Piezo channels modulate human lung fibroblast function

Abstract

Bronchial airways and lung parenchyma undergo both static and dynamic stretch in response to normal breathing as well as in the context of insults such as mechanical ventilation (MV) or in diseases such as asthma and chronic obstructive pulmonary disease (COPD) which lead to airway remodeling involving increased extracellular matrix (ECM) production. Here, the role of fibroblasts is critical, but the relationship between stretch- and fibroblast-induced ECM remodeling under these conditions is not well-explored. Piezo (PZ) channels play a role in mechanotransduction in many cell and organ systems, but their role in mechanical stretch-induced airway remodeling is not known. To explore this, we exposed human lung fibroblasts to 10% static stretch on a background of 5% oscillations for 48 h, with no static stretch considered controls. Collagen I, fibronectin, alpha-smooth muscle actin (α-SMA), and Piezo 1 (PZ1) expression was determined in the presence or absence of Yoda1 (PZ1 agonist) or GsMTx4 (PZ1 inhibitor). Collagen I, fibronectin, and α-SMA expression was increased by stretch and Yoda1, whereas pretreatment with GsMTx4 or knockdown of PZ1 by siRNA blunted this effect. Acute stretch in the presence and absence of Yoda1 demonstrated activation of the ERK pathway but not Smad. Measurement of [Ca²⁺]_i responses to histamine showed significantly greater responses following stretch, effects that were blunted by knockdown of PZ1. Our findings identify an essential role for PZ1 in mechanical stretch-induced production of ECM mediated by ERK phosphorylation and Ca²⁺ influx in lung fibroblasts. Targeting PZ channels in fibroblasts may constitute a novel approach to ameliorate airway remodeling by decreasing ECM deposition.NEW & NOTEWORTHY The lung is an inherently mechanosensitive organ that can respond to mechanical forces in adaptive or maladaptive ways, including via remodeling resulting in increased fibrosis. We explored the mechanisms that link mechanical forces to remodeling using human lung fibroblasts. We found that mechanosensitive Piezo channels increase with stretch and mediate extracellular matrix formation and the fibroblast-to-myofibroblast transition that occurs with stretch. Our data highlight the importance of Piezo channels in lung mechanotransduction toward remodeling.

Keywords: ERK signaling; Piezo channels; airway remodeling; human lung fibroblasts; stretch.