Implication of ferroptosis in aging

Anti-oxidant activity of coenzyme Q10 against AlCl3/D-galactose in albino rat induced cognitive dysfunctions: Behavioral, biochemical, and BACE-1/GSK-3β alterations

The relationship between amyloid beta (Aβ) and oxidative stress (OS), both prominent factors in Alzheimer's disease-related neural degeneration, is deeply interconnected. The cleavage of the extracellular domain of Amyloid precursor protein (APP) and phosphorylating different substrates, respectively, the β-site amyloid precursor protein cleaving enzyme-1 (BACE-1) and Glycogen synthase kinase-3-beta (GSK-3β) enzymes initiate the synthesis of Aβ, which causes cognitive deficits in AD. This study aimed to explore the protective potential of Coenzyme Q10 (CoQ10). It also sought to uncover any synergistic effects when combined with donepezil, an acetylcholinesterase inhibitor, in treating Alzheimer's disease in male albino rats, focusing on the modulation of the BACE-1/GSK-3β pathway. The experiment involved 70 rats categorized into different groups: control, donepezil alone, CoQ10 alone, AD-model, donepezil co-treatment, CoQ10 co-treatment, and CoQ10 + donepezil combination. Various assessments, such as cholinesterase activity, oxidative stress, serum iron profile, Brain Derived Neurotrophic Factor (BDNF), Tau protein, β-site amyloid precursor protein cleaving enzyme-1 (BACE-1), phosphatase and tensin homolog (Pten), and Glycogen synthase kinase-3-beta (GSK-3β), were conducted on behavioral and biochemical aspects. CoQ10 treatment demonstrated memory improvement, enhanced locomotion, and increased neuronal differentiation, mainly through the inhibition of the dual BACE-1/GSK-3β. These findings were substantiated by histological and immunohistological examinations of the hippocampus.

Tetrabromobisphenol S (TBBPS) exposure causes gastric cell senescence and inflammation by inducing iron overload

Tetrabromobisphenol S (TBBPS) is a brominated flame retardants (BFRs). TBBPS is widely used as a new type of BFR to replace TBBPA. Here, we used gastric cells as a model for evaluating the effect of TBBPS on the toxicology of gastric cells. Biochemical assays such as indirect immunofluorescence, cell proliferation assay were performed to analyze the toxicological effects of TBBPS on gastric cells. Cell proliferation analysis showed that TBBPS caused inhibition of gastric cell proliferation, and TBBPS induced gastric cell death. Further analysis showed that TBBPS led to ferroptosis and senescence of gastric cells by detecting ferroptosis-related marker molecules. Further work showed that TBBPS treatment resulted in lowered ferritin expression alongside heightened transferrin levels, which may be a potential molecular mechanism for TBBPS-induced ferroptosis and senescence in gastric cells. Here, our team investigates the effects of TBBPS on gastric cells in an in vitro model, and found that TBBPS caused toxicological damage to gastric cells. This study indicates potential toxic effects of TBBPS on the gastric cells, thereby providing a basis for further research into the toxicology of TBBPS.

Skin Aging and the Upcoming Role of Ferroptosis in Geroscience

The skin is considered the most important organ system in mammals, and as the population ages, it is important to consider skin aging and anti-aging therapeutic strategies. Exposure of the skin to various insults induces significant changes throughout our lives, differentiating the skin of a young adult from that of an older adult. These changes are caused by a combination of intrinsic and extrinsic aging. We report the interactions between skin aging and its metabolism, showing that the network is due to several factors. For example, iron is an important nutrient for humans, but its level increases with aging, inducing deleterious effects on cellular functions. Recently, it was discovered that ferroptosis, or iron-dependent cell death, is linked to aging and skin diseases. The pursuit of new molecular targets for ferroptosis has recently attracted attention. Prevention of ferroptosis is an effective therapeutic strategy for the treatment of diseases, especially in old age. However, the pathological and biological mechanisms underlying ferroptosis are still not fully understood, especially in skin diseases such as melanoma and autoimmune diseases. Only a few basic studies on regulated cell death exist, and the challenge is to turn the studies into clinical applications.

Polygonatum polysaccharide ameliorates D-galactose-induced cognitive dysfunction in aging rats by inhibiting ferroptosis through activation of Nrf2

CONTEXT

Aging is a major risk factor for various neurodegenerative diseases, and ferroptosis has been identified as an important mode of cell death during accelerated aging. As the main component of the edible plant YuZhu in China, Polygonatum polysaccharide (POP) is an important natural compound with anti-aging properties.

OBJECTIVE

To evaluate the anti-aging effects of POP and the underlying molecular mechanisms involved and to evaluate the overall anti-aging effects of POP on cognitive impairment due to accelerated aging.

MATERIALS AND METHODS

A D-galactose (D-gal)-induced accelerated aging rat model was established to evaluate the anti-aging effects of POP and the underlying molecular mechanisms involved. In turn, Morris water maze and open field experiments were used to evaluate the anti-aging effects of POP on cognitive impairment due to accelerated aging.

RESULTS

The mechanism by which POP affects nuclear factor E2-related factor 2 (Nrf2), an essential transcription factor, was confirmed. POP significantly improved d-gal-induced cognitive dysfunction in treated model rats, which exhibited reduced pathological changes in the hippocampus, reduced latency of the water maze platform, and increased exploration time in the central area in the open field experiment compared to those of untreated model rats. Furthermore, POP intervention downregulated ferroptosis-related proteins and upregulated Nrf2 expression, and selective inhibition of Nrf2 eliminated the ability of POP to reduce ferroptosis.

CONCLUSIONS

POP is a natural ingredient with therapeutic potential due to its ability to alleviate aging by activating Nrf2, inhibiting ferroptosis, and alleviating cognitive dysfunction.

The Impairment of Endothelial Autophagy Accelerates Renal Senescence by Ferroptosis and NLRP3 Inflammasome Signaling Pathways with the Disruption of Endothelial Barrier

Autophagy is a cellular process that degrades damaged cytoplasmic components and regulates cell death. The homeostasis of endothelial cells (ECs) is crucial for the preservation of glomerular structure and function in aging. Here, we investigated the precise mechanisms of endothelial autophagy in renal aging. The genetic deletion of Atg7 in the ECs of Atg7flox/flox;Tie2-Cre mice accelerated aging-related glomerulopathy and tubulointerstitial fibrosis. The EC-specific Atg7 deletion in aging mice induced the detachment of EC with the disruption of glomerular basement membrane (GBM) assembly and increased podocyte loss resulting in microalbuminuria. A Transwell co-culture system of ECs and kidney organoids showed that the iron and oxidative stress induce the disruption of the endothelial barrier and increase vascular permeability, which was accelerated by the inhibition of autophagy. This resulted in the leakage of iron through the endothelial barrier into kidney organoids and increased oxidative stress, which led to ferroptotic cell death. The ferritin accumulation was increased in the kidneys of the EC-specific Atg7-deficient aging mice and upregulated the NLRP3 inflammasome signaling pathway. The pharmacologic inhibition of ferroptosis with liproxstatin-1 recovered the disrupted endothelial barrier and reversed the decreased expression of GPX4, as well as NLRP3 and IL-1β, in endothelial autophagy-deficient aged mice, which attenuated aging-related renal injury including the apoptosis of renal cells, abnormal structures of GBM, and tubulointerstitial fibrosis. Our data showed that endothelial autophagy is essential for the maintenance of the endothelial barrier during renal aging and the impairment of endothelial autophagy accelerates renal senescence by ferroptosis and NLRP3 inflammasome signaling pathways. These processes may be attractive therapeutic targets to reduce cellular injury from renal aging.

