Electroacupuncture Exerts Chondroprotective Effect in Knee Osteoarthritis of Rabbits Through the Mitophagy Pathway

Abstract

Purpose

Mitochondrial dysfunction of chondrocytes has become an area of focus in Knee Osteoarthritis (KOA) in recent years. Activation of mitophagy could promote the survival of chondrocytes and alleviate cartilage degeneration. The aim of this study was to explore whether mitophagy was involved in the cartilage protection of KOA rabbits after electroacupuncture (EA) intervention.

Methods

The rabbits were divided into 3 groups, Control group, KOA group, EA group, with 6 rabbits in each group. KOA model rabbits were established by modified Videman’s extended immobilization method for 6 weeks and randomly divided into KOA group and EA group. The rabbits in EA group were treated every other day for 3 weeks. The degree of cartilage degeneration was detected by Safranine O-Fast Green staining and immunofluorescence. The morphological changes of chondrocytes mitochondria were detected by transmission electron microscope. ATP concentration in cartilage was measured by ATP Assay Kit. The changes of Pink1-Parkin signal pathway were detected by immunofluorescence, Western blot, and Real-time PCR.

Results

The morphology showed that EA could reduce the degeneration of KOA cartilage and increase the distribution of collagen II. We also found that EA could activate mitophagy in KOA rabbit chondrocytes to remove damaged mitochondria and restore mitochondrial homeostasis, which was manifested as increasing the expression of LC3 II/I, promoting the colocalization of TOM20 and LC3B, reducing the accumulation of mitochondrial markers outer mitochondrial membrane 20 (TOM20) and inner mitochondrial membrane 23 (TIM23), and increasing ATP production in chondrocytes. This regulation might be achieved by upregulating the Pink1-Parkin signal pathway.

Conclusion

EA may play a role in protecting KOA cartilage by activating mitophagy mediated through Pink1-Parkin pathway.

Keywords:

• osteoarthritis
• electroacupuncture
• mitophagy
• mitochondria
• Pink1-Parkin

Abbreviations

OA, osteoarthritis; KOA, knee osteoarthritis; EA, electroacupuncture; TEM, Transmission electron microscopy; ECM, extracellular matrix.

Ethics Approval

All animal experiments were performed at Beijing University of Chinese Medicine (Beijing China) according to the guidelines of the China Council on Animal Care and Use. This study was approved by the Committee of Experimental Animals of The Beijing University of Chinese Medicine (approval number: BUCM-4-2022-010101-1097). Every effort was made to minimize pain and discomfort to the animals.

Disclosure

The authors report no conflicts of interest in this work.

Additional information

Funding

This work was supported by Beijing Natural Science Foundation(NO.7192110) and National Natural Science Foundation of China (NO.82074523).