Spermidine, a caloric restriction mimetic, provides neuroprotection against normal and D-galactose-induced oxidative stress and apoptosis through activation of autophagy in male rats during aging

Curcumin protects against aging-related stress and dysfunction through autophagy activation in rat brain

BACKGROUND

Curcumin (Curcuma longa) is a well-known medicinal plant that induces autophagy in various model species, helping maintain cellular homeostasis. Its role as a caloric restriction mimetic (CRM) is being investigated. This study explores the potential of curcumin (CUR), as a CRM, to provide neuroprotection in D galactose induced accelerated senescence model of rats through modulation of autophagy. For six weeks, male rats received simultaneous supplementation of D-gal (300 mg/kg b.w., subcutaneously) and CUR (200 mg/kg b.w., oral).

METHOD AND RESULTS

The oxidative stress indices, antioxidants, and electron transport chain complexes in brain tissues were measured using standard methods. Reverse transcriptase-polymerase chain reaction (RT-PCR) gene expression analysis was used to evaluate the expression of autophagy, neuroprotection, and aging marker genes. Our results show that curcumin significantly (p ≤ 0.05) enhanced the level of antioxidants and considerably lowered the level of oxidative stress markers. Supplementing with CUR also increased the activity of electron transport chain complexes in the mitochondria of aged brain tissue, demonstrating the antioxidant potential of CUR at the mitochondrial level. CUR was found to upregulate the expression of the aging marker gene (SIRT-1) and the genes associated with autophagy (Beclin-1 and ULK-1), as well as neuroprotection (NSE) in the brain. The expression of IL-6 and TNF-α was downregulated.

CONCLUSION

Our findings demonstrate that CUR suppresses oxidative damage brought on by aging by modulating autophagy. These findings imply that curcumin might be beneficial for neuroprotection in aging and age-related disorders.

Vitamin D Protects Against Cardiac Hypertrophy Through the Regulation of Mitochondrial Function in Aging Rats

Cardiac aging is defined as mitochondrial dysfunction of the heart. Vitamin D (VitD) is an effective agent in ameliorating cardiovascular disorders. In this study, we indicated the protective effects of VitD against cardiac aging. Male Wistar rats were randomly divided into four groups: control (CONT), D-galactose (D-GAL): aged rats induced by D-GAL, D-GAL + Ethanol: aged rats treated with ethanol, and D-GAL + VitD aged rats treated with VitD. Aging was induced by D-GAL at 150 mg/kg via intraperitoneal injection for 8 weeks. Aged rats were treated with VitD (D-GAL + VitD) by gavage for 8 weeks. The serum samples were used to evaluate biochemical factors, and heart tissues were assessed to determine oxidative stress and gene expression. The D-GAL rats exhibited cardiac hypertrophy, which was associated with decreased antioxidant enzyme activity, enhanced oxidative marker, and changes in the expression of mitochondrial genes in comparison with the control rats. Co-treatment with VitD ameliorated all these changes. In conclusion, VitD could protect the heart against D-GAL-induced aging via enhancing antioxidant effects, and the expression of mitochondrial genes.

Possible Role of Cellular Polyamine Metabolism in Neuronal Apoptosis

Recent studies have shown that cellular levels of polyamines (PAs) are significantly altered in neurodegenerative diseases. Evidence from in vivo animal and in vitro cell experiments suggests that the cellular levels of various PAs may play important roles in the central nervous system through the regulation of oxidative stress, mitochondrial metabolism, cellular immunity, and ion channel functions. Dysfunction of PA metabolism related enzymes also contributes to neuronal injury and cognitive impairment in many neurodegenerative diseases. Therefore, in the current work, evidence was collected to determine the possible associations between cellular levels of PAs, and related enzymes and the development of several neurodegenerative diseases, which could provide a new idea for the treatment of neurodegenerative diseases in the future.

Analysis of cerebrospinal fluid metabolites affected by WenDanTang based on ultra-high-performance liquid chromatography coupled with high-resolution mass spectrometry

WenDanTang (WDT) is a Chinese herbal formula used to treat various diseases, including neurodegenerative diseases. However, the neuroprotective metabolic pathways and the components involved in this process are not fully understood. In this study, we examined the neuroprotective metabolic pathways of WDT in rat brains using cerebrospinal fluid metabolomics and ultra-high-performance liquid chromatography-high-resolution mass spectrometry. Twelve rats were randomly divided into a WDT (administrated with WDT solution) and a control group. The ultra-high-performance liquid chromatography technique was used to explore the components of the WDT solution and cerebrospinal fluid, and secondary mass spectra of cerebrospinal fluid were used to identify possible brain-incorporating components after WDT. The results of the differential metabolism analysis showed that eight metabolites were typically altered (all p < 0.05). By comparing the secondary mass spectra of the cerebrospinal fluid of rats and WDT solution, two possible brain-incorporating components of WDT, stachydrine and α-methoxyphenylacetic acid, were identified. The data also suggested that WDT affects nucleotide metabolism, glutathione metabolism, and B-vitamin metabolic pathways, the central differential metabolic pathways. These data suggest that WDT protects neurons through its active components, such as stachydrine, and regulates biochemical metabolism to affect the brain's energy metabolism and antioxidant capacity.

