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

Mannan-binding lectin inhibits oxidative stress-induced senescence via the NAD+/Sirt1 pathway

Prolonged or excessive oxidative stress can lead to premature cellular and body aging. Mannan-binding lectin (MBL) is synthesized by the liver and plays an important role in innate immunity, anti-inflammation, and anti-oxidation, and has a positive impact on health and longevity. To date, few studies investigated the role of MBL in attenuating oxidative stress-induced senescence. In this study, we evaluated the role of MBL in oxidative stress-induced premature aging and explored its underlying mechanism in C57BL/6 mice and mouse embryonic fibroblasts (NIH/3T3). First, we established an oxidative premature senescence model induced by D-galactose in C57BL/6 mice. We found that MBL-deficient mice had a marked aging-like appearance, reduced learning and spatial exploration abilities, severe liver pathological damage, and significantly upregulated expression of Senescence-associated proteins (p53 and p21), inflammatory kinesins (IL-1β and IL-6), and the senescence β-galactosidase (SA-β-Gal) positive rate as compared with WT mice. In the H2O2-induced oxidative senescence model of NIH/3T3 cells, consistent results were obtained after MBL intervention. In addition, MBL effectively inhibited G1 phase arrest, ROS levels, DNA damage, and mitochondrial dysfunction in premature senescent cells. Mechanistically, we found that oxidative stress inhibited the nicotinamide adenine dinucleotide (NAD+)/ silent information regulator 1 (Sirt1) signaling pathway, while MBL activated the NAD+/Sirt1 signaling pathway inhibited by oxidative stress. In addition, MBL could activate the NAD+/Sirt1 pathway by upregulating NAMPT, which in turn inhibited p38 phosphorylation by activating the NAD+/Sirt1 pathway. In conclusion, MBL inhibits oxidative aging, which may facilitate the development of therapeutics to delay oxidative aging.

The role of sirtuins in intervertebral disc degeneration: Mechanisms and therapeutic potential

Intervertebral disc degeneration (IDD) is one of the main causes of low back pain, which affects the patients' quality of life and health and imposes a significant socioeconomic burden. Despite great efforts made by researchers to understand the pathogenesis of IDD, effective strategies for preventing and treating this disease remain very limited. Sirtuins are a highly conserved family of (NAD+)-dependent deacetylases in mammals that are involved in a variety of metabolic processes in vivo. In recent years, sirtuins have attracted much attention owing to their regulatory roles in IDD on physiological activities such as inflammation, apoptosis, autophagy, aging, oxidative stress, and mitochondrial function. At the same time, many studies have explored the therapeutic effects of sirtuins-targeting activators or micro-RNA in IDD. This review summarizes the molecular pathways of sirtuins involved in IDD, and summarizes the therapeutic role of activators or micro-RNA targeting Sirtuins in IDD, as well as the current limitations and challenges, with a view to provide possible solutions for the treatment of IDD.

Mechanisms and therapeutic strategies for senescence-associated secretory phenotype in the intervertebral disc degeneration microenvironment

As a permanent state of cell cycle arrest, cellular senescence has become an important factor in aging and age-related diseases. As a central regulator of physiology and pathology associated with cellular senescence, the senescence associated secretory phenotype can create an inflammatory and catabolic environment through autocrine and paracrine ways, ultimately affecting tissue microstructure. As an age-related disease, the correlation between intervertebral disc degeneration and cellular senescence has been confirmed by many studies. Various pathological factors in the microenvironment of intervertebral disc degeneration promote senescent cells to produce and accumulate and express excessive senescence associated secretory phenotype. In this case, senescence associated secretory phenotype has received considerable attention as a potential target for delaying or treating disc degeneration. Therefore, we reviewed the latest research progress of senescence associated secretory phenotype, related regulatory mechanisms and intervertebral disc cell senescence treatment strategies. It is expected that further understanding of the underlying mechanism between cellular senescence pathology and intervertebral disc degeneration will help to formulate reasonable senescence regulation strategies, so as to achieve ideal therapeutic effects.

The translational potential of this article

Existing treatment strategies often fall short in addressing the challenge of repairing intervertebral disc Intervertebral disc degeneration（IVD） degeneration. The accumulation of senescent cells and the continuous release of senescence-associated secretory phenotype (SASP) perpetually impede disc homeostasis and hinder tissue regeneration. This impairment in repair capability presents a significant obstacle to the practical clinical implementation of strategies for intervertebral disc degeneration. As a result, we present a comprehensive overview of the latest advancements in research, the associated regulatory mechanisms, and strategies for treating SASP in IVD cells. This article aims to investigate effective interventions for delaying the onset and progression of age-related intervertebral disc degeneration. In an era where the aging population is becoming increasingly prominent, this endeavor holds paramount practical and translational significance.

