The basic immunology of asthma.

In many asthmatics, chronic airway inflammation is driven by IL-4-, IL-5-, and IL-13-producing Th2 cells or ILC2s. Type 2 cytokines promote hallmark features of the disease such as eosinophilia, mucus hypersecretion, bronchial hyperresponsiveness (BHR), IgE production, and susceptibility to exacerbations. However, only half the asthmatics have this "type 2-high" signature, and "type 2-low" asthma is more associated with obesity, presence of neutrophils, and unresponsiveness to corticosteroids, the mainstay asthma therapy. Here, we review the underlying immunological basis of various asthma endotypes by discussing results obtained from animal studies as well as results generated in clinical studies targeting specific immune pathways.

Transcriptome networks identify mechanisms of viral and nonviral asthma exacerbations in children.

Respiratory infections are common precursors to asthma exacerbations in children, but molecular immune responses that determine whether and how an infection causes an exacerbation are poorly understood. By using systems-scale network analysis, we identify repertoires of cellular transcriptional pathways that lead to and underlie distinct patterns of asthma exacerbation. Specifically, in both virus-associated and nonviral exacerbations, we demonstrate a set of core exacerbation modules, among which epithelial-associated SMAD3 signaling is upregulated and lymphocyte response pathways are downregulated early in exacerbation, followed by later upregulation of effector pathways including epidermal growth factor receptor signaling, extracellular matrix production, mucus hypersecretion, and eosinophil activation. We show an additional set of multiple inflammatory cell pathways involved in virus-associated exacerbations, in contrast to squamous cell pathways associated with nonviral exacerbations. Our work introduces an in vivo molecular platform to investigate, in a clinical setting, both the mechanisms of disease pathogenesis and therapeutic targets to modify exacerbations.

Pathogenesis of HIV-Related Lung Disease: Immunity, Infection, and Inflammation.

Despite anti-retroviral therapy (ART), human immunodeficiency virus-1 (HIV)-related pulmonary disease continues to be a major cause of morbidity and mortality for people living with HIV (PLWH). The spectrum of lung diseases has changed from acute opportunistic infections resulting in death to chronic lung diseases for those with access to ART. Chronic immune activation and suppression can result in impairment of innate immunity and progressive loss of T cell and B cell functionality with aberrant cytokine and chemokine responses systemically as well as in the lung. HIV can be detected in the lungs of PLWH and has profound effects on cellular immune functions. In addition, HIV-related lung injury and disease can occur secondary to a number of mechanisms including altered pulmonary and systemic inflammatory pathways, viral persistence in the lung, oxidative stress with additive effects of smoke exposure, microbial translocation, and alterations in the lung and gut microbiome. Although ART has had profound effects on systemic viral suppression in HIV, the impact of ART on lung immunology still needs to be fully elucidated. Understanding of the mechanisms by which HIV-related lung diseases continue to occur is critical to the development of new preventive and therapeutic strategies to improve lung health in PLWH.

Viral and non-viral episodes of wheezing in early life and the development of asthma and respiratory phenotypes among urban children.

BACKGROUND: Viral wheezing is an important risk factor for asthma, which comprises several respiratory phenotypes. We sought to understand if the etiology of early-life wheezing illnesses relates to childhood respiratory and asthma phenotypes. METHODS: Data were collected prospectively on 429 children in the Urban Environment and Childhood Asthma (URECA) birth cohort study through age 10 years. We identified wheezing illnesses and the corresponding viral etiology (PCR testing of nasal mucus) during the first 3 years of life. Six phenotypes of respiratory health were identified at 10 years of age based on trajectories of wheezing, allergic sensitization, and lung function. We compared the etiology of early wheezing illnesses to these wheezing respiratory phenotypes and the development of asthma. RESULTS: In the first 3 years of life, at least one virus was detected in 324 (67%) of the 483 wheezing episodes documented in the study cohort. Using hierarchical partitioning we found that non-viral wheezing episodes accounted for the greatest variance in asthma diagnosed at both 7 and 10 years of age (8.0% and 5.8% respectively). Rhinovirus wheezing illnesses explained the most variance in respiratory phenotype outcome followed by non-viral wheezing episodes (4.9% and 3.9% respectively) at 10 years of age. CONCLUSION AND RELEVANCE: Within this high-risk urban-residing cohort in early life, non-viral wheezing episodes were frequently identified and associated with asthma development. Though rhinovirus wheezing illnesses had the greatest association with phenotype outcome, the specific etiology of wheezing episodes in early life provided limited information about subsequent wheezing phenotypes.

