Decoding Aging: Understanding the Complex Relationship among Aging, Free Radicals, and GSH

Revealing the secrets of Blue Zones

Aging is influenced by cellular senescence mechanisms that are associated with oxidative stress. Oxidative stress is the imbalance between antioxidants and free radicals. This imbalance affects enzyme activities and causes mitochondrial dysfunction. It also slows down cellular energy production and disrupts cellular homeostasis. Additionally, oxidative stress stimulates inflammation, increases the number of point mutations, and alters intercellular communication. It can lead to epigenetic alterations, genomic instability, telomere attrition, and loss of proteostasis. Ultimately, these factors contribute to aging and the development of chronic diseases. Glucose-6-phosphate dehydrogenase (G6PD) is an antioxidant enzyme that protects cells from oxidative and nitrosative damage. It helps restore redox balance, preserve macromolecule function, and rescue cells from cellular senescence, autophagy, and stress-induced apoptosis. G6PD is considered an anti-senescence enzyme. The World Health Organization classifies G6PD variants into five groups based on the enzyme's residual activity. The first four classes are categorized according to the degree of G6PD deficiency, while the fifth class includes variants with enzyme activities greater than normal. Increased G6PD activity does not exhibit clinical manifestations. Consequently, the full spectrum of mutations and the prevalence of increased G6PD activity in the population remain unknown. The world's oldest and healthiest people live in Blue Zones. These comprise isolated populations, and there may be a geographic prevalence of high-activity G6PD variants that protect against oxidative stress-induced senescence. To uncover the secret of centenarians' longevity, additional research is needed to determine whether the hidden factor is the increased activity of the G6PD enzyme.

Exploration of the regulatory mechanisms of regeneration, anti-oxidation, anti-aging and the immune response at the post-molt stage of Eriocheir sinensis

Eriocheir sinensis is widely appreciated by the surrounding population due to its culinary delicacy and rich nutrients. The E. sinensis breeding industry is very prosperous and molting is one of the important growth characteristics. Research on the regulation of molting in E. sinensis is still in the initial stages. There is currently no relevant information on the regulatory mechanisms of heart development following molting. Comparative transcriptome analysis was used to study developmental regulation mechanisms in the heart of E. sinensis at the post-molt and inter-molt stages. The results indicated that many regulatory pathways and genes involved in regeneration, anti-oxidation, anti-aging and the immune response were significantly upregulated after molting in E. sinensis. Aside from cardiac development, the differentially expressed genes (DEGs) were relevant to myocardial movement and neuronal signal transduction. DEGs were also related to the regulation of glutathione homeostasis and biological rhythms in regard to anti-oxidation and anti-aging, and to the regulation of immune cell development and the immune response. This study provides a theoretical framework for understanding the regulation of molting in E. sinensis and in other economically important crustaceans.

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.

Integrative proteomics and metabolomics approach to elucidate metabolic dysfunction induced by silica nanoparticles in hepatocytes

Silica nanoparticles (SiNPs) are derived from manufactured materials and the natural environment, and they cause detrimental effects on human health via various exposure routes. The liver is proven to be a key target organ for SiNP toxicity; however, the mechanisms causing toxicity remain largely uncertain. Here, we investigated the effects of SiNPs on the metabolic spectrum in hepatocytes via integrative analyses of proteomics and metabolomics. First, a proteomic analysis was used to screen for critical proteins (including RPL3, HSP90AA1, SOD, PGK1, GOT1, and PNP), indicating that abnormal protein synthesis, protein misfolding, oxidative stress, and metabolic dysfunction may contribute to SiNP-induced hepatotoxicity. Next, metabolomic data demonstrated that SiNPs caused metabolic dysfunction by altering vital metabolites (including glucose, alanine, GSH, CTP, and ATP). Finally, a systematic bioinformatic analysis of protein-metabolite interactions showed that SiNPs disturbed glucose metabolism (glycolysis and pentose phosphate pathways, amino acid metabolism (alanine, aspartate, and glutamate), and ribonucleotide metabolism (purine and pyrimidine). These metabolic dysfunctions could exacerbate oxidative stress and lead to liver injury. Moreover, SOD, TKT, PGM1, GOT1, PNP, and NME2 may be key proteins for SiNP-induced hepatotoxicity. This study revealed the metabolic mechanisms underlying SiNP-induced hepatotoxicity and illustrated that integrative omics analyses can be a powerful approach for toxicity evaluations and risk assessments of nanoparticles.

Estimation of Redox Status in Military Pilots during Hypoxic Flight-Simulation Conditions—A Pilot Study

At high altitude conditions, the low-pressure atmospheric oxygen reduces the generation of energy, thus inducing a decrease in oxygen availability. As a result, endurance flights evoke imbalance in redox signaling, posing a safety risk for the pilots involved. The aim of the present study was to assess changes in the redox status of military pilots during flight simulation conditions according to their flight hours (experts vs. novice). A total of seven expert pilots and an equal number of novice pilots (trainees) were recruited from the Center for Airforce Medicine of the Greek Military Airforce. Glutathione (GSH) levels, catalase activity (CAT), total antioxidant capacity (TAC), lipid peroxidation through the thiobarbituric acid-reactive substances (TBARS), and protein oxidative damage through the assay of protein carbonyls (PCs) levels were assessed at two time points, once prior to and once immediately post a scheduled flight simulation. In the experienced pilots’ arms, GSH was significantly increased post-flight simulation, with TAC being simultaneously reduced. On the other hand, in the trainees’ arms, CAT and TAC were both increased post-flight. No differences were noted with regard to the TBARS and PCs post-simulation. When the two groups were compared, TAC and PCs were significantly lower in the trainees compared to the experienced pilots. The present study provides useful insight into the physiological redox status adaptations to hypobaric hypoxic flight conditions among pilots. In a further detail, an increase in GSH response post-flight simulation is being evoked in more experienced pilots, indicating an adaptation to the extreme flight conditions, as they battle oxidative stress.

