Aspirin may promote mitochondrial biogenesis via the production of hydrogen peroxide and the induction of Sirtuin1/PGC-1α genes

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.

Alzheimer’s Amyloid-β Accelerates Cell Senescence and Suppresses the SIRT1/NRF2 Pathway in Human Microglial Cells

Microglia play important roles in maintenance of brain homeostasis, while due to some pathological stimuli in aging-related neurodegenerative diseases including Alzheimer's disease, they are malfunctioning. Here, we demonstrated that amyloid-β (Aβ) accelerated cell senescence characterized by the upregulation of p21 and PAI-1 as well as senescence-associated beta-galactosidase (SA-β-gal) in human microglial cells. Consistently, Aβ induced the senescence-associated mitochondrial dysfunctions such as repression of ATP production, oxygen consumption rate (OCR), and mitochondrial membrane potential and enhancement of ROS production. Furthermore, Aβ was found to significantly suppress mRNA expression and protein level of Sirtuin-1 (SIRT1), a key regulator of senescence, and inhibit mRNA expression and translocation of NRF2, a critical transcription factor in inflammatory responses, leading to impairment of phagocytosis. Rescue of SIRT1, as expected, could counteract the pathological effects of Aβ. In summary, our findings revealed that Aβ accelerates human microglial senescence mainly through its suppression of the SIRT1/NRF2 pathway and suggested that genetic and pharmaceutical rescue of SIRT1 may provide a potential alternative treatment.

Alterations in Energy Metabolism, Mitochondrial Function and Redox Homeostasis in GK Diabetic Rat Tissues Treated with Aspirin

Our recent studies have demonstrated that aspirin treatment prevents inflammatory and oxidative stress-induced alterations in mitochondrial function, improves glucose tolerance and pancreatic endocrine function and preserves tissue-specific glutathione (GSH)-dependent redox homeostasis in Goto-Kakizaki (GK) diabetic rats. In the current study, we have investigated the mechanism of action of aspirin in maintaining mitochondrial bioenergetics and redox metabolism in the liver and kidneys of GK rats. Aspirin reduced the production of reactive oxygen species (ROS) and oxidative stress-induced changes in GSH metabolism. Aspirin treatment also improved mitochondrial respiratory function and energy metabolism, in addition to regulating the expression of cell signaling proteins that were altered in diabetic animals. Ultrastructural electron microscopy studies revealed decreased accumulation of glycogen in the liver of aspirin-treated diabetic rats. Hypertrophic podocytes with irregular fusion of foot processes in the renal glomerulus and detached microvilli, condensed nuclei and degenerated mitochondria observed in the proximal convoluted tubules of GK rats were partially restored by aspirin. These results provide additional evidence to support our previous observation of moderation of diabetic complications by aspirin treatment in GK rats and may have implications for cautious use of aspirin in the therapeutic management of diabetes.

Delayed administration of N-acetylcysteine blunts recovery after an acetaminophen overdose unlike 4-methylpyrazole

N-acetylcysteine (NAC) is the only clinically approved antidote against acetaminophen (APAP) hepatotoxicity. Despite its efficacy in patients treated early after APAP overdose, NAC has been implicated in impairing liver recovery in mice. More recently, 4-methylpyrazole (4MP, Fomepizole) emerged as a potential antidote in the mouse APAP hepatotoxicity model. The objective of this manuscript was to verify the detrimental effect of NAC and its potential mechanism and assess whether 4MP has the same liability. C57BL/6J mice were treated with 300 mg/kg APAP; 9h after APAP and every 12h after that, the animals received either 100 mg/kg NAC or 184.5 mg/kg 4MP. At 24 or 48h after APAP, parameters of liver injury, mitochondrial biogenesis and cell proliferation were evaluated. Delayed NAC treatment had no effect on APAP-induced liver injury at 24h but reduced the decline of plasma ALT activities and prevented the shrinkage of the areas of necrosis at 48h. This effect correlated with down-regulation of key activators of mitochondrial biogenesis (AMPK, PGC-1α, Nrf1/2, TFAM) and reduced expression of Tom 20 (mitochondrial mass) and PCNA (cell proliferation). In contrast, 4MP attenuated liver injury at 24h and promoted recovery at 48h, which correlated with enhanced mitochondrial biogenesis and hepatocyte proliferation. In human hepatocytes, 4MP demonstrated higher efficacy in preventing cell death compared to NAC when treated at 18h after APAP. Thus, due to the wider treatment window and lack of detrimental effects on recovery, it appears that at least in preclinical models, 4MP is superior to NAC as an antidote against APAP overdose.