Advances in clinical outcomes: What we have learned during the COVID-19 pandemic.

Our understanding of risk factors and interventions influencing outcomes from coronavirus disease 2019 (COVID-19) has continued to evolve, revealing advances emerging from hypotheses formed at the start of the pandemic. Epidemiologic studies have shown that asthma control, rather than a diagnosis of asthma, is a determinant of COVID-19 severity. Clinical outcomes in patients with primary immunodeficiencies, even in those with impaired cellular immunity, are variable. IL-6 has emerged as a reliable biomarker of COVID-19 severity, and large clinical trials have shown the potential for improving outcomes through inhibition of IL-6 signaling in some patients. Studies of genetic risk factors for severe COVID-19 have also revealed the importance of interferon homeostasis in the defense against severe acute respiratory syndrome coronavirus 2. Because COVID-19 vaccines constitute the primary tool for ending this pandemic, strategies have been developed to address potential allergic and immune-mediated reactions. Here, we discuss advances in our understanding of COVID-19 risk factors and outcomes within the context of allergic and immunologic mechanisms.

In vivo bronchial epithelial interferon responses are augmented in asthma on day 4 following experimental rhinovirus infection.

Despite good evidence of impaired innate antiviral responses in asthma, trials of inhaled interferon-ß given during exacerbations showed only modest benefits in moderate/severe asthma. Using human experimental rhinovirus infection, we observe robust in vivo induction of bronchial epithelial interferon response genes 4 days after virus inoculation in 25 subjects with asthma but not 11 control subjects. This signature correlated with virus loads and lower respiratory symptoms. Our data indicate that the in vivo innate antiviral response is dysregulated in asthma and open up the potential that prophylactic rather than therapeutic interferon therapy may have greater clinical benefit.

Rhinovirus and asthma: Challenges and opportunities.

Human rhinoviruses (RVs) are the primary aetiological agent of the common cold. Generally, the associated infection is mild and self-limiting, but may also be associated with bronchiolitis in infants, pneumonia in the immunocompromised and exacerbation in patients with pulmonary conditions such as asthma or chronic obstructive pulmonary disease. Viral infection accounts for as many as two thirds of asthma exacerbations in children and more than half in adults. Allergy and asthma are major risk factors for more frequent and severe RV-related illnesses. The prevalence of RV-induced wheezing will likely continue to increase given that asthma affects a significant proportion of the population, with allergic asthma accounting for the majority. Several new respiratory viruses and their subgroups have been discovered, with various degrees of relevance. This review will focus on RV infection in the context of the epidemiologic evidence, genetic variability, pathobiology, clinical studies in the context of asthma, differences with other viruses including COVID-19 and current treatment interventions.

Juvenile, but Not Adult, Mice Display Increased Myeloid Recruitment and Extracellular Matrix Remodeling during Respiratory Syncytial Virus Infection.

Early life respiratory syncytial virus (RSV) infection has been linked to the onset of asthma. Despite this association, our knowledge of the progression of the initial viral infection is limited, and no safe or effective vaccine currently exists. Bronchioalveolar lavage, whole-lung cellular isolation, and gene expression analysis were performed on 3-wk- (juvenile) and 8-wk-old (adult) RSV-infected C57BL/6 mice to investigate age-related differences in immunologic responses; juvenile mice displayed a sustained myeloid infiltrate (including monocytes and neutrophils) with increased RNA expression of Ccl2, Ccl3, and Ccl4, when compared with adult mice, at 72 h postinfection. Juvenile mice demonstrated αSma expression (indicative of myofibroblast activity), increased hyaluronan deposition in the lung parenchyma (attributed to asthma progression), and a lack of CD64 upregulation on the surface of monocytes (which, in conjunction with serum amyloid P, is responsible for clearing residual hyaluronan and cellular debris). RSV infection of human airway epithelial cell, human lung fibroblast, and U937 monocyte cocultures (at air-liquid interface) displayed similar CCL expression and suggested matrix metalloproteinase-7 and MMP9 as possible extracellular matrix modifiers. These mouse data, in conjunction with our findings in human monocytes, suggest that the sustained influx of myeloid cells in the lungs of juvenile mice during acute RSV infection could potentiate extracellular matrix remodeling, facilitating conditions that support the development of asthma.

