Collaborative interactions between neutrophil elastase and metalloproteinases in extracellular matrix degradation in three-dimensional collagen gels

Y Zhu,T Kohyama,Stephen I Rennard,Fu-Qiang Wen,X Liu,H Wang,C Magnus Sköld,Ronald F Ertl

doi:10.1186/rr73

Abstract

BackgroundExtended culture of monocytes and fibroblasts in three-dimensional collagen gels leads to degradation of the gels (see linked study in this issue, "Fibroblasts and monocytes contract and degrade three-dimensional collagen gels in extended co-culture"). The current study, therefore, was designed to evaluate production of matrix-degrading metalloproteinases by these cells in co-culture and to determine if neutrophil elastase could collaborate in the activation of these enzymes. Since co-cultures produce prostaglandin E2 (PGE2), the role of PGE2 in this process was also evaluated.MethodsBlood monocytes from healthy donors and human fetal lung fibroblasts were cast into type I collagen gels and maintained in floating cultures for three weeks. Matrix metalloproteinases (MMPs) were assessed by gelatin zymography (MMPs 2 and 9) and immunoblotting (MMPs 1 and 3). The role of PGE2 was explored by direct quantification, and by the addition of exogenous indomethacin and/or PGE2.ResultsGelatin zymography and immunoblots revealed that MMPs 1, 2, 3 and 9 were induced by co-cultures of fibroblasts and monocytes. Neutrophil elastase added to the medium resulted in marked conversion of latent MMPs to lower molecular weight forms consistent with active MMPs, and was associated with augmentation of both contraction and degradation (P < 0.01). PGE2 appeared to decrease both MMP production and activation.ConclusionThe current study demonstrates that interactions between monocytes and fibroblasts can mediate tissue remodeling.

Highlights

Three-dimensional (3D) collagen gel culture has been used as an in vitro model of in vivo tissue contraction, a common feature of fibrosis, as well as the resolution of granulation tissue that characterizes repair [1,2]
Co-culture of monocytes and fibroblasts increased both bands of Matrix metalloproteinases (MMPs)-2 and resulted in more of the 66 kDa form (Fig. 1b)
Co-culture of fibroblasts with monocytes induced the release of MMP-9 (Fig. 1b), which was present as the latent 92 kDa form

Summary

Introduction

Three-dimensional (3D) collagen gel culture has been used as an in vitro model of in vivo tissue contraction, a common feature of fibrosis, as well as the resolution of granulation tissue that characterizes repair [1,2]. Shortterm co-cultures of monocytes with fibroblasts result in the inhibition of collagen gel contraction [3], while co-cultures of fibroblasts with neutrophils, or with neutrophil elastase (NE), augment contraction [4]. The current study, was designed to evaluate production of matrix-degrading metalloproteinases by these cells in co-culture and to determine if neutrophil elastase could collaborate in the activation of these enzymes. Results: Gelatin zymography and immunoblots revealed that MMPs 1, 2, 3 and 9 were induced by cocultures of fibroblasts and monocytes. Neutrophil elastase added to the medium resulted in marked conversion of latent MMPs to lower molecular weight forms consistent with active MMPs, and was associated with augmentation of both contraction and degradation (P < 0.01). Conclusion: The current study demonstrates that interactions between monocytes and fibroblasts can mediate tissue remodeling

Methods

Results

Conclusion