Virus-induced Volatile Organic Compounds Are Detectable in Exhaled Breath during Pulmonary Infection.

Rationale: Chronic obstructive pulmonary disease (COPD) is a condition punctuated by acute exacerbations commonly triggered by viral and/or bacterial infection. Early identification of exacerbation triggers is important to guide appropriate therapy, but currently available tests are slow and imprecise. Volatile organic compounds (VOCs) can be detected in exhaled breath and have the potential to be rapid tissue-specific biomarkers of infection etiology. Objectives: To determine whether volatile organic compound measurement could distinguish viral from bacterial infection in COPD. Methods: We used serial sampling within in vitro and in vivo studies to elucidate the dynamic changes that occur in VOC production during acute respiratory viral infection. Highly sensitive gas chromatography-mass spectrometry techniques were used to measure VOC production from infected airway epithelial-cell cultures and in exhaled breath samples from healthy subjects experimentally challenged with rhinovirus (RV)-A16 and from subjects with COPD with naturally occurring exacerbations. Measurements and Main Results: We identified a novel VOC signature comprising decane and other long-chain alkane compounds that is induced during RV infection of cultured airway epithelial cells and is also increased in the exhaled breath from healthy subjects experimentally challenged with RV and from patients with COPD during naturally occurring viral exacerbations. These compounds correlated with the magnitude of antiviral immune responses, viral burden, and exacerbation severity but were not induced by bacterial infection, suggesting that they represent a specific virus-inducible signature. Conclusions: Our study highlights the potential for measurement of exhaled breath VOCs as rapid, noninvasive biomarkers of viral infection. Further studies are needed to determine whether measurement of these signatures could be used to guide more targeted therapy with antibiotic/antiviral agents for COPD 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.

Innate Immune Responses in Serum and Cerebrospinal Fluid From Neonates and Infants Infected With Parechovirus-A3 or Enteroviruses.

BACKGROUND: Parechovirus (PeV)-A3 and enteroviruses (EV) are the most common viruses causing sepsis and meningoencephalitis in neonates and young infants. Clinical manifestations of PeV-A3 infection are more severe than those of EV infection, and no pleocytosis with a positive polymerase chain reaction (PCR) result for PeV-A3 in cerebrospinal fluid (CSF) are characteristic findings. We hypothesized that innate immune responses to PeV-A3 and EV are distinct in serum and CSF. METHODS: We evaluated 22 cytokines/chemokines in serum and CSF from PeV-A3- or EV-infected patients younger than 4 months in Niigata, Japan, from 2015 through 2018. Infection was diagnosed with real-time PCR followed by sequencing. Febrile neonates and infants with sepsis-like syndrome who had negative bacterial culture and viral PCR for both PeV-A and EV were also included (non-PeV-A/EV patients). RESULTS: Among 192 febrile patients, we evaluated 16 PeV-A3-infected, 15 EV-infected, and 8 non-PeV-A/EV patients. Serum pro-/anti-inflammatory cytokine/chemokine levels were higher in PeV-A3-infected patients than in EV-infected patients (P < .02). Although most cytokine/chemokine were elevated in CSF from EV-infected patients, levels were low or undetectable in PeV-A3-infected and non-PeV-A/EV patients (P < .001). CONCLUSIONS: Distinct cytokine/chemokine patterns in serum and CSF may explain the different clinical manifestations of PeV-A3-infected and EV-infected neonates and young infants.

The impact of viral bronchiolitis phenotyping: Is it time to consider phenotype-specific responses to individualize pharmacological management?

Although recent guidelines recommend a minimalist approach to bronchiolitis, there are several issues with this posture. First, there are concerns about the definition of the disease, the quality of the guidelines, the method of administration of bronchodilators, and the availability of tools to evaluate the response to therapies. Second, for decades it has been assumed that all cases of viral bronchiolitis are the same, but recent evidence has shown that this is not the case. Distinct bronchiolitis phenotypes have been described, with heterogeneity in clinical presentation, molecular immune signatures and clinically relevant outcomes such as respiratory failure and recurrent wheezing. New research is critically needed to refine viral bronchiolitis phenotyping at the molecular and clinical levels as well as to define phenotype-specific responses to different therapeutic options.

Time-course of upper respiratory tract viral infection and COPD exacerbation.

