PEP-1-GRX-1 Modulates Matrix Metalloproteinase-13 and Nitric Oxide Expression of Human Articular Chondrocytes

Abstract

Background: The protein transduction domain (PTD) enables therapeutic proteins to directly penetrate the membranes of cells and tissues, and has been increasingly utilized. Glutaredoxin-1 (GRX-1) is an endogenous antioxidant enzyme involved in the cellular redox homeostasis system. In this study, we investigated whether PEP-1-GRX-1, a fusion protein of GRX-1 and PEP-1 peptide, a PTD, could suppress catabolic responses in primary human articular chondrocytes and a mouse carrageenan-induced paw edema model. Methods: Human articular chondrocytes were isolated enzymatically from articular cartilage and cultured in a monolayer. The transduction efficiency of PEP-1-GRX-1 into articular chondrocytes was measured by western blot and immunohistochemistry. The effects of PEP-1-GRX-1 on matrix metalloproteinases (MMPs) and catabolic factor expression in interleukin (IL)-1β- and lipopolysaccharide (LPS)-treated chondrocytes were analyzed by real-time quantitative reverse transcription-polymerase chain reaction and western blot. The effect of PEP-1-GRX1 on the mitogen-activated protein kinase (MAPK) and nuclear factor kappa-light chain-enhancer of activated B cells (NF-κB) signaling pathway were also analyzed by western blot. Finally, the inhibitory effect of PEP-1-GRX-1 on MMP-13 production was measured in vivo in a mouse carrageenan-induced paw edema model. Results: PEP-1-GRX-1 significantly penetrated into human chondrocytes and mouse cartilage, whereas GRX-1 did not. PEP-1-GRX-1 significantly suppressed MMP-13 expression and nitric oxide (NO) production in LPS-stimulated chondrocytes, and NO production in IL-1β-stimulated chondrocytes, compared with GRX-1. In addition, PEP-1-GRX-1 decreased IL-1β- and LPS-induced activation of MAPK and NF-κB. In the mouse model of carrageenan-induced paw edema, PEP-1-GRX-1 significantly suppressed carrageenan-induced MMP-13 production as well as paw edema. Conclusion: These results demonstrate that PEP-1-GRX-1 can be transduced efficiently in vitro and in vivo into human chondrocytes and mouse cartilage tissue and downregulate catabolic responses in chondrocytes by inhibiting the MAPK and NF-κB pathway. PEP-1-GRX-1 thus has the potential to reduce catabolic responses in chondrocytes and cartilage.