Nutrient availability links mitochondria, apoptosis, and obesity

Calorie restriction modulates mitochondrial dynamics and autophagy in leukocytes of patients with obesity

BACKGROUND

Although it is established that caloric restriction offers metabolic and clinical benefits, the molecular mechanisms underlying these effects remain unclear. Thus, this study aimed to investigate whether caloric restriction can modulate mitochondrial function and remodeling and stimulate autophagic flux in the PBMCs of patients with obesity.

METHODS

This was an interventional study of 38 obese subjects (BMI >35 kg/m2) who underwent 6 months of dietary therapy, including a 6-week very-low-calorie diet (VLCD) followed by an 18-week low-calorie diet (LCD). We determined clinical variables, mitochondrial function parameters (by fluorescence imaging of mitochondrial ROS and membrane potential), and protein expression of markers of mitochondrial dynamics (MNF1, MFN2, OPA, DRP1 and FIS1) and autophagy (LC3, Beclin, BCL2 and NBR1) by Western blot.

RESULTS

Caloric restriction induced an improvement in metabolic outcomes that was accompanied by an increase in AMPK expression, a decrease of mitochondrial ROS and mitochondrial membrane potential, which was associated with increased markers of mitochondrial dynamics (MFN2, DRP1 and FIS1) and activation of autophagy as evidenced by augmented LC3 II/I, Beclin1 and NBR1, and a decrease in BCL2.

CONCLUSION

These findings shed light on the specific molecular mechanisms by which caloric restriction facilitates metabolic improvements, highlighting the relevance of pathways involving energy homeostasis and cell recovery, including mitochondrial function and dynamics and autophagy.

Beneficial Effects of Capybara Oil Supplementation on Steatosis and Liver Apoptosis in Obese Mice

Obesity is a complex chronic disease characterized by excess body fat (adipose) that is harmful to health and has been a major global health problem. It may be associated with several diseases, such as nonalcoholic fatty liver disease (NAFLD). Polyunsaturated fatty acids (PUFA) are lipid mediators that have anti-inflammatory characteristics and can be found in animals and plants, with capybara oil (CO) being a promising source. So, we intend to evaluate the hepatic pathophysiological alterations in C57Bl/6 mice with NAFLD, caused by obesity, and the possible beneficial effects of OC in the treatment of this disease. Eighteen 3-month-old male C57Bl/6 mice received a control or high-fat diet for 18 weeks. From the 15th to the 18th week, the animals received treatment-through orogastric gavage-with placebo or free capybara oil (5 g/kg). Parameters inherent to body mass, glucose tolerance, evaluation of liver enzymes, percentage of hepatic steatosis, oxidative stress, the process of cell death with the apoptotic biomarkers (Bax, Bcl2, and Cytochrome C), and the ultrastructure of hepatocytes were analyzed. Even though the treatment with CO was not able to disassemble the effects on the physiological parameters, it proved to be beneficial in reversing the morphological and ultrastructural damage present in the hepatocytes. Thus, demonstrating that CO has beneficial effects in reducing steatosis and the apoptotic pathway, it is a promising treatment for NAFLD.

Thinned young apple powder prevents obesity-induced neuronal apoptosis via improving mitochondrial function of cerebral cortex in mice

Mitochondrial dysfunction is one of the triggers for obesity-induced neuron apoptosis. Thinned young apple is getting more attention on account of the extensive biological activities because of rich polyphenols and polysaccharides. However, the neuroprotective effect of thinned young apple powder (YAP) is still unclear. The aim of the present study was to investigate the preventive effect of YAP on obesity-induced neuronal apoptosis. C57BL/6J male mice were divided into 5 groups, control (CON), high fat diet (HFD), HFD + orlistat (ORL), HFD + low-dose young apple powder (LYAP) and HFD + high-dose young apple powder (HYAP) groups and intervened for 12 weeks. It was found that the YAP effectively reduced body weight gain. Importantly, the levels of pro-apoptosis protein were lower in LYAP and HYAP groups than the HFD group, such as Bak/Bcl2 and cleaved caspase3/caspase3. Pathway analysis based on untargeted metabolomics suggested that YAP alleviated obesity-induced neuronal apoptosis by three main metabolic pathway including arginine metabolism, citrate cycle (TCA cycle) and glutathione metabolism. Meanwhile, YAP improved the protein expression of mitochondrial respiratory chain complex, maintained the homeostasis of TCA cycle intermediates, protected the balance of mitochondrial dynamics and alleviated lipid accumulation. In addition, the levels of several antioxidants in cerebral cortex were higher in HYAP group than the HFD group like superoxide dismutase (SOD) and catalase (CAT). In summary, YAP supplementation suppressed neuronal apoptosis in the cerebral cortex of HFD-induced obesity mice by improving mitochondrial function and inhibiting oxidative stress.

