The characteristics of ferroptosis

Ferroptosis is a newly discovered type of cell death characterized by iron-dependent production of ROS and the accumulation of lipid peroxides to lethal levels (Chen et al. Reference Chen, Li, Kang, Klionsky and Tang2021). Compared to common types of cell death, ferroptosis exhibits significant differences in morphological characteristics and biochemical markers (Xie et al. Reference Xie, Hou, Song, Yu, Huang, Sun, Kang and Tang2016). In terms of morphological features, apoptosis is characterized by chromatin condensation, formation of apoptotic bodies, and disintegration of the cytoskeleton. Notably, mitochondrial morphology remains unaltered throughout this process (Li et al. Reference Li, Cao, Yin, Huang, Lin, Mao, Sun and Wang2020). The morphology of necrosis is defined by plasma membrane rupture and the spillover of cellular components into the microenvironment (Dixon et al. Reference Dixon, Lemberg, Lamprecht, Skouta, Zaitsev, Gleason, Patel, Bauer, Cantley, Yang and Morrison2012). Pyroptosis is often accompanied by the formation of pyroptotic bodies prior plasma membrane rupture (Yuan et al. Reference Yuan, Li, Zhang, Kang and Tang2016a). In contrast, the main morphological features of ferroptosis include mitochondrial membrane shrinkage, increased membrane density, reduced volume, and blurred cristae (Chen et al. Reference Chen, Li, Kang, Klionsky and Tang2021). Biochemically, ferroptosis is marked by elevated levels of intracellular free iron (Fe²⁺), inducing a large production of ROS. Additionally, there is a decrease in glutathione (GSH) content and the activity of glutathione peroxidase 4 (GPX4, a selenoprotein that reduces lipid hydroperoxides), leading to a substantial accumulation of the lipid peroxidation product malondialdehyde (MDA), a terminal product and biomarker of lipid peroxidation (Park and Chung Reference Park and Chung2019b). Based on the unique features of ferroptosis in cell morphology and biochemistry, these indicators are typically used to assess ferroptosis (Martinez et al. Reference Martinez, Kim and Yang2020).

Regulatory mechanisms of ferroptosis

Ferroptosis is triggered by the catalytic oxidation of polyunsaturated fatty acids (PUFAs) on the cell membrane by Fe²⁺ or lipoxygenases (LOX; nonheme iron-dependent dioxygenases that directly peroxidize PUFAs). Various molecules involved in the regulation of amino acid metabolism, iron metabolism, lipid metabolism, and mitochondrial metabolism are key regulators of ferroptosis (Fig. 1).

Figure 1. Core pathways of ferroptosis regulation. The pathways triggering ferroptosis ultimately converge on membrane lipid peroxidation as a common endpoint, with multiple metabolic processes involved, including amino acid metabolism, mitochondrial metabolism, iron metabolism, and lipid metabolism. As a plasma membrane receptor, the system Xc⁻ (SLC7A11 and SLC3A2) imports cystine into cells for GSH synthesis, the substrate of GPX4, thereby inhibiting ferroptosis. The kelch-like ECH-associated protein 1 (KEAP1)-P62-nuclear factor erythroid 2-related factor 2 (NRF2) pathway regulates the expression of various antiferroptotic proteins, including system Xc⁻ and GPX4. When cells are deficient in reducing agents such as cysteine, cellular metabolism – particularly oxidative metabolism in mitochondria – leads to ROS accumulation and promotes ferroptosis. Additionally, coenzyme Q10 (CoQ10) and tetrahydrobiopterin (BH4) can suppress ferroptosis independently of GSH. Iron metabolism plays a critical role in ferroptosis activation, primarily involving iron uptake (via transferrin receptor 1, TFRC), storage (in ferritin heavy/light chains, FTH/L), export (via ferroportin, Fpn, SLC40A1), and recycling (through nuclear receptor coactivator 4 [NCOA4]-mediated ferritinophagy and HO-1-mediated heme degradation). These processes regulate intracellular Fe²⁺ levels. Elevated Fe²⁺ reacts with H₂O₂ via the Fenton reaction, generating excessive ROS and ultimately triggering ferroptosis. Furthermore, lipogenesis involves fatty acid uptake (mediated by CD36 and fatty acid-binding protein, FABP) and the synthesis of polyunsaturated fatty acid-containing phospholipids (PUFA-PLs, key substrates for peroxidation), catalyzed by enzymes such as acyl-CoA synthetase long-chain family member 4 (ACSL4). The activation of acyl-CoA synthetase long-chain family member 1 (ACSL1), ACSL4, lysophosphatidylcholine acyltransferase 3 (LPCAT3), and lipoxygenases (LOXs) promotes lipid peroxidation, contributing to ferroptosis progression. Figure created with Biorender.

