Astaxanthin attenuates osteoarthritis progression via inhibiting ferroptosis and regulating mitochondrial function in chondrocytes.

Ferroptosis is a novel form of regulated cell death that has a close association with mitochondrial dysfunction and is characterized by iron overload, the accumulation of reactive oxygen species (ROS), and lipid ROS. Chondrocytes ferroptosis accelerates the progression of osteoarthritis (OA). Astaxanthin (ATX) is a xanthophyll carotenoid that possesses anti-inflammatory and antioxidant properties and has been explored in research studies for the treatment of diabetes and cardiovascular disease. However, the role it plays in OA, particularly in chondrocyte ferroptosis, has not yet been reported. In this study, ferroptosis-related events were analyzed in rat chondrocytes in vitro. A surgical destabilized medial meniscus was performed for the establishment of in vivo OA model. The results showed that interleukin-1β (IL-1β) induced inflammatory injury in chondrocytes through the promotion of the expressions of inflammatory factors including inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX2). IL-1β triggered chondrocyte ferroptosis by increasing the levels of intracellular ROS, lipid ROS, iron, and mitochondrial iron and inhibiting the expressions of SLC7A11/glutathione peroxidase 4 (GPX4) and Ferritin. The above indices were ameliorated by ferrostatin-1 (Fer-1, a classic ferroptosis inhibitor) and ATX. Furthermore, Fer-1 and ATX rescued the IL-1β-induced down-regulating collagen type II (collagen Ⅱ) and up-regulating matrix metalloproteinase 13 (MMP13). Following treatment with IL-1β, mitochondrial membrane potential decreased and the mitochondrial membrane was broken. At the same time, the mitochondrion shrank, becoming deformed as the mitochondrial cristae reduced and became disrupted. These changes were entirely consistent with ferroptosis features. All the aforementioned phenomena were reversed by Fer-1 and ATX. In addition, intra-articular injection of Fer-1 and ATX delayed articular cartilage degradation and OA progression. This study demonstrated that IL-1β can induce inflammatory damage and ferroptosis in chondrocytes. Both Fer-1 and ATX have the ability to mitigate chondrocyte injury and osteoarthritis progression by inhibiting ferroptosis and the regulation of mitochondrial function. Targeting ferroptosis has the potential to be a promising future treatment method for OA.

Wang X ，Liu Z ，Peng P ，Gong Z ，Huang J ，Peng H ... -  《-》

Icariin inhibits chondrocyte ferroptosis and alleviates osteoarthritis by enhancing the SLC7A11/GPX4 signaling.

Chondrocyte ferroptosis plays a critical role in the pathogenesis of osteoarthritis (OA), regulated by the SLC7A11/GPX4 signaling pathway. Icariin (ICA), a flavonoid glycoside, exhibits strong anti-inflammatory and antioxidant activities. This study investigated whether ICA could modulate the SLC7A11/GPX4 signaling to inhibit chondrocyte ferroptosis and alleviate OA. The objective was to explore the impact of ICA on chondrocyte ferroptosis in OA and its modulation of the SLC7A11/GPX4 signaling pathway. The anti-ferroptosis effects of ICA were evaluated in an interleukin-1β (IL-1β)-treated SW1353 cell model, using Ferrostatin-1 (Fer-1) and Erastin (Era) as ferroptosis inhibitor and inducer, respectively, along with GPX4 knockdown via lentivirus-based shRNA. Additionally, the therapeutic efficacy of ICA on OA-related articular cartilage damage was assessed in rats through histopathology and immunohistochemistry (IHC). IL-1β treatment upregulated the expression of OA-associated matrix metalloproteinases (MMP3 and MMP1), a disintegrin and metalloproteinase with thrombospondin motifs (ADAMTS-5), and increased intracellular ROS, lipid ROS, and MDA levels while downregulating collagen II and SOX9 expression in SW1353 cells. ICA treatment countered the IL-1β-induced upregulation of MMPs and ADAMTS-5, restored collagen II and SOX9 expression, and reduced intracellular ROS, lipid ROS, and MDA levels. Furthermore, IL-1β upregulated P53 but downregulated SLC7A11 and GPX4 expression in SW1353 cells, effects that were mitigated by ICA or Fer-1 treatment. Significantly, ICA also alleviated Era-induced ferroptosis, whereas it had no effect on GPX4-silenced SW1353 cells. In vivo, ICA treatment reduced articular cartilage damage in OA rats by partially restoring collagen II and GPX4 expression, inhibiting cartilage extracellular matrix (ECM) degradation and chondrocyte ferroptosis. ICA treatment mitigated chondrocyte ferroptosis and articular cartilage damage by enhancing the SLC7A11/GPX4 signaling, suggesting its potential as a therapeutic agent for OA interventions.

Xiao J ，Luo C ，Li A ，Cai F ，Wang Y ，Pan X ，Xu L ，Wang Z ，Xing Z ，Yu L ，Chen Y ，Tian M ... -  《-》

Inflammation Triggers Chondrocyte Ferroptosis in TMJOA via HIF-1α/TFRC.

Chen BY ，Pathak JL ，Lin HY ，Guo WQ ，Chen WJ ，Luo G ，Wang LJ ，Sun XF ，Ding Y ，Li J ，Diekwisch TGH ，Liu C ... -  《-》

The RNA-binding protein SND1 promotes the degradation of GPX4 by destabilizing the HSPA5 mRNA and suppressing HSPA5 expression, promoting ferroptosis in osteoarthritis chondrocytes.