Viral respiratory tract infections have been implicated as the predominant risk factor for acute exacerbations of chronic obstructive pulmonary disease (AECOPD). We aimed to evaluate, longitudinally, the association between upper respiratory tract infections (URTI) caused by viruses and AECOPD.Detection of 18 viruses was performed in naso- and orοpharyngeal swabs from 450 COPD patients (Global Initiative for Chronic Obstructive Lung Disease stages 2-4) who were followed for a mean of 27 months. Swabs were taken during stable periods (n=1909), at URTI onset (n=391), 10 days after the URTI (n=356) and during an AECOPD (n=177) and tested using a multiplex nucleic acid amplification test.Evidence of at least one respiratory virus was significantly higher at URTI onset (52.7%), 10 days after the URTI (15.2%) and during an AECOPD (38.4%), compared with the stable period (5.3%, p<0.001). During stable visits, rhinovirus accounted for 54.2% of all viral infections, followed by coronavirus (20.5%). None of the viruses were identified in two consecutive stable visits. Patients with a viral infection at URTI onset did not have a higher incidence of exacerbation than patients without viral infection (p=0.993). Τhe incidence of any viral infection during an AECOPD was similar between URTI-related AECOPD and non-URTI-related AECOPD (p=0.359). Only 24% of the patients that had a URTI-related AECOPD had the same virus at URTI onset and during an AECOPD. Detection of parainfluenza 3 at URTI onset was associated with a higher risk of an AECOPD (p=0.003). Rhinovirus and coronavirus were the most frequently detected viruses during AECOPD visits, accounting for 35.7% and 25.9% of all viral infections, respectively.The prevalence of viral infection during the stable period of COPD was low. The risk of exacerbation following the onset of URTI symptoms depends on the particular virus associated with the event and was significant only for parainfluenza 3.

Human parechovirus meningitis and gross-motor neurodevelopment in young children.

This multicenter prospective cohort study describes the impact of human parechovirus meningitis on gross-motor neurodevelopment of young children. Gross-motor function was measured using Alberta Infant Motor Scale. Of a total of 38 eligible children < 10 months of age at onset, nine cases had clinical evidence of meningitis and polymerase chain reaction positive for human parechovirus in cerebrospinal fluid; 11 had no meningitis and polymerase chain reaction positive for human parechovirus in nasopharyngeal aspirate, blood, urine, or feces; and in 18, no pathogen was identified (reference group).The children with human parechovirus meningitis showed more frequent albeit not statistically significant suspect gross-motor function delay (mean Z-score (standard deviation) - 1.69 (1.05)) than children with human parechovirus infection-elsewhere (- 1.38 (1.51)). The reference group did not fall in the range of suspect gross-motor function delay (- 0.96 (1.07)). Adjustment for age at onset and maternal education did not alter the results.Conclusion: Six months after infection, children with human parechovirus meningitis showed more frequent albeit not statistically significant suspect gross-motor function delay compared to the population norm and other two groups. Longitudinal studies in larger samples and longer follow-up periods are needed to confirm the impact and persistence of human parechovirus meningitis on neurodevelopment in young children. What is Known: • Human parechovirus is progressively becoming a major viral cause of meningitis in children. • There is keen interest in the development of affected infants with human parechovirus meningitis. What is New: • This study describes prospectively gross-motor functional delay in children with both clinical evidence of meningitis and polymerase chain reaction positive for human parechovirus in cerebrospinal fluid. • It shows the importance of screening young children for developmental delay in order to refer those with delay for early intervention to maximize their developmental potential.

Enterovirus and parechovirus infections in children: differences in clinical presentation, mechanisms for meningitis without pleocytosis and mechanisms involved in the neurological outcome.

Enterovirus (EV) and Parechovirus (HPeV) are a frequent cause of infection in children. This review gives an overview of possible causes for differences in clinical presentation. EV and HPeV can cause a meningitis with or without pleocytosis. Different possible mechanisms for meningitis without pleocytosis are given. Little is known about the prognosis and long-term effects of EV and HPeV meningitis in children. Only some studies with a small number of children with EV or HPeV meningitis are reported. The different possible mechanisms involved in the neurological outcome after EV or HPeV meningitis will be discussed.

Parechovirus and enterovirus infections in neonates.

