Oxidative Stress-induced Senescence Research Articles

Protective effects of pyrroloquinoline quinone against oxidative stress-induced cellular senescence and inflammation in human renal tubular epithelial cells via Keap1/Nrf2 signaling pathway

Oxidative stress-induced cellular senescence and inflammation are important biological events in diabetic nephropathy (DN). Our recent studies have found that pyrroloquinoline quinone (PQQ) has protective effects against HG-induced oxidative stress damage and apoptosis in HK-2 cells. Nevertheless, whether PQQ has the effect of anti-inflammation and anti-senescence in HK-2 cells remains unclear. Here, we showed that low-dose PQQ treatment (100 nM) downregulates the expression of P16, P21, IL-1β, TNF-α and NF-κB in HG cultured HK-2 cells. A low dose of PQQ also upregulated the protein expression of SOD2, CAT and inhibited the generation of ROS. We also indicated that PQQ affected the activity of Keap1/Nrf2 pathway, increased the nuclear accumulation of Nrf2 and the downstream pathway protein expression of Keap1/Nrf2 signaling pathway (HO-1, NQO-1, GST and GPx-3). When ML385 was added to inhibit the activity of Keap1/Nrf2 signaling pathway, the effects of PQQ on anti-oxidative stress, anti-inflammation and anti-senescence in HK-2 cells under HG condition were weakened. In conclusion, our results suggest that PQQ could modulate HG-induced inflammation and senescence in HK-2 cells via the inhibition of ROS generation and achieves the protective effects through Keap1/Nrf2 pathway and upregulating the expression of its target protein.

MHY2233 Attenuates Replicative Cellular Senescence in Human Endothelial Progenitor Cells via SIRT1 Signaling.

Cardiovascular diseases (CVDs) are a major cause of death worldwide. Due to the prevalence of many side effects and incomplete recovery from pharmacotherapies, stem cell therapy is being targeted for the treatment of CVDs. Among the different types of stem cells, endothelial progenitor cells (EPCs) have great potential. However, cellular replicative senescence decreases the proliferation, migration, and overall function of EPCs. Sirtuin 1 (SIRT1) has been mainly studied in the mammalian aging process. MHY2233 is a potent synthetic SIRT1 activator and a novel antiaging compound. We found that MHY2233 increased the expression of SIRT1, and its deacetylase activity thereby decreased expression of the cellular senescence biomarkers, p53, p16, and p21. In addition, MHY2233 decreased senescence-associated beta-galactosidase- (SA-β-gal-) positive cells and senescence-associated secretory phenotypes (SASPs), such as the secretion of interleukin- (IL-) 6, IL-8, IL-1α, and IL-1β. MHY2233 treatment protected senescent EPCs from oxidative stress by decreasing cellular reactive oxygen species (ROS) levels, thus enhancing cell survival and function. The angiogenesis, proliferation, and migration of senescent EPCs were enhanced by MHY2233 treatment. Thus, MHY2233 reduces replicative and oxidative stress-induced senescence in EPCs. Therefore, this novel antiaging compound MHY2233 might be considered a potent therapeutic agent for the treatment of age-associated CVDs.

Oxidative stress induces senescence in breast cancer stem cells

Cancer stem cells (CSCs) have been shown to be resistant to current anticancer therapies and the induction of oxidative stress is an important mechanism of action for many anticancer agents. However, it is still largely unknown how CSCs respond to hydrogen peroxide (H2O2)-induced oxidative stress. Here, we show that the levels of reactive oxygen species (ROS) are markedly lower in breast CSCs (BCSCs) than that in non-cancer stem cells (NCSCs). A transient exposure of breast cancer cells to sublethal doses of H2O2 resulted in a dose-dependent increase of the epithelium-specific antigen (ESA)+/CD44+/CD24- subpopulations, a known phenotype for BCSCs. Although BCSCs survived sublethal doses of H2O2 treatment, they lost the ability to form tumor spheres and failed to generate colonies as demonstrated by mammosphere-formation and clonogenic assays, respectively. Mechanistic studies revealed that H2O2 treatment led to a marked increase of senescence-associated β-galactosidase activity but only minimal apoptotic cell death in BCSCs. Furthermore, H2O2 triggers p53 activation and promotes p21 expression, indicating a role for the p53/p21 signaling pathway in oxidative stress-induced senescence in BCSCs. Taken together, these results demonstrate that the maintenance of a lower level of ROS is critical for CSCs to avoid oxidative stress and H2O2-induced BCSC loss of function is likely attributable to oxidative stress-triggered senescence induction, suggesting that ROS-generating drugs may have the therapeutic potential to eradicate drug-resistant CSCs via induction of premature senescence.

