Comparison of rhinovirus antibody titers in children with asthma exacerbations and species-specific rhinovirus infection

Personal Network Inference Unveils Heterogeneous Immune Response Patterns to Viral Infection in Children with Acute Wheezing

Human rhinovirus (RV)-induced exacerbations of asthma and wheeze are a major cause of emergency room presentations and hospital admissions among children. Previous studies have shown that immune response patterns during these exacerbations are heterogeneous and are characterized by the presence or absence of robust interferon responses. Molecular phenotypes of asthma are usually identified by cluster analysis of gene expression levels. This approach however is limited, since genes do not exist in isolation, but rather work together in networks. Here, we employed personal network inference to characterize exacerbation response patterns and unveil molecular phenotypes based on variations in network structure. We found that personal gene network patterns were dominated by two major network structures, consisting of interferon-response versus FCER1G-associated networks. Cluster analysis of these structures divided children into subgroups, differing in the prevalence of atopy but not RV species. These network structures were also observed in an independent cohort of children with virus-induced asthma exacerbations sampled over a time course, where we showed that the FCER1G-associated networks were mainly observed at late time points (days four-six) during the acute illness. The ratio of interferon- and FCER1G-associated gene network responses was able to predict recurrence, with low interferon being associated with increased risk of readmission. These findings demonstrate the applicability of personal network inference for biomarker discovery and therapeutic target identification in the context of acute asthma which focuses on variations in network structure.

Defining Age-specific Relationships of Respiratory Syncytial Virus and Rhinovirus Species in Hospitalized Children With Acute Wheeze

BACKGROUND

Acute wheezing is one of the most common hospital presentations for young children. Respiratory syncytial virus (RSV) and rhinovirus (RV) species A, B and the more recently described species C are implicated in the majority of these presentations. However, the relative importance and age-specificities of these viruses have not been defined. Hence, this study aimed to establish these relationships in a large cohort of prospectively recruited hospitalized children.

METHODS

The study cohort was 390 children 0-16 years of age presenting with acute wheezing to a children's emergency department, 96.4% being admitted. A nonwheezing control population of 190 was also recruited. Nasal samples were analyzed for viruses.

RESULTS

For the first 6 months of life, RSV was the dominant virus associated with wheezing (P < 0.001). From 6 months to 2 years, RSV, RV-A and RV-C were all common but none predominated. From 2 to 6 years, RV-C was the dominant virus detected (50-60% of cases), 2-3 times more common than RV-A and RSV, RSV decreasing to be absent from 4 to 7 years. RV-B was rare at all ages. RV-C was no longer dominant in children more than 10 years of age. Overall, RV-C was associated with lower mean oxygen saturation than any other virus (P < 0.001). Controls had no clear age distribution of viruses.

CONCLUSION

This study establishes a clear profile of age specificity of virus infections causing moderate to severe wheezing in children: RSV as the dominant cause in the first 6 months and RV-C in preschool-age children.

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.

Differential Gene Expression of Lymphocytes Stimulated with Rhinovirus A and C in Children with Asthma

Rationale: Individuals with asthma have heightened antibody responses to rhinoviruses (RVs), although those specific for RV-C are lower than responses specific for RV-A, suggesting poor immunity to this species.Objectives: To ascertain and compare T-cell memory responses induced by RV-A and RV-C in children with and without asthma.Methods: Peripheral blood mononuclear cells from 17 children with asthma and 19 control subjects without asthma were stimulated in vitro with peptide formulations to induce representative species-specific responses to RV-A and RV-C. Molecular profiling (RNA sequencing) was used to identify enriched pathways and upstream regulators.Measurements and Main Results: Responses to RV-A showed higher expression of IFNG and STAT1 compared with RV-C, and significant expression of CXCL9, 10, and 11 was not found for RV-C. There was no reciprocal increase of T-helper cell type 2 (Th2) cytokine genes or the Th2 chemokine genes CCL11, CCL17, and CCL22. RV-C induced higher expression of CCL24 (eotaxin-2) than RV-A in the responses of children with and without asthma. Upstream regulator analysis showed both RV-A and, although to a lesser extent, RV-C induced predominant Th1 and inflammatory cytokine expression. The responses of children with asthma compared with those without asthma were lower for both RV-A and RV-C while retaining the pattern of gene expression and upstream regulators characteristic of each species. All groups showed activation of the IL-17A pathway.Conclusions: RV-C induced memory cells with a lower IFN-γ-type response than RV-A without T-helper cell type 2 (Th2) upregulation. Children with asthma had lower recall responses than those without asthma while largely retaining the same gene activation profile for each species. RV-A and RV-C, therefore, induce qualitatively different T-cell responses.