BACKGROUND: Parechovirus and enterovirus belong to a family of Picornaviridae, non- enveloped, small-sized RNA viruses, responsible for multiple human diseases. Recent introduction of molecular tests enabled the identi cation of parechovirus and enterovirus infections. Our aim was a retrospective analysis of signs and symptoms associated with confirmed parechovirus or enterovirus infections among children treated in the Department of Neonatology, St. Louis Regional Children's Hospital in Kraków, Poland. METHODS: Based on laboratory records, we identified all cases of parecho- or enterovirus infections confirmed by identification of viral RNA in nasal swab or cerebrospinal fluid samples. Hospital records and laboratory tests results of selected patients were then analyzed, and selected data were summarized, with emphasis on clinical and laboratory findings at admission. RESULTS: We identified 11 cases of parechovirus and three of enterovirus infections. All cases were neonates admitted to hospital with fever and irritability. Except for leukopenia in 50% of patients, no significant abnormalities were noted in blood counts and serum biochemistry, including low C-reactive protein and procalcitonin. In nine cases, cerebrospinal fluid was collected, the fluid protein concentrations and cell counts were moderately increased. Final diagnosis was meningitis in 12 children, and other viral infections in two. CONCLUSIONS: Viral infection, including parecho- and enteroviruses, should be considered in the etiology of fever and meningitis in neonates. The available molecular tests allow for detection of viral genetic material even in a scant biological specimen collected from neonates.

RSV vs. rhinovirus bronchiolitis: difference in nasal airway microRNA profiles and NFκB signaling.

BackgroundAlthough rhinovirus infection is associated with increased risks of acute and chronic respiratory outcomes during childhood compared with respiratory syncytial virus (RSV), the underlying mechanisms remain unclear. We aimed to determine the differences in nasal airway microRNA profiles and their downstream effects between infants with rhinovirus and RSV bronchiolitis.MethodsAs part of a multicenter cohort study of infants hospitalized for bronchiolitis, we examined nasal samples obtained from 16 infants with rhinovirus and 16 infants with RSV. We tested nasal airway samples using microarrays to profile global microRNA expression and determine the predicted regulation of targeted transcripts. We also measured gene expression and cytokines for NFκB pathway components.ResultsBetween the virus groups, 386 microRNAs were differentially expressed (false discovery rate (FDR)<0.05). In infants with rhinovirus, the NFκB pathway was highly ranked as a predicted target for these differentially expressed microRNAs compared with RSV. Pathway analysis using measured mRNA expression data validated that rhinovirus infection had upregulation of NFκB family (RelA and NFκB2) and downregulation of inhibitor κB family. Infants with rhinovirus had higher levels of NFκB-induced type-2 cytokines (IL-10 and IL-13; FDR<0.01).ConclusionIn infants with bronchiolitis, rhinovirus and RSV infections had different nasal airway microRNA profiles associated with NFκB signaling.

Myocarditis Caused by Human Parechovirus in Adult.

The infectious etiology of myocarditis often remains unidentified. We report a case of myocarditis associated with human parechovirus (HPeV) infection in an adult. HPeV is an emerging pathogen that can cause serious illness, including myocarditis, in adults. Testing for HPeV should be considered in differential diagnosis of myocarditis.

The main rhinovirus respiratory tract adhesion site (ICAM-1) is upregulated in smokers and patients with chronic airflow limitation (CAL).

BACKGROUND: ICAM-1 is a major receptor for ~60% of human rhinoviruses, and non-typeable Haemophilus influenzae, two major pathogens in COPD. Increased cell-surface expression of ICAM-1 in response to tobacco smoke exposure has been suggested. We have investigated epithelial ICAM-1 expression in both the large and small airways, and lung parenchyma in smoking-related chronic airflow limitation (CAL) patients. METHODS: We evaluated epithelial ICAM-1 expression in resected lung tissue: 8 smokers with normal spirometry (NLFS); 29 CAL patients (10 small-airway disease; 9 COPD-smokers; 10 COPD ex-smokers); Controls (NC): 15 normal airway/lung tissues. Immunostaining with anti-ICAM-1 monoclonal antibody was quantified with computerized image analysis. The percent and type of cells expressing ICAM-1 in large and small airway epithelium and parenchyma were enumerated, plus percentage of epithelial goblet and submucosal glands positive for ICAM- 1. RESULTS: A major increase in ICAM-1 expression in epithelial cells was found in both large (p < 0.006) and small airways (p < 0.004) of CAL subjects compared to NC, with NLFS being intermediate. In the CAL group, both basal and luminal areas stained heavily for ICAM-1, so did goblet cells and sub-mucosal glands, however in either NC or NLFS subjects, only epithelial cell luminal surfaces stained. ICAM-1 expression on alveolar pneumocytes (mainly type II) was slightly increased in CAL and NLFS (p < 0.01). Pack-years of smoking correlated with ICAM-1 expression (r = 0.49; p < 0.03). CONCLUSION: Airway ICAM-1 expression is markedly upregulated in CAL group, which could be crucial in rhinoviral and NTHi infections. The parenchymal ICAM-1 is affected by smoking, with no further enhancement in CAL subjects.

