Stress Resistance Screen in a Human Primary Cell Line Identifies Small Molecules That Affect Aging Pathways and Extend Caenorhabditis elegans' Lifespan

Chili pepper extends lifespan in a concentration-dependent manner and confers cold resistance on Drosophila melanogaster cohorts by influencing specific metabolic pathways

Chili powder is a widely used spice with pungent taste, often consumed on a daily basis in several countries. Recent prospective cohort studies showed that the regular use of chili pepper improves healthspan in humans. Indeed, chili pepper fruits contain phenolic substances which are structurally similar to those that show anti-aging properties. The objective of our study was to test whether consumption of chili-supplemented food by the fruit fly, Drosophila melanogaster, would prolong lifespan and in which way this chili-supplemented food affects animal metabolism. Chili powder added to food in concentrations of 0.04%-0.12% significantly extended median lifespan in fruit fly cohorts of both genders by 9% to 13%. However, food supplemented with 3% chili powder shortened lifespan of male cohorts by 9%. Lifespan extension was accompanied by a decrease in age-independent mortality (i.e., death in early ages). The metabolic changes caused by consumption of chili-supplemented food had a pronounced dependence on gender. A characteristic of both fruit fly sexes that ate chili-supplemented food was an increased resistance to cold shock. Flies of both sexes had lower levels of hemolymph glucose when they ate food supplemented with low concentrations of chili powder, as compared with controls. However, males fed on food with 3% chili had lower levels of storage lipids and pyruvate reducing activity of lactate dehydrogenase compared with controls. Females fed on this food showed lower activities of hexokinase and pyruvate kinase, as well as lower ADP/O ratios, compared with control flies.

Caloric Restriction Mimetics in Nutrition and Clinical Trials

The human diet and dietary patterns are closely linked to the health status. High-calorie Western-style diets have increasingly come under scrutiny as their caloric load and composition contribute to the development of non-communicable diseases, such as diabetes, cancer, obesity, and cardiovascular disorders. On the other hand, calorie-reduced and health-promoting diets have shown promising results in maintaining health and reducing disease burden throughout aging. More recently, pharmacological Caloric Restriction Mimetics (CRMs) have gained interest of the public and scientific community as promising candidates that mimic some of the myriad of effects induced by caloric restriction. Importantly, many of the CRM candidates activate autophagy, prolong life- and healthspan in model organisms and ameliorate diverse disease symptoms without the need to cut calories. Among others, glycolytic inhibitors (e.g., D-allulose, D-glucosamine), hydroxycitric acid, NAD+ precursors, polyamines (e.g., spermidine), polyphenols (e.g., resveratrol, dimethoxychalcones, curcumin, EGCG, quercetin) and salicylic acid qualify as CRM candidates, which are naturally available via foods and beverages. However, it is yet unclear how these bioactive substances contribute to the benefits of healthy diets. In this review, we thus discuss dietary sources, availability and intake levels of dietary CRMs. Finally, since translational research on CRMs has entered the clinical stage, we provide a summary of their effects in clinical trials.

Augmentation of the heat shock axis during exceptional longevity in Ames dwarf mice

How the heat shock axis, repair pathways, and proteostasis impact the rate of aging is not fully understood. Recent reports indicate that normal aging leads to a 50% change in several regulatory elements of the heat shock axis. Most notably is the age-dependent enhancement of inhibitory signals associated with accumulated heat shock proteins and hyper-acetylation associated with marked attenuation of heat shock factor 1 (HSF1)–DNA binding activity. Because exceptional longevity is associated with increased resistance to stress, this study evaluated regulatory check points of the heat shock axis in liver extracts from 12 months and 24 months long-lived Ames dwarf mice and compared these findings with aging wild-type mice. This analysis showed that 12M dwarf and wild-type mice have comparable stress responses, whereas old dwarf mice, unlike old wild-type mice, preserve and enhance activating elements of the heat shock axis. Old dwarf mice thwart negative regulation of the heat shock axis typically observed in usual aging such as noted in HSF1 phosphorylation at Ser307 residue, acetylation within its DNA binding domain, and reduction in proteins that attenuate HSF1–DNA binding. Unlike usual aging, dwarf HSF1 protein and mRNA levels increase with age and further enhance by stress. Together these observations suggest that exceptional longevity is associated with compensatory and enhanced HSF1 regulation as an adaptation to age-dependent forces that otherwise downregulate the heat shock axis.

Drug discovery: Insights from the invertebrate Caenorhabditis elegans

Therapeutic drug development is a long, expensive, and complex process that usually takes 12-15 years. In the early phases of drug discovery, in particular, there is a growing need for animal models that ensure the reduction in both cost and time. Caenorhabditis elegans has been traditionally used to address fundamental aspects of key biological processes, such as apoptosis, aging, and gene expression regulation. During the last decade, with the advent of large-scale platforms for screenings, this invertebrate has also emerged as an essential tool in the pharmaceutical research industry to identify novel drugs and drug targets. In this review, we discuss the reasons why C. elegans has been positioned as an outstanding cost-effective option for drug discovery, highlighting both the advantages and drawbacks of this model. Particular attention is paid to the suitability of this nematode in large-scale genetic and pharmacological screenings. High-throughput screenings in C. elegans have indeed contributed to the breakthrough of a wide variety of candidate compounds involved in extensive fields including neurodegeneration, pathogen infections and metabolic disorders. The versatility of this nematode, which enables its instrumentation as a model of human diseases, is another attribute also herein underscored. As illustrative examples, we discuss the utility of C. elegans models of both human neurodegenerative diseases and parasitic nematodes in the drug discovery industry. Summing up, this review aims to demonstrate the impact of C. elegans models on the drug discovery pipeline.

