Development of atopy by severe paramyxoviral infection in a mouse model

Moderate-to-severe lower respiratory tract infection in early life is associated with increased risk of polysensitization and atopic dermatitis: Findings from the CHILD Study

Background

Respiratory infections in infancy are associated with the development of allergic asthma and atopy. Delineating whether symptomatic infections are a marker of atopic predisposition or contribute to atopic development is important for preventive strategies. We hypothesized that early, severe lower respiratory tract infections (LRTIs) may be a risk factor for the development of atopic disease.

Objective

Our aim was to determine whether clinically defined, moderate-to-severe LRTIs in infancy are associated with the development of atopic dermatitis and allergic sensitization at preschool age.

Methods

LRTI timing and severity in the first 18 months of life was defined by using the Canadian Healthy Infant Longitudinal Development study questionnaires. Polysensitization and atopic dermatitis were determined by standardized skin prick testing and structured clinical assessments. Longitudinal associations between LRTI severity and clinical outcomes at ages 3 years and 5 years were determined by adjusted repeated measures generalized estimation equations.

Results

Moderate-to-severe LRTIs were associated with increased odds of polysensitization (odds ratio = 1.91 [95% CI = 1.16-3.15]; P = .014) and atopic dermatitis (odds ratio = 2.19 [95% CI 1.41-3.39]; P < .001) as compared with the odds in children with no history of LRTI in the first 18 months of life. The association between moderate-to-severe LRTI and polysensitization or atopic dermatitis remained robust after adjusting for sex; study site; breast-feeding duration; and mother, father, or both-parent atopy or asthma.

Conclusions

These results highlight severe infant LRTI as an important risk factor for allergic and atopic disease (ie, polysensitization and atopic dermatitis), and they suggest that this risk is independent of maternal in utero environment, both-parent history of asthma, and both-parent genetic predisposition.

Mouse Model of Sendai Virus-Induced Lung Disease

Sendai virus (SeV), also known as the murine parainfluenza virus 1, is an enveloped negative-sense RNA paramyxovirus from the family Paramyxoviridae and genus Respirovirus. The virus was named after Sendai, city in Japan, where it was first isolated (Kuroya, Ishida, Yokohama Med Bull 4:217-233, 1953). Antigenically, SeV is closely related to human parainfluenza viruses 1 and 3. SeV is pneumotropic and naturally infects the respiratory tract of rodents. At the proper inoculum (2 × 10⁵ pfu), SeV causes infection that is limited to the airway mucosa and inflammation mainly restricted to bronchiolar tissues as seen in asthma pathogenesis models using C57BL/6 wild-type mice (Walter et al, J Clin Invest 110:165-175, 2002). We utilize SeV to explore the mechanism(s) by which a respiratory viral infection translates into postviral airway disease in mice. This chapter primarily describes the protocols we use to infect mice in vivo, assay viral replication, and assess outcomes in the lungs of the host.

Atopic Neutrophils Prevent Postviral Airway Disease

Respiratory syncytial virus (RSV) infection in infancy is associated with increased risk of asthma, except in those with allergic disease at the time of infection. Using house dust mite allergen, we examined the effect of pre-existing atopy on postviral airway disease using Sendai virus in mice, which models RSV infection in humans. Sendai virus drives postviral airway disease in nonatopic mice; however, pre-existing atopy protected against the development of airway disease. This protection depended upon neutrophils, as depletion of neutrophils at the time of infection restored the susceptibility of atopic mice to postviral airway disease. Associated with development of atopy was an increase in polymorphonuclear neutrophil-dendritic cell hybrid cells that develop in Th2 conditions and demonstrated increased viral uptake. Systemic inhibition of IL-4 reversed atopic protection against postviral airway disease, suggesting that increased virus uptake by neutrophils was IL-4 dependent. Finally, human neutrophils from atopic donors were able to reduce RSV infection of human airway epithelial cells in vitro, suggesting these findings could apply to the human. Collectively our data support the idea that pre-existing atopy derives a protective neutrophil response via potential interaction with IL-4, preventing development of postviral airway disease.

