Allergic predisposition among infants with bronchiolitis

Lung function, allergic sensitization and asthma in school-aged children after viral-coinfection bronchiolitis

Our main objective was to compare the lung function, the rate of allergic sensitization and the prevalence of asthma at 7–9 years in children hospitalized for bronchiolitis with viral coinfection versus single viral infection. Observational study in children with previous bronchiolitis and current age 7–9 years. Clinical data were collected. Fraction of exhaled nitric oxide (FeNO) determination, spirometry and skin prick test for common aeroallergens were performed. A total of 181 children hospitalized for bronchiolitis (40 coinfections and 141 single infections), with median age of 8.3 years (IQR:7.5–9.1) were included. Single-HRV-infections showed lower basal FEV1(%) than coinfections (p = 0.04) and lower z-score FEV1 than single-RSV-infections (p = 0.04) or coinfections (p = 0.02). Also, single-HRV-infections had lower post-bronchodilator FEV1(%) and z-score FEV1 values than coinfections (p = 0.03 and p = 0.03). Single-HRV-bronchiolitis was an independent risk factor for FEV1 < 80% (p = 0.007). FeNO value > 25 ppb was detected in 21(12.5%) cases, without differences between viral groups (p = 0.768). The prevalence of allergic sensitization was similar in coinfections (31.4%) versus single infections (38.7%), (p = 0.428). The highest frequency of allergic rhinitis was observed in single-HRV patients (p = 0.004). The respiratory morbidity at 7–9 years of coinfected patients was similar to the single-HRV ones. In contrast, the likelihood of current asthma was up to 5 times higher in RSV/HRV coinfections than in the single-RSV-infections ones (p = 0.012). The respiratory morbidity at 7–9 years of age after severe bronchiolitis is significantly higher in single-HRV or viral coinfection patients that in single-RSV ones. Single-HRV-bronchiolitis is independently associated with lower lung function at school-age.

Association of early viral lower respiratory infections and subsequent development of atopy, a systematic review and meta-analysis of cohort studies

INTRODUCTION

Existing evidence on the relationship between childhood lower respiratory tract infections (LRTI) and the subsequent atopy development is controversial. We aimed to investigate an association between viral LRTI at <5 years and the development of atopy at > 2 years.

METHODS

We conducted a search at Embase, Pubmed, Web of Science, and Global Index Medicus. We collected data from the included articles. We estimated the odds ratio and the 95% confidence intervals with a random effect model. We determined factors associated with atopy development after childhood LRTI using univariate and multivariate meta-regression analyses. We recorded this systematic review at PROSPERO with the number CRD42018116955.

RESULTS

We included 24 studies. There was no relationship between viral LRTI at <5 years and skin prick test-diagnosed-atopy (OR = 1.2, [95% CI = 0.7-2.0]), unknown diagnosed-atopy (OR = 0.7, [95% CI = 0.4-1.3]), atopic dermatitis (OR = 1.2, [95% CI = 0.9-1.6]), hyperreactivity to pollen (OR = 0.8, [95% CI = 0.3-2.7]), food (OR = 0.8, [95% CI = 0.3-2.5]), or house dust mite (OR = 1.1, [95% CI = 0.6-2.2]). Although not confirmed in all studies with a symmetric distribution of the 23 confounding factors investigated, the overall analyses showed that there was a relationship between childhood viral LRTI at < 5 years and serum test diagnosed-atopy (OR = 2.0, [95% CI = 1.0-4.1]), allergic rhinoconjunctivitis (OR = 1.7, [95% CI = 1.1-2.9]), hyperreactivity diagnosed by serum tests with food (OR = 5.3, [1.7-16.7]) or inhaled allergens (OR = 4.2, [95% CI = 2.1-8.5]), or furred animals (OR = 0.6, [95% CI = 0.5-0.9]).

CONCLUSION

These results suggest that there is no association between viral LRTI at < 5 years and the majority of categories of atopy studied during this work. These results, however, are not confirmed for the remaining categories of atopy and more particularly those diagnosed by serum tests. There is a real need to develop more accurate atopy diagnostic tools.

Presence of eosinophils in nasal secretion during acute respiratory tract infection in young children predicts subsequent wheezing within two months

BACKGROUND

In young children with wheezing or bronchiolitis, especially with respiratory syncitial virus, blood eosinophilia and a high eosinophil cationic protein level in nasal secretions predicts subsequent wheezing in later childhood. However, whether eosinophil activation results from virus-induced inflammation or local eosinophilia per se precedes the onset of wheezing remains unknown. In the present study, we examined the association between the presence of nasal eosinophils during respiratory tract infection (RTI) and subsequent wheezing in young children.