Amino acid metabolism

The cystine/glutamate transport system (XC^-), a crucial amino acid transport and antioxidant system, is located on the cell membrane. This system consists of solute carrier family 7 member 11 (SLC7A11) and solute carrier family 3 member 2 (SLC3A2) subunits linked through disulfide bonds, forming a functional heterodimer that mediates the 1:1 exchange of extracellular cystine for intracellular glutamate (Sato et al. Reference Sato, Tamba, Ishii and Bannai1999). SLC7A11 serves as the specific transporter for cystine uptake, whereas SLC3A2 plays an essential role in stabilizing the complex and ensuring proper membrane localization of SLC7A11 (Koppula et al. Reference Koppula, Zhang, Zhuang and Gan2018; Nakamura et al. Reference Nakamura, Sato, Yang, Miyagawa, Harasaki, Tomita, Matsuoka, Noma, Iwai and Minato1999; Sato et al. Reference Sato, Tamba, Ishii and Bannai1999). GSH, composed of cysteine, glutamate, and glycine, can bind to toxic free radicals and serves as the substrate for GPX4-catalyzed reactions, converting toxic phospholipid hydroperoxides (PLOOH) to nontoxic phospholipid alcohols phospholipid alcohols (PLOH), thereby clearing lipid ROS and reducing the occurrence of ferroptosis (Yang Reference Yang2014). Erastin, a canonical ferroptosis inducer, directly inhibits XC⁻ system activity (Reina and De Pinto Reference Reina and De Pinto2017). This inhibition comprises cystine uptake, resulting in sustained depletion of intracellular GSH, attenuation of GPX4 activity, and ultimately triggering ferroptosis.

GPX4 is the only known mammalian enzyme that can catalyze the reduction of PLOOH to phospholipid alcohol (Seiler et al. Reference Seiler, Schneider, Förster, Roth, Wirth, Culmsee, Plesnila, Kremmer, Rådmark, Wurst and Bornkamm2008). GPX4 can utilize GSH as a substrate to specifically reduce hydroperoxidized phospholipids and fatty acids, thereby protecting the body from PLOOH-mediated oxidative damage and inhibiting ferroptosis (Ursini and Maiorino Reference Ursini and Maiorino2020). Therefore, GPX4 is a key target for regulating ferroptosis. RSL3 is a GPX4 inhibitor that can covalently bind to GPX4, resulting in its inactivation (Yang Reference Yang2014). In addition to RSL3, several compounds including ML162, DPI, FIN56, and FINO2 have also been identified as GPX4 inhibitors (Cheff et al. Reference Cheff, Huang, Scholzen, Gencheva, Ronzetti, Cheng, Hall and Arnér2023).

NRF2 serves not only as an upstream regulator of GPX4, but also as a master transcription factor governing cellular antioxidant responses, playing a pivotal role in activating the antioxidant defense system. P62-mediated degradation of kelch-like ECH-associated protein 1 (KEAP1) facilitates NRF2 activation in cellular ferroptosis, thereby activating downstream regulatory genes such as SLC7A11, quinone oxidoreductase 1 (NQO1), heme oxygenase 1 (HO-1), and ferritin heavy chain 1 (FTH, an iron-sequestering protein), which confer resistance to ferroptosis by altering iron metabolism and lipid peroxidation (Sun et al. Reference Sun, Ou, Chen, Niu, Chen, Kang and Tang2016).

Therefore, the core amino acid metabolic basis of ferroptosis primarily involves system Xc⁻ dysfunction directly impairs GSH biosynthesis, consequently reducing GPX4 activity and its capacity to scavenge lipid peroxides, while the KEAP1-P62-NRF2 signaling pathway transcriptionally regulates both system Xc⁻ and GPX4 expression to modulate ferroptosis.