High-throughput small molecule screening reveals Nrf2-dependent and -independent pathways of cellular stress resistance

Aging is the dominant risk factor for most chronic diseases. Development of antiaging interventions offers the promise of preventing many such illnesses simultaneously. Cellular stress resistance is an evolutionarily conserved feature of longevity. Here, we identify compounds that induced resistance to the superoxide generator paraquat (PQ), the heavy metal cadmium (Cd), and the DNA alkylator methyl methanesulfonate (MMS). Some rescue compounds conferred resistance to a single stressor, while others provoked multiplex resistance. Induction of stress resistance in fibroblasts was predictive of longevity extension in a published large-scale longevity screen in Caenorhabditis elegans, although not in testing performed in worms and flies with a more restricted set of compounds. Transcriptomic analysis and genetic studies implicated Nrf2/SKN-1 signaling in stress resistance provided by two protective compounds, cardamonin and AEG 3482. Small molecules identified in this work may represent attractive tools to elucidate mechanisms of stress resistance in mammalian cells.

Antistress and anti-aging activities of Caenorhabditis elegans were enhanced by Momordica saponin extract

BACKGROUND

Momordica saponin extract (MSE) was found to not only improve longevity and neuroprotection but also alleviate fat accumulation in Caenorhabditis elegans in our previous study. However, the lipid-lowering activity of MSE alone could not fully explain its ability to improve health, so the antistress effects of MSE were further studied.

METHODS

Using C. elegans as an in vivo animal, the lifespan of MSE-treated C. elegans under various stressors (H₂O₂, paraquat and heat) and normal conditions was studied. Furthermore, the antioxidant activities of MSE were discussed. To study the underlying mechanisms, the expression of stress resistance genes and the resistance of related mutants to H₂O₂ stress were tested.

RESULTS

MSE significantly improved the lifespan of C. elegans under stress and normal conditions. Meanwhile, the mobility of C. elegans was also improved. Moreover, the activities of SOD and CAT and the ratio of GSH/GSSG were elevated. Consistently, the levels of ROS and lipid oxidation (the NEFA and MDA content) were reduced. Furthermore, MSE treatment upregulated the expression of the sod-3, sod-5, clt-1, clt-2, hsp-16.1 and hsp-16.2 genes. All biomarkers indicated that the antistress and anti-aging activities of MSE were due to its strong antioxidant activities. Finally, MSE induced nuclear DAF-16::GFP localization. Studies with mutants revealed that skn-1 and hsf-1 were involved in the activity of MSE, which might upregulate the expression of downstream stress-responsive genes.

CONCLUSIONS

Therefore, in addition to its lipid-lowering property, the ability of MSE to improve healthspan was also attributed to the stress resistance effect. Together, MSE might serve as a lead nutraceutical in geriatric research.

Structural basis of the anti-ageing effects of polyphenolics: mitigation of oxidative stress

Ageing, and particularly the onset of age-related diseases, is associated with tissue dysfunction and macromolecular damage, some of which can be attributed to accumulation of oxidative damage. Polyphenolic natural products such as stilbenoids, flavonoids and chalcones have been shown to be effective at ameliorating several age-related phenotypes, including oxidative stress, inflammation, impaired proteostasis and cellular senescence, both in vitro and in vivo. Here we aim to identify the structural basis underlying the pharmacology of polyphenols towards ROS and related biochemical pathways involved in age-related disease. We compile and describe SAR trends across different polyphenol chemotypes including stilbenoids, flavonoids and chalcones, review their different molecular targets and indications, and identify common structural ground between chemotypes and mechanisms of action. In particular, we focus on the structural requirements for the direct scavenging of reactive oxygen/nitrogen species such as radicals as well as coordination of a broader antioxidant response. We further suggest that it is important to consider multiple (rather than single) biological activities when identifying and developing new medicinal chemistry entities with utility in modulating complex biological properties such as cell ageing.

Phenotypic Screening in C. elegans as a Tool for the Discovery of New Geroprotective Drugs

Population aging is one of the largest challenges of the 21st century. As more people live to advanced ages, the prevalence of age-related diseases and disabilities will increase placing an ever larger burden on our healthcare system. A potential solution to this conundrum is to develop treatments that prevent, delay or reduce the severity of age-related diseases by decreasing the rate of the aging process. This ambition has been accomplished in model organisms through dietary, genetic and pharmacological interventions. The pharmacological approaches hold the greatest opportunity for successful translation to the clinic. The discovery of such pharmacological interventions in aging requires high-throughput screening strategies. However, the majority of screens performed for geroprotective drugs in C. elegans so far are rather low throughput. Therefore, the development of high-throughput screening strategies is of utmost importance.