Association of antibiotics use in preschool age with atopic and allergic skin diseases in young adulthood: a population-based retrospective cohort study

BACKGROUND

Overuse and misuse of antibiotics is a public health problem in low-income and middle-income countries. Although the association of antibiotics with atopic and allergic diseases has been established, most studies focused on prenatal exposure and the occurrence of disease in infants or young children.

OBJECTIVE

To investigate the association of preschool use of antibiotics with atopic and allergic skin diseases in young adulthood.

DESIGN

Population-based retrospective cohort.

SETTING AND PARTICIPANTS

The first-year college students (n=20 123) from five universities were investigated. The sampled universities are located in Changsha, Wuhan, Xiamen, Urumqi and Hohhot, respectively.

METHODS

We conducted a dermatological field examination and a questionnaire survey inquiring the participants about the frequency of upper respiratory tract infection (URTI) and the preschool antibiotics use (prior to 7 years old). The two-level probit model was used to estimate the associations, and adjusted risk ratio (aRR) and 95% CI were presented as the effect size.

RESULTS

A total of 20 123 participants with complete information was included in the final analysis. The frequent antibiotics use intravenously (aRR 1.36, 95% CI 1.14 to 1.62) and orally (aRR 1.18, 95% CI 1.01 to 1.38) prior to 7 years old was significantly associated with atopic dermatitis in young adulthood. Similar trends could be observed in allergic skin diseases among those who use antibiotics orally and intravenously, with RRs of 1.16 (95% CI 1.01 to 1.34) and 1.33 (95% CI 1.13 to 1.57), respectively.

CONCLUSIONS

Preschool URTI and antibiotics use significantly increases the risk of atopic and allergic skin diseases in young adulthood.

Asthma and viral infections: An intricate relationship

OBJECTIVE

To synthesize available data related to the complex associations among viral infections, atopy, and asthma.

DATA SOURCES

Key historical articles, articles highlighted in our recent review of most significant recent asthma advancements, and findings from several birth cohorts related to asthma and viral infections were reviewed. In addition, PubMed was searched for review articles and original research related to the associations between viral infection and asthma, using the search words asthma, viral infections, atopy, development of asthma, rhinovirus (RV), and respiratory syncytial virus (RSV).

STUDY SELECTIONS

Articles were selected based on novelty and relevance to our topic of interest, the role of asthma and viral infections, and possible mechanisms to explain the association.

RESULTS

There is a large body of evidence demonstrating a link between early viral infections (especially RV and RSV) and asthma inception and exacerbations. RV-induced wheezing is an important risk factor for asthma only when atopy is present, with much evidence supporting the idea that sensitization is a risk factor for early RV-induced wheezing, which in turn is a risk factor for asthma. RSV, on the other hand, is a more important risk factor for nonatopic asthma, with severe infections conferring greater risk.

CONCLUSION

There are important differences in the development of atopic and nonatopic asthma, with several proposed mechanisms explaining the association between viral infections and the development of asthma and asthma exacerbations. Understanding these complex associations is important for developing asthma prevention strategies and targeted asthma therapies.

Post-viral atopic airway disease: pathogenesis and potential avenues for intervention

Introduction: In early childhood, wheezing due to lower respiratory tract illness is often associated with infection by commonly known respiratory viruses such as respiratory syncytial virus (RSV) and human rhinovirus (RV). How respiratory viral infections lead to wheeze and/or asthma is an area of active research. Areas covered: This review provides an updated summary of the published information on the development of post-viral induced atopy and asthma and the mechanisms involved. We focus on the contribution of animal models in identifying pathways that may contribute to atopy and asthma following respiratory virus infection, different polymorphisms that have been associated with asthma development, and current options for disease management and potential future interventions. Expert commentary: Currently there are no prophylactic therapies that prevent infants infected with respiratory viruses from developing asthma or atopy. Neither are there curative therapies for patients with asthma. Therefore, a better understanding of genetic factors and other associated biomarkers in respiratory viral induced pathogenesis is important for developing effective personalized therapies.