Iron metabolism

Disruption of iron metabolism is a fundamental characteristic of ferroptosis. The body’s iron comes from the absorption of exogenous iron and the reutilization of endogenous iron. Dietary iron primarily exists in the form of Fe³⁺, which is reduced to Fe²⁺ by duodenal cytochrome B (DcytB, a brush border ferrireductase) in the intestine, and then absorbed into intestinal epithelial cells (IECs) by the divalent metal transporter 1 (DMT1). The iron can either be directly utilized or stored in ferritin (FTH/L). The iron that enters the IECs is transported into the bloodstream via ferroportin (Fpn, SLC40A1, the only known iron exporter) on the basolateral side. About 60–70% of the body’s iron is found in the hemoglobin of red blood cells. Aging red blood cells are phagocytosed by macrophages, where heme oxygenase 1 (HO-1) degrades heme in lysosomes, releasing iron bound to heme (Wu et al. Reference Wu, Feng, Yu, Yan, Che, Zhuo, Luo, Yu, Wu and Chen2021). The released free iron is pumped out of macrophages by Fpn, re-entering the bloodstream and becoming a major source of endogenous iron (Fleming Reference Fleming2008). Once exogenous or endogenous iron enters the bloodstream, it binds to transferrin (TF) and is transported to various tissue cells, where it binds to transferrin receptors (TFR1) on the cell membrane, allowing it to enter the cells and perform its physiological functions (Guan et al. Reference Guan, Xia, Ji, Chen, Li, Zhang, Liang, Chen, Gong, Dong, Wen, Zhan, Zhang, Li, Zhou, Guan, Verkhratsky and Li2021). The iron that enters the cells not only meets the needs of various cellular physiological activities but also binds to FTH/L to sequester free iron (Park and Chung Reference Park and Chung2019a). Unbound iron poses significant oxidative risk by catalyzing ROS formation. These ROS species then initiate a cascade of free radical chain reactions with PUFAs, ultimately driving their conversion into lipid peroxides. When cellular iron uptake increases while iron storage decreases or efflux becomes impaired, the consequent accumulation of free Fe²⁺ disrupts intracellular iron homeostasis. Excessive free Fe²⁺ not only drives oxidative stress but also compromises mitochondrial function, triggering overproduction of ROS. This leads to nuclear DNA and mitochondrial damage, ultimately resulting in cellular injury, degeneration, and ferroptosis (Jiang et al. Reference Jiang, Stockwell and Conrad2021).

The liver is both a major storage site for iron and a key organ for secreting the iron-regulating hormone hepcidin (Bloomer and Brown Reference Bloomer and Brown2021). Hepcidin regulates serum iron levels by binding to Fpn on the surfaces of macrophages and IECs, leading to its degradation, thereby inhibiting the absorption of exogenous iron or the release of endogenous iron, playing an important role in systemic iron metabolism (Nemeth and Ganz Reference Nemeth and Ganz2021). At the molecular level, iron metabolism is primarily regulated by iron regulatory proteins and iron response elements to maintain intracellular iron homeostasis (Gao et al. Reference Gao, Li, Zhang and Chang2019a). The two work in coordination to maintain the homeostasis of iron metabolism in the body, and any abnormalities in iron metabolism can induce ferroptosis.

Cytosolic labile iron accumulation – resulting from either promoting iron uptake or suppressing iron storage – can trigger ferroptosis initiation (Rochette et al. Reference Rochette, Dogon, Rigal, Zeller, Cottin and Vergely2022). For instance, NCOA4-mediated ferritinophagy degrades FTH/L, releasing stored iron and elevating labile iron levels (Park and Chung Reference Park and Chung2019a); HO-1 overexpression induces heme breakdown (generating biliverdin/bilirubin, CO, and Fe²⁺), which risks intracellular iron overload; hepcidin induces degradation of Fpn (SLC40A1), blocking iron export and causing iron retention. Conversely, downregulating iron homeostasis factors (DMT1, transferrin, TFR1, and FTH) reduces cellular Fe³⁺ influx and alleviates ferroptosis (Liu et al. Reference Liu, Wang, Hou, Gao and Li2025). Thus, the core iron dysregulation in ferroptosis – LIP accumulation – directly catalyzes ROS formation and initiates PUFA peroxidation cascades, ultimately driving iron-dependent lipid peroxidation and ferroptosis.