The resistant effect of SIRT1 in oxidative stress-induced senescence of rat nucleus pulposus cell is regulated by Akt-FoxO1 pathway.

Objective: The senescence of nucleus pulposus (NP) cells induced by oxidative stress is one of the important causes of intervertebral disc degeneration (IDD). Herein, we investigated the role and action mechanism of silent information regulator 1 (SIRT1) in oxidative stress-induced senescence of rat NP cell.Methods: Premature senescence of rat NP cells was induced by sublethal concentration of hydrogen peroxide (H2O2) (100 μM). SIRT1 was activated with SRT1720 (5 μM) to explore its effect on NP cells senescence. FoxO1 and Akt were inhibited by AS1842856 (0.2 μM) and MK-2206 (5 μM), respectively, to explore the role of Akt-FoxO1-SIRT1 axis in rat NP cells. Pretreatment with the resveratrol (20 μM), a common antioxidant and indirect activator of SIRT1, was done to investigate its role in senescent rat NP cells.Results: The mRNA and protein levels of SIRT1 were decreased in H2O2-induced senescent rat NP cells, and that specific activation of SIRT1 suppresses senescence. And the Akt-FoxO1 pathway, as the upstream of SIRT1, might be involved in the regulation of H2O2-induced senescence of rat NP cells by affecting the expression of SIRT1. In addition, the resveratrol played an anti-senescence role in rat NP cells, which might affect the Akt-FoxO1-SIRT1 axis.Conclusion: SIRT1 ameliorated oxidative stress-induced senescence of rat NP cell which was regulated by Akt-FoxO1 pathway, and resveratrol exerted anti-senescence effects by affecting this signaling axis.

Lizard Tail Extracts Exert Protective Effect Against Oxidative Stress-Induced Cellular Senescence in Human Fibroblasts.

Lizards are the evolutionarily closest animals to humans among the self-renewable species. Recent reports show that lizard tail extracts (LTE) inhibit the proliferation and angiogenesis of cancer cells but do not show any toxicity against human fibroblast cells. Nevertheless, few scientific studies investigated the effects of LTE on the treatment of skin diseases, especially oxidative stress aging. Therefore, we explored the effect of LTE on the anti-aging activity of human fibroblasts. We confirmed the anti-aging effect of LTE by SA-β-galactosidase staining. In addition, the hydrogen peroxide-induced reactive oxygen species (ROS) were decreased by the LTE, as measured by staining with the 2',7'-dichlorofluorescein diacetate reagent. We performed Western blot analysis to examine the signaling pathways. In conclusion, the LTE can prevent cellular senescence through the suppression of ROS and the downregulation of p21.

Oxidative stress-induced senescence markedly increases disc cell bioenergetics

Cellular senescence is a phenotype characterized by irreversible growth arrest, chronic elevated secretion of proinflammatory cytokines and matrix proteases, a phenomenon known as senescence-associated secretory phenotype (SASP). Biomarkers of cellular senescence have been shown to increase with age and degeneration of human disc tissue. Senescent disc cells in culture recapitulate features associated with age-related disc degeneration, including increased secretion of proinflammatory cytokines, matrix proteases, and fragmentation of matrix proteins. However, little is known of the metabolic changes that underlie the senescent phenotype of disc cells. To assess the metabolic changes, we performed a bioenergetic analysis of in vitro oxidative stress-induced senescent (SIS) human disc cells. SIS disc cells acquire SASP and exhibit significantly elevated mitochondrial content and mitochondrial ATP-linked respiration. The metabolic changes appear to be driven by the upregulated protein secretion in SIS cells as abrogation of protein synthesis using cycloheximide decreased mitochondrial ATP-linked respiration. Taken together, the results of the study suggest that the increased energy generation state supports the secretion of senescent associated proteins in SIS disc cells.