Anterior Pituitary Transcriptomics Following a High-Fat Diet: Impact of Oxidative Stress on Cell Metabolism

Anterior pituitary cell function requires a high level of protein synthesis and secretion which depend heavily on mitochondrial adenosine triphosphate production and functional endoplasmic reticula. Obesity adds stress to tissues, requiring them to adapt to inflammation and oxidative stress, and adding to their allostatic load. We hypothesized that pituitary function is vulnerable to the stress of obesity. Here, we utilized a 10- to 15-week high-fat diet (HFD, 60%) in a thermoneutral environment to promote obesity, testing both male and female FVB.129P mice. We quantified serum hormones and cytokines, characterized the metabolic phenotype, and defined changes in the pituitary transcriptome using single-cell RNA-sequencing analysis. Weight gain was significant by 3 weeks in HFD mice, and by 10 weeks all HFD groups had gained 20 g. HFD females (15 weeks) had increased energy expenditure and decreased activity. All HFD groups showed increases in serum leptin and decreases in adiponectin. HFD caused increased inflammatory markers: interleukin-6, resistin, monocyte chemoattractant protein-1, and tumor necrosis factorα. HFD males and females also had increased insulin and increased TSH, and HFD females had decreased serum prolactin and growth hormone pulse amplitude. Pituitary single-cell transcriptomics revealed modest or no changes in pituitary cell gene expression from HFD males after 10 or 15 weeks or from HFD females after 10 weeks. However, HFD females (15 weeks) showed significant numbers of differentially expressed genes in lactotropes and pituitary stem cells. Collectively, these studies reveal that pituitary cells from males appear to be more resilient to the oxidative stress of obesity than females and identify the most vulnerable pituitary cell populations in females.

Mitochondrial protease ClpP supplementation ameliorates diet-induced NASH in mice

BACKGROUND & AIMS

Mitochondrial dysfunction is considered a pathogenic linker in the development of non-alcoholic steatohepatitis (NASH). Inappropriate mitochondrial protein-quality control, possibly induced by insufficiency of the mitochondrial matrix caseinolytic protease P (ClpP), can potentially cause mitochondrial dysfunction. Herein, we aimed to investigate hepatic ClpP levels in a diet-induced model of NASH and determine whether supplementation of ClpP can ameliorate diet-induced NASH.

METHODS

NASH was induced by a high-fat/high-fructose (HF/HFr) diet in C57BL/6J mice. Stress/inflammatory signals were induced in mouse primary hepatocytes (MPHs) by treatment with palmitate/oleate (PA/OA). ClpP levels in hepatocytes were reduced using the RNAi-mediated gene knockdown technique but increased through the viral transduction of ClpP. ClpP activation was induced by administering a chemical activator of ClpP.

RESULTS

Hepatic ClpP protein levels in C57BL/6J mice fed a HF/HFr diet were lower than the levels in those fed a normal chow diet. PA/OA treatment also decreased the ClpP protein levels in MPHs. Overexpression or activation of ClpP reversed PA/OA-induced mitochondrial dysfunction and stress/inflammatory signal activation in MPHs, whereas ClpP knockdown induced mitochondrial dysfunction and stress/inflammatory signals in these cells. On the other hand, ClpP overexpression or activation improved HF/HFr-induced NASH characteristics such as hepatic steatosis, inflammation, fibrosis, and injury in the C57BL/6J mice, whereas ClpP knockdown further augmented steatohepatitis in mice fed a HF/HFr diet.

CONCLUSIONS

Reduced ClpP expression and subsequent mitochondrial dysfunction are key to the development of diet-induced NASH. ClpP supplementation through viral transduction or chemical activation represents a potential therapeutic strategy to prevent diet-induced NASH.

LAY SUMMARY

Western diets, containing high fat and high fructose, often induce non-alcoholic steatohepatitis (NASH). Mitochondrial dysfunction is considered pathogenically linked to diet-induced NASH. We observed that the mitochondrial protease ClpP decreased in the livers of mice fed a western diet and supplementation of ClpP ameliorated western diet-induced NASH.

Mitochondrial changes in fish cells in vitro in response to serum deprivation

Mitochondria are critical to cellular activity that implicated in expansive networks to maintain organismal homeostasis under external stimuli of nutrient variability, a common and severe stress to fish performance during the intensive culture conditions. In the present study, zebrafish embryonic fibroblast cells were used to investigate the fish mitochondrial changes upon serum deprivation. Results showed that mitochondrial content and membrane potential were significantly reduced with increased intracellular ROS level in the serum deprivation treated fish cells. And the impaired mitochondria were characterized by rough and fracted outer membrane, and more fused mitochondria were frequently observed with the upregulated mRNA expressions of mitochondrial fusion genes (mfn1b, mfn2, and opa1). Besides, the mitochondrial DNA (mtDNA) copy numbers of mtatp6, mtcox1, mtcytb, mtnd4, and mtnd6 were overall showing the highly significant reduction, together with the mRNA expressions of these genes significantly increased, exhibiting the compensatory effects in mitochondria. Furthermore, the methyl-cytosine of whole mtDNA was compared and the methyl-reads numbers were distinctly increased in the treatment group, reflecting the instability of fish mtDNA with mitochondrial dysfunction under nutrient fluctuations. Collectively, current findings could facilitate the integrated research between fish mitochondrial response and external variables that indicates the potentially profound and durative deficits in fish health during the aquaculture processes.

The potential effect mechanism of high-fat and high-carbohydrate diet-induced obesity on anxiety and offspring of zebrafish

Anxiety and obesity are two current phenomena. They are among the important public health problems with increasing prevalence worldwide. Although it is claimed that there are strong relations between them, the mechanism of this relationship has not been fully clarified yet. On the other hand, the effect of this relationship on the offspring has been another research subject. In this study, obese zebrafish were obtained by feeding two different diets, one containing high amount of lipid (HF) and the other containing high amount of carbohydrate (HK), and their anxiety levels were evaluated. To establish a relationship between these two phenomena, in addition to histopathological and immunohistochemical analysis in the brain tissues of fish, the transcription levels of some genes related to lipid and carbohydrate metabolisms were determined. In addition, offspring were taken from obese zebrafish and studied to examine the effect of parental obesity on offspring. As a result, it was observed that the HC diet, causing more weight increase than the HF diet, showed an anxiolytic while the HF diet an anxiogenic effect. It was suggested that the probable cause of this situation may be the regulatory effect on the appetite-related genes depending on the upregulation severity of the PPAR gene family based on the diet content. In addition, it was also suggested that it may have contributed to this process in neuron degenerations caused by oxidative stress. Regarding effects on offspring, it can be concluded that HF diet-induced obesity has more negative effects on the next generation than the HC diet.Level of evidenceNo Level of evidence: animal study.