A comprehensive guide to the pharmacologic regulation of angiotensin converting enzyme 2 (ACE2), the SARS-CoV-2 entry receptor

The recent emergence of coronavirus disease-2019 (COVID-19) as a global pandemic has prompted scientists to address an urgent need for defining mechanisms of disease pathology and treatment. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causative agent for COVID-19, employs angiotensin converting enzyme 2 (ACE2) as its primary target for cell surface attachment and likely entry into the host cell. Thus, understanding factors that may regulate the expression and function of ACE2 in the healthy and diseased body is critical for clinical intervention. Over 66% of all adults in the United States are currently using a prescription drug and while earlier findings have focused on possible upregulation of ACE2 expression through the use of renin angiotensin system (RAS) inhibitors, mounting evidence suggests that various other widely administered drugs used in the treatment of hypertension, heart failure, diabetes mellitus, hyperlipidemias, coagulation disorders, and pulmonary disease may also present a varied risk for COVID-19. Specifically, we summarize mechanisms on how heparin, statins, steroids and phytochemicals, besides their established therapeutic effects, may also interfere with SARS-CoV-2 viral entry into cells. We also describe evidence on the effect of several vitamins, phytochemicals, and naturally occurring compounds on ACE2 expression and activity in various tissues and disease models. This comprehensive review aims to provide a timely compendium on the potential impact of commonly prescribed drugs and pharmacologically active compounds on COVID-19 pathology and risk through regulation of ACE2 and RAS signaling.

Aspirin alleviates denervation-induced muscle atrophy via regulating the Sirt1/PGC-1α axis and STAT3 signaling

Background

Our prior studies have shown that inflammation may play an important triggering role during the process of denervated muscle atrophy. The nonsteroidal anti-inflammatory drug aspirin exhibits the effect of anti-inflammatory factors. This study will investigate the protective effect of aspirin on denervated muscle atrophy and the underlying mechanism.

Methods

Mouse models of denervated muscle atrophy were established. The protective effect of aspirin (20 mg/kg/d, i.p.) on denervated muscle atrophy was analyzed using the wet weight ratio of tibialis anterior (TA) muscle and muscle fiber cross-sectional area (CSA). The levels of inflammatory factors were detected using quantitative reverse transcription-polymerase chain reaction and enzyme-linked immunosorbent assay. Sirtuins1 (SIRT1)/Peroxisome Proliferator-Activated Receptor γ Co-Activator 1α (PGC-1α) and Signal transducer and activator of transcription 3 (STAT3) signaling pathway and the muscle fiber type related proteins in TA muscle after denervation were analyzed by western blot assay.

Results

Intraperitoneal injection of aspirin (20 mg/kg/d) effectively alleviated denervation-induced muscle atrophy. This mainly manifested as follows: The wet weight ratio of TA muscle and muscle fiber CSA of mice treated with aspirin were significantly greater compared with mice treated with normal saline. The level of myosin heavy chain (MHC) increased, and the levels of muscle specific E3 ubiquitin ligase Muscle-specific RING finger-1 (MuRF-1) and muscle atrophy F-box (MAFbx) were decreased. Mitochondrial vacuolation and autophagy were inhibited, as evidenced by reduced level of autophagy related proteins PINK1, BNIP3, LC3B and Atg7 in mice treated with aspirin compared with mice treated with saline. In addition, aspirin treatment inhibited the slow-to-fast twitch muscle fiber conversion, which were related with triggering the expression of Sirt1 and PGC-1α. Moreover, aspirin reduced the levels of inflammatory factors interleukin-6, interleukin-1β and tumor necrosis factor-α and decreased the activation of STAT3 signaling pathway.

Conclusions

This is the first study to find that aspirin can alleviate denervation-induced muscle atrophy and inhibit the type I-to-type II muscle fiber conversion and mitophagy possibly through regulating the STAT3 inflammatory signaling pathway and Sirt1/PGC-1α signal axis. This study expands our knowledge regarding the pharmacological function of aspirin and provides a novel strategy for prevention and treatment of denervated muscle atrophy.

