IL-5Rα marks nasal polyp IgG4 and IgE-secreting cells in aspirin-exacerbated respiratory disease
Authors: Buchheit Kathleen M. , Dwyer Daniel F. , Ordovas-Montanes Jose , Katz Howard R. , Lewis Erin , Lai Juying , Bhattacharyya Neil , Shalek Alex K. , Barrett Nora A. , Boyce Joshua A. , Laidlaw Tanya M. 
Published: January 2019

Background

The cause of nasal polyposis in aspirin-exacerbated respiratory disease (AERD) is unknown. Elevated antibody levels have been associated with disease severity in nasal polyps, but the upstream drivers and cellular mechanisms of local antibody production in AERD remain to be investigated.

Objective

We sought to identify the upstream drivers and phenotypic properties of local antibody-secreting cells in nasal polyps and to understand their clinical relevance in AERD.

Methods

Sinus tissue was obtained from subjects with AERD, aspirin-tolerant chronic rhinosinusitis with nasal polyps (CRSwNP), aspirin-tolerant chronic rhinosinusitis without nasal polyps (CRSsNP), and healthy controls. Tissue antibody levels were quantified via ELISA and immunohistochemistry, and were correlated with clinical markers of disease severity. Tissue cytokine mRNA levels were measured with quantitative PCR (qPCR). Antibody-secreting cells were profiled with a combination of single-cell RNA-sequencing (scRNA-seq), flow cytometry and immunofluorescence.

Results

Tissue IgE and IgG4 were elevated in AERD compared to controls (p<0.01 for IgE and p<0.001 for IgG4, vs. CRSwNP). Total IgG and IgG4 positively correlated with the number of polyp surgeries per subject (r=0.48, p=0.011 and r=0.58, p=0.0003, respectively). Polyp IL-10 mRNA expression was higher in AERD vs. CRSwNP (p<0.05), but there were no differences in mRNA expression of type 2 cytokines. ScRNA-seq revealed increasedIL5RA,IGHG4, andIGHEin the antibody-associated cells of subjects with AERD compared to CRSwNP. Total plasma cells and IL-5Rα+plasma cell numbers in the polyp tissue from AERD exceeded those in polyps from CRSwNP (p=0.0051 and p=0.026, respectively) by flow cytometry. With immunofluorescence, we determined that IL-5Rα and IgG4 are co-expressed in antibody-secreting cells in AERD.

Conclusions

Our study identifies unique clusters of antibody-secreting cells in AERD defined by enrichment of transcripts encodingIL5RA,IGHG4andIGHE. We confirm surface expression of IL-5Rα on these cells, and identify T cells as a unique transcriptional source of IL-5. Tissue antibody levels are elevated in AERD and correlate with disease severity. Our findings suggest a role for IL-5 in facilitating local antibody production that may drive features of severe sinus disease.

Key Messages

IgG4 and IgE levels are markedly increased in nasal polyp tissue from subjects with AERD compared to aspirin-tolerant CRSwNP.

Tissue IgG4 levels positively correlate with disease recurrence.

IL-10 mRNA levels are significantly higher in AERD polyp tissue compared to CRSwNP tissue, but differences were not noted for type 2 cytokines or cytokines involved in class switch recombination.

IL-5Rα transcript and protein surface expression is elevated in antibody-secreting cells from subjects with AERD and may play a role in facilitating class switching and/or survival of antibody-secreting cells.

Capsule Summary

Single-cell RNA-sequencing (scRNA-seq) of whole nasal polyp tissue identified increasedIL5RA,IGHE, andIGHG4expression in the antibody-secreting cell compartment of subjects with aspirin-exacerbated respiratory disease (AERD) compared to aspirin-tolerant chronic rhinosinusitis with nasal polyps (CRSwNP). IgE and IgG4 levels are elevated in nasal polyp tissue from subjects with AERD compared to CRSwNP and correlate with disease recurrence.