Ferroptosis and Ageing Tissues
Key Takeaways
- Ferroptosis is a regulated form of cell death caused by iron-dependent accumulation of damaging phospholipid peroxides. [1] [2]
- Age-related changes in iron handling, membrane lipids, and antioxidant capacity can alter ferroptosis susceptibility, but the direction and magnitude differ among tissues and cell states. [2] [4]
- Studies in aged animals implicate ferroptotic signalling in vascular, liver, kidney, muscle, and neuronal dysfunction; direct evidence in normally ageing human tissues is much more limited. [5] [6] [7] [8] [10]
- Iron accumulation or lipid peroxidation alone does not demonstrate that a cell has died by ferroptosis; converging mechanistic evidence and selective rescue are needed. [1] [2]
Ferroptosis is a form of regulated cell death in which iron-dependent oxidation overwhelms the systems that repair phospholipid hydroperoxides in cell membranes. It was named in 2012 after experiments showed a pattern of death that was mechanistically distinct from apoptosis and could be suppressed by iron chelation or lipid-radical-trapping compounds. [1] [2]
Who This Is Useful For
This page is useful for readers studying oxidative damage, iron metabolism, regulated cell death, or tissue-specific ageing. It also provides a framework for interpreting studies that use changes in ferroptosis-related proteins as evidence about ageing tissues.
What Makes Ferroptosis Distinct
The defining injury is not simply the presence of reactive oxygen species. Ferroptosis depends on the oxidation of susceptible polyunsaturated phospholipids within membranes, access to redox-active iron, and failure of cellular systems that normally prevent or repair lipid-peroxide propagation. The final loss of membrane integrity is therefore the outcome of an imbalance between pro-oxidant chemistry and several parallel defence pathways. [1] [2]
GPX4 is a central defence enzyme that reduces phospholipid hydroperoxides using glutathione. FSP1 provides a partly independent defence at membranes by maintaining reduced coenzyme Q, which can trap lipid radicals. The existence of parallel defences helps explain why the same iron load or oxidative exposure does not produce the same outcome in every cell type. [2] [3]
Core Components of Ferroptosis Susceptibility
| Component | Role | Relevance to Ageing Tissues |
|---|---|---|
| Redox-active iron | Supports reactions that initiate or propagate lipid oxidation [1] [2] | Iron homeostasis can change with age, but accumulation is tissue- and context-dependent [4] |
| Polyunsaturated phospholipids | Provide oxidizable membrane substrates [2] | Lipid composition helps determine which cells are vulnerable even under similar oxidative conditions [2] |
| System xc−, glutathione, and GPX4 | Supply cystine, maintain glutathione, and repair phospholipid hydroperoxides [1] [2] | Reduced capacity at any point can lower the threshold for ferroptotic injury [1] [2] |
| FSP1 and coenzyme Q | Suppress lipid-radical propagation in parallel with GPX4 [3] | Parallel protection means GPX4 abundance alone does not fully specify susceptibility [3] |
| Ferritin and ferritinophagy | Control whether cellular iron is stored or released into more reactive pools [2] | Altered storage, lysosomal handling, or ferritin turnover can either expose or sequester iron [5] [9] |
Why Ageing May Change the Threshold
Ageing can disturb iron balance at systemic and cellular levels. Inflammation, altered iron export, changes in storage, and impaired organelle function can redistribute iron without producing uniform whole-body overload. Because iron is also essential for oxygen transport, mitochondrial respiration, and many enzymes, the relevant issue is its chemical form and location rather than iron being intrinsically harmful. [4]
Tissue vulnerability also depends on membrane composition and the state of antioxidant defences. A cell with abundant oxidizable phospholipids and weakened GPX4-dependent repair may be more vulnerable than a neighbouring cell that stores iron securely or uses an alternative suppressor pathway. This is why ferroptosis is better treated as a context-dependent threshold than as an inevitable consequence of chronological age. [2] [3]
Evidence Across Ageing Tissues
| Tissue or Cell Population | Experimental Finding | Interpretive Limit |
|---|---|---|
| Arterial smooth muscle | Aged mouse arteries and senescent human vascular smooth-muscle cells showed pro-ferroptotic signalling; genetic GPX4 expression and pharmacological inhibition reduced vascular ageing phenotypes in mice. [5] | Human tissue results were associative, while causal manipulations were mainly performed in cell and mouse models. [5] |
| Liver | Old mouse hepatocytes showed greater ferroptotic stress and vulnerability to metabolic challenge; ferrostatin-1 reduced damage and shifted liver gene expression toward a younger pattern. [6] | The strongest effects occurred under diet-induced metabolic stress and do not establish the same contribution in every ageing liver. [6] |
| Kidney | Single-cell analysis of ageing mouse kidneys linked macrophage iron dyshomeostasis and ferroptosis signalling with inflammation and fibrosis; suppressing ferroptosis reduced macrophage-driven fibrotic signalling in vitro. [8] | The work combines mouse tissue, computational inference, and cell experiments rather than demonstrating a general mechanism in healthy human kidneys. [8] |
| Skeletal muscle stem cells | Disrupting transferrin-receptor-1 in satellite cells activated ferroptosis and impaired regeneration, while ferrostatin-1 improved regeneration in aged mice after injury. [7] | The study concerns regenerative response after experimental injury, not uninjured muscle ageing as a whole. [7] |