Current status and development direction of immunomodulatory therapy for intervertebral disk degeneration

Intervertebral disk (IVD) degeneration (IVDD) is a main factor in lower back pain, and immunomodulation plays a vital role in disease progression. The IVD is an immune privileged organ, and immunosuppressive molecules in tissues reduce immune cell (mainly monocytes/macrophages and mast cells) infiltration, and these cells can release proinflammatory cytokines and chemokines, disrupting the IVD microenvironment and leading to disease progression. Improving the inflammatory microenvironment in the IVD through immunomodulation during IVDD may be a promising therapeutic strategy. This article reviews the normal physiology of the IVD and its degenerative mechanisms, focusing on IVDD-related immunomodulation, including innate immune responses involving Toll-like receptors, NOD-like receptors and the complement system and adaptive immune responses that regulate cellular and humoral immunity, as well as IVDD-associated immunomodulatory therapies, which mainly include mesenchymal stem cell therapies, small molecule therapies, growth factor therapies, scaffolds, and gene therapy, to provide new strategies for the treatment of IVDD.

Food Polyphenols as Preventive Medicine

Reactive oxygen species (ROS) are the initiators in foods and in the stomach of oxidized dietary lipids, proteins, and lipid-oxidation end-products (ALEs), inducing in humans the development of several chronic diseases and cancer. Epidemiological, human clinical and animal studies supported the role of dietary polyphenols and derivatives in prevention of development of such chronic diseases. There is much evidence that polyphenols/derivatives at the right timing and concentration, which is critical, acts mostly in the aerobic stomach and generally in the gastrointestinal tract as reducing agents, scavengers of free radicals, trappers of reactive carbonyls, modulators of enzyme activity, generators of beneficial gut microbiota and effectors of cellular signaling. In the blood system, at low concentration, they act as generators of electrophiles and low concentration of H2O2, acting mostly as cellular signaling, activating the PI3K/Akt-mediated Nrf2/eNOS pathways and inhibiting the inflammatory transcription factor NF-κB, inducing the cells, organs and organism for eustress, adaptation and surviving.

In Vitro Models of Cell Senescence: A Systematic Review on Musculoskeletal Tissues and Cells

Ageing is an irreversible and inevitable biological process and a significant risk factor for the development of various diseases, also affecting the musculoskeletal system, resulting from the accumulation of cell senescence. The aim of this systematic review was to collect the in vitro studies conducted over the past decade in which cell senescence was induced through various methods, with the purpose of evaluating the molecular and cellular mechanisms underlying senescence and to identify treatments capable of delaying senescence. Through three electronic databases, 22 in vitro studies were identified and included in this systematic review. Disc, cartilage, or muscle cells or tissues and mesenchymal stem cells were employed to set-up in vitro models of senescence. The most common technique used to induce cell senescence was the addition to the culture medium of tumor necrosis factor (TNF)α and/or interleukin (IL)1β, followed by irradiation, compression, hydrogen peroxide (H2O2), microgravity, in vitro expansion up to passage 10, and cells harvested from damaged areas of explants. Few studies evaluated possible treatments to anti-senescence effects. The included studies used in vitro models of senescence in musculoskeletal tissues, providing powerful tools to evaluate age-related changes and pathologies, also contributing to the development of new therapeutic approaches.

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.

Rescuing Nucleus Pulposus Cells From Senescence via Dual-Functional Greigite Nanozyme to Alleviate Intervertebral Disc Degeneration

High levels of reactive oxygen species (ROS) lead to progressive deterioration of mitochondrial function, resulting in tissue degeneration. In this study, ROS accumulation induced nucleus pulposus cells (NPCs) senescence is observed in degenerative human and rat intervertebral disc, suggesting senescence as a new therapeutic target to reverse intervertebral disc degeneration (IVDD). By targeting this, dual-functional greigite nanozyme is successfully constructed, which shows the ability to release abundant polysulfides and presents strong superoxide dismutase and catalase activities, both of which function to scavenge ROS and maintain the tissue at physical redox level. By significantly lowering the ROS level, greigite nanozyme rescues damaged mitochondrial function in IVDD models both in vitro and in vivo, rescues NPCs from senescence and alleviated the inflammatory response. Furthermore, RNA-sequencing reveals ROS-p53-p21 axis is responsible for cellular senescence-induced IVDD. Activation of the axis abolishes greigite nanozyme rescued NPCs senescence phenotype, as well as the alleviated inflammatory response to greigite nanozyme, which confirms the role of ROS-p53-p21 axis in greigite nanozyme's function to reverse IVDD. In conclusion, this study demonstrates that ROS-induced NPCs senescence leads to IVDD and the dual-functional greigite nanozyme holds strong potential to reverse this process, providing a novel strategy for IVDD management.

Quercetin ameliorates oxidative stress-induced senescence in rat nucleus pulposus-derived mesenchymal stem cells via the miR-34a-5p/SIRT1 axis

BACKGROUND

Intervertebral disc degeneration (IDD) is a main contributor to low back pain. Oxidative stress, which is highly associated with the progression of IDD, increases senescence of nucleus pulposus-derived mesenchymal stem cells (NPMSCs) and weakens the differentiation ability of NPMSCs in degenerated intervertebral discs (IVDs). Quercetin (Que) has been demonstrated to reduce oxidative stress in diverse degenerative diseases.

AIM

To investigate the role of Que in oxidative stress-induced NPMSC damage and to elucidate the underlying mechanism.