Fundamentals of Membrane Lipid Replacement: A Natural Medicine Approach to Repairing Cellular Membranes and Reducing Fatigue, Pain, and Other Symptoms While Restoring Function in Chronic Illnesses and Aging

Membrane Lipid Replacement (MLR) uses natural membrane lipid supplements to safely replace damaged, oxidized lipids in membranes in order to restore membrane function, decrease symptoms and improve health. Oral MLR supplements contain mixtures of cell membrane glycerolphospholipids, fatty acids, and other lipids, and can be used to replace and remove damaged cellular and intracellular membrane lipids. Membrane injury, caused mainly by oxidative damage, occurs in essentially all chronic and acute medical conditions, including cancer and degenerative diseases, and in normal processes, such as aging and development. After ingestion, the protected MLR glycerolphospholipids and other lipids are dispersed, absorbed, and internalized in the small intestines, where they can be partitioned into circulating lipoproteins, globules, liposomes, micelles, membranes, and other carriers and transported in the lymphatics and blood circulation to tissues and cellular sites where they are taken in by cells and partitioned into various cellular membranes. Once inside cells, the glycerolphospholipids and other lipids are transferred to various intracellular membranes by lipid carriers, globules, liposomes, chylomicrons, or by direct membrane-membrane interactions. The entire process appears to be driven by 'bulk flow' or mass action principles, where surplus concentrations of replacement lipids can stimulate the natural exchange and removal of damaged membrane lipids while the replacement lipids undergo further enzymatic alterations. Clinical studies have demonstrated the advantages of MLR in restoring membrane and organelle function and reducing fatigue, pain, and other symptoms in chronic illness and aging patients.

Exenatide Attenuates Obesity-Induced Mitochondrial Dysfunction by Activating SIRT1 in Renal Tubular Cells

Saturated free fatty acid (FFA)-induced lipotoxicity plays an important role in obesity-induced kidney injury. Exenatide, a Glucagon-like peptide-1 receptor agonist(GLP-1RA), protects against high-fat diet (HFD)-induced kidney injury. The precise mechanism needs to be further explored. This study investigated whether exenatide protects against FFA-induced tubular epithelial cells (TECs) lipotoxicity and elucidated its underlying mechanisms. Here, we show that exenatide treatment reversed HFD induced TECs injuries, including TECs apoptosis and SIRT1 downregulation. The efficacy of exenatide was better than simvastatin. In palmitate (PA)-stimulated HK2 cells, exenatide treatment reversed the downregulation of SIRT1 and prevented an increase in reactive oxygen species (ROS) production, a decrease in mitochondrial membrane potential, and mitochondrial apoptosis. The renal-protective effects of exenatide on the generation of mitochondrial ROS and mitochondrial apoptosis were blocked by inhibiting SIRT1 activation. Collectively, these findings show that exenatide was superior to simvastatin in the treatment of obesity-TECs injuries, the mechanism is partially through SIRT1 restoration, which directly reverses mitochondrial dysfunction and apoptosis.

Ferroptosis Regulation by Nutrient Signalling

Tremendous progress has been made in the field of ferroptosis since this regulated cell death process was first named in 2012. Ferroptosis is initiated upon redox imbalance and driven by excessive phospholipid peroxidation. Levels of multiple intracellular nutrients (iron, selenium, vitamin E and coenzyme Q10) are intimately related to the cellular antioxidant system and participate in the regulation of ferroptosis. Dietary intake of monounsaturated fatty acids (MUFA) and polyunsaturated fatty acids (PUFA) regulates ferroptosis by directly modifying the fatty acid composition in cell membranes. In addition, amino acids and glucose (energy stress) manipulate the ferroptosis pathway through the nutrient-sensitive kinases mechanistic target of rapamycin complex 1 (mTORC1) and AMP-activated protein kinase (AMPK). Understanding the molecular interaction between nutrient signals and ferroptosis sensors might help in the identification of the roles of ferroptosis in normal physiology and in the development of novel pharmacological targets for the treatment of ferroptosis-related diseases.

Oxidative Stress, Plant Natural Antioxidants, and Obesity

Oxidative stress is important in the pathophysiology of obesity, altering regulatory factors of mitochondrial activity, modifying the concentration of inflammation mediators associated with a large number and size of adipocytes, promoting lipogenesis, stimulating differentiation of preadipocytes to mature adipocytes, and regulating the energy balance in hypothalamic neurons that control appetite. This review discusses the participation of oxidative stress in obesity and the important groups of compounds found in plants with antioxidant properties, which include (a) polyphenols such as phenolic acids, stilbenes, flavonoids (flavonols, flavanols, anthocyanins, flavanones, flavones, flavanonols, and isoflavones), and curcuminoids (b) carotenoids, (c) capsaicinoids and casinoids, (d) isothiocyanates, (e) catechins, and (f) vitamins. Examples are analyzed, such as resveratrol, quercetin, curcumin, ferulic acid, phloretin, green tea, Hibiscus Sabdariffa, and garlic. The antioxidant activities of these compounds depend on their activities as reactive oxygen species (ROS) scavengers and on their capacity to prevent the activation of NF-κB (nuclear factor κ-light-chain-enhancer of activated B cells), and reduce the expression of target genes, including those participating in inflammation. We conclude that natural compounds have therapeutic potential for diseases mediated by oxidative stress, particularly obesity. Controlled and well-designed clinical trials are still necessary to better know the effects of these compounds.