Triatoma virus recombinant VP4 protein induces membrane permeability through dynamic pores.

UNLABELLED: In naked viruses, membrane breaching is a key step that must be performed for genome transfer into the target cells. Despite its importance, the mechanisms behind this process remain poorly understood. The small protein VP4, encoded by the genomes of most viruses of the order Picornavirales, has been shown to be involved in membrane alterations. Here we analyzed the permeabilization activity of the natively nonmyristoylated VP4 protein from triatoma virus (TrV), a virus belonging to the Dicistroviridae family within the Picornavirales order. The VP4 protein was produced as a C-terminal maltose binding protein (MBP) fusion to achieve its successful expression. This recombinant VP4 protein is able to produce membrane permeabilization in model membranes in a membrane composition-dependent manner. The induced permeability was also influenced by the pH, being greater at higher pH values. We demonstrate that the permeabilization activity elicited by the protein occurs through discrete pores that are inserted on the membrane. Sizing experiments using fluorescent dextrans, cryo-electron microscopy imaging, and other, additional techniques showed that recombinant VP4 forms heterogeneous proteolipidic pores rather than common proteinaceous channels. These results suggest that the VP4 protein may be involved in the membrane alterations required for genome transfer or cell entry steps during dicistrovirus infection. IMPORTANCE: During viral infection, viruses need to overcome the membrane barrier in order to enter the cell and replicate their genome. In nonenveloped viruses membrane fusion is not possible, and hence, other mechanisms are implemented. Among other proteins, like the capsid-forming proteins and the proteins required for viral replication, several viruses of the order Picornaviridae contain a small protein called VP4 that has been shown to be involved in membrane alterations. Here we show that the triatoma virus VP4 protein is able to produce membrane permeabilization in model membranes by the formation of heterogeneous dynamic pores. These pores formed by VP4 may be involved in the genome transfer or cell entry steps during viral infection.

Incidence and Clinical Course of Respiratory Viral Coinfections in Children Aged 0-59 Months.

Clinical data available on coinfections are contradictory concerning both the number of viruses involved and the severity of the condition. A total of 114 patients aged 0-59 months with symptoms of respiratory tract infection were enrolled into the study. Nasal and pharyngeal swabs were tested using the PCR method for the following 12 viruses: influenza A, influenza B, respiratory syncytial virus A (RSV A), respiratory syncytial virus B (RSV B), adenovirus, metapneumovirus, coronavirus 229E/NL63 (hCoV229), coronavirus OC43 (hCoVOC43), parainfluenza virus 1 (PIV-1), parainfluenza virus 2 (PIV-2), parainfluenza virus 3 (PIV-3), and rhinovirus A/B. Coinfections were detected in nine (8 %) patients. Five of the coinfections were related to influenza A (H3N2) virus associated with the following other, single or combined, respiratory viruses: influenza B in one case, hCoV229 in two cases, hCoV229, RSV A, and PIV-2 in one case, and PIV-1, PIV-2, RSV A, RSV B, and adenovirus in one case. The other four coinfections were caused by: adenovirus and hCoVOC43, adenovirus, and rhinovirus, RSV A and PIV-1, influenza B, and RSV B. We did not observe any significant differences in the clinical course of infections caused either by a single or multiple viral factors.

Short- and long-term efficacy of prednisolone for first acute rhinovirus-induced wheezing episode.

