Changes in lipid distribution during aging and its modulation by calorie restriction

Intermittent fasting positively modulates human gut microbial diversity and ameliorates blood lipid profile

Aim

The aim was to evaluate the impact of intermittent fasting (IF) on human body mass index (BMI) and serum lipid profile thorough constructive rectification of gut microbiota.

Methods and results

Fourteen healthy women and thirty-one men were included in the study. Their blood and fecal samples were collected before and at the end of the study. Blood parameters, anthropometric values, and gut microbiology were noted to investigate the impact of intermittent fasting (IF) on human gut microbiota and physiology. Our data revealed that IF reduces the body weight and improves blood lipid profile, such as increasing high-density lipoprotein (HDL) and decreasing total cholesterol, triglycerides, and low- and very low-density lipoprotein levels. IF also decreases culturable aerobic bacterial count and increased fungal count. It was also found that the gut metagenome is altered considerably after IF. The human fecal bacterial diversity exhibited significant changes in decreased overall bacterial population, increased bacterial diversity (alpha diversity), and promoted evenness within the bacterial population at the species level. Anti-inflammatory bacteria Lactobacillus and Bifidobacterium were favorably increased, while pathogenic bacteria were decreased.

Conclusion

Collectively, these results indicated that IF could improve lipid profile and body weight in humans, and the potential mechanisms might be via regulating gut microbiota.

Significance and impact of the study

We demonstrated for the first time that IF improved body weight and blood lipid profile, indicating that IF could mitigate gut microbiota in humans.

Aging and short-term calorie restriction differently affect the cardiac and skeletal muscle expression of genes regulating energy substrate utilization in male rats

Aging affects the energy metabolism differently in the cardiac and skeletal muscles. The study aim was to assess the effects of short-term calorie restriction (SCR) and refeeding on the expression of genes involved in the control of cardiac and skeletal muscle energy metabolism in old vs. young male rats. Young (4 mo) and old (24 mo) rats were subjected to 60% SCR for 30 days, and refed ad libitum for 2 or 4 days. In the cardiac (CM) and skeletal muscles (SM) we compared the gene expression (qPCR) of carnitine palmitoyltransferase-I (Cpt-I), peroxisome proliferator-activated receptor beta/delta (Ppar-β/δ), glucose transporter 4 (Glut4), peroxisome proliferator-activated receptor-γ coactivator-1α (Pgc-1α), and sirtuin 3 (Sirt3). In CM, aging increased Cpt-I expression but did not affect the other genes. In SM, Cpt-I, Glut4, Pgc-1α, and Sirt3 mRNA levels were lower in old than young rats. In CM of only young rats SCR increased Cpt-I expression which remained elevated after refeeding. Upon SCR, the expression of Ppar-β/δ, Glut4, Pgc-1α, and Sirt3 in CM increased in young but not old rats, and refeeding re-established control levels. In SM of young rats SCR increased Ppar-β/δ and Pgc-1α, and decreased Sirt3 expression, whereas refeeding generally decreased these mRNA levels. In SM of old rats SCR decreased only Pgc-1α expression. The adaptive response to SCR and subsequent refeeding is muscle tissue-specific and differs in young and old male rats. SCR appears to increase the efficiency of glucose and fatty acid utilization in the cardiac muscle of young, but not old male rats.

Effect of Long-Term Supplementation with Acetic Acid on the Skeletal Muscle of Aging Sprague Dawley Rats

Mitochondrial function in skeletal muscle, which plays an essential role in oxidative capacity and physical activity, declines with aging. Acetic acid activates AMP-activated protein kinase (AMPK), which plays a key role in the regulation of whole-body energy by phosphorylating key metabolic enzymes in both biosynthetic and oxidative pathways and stimulates gene expression associated with slow-twitch fibers and mitochondria in skeletal muscle cells. In this study, we investigate whether long-term supplementation with acetic acid improves age-related changes in the skeletal muscle of aging rats in association with the activation of AMPK. Male Sprague Dawley (SD) rats were administered acetic acid orally from 37 to 56 weeks of age. Long-term supplementation with acetic acid decreased the expression of atrophy-related genes, such as atrogin-1, muscle RING-finger protein-1 (MuRF1), and transforming growth factor beta (TGF-β), activated AMPK, and affected the proliferation of mitochondria and type I fiber-related molecules in muscles. The findings suggest that acetic acid exhibits an anti-aging function in the skeletal muscles of aging rats.