Iron accumulation in ovarian microenvironment damages the local redox balance and oocyte quality in aging mice

Accumulating oxidative damage is a primary driver of ovarian reserve decline along with aging. However, the mechanism behind the imbalance in reactive oxygen species (ROS) is not yet fully understood. Here we investigated changes in iron metabolism and its relationship with ROS disorder in aging ovaries of mice. We found increased iron content in aging ovaries and oocytes, along with abnormal expression of iron metabolic proteins, including heme oxygenase 1 (HO-1), ferritin heavy chain (FTH), ferritin light chain (FTL), mitochondrial ferritin (FTMT), divalent metal transporter 1 (DMT1), ferroportin1(FPN1), iron regulatory proteins (IRP1 and IRP2) and transferrin receptor 1 (TFR1). Notably, aging oocytes exhibited enhanced ferritinophagy and mitophagy, and consistently, there was an increase in cytosolic Fe2+, elevated lipid peroxidation, mitochondrial dysfunction, and augmented lysosome activity. Additionally, the ovarian expression of p53, p21, p16 and microtubule-associated protein tau (Tau) were also found to be upregulated. These alterations could be phenocopied with in vitro Fe2+ administration in oocytes from 2-month-old mice but were alleviated by deferoxamine (DFO). In vivo application of DFO improved ovarian iron metabolism and redox status in 12-month-old mice, and corrected the alterations in cytosolic Fe2+, ferritinophagy and mitophagy, as well as related degenerative changes in oocytes. Thereby in the whole, DFO delayed the decline in ovarian reserve and significantly increased the number of superovulated oocytes with reduced fragmentation and aneuploidy. Together, our findings suggest that aging-related disturbance in ovarian iron homeostasis contributes to excessive ROS production and that iron chelation may improve ovarian redox status, and efficiently delay the decline in ovarian reserve and oocyte quality in aging mice. These data propose a novel intervention strategy for preserving the ovarian reserve function in elderly women.

Platelet-derived exosomes alleviate tendon stem/progenitor cell senescence and ferroptosis by regulating AMPK/Nrf2/GPX4 signaling and improve tendon-bone junction regeneration in rats

BACKGROUND

Tendon stem/progenitor cell (TSPC) senescence contributes to tendon degeneration and impaired tendon repair, resulting in age-related tendon disorders. Ferroptosis, a unique iron-dependent form of programmed cell death, might participate in the process of senescence. However, whether ferroptosis plays a role in TSPC senescence and tendon regeneration remains unclear. Recent studies reported that Platelet-derived exosomes (PL-Exos) might provide significant advantages in musculoskeletal regeneration and inflammation regulation. The effects and mechanism of PL-Exos on TSPC senescence and tendon regeneration are worthy of further study.

METHODS

Herein, we examined the role of ferroptosis in the pathogenesis of TSPC senescence. PL-Exos were isolated and determined by TEM, particle size analysis, western blot and mass spectrometry identification. We investigated the function and underlying mechanisms of PL-Exos in TSPC senescence and ferroptosis via western blot, real-time quantitative polymerase chain reaction, and immunofluorescence analysis in vitro. Tendon regeneration was evaluated by HE staining, Safranin-O staining, and biomechanical tests in a rotator cuff tear model in rats.

RESULTS

We discovered that ferroptosis was involved in senescent TSPCs. Furthermore, PL-Exos mitigated the aging phenotypes and ferroptosis of TSPCs induced by t-BHP and preserved their proliferation and tenogenic capacity. The in vivo animal results indicated that PL-Exos improved tendon-bone healing properties and mechanical strength. Mechanistically, PL-Exos activated AMPK phosphorylation and the downstream nuclear factor erythroid 2-related factor 2 (Nrf2)/glutathione peroxidase 4 (GPX4) signaling pathway, leading to the suppression of lipid peroxidation. AMPK inhibition or GPX4 inhibition blocked the protective effect of PL-Exos against t-BHP-induced ferroptosis and senescence.

CONCLUSION

In conclusion, ferroptosis might play a crucial role in TSPC aging. AMPK/Nrf2/GPX4 activation by PL-Exos was found to inhibit ferroptosis, consequently leading to the suppression of senescence in TSPCs. Our results provided new theoretical evidence for the potential application of PL-Exos to restrain tendon degeneration and promote tendon regeneration.

SLC22A17 as a Cell Death-Linked Regulator of Tight Junctions in Cerebral Ischemia

BACKGROUND

Beyond neuronal injury, cell death pathways may also contribute to vascular injury after stroke. We examined protein networks linked to major cell death pathways and identified SLC22A17 (solute carrier family 22 member 17) as a novel mediator that regulates endothelial tight junctions after ischemia and inflammatory stress.

METHODS

Protein-protein interactions and brain enrichment analyses were performed using STRING, Cytoscape, and a human tissue-specific expression RNA-seq database. In vivo experiments were performed using mouse models of transient focal cerebral ischemia. Human stroke brain tissues were used to detect SLC22A17 by immunostaining. In vitro experiments were performed using human brain endothelial cultures subjected to inflammatory stress. Immunostaining and Western blot were used to assess responses in SLC22A17 and endothelial tight junctional proteins. Water content, dextran permeability, and electrical resistance assays were used to assess edema and blood-brain barrier (BBB) integrity. Gain and loss-of-function studies were performed using lentiviral overexpression of SLC22A17 or short interfering RNA against SLC22A17, respectively.

RESULTS

Protein-protein interaction analysis showed that core proteins from apoptosis, necroptosis, ferroptosis, and autophagy cell death pathways were closely linked. Among the 20 proteins identified in the network, the iron-handling solute carrier SLC22A17 emerged as the mediator enriched in the brain. After cerebral ischemia in vivo, endothelial expression of SLC22A17 increases in both human and mouse brains along with BBB leakage. In human brain endothelial cultures, short interfering RNA against SLC22A17 prevents TNF-α (tumor necrosis factor alpha)-induced ferroptosis and downregulation in tight junction proteins and disruption in transcellular permeability. Notably, SLC22A17 could repress the transcription of tight junctional genes. Finally, short interfering RNA against SLC22A17 ameliorates BBB leakage in a mouse model of focal cerebral ischemia.

CONCLUSIONS

Using a combination of cell culture, human stroke samples, and mouse models, our data suggest that SLC22A17 may play a role in the control of BBB function after cerebral ischemia. These findings may offer a novel mechanism and target for ameliorating BBB injury and edema after stroke.

Cuproptosis-Related Gene FDX1 Identified as a Potential Target for Human Ovarian Aging

Cuproptosis is a recently discovered mode of cell death that has garnered attention due to its association with various diseases. However, the intricate genetic relationship between cuproptosis and ovarian aging has remained largely unexplored. This study aimed to bridge this knowledge gap by leveraging data sets related to ovarian aging and cuproptosis. Through comprehensive bioinformatics analyses, facilitated by R software, we uncovered FDX1 as a potential cuproptosis-related gene with relevance to ovarian aging. To gain insights into FDX1's role, we conducted spatial transcriptome analyses in the ovaries of both young and aged female mice. These experiments revealed a significant reduction in FDX1 expression in the aging group compared to the young group. To substantiate these findings at the genetic level, we turned to clinical infertility biopsies. Impressively, we observed consistent results in biopsies from elderly infertile patients, reinforcing the link between FDX1 and ovarian aging. Moreover, we delved into the pharmacogenomics of ovarian cell lines and discovered that FDX1 expression levels were intricately associated with heightened sensitivity to specific small molecule drugs. This observation suggests that modulating FDX1 could potentially be a strategy to influence drug responses in ovarian-related therapies. In sum, this study marks a pioneering effort in identifying FDX1 as a cuproptosis-related gene implicated in ovarian aging. These findings hold substantial promise, not only in shedding light on the underlying mechanisms of ovarian aging but also in positioning FDX1 as a potential diagnostic biomarker and therapeutic target. With further research, FDX1 could play a pivotal role in advancing precision medicine and therapies for ovarian-related conditions.

Iron retardation in lysosomes protects senescent cells from ferroptosis

Ferroptosis, an iron-triggered modality of cellular death, has been reported to closely relate to human aging progression and aging-related diseases. However, the involvement of ferroptosis in the development and maintenance of senescent cells still remains elusive. Here, we established a doxorubicin-induced senescent HSkM cell model and found that both iron accumulation and lipid peroxidation increase in senescent cells. Moreover, such iron overload in senescent cells has changed the expression panel of the ferroptosis-response proteins. Interestingly, the iron accumulation and lipid peroxidation does not trigger ferroptosis-induced cell death. Oppositely, senescent cells manifest resistance to the ferroptosis inducers, compared to the proliferating cells. To further investigate the mechanism of ferroptosis-resistance for senescent cells, we traced the iron flux in cell and found iron arrested in lysosome. Moreover, disruption of lysosome functions by chloroquine and LLOMe dramatically triggered the senescent cell death. Besides, the ferroitinophagy-related proteins FTH1/FTL and NCOA4 knockdown also increases the senescent cell death. Thus, we speculated that iron retardation in lysosome of senescent cells is the key mechanism for ferroptosis resistance. And the lysosome is a promising target for senolytic drugs to selectively clear senescent cells and alleviate the aging related diseases.