Polyphenols by Generating H2O2, Affect Cell Redox Signaling, Inhibit PTPs and Activate Nrf2 Axis for Adaptation and Cell Surviving: In Vitro, In Vivo and Human Health

Human health benefits from different polyphenols molecules consumption in the diet, derived mainly by their common activities in the gastrointestinal tract and at the level of blood micro-capillary. In the stomach, intestine and colon, polyphenols act as reducing agents preventing lipid peroxidation, generation and absorption of AGEs/ALEs (advanced glycation end products/advanced lipid oxidation end products) and postprandial oxidative stress. The low absorption of polyphenols in blood does not support their activity as antioxidants and their mechanism of activity is not fully understood. The results are from in vitro, animal and human studies, detected by relevant oxidative stress markers. The review carries evidences that polyphenols, by generating H₂O₂ at nM concentration, exogenous to cells and organs, act as activators of signaling factors increasing cell Eustress. When polyphenols attain high concentration in the blood system, they generate H₂O₂ at µM concentration, acting as cytotoxic agents and Distress. Pre-treatment of cells or organisms with polyphenols, by generating H₂O₂ at low levels, inhibits cellular PTPs (protein tyrosine phosphatases), inducing cell signaling through transcription of the Nrf2 (nuclear factor erythroid 2-related factor 2) axis of adaptation and protection to oxidation stress. Polyphenols ingestion at the right amount and time during the meal acts synergistically at the level of the gastrointestinal tract (GIT) and blood system, for keeping the redox homeostasis in our organism and better balancing human health.

Responses of the Nrf2/Keap1 signaling pathway in Mugilogobius abei (M. abei) exposed to environmentally relevant concentration aspirin

Aspirin (ASA) is a widely used non-steroidal anti-inflammatory drug. Its high detection frequency in various waterborne and environmental residues has drawn wide attention. Limited information were provided for the effects of aspirin exposure on oxidative stress signaling pathway in fish, which is closely related to pathological and immunological process of fish. In this study, a small fish - Mugilogobius abei (M. abei) distributing widely in aquatic ecosystems in southern China, was employed as testing organism and the key genes of the detoxification metabolism were cloned for the first time. The responses of Nrf2/Keap1 signaling pathway were investigated under the environmentally relevant concentration aspirin exposure (0.5 μg L^-1, 5 μg L^-1, and 50 μg L^-1) for 24 h, 72 h, and 168 h then. The transcriptional expression of the key genes (Nrf2, Keap1, GCLC, GPx, GST, SOD, CAT, Trx2, and TrxR) as well as the changes of the related enzymatic activities (GPx, GST, SOD, and CAT) and GSH and MDA content were also determined. Results showed that Nrf2 and Keap1 gene expression displayed a negative correlation to some extent under ASA exposure, the transcriptional expressions of the downstream related genes (GCLC, GST, SOD, CAT, Trx2, and TrxR) in Nrf2/Keap1 signaling pathway showed inhibition at 24 h but induction at 72 h and 168 h. At the protein level, ASA exposure can improve the antioxidant capacity by increasing GSH synthesis and enzymatic activity of GPx, GST, SOD, and CAT to reduce the degree of lipid peroxidation. We proposed that ASA exposure may interfere with the redox balance in M. abei at an early stage but sub-chronic ASA exposure can activate the Nrf2 signaling pathway to improve the antioxidant capacity of M. abei.

The Impact of Aspirin Intake on Lactate Dehydrogenase, Arterial Stiffness, and Oxidative Stress During High-Intensity Exercise: A Pilot Study