BACKGROUND: Rhinovirus-induced wheezing is an important risk factor for recurrent wheezing. There are no randomized controlled trials on the effect of systemic corticosteroids in patients with this disease. OBJECTIVE: We sought to study the short- and long-term effects of prednisolone treatment of the first acute, moderate-to-severe, rhinovirus-induced wheezing episode in young children. METHODS: After confirming rhinovirus from nasopharyngeal aspirate by using PCR, 79 children with a first wheezing episode at age 3 to 23 months were randomized to receive oral prednisolone (first dose of 2 mg/kg, followed by 2 mg/kg/d in 2 divided doses for 3 days) or placebo. The trial was double blind throughout the 12-month follow-up. The primary outcomes were long term: new physician-confirmed wheezing episode within 2 months, number of physician-confirmed wheezing episodes within 12 months, and initiation of regular controller medication for asthma symptoms within 12 months. The primary interaction analysis examined rhinovirus load. RESULTS: Seventy-four patients completed the study (mean age, 13 months; 28% atopic). Long-term outcomes did not differ between groups (all P ≥ .30). For short-term outcomes, the prednisolone group had less cough, rhinitis, noisy breathing, severe breathing difficulties, and nocturnal respiratory symptoms at home within 2 weeks (all P < .05). The 25 children with greater than 7000 rhinovirus copies/mL (most sensitive cutoff) benefitted from prednisolone in terms of less risk of physician-confirmed recurrence within 2 and 12 months compared with placebo (both P < .05). CONCLUSIONS: Prednisolone cannot be routinely recommended for all young children experiencing their first acute, moderate-to-severe, rhinovirus-induced wheezing episode. Prednisolone might be beneficial in a subgroup of children with high viral loads.

Rhinoviruses significantly affect day-to-day respiratory symptoms of children with asthma.

BACKGROUND: Viruses are frequently associated with acute exacerbations of asthma, but the extent to which they contribute to the level of day-to-day symptom control is less clear. OBJECTIVE: We sought to explore the relationship between viral infections, host and environmental factors, and respiratory symptoms in children. METHODS: Sixty-seven asthmatic children collected samples twice weekly for an average of 10 weeks. These included nasal wash fluid and exhaled breath for PCR-based detection of viral RNA, lung function measurements, and records of medication use and asthma and respiratory symptoms in the previous 3 days. Atopy, mite allergen exposure, and vitamin D levels were also measured. Mixed-model regression analyses were performed. RESULTS: Human rhinoviruses (hRVs) were detected in 25.5% of 1232 nasal samples and 11.5% of breath samples. Non-hRV viruses were detected in less than 3% of samples. hRV in nasal samples was associated with asthma symptoms (cough and phlegm: odds ratio = 2.0; 95% CI = 1.4-2.86, P = .0001; wheeze and chest tightness: odds ratio = 2.34, 95% CI = 1.55-3.52, P < .0001) and with cold symptoms, as reported concurrently with sampling and 3 to 4 days later. No differences were found between the 3 hRV genotypes (hRV-A, hRV-B, and hRV-C) in symptom risk. A history of inhaled corticosteroid use, but not atopic status, mite allergen exposure, or vitamin D levels, modified the association between viruses and asthma symptoms. CONCLUSION: The detection of nasal hRV was associated with a significantly increased risk of day-to-day asthma symptoms in children. Host, virus genotype, and environmental factors each had only a small or no effect on the relationship of viral infections to asthma symptoms.

Infantile respiratory syncytial virus and human rhinovirus infections: respective role in inception and persistence of wheezing.

There is evidence that respiratory viruses play a key role in the development and exacerbation of obstructive respiratory diseases in children. This review attempts to juxtapose the separate profiles and prototypes of pathogenetic mechanisms represented by the two most common amongst such viruses: respiratory syncytial virus (RSV) and human rhinovirus (HRV). RSV represents the most common agent of severe airway disease in infants and young children, and is predominant in winter months. Large epidemiological studies have revealed an unequivocal relationship between RSV infection and subsequent wheezing into childhood, thought to be related to long-term changes in neuroimmune control of the airways rather than allergic sensitisation. HRV is a highly diverse group of viruses that affect subjects of all ages, is ubiquitous and occurs year-round. In contrast to RSV, infections with HRV cause minimal cytotoxicity but induce a rapid production of cytokines and chemokines with amplification of the inflammatory response. The susceptibility to HRV-induced bronchiolitis and subsequent wheezing appears to be linked to individual predisposition since it is often associated with a family or personal history of asthma/atopy. Thus, RSV probably serves as an "inducer" rather than a "trigger". Conversely, HRVs seem to serve as a "trigger" rather than an "inducer" in predisposed individuals.