Melatonin: a ferroptosis inhibitor with potential therapeutic efficacy for the post-COVID-19 trajectory of accelerated brain aging and neurodegeneration

The unprecedented pandemic of COVID-19 swept millions of lives in a short period, yet its menace continues among its survivors in the form of post-COVID syndrome. An exponentially growing number of COVID-19 survivors suffer from cognitive impairment, with compelling evidence of a trajectory of accelerated aging and neurodegeneration. The novel and enigmatic nature of this yet-to-unfold pathology demands extensive research seeking answers for both the molecular underpinnings and potential therapeutic targets. Ferroptosis, an iron-dependent cell death, is a strongly proposed underlying mechanism in post-COVID-19 aging and neurodegeneration discourse. COVID-19 incites neuroinflammation, iron dysregulation, reactive oxygen species (ROS) accumulation, antioxidant system repression, renin-angiotensin system (RAS) disruption, and clock gene alteration. These events pave the way for ferroptosis, which shows its signature in COVID-19, premature aging, and neurodegenerative disorders. In the search for a treatment, melatonin shines as a promising ferroptosis inhibitor with its repeatedly reported safety and tolerability. According to various studies, melatonin has proven efficacy in attenuating the severity of certain COVID-19 manifestations, validating its reputation as an anti-viral compound. Melatonin has well-documented anti-aging properties and combating neurodegenerative-related pathologies. Melatonin can block the leading events of ferroptosis since it is an efficient anti-inflammatory, iron chelator, antioxidant, angiotensin II antagonist, and clock gene regulator. Therefore, we propose ferroptosis as the culprit behind the post-COVID-19 trajectory of aging and neurodegeneration and melatonin, a well-fitting ferroptosis inhibitor, as a potential treatment.

Epigenetic erosion of H4K20me1 induced by inflammation drives aged stem cell ferroptosis

Aging is associated with a decline in stem cell functionality and number across the organism. In this study, we aimed to further unravel Muscle Stem Cells (MuSCs) aging by assessing how systemic factors influence MuSC fate decisions through long-term epigenetic landscape remodelling. As aging is intricately linked to a pro-inflammatory shift, we studied the epigenetic effects of inflammatory signals in MuSCs and measured decreased H4K20me1 levels. This loss disrupts MuSC quiescence, largely through epigenetic silencing of Notch target genes. In the setting of inflammatory signals or aging, the lack of Kmt5a and the subsequent absence of de novoH4K20me1 culminate in cell death by ferroptosis. Aged MuSCs manifest abnormal iron metabolism and reduced Gpx4 levels, resulting in the accumulation of intracellular iron, increased reactive oxygen species, genomic instability, and lipid peroxidation. We showed that ferroptosis is the predominant mode of cell death in aged MuSCs, with remarkably high levels of lipid peroxidation; a phenomenon we also observed in aged hematopoietic stem cells. Implementing preventative strategies to inhibit systemic inflammation prevented aged MuSC ferroptosis, preserving their numbers and regenerative capabilities. This intervention significantly enhanced aged muscle regeneration and strength recovery and extended both lifespan and healthspan in mice. This study delineates a previously underappreciated fate trajectory for stem cell aging, and offers meaningful insights into the treatment of age-related disorders.

Involvement of regulated cell deaths in aging and age-related pathologies

Aging is a pathophysiological process that causes a gradual and permanent reduction in all biological system functions. The phenomenon is caused by the accumulation of endogenous and exogenous damage as a result of several stressors, resulting in significantly increased risks of various age-related diseases such as neurodegenerative diseases, cardiovascular diseases, metabolic diseases, musculoskeletal diseases, and immune system diseases. In addition, aging appears to be connected with mis-regulation of programmed cell death (PCD), which is required for regular cell turnover in many tissues sustained by cell division. According to the recent nomenclature, PCDs are physiological forms of regulated cell death (RCD) useful for normal tissue development and turnover. To some extent, some cell types are connected with a decrease in RCD throughout aging, whereas others are related with an increase in RCD. Perhaps the widespread decline in RCD markers with age is due to a slowdown of the normal rate of homeostatic cell turnover in various adult tissues. As a result, proper RCD regulation requires a careful balance of many pro-RCD and anti-RCD components, which may render cell death signaling pathways more sensitive to maladaptive signals during aging. Current research, on the other hand, tries to further dive into the pathophysiology of aging in order to develop therapies that improve health and longevity. In this scenario, RCD handling might be a helpful strategy for human health since it could reduce the occurrence and development of age-related disorders, promoting healthy aging and lifespan. In this review we propose a general overview of the most recent RCD mechanisms and their connection with the pathophysiology of aging in order to promote targeted therapeutic strategies.

Ferroptosis and aerobic training in ageing

 Ferroptosis is a form of programmed cell death that plays a significant role in causing several diseases such as heart attack and heart failure, through alterations in fat, amino acid, and iron metabolism. Comprehending the regulatory mechanisms of ferroptosis signaling is critical because it has a considerable effect on the elderly's mortality. Conversely, age-related changes in substrate metabolism and metabolite levels are recognized to give rise to obesity. Furthermore, research has proposed that aging and obesity-related changes in substrate metabolism may aggravate ferroptosis. The suppression of ferroptosis holds potential as a successful therapeutic approach for managing different diseases, including sarcopenia, cardiovascular diseases, and central nervous system diseases. However, the pathologic and biological mechanisms behind the function of ferroptosis are not fully comprehended yet. Physical activity could affect lipid, amino acid, and iron metabolism to modulate ferroptosis. The aim of this study is to showcase the current understanding of the molecular mechanisms leading to ferroptosis and discuss the role of aging and physical activity in this phenomenon.

Copper homeostasis and copper-induced cell death： Novel targeting for intervention in the pathogenesis of vascular aging

Copper-induced cell death, also known as cuproptosis, is distinct from other types of cell death such as apoptosis, necrosis, and ferroptosis. It can trigger the accumulation of lethal reactive oxygen species, leading to the onset and progression of aging. The significant increases in copper ion levels in the aging populations confirm a close relationship between copper homeostasis and vascular aging. On the other hand, vascular aging is also closely related to the occurrence of various cardiovascular diseases throughout the aging process. However, the specific causes of vascular aging are not clear, and different living environments and stress patterns can lead to individualized vascular aging. By exploring the correlations between copper-induced cell death and vascular aging, we can gain a novel perspective on the pathogenesis of vascular aging and enhance the prognosis of atherosclerosis. This article aims to provide a comprehensive review of the impacts of copper homeostasis on vascular aging, including their effects on endothelial cells, smooth muscle cells, oxidative stress, ferroptosis, intestinal flora, and other related factors. Furthermore, we intend to discuss potential strategies involving cuproptosis and provide new insights for copper-related vascular aging.

Combination of the biomarkers for aging and cancer? - Challenges and current status

The proportion of patients diagnosed with cancer has been shown to rise with the increasing aging global population. Advanced age is a major risk factor for morbidity and mortality in older adults. As individuals experience varying health statuses, particularly with age, it poses a challenge for medical professionals in the cancer field to obtain standardized treatment outcomes. Hence, relying solely on chronological age and disease-related parameters is inadequate for clinical decision-making for elderly patients. With functional, multimorbidity-related, and psychosocial changes that occur with aging, oncologic diseases may develop and be treated differently from younger patients, leading to unique challenges in treatment efficacy and tolerance. To overcome this challenge, personalized therapy using biomarkers has emerged as a promising solution. Various categories of biomarkers, including inflammatory, hematological, metabolic, endocrine, and DNA modification-related indicators, may display features related to both cancer and aging, aiding in the development of innovative therapeutic approaches for patients with cancer in old age. Furthermore, physical functional measurements as non-molecular phenotypic biomarkers are being investigated for their potential complementary role in structured multidomain strategies to combat age-related diseases such as cancer. This review provides insight into the current developments, recent discoveries, and significant challenges in cancer and aging biomarkers, with a specific focus on their application in advanced age.

