Piezo1 mediates stretch-induced Wnt/β-catenin signaling and extracellular matrix remodeling in aging asthmatic airway smooth muscle.

Asthma in the elderly (AIE) represents a unique challenge, necessitating a better understanding of the mechanisms that drive airway hyperreactivity and remodeling (thickened, fibrotic airways). Normal aging is associated with increased lung stiffness, and thus the influence of mechanical forces on bronchial airways (breathing, sighs, CPAP) likely changes, potentially increasing with AIE and resultant remodeling, overall highlighting the need to understand the importance of mechanobiology in aging and AIE. Here, mechanosensitive Piezo (Pz) channels are highly expressed in the lung, including within airway epithelium and smooth muscle (ASM), but their specific roles, particularly with aging, remain largely unexplored. In this study, we used human ASM cells from young vs old (≥65 y) non-asthmatics vs asthmatics to test the hypothesis that normal aging blunts Pz expression and functionality at baseline as well as in response to mechanical stretch, whereas asthma, particularly, AIE ASM leads to enhanced Pz expression promoting fibrosis and remodeling. Both Pz1 and Pz2 were expressed in ASM and increased in AIE. Oscillatory mechanical stretch mimicking breathing with superimposed static stretch increased Pz, especially in AIE: effects exacerbated by Pz activator Yoda1 and blunted by Pz inhibitor GsMTx4. Stretch or Yoda1 increased Wnt3a, β-catenin, and GSK3β activation, particularly in AIE, while ASM proliferation and extracellular matrix production remained preserved or even heightened in elderly ASM. Conversely, Pz1 inhibition by GsMTx4 potently reduced extracellular matrix (ECM) deposition, particularly in AIE cells, highlighting Pz1's pivotal role in modulating ECM deposition. Overall, our findings indicate Pz1 as a mechanosensitive regulator of airway remodeling in AIE.