Aging: All roads lead to mitochondria

Associations Between Walking Pace, APOE-ε4 Genotype, and Brain Health in Middle-Aged to Older Adults

PURPOSE

This study aimed to investigate whether self-reported walking pace (a marker of physical function) and the presence of APOE-ε4 allele interact to modify brain health outcomes.

METHODS

We used data from a prospective cohort study of middle-aged to older adults from the UK Biobank who self-reported walking pace (slow or steady-to-brisk) and who were initially free of dementia ( n = 415,110). Incident all-cause dementia was obtained from hospital and death registry records, and structural brain volumes (right and left hippocampus volumes, total gray matter volume, and volume of white matter hyperintensities) were measured from a subset of participants ( n = 33,113). Cox proportional hazard models and generalized linear models were used to assess associations between exposures and outcomes.

RESULTS

Slow walking pace and the presence of APOE-ε4 allele were associated with increased dementia risk (HR = 1.79 [95% CI = 1.66-1.93], P < 0.001; HR = 3.06 [2.90-3.23], P < 0.001, respectively), and there was an interaction between these associations, indicating that the association of walking pace with dementia risk is modified by APOE-ε4 status (reference group: HR Steady-Brisk/APOE-ε4- = 1; HR Slow/APOE-ε4- = 2.03 [1.84-2.25], P < 0.001; HR Steady-Brisk/APOE-ε4+ = 3.21 [3.02-3.41], P < 0.001; HR Slow/APOE-ε4+ = 4.99 [4.48-5.58], P < 0.001). Slow self-reported walking pace was associated with worse brain volume outcomes, and these associations were not modified by APOE-ε4 genotype.

CONCLUSIONS

These results suggest walking pace and APOE-ε4 status independently influence brain volume outcomes, but both factors independently and jointly contribute to increased dementia risk. Individuals with both risk factors (slow walking pace and APOE-ε4 allele) show the strongest associations with dementia risk.

Mitochondria in focus: From structure and function to their role in human diseases. A review

Mitochondria, double-membraned organelles within all eukaryotic cells, are essential for the proper functioning of the human organism. The frequently used phrase "powerhouses of the cell" fails to adequately capture their multifaceted roles. In addition to producing energy in the form of adenosine triphosphate through oxidative phosphorylation, mitochondria are also involved in apoptosis (programmed cell death), calcium regulation, and signaling through reactive oxygen species. Recent research suggests that they can communicate with one another and influence cellular processes. Impaired mitochondrial function on the one hand, can have widespread and profound effects on cellular and organismal health, contributing to various diseases and age-related conditions. Regular exercise on the other hand, promotes mitochondrial health by enhancing their volume, density, and functionality. Although research has made significant progress in the last few decades, mainly through the use of modern technologies, there is still a need to intensify research efforts in this field. Exploring new approaches to enhance mitochondrial health could potentially impact longevity. In this review, we focus on mitochondrial research and discoveries, examine the structure and diverse roles of mitochondria in the human body, explore their influence on energy metabolism and cellular signaling and emphasize their importance in maintaining overall health.

The Role of Mitochondrial Pyruvate Carrier in Neurological Disorders

The mitochondrial pyruvate carrier (MPC) is a specific protein complex located in the inner mitochondrial membrane. Comprising a heterodimer of two homodimeric membrane proteins, mitochondrial pyruvate carrier 1 and mitochondrial pyruvate carrier 2, MPC connects cytoplasmic metabolism to mitochondrial metabolism by transferring pyruvate from the cytoplasm to the mitochondria. The nervous system requires substantial energy to maintain its function, and the mitochondrial energy supply is closely linked to neurological function. Mitochondrial dysfunction can induce or exacerbate intracerebral pathologies. MPC influences mitochondrial function due to its specific role as a pyruvate transporter. However, recent studies on MPC and mitochondrial dysfunction in neurological disorders have yielded controversial results, and the underlying mechanisms remain unclear. In this brief review, we provide an overview of the structure and function of MPC. We further discuss the potential mechanisms and feasibility of targeting MPC in treating Parkinson's disease, Alzheimer's disease, and cerebral ischemia/hypoxia injury. This review aims to offer insights into MPC as a target for clinical treatment.

The mitochondrial and cytoplasmic superoxide anion imbalance trigger the expression of certain cellular aging markers in HaCaT keratinocytes

In cells, the term "cellular aging" represents a collection of biological changes that can precede the proliferative senescence states. Cells more resistant to proliferative senescence, such as the ones found in the basal layer of the epidermis, may also exhibit these aging patterns. Therefore, cellular aging events could be induced by endogenous signals named here as cellular aging triggers (CATs) components. The superoxide anion (O2⁻) could be a prime candidate for a CATs, as it is continuously produced by eukaryotic cells. To test this hypothesis, mitochondrial and cytoplasmic O2⁻ imbalances were induced in HaCaT keratinocytes using rotenone (ROT, 30 µM), which inhibits mitochondrial complex I and paraquat (PQT, 30 µM), which increases O2⁻ levels via redox cycling. ROT and PQT reduced cellular proliferation rate and elevated β-Galactosidase and transforming growth factor beta (TGF-β) levels. Furthermore, they increased the frequency of larger cells with nuclear alterations, the levels of oxidative markers, and interleukin 1β, a marker of the Senescence-Associated Secretory Phenotype (SASP). However, the mitochondrial O2⁻ imbalance caused by ROT led to more pronounced alterations compared to PQT. These findings support the hypothesis that the existence of CAT components, such as the O2⁻ anion, plays a significant role in cellular aging.

