Molecular Basis of Ferroptosis-Immune Metabolism Crosstalk

Ferroptosis is a form of metabolic cell death jointly driven by disruption of iron homeostasis, accumulation of membrane lipid peroxidation, and failure of lipid antioxidant defense systems. Its occurrence does not depend on a single molecular change, but rather on the relative relationship among the labile iron pool, oxidizable membrane lipid substrates, and reducing-equivalent defense systems. As the field has advanced, ferroptosis has no longer remained confined to discussion of tumor-cell-intrinsic death mechanisms, but has instead been reanalyzed within the framework of immunometabolism: cystine utilization, lipid remodeling, and iron handling in tumor cells determine their basal susceptibility, whereas the metabolic states of effector immune cells and myeloid cells determine whether ferroptosis induction in the microenvironment can be translated into effective immune clearance.

Keywords: ferroptosis; immunometabolism; lipid peroxidation; SLC7A11; GPX4; FSP1; NCOA4; CD8+ T cells

1. Research Objects in Ferroptosis-Immune Metabolism Crosstalk

1.1 Metabolic properties of ferroptosis

(1) Labile iron pool

The oxidative driving force of ferroptosis arises from the labile iron pool that can amplify lipid radical reactions, rather than from a generalized increase in total iron content. TFR1 mediates iron uptake, FTH1 participates in iron storage, FPN is responsible for iron export, and NCOA4 mediates ferritinophagy. Together, these processes determine whether a cell remains in an iron-buffered state or enters an iron-exposed state. For ferroptosis, what is truly decisive is whether labile iron reaches a level sufficient to continuously drive the chain reaction of lipid peroxidation.

(2) Membrane lipid susceptibility

Ferroptosis displays marked selectivity for lipid substrates. ACSL4 activates polyunsaturated fatty acids such as arachidonic acid and adrenic acid, and LPCAT3 further incorporates them into membrane phospholipids, thereby placing the membrane system into a highly oxidation-prone state. Ferroptosis is therefore not a form of generalized oxidative injury, but rather a program of metabolic membrane damage occurring in a specific membrane-lipid context.

(3) Lipid antioxidant defense

The system xc−-GSH-GPX4 axis is the most classical anti-ferroptotic defense line. SLC7A11/SLC3A2 mediates cystine import, GSH provides reducing equivalents, and GPX4 reduces membrane lipid hydroperoxides to relatively stable lipid alcohols. In addition, parallel defense systems such as FSP1-CoQ10 and GCH1-BH4 can also provide alternative protection in different cellular contexts. Accordingly, ferroptosis sensitivity fundamentally reflects the balance between lipid oxidative pressure and antioxidant capacity.

1.2 Analytical significance of immunometabolic crosstalk

(1) Metabolic competition in the tumor microenvironment

Tumor cells, CD8+ T cells, NK cells, dendritic cells, and myeloid cells share the same metabolic niche. Glucose competition, lactate accumulation, lipid overload, hypoxia, and abnormal iron redistribution do not act separately on different cell types, but instead simultaneously shape the metabolic states of multiple cell populations. Therefore, whether ferroptosis occurs cannot be judged independently of the immunometabolic background.

(2) Microenvironmental properties of ferroptosis

Ferroptosis is both a potential vulnerability of tumor cells and a metabolic risk point for immune cells. The same lipid peroxidation and iron stress may manifest as pro-death in tumor cells, as functional decline in effector T cells, and as inflammatory amplification in myeloid cells. Thus, the technical object of ferroptosis research is not a single cell-death event, but the differential responses of multiple cell types within the same microenvironment.

2. Molecular Determinants of Ferroptosis Sensitivity in Tumor Cells

2.1 Iron supply and ferritinophagy layer

(1) Iron import and iron buffering

Upregulation of TFR1 usually indicates enhanced iron import, whereas reduction of FTH1 implies weakened iron-buffering capacity. Together, these determine whether the free iron pool expands. In technical assessment, measuring total iron alone is usually insufficient; more informative readouts include changes in the labile iron pool, ferritin levels, and ferritin turnover status.

(2) NCOA4-dependent ferritin turnover

NCOA4-mediated ferritinophagy releases stored iron from ferritin and thereby expands the reactive iron pool. This process is not merely an accessory phenomenon of iron metabolism, but an important upstream amplification layer for ferroptosis sensitization. When NCOA4 is active and ferritin is continuously degraded, cells are more likely to enter an iron-dependent lipid peroxidation state.