Lipopolysaccharide Induces Gliotoxicity in Hippocampal Astrocytes from Aged Rats: Insights About the Glioprotective Roles of Resveratrol

Astrocytes may undergo a functional remodeling with aging, acquiring a pro-inflammatory state. In line with this, resveratrol represents an interesting strategy for a healthier brain aging since it can improve glial functions. In the present study, we investigated the glioprotective role of resveratrol against lipopolysaccharide (LPS)-induced gliotoxicity in hippocampal aged astrocytes. Astrocyte cultures were obtained from aged rats (365 days old) and challenged in vitro with LPS in the presence of resveratrol. Cultured astrocytes from newborn rats were used as an age comparative for evaluating LPS gliotoxicity. In addition, aged rats were submitted to an acute systemic inflammation with LPS. Hippocampal astrocyte cultures were also obtained from these LPS-stimulated aged animals to further investigate the glioprotective effects of resveratrol in vitro. Overall, our results show that LPS induced a higher inflammatory response in aged astrocytes, compared to newborn astrocytes. Several inflammatory and gene expression alterations promoted by LPS in aged astrocyte cultures were similar in hippocampal tissue from aged animals submitted to in vivo LPS injection, corroborating our in vitro findings. Resveratrol, in turn, presented anti-inflammatory effects in aged astrocyte cultures, which were associated with downregulation of p21 and pro-inflammatory cytokines, Toll-like receptors (TLRs), and nuclear factor κB (NFκB). Resveratrol also improved astroglial functions. Upregulation of sirtuin 1 (SIRT1), nuclear factor erythroid 2-related factor 2 (Nrf2), and heme oxygenase 1 (HO-1) represent potential molecular mechanisms associated with resveratrol-mediated glioprotection. In summary, our data show that resveratrol can prime aged astrocytes against gliotoxic stimuli, contributing to a healthier brain aging.

Protective Effect of Lactiplantibacillus plantarum 1201 Combined with Galactooligosaccharide on Carbon Tetrachloride-Induced Acute Liver Injury in Mice

Acute liver injury (ALI) has a high mortality rate of approximately 20–40%, and it is imperative to find complementary and alternative drugs for treating ALI. A carbon tetrachloride (CCl₄)-induced ALI mouse model was established to explore whether dietary intervention can alleviate ALI in mice. Intestinal flora, intestinal integrity, biomarkers of hepatic function, systemic inflammation, autophagy, and apoptosis signals were detected through a real-time PCR, hematoxylin-eosin staining, 16S rRNA gene sequencing, and so on. The results showed that Lactiplantibacillus plantarum 1201 had a strongly antioxidant ability, and galactooligosaccharide (GOS) could boost its growth. Based on these findings, the combination of L. plantarum 1201 and GOS, the synbiotic, was applied to prevent CCl₄-induced ALI in mice. The current research proved that GOS promoted the intestinal colonization of L. plantarum 1201, and the synbiotic improved the antioxidant capacity of the host, regulated the intestinal flora, repaired the intestinal barrier, inhibited the activation of the MAPK/NF-κB pathway, and then inhibited the apoptosis and autophagy pathways, relieving inflammation and liver oxidation; thereby, the ALI of mice was alleviated. These results suggest that synbiotics may become a new research direction for liver-protecting drugs.

Integrated metabolomics and transcriptomics reveal di(2-ethylhexyl) phthalate-induced mitochondrial dysfunction and glucose metabolism disorder through oxidative stress in rat liver

Di(2-ethylhexyl) phthalate (DEHP) is a ubiquitous pollutant that results in hepatotoxicity. However, an understanding of the systematic mechanism of hepatic injury caused by DEHP remains limited. Here, we performed a comprehensive metabolomics and transcriptomics analyses to describe hepatic responses of rats to long-term DEHP exposure and, together with pathology and functional injury of liver, systematically analyzed the pathogenesis and mechanisms of liver damage. SD rats were exposed to 0 and 600 mg/kg/day DEHP for 12 weeks. Thereafter, biochemical indicators and histopathological changes regarding liver function were detected. Metabolomics and transcriptomics profiles of rat liver samples were analyzed using a UPLC-MS/MS system and Illumina Hiseq 4000, respectively. DEHP induced hepatocyte structural alterations and edema, depressed monooxygenase activity, decreased antioxidant activities, aggravated oxidative damage, blocked the tricarboxylic acid cycle and respiratory chain, and disturbed glucose homeostasis in the liver. These findings indicate that reactive oxygen species play a major role in these events. Overall, this study systematically depicts the comprehensive mechanisms of long-term DEHP exposure to liver injury and highlights the power of metabolomics and transcriptomics platforms in the mechanistic understanding of xenobiotic hepatotoxicity.