Lipid metabolism

Ferroptosis is also triggered by the accumulation of lipid ROS. PUFAs can increase membrane fluidity, playing important roles in cellular substance transport, energy conversion, cell recognition, and immunity. Fatty acyl-CoA synthetase long-chain family member 4 (ACSL4; a PUFA-preferring esterification enzyme) and lysolipid acyltransferase 3 (LPCAT3) are important lipid metabolic enzymes responsible for synthesizing phospholipids containing PUFAs (PL-PUFAs; Hashidate-Yoshida et al. Reference Hashidate-Yoshida, Harayama, Hishikawa, Morimoto, Hamano, Tokuoka, Eto, Tamura-Nakano, Yanobu-Takanashi, Mukumoto and Kiyonari2015; Yuan et al. Reference Yuan, Li, Zhang, Kang and Tang2016a). In the presence of Fe²⁺, PL-PUFAs can be converted into PLOOH through both enzymatic and nonenzymatic lipid peroxidation reactions. PLOOH is a specific type of ROS, and its significant accumulation can disrupt the integrity of the lipid bilayer, ultimately affecting the functionality of the cell membrane and leading to ferroptosis (Kagan et al. Reference Kagan, Mao, Qu, Angeli, Doll, Croix, Dar, Liu, Tyurin and Ritov2017). In brief, ferroptosis is driven by PLOOH accumulation: ACSL4 and LPCAT3 synthesize PL-PUFAs, which are catalyzed by Fe²⁺ into PLOOH, disrupting lipid bilayer integrity to execute cell death.

Mitochondrial metabolism

The role of mitochondria in ferroptosis is highly controversial, and whether dysfunction itself can initiate cellular ferroptosis, as well as whether mitochondrial function in ferroptotic cells depends on the environment, remains debated (Battaglia et al. Reference Battaglia, Chirillo, Aversa, Sacco, Costanzo and Biamonte2020). On one hand, mitochondria are the primary site for iron utilization and a major regulator of oxidative metabolism, serving as a significant source of ROS (Murphy Reference Murphy2009). Mitochondrial glutamine catabolism and the electron transport chain (ETC) can induce ferroptosis by promoting cysteine deprivation (Gao et al. Reference Gao, Li, Zhang and Chang2019a). On the other hand, cells lacking mitochondrial DNA exhibit sensitivity to ferroptosis similar to that of cells with intact mitochondrial DNA (Dixon et al. Reference Dixon, Lemberg, Lamprecht, Skouta, Zaitsev, Gleason, Patel, Bauer, Cantley, Yang and Morrison2012). Cells undergoing mitophagy remain susceptible to ferroptosis inhibition by ferrostatin-1 (Fer-1), a radical-trapping compound, even in the absence of functional mitochondria. This demonstrates that mitochondria are dispensable for ferroptosis execution (Gaschler et al. Reference Gaschler, Hu, Feng, Linkermann, Min and Stockwell2018).

Ferroptosis suppressor protein 1 (FSP1, also known as flavoprotein apoptosis-inducing factor mitochondria-associated 2, AIFM2) has been identified as a GSH-independent inhibitor of ferroptosis (Bersuker et al. Reference Bersuker, Hendricks, Li, Magtanong, Ford, Tang, Roberts, Tong, Maimone, Zoncu and Bassik2019). FSP1 functions as an NADH/NADPH-dependent coenzyme Q10 (CoQ10) reductase, consuming NAD(P)H to reduce CoQ10 (ubiquinone) to coenzyme Q10H2 (CoQ10-H2, ubiquinol). CoQ10 is a lipophilic molecule primarily found in the inner mitochondrial membrane (IMM), while CoQ10-H2, as a lipophilic antioxidant, can capture free radicals and prevent lipid peroxidation. It can also indirectly regenerate another antioxidant (α-tocopherol), capturing free radicals to inhibit ferroptosis (Li et al. Reference Li, Liang, Liu, Yi and Zhou2023a). The FSP1-CoQ10-NAD(P)H pathway exists as an independent parallel system that cooperatively suppresses ferroptosis alongside GPX4-GSH (Doll et al. Reference Doll, Freitas, Shah, Aldrovandi, da Silva, Ingold, Goya, Xavier da Silva, Panzilius, Scheel and Mourão2019).

