L-cysteine influx in erythrocytes as a function of human age

hPMSCs prevent erythrocytes dysfunction caused by graft versus host disease via promoting GSH synthesis

BACKGROUND

Oxidative stress is increased in allogeneic hematopoietic stem cell transplant (allo-HSCT) recipients and leads to the development of graft versus host disease (GVHD). Mesenchymal stromal cells (MSCs) can ameliorate GVHD by regulating the function of T cells. However, whether MSCs can modulate erythrocyte antioxidant metabolism and thus reduce GVHD is not known.

METHODS

Forty female BALB/c mice were randomly assigned to four groups: the control, GVHDhigh, hPMSC, and PBS groups. A hypoxanthine/xanthine oxidase system was used to steadily and gradually produce superoxide in an in vitro experiment. A scanning microscope was used to examine the ultrastructure of erythrocytes. Laser diffraction analyses were used to analyze erythrocyte deformability. Western blotting was used to measure the expression of the erythrocyte membrane skeleton proteins Band 3 and β-Spectrin. Corresponding kits were used to assess the levels of oxidative damage and the activity of antioxidant enzymes.

RESULTS

Morphological and deformability defects were significantly increased in erythrocytes from GVHD patients. Band 3 and β-Spectrin expression was also reduced in GVHD patients and model mice. Furthermore, we observed significantly increased oxidative stress-induce injury and decreased antioxidant capability in erythrocytes from both GVHD patients and model mice. Subsequent research showed that human placenta-derived MSC (hPMSC) therapy decreased the GVHD-induced redox imbalance in erythrocytes. Furthermore, our findings suggested that upregulating glucose metabolism promoted both the de novo synthesis and recycling of GSH, which is the primary mechanism by which hPMSCs mediate the increase in antioxidant capacity in erythrocytes.

CONCLUSION

Together, our findings suggest that hPMSCs can increase antioxidant capacity by increasing erythrocyte GSH production and thus ameliorate GVHD.

Trioxidized cysteine in the aging proteome mimics the structural dynamics and interactome of phosphorylated serine

Aging is the primary risk factor for the development of numerous human chronic diseases. On a molecular level, it significantly impacts the regulation of protein modifications, leading to the accumulation of degenerative protein modifications (DPMs) such as aberrant serine phosphorylation (p-Ser) and trioxidized cysteine (t-Cys) within the proteome. The altered p-Ser is linked to abnormal cell signaling, while the accumulation of t-Cys is associated with chronic diseases induced by oxidative stress. Despite this, the potential cross-effects and functional interplay between these two critical molecular factors of aging remain undisclosed. This study analyzes the aging proteome of wild-type C57BL/6NTac mice over 2 years using advanced proteomics and bioinformatics. Our objective is to provide a comprehensive analysis of how t-Cys affects cell signaling and protein structure in the aging process. The results obtained indicate that t-Cys residues accumulate in the aging proteome, interact with p-Ser interacting enzymes, as validated in vitro, and alter their structures similarly to p-Ser. These findings have significant implications for understanding the interplay of oxidative stress and phosphorylation in the aging process. Additionally, they open new venues for further research on the role(s) of these protein modifications in various human chronic diseases and aging, wherein exacerbated oxidation and aberrant phosphorylation are implicated.

Whey protein concentrate protects against age-dependent alteration in redox biomarkers

Aging is associated with decreased cellular cysteine uptake, which acts as a precursor for glutathione biosynthesis. Whey protein, a liquid aspect of milk, is an effective cysteine delivery system. The study was undertaken to evaluate the potential role of whey protein concentrate (WPC) on the redox biomarkers during aging. Male Wistar rats were divided into following four groups: young control (4 months old); young treated with WPC (300 mg/kg b.w./day orally); old (24 months old) control; old treated with WPC for 28 days. After treatment, changes in body weight, lipid profile and levels of redox biomarkers were determined. A marked decrease in prooxidants such as reactive oxygen species, lipid peroxidation and protein carbonyl and significant (p ≤ 0.05) increase in antioxidants such as reduced glutathione and GST levels were observed after WPC supplementation in old age rats. We also found marked decrease in the level of sialic acid and AGEs after WPC supplementation. In conclusion, WPC provides protection against age-dependent redox imbalance which might be attributed to its antioxidant activity.