Multiplexed High-Throughput Serological Assay for Human Enteroviruses

Immunological assays detecting antibodies against enteroviruses typically use a single enterovirus serotype as antigen. This limits the ability of such assays to detect antibodies against different enterovirus types and to detect possible type-specific variation in antibody responses. We set out to develop a multiplexed assay for simultaneous detection of antibodies against multiple enterovirus and rhinovirus types encompassing all human infecting species. Seven recombinant VP1 proteins from enteroviruses EV-A to EV-D and rhinoviruses RV-A to RV-C species were produced. Using Meso Scale Diagnostics U-PLEX platform we were able to study antibody reactions against these proteins as well as non-structural enterovirus proteins in a single well with 140 human serum samples. Adults had on average 33-fold stronger antibody responses to these antigens (p < 10⁻¹¹) compared to children, but children had less cross-reactivity between different enterovirus types. The results suggest that this new high-throughput assay offers clear benefits in the evaluation of humoral enterovirus immunity in children, giving more exact information than assays that are based on a single enterovirus type as antigen.

Rhinovirus Species-Specific Antibodies Differentially Reflect Clinical Outcomes in Health and Asthma

Rationale: Rhinoviruses (RVs) are major triggers of common cold and acute asthma exacerbations. RV species A, B, and C may have distinct clinical impact; however, little is known regarding RV species-specific antibody responses in health and asthma.Objectives: To describe and compare total and RV species-specific antibody levels in healthy children and children with asthma, away from an acute event.Methods: Serum samples from 163 preschool children with mild to moderate asthma and 72 healthy control subjects from the multinational Predicta cohort were analyzed using the recently developed PreDicta RV antibody chip.Measurements and Main Results: RV antibody levels varied, with RV-C and RV-A being higher than RV-B in both groups. Compared with control subjects, asthma was characterized by significantly higher levels of antibodies to RV-A and RV-C, but not RV-B. RV antibody levels positively correlated with the number of common colds over the previous year in healthy children, and wheeze episodes in children with asthma. Antibody levels also positively correlated with asthma severity but not with current asthma control.Conclusions: The variable humoral response to RV species in both groups suggests a differential infectivity pattern between RV species. In healthy preschoolers, RV antibodies accumulate with colds. In asthma, RV-A and RV-C antibodies are much higher and further increase with disease severity and wheeze episodes. Higher antibody levels in asthma may be caused by a compromised innate immune response, leading to increased exposure of the adaptive immune response to the virus. Importantly, there is no apparent protection with increasing levels of antibodies.

Prevalence of viral respiratory infections amongst asthmatics: Results of a meta-regression analysis

Viral respiratory infections (VRI) can act as triggers for acute asthma exacerbations and contribute significantly to asthma-related healthcare costs. Knowing the patterns of viruses amongst asthmatics can be useful in treating and preventing these exacerbations and help decrease the burden they impose on patients and healthcare systems. We aimed to quantify the viral prevalence in asthmatics presenting with exacerbations and identify influencing factors. A meta-analysis with a systematic search was conducted. Random-effect analysis was performed to quantify prevalence of viruses. A meta-regression was conducted to explain sources of heterogeneity and identify confounding factors. A VRI was detected in 52%-65% of the cases, and the detection rate was higher in children compared to adults. Rhinovirus was most often detected [51-71%], followed by respiratory syncytial virus [8-18%], influenza virus [7-15%], human parainfluenza virus [4-11%] and metapneumovirus virus [3-9%]. Meta-regression showed that the variables age and hemisphere contributed to the heterogeneity observed and were significantly associated with the detection of viruses in asthmatics. The climate variable reached significance for RSV and indicated a higher detection rate of viruses in asthmatics living in temperate compared to tropical regions. Besides age, geographic location and related variables significantly influence to what extent respiratory viruses are detected amongst asthmatics with exacerbations. Our results indicate that health authorities should adopt region- and population specific prevention and treatment strategies. Prevention and detection of viral respiratory infections in asthmatics could reduce asthma related disease burden and decrease antibiotic misuse.

T-bet+ Memory B Cells Link to Local Cross-Reactive IgG upon Human Rhinovirus Infection

Human rhinoviruses cause the common cold and exacerbate chronic respiratory diseases. Although infection elicits neutralizing antibodies, these do not persist or cross-protect across multiple rhinovirus strains. To analyze rhinovirus-specific B cell responses in humans, we developed techniques using intact RV-A16 and RV-A39 for high-throughput high-dimensional single-cell analysis, with parallel assessment of antibody isotypes in an experimental infection model. Our approach identified T-bet+ B cells binding both viruses that account for ∼5% of CXCR5- memory B cells. These B cells infiltrate nasal tissue and expand in the blood after infection. Their rapid secretion of heterotypic immunoglobulin G (IgG) in vitro, but not IgA, matches the nasal antibody profile post-infection. By contrast, CXCR5+ memory B cells binding a single virus are clonally distinct, absent in nasal tissue, and secrete homotypic IgG and IgA, mirroring the systemic response. Temporal and spatial functions of dichotomous memory B cells might explain the ability to resolve infection while rendering the host susceptible to re-infection.

Rhinovirus species and tonsillar immune responses

Background

Rhinovirus A and C infections are important contributors to asthma induction and exacerbations. No data exist on the interaction of local immune responses in rhinovirus infection. Therefore, we aimed to determine the tonsillar immune responses according to rhinovirus A, B and C infections.