METHODS

A total of 35 young children less than 3 years of age who visited our outpatient clinic with rhinorrhea between April and July 2004 were enrolled in this prospective cohort study. Subjects who were given diagnoses of allergic rhinitis were excluded. In all the subjects, the presence of eosinophils in nasal secretions was determined. The subjects were followed, and the cumulative incidences of wheezing during the subsequent 2- and 12-month periods were examined.

RESULTS

According to a logistic regression analysis adjusted for age, sex, family history, allergies, and wheezing at entry, young children with nasal eosinophil infiltration during acute RTI had a significantly higher risk of wheezing during the subsequent 2 months, compared with those without nasal eosinophil infiltration (adjusted odds ratio, 27.618, p = 0.016).

CONCLUSIONS

Our findings not only suggest that nasal eosinophil testing may serve as a convenient clinical marker for identifying young children at risk for subsequent wheezing, but also shed new light on the role of eosinophils in the onset of wheezing in young children.

Novel pathways in the pathogenesis of respiratory syncytial virus disease

Respiratory syncytial virus (RSV) is a leading cause of severe respiratory infections in infants and children. Extensive research in past decades has expanded our knowledge regarding the specific mechanisms involved in the pathogenesis of RSV bronchiolitis and subsequent chronic obstructive airway disease. Studies of RSV infection are performed in humans, cell culture models, and animal models, each with their own specific limitations. A recently developed murine model in which pulmonary dysfunction can be monitored and quantified appears to add a powerful tool for the study of specific pathogenic mechanisms of experimental RSV infections. Both immunologic and nonimmunologic factors have been implicated in the pathogenesis of RSV-induced diseases. Recently, a hypothesis that RSV bronchiolitis may be the result of production of Th2-type cytokines has become popular. There are, however, studies in human infants with RSV as well as in RSV-infected mice that suggest this theory is incorrect, or at least an oversimplification. There is compelling evidence that cells producing interferon gamma may contribute to RSV-induced wheezing, possibly through induction of leukotriene release. Among the nonimmunologic factors, pulmonary surfactant has recently attracted attention, especially because of the therapeutic implications for infants with severe bronchiolitis. A better understanding of the pathogenesis of RSV-induced diseases will be of considerable help in developing specific therapeutic strategies and in vaccine development.

Atopy and pulmonary function abnormalities in children with a history of acute bronchiolitis

To assess the relationship between acute viral bronchiolitis and subsequent development of asthma, we studied retrospectively 97 index children, aged between 9 and 14 years, and 52 controls. The bronchiolitis group showed significantly lower values for mean expiratory flow at 50% of vital capacity (MEF50) higher incidence of atopy, and were more sensitive to methacholine than were controls, even if they had not shown recurrent wheezing episodes. It is suggested that an increased incidence of atopy, bronchial hyperresponsiveness, and reduced expiratory flows may be detectable in children with a history of acute bronchiolitis, regardless of the fact that they did not develop subsequent clinical symptoms suggestive of bronchial asthma.

Childhood viral infection and the pathogenesis of asthma and chronic obstructive lung disease

Many epidemiologic studies have implicated childhood respiratory infections as an independent risk factor for the subsequent development of persistent asthma and chronic obstructive pulmonary disease (COPD). The majority of these childhood infections are viral in origin, and great strides are being made in understanding their pathogenesis at the molecular level. Some viruses, such as respiratory syncytial virus-a common cause of childhood bronchiolitis-stimulate the helper T cell type 2 (Th2) pattern of immune responses associated with allergic inflammation. Other viruses, such as adenovirus, appear to persist as latent infections in the airways of patients with COPD, and adenoviral E1A protein is capable of amplifying host genes, possibly including those involved in cigarette smoke-induced lung inflammation. Studies of the chronic, low-grade peripheral lung inflammation caused by adenoviral infection of guinea pigs will enable examination of the possibility that latent infection may induce resistance to the antiinflammatory actions of corticosteroids. Studies of the molecular mechanisms of viral infections of the airways could provide important insights into the nature of the inflammatory process involved in asthma and COPD. Hogg JC. Childhood viral infection and the pathogenesis of asthma and chronic obstructive lung disease.