Long-term lifestyle intervention is superior to transient modification for neuroprotection in D-galactose-induced aging rats

AIMS

To investigate whether transient dietary restriction or aerobic exercise in young adulthood exert long-lasting protection against brain aging later in life.

MAIN METHODS

Seven-week-old male Wistar rats were divided into 2 groups and given either normal saline as a vehicle (n = 8) or 150 mg/kg/day of D-galactose (n = 40) for 28 weeks, the D-galactose being used to induce aging. At week 13 of the experiment, D-galactose-treated rats were further divided into 5 groups, 1) no intervention, 2) transient dietary restriction for 6 weeks (week 13-18), 3) transient exercise for 6 weeks (week 13-18), 4) long-term dietary restriction for 16 weeks (week 13-28), and 5) long-term exercise for 16 weeks (week 13-28). At the end of week 28, cognitive function was examined, followed by molecular studies in the hippocampus.

KEY FINDINGS

Our results showed that either long-term dietary restriction or aerobic exercise effectively attenuated cognitive function in D-galactose-treated rats via the attenuation of oxidative stress, cellular senescence, Alzheimer's-like pathology, neuroinflammation, and improvements in mitochondria, brain metabolism, adult neurogenesis, and synaptic integrity. Although transient interventions provided benefits in some brain parameters in D-galactose-treated rats, an improvement in cognitive function was not observed.

SIGNIFICANCE

Our findings suggested that transient lifestyle interventions failed to exert a long-lasting protective effect against brain aging. Hence, novel drugs mimicking the neuroprotective effect of long-term dietary restriction or exercise and the combination of the two since young age appear to be more appropriate treatments for the elderly who are unable to engage in long-term dietary restriction or exercise.

Molecular aspects of optic nerve autophagy in glaucoma

The optic nerve consists of the glia, vessels, and axons including myelin and axoplasm. Since axonal degeneration precedes retinal ganglion cell death in glaucoma, the preceding axonal degeneration model may be helpful for understanding the molecular mechanisms of optic nerve degeneration. Optic nerve samples from these models can provide information on several aspects of autophagy. Autophagosomes, the most typical organelles expressing autophagy, are found much more frequently inside axons than around the glia. Thus, immunoblot findings from the optic nerve can reflect the autophagy state in axons. Autophagic flux impairment may occur in degenerating optic nerve axons, as in other central nervous system neurodegenerative diseases. Several molecular candidates are involved in autophagy enhancement, leading to axonal protection. This concept is an attractive approach to the prevention of further retinal ganglion cell death. In this review, we describe the factors affecting autophagy, including nicotinamide riboside, p38, ULK, AMPK, ROCK, and SIRT1, in the optic nerve and propose potential methods of axonal protection via enhancement of autophagy.

Spermidine suppresses oxidative stress and ferroptosis by Nrf2/HO-1/GPX4 and Akt/FHC/ACSL4 pathway to alleviate ovarian damage

AIMS

Oxidative stress is considered to be one of the culprits of ovarian dysfunction. Spermidine (SPD) is a natural aliphatic polyamine that is widely present in living organisms and has been shown to exert preventive effects on various ageing-related diseases. This study seeks to investigate the potential preventive and protective effects of SPD on ovarian oxidative damage.

MAIN METHODS

Ovarian oxidative stress model in C57BL/6 mice was established by 3-nitropropionic acid. Female mice were administrated 10 mg/kg or 15 mg/kg SPD. The estrous cycle, serum hormone levels and mating test were measured to evaluate ovarian function. Follicle counts and AMH levels to assess ovarian reserve. Masson's trichrome to assess ovarian fibrosis. TUNEL analysis to evaluate follicular granulosa cells (GCs) apoptosis. Oxidative stress and autophagy indicators (Nrf2, HO-1, GPX4, LC3B, P62) were measured in vivo and in vitro. RNA-sequencing was performed on SPD-treated GC to study the effects of SPD on Akt and FHC/ACSL4 signaling.