Pulmonary Innate Lymphoid Cell Responses during Rhinovirus-induced Asthma Exacerbations In Vivo: A Clinical Trial.

Rationale: Type 2 innate lymphoid cells (ILC2s) are significant sources of type 2 cytokines, which are implicated in the pathogenesis of asthma and asthma exacerbations. The role of ILC2s in virus-induced asthma exacerbations is not well characterized. Objectives: To characterize pulmonary ILC responses following experimental rhinovirus challenge in patients with moderate asthma and healthy subjects. Methods: Patients with moderate asthma and healthy subjects were inoculated with rhinovirus-16 and underwent bronchoscopy at baseline and at Day 3, and Day 8 after inoculation. Pulmonary ILC1s and ILC2s were quantified in bronchoalveolar lavage using flow cytometry. The ratio of bronchoalveolar lavage ILC2:ILC1 was assessed to determine their relative contributions to the clinical and immune response to rhinovirus challenge. Measurements and Main Results: At baseline, ILC2s were significantly higher in patients with asthma than in healthy subjects. At Day 8, ILC2s significantly increased from baseline in both groups, which was significantly higher in patients with asthma than in healthy subjects (all comparisons P < 0.05). In healthy subjects, ILC1s increased from baseline at Day 3 (P = 0.001), while in patients with asthma, ILC1s increased from baseline at Day 8 (P = 0.042). Patients with asthma had significantly higher ILC2:ILC1 ratios at baseline (P = 0.024) and Day 8 (P = 0.005). Increased ILC2:ILC1 ratio in patients with asthma correlated with clinical exacerbation severity and type 2 cytokines in nasal mucosal lining fluid. Conclusions: An ILC2-predominant inflammatory profile in patients with asthma was associated with increased severity and duration of rhinovirus infection compared with healthy subjects, supporting the potential role of ILC2s in the pathogenesis of virus-induced asthma exacerbations.

Enhanced Neutralizing Antibody Responses to Rhinovirus C and Age-Dependent Patterns of Infection.

Rationale: Rhinovirus (RV) C can cause asymptomatic infection and respiratory illnesses ranging from the common cold to severe wheezing.Objectives: To identify how age and other individual-level factors are associated with susceptibility to RV-C illnesses.Methods: Longitudinal data from the COAST (Childhood Origins of Asthma) birth cohort study were analyzed to determine relationships between age and RV-C infections. Neutralizing antibodies specific for RV-A and RV-C (three types each) were determined using a novel PCR-based assay. Data were pooled from 14 study cohorts in the United States, Finland, and Australia, and mixed-effects logistic regression was used to identify factors related to the proportion of RV-C versus RV-A detection.Measurements and Main Results: In COAST, RV-A and RV-C infections were similarly common in infancy, whereas RV-C was detected much less often than RV-A during both respiratory illnesses and scheduled surveillance visits (P < 0.001, χ2) in older children. The prevalence of neutralizing antibodies to RV-A or RV-C types was low (5-27%) at the age of 2 years, but by the age of 16 years, RV-C seropositivity was more prevalent (78% vs. 18% for RV-A; P < 0.0001). In the pooled analysis, the RV-C to RV-A detection ratio during illnesses was significantly related to age (P < 0.0001), CDHR3 genotype (P < 0.05), and wheezing illnesses (P < 0.05). Furthermore, certain RV types (e.g., C2, C11, A78, and A12) were consistently more virulent and prevalent over time.Conclusions: Knowledge of prevalent RV types, antibody responses, and populations at risk based on age and genetics may guide the development of vaccines or other novel therapies against this important respiratory pathogen.

Lung virome: New potential biomarkers for asthma severity and exacerbation.