Unraveling the Clinical Relevance of Ferroptosis-Related Genes in Human Ovarian Aging

Ferroptosis, a recently discovered form of cell death, has been implicated in various diseases. However, the genetic relationship between ferroptosis and ovarian aging has not been thoroughly investigated through informatics analysis. In this study, we conducted bioinformatics analysis using ovarian aging and ferroptosis datasets to identify potential ferroptosis-related genes using R software. The expression levels of these genes at different ages were analyzed using the GTEx public database. To validate these findings at the genetic level, we performed clinical infertility biopsies. Bioinformatics analysis of a mouse ovary dataset revealed significantly higher expression of Tfrc, Ncoa4, and Slc3a2 in the aging group compared to the young group, while Gpx4 showed the opposite pattern. Consistent results were observed in biopsies from clinically aged infertile patients. This study is the first to identify a ferroptosis-related gene associated with ovarian aging, highlighting its potential as a diagnostic biomarker.

Glutathione and glutathione-dependent enzymes: From biochemistry to gerontology and successful aging

The tripeptide glutathione (GSH), namely γ-L-glutamyl-L-cysteinyl-glycine, is an ubiquitous low-molecular weight thiol nucleophile and reductant of utmost importance, representing the central redox agent of most aerobic organisms. GSH has vital functions involving also antioxidant protection, detoxification, redox homeostasis, cell signaling, iron metabolism/homeostasis, DNA synthesis, gene expression, cysteine/protein metabolism, and cell proliferation/differentiation or death including apoptosis and ferroptosis. Various functions of GSH are exerted in concert with GSH-dependent enzymes. Indeed, although GSH has direct scavenging antioxidant effects, its antioxidant function is substantially accomplished by glutathione peroxidase-catalyzed reactions with reductive removal of H2O2, organic peroxides such as lipid hydroperoxides, and peroxynitrite; to this antioxidant activity also contribute peroxiredoxins, enzymes further involved in redox signaling and chaperone activity. Moreover, the detoxifying function of GSH is basically exerted in conjunction with glutathione transferases, which have also antioxidant properties. GSH is synthesized in the cytosol by the ATP-dependent enzymes glutamate cysteine ligase (GCL), which catalyzes ligation of cysteine and glutamate forming γ-glutamylcysteine (γ-GC), and glutathione synthase, which adds glycine to γ-GC resulting in GSH formation; GCL is rate-limiting for GSH synthesis, as is the precursor amino acid cysteine, which may be supplemented as N-acetylcysteine (NAC), a therapeutically available compound. After its cell export, GSH is degraded extracellularly by the membrane-anchored ectoenzyme γ-glutamyl transferase, a process occurring, as GSH synthesis and export, in the γ-glutamyl cycle. GSH degradation occurs also intracellularly by the cytoplasmic enzymatic ChaC family of γ-glutamyl cyclotransferase. Synthesis and degradation of GSH, together with its export, translocation to cell organelles, utilization for multiple essential functions, and regeneration from glutathione disulfide by glutathione reductase, are relevant to GSH homeostasis and metabolism. Notably, GSH levels decline during aging, an alteration generally related to impaired GSH biosynthesis and leading to cell dysfunction. However, there is evidence of enhanced GSH levels in elderly subjects with excellent physical and mental health status, suggesting that heightened GSH may be a marker and even a causative factor of increased healthspan and lifespan. Such aspects, and much more including GSH-boosting substances administrable to humans, are considered in this state-of-the-art review, which deals with GSH and GSH-dependent enzymes from biochemistry to gerontology, focusing attention also on lifespan/healthspan extension and successful aging; the significance of GSH levels in aging is considered also in relation to therapeutic possibilities and supplementation strategies, based on the use of various compounds including NAC-glycine, aimed at increasing GSH and related defenses to improve health status and counteract aging processes in humans.

Vitamin D Improves Cognitive Impairment and Alleviates Ferroptosis via the Nrf2 Signaling Pathway in Aging Mice

Ferroptosis is an iron-dependent mode of cell death associated with the occurrence and development of age-related neurodegenerative diseases. Currently, there are no effective drugs available to prevent or treat these aging-related neurodegenerative diseases. Vitamin D (VD) is an antioxidant and immunomodulator, but its relationship with ferroptosis in aging-related neurodegenerative diseases has not been extensively studied. In this study, we aimed to investigate the role of VD in learning and memory in aging mice. To examine whether VD protects aging hippocampal neurons, we used physiologically active 1,25(OH)2D3. We established aging models in vivo (C57BL/6 mice) and in vitro (HT22 cells) using D-galactose (D-gal). The results demonstrated that VD could improve learning and memory in mice aged via the use of D-gal, and it reduced damage to hippocampal neurons. VD could regulate ferroptosis-related proteins (increasing GPX4 expression and decreasing ACSL4 and ALOX15 protein expression levels), increasing GSH levels, reducing MDA and intracellular and mitochondrial ROS levels, as well as total iron and Fe2+ levels, and improving mitochondrial morphology, thereby alleviating ferroptosis in aging hippocampal neurons. Additionally, VD activated the VDR/Nrf2/HO-1 signaling pathway, thereby inhibiting ferroptosis. Notably, when the VDR was knocked down, VD lost its ability to activate Nrf2. Consequently, inhibiting Nrf2 decreased the protective effect of VD against ferroptosis in aged hippocampal neurons. In summary, VD activates the Nrf2/HO-1 signaling pathway through the VDR, effectively preventing ferroptosis induced by aging in hippocampal neurons.

Cardiac iron metabolism during aging - Role of inflammation and proteolysis

Iron is the most abundant trace element in the human body. Since iron can switch between its 2-valent and 3-valent form it is essential in various physiological processes such as energy production, proliferation or DNA synthesis. Especially high metabolic organs such as the heart rely on iron-associated iron-sulfur and heme proteins. However, due to switches in iron oxidation state, iron overload exhibits high toxicity through formation of reactive oxygen species, underlining the importance of balanced iron levels. Growing evidence demonstrates disturbance of this balance during aging. While age-associated cardiovascular diseases are often related to iron deficiency, in physiological aging cardiac iron accumulates. To understand these changes, we focused on inflammation and proteolysis, two hallmarks of aging, and their role in iron metabolism. Via the IL-6-hepcidin axis, inflammation and iron status are strongly connected often resulting in anemia accompanied by infiltration of macrophages. This tight connection between anemia and inflammation highlights the importance of the macrophage iron metabolism during inflammation. Age-related decrease in proteolytic activity additionally affects iron balance due to impaired degradation of iron metabolism proteins. Therefore, this review accentuates alterations in iron metabolism during aging with regards to inflammation and proteolysis to draw attention to their implications and associations.

The iron-dopamine D1 coupling modulates neural signatures of working memory across adult lifespan

Brain iron overload and decreased integrity of the dopaminergic system have been independently reported as brain substrates of cognitive decline in aging. Dopamine (DA), and iron are co-localized in high concentrations in the striatum and prefrontal cortex (PFC), but follow opposing age-related trajectories across the lifespan. DA contributes to cellular iron homeostasis and the activation of D1-like DA receptors (D1DR) alleviates oxidative stress-induced inflammatory responses, suggesting a mutual interaction between these two fundamental components. Still, a direct in-vivo study testing the iron-D1DR relationship and their interactions on brain function and cognition across the lifespan is rare. Using PET and MRI data from the DyNAMiC study (n=180, age=20-79, %50 female), we showed that elevated iron content was related to lower D1DRs in DLPFC, but not in striatum, suggesting that dopamine-rich regions are less susceptible to elevated iron. Critically, older individuals with elevated iron and lower D1DR exhibited less frontoparietal activations during the most demanding task, which in turn was related to poorer working-memory performance. Together, our findings suggest that the combination of elevated iron load and reduced D1DR contribute to disturbed PFC-related circuits in older age, and thus may be targeted as two modifiable factors for future intervention.

