Impaired antioxidant capacity causes a disruption of metabolic homeostasis in sickle erythrocytes

Disrupted homeostasis in sickle cells: Expanding the comprehension of metabolism adaptation and related therapeutic strategies

Sickle cell disease (SCD) is a hereditary hemolytic anemia associated with the alteration of the membrane composition of the sickle erythrocytes, the loss of glycolysis, dysregulation of the pyruvate phosphatase pathway, and changes in nucleotide metabolism of the sickle red blood cell (RBC). This review provides a comprehensive overview of the impact of the presence of Hb S, which leads to the disruption of the normal RBC metabolism. The intricate interplay between the redox and energetic balance in erythrocytic cells, where the glycolysis, pentose phosphate pathway, and methemoglobin reductase pathways are all altered in sickle RBC, is a key focus. Moreover, this review summarizes the current knowledge about the disease-modifying agents and their action mechanisms based on the sickle RBC alterations previously mentioned (i.e., their association with beneficial effects on the sickle cells' membrane, to their RBCs' energy metabolism, and to their oxidative status). Therefore, providing a comprehensive understanding of how sickle cells cope with the disruption of metabolic homeostasis and the most promising therapeutic agents able to ameliorate the various consequences of abnormal sickle RBC alterations.

Unraveling the multifaceted roles of peroxiredoxins in sickle cell anemia: implications in redox and inflammation adaptations

Sickle cell anemia (SCA) presents a complex interplay of factors, with the production of high levels of reactive oxygen species (ROS) and the chronic inflammatory process leading to chronic oxidative stress. In this context, efficient action of antioxidant systems becomes crucial, with particular emphasis on peroxiredoxins (PRDXs) due to their abundance and vital roles. Our primary objective was to establish associations between gene and protein expression of PRDXs 1, 2, and 6, as well as their reducers TRX1, TRXR1, and SRX1, with the characteristic hyperoxidative status observed in SCA patients. Concomitantly, we assessed the production of other essential antioxidant enzymes (SOD1, CAT, and GPX1) in reticulocytes and erythrocytes and explored mRNA levels of the NRF2/KEAP1/PKCδ complex. Our comprehensive analysis revealed a ∼ 3-fold elevation in ROS levels in erythrocytes of patients compared to healthy individuals. However, the NRF2/KEAP1/PKCδ complex exhibited a significant reduction in gene expression, hinting that another transcription factor may regulate the antioxidant response among SCA patients. In addition, the pattern of increased transcript levels of antioxidants in SCA patients was not associated with their protein levels, indicating a possible degradation by proteasome. The protein content of PRDX2 showed a significant reduction, indicating an increased vulnerability of these cells to oxidative damage. Intriguingly, both PRDXs 1 and 2 exhibited significant increases in the plasma of SCA patients, indicating that, besides their well-known intracellular antioxidant role, these enzymes may also play a vital extracellular role in modulating inflammation in these individuals. Our findings unveil novel insights into the redox metabolism adaption of erythroid cells in response to the presence of HbS in homozygosity, thus, into the complex SCA pathophysiology. Moreover, our study reveals the simultaneous presence of both PRDXs 1 and 2 in the plasma of these patients, thereby offering valuable implications for potential prognostic and therapeutic avenues.

The roles and functions of ergothioneine in metabolic diseases

The global prevalence of metabolic diseases is on the increase, and it has become a significant threat to the health and lives of individuals. Ergothioneine (EGT) is a natural betaine amino acid found in various foods, particularly mushrooms. EGT cannot be synthesized by mammals; it is absorbed into small intestinal epithelial cells by a cationic protein, the novel organic cation transporter 1 (OCTN1), and transported to certain organs including liver, spleen, kidney, lung, heart, eyes and brain. EGT has been reported to exhibit antioxidant, anti-inflammatory, anti-apoptotic, anti-aging, and metal-chelating effects. The unique chemical properties and biological functions of EGT position it as a promising candidate for the research and treatment of metabolic diseases. This review summarizes EGT's capacities, potential therapeutic effects on multiple metabolic diseases, and their specific mechanisms. Finally, we outline challenges for future research on EGT and aspire to establish it as a prospective therapeutic agent for metabolic diseases.