2.2 Lipid remodeling layer

(1) ACSL4-dependent substrate loading

ACSL4 is a key enzyme determining whether the cell membrane acquires a ferroptosis-sensitive substrate profile. High ACSL4 expression usually means that more PUFA species are loaded into the membrane system, making cells more prone to accumulation of lipid peroxidation products under the same oxidative pressure.

(2) LPCAT3-mediated membrane phospholipid remodeling

LPCAT3 integrates activated polyunsaturated fatty acids into the phospholipid backbone of membranes, thereby further stabilizing lipid susceptibility. Ferroptosis is therefore not determined by iron alone, but jointly by iron availability and lipid substrate loading.

2.3 Antioxidant defense layer

(1) The SLC7A11-GSH-GPX4 main axis

High SLC7A11 expression enhances cystine uptake, promotes GSH synthesis, and maintains GPX4 activity, thereby markedly increasing tumor-cell tolerance to ferroptosis. Conversely, when this pathway is inhibited, membrane lipid peroxides are more likely to accumulate uncontrollably.

(2) Parallel systems of FSP1 and BH4

Even when GPX4 is inhibited, some cells can still maintain membrane lipid antioxidant capacity through the FSP1-CoQ10 or GCH1-BH4 systems. Therefore, assessment of tumor-cell ferroptosis sensitivity should not stop at GPX4 expression alone, but should also evaluate whether compensatory parallel defenses are present.

Table 1. Key molecular framework of the ferroptotic execution layer

Regulatory layer	Representative nodes	Major function	Interpretive significance
Iron supply layer	TFR1, FTH1, FPN, NCOA4	Determines the size of the labile iron pool	Indicates whether oxidative driving force is present
Lipid susceptibility layer	ACSL4, LPCAT3, PUFA-PL	Determines whether membrane lipids enter an oxidation-prone state	Indicates whether a substrate basis is present
Classical defense layer	SLC7A11, SLC3A2, GSH, GPX4	Clears lipid peroxides	Indicates whether the cell can maintain survival
Parallel defense layer	FSP1, CoQ10, GCH1, BH4	Provides alternative antioxidant protection	Indicates whether compensatory tolerance exists

3. Mechanisms by Which the Immune System Shapes the Ferroptosis Threshold

3.1 CD8+ T-cell induction layer

(1) IFN-gamma-mediated metabolic suppression

After activation, CD8+ T cells secrete IFN-gamma, which can downregulate expression of SLC7A11 and SLC3A2 in tumor cells through a JAK/STAT1-related program, thereby weakening cystine uptake and GSH supply and making tumor cells more likely to cross the ferroptosis threshold. In essence, immune effector activity promotes tumor-cell killing by rewriting metabolic defense systems.

(2) Ferroptosis amplification in immunotherapy

In the context of immune checkpoint therapy, sensitization of tumor cells to ferroptosis is often associated with sustained IFN-gamma signaling input. Accordingly, tumor clearance is not simply a matter of increasing the number of effector T cells, but also involves whether tumor cells have already been pushed into a lower ferroptosis-threshold range.

3.2 Nutrient competition and reducing-equivalent allocation layer

(1) Competition for cysteine utilization

SLC7A11 is positioned at the metabolic exchange interface between tumor cells and the microenvironment. It determines not only the antioxidant reserve of tumor cells, but also reshapes glutamate export and amino acid exchange patterns. Thus, SLC7A11 is not only a ferroptosis node, but also a node of metabolic competition in the microenvironment.

(2) Lactate and low-glucose stress

High lactate, low glucose, and lipid abnormalities rewrite the allocation of NADPH, GSH, and mitochondrial metabolism, thereby altering the buffering capacity of cells under lipid peroxidation stress. Therefore, the ferroptosis threshold is not a fixed constant, but a dynamic variable continuously reshaped by nutritional pressure in the microenvironment.

3.3 Myeloid-cell amplification layer

(1) State dependence of macrophages

The ferroptosis sensitivity of macrophages is closely related to their polarization state, iron-handling mode, and lipid metabolic background. Inflammatory and reparative macrophages differ substantially in iron uptake, iron storage, ROS production, and fatty acid utilization, and therefore also differ in their responses to ferroptosis induction.

(2) Metabolic adaptability of MDSCs

Myeloid-derived suppressor cells usually exhibit high lipid load and strong metabolic adaptability. They may either become targets of ferroptosis induction or, when ferroptosis is insufficient, continue to maintain an immunosuppressive microenvironment. Therefore, the myeloid ecological state is an indispensable branching layer in ferroptosis-immune crosstalk.

