumonia. Fever (60%), cough (92%), sputum production (61%), and dyspnea (60%) were common symptoms. Fifteen (60%) episodes demonstrated bacterial (n = 7), fungal (n = 5), or viral (n = 3) co-infection. Among the remaining 10 (40%) cases of HRV monoinfection, patients' oxygen saturations ranged from 80% to 97% on ambient air, and computed tomography scans showed peribronchiolar, patchy, ground glass infiltrates.

CONCLUSIONS

HRV pneumonia is relatively common after HSCT and frequently accompanied by bacterial co-infection. As use of molecular assays for respiratory viral diagnosis becomes widespread, HRV will be increasingly recognized as a significant cause of pneumonia in immunocompromised hosts.

Response to rhinovirus infection by human airway epithelial cells and peripheral blood mononuclear cells in an in vitro two-chamber tissue culture system

Human rhinovirus (HRV) infections are associated with the common cold, occasionally with more serious lower respiratory tract illnesses, and frequently with asthma exacerbations. The clinical features of HRV infection and its association with asthma exacerbation suggest that some HRV disease results from virus-induced host immune responses to infection. To study the HRV-infection-induced host responses and the contribution of these responses to disease, we have developed an in vitro model of HRV infection of human airway epithelial cells (Calu-3 cells) and subsequent exposure of human peripheral blood mononuclear cells (PBMCs) to these infected cells in a two-chamber trans-well tissue culture system. Using this model, we studied HRV 14 (species B) and HRV 16 (species A) induced cytokine and chemokine responses with PBMCs from four healthy adults. Infection of Calu-3 cells with either virus induced HRV-associated increases in FGF-Basic, IL-15, IL-6, IL-28A, ENA-78 and IP-10. The addition of PBMCs to HRV 14-infected cells gave significant increases in MIP-1β, IL-28A, MCP-2, and IFN-α as compared with mock-infected cells. Interestingly, ENA-78 levels were reduced in HRV 14 infected cells that were exposed to PBMCs. Addition of PBMCs to HRV 16-infected cells did not induce MIP-1β, IL-28A and IFN-α efficiently nor did it decrease ENA-78 levels. Our results demonstrate a clear difference between HRV 14 and HRV 16 and the source of PBMCs, in up or down regulation of several cytokines including those that are linked to airway inflammation. Such differences might be one of the reasons for variation in disease associated with different HRV species including variation in their link to asthma exacerbations as suggested by other studies. Further study of immune responses associated with different HRVs and PBMCs from different patient groups, and the mechanisms leading to these differences, should help characterize pathogenesis of HRV disease and generate novel approaches to its treatment.

Rhinovirus-Infected Epithelial Cells Produce More IL-8 and RANTES Compared With Other Respiratory Viruses

Purpose

The environmental factors human rhinoviruses (HRVs) and house dust mites (HDMs) are the most common causes of acute exacerbations of asthma. The aim of this study was to compare the chemokine production induced by HRVs in airway epithelial cells with that induced by other respiratory viruses, and to investigate synergistic interactions between HRVs and HDMs on the induction of inflammatory chemokines in vitro.

Methods

A549 human airway epithelial cells were infected with either rhinovirus serotype 7, respiratory syncytial virus (RSV)-A2 strain, or adenovirus serotype 3 and analyzed for interleukin (IL)-8 and regulated on activation, normal T-cell expressed and secreted (RANTES) release and mRNA expression. Additionally, activation of nuclear factor (NF)-κB and activator protein (AP)-1 were evaluated. The release of IL-8 and RANTES was also measured in cells stimulated simultaneously with a virus and the HDM allergen, Der f1.

Results

HRV caused greater IL-8 and RANTES release and mRNA expression compared with either RSV or adenovirus. NF-κB and AP-1 were activated in these processes. Cells incubated with a virus and Der f1 showed an increased IL-8 release. However, compared with cells incubated with virus alone as the stimulator, only HRV with Der f1 showed a statistically significant increase.

