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

Primary components of MCT ketogenic diet are detrimental to bone loss associated with accelerated aging and age-related neurotoxicity in mice

Medium chained triglycerides (MCT) ketogenic diet is being extensively investigated for its neuroprotective effects against adverse effects associated with aging and neurodegenerative disorders. Aging is a common risk factor for the development of both osteoporosis and neurological disorders. Hence, suppression of aging and age-related neurodegeneration might contribute to delaying skeletal aging. The present study was designed to investigate the effects of the primary components of the MCT diet, against bone resorption associated with D-gal-induced accelerated aging and D-gal /AlCl3-induced age-related toxicity. We report bone loss in accelerated aged mice and age-related neurotoxic mice through declined Sirtuin1 (SIRT1) expression, depleted bone turnover markers, (P1NP and β-CTX-1), low bone mineral density (BMD), and deterioration of trabecular bone microarchitecture in both the distal femur and proximal tibia bones. Administration of MCT dietary components decanoic acid and octanoic acid, led to a decrease in body weight and only octanoic acid increased serum levels of ketone body, β-hydroxybutyrate (β-HB), but both of them failed to reverse the diminishing effects on bone health associated with aging and age-related neurotoxicity. Surprisingly, decanoic acid, octanoic acid, and their combination also exhibited negative effects on trabecular bone microarchitecture and BMD in the distal femur and proximal tibia bones of healthy mice. The findings from this study provide supporting evidence on the deterioration of bone health associated with aging and age-related neurotoxicity, and the bone resorption potential of MCT dietary supplements that are being prescribed in healthy older populations and elderly persons diagnosed with neurological disorders.

Epigenetic Impact of Curcumin and Thymoquinone on Cancer Therapeutics

Today, one of the most prevalent reasons for death among people is carcinoma. Because it is still on the increase throughout the world, there is a critical need for in- -depth research on the pathogenic mechanisms behind the disease as well as for efficient treatment. In the field of epigenetics, gene expression alterations that are inherited but not DNA sequence changes are investigated. Three key epigenetic changes, histone modifications, DNA methylation and non-coding RNA (ncRNA) expression, are principally responsible for the initiation and progression of different tumors. These changes are interconnected and constitute many epigenetic changes. A form of polyphenolic chemical obtained from plants called curcumin has great bioactivity against several diseases, specifically cancer. A naturally occurring substance called thymoquinone is well-known for its anticancer properties. Thymoquinone affects cancer cells through a variety of methods, according to preclinical studies. We retrieved information from popular databases, including PubMed, Google Scholar, and CNKI, to summarize current advancements in the efficiency of curcumin against cancer and its epigenetic regulation in terms of DNA methylation, histone modifications, and miRNA expression. The present investigation offers thorough insights into the molecular processes, based on epigenetic control, that underlie the clinical use of curcumin and thymoquinone in cancerous cells.

Extraction, purification, structural identification, and anti-senescent activity of novel pearl peptides on human dermal fibroblasts

The purpose of the present study was to prepare novel anti-senescent peptides from pearls, characterize their primary sequence and secondary structure, and investigate their protective effects and molecular mechanisms towards D-galactose (D-gal)-induced senescence on human dermal fibroblasts (HDFs). Novel pearl peptides with a purity of 96.58 % and maximum yield of 3.29 % were obtained using ultrasonic-assisted acetic acid extraction strategy under the optimal extraction conditions (ultrasonic power 200 W, ultrasonic time 70 min, and the ratio of pearl powder to acetic acid 1:20). It is sequenced mainly as five novel anti-senescent peptides with molecular weight < 2000 Da, and consisted of β-sheet (43.2 %), random coil (32.1 %), β-turn (21.2 %) and α-helix (3.5 %) analyzed by LC-MS/MS, FT-IR and CD spectroscopy. Further anti-senescent experiments showed that pearl peptides can increase cell viability, restore DNA damage, and suppress the accumulation of ROS as well as senescence-associated-β-galactosidase (SA-β-gal). The molecular mechanism may be that pearl peptides down-regulate the gene and protein expressions of senescence-associated proteins p53, p21, and p16. Therefore, novel pearl peptides could be developed as functional foods or nutritional supplements for the prevention of skin aging.