4. Stratified Differences in Ferroptosis Across Immune Cell Subsets

4.1 Metabolic vulnerability in CD8+ T cells

(1) GPX4-dependent maintenance of effector function

After activation, CD8+ T cells must maintain high metabolic flux and ROS-buffering capacity, and therefore depend strongly on GPX4 and GSH. Once this pathway is impaired, T cells may first show a decline in effector output and then enter a state of sustained lipid injury.

(2) Lipid-load accumulation under exhaustion conditions

Under chronic antigen stimulation and within the tumor microenvironment, T cells are exposed to high lactate, low glucose, and high lipid conditions, causing persistent elevation of membrane lipid peroxidation pressure. In this context, ferroptosis-related pathways function more like a threshold for maintenance of function rather than merely a terminal death pathway.

4.2 Functional vulnerability in NK cells and dendritic cells

(1) Stability of NK-cell cytotoxicity

NK cells depend on rapid energy supply and membrane structural integrity to accomplish degranulation and sustained killing. Therefore, accumulation of lipid peroxidation can directly impair their cytotoxic output. Their ferroptosis sensitivity is closely related to lipid composition, reducing-equivalent support, and microenvironmental pressure.

(2) Antigen-presenting capacity of dendritic cells

Dendritic cells depend strongly on membrane-system homeostasis. When lipid peroxidation worsens, overt cell death may not necessarily appear first; instead, a more common outcome is decline in antigen uptake, processing, and presentation efficiency. Thus, ferroptosis-related damage in dendritic cells more often manifests as functional impairment.

4.3 Ecological consequences in macrophages and MDSCs

(1) Reprogramming of iron handling in macrophages

The iron homeostasis and lipid metabolic patterns of macrophages determine whether they shift toward inflammatory amplification or reparative deviation. The effects of ferroptosis on macrophages should not be judged only from survival rate, but rather from whether inflammatory output and iron-handling modes are reprogrammed.

(2) Amplification of immunosuppression by MDSCs

MDSCs exhibit strong adaptability in high-lipid and high-stress environments. If ferroptosis induction is insufficient, their immunosuppressive function can be maintained continuously; if induction is sufficient, their abundance and function in the tumor microenvironment may be altered. Thus, MDSCs are an important indicator layer for determining whether ferroptosis has truly reshaped immune ecology.

Table 2. Stratified differences in ferroptosis across immune cell subsets

Cell type	Key metabolic characteristics	Ferroptosis-related vulnerability	Major functional consequence
CD8+ T cells	High activation, high ROS, high GSH demand	GPX4 decline, accumulation of lipid peroxidation	Reduced cytotoxic function, aggravated exhaustion
NK cells	Rapid energy consumption, high dependence on membrane structure	Loss of control over lipid peroxidation	Weakened cytotoxicity
Dendritic cells	Dependence on membrane remodeling and antigen processing	Damage to membrane lipid homeostasis	Reduced antigen presentation and costimulatory output
Macrophages	Strong dependence on iron handling and lipid metabolic state	Reconstructed iron load and ROS profile	Inflammatory amplification or reparative imbalance
MDSCs	High lipid load, metabolic advantage in immunosuppression	Insufficient ferroptosis induction or abnormal adaptation	Persistent immunosuppression

5. Scientific Questions and Experimental Readouts

5.1 Scientific questions

(1) Stratification of responding cell populations

In research on ferroptosis-immunometabolism crosstalk, the first priority is to define the major responding populations in the current model. Tumor cells, CD8+ T cells, NK cells, dendritic cells, and myeloid cells do not respond in the same direction under the same treatment conditions. Therefore, a single cell-death outcome cannot substitute for judgment in a multicellular system.

(2) Threshold-shift layer

Ferroptosis is not simply present or absent, but instead is determined by the combined threshold set by the labile iron pool, membrane lipid substrates, and antioxidant defenses. Under different microenvironmental conditions, this threshold can shift continuously. Therefore, the more informative scientific question is how the threshold is reset, rather than whether terminal cell death increases.

(3) Microenvironmental feedback layer

Lipid peroxidation products, lactate, iron redistribution, and changes in inflammatory mediators can all in turn reshape the states of effector immune cells and myeloid cells. Therefore, ferroptosis studies that ignore microenvironmental feedback can explain only local pro-death effects, but not the overall immune outcome.