Inter- and intracellular mitochondrial communication: signaling hubs in aging and age-related diseases

Mitochondria are versatile and complex organelles that can continuously communicate and interact with the cellular milieu. Deregulated communication between mitochondria and host cells/organelles has significant consequences and is an underlying factor of many pathophysiological conditions, including the process of aging. During aging, mitochondria lose function, and mitocellular communication pathways break down; mitochondrial dysfunction interacts with mitochondrial dyscommunication, forming a vicious circle. Therefore, strategies to protect mitochondrial function and promote effective communication of mitochondria can increase healthy lifespan and longevity, which might be a new treatment paradigm for age-related disorders. In this review, we comprehensively discuss the signal transduction mechanisms of inter- and intracellular mitochondrial communication, as well as the interactions between mitochondrial communication and the hallmarks of aging. This review emphasizes the indispensable position of inter- and intracellular mitochondrial communication in the aging process of organisms, which is crucial as the cellular signaling hubs. In addition, we also specifically focus on the status of mitochondria-targeted interventions to provide potential therapeutic targets for age-related diseases.

Mitochondrial Fitness Science Communication for Aging Adults: Prospective Formative Pilot Study

BACKGROUND

A key driver that leads to age-associated decline and chronic disease is mitochondrial dysfunction. Our previous work revealed strong community interest in the concept of mitochondrial fitness, which led to the development of a video-based science communication intervention to prompt behavior change in adults aged 50 years and older.

OBJECTIVE

This study aimed to conduct formative and summative evaluations of MitoFit, an instructional, biologically based communication intervention aimed at improving physical activity in older adults aged 50 years and older.

METHODS

In the phase-1 formative evaluation, community-dwelling older adults (N=101) rated the acceptability, appropriateness, and helpfulness of our MitoFit video series, titled "How to Slow Down Aging Through Mitochondrial Fitness." In the phase-2 summative evaluation, a subgroup of phase-1 participants (n=19) participated in a 1-month MitoFit intervention prototype to evaluate the intervention and data collection feasibility.

RESULTS

In phase 1, participants (mean age 67.8, SD 8.9 y; 75/100, 75% female) rated the MitoFit videos as acceptable (≥4 out of 5 on a Likert-scale survey; from 97/101, 96% to 100/101, 99%), appropriate (101/101, 100%), and helpful (from 95/101, 94% to 100/101, 99%) to support adaptation and continued work on our novel approach. Previous knowledge of mitochondria ranged from 52% (50/97; What are mitochondria?) to 80% (78/97; What are the primary functions of mitochondria?). In phase 2, participants (mean age 71.4, SD 7.9 y; 13/19, 72% female) scored better than the national average (50) on the Patient-Reported Outcomes Measurement Information System-19 for physical function (57), social activities (55.5), depression (41), fatigue (48.6), and sleep disturbance (49.6) but worse for anxiety (55.3) and pain interference (52.4). Additionally, 95% (18/19) of participants demonstrated MitoFit competencies within 2 attempts (obtaining pulse: 19/19, 100%; calculating maximum and zone 2 heart rate: 18/19, 95%; and demonstration of exercises: 19/19, 100%). At 1 month after instruction, 68% (13/19) had completed a self-initiated daily walking/exercise plan and submitted a daily activity log. A walking pulse was documented by 85% (11/13) of participants. The time needed to walk 1 mile ranged from 17.4 to 27.1 minutes. The number of miles walked in 1 month was documented by 62% (8/13) of participants and ranged from 10 miles to 31 miles. The number of days of strength training ranged from 2 to 31 days/month. Intervention feasibility scores ranged from 89% (17/19; seems easy to follow) to 95% (18/19; seems implementable, possible, and doable). Overall, 79% (15/19) stated an intention to continue the MitoFit intervention. Furthermore, 4 weeks after delivery of the prototype intervention, the percentage of participants doing aerobic activity for regular moderate activity increased from 35% (6/17) to 59% (10/17; P=.03).

CONCLUSIONS

MitoFit was enthusiastically embraced and is a cost-effective, scalable, and potentially efficacious intervention to advance with community-dwelling older adults.

Aging Lung: Molecular Drivers and Impact on Respiratory Diseases-A Narrative Clinical Review

The aging process significantly impacts lung physiology and is a major risk factor for chronic respiratory diseases, including chronic obstructive pulmonary disease (COPD), idiopathic pulmonary fibrosis (IPF), asthma, and non-IPF interstitial lung fibrosis. This narrative clinical review explores the molecular and biochemical hallmarks of aging, such as oxidative stress, telomere attrition, genomic instability, epigenetic modifications, proteostasis loss, and impaired macroautophagy, and their roles in lung senescence. Central to this process are senescent cells, which, through the senescence-associated secretory phenotype (SASP), contribute to chronic inflammation and tissue dysfunction. The review highlights parallels between lung aging and pathophysiological changes in respiratory diseases, emphasizing the role of cellular senescence in disease onset and progression. Despite promising research into modulating aging pathways with interventions like caloric restriction, mTOR inhibitors, and SIRT1 activators, clinical evidence for efficacy in reversing or preventing age-related lung diseases remains limited. Understanding the interplay between aging-related mechanisms and environmental factors, such as smoking and pollution, is critical for developing targeted therapies. This review underscores the need for future studies focusing on therapeutic strategies to mitigate aging's detrimental effects on lung health and improve outcomes for patients with chronic respiratory conditions.