Potential Antiaging Effects of DLBS1649, a Centella asiatica Bioactive Extract

Purpose

Centella asiatica is a traditional medicinal plant, especially for wound healing and as a neuroprotective agent. DLBS1649 is a bioactive extract from C. asiatica, and was studied to investigate its benefits as an antiaging agent.

Methods

DLBS1649 was administered to HEK293 and 3T3L1 mammalian cells cultured in a time- or dose-dependent manner. Telomere length analysis was performed. TERT, CMYC, SIRT1, SIRT2, and KL expression were observed using reverse-transcription qPCR. Telomerase protein was studied with ELISA, while calorie restriction was observed using Oil Red O. In vivo study was conducted using Drosophila melanogaster with restricted mean survival time as the statistical method of analysis.

Results

DLBS1649 50 µg/mL showed an effect in the prevention of telomere shortening by 50% and decrease in telomerase activity by 28% compared to the controls (70% and 40%, respectively) in the HEK293 cell cultures. TERT-, CMYC-, SIRT1-, SIRT2-, and KL-expression degression was also reduced (29%, 9%, 18%, 25%, 9%, and 30%, respectively) compared to the controls (46%, 40%, 56%, 44%, and 46%, respectively) after ten serial passages. Calorie-restriction activity from DLBS1649 50 µg/mL was seen, with lower fat droplet counts being detected in the treated samples (37%) than the controls (28%) in 3T3L1 cells. DLBS1649 2 mg/mL increased restricted mean survival time in male and female D. melanogaster (23.87% [p<0.05] and 12.58%, respectively).

Conclusion

The results revealed DLBS1649’s potential as an antiaging agent based on telomere-length preservation, decreased expression of aging-related genes, increased calorie restriction in vitro, and mortality reduction in D. melanogaster in vivo.

Aging Liver: Can Exercise be a Better Way to Delay the Process than Nutritional and Pharmacological Intervention? Focus on Lipid Metabolism

BACKGROUND & AIMS

Nowadays, the world is facing a common problem that the population aging process is accelerating. How to delay metabolic disorders in middle-aged and elderly people, has become a hot scientific and social issue worthy of attention. The liver plays an important role in lipid metabolism, and abnormal lipid metabolism may lead to liver diseases. Exercise is an easily controlled and implemented intervention, which has attracted extensive attention in improving the health of liver lipid metabolism in the elderly. This article reviewed the body aging process, changes of lipid metabolism in the aging liver, and the mechanism and effects of different interventions on lipid metabolism in the aging liver, especially focusing on exercise intervention.

METHODS

A literature search was performed using PubMed-NCBI, EBSCO Host and Web of Science, and also a report from WHO. In total, 143 studies were included from 1986 to 15 February 2020.

CONCLUSION

Nutritional and pharmacological interventions can improve liver disorders, and nutritional interventions are less risky relatively. Exercise intervention can prevent and improve age-related liver disease, especially the best high-intensity interval training intensity and duration is expected to be one of the research directions in the future.

Anti-aging Effects of Calorie Restriction (CR) and CR Mimetics based on the Senoinflammation Concept

Chronic inflammation, a pervasive feature of the aging process, is defined by a continuous, multifarious, low-grade inflammatory response. It is a sustained and systemic phenomenon that aggravates aging and can lead to age-related chronic diseases. In recent years, our understanding of age-related chronic inflammation has advanced through a large number of investigations on aging and calorie restriction (CR). A broader view of age-related inflammation is the concept of senoinflammation, which has an outlook beyond the traditional view, as proposed in our previous work. In this review, we discuss the effects of CR on multiple phases of proinflammatory networks and inflammatory signaling pathways to elucidate the basic mechanism underlying aging. Based on studies on senoinflammation and CR, we recognized that senescence-associated secretory phenotype (SASP), which mainly comprises cytokines and chemokines, was significantly increased during aging, whereas it was suppressed during CR. Further, we recognized that cellular metabolic pathways were also dysregulated in aging; however, CR mimetics reversed these effects. These results further support and enhance our understanding of the novel concept of senoinflammation, which is related to the metabolic changes that occur in the aging process. Furthermore, a thorough elucidation of the effect of CR on senoinflammation will reveal key insights and allow possible interventions in aging mechanisms, thus contributing to the development of new therapies focused on improving health and longevity.