Inhibition of Sumoylation Alleviates Oxidative Stress-induced Retinal Pigment Epithelial Cell Senescence and Represses Proinflammatory Gene Expression.

Advanced age is the largest risk factor for age-related macular degeneration (AMD). Sumoylation is a reversible post-translational modification that conjugates small peptide, small ubiquitin-like modifier (SUMO), to a target protein. Dysregulation of sumoylation is recently found to be critically involved in several age-related disorders. However, the effects of sumoylation during retina senescence and aging remains elusive. This study is aimed to investigate the function and regulation of sumoylation pathway in the aging retina and premature senescent retinal pigment epithelial (RPE) cells. 1.5- and 10-month C57/B6 mice were used for comparative aging study. Both ARPE primary cultures and ARPE-19 cells were used for assay systems. The qRT-PCR was used for analysis of mRNA expression. Western blot and immunofluorescence were used to analyze the protein expression. Cell flow cytometry was used for cell cycle progression analysis. RPE barrier function and senescent-associated β-galactosidase (SA β-gal) activity were analyzed to measure cellular senescence. We show that the expression of SUMO enzymes and global protein sumoylation were downregulated in the aging mouse retina, and in the oxidative stress (OS) -induced premature senescent RPE cells. Dramatical altered distribution of SUMO E1, E2 and E3 enzymes were observed during RPE senescence. Inhibition of sumoylation alleviated OS-induced cell senescence in RPE cells, as indicated by decreased p21 and p53 expression and decreased percentage of cell cycle arrest at G0/G1 phase. Intriguingly, inhibition of SUMO E1 repressed the expression of proinflammatory cytokine and chemokine in the premature senescent RPE cells. However, inhibition of sumoylation did not prevent DNA damage during the OS-induced RPE senescence process. Our data indicate sumoylation critically regulates retina and RPE aging and that targeting sumoylation process may provide potential therapeutic strategy for AMD treatment.

Hot Water Extract of Loliolus beka Meat Attenuates H2O2-Induced Damage in Human Umbilical Vein Endothelial Cells.

Blood vessels become less flexible with senescence; arteries narrow and become less flexible, disturbing blood circulation in aging and other vascular diseases. Mechanistically, vascular senescence plays an important role in the pathogenesis of normal aging and age-related vascular diseases. Vascular senescence also causes vascular dysfunction, resulting in damage to the vessel wall. Vascular aging involves the senescence of endothelial cells. Hydrogen peroxide is widely used to achieve oxidative stress-induced premature senescence. Here, we investigated the protective effects of a hot water extract of Loliolus beka meat (LBM) against H2O2-exposed HUVECs, a human umbilical vein endothelial cells line. The hot water extract of LBM protected cells against H2O2-induced cytotoxicity while reducing the expression of senescence markers, including β-galactosidase, p53, and p21. In addition, the hot water extract of LBM protected against H2O2-induced DNA damage. These findings suggest that the hot water extract of LBM protects HUVECs from H2O2-induced senescence by preventing cellular damage. LBM serve as a supplement or natural food with benefits against vascular disease.

Melatonin protects chronic kidney disease mesenchymal stem cells against senescence via PrPC‐dependent enhancement of the mitochondrial function

Although mesenchymal stem cell (MSC)-based therapy is a treatment strategy for ischemic diseases associated with chronic kidney disease (CKD), MSCs of CKD patients undergo accelerated senescence, with decreased viability and proliferation upon uremic toxin exposure, inhibiting their utility as a potent stem cell source for transplantation therapy. We investigated the effects of melatonin administration in protecting against cell senescence and decreased viability induced by pathophysiological conditions near the engraftment site. MSCs harvested from CKD mouse models were treated with H2 O2 to induce oxidative stress. CKD-derived MSCs exhibited greater oxidative stress-induced senescence than normal-mMSCs, while melatonin protected CKD-mMSCs from H2 O2 and associated excessive senescence. The latter was mediated by PrPC -dependent mitochondrial functional enhancement; melatonin upregulated PrPC , which bound PINK1, thus promoting mitochondrial dynamics and metabolism. In vivo, melatonin-treated CKD-mMSCs survived longer, with increased secretion of angiogenic cytokines in ischemic disease engraftment sites. CKD-mMSCs are more susceptible to H2 O2 -induced senescence than normal-mMSCs, and melatonin administration protects CKD-mMSCs from excessive senescence by upregulating PrPC and enhancing mitochondrial function. Melatonin showed favorable therapeutic effects by successfully protecting CKD-mMSCs from related ischemic conditions, thereby enhancing angiogenesis and survival. These results elucidate the mechanism underlying senescence inhibition by melatonin in stem cell-based therapies using mouse-derived CKD-mMSCs.