KEY FINDINGS

SPD supplementation improved ovarian endocrine function and reproductive capacity in oxidative stress mice. SPD regularized the estrous cycle and alleviated oxidative stress. Furthermore, SPD increased the ovarian reserve, reducing GC apoptosis by activating the Nrf2/HO-1/GPX4 pathway. RNA-sequencing showed that SPD induced 230 genes changes in porcine GC, which were mainly involved in oocyte meiosis, arginine biosynthesis and glutathione metabolism pathways. SPD attenuated H2O2-induced ferroptosis by regulating Akt/FHC/ACSL4 signaling.

SIGNIFICANCE

SPD alleviates oxidative stress and ferroptosis by regulating the Nrf2/HO-1/GPX4 and Akt/FHC/ACSL4 pathway, which may be a novel potential strategy to protect ovarian oxidative damage.

Molecular mechanism of caloric restriction mimetics-mediated neuroprotection of age-related neurodegenerative diseases: an emerging therapeutic approach

Aging-induced neurodegenerative diseases (NDs) are significantly increasing health problem worldwide. It has been well documented that oxidative stress is one of the potential causes of aging and age-related NDs. There are no drugs for the treatment of NDs, therefore there is an immediate necessity for the development of strategies/treatments either to prevent or cure age-related NDs. Caloric restriction (CR) and intermittent fasting have been considered as effective strategies in increasing the healthspan and lifespan, but it is difficult to adhere to these routines strictly, which has led to the development of calorie restriction mimetics (CRMs). CRMs are natural compounds that provide similar molecular and biochemical effects of CR, and activate autophagy process. CRMs have been reported to regulate redox signaling by enhancing the antioxidant defense systems through activation of the Nrf2 pathway, and inhibiting ROS generation through attenuation of mitochondrial dysfunction. Moreover, CRMs also regulate redox-sensitive signaling pathways such as the PI3K/Akt and MAPK pathways to promote neuronal cell survival. Here, we discuss the neuroprotective effects of various CRMs at molecular and cellular levels during aging of the brain. The CRMs are envisaged to become a cornerstone of the pharmaceutical arsenal against aging and age-related pathologies.

Spermidine alleviating oxidative stress and apoptosis by inducing autophagy of granulosa cells in Sichuan white geese

Spermidine have been reported a role in antioxidative, antiaging, and antiinflammatory. Oxidative stress causes granulosa cell (GC) apoptosis, follicular atresia, and impairs poultry reproductive functions. Studies have found that autophagy is the protective mechanism against antioxidant stress and apoptosis in cells. However, the relationship between spermidine-induced autophagy, oxidative stress, and apoptosis in goose GCs remains unclear. In this study, we investigated the autophagy mechanism to mediate spermidine effects on the alleviation of oxidative stress and apoptosis in goose GCs. Follicular GCs were treated with spermidine combination with 3-Nitropropanoic acid (3-NPA), rapamycin (RAPA), and chloroquine (CQ) or with hydrogen peroxide, RAPA, and CQ. Spermidine upregulated the ratio of LC3-II/I, inhibited the accumulation of p62 protein, and induced autophagy. 3-NPA treatment significantly increased ROS production, MDA content, SOD activity, cleaved CASPASE-3 protein expression, and decreased BCL-2 protein expression in follicular GCs. Spermidine inhibited oxidative stress and apoptosis induced by 3-NPA. In addition, hydrogen peroxide-induced oxidative stress was inhibited by spermidine. However, the inhibitory effect of spermidine was eliminated under chloroquine. Our results demonstrated that spermidine relieved oxidative stress and apoptosis of GCs by inducing autophagy, indicating that spermidine has a great potential to maintain proteostasis and sustain granulosa cell viability in geese.

Mitigation of behavioral deficits and cognitive impairment by antioxidant and neuromodulatory potential of Mukia madrespatana in D-galactose treated rats

Plants and their parts have been extensively used for the therapeutic purposes such as aging due to their powerful antioxidative belongings. Presently, we intended to examine the consequence of fruit peel of Mukia madrespatana (M.M) on D-galactose (D-Gal) persuaded anxiety and/or depression profile, cognition and serotonin metabolism in rats. Animals were divided in to 4 groups (n = 6). (i) Water treated (ii) D-Gal treated (iii) M.M. treated (iv) D-Gal + M.M. treated. All the animals received their respective treatment for 4 weeks. D-Gal and M.M. fruit peel were given to animals with oral gavage with doses 300 mg/ml/kg/day and 2 g/kg/day respectively. After 4 weeks' behavioral analysis performed to evaluate anxiety and depression profile, cognitive function of animals. After that animals were sacrificed and whole brain removed for biochemical (redox status, degradative enzyme of acetylcholine), and neurochemical (serotonin metabolism) analysis. Results showed that administration of M.M. inhibited D-Gal-instigated anxious and depressive behaviors and improved cognition. Treatment of M.M. decreased MDA levels, AChE activity and increased antioxidant enzyme activity in D-Gal administered and control rats. Enhanced serotonin metabolism also decreased by M.M. in control and D-Gal administered rats. In conclusion, M.M. fruit peel has powerful antioxidative and neuromodulatory properties and due to this effect, it may be a good source of mitigation/treatment for aging induced behavioral and cognitive impairment.