Methods

We collected tonsillar samples, nasopharyngeal aspirates and peripheral blood from 42 rhinovirus positive tonsillectomy patients. Fifteen respiratory viruses or their types were investigated from nasopharynx and tonsil tissue, and rhinovirus species were typed. The expression of 10 cytokines and 4 transcription factors (IFN-α, IFN-β, IFN-γ, IL-10, IL-13, IL-17, IL-28, IL-29, IL-37, TGF-β, FOXP3, GATA3, RORC2 and Tbet) were studied from tonsil tissue by quantitative PCR. A standard questionnaire of respiratory symptoms and health was filled by the patient or his/her guardian. The patients were divided into three groups by the determination of rhinovirus species.

Results

Overall, 16 patients had rhinovirus A, 12 rhinovirus B and 14 rhinovirus C infection. In rhinovirus B positive group there were significantly less men (P = 0.0072), less operated in spring (P = 0.0096) and more operated in fall (P = 0.030) than in rhinovirus A or C groups. Rhinovirus A positive patients had more respiratory symptoms (P = 0.0074) and particularly rhinitis (P = 0.036) on the operation day. There were no significant differences between the groups in virus codetection. In adjusted analysis, rhinovirus C infections were associated with increased IFN-α (P = 0.045) and decreased RORC2 expression (P = 0.025).

Conclusions

Rhinovirus species associated differently with clinical characteristics and tonsillar cytokine responses.

Serum IgG Concentrations in Adult Patients Experiencing Virus-Induced Severe Asthma Exacerbations

BACKGROUND

Patients experiencing severe asthma exacerbations have a poorer quality of life and an increase in morbidity and mortality. Viruses are frequently involved in asthma exacerbations.

OBJECTIVE

To determine the value of measuring serum IgG concentrations in asthma exacerbations and assess their link with viral infections in patients hospitalized for asthma.

METHODS

Patients hospitalized for asthma exacerbation were included in an observational study from January 1, 2015, to December 31, 2015. Serum IgG concentrations on admission were compared between patients with a positive upper airway viral sample and those with a negative viral sample.

RESULTS

Among the 82 patients included, those with positive viral nasopharyngeal samples (n = 40) presented with lower serum IgG concentrations during exacerbation than those with a negative viral sample (n = 42) (10.1 ± 2.3 g/L vs 11.5 ± 3.6 g/L; P < .05). The median concentration of serum IgG was lower in patients hospitalized for more than 3 days compared with those hospitalized for less than 3 days (10.0 g/L [8.2-12.4] vs 11.4 g/L [10.1-12.8]; P < .05) and in patients who received oral corticosteroid therapy for more than 5 days compared with those treated with oral steroids for less than 5 days (10.1 g/L [8.3-12.2] vs 11.6 g/L [10.0-13.8]; P < .05).

CONCLUSIONS

Serum IgG level was significantly lower when asthma exacerbations were associated with positive viral samples. The patients with lower serum IgG concentrations required longer hospitalizations and longer courses of steroids.

High correlation between human rhinovirus type C and children with asthma exacerbations in Taiwan

BACKGROUND/PURPOSES

Human rhinovirus type C (HRV-C) has been associated with asthma exacerbation (AE) in children in several countries. However, in Taiwan the association between HRV, especially HRV-C, and AE in children has yet to be elucidated. We sought to investigate the prevalence of respiratory viruses in children with acute lower respiratory tract infection (ALRTI) in Taiwan and the association between different types of HRV and AE in children.

METHODS

This prospective study was conducted from 2011 to 2013, and enrolled children with ALRTI, including an asthma exacerbation group (AE; n = 28) and a Non-asthma group (n = 66). Viruses were detected by culture, reverse transcription-polymerase chain reaction, and molecular sequencing of nasopharyngeal swabs.

RESULTS

The prevalence of identified respiratory viruses was 78.6% in the AE group and 65.2% in the Non-asthma group. The prevalence rates of HRV and HRV-C were significantly higher in the AE group than in the Non-asthma group (67.9% vs. 33.3% in HRV, p = 0.002; and 50% vs. 15.2% in HRV-C, p < 0.001). Among the children with HRV, the prevalence of HRV-C (68.4%) was higher than that of the other types of HRV (31.6%, including HRV-A 26.3%, and HRV-B 5.3%) in the AE group but not in the Non-asthma group (40.9% vs. 59.1%).

CONCLUSIONS

HRV is the most predominant viral infection responsible for pediatric AE in Taiwan, and HRV-C is responsible for more of these exacerbations than HRV-A or HRV-B.