Icariin targets p53 to protect against ceramide-induced neuronal senescence: Implication in Alzheimer's disease

BACKGROUND

Alzheimer's disease (AD) is a leading cause of dementia. The aging brain is particularly vulnerable to various stressors, including increased levels of ceramide. However, the role of ceramide in neuronal cell senescence and AD progression and whether icariin, a natural flavonoid glucoside, could reverse neuronal senescence remain inadequately understood.

AIM

In this study, we explore the role of ceramide in neuronal senescence and AD, and whether icariin can counteract these effects.

METHODS

We pretreated HT-22 cells with icariin and then induced senescence with ceramide. Various assays were employed to assess cell senescence, such as reactive oxygen species (ROS) production, cell cycle progression, β-galactosidase staining, and expression of senescence-associated proteins. In vivo studies utilized APP/PS1 mice and C57BL/6J mice injected with ceramide to evaluate behavioral changes, histopathological alterations, and senescence-associated protein expression. Transcriptomics, molecular docking, molecular dynamics simulations, and cellular thermal shift assays were employed to verify the interaction between icariin and P53. The specificity of icariin targeting of P53 was further confirmed through rescue experiments utilizing the P53 activator Navtemadlin.

RESULTS

Our data demonstrated that ceramide could induce neuronal senescence and AD-related pathologies, which were reversed by icariin. Moreover, molecular studies revealed that icariin directly targeted P53, and its neuroprotective effects were attenuated by P53 activation, providing evidence for the role of P53 in icariin-mediated neuroprotection.

CONCLUSION

Icariin demonstrates a protective effect against ceramide-induced neuronal senescence by inhibiting the P53 pathway. This identifies a novel mechanism of action for icariin, offering a novel therapeutic approach for AD and other age-related neurodegenerative diseases.

Development of a brain-targeted nano drug delivery system to enhance the treatment of neurodegenerative effects of resveratrol

As the aging population continues to increase, aging-related inflammation, oxidative stress, and neurodegenerative diseases have become serious global health threats. Resveratrol, a star molecule in natural polyphenols, has been widely reported to have physiological activities such as anti-aging, anti-inflammatory, antioxidant, and neuroprotection. However, its poor water solubility, rapid metabolism, low bioavailability and poor targeting ability, which limits its application. Accordingly, a brain-targeted resveratrol liposome (ANG-RES-LIP) was developed to solve these issues. Experimental results showed that ANG-RES-LIP has a uniform size distribution, good biocompatibility, and a drug encapsulation rate of over 90%. Furthermore, in vitro cell experiments showed that the modification of the targeting ligand ANG significantly increased the capability of RES to cross the BBB and neuronal uptake. Compared with free RES, ANG-RES-LIP demonstrated stronger antioxidant activity and the ability to rescue oxidatively damaged cells from apoptosis. Additionally, ANG-RES-LIP showed the ability to repair damaged neuronal mitochondrial membrane potential. In vivo experiments further demonstrated that ANG-RES-LIP improved cognitive function by reducing oxidative stress and inflammation levels in the brains of aging model mice, repairing damaged neurons and glial cells, and increasing brain-derived neurotrophic factor. In summary, this study not only provides a new method for further development and application of resveratrol but also a promising strategy for preventing and treating age-related neurodegenerative diseases.

Icariin Ameliorates D-galactose-induced Cell Injury in Neuron-like PC12 Cells by Inhibiting MPTP Opening

OBJECTIVE

Icariin (ICA) has a good neuroprotective effect and can upregulate neuronal basal autophagy in naturally aging rats. Mitochondrial dysfunction is associated with brain aging-related neurodegenerative diseases. Abnormal opening of the mitochondrial permeability transition pore (mPTP) is a crucial factor in mitochondrial dysfunction and is associated with excessive autophagy. This study aimed to explore that ICA protects against neuronal injury by blocking the mPTP opening and down-regulating autophagy levels in a D-galactose (D-gal)-induced cell injury model.