Berberine may provide redox homeostasis during aging in rats

Aging is a natural phenomenon, which is characterised by progressive physiological changes at cellular and organ level. During aging, the defence mechanism of an organism declines over the period of time. The aim of this study was to investigate the biological efficacy of berberine in D-galactose induced aging rat models. For the study, rats were divided into four groups: Control received only vehicle, BBR received berberine orally, D-Gal received D-galactose subcutaneously and BBR + D-Gal received D-galactose and berberine simultaneously. D-galactose treatment increased the pro-oxidants such as malondialdehyde (MDA) level, protein carbonyl, plasma membrane redox system (PMRS) and advanced oxidation protein products (AOPP) in the erythrocytes or plasma. It reduced the anti-oxidant level such as reduced glutathione (GSH), ferric reducing ability of plasma (FRAP), plasma thiols, sialic acid and membrane transporters like Na+/K+ ATPase and Ca2+ ATPase activity in the erythrocyte membrane. Co-treatment of berberine in D-galactose induced aging rat models restored pro-oxidants and anti-oxidants in erythrocytes. Berberine also restored the activity of Na+/K+ ATPase and Ca2+ ATPase in the erythrocyte membrane. On the basis of these findings, we suggest that berberine treatment could attenuate erythrocyte aging in rats through stabilisation of the redox equilibrium.

Gut microbiota and anti-aging: Focusing on spermidine

The human gut microbiota plays numerous roles in regulating host growth, the immune system, and metabolism. Age-related changes in the gut environment lead to chronic inflammation, metabolic dysfunction, and illness, which in turn affect aging and increase the risk of neurodegenerative disorders. Local immunity is also affected by changes in the gut environment. Polyamines are crucial for cell development, proliferation, and tissue regeneration. They regulate enzyme activity, bind to and stabilize DNA and RNA, have antioxidative properties, and are necessary for the control of translation. All living organisms contain the natural polyamine spermidine, which has anti-inflammatory and antioxidant properties. It can regulate protein expression, prolong life, and improve mitochondrial metabolic activity and respiration. Spermidine levels experience an age-related decrease, and the development of age-related diseases is correlated with decreased endogenous spermidine concentrations. As more than just a consequence, this review explores the connection between polyamine metabolism and aging and identifies advantageous bacteria for anti-aging and metabolites they produce. Further research is being conducted on probiotics and prebiotics that support the uptake and ingestion of spermidine from food extracts or stimulate the production of polyamines by gut microbiota. This provides a successful strategy to increase spermidine levels.

Exploration of the Antioxidant Effect of Spermidine on the Ovary and Screening and Identification of Differentially Expressed Proteins

Spermidine is a naturally occurring polyamine compound that has many biological functions, such as inducing autophagy and anti-inflammatory and anti-aging effects. Spermidine can affect follicular development and thus protect ovarian function. In this study, ICR mice were fed exogenous spermidine drinking water for three months to explore the regulation of ovarian function by spermidine. The results showed that the number of atretic follicles in the ovaries of spermidine-treated mice was significantly lower than that in the control group. Antioxidant enzyme activities (SOD, CAT, T-AOC) significantly increased, and MDA levels significantly decreased. The expression of autophagy protein (Beclin 1 and microtubule-associated protein 1 light chain 3 LC3 II/I) significantly increased, and the expression of the polyubiquitin-binding protein p62/SQSTM 1 significantly decreased. Moreover, we found 424 differentially expressed proteins (DEPs) were upregulated, and 257 were downregulated using proteomic sequencing. Gene Ontology and KEGG analyses showed that these DEPs were mainly involved in lipid metabolism, oxidative metabolism and hormone production pathways. In conclusion, spermidine protects ovarian function by reducing the number of atresia follicles and regulating the level of autophagy protein, antioxidant enzyme activity, and polyamine metabolism in mice.