Unveiling the Longevity Potential of Natural Phytochemicals: A Comprehensive Review of Active Ingredients in Dietary Plants and Herbs

Ancient humans used dietary plants and herbs to treat disease and to pursue eternal life. Today, phytochemicals in dietary plants and herbs have been shown to be the active ingredients, some of which have antiaging and longevity-promoting effects. Here, we summarize 210 antiaging phytochemicals in dietary plants and herbs, systematically classify them into 8 groups. We found that all groups of phytochemicals can be categorized into six areas that regulate organism longevity: ROS levels, nutrient sensing network, mitochondria, autophagy, gut microbiota, and lipid metabolism. We review the role of these processes in aging and the molecular mechanism of the health benefits through phytochemical-mediated regulation. Among these, how phytochemicals promote longevity through the gut microbiota and lipid metabolism is rarely highlighted in the field. Our understanding of the mechanisms of phytochemicals based on the above six aspects may provide a theoretical basis for the further development of antiaging drugs and new insights into the promotion of human longevity.

Mitochondrial destabilization in tendinopathy and potential therapeutic strategies

Tendinopathy is a prevalent aging-related disorder characterized by pain, swelling, and impaired function, often resulting from micro-scarring and degeneration caused by overuse or trauma. Current interventions for tendinopathy have limited efficacy, highlighting the need for innovative therapies. Mitochondria play an underappreciated and yet crucial role in tenocytes function, including energy production, redox homeostasis, autophagy, and calcium regulation. Abnormalities in mitochondrial function may lead to cellular senescence. Within this context, this review provides an overview of the physiological functions of mitochondria in tendons and presents current insights into mitochondrial dysfunction in tendinopathy. It also proposes potential therapeutic strategies that focus on targeting mitochondrial health in tenocytes. These strategies include: (1) utilizing reactive oxygen species (ROS) scavengers to mitigate the detrimental effects of aberrant mitochondria, (2) employing mitochondria-protecting agents to reduce the production of dysfunctional mitochondria, and (3) supplementing with exogenous normal mitochondria. In conclusion, mitochondria-targeted therapies hold great promise for restoring mitochondrial function and improving outcomes in patients with tendinopathy. The translational potential of this article: Tendinopathy is challenging to treat effectively due to its poorly understood pathogenesis. This review thoroughly analyzes the role of mitochondria in tenocytes and proposes potential strategies for the mitochondrial treatment of tendinopathy. These findings establish a theoretical basis for future research and the clinical translation of mitochondrial therapy for tendinopathy.

Synergy between nanoplastics and benzo[a]pyrene promotes senescence by aggravating ferroptosis and impairing mitochondria integrity in Caenorhabditis elegans

Micro-nano plastics have been reported as important carriers of polycyclic aromatic hydrocarbons (PAHs) for long-distance migration in the environment. However, the combined toxicity from long-term chronic exposure beyond the vehicle-release mechanism remains elusive. In this study, we investigated the synergistic action of Benzo[a]pyrene (BaP) and Polystyrene nanoparticles (PS) in Caenorhabditis elegans (C. elegans) as a combined exposure model with environmental concentrations. We found that the combined exposure to BaP and PS, as opposed to single exposures at low concentrations, significantly shortened the lifespan of C. elegans, leading to the occurrence of multiple senescence phenotypes. Multi-omics data indicated that the combined exposure to BaP and PS is associated with the disruption of glutathione homeostasis. Consequently, the accumulated reactive oxygen species (ROS) cannot be effectively cleared, which is highly correlated with mitochondrial dysfunction. Moreover, the increase in ROS promoted lipid peroxidation in C. elegans and downregulated Ferritin-1 (Ftn-1), resulting in ferroptosis and ultimately accelerating the aging process of C. elegans. Collectively, our study provides a new perspective to explain the long-term compound toxicity caused by BaP and PS at real-world exposure concentrations.

Particulate matter 2.5 accelerates aging: Exploring cellular senescence and age-related diseases

Exposure to Particulate matter 2.5 (PM2.5) accelerates aging, causing declines in tissue and organ function, and leading to diseases such as cardiovascular, neurodegenerative, and musculoskeletal disorders. PM2.5 is a major environmental pollutant and an exogenous pathogen in air pollution that is now recognized as an accelerator of human aging and a predisposing factor for several age-related diseases. In this paper, we seek to elucidate the mechanisms by which PM2.5 induces cellular senescence, such as genomic instability, telomere attrition, epigenetic alterations, loss of proteostasis, and mitochondrial dysfunction, and age-related diseases. Our goal is to increase awareness among researchers within the field of the toxicity of environmental pollutants and to advocate for personal and public health initiatives to curb their production and enhance population protection. Through these endeavors, we aim to promote longevity and health in older adults.