Pomegranate polyphenol punicalagin improves learning memory deficits, redox homeostasis, and neuroinflammation in aging mice

Alzheimer's disease (AD) is an irreversible, progressive brain disorder characterized by loss of memory and cognitive dysfunction in the aged. Despite remarkable advances in drug therapy, effective pharmacological interventions are rare. Punicalagin (PU) is an active antioxidant polyphenol found in pomegranates, raspberries, blueberries, and chestnuts that has attracted considerable attention owing to its strong antioxidant and anti-inflammatory properties. The current study focused on the neuroprotective effect of PU on aging mice and its potential mechanisms. In this study, we first evaluated the protective effect of PU on neuro-2a (N2a) cell damage mediated by BV2 microglia-induced neuroinflammation. The in vivo D-galactose (D-gal)-induced brain aging model demonstrated that PU ameliorated deficits in learning and memory and prevented neuroinflammation, which was evident from the decrease in microglial activation and astrocytosis. Furthermore, PU reduced the levels of malondialdehyde (MDA) and reactive oxygen species (ROS) and inhibited NLRP3 inflammasome activation, reducing the levels of inflammatory cytokines, such as interleukin-6 (IL-6), tumor necrosis factor-a (TNF-a), interleukin-18 (IL-18), and interleukin-1 beta (IL-1β) in both accelerated aging and naturally senescent mouse models. PU effectively improved neuroinflammation, learning and memory deficits, and redox homeostasis in aging mice, and it could be a potential therapeutic agent for AD.

Increased Iron Levels and Oxidative Stress Mediate Age-Related Impairments in Male and Female Drosophila melanogaster

Aging is characterized by a functional decline in the physiological functions and organic systems, causing frailty, illness, and death. Ferroptosis is an iron- (Fe-) dependent regulated cell death, which has been implicated in the pathogenesis of several disorders, such as cardiovascular and neurological diseases. The present study investigated behavioral and oxidative stress parameters over the aging of Drosophila melanogaster that, together with augmented Fe levels, indicate the occurrence of ferroptosis. Our work demonstrated that older flies (30-day-old) of both sexes presented impaired locomotion and balance when compared with younger flies (5-day-old). Older flies also produced higher reactive oxygen species (ROS) levels, decreased glutathione levels (GSH), and increased lipid peroxidation. In parallel, Fe levels were augmented in the fly's hemolymph. The GSH depletion with diethyl maleate potentiated the behavioral damage associated with age. Our data demonstrated biochemical effects that characterize the occurrence of ferroptosis over the age of D. melanogaster and reports the involvement of GSH in the age-associated damages, which could be in part attributed to the augmented levels of Fe.

Age-related changes in adipose tissue metabolomics and inflammation, cardiolipin metabolism, and ferroptosis markers in female aged rat model

Aging adipose tissue exhibits elevated inflammation and oxidative stress that are major sources of age-related metabolic dysfunction. However, the exact metabolic changes associated with inflammation and oxidative stress are unclear. To address this topic, we assessed variation in metabolic phenotypes of adipose tissue from 18 months adult sedentary (ASED), 26 months old sedentary (OSED), and 8 months young sedentary (YSED). The results of metabolomic analysis showed that ASED and OSED group had higher palmitic acid, elaidic acid, 1-heptadecanol, and α-tocopherol levels than YSED, but lower sarcosine levels. Furthermore, stearic acid was specifically elevated in ASED compared with YSED. Cholesterol was upregulated specifically in the OSED group compared with YSED, whereas linoleic acid was downregulated. In addition, ASED and OSED had more inflammatory cytokines, lower antioxidant capacity, and higher expression of ferroptosis-related genes than YSED. Moreover, mitochondrial dysfunction associated with abnormal cardiolipin synthesis was more pronounced in the OSED group. In conclusion, both ASED and OSED can affect the FA metabolism and increase oxidative stress in adipose tissue, leading to inflammation. In particular, linoleic acid content specifically decreases in OSED, which associated with abnormal cardiolipin synthesis and mitochondrial dysfunction in adipose tissue.

Klotho protects against aged myocardial cells by attenuating ferroptosis

Klotho (KL) is a renal protein with aging-suppression properties that mediates its regulatory effect during cardiac fibroblast aging. However, to determine whether KL can protect aged myocardial cells by attenuating ferroptosis, this study aimed to investigate the protective effect of KL on aged cells and to explore its potential mechanism. Cell injury of H9C2 cells was induced with D-galactose (D-gal) and treated with KL in vitro. This study demonstrated that D-gal induces aging in H9C2 cells. D-gal treatment increased β-GAL(β-galactosidase) activity, decreased cell viability, enhanced oxidative stress, reduced mitochondrial cristae, and decreased the expression of solute carrier family 7 member 11 (SLC7A11), glutathione peroxidase-4 (GPx4), and P53, which are primary regulators of ferroptosis. The results showed that KL can eliminate D-gal-induced aging in H9C2 cells, likely due to its ability to increase the expression of the ferroptosis-associated proteins SLC7A11 and GPx4. Moreover, pifithrin-α, a P53-specific inhibitor, attenuated the expression of SLC7A11 and GPx4. These results suggest that KL may be involved in D-gal-induced H9C2 cellular aging during ferroptosis, mainly through the P53/SLC7A11/GPx4 signaling pathway.

Molecular Mechanisms of Ferroptosis and Updates of Ferroptosis Studies in Cancers and Leukemia

Ferroptosis is a mode of cell death regulated by iron-dependent lipid peroxidation. Growing evidence suggests ferroptosis induction as a novel anti-cancer modality that could potentially overcome therapy resistance in cancers. The molecular mechanisms involved in the regulation of ferroptosis are complex and highly dependent on context. Therefore, a comprehensive understanding of its execution and protection machinery in each tumor type is necessary for the implementation of this unique cell death mode to target individual cancers. Since most of the current evidence for ferroptosis regulation mechanisms is based on solid cancer studies, the knowledge of ferroptosis with regard to leukemia is largely lacking. In this review, we summarize the current understanding of ferroptosis-regulating mechanisms with respect to the metabolism of phospholipids and iron as well as major anti-oxidative pathways that protect cells from ferroptosis. We also highlight the diverse impact of p53, a master regulator of cell death and cellular metabolic processes, on the regulation of ferroptosis. Lastly, we discuss recent ferroptosis studies in leukemia and provide a future perspective for the development of promising anti-leukemia therapies implementing ferroptosis induction.

Protective effect of rutin on ferroptosis-induced oxidative stress in aging laying hens through Nrf2/HO-1 signaling

Oxidative stress is a major cause of ovarian aging and follicular atresia. There is growing evidence that showed potential roles of rutin in antidiabetic, anti-inflammatory, antitumor, antibacterial and antioxidant, although it is yet unclear what the underlying mechanism is. Here, we looked into the potential effects of rutin on oxidative stress in the prehierarchical small white follicles (SWFs) from 580-day-old (D580) laying chickens. According to the findings, aging D580 layer ferroptosis was much higher than it was for laying hens during the peak period (280-day-old, D280). In both naturally aged and d-gal-induced chicken SWFs, rutin treatment concurrently boosted cell proliferation and prevented apoptosis. In addition, rutin inhibited the increased ferroptosis in aging hens. Meanwhile, rutin markedly suppressed the elevated ferroptosis and descending antioxidant capacity of D280-culture-SWFs from chicken elicited by d-gal. Rutin's activation of the Nrf2/HO-1 pathway hastened the SWFs' verbal battle with oxidative damage and reduced ferroptosis. Furthermore, activation of the ferroptosis signal increased the oxidative damage in SWFs. In conclusion, rutin alleviated oxidative stress that was induced by ferroptosis in aging chicken SWFs through Nrf2/HO-1 pathway. These findings point to a novel mechanism by which rutin protects SWFs from oxidative stress by suppressing ferroptosis, which is presumably a fresh approach to slowing ovarian aging in laying hens.

