Caffeine Protects Skin from Oxidative Stress-Induced Senescence through the Activation of Autophagy

Autophagy plays an essential role in ultraviolet radiation-driven skin photoaging

Photoaging is characterized by a chronic inflammatory response to UV light. One of the most prominent features of cutaneous photoaging is wrinkling, which is due primarily to a loss of collagen fibers and deposits of abnormal degenerative elastotic material within the dermis (actinic elastosis). These changes are thought to be mediated by inflammation, with subsequent upregulation of extracellular matrix-degrading proteases and down-regulation of collagen synthesis. Autophagy is a vital homeostatic cellular process of either clearing surplus or damaged cell components notably lipids and proteins or recycling the content of the cells’ cytoplasm to promote cell survival and adaptive responses during starvation and other oxidative and/or genotoxic stress conditions. Autophagy may also become a means of supplying nutrients to maintain a high cellular proliferation rate when needed. It has been suggested that loss of autophagy leads to both photodamage and the initiation of photoaging in UV exposed skin. Moreover, UV radiation of sunlight is capable of regulating a number of autophagy-linked genes. This review will focus on the protective effect of autophagy in the skin cells damaged by UV radiation. We hope to draw attention to the significance of autophagy regulation in the prevention and treatment of skin photoaging.

Phospholipid peroxidation-driven modification of chondrogenic transcription factor mediates alkoxyl radicals-induced impairment of embryonic bone development

Maternal stress has been associated with poor birth outcomes, including preterm birth, infant mortality, and low birth weight. Bone development disorders in the embryo as a result of maternal stress are believed to be mediated through oxidative stress damage. Various species of free radicals, such as alkoxyl radicals, can be formed through endogenous redox response or exogenous stimuli in the womb and transmitted to embryos. Yet, whether these free radicals lead to abnormal fetal bone development is unclear. Here, we demonstrate prenatal bone growth retardation and ferroptosis-related signals of chondrocytes were induced by classic alkoxyl radical generators. We also show that alkoxyl radicals lead to significant accumulation of oxidized phospholipids in chondrocytes, through the iron-mediated Fenton reaction in embryos. We further demonstrate a role for the lipid peroxidation end product, 4-HNE, which forms adducts with the pivotal chondrogenesis transcription factor SOX9, leading to its degradation, therefore dampening chondrogenesis. Our data define a critical role for phospholipid peroxidation in alkoxyl radicals-evoked abnormal chondrogenesis, and pinpoint it being a precise target for treating oxidative stress-related bone development disorders.

Salidroside Ameliorates Ultraviolet-Induced Keratinocyte Injury by Inducing SIRT1-Dependent Autophagy

Introduction

Methods

Results

Discussion

Corylin from Psoralea fructus (Psoralea corylifolia L.) protects against UV-induced skin aging by activating Nrf2 defense mechanisms

Oxidative stress damage can lead to premature skin aging or age-related skin disorders. Therefore, strategies to improve oxidative stress-induced aging are needed to protect the skin and to treat skin diseases. This study aimed to determine whether the flavonoid corylin derived from Psoralea corylifolia can prevent UV-induced skin aging and if so, to explore the potential molecular mechanisms. We found that corylin potently blocked UV-induced skin photoaging in mice by reducing oxidative stress and increasing the nuclear expression of nuclear factor-erythroid factor 2-related factor 2 Nrf2. We also found that corylin stimulated Nrf2 translocation into the nucleus and increased the delivery of its target antioxidant genes together with Kelch-like ECH-associated protein 1 (Keap1) to dissociate Nrf2. These findings indicate that corylin could prevent skin aging by inhibiting oxidative stress via Keap1-Nrf2 in mouse cells. Thus, Nrf2 activation might be a therapeutic target for preventing skin aging or skin diseases caused by aging. Our findings also provided evidence that warrants the further investigation of plant ingredients to facilitate the discovery of novel therapies targeting skin aging.

Cyclo(-Phe-Phe) alleviates chick embryo liver injury via activating the Nrf2 pathway

Excessive reactive oxygen species (ROS) accumulation is involved in the pathogenesis of liver fibrosis and damage, specifically in the developing embryo that is extremely sensitive to oxidative stress. Herein, a liver injury model in chick embryo was established by using 2,2-azobis (2-amidinopropane) dihydrochloride (AAPH), which was used to investigate the effect of cyclo(-Phe-Phe) (CPP), a natural dipeptide found in foods and beverages. The results showed that CPP significantly alleviated AAPH-induced liver pathological damage, hepatic dysfunction and inhibited the excessive production of ROS in both chick embryo liver and HepG2 cells. Additionally, CPP increased the antioxidative activity of glutathione peroxidase (GPx) and superoxide dismutase (SOD), as well as elevated the level of glutathione (GSH), suggesting that CPP combating liver injury probably depends on its antioxidant capability. Mechanistically, CPP upregulated the mRNA and protein expression of heme oxyense-1 (HO-1) and NADPH quinone oxidoreductase 1 (NQO1) in vivo and in vitro, along with promoting the translocation of nuclear factor erythroid 2-related factor 2 (Nrf2) while inhibiting its degradation through binding with Kelch-like ECH-associated protein 1 (Keap1). In conclusion, this study proposes a potential peptide drug for the treatment of hepatic damage induced by oxidative stress and also unravels its mechanism of action.

Autophagy and Renal Fibrosis

Renal fibrosis is a common process of almost all the chronic kidney diseases progressing to end-stage kidney disease. As a highly conserved lysosomal protein degradation pathway, autophagy is responsible for degrading protein aggregates, damaged organelles, or invading pathogens to maintain intracellular homeostasis. Growing evidence reveals that autophagy is involved in the progression of renal fibrosis, both in the tubulointerstitial compartment and in the glomeruli. Nevertheless, the specific role of autophagy in renal fibrosis has still not been fully understood. Therefore, in this review we will describe the characteristics of autophagy and summarize the recent advances in understanding the functions of autophagy in renal fibrosis. Moreover, the problem existing in this field and the possibility of autophagy as the potential therapeutic target for renal fibrosis have also been discussed.

Dietary sources, health benefits, and risks of caffeine

Dietary intake of caffeine has significantly increased in recent years, and beneficial and harmful effects of caffeine have been extensively studied. This paper reviews antioxidant and anti-inflammatory activities of caffeine as well as its protective effects on cardiovascular diseases, obesity, diabetes mellitus, cancers, and neurodegenerative and liver diseases. In addition, we summarize the side effects of long-term or excessive caffeine consumption on sleep, migraine, intraocular pressure, pregnant women, children, and adolescents. The health benefits of caffeine depend on the amount of caffeine intake and the physical condition of consumers. Moderate intake of caffeine helps to prevent and modulate several diseases. However, the long-term or over-consumption of caffeine can lead to addiction, insomnia, migraine, and other side effects. In addition, children, adolescents, pregnant women, and people who are sensitive to caffeine should be recommended to restrict/reduce their intake to avoid potential adverse effects.

4,4'-Dimethoxychalcone protects the skin from AAPH-induced senescence and UVB-induced photoaging by activating autophagy

Aging can lead to the occurrence of many degenerative diseases, and the most intuitive consequences are mainly manifested on the skin, which is affected by both endogenous and exogenous aging factors and can be used as an ideal model organ for studying aging. 4,4'-Dimethoxychalcone (DMC), a natural flavonoid compound from Angelica sinensis, has been proven to prolong the lifespan of multiple species. However, it is not clear whether it has the effect of delaying skin aging. This study aimed to establish a skin senescent cell model induced by oxidative stress, and further, to analyze the inhibitory effect of DMC on cellular senescence, and explore its molecular mechanisms. We found that treatment of HaCaT cells with 1 mM 2,2'-azobis(2-methylpropionamidine) dihydrochloride (AAPH) for 48 h showed significant senescent characteristics, which could be effectively alleviated by pretreatment with the antioxidant N-acetyl-L-cysteine (NAC). DMC significantly inhibited AAPH-induced senescence, and further mechanism studies showed that the activation of autophagy which depended on the phosphorylation of ULK1 at Ser555 was necessary for DMC to alleviate senescence of HaCaT cells. In addition, the mitogen-activated protein kinase (MAPK) signal pathway was also involved in the regulation of autophagy induced by DMC. These results were also validated in UVB-induced photoaging mice. In conclusion, we successfully establish a skin senescent cell model and prove that DMC can be used as a potential therapeutic agent to intervene in skin aging.

