Extra-Cellular Matrix Proteins Induce Matrix Metalloproteinase-1 (MMP-1) Activity and Increase Airway Smooth Muscle Contraction in Asthma

Abstract

Airway remodelling describes the histopathological changes leading to fixed airway obstruction in patients with asthma and includes extra-cellular matrix (ECM) deposition. Matrix metalloproteinase-1 (MMP-1) is present in remodelled airways but its relationship with ECM proteins and the resulting functional consequences are unknown. We used airway smooth muscle cells (ASM) and bronchial biopsies from control donors and patients with asthma to examine the regulation of MMP-1 by ECM in ASM cells and the effect of MMP-1 on ASM contraction. Collagen-I and tenascin-C induced MMP-1 protein expression, which for tenascin-C, was greater in asthma derived ASM cells. Tenascin-C induced MMP-1 expression was dependent on ERK1/2, JNK and p38 MAPK activation and attenuated by function blocking antibodies against the β1 and β3 integrin subunits. Tenascin-C and MMP-1 were not expressed in normal airways but co-localised in the ASM bundles and reticular basement membrane of patients with asthma. Further, ECM from asthma derived ASM cells stimulated MMP-1 expression to a greater degree than ECM from normal ASM. Bradykinin induced contraction of ASM cells seeded in 3D collagen gels was reduced by the MMP inhibitor ilomastat and by siRNA knockdown of MMP-1. In summary, the induction of MMP-1 in ASM cells by tenascin-C occurs in part via integrin mediated MAPK signalling. MMP-1 and tenascin-C are co-localised in the smooth muscle bundles of patients with asthma where this interaction may contribute to enhanced airway contraction. Our findings suggest that ECM changes in airway remodelling via MMP-1 could contribute to an environment promoting greater airway narrowing in response to broncho-constrictor stimuli and worsening asthma symptoms.

Matrix Metalloproteinase-1 Activation Contributes to Airway Smooth Muscle Growth and Asthma Severity

“…MMP-1 activity was measured using a Human Active MMP-1 Fluorokine E Kit (R&D Systems). Generation of the active 43-kD MMP-1 species was assessed by Western blotting (14). Proteolytic cleavage of MMP-1 by tryptase was examined by incubation of recombinant pro-MMP-1 (10 ng; R&D Systems) and recombinant human mast cell tryptase (0.1-2 IU; Promega, Southampton, UK) in physiologic buffered saline for 30 minutes at 37 8 C. Products were resolved on sodium dodecyl sulfate-polyacrylamide gel electrophoresis and visualized by silver staining.…”

“…ASM cell-derived ECM was prepared as described (14). Further details are given in the online supplement.…”

“…MMP-1 siRNA Knockdown siRNA was used as previously described (14) and reduced MMP-1 protein by greater than 70% (see Figure E2). …”

“…Our overarching hypothesis is that the airway environment in asthma sustains airway remodeling (14)(15)(16). We have shown that components of the ECM in asthmatic airways can promote remodeling by affecting proliferation (17), migration (16), apoptosis (18), matrix metalloproteinase (MMP) activation (16), and b-agonist signaling of ASM cells (19).…”

Novas Perspectivas Acerca do Contexto Inflamatório Th2 Na Asma

“…A MPMEC -1, uma colagenase, possui uma maior expressão nas vias respiratórias de pacientes asmáticos (CATALDO et al, 2004). Segundo Rogers et al (2014), a avaliação in vitro da atividade da MPMEC, e sua atuação nas CMLVA, demonstrou a atividade das proteínas da MEC na ativação da MPMEC. Além disso, foi observado o aumento na contração das CMLVA na presença de MPMEC -1, no qual a utilização de um siRNA para MPMEC -1 reduziu significativamente a contração das CMLVA.…”