Feeding level regulates the expression of some genes involved with programed cell death and remodeling in goat and sheep mammary tissue

Mammary tissue (MT) turnover is characterized by programed cell death and remodeling which might be affected by both feeding level and animal species. Thus, twenty-four dairy goats and the same number of sheep were assigned to three homogenous sub-groups per animal species and fed the same diet in quantities which met 70% (FL70), 100% (FL100) and 130% (FL130) of their daily energy and crude protein requirements. Individual MT samples were taken by biopsy from the animals on the 30th and 60th experimental day. The results showed, in the first sampling time, a significant reduction in the mRNA abundance for selected genes involved in programed cell death in both FL 70 fed goats (STAT3 and BECN1) and sheep (CASPASE8 and BECN1) compared with the respective FL100 groups. The FL130, in comparison with the FL100, caused a significant increase in transcripts accumulation of STAT3 gene in both sampling times and CASPASE8 gene in the second sampling time in goat MT, while the opposite happened for the mRNA expression of CASPASE8 and BECN1 genes in sheep MT, but only in the first sampling time. Moreover, a significant up regulation in the mRNA levels of MMP2 gene in MT of FL130 fed sheep was observed. The FL130, in comparison with the FL70, caused an enhancement in the mRNA expression levels of BECN1, CASPASE8, BAX and STAT3 genes in goat MT only. It was also shown that apoptosis and autophagy can be affected simultaneously by the feeding level. Overfeeding affects MT programed cell death and remodeling by a completely different way in goats than sheep. In conclusion, feeding level and animal species have strong effects on both MT programed cell death (apoptosis and autophagy) and remodeling but the molecular mechanisms need further investigation.

Insulin-like growth factor-1 short-period therapy improves cardiomyopathy stimulating cardiac progenitor cells survival in obese mice

BACKGROUND AND AIMS

Cardiovascular diseases are the main cause of mortality in obesity. Despite advanced understanding, the mechanisms that regulate cardiac progenitor cells (CPC) survival in pathological conditions are not clear. Low IGF-1 plasma levels are correlated to obesity, cardiomyopathy and CPC death, so this work aimed to investigate IGF-1 therapeutic potential on cardiomyopathy and its relationship with the survival, proliferation and differentiation of CPC in Western diet-induced obesity.

METHODS AND RESULTS

Male Swiss mice were divided into control group (CG, n = 8), fed with standard diet; and obese group (OG, n = 16), fed with Western diet, for 12 weeks. At 11th week, OG was subdivided to receive a daily subcutaneous injection of human recombinant IGF-1 (100 μg.Kg^-1) for seven consecutive days (OG + IGF1, n = 8). Results showed that IGF-1 therapy improved the metabolic parameters negatively impacted by western diet in OG, reaching levels similar to CG. OG + IGF-1 also demonstrated restored heart energetic metabolism, fibrosis resolution, decreased apoptosis level, restored cardiac gap junctions and intracellular calcium balance. Cardiomyopathy improvement was accompanied by increased CPC survival, proliferation and newly cardiomyocytes formation related to increased pAkt/Akt ratio.

CONCLUSION

These results suggest that only one week of IGF-1 therapy has cardioprotective effects through Akt pathway upregulation, ensuring CPC survival and differentiation, contributing to heart failure rescue.

Delayed Pulmonary Apoptosis of Diet-Induced Obesity Mice following Escherichia coli Infection through the Mitochondrial Apoptotic Pathway

Escherichia coli (E. coli) is one of pathogens causing nosocomial pneumonia and could induce pulmonary excessive apoptosis. Although much has been learned about metabolic diseases induced by obesity, the information linking bacterial pneumonia to obesity is limited. Accordingly, we investigated the apoptosis of normal (lean) and diet-induced obesity (DIO, fed a high-fat diet) mice after nasal instillation with E. coli. Lung tissues were obtained at 0 (preinfection), 12, 24, and 72 h after infection, and acute pulmonary inflammation was observed at 12 h. Elevated cell apoptosis and percentage of pulmonary cells depolarized with collapse of the mitochondrial transmembrane potential (Δψm) occurred in response to bacterial infection. The relative mRNA and protein expressions of Bax, caspase-3, and caspase-9 increased, but Bcl-2 decreased in the lung. Interestingly, the apoptotic percentage and most of apoptosis-associated factors mentioned above peaked at 12 or 24 h in the lean-E. coli group, while at 24 or 72 h in the DIO-E. coli group. Taken together, these findings indicated that the E. coli pneumonia caused excessive pulmonary apoptosis through the mitochondria-mediated pathway, and the apoptosis was delayed in the DIO mice with E. coli pneumonia.