Mutius E, Kopp MV. Rhinovirus infections change DNA methylation and mRNA expression in children with asthma

Human rhinovirus infection (HRVI) plays an important role in asthma exacerbations and is thought to be involved in asthma development during early childhood. We hypothesized that HRVI causes differential DNA methylation and subsequently differential mRNA expression in epithelial cells of children with asthma. Primary nasal epithelial cells from children with (n = 10) and without (n = 10) asthma were cultivated up to passage two and infected with Rhinovirus-16 (RV-16). HRVI-induced genome-wide differences of DNA methylation in asthmatics (vs. controls) and resulting mRNA expression were analyzed by the HumanMethylation450 BeadChip Kit (Illumina) and RNA sequencing. These results were further verified by pyrosequencing and quantitative PCR, respectively. 471 CpGs belonging to 268 genes were identified to have HRVI-induced asthma-specifically modified DNA methylation and mRNA expression. A minimum-change criteria was applied to restrict assessment of genes with changes in DNA methylation and mRNA expression of at least 3% and least 0.1 reads/kb per million mapped reads, respectively. Using this approach we identified 16 CpGs, including HLA-B-associated transcript 3 (BAT3) and Neuraminidase 1 (NEU1), involved in host immune response against HRVI. HRVI in nasal epithelial cells leads to specific modifications of DNA methylation with altered mRNA expression in children with asthma. The HRVI-induced alterations in DNA methylation occurred in genes involved in the host immune response against viral infections and asthma pathogenesis. The findings of our pilot study may partially explain how HRVI contribute to the persistence and progression of asthma, and aid to identify possible new therapeutic targets. The promising findings of this pilot study would benefit from replication in a larger cohort.

PreDicta chip-based high resolution diagnosis of rhinovirus-induced wheeze

Rhinovirus (RV) infections are major triggers of acute exacerbations of severe respiratory diseases such as pre-school wheeze, asthma and chronic obstructive pulmonary disease (COPD). The occurrence of numerous RV types is a major challenge for the identification of the culprit virus types and for the improvement of virus type-specific treatment strategies. Here, we develop a chip containing 130 different micro-arrayed RV proteins and peptides and demonstrate in a cohort of 120 pre-school children, most of whom had been hospitalized due to acute wheeze, that it is possible to determine the culprit RV species with a minute blood sample by serology. Importantly, we identify RV-A and RV-C species as giving rise to most severe respiratory symptoms. Thus, we have generated a chip for the serological identification of RV-induced respiratory illness which should be useful for the rational development of preventive and therapeutic strategies targeting the most important RV types.

Prospective Assessment of Rhinovirus Symptoms and Species Recurrence in Children With and Without an Acute Wheezing Exacerbation

To assess if the difference in species-specific immune response to RV-C correlates with a higher frequency of reinfection, shorter time to reinfection, or different symptom severity than infections with RV-A or RV-B. Forty-three patients were enrolled of which 34 were successfully tracked longitudinally over 3 months, with nasal swabs and symptom questionnaires provided every 2 weeks to identify rhinovirus (RV) strains and the concurrent symptomatology. No difference was found in the time to reinfection with an RV species between RV-C and RV-A or RV-B (p = 0.866). There was a trend toward more rapid reinfection with the same species in RV-C than RV-A (55.1 days vs. 67.9 days), but this failed to reach statistical significance (p = 0.105). RV infections were generally associated with only minor symptoms, with rhinorrhea being the only significantly associated symptom (p = 0.01). RV-C was shown to have higher levels of lethargy and wheeze than other RV species. Time to reinfection with subsequent RV is not influenced by the species of the preceding RV.

Single-Cell Tracking Reveals a Role for Pre-Existing CCR5+ Memory Th1 Cells in the Control of Rhinovirus-A39 After Experimental Challenge in Humans

Background

Little is known about T cells that respond to human rhinovirus in vivo, due to timing of infection, viral diversity, and complex T-cell specificities. We tracked circulating CD4+ T cells with identical epitope specificities that responded to intranasal challenge with rhinovirus (RV)-A39, and we assessed T-cell signatures in the nose.

Methods

Cells were monitored using a mixture of 2 capsid-specific major histocompatibility complex II tetramers over a 7-week period, before and after RV-A39 challenge, in 16 human leukocyte antigen-DR4+ subjects who participated in a trial of Bifidobacterium lactis (Bl-04) supplementation.

Results

Pre-existing tetramer+ T cells were linked to delayed viral shedding, enriched for activated CCR5+ Th1 effectors, and included a minor interleukin-21+ T follicular helper cell subset. After RV challenge, expansion and activation of virus-specific CCR5+ Th1 effectors was restricted to subjects who had a rise in neutralizing antibodies, and tetramer-negative CCR5+ effector memory types were comodulated. In the nose, CXCR3-CCR5+ T cells present during acute infection were activated effector memory type, whereas CXCR3+ cells were central memory type, and cognate chemokine ligands were elevated over baseline. Probiotic had no T-cell effects.

Conclusions

We conclude that virus-specific CCR5+ effector memory CD4+ T cells primed by previous exposure to related viruses contribute to the control of rhinovirus.

T-cell responses against rhinovirus species A and C in asthmatic and healthy children

Background

Infections by rhinovirus (RV) species A and C are the most common causes of exacerbations of asthma and a major cause of exacerbations of other acute and chronic respiratory diseases. Infections by both species are prevalent in pre‐school and school‐aged children and, particularly for RV‐C, can cause severe symptoms and a need for hospitalization. While associations between RV infection and asthma are well established, the adaptive immune‐mechanisms by which RV infections influence asthma exacerbations are yet to be defined.

