# Interkingdom signaling elicited by bacterial extracellular vesicles in human cystic fibrosis airway epithelium and neutrophils

## TL;DR

This study explores how bacteria communicate with human cells in the lungs of people with cystic fibrosis through tiny particles called extracellular vesicles.

## Contribution

It is the first to show that bacterial extracellular vesicles can influence human airway epithelial and neutrophil responses in cystic fibrosis.

## Key findings

- Bacterial and host extracellular vesicles coexist in cystic fibrosis airway fluids.
- Exposure to Pseudomonas aeruginosa extracellular vesicles alters host cell vesicle release and neutrophil phenotype.
- Modifications in bacterial vesicle content affect host cell responses in cystic fibrosis.

## Abstract

Defects in epithelial host defense and dysfunctional neutrophilic inflammation in the presence of sustained bacterial infection underpin chronic lung disease in cystic fibrosis (CF). Deciphering mechanisms on how bacteria interact with the host to establish chronic infection is critical for disease control in people with CF (pwCF).

We sought to investigate the co-existence of microbial and host extracellular vesicles (EVs) in CF airway fluids and evaluate if bacterial EVs from Pseudomonas (P.) aeruginosa impact EV release by host cells (epithelia and neutrophils) from pwCF.

EVs from sputum and bronchoalveolar lavage fluid from pwCF (n = 26 samples total) were characterized by nanoparticle tracking analysis (NTA) and mass spectrometry (MS)-based proteomics. The impact of EVs from P. aeruginosa (wild-type and select mutant strains) on functional responses of human epithelial cultures derived from pwCF and control subjects (n = 8) and human neutrophils transmigrated into CF and control lung conditions (n = 3) was examined using NTA and MS, and flow cytometry, respectively.

We observed the co-existence of bacterial and host EVs in airway fluid from pwCF. Functionally, exposure to EVs from wild-type P. aeruginosa impacted the number and content of host EVs released from epithelia of pwCF and the surface phenotype of lung-conditioned neutrophils. Furthermore, mutations modifying the content of P. aeruginosa EVs impacted host epithelial EV release and neutrophil phenotype.

This proof-of-concept study suggests host–bacterial interplay via EVs in CF airways.