Iron metabolism and regulation are crucial for maintaining normal cellular functions (Ward et al., 2014; Zheng and Conrad, 2020; Simao and Cancela, 2021). Transferrin receptor 1 (TfR1) mediates the endocytosis of iron-bound transferrin (TF) (Aisen et al., 1978; Johnsen et al., 2019). TF, a natural chelator abundant in plasma, possesses two high-affinity iron-binding sites. Once TF binds to Fe³⁺ to form holo-TF, it associates with TfR1 on the cell surface and is internalized. In the acidic environment of endosomes, the lowered pH facilitates the release of Fe³⁺ from the Tf-TfR1 complex, allowing TfR1 and apotransferrin (apoTF) to be recycled back to the cell surface (Klausner et al., 1983; Zhou et al., 2021). During this process, divalent metal transporter 1 (DMT1) is crucial for the transmembrane transport of iron, primarily responsible for transporting iron ions from the extracellular space or organelles into the cytoplasm. Metalloreductase six-transmembrane epithelial antigen of prostate 3 (STEAP3) possesses ferrireductase activity, reducing Fe³⁺ to Fe²⁺, which is then released into the cytoplasm via DMT1, contributing to an unstable iron pool (Pantopoulos, 2004; Feng et al., 2020; Koike et al., 2020). Excess iron is stored in ferritin or exported extracellularly through ferroportin 1 (FPN1) (Kakhlon and Cabantchik, 2002).

Intracellular iron overload is a key driver of ferroptosis, facilitated by increased iron uptake and ferritin degradation through ferritinophagy. In ferroptosis-sensitive cells, TfR1 expression is upregulated, enhancing iron uptake, while ferritin heavy chain (FTH1) and ferritin light chain (FTL) undergo selective degradation via ferritinophagy (Santana-Codina and Mancias, 2018; Li et al., 2024). This process is regulated by nuclear receptor coactivator 4 (NCOA4), a critical mediator of intracellular iron homeostasis. NCOA4 recognizes and binds to ferritin, transporting it to lysosomes for degradation (Latunde-Dada, 2017). This releases stored iron, increasing the pool of bioavailable iron (Mancias et al., 2015). Upregulation of NCOA4 significantly elevates intracellular iron levels, further promoting lipid peroxidation and ferroptosis (Masaldan et al., 2018). Additionally, research has found a close interplay between NCOA4 and other ferroptosis-related signaling pathways. For instance, NCOA4-mediated ferritinophagy may impact the activity of glutathione peroxidase 4 (GPX4), as increased iron levels can deplete intracellular antioxidants like glutathione, indirectly inhibiting GPX4 function and thereby facilitating ferroptosis (Mancias et al., 2014).

Additionally, iron overload in ferroptosis is further modulated by key metal ion transporters, including solute carrier family 39 member 14 (Slc39a14) and solute carrier family 39 member 8 (Slc39a8) (Aierken et al., 2024). Slc39a14 primarily facilitates the uptake of non-transferrin-bound iron (NTBI), significantly contributing to intracellular iron accumulation (Aierken et al., 2024). Likewise, Slc39a8 also has a similar function, enhancing iron import and increasing intracellular iron levels (Aierken et al., 2024). Upregulation of these transporters promotes iron overload, lipid peroxidation, and ferroptosis. Conversely, inhibiting Slc39a14 or Slc39a8 has alleviated ferroptosis by reducing intracellular iron levels and mitigating oxidative stress (Aierken et al., 2024).

Together, the processes of ferritinophagy, mediated by NCOA4, and enhanced iron import via Slc39a14 and Slc39a8 synergistically increase intracellular iron levels, solidifying their roles as critical factors in regulating ferroptosis.

Lipid peroxidation, a central driving process of ferroptosis, is a key distinguishing feature from other forms of cell death (Liang et al., 2022). It occurs when reactive oxygen species (ROS) attack polyunsaturated fatty acids (PUFAs) in cellular membranes. ROS, highly reactive molecules derived from molecular oxygen, include superoxide anions, hydrogen peroxide, and hydroxyl radicals. They are primarily generated through enzymatic reactions involving NADPH oxidases (NOXs), cytochrome P450 reductase (POR), and NADH-cytochrome b5 reductase (CYB5R1), with the mitochondrial electron transport chain (mETC) serving as another significant source (Ai et al., 2021; Yan et al., 2021). PUFAs, with their multiple double bonds, are particularly vulnerable to oxidative attack, leading to the formation of lipid peroxidation products (L-OOH) such as malondialdehyde (MDA) and 4-hydroxy-trans-2-nonenal (4-HNE) (Barrera et al., 2015). These toxic byproducts compromise membrane integrity, increase permeability, cause leakage of intracellular components, and trigger inflammatory responses, exacerbating cellular damage (Yang and Stockwell, 2016). Additionally, iron plays a critical role as a cofactor in the biosynthesis of lipoxygenases (LOXs) and cytochrome P450 enzymes, which are central to the generation of ROS during ferroptosis (Zou et al., 2020). Iron metabolism promotes lipid peroxidation through the Fenton reaction (Fe²⁺ + H₂O₂ → Fe³⁺ + ⋅OH + OH⁻), which produces hydroxyl radicals that amplify oxidative stress and accelerate lipid peroxidation, as well as the Haber–Weiss reaction (Dixon et al., 2012).