METHODS

In vitro, NPMSCs were isolated from rat tails. Senescence-associated β-galactosidase (SA-β-Gal) staining, cell cycle, reactive oxygen species (ROS), real-time quantitative polymerase chain reaction (RT-qPCR), immunofluorescence, and western blot analyses were used to evaluated the protective effects of Que. Meanwhile the relationship between miR-34a-5p and Sirtuins 1 (SIRT1) was evaluated by dual-luciferase reporter assay. To explore whether Que modulates tert-butyl hydroperoxide (TBHP)-induced senescence of NPMSCs via the miR-34a-5p/SIRT1 pathway, we used adenovirus vectors to overexpress and downregulate the expression of miR-34a-5p and used SIRT1 siRNA to knockdown SIRT1 expression. In vivo, a puncture-induced rat IDD model was constructed, and X rays and histological analysis were used to assess whether Que could alleviate IDD in vivo.

RESULTS

We found that TBHP can cause NPMSCs senescence changes, such as reduced cell proliferation ability, increased SA-β-Gal activity, cell cycle arrest, the accumulation of ROS, and increased expression of senescence-related proteins. While abovementioned senescence indicators were significantly alleviated by Que treatment. Que decreased the expression levels of senescence-related proteins (p16, p21, and p53) and senescence-associated secreted phenotype (SASP), including IL-1β, IL-6, and MMP-13, and it increased the expression of SIRT1. In addition, the protective effects of Que on cell senescence were partially reversed by miR-34a-5p overexpression and SIRT1 knockdown. In vivo, X-ray, and histological analyses indicated that Que alleviated IDD in a puncture-induced rat model.

CONCLUSION

In summary, the present study provides evidence that Que reduces oxidative stress-induced senescence of NPMSCs via the miR-34a/SIRT1 signaling pathway, suggesting that Que may be a potential agent for the treatment of IDD.

Integrative single-cell RNA and ATAC sequencing reveals that the FOXO1-PRDX2-TNF axis regulates tendinopathy

Introduction

Tendinopathy, the most common form of chronic tendon disorder, leads to persistent tendon pain and loss of function. Profiling the heterogeneous cellular composition in the tendon microenvironment helps to elucidate rational molecular mechanisms of tendinopathy.

Methods and results

In this study, through a multi-modal analysis, a single-cell RNA- and ATAC-seq integrated tendinopathy landscape was generated for the first time. We found that a specific cell subpopulation with low PRDX2 expression exhibited a higher level of inflammation, lower proliferation and migration ability, which not only promoted tendon injury but also led to microenvironment deterioration. Mechanistically, a motif enrichment analysis of chromatin accessibility showed that FOXO1 was an upstream regulator of PRDX2 transcription, and we confirmed that functional blockade of FOXO1 activity induced PRDX2 silencing. The TNF signaling pathway was significantly activated in the PRDX2-low group, and TNF inhibition effectively restored diseased cell degradation.

Discussion

We revealed an essential role of diseased cells in tendinopathy and proposed the FOXO1-PRDX2-TNF axis is a potential regulatory mechanism for the treatment of tendinopathy.

Aging, cell senescence, the pathogenesis and targeted therapies of intervertebral disc degeneration

Intervertebral disc degeneration (IVDD) refers to the aging and degenerative diseases of intervertebral disc components such as nucleus pulposus, annulus fibrosus, and cartilage endplate, and is the main cause of chronic low back pain. Over the past few years, many researchers around the world concerned that the degeneration of nucleus pulposus (NP) cells plays the main role in IVDD. The degeneration of NP cells is caused by a series of pathological processes, including oxidative stress, inflammatory response, apoptosis, abnormal proliferation, and autophagy. Interestingly, many studies have found a close relationship between the senescence of NP cells and the progression of NP degeneration. The classical aging pathways also have been confirmed to be involved in the pathological process of IVDD. Moreover, several anti-aging drugs have been used to treat IVDD by inhibiting NP cells senescence, such as proanthocyanidins, resveratrol and bone morphogenetic protein 2. Therefore, this article will systematically list and discuss aging, cell senescence, the pathogenesis and targeted therapies of IVDD, in order to provide new ideas for the treatment of IVDD in the future.

Cellular Senescence in Intervertebral Disc Aging and Degeneration: Molecular Mechanisms and Potential Therapeutic Opportunities

Closely associated with aging and age-related disorders, cellular senescence (CS) is the inability of cells to proliferate due to accumulated unrepaired cellular damage and irreversible cell cycle arrest. Senescent cells are characterized by their senescence-associated secretory phenotype that overproduces inflammatory and catabolic factors that hamper normal tissue homeostasis. Chronic accumulation of senescent cells is thought to be associated with intervertebral disc degeneration (IDD) in an aging population. This IDD is one of the largest age-dependent chronic disorders, often associated with neurological dysfunctions such as, low back pain, radiculopathy, and myelopathy. Senescent cells (SnCs) increase in number in the aged, degenerated discs, and have a causative role in driving age-related IDD. This review summarizes current evidence supporting the role of CS on onset and progression of age-related IDD. The discussion includes molecular pathways involved in CS such as p53-p21CIP1, p16INK4a, NF-κB, and MAPK, and the potential therapeutic value of targeting these pathways. We propose several mechanisms of CS in IDD including mechanical stress, oxidative stress, genotoxic stress, nutritional deprivation, and inflammatory stress. There are still large knowledge gaps in disc CS research, an understanding of which will provide opportunities to develop therapeutic interventions to treat age-related IDD.

