Introduction

Osteoarthritis (OA) is a common disease that causes physical pain and even disability in patients. This disease affects the majority of older people in the world and brings huge economic burden to society [1, 2]. A variety of risk factors have been identified for OA [3], but the clear pathogenesis and effective treatment remain to be further studied. The pathological changes of OA are characterized by chondrocyte death and cartilage destruction, synovitis, and osteophyte formation [4]. Chondrocytes and their secreted extracellular matrix (ECM) are main components of articular cartilage [5]. Chondrocytes maintain physiological structure of articular cartilage and improve joint function by well-regulating the balance of anabolism and catabolism of ECM [4]. Tumor necrosis factor-α (TNF-α) is a key inflammatory mediator in OA progression and one of the leading cytokines giving rise to the imbalance of matrix synthesis and decomposition [6, 7]. Therefore, it is important to maintain homeostasis of chondrocytes by protecting chondrocytes against death and degradation of ECM under the pathological conditions.

TNFR1-associated death domain protein (TRADD), is an adaptor molecule for the signaling downstream of tumor necrosis factor receptor 1 (TNFR1) [47]. The sections were incubated with anti-LC3, MMP13, P-RIPK3, and COL2A1 antibodies to observe expression changes of these markers.

Statistical analysis

Graph Pad Prism 8.0 software was used for statistical analysis. Results were revealed as mean ± standard deviation (SD). Student T test (unpaired, two-tailed) was used for statistical analysis between the two groups. Comparisons between more than two groups were performed by ANOVA and Tukey test. P values <0.05 was statistically significant. N = 3 means the in vitro experiments were performed at least three biological replicates.