Aspirin is a common nonsteroidal anti-inflammatory drug used to reduce fever, pain, and inflammation. However, aspirin’s anti-inflammatory properties may also prevent increased levels of blood lactate dehydrogenase, vascular arterial stiffness and oxidative stress induced by high-intensity exercise. The purpose of this study was to investigate the effects of 4 weeks of aspirin supplementation on lactate dehydrogenase activity, lactate, arterial stiffness, and antioxidant capacity during high-intensity exercise in Taekwondo athletes. Participants were randomly divided into two groups: aspirin supplementation (n = 10) and placebo-control (n = 10). Blood levels of lactate dehydrogenase (LDH) enzyme activity and lactate were assessed to examine muscle damage and carotid-to-radial pulse wave velocity and the augmentation index were measured to examine arterial stiffness. Blood levels of superoxide dismutase, malondialdehyde, and glutathione peroxidase were assessed to determine antioxidant capacity and levels of oxidative stress. There were significant group × time interactions for enzyme activity of LDH (Δ-60 ± 24.36 U/L) and carotid-to-radial pulse wave velocity (Δ-1.33 ± 0.54 m/s), which significantly decreased (p < 0.05) following aspirin supplementation compared to placebo-control. Superoxide dismutase (Δ359 ± 110 U/gHb) and glutathione peroxidase (Δ28.2 ± 10.1 U/gHb) significantly decreased while malondialdehyde (0Δ3.0 ± 0.1 mmol/mL) significantly increased (p < 0.05) in the placebo-control group compared to the supplementation group. However, there were no changes in lactate concentration levels or augmentation index. These results reveal that low-dose aspirin supplementation would be a useful supplementation therapy to prevent high-intensity exercise training-induced increases in oxidative damage, inflammation, skeletal muscle fatigue, and arterial stiffness in elite Taekwondo athletes.

Role of the aryl hydrocarbon receptor signaling pathway in promoting mitochondrial biogenesis against oxidative damage in human melanocytes

BACKGROUND

Reactive oxygen species (ROS)-induced mitochondrial damage aggravates oxidative stress and activates mitochondrial apoptosis pathway to mediate melanocyte death. However, the repair mechanisms underlying damaged mitochondria of melanocytes remain unclear. Accumulative evidence has revealed that the aryl hydrocarbon receptor (AHR), a ligand-activated transcription factor, plays a vital role in maintaining mitochondrial homeostasis.

OBJECTIVE

To investigate whether the AHR signaling pathway could protect human melanocytes from oxidative damage through controlling mitochondrial quality.

METHODS

We constructed an oxidative stress model of melanocytes with hydrogen peroxide (H₂O₂) in the human normal melanocyte PIG1 cell line, and detected ROS level, apoptosis, mitochondrial ROS level, mitochondrial membrane potential, ATP production, mitochondrial DNA and mitochondrial modulators after co-treatment with AHR ligand or antagonist and H₂O₂ in the PIG1 cells.

RESULTS

In the present study, we found that H₂O₂-induced oxidative stress directly activated the AHR signaling pathway in melanocytes, whereas abnormal activation of AHR signaling pathway enhanced oxidative damage to mitochondria and melanocytes. Further studies showed that the AHR signaling pathway promoted mitochondrial DNA synthesis and ATP production probably by regulating the expression of nuclear respiratory factor 1 (NRF1) and its downstream targets.

CONCLUSION

Our findings reveal that the AHR signaling pathway might have a major role in protecting melanocytes against oxidative damage via inducing mitochondrial biogenesis, while impaired AHR activation could cause defective repair of mitochondria and exacerbate oxidative damage-induced apoptosis in melanocytes. Our data suggest that the AHR signaling pathway might be a novel mechanism of mitochondrial biogenesis involved in protecting melanocytes from oxidative stress.

Aspirin Inhibits Natural Killer/T-Cell Lymphoma by Modulation of VEGF Expression and Mitochondrial Function

Extranodal nasal-type natural killer/T-cell lymphoma (NKTCL) is an Epstein-Barr virus (EBV)-associated lymphoma with a strong tendency relapse or be refractory in response to chemotherapy. Development of a new strategy for NKTCL treatment is still quite necessary. In this study, we found that aspirin treatment suppresses VEGF expression in NKTCL SNK-6 cells. Further investigation showed that aspirin treatment increases histone methylation in the range of −100~0 that is proximal to the transcription start site on the VEGF promoter, subsequently decreasing the binding ability of Sp1 to the VEGF promoter with VEGF suppression. Furthermore, aspirin treatment modulates mitochondrial function with increased ROS formation and apoptosis in NKTCL cells. Aspirin treatment alone slightly inhibits NKTCL SNK-6 tumor growth and EBV replication; while in the presence of histone deacetylase inhibitor (HDACi) chidamide (CDM), aspirin significantly suppresses the VEGF signaling pathway with increased ROS overgeneration and EBV inhibition. We also showed that with the addition of chidamide, aspirin significantly suppresses NKTCL tumor growth in both in vitro cell culture and in vivo mouse model with prolonged mouse survival. This is the first time that the potential mechanism for aspirin-mediated VEGF suppression and anti-tumor effect has been discovered, and this study provides a new strategy for anti-tumor drug development for NKTCL treatment based on aspirin-mediated targeting of the VEGF signaling pathway and ROS formation.