C-terminus of Hsc70-interacting protein (CHIP) enhances stemness properties of human Wharton’s jelly mesenchymal stem cell

ABSTRACT Mesenchymal stem cells are an attractive source of multipotent cells in part because they are easy to obtain. Several E3 ligases regulate the stability and functions of various factors in different adult stem cells through the ubiquitylation pathway. We investigated the C-terminus of Hsc70-interacting protein (CHIP) E3 ligase that regulates pluripotency of human Wharton’s jelly mesenchymal stem cells (hWJMSC). We found that CHIP increases protein kinase B (Akt) phosphorylation by decreased expression of phosphatase and tensin homolog (PTEN), which suggests improvement of the survival pathway by CHIP over-expression. We also found that increased CHIP expression induced Sox2 and NANOG, which can promote stem cell self-renewal and prevent oxidative stress-induced senescence of hWJMSC by decreased p21. We found that CHIP could be used to enhance the multiple functions of hWJMSC.

Sirtuin 3-dependent mitochondrial redox homeostasis protects against AGEs-induced intervertebral disc degeneration

Intervertebral disc (IVD) degeneration contributes largely to pathoanatomical and degenerative changes of spinal structure that increase the risk of low back pain. Apoptosis in nucleus pulposus (NP) can aggravate IVD degeneration, and increasing studies have shown that interventions targeting NP cell apoptosis can ameliorate IVD degeneration, exhibiting their potential for use as therapeutic strategies. Recent data have shown that advanced glycation end products (AGEs) accumulate in NP tissues in parallel with the progression of IVD degeneration and form a microenvironment of oxidative stress. This study examined whether AGEs accumulation aggravates NP cell apoptosis and IVD degeneration, and explored the mechanisms underlying these effects. We observed that the viability and proliferation of human NP cells were significantly suppressed by AGEs treatment, mainly due to apoptosis. Furthermore, activation of the mitochondrial apoptosis pathway was detected after AGEs treatment. In addition, the molecular data showed that AGEs could significantly aggravate the generation of mitochondrial reactive oxygen species and prolonged activation of the mitochondrial permeability transition pore, as well as the increased level of Bax protein and decreased level of Bcl-2 protein in mitochondria. These effects could be reduced by antioxidant (2-(2,2,6,6-Tetramethylpiperidin-1-oxyl-4-ylamino)-2-oxoethyl) triphenylphosphonium chloride (MitoTEMPO) and Visomitin (SKQ1). Importantly, we identified that impairment of Sirtuin3 (SIRT3) function and the mitochondrial antioxidant network were vital mechanisms in AGEs-induced oxidative stress and secondary human NP cell apoptosis. Finally, based on findings that nicotinamide mononucleotide (NMN) could restore SIRT3 function and rescue human NP cell apoptosis through adenosine monophosphate-activated protein kinase and peroxisome proliferator-activated receptor-γ coactivator 1α (AMPK-PGC-1α) pathway in vitro, we confirmed its protective effect on AGEs-induced IVD degeneration in vivo. In conclusion, our data demonstrate that SIRT3 protects against AGEs-induced human NP cell apoptosis and IVD degeneration. Targeting SIRT3 to improve mitochondrial redox homeostasis may represent a potential therapeutic strategy for attenuating AGEs-associated IVD degeneration.

Rapamycin Confers Neuroprotection Against Aging-Induced Oxidative Stress, Mitochondrial Dysfunction, and Neurodegeneration in Old Rats Through Activation of Autophagy.