Dihydroorotate dehydrogenase (DHODH), localized on the outer surface of the IMM, operates in parallel with mitochondrial GPX4 (but independently of cytosolic GPX4 or FSP1) by reducing CoQ to CoQH2, which then reduces mitochondrial membrane PLOOH to PLOH, thereby inhibiting ferroptosis (Mao et al. Reference Mao, Liu, Zhang, Lei, Yan, Lee, Koppula, Wu, Zhuang and Fang2021).

Tetrahydrobiopterin (BH4), an essential redox cofactor, plays critical roles in nitric oxide biosynthesis and aromatic amino acid metabolism. Its de novo synthesis is initiated by GTP cyclohydrolase 1 (GCH1), which catalyzes the conversion of guanosine triphosphate (GTP) to BH4 in the rate-limiting step of this pathway (Xu et al. Reference Xu, Wu, Song, Zhang, Wang and Zou2007). Beyond its classical enzymatic functions, BH4 is an effective free radical-capturing antioxidant that can independently protect lipid membranes from auto-oxidation and works synergistically with vitamin E (Soula et al. Reference Soula, Weber, Zilka, Alwaseem, La, Yen, Molina, Garcia-Bermudez, Pratt and Birsoy2020). Notably, GCH1 overexpression has been shown to confer protection against both lipid peroxidation and ferroptosis (Hu et al. Reference Hu, Wei, Wu, Huang, Li, Li, Yin, Peng, Lu, Zhao and Liu2022). Mitochondrial dysfunction promotes ferroptosis (e.g., via ETC-mediated cysteine deprivation) and supports antiferroptotic pathways (FSP1/DHODH/BH4). However, mitochondrial essentiality in ferroptosis remains contentious.

The promoting relationship between viruses and host cellular ferroptosis

Ferroptosis can provide a favorable environment for the survival, replication, and evasion of viruses. Some viruses can inhibit ferroptosis by affecting the host cell’s iron metabolism, lipid metabolism, and mitochondrial metabolism, thereby promoting their own replication and spread. Ferroptosis in host cells can exacerbate viral infections, and inhibiting ferroptosis with ferroptosis inhibitors can reduce the extent of viral infection in host cells.

Viruses inducing ferroptosis by regulating iron metabolism

Iron is one of the essential raw materials for basic metabolism and is a target of competition between the host and the virus (Li et al. Reference Li, Cao, Yin, Huang, Lin, Mao, Sun and Wang2020). Iron is required for viral genome replication and protein synthesis, so viruses must obtain sufficient iron from the host to proliferate within host cells (Wang et al. Reference Wang, Joshua, Jin, Du and Li2022). Studies have indicated that the expression of iron transport proteins inhibits HIV-1 transcription. In THP-1 cells, hepcidin is associated with enhanced HIV-1 transcription, reduced expression of iron transport proteins, and accumulation of intracellular iron (Li et al. Reference Li, Cao, Yin, Huang, Lin, Mao, Sun and Wang2020). Coxsackievirus B3 (CVB3) infection upregulates the expression of TFR1, leading to a large influx of iron into cells, which subsequently causes ferroptosis (Yi et al. Reference Yi, Hu, Wu, Li, Kong, Kang, Zuoyuan and Yang2022).