Aspirin abrogates impairment of mammary gland differentiation induced by early in life second-hand smoke in mice

Epidemiological studies show that there is limited evidence that tobacco smoking causes breast cancer in humans. In rodents, many tobacco smoke chemicals cause mammary gland tumors. This study evaluated the mammary gland differentiation in mice exposed to environmental cigarette smoke (ECS), using 3R4F Kentucky reference cigarettes, starting after birth and continuing daily for 10 weeks (total particulate exposure 95 mg/m3; CO 610 ppm). We also analyzed the effects of oral administration of non-steroidal anti-inflammatory drugs (NSAIDs), aspirin (1600 mg/kg) or naproxen (320 mg/kg), on mammary gland differentiation, either in unexposed or ECS-exposed mice. The ECS exposure caused delay of mammary glands development. We speculate that this delay may result from aryl hydrocarbon receptor (AHR) signaling activation, which has an antiestrogenic effect and crosstalk to the estrogen metabolism pathway. Similarly, naproxen impaired gland differentiation in unexposed and ECS-exposed mice, while aspirin hindered its development only in unexposed mice. The lack of differentiation induced by the NSAIDs could be explained by their antiestrogenic effect through inhibition of aldo-keto reductases. In ECS-exposed animals, aspirin induced intense lobular formation, which could indicate that aspirin is counteracting the AHR signaling induced by ECS. Based on the differentiation induced by aspirin in ECS-exposed animals, we postulate that these mice would be less susceptible to mammary carcinogenesis. Our results suggest that exposure to smoke at an early age impairs the development of the mammary gland, thus resulting in a longer period of susceptibility and increased risk of breast cancer. However, addition of aspirin can abrogate this effect.

Maternal exercise upregulates mitochondrial gene expression and increases enzyme activity of fetal mouse hearts

Maternal exercise during pregnancy has been shown to improve the long‐term health of offspring in later life. Mitochondria are important organelles for maintaining adequate heart function, and mitochondrial dysfunction is linked to cardiovascular disease. However, the effects of maternal exercise during pregnancy on mitochondrial biogenesis in hearts are not well understood. Thus, the purpose of this study was to test the hypothesis that mitochondrial gene expression in fetal myocardium would be upregulated by maternal exercise. Twelve‐week‐old female C57BL/6 mice were divided into sedentary and exercise groups. Mice in the exercise group were exposed to a voluntary cage‐wheel from gestational day 1 through 17. Litter size and individual fetal weights were taken when pregnant dams were sacrificed at 17 days of gestation. Three to four hearts from the same group were pooled to study gene expression, protein expression, and enzyme activity. There were no significant differences in litter size, sex distribution, and average fetal body weight per litter between sedentary and exercised dams. Genes encoding mitochondrial biogenesis and dynamics, including nuclear respiratory factor‐1 (Nrf1), Nrf2, and dynamin‐related GTPase termed mitofusin‐2 (Mfn2) were significantly upregulated in the fetal hearts from exercised dams. Cytochrome c oxidase activity and ATP production were significantly increased, while the hydrogen peroxide level was significantly decreased in the fetal hearts by maternal exercise. Our results demonstrate that maternal exercise initiated at day 1 of gestation could transfer the positive mitochondrial phenotype to fetal hearts.

Aspirin increases metabolism through germline signalling to extend the lifespan of Caenorhabditis elegans

Aspirin is a prototypic cyclooxygenase inhibitor with a variety of beneficial effects on human health. It prevents age-related diseases and delays the aging process. Previous research has shown that aspirin might act through a dietary restriction-like mechanism to extend lifespan. To explore the mechanism of action of aspirin on aging, we determined the whole-genome expression profile of Caenorhabditis elegans treated with aspirin. Transcriptome analysis revealed the RNA levels of genes involved in metabolism were primarily increased. Reproduction has been reported to be associated with metabolism. We found that aspirin did not extend the lifespan or improve the heat stress resistance of germline mutants of glp-1. Furthermore, Oil Red O staining showed that aspirin treatment decreased lipid deposition and increased expression of lipid hydrolysis and fatty acid β-oxidation-related genes. The effect of germline ablation on lifespan was mainly mediated by DAF-12 and DAF-16. Next, we performed genetic analysis with a series of worm mutants and found that aspirin did not further extend the lifespans of daf-12 and daf-16 single mutants, glp-1;daf-12 and glp-1;daf-16 double mutants, or glp-1;daf-12;daf-16 triple mutants. The results suggest that aspirin increase metabolism and regulate germline signalling to activate downstream DAF-12 and DAF-16 to extend lifespan.

