Binding of myeloperoxidase to the extracellular matrix of smooth muscle cells and subsequent matrix modification

Huan Cai,Michael J Davies,Clare L Hawkins,Christine Y Chuang

doi:10.1038/s41598-019-57299-6

Huan Cai, Michael J Davies + Show 2 more

Open Access

https://doi.org/10.1038/s41598-019-57299-6

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Journal: Scientific Reports	Publication Date: Jan 20, 2020
Citations: 30	License type: open-access

Affiliation: University of Copenhagen

Abstract

The extracellular matrix (ECM) of tissues is susceptible to modification by inflammation-associated oxidants. Considerable data support a role for hypochlorous acid (HOCl), generated by the leukocyte-derived heme-protein myeloperoxidase (MPO) in these changes. HOCl can modify isolated ECM proteins and cell-derived matrix, with this resulting in decreased cell adhesion, modulated proliferation and gene expression, and phenotypic changes. Whether this arises from free HOCl, or via site-specific reactions is unresolved. Here we examine the mechanisms of MPO-mediated changes to human coronary smooth muscle cell ECM. MPO is shown to co-localize with matrix fibronectin as detected by confocal microscopy, and bound active MPO can initiate ECM modification, as detected by decreased antibody recognition of fibronectin, versican and type IV collagen, and formation of protein carbonyls and HOCl-mediated damage. These changes are recapitulated by a glucose/glucose oxidase/MPO system where low continuous fluxes of H2O2 are generated. HOCl-induced modifications enhance MPO binding to ECM proteins as detected by ELISA and MPO activity measurements. These data demonstrate that MPO-generated HOCl induces ECM modification by interacting with ECM proteins in a site-specific manner, and generates alterations that increase MPO adhesion. This is proposed to give rise to an increasing cycle of alterations that contribute to tissue damage.

Highlights

The extracellular matrix (ECM) of tissues is susceptible to modification by inflammation-associated oxidants
We examined modification of the human coronary artery smooth muscle cell (HCASMC)-ECM by associated MPO where the H2O2 was generated in situ using a glucose/glucose oxidase (GO) system, that generates H2O2 over a long time period, with potential damage to the HCASMC-ECM detected using immunofluorescence staining and ELISA, as described above
We have reported that exposure of HCASMC-ECM to either reagent or MPO-derived hypochlorous acid (HOCl) can give rise to oxidative modifications of the HCASMC-ECM and its components, and that these modified materials affect the behavior of HCASMCs, including loss of adhesion, accelerated proliferation and modulated gene expression[43]

Summary

Introduction

The extracellular matrix (ECM) of tissues is susceptible to modification by inflammation-associated oxidants. MPO is shown to co-localize with matrix fibronectin as detected by confocal microscopy, and bound active MPO can initiate ECM modification, as detected by decreased antibody recognition of fibronectin, versican and type IV collagen, and formation of protein carbonyls and HOCl-mediated damage These changes are recapitulated by a glucose/glucose oxidase/MPO system where low continuous fluxes of H2O2 are generated. MPO is released from intracellular storage granules of activated neutrophils, monocytes and some tissue macrophages, and shows a high affinity for both ECM proteins and negatively-charged glycosaminoglycan (GAG) chains due to the high abundance of (positively-charged) Lys and Arg residues on the protein surface[29,30,31] These observations suggest that the HOCl formation by MPO/H2O2/Cl− may occur in a localized and site-specific manner. MPO protein has been reported to be localized to the shoulder regions of lesions, which are especially prone to rupture and thrombus formation[35,36], and high numbers of MPO-expressing cells have been reported at such sites[37,38,39]

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