Theaflavin-3,3$\prime$-Digallate Inhibits Erastin-Induced Chondrocytes Ferroptosis via the Nrf2/GPX4 Signaling Pathway in Osteoarthritis

Abstract

There is evidence that osteoarthritis (OA) is associated with ferroptosis which is a kind of lipid peroxidation-related cell death. Theaflavin-3,3 ′ -digallate(TF3), a polyphenol compound extracted from black tea, possesses antioxidative and anti-inflammatory properties, but its effects on chondrocyte ferroptosis in osteoarthritis (OA) remain unclear. Our present study aims at exploring the protective role and underlying mechanisms of TF3 against erastin-induced chondrocyte ferroptosis in OA. In human primary chondrocytes treated with erastin alone or combined with different doses of TF3, cell viability was assessed by MTS. Ferroptosis-related proteins, including Gpx4, HO-1, and FTH1, were detected by western blot. The levels of lipid peroxidation and Fe2+ were determined by fluorescence staining. Meanwhile, the change of related proteins in the Nrf2/Gpx4 signaling pathway was determined by western blot. siRNA-mediated Nrf2 knockdown and the Gpx4 inhibitor RSL3 were used to explore molecular mechanisms for TF3-induced ferroptosis in OA chondrocyte. The magnetic resonance imaging (MRI), HE staining, Masson’s staining, and immunohistochemistry were used to evaluate articular cartilage damages in the rat OA model. The results showed that Gpx4 expression was markedly downregulated in the chondrocytes of OA patients. TF3 reversed erastin-induced ferroptosis of human cultured chondrocytes, lipid ROS, and Fe2+ production in mitochondria. Moreover, the expression of Gpx4, HO-1, FTH1, and Nrf2 was markedly induced by TF3 in the erastin-treated chondrocytes. The antiferroptotic effect of TF3 was related to enhance Nrf2/Gpx4 signaling pathway. Finally, TF3 inhibited OA progression by alleviating in vivo cartilage damage related to chondrocyte ferroptosis. Thus, TF3 significantly inhibits chondrocyte ferroptosis by activating the Nrf2/Gpx4 signaling pathway, suggesting that TF3 serves as a potential therapeutic supplement for OA treatment.

Oxidative stress as a key modulator of cell fate decision in osteoarthritis and osteoporosis: a narrative review

“…The crucial role of ferroptotic cell death in OA progression was recently confirmed in rodent PTOA models [ 153 – 155 ]. Interestingly, antioxidant treatment with natural phenol theaflavin-3,3′-digallate protected human chondrocytes from erastin-induced ferroptosis by promoting the Nrf2-pathway and thus increasing GPX4 and HO-1 expression.…”

Plant molecules reinforce bone repair: Novel insights into phenol-modified bone tissue engineering scaffolds for the treatment of bone defects

“…With the treatment of CUR on iron-overloading MC3T3 cells, the expression and nucleus-translocation of Nrf-2 and FoxO1 (a transcription factor involved in antioxidation and osteogenesis) were enhanced while the IGFR/AKT pathway was suppressed, which synergistically increased GPX4 expression and inhibit ferroptosis [ 44 ]. The same pathway of anti -ferroptosis was also observed in theaflavin-3,3′-digallate [ 45 ].…”

“…Additionally, it is worth noting that osteoclast differentiation can be promoted by iron overloading through the activation of NF-κB and JNK/ERK pathways [ 34 ], which accelerates bone mass loss together with ferroptosis. Recently, curculigoside [ 44 , 45 ] and butein [ 46 ] were proved to be modulators of the ferroptosis in BTCs. With the treatment of CUR on iron-overloading MC3T3 cells, the expression and nucleus-translocation of Nrf-2 and FoxO1 (a transcription factor involved in antioxidation and osteogenesis) were enhanced while the IGFR/AKT pathway was suppressed, which synergistically increased GPX4 expression and inhibit ferroptosis [ 44 ].…”

Targeting Ferroptosis in Bone-Related Diseases: Facts and Perspectives

“… 122 Activation of the Nrf2-GPX4 pathway can ameliorate Erastin-induced ferroptosis in OA chondrocytes. 119 In another study, metformin reversed Erastin-induced ferroptosis and p53 pathway activation in OA chondrocytes. 123 The AMPK pathway is also involved in the regulation of chondrocyte activity and OA.…”