METHODS

A cell model of neuronal injury was established in rat pheochromocytoma cells (PC12 cells) treated with 200 mmol/L D-gal for 48 h. In this cell model, PC12 cells were pre-treated with different concentrations of ICA for 24 h. MTT was used to detect cell viability. Senescence associated β-galactosidase (SA-β-Gal) staining was used to observe cell senescence. Western blot analysis was performed to detect the expression levels of a senescence-related protein (p21), autophagy markers (LC3B, p62, Atg7, Atg5 and Beclin 1), mitochondrial fission and fusion-related proteins (Drp1, Mfn2 and Opa1), and mitophagy markers (Pink1 and Parkin). The changes of autophagic flow were detected by using mRFP-GFP-LC3 adenovirus. The intracellular ultrastructure was observed by transmission electron microscopy. Immunofluorescence was used to detect mPTP, mitochondrial membrane potential (MMP), mitochondrial reactive oxygen species (mtROS) and ROS levels. ROS and apoptosis levels were detected by flow cytometry.

RESULTS

D-gal treatment significantly decreased the viability of PC12 cells, and markedly increased the SA-β-Gal positive cells as compared to the control group. With the D-gal stimulation, the expression of p21 was significantly up-regulated. Furthermore, D-gal stimulation resulted in an elevated LC3B II/I ratio and decreased p62 expression. Meanwhile, autophagosomes and autolysosomes were significantly increased, indicating abnormal activation of autophagy levels. In addition, in this D-gal-induced model of cell injury, the mPTP was abnormally open, the ROS generation was continuously increased, the MMP was gradually decreased, and the apoptosis was increased. ICA effectively improved mitochondrial dysfunction to protect against D-gal-induced cell injury and apoptosis. It strongly inhibited excessive autophagy by blocking the opening of the mPTP. Cotreatment with ICA and an mPTP inhibitor (cyclosporin A) did not ameliorate mitochondrial dysfunction. However, the protective effects were attenuated by cotreatment with ICA and an mPTP activator (lonidamine).

CONCLUSION

ICA inhibits the activation of excessive autophagy and thus improves mitochondrial dysfunction by blocking the mPTP opening.

Bioactive Peptides and Other Immunomodulators of Mushroom Origin

For centuries, humans have used mushrooms as both food and pro-health supplements. Mushrooms, especially those related to the functions of the human immune system, are rich in dietary fiber, minerals, essential amino acids, and various bioactive compounds and have significant health-promoting properties. Immunoregulatory compounds in mushrooms include lectins, terpenes, terpenoids, polysaccharides, and fungal immunomodulatory proteins (FIPs). The distribution of these compounds varies from one species of mushroom to another, and their immunomodulatory activities depend on the core structures and chemical modifications in the composition of the fractions. In this review, we describe active compounds from medical mushrooms. We summarize potential mechanisms for their in vitro and in vivo activities and detail approaches used in developing and applying bioactive compounds from mushrooms. Finally, we discuss applications of fungal peptides and highlight areas that require improvement before the widespread use of those compounds as therapeutic agents and explore the status of clinical studies on the immunomodulatory activities of mushrooms and their products, as well as the prospect of clinical application of AMPs as 'drug-like' compounds with great potential for treatment of non-healing chronic wounds and multiresistant infections.

Methylated urolithin A, mitigates cognitive impairment by inhibiting NLRP3 inflammasome and ameliorating mitochondrial dysfunction in aging mice