Respiratory viral infections and atopic development: From possible mechanisms to advances in treatment

Atopic sensitization and allergic diseases are increasing in modernized countries. These diseases affect millions of individuals, but the mechanisms behind their development are not fully understood. One hypothesis relates to early life respiratory viral infections driving the development of atopic disease including asthma. This review presents the current state of the field, focusing on epidemiologic data supporting a role for early life respiratory viruses in the development of specific IgE, both against aeroallergens and the respiratory virus. Our own work using the Sendai mouse model is then summarized to provide a potential mechanistic explanation for how a respiratory viral infection could drive development of atopic sensitization and disease. We then discuss the components of this mechanistic pathway that have and have not been validated in humans. Finally, we discuss areas ripe for research, as well as potential and current therapeutics that might disrupt the link between respiratory viral infections in early life and atopic sensitization/disease.

Cysteinyl leukotriene receptor 1 expression identifies a subset of neutrophils during the antiviral response that contributes to postviral atopic airway disease

BACKGROUND

Viral respiratory tract infections increase the risk of development and exacerbation of atopic disease. Previously, we demonstrated the requirement for a neutrophil (PMN) subset expressing CD49d to drive development of postviral atopic airway disease in mice.

OBJECTIVE

We sought to determine whether human CD49d⁺ PMNs are present in the nasal mucosa during acute viral respiratory tract infections and further characterize this PMN subset in human subjects and mice.

METHODS

Sixty subjects (5-50 years old) were enrolled within 4 days of acute onset of upper respiratory symptoms. Nasal lavage for flow cytometry and nasal swabs for viral PCR were performed at enrollment and during convalescence. The Sendai virus mouse model was used to investigate the phenotype and functional relevance of CD49d⁺ PMNs.

RESULTS

CD49d⁺ PMN frequency was significantly higher in nasal lavage fluid during acute respiratory symptoms in all subjects (2.9% vs 1.0%, n = 42, P < .001). In mice CD49d⁺ PMNs represented a "proatopic" neutrophil subset that expressed cysteinyl leukotriene receptor 1 (CysLTR1) and produced TNF, CCL2, and CCL5. Inhibition of CysLTR1 signaling in the first days of a viral respiratory tract infection was sufficient to reduce accumulation of CD49d⁺ PMNs in the lungs and development of postviral atopic airway disease. Similar to the mouse, human CD49d⁺ PMNs isolated from nasal lavage fluid during a viral respiratory tract infection expressed CysLTR1.

CONCLUSION

CD49d and CysLTR1-coexpressing PMNs are present during symptoms of an acute viral respiratory tract infection in human subjects. Further study is needed to examine selective targeting of proatopic neutrophils as a potential therapeutic strategy to prevent development of postviral atopic airway disease.

POL7085 or anti-CCL28 treatment inhibits development of post-paramyxoviral airway disease

INTRODUCTION

Asthma is major health burden throughout the world, and there are no therapies that have been shown to be able to prevent the development of disease. A severe respiratory paramyxoviral infection early in life has been demonstrated to greatly increase the risk of developing asthma. We have a mouse model of a severe respiratory paramyxoviral infection (Sendai virus, SeV) that mimics human disease, and requires early expression of the cytokine CCL28 to drive the development of post-viral airway disease. The known receptors for CCL28 are CCR3 and CCR10. However, it is not known if blockade of these receptors will prevent the development of post-viral airway disease. The objective of this study was to determine if treatment with a protein epitope mimetic antagonist of CCR10, POL7085, will provide sufficient protection against the development of post-viral airway disease.

METHODS

C57BL6 mice were inoculated with SeV or UV inactivated SeV. From day 3-19 post inoculation (PI), mice were subcutaneously administered daily POL7085 or saline, or every other day anti-CCL28 mAb. On days 8, 10, and 12 PI bronchoalveolar cytokines, serum IgE, and lung cellular constituents were measured. At day 21 PI airway hyper-reactivity to methacholine and mucous cell metaplasia was measured.