Rapamycin ameliorates chronic intermittent hypoxia and sleep deprivation-induced renal damage via the mammalian target of rapamycin (mTOR)/NOD-like receptor protein 3 (NLRP3) signaling pathway

Rapamycin inhibits the activation of NOD-like receptor protein 3 (NLRP3) by regulating the mammalian target of rapamycin (mTOR) to treat obstructive sleep apnea-related renal injury. Sleep deprivation (SD) and chronic intermittent hypoxia (CIH) mouse models were used to assess the effects of autophagy in vivo. Compared with the control, SD, and CIH groups, the SD+CIH group had lower body weight and higher levels of blood urea nitrogen (BUN), creatinine, and urinary albumin (U-Alb) (P < 0.05); renal injury and oxidative damage occurred in the SD+CIH group, the kidney cell nucleus ruptured, and morphological structure of the cells was unclear in the SD+CIH group. The SD+CIH group demonstrated increased apoptosis compared with the control, SD, and CIH groups using Western blot analysis. Compared to the control, SD, and CIH groups, the SD+CIH group showed a higher degree of microtubule-associated protein light chain 3\ staining. Compared to the SD+CIH group, BUN, creatinine, and U-Alb levels decreased, and apoptosis increased in the SD+CIH+rapamycin group, and the structure of the kidney after rapamycin treatment was well preserved. The mTOR expression was increased in the kidneys of the SD+CIH group. The NLRP3, Gasdermin D (GMDSD), interleukin (IL)-18, IL-1β, and cleaved-caspase-1 protein levels were higher in the SD+CIH group than the SD+CIH+rapamycin group, and the NLRP3, GMDSD, IL-18, IL-1β, and cleaved-caspase-1 mRNA levels were higher in the SD+CIH group than the SD+CIH+rapamycin group. Following rapamycin treatment, pyroptosis was suppressed. Rapamycin ameliorates renal damage by inhibiting the mTOR/NLRP3 signaling pathway.

Bamboo Leaf Flavonoids Suppress Oxidative Stress-Induced Senescence of HaCaT Cells and UVB-Induced Photoaging of Mice through p38 MAPK and Autophagy Signaling

With the global escalation of the aging process, the research on aging mechanisms and anti-aging strategies has become a hot spot. As the most external organ of the human body, skin can be used as an ideal organ for the study of endogenous and exogenous aging. Bamboo leaf flavonoids (BLF) possess a variety of biological effects such as antioxidant, anti-bacterial, anti-inflammatory, lipid-lowering, anti-radiation, and anti-aging. However, it is still unclear whether they can delay skin aging. This study aimed to analyze the inhibitory effect of BLF on skin aging and explore their molecular mechanisms. We found that 10–40 μg/mL BLF significantly inhibited the senescence of HaCaT cells induced by AAPH, which might be related to their antioxidant and anti-inflammatory abilities. Further mechanism studies showed that mitogen-activated protein kinase (MAPK), especially the p38 MAPK pathway, was the key to BLF to alleviate the senescence of HaCaT cells. In addition, autophagy was also involved in the anti-senescence effect of BLF. The results were also verified in UVB-induced photoaging mice. Therefore, BLF can be used as a potential therapeutic agent to intervene skin aging in vitro and in vivo.

δ-Catenin promotes cell migration and invasion via Bcl-2-regulated suppression of autophagy in prostate cancer cells

As a member of the catenin family, δ-catenin is overexpressed in many cancers, including prostate cancer, and the role of δ-catenin in prostate tumor growth has been reported. However, the involvement of δ-catenin in the migration and invasion of prostate cancer has rarely been studied. In this study, we innovatively proposed that δ-catenin would enhance the migration and invasion ability of prostate cancer cells. It is worth noting that the molecular mechanism underlying the effect involved the downregulation of autophagy. We demonstrated that δ-catenin could suppress autophagy by Bcl-2-regulated disruption of the Beclin1-Vps34 autophagosome complex. Furthermore, the effect of δ-catenin on promoting cell migration and invasion was dependent upon β-catenin-mediated Bcl-2 transcription. Finally, using rapamycin and bafilomycin, we largely confirmed that the degradation of Snails by autolysosomes may be related to δ-catenin regulated migration and invasion. Overall, our results indicated that δ-catenin promoted cell migration and invasion of prostate cancer cells via Bcl-2-regulated autophagy suppression.

Skin senescence: mechanisms and impact on whole-body aging

The skin is the largest organ and has a key protective role. Similar to any other tissue, the skin is influenced not only by intrinsic/chronological aging, but also by extrinsic aging, triggered by environmental factors that contribute to accelerating the skin aging process. Aged skin shows structural, cellular, and molecular changes and accumulation of senescent cells. These senescent cells can induce or accelerate the age-related dysfunction of other nearby cells from the skin, or from different origins. However, the extent and underlying mechanisms remain unknown. In this opinion, we discuss the possible relevant role of skin senescence in the induction of aging phenotypes to other organs/tissues, contributing to whole-body aging. Moreover, we suggest that topical administration of senolytics/senotherapeutics could counteract the overall whole-body aging phenotype.

Bitter taste receptors protect against skin aging by inhibiting cellular senescence and enhancing wound healing

BACKGROUND/OBJECTIVES

Bitter taste receptors are taste signaling pathway mediators, and are also expressed and function in extra-gustatory organs. Skin aging affects the quality of life and may lead to medical issues. The purpose of this study was to better understand the anti-skin aging effects of bitter taste receptors in D-galactose (D-gal)-induced aged human keratinocytes, HaCaT cells.

MATERIALS/METHODS

Expressions of bitter taste receptors in HaCaT cells and mouse skin tissues were examined by polymerase chain reaction assay. Bitter taste receptor was overexpressed in HaCaT cells, and D-gal was treated to induce aging. We examined the effects of bitter taste receptors on aging by using β-galactosidase assay, wound healing assay, and Western blot assay.

RESULTS

TAS2R16 and TAS2R10 were expressed in HaCaT cells and were upregulated by D-gal treatment. TAS2R16 exerted protective effects against skin aging by regulating p53 and p21, antioxidant enzymes, the SIRT1/mechanistic target of rapamycin pathway, cell migration, and epithelial-mesenchymal transition markers. TAS2R10 was further examined to confirm a role of TAS2R16 in cellular senescence and wound healing in D-gal-induced aged HaCaT cells.

CONCLUSIONS

Our results suggest a novel potential preventive role of these receptors on skin aging by regulating cellular senescence and wound healing in human keratinocyte, HaCaT.

Artesunate treatment ameliorates ultraviolet irradiation-driven skin photoaging via increasing β-catenin expression

OBJECTIVE

Artesunate, a semi-synthetic derivative of artemisinin, exerts various pharmacological activities. Nevertheless, the effects of Art on skin photoaging remain unclear. Herein, we investigated whether Art ameliorated ultraviolet-irradiated skin photoaging in HaCaT cells and mice.

METHODS

To construct skin photoaging cellular models, HaCaT cells were irradiated by UV (UVB, 20mJ/cm²) for 5 days. HaCaT cells were pretreated with three concentrations of Art (1, 5 and 20 μg/ml) for 2 h each day. After 5 days, cell senescence, ROS production, SOD levels, p16^INK4a and β-catenin expression, proliferation and apoptosis were detected in HaCaT cells. Effects of Art on normal cells were investigated. After sh-β-catenin transfection or XAV-939 treatment, HaCaT cells were pretreated with 20 μg/ml Art and irradiated by UVB. After 5 days, skin photoaging was then observed. Furthermore, skin photoaging mouse models were established and the effects of Art and β-catenin silencing on skin photoaging were investigated.