Plant Extracts and Reactive Oxygen Species as Two Counteracting Agents with Anti- and Pro-Obesity Properties

Obesity is a complex disease of great public health significance worldwide: It entails several complications including diabetes mellitus type 2, cardiovascular dysfunction and hypertension, and its prevalence is increasing around the world. The pathogenesis of obesity is closely related to reactive oxygen species. The role of reactive oxygen species as regulatory factors in mitochondrial activity in obese subjects, molecules taking part in inflammation processes linked to excessive size and number of adipocytes, and as agents governing the energy balance in hypothalamus neurons has been examined. Phytotherapy is the traditional form of treating health problems using plant-derived medications. Some plant extracts are known to act as anti-obesity agents and have been screened in in vitro models based on the inhibition of lipid accumulation in 3T3-L1 cells and activity of pancreatic lipase methods and in in vivo high-fat diet-induced obesity rat/mouse models and human models. Plant products may be a good natural alternative for weight management and a source of numerous biologically-active chemicals, including antioxidant polyphenols that can counteract the oxidative stress associated with obesity. This review presents polyphenols as natural complementary therapy, and a good nutritional strategy, for treating obesity without serious side effects.

Obesity May Accelerate the Aging Process

Lines of evidence from several studies have shown that increases in life expectancy are now accompanied by increased disability rate. The expanded lifespan of the aging population imposes a challenge on the continuous increase of chronic disease. The prevalence of overweight and obesity is increasing at an alarming rate in many parts of the world. Further to increasing the onset of metabolic imbalances, obesity leads to reduced life span and affects cellular and molecular processes in a fashion resembling aging. Nine key hallmarks of the aging process have been proposed. In this review, we will review these hallmarks and discuss pathophysiological changes that occur with obesity, that are similar to or contribute to those that occur during aging. We present and discuss the idea that obesity, in addition to having disease-specific effects, may accelerate the rate of aging affecting all aspects of physiology and thus shortening life span and health span.

Metabolites in visceral fat: useful signals of metabolic syndrome?

Metabolic syndrome comprises a series of health conditions, such as increased blood pressure, high blood sugar, excess abdominal fat, and altered circulating cholesterol or triglyceride levels. A fast growing number of affected individuals are at an increased risk of heart disease, stroke and type-2 diabetes. Obesity, especially build-up of visceral fat, is a recognized major risk factor for the development of metabolic syndrome. However, our understanding of the mechanistic links and biomarkers that associate visceral fat with the development of conditions underlying metabolic syndrome is still inadequate. In a recent paper published in the Biochemical Journal [Biochem. J. (2018) 475, 1019–1035], Candi et al. address this lack of knowledge, performing high-throughput metabolomics analysis of visceral fat isolated from obese individuals, with and without metabolic syndrome, and non-obese healthy controls. The authors identify alterations in metabolic pathways that distinguish pathologically from healthy obese subjects. They identify metabolic cues that point to oxidative and inflammatory burden as the leitmotifs of metabolic syndrome. Of particular interest is the identification of increased metabolism of γ-glutamyl amino acids and plasmalogens in pathological obesity. γ-glutamyl amino acids, generated through the transfer of a γ-glutamyl moiety from glutathione to an amino acid acceptor, are involved in glutathione metabolism and the response to oxidative stress, whereas plasmalogens, a poorly studied class of phospholipids, are known contributors to insulin resistance and hypertension. Both classes of metabolites are intriguing candidate biomarkers that warrant further investigation.

Mitochondrial dysfunction in obesity

Obesity leads to various changes in the body. Among them, the existing inflammatory process may lead to an increase in the production of reactive oxygen species (ROS) and cause oxidative stress. Oxidative stress, in turn, can trigger mitochondrial changes, which is called mitochondrial dysfunction. Moreover, excess nutrients supply (as it commonly is the case with obesity) can overwhelm the Krebs cycle and the mitochondrial respiratory chain, causing a mitochondrial dysfunction, and lead to a higher ROS formation. This increase in ROS production by the respiratory chain may also cause oxidative stress, which may exacerbate the inflammatory process in obesity. All these intracellular changes can lead to cellular apoptosis. These processes have been described in obesity as occurring mainly in peripheral tissues. However, some studies have already shown that obesity is also associated with changes in the central nervous system (CNS), with alterations in the blood-brain barrier (BBB) and in cerebral structures such as hypothalamus and hippocampus. In this sense, this review presents a general view about mitochondrial dysfunction in obesity, including related alterations, such as inflammation, oxidative stress, and apoptosis, and focusing on the whole organism, covering alterations in peripheral tissues, BBB, and CNS.

The impact of obesity on neurodegenerative diseases

Neurodegenerative diseases are a growing health concern. The increasing incidences of these disorders have a great impact on the patients' quality of life. Although the mechanisms of neurodegenerative diseases are still far from being clarified, several studies look for new discoveries about their pathophysiology and prevention. Furthermore, evidence has shown a strong correlation between obesity and the development of Alzheimer's disease (AD) and Parkinson's disease (PD). Metabolic changes caused by overweight are related to damage to the central nervous system (CNS), which can lead to neural death, either by apoptosis or cell necrosis, as well as alter the synaptic plasticity of the neuron. This review aims to show the association between neurodegenerative diseases, focusing on AD and PD, and metabolic alterations.

