Effects of aclidinium on cigarette smoke-induced fibroblast activation in vitro

Introduction: Lung fibroblast activation in chronic obstructive pulmonary disease (COPD) results in expression of α-smooth muscle actin (αSMA) and collagen type I. Cigarette smoke (CS) promotes lung fibroblast proliferation via cholinergic system activation. Aims: To assess the effects of aclidinium bromide, a novel, long-acting muscarinic antagonist, on human lung fibroblast activation after CS exposure in vitro . Methods: Lung fibroblasts were incubated with aclidinium (10 -9 M-10 -7 M), the ERK 1/2 inhibitor PD98059 (10μM), the cAMP analogue dbcAMP (1mM) or the antioxidants N-acetylcisteine (NAC; 1mM) and apocynin (100μM) for 30 min and then exposed to CS extract (CSE) for 48 h. Collagen type I, αSMA expression and ERK 1/2 phosphorylation were measured by RT-PCR and/or Western blot (WB). Intracellular reactive oxygen species (ROS) were measured by DCFDA fluorescence dye. Protein expression by the NADPH complex gp67phox and choline acetyltransferase (ChAT) were measured by WB. Results: Aclidinium, PD98059, dbcAMP, NAC and apocynin attenuated the CSE-induced increase in αSMA and collagen type I expression. Aclidinium also attenuated the CSE-dependent increase in Phospho-ERK and the CSE-induced increase in ROS to 50% of control. NAC and apocynin fully suppressed the increase in ROS, and PD98059 and dbcAMP reduced it to 20% of control. Aclidinium 10 -7 M completely suppressed the CSE-induced increase in gp67phox expression. A CSE-induced ChAT upregulation suggested an autocrine acetylcholine regulation in response to CSE. Conclusions: Aclidinium reduces human lung fibroblast activation following CSE exposure in vitro . Aclidinium may reduce lung fibroblast activation in patients with COPD after CS exposure.