Myricetin alleviated hydrogen peroxide-induced cellular senescence of nucleus pulposus cell through regulating SERPINE1

BACKGROUND

Myricetin (MYR) is a common plant flavonoid with antioxidant and anticancer properties. However, the anti-aging effect of MYR on nucleus pulposus cells (NPCs) is still unknown. The study aimed to explore the effect of MYR on the senescence of NPCs.

METHODS

Methyl-thiazolyl tetrazolium assay was used to detect NPCs viability. Senescence level was evaluated by senescence-associated β-galactosidase (SA-β-Gal) staining and the expression levels of P21, P16, IL-6 and IL-8. RNA-Sequencing (RNA-seq) technology was used to identify differentially expressed genes (DEGs) between hydrogen peroxide + MYR (HO + MYR) group and HO group, and Gene Ontology (GO) functional was performed to analyze DEGs. A Venn diagram was generated to screen overlapping DEGs related to aging and inflammation, and the role of the promising validated DEG was selected for further investigation by gene functional assays.

RESULTS

HO inhibited NPCs viability and stimulated the senescent phenotype of NPCs, whereas MYR treatment significantly reversed SA-β-gal activity in NPCs. MYR also reduced the expression of p21 and p16 and the secretion of IL-6 and IL-8 induced by HO. RNA-seq screened 421 DEGs. The GO enrichment results showed DEGs were mainly enriched in terms such as "sterol biosynthetic process". We also found SERPINE1 has the highest log2FC abs. Silence of SERPINE1 inhibited HO-induced NPCs senescence, and overexpression of SERPINE1 could limit the anti-aging effect of MYR.

CONCLUSIONS

MYR alleviated HO-induced senescence of NPCs by regulating SERPINE1 in vitro.

Proanthocyanidins inhibit the apoptosis and aging of nucleus pulposus cells through the PI3K/Akt pathway delaying intervertebral disc degeneration

BACKGROUND

Low back pain is a common symptom of intervertebral disc degeneration (IDD), which seriously affects the quality of life of patients. The abnormal apoptosis and senescence of nucleus pulposus (NP) cells play important roles in the pathogenesis of IDD. Proanthocyanidins (PACs) are polyphenolic compounds with anti-apoptosis and anti-aging effects. However, their functions in NP cells are not yet clear. Therefore, this study was performed to explore the effects of PACs on NP cell apoptosis and aging and the underlying mechanisms of action.

METHODS

Cell viability was evaluated by cell counting kit-8 (CCK-8) assay. The apoptosis rate was determined TUNEL assays. Levels of apoptosis-associated molecules (Bcl-2, Bax, C-caspase-3 and Caspase-9) were evaluated via western blot. The senescence was observed through SA-β-gal staining and western blotting analysis was performed to observe the expression of senescence-related molecules (p-P53, P53, P21 and P16).

RESULTS

Pretreatment with PACs exhibited protective effects against IL-1β-induced NP cell apoptosis including apoptosis rate, expressions of proapoptosis and antiapoptosis related genes and protein. PACs could also alleviate the increase of p-p53, P21, and P16 in IL-1β-treated NP cells. SA-β-gal staining showed that IL-1β-induced senescence of NP cells was prevented by PACs pertreatment. In addition, PACs activated PI3K/Akt pathway in IL-1β-stimulated NP cells. However, these protected effects were inhibited after LY294002 treatment.

CONCLUSION

The results of the present study showed that PACs inhibit IL-1β-induced apoptosis and aging of NP cells by activating the PI3K/Akt pathway, and suggested that PACs have therapeutic potential for IDD.

Oxidative Stress and Intervertebral Disc Degeneration: Pathophysiology, Signaling Pathway, and Therapy

Intervertebral disc degeneration (IDD), characterized as decreased proteoglycan content, ossification of endplate, and decreased intervertebral height, is one of the major reasons of low back pain, which seriously affects the quality of life and also brings heavy economic burden. However, the mechanisms leading to IDD and its therapeutic targets have not been fully elucidated. Oxidative stress refers to the imbalance between oxidation and antioxidant systems, between too many products of reactive oxygen species (ROS) and the insufficient scavenging function. Excessive ROS can damage cell lipids, nucleic acids and proteins, which has been proved to be related to the development of a variety of diseases. In recent years, an increasing number of studies have reported that oxidative stress is involved in the pathological process of IDD. Excessive ROS can accelerate the IDD process via inducing the pathological activities, such as inflammation, apoptosis, and senescence. In this review, we focused on pathophysiology and molecular mechanisms of oxidative stress-induced IDD. Moreover, the present review also summarized the possible ideas for the future therapy strategies of oxidative stress-related IDD.