Cystathionine gamma-lyase/H2 S signaling facilitates myogenesis under aging and injury condition

Hydrogen sulfide (H₂ S) can be endogenously produced and belongs to the class of signaling molecules known as gasotransmitters. Cystathionine gamma-lyase (CSE)-derived H₂ S is implicated in the regulation of cell differentiation and the aging process, but the involvements of the CSE/H₂ S system in myogenesis upon aging and injury have not been explored. In this study, we demonstrated that CSE acts as a major H₂ S-generating enzyme in skeletal muscles and is significantly down-regulated in aged skeletal muscles in mice. CSE deficiency exacerbated the age-dependent sarcopenia and cardiotoxin-induced injury/regeneration in mouse skeletal muscle, possibly attributed to inefficient myogenesis. In contrast, supplement of NaHS (an H₂ S donor) induced the expressions of myogenic genes and promoted muscle regeneration in mice. In vitro, incubation of myoblast cells (C2C12) with H₂ S promoted myogenesis, as evidenced by the inhibition of cell cycle progression and migration, altered expressions of myogenic markers, elongation of myoblasts, and formation of multinucleated myotubes. Myogenesis was also found to upregulate CSE expression, while blockage of CSE/H₂ S signaling resulted in a suppression of myogenesis. Mechanically, H₂ S significantly induced the heterodimer formation between MEF2c and MRF4 and promoted the binding of MEF2c/MRF4 to myogenin promoter. MEF2c was S-sulfhydrated at both cysteine 361 and 420 in the C-terminal transactivation domain, and blockage of MEF2c S-sulfhydration abolished the stimulatory role of H₂ S on MEF2c/MRF4 heterodimer formation. These findings support an essential role for H₂ S in maintaining myogenesis, presenting it as a potential candidate for the prevention of age-related sarcopenia and treatment of muscle injury.

Hydrogen sulfide in longevity and pathologies: Inconsistency is malodorous

Hydrogen sulfide (H₂S) is one of the biologically active gases (gasotransmitters), which plays an important role in various physiological processes and aging. Its production in the course of methionine and cysteine catabolism and its degradation are finely balanced, and impairment of H₂S homeostasis is associated with various pathologies. Despite the strong geroprotective action of exogenous H₂S in C. elegans, there are controversial effects of hydrogen sulfide and its donors on longevity in other models, as well as on stress resistance, age-related pathologies and aging processes, including regulation of senescence-associated secretory phenotype (SASP) and senescent cell anti-apoptotic pathways (SCAPs). Here we discuss that the translation potential of H₂S as a geroprotective compound is influenced by a multiplicity of its molecular targets, pleiotropic biological effects, and the overlapping ranges of toxic and beneficial doses. We also consider the challenges of the targeted delivery of H₂S at the required dose. Along with this, the complexity of determining the natural levels of H₂S in animal and human organs and their ambiguous correlations with longevity are reviewed.

Downregulated Recycling Process but Not De Novo Synthesis of Glutathione Limits Antioxidant Capacity of Erythrocytes in Hypoxia

Red blood cells (RBCs) are susceptible to sustained free radical damage during circulation, while the changes of antioxidant capacity and regulatory mechanism of RBCs under different oxygen gradients remain unclear. Here, we investigated the changes of oxidative damage and antioxidant capacity of RBCs in different oxygen gradients and identified the underlying mechanisms using an in vitro model of the hypoxanthine/xanthine oxidase (HX/XO) system. In the present study, we reported that the hypoxic RBCs showed much higher oxidative stress injury and lower antioxidant capacity compared with normoxic RBCs. In addition, we found that the disturbance of the recycling process, but not de novo synthesis of glutathione (GSH), accounted for the significantly decreased antioxidant capacity of hypoxic RBCs compared to normoxic RBCs. We further elucidated the underlying molecular mechanism by which oxidative phosphorylation of Band 3 blocked the hexose monophosphate pathway (HMP) and decreased NADPH production aggravating the dysfunction of GSH synthesis in hypoxic RBCs under oxidative conditions.

Erythrocyte Senescence in a Model of Rat Displaying Hutchinson-Gilford Progeria Syndrome

Background

Increased oxidative stress is a major cause of aging and age-related diseases. Erythrocytes serve as good model for aging studies. Dihydrotachysterol is known to induce premature aging feature in rats mimicking Hutchinson-Gilford progeria syndrome.

Aim

In the present study, attempts have been made to explore the differential response of young and senescent erythrocytes separated by density gradient centrifugation from accelerated senescence model of rats mimicking Hutchinson-Gilford progeria syndrome and naturally aged rats.

Methods

The erythrocytes of naturally aged and progeroid rats were separated into distinct, young and old cells on the basis of their differential densities. The parameters of oxidative stress and membrane transport systems were studied.