ROS-driven lipid peroxidation proceeds through three main stages: initiation, propagation, and termination. ROS, such as hydroxyl radicals, abstract allylic hydrogen atoms from PUFAs during initiation, generating lipid radicals (L⋅). In tell as the Haber–Weiss reaction (Dixon et al., 2012), adjacent lipids produce more lipid radicals and lipid hydroperoxides (L-OOH), thus sustaining the chain reaction (Hermetter et al., 2012; Volinsky and Kinnunen, 2013; Que et al., 2018). This process leads to severe oxidative damage if left unchecked, compromising membrane integrity and ultimately triggering ferroptosis.

Notably, the specific composition of membrane phospholipids, particularly the levels of phosphatidylethanolamine (PE) containing polyunsaturated fatty acids (PE-PUFAs), plays a crucial role in determining ferroptosis sensitivity (Kagan et al., 2017). Higher PE-PUFA content increases the susceptibility of cells to lipid peroxidation, thereby elevating the risk of ferroptosis (Kagan et al., 2017). Acyl-CoA synthetase long-chain family member 4 (ACSL4) catalyzes the conversion of PUFAs into PUFA-CoA derivatives, which are then incorporated into PE by lysophosphatidylcholine acyltransferase 3 (LPCAT3) (Kagan et al., 2017). This process enhances membrane susceptibility to oxidative damage, accelerating lipid peroxidation and ferroptosis.

However, lipid peroxidation is not entirely uncontrollable, as multiple regulatory mechanisms exist within cells. Glutathione peroxidase 4 (GPX4), a key inhibitor of ferroptosis, uses glutathione (GSH) as a cofactor to reduce phospholipid hydroperoxides to their corresponding alcohols, thereby protecting cells and membranes from oxidative damage. In addition to the pivotal role of GPX4, recent studies have identified several GPX4-independent pathways that regulate lipid peroxidation and ferroptosis, providing multilayered protection against oxidative stress. Membrane-bound O-acyltransferase 1/2 (MBOAT1/2) is a ferroptosis suppressor (Liang et al., 2023). As a member of the lysophospholipid acyltransferase (LPLAT) family, MBOAT1/2 transfers monounsaturated fatty acids (MUFA) from MUFA-CoA to lysophosphatidylethanolamine (lyso-PE), thereby competitively reducing the incorporation of PUFA-CoA into lyso-PE (Liang et al., 2023). This modification alters the cellular phospholipid profile by increasing PE-MUFA levels while decreasing PE-PUFA levels, the latter being the preferred substrate for lipid peroxidation and a key determinant of ferroptosis sensitivity (Liang et al., 2023). Thus, this selective remodeling decreases the pool of peroxidation-prone phospholipids, offering an alternative pathway to suppress ferroptosis independently of GPX4 and FSP1 (Liang et al., 2023). Moreover, iPLA2β, a member of the calcium-independent phospholipase A2 family, functions independently of glutathione by cleaving oxidized fatty acid chains from phospholipids, directly removing peroxidized products, effectively detoxifying damaged lipids, and maintaining membrane integrity (Chen et al., 2021). This activity is particularly crucial under conditions where GPX4 is absent or impaired, significantly suppressing lipid peroxidation and ferroptosis. Studies have also shown that iPLA2β reduces oxidized phospholipid levels mediated by ALOX12, thereby limiting the accumulation of lipid peroxidation products (Chen et al., 2021). This detoxification mechanism works synergistically with the lipid remodeling functions of MBOAT1 and MBOAT2, forming a multi-layered defense system against ferroptosis.

In summary, lipid peroxidation is central in ferroptosis, driven by ROS-mediated oxidative damage to PUFAs in cellular membranes. While GPX4 is a key regulator in detoxifying lipid peroxides, several GPX4-independent mechanisms, such as lipid remodeling by MBOAT1 and MBOAT2 and lipid detoxification by iPLA2β, provide additional layers of protection. These interconnected mechanisms further illuminate the complexity of ferroptosis regulation and underscore the essential role of lipid peroxidation in its execution.

