The activation of C-fibers in the airways induces coughing, mucus production and bronchoconstriction, which are also symptoms of airway diseases. In this study, we evaluated the role of the C-fibers and the TRPV1 (transient receptor potential vanilloid 1) receptor in an experimental mouse model of allergic airway
inflammation. To study the role of C-fibers, we either degenerated the C-fibers persistently (
capsaicin administration in neonate mice) or transiently (
capsaicin administration in adult mice). No alteration was observed in eosinophil recruitment to the bronchoalveolar lavage fluid in animals treated with
capsaicin in the neonatal period. However, in adult animals,
capsaicin treatment after the first
ovalbumin challenge (in the establishment of the inflammatory process) decreased the eosinophil numbers. This effect was more pronounced in adult animals treated with
capsaicin before beginning the
ovalbumin immunization (in the development of the inflammatory process). In addition,
interleukin (IL)-5 and
chemokine ligand 11 (CCL11) levels in the bronchoalveolar lavage fluid, as well as
P-selectin expression and p65 nuclear factor κB (NF-κB) activation in the lung were also decreased. No alterations were observed in the
IL-10 and
IL-13 levels. Next we determined the effect of
TRPV1 receptor blockade on allergic airway
inflammation.
SB366791 administrated in mice by intraperitoneal (500μg/kg) or intranasal (0.1, 1 or 10nmol/site) route failed to decrease eosinophil recruitment to the bronchoalveolar lavage fluid or alter any other metrics cited above. Thus, the present results confirm and extend previous data supporting the involvement of C-fibers, but not the
TRPV1 receptor, in allergic airway
inflammation.