Discussion and Conclusion

Our study provides evidence that organismal aging negatively affects oxidative stress markers and membrane transport systems in both young and old erythrocytes. This study further substantiates that the changes in progeria model of rats resemble natural aging in terms of erythrocyte senescence.

Effect of Copper on l-Cysteine/l-Cystine Influx in Normal Human Erythrocytes and Erythrocytes of Wilson's Disease

Wilson's disease is a disease of abnormal copper metabolism in which free serum copper level is raised. The objective of the study was to determine, whether in Wilson disease, l-cysteine/l-cystine influx into RBC was decreased or not and the specific amino acid transporter affected by copper in normal human RBC. For l-cysteine/l-cystine influx, ten untreated cases, ten treated cases and ten age and sex matched healthy controls were recruited. To study the effect of copper on l-cysteine/l-cystine influx in RBC, 15 healthy subjects were selected. RBC GSH and l-cysteine/l-cystine influx were estimated by Beautler's and Yildiz's method respectively. In untreated cases, l-cysteine/l-cystine influx and erythrocyte GSH level were decreased showing that elevated level of free copper in serum or media decreased l-cysteine/l-cystine influx in human RBC. Copper treatment inhibited L amino acid transporter in normal RBC specifically.

Vitamin C and E Supplements Enhance the Antioxidant Capacity of Erythrocytes Obtained from Aged Rats

BACKGROUND/AIMS

The main purpose of the present study was to investigate the effects of vitamin C and E supplements on the antioxidant capacity of erythrocytes obtained from young and aged rats.

METHODS

Male Wistar rats aged 3 and 24 months were used. Vitamins C and E were injected at doses of 200 mg/kg (day) intraperitoneally in young and aged groups. The antioxidant capacity, oxidant stress parameters, and deformability of red blood cells collected from different age stages were evaluated. An in vitro oxidation system was constructed to explore the mechanisms of antioxidant capacity change in the vitamin treatment groups.

RESULTS

Treatment with vitamins C and E can effectively restore the antioxidant capacity and deformability of red blood cells (RBCs) in aged rats. Under in vitro oxidative conditions, an age-dependent decline in the influx rate of L-cysteine was observed. This was significantly improved following treatment with vitamins C and E.

CONCLUSION

We present evidence of an improvement in the antioxidant capacity of RBCs by treatment with vitamins C and E in aged rats. These observations also suggest that treatment with vitamins C and E improves glutathione synthesis by enhancing the influx rate of L-cysteine through the modification of membrane proteins and lipids.

Quercetin-modulated erythrocyte membrane sodium-hydrogen exchanger during human aging: correlation with ATPase's

CONTENT

Quercetin uptake by erythrocytes is rapid. The sodium-hydrogen exchanger (NHE) is a secondary active transporter, regulating intracellular pH, Na(+) concentration and cell volume.

OBJECTIVE

The aim of present study was to investigate NHE as a function of human age and effect of quercetin on its activity. The NHE activity was correlated with erythrocytes ATPases.

MATERIALS AND METHODS

We analyzed normal, healthy subjects of both sexes (20-82 years). NHE activity was estimated in terms of amiloride-sensitive H+-efflux from acid-loaded cells.

RESULTS

A significant age-dependent increase in NHE activity was observed during aging in humans. Concentration (10(-3 )M to 10(-8 )M)-dependent in vitro treatment with quercetin causes inhibition of NHE activity. The Na(+)/K(+) -ATPase (r = 0.8882) and Ca(2+)-ATPase (r = 0.9540) activities positively correlated with it.

DISCUSSION AND CONCLUSION

The present data show an additional mechanism where dietary flavonoids may exerts beneficial effect during aging.

The role of oxidative and nitrosative stress in accelerated aging and major depressive disorder

Major depressive disorder (MDD) affects millions of individuals and is highly comorbid with many age associated diseases such as diabetes mellitus, immune-inflammatory dysregulation and cardiovascular diseases. Oxidative/nitrosative stress plays a fundamental role in aging, as well as in the pathogenesis of neurodegenerative/neuropsychiatric disorders including MDD. In this review, we critically review the evidence for an involvement of oxidative/nitrosative stress in acceleration of aging process in MDD. There are evidence of the association between MDD and changes in molecular mechanisms involved in aging. There is a significant association between telomere length, enzymatic antioxidant activities (SOD, CAT, GPx), glutathione (GSH), lipid peroxidation (MDA), nuclear factor κB, inflammatory cytokines with MDD. Major depression also is characterized by significantly lower concentration of antioxidants (zinc, coenzyme Q10, PON1). Since, aging and MDD share a common biological base in their pathophysiology, the potential therapeutic use of antioxidants and anti-aging molecules in MDD could be promising.