Quantity and quality of the peroneus longus assessed using ultrasonography in leg with chronic ankle instability

[Purpose] Muscle quantity (e.g., cross-sectional area) and quality (e.g., muscle adipose tissue), which are muscle strength determinants, can be assessed using ultrasonography. The study aimed to investigate the changes in the quantity and quality of the peroneus longus and evaluate evertor strength in legs with chronic ankle instability (CAI). Furthermore, the associations among cross-sectional area, echogenicity, evertor strength, and frequency of ankle sprain were examined. [Participants and Methods] Nine males with CAI in unilateral legs were the voluntary participants in this study. The cross-sectional area of the peroneus longus, echogenicity, and evertor strength were measured for all the participants on the sides with CAI and that without. [Results] No significant difference in cross-sectional area was observed between the sides. Significant differences in echogenicity (higher on the CAI side) and evertor strength (lower on the CAI side) were observed between the sides. In addition, a moderate correlation was observed between echogenicity and increased sprain frequency on both sides. [Conclusion] Muscle adipose tissue increased, evertor strength decreased, and the cross-sectional area remained unchanged on the CAI side. The study results suggested that muscle adipose tissue increases with increasing frequency of ankle sprain.

Hepatic lipid metabolism and non-alcoholic fatty liver disease in aging

Aging is associated with dysregulation of glucose and lipid metabolism. Various factors that contribute to the dysregulation include both modifiable (e.g. obesity, insulin resistance) and non-modifiable risk factors (age-associated physiologic changes). Although there is no linear relationship between aging and prevalence of non-alcoholic fatty liver disease, current data strongly suggests that advanced age leads to more severe histological changes and poorer clinical outcomes. Hepatic lipid accumulation could lead to significant hepatic and systemic consequences including steatohepatitis, cirrhosis, impairment of systemic glucose metabolism and metabolic syndrome, thereby contributing to age-related diseases. Insulin, leptin and adiponectin are key regulators of the various physiologic processes that regulate hepatic lipid metabolism. Recent advances have expanded our understanding in this field, highlighting the role of novel mediators such as FGF 21, and mitochondria derived peptides. In this review, we will summarize the mediators of hepatic lipid metabolism and how they are altered in aging.

Peroxisome proliferator-activated receptor agonists in a battle against the aging kidney

As aging is a complex phenomenon characterized by intraindividual and interindividual diversities in the maintenance of the homeostatic condition of cells and tissues, changes in renal function are not uniform and depend on associated diseases and environmental factors. Multiple studies have investigated the possible underlying mechanisms of age-related decline in kidney function. Evolutionary, molecular, cellular and systemic theories have been postulated to explain the primary disease independent age-related changes and adaptive responses. As peroxisome proliferator-activated receptors (PPARs) are involved in a broad spectrum of biological processes, PPAR activation might have an effect on the prevention of cell senescence. In this review, we will focus on the experimental and clinical evidence of PPAR agonists in a battle against the aging kidney.

Roles of nonmyogenic mesenchymal progenitors in pathogenesis and regeneration of skeletal muscle