Ferroptosis and Senescence: A Systematic Review

Senescence is a cellular aging process in all multicellular organisms. It is characterized by a decay in cellular functions and proliferation, resulting in increased cellular damage and death. This condition plays an essential role in the aging process and significantly contributes to the development of age-related complications. On the other hand, ferroptosis is a systemic cell death pathway characterized by excessive iron accumulation followed by the generation of reactive oxygen species (ROS). Oxidative stress is a common trigger of this condition and may be induced by various factors such as toxins, drugs, and inflammation. Ferroptosis is linked to numerous disorders, including cardiovascular disease, neurodegeneration, and cancer. Senescence is believed to contribute to the decay in tissue and organ functions occurring with aging. It has also been linked to the development of age-related pathologies, such as cardiovascular diseases, diabetes, and cancer. In particular, senescent cells have been shown to produce inflammatory cytokines and other pro-inflammatory molecules that can contribute to these conditions. In turn, ferroptosis has been linked to the development of various health disorders, including neurodegeneration, cardiovascular disease, and cancer. Ferroptosis is known to play a role in the development of these pathologies by promoting the death of damaged or diseased cells and contributing to the inflammation often associated. Both senescence and ferroptosis are complex pathways that are still not fully understood. Further research is needed to thoroughly investigate the role of these processes in aging and disease, and to identify potential interventions to target such processes in order to prevent or treat age-related conditions. This systematic review aims to assess the potential mechanisms underlying the link connecting senescence, ferroptosis, aging, and disease, and whether they can be exploited to block or limit the decay of the physiological functions in elderly people for a healthy longevity.

Establishment of Ferroptosis-Related Key Gene Signature and Its Validation in Compression-Induced Intervertebral Disc Degeneration Rats

Cell death and functional loss of nucleus pulposus cell play essential roles in intervertebral disc degeneration (IDD). Ferroptosis is a newly identified cell death type, and its role in IDD is still under investigation. Identifying the key genes of ferroptosis in IDD helps to identify the therapeutic targets of IDD. In this study, we downloaded the human IDD mRNA microarray data from the Gene Expression Omnibus and ferroptosis genes from FerrDb, then performed a series of analyses using strict bioinformatics algorithms. In general, we obtained 40 ferroptosis-related differential expression genes (FerrDEGs) and identified six ferroptosis key gene signatures, namely, ATF3, EIF2S1, AR, NQO1, TXNIP, and AKR1C3. In addition, enrichment analysis of the FerrDEGs was conducted, the protein-protein interaction network was constructed, the correlations between ferroptosis key genes and immune infiltrating cells were analyzed, and the lncRNA-miRNA-mRNA ceRNA network was constructed. In particular, ATF3 and EIF2S1 showed the strongest correlation with immune cell function, which might lead to the development of IDD. Finally, the expressions of ferroptosis key genes were verified in the rat compression-induced IDD. In conclusion, this preliminary study analyzed and verified the mechanism of ferroptosis in IDD, laid a foundation for the follow-up study of the mechanism of ferroptosis in IDD, and provided new targets for preventing and delaying IDD.

A proteomic profile of the healthy human placenta

BACKGROUND

The placenta remains one of the least studied organs within the human body. Yet, placental dysfunction has been associated with various pregnancy complications leading to both maternal and fetal death and long-term health consequences. The aim of this study was to characterise the protein networks of healthy term placental sub-anatomical regions using label free quantification mass spectrometry.

METHODS

Three healthy placentae were sampled at five sample sites and each biopsy was dissected into maternal-, middle-, and fetal- sub-anatomical regions. Quadrupole-orbitrap mass spectrometer was used in data dependant analysis mode to identify 1859 unique proteins before detailed differential expression between regions.

RESULTS

Protein profiling identified 1081, 1086, and 1101 proteins in maternal, middle, and fetal sub-anatomical regions respectively. Differentially expressed proteins were identified considering the effect between sample site location and sub-anatomical region on protein expression. Of these, 374 differentially expressed proteins (Two-way ANOVA adjusted p-value < 0.05, HSD Tukey adjusted p-value 0.05) were identified between sample site locations and sub-anatomical regions. The placenta specific disease map NaviCenta ( https://www.sbi.uni-rostock.de/minerva/index.xhtml?id=NaviCenta ) was used to focus functional analysis results to the placenta specific context. Subsequently, functional analysis with a focus on senescence, and mitochondrial function were performed. Significant differences were observed between sub-anatomical regions in protein intensity and composition. A decrease in anti-senescent proteins within the maternal sub-anatomical region, and an increase in proteins associated with a switch from ATP to fatty acid consumption as a source of energy between middle and fetal sub-anatomical regions were observed.

CONCLUSION

These results suggest that normal proteomic variations exist within the anatomical structure of the placenta, thus recommending serial sectioning methodology for consistent placental research.

Alteration of Cognitive Function in Aging and Alzheimer's Disease Mice Is Related to Dysfunction of the Neuroimmune System

BACKGROUND

Both Alzheimer's disease (AD) and aging have aging-related cognitive dysfunction with a high incidence. These neurological diseases cause serious cognitive problems in patients' daily life. But the cognitive dysfunction mechanism in-depth of aging is far less known than that of AD.

OBJECTIVE

To reveal the different mechanisms of AD and aging-related cognitive dysfunction, we compared the mechanisms of aging and AD through analysis of differentially expressed genes.

METHODS

Mice were divided into four groups (3-month C57BL, 16-month C57BL, 3-month 3xTg AD mice, and 16-month 3xTg AD mice) according to genotype and age. The Morris water maze was employed to investigate the spatial cognition of mice. Differential expressions of genes of AD and aging were analyzed through RNA sequencing and GO, KEGG, Reactome analysis, and the dynamic change trend analysis. Microglia was stained with immunofluorescence and its numbers were counted for analysis.

RESULTS

The cognitive function of elderly mice were worse through testing with the Morris water maze. The cognitive function of 16-month 3xTg AD mice were worse than 16-month C57BL mice. The alteration tendencies of DE genes were uncovered, and microglia numbers increased during aging and AD progression through immunofluorescence.

CONCLUSION

These results suggest that immune-related pathways might play a critical role in aging and AD-related cognitive dysfunction. Our research will help to provide some new potential targets for treating cognitive dysfunction in aging and AD.

Croix CM, Sinha D. Increased LCN2 (lipocalin 2) in the RPE decreases autophagy and activates inflammasome-ferroptosis processes in a mouse model of dry AMD

In dry age-related macular degeneration (AMD), LCN2 (lipocalin 2) is upregulated. Whereas LCN2 has been implicated in AMD pathogenesis, the mechanism remains unknown. Here, we report that in retinal pigmented epithelial (RPE) cells, LCN2 regulates macroautophagy/autophagy, in addition to maintaining iron homeostasis. LCN2 binds to ATG4B to form an LCN2-ATG4B-LC3-II complex, thereby regulating ATG4B activity and LC3-II lipidation. Thus, increased LCN2 reduced autophagy flux. Moreover, RPE cells from cryba1 KO, as well as sting1 KO and Sting1Gt mutant mice (models with abnormal iron chelation), showed decreased autophagy flux and increased LCN2, indicative of CGAS- and STING1-mediated inflammasome activation. Live cell imaging of RPE cells with elevated LCN2 also showed a correlation between inflammasome activation and increased fluorescence intensity of the Liperfluo dye, indicative of oxidative stress-induced ferroptosis. Interestingly, both in human AMD patients and in mouse models with a dry AMD-like phenotype (cryba1 cKO and KO), the LCN2 homodimer variant is increased significantly compared to the monomer. Sub-retinal injection of the LCN2 homodimer secreted by RPE cells into NOD-SCID mice leads to retinal degeneration. In addition, we generated an LCN2 monoclonal antibody that neutralizes both the monomer and homodimer variants and rescued autophagy and ferroptosis activities in cryba1 cKO mice. Furthermore, the antibody rescued retinal function in cryba1 cKO mice as assessed by electroretinography. Here, we identify a molecular pathway whereby increased LCN2 elicits pathophysiology in the RPE, cells known to drive dry AMD pathology, thus providing a possible therapeutic strategy for a disease with no current treatment options.Abbreviations: ACTB: actin, beta; Ad-GFP: adenovirus-green fluorescent protein; Ad-LCN2: adenovirus-lipocalin 2; Ad-LCN2-GFP: adenovirus-LCN2-green fluorescent protein; LCN2AKT2: AKT serine/threonine kinase 2; AMBRA1: autophagy and beclin 1 regulator 1; AMD: age-related macular degeneration; ARPE19: adult retinal pigment epithelial cell line-19; Asp278: aspartate 278; ATG4B: autophagy related 4B cysteine peptidase; ATG4C: autophagy related 4C cysteine peptidase; ATG7: autophagy related 7; ATG9B: autophagy related 9B; BLOC-1: biogenesis of lysosomal organelles complex 1; BLOC1S1: biogenesis of lysosomal organelles complex 1 subunit 1; C57BL/6J: C57 black 6J; CGAS: cyclic GMP-AMP synthase; ChQ: chloroquine; cKO: conditional knockout; Cys74: cysteine 74; Dab2: DAB adaptor protein 2; Def: deferoxamine; DHE: dihydroethidium; DMSO: dimethyl sulfoxide; ERG: electroretinography; FAC: ferric ammonium citrate; Fe2+: ferrous; FTH1: ferritin heavy chain 1; GPX: glutathione peroxidase; GST: glutathione S-transferase; H2O2: hydrogen peroxide; His280: histidine 280; IFNL/IFNλ: interferon lambda; IL1B/IL-1β: interleukin 1 beta; IS: Inner segment; ITGB1/integrin β1: integrin subunit beta 1; KO: knockout; LC3-GST: microtubule associated protein 1 light chain 3-GST; C-terminal fusion; MAP1LC3/LC3: microtubule associated protein 1 light chain 3; LCN2: lipocalin 2; mAb: monoclonal antibody; MDA: malondialdehyde; MMP9: matrix metallopeptidase 9; NLRP3: NLR family pyrin domain containing 3; NOD-SCID: nonobese diabetic-severe combined immunodeficiency; OS: outer segment; PBS: phosphate-buffered saline; PMEL/PMEL17: premelanosome protein; RFP: red fluorescent protein; rLCN2: recombinant LCN2; ROS: reactive oxygen species; RPE SM: retinal pigmented epithelium spent medium; RPE: retinal pigment epithelium; RSL3: RAS-selective lethal; scRNAseq: single-cell ribonucleic acid sequencing; SD-OCT: spectral domain optical coherence tomography; shRNA: small hairpin ribonucleic acid; SM: spent medium; SOD1: superoxide dismutase 1; SQSTM1/p62: sequestosome 1; STAT1: signal transducer and activator of transcription 1; STING1: stimulator of interferon response cGAMP interactor 1; TYR: tyrosinase; VCL: vinculin; WT: wild type.