Multi-target detection of oxidative stress biomarkers in quercetin and myricetin treated human red blood cells

Quercetin and myricetin help against oxidative stress in human red blood cells during aging, thereby has tremendous scope in medical diagnostics and therapeutics.

Biomarkers of oxidative stress in erythrocytes as a function of human age

Despite more than 300 theories to explain the aging process, oxidative stress theory offers the best mechanism to explain aging and age related disorders. Several studies has shown the importance of oxidative stress during aging. PubMed, Science Direct and Springer online data bases are taken into consideration to write this mini-review. Human erythrocytes are most abundant and specialized cells in the body. Erythrocytes were extensively studied due to their metabolism and gas transport functions. Recent studies on erythrocytes have provided us detailed information of cell membrane and its structural organization that may help in studying the aging and age associated changes. The susceptibility of an organism is associated with the antioxidant potential of the body. Erythrocytes have potent antioxidant protection consisting of enzymatic and non-enzymatic pathways that counteract with reactive oxygen species, thus maintaining the redox regulation in the body. The non-enzymatic and enzymatic antioxidants and other biomarkers associated with erythrocyte membrane transport functions are the main content of this review. Biomarkers of oxidative stress in erythrocytes and its membrane were taken into the consideration during human aging that will be the main subject of this mini- review.

Influence of Dietary Capsaicin on Redox Status in Red Blood Cells During Human Aging

PURPOSE

Capsaicin (8-methyl-N-vanillyl-6-nonenamide) is a major pungent compound found in hot peppers of the plant genus Capsicum. In vitro effects of dietary capsaicin on redox status in red blood cells during human aging have been explored.

METHODS

Total antioxidant potential of capsaicin was evaluated using Ferric reducing ability of plasma (FRAP) assay. GSH was measured as per standard protocol. The in vitro effect of capsaicin was evaluated by incubation of the cells in the assay medium with 10(-5)M capsaicin (final concentration) for 60 min at 37°C.

RESULTS

Treatment with capsaicin (10(-5)M) caused a significant (p < 0.01) increase in GSH level in all age groups. Reduced glutathione (GSH) / Oxidized glutathione (GSSG) ratio measures the redox status of the red blood cell. Significant increase in GSH level due to capsaicin, shift the GSH/GSSG ratio, thus alters the redox status of the cell.

CONCLUSION

The results conclusively prove the efficacy of the antioxidant property of capsaicin and its role in modulating the redox status of red blood cells. This evidence suggests that dietary factors that act as antioxidants to increase GSH level may contribute to a protective effect against age related diseases. This antioxidant effect may, in part, explain the high consumption of capsicum in certain regions of the world.

Markers of oxidative stress in senescent erythrocytes obtained from young and old age rats

The role of oxidative stress during aging is well documented. Evidence is available linking animal life span to the development of oxidative stress. Up to a certain limit of oxidative stress, cells function to counteract the oxidant effects and to restore redox balance by resetting critical homeostatic parameters. Red blood cells (RBCs) offer a very good model to study cellular senescence. In vivo aging of red blood cells is associated with increased cellular density, which corresponds to increased cell age. The present study aims to investigate age-dependent oxidative stress in RBC subpopulations obtained after Percoll density gradient centrifugation from young and old rats. We observe an increase in plasma membrane redox system (PMRS) activity (p<0.001) and lipid peroxidation (p<0.001) between less dense and senescent RBCs in both young and old rats. Our findings provide evidence of a higher level of oxidative stress in senescent erythrocytes, with the effect being more pronounced in old (24-month-old) rats compared to young (4-month-old) rats. The present findings emphasize the role of oxidative stress not only in organismal aging but also in cell senescence.

Epigallocatechin-3-Gallate Protects Erythrocyte Ca(2+)-ATPase and Na(+)/K(+)-ATPase Against Oxidative Induced Damage During Aging in Humans

PURPOSE

The main purpose of this study was to investigate the protective role of epigallocatechin-3-gallate on tertiary butyl hydroperoxide induced oxidative damage in erythrocyte during aging in humans.

METHODS

Human erythrocyte membrane bound Ca(2+)-ATPase and Na(+)/K(+)-ATPase activities were determined as a function of human age. Protective role of epigallocatechin-3-gallate was evaluated by in vitro experiments by adding epigallocatechin-3-gallate in concentration dependent manner (final concentration range 10(-7)M to 10(-4)M) to the enzyme assay medium. Oxidative stress was induced in vitro by incubating washed erythrocyte ghosts with tertiary butyl hydroperoxide (10(-5) M final concentration).

