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Katja Koeppen1, Amanda Nymon1, Roxanna Barnaby1
1Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire.
Abstract:
Mutations in CFTR alter macrophage responses, for example, by reducing their ability to phagocytose and kill bacteria. Altered macrophage responses may facilitate bacterial infection and inflammation in the lungs, contributing to morbidity and mortality in cystic fibrosis (CF). Extracellular vesicles (EVs) are secreted by multiple cell types in the lungs and participate in the host immune response to bacterial infection, but the effect of EVs secreted by CF airway epithelial cells (AEC) on CF macrophages is unknown. This report examines the effect of EVs secreted by primary AEC on monocyte-derived macrophages (MDM) and contrasts responses of CF and wild type (WT) MDM. We found that EVs generally increase pro-inflammatory cytokine secretion and expression of innate immune genes in MDM, especially when EVs are derived from AEC exposed to Pseudomonas aeruginosa and that this effect is attenuated in CF MDM. Specifically, EVs secreted by P. aeruginosa exposed AEC (EV-PA) induced immune response genes and increased secretion of proinflammatory cytokines, chemoattractants, and chemokines involved in tissue repair by WT MDM, but these effects were less robust in CF MDM. We attribute attenuated responses by CF MDM to differences between CF and WT macrophages because EVs secreted by CF AEC or WT AEC elicited similar responses in CF MDM. Our findings demonstrate the importance of AEC EVs in macrophage responses and show that the Phe508del mutation in CFTR attenuates the innate immune response of MDM to EVs.
Insights
Cystic fibrosis (CF) airway epithelial cell extracellular vesicles (EVs) impair macrophage immune responses. The Phe508del mutation in CFTR reduces how well macrophages fight Pseudomonas aeruginosa infections and inflammation in CF lung disease.
Area of Science:
- Immunology
- Cell Biology
- Genetics
Background:
- Mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene impact macrophage function, potentially worsening bacterial infections and inflammation in cystic fibrosis (CF) lung disease.
- Extracellular vesicles (EVs) from lung cells are involved in immune responses, but their specific role in CF lung immunity is unclear.
Purpose of the Study:
- To investigate the impact of EVs secreted by primary airway epithelial cells (AEC) on monocyte-derived macrophages (MDM).
- To compare the responses of CF MDM versus wild-type (WT) MDM to AEC-derived EVs, particularly after exposure to Pseudomonas aeruginosa.
Main Methods:
- Primary AEC from CF and WT individuals were cultured and exposed to P. aeruginosa.
- EVs were isolated from AEC cultures.
- MDM were treated with AEC-derived EVs.
- Macrophage responses, including cytokine secretion and innate immune gene expression, were analyzed.
Main Results:
- EVs generally enhanced pro-inflammatory cytokine secretion and innate immune gene expression in MDM.
- This pro-inflammatory effect was more pronounced when EVs were derived from P. aeruginosa-exposed AEC.
- CF MDM exhibited attenuated responses to EVs compared to WT MDM, irrespective of the EVs' origin (CF or WT AEC).
- The Phe508del mutation in CFTR was identified as a key factor in the attenuated MDM response to EVs.
Conclusions:
- AEC-derived EVs play a significant role in modulating macrophage immune responses.
- The CFTR Phe508del mutation attenuates the innate immune response of MDM to EVs, contributing to impaired host defense in CF.
- Understanding these EV-mediated interactions is crucial for developing novel therapeutic strategies for CF lung disease.
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