Conclusions

IL-8 and RANTES were induced to a greater extent by HRV compared with other viruses, and only HRV with Der f1 acted synergistically to induce bronchial epithelial IL-8 release. These findings may correspond with the fact that rhinoviruses are identified more frequently than other viruses in cases of acute exacerbation of asthma.

Difficult childhood asthma: management and future

Diagnosis and management of severe asthma implies the definition of different entities, that is, difficult asthma and refractory severe asthma, but also the different phenotypes included in the term refractory severe asthma. A complete evaluation by a physician expert in asthma is necessary, adapted for each child. Identification of mechanisms involved in different phenotypes in refractory severe asthma may improve the therapeutic approach. The quality of care and monitoring of children with severe asthma is as important as the prescription drug, and is also crucial for differentiating between severe asthma and difficult asthma, whereby expertise is required.

Rhinovirus-Induced Exacerbations of Asthma and COPD

Over the past two decades, increasing evidence has shown that, in patients with chronic airways disease, viral infection is the most common cause of exacerbation. This review will examine the evidence for viral-induced exacerbations of asthma and chronic obstructive lung disease and the potential mechanisms by which viruses cause exacerbations. Attention will be focused on rhinovirus, the most common cause of respiratory exacerbations. Exacerbations due to rhinovirus, which infects relatively few cells in the airway and does not cause the cytotoxicity of other viruses such as influenza or respiratory syncytial virus, are particularly poorly understood. While the innate immune response likely plays a role in rhinovirus-induced exacerbations, its precise role, either adaptive or maladaptive, is debated. Because current treatment strategies are only partially effective, further research examining the cellular and molecular mechanisms underlying viral-induced exacerbations of chronic airways diseases is warranted.

Biological characteristics and propagation of human rhinovirus-C in differentiated sinus epithelial cells

Information about the basic biological properties of human rhinovirus-C (HRV-C) viruses is lacking due to difficulties with culturing these viruses. Our objective was to develop a cell culture system to grow HRV-C. Epithelial cells from human sinuses (HSEC) were differentiated at air–liquid interface (ALI). Differentiated cultures supported 1–2  logs growth of HRV-C15 as detected by quantitative RT-PCR. Two distinguishing features of HRVs are acid lability and optimal growth at 33–34  °C. We used this system to show that HRV-C15 is neutralized by low pH (4.5). In contrast to most HRV types, replication of HRV-C15 and HRV-C41 was similar at 34 and 37 °C. The HSEC ALI provides a useful tool for quantitative studies of HRV-C replication. The ability of HRV-C to grow equally well at 34 °C and 37 °C may contribute to the propensity for HRV-C to cause lower airway illnesses in infants and children with asthma.

Activation of the small G-protein Rac by human rhinovirus attenuates the TLR3/IFN-α axis while promoting CCL2 release in human monocyte-lineage cells

Although rhinoviral infections, a major cause of asthma exacerbations, occur predominantly in upper airway bronchial epithelial cells, monocytic-lineage cells are implicated in establishing the inflammatory microenvironment observed during the disease. Human rhinovirus (HRV) is unique in that nearly genetically identical viruses bind either the ICAM-1 or low-density lipoprotein receptor (LDL-R). Within minutes of binding, HRV is capable of eliciting a signaling response in both epithelial cells and monocyte-derived macrophages. It is unclear whether this signaling response is important to the subsequent release of inflammatory mediators, particularly in cells not capable of supporting viral replication. We show here that the small molecular mass G-protein Rac is activated following exposure of macrophages to HRV serotypes known to be ICAM-1- and LDL-R-tropic. We demonstrate that inhibiting Rac resulted in the upregulation of TLR3 in macrophages exposed to major- and minor-group HRV, and resulted in increased release of IFN-α. Furthermore, inhibiting Rac in HRV-exposed macrophages attenuated activation of the stress kinase p38 and release of the pro-inflammatory cytokine CCL2, but inhibiting Rac did not affect release of the pro-inflammatory cytokine CCL5. These findings suggest that Rac is an important regulator in establishing the inflammatory microenvironment that is initiated in the human airway upon exposure to rhinovirus.