RESULTS

Treatment with either anti-CCL28 or POL7085 significantly reduced development of airway hyper-reactivity and mucous cell metaplasia following SeV infection. The prevention of post-viral airway disease was associated with early reductions in innate immune cells, but did not appear to be due to a reduction in IL-13 or IgE.

CONCLUSIONS

Blockade of CCL28 or CCR10 during an acute severe respiratory paramyxoviral infection is sufficient to prevent the development of post-viral airway disease. However, the mechanism of action is unclear and requires further exploration.

IL-10 gene polymorphism is associated with preschool atopy and early-life recurrent wheezing after bronchiolitis in infancy

BACKGROUND

Variations in the genes that regulate innate immunity responses may be associated with susceptibility to asthma or atopy after early-life bronchiolitis. The aim of this study was to evaluate the association between four different polymorphisms of the IL-10 gene at rs1800871, rs1800872, rs1800890, and rs1800896, either alone or in combination, and post-bronchiolitis asthma or allergies at 5-7 years of age.

METHODS

Data on single nucleotide polymorphisms (SNP) of IL-10 rs1800896 (-1082G/A), rs1800871 (-819C/T), rs1800872 (-592C/A), and IL-10 rs1800890 (-3575T/A) were available for 135 children. Polymorphisms and their associations with asthma and allergies were studied in 135 preschool-aged children who had been hospitalized for bronchiolitis at age 0-6 months. Their parents were interviewed to record the children's history with asthma and allergies from infancy to the present.

RESULTS

At 6.4 years (mean), asthma was present in 17 children (12.6%), while recurrent wheezing during the first 7 years of life was present in 39 (28.9%) children. Fifty-three (39.3%) study participants had current atopy (atopic eczema or allergic rhinitis). Eight (72%) of 11 children with the IL-10 rs1800896, IL-10 rs1800871, and IL-10 rs1800872 combination AA + CT + CA had current atopy (P = 0.02 vs. 38% in other genotype combinations). Twenty-three (56%) children with the IL-10 rs1800871C/T or IL-10 rs1800872C/A genotype had present atopy versus 34 (38%) with other IL-10 genotypes (P = 0.03). Between 2 years and 3 years of age, 27% of ATA haplotype carriers had asthma versus 13.7% of other haplotype carriers (P = 0.02).

CONCLUSIONS

IL-10 polymorphisms at rs1800871, rs1800872, rs1800890, and rs1800896 seem to be associated with elevated allergies and/or recurrent wheezing risk in later childhood, after early-life bronchiolitis. Pediatr Pulmonol. 2017;52:14-20. © 2016 Wiley Periodicals, Inc.

Rhinoviruses and Their Receptors: Implications for Allergic Disease

Human rhinoviruses (RVs) are picornaviruses that can cause a variety of illnesses including the common cold, lower respiratory tract illnesses such as bronchitis and pneumonia, and exacerbations of asthma. RVs are classified into three species, RV-A, B, and C, which include over 160 types. They utilize three major types of cellular membrane glycoproteins to gain entry into the host cell: intercellular adhesion molecule 1 (ICAM-1) (the majority of RV-A and all RV-B), low-density lipoprotein receptor (LDLR) family members (12 RV-A types), and cadherin-related family member 3 (CDHR3) (RV-C). CDHR3 is a member of cadherin superfamily of transmembrane proteins with yet unknown biological function, and there is relatively little information available about the mechanisms of RV-C interaction with CDHR3. A coding single nucleotide polymorphism (rs6967330) in CDHR3 could promote RV-C infections and illnesses in infancy, which could in turn adversely affect the developing lung to increase the risk of asthma. Further studies are needed to determine how RV infections contribute to pathogenesis of asthma and to develop the optimal treatment approach to control asthma exacerbations.