The antioxidant defense System in cells is critically dependent on glutathione peroxidase 4 (GPX4), a crucial metabolic enzyme that uses glutathione (GSH) to convert lipid peroxides into non-toxic alcohols, thereby minimizing harmful lipid peroxidation and safeguarding cells from ferroptosis. The activity of GPX4 is highly reliant on sufficient intracellular GSH levels, which are synthesized via the cystine/glutamate antiporter System Xc⁻. Comprising the subunits solute carrier family seven member 11 (SLC7A11) and solute carrier family three member 2 (SLC3A2), System Xc⁻ is a vital antioxidant System, facilitating the 1:1 exchange of cystine and glutamate across the cell membrane (Dixon et al., 2014). The imported cystine is reduced to cysteine within the cell, contributing to GSH synthesis (Dixon et al., 2014). GPX4 converts GSH to oxidized glutathione while reducing toxic lipid peroxides (L-OOH) to their corresponding alcohols (L-OH), thus lowering ROS production (Yang and Stockwell, 2016; Zheng and Conrad, 2020). Under normal physiological conditions, reduced GSH is present in concentrations 10 to 100 times greater than oxidized GSH (GSSG), making the GSH/GSSG ratio a common measure of cellular oxidative stress (Em et al., 2013; Lei et al., 2015; Hambright et al., 2017; Tang et al., 2021). Therefore, maintaining adequate GSH levels and GPX4 activity is crucial for cellular antioxidant defense; any disruption to this mechanism can lead to increased oxidative stress and subsequent cellular damage.

The function of GPX4 is precisely regulated by nuclear factor E2-related factor 2 (NRF2), a key transcription factor that activates the expression of various antioxidant genes, including those encoding GSH synthetase and superoxide dismutase (SOD), facilitating the clearance of excess ROS (Xie et al., 2016; Tang et al., 2021). Under normal conditions, NRF2 is tightly suppressed by Kelch-like ECH-associated protein 1 (KEAP1), which mediates NRF2 degradation through ubiquitination (Kobayashi et al., 2004). However, under oxidative stress, KEAP1 undergoes a conformational change that relieves its suppression, allowing NRF2 to stabilize and upregulate antioxidant gene expression (Sun et al., 2016).

In addition to GPX4 and NRF2, cells employ various antioxidant mechanisms, including SOD, catalase (CAT), and vitamins C and E, to combat oxidative stress (Chen et al., 2016). SOD effectively catalyzes the conversion of superoxide radicals into water and oxygen, serving as the first line of antioxidant defense, while CAT further decomposes hydrogen peroxide to prevent harmful hydroxyl radical formation (Yuewei et al., 2014; Baker et al., 2023). Vitamins C and E enhance cellular antioxidant capacity through their hydrophilic and lipophilic properties, respectively (Tm et al., 2019; Hu Q et al., 2021). However, inflammatory factors such as interleukin-1β (IL-1β) and tumor necrosis factor-alpha (TNF-α) can significantly inhibit SOD and CAT activity, reduce levels of vitamins C and E, and activate the nuclear factor-kappa B (NF-κB) pathway, exacerbating oxidative stress and stimulating inflammatory responses, thereby creating a vicious cycle (Ueda and Takasawa, 2018).

Additionally, the NADPH/FSP1/CoQ10 pathway, through the action of FSP1, reduces CoQ10 with NADPH, further inhibiting lipid peroxidation and ferroptosis (Frei et al., 1990). Research also indicates that the gtp cyclohydrolase 1/Tetrahydrobiopterin/dihydrofolate reductase (GCH1/BH4/DHFR) pathway, particularly DHFR, suppresses ferroptosis by promoting BH4 synthesis; inhibiting DHFR leads to decreased BH4 production, thereby enhancing lipid peroxidation (Soula et al., 2020; Fanet et al., 2021).

Mitochondria, as central organelles for iron, calcium, lipid, and amino acid metabolism, have limited iron content. However, elevated iron levels can disrupt mitochondrial iron homeostasis (Beckman and Ames, 1998). Research has demonstrated that inhibiting mitochondrial tricarboxylic acid cycles or electron transport chains can lower mitochondrial membrane hyperpolarization and lipid peroxidation, underscoring the critical role of mitochondrial pathways in ferroptosis (Steiner and Lang, 2017; Haileselassie et al., 2019).

In summary, the ferroptosis-related biological components discussed above are presented in Table 1 and Figure 1. Figure 1 was created using Adobe Illustrator 2019 (Adobe Inc., San Jose, CA, USA). The design of the signaling pathways related to iron metabolism, the Fenton reaction, lipid peroxidation, and antioxidant pathways was inspired by the overall concepts and graphical elements from the literature to ensure scientific accuracy and rigor (An et al., 2023).