Effective therapeutic interventions for elderly patients are lacking, despite advances in pharmacotherapy. Methylated urolithin A (mUro A), a modified ellagitannin (ET)-derived metabolite, exhibits anti-inflammatory, antioxidative, and anti-apoptotic effects. Current research has primarily investigated the neuroprotective effects of mUroA in aging mice and explored the underlying mechanisms. Our study used an in vivo aging model induced by d-galactose (D-gal) to show that mUro A notably improved learning and memory, prevented synaptic impairments by enhancing synaptic protein expression and increasing EPSCs, and reduced oxidative damage in aging mice. mUro A alleviated the activation of the NOD-like receptor thermal protein domain-associated protein 3 (NLRP3) inflammasome, leading to reduced glial cell activity and neuroinflammation in both accelerated aging and naturally senescent mouse models. Moreover, mUroA enhanced the activity of TCA cycle enzymes (PDH, CS, and OGDH), decreased 8-OHdG levels, and raised ATP and NAD+ levels within the mitochondria. At the molecular level, mUro A decreased phosphorylated p53 levels and increased the expression of peroxisome proliferator-activated receptor γ coactivator 1α (PGC-1α), thus enhancing mitochondrial function. In conclusion, mUro A alleviates cognitive impairment in aging mice by suppressing neuroinflammation through NLRP3 inflammasome inhibition and restoring mitochondrial function via the p53-PGC-1α pathway. This suggests its potential therapeutic agent for brain aging and aging-related diseases.

γ-Glutamylcysteine ameliorates blood-brain barrier permeability and neutrophil extracellular traps formation after ischemic stroke by modulating Wnt/β-catenin signalling in mice

During the inflammatory response after stroke, the blood-brain barrier (BBB) is significantly disrupted, compromising its integrity. This disruption allows many peripheral neutrophils to infiltrate the injury site in the brain and release neutrophil extracellular traps (NETs), which further increase BBB permeability. In this study, we aimed to investigate the protective effects of γ-Glutamylcysteine (γ-GC), an immediate precursor of GSH, against BBB breakdown and NET formation after ischemic stroke. Our data indicated that γ-GC treatment effectively attenuated BBB damage, decreased neutrophil infiltration, and suppressed the release of NETs, ultimately leading to the amelioration of ischemic injury. Transcriptomic data and subsequent validation studies revealed that mechanistically, γ-GC exerts its effect by activating the Wnt/β-catenin pathway after ischemic stroke. This research suggests that γ-GC may hold promise as a therapeutic agent for alleviating brain injury following an ischemic stroke.

Aerobic exercise mitigates hippocampal neuronal apoptosis by regulating DAPK1/CDKN2A/REDD1/FoXO1/FasL signaling pathway in D-galactose-induced aging mice

Brain aging is the most important risk factor for neurodegenerative disorders, and abnormal apoptosis is linked to neuronal dysfunction. Specifically, studies have found that exercise effectively inhibits hippocampal neuronal apoptosis, while the molecular mechanism remains unclear. In the present study, we investigated the impact of aerobic exercise on hippocampal neuronal apoptosis in aging mice and the potential involvement of DAPK1 and its downstream pathways based on recent data that DAPK1 may be associated with neuronal death in neurodegenerative diseases. Senescent mice were subjected to 8 weeks of Aerobic training. Following behavioral testing, hippocampal samples were examined histologically and biochemically to detect pathological changes, neuronal apoptosis, and mRNA and protein levels. We found that the exercise intervention improved spatial memory and alleviated neuronal apoptosis in the brain. Notably, exercise down-regulated DAPK1 expression and inhibited Fas death receptor transactivation and the mitochondrial apoptotic pathway in the hippocampus. These results shed new light on the protective effect of regular exercise against brain aging though modulating the DAPK1 pathway.

Bioactive Peptides from Edible Mushrooms-The Preparation, Mechanisms, Structure-Activity Relationships and Prospects

Mushroom bioactive peptides (MBPs) are bioactive peptides extracted directly or indirectly from edible mushrooms. MBPs are known to have antioxidant, anti-aging, antibacterial, anti-inflammatory and anti-hypertensive properties, and facilitate memory and cognitive improvement, antitumour and anti-diabetes activities, and cholesterol reduction. MBPs exert antioxidant and anti-inflammatory effects by regulating the MAPK, Keap1-Nrf2-ARE, NF-κB and TNF pathways. In addition, MBPs exert antibacterial, anti-tumour and anti-inflammatory effects by stimulating the proliferation of macrophages. The bioactivities of MBPs are closely related to their molecular weights, charge, amino acid compositions and amino acid sequences. Compared with animal-derived peptides, MBPs are ideal raw materials for healthy and functional products with the advantages of their abundance of resources, safety, low price, and easy-to-achieve large-scale production of valuable nutrients for health maintenance and disease prevention. In this review, the preparation, bioactivities, mechanisms and structure-activity relationships of MBPs were described. The main challenges and prospects of their application in functional products were also discussed. This review aimed to provide a comprehensive perspective of MBPs.