RESULTS

Art treatment suppressed cell senescence, intracellular ROS production, p16^INK4a expression and apoptosis and promoted proliferation and SOD and β-catenin expression in UVB irradiated HaCaT cells. But Art had no toxic effects on normal cells. Silencing β-catenin by sh-β-catenin or XAV-939 exacerbated UVB irradiation-mediated cell senescence, apoptosis, and ROS production in HaCaT cells, which was ameliorated by Art treatment. The therapeutic effects of Art on skin photoaging were also confirmed in mouse models.

CONCLUSIONS

These findings suggested that Art treatment alleviated UVB irradiation-driven skin photoaging through enhancing β-catenin expression, which offered novel clues for pharmacological activity of Art.

Pva-miR-252 participates in ammonia nitrogen-induced oxidative stress by modulating autophagy in Penaeus vannamei

MicroRNAs (miRNAs) are critical post-transcriptional regulators, which play a crucial role in resistance to adverse environmental stress by regulating autophagy. However, the mechanism of miRNA involved in the autophagy regulation of shrimp under ammonia nitrogen stress is still limited. In the present study, ammonia nitrogen could induce hepatopancreas injury and oxidative stress of P. vannamei, and significantly increase the content of ROS in hemocytes by flow cytometry. Simultaneously, it is accompanied by autophagy occurred in the hemocytes and hepatopancreas. Furthermore, the qRT-PCR analysis revealed that the expression of pva-miR-252 in P. vannamei decreased significantly after ammonia nitrogen stress, and pva-miR-252 negatively regulated PvPI3K by binding to 3'UTR of PvPI3K by double-luciferase assay. Pva-miR-252 overexpression could significantly increase the level of autophagy, and restore the autophagy inhibition caused by Chloroquine in vitro , whereas silencing of pva-miR-252 resulted in the opposite effect. More importantly, overexpression of pva-miR-252 could enhance the activity of antioxidant enzymes and reduced the production of ROS of shrimp under ammonia nitrogen stress. In conclusion, pva-miR-252 could positively regulate autophagy through PvPI3K and improve the antioxidant enzyme activity of P. vannamei under ammonia nitrogen stress, and our study provides a novel theoretical molecular mechanism for further understanding the shrimp cope with a high ammonia nitrogen environment.

Camphorquinone Promotes the Antisenescence Effect via Activating AMPK/SIRT1 in Stem Cells and D-Galactose-Induced Aging Mice

Terpenoids are a wide class of secondary metabolites with geroprotective properties that can alter the mechanism of aging and aging-related diseases. Camphorquinone (CQ) is a bicyclic monoterpenoid compound that can be efficiently synthesized through the continuous bromination and oxidation reaction of camphor. The purpose of this study is to investigate the effects of CQ on oxidative-stress-induced senescence and its underlying mechanisms. To generate oxidative stress in human bone marrow mesenchymal stem cells (hBM-MSCs) and mice, we used hydrogen peroxide (200 μM twice) and D-galactose (D-Gal) (150 mg/kg for 10 weeks), respectively. Our findings suggest that CQ potentially reduces senescence in hBM-MSCs and mouse heart tissue. In addition, we found that CQ boosted AMPK/SIRT1 activation and autophagy in both models. These results were subsequently verified in hBM-MSCs using compound C (an AMPK inhibitor) but AMPK inhibition by CC did not significantly reduce the SIRT1 and the autophagy markers. CQ treatment also reduced the gene expression of inflammation markers in D-Gal-induced aging mouse heart tissue. Furthermore, we determined that CQ fits all of the pharmacological parameters using the freely available SwissADME Web tool. Collectively, our findings demonstrate that CQ possesses antisenescence and cardioprotective properties, and that oxidative-stress-induced senescence could be suppressed by AMPK/SIRT1 and autophagy mechanisms.

Cyclosporin A alleviates trophoblast apoptosis and senescence by promoting autophagy in preeclampsia

INTRODUCTION

Abnormal extravillous trophoblast (EVT) function is closely related to preeclampsia (PE) and may be caused by inadequate autophagy, apoptosis, and senescence. Cyclosporin A (CsA) is an effective immunosuppressant that has been reported to stimulate autophagy and exert benign biological effects on EVTs. Therefore, we hypothesized that CsA may display therapeutic efficacy against PE by activating autophagy.

METHODS

We established the nitro-l-arginine methyl ester (l-NAME)-induced preeclamptic mice model and a hypoxia-reoxygenation (H/R) model in vitro. The effects of CsA on autophagy were evaluated by western blotting (WB). The effects of CsA on apoptosis were analyzed by Hematoxylin-eosin (H&E) staining, cell apoptosis assay and WB. Senescence-associated β-galactosidase (SA-β-gal) staining, RT-qPCR and WB were used to examine the senescence level. RT-qPCR were used to detect the senescence-associated secretory phenotype (SASP) level. DCFH-DA fluorescent probe, dihydroethidium (DHE) staining and mitochondrial membrane potential (ΔΨm) were used to detect senescence-associated mitochondrial dysfunction (SAMD).

RESULTS

CsA alleviated PE-like symptoms and reduced placental necrosis and senescence in mice injected with l-NAME. CsA ameliorated placental SASP and SAMD level induced by l-NAME. CsA also upregulated the expression of autophagic proteins in mouse placentas disrupted using l-NAME. In vitro, we found that CsA reversed H/R-induced apoptosis and senescence, as well as decreasing SASP and SAMD levels and upregulating autophagic proteins levels. Notably, 3-methyladenine (3-MA), an early phase inhibitor of autophagosome formation, abolished the protective effects of CsA against H/R.

DISCUSSION

CsA may display some therapeutic effects against PE by activating autophagy in vivo and in vitro.

Antioxidant Effect of Lactobacillus fermentum CQPC04-Fermented Soy Milk on D-Galactose-Induced Oxidative Aging Mice

The aim of this study is to evaluate the changes in soy isoflavones and peptides in soy milk after lactic acid bacterial fermentation, and explore the positive effects of fermented soy milk on an oxidative aging mouse model induced with D-galactose. We found that free soybean isoflavones and peptides increased after soy milk was fermented by Lactobacillus fermentum CQPC04. The in vivo results indicated that L. fermentum CQPC04-fermented soy milk enhanced the organ index of the liver and spleen, and improved the pathological morphology of the liver, spleen, and skin. L. fermentum CQPC04-fermented soy milk increased the enzymatic activity of glutathione peroxidase (GSH-Px), total superoxide dismutase (T-SOD), and catalase (CAT), increased glutathione (GSH), but decreased the levels of nitric oxide (NO) and malondialdehyde (MDA) in serum, liver, and brain tissues of oxidative aging mice. The above mentioned fermented soy milk also increased the levels of collagen I (Col I), hyaluronic acid (HA), and collagen III (Col III), and decreased the levels of advanced glycation End products (AGEs) and hydrogen peroxide (H₂O₂). The RT-qPCR results showed that L. fermentum CQPC04-fermented soy milk upregulated the mRNA expression of nuclear factor erythroid 2?related factor (Nrf2), heme oxygenase-1 (HMOX1), quinone oxido-reductase 1 (Nqo1), neuronal nitric oxide synthase (NOS1), endothelial nitric oxide synthase (NOS3), Cu/Zn–superoxide dismutase (Cu/Zn-SOD), Mn–superoxide dismutase (Mn-SOD), and CAT, but downregulated the expression of inducible nitric oxide synthase (NOS2) and glutamate cysteine ligase modifier subunit (Gclm) in liver and spleen tissues. Lastly, the fermented soy milk also increased the gene expression of Cu/Zn-SOD, Mn-SOD, CAT, GSH-Px, matrix metalloproteinases 1 (TIMP1), and matrix metalloproteinases 2 (TIMP2), and decreased the expression of matrix metalloproteinase 2 (MMP2) and matrix metalloproteinase 9 (MMP9) in skin tissue. In conclusion, L. fermentum CQPC04-fermented soy milk was able to satisfactorily delay oxidative aging effects, and its mechanism may be related to the increase in free soy isoflavones and peptides.

