Extending healthy life span--from yeast to humans

Xenohormetic, hormetic and cytostatic selective forces driving longevity at the ecosystemic level

We recently found that lithocholic acid (LCA), a bile acid, extends yeast longevity. Unlike mammals, yeast do not synthesize bile acids. We therefore propose that bile acids released into the environment by mammals may act as interspecies chemical signals providing longevity benefits to yeast and, perhaps, other species within an ecosystem.

Metabolic syndrome, hormones, and maintenance of T cells during aging

Although the phenotype of T-cell senescence has been extensively investigated, few studies have analyzed the factors that promote the generation and maintenance of naïve and memory T cells that exist throughout the lifespan of the individuals. Unlike senescent T cells, naïve and memory T cells are able to participate in useful immune responses as well as respond to new activation. Hormones such as leptin, ghrelin, insulin-like growth factor 1, IGFBP3, and cytokines, including IL-7, regulate both thymopoiesis and maintenance of naïve T cells in the periphery. Although chronic viruses such as cytomegalovirus (CMV) are thought to drive T-cell senescence, other microbes may be important for the maintenance of nonsenescent T cells. Microbiota of the gut can induce metabolic syndrome as well as modulate T-cell development into specific subpopulations of effector cells. Finally, T-cell generation, maintenance, and apoptosis depend upon pathways of energy utilization within the T cells, which parallel those that regulate overall metabolism. Therefore, better understanding of metabolic syndrome, T-cell metabolism, hormones, and microbiota may lead to new insights into the maintenance of proper immune responses in old age.

Metabolic networks of longevity

Molecular and cellular networks implicated in aging depend on a multitude of proteins that collectively mount adaptive and contingent metabolic responses to environmental challenges. Here, we discuss the intimate links between metabolic regulation and longevity and outline new approaches for analyzing and manipulating such links to promote human health span.

Calorie restriction for optimal cardiovascular aging: the weight of evidence

The epidemic of obesity and overweight is spreading worldwide. Excessive adiposity is associated with a myriad of adverse health outcomes, leading to increased healthcare expenditures and shortened life expectancy. In contrast to overeating, calorie restriction (CR), defined as a reduction in food intake without malnutrition, increases both mean and maximum lifespan in a variety of species by reducing the incidence of several chronic degenerative diseases, including cardiovascular disease. The constellation of health benefits brought about by CR results from biological and physiological changes affecting fundamental processes underlying aging and age-related pathologies. Despite the beneficial properties of CR, it is likely that most people will not engage in such a dietary regimen for the long-term. Supplementation with specific compounds mimicking CR may represent a more feasible means to improve health and prolong life. However, evidence on long-term effectiveness and safety of these compounds is not yet available in humans.

Does ageing originate in utero?

Ageing still remains a conundrum on the cellular and molecular level, while environmental factors and interactions further increase the complexity of the ageing process. On the other hand is cancer, for which 20 years ago, it was proposed by Trichopoulos that it might have intrauterine origin. We herein discuss the idea that parameters such as the influence of insulin-like growth factor (IGF) signalling, of hormones and of the number of stem cells, as well as the effect of foetal and early life nutrition on ageing may also commence in utero and we provide epidemiological and biological data to advocate for this hypothesis. Finally, we analyse the public health implication of this hypothesis based on the World Health Organization (WHO) report that the burden of diseases, including ageing, may be due to impaired foetal development.

Longevity mutants do not establish any "new science" of ageing

The biological reasons for ageing are now well known, so it is no longer an unsolved problem in biology. Furthermore, there is only one science of ageing, which is continually advancing. The significance and importance of the mutations that lengthen the lifespan of invertebrates can be assessed only in relationship to previous well-established studies of ageing. The mutant strains of model organisms that increase longevity have altered nutrient signalling pathways similar to the effects of dietary restriction, and so it is likely that there is a shift in the trade-off between reproduction and maintenance of the soma. To believe that the isolation and characterisation of a few invertebrate mutations (as well as those in yeast) will "galvanise" the field and provide new insights into human ageing is an extreme point of view which does not recognize the huge progress in ageing research that has been made in the last 50 years or so.