Targeting integrin α₅β₁ ameliorates severe airway hyperresponsiveness in experimental asthma

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Abstract

Treatment options are limited for severe asthma, and the need for additional therapies remains great. Previously, we demonstrated that integrin α_vβ₆-deficient mice are protected from airway hyperresponsiveness, due in part to increased expression of the murine ortholog of human chymase. Here, we determined that chymase protects against cytokine-enhanced bronchoconstriction by cleaving fibronectin to impair tension transmission in airway smooth muscle (ASM). Additionally, we identified a pathway that can be therapeutically targeted to mitigate the effects of airway hyperresponsiveness. Administration of chymase to human bronchial rings abrogated IL-13–enhanced contraction, and this effect was not due to alterations in calcium homeostasis or myosin light chain phosphorylation. Rather, chymase cleaved fibronectin, inhibited ASM adhesion, and attenuated focal adhesion phosphorylation. Disruption of integrin ligation with an RGD-containing peptide abrogated IL-13–enhanced contraction, with no further effect from chymase. We identified α₅β₁ as the primary fibronectin-binding integrin in ASM, and α₅β₁-specific blockade inhibited focal adhesion phosphorylation and IL-13–enhanced contraction, with no additional effect from chymase. Delivery of an α₅β₁ inhibitor into murine airways abrogated the exaggerated bronchoconstriction induced by allergen sensitization and challenge. Finally, α₅β₁ blockade enhanced the effect of the bronchodilator isoproterenol on airway relaxation. Our data identify the α₅β₁ integrin as a potential therapeutic target to mitigate the severity of airway contraction in asthma.

Authors

Aparna Sundaram, Chun Chen, Amin Khalifeh-Soltani, Amha Atakilit, Xin Ren, Wenli Qiu, Hyunil Jo, William DeGrado, Xiaozhu Huang, Dean Sheppard