BACKGROUND: Although some respiratory virus infections are known to contribute to the development and exacerbation of asthma, commensal viromes in airway have not been extensively studied due to technical challenges. OBJECTIVES: This study investigated the characteristics of the virome in asthmatic airways. METHODS: Both the bacteriome and virome profiles in sputum from 12 healthy individuals, 15 patients with nonsevere asthma, and 15 patients with severe asthma were analyzed and assessed for the association with clinical characteristics such as severity, exacerbation, Asthma Control Test (ACT), and lung function. RESULTS: While analysis of the 16S ribosomal RNA bacteriome in the airway showed no differences, clear contrasts in the diversity and composition of airway viromes were observed between healthy controls and patients with asthma. Herpesviruses were the most abundant type of virus in the asthma group (44.6 ± 4.6%), mainly with cytomegalovirus (CMV) and EBV accounting for 24.5 ± 3.3% and 16.9 ± 3.5%, respectively, in contrast to those in the healthy controls (5.4 ± 2.5% and 7.1 ± 3.0%, respectively). CMV and EBV were more abundant in patients with asthma who experienced exacerbation, and their abundance showed correlation with more severe asthma, lower ACT score, and lower lung function. On the contrary, bacteriophage that is abundant in healthy controls was severely reduced in patients with asthma in the order of nonsevere and severe asthma and presented significant positive correlation with ACT and FEV1/forced vital capacity. CONCLUSIONS: Lung viromes, especially, CMV, EBV, and bacteriophage may be potential biomarkers of asthma severity and exacerbation.

Rhinovirus-induced CCL17 and CCL22 in Asthma Exacerbations and Differential Regulation by STAT6.

The interplay of type-2 inflammation and antiviral immunity underpins asthma exacerbation pathogenesis. Virus infection induces type-2 inflammation-promoting chemokines CCL17 and CCL22 in asthma; however, mechanisms regulating induction are poorly understood. By using a human rhinovirus (RV) challenge model in human airway epithelial cells in vitro and mice in vivo, we assessed mechanisms regulating CCL17 and CCL22 expression. Subjects with mild to moderate asthma and healthy volunteers were experimentally infected with RV and airway CCL17 and CCL22 protein quantified. In vitro airway epithelial cell- and mouse-RV infection models were then used to define STAT6- and NF-κB-mediated regulation of CCL17 and CCL22 expression. Following RV infection, CCL17 and CCL22 expression was higher in asthma, which differentially correlated with clinical and immunological parameters. Air-liquid interface-differentiated primary epithelial cells from donors with asthma also expressed higher levels of RV-induced CCL22. RV infection boosted type-2 cytokine-induced STAT6 activation. In epithelial cells, type-2 cytokines and STAT6 activation had differential effects on chemokine expression, increasing CCL17 and suppressing CCL22, whereas NF-κB promoted expression of both chemokines. In mice, RV infection activated pulmonary STAT6, which was required for CCL17 but not CCL22 expression. STAT6-knockout mice infected with RV expressed increased levels of NF-κB-regulated chemokines, which was associated with rapid viral clearance. Therefore, RV-induced upregulation of CCL17 and CCL22 was mediated by NF-κB activation, whereas expression was differentially regulated by STAT6. Together, these findings suggest that therapeutic targeting of type-2 STAT6 activation alone will not block all inflammatory pathways during RV infection in asthma.

RSV infection potentiates TRPV1-mediated calcium transport in bronchial epithelium of asthmatic children.