Purine metabolism in bone marrow microenvironment inhibits hematopoietic stem cell differentiation under microgravity

BACKGROUND

Spaceflight and microgravity environments have been shown to cause significant health impairments, including bone loss, immune dysfunction, and hematopoietic disorders. Hematopoietic stem cells (HSCs), as progenitors of the hematopoietic system, are critical for the continuous renewal and regulation of immune cells. Therefore, elucidating the regulatory mechanisms governing HSC fate and differentiation in microgravity environments is of paramount importance.

METHODS

In this study, hindlimb unloading (HU) was employed in mice to simulate microgravity conditions. After 28 days of HU, cells were isolated for analysis. Flow cytometry and colony-forming assays were utilized to assess changes in HSC proliferation and differentiation. Additionally, transcriptomic and untargeted metabolomic sequencing were performed to elucidate alterations in the metabolic pathways of the bone marrow microenvironment and their molecular regulatory effects on HSCs fate.

RESULTS

Our findings revealed that 28 days of HU impaired hematopoietic function, leading to multi-organ damage and hematological disorders. The simulated microgravity environment significantly increased the HSCs population in the bone marrow, particularly within the long-term and short-term subtypes, while severely compromising the differentiation capacity of hematopoietic stem/progenitor cells. Transcriptomic analysis of HSCs, combined with metabolomic profiling of bone marrow supernatants, identified 1,631 differentially expressed genes and 58 metabolites with altered abundance. Gene set enrichment analysis indicated that HU suppressed key pathways, including hematopoietic cell lineage and MAPK signaling. Furthermore, integrated analyses revealed that metabolites affected by HU, particularly hypoxanthine enriched in the purine metabolism pathway, were closely associated with hematopoietic cell lineage and MAPK signaling pathways. Molecular docking simulations and in vitro experiments confirmed that hypoxanthine interacts directly with core molecules within these pathways, influencing their expression.

CONCLUSIONS

These findings demonstrate that hypoxanthine in the bone marrow supernatant acts as a signaling mediator under microgravity, influencing HSCs fate by modulating hematopoietic cell lineage and MAPK signaling pathways. This study offers novel insights into the impact of microgravity on HSC fate and gene expression, underscoring the pivotal role of bone marrow microenvironmental metabolic changes in regulating key signaling pathways that determine hematopoietic destiny.

Targeting sickle cell pathobiology and pain with novel transdermal curcumin

Several comorbidities of sickle cell disease (SCD) originate from red blood cell (RBC) instability, chronic inflammation, and oxidative stress. Development of scalable, cost-effective therapeutics suitable for chronic administration to prevent, attenuate, and perhaps reverse the consequences of RBC instability is needed. Curcumin has many of these attributes as a safe compound with antisickling, antiinflammatory, and antioxidant properties, but its translational potential has been constrained due to limited bioavailability from oral administration. The present study demonstrates the rapid and high bioavailability of a novel topical/transdermal (TD) curcumin gel formulation in the plasma and blood cells and its effectiveness in humanized sickle cell mice in: (i) ameliorating features of sickle cell pain hypersensitivity and axonal injury; (ii) reducing multiple manifestations of RBC instability including evidence of decreased hemolysis (reduced lactate dehydrogenase levels), enhanced RBC ATP levels along with decreased oxidative damage; (iii) decreasing multiple proinflammatory cytokines including interleukin-6, monocyte chemoattractant protein-1, granulocyte-macrophage colony-stimulating factor, and activation, normal T cell expressed and secreted protein in skin secretome; and (iv) reducing mast cell degranulation and activation. Our data suggest that an easy-to-use novel TD curcumin gel formulation has the potential to ameliorate chronic pain, improve RBC stability, and reduce inflammatory consequences of SCD.

The Association Between Serum Ergothioneine Concentration and Japanese Dietary Habits: The Third Survey of the ROAD Study

Background/Objectives: As a result of aging societies, the increasing number of older adults requiring nursing care has become a serious issue and the extension of healthy life expectancy has become an urgent priority. Ergothioneine (EGT) is a sulfur-containing amino acid found in foods such as mushrooms. Low EGT blood concentrations have been reported to be associated with the risk of onset and progression of various diseases. However, the distribution of EGT blood concentrations and their association with dietary habits in the Japanese general population remains unclear. Methods: This cross-sectional study was conducted using data from the third survey of the Research on Osteoarthritis/osteoporosis Against Disability (ROAD) study, which analyzed 1457 participants (474 men and 983 women) aged ≥ 40 years. Serum EGT concentrations and their association with dietary habits were analyzed. Results: Serum EGT concentrations (1) peaked in the 70s in men and the 60s in women, (2) were higher in women than in men, and (3) showed a significant positive correlation with fish intake and nutrients commonly found in fish. Conclusions: In the present study, we report for the first time an age- and sex-specific serum EGT distribution in a Japanese population and its association with dietary habits, particularly fish intake. These findings help define normal and abnormal EGT levels and suggest new potential sources of EGT.

