The Role of Autophagy in Osteoarthritic Cartilage

Abstract

Osteoarthritis (OA) is one of the most common diseases leading to physical disability, with age being the main risk factor, and degeneration of articular cartilage is the main focus for the pathogenesis of OA. Autophagy is a crucial intracellular homeostasis system recycling flawed macromolecules and cellular organelles to sustain the metabolism of cells. Growing evidences have revealed that autophagy is chondroprotective by regulating apoptosis and repairing the function of damaged chondrocytes. Then, OA is related to autophagy depending on different stages and models. In this review, we discuss the character of autophagy in OA and the process of the autophagy pathway, which can be modulated by some drugs, key molecules and non-coding RNAs (microRNAs, long non-coding RNAs and circular RNAs). More in-depth investigations of autophagy are needed to find therapeutic targets or diagnostic biomarkers through in vitro and in vivo situations, making autophagy a more effective way for OA treatment in the future. The aim of this review is to introduce the concept of autophagy and make readers realize its impact on OA. The database we searched in is PubMed and we used the keywords listed below to find appropriate article resources.

Correlation between the Signal Intensity Alteration of Infrapatellar Fat Pad and Knee Osteoarthritis: A Retrospective, Cross-Sectional Study

“…With more in-depth understanding of osteoarthritis, its complex etiology and the interaction of internal and external structures in joints have become the focus of scientists’ attention. As the largest and most complex joint in the human body, the knee joint, articular cartilage, subchondral bone, synovium, infrapatellar fat pad, ligaments, and skeletal muscles jointly promote or inhibit the progression of osteoarthritis [ 28 , 29 , 30 , 31 , 32 , 33 , 34 ].…”

New insights into the interplay between autophagy and cartilage degeneration in osteoarthritis

“…Autophagy is activated as an adaptive response to sublethal conditions, with the aim to avoid cell death ( Klionsky, 2005 ; Levine & Yuan, 2005 ). Some studies have found that the ULK1, beclin-1, LC3 protein expression is decreased in the superficial zone, while these proteins are strongly expressed in the middle and deep zone ( Kao et al, 2022 ). In later stages, there is an all-layered autophagic genetic change, including not only reduced ULK1, LC3, and beclin-1 but also fewer ATG3, ATG5, and ATG12.…”

“…Targeted deletion of ATG in chondrocytes can promote cell death ( Vuppalapati et al, 2015 ). Furthermore, the loss of proteoglycan is associated with reduced autophagic markers in OA ( Kao et al, 2022 ). As essential organelles in chondrocytes, mitochondria supply energy and play vital roles in cellular metabolism and proliferation.…”

Clinical efficacy of Yiqi Yangxue formula on knee osteoarthritis and unraveling therapeutic mechanism through plasma metabolites in rats

“…Knee osteoarthritis (KOA) is the most prevalent form of arthritis characterized by a degeneration of articular cartilage resulting in the development of osteophytes, or bone spurs ( Horecka et al, 2022 ). The global prevalence of KOA is around 3.8% ( Kao et al, 2022 ). KOA is closely associated with age, as radiographic evidence of KOA occurs in most people over the age of 65 years ( Lespasio et al, 2017 ).…”