The transient receptor potential vanilloid 1 (TRPV1) channel is expressed in human bronchial epithelium (HBE), where it transduces Ca2+ in response to airborne irritants. TRPV1 activation results in bronchoconstriction, cough, and mucus production, and may therefore contribute to the pathophysiology of obstructive airway disease. Since children with asthma face the greatest risk of developing virus-induced airway obstruction, we hypothesized that changes in TRPV1 expression, localization, and function in the airway epithelium may play a role in bronchiolitis and asthma in childhood. We sought to measure TRPV1 protein expression, localization, and function in HBE cells from children with versus without asthma, both at baseline and after RSV infection. We determined changes in TRPV1 protein expression, subcellular localization, and function both at baseline and after RSV infection in primary HBE cells from normal children and children with asthma. Basal TRPV1 protein expression was higher in HBE from children with versus without asthma and primarily localized to plasma membranes (PMs). During RSV infection, TRPV1 protein increased more in the PM of asthmatic HBE as compared with nonasthmatic cells. TRPV1-mediated increase in intracellular Ca2+ was greater in RSV-infected asthmatic cells, but this increase was attenuated when extracellular Ca2+ was removed. Nerve growth factor (NGF) recapitulated the effect of RSV on TRPV1 activation in HBE cells. Our data suggest that children with asthma have intrinsically hyperreactive airways due in part to higher TRPV1-mediated Ca2+ influx across epithelial membranes, and this abnormality is further exacerbated by NGF overexpression during RSV infection driving additional Ca2+ from intracellular stores.

Distinct Chronic Post-Viral Lung Diseases upon Infection with Influenza or Parainfluenza Viruses Differentially Impact Superinfection Outcome.

Chronic obstructive pulmonary disease (COPD) and asthma remain prevalent human lung diseases. Variability in epithelial and inflammatory components that results in pathologic heterogeneity complicates the development of treatments for these diseases. Early childhood infection with parainfluenza virus or respiratory syncytial virus is strongly associated with the development of asthma and COPD later in life, and exacerbations of these diseases correlate with the presence of viral RNA in the lung. Well-characterized animal models of postviral chronic lung diseases are necessary to study the underlying mechanisms of viral-related COPD and asthma and to develop appropriate therapies. In this study, we cross-analyzed chronic lung disease caused by infection with Sendai virus (SeV) or influenza A virus in mice. Differences were observed in lesion composition and inflammatory profiles between SeV- and influenza A virus-induced long-term lung disease. In addition, a primary SeV infection led to worsened pathologic findings on secondary heterologous viral challenge, whereas the reversed infection scheme protected against disease in response to a secondary viral challenge >1 month after the primary infection. These data demonstrate the differential effect of primary viral infections in the susceptibility to disease exacerbation in response to a different secondary viral infection and highlight the usefulness of these viral models as tools to understand the underlying mechanisms that mediate distinct chronic postviral lung diseases.

Respiratory syncytial virus upregulates IL-33 expression in mouse model of virus-induced inflammation exacerbation in OVA-sensitized mice and in asthmatic subjects.

BACKGROUND: Bronchial asthma (BA) is a chronic disease of the airways. The great majority of BA exacerbations are associated with respiratory viral infections. Recent findings point out a possible role of proinflammatory cytokine interleukin-33 (IL-33) in the development of atopic diseases. Although, little is known about the role of IL-33 in virus-induced BA exacerbations. METHODS: We used mouse models of RSV (respiratory syncytial virus)-induced inflammation exacerbation in OVA-sensitized mice and RSV infection alone in adult animals to characterize expression of il33 in the mouse lungs. Moreover, we studied the influence of il33 knockdown with intranasally administrated siRNA on the development of RSV-induced inflammation exacerbation. In addition, we evaluated the expression of IL33 in the ex vivo stimulated PBMCs from allergic asthma patients and healthy subjects with and without confirmed acute respiratory viral infection. RESULTS: Using mouse models, we found that infection with RSV drives enhanced il33 mRNA expression in the mouse lung. Treatment with anti-il33 siRNA diminishes airway inflammation in the lungs (we found a decrease in the number of inflammatory cells in the lungs and in the severity of histopathological alterations) of mice with RSV-induced inflammation exacerbation, but do not influence viral load. Elevated level of the IL33 mRNA was detected in ex vivo stimulated blood lymphocytes of allergic asthmatics infected with respiratory viruses. RSV and rhinovirus were the most detected viruses in volunteers with symptoms of respiratory infection. CONCLUSION: The present study provides additional evidence of the crucial role of the IL-33 in pathogenesis of RSV infection and virus-induced allergic bronchial asthma exacerbations.

Neutralization of IL-33 modifies the type 2 and type 3 inflammatory signature of viral induced asthma exacerbation.