Tetramethylpyrazine nitrone delays the aging process of C. elegans by improving mitochondrial function through the AMPK/mTORC1 signaling pathway

Aging is characterized as the process of functional decline in an organism from adulthood, often marked by a progressive loss of cellular function and systemic deterioration of multiple tissues. Among the numerous molecular, cellular, and systemic hallmarks associated with aging, mitochondrial dysfunction is considered one of the pivotal factors that initiates the aging process. During aging, mitochondria undergo varying degrees of damage, resulting in impaired energy production and disruption of the homeostatic regulation of mitochondrial quality control systems, which in turn affects cellular energy metabolism and results in cellular dysfunction, accelerating the aging process. AMP-activated protein kinase (AMPK) and the mechanistic target of rapamycin complex 1 (mTORC1) are two central kinase complexes responsible for sensing intracellular nutrient levels, regulating metabolic homeostasis, modulating aging and play a crucial role in maintaining the homeostatic balance of mitochondria. Our previous studies found that the novel compound tetramethylpyrazine nitrone (TBN) can protect mitochondria via the AMPK/mTOR pathway in many animal models, extending healthy lifespan through the Nrf2 signaling pathway in nematodes. Building upon this foundation, we have posited a reasonable hypothesis, TBN can improve mitochondrial function to delay aging by regulating the AMPK/mTORC1 signaling pathway. This study focuses on the C. elegans, exploring the impact and underlying mechanisms of TBN on aging and mitochondrial function (especially the mitochondrial quality control system) during the aging process. The present studies demonstrated that TBN extends lifespan of wild-type nematodes and is associated with the AMPK/mTORC1 signaling pathway. TBN elevated ATP and NAD+ levels in aging nematodes while orchestrating mitochondrial biogenesis and mitophagy. Moreover, TBN was observed to significantly enhance normal activities during aging in C. elegans, such as mobility and pharyngeal pumping, concurrently impeding lipofuscin accumulation that were closely associated with AMPK and mTORC1. This study not only highlights the delayed effects of TBN on aging but also underscores its potential application in strategies aimed at improving mitochondrial function via the AMPK/mTOR pathway in C. elegans.

Enhancing healthy aging with small molecules: A mitochondrial perspective

The pursuit of enhanced health during aging has prompted the exploration of various strategies focused on reducing the decline associated with the aging process. A key area of this exploration is the management of mitochondrial dysfunction, a notable characteristic of aging. This review sheds light on the crucial role that small molecules play in augmenting healthy aging, particularly through influencing mitochondrial functions. Mitochondrial oxidative damage, a significant aspect of aging, can potentially be lessened through interventions such as coenzyme Q10, alpha-lipoic acid, and a variety of antioxidants. Additionally, this review discusses approaches for enhancing mitochondrial proteostasis, emphasizing the importance of mitochondrial unfolded protein response inducers like doxycycline, and agents that affect mitophagy, such as urolithin A, spermidine, trehalose, and taurine, which are vital for sustaining protein quality control. Of equal importance are methods for modulating mitochondrial energy production, which involve nicotinamide adenine dinucleotide boosters, adenosine 5'-monophosphate-activated protein kinase activators, and compounds like metformin and mitochondria-targeted tamoxifen that enhance metabolic function. Furthermore, the review delves into emerging strategies that encourage mitochondrial biogenesis. Together, these interventions present a promising avenue for addressing age-related mitochondrial degradation, thereby setting the stage for the development of innovative treatment approaches to meet this extensive challenge.

Nanodrug Delivery Systems for Myasthenia Gravis: Advances and Perspectives

Myasthenia gravis (MG) is a rare chronic autoimmune disease caused by the production of autoantibodies against the postsynaptic membrane receptors present at the neuromuscular junction. This condition is characterized by fatigue and muscle weakness, including diplopia, ptosis, and systemic impairment. Emerging evidence suggests that in addition to immune dysregulation, the pathogenesis of MG may involve mitochondrial damage and ferroptosis. Mitochondria are the primary site of energy production, and the reactive oxygen species (ROS) generated due to mitochondrial dysfunction can induce ferroptosis. Nanomedicines have been extensively employed to treat various disorders due to their modifiability and good biocompatibility, but their application in MG management has been rather limited. Nevertheless, nanodrug delivery systems that carry immunomodulatory agents, anti-oxidants, or ferroptosis inhibitors could be effective for the treatment of MG. Therefore, this review focuses on various nanoplatforms aimed at attenuating immune dysregulation, restoring mitochondrial function, and inhibiting ferroptosis that could potentially serve as promising agents for targeted MG therapy.

The impact of ageing mechanisms on musculoskeletal system diseases in the elderly

Ageing is an inevitable process that affects various tissues and organs of the human body, leading to a series of physiological and pathological changes. Mechanisms such as telomere depletion, stem cell depletion, macrophage dysfunction, and cellular senescence gradually manifest in the body, significantly increasing the incidence of diseases in elderly individuals. These mechanisms interact with each other, profoundly impacting the quality of life of older adults. As the ageing population continues to grow, the burden on the public health system is expected to intensify. Globally, the prevalence of musculoskeletal system diseases in elderly individuals is increasing, resulting in reduced limb mobility and prolonged suffering. This review aims to elucidate the mechanisms of ageing and their interplay while exploring their impact on diseases such as osteoarthritis, osteoporosis, and sarcopenia. By delving into the mechanisms of ageing, further research can be conducted to prevent and mitigate its effects, with the ultimate goal of alleviating the suffering of elderly patients in the future.

Association of Inflammatory Mediators with Mitochondrial DNA Variants in Geriatric COVID-19 Patients

COVID-19 remains a serious concern for elderly individuals with underlying comorbidities. SARS-CoV-2 can target and damage mitochondria, potentially leading to mutations in mitochondrial DNA (mtDNA). This study aimed to evaluate single nucleotide substitutions in mtDNA and analyze their correlation with inflammatory biomarkers in elderly COVID-19 patients. A total of 30 COVID-19 patients and 33 older adult controls without COVID-19 (aged over 65 years) were enrolled. mtDNA was extracted from buffy coat samples and sequenced using a chip-based resequencing system (MitoChip v2.0) which detects both homoplasmic and heteroplasmic mtDNA variants (40-60% heteroplasmy) and allows the assessment of low-level heteroplasmy (<10% heteroplasmy). Serum concentrations of IL-6, IFN-α, TNF-α and IL-10 were determined in patients by a high-sensitivity immunoassay. We found a higher burden of total heteroplasmic variants in COVID-19 patients compared to controls with a selective increment in ND1 and COIII genes. Low-level heteroplasmy was significantly elevated in COVID-19 patients, especially in genes of the respiratory complex I. Both heteroplasmic variant burden and low-level heteroplasmy were associated with increased levels of IL-6, TNF-α, and IFN-α. These findings suggest that SARS-CoV-2 may induce mtDNA mutations that are related to the degree of inflammation.

