| The prevalence and economic burden of chronic airway disorders such as asthma is on the rise annually. Allergic asthma is characterized by chronic airway inflammation, airway hyper-responsiveness (AHR), and structural airway remodeling due to increased smooth muscle mass. Most allergic asthma occurs due to the overproduction of immunoglobulin E (IgE) antibodies against common allergens. Classically, IgE has been shown to modulate airway smooth muscle (ASM) contraction/relaxation which is believed to be the underlying cause of airway hyperreactivity. However, the molecular mechanisms underlying IgE effects on ASM cell are not established.;Recently, the high-affinity Fc receptor for IgE (FcepsilonRI) has been identified in human ASM cells in vitro and in vivo within bronchial biopsies of allergic asthma patients. However, it is unknown whether FcepsilonRI activation on ASM can modulate the immune response within the airways. We hypothesized that the IgE-FcepsilonRI interaction plays a key role in inducing phenotypic and functional changes in ASM cells that eventually contributes to the establishment of airway inflammation, AHR, and remodeling. We sought to investigate the regulation, effector functions, and underlying mechanisms of FcepsilonRI activation in ASM cells. Our work shows that the proinflammatory tumor necrosis factor (TNF) and T helper type 2 (Th2) cytokine interleukin (IL)-4 enhanced the FcepsilonRI abundance and amplified the IgE-induced chemokine (eotaxin-1/CCL11, RANTES/CCL5, IL-8/CXCL8, and IP-10/CXCL10) release in ASM cells via transcriptional mechanisms. Both TNF and IgE induced a novel, Th2-favoring cytokine thymic stromal lymphopoietin (TSLP) through the activation of spleen tyrosine kinase (Syk), and nuclear factor kappa B (NF-kappaB) and activator protein-1 (AP-1). In addition, IgE induced de novo DNA synthesis and ASM cell proliferation via mitogen-activated protein kinases (MAPKs) and signal-transducer and activator of transcription 3 (STAT3) activation. Collectively, our data suggest that the IgE-induced FcepsilonRI activation leads to the expression of multiple chemokines in ASM which may indirectly recruit inflammatory cells and promote allergic airway inflammation; IgE induces TSLP which can promote the Th2 immune responses within the airways; and IgE may potentially induce airway remodeling by directly inducing ASM cell proliferation. Therefore, targeting the IgE-FcepsilonRI network on ASM may offer a novel therapeutic strategy in allergic asthma. |
