Bronchiolitis needs a revisit: Distinguishing between virus entities and their treatments

Abstract

Current data indicate that the “bronchiolitis” diagnosis comprises more than one condition. Clinically, pathophysiologically, and even genetically three main clusters of patients can be identified among children suffering from severe bronchiolitis (or first wheezing episode): (a) respiratory syncytial virus (RSV)‐induced bronchiolitis, characterized by young age of the patient, mechanical obstruction of the airways due to mucus and cell debris, and increased risk of recurrent wheezing. For this illness, an effective prophylactic RSV‐specific monoclonal antibody is available; (b) rhinovirus‐induced wheezing, associated with atopic predisposition of the patient and high risk of subsequent asthma development, which may, however, be reversed with systemic corticosteroids in those with severe illness; and (c) wheeze due to other viruses, characteristically likely to be less frequent and severe. Clinically, it is important to distinguish between these partially overlapping patient groups as they are likely to respond to different treatments. It appears that the first episode of severe bronchiolitis in under 2‐year‐old children is a critical event and an important opportunity for designing secondary prevention strategies for asthma. As data have shown bronchiolitis cannot simply be diagnosed using a certain cutoff age, but instead, as we suggest, using the viral etiology as the differentiating factor.

Rhinovirus Type in Severe Bronchiolitis and the Development of Asthma

“…11 Similarly, genetic factors can modify the risk of RSV bronchiolitis and development of asthma. 10 Our finding of strong association of both RV-Ae and RV-Ceinduced bronchiolitis with the use of asthma control medication 4 years later is consistent with previous RV studies. In a recent meta-analysis including 15 original articles, the association between RV-induced wheezing and later development of asthma was confirmed.…”

“…8,11,21,22,31 Finally, RV infection can inhibit IFN responses and potentiate T H 2-celledriven inflammation and production of cytokines, which promote airway obstruction and wheeze. 10 Atopic characteristics are not seen as a risk factor for RSV-induced wheezing and asthma, which is more linked to young age and low lung function, indicating that the timing of RSV infection may be important for the future development of respiratory illnesses. 11 Similarly, genetic factors can modify the risk of RSV bronchiolitis and development of asthma.…”

“…28,33,34 Early-life RV wheezing illnesses and aeroallergen sensitization increase the risk of asthma. 10,11 In a high-risk birth cohort, the persistence of asthma at age 13 years has been shown to be strongly and additively associated with RV wheezing illness and aeroallergen sensitization in early life. 8 In accordance, we show that histories of wheezing, atopic dermatitis, and RV-Ae and RV-Ceinduced bronchiolitis were independently associated with the initiation and the current use of asthma control medications 4 years later.…”

“…3,6 In follow-up studies, RV-induced bronchiolitis/early wheezing illness has been highly associated Abbreviations used aHR-Adjusted hazard ratio aOR-Adjusted odds ratio HR-Hazard ratio OR-Odds ratio RSV-Respiratory syncytial virus RV-Rhinovirus with the development of asthma. [7][8][9][10][11] Whether it is the RV infection itself or the immunologic responses of the child, which primarily enhance the development, is still partly unknown. Furthermore, it is unclear whether the RV types involved with bronchiolitis have different risks associated with the later development of asthma.…”

“…RVs cause 20% to 40% of bronchiolitis and 50% to 80% of wheezing episodes and asthma exacerbations in children. 10,12,13 RV types are classified into 3 species: RV-A, RV-B, and RV-C. 14 RV-A and RV-C cause more severe respiratory illness than RV-B and are associated with wheezing in early childhood, 14 as well as exacerbations of asthma. [15][16][17][18][19] Cadherin-related family member 3 (a receptor for RV-C) and atopy have been shown to be risk factors for the development of early-onset asthma.…”