<strong class=""boldFont"">They may be caused by injury to the respiratory epitheliumstrong> in a chronic inflammatory environment.
<strong class=""boldFont"">Several studies show that during NP nasal epithelial cellsstrong> are involved in the overexpression of cytokines and growth factors.
<strong class=""boldFont"">Among these, transforming growth factor |1 (TGF-|1)strong> appears to play a major role in the genesis of NP.
<strong class=""boldFont"">Differentiated respiratory epithelium,strong> obtained from in vivo or in vitro models, is used to study wound healing in inflammatory environments, to elucidate the pathophysiology of NP, and to improve understanding and management of upper airway inflammatory diseases.