Ambra1 regulates apoptosis and chemosensitivity in breast cancer cells through the Akt-FoxO1-Bim pathway

The sensitivity of cells to chemotherapeutic agents has a major effect on disease outcome in breast cancer patients. Unfortunately, there are numerous factors involved in the regulation of chemosensitivity, and the mechanisms need to be further investigated. Autophagy/Beclin 1 regulator 1 (Ambra1) is a key protein in the crosstalk between autophagy and apoptosis. It controls the switch between these two processes, which determines whether cells survive or die. Induction of apoptosis is the primary mechanism by which most chemotherapeutic drugs eliminate cancer cells. Recently, Ambra1 has been shown to modulate paclitaxel-induced apoptosis in breast cancer cells via the Bim/mitochondrial pathway, thereby modifying the sensitivity of cells to paclitaxel. However, how Ambra1 regulates Bim expression remains unclear. Here, we further confirmed that Bim plays an indispensable role in Ambra1's regulation of apoptosis and chemosensitivity in breast cancer cells. Furthermore, Ambra1 was found to regulate Bim expression at the transcriptional level through the Akt-FoxO1 pathway. Therefore, we propose a novel pathway, Ambra1-Akt-FoxO1-Bim, which regulates apoptosis and chemosensitivity in breast cancer cells. Thus, Ambra1 may represent a potential target for breast cancer treatment.

Exosomes Immunity Strategy: A Novel Approach for Ameliorating Intervertebral Disc Degeneration

Low back pain (LBP), which is one of the most severe medical and social problems globally, has affected nearly 80% of the population worldwide, and intervertebral disc degeneration (IDD) is a common musculoskeletal disorder that happens to be the primary trigger of LBP. The pathology of IDD is based on the impaired homeostasis of catabolism and anabolism in the extracellular matrix (ECM), uncontrolled activation of immunologic cascades, dysfunction, and loss of nucleus pulposus (NP) cells in addition to dynamic cellular and biochemical alterations in the microenvironment of intervertebral disc (IVD). Currently, the main therapeutic approach regarding IDD is surgical intervention, but it could not considerably cure IDD. Exosomes, extracellular vesicles with a diameter of 30–150 nm, are secreted by various kinds of cell types like stem cells, tumor cells, immune cells, and endothelial cells; the lipid bilayer of the exosomes protects them from ribonuclease degradation and helps improve their biological efficiency in recipient cells. Increasing lines of evidence have reported the promising applications of exosomes in immunological diseases, and regarded exosomes as a potential therapeutic source for IDD. This review focuses on clarifying novel therapies based on exosomes derived from different cell sources and the essential roles of exosomes in regulating IDD, especially the immunologic strategy.

Berberine mitigates nonalcoholic hepatic steatosis by downregulating SIRT1-FoxO1-SREBP2 pathway for cholesterol synthesis

OBJECTIVE

To investigate effects of berberine (BBR) on cholesterol synthesis in HepG2 cells with free fatty acid (FFA)-induced steatosis and to explore the underlying mechanisms.

METHODS

A steatosis cell model was induced in HepG2 cell line fed with FFA (0.5 mmol/L, oleic acid:palmitic acid = 2:1), and then treated with three concentrations of BBR; cell viability was assessed with cell counting kit-8 assays. Lipid accumulation in cells was observed through oil red O staining and total cholesterol (TC) content was detected by TC assay. The effects of BBR on cholesterol synthesis mediators were assessed by Western blotting and quantitative polymerase chain reaction. In addition, both silent information regulator 1 (SIRT1) and forkhead box transcription factor O1 (FoxO1) inhibitors were employed for validation.

RESULTS

FFA-induced steatosis was successfully established in HepG2 cells. Lipid accumulation and TC content in BBR groups were significantly lower (P < 0.05, P < 0.01), associated with significantly higher mRNA and protein levels of SIRT1(P < 0.05, P < 0.01), significantly lower sterol regulatory element-binding protein 2 (SREBP2) and 3-hydroxy 3-methylglutaryl-CoA reductase levels (P < 0.05, P < 0.01), as well as higher Acetyl-FoxO1 protein level (P < 0.05, P < 0.01) compared to the FFA only group. Both SIRT1 inhibitor SIRT1-IN-1 and FoxO1 inhibitor AS1842856 blocked the BBR-mediated therapeutic effects. Immunofluorescence showed that the increased SIRT1 expression increased FoxO1 deacetylation, and promoted its nuclear translocation.

CONCLUSION

BBR can mitigate FFA-induced steatosis in HepG2 cells by activating SIRT1-FoxO1-SREBP2 signal pathway. BBR may emerge as a potential drug candidate for treating nonalcoholic hepatic steatosis.

SIRT3 mitigates intervertebral disc degeneration by delaying oxidative stress-induced senescence of nucleus pulposus cells

