SERPINE2 Inhibits IL-1α-Induced MMP-13 Expression in Human Chondrocytes: Involvement of ERK/NF-κB/AP-1 Pathways.

Anna Santoro,Juan J Gomez-Reino,Oreste Gualillo,Morena Scotece,Ana Lois,Jesus Pino,Javier Conde,Veronica Lopez,Rodolfo Gomez,Vanessa Abella,Fulvio D'Acquisto

doi:10.1371/journal.pone.0135979

Abstract

ObjectivesOsteoarthritis (OA) is a chronic joint disease, characterized by a progressive loss of articular cartilage. During OA, proinflammatory cytokines, such as interleukin IL-1, induce the expression of matrix metalloproteinases (MMPs) in chondrocytes, contributing thus to the extracellular matrix (ECM) degradation. Members of Serpine family, including plasminogen activator inhibitors have been reported to participate in ECM regulation. The aim of this study was to assess the expression of serpin peptidase inhibitor clade E member 2 (SERPINE2), under basal conditions and in response to increasing doses of IL-1α, in human cultured chondrocytes. We also examined the effects of SERPINE2 on IL-1α-induced MMP-13 expression. For completeness, the signaling pathway involved in this process was also explored.MethodsSERPINE2 mRNA and protein expression were evaluated by RT-qPCR and western blot analysis in human T/C-28a2 cell line and human primary chondrocytes. These cells were treated with human recombinant SERPINE2, alone or in combination with IL-1α. ERK 1/2, NFκB and AP-1 activation were assessed by western blot analysis.ResultsHuman cultured chondrocytes express SERPINE2 in basal condition. This expression increased in response to IL-1α stimulation. In addition, recombinant SERPINE2 induced a clear inhibition of MMP-13 expression in IL-1α-stimulated chondrocytes. This inhibitory effect is likely regulated through a pathway involving ERK 1/2, NF-κB and AP-1.ConclusionsTaken together, these data demonstrate that SERPINE2 might prevent cartilage catabolism by inhibiting the expression of MMP-13, one of the most relevant collagenases, involved in cartilage breakdown in OA.

Highlights

Osteoarthritis (OA) is one of the most common rheumatic disorders and a major cause of pain and disability in older adults
Clear inhibition of matrix metalloproteinases (MMPs)-13 expression in IL-1α-stimulated chondrocytes. This inhibitory effect is likely regulated through a pathway involving ERK 1/2, NF-κB and AP-1. These data demonstrate that SERPINE2 might prevent cartilage catabolism by inhibiting the expression of MMP-13, one of the most relevant collagenases, involved in cartilage breakdown in OA
In order to assess the effect of IL-1α on SERPINE2 expression, human primary chondrocytes and T/C-28a2 cells were treated with this pro-inflammatory cytokine at increasing concentrations (0.05–10 ng/mL) for 24 h

Summary

Introduction

Osteoarthritis (OA) is one of the most common rheumatic disorders and a major cause of pain and disability in older adults. Chondrocytes, the unique cell type of adult articular cartilage, remain as quiescent cells in normal conditions, maintaining the turnover of the extracellular matrix components. During OA, chondrocytes become activated, characterized by phenotypic changes and increased production of extracellular matrix-degrading enzymes, which include different matrix metalloproteinases (MMPs) [2]. This chondrocyte-phenotypic shift is caused, in part, by the exposure to abnormal environmental insults, including high mechanical stress, metabolic alterations, pro-inflammatory cytokines and adipokines [2,3,4]. One of the most relevant pro-inflammatory cytokines involved in cartilage degeneration is interleukin-1 (IL-1). This cytokine is able to induce MMP-13, one of the most relevant collagenases involved in cartilage breakdown during OA

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