TfR1 expression is elevated in OA patients’ synovial tissue and chondrocytes, making it a potential early diagnostic marker that reflects disease progression. Its integration with imaging techniques can enhance diagnostic accuracy, facilitating timely intervention. Research on TfR1 has identified several therapeutic interventions. For example, ferristatin II promotes the degradation of TfR1, disrupting Tf-mediated iron delivery and intervening in the pathological processes of OA (Yuewei et al., 2014). Additionally, Biochanin A (BCA) can reduce intracellular iron levels by suppressing TfR1 activity and enhancing the expression of ferroportin (FPN), thereby alleviating mitochondrial damage and chondrocyte apoptosis induced by iron overload (He Q et al., 2023).

Iron chelators represent an effective intervention for patients with excessive TfR1 expression, binding circulating and intracellular iron for excretion via urine or bile, thereby reducing ferroptosis (Di Maggio and Maggio, 2017). Commonly used iron chelators include deferoxamine (DFO), deferiprone (DFP), and deferasirox (DFS) (Rodrigues de Morais and Gambero, 2019). In vitro studies have demonstrated that DFO can inhibit the degradation of type II collagen in osteoarthritis cartilage while also reducing the expression of inflammatory factors such as MMP-1, MMP-13, IL-1β, and TNF-α (Tchetina et al., 2016). Furthermore, DFO can restore ferritin levels by inhibiting NCOA4 expression and chelating excess iron to regulate iron homeostasis. These findings indicate that iron chelators regulate iron levels and contribute to managing inflammation associated with OA.

However, existing iron chelators exhibit side effects in clinical applications, including gastrointestinal discomfort, hepatotoxicity, and nephrotoxicity (Guo et al., 2024). Thus, developing novel iron chelators, particularly nanoscale formulations, may represent a future direction to reduce side effects while maintaining or enhancing therapeutic efficacy (Kalanaky et al., 2016). Additionally, the compound White Cardamonin (CAR), derived from Vitex negundo, protects cartilage by mitigating iron overload-induced chondrocyte damage and apoptosis (Li S et al., 2023). CAR activates the SIRT1 pathway and inhibits the p38 MAPK signaling pathway, reducing NLRP3 inflammasome production and alleviating inflammation and cartilage degeneration (Li S et al., 2023). It also reverses the reduction in type II collagen expression and the elevation of MMPs caused by iron overload, thereby mitigating chondrocyte degeneration (Li S et al., 2023).

Based on TfR1-mediated iron uptake and ferroptosis mechanisms, researchers are exploring possibly delaying OA progression by intervening in ferroptosis. Inhibiting TfR1 expression may reduce chondrocyte ferroptosis and diminish synovial inflammation, slowing OA advancement. Currently, ferroptosis inhibitors such as Ferrostatin-1 and Liproxstatin-1 have entered clinical trials, potentially leading to precision treatment strategies that integrate TfR1 detection techniques (Li S et al., 2023).

Despite the promising clinical prospects of TfR1 in OA, challenges remain in its practical application. Future research should further validate the specificity and sensitivity of TfR1 as an early diagnostic marker and develop cost-effective detection technologies. Moreover, multi-omics analyses could help elucidate the interactions between TfR1 and other ferroptosis regulatory molecules, such as GPX4, providing a comprehensive perspective to support personalized treatment strategies.

DMT1 plays a crucial role in the transport of iron ions, and its abnormal expression in OA patients is closely associated with disease progression. Research has shown that the upregulation of DMT1 results in excessive iron accumulation within chondrocytes, increasing the risk of cellular damage (Li S et al., 2023). Research indicates that DMT1 is critical in the progression of osteoarthritis (OA) driven by iron overload; inhibiting DMT1 alleviates IL-1β-induced inflammatory responses and extracellular matrix degradation by significantly suppressing the MAPK and PI3K/AKT/NF-κB signaling pathways (Liu et al., 2024). This finding suggests that regulating the activity of the iron transporter DMT1 could offer a novel therapeutic target for OA.

Implementing DMT1 inhibitors as an intervention strategy demonstrates significant therapeutic potential (Jing et al., 2020). Additionally, multi-target combination strategies are gaining attention. For instance, combining DMT1 inhibitors with antioxidants can yield synergistic effects across multiple pathways. This approach reduces iron ion accumulation, suppresses ferroptosis, and enhances antioxidant defense mechanisms, thereby protecting chondrocytes from oxidative stress damage and effectively slowing OA progression.

Ferritin consists of heavy chain ferritin (FTH1) and light chain ferritin (FTL), and it primarily functions to store intracellular iron, preventing excessive accumulation of free iron and reducing cellular iron toxicity (Arosio et al., 2017). In OA patients, alterations in ferritin expression and stability lead to elevated levels of free iron, heightening the risk of ferroptosis. Studies have shown that in models of iron overload and destabilization of the medial meniscus (DMM)-induced OA, FTH1 expression is significantly elevated, accompanied by increased ferritin levels in the synovial tissue (Yuan et al., 2024). Thus, monitoring changes in both FTH1 and FTL may provide new insights for early OA diagnosis.