Protocatechuic Aldehyde Alleviates d -Galactose-Induced Cardiomyocyte Senescence by Regulating the TCF3/ATG5 Axis

ABSTRACT

Cardiomyocyte senescence is an independent risk factor for cardiovascular diseases. Protocatechuic aldehyde (PCA) is a natural chemical in the Chinese medicinal herb Salvia miltiorrhiza . PCA could protect against oxidative stress and inflammation in the cardiovascular system. In present study, we treated H9C2 cells with d -galactose to establish an in vitro model of cardiomyocyte senescence and investigated the role and underlying mechanisms of PCA in myocardial cell senescence. It was found that d -galactose induced transcription factor 3 (TCF3) expression and decreased autophagy-related genes 5 (ATG5) expression. Meanwhile, inflammation and senescence were exacerbated by d -galactose. TCF3 transcriptionally inhibited ATG5 expression. TCF3 knockdown abolished the effects of d -galactose on H9C2 by activating ATG5-mediated autophagy. PCA hindered TCF3 and inflammation to alleviate the d -galactose-induced senescence of H9C2 cells in a dose-dependent manner. Whereas, the anti-inflammation and anti-senescence effects of PCA were reversed by TCF3 knockdown. Furthermore, absence of ATG5 partially eliminated the impacts of PCA on H9C2 cells treated with d -galactose. Conclusively, PCA alleviated d -galactose-induced senescence by downregulating TCF3, promoting ATG5-mediated autophagy, and inhibiting inflammation in H9C2 cells. These results elucidated the potential mechanism by which PCA alleviated cardiomyocyte senescence and enabled its application in treating cardiomyocyte senescence.

Spermidine inhibits high glucose-induced endoplasmic reticulum stress in HT22 cells by upregulation of growth differentiation factor 11

Hyperglycemia-induced neuronal endoplasmic reticulum (ER) stress is particularly important for the pathogenesis of diabetic encephalopathy. Spermidine (Spd) has neuroprotection in several nervous system diseases. Our current study to explore the potential protective role of Spd in hyperglycemia-induced neuronal ER stress and the underlying mechanisms. HT22 cells were treated with high glucose (HG) to establish an in-vitro model of hyperglycemia toxicity. The HT22 cells' activity was tested by cell counting kit-8 assay. RNA interference technology was used to silence the expression of growth differentiation factor 11 (GDF11) in HT22 cells. The GDF11 expression levels of mRNA were assessed using reverse transcription-PCR (RT-PCR). Western blotting analysis was applied to evaluate the expressions of GRP78 and cleaved caspase-12. Spd markedly abolished HG-exerted decline in cell viability as well as upregulations of GRP78 and cleaved caspase-12 in HT22 cells, indicating the protection of Spd against HG-induced neurotoxicity and ER stress. Furthermore, we showed that Spd upregulated the expression of GDF11 in HG-exposed HT22 cells. While, silenced GDF11 expression by RNA interference reversed the protective effects of Spd on HG-elicited neurotoxicity and ER stress in HT22 cells. These results indicated that Spd prevents HG-induced neurotoxicity and ER stress through upregulation of GDF11. Our findings identify Spd as a potential treatment for diabetic encephalopathy as well as ER stress-related neurologic diseases.

Microbiome-metabolome analysis reveals alterations in the composition and metabolism of caecal microbiota and metabolites with dietary Enteromorpha polysaccharide and Yeast glycoprotein in chickens

The intestinal microbiome is responsible for the fermentation of complex carbohydrates and orchestrates the immune system through gut microbiota-derived metabolites. In our previous study, we reported that supplementation of Enteromorpha polysaccharide (EP) and yeast glycoprotein (YG) in combination synergistically improved antioxidant activities, serum lipid profile, and fatty acid metabolism in chicken. However, the mechanism of action of these polysaccharides remains elusive. The present study used an integrated 16S-rRNA sequencing technology and untargeted metabolomics technique to reveal the mechanism of action of EP+YG supplementation in broiler chickens fed basal diet or diets supplemented with EP+YG (200mg/kg EP + 200mg/kg YG). The results showed that EP+YG supplementation altered the overall structure of caecal microbiota as evidenced by β diversities analysis. Besides, EP+YG supplementation changed the microbiota composition by altering the community profile at the phylum and genus levels. Furthermore, Spearman correlation analysis indicated a significant correlation between altered microbiota genera vs serum cytokine levels and microbiota genera vs volatile fatty acids production. Predicted functional analysis showed that EP+YG supplementation significantly enriched amino acid metabolism, nucleotide metabolism, glycan biosynthesis and metabolism, energy metabolism, and carbohydrate metabolism. Metabolomics analysis confirmed that EP+YG supplementation modulates a myriad of caecal metabolites by increasing some metabolites, including pyruvic acid, pyridoxine, spermidine, spermine, and dopamine, and decreasing metabolites related to lipid metabolisms such as malonic acid, oleic acid, and docosahexaenoic acid. The quantitative enrichment analysis results further showed that glycolysis/gluconeogenesis, citric acid cycle, tyrosine metabolism, glycine, serine, and threonine metabolism, and cysteine and methionine metabolism were the most important enriched pathways identified with enrichment ratio >11, whereas, fatty acid biosynthesis and biosynthesis of unsaturated fatty acids pathways were suppressed. Together, the 16S-rRNA and untargeted metabolomics results uncovered that EP+YG supplementation modulates intestinal microbiota and their metabolites, thereby influencing the important metabolism pathways, suggesting a potential feed additive.