Effects of an anti-inflammatory VAP-1/SSAO inhibitor, PXS-4728A, on pulmonary neutrophil migration.

BACKGROUND AND PURPOSE: The persistent influx of neutrophils into the lung and subsequent tissue damage are characteristics of COPD, cystic fibrosis and acute lung inflammation. VAP-1/SSAO is an endothelial bound adhesion molecule with amine oxidase activity that is reported to be involved in neutrophil egress from the microvasculature during inflammation. This study explored the role of VAP-1/SSAO in neutrophilic lung mediated diseases and examined the therapeutic potential of the selective inhibitor PXS-4728A. METHODS: Mice treated with PXS-4728A underwent intra-vital microscopy visualization of the cremaster muscle upon CXCL1/KC stimulation. LPS inflammation, Klebsiella pneumoniae infection, cecal ligation and puncture as well as rhinovirus exacerbated asthma models were also assessed using PXS-4728A. RESULTS: Selective VAP-1/SSAO inhibition by PXS-4728A diminished leukocyte rolling and adherence induced by CXCL1/KC. Inhibition of VAP-1/SSAO also dampened the migration of neutrophils to the lungs in response to LPS, Klebsiella pneumoniae lung infection and CLP induced sepsis; whilst still allowing for normal neutrophil defense function, resulting in increased survival. The functional effects of this inhibition were demonstrated in the RV exacerbated asthma model, with a reduction in cellular infiltrate correlating with a reduction in airways hyperractivity. CONCLUSIONS AND IMPLICATIONS: This study demonstrates that the endothelial cell ligand VAP-1/SSAO contributes to the migration of neutrophils during acute lung inflammation, pulmonary infection and airway hyperractivity. These results highlight the potential of inhibiting of VAP-1/SSAO enzymatic function, by PXS-4728A, as a novel therapeutic approach in lung diseases that are characterized by neutrophilic pattern of inflammation.

Utility of animal and in vivo experimental infection of humans with rhinoviruses in the development of therapeutic agents for viral exacerbations of asthma and chronic obstructive pulmonary disease.

There is an association with acute viral infection of the respiratory tract and exacerbations of asthma and chronic obstructive pulmonary disease (COPD). Although these exacerbations are associated with several types of viruses, human rhinoviruses (HRVs) are associated with the vast majority of disease exacerbations. Due to the lack of an animal species that is naturally permissive for HRVs to use as a facile model system, and the limitations associated with animal models of asthma and COPD, studies of controlled experimental infection of humans with HRVs have been used and conducted safely for decades. This review discusses how these experimental infection studies with HRVs have provided a means of understanding the pathophysiology underlying virus-induced exacerbations of asthma and COPD with the goal of developing agents for their prevention and treatment.

IL-33-dependent type 2 inflammation during rhinovirus-induced asthma exacerbations in vivo.

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

Human rhinovirus infection during naturally occurring COPD exacerbations.

Human rhinovirus (HRV) infection is an important trigger of exacerbations of chronic obstructive pulmonary disease (COPD) but its role in determining exacerbation frequency phenotype or the time-course of HRV infection in naturally occurring exacerbations is unknown. Sputum samples from 77 patients were analysed by real-time quantitative PCR for both HRV (388 samples), and Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis (89 samples). Patients recorded worsening of respiratory symptoms on daily diary cards, from which exacerbations were identified. HRV prevalence and load at exacerbation presentation were significantly higher than in the stable state (prevalence 53.3% versus 17.2%, respectively; p<0.001) but 0% by day 35 post-exacerbation. HRV load was higher in patients with cold symptoms (p=0.046) or sore throats (p=0.006) than those without. 73% of bacterium-negative but HRV-positive exacerbations were bacterium-positive by day 14. Patients with HRV detected at exacerbation had a higher exacerbation frequency (interquartile range) of 3.01 (2.02-5.30) per year compared with patients without HRV (2.51 (2.00-3.51)) (p=0.038). HRV prevalence and load increased at COPD exacerbation, and resolved during recovery. Frequent exacerbators were more likely to experience HRV infection. Secondary bacterial infection is common after HRV infection, and provides a possible mechanism for exacerbation recurrence and a potential target for novel therapies.