Combining the detection of ferritin with other ferroptosis biomarkers, such as TfR1, DMT1, and GPX4, holds promise for enhancing diagnostic sensitivity and accuracy, thereby offering stronger support for early intervention. Additionally, variations in ferritin levels may serve as auxiliary indicators for evaluating the efficacy of antioxidant treatments (Arosio et al., 2017). The concurrent use of antioxidants, such as N-acetylcysteine (NAC), may improve treatment precision and reduce adverse effects (de Andrade et al., 2015; Li et al., 2022).

Furthermore, ferritin plays a dual role in iron metabolism imbalance; while it helps sequester excess free iron, it may also act as a source of free iron during ferroptosis (Bauckman et al., 2015; Bellelli et al., 2016). Research has identified YL-939, a ferroptosis inhibitor targeting prohibitin 2 (PHB2), which can reduce iron levels in the labile iron pool (LIP) by modulating ferritin expression and uptake (Yang et al., 2022a). Consequently, in future developments of ferroptosis inhibitors, ferritin is anticipated to be a potential target. Its combination with iron chelators and agents that regulate ferritin could further enhance intervention strategies for ferroptosis, providing new avenues for OA treatment.

FPN is mammalian cells’ sole iron exporter, pivotal in maintaining intracellular iron homeostasis. Recent studies have highlighted the significance of FPN in regulating ferroptosis. The degradation of FPN, mediated by the E3 ubiquitin ligase RNF217, leads to intracellular iron accumulation, thereby increasing susceptibility to ferroptosis (Jiang et al., 2021). Therefore, maintaining proper FPN function is crucial for preventing iron overload and subsequent ferroptotic cell death in joint tissues.

Therapeutic approaches to prevent FPN degradation may hold promise for mitigating OA progression. For instance, targeting the RNF217-mediated degradation pathway of FPN could help preserve its function, thereby reducing intracellular iron accumulation and the risk of ferroptosis. Additionally, combining such approaches with antioxidants or ferroptosis inhibitors might synergize in protecting chondrocytes and synovial cells from iron-induced damage (Jiang et al., 2021).

Further research is needed to elucidate the precise role of FPN in OA and to develop targeted therapies that modulate its expression or activity. Understanding the interplay between iron metabolism, FPN regulation, and ferroptosis will be essential in devising effective interventions for OA and other iron-related pathologies.

Hepcidin and NCOA4 play crucial roles in regulating iron homeostasis and ferroptosis, and their abnormal expression is closely linked to the progression of OA (Bellelli et al., 2016; Wang and Babitt, 2019). Hepcidin, a central regulatory hormone in iron metabolism, promotes the degradation of FPN, leading to decreased extracellular iron export and subsequent intracellular iron overload (Wang and Babitt, 2019). This mechanism exacerbates chondrocyte damage associated with ferroptosis in OA patients. Concurrently, NCOA4 mediates the autophagy of ferritin, releasing stored iron and further increasing free iron levels within cells (Bellelli et al., 2016). This process induces oxidative stress and lipid peroxidation, accelerating ferroptosis and driving the progression of OA.

Targeting these mechanisms by inhibiting the activity of hepcidin and NCOA4 offers new therapeutic avenues for OA. Recently, a class of ferroptosis inhibitors that target NCOA4 has been identified. These compounds bind to NCOA4, disrupting its interaction with FTH1 and inhibiting NCOA4-dependent ferritin autophagy, thereby reducing intracellular free iron (Fe²⁺) levels and suppressing ferroptosis (Fang et al., 2021).

MDA and 4-HNE are key end products of lipid peroxidation and significant markers of ferroptosis. Their levels are markedly elevated in OA patients’ synovial fluid, cartilage, and serum and positively correlate with disease severity. Thus, MDA and 4-HNE are considered effective biomarkers for reflecting the progression of OA (Shah et al., 2005; Mas-Bargues et al., 2021). Studies show that MDA levels significantly increase in IL-1β- or erastin-induced OA mouse models, while 4-HNE and its protein adducts rise in the synovial fluid and chondrocytes of OA patients, underscoring the critical role of lipid peroxidation in OA pathology (Grigolo et al., 2003; Shah et al., 2005; Gladkova, 2022).

Targeting this mechanism, antioxidants like astaxanthin exhibit potential therapeutic effects (Wang et al., 2022a). Astaxanthin mitigates the downregulation of ferroptosis-related proteins induced by IL-1β by downregulating p53 expression, effectively inhibiting chondrocyte ferroptosis (Wang et al., 2022a). Forkhead Box O3 (FOXO3), an important transcription factor, reduces lipid peroxidation and intracellular iron accumulation by upregulating antioxidant genes and inhibiting the NF-κB/MAPK signaling pathway, thereby lessening chondrocyte ferroptosis and ECM degradation (Zhao et al., 2023). In vitro experiments indicate that stimulating FOXO3 expression significantly decreases the generation of ferroptosis-related markers like MDA, suggesting its potential to suppress OA progression (Zhao et al., 2023).

