CFTR Modulators Restore Acidification of Autophago-Lysosomes and Bacterial Clearance in Cystic Fibrosis Macrophages

Area of Science:

• Cell Biology
• Immunology
• Genetics

Background:

• Cystic fibrosis (CF) macrophages exhibit impaired bacterial clearance, particularly of Burkholderia cenocepacia.
• The autophagy pathway is defective in CF (F508del) macrophages, with the precise mechanism remaining elusive.
• The role of the cystic fibrosis transmembrane conductance regulator (CFTR) in lysosomal and endosomal acidification in CF cells is debated.

Purpose of the Study:

• To investigate the role of CFTR in the autophagy pathway and lysosomal acidification in CF macrophages.
• To determine if CFTR modulators can restore autophagic function and bacterial clearance in CF macrophages.

Main Methods:

• 3D reconstruction of z-stack confocal images to visualize CFTR recruitment to autophagosomes.
• Complementary biochemical and imaging approaches to assess lysosomal acidification and degradative function.
• Patch-clamp electrophysiology to confirm CFTR function after modulator treatment.

Main Results:

• CFTR was observed to be recruited to autophagosomes containing B. cenocepacia.
• CF macrophages showed defective lysosomal acidification and cargo degradation specifically for autophagosomal contents.
• Treatment with CFTR modulators (tezacaftor/ivacaftor) restored autophagy flux, lysosomal acidification, bacterial clearance, and CFTR function.

Conclusions:

• CFTR regulates the acidification of a specific subset of lysosomes involved in autophagosome fusion.
• This study identifies a novel role for CFTR in autophagolysosomes, clarifying previous discrepancies in CF research.
• CFTR modulators hold therapeutic potential for restoring macrophage function in cystic fibrosis.