Viruses inducing ferroptosis by regulating lipid metabolism

ACSL1 is a ferroptosis-activating factor. Research has found that mouse hepatitis virus strain A59 (MHV-A59) can induce ferroptosis in mouse macrophages by promoting the expression of ACSL1; conversely, the ACSL1 inhibitor Triacsin C can inhibit macrophage ferroptosis, thereby protecting the host from MHV-A59 infection (Xia et al. Reference Xia, Zhang and You2021). ACSL4 is an enzyme that esterifies CoA to specific PUFAs and is a key regulator of lipid metabolism and ferroptosis. Further studies have demonstrated that ACSL4 participates in the biogenesis of replication organelles during Coxsackievirus A6 (CV-A6) and SARS-CoV-2 infections, while simultaneously promoting virus-induced ferroptosis. Notably, specific ferroptosis inhibitors (Fer-1, TRO [troglitazone], ROSI [rosiglitazone], and PIO [pioglitazone]) have been shown to significantly restore cellular viability following infection by these viruses (Kung et al. Reference Kung, Chiang, Li, Gong, Chiu, Hung, Huang, Huang, Wang, Hsu and Brewer2022).

Viruses inducing ferroptosis by regulating mitochondrial metabolism

Human herpesvirus 7 (HHV-7) is a type B herpesvirus that can invade the nervous system. Once it enters the central nervous system, it can replicate and trigger immune and inflammatory responses associated with related encephalopathies (Foiadelli et al. Reference Foiadelli, Rossi, Paolucci, Rovida, Novazzi, Orsini, Brambilla, Marseglia, Baldanti and Savasta2021). The mitochondrial electron transport chain serves as a primary source of cellular ROS, with cytochrome c oxidase (COX) functioning as the terminal electron acceptor in this system. As an essential component of oxidative phosphorylation, COX plays an indispensable role in ATP generation in cells (Pajuelo et al. Reference Pajuelo, Čunátová, Vrbacký, Pecinová, Houštěk, Mráček and Pecina2020). Emerging evidence indicates that HHV-7 induces ferroptosis in rat Schwann cells by upregulating COX4I2 expression, ultimately causing peripheral facial nerve damage (Chang et al. Reference Chang, Guan, Wang, Chen, Zhu, Wei and Li2021). Bovine viral diarrhea virus (BVDV) represents a major global threat to both domestic livestock and wild cattle populations worldwide, causing significant economic losses in the cattle industry through its immunosuppressive effects and persistent infections. BVDV can induce ferroptosis through mitochondrial metabolism, primarily by inhibiting the protein levels of NRF2 and downregulating the protein expression of mitochondrial GPX4, leading to ferroptosis in infected cells (Li et al. Reference Li, Zhao, Zhang, Fan, Xue, Chen, Wang and Qi2024).

Viruses inducing ferroptosis by inhibiting the XC^-/GPX4 system

Swine influenza (SI), an acute respiratory disease caused by the IAV, poses significant challenges to the swine industry. Cheng and colleagues demonstrated that infection with H1N1 subtype swine influenza virus (SIV) induced excessive iron uptake and storage, inhibited the XC^-/GPX4 axis, reduced SLC7A11 levels, led to GSH depletion, decreased GPX4 activity and expression, and resulted in the accumulation of lipid peroxidation products, triggering ferroptosis and enhancing viral replication (Cheng et al. Reference Cheng, Tao, Li, Shi and Liu2022). Hepatitis B virus (HBV) remains a major global health challenge, affecting approximately 257 million individuals worldwide and contributing to an estimated 887,000 annual deaths from HBV-related complications (Gentile et al. Reference Gentile, Arcaini, Antonelli and Martelli2023). HBx is a protein associated with HBV and is indispensable in HBV replication and infection (Wang et al. Reference Wang, Zhao, Zhao, Geng, Li, Chen, Yu, Yuan, Zhang, Yun and Yuan2023). HBx can also sensitize hepatocytes to ferroptosis by inhibiting SLC7A11 (Liu et al. Reference Liu, Xu, Tao, Gao and Hou2021). Rotavirus (RV), which causes viral-associated gastroenteritis in infants, can reduce intracellular GSH and enhance lipid peroxidation, triggering ferroptosis through the SLC7A11-AS1/ XC^- axis, thereby facilitating RV replication and the spread of viral particles (Banerjee et al. Reference Banerjee, Sarkar, Mukherjee, Mitra, Gope and Chawla-Sarkar2024). Newcastle disease virus (NDV) is an RNA virus that can cause highly infectious poultry diseases, causing significant economic losses in the global poultry industry. NDV promotes cellular ferroptosis by inhibiting the XC^--GSH-GPX4 axis, activating p53, and inducing ferritinophagy (Kan et al. Reference Kan, Yin, Song, Tan, Qiu, Liao, Liu, Meng, Sun and Ding2021).

