Airway Exosomes from Asthmatics Modulate Differential T Helper Responses
Saturday, March 4, 2017: 2:00 PM
Rooms B213-B214 (Georgia World Congress Center, Building B)
Jessy Deshane, PhD, , , , , , , , , , , , , ,
Rationale: Recent studies have illustrated a role for exosomes (nano-sized membrane vesicles) in the pathogenesis of various diseases. We hypothesize the potential for airway exosomes to mediate CD4+T cell activation and polarization. Furthermore, we characterize unique lipid compositions of airway exosomes from asthmatics and healthy controls.

Methods: Exosomes were isolated from the bronchoalveolar lavage fluid (BALF) of healthy (n=9) or asthmatic (n=11) subjects. Exosomes were then characterized by transmission electron microscopy, Nanosight nanoparticle tracking, flow cytometry, and the AMNIS ImageStream. Proliferation and polarization of CD4+T lymphocytes were assessed by co-culturing exosomes with purified autologous T cells. Lipids were extracted from exosomes using methanol:chloroform (2:1) with 5mM ammonium acetate. Untargeted lipidomics was performed on the exosomes using a SCIEX 5600 TripleTof mass spectrometer in both positive and negative modes, and SWATH analysis was performed using a mass evaluation range of 200-1200 m/z.

Results: Airway exosomes isolated from mild asthmatics displayed a heterogeneous population of particles varying in size and granularity. Flow cytometry analyses demonstrated higher expression of HLA-DR, CD54, and CD36 in exosomes from asthmatics. Airway exosomes from asthmatics promoted CD4+T lymphocyte proliferation and enhanced Th2 and Th17 polarization. SWATH lipidomics analysis revealed significantly higher levels of phosphatidylcholines and sphingomyelin in airway exosomes from asthmatics.

Conclusions: Unique lipid species that are known to play a role in inflammation are significantly different in exosomes isolated from asthmatics. Furthermore, airway exosomes from asthmatics can enhance Th2 and Th17 polarization, suggesting a novel role in asthma pathogenesis.