The Impact of Spermidine on C2C12 Myoblasts Proliferation, Redox Status and Polyamines Metabolism under H2O2 Exposure

A central feature of the skeletal muscle is its ability to regenerate through the activation, by environmental signals, of satellite cells. Once activated, these cells proliferate as myoblasts, and defects in this process profoundly affect the subsequent process of regeneration. High levels of reactive oxygen species such as hydrogen peroxide (H₂O₂) with the consequent formation of oxidized macromolecules increase myoblasts’ cell death and strongly contribute to the loss of myoblast function. Recently, particular interest has turned towards the beneficial effects on muscle of the naturally occurring polyamine spermidine (Spd). In this work, we tested the hypothesis that Spd, upon oxidative challenge, would restore the compromised myoblasts’ viability and redox status. The effects of Spd in combination with aminoguanidine (Spd-AG), an inhibitor of bovine serum amine oxidase, on murine C2C12 myoblasts treated with a mild dose of H₂O₂ were evaluated by analyzing: (i) myoblast viability and recovery from wound scratch; (ii) redox status and (iii) polyamine (PAs) metabolism. The treatment of C2C12 myoblasts with Spd-AG increased cell number and accelerated scratch wound closure, while H₂O₂ exposure caused redox status imbalance and cell death. The combined treatment with Spd-AG showed an antioxidant effect on C2C12 myoblasts, partially restoring cellular total antioxidant capacity, reducing the oxidized glutathione (GSH/GSSG) ratio and increasing cell viability through a reduction in cell death. Moreover, Spd-AG administration counteracted the induction of polyamine catabolic genes and PA content decreased due to H₂O₂ challenges. In conclusion, our data suggest that Spd treatment has a protective role in skeletal muscle cells by restoring redox balance and promoting recovery from wound scratches, thus making myoblasts able to better cope with an oxidative insult.

Highly efficient biosynthesis of spermidine from L-homoserine and putrescine using an engineered Escherichia coli with NADPH self-sufficient system

Spermidine is an important polyamine that can be used for the synthesis of various bioactive compounds in the food and pharmaceutical fields. In this study, a novel efficient whole-cell biocatalytic method with an NADPH self-sufficient cycle for spermidine biosynthesis was designed and constructed by co-expressing homoserine dehydrogenase (HSD), carboxyspermidine dehydrogenase (CASDH), and carboxyspermidine decarboxylase (CASDC). First, the enzyme-substrate coupled cofactor regeneration system from co-expression of NADP⁺-dependent ScHSD and NADPH-dependent AfCASDH exactly provides an efficient method for cofactor cycling. Second, we identified and characterized a putative CASDC with high decarboxylase activity from Butyrivibrio crossotus DSM 2876; it showed an optimum temperature of 35 °C and an optimum pH of 7.0, which make it better suited for the designed synthetic route. Subsequently, the protein expression level of each enzyme was optimized through the variation of the gene copy number, and a whole-cell catalyst with high catalytic efficiency was constructed successfully. Finally, a yield of 28.6 mM of spermidine was produced in a 1-L scale of E. coli whole-cell catalytic system with a 95.3% molar conversion rate after optimization of temperature, the ratio of catalyst-to-substrate, and the amount of NADP⁺, and a productivity of 0.17 g·L^-1·h^-1 was achieved. In summary, this novel pathway of constructing a whole-cell catalytic system from L-homoserine and putrescine could provide a green alternative method for the efficient synthesis of spermidine. KEY POINTS: • A novel pathway for spermidine biosynthesis was developed in Escherichia coli. • The enzyme-substrate coupled system provides an NADPH self-sufficient cycle. • Spermidine with 28.6 mM was obtained using an optimized whole-cell system.

γ-Glutamylcysteine ameliorates D-gal-induced senescence in PC12 cells and mice via activating AMPK and SIRT1

Aging is a natural process accompanied by inflammation and oxidative stress and is closely associated with age-related diseases. As a direct precursor of glutathione, γ-glutamylcysteine (γ-GC) possesses antioxidant and anti-inflammatory properties; however, whether γ-GC plays an important role in anti-aging remains unknown. Here, we investigated the protective effects and mechanisms of γ-GC in D-galactose (D-gal)-induced senescence in PC12 cells and aging mice. Our results showed that γ-GC treatment significantly reduced the percentage of senescence-associated-β-galactosidase (SA-β-Gal)-positive cells and inhibited D-gal-induced cell cycle arrest in PC12 cells. The results of Nissl and hematoxylin and eosin (H&E) staining in mouse brain showed that γ-GC treatment markedly reversed the damage in the hippocampus of D-gal-induced aging mice. Moreover, γ-GC increased the phosphorylation of AMP-activated protein kinase (AMPK) to promote the nuclear translocation of glyceraldehyde-3-phosphate dehydrogenase (GAPDH) while inhibiting the nuclear translocation of deleted in breast cancer 1 (DBC1), which leads to the activation of sirtuin 1 (SIRT1) and deacetylation of p53 in the nucleus. Therefore, γ-GC may be a potential therapeutic candidate compound for the prevention and treatment of age-related diseases.