Viruses promoting ferroptosis by regulating NRF2

Herpes simplex virus type 1 (HSV-1) is a DNA virus belonging to the Herpesviridae family. Studies have shown that HSV-1 infection enhances the ubiquitin-mediated degradation of NRF2. This degradation leads to marked downregulation of NRF2-dependent antioxidant genes, ultimately disrupting cellular redox homeostasis (Xu et al. Reference Xu, Xu, Ji, Wang, Ren, Xiong, Zhou, Lin, Xu and Qiu2023). Recent research indicates that H1N1 can induce ferroptosis and glutamine catabolism in human nasal epithelial progenitor cells via the KEAP1-NRF2-GCLC signaling pathway, leading to inflammation in the nasal mucosa (Liu et al. Reference Liu, Wu, Bing, Qi, Zhu, Guo, Li, Gao, Cao, Zhao and Xia2023).

The inhibitory relationship between viruses and host cell ferroptosis

Cell death represents a fundamental host defense mechanism wherein infected cells are selectively eliminated to protect uninfected tissues and maintain organismal homeostasis. Pathogens often inhibit cell death to allow for their replication and promote their spread (Ashida et al. Reference Ashida, Mimuro, Ogawa, Kobayashi, Sanada, Kim and Sasakawa2011). After a virus infiltrates the host cell, it can reduce the sensitivity of host cells to ferroptosis by regulating GPX4, NRF2, XC^-, iron metabolism, and other factors.

Viruses inhibiting ferroptosis by upregulating SLC7A11/GPX4 and promoting their own replication

It has also been reported that HBx mediates the upregulation of heat shock protein family A member 8 (HSPA8) expression and stimulates HBV replication, with HSPA8 suppressing ferroptosis in liver cancer cells by upregulating SLC7A11/GPX4 expression and reducing the accumulation of Erastin-mediated ROS and Fe²⁺ in cells, thereby promoting the proliferation of liver cancer cells (Kuo et al. Reference Kuo, Chiu, Hsieh, Huang, Huang, Tzeng, Tsai, Chen, Liu and Chen2020; Wang et al. Reference Wang, Zhao, Zhao, Geng, Li, Chen, Yu, Yuan, Zhang, Yun and Yuan2023). PEDV is a α-coronavirus, primarily infecting intestinal and villous cells in pigs, rapidly spreading and causing diarrheal diseases characterized by vomiting, diarrhea, and dehydration, with a high mortality rate reaching up to 100% in newborn piglets, resulting in significant economic losses in the swine industry (Lin et al. Reference Lin, Zhang, Li, Yang, Zou, Chen and Tang2022). Research has shown that overexpression of GPX4 can inhibit ferroptosis and promote PEDV proliferation. Conversely, inhibiting GPX4 expression with RSL3 and activating ferroptosis suppresses PEDV replication. This indicates that cellular ferroptosis can affect the infection and replication of PEDV in Vero cells (Li et al. Reference Li, Bao, Li, Duan, Dong, Lin, Chang, Tan, Zhang and Shan2023b).

Viruses reducing cellular sensitivity to ferroptosis by activating the KEAP1-P62-NRF2 signaling pathway

Epstein-Barr virus (EBV) is a DNA herpesvirus associated with many human cancers, including nasopharyngeal carcinoma (NPC; Young and Murray Reference Young and Murray2003). Li et al. (Yuan et al. Reference Yuan, Li, Chen, Xia, Luo, Li, Liu, Guo, Liu, Du and Jia2022) reported that EBV infection reduces NPC cells’ sensitivity to ferroptosis by activating the KEAP1-P62-NRF2 signaling pathway and upregulating the expression of SLC7A11 and GPX4. Other studies have shown that EBV dynamically sensitizes B cells to ferroptosis (Burton et al. Reference Burton, Voyer and Gewurz2022). Thus, it is evident that the effects of the same virus on ferroptosis can differ across different cell types.