Structure-function analysis of CCL28 in the development of post-viral asthma

CCL28 is a human chemokine constitutively expressed by epithelial cells in diverse mucosal tissues and is known to attract a variety of immune cell types including T-cell subsets and eosinophils. Elevated levels of CCL28 have been found in the airways of individuals with asthma, and previous studies have indicated that CCL28 plays a vital role in the acute development of post-viral asthma. Our study builds on this, demonstrating that CCL28 is also important in the chronic post-viral asthma phenotype. In the absence of a viral infection, we also demonstrate that CCL28 is both necessary and sufficient for induction of asthma pathology. Additionally, we present the first effort aimed at elucidating the structural features of CCL28. Chemokines are defined by a conserved tertiary structure composed of a three-stranded β-sheet and a C-terminal α-helix constrained by two disulfide bonds. In addition to the four disulfide bond-forming cysteine residues that define the traditional chemokine fold, CCL28 possesses two additional cysteine residues that form a third disulfide bond. If all disulfide bonds are disrupted, recombinant human CCL28 is no longer able to drive mouse CD4+ T-cell chemotaxis or in vivo airway hyper-reactivity, indicating that the conserved chemokine fold is necessary for its biologic activity. Due to the intimate relationship between CCL28 and asthma pathology, it is clear that CCL28 presents a novel target for the development of alternative asthma therapeutics.

The role of early life viral bronchiolitis in the inception of asthma

PROPOSE OF REVIEW: Cumulative evidence suggest that early life bronchiolitis is a major risk factor for subsequent wheezing episodes and asthma. The purpose of this review is to present the recent findings and current perspectives regarding the interplay between bronchiolitis and long-term respiratory outcomes.

RECENT FINDINGS

Recent studies have supported the long-recognized link between early life severe respiratory syncytial virus bronchiolitis and the physician diagnosis of asthma by school age, and this association appears to continue into early adulthood. Evidence is accumulating regarding the role of early life infection with human rhinovirus as an important antecedent for future asthma. Whether viral bronchiolitis is causal or an early manifestation of future asthma remains uncertain. Vitamin D status has emerged as a potential modifying factor for viral-induced wheeze and could potentially influence the development of asthma.

SUMMARY

Viral bronchiolitis early in life is a major and potential long-term risk factor for subsequent wheezing and asthma. Whether the association between bronchiolitis and subsequent asthma is due to causality or a reflection of predisposition may be dependent on host factors and virus-specific effects.

Role of viruses in the development of atopic disease in pediatric patients

The prevalence of atopic diseases continues to rise in modernized countries, without a clear explanation for this increase. One potential cause identified from epidemiologic studies of children is respiratory RNA viral infections leading to development of recurrent wheezing, asthma, and allergic sensitization. We review human epidemiologic data that both support and refute the role of viruses in this process. Exploring recent murine models, we document possible immunologic mechanisms that could translate a viral infection into atopic disease. We further discuss evidence for a post-viral "atopic cycle" that could explain the development of multiple allergen sensitization, and we explore available data to suggest a connection between viral infections of the gastrointestinal tract with the development of food allergy. Taken together, this review documents evidence to support the "viral hypothesis", and, in particular, the role of RNA viruses in the development of atopic disease.

Dendritic cells, viruses, and the development of atopic disease

Dendritic cells are important residents of the lung environment. They have been associated with asthma and other inflammatory diseases of the airways. In addition to their antigen-presenting functions, dendritic cells have the ability to modulate the lung environment to promote atopic disease. While it has long been known that respiratory viral infections associate with the development and exacerbation of atopic diseases, the exact mechanisms have been unclear. Recent studies have begun to show the critical importance of the dendritic cell in this process. This paper focuses on these data demonstrating how different populations of dendritic cells are capable of bridging the adaptive and innate immune systems, ultimately leading to the translation of viral illness into atopic disease.