Membrane Lipid Replacement for chronic illnesses, aging and cancer using oral glycerolphospholipid formulations with fructooligosaccharides to restore phospholipid function in cellular membranes, organelles, cells and tissues

Membrane Lipid Replacement is the use of functional, oral supplements containing mixtures of cell membrane glycerolphospholipids, plus fructooligosaccharides (for protection against oxidative, bile acid and enzymatic damage) and antioxidants, in order to safely replace damaged, oxidized, membrane phospholipids and restore membrane, organelle, cellular and organ function. Defects in cellular and intracellular membranes are characteristic of all chronic medical conditions, including cancer, and normal processes, such as aging. Once the replacement glycerolphospholipids have been ingested, dispersed, complexed and transported, while being protected by fructooligosaccharides and several natural mechanisms, they can be inserted into cell membranes, lipoproteins, lipid globules, lipid droplets, liposomes and other carriers. They are conveyed by the lymphatics and blood circulation to cellular sites where they are endocytosed or incorporated into or transported by cell membranes. Inside cells the glycerolphospholipids can be transferred to various intracellular membranes by lipid globules, liposomes, membrane-membrane contact or by lipid carrier transfer. Eventually they arrive at their membrane destinations due to 'bulk flow' principles, and there they can stimulate the natural removal and replacement of damaged membrane lipids while undergoing further enzymatic alterations. Clinical trials have shown the benefits of Membrane Lipid Replacement in restoring mitochondrial function and reducing fatigue in aged subjects and chronically ill patients. Recently Membrane Lipid Replacement has been used to reduce pain and other symptoms as well as removing hydrophobic chemical contaminants, suggesting that there are additional new uses for this safe, natural medicine supplement. This article is part of a Special Issue entitled: Membrane Lipid Therapy: Drugs Targeting Biomembranes edited by Pablo V. Escribá.

Proteomic Analysis, Immune Dysregulation, and Pathway Interconnections with Obesity

Proteomic studies can offer information on hundreds to thousands of proteins and potentially provide researchers with a comprehensive understanding of signaling response during stress and disease. Large data sets, such as those obtained in high-dimensional proteomic studies, can be leveraged for pathway analysis to discover or describe the biological implications of clinical disease states. Obesity is a worldwide epidemic that is considered a risk factor for numerous other diseases. We performed analysis on plasma proteomic data from 3 separate sample sets of postmenopausal women to identify the pathways that are altered in subjects with a high body mass index (BMI) compared to normal BMI. We found many pathways consistently and significantly associated with inflammation dysregulated in plasma from obese/overweight subjects compared to plasma from normal BMI subjects. These pathways indicate alterations of soluble inflammatory regulators, cellular stress, and metabolic dysregulation. Our results highlight the importance of high-dimensional pathway analysis in complex diseases as well as provide information on the interconnections between pathways that are dysregulated with obesity. Specifically, overlap of obesity related pathways with those activated during cancer and infection could help describe why obesity is a risk factor for disease and help devise treatment options that mitigate its effect.

Cordyceps militaris induces tumor cell death via the caspase‑dependent mitochondrial pathway in HepG2 and MCF‑7 cells

Cordyceps militaris (CM), an entomopathogenic fungus belonging to the class ascomycetes, possesses various pharmacological activities, including cytotoxic effects, on various types of human tumor cells. The present study investigated the anti-hepatocellular carcinoma (HCC) and anti-breast cancer effects of CM in in vitro and in vivo models. CM aqueous extract reduced cell viability, suppressed cell proliferation, inhibited cell migration ability, caused the over-release of lactate dehydrogenase, induced mitochondrial dysfunction and enhanced apoptotic rates in MCF-7 and HepG2 cells. The expression levels of cleaved poly (ADP ribose) polymerase and caspase-3, biomarkers of apoptosis, were increased following treatment with CM aqueous extract for 24 h. Furthermore, in the MCF-7 and HepG2 cells, enhanced levels of B cell-associated X protein and cleaved caspase-8 were observed in the CM-treated cells. Finally, the antitumor activities of CM in HCC and breast cancer were also confirmed in MCF-7- and HepG2-xengraft nude mice models. Collectively, the data obtained in the present study suggested that the cytotoxic effects of CM aqueous extract on HCC and breast cancer are associated with the caspase-dependent mitochondrial pathway.

Obesity-driven alterations in adipose-derived stem cells are partially restored by weight loss

OBJECTIVE

The therapeutic potential of adipose-derived stem cells (ASCs) is reduced by various stress-inducing conditions that affect tissue homeostasis such as diabetes, aging, and obesity. Previous works have provided evidence of negative effects of obesity on ASC populations, but it is unclear whether this persists after a weight loss. This study evaluated whether weight loss can restore the attenuated properties found in ASCs derived from populations with obesity (oASCs).

METHODS

In vitro functional analyses were performed to investigate the possible recovery properties in mouse oASCs. Using ASCs isolated from subcutaneous tissue from formerly obese mice (dASCs) and control mice (cASCs), cell proliferation, viability, and some regenerative properties in these cells were analyzed compared with oASCs to evaluate the functional cell state.

RESULTS

Cell proliferation, viability, and some regenerative properties are strengthened in dASCs and cASCs compared with oASCs. Nevertheless, metabolic analysis reveals a mitochondrial load misbalance and function leading to impaired respiration in dASCs.

CONCLUSIONS

This study demonstrates that an initial obese environment triggers a detrimental state in ASCs that is not completely recovered after weight loss.