Objective

The aim of this study was to characterize and compare T‐cell responses between RV‐A and RV‐C and to test the hypothesis that T‐cell responses would differ between asthmatic children and healthy controls.

Methods

A multi‐parameter flow cytometry assay was used to characterize the in vitro recall T‐cell response against RV‐A and RV‐C in PBMCs from children with acute asthma (n = 22) and controls (n = 26). The responses were induced by pools of peptides containing species‐specific VP1 epitopes of RV‐A and RV‐C.

Results

Regardless of children's clinical status, all children that responded to the in vitro stimulation (>90%) had a similar magnitude of CD4+ T‐cell responses to RV‐A and RV‐C. However, asthmatic children had a significantly lower number of circulating regulatory T cells (Tregs), and healthy controls had significantly more Tregs induced by RV‐A than RV‐C.

Conclusions and Clinical Relevance

The comparable recall memory T‐cell responses in asthmatic and control children to both RV‐A and RV‐C show that differences in the antibody and inflammatory responses previously described are likely to be due to regulation, with a demonstrated candidate being reduced regulatory T‐cells. The reduced Treg numbers demonstrated here could explain the asthmatic's inability to appropriately control immunopathological responses to RV infections.

Rhinovirus and preschool wheeze

Rhinovirus (RV) known as the common cold virus generally only causes a mild upper respiratory infection, but severe lower respiratory symptoms have been associated with RV infections especially in asthmatic individuals. Wheezing is a symptom of airway obstruction, and preschool children wheezing with RV have been associated with increased risk of asthma at school age. There are, however, conflicting opinions as to whether there are differences in response to RV infection or whether wheezing with RV reveals a preexisting impairment that promotes asthma mainly in predisposed children. The advent of molecular diagnostics to detect respiratory viruses has led to new insights into the role of RV infections. This review will discuss recent information concerning the role of RV as an important respiratory pathogen related to early onset wheeze and exacerbation of established asthma in preschool children.

House Dust Mite Allergens: New Discoveries and Relevance to the Allergic Patient

PURPOSE OF REVIEW

Recent findings on house dust allergens and their contribution to knowledge that will significantly impact on current and future allergy treatments are appraised.

RECENT FINDINGS

Quantitation of IgE binding to a spectrum of allergen components in several independent studies in varying locations has largely affirmed the main components as the groups 1 and 2 and possibly 23 allergens with mid-tier contributions from the groups 4, 5, 7, and 21. Prevalent binding to Der p 23 has been recapitulated sometimes with low titers. The IgE of non-asthmatic atopic subjects binds at lower titer and to fewer components than that of asthmatics, and their IgG binding relative to IgE is higher especially for children hospitalized for exacerbation. The higher IgG ratios were associated with increased IL-10 a cytokine more readily induced from T cells of allergic subjects. Peptides representing the groups 1 and 2 allergens can be used to stimulate ex vivo T cells showing responses correlating with IgE binding and providing a valuable tool for ascertaining the contribution of IgE and T cells to disease. Also, the induction of Th2 and follicular helper T cells are shown to make different contributions in mice. Cross-reactivity of IgE binding assays with high-titer cross-reactive antibodies induced by scabies is a problem in the many areas of the world where scabies is highly prevalent and endemic and from recent increases in immigration. In the last few years, allergen research has produced results that warrant rapid translation into diagnostic tools and the formulation of allergen components for immunotherapy.

Allergy in severe asthma

It is well recognized that atopic sensitization is an important risk factor for asthma, both in adults and in children. However, the role of allergy in severe asthma is still under debate. The term 'Severe Asthma' encompasses a highly heterogeneous group of patients who require treatment on steps 4-5 of GINA guidelines to prevent their asthma from becoming 'uncontrolled', or whose disease remains 'uncontrolled' despite this therapy. Epidemiological studies on emergency room visits and hospital admissions for asthma suggest the important role of allergy in asthma exacerbations. In addition, allergic asthma in childhood is often associated with severe asthma in adulthood. A strong association exists between asthma exacerbations and respiratory viral infections, and interaction between viruses and allergy further increases the risk of asthma exacerbations. Furthermore, fungal allergy has been shown to play an important role in severe asthma. Other contributing factors include smoking, pollution and work-related exposures. The 'Allergy and Asthma Severity' EAACI Task Force examined the current evidence and produced this position document on the role of allergy in severe asthma.

Rhinovirus-induced asthma exacerbations and risk populations

PURPOSE OF REVIEW

This article discusses recent findings into the mechanisms that determine how viruses trigger asthma exacerbations.

RECENT FINDINGS

Substantial progress has been made in our understanding of the pathogenesis of virus-induced asthma exacerbations. This includes new insights into the role of bacteria, the regulation of interferon responses, and the discovery of innate immune pathways that link viral infections with allergic inflammation. Progress has also been made in elucidating the genetic risk factors for asthma exacerbations, most notably the contribution of the ORMDL3/GSDMB locus on 17q, the mechanisms underlying the farming effect, and the discovery that CDHR3 binds to rhinovirus species C.