5.2 Experimental readouts

(1) Tumor-cell layer readouts

More informative tumor-cell readouts include changes in the labile iron pool, expression of ACSL4/LPCAT3, status of SLC7A11/GPX4/FSP1, accumulation of lipid ROS, and generation of membrane lipid oxidation products. Compared with simple decline in cell viability, these indicators are more capable of defining whether ferroptosis is genuinely occurring.

(2) Immune-cell layer readouts

At the level of effector T cells and NK cells, GPX4 status, lipid peroxidation levels, mitochondrial ROS, cytotoxic-molecule output, and maintenance of effector function should be assessed simultaneously. For dendritic cells, attention should focus on antigen uptake, processing, and presentation efficiency. If only numerical changes are observed without functional readouts, the immune-layer information is usually insufficient.

(3) Myeloid ecological readouts

At the myeloid level, macrophage polarization state, iron-handling mode, inflammatory mediator release, and the abundance and metabolic characteristics of MDSCs should be evaluated. This layer helps determine whether ferroptosis induction has truly altered the suppressive state of the microenvironment.

(4) System-level readouts

A more complete study design should integrate tumor-cell ferroptosis indicators, effector lymphocyte functional indicators, dendritic-cell antigen-presentation indicators, and myeloid suppressive-state indicators. Only when multiple layers of readouts support the same conclusion does a ferroptosis-immunometabolism crosstalk model gain strong interpretive value.