The Impacts of Iron Overload and Ferroptosis on Intestinal Mucosal Homeostasis and Inflammation

Intestinal homeostasis is maintained through the interplay of the intestinal mucosa, local and systemic immune factors, and the microbial content of the gut. Iron is a trace mineral in most organisms, including humans, which is essential for growth, systemic metabolism and immune response. Paradoxically, excessive iron intake and/or high iron status can be detrimental to iron metabolism in the intestine and lead to iron overload and ferroptosis-programmed cell death mediated by iron-dependent lipid peroxidation within cell membranes, which contributes to several intestinal diseases. In this review, we comprehensively review recent findings on the impacts of iron overload and ferroptosis on intestinal mucosal homeostasis and inflammation and then present the progress of iron overload and ferroptosis-targeting therapy in intestinal diseases. Understanding the involved mechanisms can provide a new understanding of intestinal disease pathogenesis and facilitate advanced preventive and therapeutic strategies for intestinal dysfunction and diseases.

Oxidative degradation of dihydrofolate reductase increases CD38-mediated ferroptosis susceptibility

High expression of CD38 in tissues is a characteristic of aging, resulting in a decline in nicotinamide adenine dinucleotide (NAD) and increasing cellular reactive oxygen species (ROS). However, whether CD38 increases susceptibility to ferroptosis remains largely unexplored. Our previous study showed that CD38 overexpression decreased dihydrofolate reductase (DHFR). In the present study, we confirmed that high expression of CD38 increased ROS levels and induced DHFR degradation, which was prevented by nicotinamide mononucleotide (NMN) replenishment. We further revealed that ROS-mediated sulfonation on Cys7 of DHFR induced its degradation via the autophagy and non-canonical proteasome pathways. Mutation of Cys7 to alanine abolished ROS-induced DHFR degradation. Moreover, oxidative degradation of DHFR was responsible for the increased ferroptosis susceptibility of cells in which CD38 was highly expressed. We also found that CD38 expression was higher in bone-marrow-derived macrophages (BMDMs) from aged mice than those from young mice, while the DHFR level was lower. Consequently, we demonstrated that BMDMs from aged mice were more susceptible to ferroptosis that can be reverted by NMN replenishment, suggesting that CD38 high expression rendered cells more susceptible to ferroptosis. Taken together, these results indicated that CD38-mediated NAD⁺ decline promoted DHFR oxidative degradation, thus resulting in increased cellular susceptibility to ferroptosis and suggesting that NMN replenishment may protect macrophages from ferroptosis in aged mice.

Nutritional components as mitigators of cellular senescence in organismal aging: a comprehensive review

The process of cellular senescence is rapidly emerging as a modulator of organismal aging and disease. Targeting the development and removal of senescent cells is considered a viable approach to achieving improved organismal healthspan and lifespan. Nutrition and health are intimately linked and an appropriate dietary regimen can greatly impact organismal response to stress and diseases including during aging. With a renewed focus on cellular senescence, emerging studies demonstrate that both primary and secondary nutritional elements such as carbohydrates, proteins, fatty acids, vitamins, minerals, polyphenols, and probiotics can influence multiple aspects of cellular senescence. The present review describes the recent molecular aspects of cellular senescence-mediated understanding of aging and then studies available evidence of the cellular senescence modulatory attributes of major and minor dietary elements. Underlying pathways and future research directions are deliberated to promote a nutrition-centric approach for targeting cellular senescence and thus improving human health and longevity.

Age-Related Lysosomal Dysfunctions

Organismal aging is normally accompanied by an increase in the number of senescent cells, growth-arrested metabolic active cells that affect normal tissue function. These cells present a series of characteristics that have been studied over the last few decades. The damage in cellular organelles disbalances the cellular homeostatic processes, altering the behavior of these cells. Lysosomal dysfunction is emerging as an important factor that could regulate the production of inflammatory molecules, metabolic cellular state, or mitochondrial function.

Glycolysis-Related LINC02432/Hsa-miR-98–5p/HK2 Axis Inhibits Ferroptosis and Predicts Immune Infiltration, Tumor Mutation Burden, and Drug Sensitivity in Pancreatic Adenocarcinoma

Pancreatic adenocarcinoma (PAAD) is a malignant cancer with high incidence and mortality. Glycometabolic rearrangements (aerobic glycolysis) is a hallmark of PAAD and contributes to tumorigenesis and progression through numerous mechanisms. This study aimed to identify a novel glycolysis-related lncRNA-miRNA-mRNA ceRNA signature in PAAD and explore its potential molecular function. We first calculated the glycolysis score for each PAAD patient by the ssGSEA algorithm and found that patients with higher hallmark glycolysis scores had poorer prognosis. Subsequently, we obtained a novel glycolysis-related LINC02432/hsa-miR-98–5p/HK2 axis from the TCGA and GEO databases using comprehensive bioinformatics analysis and developed a nomogram to predict overall survival. Furthermore, functional characterization analysis revealed that LINC02432/hsa-miR-98–5p/HK2 axis risk score was negatively correlated with ferroptosis. The tumor immune infiltration analysis suggested positive correlations between ceRNA risk score and infiltrated M0 macrophage levels in PAAD. Correlation analysis found that ceRNA risk scores were positively correlated with four chemokines (CXCL3, CXCL5, CXCL8 and CCL20) and one immune checkpoint gene (SIGLEC15). Meanwhile, tumor mutation burden (TMB), an indicator for predicting response to immunotherapy, was positively correlated with ceRNA risk score. Finally, the drug sensitivity analysis showed that the high-risk score patients might be more sensitive to EGFR, MEK and ERK inhibitors than low-risk score patients. In conclusion, our study suggested that LINC02432/hsa-miR-98–5p/HK2 axis may serve as a novel diagnostic, prognostic, and therapeutic target in PAAD treatment.