Long-Lasting Metabolic Imbalance Related to Obesity Alters Olfactory Tissue Homeostasis and Impairs Olfactory-Driven Behaviors

Obesity is associated with chronic food intake disorders and binge eating. Food intake relies on the interaction between homeostatic regulation and hedonic signals among which, olfaction is a major sensory determinant. However, its potential modulation at the peripheral level by a chronic energy imbalance associated to obese status remains a matter of debate. We further investigated the olfactory function in a rodent model relevant to the situation encountered in obese humans, where genetic susceptibility is juxtaposed on chronic eating disorders. Using several olfactory-driven tests, we compared the behaviors of obesity-prone Sprague-Dawley rats (OP) fed with a high-fat/high-sugar diet with those of obese-resistant ones fed with normal chow. In OP rats, we reported 1) decreased odor threshold, but 2) poor olfactory performances, associated with learning/memory deficits, 3) decreased influence of fasting, and 4) impaired insulin control on food seeking behavior. Associated with these behavioral modifications, we found a modulation of metabolism-related factors implicated in 1) electrical olfactory signal regulation (insulin receptor), 2) cellular dynamics (glucorticoids receptors, pro- and antiapoptotic factors), and 3) homeostasis of the olfactory mucosa and bulb (monocarboxylate and glucose transporters). Such impairments might participate to the perturbed daily food intake pattern that we observed in obese animals.

Altered metabolic and stemness capacity of adipose tissue-derived stem cells from obese mouse and human

Adipose stem cells (ASCs) are an appealing source of cells for therapeutic intervention; however, the environment from which ASCs are isolated may impact their usefulness. Using a range of functional assays, we have evaluated whether ASCs isolated from an obese environment are comparable to cells from non-obese adipose tissue. Results showed that ASCs isolated from obese tissue have a reduced proliferative ability and a loss of viability together with changes in telomerase activity and DNA telomere length, suggesting a decreased self-renewal capacity. Metabolic analysis demonstrated that mitochondrial content and function was impaired in obese-derived ASCs resulting in changes in favored oxidative substrates. These findings highlight the impact of obesity on adult stem properties. Hence, caution should be exercised when considering the source of ASCs for cellular therapies since their therapeutic potential may be impaired.

Comparative proteome analysis of brown adipose tissue in obese C57BL/6J mice using iTRAQ-coupled 2D LC-MS/MS

High-fat diet (HFD) leads to the development of obesity accompanied by insulin resistance, which increases the risk of type 2 diabetes mellitus and cardiovascular disease. Brown adipose tissue (BAT) plays an essential role in energy metabolism, thus it will give us promising treatment targets through elucidating underlying mechanisms of BAT in obesity. In this study, female C57BL/6J mice were fed HFD or normal diet (ND) for 22 weeks. Hyperinsulinemic-euglycemic clamp was performed to evaluate insulin sensitivity, which was independently correlated with obesity. Using isobaric tag for relative and absolute quantification (iTRAQ) coupled with 2D LC-MS/MS, we quantitated 3048 proteins in BAT. As compared HFD with ND, we obtained 727 differentially expressed proteins. Functional analysis found that those proteins were mainly assigned to the pathway of mitochondrial function. In this pathway, carnitine O-palmitoyltransferase 2 (CPT2), uncoupling protein 1 (UCP1) and apoptosis-inducing factor 1 (AIF1) were up-regulated significantly by HFD, and they were confirmed by western blotting. The results indicated that HFD might induce the apoptosis of brown adipocytes via the up-regulated AIF1. Meanwhile, HFD also stimulated fatty acid β-oxidation and raised compensatory energy consuming through the increases of CPT2 and UCP1, respectively. However, the apoptosis of brown adipocytes might weaken the compensatory energy expenditure, and finally contribute to overweight/obesity. So, preventing the apoptosis of brown adipocytes may be the key target to treat obesity.

Evaluation of chromosomal damage, cytostasis, cytotoxicity, oxidative DNA damage and their association with body-mass index in obese subjects

Over-weight and obesity are serious problems that increase the risk not only for chronic diseases like diabetes and heart disease but also of various types of cancer. This study was conducted to evaluate cytokinesis-block micronucleus cytome (CBMN-cyt) assay parameters and plasma concentrations of 8-hydroxy-2'-deoxyguanosine (8-OHdG), and their relationship with age, body-mass index (BMI) and waist-to-hip ratio (WHR) in 83 obese, 21 over-weight and 21 normal-weight subjects. Frequencies of micronuclei (MN), nucleoplasmic bridges (NPB), nuclear buds (NBUD), and apoptotic and necrotic cells in lymphocytes of obese subjects were found to be significantly higher than those found in normal-weight and over-weight subjects (p<0.01 and p<0.05), whereas plasma concentrations of 8-OHdG in obese subjects were lower than those observed in normal-weight and over-weight subjects (p<0.05 and p<0.01, respectively). There was a negative correlation between age and frequency of necrotic cells and NDI (p<0.05), whereas there was no correlation between BMI, WHR, CBMN cyt assay parameters and plasma 8-OHdG in normal-weight subjects. In over-weight subjects, a negative correlation was observed between age and NDI (p<0.01) and a positive correlation between age and frequency of NPB (p<0.01) and between BMI and frequency of NBUD (p<0.05). In obese subjects, a negative correlation was observed between age and NDI (p<0.01) and between BMI and NDI (p<0.05), whereas no correlation was observed between WHR and CBMN-cyt assay parameters and plasma 8-OHdG. However, frequencies of MN, NPB, NBUD, apoptotic and necrotic cells in total over-weight/obese (p<0.01/p<0.05) and all subjects (p<0.01) increased with increasing BMI. The increase in genomic damage (MN, NPB and NBUD) in obese subjects and the positive correlation between genomic damage and BMI in total over-weight/obese subjects indicate that obesity increases genomic damage and may be associated with an increased risk of cancer, because an increase in MN frequency is a predictor of cancer risk.