Caffeine Inhibits Activation of the NLRP3 Inflammasome via Autophagy to Attenuate Microglia-Mediated Neuroinflammation in Experimental Autoimmune Encephalomyelitis

The activation of microglia is an important cause of central nervous system (CNS) inflammatory cell infiltration and inflammatory demyelination in experimental autoimmune encephalomyelitis (EAE). Furthermore, the proinflammatory response induced by the NLR family pyrin domain containing 3 (NLRP3) inflammasome can be amplified in microglia after NLRP3 inflammasome activation. Autophagy is closely related to the inflammatory response. Caffeine exerts anti-inflammatory and autophagy-stimulating effects, but the specific mechanism remains unclear. This study examined the mechanism underlying the anti-inflammatory effect of caffeine on EAE. In this study, C57BL/6 mice were immunized to induce EAE and treated with caffeine to observe its effect on prognosis. The effects of caffeine on autophagy and inflammation were also analysed in mouse primary microglia (PM) and the BV2 cell line. The data demonstrated that caffeine reduced the clinical score, the infiltration of inflammatory cells, the demyelination level, and the activation of microglia in EAE mice. Furthermore, caffeine increased the LC3-II/LC3-I levels and decreased the NLRP3 and P62 levels in EAE mice, whereas the autophagy inhibitor 3-methylamine (3-MA) blocked these effects. In vitro, caffeine promoted autophagy by suppressing the mechanistic target of rapamycin (mTOR) pathway and inhibited activation of the NLRP3 inflammasome. However, autophagy-related gene 5 (ATG5)-specific siRNA abolished the anti-inflammatory effect of caffeine treatment in PM and BV2 cells. Taken together, these data suggest that caffeine exerts a newly discovered effect on EAE by reducing NLRP3 inflammasome activation via the induction of autophagy in microglia.

Caffeine as a Factor Influencing the Functioning of the Human Body-Friend or Foe?

Nowadays, caffeine is one of the most commonly consumed substances, which presents in many plants and products. It has both positive and negative effects on the human body, and its activity concerns a variety of systems including the central nervous system, immune system, digestive system, respiratory system, urinary tract, etc. These effects are dependent on quantity, the type of product in which caffeine is contained, and also on the individual differences among people (sex, age, diet etc.). The main aim of this review was to collect, present, and analyze the available information including the latest discoveries on the impact of caffeine on human health and the functioning of human body systems, taking into account the role of caffeine in individual disease entities. We present both the positive and negative sides of caffeine consumption and the healing properties of this purine alkaloid in diseases such as asthma, Parkinson's disease, and others, not forgetting about the negative effects of excess caffeine (e.g., in people with hypertension, children, adolescents, and the elderly). In summary, we can conclude, however, that caffeine has a multi-directional influence on various organs of the human body, and because of its anti-oxidative properties, it was, and still is, an interesting topic for research studies including those aimed at developing new therapeutic strategies.

Licochalcone D Ameliorates Oxidative Stress-Induced Senescence via AMPK Activation

Increased oxidative stress is a crucial factor for the progression of cellular senescence and aging. The present study aimed to investigate the effects of licochalcone D (Lico D) on oxidative stress-induced senescence, both in vitro and in vivo, and explore its potential mechanisms. Hydrogen peroxide (200 µM for double time) and D-galactose (D-Gal) (150 mg/kg) were used to induce oxidative stress in human bone marrow-mesenchymal stem cells (hBM-MSCs) and mice, respectively. We performed the SA-β-gal assay and evaluated the senescence markers, activation of AMPK, and autophagy. Lico D potentially reduced oxidative stress-induced senescence by upregulating AMPK-mediated activation of autophagy in hBM-MSCs. D-Gal treatment significantly increased the expression levels of senescence markers, such as p53 and p21, in the heart and hippocampal tissues, while this effect was reversed in the Lico D-treated animals. Furthermore, a significant increase in AMPK activation was observed in both tissues, while the activation of autophagy was only observed in the heart tissue. Interestingly, we found that Lico D significantly reduced the expression levels of the receptors for advanced glycation end products (RAGE) in the hippocampal tissue. Taken together, our findings highlight the antioxidant, anti-senescent, and cardioprotective effects of Lico D and suggest that the activation of AMPK and autophagy ameliorates the oxidative stress-induced senescence.

Caffeine prevents oxalate-induced epithelial-mesenchymal transition of renal tubular cells by its anti-oxidative property through activation of Nrf2 signaling and suppression of Snail1 transcription factor

Caffeine is an active ingredient found in coffee and energy beverages. Its hepatoprotective effects against liver fibrosis are well-documented. Nonetheless, its renoprotective effects against renal fibrogenesis and epithelial-mesenchymal transition (EMT) processes remain unclear and under-investigated. In this study, the protective effects of caffeine against oxalate-induced EMT in renal tubular cells were evaluated by various assays to measure expression levels of epithelial and mesenchymal markers, cell migrating activity, level of oxidized proteins, and expression of Nrf2 and Snail1. Oxalate at sublethal dose significantly suppressed cell proliferation but increased cell elongation, spindle index and migration. Oxalate also decreased expression of epithelial markers (zonula occludens-1 (ZO-1) and E-cadherin) but increased expression of mesenchymal markers (fibronectin, vimentin and α-smooth muscle actin (α-SMA)). All of these EMT-inducing effects of oxalate could be prevented by pretreatment with caffeine. While oxalate increased oxidized proteins and Snail1 levels, it decreased Nrf2 expression. Caffeine could preserve all these molecules to their basal (control) levels. Finally, silencing of Nrf2 expression by small interfering RNA (siRNA) could abolish such protective effects of caffeine on oxalate-induced EMT. Our data indicate that the renoprotective effects of caffeine against oxalate-induced EMT is mediated, at least in part, by its anti-oxidative property through activation of Nrf2 signaling and suppression of Snail1 transcription factor.

Tribological, cytotoxicity and antibacterial properties of graphene oxide/carbon fibers/polyetheretherketone composite coatings on Ti-6Al-4V alloy as orthopedic/dental implants

In this work, graphene oxide/carbon fibers/polyetheretherketone (GO/CF/PEEK) composite coatings on Ti-6Al-4V (TC4) alloy were fabricated by electrostatic powder spraying method. The coatings with 0.02 wt% GO and 25 wt% CF were made to improve the wear resistance, cytocompatibility and antibacterial properties of the TC4 as orthopedic/dental implants. The physicochemical properties involving coating thickness, Vickers hardness, micromorphology, phase structures and contact angles were investigated. The results indicated that the GO/CF/PEEK coatings can significantly decrease the coefficient of friction (COF) (from 0.433 ± 0.017 to 0.085 ± 0.008) and enhance the wear resistance of TC4 alloy during the wet friction process in sliding contact with a Si₃N₄ ball. The results showed that few scratches appeared on the GO/CF/PEEK coating. As the in vitro cytotoxicity test by murine fibroblast L929 cells shown, the GO/CF/PEEK coating revealed good cytocompatibility. More importantly, GO/CF/PEEK coating exhibited excellent suppression toward Staphylococcus aureus (S. aureus) owing to the antibacterial nature of GO. Therefore, the GO/CF/PEEK composite coated TC4 could be considered as a prospective orthopedic/dental implant material for bone tissue engineering.

