Integrin α2β1 regulates collagen I tethering to modulate hyperresponsiveness in reactive airway disease models.

Severe asthma remains challenging to manage with limited treatment options. We have previously shown that targeting smooth muscle integrin α5β1 interaction with fibronectin can mitigate the effects of airway hyperresponsiveness by impairing force transmission. In this paper we show that another member of the integrin superfamily, integrin α2β1, is present in airway smooth muscle and capable of regulating force transmission via cellular tethering to the matrix protein collagen I, and to a lesser degree, laminin-111. The addition of an inhibitor of integrin α2β1 impaired IL-13-enhanced contraction in mouse tracheal rings and human bronchial rings, and abrogated the exaggerated bronchoconstriction induced by allergen sensitization and challenge. We confirmed that this effect was not due to alterations in classic intracellular myosin light chain phosphorylation regulating muscle shortening. Although IL-13 did not affect surface expression of α2β1, it did increase α2β1-mediated adhesion and the level of expression of an activation-specific epitope on the β1 subunit. We developed a method to simultaneously quantify airway narrowing and muscle shortening using two-photon microscopy and demonstrated that inhibition of α2β1 mitigated IL-13-enhanced airway narrowing without altering muscle shortening by impairing the tethering of muscle to the surrounding matrix. Our data identify cell-matrix tethering as an attractive therapeutic target to mitigate the severity of airway contraction in asthma.