Brain aging is an intricate and natural phenomenon exclusively characterized by oxidative stress, accumulation of oxidatively damaged macromolecules, and alterations in structure and function of neurons that further increase the risk factor for most of the neurodegenerative diseases. In addition, age-dependent defective autophagy has also been implicated to favor the pathogenesis and prevalence of the neurological diseases. Therefore, the development of strategies that delay aging and the concomitant neurological disorders remain elusive. Thus, the present study was undertaken to investigate the effect of rapamycin-induced activation of autophagy on aging-related oxidative stress, cell death, neuroinflammation, and neurodegeneration in rat brain. Our data demonstrated the significant age-related oxidative stress, apoptotic cell death, elevated inflammatory response, and reduced level of markers associated with rejuvenation and neural integrity, including the activities of ion channel transporters (Na+/K+-ATPase and Ca2+-ATPase) and acetylcholinesterase in the brain of old aged rats. Furthermore, rapamycin (0.5 mg/kg b.w. for 28 days) induced activation of autophagy provided significant protection to aging rat brain by reducing the aging-induced oxidative stress, apoptotic cell death, and markers of neurodegeneration. Thus, our data confirmed that autophagy plays a pivotal role in delaying brain aging plausibly by maintaining the cellular homeostasis, and structural and functional integrity of cells in the brain.

Heme oxygenase-1 ameliorates oxidative stress-induced endothelial senescence via regulating endothelial nitric oxide synthase activation and coupling.

Aim: Premature senescence of vascular endothelial cells is a leading cause of various cardiovascular diseases. Therapies targeting endothelial senescence would have important clinical implications. The present study was aimed to evaluate the potential of heme oxygenase-1 (HO-1) as a therapeutic target for endothelial senescence.Methods and Results: Upregulation of HO-1 by Hemin or adenovirus infection reversed H2O2-induced senescence in human umbilical vein endothelial cells (HUVECs); whereas depletion of HO-1 by siRNA or HO-1 inhibitor protoporphyrin IX zinc (II) (ZnPP) triggered HUVEC senescence. Mechanistically, overexpression of HO-1 enhanced the interaction between HO-1 and endothelial nitric oxide synthase (eNOS), and promoted the interaction between eNOS and its upstream kinase Akt, thus resulting in an enhancement of eNOS phosphorylation at Ser1177 and a subsequent increase of nitric oxide (NO) production. Moreover, HO-1 induction prevented the decrease of eNOS dimer/monomer ratio stimulated by H2O2 via its antioxidant properties. Contrarily, HO-1 silencing impaired eNOS phosphorylation and accelerated eNOS uncoupling. In vivo, Hemin treatment alleviated senescence of endothelial cells of the aorta from spontaneously hypertensive rats, through upregulating eNOS phosphorylation at Ser1177.Conclusions: HO-1 ameliorated endothelial senescence through enhancing eNOS activation and defending eNOS uncoupling, suggesting that HO-1 is a potential target for treating endothelial senescence.

Naringenin, a common flavanone, inhibits the formation of AGEs in bread and attenuates AGEs-induced oxidative stress and inflammation in RAW264.7 cells

Dietary flavonoids as popular food additives have attracted a wide range of research interests. Naringenin, a common flavanone, was evaluated of its impact on the formation of advanced glycation endproducts (AGEs) in bread crust. It was found that with the increase of naringenin content in bread (0.25–1% w/w), the formation of CML and total fluorescent AGEs were significantly inhibited (9.67–54.27% and 11.79–35.19%, respectively). In addition, the fortification with naringenin could also significantly inhibit the formation of acrylamide in bread crust, while enhancing the antioxidant and antibacterial activity of bread crumb without bringing undesirable changes to the bread quality attributes. Moreover, in RAW264.7 cells, naringenin significantly reduced of AGEs-induced ROS production as well as the contents of some inflammatory mediators. Altogether, our finding indicated naringenin can have dual inhibitory effects on both AGEs’ formation in foods and AGEs-induced cellular oxidative stress and inflammation.