A Dietary Supplement Containing Micronutrients, Phosphatidylserine, and Docosahexaenoic Acid Counteracts Cognitive Impairment in D-Galactose-Induced Aged Rats

At present, it is a trend to use dietary supplements to prevent age-related cognitive impairment. This study aimed to investigate the effects of a dietary supplement enriched with micronutrients, phosphatidylserine, and docosahexaenoic acid on cognitive performance using a D-galactose (D-gal) induced aging rat model. Seven-month-old male Sprague-Dawley rats were randomly divided into five groups, including the control group, D-gal model group, and low-dose (2 g/kg body weight), medium-dose (6 g/kg body weight), and high-dose (10 g/kg body weight) dietary supplement intervention groups, which were investigated for 13 weeks. The dietary supplement intervention was found to improve cognitive performance in Morris water maze test, increase superoxidase dismutase activity, reduce malondialdehyde activity, decrease tumor necrosis factor-α and interleukin-6 concentrations, inhibit the activation of astrocytes, and elevate brain-derived neurotrophic factor protein and mRNA expression in the brains of D-gal-induced aged rats. This dietary supplement customized for the aged can be applied to the restoration of cognitive performance by enhancing antioxidant and anti-neuroinflammatory abilities, up-regulating neurotrophic factors, and inhibiting the activation of astrocytes. These results will be useful for future studies focused on implementation in humans.

Effect of Serum Spermidine on the Prognosis in Patients with Acute Myocardial Infarction: A Cohort Study

Background: Spermidine, a natural polyamine, was found critically involved in cardioprotection and lifespan extension from both animal experiments and human studies. Aims: This study aimed to evaluate the effect of serum spermidine levels on the prognosis in patients with acute myocardial infarction (AMI) and investigate the potential mediation effect of oxidative stress in the above relationship. Methods: We included 377 patients with AMI in a prospective cohort study and measured serum spermidine and oxidative stress indexes (superoxide dismutase enzymes, glutathione peroxidase, and Malondialdehyde) using high-performance liquid chromatography with fluorescence detector and enzyme-linked immunosorbent assay, respectively. The associations of spermidine with AMI outcomes were evaluated using Cox proportional hazards models. Results: 84 (22.3%) major adverse cardiac events (MACE) were documented during a mean follow-up of 12.3 ± 4.2 months. After multivariable adjustment, participants with serum spermidine levels of ≥15.38 ng/mL (T3) and 7.59–5.38 ng/mL (T2) had hazard ratio (HR) for recurrent AMI of 0.450 [95% confidence interval (CI): 0.213–0.984] and 0.441 (95% CI: 0.215–0.907) compared with the ≤7.59 ng/mL (T1), respectively. Participants in T3 and T2 had HR for MACE of 0.566 (95% CI: 0.329–0.947) and 0.516 (95% CI: 0.298–0.893) compared with T1. A faint J-shaped association was observed between serum spermidine levels and the risk of MACE (p-nonlinearity = 0.036). Comparisons of areas under receiver operator characteristics curves confirmed that a model including serum spermidine levels had greater predictive power than the one without it (0.733 versus 0.701, p = 0.041). A marginal statistically significant mediation effect of superoxide dismutase was shown on the association between spermidine and MACE (p = 0.091). Conclusions: Serum spermidine was associated with an improved prognosis in individuals with AMI, whereas the underlying mechanism mediated by oxidative stress was not found.

Bacillus amyloliquefaciens SC06 Induced AKT-FOXO Signaling Pathway-Mediated Autophagy to Alleviate Oxidative Stress in IPEC-J2 Cells

