Punicalagin Inhibits Tert-Butyl Hydroperoxide-Induced Apoptosis and Extracellular Matrix Degradation in Chondrocytes by Activating Autophagy and Ameliorates Murine Osteoarthritis

Abstract

Background

Osteoarthritis (OA) is a prevalent articular disorder and has no entirely satisfactory treatment. Punicalagin (PUG) is a polyphenol which has shown multiple pharmacological effects on various diseases. However, the role of PUG in the treatment of OA has not been well defined.

Methods

The effects of PUG on anti-oxidative stress, anti-apoptosis, extracellular matrix (ECM) degradation and autophagy were evaluated in chondrocytes through Western blot and immunofluorescence (IF) staining. Meanwhile, the effects of PUG on destabilization of the medial meniscus (DMM) model were also assessed in vivo by performing histopathologic analysis and IF staining.

Results

In vitro, PUG treatment not only increased the level of HO-1 and SOD1 against oxidative stress but also suppressed the expression of apoptotic proteins and inhibited ECM degradation. Meanwhile, PUG treatment activated autophagy and restores autophagic flux in chondrocytes after tert-butyl hydroperoxide (TBHP) insult, inhibition of autophagy by 3-methyladenine (3-MA) partly abrogated the protective effects of PUG on chondrocytes. In vivo, degeneration of the articular cartilage following DMM was also ameliorated by PUG treatment.

Conclusion

PUG prevents the progression of OA through inhibition of apoptosis, oxidative stress and ECM degradation in chondrocytes, which mediated by the activation of autophagy.

Keywords:

• punicalagin
• autophagy
• osteoarthritis
• apoptosis
• extracellular matrix

Acknowledgments

This study was partially supported by a research grant from Medical and Health Foundation of Zhejiang Province (2020KY367, 2020PY091) and Taizhou science project (XM20190640).

Abbreviations

OA, osteoarthritis; PUG, punicalagin; ECM, extracellular matrix; IF, immunofluorescence; DMM, destabilization of the medial meniscus; TBHP, tert-butyl hydroperoxide; 3-MA, 3-methyladenine; ROS, reactive oxygen species; FBS, foetal bovine serum; DAPI, 4,6-Diami-dino-2-phenylindole; CCK-8, cell counting kit-8; PFA, paraformaldehyde; PVDF, polyvinylidene fluoride; OARSI, Osteoarthritis Research Society International; ANOVA, One-way analysis of variance.

Data Sharing Statement

The datasets used and analyzed during the current study are available from the corresponding authors on reasonable request.

Consent for Publication

We declare that our institutes are aware of the work and declare consent for publication of the manuscript. We received consent to publish the animal experimental data from the animal ethical committee.

Disclosure

The authors declare that they have no conflicts of interest.