Senescence of nucleus pulposus (NP) cells (NPC) is a major cause of intervertebral disc degeneration (IVDD), so delay NPC senescence may be beneficial for mitigating IVDD. We studied the effect and mechanism of silent information regulator 2 homolog 3 (SIRT3) on NPC senescence in vivo and in vitro. First, we observed SIRT3 expression in normal and degenerated NPC with immunohistochemical and immunofluorescence staining. Second, using SIRT3 lentivirus transfection, reactive oxygen species probe, senescence-associated β-galactosidase staining, polymerase chain reaction, and western blot to observe the oxidative stress, senescence, and degeneration degree among groups. Subsequently, pretreatment with adenosine monophosphate-activated protein kinase (AMPK) agonists and inhibitors, observing oxidative stress, senescence, and degeneration degree among groups. Finally, the IVDD model was constructed and divided into Ctrl, Vehicle, LV-shSIRT3, and LV-SIRT3 groups. X-ray and magnetic resonance imaging scans were performed on rat's tails after 1 week; hematoxylin and eosin and safranin-O staining were used to evaluate the degree of IVDD; immunofluorescence staining was used to observe SIRT3 expression; immunohistochemical staining was used to observe oxidative stress, senescence, and degeneration degree of NP. We found that SIRT3 expression is reduced in degenerated NP tissues but increased in H2 O2 -induced NPC. Moreover, SIRT3 upregulation decreased oxidative stress, delayed senescence, and degeneration of NPC. In addition, activation of the AMPK/PGC-1α pathway can partially mitigate the NPC oxidative stress, senescence, and degeneration caused by SIRT3 knockdown. The study in vivo revealed that local SIRT3 overexpression can significantly reduce oxidative stress and ECM degradation of NPC, delay NPC senescence, thereby mitigating IVDD. In summary, SIRT3 mediated by the AMPK/PGC-1α pathway mitigates IVDD by delaying oxidative stress-induced NPC senescence.

Natural Products of Pharmacology and Mechanisms in Nucleus Pulposus Cells and Intervertebral Disc Degeneration

Intervertebral disc degeneration (IDD) is one of the main causes of low back pain (LBP), which severely reduces the quality of life and imposes a heavy financial burden on the families of affected individuals. Current research suggests that IDD is a complex cell-mediated process. Inflammation, oxidative stress, mitochondrial dysfunction, abnormal mechanical load, telomere shortening, DNA damage, and nutrient deprivation contribute to intervertebral disc cell senescence and changes in matrix metabolism, ultimately causing IDD. Natural products are widespread, structurally diverse, afford unique advantages, and exhibit great potential in terms of IDD treatment. In recent years, increasing numbers of natural ingredients have been shown to inhibit the degeneration of nucleus pulposus cells through various modes of action. Here, we review the pharmacological effects of natural products on nucleus pulposus cells and the mechanisms involved. An improved understanding of how natural products target signalling pathways will aid the development of anti-IDD drugs. This review focuses on potential IDD drugs.

Apigenin Alleviates Oxidative Stress-Induced Cellular Senescence via Modulation of the SIRT1-NAD[Formula: see text]-CD38 Axis

Oxidative stress-induced cellular senescence is now regarded as an important driving mechanism in chronic lung diseases-particularly chronic obstructive pulmonary disease (COPD). 4[Formula: see text],5,7-trihydroxyflavone (Apigenin) is a natural flavonoid product abundantly present in fruits, vegetables, and Chinese medicinal herbs. It has been known that apigenin has anti-oxidant, anti-inflammatory and liver-protecting effects. The efficacy of apigenin for lung aging, however, has not been reported. In this study, we selected the hydrogen peroxide (H₂O[Formula: see text]- or doxorubicin (DOXO)-induced senescence model in WI-38 human embryonic lung fibroblast cells to determine the potential anti-aging effects of apigenin in vitro and associated molecular mechanisms. We found that apigenin reduced senescence-associated [Formula: see text]-galactosidase (SA-[Formula: see text]-gal) activity and promoted cell growth, concomitant with a decrease in levels of Acetyl (ac)-p53, p21[Formula: see text], and p16[Formula: see text] and an increase in phospho (p)-Rb. Apigenin also increased the activation ratio of silent information regulator 1 (SIRT1), nicotinamide adenine dinucleotide (NAD[Formula: see text], and NAD[Formula: see text]/NADH and inhibited cluster of differentiation 38 (CD38) activity in a concentration-dependent manner. SIRT1 inhibition by SIRT1 siRNA abolished the anti-aging effect of apigenin. In addition, CD38 inhibition by CD38 siRNA or apigenin increased the SIRT1 level and reduced H₂O₂-induced senescence. Our findings suggest that apigenin is a promising phytochemical for reducing the impact of senescent cells in age-related lung diseases such as COPD.

The investigation of the role of sirtuin-1 on embryo implantation in oxidative stress-induced mice

PURPOSE

Implantation is essential for a successful pregnancy. Despite the increasing number of studies, implantation is still an unknown process. This study aimed to determine whether sirtuin-1 has a role in embryo implantation in oxidative stress-induced mice.

METHODS

Pregnant mice were separated into 5 groups: control, vehicle, paraquat, SRT1720, and SRT1720+Paraquat. Paraquat is a herbicide and is used to induce oxidative stress. SRT1720 is a specific sirtuin-1 activator. Implantation and inter-implantation sites were removed in the morning of the 5th day of pregnancy after Chicago blue injection was performed. Sirtuin-1 and Forkhead box O1 (FoxO1) were detected by immunohistochemistry and Western blot while acetylated lysine was evaluated by Western blot analysis. Reactive oxygen and nitrogen species (ROS/RNS) and superoxide dismutase (SOD) activity were determined by fluorometric and spectrometric methods, respectively.

RESULTS

Although there was no embryo implantation in paraquat-treated mice, 5 out of 9 SRT1720+Paraquat-treated mice had implantation sites which were significantly higher compared to the paraquat-treated group. Sirtuin-1 and FoxO1 expressions were increased at implantation sites of SRT1720-treated mice. ROS/RNS levels were decreased, while deacetylated FoxO1 levels and SOD activity were increased in SRT1720-treated mice.