Novel association of the obesity risk-allele near Fas Apoptotic Inhibitory Molecule 2 (FAIM2) gene with heart rate and study of its effects on myocardial infarction in diabetic participants of the PREDIMED trial

BACKGROUND

The Fas apoptotic pathway has been implicated in type 2 diabetes and cardiovascular disease. Although a polymorphism (rs7138803; G > A) near the Fas apoptotic inhibitory molecule 2 (FAIM2) locus has been related to obesity, its association with other cardiovascular risk factors and disease remains uncertain.

METHODS

We analyzed the association between the FAIM2-rs7138803 polymorphism and obesity, blood pressure and heart rate in 7,161 participants (48.3% with type 2 diabetes) in the PREDIMED study at baseline. We also explored gene-diet interactions with adherence to the Mediterranean diet (MedDiet) and examined the effects of the polymorphism on cardiovascular disease incidence per diabetes status after a median 4.8-year dietary intervention (MedDiet versus control group) follow-up.

RESULTS

We replicated the association between the FAIM2-rs7138803 polymorphism and greater obesity risk (OR: 1.08; 95% CI: 1.01-1.16; P = 0.011; per-A allele). Moreover, we detected novel associations of this polymorphism with higher diastolic blood pressure (DBP) and heart rate at baseline (B = 1.07; 95% CI: 0.97-1.28 bmp in AA vs G-carriers for the whole population), that remained statistically significant even after adjustment for body mass index (P = 0.012) and correction for multiple comparisons. This association was greater and statistically significant in type-2 diabetic subjects (B = 1.44: 95% CI: 0.23-2.56 bmp; P = 0.010 for AA versus G-carriers). Likewise, these findings were also observed longitudinally over 5-year follow-up. Nevertheless, we found no statistically significant gene-diet interactions with MedDiet for this trait. On analyzing myocardial infarction risk, we detected a nominally significant (P = 0.041) association in type-2 diabetic subjects (HR: 1.86; 95% CI:1.03-3.37 for AA versus G-carriers), although this association did not remain statistically significant following correction for multiple comparisons.

CONCLUSIONS

We confirmed the FAIM2-rs7138803 relationship with obesity and identified novel and consistent associations with heart rate in particular in type 2 diabetic subjects. Furthermore, our results suggest a possible association of this polymorphism with higher myocardial infarction risk in type-2 diabetic subjects, although this result needs to be replicated as it could represent a false positive.

Lipid Replacement Therapy: a natural medicine approach to replacing damaged lipids in cellular membranes and organelles and restoring function

Lipid Replacement Therapy, the use of functional oral supplements containing cell membrane phospholipids and antioxidants, has been used to replace damaged, usually oxidized, membrane glycerophospholipids that accumulate during aging and in various clinical conditions in order to restore cellular function. This approach differs from other dietary and intravenous phospholipid interventions in the composition of phospholipids and their defense against oxidation during storage, ingestion, digestion and uptake as well as the use of protective molecules that noncovalently complex with phospholipid micelles and prevent their enzymatic and bile disruption. Once the phospholipids have been taken in by transport processes, they are protected by several natural mechanisms involving lipid receptors, transport and carrier molecules and circulating cells and lipoproteins until their delivery to tissues and cells where they can again be transferred to intracellular membranes by specific and nonspecific transport systems. Once delivered to membrane sites, they naturally replace and stimulate removal of damaged membrane lipids. Various chronic clinical conditions are characterized by membrane damage, mainly oxidative but also enzymatic, resulting in loss of cellular function. This is readily apparent in mitochondrial inner membranes where oxidative damage to phospholipids like cardiolipin and other molecules results in loss of trans-membrane potential, electron transport function and generation of high-energy molecules. Recent clinical trials have shown the benefits of Lipid Replacement Therapy in restoring mitochondrial function and reducing fatigue in aged subjects and patients with a variety of clinical diagnoses that are characterized by loss of mitochondrial function and include fatigue as a major symptom. This Article is Part of a Special Issue Entitled: Membrane Structure and Function: Relevance in the Cell's Physiology, Pathology and Therapy.

Mitochondrial dysfunction: a basic mechanism in inflammation-related non-communicable diseases and therapeutic opportunities

Obesity is not necessarily a predisposing factor for disease. It is the handling of fat and/or excessive energy intake that encompasses the linkage of inflammation, oxidation, and metabolism to the deleterious effects associated with the continuous excess of food ingestion. The roles of cytokines and insulin resistance in excessive energy intake have been studied extensively. Tobacco use and obesity accompanied by an unhealthy diet and physical inactivity are the main factors that underlie noncommunicable diseases. The implication is that the management of energy or food intake, which is the main role of mitochondria, is involved in the most common diseases. In this study, we highlight the importance of mitochondrial dysfunction in the mutual relationships between causative conditions. Mitochondria are highly dynamic organelles that fuse and divide in response to environmental stimuli, developmental status, and energy requirements. These organelles act to supply the cell with ATP and to synthesise key molecules in the processes of inflammation, oxidation, and metabolism. Therefore, energy sensors and management effectors are determinants in the course and development of diseases. Regulating mitochondrial function may require a multifaceted approach that includes drugs and plant-derived phenolic compounds with antioxidant and anti-inflammatory activities that improve mitochondrial biogenesis and act to modulate the AMPK/mTOR pathway.