Mechanism of bronchopulmonary C-fiber hyperexcitability in allergic asthma: Loss of TRPV1 inhibition by GDNF downregulation?

Sensory C-fibers activation contributes to several symptoms in allergic asthma, e.g. cough, dyspnea and bronchoconstriction. Many environmental irritants that cause asthma attacks (including ozone, cold air, cigarette smoke) are ligands of the transient receptor potential (TRP) channel family members that includes TRPV1. Therefore, it has been speculated that dysfunction of TRP channels is responsible for the enhanced excitability of sensory C-fibers. Nerve Growth Factor (NGF) is known to regulate TRPV1 responses in C-fibers located in dorsal root ganglia. However, the majority of bronchopulmonary C-fibers is de…