PTP1B knockdown alleviates BMSCs senescence via activating AMPK-mediated mitophagy and promotes osteogenesis in senile osteoporosis

The senescence of bone marrow mesenchymal stem cells (BMSCs) is the basis of senile osteoporosis (SOP). Targeting BMSCs senescence is of paramount importance for developing anti-osteoporotic strategy. In this study, we found that protein tyrosine phosphatase 1B (PTP1B), an enzyme responsible for tyrosine dephosphorylation, was significantly upregulated in BMSCs and femurs with advancing chronological age. Therefore, the potential role of PTP1B in BMSCs senescence and senile osteoporosis was studied. Firstly, significantly upregulated PTP1B expression along with impaired osteogenic differentiation capacity was observed in D-galactose (D-gal)-induced BMSCs and naturally-aged BMSCs. Furthermore, PTP1B silencing could effectively alleviate senescence, improve mitochondrial dysfunction, and restore osteogenic differentiation in aged BMSCs, which was attributable to enhanced mitophagy mediated by PKM2/AMPK pathway. In addition, hydroxychloroquine (HCQ), an autophagy inhibitor, significantly reversed the protective effects from PTP1B knockdown. In SOP animal model, transplantation of LV^sh-PTP1B-transfected D-gal-induced BMSCs harvested double protective effects, including increased bone formation and reduced osteoclastogenesis. Similarly, HCQ treatment remarkably suppressed osteogenesis of LV^sh-PTP1B-transfected D-gal-induced BMSCs in vivo. Taken together, our data demonstrated that PTP1B silencing protects against BMSCs senescence and mitigates SOP via activating AMPK-mediated mitophagy. Targeting PTP1B may represent a promising interventional strategy to attenuate SOP.

γ-glutamylcysteine alleviates insulin resistance and hepatic steatosis by regulating adenylate cyclase and IGF-1R/IRS1/PI3K/Akt signaling pathways

Type 2 diabetes mellitus (T2DM), a complex metabolism disease, which was characterized by metabolic disorders including hyperglycemia, has become a major health problem due to the increasing prevalence worldwide. γ-glutamylcysteine (γ-GC) as an immediate precursor of glutathione (GSH) was originally used for the treatment of sepsis, inflammation bowel disease, and senescence. Here, we evaluated the capacity of γ-GC on diabetes-related metabolic parameters in db/db mice and insulin resistance (IR) amelioration in cells induced by palmitic acid (PA). Our data suggested that γ-GC treatment decreased body weight, reduced adipose tissue size, ameliorated ectopic fat deposition in liver, increased the GSH content in liver, improved glucose control and other diabetes-related metabolic parameters in vivo. Moreover, in vitro experiments showed that γ-GC could maintain the balance of free fatty acids (FFAs) and glucose uptake through regulating the translocation of CD36 and GLUT4 from cytoplasm to plasma membrane. Furthermore, our finding also provided evidence that γ-GC could activate Akt not only via adenylate cyclase (AC)/cAMP/PI3K signaling pathway, but also via IGF-1R/IRS1/PI3K signaling pathway to improve IR and hepatic steatosis. Blocking either of two signaling pathways could not activate Akt activation induced by γ-GC. This unique characteristic ensures the important role of γ-GC in glucose metabolism. Collectively, these results suggested that γ-GC could serve as a candidate dipeptide for the treatment of T2DM and related chronic diabetic complications via activating AC and IGF-1R/IRS1/PI3K/Akt signaling pathways to regulate CD36 and GLUT4 trafficking.