Skin Antiaging Effects of the Fermented Outer Layers of Leaf Skin of Aloe barbadensis Miller Associated with the Enhancement of Mitochondrial Activities of UVb-Irradiated Human Skin Fibroblasts

This study is the first to show that increased mitochondrial activities improved the antiaging effects of Aloe vera leaf skin fermented by Lactobacillus plantarum on UVb-irradiated skin fibroblasts. The fermented extract (AF) increased the activities of mitochondrial reductase and the complex II and significantly reduced reactive oxygen species (ROS) production, even under UVb stress conditions, and also increased DPPH free radical scavenging activities compared with the hot water extract of outer layers of aloe leaf (AW) and quercetin itself. AF exerted a synergistic effect with quercetin and bioactive substances derived from the fermentation process. Moreover, mitochondrial activation of UVb-irradiated human skin fibroblasts by 0.3% (w/v) of the AF plays important roles in increasing collagen production up to 125 ± 5.45% and decreasing MMP-1 secretion down to 69.41 ± 2.63% of the control levels. The AF enhanced the upregulation of collagen gene expression, and this change was also greater than those induced by the AW and quercetin. Therefore, this study concludes that fermentation of the skin of aloe leaves increases the activation of mitochondria and inhibits the photo-aging of UVb-irradiated skin fibroblasts.

Primary Osteocyte Supernatants Metabolomic Profiling of Two Transgenic Mice With Connexin43 Dominant Negative Mutants

Osteocytes could release some small molecules (≤ 1 kDa) through gap junctions and hemichannels to extracellular environment, such as prostaglandin E2 (PGE2), nitric oxide (NO) and adenosine triphosphate (ATP), which play key roles in transferring signals between bone cells and other tissue cells. Connexin (Cx) 43 is the most abundant connexin in osteocytes. To further discover molecules released by osteocytes through Cx43 channels and better understand the regulatory function of Cx43 channels in osteocytes, we performed non-targeted global metabolomics analysis using liquid chromatography-tandem mass spectrometry (LC-MS/MS) on conditioned medium collected from osteocytes isolated from two transgenic mouse models with Cx43 dominant negative mutants driven by a 10 kb-DMP1 promoter: R76W (gap junctions are blocked, whereas hemichannels are promoted) and Δ130-136 (both gap junctions and hemichannels are blocked). The results revealed that several new categories of molecules, such as "fatty acyls" and "carboxylic acids and derivatives", could be released through osteocytic Cx43 channels. In addition, alteration of Cx43 channel function affected the release of metabolites related to inflammatory reaction and oxidative stress. Pathway analysis further showed that citric acid cycle was the most differential metabolic pathway regulated by Cx43 channels. In sum, these results isolated new potential metabolites released by osteocytes through Cx43 channels, and offered a novel perspective to understand the regulatory mechanisms of osteocytes on themselves and other cells as well.

Cellular Senescence and Inflammaging in the Skin Microenvironment

Cellular senescence and aging result in a reduced ability to manage persistent types of inflammation. Thus, the chronic low-level inflammation associated with aging phenotype is called “inflammaging”. Inflammaging is not only related with age-associated chronic systemic diseases such as cardiovascular disease and diabetes, but also skin aging. As the largest organ of the body, skin is continuously exposed to external stressors such as UV radiation, air particulate matter, and human microbiome. In this review article, we present mechanisms for accumulation of senescence cells in different compartments of the skin based on cell types, and their association with skin resident immune cells to describe changes in cutaneous immunity during the aging process.

Caffeine promotes the expression of telomerase reverse transcriptase to regulate cellular senescence and aging

Telomere shortening is one of the main causes of cellular senescence. Caffeine is a natural stimulant most commonly found in coffee and tea. In this study, caffeine was found to promote the expression of telomerase reverse transcriptase (TERT) at both mRNA and protein levels, and consequently extended the telomere length and prevented cellular senescence. Knockdown of TERT eliminated the effect of caffeine on telomere elongation. Moreover, animal studies indicated that caffeine promoted the expression of TERT and extended the telomere length in the thymus and spleen of mice treated with caffeine for a long period of eight months. In addition, caffeine restored the decline of organ index and improved the histological structural change of the thymus, spleen and liver of mice due to aging. These results suggest that caffeine promotes the expression of TERT to delay cellular senescence and aging, which help to understand the mechanism for the beneficial effects of caffeine containing foods on health.

Skin Pigmentation Abnormalities and Their Possible Relationship with Skin Aging

Skin disorders showing abnormal pigmentation are often difficult to manage because of their uncertain etiology or pathogenesis. Abnormal pigmentation is a common symptom accompanying aging skin. The association between skin aging and skin pigmentation abnormalities can be attributed to certain inherited disorders characterized by premature aging and abnormal pigmentation in the skin and some therapeutic modalities effective for both. Several molecular mechanisms, including oxidative stress, mitochondrial DNA mutations, DNA damage, telomere shortening, hormonal changes, and autophagy impairment, have been identified as involved in skin aging. Although each of these skin aging-related mechanisms are interconnected, this review examined the role of each mechanism in skin hyperpigmentation or hypopigmentation to propose the possible association between skin aging and pigmentation abnormalities.

The Role of Autophagy in Skin Fibroblasts, Keratinocytes, Melanocytes, and Epidermal Stem Cells

Human skin acts as a barrier to protect our bodies from UV rays and external pathogens and to prevent water loss. Phenotypes of aging, or natural aging due to chronic damage, include wrinkles and the reduction of skin thickness that occur because of a loss of skin cell function. The dysregulation of autophagy, a lysosome-related degradation pathway, can lead to cell senescence, cancer, and various human diseases due to abnormal cellular homeostasis. Here, we discuss the roles and molecular mechanisms of autophagy involved in the anti-aging effects of autophagy and the relationship between autophagy and aging in skin cells.

Nicotinamide Mononucleotide Combined With Lactobacillus fermentum TKSN041 Reduces the Photoaging Damage in Murine Skin by Activating AMPK Signaling Pathway

Long-term exposure to UVB (280-320 nm) can cause oxidative skin damage, inflammatory injury, and skin cancer. Research on nicotinamide mononucleotide (NMN) and lactic acid bacteria (LAB) with regard to antioxidation, anti-inflammation, and prevention of other age-related diseases has received increasing attention. In the present study, the in vitro antioxidant analysis showed that NMN combined with Lactobacillus fermentum TKSN041 (L. fermentum TKSN041) has a high scavenging ability on hydroxyl (OH), 2, 2'-azino-bis (3-ethylbenzthiazoline-6-sulphonic acid) diammonium salt (ABTS) and 1, 1-diphenyl-2-picrylhydrazyl (DPPH), and it also possess a good total antioxidant capacity. The animal experimental results show that NMN combined with LAB maintained normal liver morphology of mice and reduced pathological damage to murine skin. NMN combined with LAB significantly increased the serum levels of total superoxide dismutase (T-SOD), catalase (CAT), and interleukin (IL)-10, but reduced the levels of malondialdehyde, advanced glycation end products, tumor necrosis factor (TNF)-α, and IL-6. NMN combined with LAB increased T-SOD, CAT, IL-10, Na⁺-K⁺-ATPase, and NAD⁺ levels in the skin, but reduced TNF-α level in the skin. NMN combined with LAB increased the mRNA expression levels of SOD1, CAT, glutathione (GSH), inhibitor of NF-κB (IκB-α), IL-10, AMP-activated protein kinase (AMPK), adaptor protein, phosphotyros ineinteraction, PH domain and leucine zipper containing 1 (APPL1), peroxisome proliferator-activated receptor γ co-activator-1α (PGC-1α), and forkhead transcription factor O (FOXO) in the skin and liver, but decreased the mRNA expression levels of nuclear factor (NF)-κBp65, TNF-α, IL-6, and rapamycin target protein (mTOR). NMN combined with LAB increased the protein expression levels of AMPK, IκB-α, SOD1, and CAT in the skin tissues and reduced protein expression of NF-κBp65. NMN combined with L. fermentum TKSN041 improved murine skin damage caused by UVB irradiation, and the protective mechanism may be related to activation of the AMPK signaling pathway. The results of this study are expected to provide a reference for preventing and the treating skin photoaging.