CONCLUSION

Our findings suggest that sirtuin-1 may play a role in embryo implantation against oxidative stress through FoxO1-SOD signaling.

Combination of Botulinum Toxin and minocycline Ameliorates Neuropathic Pain Through Antioxidant Stress and Anti-Inflammation via Promoting SIRT1 Pathway

Neuropathic pain (NP) is one of the intractable complications of spinal cord injury (SCI), with poor prognosis and seriously affects the quality of life of patients. This study aims to determine the treatment effect and mechanism of multimodal therapies in a rat model of SCI-induced NP by combining treatment with the anti-inflammatory agent minocycline (MC) and botulinum toxin (BoNT). The combined utilization alleviated SCI-induced NP and reduced apoptosis, inflammation, and oxidative stress of SCI by activating SIRT1 and dampening pAKT, P53, and p-NF-KB. BoNT with a concentration of 0.1 nm and MC with a concentration of 20 uM were selected for the experiment in the primary microglia and astrocytes treated with LPS. It was found that the combination of BoNT and MC obviously inhibits the inflammatory response and oxidative stress of glial cells, and notably activates SIRT1 and restrains pAKT, P53, and p-NF-KB. Therefore, in the treatment of SCI-induced NP, the combination of BoNT and MC markedly improves the therapeutic effect of NP by promoting the SIRT1 expression, thereby inactivating NF-KB, P53, and PI3K/AKT signaling pathway, inhibiting inflammation and oxidative stress as well as relieving SCI-induced NP.

Food as medicine: targeting the uraemic phenotype in chronic kidney disease

The observation that unhealthy diets (those that are low in whole grains, fruits and vegetables, and high in sugar, salt, saturated fat and ultra-processed foods) are a major risk factor for poor health outcomes has boosted interest in the concept of 'food as medicine'. This concept is especially relevant to metabolic diseases, such as chronic kidney disease (CKD), in which dietary approaches are already used to ameliorate metabolic and nutritional complications. Increased awareness that toxic uraemic metabolites originate not only from intermediary metabolism but also from gut microbial metabolism, which is directly influenced by diet, has fuelled interest in the potential of 'food as medicine' approaches in CKD beyond the current strategies of protein, sodium and phosphate restriction. Bioactive nutrients can alter the composition and metabolism of the microbiota, act as modulators of transcription factors involved in inflammation and oxidative stress, mitigate mitochondrial dysfunction, act as senolytics and impact the epigenome by altering one-carbon metabolism. As gut dysbiosis, inflammation, oxidative stress, mitochondrial dysfunction, premature ageing and epigenetic changes are common features of CKD, these findings suggest that tailored, healthy diets that include bioactive nutrients as part of the foodome could potentially be used to prevent and treat CKD and its complications.

Upregulation of Sirt1 by tyrosol suppresses apoptosis and inflammation and modulates extracellular matrix remodeling in interleukin-1β-stimulated human nucleus pulposus cells through activation of PI3K/Akt pathway

Intervertebral disc degeneration (IDD) is the major pathogenesis of lower back pain. Tyrosol is a polyphenolic compound that exhibits anti-oxidant, anti-apoptotic, and anti-inflammatory effects. Herein, we explored the effects and mechanisms of tyrosol on IDD progression in interleukin (IL)-1β-stimulated human nucleus pulposus cells (HNPCs). Cell viability and apoptosis were detected by CCK-8 and flow cytometry analysis, respectively. The production of tumor necrosis factor-α (TNF-α), IL-6, nitric oxide (NO), and prostaglandin E2 (PGE2) was examined to evaluate inflammation. The mRNA expression of matrix metalloproteinases (MMPs) (MMP-3/9/13), collagen type II, SRY-related high mobility group box 9 (SOX-9), and aggrecan was measured by qRT-PCR. Protein levels of silent information regulator 2 homolog 1 (Sirt1), phosphorylated protein kinase B (p-Akt), Akt, collagen type II, SOX-9, and aggrecan were determined by western blot. Results showed that tyrosol attenuated IL-1β-induced viability reduction, apoptosis, and caspase-3/7 activity in HNPCs. The increase in the production of TNF-α, IL-6, NO, and PGE2 in IL-1β-treated HNPCs was abolished by tyrosol treatment. Tyrosol treatment reversed IL-1β-induced upregulation of MMP-3, MMP-9, and MMP-13, and downregulation of collagen II, SOX-9, and aggrecan in HNPCs. Additionally, tyrosol treatment activated the phosphatidylinositol 3-kinase (PI3K)/Akt pathway in IL-1β-stimulated HNPCs. Sirt1 was upregulated by tyrosol, and Sirt1 silencing inhibited Akt phosphorylation in HNPCs. Sirt1 knockdown attenuated the effects of tyrosol on IL-1β-induced apoptosis, inflammation, and ECM remodeling in HNPCs. In summary, upregulation of Sirt1 by tyrosol suppressed apoptosis and inflammation and regulated ECM remodeling in IL-1β-stimulated HNPCs through activation of PI3K/Akt pathway.