Moreover, Tanshinone IIA (Tan IIA) can inhibit lipopolysaccharide (LPS)-induced iron hypersensitivity by lowering iron, reactive oxygen species, and MDA levels while increasing glutathione (GSH) levels (Xu J et al., 2023). These findings suggest that Tan IIA may demonstrate potential clinical value in OA treatment by improving oxidative stress conditions. Recent studies show that naringin (NAR), an active component of grapefruit, possesses significant anti-inflammatory and antioxidant properties (Pan et al., 2022). In vitro, NAR has been found to reduce intracellular MDA levels and ROS accumulation while upregulating the antioxidant gene NRF2, indicating its ability to alleviate oxidative stress and chondrocyte damage induced by iron overload (Pan et al., 2022).

As terminal products of lipid peroxidation, MDA and 4-HNE directly reflect the extent of lipid oxidative damage within cells. Therefore, monitoring these biomarkers can aid in the early diagnosis of OA and serve for disease monitoring and prognostic assessment, facilitating the development of more targeted treatment strategies.

GPX4 is a crucial enzyme inhibiting ferroptosis, protecting cell membranes from oxidative damage by reducing lipid peroxides. A decline in GPX4 function directly increases the risk of ferroptosis, making its expression changes in OA a significant marker for assessing this risk. Clinically, monitoring GPX4 levels in articular cartilage can enhance the accuracy of early OA diagnosis.

Recent studies have explored therapeutic strategies targeting the GPX4 axis to suppress ferroptosis. For example, icariin (ICA) can upregulate GPX4 expression, reducing MDA levels and iron content in synovial cells, thereby activating the System Xc⁻/GPX4 axis to inhibit ferroptosis and alleviate synovial inflammation (Wang et al., 2016; Xiao et al., 2024). Such research opens possibilities for developing GPX4-based OA treatments (Xiao et al., 2024). Additionally, thiazolidinedione (TZD) drugs selectively inhibit ACSL4 activity, significantly reducing lipid peroxidation and ferroptosis (Doll et al., 2017).

Combining GPX4 with iron chelators, antioxidants, or free radical scavengers such as Fer-1, Lip-1, vitamin E, or edaravone can further enhance its protective effects, reducing lipid oxidative damage and slowing OA progression (Kagan et al., 2017; Homma et al., 2019). Studies indicate that in mild OA patients, using ferroptosis inhibitors like Ferrostatin-1 (Fer-1) can significantly upregulate GPX4 and SLC7A11 expression while downregulating ACSL4 expression, suggesting the potential for early intervention with these inhibitors (Y. Xu Y et al., 2023). However, this regulatory effect weakens in moderate to severe OA patients, indicating that early treatment may be more effective, with additional therapies needed in later stages for optimal results (Xu Y et al., 2023).

In clinical practice, selecting ferroptosis inhibitors or antioxidants based on GPX4 level changes can substantially improve patient outcomes. For patients with markedly reduced GPX4 expression, antioxidants like NAC could enhance antioxidant capacity and delay disease progression. Although GPX4’s potential in OA treatment is evident, further validation as a therapeutic target is necessary. Future research should explore GPX4’s specific roles in different OA subtypes, developing personalized treatments based on GPX4.

MBOAT1/2, as critical membrane-bound O-acyltransferases, functions by incorporating monounsaturated fatty acids (MUFA) into phospholipids, thereby reducing polyunsaturated fatty acids (PUFA) levels. This mechanism decreases the proportion of peroxidation-prone phospholipids, thereby enhancing cellular resistance to ferroptosis. These enzymes have demonstrated potential therapeutic value in mitigating lipid peroxidation and ferroptosis (Liang et al., 2023). Studies have shown that these enzymes are transcriptionally regulated by sex hormone receptors—estrogen receptor (ER) and androgen receptor (AR)—which mediate ferroptosis surveillance independent of GPX4 and FSP1 (Liang et al., 2023).

Postmenopausal women experience a significant decline in estrogen levels, associated with an increased incidence of OA (Parazzini and Progretto Menopausa Italia Study Group, 2003; Herndon, 2004; Høegh-Andersen et al., 2004). Researchers using an ovariectomized rat model found that the decline in estrogen levels significantly increased the metabolic activity of subchondral bone, leading to frequent microdamage and remodeling. This process resulted in increased subchondral bone stiffness, which subsequently altered the local biomechanical environment of the joint, exacerbating cartilage damage and accelerating the progression of OA (Sowers et al., 1996; Wu et al., 2019; Xu et al., 2019; Ziemian et al., 2021). Given the pivotal role of MBOAT1/2 in suppressing oxidative stress and ferroptosis, strategies aimed at restoring their functions may offer therapeutic benefits in addressing joint damage associated with sex hormone deficiencies (Liang et al., 2023). For instance, hormone replacement therapy (HRT) or pharmacological agents mimicking estrogen may enhance the protective role of MBOAT1, thereby inhibiting ferroptosis and lipid peroxidation (Liang et al., 2023).