Research progress of keratinocyte-programmed cell death in UV-induced Skin photodamage

Programmed cell death (PCD) is a basic component of life and an important terminal path for cells. A variety of biological events are associated with PCD, including the conservation of tissue homeostasis and removal of harmful cells. Overexposure of the skin to UV radiation causes skin photodamage. Keratinocytes are the first line of defence against ultraviolet radiation. During UV radiation, the keratinocyte can undergo four modes of PCD: apoptosis, pyroptosis, necroptosis and autophagy. The molecular mechanisms of these four modes of PCD have been widely studied as potential therapeutic targets for the prevention of UV-induced skin inflammation, ageing and skin cancer. In this review, we summarize the role of keratinocyte PCD in the pathogenesis of UV-induced skin photodamage. This article will provide new research directions for the design of intervention strategies for the treatment and prevention of skin photodamage.

Key Signaling Pathways in Aging and Potential Interventions for Healthy Aging

Aging is a fundamental biological process accompanied by a general decline in tissue function. Indeed, as the lifespan increases, age-related dysfunction, such as cognitive impairment or dementia, will become a growing public health issue. Aging is also a great risk factor for many age-related diseases. Nowadays, people want not only to live longer but also healthier. Therefore, there is a critical need in understanding the underlying cellular and molecular mechanisms regulating aging that will allow us to modify the aging process for healthy aging and alleviate age-related disease. Here, we reviewed the recent breakthroughs in the mechanistic understanding of biological aging, focusing on the adenosine monophosphate-activated kinase (AMPK), Sirtuin 1 (SIRT1) and mammalian target of rapamycin (mTOR) pathways, which are currently considered critical for aging. We also discussed how these proteins and pathways may potentially interact with each other to regulate aging. We further described how the knowledge of these pathways may lead to new interventions for antiaging and against age-related disease.

Lifetime Impact of Cow's Milk on Overactivation of mTORC1: From Fetal to Childhood Overgrowth, Acne, Diabetes, Cancers, and Neurodegeneration

The consumption of cow's milk is a part of the basic nutritional habits of Western industrialized countries. Recent epidemiological studies associate the intake of cow's milk with an increased risk of diseases, which are associated with overactivated mechanistic target of rapamycin complex 1 (mTORC1) signaling. This review presents current epidemiological and translational evidence linking milk consumption to the regulation of mTORC1, the master-switch for eukaryotic cell growth. Epidemiological studies confirm a correlation between cow's milk consumption and birthweight, body mass index, onset of menarche, linear growth during childhood, acne vulgaris, type 2 diabetes mellitus, prostate cancer, breast cancer, hepatocellular carcinoma, diffuse large B-cell lymphoma, neurodegenerative diseases, and all-cause mortality. Thus, long-term persistent consumption of cow's milk increases the risk of mTORC1-driven diseases of civilization. Milk is a highly conserved, lactation genome-controlled signaling system that functions as a maternal-neonatal relay for optimized species-specific activation of mTORC1, the nexus for regulation of eukaryotic cell growth, and control of autophagy. A deeper understanding of milk´s impact on mTORC1 signaling is of critical importance for the prevention of common diseases of civilization.

Synergistic Effects of Milk-Derived Exosomes and Galactose on α-Synuclein Pathology in Parkinson's Disease and Type 2 Diabetes Mellitus

Epidemiological studies associate milk consumption with an increased risk of Parkinson's disease (PD) and type 2 diabetes mellitus (T2D). PD is an α-synucleinopathy associated with mitochondrial dysfunction, oxidative stress, deficient lysosomal clearance of α-synuclein (α-syn) and aggregation of misfolded α-syn. In T2D, α-syn promotes co-aggregation with islet amyloid polypeptide in pancreatic β-cells. Prion-like vagal nerve-mediated propagation of exosomal α-syn from the gut to the brain and pancreatic islets apparently link both pathologies. Exosomes are critical transmitters of α-syn from cell to cell especially under conditions of compromised autophagy. This review provides translational evidence that milk exosomes (MEX) disturb α-syn homeostasis. MEX are taken up by intestinal epithelial cells and accumulate in the brain after oral administration to mice. The potential uptake of MEX miRNA-148a and miRNA-21 by enteroendocrine cells in the gut, dopaminergic neurons in substantia nigra and pancreatic β-cells may enhance miRNA-148a/DNMT1-dependent overexpression of α-syn and impair miRNA-148a/PPARGC1A- and miRNA-21/LAMP2A-dependent autophagy driving both diseases. MiRNA-148a- and galactose-induced mitochondrial oxidative stress activate c-Abl-mediated aggregation of α-syn which is exported by exosome release. Via the vagal nerve and/or systemic exosomes, toxic α-syn may spread to dopaminergic neurons and pancreatic β-cells linking the pathogenesis of PD and T2D.

Synergistic neuroprotective effect of schisandrin and nootkatone on regulating inflammation, apoptosis and autophagy via the PI3K/AKT pathway

Alzheimer's disease (AD) is a neurodegenerative disease that seriously threatens elderly health. Schisandrin (SCH) and nootkatone (NKT) are two core components derived from Alpinia oxyphylla-Schisandra chinensis herb pair (ASHP), a traditional Chinese medicine formulation. Previous studies demonstrated that the combination of NKT and SCH exerted a neuroprotective effect in AD mouse models. The present study was undertaken to investigate whether there was a synergistic effect between NKT and SCH and the possible mechanism in Aβ1-42 induced PC12 cells. SCH (50 μM) and NKT (10 μM) had the most notable inhibitory effect on the level of Aβ secreted by cells. Treatment with NKT + SCH activated the PI3K/AKT/Gsk-3β/mTOR pathway. Inflammation related proteins such as NF-κB, IKK, IL-1β, IL-6 and TNF-α were decreased. The levels of cleaved-Caspase3 and LC3-II were reduced, indicating that apoptosis and autophagy were inhibited. These results revealed that NKT + SCH exerted a neuroprotective effect via the PI3K/AKT pathway, inhibiting inflammation, apoptosis and autophagy.

Caffeine and Parkinson's Disease: Multiple Benefits and Emerging Mechanisms

Parkinson’s disease (PD) is the second most common neurodegenerative disorder, characterized by dopaminergic neurodegeneration, motor impairment and non-motor symptoms. Epidemiological and experimental investigations into potential risk factors have firmly established that dietary factor caffeine, the most-widely consumed psychoactive substance, may exerts not only neuroprotective but a motor and non-motor (cognitive) benefits in PD. These multi-benefits of caffeine in PD are supported by convergence of epidemiological and animal evidence. At least six large prospective epidemiological studies have firmly established a relationship between increased caffeine consumption and decreased risk of developing PD. In addition, animal studies have also demonstrated that caffeine confers neuroprotection against dopaminergic neurodegeneration using PD models of mitochondrial toxins (MPTP, 6-OHDA, and rotenone) and expression of α-synuclein (α-Syn). While caffeine has complex pharmacological profiles, studies with genetic knockout mice have clearly revealed that caffeine’s action is largely mediated by the brain adenosine A_2A receptor (A_2AR) and confer neuroprotection by modulating neuroinflammation and excitotoxicity and mitochondrial function. Interestingly, recent studies have highlighted emerging new mechanisms including caffeine modulation of α-Syn degradation with enhanced autophagy and caffeine modulation of gut microbiota and gut-brain axis in PD models. Importantly, since the first clinical trial in 2003, United States FDA has finally approved clinical use of the A_2AR antagonist istradefylline for the treatment of PD with OFF-time in Sept. 2019. To realize therapeutic potential of caffeine in PD, genetic study of caffeine and risk genes in human population may identify useful pharmacogenetic markers for predicting individual responses to caffeine in PD clinical trials and thus offer a unique opportunity for “personalized medicine” in PD.

Sénothérapies

Bien que la sénescence cellulaire joue un rôle essentiel dans le développent embryonnaire, la cicatrisation ou l’hémostase, il est maintenant également démontré qu’elle est à l’origine de nombreux processus dégénératifs qui caractérisent le vieillissement. Cette sénescence est induite en réponse à divers stress ou stimulus inappropriés, conduisant à un arrêt de la prolifération et des adaptations géniques, épigénétiques, métaboliques, structurelles et fonctionnelles. Ces cellules sénescentes, lorsqu’elles ne sont pas éliminées, favorisent la propagation de leur phénotype de proche en proche dans le tissu environnant, par l’établissement d’un profil sécrétoire spécifique. Éliminer ou bloquer l’action de ces cellules par des agents dits sénothérapeutiques pourrait prévenir la dégénérescence tissulaire et améliorer la longévité en bonne santé. Nous nous proposons dans cette revue de présenter les dernières avancées et applications développées en sénothérapie et discuterons les résultats très prometteurs des premiers essais cliniques chez l’homme.