Salicylates promote mitochondrial biogenesis by regulating the expression of PGC-1α in murine 3T3-L1 pre-adipocytes

Mitochondrial dysfunction has been associated with insulin resistance and diabetes. Decreased mitochondrial density and mitochondrial copy numbers have been found in insulin-resistant individuals. Restoration of the number of mitochondria and normal mitochondrial function has become an important therapeutic target of diabetes. Salicylate, the main active ingredient in aspirin, has been in medicinal use since ancient times. Little information regarding the effects of salicylate on mitochondrial function has been reported. In this study, we assessed the effects of salicylate on the peroxisome proliferator-activated receptor γ coactivator 1α (PGC-1α) signaling pathway and mitochondrial biogenesis in pre-adipocytes. Our findings demonstrate that treatment with salicylate promoted the expression of PGC-1α and its downstream targets nuclear respiratory factor 1 (NRF1) and mitochondrial transcription factor A (TFAM). Importantly, salicylate treatment significantly increased the number of mDNA, citrate synthase activity, expression of respiratory chain complex I, and mitochondrial mass, which were suppressed by the specific AMPK inhibitor Compound C. Indeed, salicylate treatment induced the phosphorylation of AMPK, which was involved in the induction of PGC-1α, NRF1, and TFAM. Importantly, inhibition of PGC-1α expression using PGC-1α small RNA interference abolished the effects of salicylate on mitochondrial biogenesis. These results suggest that salicylate has a potential therapeutic capacity against mitochondrial dysfunction in diabetes.

New natural amino acid-bearing prodrugs boost pterostilbene's oral pharmacokinetic and distribution profile

The biomedical effects of the natural phenol pterostilbene are of great interest but its bioavailability is negatively affected by the phenolic group in position 4' which is an ideal target for the conjugative enzymes of phase II metabolism. We report the synthesis and characterization of prodrugs in which the hydroxyl moiety is reversibly protected as a carbamate ester linked to the N-terminus of a natural amino acid. Prodrugs comprising amino acids with hydrophobic side chains were readily absorbed after intragastric administration to rats. The Area Under the Curve for pterostilbene in blood was optimal when prodrugs with isoleucine or β-alanine were used. The prodrug incorporating isoleucine was used for further studies to map distribution into major organs. When compared to pterostilbene itself, administration of the isoleucine prodrug afforded increased absorption, reduced metabolism and higher concentrations of pterostilbene, sustained for several hours, in most of the organs examined. Experiments using Caco-2 cells as an in vitro model for human intestinal absorption suggest that the prodrug could have promising absorption profiles also in humans; its uptake is partly due to passive diffusion, and partly mediated by H⁺-dependent transporters expressed on the apical membrane of enterocytes, such as PepT1 and OATP.

Resveratrol Co-Treatment Attenuates the Effects of HIV Protease Inhibitors on Rat Body Weight and Enhances Cardiac Mitochondrial Respiration

Since the early 1990s human immunodeficiency virus (HIV)/acquired immunodeficiency syndrome (AIDS) emerged as a global health pandemic, with sub-Saharan Africa the hardest hit. While the successful roll-out of antiretroviral (ARV) therapy provided significant relief to HIV-positive individuals, such treatment can also elicit damaging side-effects. Here especially HIV protease inhibitors (PIs) are implicated in the onset of cardio-metabolic complications such as type-2 diabetes and coronary heart disease. As there is a paucity of data regarding suitable co-treatments within this context, this preclinical study investigated whether resveratrol (RSV), aspirin (ASP) or vitamin C (VitC) co-treatment is able to blunt side-effects in a rat model of chronic PI exposure (Lopinavir/Ritonavir treatment for 4 months). Body weights and weight gain, blood metabolite levels (total cholesterol, HDL, LDL, triglycerides), echocardiography and cardiac mitochondrial respiration were assessed in PI-treated rats ± various co-treatments. Our data reveal that PI treatment significantly lowered body weight and cardiac respiratory function while no significant changes were found for heart function and blood metabolite levels. Moreover, all co-treatments ameliorated the PI-induced decrease in body weight after 4 months of PI treatment, while RSV co-treatment enhanced cardiac mitochondrial respiratory capacity in PI-treated rats. This pilot study therefore provides novel hypotheses regarding RSV co-treatment that should be further assessed in greater detail.