SUMMARY

Asthma exacerbations are heterogeneous conditions that involve the complex interplay between environmental exposures and innate and adaptive immune function in genetically predisposed individuals. Recent insights into the interrelationships between these factors provide new opportunities for therapeutic intervention.

Rhinovirus-specific antibody responses in preschool children with acute wheeze reflect severity of respiratory symptoms

BACKGROUND

Some children with rhinovirus (RV) infections wheeze, but it is unknown whether this is due to more virulent strains of virus or differences in host immune responses. The aim of this study was to investigate the RV species-specific antibody responses measured at a follow-up visit in preschool children in relation to reported time with respiratory symptoms and the presence of different RV species during an acute episode of wheeze.

METHOD

Nasopharyngeal swabs and blood samples were taken among 120 preschool children (<4 years of age) at an acute episode of wheeze and at a follow-up visit (median 11 weeks later). Nested PCR was used to detect different RV strains, and serum levels of IgG₁ against purified recombinant VP1 proteins from representatives of the three RV species (RV-A, RV-B, and RV-C) were measured by ELISA.

RESULTS

Rhinovirus was detected in 74% (n = 80/108) of the children at the acute visit, and RV-C was the most common subtype (n = 59/80, 74%). An increase in RV-specific IgG₁ was seen in 61% (n = 73) of the children at follow-up, most frequently against RV-A (n = 61/73, 86%) irrespective of the RV strains detected by PCR. Increases in RV-specific IgG₁ against RV-A or against RV-A and RV-C were significantly associated with more respiratory symptoms (p = 0.03, p = 0.007).

CONCLUSION

Antibody response to recombinant RV VP1 proteins was associated with longer time with respiratory symptoms.

Respiratory viral infections and host responses; insights from genomics

Respiratory viral infections are a leading cause of disease and mortality. The severity of these illnesses can vary markedly from mild or asymptomatic upper airway infections to severe wheezing, bronchiolitis or pneumonia. In this article, we review the viral sensing pathways and organizing principles that govern the innate immune response to infection. Then, we reconstruct the molecular networks that differentiate symptomatic from asymptomatic respiratory viral infections, and identify the underlying molecular drivers of these networks. Finally, we discuss unique aspects of the biology and pathogenesis of infections with respiratory syncytial virus, rhinovirus and influenza, drawing on insights from genomics.

Immunodominant T-Cell Epitopes in the VP1 Capsid Protein of Rhinovirus Species A and C

Rhinovirus (RV) species A and C are the most frequent cause of respiratory viral illness worldwide, and RV-C has been linked to more severe exacerbations of asthma in young children. Little is known about the immune responses to the different RV species, although studies comparing IgG1 antibody titers found impaired antibody responses to RV-C. Therefore, the aim of this study was to assess whether T-cell immunity to RV-C is similarly impaired. We measured T-cell proliferation to overlapping synthetic peptides covering the entire VP1 capsid protein of an RV-A and RV-C genotype for 20 healthy adult donors. Human leukocyte antigen (HLA) was typed in all the donors in order to investigate possible associations between the HLA type and RV peptide recognition. Total and specific IgG1 antibody titers to the VP1 proteins of both RV-A and RV-C were also measured to examine associations between the antibody and T-cell responses. We identified T-cell epitopes that are specific to and representative of each RV-A and RV-C species. These epitopes stimulated CD4⁺-specific T-cell proliferation, with similar magnitudes of response for both RV species. All the donors, independent of their HLA-DR or -DQ type, were able to recognize the immunodominant RV-A and -C regions of VP1. Furthermore, the presence or absence of specific antibody titers was not related to changes in T-cell recognition. Our results indicate a dissociation between the antibody and T-cell responses to rhinoviruses. The species-representative T-cell epitopes identified in this study are valuable tools for future studies investigating T-cell responses to the different RV species.

IMPORTANCE

Rhinoviruses (RVs) are mostly associated with the common cold and asthma exacerbations, although their contributions to most upper and lower respiratory tract diseases have increasingly been reported. Species C (RV-C) has been associated with more frequent and severe asthma exacerbations in young children and, along with RV-A, is the most clinically relevant species. Little is known about how our immune system responds to rhinoviruses, and there are limited tools to study specific adaptive immunity against each rhinovirus species. In this study, we identified immunodominant T-cell epitopes of the VP1 proteins of RV-A and RV-C, which are representative of each species. The study found that T-cell responses to RV-A and RV-C were of similar magnitudes, in contrast with previous findings showing RV-C-specific antibody responses were low. These findings will provide the basis for future studies on the immune response to rhinoviruses and can help elucidate the mechanisms of severity of rhinovirus-induced infections.