The bright and dark side of skin senescence. Could skin rejuvenation anti-senescence interventions become a "bright" new strategy for the prevention of age-related skin pathologies?

The number of senescent cells in the skin is increasing with age. Numerous studies have attempted to elucidate the role of these cells in normal aging of the skin as well as in age-related skin conditions. In recent years, attempts have also been made to find treatments that aim either to cleanse the skin tissues of senescent cells or to neutralize their effects (referred to as senolytics and senomorphics respectively) and thus prevent the consequences, particularly on the skin's appearance in advanced age. Through this review, we have tried to gather data on the role of senescent cells in the skin, in treatments aimed at removing them, and we are asking a reasonable question as to whether anti-senescence treatments may contribute to the protection against age-related skin pathologies, including skin cancer, such as non-melanoma skin cancer, in addition to their involvement in skin rejuvenation.

Caffeine Targets G6PDH to Disrupt Redox Homeostasis and Inhibit Renal Cell Carcinoma Proliferation

Glucose-6-phosphate dehydrogenase (G6PDH) is the rate-limiting enzyme in the pentose phosphate pathway (PPP) and plays a crucial role in the maintenance of redox homeostasis by producing nicotinamide adenine dinucleotide phosphate (NADPH), the major intracellular reductant. G6PDH has been shown to be a biomarker and potential therapeutic target for renal cell carcinoma (RCC). Here, we report a previously unknown biochemical mechanism through which caffeine, a well-known natural small molecule, regulates G6PDH activity to disrupt cellular redox homeostasis and suppress RCC development and progression. We found that caffeine can inhibit G6PDH enzymatic activity. Mechanistically, caffeine directly binds to G6PDH with high affinity (K _D = 0.1923 μM) and competes with the coenzyme NADP⁺ for G6PDH binding, as demonstrated by the decreased binding affinities of G6PDH for its coenzyme and substrate. Molecular docking studies revealed that caffeine binds to G6PDH at the structural NADP⁺ binding site, and chemical cross-linking analysis demonstrated that caffeine inhibits the formation of dimeric G6PDH. G6PDH inhibition abrogated the inhibitory effects of caffeine on RCC cell growth. Moreover, inhibition of G6PDH activity by caffeine led to a reduction in the intracellular levels of NADPH and reactive oxygen species (ROS), and altered the expression of redox-related proteins in RCC cells. Accordingly, caffeine could inhibit tumor growth through inhibition of G6PDH activity in vivo. Taken together, these results demonstrated that caffeine can target G6PDH to disrupt redox homeostasis and inhibit RCC tumor growth, and has potential as a therapeutic agent for the treatment of RCC.

Matrine attenuates cardiomyocyte ischemia-reperfusion injury through activating AMPK/Sirt3 signaling pathway

Matrine has been found to affect cell viability and function. In the present study, we explored the cardioprotective role of matrine in cardiomyocyte damage under hypoxia/reoxygenation. In vitro, cardiomyocyte hypoxia/reoxygenation was used to mimic ischemia/reperfusion injury in the presence of matrine. After exposure to hypoxia/reoxygenation, cardiomyocyte viability was reduced and cell apoptosis was increased; this alteration was inhibited by matrine. At the molecular levels, Sirt3 and AMPK were significantly downregulated by hypoxia/reoxygenation injury whereas matrine administration was able to upregulate Sirt3 and AMPK expression and activity in the presence of hypoxia/reoxygenation. Interestingly, inhibition of Sirt3/AMPK pathway abolished the cardioprotective action of matrine on cardiomyocyte in the presence of hypoxia/reoxygenation injury, resulting into cardiomyocyte viability reduction and cell death augmentation. Altogether, our results demonstrated a novel role played by matrine in regulating cardiomyocyte viability and death in the presence of hypoxia/reoxygenation, with a potential application in the clinical practice for the treatment of patients with myocardial infarction.

Intracellular calcium current disorder and disease phenotype in OBSCN mutant iPSC-based cardiomyocytes in arrhythmogenic right ventricular cardiomyopathy

Obscurin participates in the development of striated muscles and maintenance of the functional sarcoplasmic reticulum. However, the role of obscurin in arrhythmogenic right ventricular cardiomyopathy (ARVC) is not well understood. We aimed to study the novel obscurin mutations in the pathogenesis of ARVC and the underlying mechanisms. Methods: We generated induced pluripotent stem cells (iPSC) through retroviral reprogramming of peripheral blood mononuclear cells isolated from a 46-year-old female diagnosed with ARVC, carrying a mutation in OBSCN. The cells differentiated into functional iPSC-based cardiomyocytes (iPSC-CMs), whose phenotype was determined by transmission electron microscopy, electrophysiological description, immunofluorescence staining, and Oil Red O staining. Molecular characterization was performed by bioinformatic analyses, and identification by quantitative real-time polymerase chain reaction (qRT-PCR) and Western blotting. Results: ARVC-iPSC-CMs mutation in OBSCN showed significant accumulation of lipids, increased pleomorphism, irregular Z-bands, and increased L type calcium currents. Functional enrichment analysis identified pathways involved in focal adhesion and structure formation; the adipocytokines and PPAR signaling pathways were also activated in the ARVC group. Moreover, our results from ultra-high-resolution microscopy, qRT-PCR and Western blotting confirmed that the mutant OBSCN protein and its anchor protein, Ank1.5, showed structural disorder and decreased expression, but there was increased expression of junctional protein N-Cadherin. Further analysis revealed the gene expression of other desmosomal proteins in ARVC-iPSC-CMs was also decreased but some adipogenesis pathway-related proteins (PPARγ, C/EBPα, and FABP4) were increased. Conclusion: A novel frameshift mutation in OBSCN caused phenotypic alteration accompanied by disrupted localization and decreased expression of its anchoring protein Ank1.5. Furthermore, there was an accumulation of lipids with an increase in fatty fibrosis area and myocardial structural disorder, possibly leading to dysrhythmia in calcium channel-related myocardial contraction. These observations suggested the possibility of attenuating ARVC progression by therapeutic modulation of OBSCN expression.

Caffeine Targets SIRT3 to Enhance SOD2 Activity in Mitochondria

Caffeine is chemically stable and not readily oxidized under normal physiological conditions but also has antioxidant effects, although the underlying molecular mechanism is not well understood. Superoxide dismutase (SOD) 2 is a manganese-containing enzyme located in mitochondria that protects cells against oxidative stress by scavenging reactive oxygen species (ROS). SOD2 activity is inhibited through acetylation under conditions of stress such as exposure to ultraviolet (UV) radiation. Sirtuin 3 (SIRT3) is the major mitochondrial nicotinamide adenine dinucleotide (NAD⁺)-dependent deacetylase, which deacetylates two critical lysine residues (lysine 68 and lysine 122) on SOD2 and promotes its antioxidative activity. In this study, we investigated whether the antioxidant effect of caffeine involves modulation of SOD2 by SIRT3 using in vitro and in vivo models. The results show that caffeine interacts with SIRT3 and promotes direct binding of SIRT3 with its substrate, thereby enhancing its enzymatic activity. Mechanistically, caffeine bound to SIRT3 with high affinity (K_D = 6.858 × 10^–7 M); the binding affinity between SIRT3 and its substrate acetylated p53 was also 9.03 (without NAD⁺) or 6.87 (with NAD⁺) times higher in the presence of caffeine. Caffeine effectively protected skin cells from UV irradiation-induced oxidative stress. More importantly, caffeine enhanced SIRT3 activity and reduced SOD2 acetylation, thereby leading to increased SOD2 activity, which could be reversed by treatment with the SIRT3 inhibitor 3-(1H-1,2,3-triazol-4-yl) pyridine (3-TYP) in vitro and in vivo. Taken together, our results show that caffeine targets SIRT3 to enhance SOD2 activity and protect skin cells from UV irradiation-induced oxidative stress. Thus, caffeine, as a small-molecule SIRT3 activator, could be a potential agent to protect human skin against UV radiation.

