A preliminary attempt to establish multiple stress response profiles of human skin fibroblasts exposed to mild or severe stress during ageing in vitro

Changing dynamics in daily rhythms of oxidative stress indicators in SCN and extra-SCN brain regions with aging in male Wistar rats

The suprachiasmatic nucleus (SCN) in the hypothalamus regulates circadian timing system (CTS) by co-ordinating peripheral tissue clocks and extra-SCN oscillators in the brain. Aging disrupts the CTS, impairing physiological functions and reducing antioxidant defences, which contribute to neurodegeneration. The brain is vulnerable to oxidative damage due to its high metabolic activity, oxygen consumption, and levels of iron and lipids. Antioxidant enzymes, such as catalase (CAT), glutathione S-transferase (GST), superoxide dismutase (SOD), and lipid peroxidation (LPO), help against oxidative damage. In this study, we examined the temporal patterns of these antioxidant stress indicators in the SCN and extra-SCN brain regions (frontal cortex, cerebellum, and hippocampus) at various time points in male Wistar rats 3, 12, and 24 months. The rhythmicity of GST and LPO levels persisted across brain regions with aging, while CAT rhythmicity was lost in the SCN and hippocampus of older rats. SOD rhythmicity persisted in cortex, cerebellum, and hippocampus but was lost in the SCN. The daily rhythm parameters of CAT were affected most significantly, followed by SOD, GST, and LPO. Our findings demonstrate that aging leads to desynchronization of oxidative stress indicators potentially contributing to neurodegeneration and circadian dysfunction with varying effects across different brain tissues.

Seven knowledge gaps in modern biogerontology

About a year ago, members of the editorial board of Biogerontology were requested to respond to a query by the editor-in-chief of the journal as to what one question within their field of ageing research still needs to be asked and answered. This editorial is inspired by the wide range and variety of questions, ideas, comments and suggestions received in response to that query. The seven knowledge gaps identified in this article are arranged into three main categories: evolutionary aspects of longevity, biological survival and death aspects, and heterogeneity in the progression and phenotype of ageing. This is not an exhaustive and exclusive list, and may be modified and expanded. Implications of these knowledge gaps, especially in the context of ongoing attempts to develop effective interventions in ageing and longevity are also discussed.

A Clinical and Biochemical Evaluation of a Temperature-Controlled Continuous Non-Invasive Radiofrequency Device for the Treatment of Melasma

Background

Melasma shows characteristic histological features of photoaged skin.

Objective

We evaluated the effect of dermal rejuvenation using a temperature-controlled continuous non-invasive radiofrequency (RF) device on melasma.

Methods

Continuous skin heating at the temperature of 43°C for 20 minutes was performed in ten subjects with melasma who underwent 3 tri-weekly RF sessions. Pigmentation was evaluated with Mexameter® and investigator’s global assessment (IGA). Immunohistochemical staining and image analysis was performed to evaluate biopsies from melasma skin before and after the treatment.

Results

The lesional melanin index was decreased by 13.7% at week 9. IGA score was improved from 3.50 at baseline to 2.95 at week 9. No significant adverse event was reported. Histologic analysis revealed reduced melanin and increased collagen density and thickness. The expression of procollagen-1 and type IV collagen was increased after the treatment. The number of p16^INK4A-positive senescent fibroblasts was reduced after the treatment, while the expression of heat shock protein 70 and 90 was increased. Stromal derived factor-1, a senescence-associated anti-melanogenic factor secreted from the fibroblasts, was up-regulated after the treatment, while the level of c-kit was not changed.

Conclusion

Thermal skin stimulation by the temperature-controlled continuous RF device improved melasma through dermal rejuvenation.

Negative genetic correlation between longevity and its hormetic extension by dietary restriction in Drosophila melanogaster

Longevity is a highly malleable trait which is influenced by many genetic and environmental factors including nutrition. Mild stress of dietary restriction (DR) is often beneficial by extending longevity in many organisms. Here, DR-induced effects on longevity were tested for genetic variation in a set of recombinant inbred lines (RIL) in D. melanogaster. Genetic variability was significant in the longevity response following a DR-treatment across RIL, with detrimental effects in several RIL but beneficial effects in other RIL. One quantitative trait locus (QTL) was consistently significant in the middle of chromosome 2 for DR-induced changes in longevity, including hormesis (an increase in longevity by DR). Another QTL co-localized with a previously found QTL for starvation resistance in females. Several other QTL were also significant on most chromosomal arms. Longevity in controls was negatively correlated to DR effects across RIL for longevity in females, the sex showing higher DR-induced hormesis. This negative genetic correlation highlights the importance to further investigate the effects of genetic variation in the strength of DR-induced hormesis in longevity and its sex-specificity.

Naive extrapolations, overhyped claims and empty promises in ageing research and interventions need avoidance

Most proclamations about another wonder breakthrough and another imminent miracle treatment of ageing are usually overhyped claims and empty promises. It is not that the experimental science behind those claims is totally wrong or fake. But it is often a case of being ahistorical and ignoring the cumulated knowledge and understanding of the evolutionary and biological principles of ageing and longevity. Furthermore, remaining stuck to the body-as-a-machine viewpoint reduces ageing and its associated health challenges to a mere problem of engineering and design. However, highly dynamic nature of the living systems with properties of interaction, interdependence, tolerance, adaptation and constant remodelling requires wholistic and interactive modes of understanding and maintaining health. The physiological relevance and significance of progressively accumulating molecular damage remains to be fully understood. As for ageing interventions, the three pillars of health-food, physical activity, and social and mental engagement-which actually show health-promoting effect, cannot simply be reduced to a single or a limited number of molecular targets with hopes of creating an exercise pill, a fasting pill, a happiness pill and so on. If we want to increase the credibility and socio-political-economic support of ageing research and interventions, we need to resist the temptation to overhype the claims or to make far-fetched promises, which undermine the theoretical and practical significance of new discoveries in biogerontology.

Exercise-Induced Mitohormesis for the Maintenance of Skeletal Muscle and Healthspan Extension

Oxidative damage is one mechanism linking aging with chronic diseases including the progressive loss of skeletal muscle mass and function called sarcopenia. Thus, mitigating oxidative damage is a potential avenue to prevent or delay the onset of chronic disease and/or extend healthspan. Mitochondrial hormesis (mitohormesis) occurs when acute exposure to stress stimulates adaptive mitochondrial responses that improve mitochondrial function and resistance to stress. For example, an acute oxidative stress via mitochondrial superoxide production stimulates the activation of endogenous antioxidant gene transcription regulated by the redox sensitive transcription factor Nrf2, resulting in an adaptive hormetic response. In addition, acute stresses such as aerobic exercise stimulate the expansion of skeletal muscle mitochondria (i.e., mitochondrial biogenesis), constituting a mitohormetic response that protects from sarcopenia through a variety of mechanisms. This review summarized the effects of age-related declines in mitochondrial and redox homeostasis on skeletal muscle protein homeostasis and highlights the mitohormetic mechanisms by which aerobic exercise mitigates these age-related declines and maintains function. We discussed the potential efficacy of targeting the Nrf2 signaling pathway, which partially mediates adaptation to aerobic exercise, to restore mitochondrial and skeletal muscle function. Finally, we highlight knowledge gaps related to improving redox signaling and make recommendations for future research.