Defining Mitochondrial Cristae Morphology Changes Induced by Aging in Brown Adipose Tissue

Mitochondria are required for energy production and even give brown adipose tissue (BAT) its characteristic color due to their high iron content and abundance. The physiological function and bioenergetic capacity of mitochondria are connected to the structure, folding, and organization of its inner-membrane cristae. During the aging process, mitochondrial dysfunction is observed, and the regulatory balance of mitochondrial dynamics is often disrupted, leading to increased mitochondrial fragmentation in aging cells. Therefore, it is hypothesized that significant morphological changes in BAT mitochondria and cristae will be present with aging. A quantitative 3D electron microscopy approach is developed to map cristae network organization in mouse BAT to test this hypothesis. Using this methodology, the 3D morphology of mitochondrial cristae is investigated in adult (3-month) and aged (2-year) murine BAT tissue via serial block face-scanning electron microscopy (SBF-SEM) and 3D reconstruction software for manual segmentation, analysis, and quantification. Upon investigation, an increase is found in mitochondrial volume, surface area, and complexity and decreased sphericity in aged BAT, alongside significant decreases in cristae volume, area, perimeter, and score. Overall, these data define the nature of the mitochondrial structure in murine BAT across aging.

Mitochondria-targeted cerium vanadate nanozyme suppressed hypoxia-ischemia injury in neonatal mice via intranasal administration

Oxidative stress is a major obstacle for neurological functional recovery after hypoxia-ischemia (HI) brain damage. Nanozymes with robust anti-oxidative stress properties offer a therapeutic option for HI injury. However, insufficiency of nanozyme accumulation in the HI brain by noninvasive administration hinders their application. Herein, we reported a cerium vanadate (CeVO4) nanozyme to realize a noninvasive therapy for HI brain in neonatal mice by targeting brain neuron mitochondria. CeVO4 nanozyme with superoxide dismutase activity mainly co-located with neuronal mitochondria 1 h after administration. Pre- and post-HI administrations of CeVO4 nanozyme were able to attenuate acute brain injury, by inhibiting caspase-3 activation, microglia activation, and proinflammation cytokine production in the lesioned cortex 2 d after HI injury. Moreover, CeVO4 nanozyme administration led to short- and long-term functional recovery following HI insult without any potential toxicities in peripheral organs of mice even after prolonged delivery for 4 weeks. These beneficial effects of CeVO4 nanozyme were associated with suppressed oxidative stress and up-regulated nuclear factor erythroid-2-related factor 2 (Nrf2) expression. Finally, we found that Nrf2 inhibition with ML385 abolished the protective effects of CeVO4 nanozyme on HI injury. Collectively, this strategy may provide an applicative perspective for CeVO4 nanozyme therapy in HI brain damage via noninvasive delivery.

Epoxyeicosatrienoic acids alleviate alveolar epithelial cell senescence by inhibiting mitophagy through NOX4/Nrf2 pathway

Alveolar epithelial cell (AEC) senescence is considered to be a universal pathological feature of many chronic pulmonary diseases. Our previous study found that epoxyeicosatrienoic acids (EETs), produced from arachidonic acid (ARA) through the cytochrome P450 cyclooxygenase (CYP) pathway, have significant negative regulatory effects on cellular senescence in AECs. However, the exact mechanisms by which EETs alleviate the senescence of AECs still need to be further explored. In the present study, we observed that bleomycin (BLM) induced enhanced mitophagy accompanied by increased mitochondrial ROS (mito-ROS) content in the murine alveolar epithelial cell line MLE12. While EETs reduced BLM-induced mitophagy and mito-ROS content in MLE12 cells, and the mechanism was related to the regulation of NOX4/Nrf2-mediated redox imbalance. Furthermore, we found that inhibition of EETs degradation could significantly inhibit mitophagy and regulate NOX4/Nrf2 balance to exert anti-oxidant effects in D-galactose-induced premature aging mice. Collectively, these findings may provide new ideas for treating age-related pulmonary diseases by targeting EETs to improve mitochondrial dysfunction and reduce oxidative stress.

Cmpk2 regulates mitochondrial function in glucocorticoid-induced osteoblast senescence and affects glucocorticoid-inhibited osteoblast differentiation

Mitochondrial dysfunction plays a crucial role in the development of glucocorticoid-induced osteoporosis (GIO). Cytidine monophosphate kinase 2 (Cmpk2), an essential mitochondria-associated gene, promotes the production of free mitochondrial DNA, which leads to the formation of inflammasome-mediated inflammatory factors. However, the specific role of Cmpk2 in GIO remains unclear. In this study, we report that glucocorticoids induce cellular senescence within the bone, particularly in bone marrow mesenchymal stem cells and preosteoblasts. We discovered that glucocorticoids cause mitochondrial dysfunction in preosteoblasts, increasing cellular senescence. Moreover, we observed elevated expression of Cmpk2 in preosteoblasts following glucocorticoid exposure. Inhibiting Cmpk2 expression alleviates glucocorticoid-induced cellular senescence and promotes osteogenic differentiation by improving mitochondrial function. Our study uncovers new mechanisms underlying glucocorticoid-induced senescence in stem cells and preosteoblasts, highlighting the potential of inhibiting the mitochondrial gene Cmpk2 to reduce senescence and enhance osteogenic differentiation. This finding offers a potential therapeutic approach for the treatment of GIO.