Circulating Memory CD4+ T Cells Target Conserved Epitopes of Rhinovirus Capsid Proteins and Respond Rapidly to Experimental Infection in Humans

Rhinovirus (RV) is a major cause of common cold and an important trigger of acute episodes of chronic lung diseases. Antigenic variation across the numerous RV strains results in frequent infections and a lack of durable cross-protection. Because the nature of human CD4⁺ T cells that target RV is largely unknown, T cell epitopes of RV capsid proteins were analyzed, and cognate T cells were characterized in healthy subjects and those infected by intranasal challenge. Peptide epitopes of the RV-A16 capsid proteins VP1 and VP2 were identified by peptide/MHC class II tetramer-guided epitope mapping, validated by direct ex vivo enumeration, and interrogated using a variety of in silico methods. Among noninfected subjects, those circulating RV-A16-specific CD4⁺ T cells detected at the highest frequencies targeted 10 unique epitopes that bound to diverse HLA-DR molecules. T cell epitopes localized to conserved molecular regions of biological significance to the virus were enriched for HLA class I and II binding motifs, and constituted both species-specific (RV-A) and pan-species (RV-A, -B, and -C) varieties. Circulating epitope-specific T cells comprised both memory Th1 and T follicular helper cells, and were rapidly expanded and activated after intranasal challenge with RV-A16. Cross-reactivity was evidenced by identification of a common *0401-restricted epitope for RV-A16 and RV-A39 by tetramer-guided epitope mapping and the ability for RV-A16-specific Th1 cells to proliferate in response to their RV-A39 peptide counterpart. The preferential persistence of high-frequency RV-specific memory Th1 cells that recognize a limited set of conserved epitopes likely arises from iterative priming by previous exposures to different RV strains.

Lower anti-echovirus antibody responses in children presenting to hospital with asthma exacerbations

BACKGROUND

Rhinoviruses from the Enterovirus genus cause frequent infections and induce remarkably high titres of anticapsid antigen antibodies in asthmatics, while the prevalence of neutralising antibodies to the gut-trophic echoviruses from the same genus is diminished.

OBJECTIVE

To assess the absolute and specific antibody titres to VP1 antigens of the gut-trophic enteroviruses, echovirus 30 and Sabin 1 poliovirus, in asthmatic and non-asthmatic children.

METHODS

Recombinant polypeptides representing the VP1 capsid antigens of echovirus 30 and Sabin poliovirus 1 were produced. Their ability to bind IgG1 antibodies from the plasma of asthmatic (n = 45) and non-asthmatic (n = 29) children were quantitated by immunoassays that incorporated immunoabsorptions to remove cross-reactivity.

RESULTS

The IgG1 antibody titres and prevalence of antibody binding to echovirus 30 were significantly lower for asthmatic children compared to controls (P < 0.05) and inversely correlated with total IgE levels for the whole study population (r = -0.262; P < 0.05). There was no difference in the prevalence and titre between groups to the VP1 antigen of Sabin poliovirus. Anti-tetanus toxoid titres measured for comparison did not correlate with anti-echovirus or poliovirus, but correlated with anti-rhinovirus titres in controls but not asthmatics, where the titres were higher for the asthmatic group.

CONCLUSIONS AND CLINICAL RELEVANCE

The associations of lower antibody titres of asthmatic children to echovirus reported here and those of our previous findings of a heightened response to rhinovirus suggest a dichotomy where respiratory enterovirus infection/immunity increases the probability of developing asthma and enteric infections lower the risk. This provides further support for the concept of intestinal infection playing a key role in the development of allergic respiratory disease.

Advances in environmental and occupational disorders in 2014

In 2014, the Journal published a number of studies that have advanced our understanding of the effects of various environmental factors and immune responses in patients with allergic diseases. In this review we emphasize reports that have appeared in the Journal over the past year that deal with environmental and occupational respiratory disorders and novel approaches to their treatment. The review will focus on the effects of environmental factors and immune responses in allergic airway diseases, identification of new allergens, and risk factors in stinging insect allergy, development of asthma in different age groups, effects of viral infections, and benefits of new therapies.

Recurrent rhinovirus detections in children following a rhinovirus-induced wheezing exacerbation: A retrospective study

INTRODUCTION

It is unclear if children with a rhinovirus (RV)-induced wheezing exacerbation are more susceptible to viruses longitudinally, and whether a parental history of asthma and/or allergy impacts their susceptibility. The objective of this study was to determine if RV, RV-A and RV-C related wheezing exacerbations in children were associated with prior or subsequent viral detections and investigate the role of parental history of asthma and allergy.

MATERIALS AND METHODS

Children presenting to hospital with acute wheeze were prospectively recruited and tested for respiratory viruses. Data on viruses detected in other respiratory samples (May 1997 to December 2012) were collected from hospital microbiology records and additional RV testing was performed on stored hospital respiratory samples (September 2009 to December 2012). A positive parental history was defined as either parent with self-reported asthma and/or allergy.

RESULTS

At recruitment, RV was detected in 69.2% of samples from children with an acute wheezing episode (n=373, 0-16 years of age), with RV-C the most common virus (65.5%). Children with a history of parental asthma and/or allergy and RV at recruitment had a 14-fold increased incidence rate ratio (IRR) of subsequent RV detection (IRR 14.0, 95% CI 1.9-104.1; p=0.01) compared with children without RV at recruitment. Children without this parental history had a reduced incident rate ratio for samples assessed during this time (IRR 0.5, 95% CI 0.3-0.9; p=0.03).