Targeted therapeutic strategies that regulate MBOAT1/2 activity, particularly for hormone-deficient populations, could serve as a promising approach to delay OA progression. Combining MBOAT1/2-enhancing interventions with antioxidants or ferroptosis inhibitors may yield synergistic effects. Future research should focus on elucidating the specific mechanisms of hormone-MBOAT1/2 interactions in OA treatment and further validating their clinical applications in personalized therapies.

Lipid-ROS are reactive oxygen species produced during lipid peroxidation, and their accumulation is a core feature of ferroptosis. In OA, elevated levels of Lipid-ROS are closely linked to chondrocyte death and cartilage degradation. Monitoring Lipid-ROS levels can aid in assessing OA progression and provide a basis for dynamically adjusting treatment strategies.

In the context of ferroptosis regulation, inhibiting Lipid-ROS generation is a crucial therapeutic approach for OA. Ferroptosis inhibitors like Fer-1 and Liproxstatin-1 (Lip-1) effectively reduce the accumulation of Lipid-ROS, thereby inhibiting chondrocyte ferroptosis and delaying OA progression (Skouta et al., 2014; Shah et al., 2017; Guo et al., 2022). While both Lip-1 and Fer-1 operate through similar mechanisms, Lip-1 possesses better pharmacokinetic properties, allowing it to inhibit ferroptosis effectively at lower doses (Wang et al., 2022c). However, these compounds have limitations in solubility and half-life, necessitating further optimization to enhance clinical applicability.

Melatonin has emerged as an important adjunct in combating OA due to its suppressing oxidative stress caused by iron overload (Yang et al., 2017). It inhibits ROS accumulation and protects stem cell osteogenic differentiation and proliferation by modulating signaling pathways like p53, ERK, and p38 (Yang et al., 2017). Other antioxidants also show potential in protecting cartilage by inhibiting Lipid-ROS. For instance, metformin reduces OA cartilage damage by inhibiting lipid peroxidation (Li et al., 2020); NAC prevents osteoblast apoptosis by inhibiting ROS production (Tian et al., 2016); resveratrol effectively reduces bone loss due to its potent antioxidant capabilities (Zhao et al., 2015); and tea polyphenols promote bone formation while reducing bone resorption through their antioxidant and anti-inflammatory properties (Shen et al., 2013). While these antioxidants hold great promise for OA treatment, further studies are required to validate their safety and efficacy before clinical application. Future therapeutic directions should focus on developing more targeted Lipid ROS inhibitors and utilizing advanced imaging techniques to monitor real-time dynamic changes in Lipid ROS levels.

Nrf2 is a key transcription factor that regulates the expression of antioxidant genes, directly influencing a cell’s antioxidant capacity. In OA, one of the core mechanisms of ferroptosis is the imbalance between lipid peroxidation and the antioxidant defense system. Nrf2 can effectively inhibit lipid peroxidation and mitigate cellular damage by regulating the expression of antioxidant enzymes such as GPX4. Therefore, activating Nrf2 offers a potential therapeutic strategy for intervening in ferroptosis in OA.

Studies have shown that Nrf2 activators, such as sulforaphane (SFN), can significantly reduce the generation of lipid peroxidation products by increasing GPX4 levels, thereby alleviating ferroptosis-induced damage to chondrocytes (Calabrese and Kozumbo, 2021; Mahn and Castillo, 2021). As a potent antioxidant, Pyrroloquinoline quinone (PQQ) may also reduce lipid peroxidation, though its direct impact on GPX4 regulation remains further elucidated (Li J et al., 2023). Additionally, ergosterol (ER) has been found to enhance Nrf2 activity, inhibiting molecules related to ferroptosis, such as MMP-9 and MMP-13, which strengthens the cell’s resistance to oxidative stress and protects chondrocytes from damage (Cai et al., 2021). Preclinical studies have validated the safety of Nrf2 activators, laying the groundwork for their clinical application in OA.

SOD and CAT are essential enzymes in the antioxidant defense system. SOD converts superoxide anions (O₂⁻) into hydrogen peroxide (H₂O₂), which is then decomposed by CAT into water and oxygen, thereby alleviating oxidative stress. In osteoarthritis (OA), the inhibition of the Nrf2 pathway leads to decreased activity levels of SOD and CAT, impairing the antioxidant defense system’s ability to eliminate reactive ROS and increasing the risk of ferroptosis effectively. Since SOD and CAT neutralize excess ROS, their reduced activity directly reflects weakened antioxidant capacity and exacerbated ferroptosis.