Changes in the Mitochondria in the Aging Process-Can α-Tocopherol Affect Them?

Aerobic organisms use molecular oxygen in several reactions, including those in which the oxidation of substrate molecules is coupled to oxygen reduction to produce large amounts of metabolic energy. The utilization of oxygen is associated with the production of ROS, which can damage biological macromolecules but also act as signaling molecules, regulating numerous cellular processes. Mitochondria are the cellular sites where most of the metabolic energy is produced and perform numerous physiological functions by acting as regulatory hubs of cellular metabolism. They retain the remnants of their bacterial ancestors, including an independent genome that encodes part of their protein equipment; they have an accurate quality control system; and control of cellular functions also depends on communication with the nucleus. During aging, mitochondria can undergo dysfunctions, some of which are mediated by ROS. In this review, after a description of how aging affects the mitochondrial quality and quality control system and the involvement of mitochondria in inflammation, we report information on how vitamin E, the main fat-soluble antioxidant, can protect mitochondria from age-related changes. The information in this regard is scarce and limited to some tissues and some aspects of mitochondrial alterations in aging. Improving knowledge of the effects of vitamin E on aging is essential to defining an optimal strategy for healthy aging.

Defining Mitochondrial Cristae Morphology Changes Induced by Aging in Brown Adipose Tissue

Mitochondria are required for energy production and even give brown adipose tissue (BAT) its characteristic color due to their high iron content and abundance. The physiological function and bioenergetic capacity of mitochondria are connected to the structure, folding, and organization of its inner-membrane cristae. During the aging process, mitochondrial dysfunction is observed, and the regulatory balance of mitochondrial dynamics is often disrupted, leading to increased mitochondrial fragmentation in aging cells. Therefore, we hypothesized that significant morphological changes in BAT mitochondria and cristae would be present with aging. We developed a quantitative three-dimensional (3D) electron microscopy approach to map cristae network organization in mouse BAT to test this hypothesis. Using this methodology, we investigated the 3D morphology of mitochondrial cristae in adult (3-month) and aged (2-year) murine BAT tissue via serial block face-scanning electron microscopy (SBF-SEM) and 3D reconstruction software for manual segmentation, analysis, and quantification. Upon investigation, we found increases in mitochondrial volume, surface area, and complexity and decreased sphericity in aged BAT, alongside significant decreases in cristae volume, area, perimeter, and score. Overall, these data define the nature of the mitochondrial structure in murine BAT across aging.

Abstract Figure

Maintenance of mitochondrial homeostasis for Alzheimer's disease: Strategies and challenges

Alzheimer's disease (AD) is one of the most common neurodegenerative diseases, and its early onset is closely related to mitochondrial energy metabolism. The brain is only 2% of body weight, but consumes 20% of total energy needs. Mitochondria are responsible for providing energy in cells, and maintaining their homeostasis ensures an adequate supply of energy to the brain. Mitochondrial homeostasis is constituted by mitochondrial quantity and quality control, which is dynamically regulated by mitochondrial energy metabolism, mitochondrial dynamics and mitochondrial quality control. Impaired energy metabolism of brain cells occurs early in AD, and maintaining mitochondrial homeostasis is a promising therapeutic target in the future. We summarized the mechanism of mitochondrial homeostasis in AD, its influence on the pathogenesis of early AD, strategies for maintaining mitochondrial homeostasis, and mitochondrial targeting strategies. This review concludes with the authors' opinions on future research and development for mitochondrial homeostasis of early AD.

Genomics of aging: Reactive oxidation and inefficient mitochondria

ABSTRACT

Many things are associated with decreased health and lifespan, including cancer, diabetes, atherosclerosis, high blood pressure, and chronic inflammatory conditions. Clinicians may not be familiar with the role that mitochondrial mutations and associated mitochondrial dysfunction play in a shortened lifespan. This article, the fifth in the JAANP Genomics of Aging series, describes the role that mitochondrial dysfunction plays in the development of age-related diseases such as Alzheimer disease, Parkinson disease, cancer, heart disease, and stroke.

Age-Dependent Alterations in Platelet Mitochondrial Respiration

Mitochondrial dysfunction is an important cellular hallmark of aging and neurodegeneration. Platelets are a useful model to study the systemic manifestations of mitochondrial dysfunction. To evaluate the age dependence of mitochondrial parameters, citrate synthase activity, respiratory chain complex activity, and oxygen consumption kinetics were assessed. The effect of cognitive impairment was examined by comparing the age dependence of mitochondrial parameters in healthy individuals and those with neuropsychiatric disease. The study found a significant negative slope of age-dependence for both the activity of individual mitochondrial enzymes (citrate synthase and complex II) and parameters of mitochondrial respiration in intact platelets (routine respiration, maximum capacity of electron transport system, and respiratory rate after complex I inhibition). However, there was no significant difference in the age-related changes of mitochondrial parameters between individuals with and without cognitive impairment. These findings highlight the potential of measuring mitochondrial respiration in intact platelets as a means to assess age-related mitochondrial dysfunction. The results indicate that drugs and interventions targeting mitochondrial respiration may have the potential to slow down or eliminate certain aging and neurodegenerative processes. Mitochondrial respiration in platelets holds promise as a biomarker of aging, irrespective of the degree of cognitive impairment.