Heat shock protein family A member 5 (HSPA5), a recently identified suppressor of ferroptosis, was reported to potentially regulating osteoarthritis. However, the exact role of HSPA5 and how its expression was regulated in osteoarthritis are largely unclear. Rat primary chondrocytes were treated with 10 ng/mL IL-1β for 24 h and incubated with ferrostatin-1 (a ferroptosis inhibitor). Cell viability, production of TNF-α, ROS and MDA, expression levels of collagen II, MMP13, GPX4, and SND1, and Fe2+ concentration were detected. Gain- and loss-of-function manipulations were performed to investigate the effect of HSPA5 on chondrocyte functions, and SND1 shRNA (sh-SND1) was transfected into IL-1β-treated primary chondrocytes alone or together with sh-HSPA5. Furthermore, the interaction between HSPA5 and GPX4 and the regulation of HSPA5 on GPX4 were explored. Finally, SND1 was knocked down in the rats with osteoarthritis, and the histopathology, expression of HSPA5-GPX4 axis, and levels of oxidative stress markers were evaluated. IL-1β treatment could enhance extracellular matrix (ECM) degradation (collagen II reduced and MMP13 increased), promote ferroptosis, manifested by decreased cell viability, increased levels of TNF-α, ROS, MDA, and Fe2+ concentrations, and decreased level of GPX4 protein, and increase SND1 expression in chondrocytes, which could be reversed by ferrostatin-1. Knockdown of SND1 enhanced ECM degradation and suppressed ferroptosis IL-1β-treated chondrocytes, which could be eliminated by knockdown of HSPA5. SND1 bound with HSPA5 at the 3'UTR and destabilized the HSPA5 mRNA. HSPA5 protein directly bound with GPX4 protein and positively regulate its expression. HSPA5 overexpression suppressed IL-1β-induced chondrocyte ferroptosis, while this effect was counteracted by GPX4 silencing. Knockdown of SND1 upregulated HSPA5 and GPX4 in rat cartilage, inhibited inflammatory damage and ferroptosis, and alleviated OA progression. The RNA-binding protein SND1 promotes the degradation of GPX4 by destabilizing the HSPA5 mRNA and suppressing HSPA5 expression, promoting ferroptosis in osteoarthritis chondrocytes.

Lv M ，Cai Y ，Hou W ，Peng K ，Xu K ，Lu C ，Yu W ，Zhang W ，Liu L ... -  《-》

Deferoxamine Alleviates Osteoarthritis by Inhibiting Chondrocyte Ferroptosis and Activating the Nrf2 Pathway.

Objective: Osteoarthritis (OA) is a common disease with a complex pathology including mechanical load, inflammation, and metabolic factors. Chondrocyte ferroptosis contributes to OA progression. Because iron deposition is a major pathological event in ferroptosis, deferoxamine (DFO), an effective iron chelator, has been used to inhibit ferroptosis in various degenerative disease models. Nevertheless, its OA treatment efficacy remains unknown. We aimed to determine whether DFO alleviates chondrocyte ferroptosis and its effect on OA and to explore its possible mechanism. Methods: Interleukin-1β (IL-1β) was used to simulate inflammation, and chondrocyte ferroptosis was induced by erastin, a classic ferroptosis inducer. A surgical destabilized medial meniscus mouse model was also applied to simulate OA in vivo, and erastin was injected into the articular cavity to induce mouse knee chondrocyte ferroptosis. We determined the effects of DFO on ferroptosis and injury-related events: chondrocyte inflammation, extracellular matrix degradation, oxidative stress, and articular cartilage degradation. Results: IL-1β increased the levels of ROS, lipid ROS, and the lipid peroxidation end product malondialdehyde (MDA) and altered ferroptosis-related protein expression in chondrocytes. Moreover, ferrostatin-1 (Fer-1), a classic ferroptosis inhibitor, rescued the IL-1β-induced decrease in collagen type II (collagen II) expression and increase in matrix metalloproteinase 13 (MMP13) expression. Erastin promoted MMP13 expression in chondrocytes but inhibited collagen II expression. DFO alleviated IL-1β- and erastin-induced cytotoxicity in chondrocytes, abrogated ROS and lipid ROS accumulation and the increase in MDA, improved OA-like changes in chondrocytes, and promoted nuclear factor E2-related factor 2 (Nrf2) antioxidant system activation. Finally, intra-articular injection of DFO enhanced collagen II expression in OA model mice, inhibited erastin-induced articular chondrocyte death, and delayed articular cartilage degradation and OA progression. Conclusion: Our research confirms that ferroptosis occurs in chondrocytes under inflammatory conditions, and inhibition of chondrocyte ferroptosis can alleviate chondrocyte destruction. Erastin-induced chondrocyte ferroptosis can stimulate increased MMP13 expression and decreased collagen II expression in chondrocytes. DFO can suppress chondrocyte ferroptosis and promote activation of the Nrf2 antioxidant system, which is essential for protecting chondrocytes. In addition, ferroptosis inhibition by DFO injection into the articular cavity may be a new OA treatment.

Guo Z ，Lin J ，Sun K ，Guo J ，Yao X ，Wang G ，Hou L ，Xu J ，Guo J ，Guo F ... -  《Frontiers in Pharmacology》