Autophagy is a conserved proteolytic mechanism, which degrades and recycles damaged organs and proteins in cells to resist external stress. Probiotics could induce autophagy; however, its underlying molecular mechanisms remain elusive. Our previous study has found that BaSC06 could alleviate oxidative stress by inducing autophagy in rats. This research aimed to verify whether Bacillus amyloliquefaciens SC06 can induce autophagy to alleviate oxidative stress in IPEC-J2 cells, as well as explore its mechanisms. IPEC-J2 cells were first pretreated with 10⁸ CFU/mL BaSC06, and then were induced to oxidative stress by the optimal dose of diquat. The results showed that BaSC06 significantly triggered autophagy, indicated by the up-regulation of LC3 and Beclin1 along with downregulation of p62 in IPEC-J2 cells. Further analysis revealed that BaSC06 inhibited the AKT-FOXO signaling pathway by inhibiting the expression of p-AKT and p-FOXO and inducing the expression of SIRT1, resulting in increasing the transcriptional activity of FOXO3 and gene expression of the ATG5-ATG12 complex to induce autophagy, which alleviated oxidative stress and apoptosis. Taken together, BaSC06 can induce AKT-FOXO-mediated autophagy to alleviate oxidative stress-induced apoptosis and cell damage, thus providing novel theoretical support for probiotics in the prevention and treatment of oxidative damage.

Age-dependent effect of continuous 'artificial light at night' on circadian rhythm in male rats: neuroprotective role of melatonin

Circadian disruption due to artificial light at night (ALAN) is an alarming threat to modern society. In the present study we evaluated the protective effect of melatonin on age dependent redox insults and neurochemical deficits induced by ALAN in the brain of chronodisrupted rat model. Young (3 months) and old (22 months) male Wistar rats were exposed to ALAN along with melatonin supplementation (10 mg Kg^-1, oral) for 10 days. Results demonstrated significant increment in the pro-oxidant biomarkers: reactive oxygen species, lipid hydroperoxidation, protein carbonyl, nitric oxide while suppression in the total thiol, ferric reducing antioxidant potential level, superoxide dismutase and catalase activities in the brain of ALAN exposed groups with higher amplitude in aged rats. Further these oxidative modifications were protected by subsequent administration of melatonin. Mitochondrial complexes (C-I to C-IV) activity was significantly altered in young and old ALAN exposed groups with melatonin showing protective effect. Histopathological analysis show dense cytosolic staining and neuronal degeneration in cerebral cortex and different hippocampus regions with greater extent in old ALAN rats effectively moderated by melatonin supplementation. RT-PCR data analysis revealed melatonin effectively downregulated neuroinflammatory (IL-6, TNF α) and neurodegenerative marker (Ngb) while upregulating the aging (Sirt 1) gene expression in both young and old melatonin supplemented ALAN exposed groups. Our results may help in understanding the degree of ALAN induced photo-oxidative damage in neuronal redox homeostasis during aging. We also show that melatonin supplementation might provide a basis for amelioration of oxidative disturbances to improve circadian entrainment in aged populations.

Targeting autophagy in disease: established and new strategies

Macroautophagy/autophagy is an evolutionarily conserved pathway responsible for clearing cytosolic aggregated proteins, damaged organelles or invading microorganisms. Dysfunctional autophagy leads to pathological accumulation of the cargo, which has been linked to a range of human diseases, including neurodegenerative diseases, infectious and autoimmune diseases and various forms of cancer. Cumulative work in animal models, application of genetic tools and pharmacologically active compounds, has suggested the potential therapeutic value of autophagy modulation in disease, as diverse as Huntington, Salmonella infection, or pancreatic cancer. Autophagy activation versus inhibition strategies are being explored, while the role of autophagy in pathophysiology is being studied in parallel. However, the progress of preclinical and clinical development of autophagy modulators has been greatly hampered by the paucity of selective pharmacological agents and biomarkers to dissect their precise impact on various forms of autophagy and cellular responses. Here, we summarize established and new strategies in autophagy-related drug discovery and indicate a path toward establishing a more efficient discovery of autophagy-selective pharmacological agents. With this knowledge at hand, modern concepts for therapeutic exploitation of autophagy might become more plausible.

Abbreviations: ALS: amyotrophic lateral sclerosis; AMPK: AMP-activated protein kinase; ATG: autophagy-related gene; AUTAC: autophagy-targeting chimera; CNS: central nervous system; CQ: chloroquine; GABARAP: gamma-aminobutyric acid type A receptor-associated protein; HCQ: hydroxychloroquine; LYTAC: lysosome targeting chimera; MAP1LC3/LC3: microtubule associated protein 1 light chain 3; MTOR: mechanistic target of rapamycin kinase; NDD: neurodegenerative disease; PDAC: pancreatic ductal adenocarcinoma; PE: phosphatidylethanolamine; PIK3C3/VPS34: phosphatidylinositol 3-kinase catalytic subunit type 3; PtdIns3K: class III phosphatidylinositol 3-kinase; PtdIns3P: phosphatidylinositol 3-phosphate; PROTAC: proteolysis-targeting chimera; SARS-CoV-2: severe acute respiratory syndrome coronavirus 2; SQSTM1/p62: sequestosome 1; ULK1: unc-51 like autophagy activating kinase 1.