Chronic D-Galactose Administration Induces Natural Aging Characteristics, in Rat's Brain and Heart

We aimed to investigate the effect of chronic D-galactose exposure on the mimicking of natural aging processes based upon the hallmarks of aging. Seven-week-old male Wistar rats (n = 12) were randomly assigned to receive either normal saline solution as a vehicle (n = 6) or 150mg/kg/day of D-galactose subcutaneously for 28 weeks. Seventeen-month-old rats (n = 6) were also included as the chronologically aged controls. At the end of week 28 of the experiment (when the rats reach 35 weeks old and 24 months old), all rats were sacrificed for brain and heart collection. Our results showed that chronic D-galactose exposure mimicked natural aging characteristics of the brain and the heart in terms of deregulated nutrient sensing, mitochondrial dysfunction, cellular senescence, stem cell exhaustion, altered intercellular communication, and functional impairment. All of which highlight the potential of D-galactose as a substance for inducing brain and cardiac aging in animal experiments. DATA AVAILABILITY: The data that support the findings of this study are available from the corresponding author upon reasonable request.

GPR19 Coordinates Multiple Molecular Aspects of Stress Responses Associated with the Aging Process

G protein-coupled receptors (GPCRs) play a significant role in controlling biological paradigms such as aging and aging-related disease. We have previously identified receptor signaling systems that are specifically associated with controlling molecular pathologies associated with the aging process. Here, we have identified a pseudo-orphan GPCR, G protein-coupled receptor 19 (GPR19), that is sensitive to many molecular aspects of the aging process. Through an in-depth molecular investigation process that involved proteomic, molecular biological, and advanced informatic experimentation, this study found that the functionality of GPR19 is specifically linked to sensory, protective, and remedial signaling systems associated with aging-related pathology. This study suggests that the activity of this receptor may play a role in mitigating the effects of aging-related pathology by promoting protective and remedial signaling systems. GPR19 expression variation demonstrates variability in the molecular activity in this larger process. At low expression levels in HEK293 cells, GPR19 expression regulates signaling paradigms linked with stress responses and metabolic responses to these. At higher expression levels, GPR19 expression co-regulates systems involved in sensing and repairing DNA damage, while at the highest levels of GPR19 expression, a functional link to processes of cellular senescence is seen. In this manner, GPR19 may function as a coordinator of aging-associated metabolic dysfunction, stress response, DNA integrity management, and eventual senescence.

Mitochondrial ROS production, oxidative stress and aging within and between species: Evidences and recent advances on this aging effector

Mitochondria play a wide diversity of roles in cell physiology and have a key functional implication in cell bioenergetics and biology of free radicals. As the main cellular source of oxygen radicals, mitochondria have been postulated as the mediators of the cellular decline associated with the biological aging. Recent evidences have shown that mitochondrial free radical production is a highly regulated mechanism contributing to the biological determination of longevity which is species-specific. This mitochondrial free radical generation rate induces a diversity of adaptive responses and derived molecular damage to cell components, highlighting mitochondrial DNA damage, with biological consequences that influence the rate of aging of a given animal species. In this review, we explore the idea that mitochondria play a fundamental role in the determination of animal longevity. Once the basic mechanisms are discerned, molecular approaches to counter aging may be designed and developed to prevent or reverse functional decline, and to modify longevity.

Mapping mitonuclear epistasis using a novel recombinant yeast population

Genetic variation in mitochondrial and nuclear genomes can perturb mitonuclear interactions and lead to phenotypic differences between individuals and populations. Despite their importance to most complex traits, it has been difficult to identify the interacting mitonuclear loci. Here, we present a novel advanced intercrossed population of Saccharomyces cerevisiae yeasts, called the Mitonuclear Recombinant Collection (MNRC), designed explicitly for detecting mitonuclear loci contributing to complex traits. For validation, we focused on mapping genes that contribute to the spontaneous loss of mitochondrial DNA (mtDNA) that leads to the petite phenotype in yeast. We found that rates of petite formation in natural populations are variable and influenced by genetic variation in nuclear DNA, mtDNA and mitonuclear interactions. We mapped nuclear and mitonuclear alleles contributing to mtDNA stability using the MNRC by integrating a term for mitonuclear epistasis into a genome-wide association model. We found that the associated mitonuclear loci play roles in mitotic growth most likely responding to retrograde signals from mitochondria, while the associated nuclear loci with main effects are involved in genome replication. We observed a positive correlation between growth rates and petite frequencies, suggesting a fitness tradeoff between mitotic growth and mtDNA stability. We also found that mtDNA stability was correlated with a mobile mitochondrial GC-cluster that is present in certain populations of yeast and that selection for nuclear alleles that stabilize mtDNA may be rapidly occurring. The MNRC provides a powerful tool for identifying mitonuclear interacting loci that will help us to better understand genotype-phenotype relationships and coevolutionary trajectories.