Evidence of oxidative stress-induced senescence in mature, post-mature and pathological human placentas

IntroductionPremature ageing has been implicated in placental dysfunction. Senescence can be activated by oxidative stress, a key intermediary in the pathophysiology of pre-eclampsia. We examined senescence markers across normal gestation, and in pathological and post-mature pregnancies. Inducers of oxidative stress were used to mimic senescence changes in term explants. MethodsPlacental samples were collected with ethical approval and informed consent: first and second trimester samples from surgical terminations; term and pre-term controls, and early-onset pre-eclampsia samples from caesarean deliveries. Paraffin and EM blocks of post-mature placentas were from an archival collection. Term explants were subjected to hypoxia-reoxygenation (HR) or hydrogen peroxide (H2O2). Resultsp21 was increased significantly in term homogenates compared to first and second trimester samples, and was significantly higher in PE compared to term controls. Immunostaining revealed nuclear localisation of p21 and phosphorylated histone γH2AX in syncytiotrophoblast, with abundant foci in pathological and post-mature placentas. Abnormal nuclear appearances were observed in post-mature placentas. Sudan-Black-B staining demonstrated abundant lipofuscin, an aggregate of oxidised proteins, lipids and metals, in post-mature and pathological placentas. The percentage of nuclei positive for 8-hydroxy-2′-deoxy-guanosine, a marker of oxidised DNA/RNA, was increased in pathological placentas compared to age-matched controls. These changes could be mimicked by challenge with HR or H2O2. DiscussionSenescence markers increase in normal placentas with gestational age, and are exaggerated in post-mature and pathological cases. Oxidative stress triggers equivalent changes in explants, and may precipitate senescence in vivo. The consequent pro-inflammatory senescence-associated secretory phenotype may contribute to the pathophysiology of pre-eclampsia.

1122 Nicotinamide prevents oxidative stress-induced senescence and differentiation in 2D and 3D human skin models

1122 Nicotinamide prevents oxidative stress-induced senescence and differentiation in 2D and 3D human skin models

Inhibitory effect of phytol on cellular senescence

BackgroundPhytol is a component of chlorophyll with demonstrated anticancer and immune-enhancing effects. In particular, it has been reported that phytol enhances the activity of natural killer cells that detect and remove cancer cells and promotes macrophage functions in immunity. In this study, based on the recently published precedent articles, we examined whether phytol can also inhibit cellular senescence to provide evidence for its possible use as a base material for cosmetics.MethodsHaCaT keratinocytes were pretreated with phytol for 24 h and then treated with oxidative stress-inducing hydrogen peroxide (H2O2) for 6 h before the analysis; anti-inflammation analysis, cell cycle analysis, cytoprotection analysis, caspase 3 (CASP3) activity analysis, and senescence-associated β-galactosidase (SA-β-gal) assay were performed to examine the cell potency of phytol.ResultsIn this study, HaCaT keratinocytes, treated with 750 μM H2O2, were tested with a phytol concentration below 10 μM to obtain the following results. First, phytol pretreatment suppressed H2O2-induced inflammation in a concentration-dependent manner, as indicated by the reduced expression of the mRNA levels of TNF-α (tumor necrosis factor-alpha), IL6 (interleukin 6), IL8 (interleukin 8), and COX2 (cyclooxygenase 2). Second, the quantitative analysis of cell cycle, NRF2 (nuclear factor erythroid 2-related factor 2), HO-1 (heme oxygenase 1), 14-3-3σ (Stratifin), cyclin B mRNA, and CASP3 was performed to examine the cytoprotective effects of phytol, as evidenced by increased mRNA expression of the cytoprotective genes NRF2 and HO-1 and decreased mRNA expression of the G2 cell cycle arrest-inducing genes 14-3-3σ and Cyclin B. CASP3, a protein that induces apoptosis, was reduced in a concentration-dependent manner, confirming that phytol protected cells from apoptosis. Third, the SA-β-gal assay revealed that phytol reduced H2O2-induced senescence in a concentration-dependent manner, and the cellular senescence was delayed on treatment using phytol.ConclusionsThis study verifies that phytol can inhibit oxidative stress-induced senescence of HaCaT keratinocytes. The results suggest the use of phytol as a base material for cosmetics to inhibit cellular senescence.