Activation of ferroptosis via the DHODH pathway can inhibit viral infection

ASFV infection does not inherently induce cellular ferroptosis; however, brequinar (a DHODH inhibitor) can suppress ASFV replication by activating cellular ferroptosis (Chen et al. Reference Chen, Guo, Chang, Song, Wei, Huang, Zheng, Zhang and Sun2023b). Influenza viruses are highly infectious, with a multitude of subtypes and frequent mutations, which limits the development of effective broad-spectrum antiviral strategies. One study showed that metastable iron-sulfur (FeS) relies on Fe²⁺, inducing high levels of lipid peroxidation and free radical production in conserved viral envelopes, leading to viral ferroptosis and resulting in the loss of infectivity and pathogenicity of the influenza virus (Miao et al. Reference Miao, Yin, Chen, Bi, Yin, Chen, Peng, Gao, Qin and Liu2023). Other studies have indicated that high concentrations of iron within host cells can inhibit viral infections, including HSV-1, hepatitis C virus (HCV), and BVDV (Bartolomei et al. Reference Bartolomei, Cevik and Marcello2011; Terpiłowska and Siwicki Reference Terpiłowska and Siwicki2017).

How nutrients activate ferroptosis in the context of viral infection

Emerging evidence indicates that intracellular iron homeostasis modulates neonatal piglet susceptibility to PEDV infection through TFR1-mediated mechanisms. Iron overload, induced by ammonium ferrous citrate (FAC) supplementation, was shown to attenuate PEDV infectivity in both in vitro and in vivo models, likely through competitive inhibition of TFR1 – the established cellular receptor for PEDV (Zhang et al. Reference Zhang, Cao and Yang2020). Tremella fuciformis polysaccharides (TFP) are active components of Tremella mushrooms, with significant antioxidant and anti-inflammatory properties (Ruan et al. Reference Ruan, Li, Pu, Shen and Jin2018). Approximately 10% of gastric cancer cases are associated with EBV, and EBV-infected cells exhibit heightened susceptibility to ferroptosis. The ferroptosis inducer TFP promotes this process through dual inhibitory mechanisms, suppressing NRF2-mediated transcription of HMOX1 (encoding heme oxygenase-1, HO-1) and GPX4, and downregulating xCT (SLC7A11) to impair GSH biosynthesis. Collectively, these actions induce GPX4 dysfunction, triggering lethal phospholipid peroxidation that ultimately eliminates EBV-infected cells (Kong et al. Reference Kong, Liu, Zhu, Zheng, Yin, Yu, Shan, Ma, Ying and Jin2024). Rhein is a naturally occurring anthraquinone extracted from the roots of palm trees, known for its neuroprotective, anticancer, antibacterial, antiviral, antioxidant, and lipid-regulating pharmacological effects. HBx alleviates cell death by inhibiting ferroptosis, whereas rhein can attenuate HBx-induced hepatic stellate cell activation via a GPX4-dependent pathway and diminish HBx-mediated cell death suppression via a GPX4-independent pathway, mitigating hepatic stellate cell fibrosis (Kuo et al. Reference Kuo, Chiu, Hsieh, Huang, Huang, Tzeng, Tsai, Chen, Liu and Chen2020).

How nutrients inhibit ferroptosis in the context of viral infection

Proanthocyanidins (PAs) are flavonoids found in safflower, known for their antioxidant and antiviral properties. Infection with IAV can provoke acute lung injury. While PAs do not inhibit IAV replication, they significantly decrease the levels of MDA and ACSL4 while upregulating GSH, GPX4, and SLC7A11, which can alleviate IAV-induced acute lung injury by inhibiting cellular ferroptosis (Lv et al. Reference Lv, Du, Ma, Shi, Xu, Deng and Chen2023). Excessive death of normal liver cells may lead to severe liver damage, even liver cancer. Selenocysteine (Sec), an essential catalytic residue for GPX4 enzymatic activity, is incorporated into its catalytic center through selenium supplementation, which enhances GPX4 activity, and selenium donors can regulate GPX4 expression and reduce iron-induced ferroptosis in liver cells via the Na₂SeO₃-GPX4 axis, thereby mitigating acute liver injury mediated by HBx infection in normal liver cells (Shi et al. Reference Shi, Liu, Li and Wang2023).