Therefore, monitoring the activity levels of SOD and CAT can serve as supplementary indicators for assessing the antioxidant defense status and ferroptosis risk in OA patients. The significant roles of SOD and CAT in antioxidant defense and ferroptosis suppression also highlight the therapeutic potential of combining antioxidants with ferroptosis inhibitors. Employing a multi-target intervention strategy that includes anti-inflammatory drugs, antioxidants, and ferroptosis inhibitors can more effectively control oxidative stress and the ferroptosis process.

In terms of personalized treatment, adjusting therapeutic strategies based on the activity levels of SOD and CAT can optimize the suppression of ferroptosis according to the patient’s antioxidant capacity. Future research should focus on exploring the regulatory mechanisms of SOD and CAT, particularly on how to restore antioxidant defense capabilities when the Nrf2 pathway is inhibited in order to halt the progression of OA.

HIF-2α plays a significant role in the progression of OA, particularly in regulating the sensitivity of chondrocytes to ferroptosis. Studies indicate that HIF-2α, upon stimulation by inflammatory factors such as IL-1β, leads to a decrease in GSH levels, thereby increasing chondrocytes’ sensitivity to lipid peroxidation and ferroptosis. This process weakens the cellular antioxidant defense, accelerating chondrocyte death and the progression of OA pathology. Research has also shown that supplementing D-mannose can reverse this change, restoring GSH levels and enhancing the expression of GPX4 and SLC7A11, which reduces the occurrence of ferroptosis (Zhou et al., 2021).

The weakening of cellular antioxidant defenses caused by reduced GSH levels accelerates chondrocyte death and drives the progression of OA pathology. Future therapeutic strategies targeting HIF-2α-related pathways to modulate chondrocyte ferroptosis responses may effectively inhibit OA progression. Additionally, the potential of combining HIF-2α with other ferroptosis inhibitors warrants further exploration. By regulating oxidative stress responses within cartilage, combination therapies could more effectively address the sensitivity issues associated with HIF-2α-mediated ferroptosis and suppress OA deterioration. Clinical research should further validate the potential application of HIF-2α in personalized treatment, alongside ferroptosis markers like GPX4, to precisely regulate the survival environment of chondrocytes, advancing and refining OA treatment.

FtMt, localized in mitochondria, is essential for maintaining iron homeostasis by reducing free iron ions and mitigating oxidative stress, thereby inhibiting ferroptosis (Wang et al., 2022b). FtMt deficiency has been shown to cause mitochondrial iron overload and oxidative stress, triggering ferroptosis through enhanced mitophagy (Wang et al., 2022b). In OA, these processes may contribute to cellular damage and disease progression. Ferroptosis inhibitors, such as Fer-1, have demonstrated the potential to alleviate oxidative stress, restore mitochondrial integrity, and reduce lipid peroxidation damage (Chen J et al., 2024). Additionally, significant rescue of IL-1β-induced loss of mitochondrial membrane potential is achieved by inhibiting hypoxia-inducible factor 1α (HIF-1α) or TfR1, indicating that protecting mitochondrial function plays a crucial role in preventing chondrocyte ferroptosis and degeneration (Chen B. Y. et al., 2024). Research has shown that Catalpol, an active component of traditional medicine, can promote mitochondrial biogenesis by inducing the expression of key regulators like PGC-1α, NRF1, and TFAM (Chen et al., 2022). It also enhances the expression of mitochondrial and nuclear DNA, increasing mitochondrial respiration rates and ATP production (Chen et al., 2022). These findings suggest that Catalpol may alleviate oxidative stress and ferroptosis by enhancing mitochondrial function, which could positively influence OA progression. Recent studies indicate that astragalus polysaccharides (APS) can significantly mitigate the damage caused by iron overload to the function of bone marrow mesenchymal stem cells by suppressing ROS levels within mitochondria (F. Yang et al., 2016). These findings further support the therapeutic potential of improving chondrocyte health in OA through mitochondrial function regulation.

In addition to conventional antioxidant and iron regulation strategies, botulinum toxin type A (BoNT/A) has emerged as a promising therapeutic approach for alleviating osteoarthritis (OA) by inhibiting chondrocyte ferroptosis. The mechanisms of BoNT/A include reducing reactive oxygen species (ROS) and iron ion accumulation, restoring mitochondrial function, and activating the SLC7A11/GPX4 anti-ferroptotic pathway (Zeng et al., 2024). Furthermore, the successful application of BoNT/A in experimental models offers valuable insights into its potential clinical translation in OA treatment. Future studies exploring the detailed mechanisms and long-term effects of BoNT/A may pave the way for precision OA therapy targeting ferroptosis regulation.

In summary, the ferroptosis-related biological molecules discussed in this section are presented in Table 2, while the small molecules and drugs are listed in Table 3.