Metabolic stimulation improves bioenergetics and haematologic indices of circulating erythrocytes from sickle cell mice

Circulating mature red blood cells (RBCs) from patients and mice with sickle cell disease (SCD) abnormally retain mitochondria, a factor shown to contribute to the disease's pathobiology. To further understand the functional implications of RBC mitochondria retention in SCD, we used mitochondria inhibitors and metabolites/substrates from the tricarboxylic acid cycle, oxidative phosphorylation and glycolysis pathways (ADP, glutamate, malate, pyruvate, succinate or all metabolites combined) and examined RBC bioenergetics, reactive oxygen species (ROS) levels, calcium flux and hydration. In RBCs from sickle mice, mitochondria inhibition reduced ATP levels by 30%-60%, whereas control RBCs were unaffected. Conversely, in vitro treatment with metabolites/substrates known to stimulate mitochondria function increased RBC ATP levels and reduced RBC ROS, and these effects were notably more pronounced in sickle RBCs compared to those in control mice. In sickle RBCs, the increases in ATP and decreases in ROS were associated with greater decreases in RBC baseline calcium concentration and improvements in calcium flux. These changes also led to greater increases in RBC volume and hydration, and greater decreases in mean corpuscular haemoglobin concentration in sickle RBCs compared to control RBCs. These results propose a novel model of RBC metabolism in SCD, where retained mitochondria in circulating RBCs are functional and can significantly impact RBC bioenergetics, ATP production and RBC hydration and redox status. These in vitro findings could inform the development of in vivo strategies aimed at increasing RBC ATP, reducing RBC ROS, improving RBC hydration, which could decrease sickling and prove beneficial in SCD. KEY POINTS: Red blood cells (RBCs) from humans and mice with sickle cell disease (SCD) abnormally retain mitochondria. Mitochondria inhibitors lower ATP in circulating RBCs from sickle mice indicating that retained mitochondria contribute to ATP levels in sickle RBC. Metabolic stimulation of mitochondria function improves RBC bioenergetics, redox state and calcium flux, and increases RBC hydration. These data propose a new model of RBC metabolism in SCD, where in addition to glycolysis, retained mitochondria contribute to RBC ATP production. The effects of metabolic stimulation of RBCs resulting in improved RBC bioenergetics and hydration may prove beneficial in SCD.

The Role of Ergothioneine in Red Blood Cell Biology: A Review and Perspective

Oxidative stress can damage tissues and cells, and their resilience or susceptibility depends on the robustness of their antioxidant mechanisms. The latter include small molecules, proteins, and enzymes, which are linked together in metabolic pathways. Red blood cells are particularly susceptible to oxidative stress due to their large number of hemoglobin molecules, which can undergo auto-oxidation. This yields reactive oxygen species that participate in Fenton chemistry, ultimately damaging their membranes and cytosolic constituents. Fortunately, red blood cells contain robust antioxidant systems to enable them to circulate and perform their physiological functions, particularly delivering oxygen and removing carbon dioxide. Nonetheless, if red blood cells have insufficient antioxidant reserves (e.g., due to genetics, diet, disease, or toxin exposure), this can induce hemolysis in vivo or enhance susceptibility to a "storage lesion" in vitro, when blood donations are refrigerator-stored for transfusion purposes. Ergothioneine, a small molecule not synthesized by mammals, is obtained only through the diet. It is absorbed from the gut and enters cells using a highly specific transporter (i.e., SLC22A4). Certain cells and tissues, particularly red blood cells, contain high ergothioneine levels. Although no deficiency-related disease has been identified, evidence suggests ergothioneine may be a beneficial "nutraceutical." Given the requirements of red blood cells to resist oxidative stress and their high ergothioneine content, this review discusses ergothioneine's potential importance in protecting these cells and identifies knowledge gaps regarding its relevance in enhancing red blood cell circulatory, storage, and transfusion quality.

