Abstract
Dendritic cell (DC) trafficking from lung to the draining mediastinal lymph nodes (MLNs) is a key step for initiation of T cell responses in allergic asthma. In the present study, we investigate the role of DC-mediated airway inflammation after inhibition of p21-activated kinase-1 (PAK1), an effector of Rac and Cdc42 small GTPases, in the allergen-induced mouse models of asthma. Systemic administration of PAK1 specific inhibitor IPA-3 significantly attenuates not only the airway inflammation but also the airway hyperresponsiveness in a mouse model of ovalbumin-induced asthma. Specifically, intratracheal administration of low dosage of IPA-3 consistently decreases not only the airway inflammation but also the DC trafficking from lung to the MLNs. Importantly, intratracheal instillation of IPA-3-treated and ovalbumin-pulsed DCs behaves largely the same as that of either Rac inhibitor-treated and ovalbumin-pulsed DCs or Cdc42 inhibitor-treated and ovalbumin-pulsed DCs in attenuation of the airway inflammation in ovalbumin-challenged mice. Mechanistically, PAK1 is not involved in the maturation, apoptosis, antigen uptake, and T cell activation of cultured DCs, but PAK1 dose lie on the downstream of Rac and Cdc42 to regulate the DC migration toward the chemokine C-C motif chemokine ligand 19. Taken together, this study demonstrates that inhibition of PAK1 attenuates the cardinal features of asthma through suppressing the DC trafficking from lung to the MLN, and that interfere with DC trafficking by a PAK1 inhibitor thus holds great promise for the therapeutic intervention of allergic diseases.