Adult skeletal muscle possesses a remarkable regenerative ability that is dependent on satellite cells. However, skeletal muscle is replaced by fatty and fibrous connective tissue in several pathological conditions. Fatty and fibrous connective tissue becomes a major cause of muscle weakness and leads to further impairment of muscle function. Because the occurrence of fatty and fibrous connective tissue is usually associated with severe destruction of muscle, the idea that dysregulation of the fate switch in satellite cells may underlie this pathological change has emerged. However, recent studies identified nonmyogenic mesenchymal progenitors in skeletal muscle and revealed that fatty and fibrous connective tissue originates from these progenitors. Later, these progenitors were also demonstrated to be the major contributor to heterotopic ossification in skeletal muscle. Because nonmyogenic mesenchymal progenitors represent a distinct cell population from satellite cells, targeting these progenitors could be an ideal therapeutic strategy that specifically prevents pathological changes of skeletal muscle, while preserving satellite cell-dependent regeneration. In addition to their roles in pathogenesis of skeletal muscle, nonmyogenic mesenchymal progenitors may play a vital role in muscle regeneration by regulating satellite cell behavior. Conversely, muscle cells appear to regulate behavior of nonmyogenic mesenchymal progenitors. Thus, these cells regulate each other reciprocally and a proper balance between them is a key determinant of muscle integrity. Furthermore, nonmyogenic mesenchymal progenitors have been shown to maintain muscle mass in a steady homeostatic condition. Understanding the nature of nonmyogenic mesenchymal progenitors will provide valuable insight into the pathophysiology of skeletal muscle. In this review, we focus on nonmyogenic mesenchymal progenitors and discuss their roles in muscle pathogenesis, regeneration, and homeostasis.

Evidence for association of mitochondrial metabolism alteration with lipid accumulation in aging rats

Adipogenesis and lipid accumulation during aging have a great impact on the aging process and the pathogenesis of chronic, age-related diseases. However, little is known about the age-related molecular changes in lipid accumulation and the mechanisms underlying them. Here, using 5-month- and 25-month-old rats (young and old, respectively), we found that epididymal fat is the only tissue to accumulate during aging. By testing tissues rich with mitochondria in old and young animals, we found that the old animals had elevated levels of triglycerides in their muscle, heart and liver tissues but not in their kidneys, while, the mRNA level of fatty acid synthase remained unchanged among the four tissues. Regarding lipid catabolism, we determined that the activities of mitochondrial ETC. complexes changed in aged rats (muscle: decreased complex I and V activities; heart: decreased complex I activity; liver: increased complex I and III activities; kidney: decreased complex I and increased complex II activities), while changes in mitochondrial content were not observed in the muscle, heart nor in the liver tissue except increased complex IV and V subunits in aged kidneys. Furthermore, decreased mitochondrial fusion marker Mfn2 and decreased PGC-1α level were observed in the aged muscle, heart and liver but remained unchanged in the kidneys. Down-regulation of Mfn2 with siRNA in 293T cells induced significant mitochondrial dysfunction including decreased oxygen consumption, decreased ATP production, and increased ROS production, followed by increased triglyceride content suggesting a contributing role of decreased mitochondrial fusion to lipid deposit. Meanwhile, judging from autophagy marker p62/SQSTM1 and LC3-II, autophagy was suppressed in the aged muscle, heart and liver but remained unchanged in the kidneys. Taken together, these data suggest that reduction in PGC-1α expression and disruption of mitochondrial dynamics and autophagy might contribute to lipid accumulation during aging.

Metabolomics reveals that carnitine palmitoyltransferase-1 is a novel target for oxidative inactivation in human cells

Oxidative dysfunction in the metabolism has long been implicated in diverse biological disorders. Although a substantial number of metabolic enzymes are targeted for inactivation by oxidative stress, identifying those targets remains difficult due to a lack of comprehensive observations of the metabolism acting through the stress response. We herein developed a metabolomics strategy using integrative liquid chromatography-mass spectrometry (LC-MS) and observing rapid metabolomic changes in response to hydrogen peroxide (H2 O2 )-induced oxidative stress in HeLa cells. Among the many metabolite changes detected, the most characteristic metabolites uniquely indicated carnitine palmitoyltransferase-1 (CPT1), the critical enzyme for mitochondrial β-oxidation of long-chain fatty acids, to be a target for oxidative inactivation. We showed that the enzymatic activity of CPT1 significantly declined by H2 O2 in several human cells. Interestingly, the inactivation was shown to be a direct effect of H2 O2 in vitro, but substantially occurred when cells were cultured with some reagents that generate reactive oxygen species (ROS). Thus, our results suggest the generality of CPT1 inhibition under various stress conditions associated with ROS generation, providing an insight into a mechanism for oxidative dysfunction in mitochondrial metabolism. Our metabolome data additionally suggest that certain methyltransferase(s) may be targets of oxidative stress as well.