Ginsenoside Rg2 Promotes the Proliferation and Stemness Maintenance of Porcine Mesenchymal Stem Cells through Autophagy Induction

Mesenchymal stem cells (MSCs) can be used as a cell source for cultivated meat production due to their adipose differentiation potential, but MSCs lose their stemness and undergo replicative senescence during expansion in vitro. Autophagy is an important mechanism for senescent cells to remove toxic substances. However, the role of autophagy in the replicative senescence of MSCs is controversial. Here, we evaluated the changes in autophagy in porcine MSCs (pMSCs) during long-term culture in vitro and identified a natural phytochemical, ginsenoside Rg2, that could stimulate pMSC proliferation. First, some typical senescence characteristics were observed in aged pMSCs, including decreased EdU-positive cells, increased senescence-associated beta-galactosidase activity, declined stemness-associated marker OCT4 expression, and enhanced P53 expression. Importantly, autophagic flux was impaired in aged pMSCs, suggesting deficient substrate clearance in aged pMSCs. Rg2 was found to promote the proliferation of pMSCs using MTT assay and EdU staining. In addition, Rg2 inhibited D-galactose-induced senescence and oxidative stress in pMSCs. Rg2 increased autophagic activity via the AMPK signaling pathway. Furthermore, long-term culture with Rg2 promoted the proliferation, inhibited the replicative senescence, and maintained the stemness of pMSCs. These results provide a potential strategy for porcine MSC expansion in vitro.

γ-Glutamylcysteine rescues mice from TNBS-driven inflammatory bowel disease through regulating macrophages polarization

OBJECTIVE

To explore the molecular mechanism of γ-glutamylcysteine (γ-GC) in response to inflammation in vivo and in vitro on regulating the polarization of macrophages.

METHODS

The expressions of gene or protein were assessed by qPCR and Western blot assays, respectively. Cell viability was investigated by CCK-8 assay. Eight-week-old male BALB/c mice were established to examine the therapeutic effects of γ-GC in vivo. The release of TNF-α and IL-4 was determined by ELISA assay. Macrophages polarization was identified by flow cytometry assay.

RESULTS

Our data showed that γ-GC treatment significantly improved the survival, weight loss, and colon tissue damage of IBD mice. Furthermore, we established M1- and M2-polarized macrophages, respectively, and our findings provided evidence that γ-GC switched M1/M2-polarized macrophages through activating AMPK/SIRT1 axis and inhibiting inflammation-related signaling pathway.

CONCLUSION

Collectively, both in vivo and in vitro experiments suggested that γ-GC has the potential to become a promising novel therapeutic dipeptide for the treatment of IBD, which provide new ideas for the treatment of inflammatory diseases in the future.

Use of Steaming Process to Improve Biochemical Activity of Polygonatum sibiricum Polysaccharides against D-Galactose-Induced Memory Impairment in Mice

Polysaccharide from Polygonatum sibiricum (PSP) possesses antioxidant, antiaging, and neuroprotective activities. However, whether and how the steaming process influences the biological activities of PSP, especially against aging-related memory impairment, is not yet known. In this study, Polygonatum sibiricum rhizome was subjected to a “nine steaming and nine drying” process, then PSPs with different steaming times were abstracted. Thereafter, the physicochemical properties were qualified; the antioxidant activities of PSPs were evaluated in a D-gal-induced HT-22 cell model, and the effects of PSPs (PSP0, PSP5 and PSP9) on memory was evaluated using D-gal-injured mice. Our results showed that while the steamed PSPs had a low pH value and a large negative charge, they shared similar main chains and substituents. Cellular experiments showed that the antioxidant activity of steamed PSPs increased. PSP0, PSP5, and PSP9 could significantly ameliorate the memory impairment of D-gal-injured mice, with PSP5 showing the optimal effect. Meanwhile, PSP5 demonstrated the best effect in terms of preventing cell death and synaptic injury in D-gal-injured mice. Additionally, the steamed PSPs increased anti-oxidative stress-related protein expression and decreased inflammation-related protein expression in D-gal-injured mice. Collectively, the steaming process improves the effects of PSPs against D-gal-induced memory impairment in mice, likely by increasing the antioxidant activity of PSPs.