BACKGROUND: Respiratory viral infections are one of the leading causes of need for emergency care and hospitalizations in asthmatic individuals, and airway-secreted cytokines are released within hours of viral infection to initiate these exacerbations. IL-33, specifically, contributes to these allergic exacerbations by amplifying type 2 inflammation. We hypothesized that blocking IL-33 in RSV-induced exacerbation would significantly reduce allergic inflammation. METHODS: Sensitized BALB/c mice were challenged with aerosolized ovalbumin (OVA) to establish allergic inflammation, followed by RSV-A2 infection to yield four treatment groups: saline only (Saline), RSV-infected alone (RSV), OVA alone (OVA), and OVA-treated with RSV infection (OVA-RSV). Lung outcomes included lung mRNA and protein markers of allergic inflammation, histology for mucus cell metaplasia and lung immune cell influx by cytospin and flow cytometry. RESULTS: While thymic stromal lymphopoietin (TSLP) and IL-33 were detected 6 h after RSV infection in the OVA-RSV mice, IL-23 protein was uniquely upregulated in RSV-infected mice alone. OVA-RSV animals varied from RSV- or OVA-treated mice as they had increased lung eosinophils, neutrophils, group 2 innate lymphoid cells (ILC2) and group 3 innate lymphoid cells (ILC3) detectable as early as 6 h after RSV infection. Neutralized IL-33 significantly reduced ILC2 and eosinophils, and the prototypical allergic proteins, IL-5, IL-13, CCL17 and CCL22 in OVA-RSV mice. Numbers of neutrophils and ILC3 were also reduced with anti-IL-33 treatment in both RSV and OVA-RSV treated animals as well. CONCLUSIONS: Taken together, our findings indicate a broad reduction in allergic-proinflammatory events mediated by IL-33 neutralization in RSV-induced asthma exacerbation.

Nutritional immunity: the impact of metals on lung immune cells and the airway microbiome during chronic respiratory disease.

Nutritional immunity is the sequestration of bioavailable trace metals such as iron, zinc and copper by the host to limit pathogenicity by invading microorganisms. As one of the most conserved activities of the innate immune system, limiting the availability of free trace metals by cells of the immune system serves not only to conceal these vital nutrients from invading bacteria but also operates to tightly regulate host immune cell responses and function. In the setting of chronic lung disease, the regulation of trace metals by the host is often disrupted, leading to the altered availability of these nutrients to commensal and invading opportunistic pathogenic microbes. Similarly, alterations in the uptake, secretion, turnover and redox activity of these vitally important metals has significant repercussions for immune cell function including the response to and resolution of infection. This review will discuss the intricate role of nutritional immunity in host immune cells of the lung and how changes in this fundamental process as a result of chronic lung disease may alter the airway microbiome, disease progression and the response to infection.

Asthma and severe acute respiratory syndrome coronavirus 2019: current evidence and knowledge gaps.

PURPOSE OF REVIEW: Although respiratory viruses are common triggers of asthma exacerbation, it is unknown whether this also applies to infection with SARS-CoV-2. Indeed, patients with asthma and allergy appear underrepresented in large reports of COVID-19 cases worldwide. In this review, we evaluate existing literature on this topic and potential underlying mechanisms for any interrelationship between asthma and COVID-19. RECENT FINDINGS: Data from several preclinical and clinical reports suggest a lower susceptibility for COVID-19 in patients with underlying type 2 airway inflammation including asthma that may be related to a reduced expression of ACE2 and TMPRSS2 receptors for SARS-CoV-2. Corticosteroids further decrease expression of the ACE2 and TMPRSS2 receptors, hence may also have a protective effect against infection with SARS-CoV-2. In addition, some studies suggest that the reported improvement in asthma control and a reduction in asthma exacerbations during the COVID-19 pandemic may be related to improvement in adherence to controller therapy and reduced exposure to triggers, such as other respiratory viruses and air pollutants. Recent data point towards differential susceptibility for COVID-19 among asthma patients based on their phenotype and/or endotype. On the basis of existing evidence, continuation with controller therapies is recommended for all patients with asthma. For patients with severe uncontrolled asthma infected by SARS-CoV-2, adjustment of controllers and biologics should be based on a multidisciplinary decision. SUMMARY: Underrepresentation of SARS-CoV-2-infected patients with asthma and related allergic diseases may be based on potentially protective underlying mechanisms, such as type 2 airway inflammation, downregulation of ACE2/TMPRSS2 receptors, reduced exposures to triggers and improved adherence to controller medications. Although it is imperative that control should be maintained and asthma medications be continued in all patients, management of patients with severe uncontrolled asthma infected by SARS-CoV-2 including adjustment of controllers and biologics should be discussed on an individual basis.