Nitrite decreases sickle hemoglobin polymerization in vitro independently of methemoglobin formation

The root cause of sickle cell disease (SCD) is the polymerization of sickle hemoglobin (HbS) leading to sickling of red blood cells (RBC). Earlier studies showed that in patients with SCD, high-dose nitrite inhibited sickling, an effect originally attributed to HbS oxidation to methemoglobin-S even though the anti-sickling effect did not correlate with methemoglobin-S levels. Here, we examined the effects of nitrite on HbS polymerization and on methemoglobin formation in a SCD mouse model. In vitro, at concentrations higher than physiologic (>1 μM), nitrite increased the delay time for polymerization of deoxygenated HbS independently of methemoglobin-S formation, which only occurred at much higher concentrations (>300 μM). In vitro, higher nitrite concentrations oxidized 100% of normal hemoglobin A (HbA), but only 70% of HbS. Dimethyl adipimidate, an anti-polymerization agent, increased the fraction of HbS oxidized by nitrite to 82%, suggesting that polymerized HbS partially contributed to the oxidation-resistant fraction of HbS. At low concentrations (10 μM-1 mM), nitrite did not increase the formation of reactive oxygen species but at high concentrations (10 mM) it decreased sickle RBC viability. In SCD mice, 4-week administration of nitrite yielded no significant changes in methemoglobin or nitrite levels in plasma and RBC, however, it further increased leukocytosis. Overall, these data suggest that nitrite at supra-physiologic concentrations has anti-polymerization properties in vitro and that leukocytosis is a potential nitrite toxicity in vivo. Therefore, to determine whether the anti-polymerization effect of nitrite observed in vitro underlies the decreases in sickling observed in patients with SCD, administration of higher nitrite doses is required.

Green Coffee Bean Extract Potentially Ameliorates Liver Injury due to HFD/STZ-Induced Diabetes in Rats

The goal of the current study was to examine the therapeutic potential of green coffee bean extract (GCBE) in the treatment of diabetic hepatic damage induced by high-fat diet (HFD) and streptozotocin (STZ) administration. The novelty of this study lies in constructing a newly stabilized in vivo obese diabetic animal model in rats using HFD/STZ for investigating the dose-dependent effect of two commonly used doses of GCBE in hepatoprotection against oxidative stress-induced hepatic damage by measuring many parameters that have not been carried out previously in other studies. GCBE that was used in this study was a hot water extract of green coffee beans with a concentration of 0.1 g ml−1. Male albino rats were given a single dose of STZ (35 mg kg−1), and HFD to induce diabetes mellitus (DM). For 28 days, two separate doses of GCBE 50 mg kg−1 and 100 mg kg−1 were administered orally to diabetic animals. Leptin, liver enzymes, oxidative stress parameters, inflammatory parameters, fasting plasma glucose (FPG), fasting plasma insulin (FPI), and lipid profile levels were examined. Real-time PCR and ELISA were used to quantitatively detect the mRNAs of the genes involved in the insulin signaling pathway, the genes involved in glucose metabolism, and the amounts of proteins. The levels of FPG, lipid profile, liver enzymes, inflammatory markers, and leptin in the HFD/STZ diabetic group revealed a considerable spike, while they considerably decreased after GCBE treatment in a dose-dependent manner. After GCBE treatment, the diabetic group showed a significant rise in the antioxidant markers glutathione, superoxide dismutase, and catalase, as well as a decrease in malondialdehyde and nitric oxide levels. The liver changes caused by HFD/STZ were entirely reversed by GCBE, and most intriguingly, in a dose-dependent manner. We concluded that GCBE can repair the hepatic oxidative damage caused by HFD and STZ by reversing all the previously measured parameters and improving the insulin signaling pathways. GCBE demonstrated strong antifree radical activity and significantly protected cells from oxidative damage caused by HFD/STZ.

Potential Cytoprotective and Regulatory Effects of Ergothioneine on Gene Expression of Proteins Involved in Erythroid Adaptation Mechanisms and Redox Pathways in K562 Cells