Acetyl-L-carnitine supplementation reverses the age-related decline in carnitine palmitoyltransferase 1 (CPT1) activity in interfibrillar mitochondria without changing the L-carnitine content in the rat heart

The aging heart displays a loss of bioenergetic reserve capacity partially mediated through lower fatty acid utilization. We investigated whether the age-related impairment of cardiac fatty acid catabolism occurs, at least partially, through diminished levels of L-carnitine, which would adversely affect carnitine palmitoyltransferase 1 (CPT1), the rate-limiting enzyme for fatty acyl-CoA uptake into mitochondria for β-oxidation. Old (24-28 mos) Fischer 344 rats were fed±acetyl-L-carnitine (ALCAR; 1.5% [w/v]) for up to four weeks prior to sacrifice and isolation of cardiac interfibrillar (IFM) and subsarcolemmal (SSM) mitochondria. IFM displayed a 28% (p<0.05) age-related loss of CPT1 activity, which correlated with a decline (41%, p<0.05) in palmitoyl-CoA-driven state 3 respiration. Interestingly, SSM had preserved enzyme function and efficiently utilized palmitate. Analysis of IFM CPT1 kinetics showed both diminished V(max) and K(m) (60% and 49% respectively, p<0.05) when palmitoyl-CoA was the substrate. However, no age-related changes in enzyme kinetics were evident with respect to L-carnitine. ALCAR supplementation restored CPT1 activity in heart IFM, but not apparently through remediation of L-carnitine levels. Rather, ALCAR influenced enzyme activity over time, potentially by modulating conditions in the aging heart that ultimately affect palmitoyl-CoA binding and CPT1 kinetics.

Usefulness of preclinical models for assessing the efficacy of late-life interventions for sarcopenia

Caloric restriction and physical exercise have proven beneficial against age-associated changes in body composition and declining physical performance; however, little is known regarding what benefit these interventions might have when initiated late in life. The study of mimetics of diet and exercise and the combination thereof may provide additional treatments for a vulnerable elderly population; however, how and when to initiate such interventions requires consideration in developing the most safe and efficacious treatment strategies. In this review, we focus on preclinical late-life intervention studies, which assess the relationship between physical function, sarcopenia, and body composition. We provide a conceptual framework for the ever-changing definition of sarcopenia and a rationale for the use of an appropriate rodent model of this condition. We finish by providing our perspective regarding the implications of this body of work and future areas of research that may also contribute to the ultimate goal of extending healthspan.

Vitamin C deficiency attenuates liver fibrosis by way of up-regulated peroxisome proliferator-activated receptor-gamma expression in senescence marker protein 30 knockout mice

Senescence marker protein 30 (SMP30), an important aging marker molecule that is highly expressed in the liver, has been known to protect hepatocytes from apoptosis by the synthesis of vitamin C. To explore the function of SMP30 in liver fibrosis, the effect of SMP30 deficiency on liver fibrosis was investigated in SMP30 knockout (KO) mice. Moreover, the in vivo results were further confirmed by way of hepatic stellate cell (HSC) isolation. We demonstrated that carbon tetrachloride (CCl(4))-induced liver fibrosis and the nuclear translocation of p-Smad2/3, the immediate downstream of transforming growth factor beta (TGF-beta), were significantly inhibited in the liver of SMP30 KO mice compared with wildtype (WT) mice. We also confirmed that both WT and SMP30 KO HSCs did not express SMP30. Finally, we further confirmed that up-regulation of peroxisome proliferator-activated receptor-gamma (PPAR-gamma) caused by a lack of vitamin C was the pivotal factor in the mechanisms for attenuated liver fibrosis of SMP30 KO mice, and feeding with vitamin C restored CCl(4)-induced liver fibrosis in SMP30 KO mice.

CONCLUSION

Vitamin C deficiency by SMP30 depletion attenuated liver fibrosis by way of up-regulated PPAR-gamma expression in SMP30 KO mice. Our results provide, for the first time, the possible mechanisms underlying inhibition of HSC activation associated with vitamin C and PPAR-gamma up-regulation in liver fibrosis of SMP30 KO mice.