Insight into Rhinovirus-Induced Asthma Exacerbation Using High-Throughput Immunosequencing of B-Cell Repertoires

Rationale: Viral infections, particularly by the common cold rhinovirus (RV), increase risk and severity of asthma exacerbations. We hypothesize that RV infections affect the IgE repertoire and intensify IgE-mediated allergic reactions in asthmatic patients.

Methods: Fifteen healthy and 16 moderate asthmatic subjects were experimentally infected with RV-16. Total B cells bronchial biopsies and bronchoalveolar lavage and 5 B-cell populations (naïve cells, three memory subsets, and plasmablasts distinguished by CD27, IgD, CD38 expression using flow cytometry) in the blood were collected at baseline (day -14) and post- RV infection (day +3 and day +8). The immunoglobulin (Ig) heavy-chain genes in a total of 152 samples were sequenced on the Illumina 2x300 MiSeq system. Multiple bioinformatics tools were employed to analyse Ig repertoires including IMGT/HighV-QUEST and other tailored Ig repertoire analysis software (e.g.BASELINe). 

Results: Over 6 million unique productive sequences (IgA, IgG, IgE and IgM) were included after stringent quality-control filtering. Baseline IgE clones in asthmatics were distinguished from those in healthy subjects with different Ig gene usage, more selection and higher hypermutaitons (p<0.0001). Post-infection IgE sequences with higher hypermutaitons and clonal relatives to baseline IgE repertoires were observed in asthmatic but not in healthy subjects. Temporal dynamics and compartmental connections of B-cell clones, differing between asthmatic and healthy subjects, suggests a significant involvement of IgG clones in IgE-mediated immune responses in asthmatic patients. 

Conclusions: Our high-throughput immunosequencing of B-cell repertoires revealed that RV infection exacerbated IgE responses in asthmatic patients, leading to higher serum IgE levels associated with their clinical symptoms.