Blood eosinophil counts during bronchiolitis are related to bronchial hyper-responsiveness and lung function in early adolescence

Blood eosinophils during bronchiolitis: Associations with atopy, asthma and lung function in young adults

AIM

To study if blood eosinophils during bronchiolitis were associated with atopy, asthma and lung function in young adults and if these associations differed between respiratory syncytial virus (RSV) bronchiolitis and non-RSV bronchiolitis.

METHODS

This historical cohort enrolled 225 subjects. Blood eosinophils were measured during bronchiolitis in infancy, and the subjects were invited to a follow-up at 17-20 years of age including questionnaires for asthma and examinations of lung function and atopy.

RESULTS

The level of eosinophils was positively associated with subsequent atopy in the unadjusted analysis, but not in the adjusted analysis, and not with asthma. There was a negative association between the level of eosinophils and forced vital capacity (FVC) (-0.11; -0.19, -0.02) and forced expiratory volume in first second (FEV₁ ) (-0.12; -0.21, -0.03) (regression coefficient; 95% confidence interval). The non-RSV group had higher levels of eosinophils during bronchiolitis, but there was no interaction between the level of eosinophils and RSV status for any outcome.

CONCLUSIONS

The level of eosinophils during bronchiolitis was negatively associated with lung function in young adult age, but we found no associations with atopy or asthma. These associations were not different after RSV bronchiolitis compared to non-RSV bronchiolitis.

Blood eosinophils, specific immunoglobulin E, and bronchiolitis severity

BACKGROUND

Bronchiolitis is the leading cause of hospitalization for United States infants. Blood eosinophil and serum specific IgE (sIgE) levels are separately linked to clinical severity but few studies have examined these biomarkers together.

OBJECTIVE

Among infants hospitalized for bronchiolitis, we investigated the association between (1) blood eosinophilia and severity, (2) sIgE sensitization and severity, and (3) interaction between the two biomarkers on severity.

METHODS

We enrolled 1016 infants hospitalized for bronchiolitis between 2011 and 2014 across 17 U.S. hospitals into a prospective cohort study. Of those, 873 (86%) had eosinophils measured and all had sIgE levels from blood collected at hospitalization. We investigated higher bronchiolitis severity using intensive care therapy as the outcome (i.e., intensive care unit admission, intubation, and/or receipt of continuous positive pressure ventilation).

RESULTS

Among 873 infants in the analytic cohort, 18% had blood eosinophilia of ≥3%, and 20% were positive for sIgE. With regard to bronchiolitis severity, 15% received intensive care therapy. In unadjusted analyses, eosinophils ≥3% was not associated with intensive care therapy, while sIgE was associated with a significantly higher risk (odds ratio [OR]: 1.44, 95% confidence interval [CI]: 1.08-1.92; p = .01). In a multivariable model for intensive care therapy, eosinophilia remained unassociated with severity, and sIgE remained associated (OR: 1.60, 95% CI: 1.05-2.45; p = .03). Also, sIgE did not modify the association between eosinophil level and intensive care therapy (pinteraction  = .14).

CONCLUSION

Blood eosinophilia of ≥3% was not associated with bronchiolitis severity. By contrast, sIgE was independently associated with bronchiolitis severity and did not modify the association between eosinophil level and severity.

Factors Associated With Asthma Diagnosis Within Five Years of a Bronchiolitis Hospitalization: A Retrospective Cohort Study in a High Asthma Prevalence Population

OBJECTIVES

Bronchiolitis, the leading cause of infant hospitalizations in the United States, is associated with increased risk of childhood asthma. We hypothesized that factors during a bronchiolitis hospitalization were associated with subsequent asthma.

METHODS

This is a retrospective cohort study at an urban, tertiary-care children's hospital of infants <12 months old, hospitalized for bronchiolitis. The primary outcome measure was an asthma diagnosis, defined as a billing code for an asthma visit or a prescription for controller medication, within 5 years of discharge from the bronchiolitis hospitalization.

RESULTS

There were 534 infants hospitalized for bronchiolitis, of which 294 (55.1%) were diagnosed with asthma, and 102 (19.1%) were hospitalized for asthma within 5 years of discharge. There was significant interaction between age and family history. In both models, female sex was protective (odds ratio [OR] 0.46). Age and race were only associated with asthma in infants without a family history of asthma: age (OR 1.19; 95% confidence interval 1.08-1.32) and race (OR 4.06; 95% confidence interval 1.56-10.58). Hospitalization length, ICU stay, albuterol treatments received, supplemental oxygen, respiratory support, highest respiratory rate, and respiratory syncytial virus infection were not associated with asthma diagnosis.

