Critical Role for STAT3 in IL-17A-Mediated CCL11 Expression in Human Airway Smooth Muscle Cells

Abstract

IL-17A has been shown to be expressed at higher levels in respiratory secretions from asthmatics and to correlate with airway hyperresponsiveness. Although these studies raise the possibility that IL-17A may influence allergic disease, the mechanism remains unknown. We previously demonstrated that IL-17A mediates CC chemokine (CCL11) production from human airway smooth muscle (ASM) cells. In this study, we demonstrate that STAT3 activation is critical in IL-17A-mediated CCL11 expression in ASM cells. IL-17A mediated a rapid phosphorylation of STAT3 but not STAT6 or STAT5 in ASM cells. Interestingly, transient transfection with wild-type or mutated CCL11 promoter constructs showed that IL-17A-mediated CCL11 expression relies on the STAT6 binding site. However, STAT3 but not STAT6 in vivo binding to the CCL11 promoter was detected following IL-17A stimulation of ASM cells. Overexpression of DN STAT3 (STAT3β) abolishes IL-17A-induced CCL11 promoter activity. This effect was not observed with STAT6 DN or the STAT3 mutant at Ser727. Interestingly, disruption of STAT3 activity with the SH2 domain binding peptide, but not with control peptide, results in a significant reduction of IL-17A-mediated STAT3 phosphorylation and CCL11 promoter activity. IL-17A-mediated CCL11 promoter activity and mRNA were significantly diminished in STAT3- but not STAT6-silenced ASM cells. Finally, IL-17A-induced STAT3 phosphorylation was sensitive to pharmacological inhibitors of JAK2 and ERK1/2. Taken together, our data provide the first evidence of IL-17A-mediated gene expression via STAT3 in ASM cells. Collectively, our results raise the possibility that the IL-17A/STAT3 signaling pathway may play a crucial role in airway inflammatory responses.

IL-17A Plays a Critical Role in the Pathogenesis of Liver Fibrosis through Hepatic Stellate Cell Activation

“…Because Stat3 could be phosphorylated by activated ERK1/2, JNK, or p38 (at Ser 727 ), we further investigated which MAPK pathway may be involved. We observed that ERK1/2, p38, and JNK exhibit time-dependent phosphorylation in HSCs upon IL-17A restimulation, and their response to rmIL-17A restimulation is rapid (within 30 min), like previously observed in human airway smooth muscle cells (45,46). Furthermore, pharmacological inhibition of ERK1/2 or p38 decreased collagen and a-SMA expression in rmIL-17A-challenged or quiescent HSCs.…”

Thymic Stromal Lymphopoietin Receptor-Mediated IL-6 and CC/CXC Chemokines Expression in Human Airway Smooth Muscle Cells: Role of MAPKs (ERK1/2, p38, and JNK) and STAT3 Pathways

“…Written informed consent for airway smooth muscle (ASM) harvesting was obtained from all patients. HASM cells were cultured and maintained as described earlier (22)(23)(24)(25)(26).…”

“…STAT3 has recently been implicated to play a critical role in promoting allergic inflammation, notably in studies where epithelial STAT3 disruption reduced the airway eosinophilia (21), and IL-17A-induced STAT3 activation mediated the eotaxin-1/CCL11 induction in HASM (22). However, despite the increased interest in pathophysiology of TSLP in inflammatory diseases such as asthma (6), cellular targets and TSLPR-associated cell signaling mechanisms and functions remain poorly understood.…”

IL-17 signaling in host defense and inflammatory diseases

“…50 Interestingly, a recent report showed that Stat3 is critical for IL-17-mediated CCL11 expression in human airway smooth muscle cells. 51 However, more direct evidence for the roles of JAK/PI3K and JAK/Stat in IL-17 signaling are needed to avoid secondary effects because JAKs can be strongly activated by IL-17-induced cytokines, such as IL-6. mRNA stability.…”