RESULTS

We have reported concentration dependent effect of epigallocatechin-3-gallate on tertiary butyl hydroperoxide induced damage on activities of Ca(2+)-ATPase and Na(+)/K(+)-ATPase during aging in humans. We have detected a significant (p < 0.001) decreased activity of Ca(2+)-ATPase and Na(+)/K(+) -ATPase as a function of human age. Epigallocatechin-3-gallate protected ATPases against tertiary butyl hydroperoxide induced damage in concentration dependent manner during aging in humans.

CONCLUSION

Epigallocatechin-3-gallate is a powerful antioxidant that is capable of protecting erythrocyte Ca(2+)-ATPase and Na(+)/K(+) -ATPase against oxidative stress during aging in humans. We may propose hypothesis that a high intake of catechin rich diet may provide some protection against development of aging and age related diseases.

L-cysteine efflux in erythrocytes as a function of human age: correlation with reduced glutathione and total anti-oxidant potential

Thiol compounds such as cysteine (Cys) and reduced glutathione (GSH) play an important role in human aging and age-related diseases. In erythrocytes, GSH is synthesized by glutamic acid, cysteine, and glycine, but the rate of GSH synthesis is determined only by the availability of L-cysteine. Cysteine supplementation has been shown to ameliorate several parameters that are known to degenerate during human aging. We have studied L-cysteine efflux in vitro in human erythrocytes as a function of age by suspending cells in solution containing 10 mM L-cysteine for uptake; later cells were re-suspended in phosphate-buffered saline (PBS)-glucose to allow efflux. Change in the free sulfhydryl (-SH) concentration was then measured to calculate the rate of efflux. The GSH/oxidized glutathione (GSSG) ratio was taken as a control to study the oxidation/reduction state of the erythrocyte. The total anti-oxidant potential of plasma was measured in terms of ferric reducing ability of plasma (FRAP) values. We have shown a significant (p<0.0001) decline in the efflux of L-cysteine in erythrocytes during human aging, and the GSH/GSSG ratio decreases as a function of human age. The decline in L-cysteine efflux during aging correlates with the decrease in GSH and the FRAP value. This finding may help to explain the shift in the redox status and low GSH concentration that might determine the rate of L-cysteine efflux observed in erythrocytes and an important factor in the development of oxidative stress in erythrocytes during aging.

[L-cysteine influx in diabetic erythrocytes]

Erythrocyte oxidative stress has been implicated in the pathogenesis of diabetes mellitus, and the deficiency of antioxidant defense by the glutathione (GSH) pathway is thought to be one of the factors responsible for development of complications in diabetes. Erythrocytes require L-cysteine for thesynthesis of GSH and the rate of synthesis is determined only by L-cysteine availability. In the present study we have found that the L-cysteine influx in erythrocytes from type 2 diabetic patients was significantly lower compared to age-matched controls. The decreased influx may be one of the factors leading to low GSH concentration observed in type 2 diabetes. Since L-cysteine is the limiting amino acid in GSH synthesis, any strategy aimed to increase L-cysteine influx in erythrocytes may be beneficial for type 2 diabetic patients.

Strategies for the discovery of anti-aging compounds

IMPORTANCE OF THE FIELD

Life expectancy has increased across the globe and the number of aged people is increasing rapidly. With the rise in the average age of people, the prevalence of age related pathologies has also increased and thus the strategies to find anti-aging molecules assume significance. Anti-aging basically concerns the prevention or delaying the alterations taking place as a function of age which are manifested as age-associated illnesses.

AREAS COVERED IN THIS REVIEW

This review covers anti-aging strategies involving supplementation of dietary antioxidants such as polyphenols, vitamins E and C, lipoic acid, acetyl carnitine, carnosine and cysteine along with the application of mammalian target of rapamycin inhibitors and plasma membrane redox system activators. It also presents the use of different hormone supplementation, for example, melatonin, dehydroepiandrosterone, growth hormone and sex hormones as a tool against aging. The use of caloric restriction and calorie restriction mimetics as an anti-aging intervention is also reviewed.

WHAT THE READER WILL GAIN

The concept, use and efficacy of different anti-aging approaches.

TAKE HOME MESSAGE

Despite a lot of research and sustained ongoing efforts, finding a viable anti-aging therapy which can extend the maximum human lifespan remains elusive. However, several interventions aimed towards a longer healthy life seem promising.