IL-13 and IL-17A Activate β1 Integrin through an NF-kB/Rho kinase/PIP5K1γ pathway to Enhance Force Transmission in Airway Smooth Muscle

Abstract

ABSTRACTIntegrin activation resulting in enhanced adhesion to the extracellular matrix plays a key role in fundamental cellular processes. Although G-protein coupled receptor-mediated integrin activation has been extensively studied in non-adherent migratory cells such as leukocytes and platelets, much less is known about the regulation and functional impact of integrin activation in adherent stationary cells such as airway smooth muscle. Here we show that two different asthmagenic cytokines, IL-13 and IL-17A, activate type I and IL-17 cytokine receptor families respectively, to enhance adhesion of muscle to the matrix. These cytokines also induce activation of β1 integrins as detected by the conformation-specific antibody HUTS-4. Moreover, HUTS-4 binding is significantly increased in the smooth muscle of patients with asthma compared to healthy controls, suggesting a disease-relevant role for aberrant integrin activation. Indeed, we find integrin activation induced by a β1 activating antibody, the divalent cation manganese, or the synthetic peptide β1-CHAMP, dramatically enhances force transmission in collagen gels, mouse tracheal rings, and human bronchial rings even in the absence of cytokines. We further demonstrate that cytokine-induced activation of β1 integrins is regulated by a common pathway of NF-kB-mediated induction of RhoA and its effector Rho kinase, which in turn stimulates PIP5K1γ-mediated synthesis of PIP2resulting in β1 integrin activation. Taken together, these data identify a previously unknown pathway by which type I and IL-17 cytokine receptor family stimulation induces functionally relevant β1 integrin activation in adherent smooth muscle and help explain the exaggerated force transmission that characterizes chronic airways diseases such as asthma.SIGNIFICANCE STATEMENTIntegrin activation plays a central role in regulating cellular adhesion and migration. While chemokine-mediated integrin activation has been extensively studied in circulating cells, the role and impact of other cytokine families on non-migratory cells remains incompletely characterized. Here, we demonstrate in airway smooth muscle that asthmagenic cytokines IL-13 and IL-17A stimulate type I and IL-17 cytokine receptor families to induce β1 integrin activation and enhance adhesion. We also identify a common pathway linking NF-kB/RhoA/Rho kinase with PIP5K1γ/PIP2/β1 integrin activation. We show that airway biopsies from asthmatic patients have increased active β1 integrin staining in the muscle, and furthermore that β1 integrin activation alone dramatically enhances force transmission, underscoring the disease-relevant impact of cytokine-mediated integrin activation in adherent muscle.