CONCLUSION

Children with a parental history of asthma and/or allergy may become more susceptible to recurrent symptomatic RV infections.

Challenges in developing a cross-serotype rhinovirus vaccine

A great burden of disease is attributable to human rhinovirus (HRV) infections which are the major cause of the common cold, exacerbations of both asthma and chronic obstructive pulmonary disease (COPD), and are associated with asthma development. Despite this there is currently no vaccine for HRV. The first vaccine studies showed some promise in terms of serotype-specific protection against cold symptoms, but antigenic heterogeneity amongst the >150 HRVs has been regarded as a major barrier to effective vaccine development and has resulted in little progress over 50 years. Here we review those vaccine studies conducted to date, discuss the difficulties posed by antigenic heterogeneity and describe some recent advances in generating cross-reactive antibodies and T cell responses using peptide immunogens.

Advances in pediatric asthma in 2014: Moving toward a population health perspective

Last year's "Advances in pediatric asthma in 2013: Coordinating asthma care" concluded that, "Enhanced communication systems will be necessary among parents, clinicians, health care providers and the pharmaceutical industry so that we continue the pathway of understanding the disease and developing new treatments that address the unmet needs of patients who are at risk for severe consequences of unchecked disease persistence or progression." This year's summary will focus on further advances in pediatric asthma related to prenatal and postnatal factors altering the natural history of asthma, assessment of asthma control, and new insights regarding the management of asthma in children as indicated in Journal of Allergy and Clinical Immunology publications in 2014. A major theme of this review is how new research reports can be integrated into medical communication in a population health perspective to assist clinicians in asthma management. The asthma specialist is in a unique position to convey important messages to the medical community related to factors that influence the course of asthma, methods to assess and communicate levels of control, and new targets for intervention, as well as new immunomodulators. By enhancing communication among patients, parents, primary care physicians, and specialists within provider systems, the asthma specialist can provide timely information that can help to reduce asthma morbidity and mortality.

The Argentina Premature Asthma and Respiratory Team (APART): objectives, design, and recruitment results of a prospective cohort study of viruses and wheezing in very low birth weight infants

Background

Asthma and wheezing account for a substantial disease burden around the world. Very low birth weight (VLBW, <1500 grams) infants are at an increased risk for the development of severe acute respiratory illness (ARI) and recurrent wheeze/asthma. The role of respiratory viruses in asthma predisposition in premature infants is not well understood. Preliminary evidence suggests that infection with human rhinovirus (RV) early in life may contribute to greater burden of asthma later in life.

Methods

A prospective cohort study of premature VLBW infants from Buenos Aires, Argentina, was enrolled year-round during a three-year period in the neonatal intensive care unit and followed during every ARI and with monthly well visits during the first year of life. Longitudinal follow-up up until age five years is ongoing.

Results

This report describes the objectives, design, and recruitment results of this prospective cohort. Two hundred and five patients were enrolled from August 2011 through January 2014, and follow-up is ongoing. A total of 319 ARI episodes were observed from August 2011 to July 2014, and 910 well visits occurred during this time period.

Conclusions

The Argentina Premature Asthma and Respiratory Team (APART) is a unique cohort consisting of over 200 patients and over 1200 specimens who have been and will continue to be followed intensively from NICU discharge to capture baseline risk factors and every ARI, with interceding well visits during the first year of life, as well as longitudinal follow-up to age 5 years for asthma and atopy outcomes.

Rhinovirus-induced VP1-specific Antibodies are Group-specific and Associated With Severity of Respiratory Symptoms

Background

Rhinoviruses (RVs) are a major cause of common colds and induce exacerbations of asthma and chronic inflammatory lung diseases.

Methods

We expressed and purified recombinant RV coat proteins VP1-4, non-structural proteins as well as N-terminal fragments of VP1 from four RV strains (RV14, 16, 89, C) covering the three known RV groups (RV-A, RV-B and RV-C) and measured specific IgG-subclass-, IgA- and IgM-responses by ELISA in subjects with different severities of asthma or without asthma before and after experimental infection with RV16.

Findings

Before infection subjects showed IgG₁ > IgA > IgM > IgG₃ cross-reactivity with N-terminal fragments from the representative VP1 proteins of the three RV groups. Antibody levels were higher in the asthmatic group as compared to the non-asthmatic subjects. Six weeks after infection with RV16, IgG₁ antibodies showed a group-specific increase towards the N-terminal VP1 fragment, but not towards other capsid and non-structural proteins, which was highest in subjects with severe upper and lower respiratory symptoms.

Interpretation

Our results demonstrate that increases of antibodies towards the VP1 N-terminus are group-specific and associated with severity of respiratory symptoms and suggest that it may be possible to develop serological tests for identifying causative RV groups.

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Increases of rhinovirus-specific antibodies are surrogate markers for severity of rhinovirus-induced respiratory symptoms.

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Serological tests based on recombinant rhinovirus coat protein fragments identify the culprit rhinovirus strain.

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Identification of the most relevant RV strains by serology should allow the rational design of RV vaccines.