Hydrogen Sulfide Biology and Its Role in Cancer

Hydrogen sulfide (H2S) is an endogenous biologically active gas produced in mammalian tissues. It plays a very critical role in many pathophysiological processes in the body. It can be endogenously produced through many enzymes analogous to the cysteine family, while the exogenous source may involve inorganic sulfide salts. H2S has recently been well investigated with regard to the onset of various carcinogenic diseases such as lung, breast, ovaries, colon cancer, and neurodegenerative disorders. H2S is considered an oncogenic gas, and a potential therapeutic target for treating and diagnosing cancers, due to its role in mediating the development of tumorigenesis. Here in this review, an in-detail up-to-date explanation of the potential role of H2S in different malignancies has been reported. The study summarizes the synthesis of H2S, its roles, signaling routes, expressions, and H2S release in various malignancies. Considering the critical importance of this active biological molecule, we believe this review in this esteemed journal will highlight the oncogenic role of H2S in the scientific community.

Cerebral Iron Deposition in Neurodegeneration

Disruption of cerebral iron regulation appears to have a role in aging and in the pathogenesis of various neurodegenerative disorders. Possible unfavorable impacts of iron accumulation include reactive oxygen species generation, induction of ferroptosis, and acceleration of inflammatory changes. Whole-brain iron-sensitive magnetic resonance imaging (MRI) techniques allow the examination of macroscopic patterns of brain iron deposits in vivo, while modern analytical methods ex vivo enable the determination of metal-specific content inside individual cell-types, sometimes also within specific cellular compartments. The present review summarizes the whole brain, cellular, and subcellular patterns of iron accumulation in neurodegenerative diseases of genetic and sporadic origin. We also provide an update on mechanisms, biomarkers, and effects of brain iron accumulation in these disorders, focusing on recent publications. In Parkinson’s disease, Friedreich’s disease, and several disorders within the neurodegeneration with brain iron accumulation group, there is a focal siderosis, typically in regions with the most pronounced neuropathological changes. The second group of disorders including multiple sclerosis, Alzheimer’s disease, and amyotrophic lateral sclerosis shows iron accumulation in the globus pallidus, caudate, and putamen, and in specific cortical regions. Yet, other disorders such as aceruloplasminemia, neuroferritinopathy, or Wilson disease manifest with diffuse iron accumulation in the deep gray matter in a pattern comparable to or even more extensive than that observed during normal aging. On the microscopic level, brain iron deposits are present mostly in dystrophic microglia variably accompanied by iron-laden macrophages and in astrocytes, implicating a role of inflammatory changes and blood–brain barrier disturbance in iron accumulation. Options and potential benefits of iron reducing strategies in neurodegeneration are discussed. Future research investigating whether genetic predispositions play a role in brain Fe accumulation is necessary. If confirmed, the prevention of further brain Fe uptake in individuals at risk may be key for preventing neurodegenerative disorders.

The Selenoprotein Glutathione Peroxidase 4: From Molecular Mechanisms to Novel Therapeutic Opportunities

The selenoprotein glutathione peroxidase 4 (GPX4) is one of the main antioxidant mediators in the human body. Its central function involves the reduction of complex hydroperoxides into their respective alcohols often using reduced Glutathione (GSH) as a reducing agent. GPX4 has become a hotspot therapeutic target in biomedical research following its characterization as a chief regulator of ferroptosis, and its subsequent recognition as a specific pharmacological target for the treatment of an extensive variety of human diseases including cancers and neurodegenerative disorders. Several recent studies have provided insights into how GPX4 is distinguished from the rest of the glutathione peroxidase family, the unique biochemical properties of GPX4, how GPX4 is related to lipid peroxidation and ferroptosis, and how the enzyme may be modulated as a potential therapeutic target. This current report aims to review the literature underlying all these insights and present an up-to-date perspective on the current understanding of GPX4 as a potential therapeutic target.

Ferroptosis and Its Potential Role in the Nervous System Diseases

Ferroptosis is a novel regulated cell death characterized by metabolic disorders and iron-dependent oxidative destruction of the lipid bilayer. It is primarily caused by the imbalance of oxidation and anti-oxidation in the body and is precisely regulated by numerous factors and pathways inside and outside the cell. Recent studies have indicated that ferroptosis plays a vital role in the pathophysiological process of multiple systems of the body including the nervous system. Ferroptosis may be closely linked to the occurrence and development of neurodegenerative diseases, strokes, and brain tumors. It may also be involved in the development, maturation, and aging of the nervous system. Therefore, this study aims to investigate ferroptosis’s occurrence and regulatory mechanism and summarize its research progress in the pathogenesis and treatment of neurological diseases. This would allow for novel ideas for basic and clinical research of neurological diseases.

Ferroptosis and Its Potential Role in Lung Cancer: Updated Evidence from Pathogenesis to Therapy

Lung cancer is characterized by high morbidity and mortality rates, and its occurrence is associated with many types of cell death. As a new form of regulated cell death, ferroptosis is an iron- dependent pattern of cell death and characterized by lethal accumulation of lipid-based reactive oxygen species (ROS), which is different from apoptosis, necrosis and autophagy at both the morphological and biochemical levels. It plays an important role in the development of lung cancer and induction of ferroptosis in lung cancer cells has become a new strategy for anti- lung cancer treatment. However, a few reviews summarized ferroptosis and its role in lung cancer has not been elucidated, and the precise mechanism of ferroptosis modeling lung cancer has not yet been revealed till date. Herein, we review the latest literature on the process of ferroptosis regarding lung cancer, including basic molecular or biology mechanistic studies both in vivo and in vitro, as well as human studies with a more translational or clinical approach. This review provides a practical, concise and updated outline on the mechanisms and therapeutic strategies in lung cancer with ferroptosis alterations. Looking ahead, further studies are required to uncover the possible modulatory relationship between ferroptosis and lung cancer.

Attenuated initial serum ferritin concentration in critically ill coronavirus disease 2019 geriatric patients with comorbid psychiatric conditions

We examined the effects of psychiatric comorbidity, sex, and ICU admission on serum ferritin concentration in 628 elderly patients (79.7 ± 8.5 years) with positive SARS-CoV-2 PCR test. Hospitalization was required in 96% of patients and 17% required ICU admission. Patients with COVID-19 and psychiatric comorbidities (n = 212) compared to patients without psychiatric comorbidities (n = 416) had significantly lower ferritin concentration (570.4 ± 900.1 vs. 744.1 ± 965, P = 0.029), a greater incidence of delirium (22.6 vs. 14.4%, P = 0.013) and higher mortality (35.3 vs. 27.6%, P = 0.015). Furthermore, we found significant effects for sex (P = 0.002) and ICU admission (P = 0.007). Among patients without comorbid psychiatric conditions, males had significantly higher ferritin compared to females (1,098.3 ± 78.4 vs. 651.5 ± 94.4, P < 0.001). ICU patients without comorbid psychiatric conditions had significantly higher serum ferritin compared to ICU patients with comorbid psychiatric conditions: (1,126.6 ± 110.7 vs. 668.6 ± 156.5, P < 0.001). Our results suggest that the presence of comorbid psychiatric conditions in elderly patients with COVID-19 is associated with higher rates of delirium and mortality and lower ferritin levels during severe illness. Whether high serum ferritin is protective during severe infection requires further investigation.

Ferroptosis Mechanisms Involved in Hippocampal-Related Diseases

Ferroptosis is a newly recognized type of cell death that is different from traditional forms of cell death, such as apoptosis, autophagy, and necrosis. It is caused by the accumulation of intracellular iron, promoting lipid peroxidation and leading to cell death. Iron is essential as a redox metal in several physiological functions. The brain is one of the organs known to be affected by iron homeostatic balance disruption. An increased concentration of iron in the central nervous system has been associated with oxidative stress, lipid peroxidation of proteins, and cell death. The hippocampus is an important brain region for learning, memory, and emotional responses, and is also a sensitive part of the brain to the dysfunctional homeostasis of transition metals. Damage of hippocampal structure and function are intimately involved in the pathogenic mechanisms underlying neurodegenerative diseases. Currently, ferroptosis is playing an increasingly important role in treatment areas of central nervous system diseases. Thus, we provide an overview of ferroptosis regulatory mechanisms, such as lipid metabolism, glutathione metabolism, and iron metabolism in this review. We also highlight the role of ferroptosis in hippocampal-related diseases and investigate a theoretical basis for further research on the role of ferroptosis in nervous system disease treatment.