Aspirin increases mitochondrial fatty acid oxidation

The metabolic effects of salicylates are poorly understood. This study investigated the effects of aspirin on fatty acid oxidation. Aspirin increased mitochondrial long-chain fatty acid oxidation, but inhibited peroxisomal fatty acid oxidation, in two different cell lines. Aspirin increased mitochondrial protein acetylation and was found to be a stronger acetylating agent in vitro than acetyl-CoA. However, aspirin-induced acetylation did not alter the activity of fatty acid oxidation proteins, and knocking out the mitochondrial deacetylase SIRT3 did not affect the induction of long-chain fatty acid oxidation by aspirin. Aspirin did not change oxidation of medium-chain fatty acids, which can freely traverse the mitochondrial membrane. Together, these data indicate that aspirin does not directly alter mitochondrial matrix fatty acid oxidation enzymes, but most likely exerts its effects at the level of long-chain fatty acid transport into mitochondria. The drive on mitochondrial fatty acid oxidation may be a compensatory response to altered mitochondrial morphology and inhibited electron transport chain function, both of which were observed after 24 h incubation of cells with aspirin. These studies provide insight into the pathophysiology of Reye Syndrome, which is known to be triggered by aspirin ingestion in patients with fatty acid oxidation disorders.

The epigenetic effects of aspirin: the modification of histone H3 lysine 27 acetylation in the prevention of colon carcinogenesis in azoxymethane- and dextran sulfate sodium-treated CF-1 mice

Colorectal cancer (CRC) is the third most common cancer worldwide. Chronic inflammation appears to enhance the risk of CRC. Emerging evidence has suggested that epigenetic mechanisms play an important role in CRC. Aspirin [acetylsalicylic acid (ASA)] has been shown to prevent CRC; however, the epigenetic mechanisms of its action remain unknown. This study investigated the protective role of ASA in azoxymethane (AOM)-initiated and dextran sulfate sodium (DSS)-promoted colitis-associated colon cancer (CAC) and examined the epigenetic effects, particularly on histone 3 lysine 27 acetylation (H3K27ac), underlying the preventive effect of ASA. CF-1 mice were fed with AIN-93M diet with or without 0.02% ASA from 1 week prior to AOM initiation until the mice were killed 20 weeks after AOM injection. Our results showed that AOM/DSS + ASA significantly suppressed inflammatory colitis symptoms and tumor multiplicity. AOM/DSS + ASA reduced AOM/DSS-induced protein expression and the activity of histone deacetylases (HDACs) and globally restored H3K27ac. Furthermore, AOM/DSS + ASA inhibited AOM/DSS-induced enrichment of H3K27ac in the promoters of inducible nitric oxide synthase (iNOS), tumor necrosis factor alpha (TNF-α) and interleukin 6 (IL-6) that corresponded to the dramatic suppression of the messenger RNA (mRNA) and protein levels. Surprisingly, no significant changes in the H3K27ac abundance in the prostaglandin-endoperoxide synthase 2 (Cox-2) promoters or in the Cox-2 mRNA and protein expression were observed. Collectively, our results suggest that a potential novel epigenetic mechanism underlies the chemopreventive effects of ASA, and this mechanism attenuates CAC in AOM/DSS-induced CF-1 mice via the inhibition of HDACs and the modification of H3K27ac marks that suppress iNOS, TNF-α and IL-6.

Transcriptomic analysis of pancreatic cancer cells in response to metformin and aspirin: an implication of synergy