6. Related Research Products

Table 3. Product table related to ferroptosis and immunometabolic crosstalk

Name	CAS No.	Experimental stage	Key use	Use notes
Erastin	571203-78-6	system xc− inhibition layer	Classical ferroptosis inducer used to inhibit SLC7A11-mediated cystine uptake	Suitable for screening tumor-cell ferroptosis sensitivity
Sulfasalazine	599-79-1	SLC7A11 inhibition layer	Inhibits cystine uptake and lowers GSH synthesis	Suitable for immune-tumor coculture models
Sorafenib	284461-73-0	system xc−/kinase intervention layer	Can induce ferroptosis in specific contexts while also exerting kinase-inhibitory activity	Suitable for combination studies in tumor therapy
RSL3	1219810-16-8	GPX4 inhibition layer	Directly inhibits GPX4 activity and rapidly induces lipid peroxidation	Suitable for validation of GPX4 dependence
FINO2	1448428-04-3	Lipid-peroxidation amplification layer	Induces ferroptosis by promoting oxidation and iron-dependent reactions	Suitable for oxidation-amplified models
Ferrostatin-1	347174-05-4	Ferroptosis inhibition layer	Classical lipid-radical-trapping agent used to rescue ferroptosis phenotypes	Suitable as a standard negative control
Liproxstatin-1	950455-15-9	Ferroptosis inhibition layer	Potent ferroptosis inhibitor used to validate lipid-peroxidation dependence	Suitable for in vitro and in vivo protection experiments
Deferoxamine mesylate	138-14-7	Iron-chelation layer	Chelates labile iron and suppresses iron-dependent amplification of lipid oxidation	Suitable for validating iron dependence
Deferiprone	30652-11-0	Iron-chelation layer	Oral iron chelator used to study the contribution of the free iron pool to ferroptosis	Suitable for long-term culture models
Ciclopirox olamine	41621-49-2	Iron-dependent oxidation layer	Has metal-chelating properties and can be used for supplementary validation of iron-dependent oxidation processes	Suitable for comparison with DFO
Ferric ammonium citrate	1185-57-5	Iron-load layer	Used to increase cellular iron input and amplify ferroptosis susceptibility	Suitable for iron-overload models
Hemin	16009-13-5	Heme/iron-load layer	Used to simulate iron release associated with heme breakdown	Suitable for inflammatory and hemorrhagic microenvironment models
Bafilomycin A1	88899-55-2	Autophagy-ferritinophagy layer	Inhibits lysosomal acidification and interferes with NCOA4-mediated ferritinophagy	Suitable for ferritinophagy validation
Chloroquine diphosphate	50-63-5	Autophagy-lysosome layer	Inhibits autophagic flux and is used to analyze amplification of ferroptosis by ferritinophagy	Suitable for NCOA4-related models
Rapamycin	53123-88-9	Autophagy induction layer	Induces autophagy to evaluate ferritin turnover and changes in ferroptosis sensitivity	Suitable for autophagy-ferroptosis interaction studies
Rosiglitazone	122320-73-4	ACSL4 regulation layer	One of the tool molecules associated with ACSL4 inhibition, used to weaken PUFA loading	Suitable for substrate-susceptibility studies
Triacsin C	76896-80-5	ACSL inhibition layer	Inhibits long-chain acyl-CoA synthetases and interferes with lipid remodeling	Suitable for validating dependence on lipid substrates
Arachidonic acid	506-32-1	PUFA substrate layer	Provides ferroptosis-sensitive membrane lipid substrates	Suitable for amplifying lipid-peroxidation models
Adrenic acid	20590-32-3	PUFA substrate layer	Used to study the contribution of specific PUFA-phospholipids to ferroptosis	Suitable for membrane-lipid loading studies
Glutamate	56-86-0	system xc− exchange layer	Used to simulate the effects of glutamate export/exchange conditions on system xc−	Suitable for metabolic-competition models
N-acetyl-L-cysteine	616-91-1	GSH supplementation layer	Provides thiol buffering and relieves oxidative stress	Suitable for reducing-equivalent rescue experiments
Reduced glutathione	70-18-8	Antioxidant-buffering layer	Directly supplements the GSH background to analyze GPX4-axis dependence	More suitable for in vitro systems
Buthionine sulfoximine	83730-53-4	GSH depletion layer	Inhibits GSH synthesis and enhances ferroptosis susceptibility	Suitable for use with RSL3 or Erastin
Idebenone	58186-27-9	CoQ antioxidant layer	Used in studies of compensatory membrane-lipid antioxidant mechanisms	Suitable for analysis of the FSP1/CoQ defense axis
Coenzyme Q10	303-98-0	CoQ defense layer	Used to study the FSP1-CoQ lipid antioxidant axis	Suitable for validation of parallel defense mechanisms
iFSP1	1644443-47-9	FSP1 inhibition layer	Selectively inhibits FSP1 and weakens the extra-GPX4 protective pathway	Suitable for FSP1-dependent models
Z-VAD-FMK	187389-52-2	Apoptosis-exclusion layer	Broad-spectrum caspase inhibitor used to exclude interference from apoptosis in ferroptotic phenotypes	Suitable for distinguishing cell-death modalities
Necrostatin-1	4311-88-0	Necroptosis-exclusion layer	Used to distinguish RIPK1-dependent death from ferroptosis	Suitable for stratified death-mode analysis
MitoTEMPO	1334850-99-5	Mitochondrial ROS layer	Mitochondria-targeted antioxidant used to analyze the role of mitochondrial ROS in ferroptosis	Suitable for immune-cell protection models
4-Hydroxynonenal	75899-68-2	Lipid-peroxidation product layer	Used to simulate the effects of lipid-peroxidation breakdown products on the immune microenvironment	Suitable for microenvironment-feedback studies
JAK Inhibitor I	457081-03-7	IFN-gamma signaling layer	Blocks JAK/STAT signaling to validate pathway dependence of immune-induced ferroptosis	Suitable for IFN-gamma mechanistic validation
Ruxolitinib	1092939-17-7	JAK1/2 layer	Inhibits JAK-STAT signaling to analyze coupling between CD8+ T-cell-induced effects and ferroptosis	Suitable for coculture models
Etomoxir	124083-20-1	Fatty-acid-oxidation layer	Inhibits CPT1 to analyze the relationship between lipid metabolism and ferroptosis sensitivity	Suitable for immune-cell metabolism studies
2-Deoxy-D-glucose	154-17-6	Glycolysis intervention layer	Used to rewrite reducing-equivalent allocation and immunometabolic state	Suitable for tumor-T-cell competition models
Sodium lactate	867-56-1	Lactate microenvironment layer	Used to create lactate-accumulation conditions and analyze the effects of microenvironmental stress on the ferroptosis threshold	Suitable for tumor-microenvironment models

The key to ferroptosis-immunometabolism crosstalk does not lie in viewing ferroptosis as an isolated cell-death modality, but in understanding how it is embedded within a shared network of iron homeostasis, membrane-lipid remodeling, reducing-equivalent allocation, and immune-effector programs. For tumors, inflammation, and immunotherapy, the more technically meaningful question is how different cell populations cross their respective ferroptosis thresholds within the same microenvironment.

For more related articles, please see below:

[1] The Drug Target Potential of the GPX Family in Lipid Peroxidation Defense, Ferroptosis Regulation, and Organ Injury Protection