Eosinophils and basophilic cells in sputum and nasal smears taken from infants and young children during acute asthma

To examine the increase in eosinophils and basophilic cells in the respiratory areas of infants and young children with asthma (n = 111), we analyzed the numbers of eosinophils and basophilic cells in sputum and nasal smears. The number of children with eosinophilia grades of 2+ or greater (> or = 11 cells/five fields in x1000 magnification) in sputum and nasal smears, respectively, in each age group was as follows: 33% and 21% under 1 year, 59% and 64% at 1 year, and 79-80% and 75-78% at 2-3 years. An increased infiltration of basophilic cells according to age was also observed. Infiltration of these cells began earlier than the appearance of IgE antibodies to mite in blood.

Peripheral blood eosinophil counts and eosinophil cationic protein content of respiratory secretions in bronchiolitis: relationship to severity of disease

Infants and young children with acute viral respiratory illness were studied to determine the association of peripheral blood eosinophil counts and concentrations of eosinophil cationic protein (ECP) in nasopharyngeal secretions with the development and severity of bronchiolitis. Subjects included those with upper respiratory illness (URI) alone, pneumonia or bronchiolitis. Controls consisted of healthy infants, and those hospitalized with non-respiratory illnesses. While peripheral blood eosinophil counts were suppressed in all infected infants greater than two months of age, eosinophil counts in patients with bronchiolitis were significantly greater than in those with URI alone. ECP concentrations were significantly greater among individuals with bronchiolitis than other infected infants. For bronchiolitis cases with detectable peripheral blood eosinophils, eosinophil counts correlated weakly and inversely with oxygen saturations. In contrast, ECP concentrations were strongly inversely correlated with initial oxygen saturation. ECP concentrations were also significantly correlated with peripheral blood eosinophil counts. Viral infections suppress peripheral blood eosinophil counts in infants greater than two months of age, although the effect is somewhat overcome in patients with bronchiolitis. The form and severity of bronchiolitis is much more strongly related to degranulation of eosinophils in the respiratory tract than to peripheral blood eosinophil counts.

The predictive relationship between serum IgE levels at birth and subsequent incidences of lower respiratory illnesses and eczema in infants

Cord serum IgE levels are predictive of subsequent atopic diseases early in life. Lower respiratory illnesses (LRI) have often been included with atopic diseases in infancy but have not been examined as a separate entity for a relation to cord IgE levels. Among 767 healthy newborns in Tucson, Arizona studied longitudinally, cord serum IgE levels were directly related to the subsequent incidence of eczema. In contrast, the incidence of LRI not only failed to show a direct relationship to IgE levels but actually decreased with increasing cord IgE levels from 34.8% in the lowest cord IgE group to 22.2% in the highest IgE group (greater than 1.0 IU/ml IgE; p for trend chi-square less than 0.03). Limiting LRI to those with wheeze did not alter the inverse relationship with IgE levels. The inverse LRI-IgE relationship was strong for non-RSV LRI, whereas RSV LRI had neither a direct nor an inverse relationship. These inverse LRI-IgE relationships were significant for LRI occurring in infants before but not after 6 months of age. Maternal (but not paternal) allergic history was associated with higher cord IgE levels and with an increased incidence of LRI, the latter effect being independent of IgE. This study suggests that most LRI in the first year of life are not early manifestations of an allergic predisposition.

Clinical observations on lower respiratory tract infections with special reference to serum IgE levels

To examine if the occurrence of wheezing among children with lower respiratory tract infections is associated with atopic predisposition, serum levels of IgE were determined for groups of children with or without wheezing, during infection with Mycoplasma pneumoniae or respiratory syncytial virus (RSV). In M. pneumoniae infection, more than 60% of wheezy children over 2 years of age showed a high IgE level (200 IU/mL or more), while IgE levels were less than 200 IU/mL in 73% of non-wheezy children. In RSV infection, the incidence of high IgE levels among wheezy children was nearly double that of non-wheezy children, although the difference was not significant. These results suggest that in children an allergic disposition is involved in the occurrence of wheezing during the course of lower respiratory tract infections.

Total and specific IgE responses in the acute and recovery phases of respiratory infections in children

Total IgE and specific IgE antibodies to common allergens were determined by the enzyme-linked immunosorbent assay in children with Mycoplasma pneumoniae or respiratory syncytial virus (RSV) infections. The decrease of total IgE from the acute to convalescent phase was observed in 105 of 134 (78.4%) children with M. pneumoniae infection and in 40 of 49 (81.6%) of those with RSV infection. Similarly, many patients showed a decrease of the responses of specific IgE in the convalescent phase of the infections. The results indicated that these infections might alter the production of total IgE and IgE specific to common allergens unrelated to the infectious agents.