Respiratory syncytial virus reverses airway hyperresponsiveness to methacholine in ovalbumin-sensitized mice

Each year, approximately 20% of asthmatics in the United States experience acute symptom exacerbations, which commonly result from pulmonary viral infections. The majority of asthma exacerbations in very young children follow infection with respiratory syncytial virus (RSV). However, pathogenic mechanisms underlying induction of asthma exacerbations by RSV are not well understood. We therefore investigated the effect of post-sensitization RSV infection on lung function in ovalbumin (OVA)-sensitized BALB/c mice as a model of RSV asthma exacerbations. OVA sensitization of uninfected female BALB/c mice increased bronchoalveolar lavage fluid (BALF) eosinophil levels and induced airway hyperresponsiveness to the muscarinic agonist methacholine, as measured by the forced-oscillation technique. In contrast, intranasal infection with replication-competent RSV strain A2 for 2–8 days reduced BALF eosinophil counts and reversed airway hyperresponsiveness in a pertussis toxin-sensitive manner. BALF levels of the chemokine keratinocyte cytokine (KC; a murine homolog of interleukin-8) were elevated in OVA-sensitized, RSV-infected mice and reversal of methacholine hyperresponsiveness in these animals was rapidly inhibited by KC neutralization. Hyporesponsiveness could be induced in OVA-sensitized, uninfected mice by recombinant KC or the Gαi agonist melittin. These data suggest that respiratory syncytial virus induces KC-mediated activation of Gαi, resulting in cross-inhibition of Gαq-mediated M₃-muscarinic receptor signaling and reversal of airway hyperresponsiveness. As in unsensitized mice, KC therefore appears to play a significant role in induction of airway dysfunction by respiratory syncytial virus. Hence, interleukin-8 may be a promising therapeutic target to normalize lung function in both asthmatics and non-asthmatics with bronchiolitis. However, the OVA-sensitized, RSV-infected mouse may not be an appropriate model for investigating the pathogenesis of viral asthma exacerbations.

Expression of high-affinity IgE receptor on human peripheral blood dendritic cells in children

Background

In a mouse model of viral induced atopic disease, expression of FcεRI on dendritic cells is critical. While adult human conventional (cDC) and plasmacytoid (pDC) dendritic cells have been shown to express FcεRI, it is not known if this receptor is expressed in childhood and how its expression is governed by IgE.

Methods

Following informed consent of subjects (n = 27, aged 12–188 months), peripheral blood was stained for surface expression of CD19, ILT7, CD1c, IgE, FcεRI and analyzed by flow cytometry (cDC: CD19⁻ ILT7⁻ CD1c⁺; pDC: CD19⁻ ILT7⁺ CD1c⁻). Total and specific serum IgE levels to food and inhalant allergens were determined by ImmunoCAP, and the relationship between FcεRI expression on dendritic cells and sensitization, free IgE, cell bound IgE, and age was determined.

Results

Independent of sensitization status, FcεRI expression was noted on cDC and pDC as early as 12 months of age. Serum IgE level correlated with expression of FcεRI on cDC, but not pDC. Based on the concentration of IgE, a complex relationship was found between surface bound IgE and expression of FcεRI on cDC. pDC exhibited a linear relationship of FcεRI expression and bound IgE that was consistent through all IgE concentrations.

Conclusions

In children, FcεRI expression on cDC and pDC is modulated differently by serum and cell bound IgE. IgE governance of FcεRI expression on cDC depends upon a complex relationship. Further studies are needed to determine the functional roles of FcεRI on cDC and pDC.

Characterization of intestinal dendritic cells in murine norovirus infection

We have shown that respiratory viral infections drive allergic disease through dendritic cells, whether gastrointestinal viruses induce allergies is not known. Norovirus infections are a major cause of gastroenteritis in humans. We used murine norovirus (MNV) to explore the effect of MNV infection on gastrointestinal conventional DCs (cDCs) and plasmacytoid DCs (pDCs). MNV infection induced disparate effects on cDCs and pDCs in lymphoid tissues of the small intestine and draining mesenteric lymph nodes. FcεRI was transiently expressed on lamina propria cDCs, but not on pDCs. In addition, feeding ovalbumin during the viral infection led to a modest, brief induction of anti-ovalbumin IgE. Together, these data suggest that like with a respiratory viral infection, an intestinal viral infection may be sufficient to induce changes in DCs and the generation of food-specific IgE. Whether this represents a novel mechanism of food allergy remains to be determined.