NOX1 down-regulation attenuated the autophagy and oxidative damage in pig intestinal epithelial cell following transcriptome analysis of transport stress

The previous study indicated that transport stress resulted in oxidative damage and autophagy/mitophagy elevation, companied by NOX1 over- expression in the jejunal tissues of pigs. However, the transportation-related gene expression profile and NOX1 function in intestine remain to be explicated. In the current study, differentially expressed genes involved in PI3K-Akt and NF-κB pathways, oxidative stress and autophagy process have been identified in pig jejunal tissues after transcriptome analysis following transportation. The physiological functions of NOX1 down-regulation were explored against oxidative damage and excessive autophagy in porcine intestinal epithelial cells (IPEC-1) following NOX1 inhibitor ML171 and H₂O₂ treatments. NOX1 down-regulation could decrease the content of Malondialdehyde (MDA), Lactic dehydrogenase (LDH) activity and reactive oxygen species (ROS) level, and up-regulate superoxide dismutase (SOD) activity. Furthermore, mitochondrial membrane potential and content were restored, and the expressions of tight junction proteins (Claudin-1 and ZO-1) were also increased. Additionally, NOX1 inhibitior could down-regulate the expression of autophagy-associated proteins (ATG5, LC3, p62), accompanied by activating SIRT1/PGC-1α pathway. NOX1 down-regulation might alleviate oxidative stress-induced mitochondria damage and intestinal mucosal injury via modulating excessive autophagy and SIRT1/PGC-1α signaling pathway. The data will shed light on the molecular mechanism of NOX1 on intestine oxidative damage following pig transportation.

The effect of Yang Yan Qing E Wan on senescent phenotypes and the expression of β-catenin and p16INK4a in human skin fibroblasts

This aim of this study was to observe the effect of Yang Yan Qing E Wan (YYQEW) on senescent phenotypes and the expression of β-catenin and p16^INK4a in the hydrogen peroxide (H₂O₂)-induced premature senescence of normal human skin fibroblasts (NHSFs). Primary normal human skin fibroblasts were randomly divided into a normal group, a blank group, a model group, and a YYQEW group. The cells of the model group and the YYQEW group were exposed to 150 μmol/L H₂O₂ for 2 h. The morphological changes of the cells were analyzed by microscopy and by kits used to estimate the activities of the senescence-associated β-galactosidase (SA-β-gal), reactive oxygen species (ROS), and superoxide dismutase (SOD). The outcomes revealed that dyeing rate proportion of SA-β-gal was 2.78% ± 0.22% in the normal group, 2.83% ± 0.29% in the blank group, 37.58% ± 2.56% in the model group, and 28.39% ± 0.93% in the YYQEW group. The number of SA-β-gal positive cells was thus significantly higher in the model group than in the normal or blank group. There were also fewer SA-β-gal positive cells in the YYQEW group compared with the model group. The expression of ROS and p16^INK4a in the model group increased significantly compared with that in the normal or blank groups, while the expression of ROS and p16^INK4a in the YYQEW group decreased significantly compared with that in the model group. The expression of SOD and β-catenin in the model group decreased significantly compared with that in the normal or blank group, and the expression of SOD and β-catenin in the YYQEW group increased significantly compared with that in the model group. Overall, it was found that YYQEW was able to delay the senescence of NHSFs induced by H₂O₂ treatment by alleviating oxidative stress and regulating a number of senescence-related molecules, such as β-catenin and p16^INK4a.

Blockade of Adenosine A2A Receptor Protects Photoreceptors after Retinal Detachment by Inhibiting Inflammation and Oxidative Stress

Purpose

Adenosine A_2A receptor (A_2AR) signaling is neuroprotective in some retinal damage models, but its role in neuronal survival during retinal detachment (RD) is unclear. We tested the hypothesis that A_2AR antagonist ZM241385 would prevent photoreceptor apoptosis by inhibiting retinal inflammation and oxidative stress after RD.

Methods

The A_2AR antagonist ZM241385 was delivered daily to C57BL/6J mice for three days at a dose (3 mg/kg, i.p.) starting 2 hours prior to creating RD. A_2AR expression, microglia proliferation and reactivity, glial fibrillary acidic protein (GFAP) accumulation, IL-1β expression, and reactive oxygen species (ROS) production were evaluated with immunofluorescence. Photoreceptor TUNEL was analyzed.

Results

A_2AR expression obviously increased and accumulated in microglia and Müller cells in the retinas after RD. The A_2AR antagonist ZM241385 effectively inhibited retinal microglia proliferation and reactivity, decreased GFAP upregulation and proinflammatory cytokine IL-1β expression of Müller cells, and suppressed ROS overproduction, resulting in attenuation of photoreceptor apoptosis after RD.

Conclusions

The A_2AR antagonist ZM241385 is an effective suppressor of microglia proliferation and reactivity, gliosis, neuroinflammation, oxidative stress, and photoreceptor apoptosis in a mouse model of RD. This suggests that A_2AR blockade may be an important therapeutic strategy to protect photoreceptors in RD and other CNS diseases that share a common etiology.

Self-eating: friend or foe? The emerging role of autophagy in fibrotic diseases

Fibrosis occurs in most human organs including the liver, lung, heart and kidney, and is crucial for the progression of most chronic diseases. As an indispensable catabolic process for intracellular quality control and homeostasis, autophagy occurs in most mammalian cells and is implicated in many biological processes including fibrogenesis. Although advances have been made in understanding autophagy process, the potential role of autophagy in fibrotic diseases remains controversial and has recently attracted a great deal of attention. In the current review, we summarize the commonalities of autophagy affecting different types of fibrosis in different organs, including the liver, lung, heart, and kidney as well as in cystic fibrosis, systematically outline the contradictory results and highlight the distinct role of autophagy during the various stages of fibrosis. In summary, the exact role autophagy plays in fibrogenesis depends on specific cell types and different stimuli, and identifying and evaluating the pathogenic contribution of autophagy in fibrogenesis will promote the discovery of novel therapeutic strategies for the clinical management of these fibrotic diseases.

Caffeine inhibits the anticancer activity of paclitaxel via down-regulation of α-tubulin acetylation

Caffeine (1,3,7-trimethylxanthine) is a xanthine alkaloid found in a number of dietary products consumed worldwide, such as coffee, tea, and soft beverages, and is known to act as a modifying agent for cytotoxic chemotherapeutic drugs. Studies have shown that caffeine reduces the cytotoxic effects of paclitaxel and inhibits paclitaxel-induced apoptosis; however, the underlying mechanism remains unclear. Here, we investigated whether caffeine inhibits the antitumor activity of paclitaxel via down-regulation of α-tubulin acetylation. In vitro studies, involving MTT assay, wound-healing assay, cell apoptosis assay, and western blotting analysis of A549 and HeLa cells, were performed. A549 and HeLa cell-based xenografts were established, and western blotting and immunohistochemical staining were performed for in vivo studies. The results showed that caffeine promoted the growth of cancer cells treated with paclitaxel. Additionally, caffeine enhanced migration ability, inhibited apoptosis, and decreased the acetylation of α-tubulin in paclitaxel-treated cancer cells. Furthermore, caffeine decreased the inhibitory effect of paclitaxel on tumor growth through down-regulation of α-tubulin acetylation in vivo. Taken together, these findings demonstrate that caffeine inhibits the anticancer activity of paclitaxel via down-regulation of α-tubulin acetylation, suggesting that patients receiving treatment with taxanes, such as paclitaxel, should avoid consuming caffeinated beverages or foods.