Dynamics of IFN-ß Responses during Respiratory Viral Infection. Insights for Therapeutic Strategies.

Rationale: Viral infections are major drivers of exacerbations and clinical burden in patients with asthma and chronic obstructive pulmonary disease (COPD). IFN-ß is a key component of the innate immune response to viral infection. To date, studies of inhaled IFN-ß treatment have not demonstrated a significant effect on asthma exacerbations.Objectives: The dynamics of exogenous IFN-ß activity were investigated to inform on future clinical indications for this potential antiviral therapy.Methods: Monocyte-derived macrophages (MDMs), alveolar macrophages, and primary bronchial epithelial cells (PBECs) were isolated from healthy control subjects and patients with COPD and infected with influenza virus either prior to or after IFN-ß stimulation. Infection levels were measured by the percentage of nucleoprotein 1-positive cells using flow cytometry. Viral RNA shedding and IFN-stimulated gene expression were measured by quantitative PCR. Production of inflammatory cytokines was measured using MSD.Measurements and Main Results: Adding IFN-ß to MDMs, alveolar macrophages, and PBECs prior to, but not after, infection reduced the percentage of nucleoprotein 1-positive cells by 85, 56, and 66%, respectively (P < 0.05). Inhibition of infection lasted for 24 hours after removal of IFN-ß and was maintained albeit reduced up to 1 week in MDMs and 72 hours in PBECs; this was similar between healthy control subjects and patients with COPD. IFN-ß did not induce inflammatory cytokine production by MDMs or PBECs but reduced influenza-induced IL-1ß production by PBECs.Conclusions:In vitro modeling of IFN-ß dynamics highlights the potential for intermittent prophylactic doses of exogenous IFN-ß to modulate viral infection. This provides important insights to aid the future design of clinical trials of IFN-ß in asthma and COPD.

Long-chain non-coding RNA n337374 relieves symptoms of respiratory syncytial virus-induced asthma by inhibiting dendritic cell maturation via the CD86 and the ERK pathway.

BACKGROUND: In this study, we investigated the relationship between long-chain non-coding RNAs (lncRNAs) and respiratory syncytial virus (RSV)-exacerbated asthma. METHODS: Transcriptome microarray was used to detect differentially expressed lncRNAs in dendritic cells (DCs) co-cultured with RSV-infected human airway epithelial cells and DCs infected with RSV. The identified downregulation of lncRNA n337374 was validated using fluorescence RT-qPCR. LncRNA n337374-overexpressing DCs and RSV-exacerbated asthmatic mouse models were established. Airway hyper-reactivity and bronchoalveolar lavage fluid (BALF) were examined, and pathological changes in lung tissues were observed in mice. Surface molecules in DCs were detected by flow cytometry and RT-qPCR and the expression of CD86 and mitogen-activated protein kinases was determined by western blot. RESULTS: In an RSV-exacerbated asthmatic mouse model, the airway wall was thickened, luminal stenosis was observed, a large number of inflammatory cells were infiltrated in the lung tissue, lung function was impaired, and counts of inflammatory cells in the BALF were increased. The overexpression of lncRNA n337374 ameliorated these pathological changes and improved impaired lung function and inflammation in an asthmatic mouse model. In DCs co-cultured with RSV-infected human airway epithelial cells, CD86 expression was promoted and ERK was markedly phosphorylated. When lncRNA n337374-overexpressing DCs were used in the co-cultures, the expression of CD86 and phosphorylated ERK was decreased. CONCLUSION: The results suggest that lncRNA n337374 overexpression may suppress DC maturation by downregulating the CD86 and ERK pathway, subsequently relieving the symptoms of RSV-induced asthma. LncRNA n337374 may be a promising target in the treatment of RSV infection-induced asthma.