Multiple β1 Integrins Mediate Enhancement of Human Airway Smooth Muscle Cytokine Secretion by Fibronectin and Type I Collagen

Abstract

Altered airway smooth muscle (ASM) function and enrichment of the extracellular matrix (ECM) with interstitial collagen and fibronectin are major pathological features of airway remodeling in asthma. We have previously shown that these ECM components confer enhanced ASM proliferation in vitro, but their action on its newly characterized secretory function is unknown. Here, we examined the effects of fibronectin and collagen types I, III, and V on IL-1β-dependent secretory responses of human ASM cells, and characterized the involvement of specific integrins. Cytokine production (eotaxin, RANTES, and GM-CSF) was evaluated by ELISA, RT-PCR, and flow cytometry. Function-blocking integrin mAbs and RGD (Arg-Gly-Asp)-blocking peptides were used to identify integrin involvement. IL-1β-dependent release of eotaxin, RANTES, and GM-CSF was enhanced by fibronectin and by fibrillar and monomeric type I collagen, with similar changes in mRNA abundance. Collagen types III and V had no effect on eotaxin or RANTES release but did modulate GM-CSF. Analogous changes in intracellular cytokine accumulation were found, but in <25% of the total ASM cell population. Function-blocking Ab and RGD peptide studies revealed that α2β1, α5β1, αvβ1, and αvβ3 integrins were required for up-regulation of IL-1β-dependent ASM secretory responses by fibronectin, while α2β1 was an important transducer for type I collagen. Thus, fibronectin and type I collagen enhance IL-1β-dependent ASM secretory responses through a β1 integrin-dependent mechanism. Enhancement of cytokine release from ASM by these ECM components may contribute to airway wall inflammation and remodeling in asthma.

Mast Cell Fibroblastoid Differentiation Mediated by Airway Smooth Muscle in Asthma

“…However, TGF-b is an important inducer of ECM protein production by ASM, in particular, fibronectin (36,37). This increased release of fibronectin will in turn promote ASM synthetic function (38,39) and mast cell activation (26,40), as well as transition to fibroblastoid phenotype. This altered phenotype has the capacity to further drive the ASM to a more contractile phenotype, therefore propagating the cycle to promote AHR (35).…”

Cell Shape and Matrix Production of Fibroblasts Cultured on Fibroin-organized Silk Scaffold with Type-II .BETA.-turn Structured (Ala-Gly-Ala-Gly-Ser-Gly)n Sequences

“…A previous study reported the matrix ligand contains an RGD sequence which binds to α2β1 integrin to stimulate autologous production of various cytokines. 15) It is well known that fibronectin possess RGD sequence, and facilitates dermal fibroblast migration during wound healing. 16) In this study, fibroblasts cultured on the SILK I showed the enhanced expression of fibronectin, suggesting possible roles of fibronectin in cell migration and scaffold condition for skin fibroblasts wound healing.…”

Extended interaction of β1 integrin subunit-deficient cells (GD25) with surfaces modified with fibronectin-derived peptides: Culture optimization, adhesion and cytokine panel studies

“…IL-1, IL-6 and TNF-α are proinflammatory cytokines expressed by a variety of cell types which encourage host responses typical of early stage wound healing [14,15]. GM-CSF has been shown to play a role in the local activation, recruitment and survival of macrophage lineage cells [15,16]. MCP-1 and RANTES are potent stimulators of monocyte and T-cell migration [16][17][18].…”

“…GM-CSF has been shown to play a role in the local activation, recruitment and survival of macrophage lineage cells [15,16]. MCP-1 and RANTES are potent stimulators of monocyte and T-cell migration [16][17][18]. Overall, this panel of key inflammatory proteins should provide a representation of the β1 subunits' role in inflammatory signaling.…”