Inosine improves cognitive function and decreases aging-induced oxidative stress and neuroinflammation in aged female rats

In the present study, the effect of inosine was evaluated on learning and memory of 18months old aged female rats. Inosine (50, 100 and 200mg/kg; i.p.) was administered to separate groups of rats for 15 successive days. Donepezil (1mg/kg; i.p.), an acetylcholinesterase inhibitor, was used as a standard drug. Behavioral models such as Morris water maze and elevated plus maze were used to evaluate the effect of drugs on learning and memory of rats. After behavioral studies, animals were killed and their brain was isolated and further processed for estimation of various biochemical parameters such as acetylcholinesterase activity, oxidative stress markers, proinflammatory marker and histological examinations. Inosine (100 and 200mg/kg) significantly improved learning and memory of aged rats. Further, inosine significantly reduced lipid peroxidation and nitrite, and increased the levels of reduced glutathione and superoxide dismutase. However, no significant difference in AChEs activity was observed in inosine-treated rats as compared to aged control rats. TNF-α level was found to be ameliorated in aged rats by inosine. Histopathological evaluation showed that inosine-treated aged rats have less number of pyknotic neurons in hippocampal CA1 region as compared to aged control rats. In conclusion, inosine significantly improved learning and memory of aged female rats possibly through its antioxidant as well as anti-inflammatory effect and improvement of neuronal survival in the hippocampal CA1 region. However, additional studies are required to further explore the downstream signaling pathways involved in the neuroprotective effect of inosine in aged animals.

Radical scavenging activity of sulfated Bupleurum chinense polysaccharides and their effects against oxidative stress-induced senescence

In this study, BCPS-1, a polysaccharide previously isolated and characterized from Bupleurum chinense was chemically modified to yield two sulfated derivatives, which we designated as S-BCP1-4 and S-BCP1-8. The physicochemical properties of these sulfated derivatives were then determined by high performance liquid chromatography (HPLC), Fourier transform infrared spectrometry (FT-IR), and gas chromatography (GC), and then compared with those of BCPS-1. Furthermore, the antioxidant activities of all three polysaccharides were also evaluated using 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical assay, superoxide radical assay and hydroxyl radical assay, while their effects against H2O2-induced cellular senescence were determined using senescence-associated β-galactosidase (SA-β-gal) staining, cell cycle assay and immunoblotting in H2O2-induced mouse lung endothelial cells (MLECs). Compared to BCPS-1, S-BCP1-4 and S-BCP1-8 exhibited remarkable antioxidant effect, and in a concentration-dependent manner. They also provided stronger protection against H2O2-induced cellular senescence in MLECs. These results indicated that the sulfate group in the modified B. chinense polysaccharides might play an important role in radical scavenging and resistance to H2O2-induced senescence. These sulfated polysaccharides could be considered as novel pharmaceutical products with potential antioxidant and anti-senescence effects.

A bioactive polysaccharide TLH-3 isolated from Tricholoma lobayense protects against oxidative stress-induced premature senescence in cells and mice

To inform rational therapeutics to alleviate many senescence-related diseases in terms of the pathogenic pathways, we investigated the protective mechanisms of TLH-3 against premature senescence in tert-butyl hydroperoxide (t-BHP)-induced human embryonic lung fibroblast (HELF) cells model and d-galactose-induced premature aging mice model.We demonstrate that TLH-3 ameliorated t-BHP-induced premature senescence, which is characterized by decreased senescence-associated β-galactosidase (SA-β-Gal) positive cells containing decreased senescence effector p53 level, via up-regulating bcl-2 and down-regulated bax and caspase-3 protein expression to block t-BHP-induced inappropriate apoptosis. Furthermore, d-galactose-induced mice exhibit senescence hallmark features such as increased senescence-associated secretory phenotype characterized by increased interleukin-6 (IL-6) secretion. TLH-3 diminished age-dependent increase in circulating IL-6, lipofuscin pigment (LPF) and advanced glycation endproducts (AGEs) accumulation, the monoamine oxidase (MAO) activity and the intensity of nuclear p53 staining, which was up-regulated by d-galactose stimulation in premature aging mice. Meanwhile, TLH-3 attenuated d-galactose-induced histopathological lesions in premature aging mice.