This study aimed to establish the importance of ergothioneine (ERT) in the erythroid adaptation mechanisms by appraising the expression levels of redox-related genes associated with the PI3K/AKT/FoxO3 and Nrf2-ARE pathways using K562 cells induced to erythroid differentiation and H₂O₂-oxidative stress. Cell viability and gene expression were evaluated. Two concentrations of ERT were assessed, 1 nM (C1) and 100 µM (C2), with and without stress induction (100 µM H₂O₂). Assessments were made in three periods of the cellular differentiation process (D0, D2, and D4). The C1 treatment promoted the induction of FOXO3 (D0 and 2), PSMB5, and 6 expressions (D4); C1 + H₂O₂ treatment showed the highest levels of NRF2 transcripts, KEAP1 (D0), YWHAQ (D2 and 4), PSMB5 (D2) and PSMB6 (D4); and C2 + H₂O₂ (D2) an increase in FOXO3 and MST1 expression, with a decrease of YWHAQ and NRF2 was observed. in C2 + H₂O₂ (D2) an increase in FOXO3 and MST1, with a decrease in YWHAQ and NRF2 was observed All ERT treatments increased gamma-globin expression. Statistical multivariate analyzes highlighted that the Nrf2-ARE pathway presented a greater contribution in the production of PRDX1, SOD1, CAT, and PSBM5 mRNAs, whereas the PI3K/AKT/FoxO3 pathway was associated with the PRDX2 and TRX transcripts. In conclusion, ERT presented a cytoprotective action through Nrf2 and FoxO3, with the latter seeming to contribute to erythroid proliferation/differentiation.

Ergothioneine Production by Submerged Fermentation of a Medicinal Mushroom Panus conchatus

Ergothioneine is a natural and safe antioxidant that plays an important role in anti-aging and the prevention of various diseases. This study aimed to report on a kind of medicinal mushroom of Panus conchatus with great potential for the bioproduction of ergothioneine. The effect of different nutritional and environmental conditions on the growth of Panus conchatus and ergothioneine production were investigated. Molasses and soy peptone were found to promote cell growth of Panus conchatus and enhance ergothioneine accumulation. Adding precursors of histidine, methionine and cysteine could increase ergothioneine production and the highest ergothioneine concentration of 148.79 mg/L was obtained. Finally, the extraction and purification processes were also established to obtain the crude ergothioneine extract for further antioxidant property evaluation. The ergothioneine from Panus conchatus showed high antioxidant activity with good stability in a lower pH environment. This study provided a new strain and process for the bioproduction of ergothioneine.

Ergothioneine: A Stress Vitamin with Antiaging, Vascular, and Neuroprotective Roles?

Significance: Ergothioneine (ET) is an unusual sulfur-containing amino acid derived from histidine, acquired predominantly from food. Its depletion is associated with deleterious consequences in response to stress stimuli in cell culture models, prompting us to classify it as a vitamin in 2010, which was later supported by in vivo studies. ET is obtained from a variety of foods and is taken up by a selective transporter. ET possesses antioxidant and anti-inflammatory properties that confer cytoprotection. ET crosses the blood-brain barrier and has been reported to have beneficial effects in the brain. In this study, we discuss the cytoprotective and neuroprotective properties of ET, which may be harnessed for combating neurodegeneration and decline during aging. Recent Advances: The designation of ET as a stress vitamin is gaining momentum, opening a new field of investigation involving small molecules that are essential for optimal physiological functioning and maintenance of health span. Critical Issues: Although ET was discovered more than a century ago, its physiological functions are still being elucidated, especially in the brain. As ET is present in most foods, toxicity associated with its deprivation has been difficult to assess. Future Directions: Using genetically engineered cells and mice, it may now be possible to elucidate roles of ET. This coupled with advances in genomics and metabolomics may lead to identification of ET function. As ET is a stable antioxidant with anti-inflammatory properties, whose levels decline during aging, supplementing ET in the diet or consuming an ET-rich diet may prove beneficial. Antioxid. Redox Signal. 36, 1306-1317.

Sickle Cell Disease: Role of Oxidative Stress and Antioxidant Therapy

Sickle cell disease (SCD) is the most common hereditary disorder of hemoglobin (Hb), which affects approximately a million people worldwide. It is characterized by a single nucleotide substitution in the β-globin gene, leading to the production of abnormal sickle hemoglobin (HbS) with multi-system consequences. HbS polymerization is the primary event in SCD. Repeated polymerization and depolymerization of Hb causes oxidative stress that plays a key role in the pathophysiology of hemolysis, vessel occlusion and the following organ damage in sickle cell patients. For this reason, reactive oxidizing species and the (end)-products of their oxidative reactions have been proposed as markers of both tissue pro-oxidant status and disease severity. Although more studies are needed to clarify their role, antioxidant agents have been shown to be effective in reducing pathological consequences of the disease by preventing oxidative damage in SCD, i.e., by decreasing the oxidant formation or repairing the induced damage. An improved understanding of oxidative stress will lead to targeted antioxidant therapies that should prevent or delay the development of organ complications in this patient population.

