Platelet Activation Through TRPC6 Mediates Cystic Fibrosis Lung Inflammation and Injury

Introduction. Cystic Fibrosis (CF) lung disease presents with an early, exaggerated inflammatory response, which impairs bacterial clearance. Platelets mediate inflammation through activation, signaling, and cross-talk with neutrophils. We previously showed that deletion of CFTR in platelets results in a hyperinflammatory yet impaired immune response in CF mouse models, which can be rescued by pharmacologic or genetic inhibition of the Transient Receptor Potential Cation Channel 6 (TRPC6). Here, we investigate the role platelet-neutrophil interactions such as neutrophil-platelet aggregation (NPAs) and NETosis in CF mouse models.

Methods. We generated conditional CFTR knockouts in which CFTR^fl/fl mice were crossed with LysM-Cre (CF-LysM) or MRP8-Cre (CF-MRP8) to delete CFTR in myeloid cells or neutrophils, respectively, and PF4-Cre (CF-PF4) to delete CFTR in platelets. We generated a global double knockout of CFTR and TRPC6 (CFTR^-/- TRPC6^-/-). Mice were challenged with intratracheal LPS or Pseudomonas aeruginosa (PsA). Markers of inflammation, bacterial cfu, NPAs, and NETs were quantified at 48 hrs.

Results. CFTR^-/- and CF-PF4 mice demonstrated a hyperinflammatory yet impaired immune response in LPS and PsA models as well as increased NPAs and NETs. CF-LysM and CF-MRP8 mice did not exhibit this hyperinflammatory response. Genetic inhibition of the TRPC6 in the CFTR^-/- TRPC6^-/- double knockout mice normalized inflammation, bacterial clearance, and decreased NETosis.

Conclusions. CFTR deletion in platelets results in a pathologic and impaired inflammatory response, which is attenuated by TRPC6 inhibition. Platelet activation mediates lung inflammation through increased NPAs and NETs. Modulating platelet activation and TRPC6 may be new therapeutic targets for treating CF.