IL-17 enhances IL-1β-mediated CXCL-8 release from human airway smooth muscle cells

Abstract

December 22, 2006; doi:10.1152/ajplung.00306.2006.-Recent studies into the pathogenesis of airway disorders such as asthma have revealed a dynamic role for airway smooth muscle cells in the perpetuation of airway inflammation via secretion of cytokines and chemokines. In this study, we evaluated whether IL-17 could enhance IL-1␤-mediated CXCL-8 release from human airway smooth muscle cells (HASMC) and investigated the upstream and downstream signaling events regulating the induction of CXCL-8. CXCL-8 mRNA and protein induction were assessed by real-time RT-PCR and ELISA from primary HASMC cultures. HASMC transfected with site-mutated activator protein (AP)-1/NF-B CXCL-8 promoter constructs were treated with selective p38, MEK1/2, and phosphatidylinositol 3-kinase (PI3K) inhibitors to determine the importance of MAPK and PI3K signaling pathways as well as AP-1 and NF-B promoter binding sites. We demonstrate IL-17 induced and synergized with IL-1␤ to upregulate CXCL-8 mRNA and protein levels. Erk1/2 and p38 modulated IL-17 and IL-1␤ CXCL-8 promoter activity; however, IL-1␤ also activated the PI3K pathway. The synergistic response mediating CXCL-8 promoter activity was dependent on both MAPK and PI3K signal transduction pathways and required the cooperation of AP-1 and NF-B cis-acting elements upstream of the CXCL-8 gene. Collectively, our observations indicate MAPK and PI3K pathways regulate the synergy of IL-17 and IL-1␤ to enhance CXCL-8 promoter activity, mRNA induction, and protein synthesis in HASMC via the cooperative activation of AP-1 and NF-B trans-acting elements.

Inflammatory Effects of Ex Vivo Human Th17 Cells Are Suppressed by Regulatory T Cells

“…Determining the answer to this question has been complicated by the finding that in humans subsets of Tregs themselves can make IL-17 (19)(20)(21)(22)(23)(24) (45). Because IL-17 can induce CXCL8 in several cell types (36,46,47) and human CD4 + T cells express the IL-17R (48), the suppression of CXCL8 production may be an indirect consequence of suppression of autocrine IL-17.…”

Structure–function relationships in the IL-17 receptor: Implications for signal transduction and therapy

“…In addition to IL-6, a major group of IL-17 target genes are chemokines, particularly neutrophilattracting CXC chemokines (Table 2) [77,81,82,[88][89][90], which to a large extent underlies the potent effects of IL-17 on the neutrophil axis in vivo [91,92]. In addition, some CC chemokines are also targets of IL-17, including CCL2/MCP-1 [76,93,94], CCL11/eotaxin [95] and CCL20 [96].…”

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

“…After 12 h of cytokine stimulation, cells were washed twice with PBS and cell lysates were collected with 100 l of reporter lysis buffer (Promega). The luciferase activity was measured by the Dual-Luciferase assay system kit (Promega) using a luminometer (model LB9501; Berthold Lumat) as we described previously (17). All values are normalized to Renilla luciferase activity and expressed relative to the control-transfected nonstimulated cells.…”

“…For pharmacological studies, cells were pretreated with inhibitors for ERK1/2 (U0126; 10 M), p38 (SB203580; 10 M), JNK1/2 (SP600125; 40 nM), JAK2 inhibitor II (10 M,) and JAK3 inhibitor VI (10 M) before stimulation with IL-17A (10 ng/ml) or IL-4 (10 ng/ml). Concentration of MAPK inhibitors are based on our study (13,17) and others (18). The concentration of JAK3 inhibitor VI was chosen as multiples of the in vitro IC 50 as provided by the manufacturer.…”