Eccentric Cycling Training Improves Erythrocyte Antioxidant and Oxygen Releasing Capacity Associated with Enhanced Anaerobic Glycolysis and Intracellular Acidosis

The antioxidant capacity of erythrocytes protects individuals against the harmful effects of oxidative stress. Despite improved hemodynamic efficiency, the effect of eccentric cycling training (ECT) on erythrocyte antioxidative capacity remains unclear. This study investigates how ECT affects erythrocyte antioxidative capacity and metabolism in sedentary males. Thirty-six sedentary healthy males were randomly assigned to either concentric cycling training (CCT, n = 12) or ECT (n = 12) at 60% of the maximal workload for 30 min/day, 5 days/week for 6 weeks or to a control group (n = 12) that did not receive an exercise intervention. A graded exercise test (GXT) was performed before and after the intervention. Erythrocyte metabolic characteristics and O₂ release capacity were determined by UPLC-MS and high-resolution respirometry, respectively. An acute GXT depleted Glutathione (GSH), accumulated Glutathione disulfide (GSSG), and elevated the GSSG/GSH ratio, whereas both CCT and ECT attenuated the extent of the elevated GSSG/GSH ratio caused by a GXT. Moreover, the two exercise regimens upregulated glycolysis and increased glucose consumption and lactate production, leading to intracellular acidosis and facilitation of O₂ release from erythrocytes. Both CCT and ECT enhance antioxidative capacity against severe exercise-evoked circulatory oxidative stress. Moreover, the two exercise regimens activate erythrocyte glycolysis, resulting in lowered intracellular pH and enhanced O₂ released from erythrocytes.

The current status of biotechnological production and the application of a novel antioxidant ergothioneine

Ergothioneine is a sulfur-containing histidine derivative, that possessesexcellent antioxidant activity and has been used in the food and cosmetics industries. It plays a significant role in anti-aging and the prevention of various diseases. This review will briefly introduce the functions and applications of ergothioneine, elaborate the biosynthetic pathways of ergothioneine and describe several strategies to increase the production of ergothioneine. Then the efficient extraction and detection methods of ergothioneine will be presented. Finally, several proposals are put forward to increase the yield of ergothioneine, and the development prospects of ergothioneine will be discussed.

The biology of ergothioneine, an antioxidant nutraceutical

Ergothioneine (ERG) is an unusual thio-histidine betaine amino acid that has potent antioxidant activities. It is synthesised by a variety of microbes, especially fungi (including in mushroom fruiting bodies) and actinobacteria, but is not synthesised by plants and animals who acquire it via the soil and their diet, respectively. Animals have evolved a highly selective transporter for it, known as solute carrier family 22, member 4 (SLC22A4) in humans, signifying its importance, and ERG may even have the status of a vitamin. ERG accumulates differentially in various tissues, according to their expression of SLC22A4, favouring those such as erythrocytes that may be subject to oxidative stress. Mushroom or ERG consumption seems to provide significant prevention against oxidative stress in a large variety of systems. ERG seems to have strong cytoprotective status, and its concentration is lowered in a number of chronic inflammatory diseases. It has been passed as safe by regulatory agencies, and may have value as a nutraceutical and antioxidant more generally.

Metabolome Changes during In Vivo Red Cell Aging Reveal Disruption of Key Metabolic Pathways

Understanding the mechanisms for cellular aging is a fundamental question in biology. Normal red blood cells (RBCs) survive for approximately 100 days, and their survival is likely limited by functional decline secondary to cumulative damage to cell constituents, which may be reflected in altered metabolic capabilities. To investigate metabolic changes during in vivo RBC aging, labeled cell populations were purified at intervals and assessed for abundance of metabolic intermediates using mass spectrometry. A total of 167 metabolites were profiled and quantified from cell populations of defined ages. Older RBCs maintained ATP and redox charge states at the cost of altered activity of enzymatic pathways. Time-dependent changes were identified in metabolites related to maintenance of the redox state and membrane structure. These findings illuminate the differential metabolic pathway usage associated with normal cellular aging and identify potential biomarkers to determine average RBC age and rates of RBC turnover from a single blood sample.

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Altered glycolytic, amino acid, and fatty acid metabolism occurs in normal RBC aging

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GSH pools are maintained in spite of age-dependent shifts in enzyme synthesis

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Changes in choline and GPC suggest alterations in membrane lipid metabolism

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Ophthalmate, GPC, and ergothioneine are candidate metabolic clocks for RBC aging