| Forebrain neurons | Conditional loss of GPX4 in adult mouse forebrain neurons caused lipid peroxidation, neurodegeneration, and cognitive impairment that was partly reduced by a ferroptosis inhibitor. [10] | Engineered GPX4 loss demonstrates neuronal susceptibility but is not a model of the gradual molecular changes of normal human brain ageing. [10] |
Ferroptosis and Cellular Senescence Are Not the Same
Ferroptosis ends in cell death, whereas cellular senescence is a durable state in which a living cell stops dividing and changes its signalling and metabolism. The two processes can influence one another, but a senescent marker does not show that ferroptosis has occurred, and a ferroptotic cell is not by definition senescent. [5] [9]
Their relationship can even run in different directions. Pro-ferroptotic signalling promoted vascular smooth-muscle-cell senescence in one experimental system. In another, chemically induced senescent human skeletal-muscle cells accumulated iron but resisted ferroptosis because much of that iron was retained in lysosomes. These results indicate that cell lineage, senescence trigger, iron location, and lysosomal state can change the outcome. [5] [9]
How Ferroptosis Is Inferred Experimentally
No single commonly measured feature is unique to ferroptosis. Iron accumulation, reduced GPX4, increased ACSL4, reactive oxygen species, malondialdehyde, or 4-hydroxynonenal can support a mechanistic case, but each can also appear in other forms of stress and injury. Stronger studies combine several measurements with genetic perturbation or selective rescue by iron chelators and lipid-radical-trapping inhibitors. [1] [2]
This distinction matters in old tissues, where oxidative damage, inflammation, senescence, and impaired organelle quality control often coexist. A ferroptosis-related molecular signature can reveal altered susceptibility or signalling without proving that extensive ferroptotic cell death is occurring at the time a tissue sample is collected. [2] [6]
Evidence Quality and Open Questions
Confidence is high in the core biochemistry of ferroptosis and in the ability of GPX4, FSP1, iron availability, and membrane-lipid composition to modify susceptibility. These conclusions are supported by converging chemical, genetic, and biochemical experiments across multiple model systems. [1] [2] [3]
Confidence is lower about how much ferroptosis contributes to normal human tissue ageing. Much of the causal evidence comes from engineered cells, aged rodents, injury paradigms, or models of age-related disease. It remains unresolved whether ferroptosis initiates decline, amplifies other stresses, or is a late consequence in each tissue, and whether cells that approach ferroptosis die or instead adapt into a dysfunctional state. [5] [6] [8] [9]
What This Does Not Mean
- Age-related iron accumulation does not automatically mean that ferroptosis is occurring. [2] [4]
- Oxidative stress and lipid peroxidation are not unique to ferroptosis and need mechanistic context. [1] [2]
- Cellular senescence and ferroptosis are distinct states, and senescent cells may be either sensitized or resistant depending on the model. [5] [9]
- Results from ferroptosis inhibitors in animals do not establish efficacy, safety, or appropriate use in humans. [5] [6] [8]
Summary
Ferroptosis connects iron metabolism, membrane-lipid composition, and antioxidant repair in a defined mechanism of regulated cell death. Ageing can alter each part of this balance, creating tissue-specific vulnerabilities rather than one uniform ferroptotic programme. Experimental studies show that this pathway can contribute to dysfunction in several aged animal tissues, but human evidence and causal ordering remain incomplete. The most defensible interpretation is that ferroptosis is one possible amplifier of tissue decline whose importance depends on cell type, metabolic stress, and the condition of iron-handling and lipid-repair systems. [2] [4] [5] [6]
References
- Dixon, S. J., et al. (2012). "Ferroptosis: an iron-dependent form of nonapoptotic cell death." Cell. https://pmc.ncbi.nlm.nih.gov/articles/PMC3367386/
- Jiang, X., Stockwell, B. R., and Conrad, M. (2021). "Ferroptosis: mechanisms, biology and role in disease." Nature Reviews Molecular Cell Biology. https://pmc.ncbi.nlm.nih.gov/articles/PMC8142022/
- Bersuker, K., et al. (2019). "The CoQ oxidoreductase FSP1 acts parallel to GPX4 to inhibit ferroptosis." Nature. https://pmc.ncbi.nlm.nih.gov/articles/PMC6883167/
- Zeidan, R. S., et al. (2021). "Iron homeostasis and organismal aging." Ageing Research Reviews. https://pmc.ncbi.nlm.nih.gov/articles/PMC8620744/
- Sun, D. Y., et al. (2024). "Pro-ferroptotic signaling promotes arterial aging via vascular smooth muscle cell senescence." Nature Communications. https://pmc.ncbi.nlm.nih.gov/articles/PMC10873425/
- Du, K., et al. (2024). "Aging promotes metabolic dysfunction-associated steatotic liver disease by inducing ferroptotic stress." Nature Aging. https://pmc.ncbi.nlm.nih.gov/articles/PMC12810195/
- Ding, H., et al. (2021). "Transferrin receptor 1 ablation in satellite cells impedes skeletal muscle regeneration through activation of ferroptosis." Journal of Cachexia, Sarcopenia and Muscle. https://pmc.ncbi.nlm.nih.gov/articles/PMC8200440/
- Wu, L., et al. (2024). "Macrophage iron dyshomeostasis promotes aging-related renal fibrosis." Aging Cell. https://pmc.ncbi.nlm.nih.gov/articles/PMC11561705/
- Feng, Y., et al. (2024). "Iron retardation in lysosomes protects senescent cells from ferroptosis." Aging. https://pmc.ncbi.nlm.nih.gov/articles/PMC11131988/
- Hambright, W. S., et al. (2017). "Ablation of ferroptosis regulator glutathione peroxidase 4 in forebrain neurons promotes cognitive impairment and neurodegeneration." Redox Biology. https://pmc.ncbi.nlm.nih.gov/articles/PMC5312549/
This content is provided for educational purposes only and does not constitute medical advice.