Exosome-Transported circRNA_0000253 Competitively Adsorbs MicroRNA-141-5p and Increases IDD

The pathogenesis of intervertebral disc degeneration (IDD) is complex, and a better understanding of IDD pathogenesis may provide a better method for the treatment of IDD. Exosomes are 40-100 nm nanosized vesicles that are released from many cell types into the extracellular space. We speculated that exosome-transported circular RNAs (circRNAs) could regulate IDD. Exosomes from different degenerative grades were isolated and added to nucleus pulposus cells (NPCs), and indicators of proliferation and apoptosis were detected. Based on the previous circRNA microarray results, the top 10 circRNAs were selected. PCR was performed to determine the circRNA with the maximum upregulation. Competing endogenous RNA (ceRNA) analysis was carried out, and the sponged microRNA (miRNA) was identified. Further functional verification of the selected circRNA was carried out in vivo and in vitro. NPCs of different degenerative grades secreted exosomes, which could regulate IDD. circRNA_0000253 was selected as having the maximum upregulation in degenerative NPC exosomes. ceRNA analysis showed that circRNA_0000253 could adsorb miRNA-141-5p to downregulate SIRT1. circRNA_0000253 was confirmed to increase IDD by adsorbing miRNA-141-5p and downregulating SIRT1 in vivo and in vitro. Exosomal circRNA_0000253 owns the maximum upregulation in degenerative NPC exosomes and could promote IDD by adsorbing miRNA-141-5p and downregulating SIRT1.

Ethanol Inhibits Mesenchymal Stem Cell Osteochondral Lineage Differentiation Due in Part to an Activation of Forkhead Box Protein O-Specific Signaling

BACKGROUND

During bone fracture repair, resident mesenchymal stem cells (MSCs) differentiate into chondrocytes, to form a cartilaginous fracture callus, and osteoblasts, to ossify the collagen matrix. Our laboratory previously reported that alcohol administration led to decreased cartilage formation within the fracture callus of rodents and this effect was mitigated by postfracture antioxidant treatment. Forkhead box protein O (FoxO) transcription factors are activated in response to intracellular reactive oxygen species (ROS), and alcohol has been shown to increase ROS. Activation of FoxOs has also been shown to inhibit canonical Wnt signaling, a necessary pathway for MSC differentiation. These findings have led to our hypothesis that alcohol exposure decreases osteochondrogenic differentiation of MSCs through the activation of FoxOs.

METHODS

Primary rat MSCs were treated with ethanol (EtOH) and assayed for FoxO expression, FoxO activation, and downstream target expression. Next, MSCs were differentiated toward osteogenic or chondrogenic lineages in the presence of 50 mM EtOH and alterations in osteochondral lineage marker expression were determined. Lastly, osteochondral differentiation experiments were repeated with FoxO1/3 knockdown or with FoxO1/3 inhibitor AS1842856 and osteochondral lineage marker expression was determined.

RESULTS

EtOH increased the expression of FoxO3a at mRNA and protein levels in primary cultured MSCs. This was accompanied by an increase in FoxO1 nuclear localization, FoxO1 activation, and downstream catalase expression. Moreover, EtOH exposure decreased expression of osteogenic and chondrogenic lineage markers. FoxO1/3 knockdown restored proosteogenic and prochondrogenic lineage marker expression in the presence of 50 mM EtOH. However, FoxO1/3 inhibitor only restored proosteogenic lineage marker expression.

CONCLUSIONS

These data show that EtOH has the ability to inhibit MSC differentiation, and this ability may rely, at least partially, on the activation of FoxO transcription factors.

Sirtuins and intervertebral disc degeneration: Roles in inflammation, oxidative stress, and mitochondrial function

Intervertebral disc degeneration (IDD) is one of the main causes of low back pain, which seriously reduces the quality of life of patients and places a heavy economic burden on their families. Cellular senescence is considered to be an important factor leading to IDD, and inflammatory response, oxidative stress, and mitochondrial dysfunction are closely related to intervertebral disc (IVD) senescence. Therefore, inhibition of the inflammatory response and oxidative stress, along with maintaining mitochondrial function, may be useful in treating IDD. The sirtuins are a family of evolutionarily conserved nicotinamide adenine dinucleotide (NAD⁺)-dependent histone deacetylases, which are the major molecules mediating life extension or delay of aging-related diseases. The sirtuin protein family consist of seven members (SIRT1 - 7), which are mainly involved in various aging-related diseases by regulating inflammation, oxidative stress, and mitochondrial function. Among them, SIRT1, SIRT2, SIRT3, and SIRT6 are closely related to IDD. In addition, some activators of sirtuin proteins, such as resveratrol, melatonin, magnolol, 1,4-dihydropyridine (DHP), SRT1720, and nicotinamide mononucleotide (NMN), have been evaluated in preclinical studies for their effects in preventing IDD. This review described the biological functions of sirtuins and the important roles of SIRT1, SIRT2, SIRT3, and SIRT6 in IDD by regulating oxidative stress, inflammatory response, and mitochondrial function. In addition, we introduce the status of some sirtuin activators in IDD preclinical studies. This review will provide a background for further clarification of the molecular mechanism underlying IDD and the development of potential therapeutic drugs.