Metformin and aspirin have been studied extensively as cancer preventative and therapeutic agents. However, the underlying molecular mechanisms for the inhibitory effects of pancreatic cancer development remain undefined. To gain further insight into their biological function in pancreatic cancer, we conducted a transcriptomic analysis using RNA sequencing to assess the differential gene expression induced by metformin (5 mM) and aspirin (2 mM), alone or in combination, after treatment of PANC-1 cells for 48 hours. Compared to an untreated control, metformin down-regulated 58 genes and up-regulated 91 genes, aspirin down-regulated 12 genes only, while metformin plus aspirin down-regulated 656 genes and up-regulated 449 genes (fold-change > 2, P < 10⁻⁵). Of the top 10 genes (fold-change > 10, P < 10⁻¹⁰) regulated by metformin plus aspirin, PCDH18, CCL2, RASL11A, FAM111B and BMP5 were down-regulated ≥ 20-fold, while NGFR, NPTX1, C7orf57, MRPL23AS1 and UNC5B were up-regulated ≥ 10-fold. Ingenuity Pathway Analysis (IPA) revealed that the pathways, “cholesterol biosynthesis”, “cell cycle: G1/S checkpoint regulation”, and “axonal guidance signaling” were the most statistically significant pathways modulated by metformin plus aspirin. Although the results need further functional validation, these data provide the first evidence for the synergistic action between metformin and aspirin in modulating the transcriptional profile of pancreatic cancer cells.

Artemisinin mimics calorie restriction to trigger mitochondrial biogenesis and compromise telomere shortening in mice

Calorie restriction is known to extend lifespan among organisms by a debating mechanism underlying nitric oxide-driven mitochondrial biogenesis. We report here that nitric oxide generators including artemisinin, sodium nitroprusside, and L-arginine mimics calorie restriction and resembles hydrogen peroxide to initiate the nitric oxide signaling cascades and elicit the global antioxidative responses in mice. The large quantities of antioxidant enzymes are correlated with the low levels of reactive oxygen species, which allow the down-regulation of tumor suppressors and accessory DNA repair partners, eventually leading to the compromise of telomere shortening. Accompanying with the up-regulation of signal transducers and respiratory chain signatures, mitochondrial biogenesis occurs with the elevation of adenosine triphosphate levels upon exposure of mouse skeletal muscles to the mimetics of calorie restriction. In conclusion, calorie restriction-triggered nitric oxide provides antioxidative protection and alleviates telomere attrition via mitochondrial biogenesis, thereby maintaining chromosomal stability and integrity, which are the hallmarks of longevity.

Aspirin may influence cellular energy status

In our previous findings, we have demonstrated that aspirin/acetyl salicylic acid (ASA) might induce sirtuins via aryl hydrocarbon receptor (Ah receptor). Induction effects included an increase in cellular paraoxonase 1 (PON1) activity and apolipoprotein A1 (ApoA1) gene expression. As predicted, ASA and salicylic acid (SA) treatment resulted in generation of H2O2, which is known to be an inducer of mitochondrial gene Sirt4 and other downstream target genes of Sirt1. Our current mass spectroscopic studies further confirm the metabolism of the drugs ASA and SA. Our studies show that HepG2 cells readily converted ASA to SA, which was then metabolized to 2,3-DHBA. HepG2 cells transfected with aryl hydrocarbon receptor siRNA upon treatment with SA showed the absence of a DHBA peak as measured by LC-MS/MS. MS studies for Sirt1 action also showed a peak at 180.9 m/z for the deacetylated and chlorinated product formed from N-acetyl lε-lysine. Thus an increase in Sirt4, Nrf2, Tfam, UCP1, eNOS, HO1 and STAT3 genes could profoundly affect mitochondrial function, cholesterol homeostasis, and fatty acid oxidation, suggesting that ASA could be beneficial beyond simply its ability to inhibit cyclooxygenase.

Acute effects of green tea extract intake on exogenous and endogenous metabolites in human plasma

The acute effects of green tea extract (GTE) on plasma metabolites in vivo are largely unknown. In this parallel, double-blind study, the transient changes in total and free concentrations of catechins were measured in plasma from healthy males following the consumption of a single GTE dose (559.2 mg total catechins, 120.4 mg caffeine). Furthermore, the acute effects on endogenous metabolites were assessed 2 h after GTE intake using four-phase metabolite profiling. The ratios of the catechin concentrations in plasma to those in the GTE followed the order ECG/CG > EC > GCG > EGCG > EGC > C > GC. The gallated catechins EGCG, CG/ECG, GC, and GCG were also present in their free form. Sixteen out of 163 mostly endogenous metabolites were affected by acute GTE ingestion, when compared to placebo. These included caffeine, salicylate, hippurate, taurine, 3,4-dihydroxyphenylethylene-glycol, serotonin, some cholesterylesters, fatty acids, triglycerides, and sphingosines. Our results on the exogenous metabolites largely confirm previous studies, while our findings on the endogenous metabolites are novel and may suggest specific biological targets.