CONCLUSIONS

More than 55% of infants hospitalized for bronchiolitis developed asthma within 5 years of discharge. Demographic and family history variables were independently associated with asthma. However, hospital-based variables during the bronchiolitis hospitalization were not independently associated with asthma. These results can direct further research and differentiate anticipatory guidance for infants with bronchiolitis at risk for asthma.

Severe bronchiolitis profiles and risk of recurrent wheeze by age 3 years

BACKGROUND

A better understanding of bronchiolitis heterogeneity might help clarify its relationship with the development of recurrent wheezing and asthma.

OBJECTIVES

We sought to identify severe bronchiolitis profiles using a clustering approach and to investigate for the first time their association with allergy/inflammatory biomarkers, nasopharyngeal microbiota, and development of recurrent wheezing by age 3 years.

METHODS

We analyzed data from a prospective, 17-center US cohort study of 921 infants (age <1 year) hospitalized with bronchiolitis (2011-2014 winters) with posthospitalization follow-up. Severe bronchiolitis profiles at baseline (hospitalization) were determined by using latent class analysis based on clinical factors and viral etiology. Blood biomarkers and nasopharyngeal microbiota profiles were determined by using samples collected within 24 hours of hospitalization. Recurrent wheezing by age 3 years was defined based on parental report of breathing problem episodes after discharge.

RESULTS

Three severe bronchiolitis profiles were identified: profile A (15%), which was characterized by a history of breathing problems/eczema during infancy and non-respiratory syncytial virus (mostly rhinovirus) infection; profile B (49%), which has the largest probability of respiratory syncytial virus infection and resembled classic respiratory syncytial virus-induced bronchiolitis; and profile C (36%), which was composed of the most severely ill group. Profile A infants had higher eosinophil counts, higher cathelicidin levels, and increased proportions of Haemophilus-dominant or Moraxella-dominant microbiota profiles. Compared with profile B, we observed significantly increased risk of recurrent wheezing in children with profile A (hazard ratio, 2.64; 95% CI, 1.90-3.68) and, to a lesser extent, with profile C (hazard ratio, 1.51; 95% CI, 1.14-2.01).

CONCLUSION

Although longer follow-up is needed, our results might help identify, among children hospitalized for bronchiolitis, subgroups with particularly increased risk of asthma.

Low eosinophils during bronchiolitis in infancy are associated with lower risk of adulthood asthma

BACKGROUND

Infant bronchiolitis may be the first manifestation of asthma.

AIM

To evaluate the association of early-childhood risk or protective factors for asthma and lung function reduction in adults 30 years after bronchiolitis in infancy.

METHODS

Forty-seven former bronchiolitis patients attended the clinical study at the median age of 29.5 years, including doctoral examination and measurement of post-bronchodilator lung function with flow-volume spirometry. Data on early-life risk factors including blood eosinophil counts on admission for bronchiolitis and on convalescence 4-6 weeks after bronchiolitis were available.

RESULTS

Low blood eosinophil count <0.25 × 10E9/l on admission for bronchiolitis was a significant protective factor and high blood eosinophil count >0.45 × 10E9/l on convalescence was a significant risk factor for asthma in adulthood independently from atopic status in infancy. Parental asthma and high blood eosinophil count >0.45 × 10E9/l during bronchiolitis were significant risk factors for irreversible airway obstruction (FEV1/FVC ratio below the 5th percentile lower limit of normality after bronchodilation).

CONCLUSION

Our adjusted analyses confirmed that eosinopenia during infant bronchiolitis predicted low asthma risk and eosinophilia outside infection predicted high asthma risk up to the age of 28-31 years. Parental asthma and eosinophilia during bronchiolitis were recognized as risk factors for irreversible airway obstruction.

Inhaled budesonide protects against chronic asthma-induced neuroinflammation in mouse brain

Chronic asthma is one of the most common respiratory diseases, characterized by airway inflammation. However, little is known whether asthma-induced airway inflammation might influence the brain. We found that chronic asthma not only resulted in peripheral inflammation, but also induced neuroinflammation which was characterized by microglial activations and increased levels of TNFα and IL-1β in the hippocampus and prefrontal cortex. Simultaneously, we found that there was significant neuronal loss in the asthmatic mouse brain. Inhaled budesonide, the classic therapeutic drug for chronic asthma, could inhibit asthma-induced microglial activation, down-regulate TNFα and IL-1β but up-regulate TGFβ and IL-10 of mouse brain, and thereby attenuate neuronal loss. Further study showed that chronic asthma increased the expressions of TLR4 and p65/NFκB in the brain, which could be reversed by budesonide treatment. Therefore, the present study reveals that inhaled budesonide protects against asthma-induced neuroinflammation in mouse brain, which might be contributed to attenuate neuronal loss.