Yeast Chromatin Mutants Reveal Altered mtDNA Copy Number and Impaired Mitochondrial Membrane Potential

Mitochondria are multifunctional, dynamic organelles important for stress response, cell longevity, ageing and death. Although the mitochondrion has its genome, nuclear-encoded proteins are essential in regulating mitochondria biogenesis, morphology, dynamics and function. Moreover, chromatin structure and epigenetic mechanisms govern the accessibility to DNA and control gene transcription, indirectly influencing nucleo-mitochondrial communications. Thus, they exert crucial functions in maintaining proper chromatin structure, cell morphology, gene expression, stress resistance and ageing. Here, we present our studies on the mtDNA copy number in Saccharomyces cerevisiae chromatin mutants and investigate the mitochondrial membrane potential throughout their lifespan. The mutants are arp4 (with a point mutation in the ARP4 gene, coding for actin-related protein 4-Arp4p), hho1Δ (lacking the HHO1 gene, coding for the linker histone H1), and the double mutant arp4 hho1Δ cells with the two mutations. Our findings showed that the three chromatin mutants acquired strain-specific changes in the mtDNA copy number. Furthermore, we detected the disrupted mitochondrial membrane potential in their chronological lifespan. In addition, the expression of nuclear genes responsible for regulating mitochondria biogenesis and turnover was changed. The most pronounced were the alterations found in the double mutant arp4 hho1Δ strain, which appeared as the only petite colony-forming mutant, unable to grow on respiratory substrates and with partial depletion of the mitochondrial genome. The results suggest that in the studied chromatin mutants, hho1Δ, arp4 and arp4 hho1Δ, the nucleus-mitochondria communication was disrupted, leading to impaired mitochondrial function and premature ageing phenotype in these mutants, especially in the double mutant.

Aging and aging-related diseases: from molecular mechanisms to interventions and treatments

Aging is a gradual and irreversible pathophysiological process. It presents with declines in tissue and cell functions and significant increases in the risks of various aging-related diseases, including neurodegenerative diseases, cardiovascular diseases, metabolic diseases, musculoskeletal diseases, and immune system diseases. Although the development of modern medicine has promoted human health and greatly extended life expectancy, with the aging of society, a variety of chronic diseases have gradually become the most important causes of disability and death in elderly individuals. Current research on aging focuses on elucidating how various endogenous and exogenous stresses (such as genomic instability, telomere dysfunction, epigenetic alterations, loss of proteostasis, compromise of autophagy, mitochondrial dysfunction, cellular senescence, stem cell exhaustion, altered intercellular communication, deregulated nutrient sensing) participate in the regulation of aging. Furthermore, thorough research on the pathogenesis of aging to identify interventions that promote health and longevity (such as caloric restriction, microbiota transplantation, and nutritional intervention) and clinical treatment methods for aging-related diseases (depletion of senescent cells, stem cell therapy, antioxidative and anti-inflammatory treatments, and hormone replacement therapy) could decrease the incidence and development of aging-related diseases and in turn promote healthy aging and longevity.

Role of angiotensin II in aging

Aging is an inevitable progressive decline in physiological organ function that increases the chance of disease and death. The renin-angiotensin system (RAS) is involved in the regulation of vasoconstriction, fluid homeostasis, cell growth, fibrosis, inflammation, and oxidative stress. In recent years, unprecedented advancement has been made in the RAS study, particularly with the observation that angiotensin II (Ang II), the central product of the RAS, plays a significant role in aging and chronic disease burden with aging. Binding to its receptors (Ang II type 1 receptor - AT1R in particular), Ang II acts as a mediator in the aging process by increasing free radical production and, consequently, mitochondrial dysfunction and telomere attrition. In this review, we examine the physiological function of the RAS and reactive oxygen species (ROS) sources in detail, highlighting how Ang II amplifies or drives mitochondrial dysfunction and telomere attrition underlying each hallmark of aging and contributes to the development of aging and age-linked diseases. Accordingly, the Ang II/AT1R pathway opens a new preventive and therapeutic direction for delaying aging and reducing the incidence of age-related diseases in the future.

Developing and pilot testing a frailty-focused education and communication training workshop

Objective

To describe development and pilot testing of a multi-modal frailty-focused education and communication training workshop for health care clinicians.

Methods

Pilot testing was conducted via two workshops (#1:face-to-face [2019], #2:virtual [2020]). Participants: convenience sample of clinicians and students who volunteered. Workshop #1 included registered nurses working in an acute care and one medical student (N=14); #2: nursing students enrolled in an APRN program. Design: Pre/post observational study. Data analysis: descriptive statistics, paired t-tests and Wilcoxon rank test.

Results

Statistically significant increases in frailty knowledge (#1: p = 0.02, d = 0.44; #2: p = 0.006, d = 0.55) and self-reported competency with older adult interactions (#1: p < 0.001, d = 0.62; #2: p = 0.001, d = 0.63) were reported for both workshops. Post course evaluations of the workshop were positive, with scores ranging from 3.5-3.9 (range: 0-4) for increased understanding of the concept of frailty, communication to support health-related behavior, and best practice empathic communication skills.

Conclusion

The FCOM workshop was successful. Participants gained knowledge and skills for use in working with older adults across the aging continuum from non-frail to frail.

Innovation

Our FCOM training workshop expands prior communication training on shared decision-making with frail individuals to a broader population of all older adults.

Transcription Factor Nrf2 and Mitochondria - Friends or Foes in the Regulation of Aging Rate

At the first sight, the transcription factor Nrf2 as a master regulator of cellular antioxidant systems, and mitochondria as the main source of reactive oxygen species (ROS), should play the opposite roles in determining the pace of aging. However, since the causes of aging cannot be confined to the oxidative stress, the role of Nrf2 role cannot be limited to the regulation of antioxidant systems, and moreover, the role of mitochondria is not confined to the ROS production. In this review, we discussed only one aspect of this problem, namely, the molecular mechanisms of interaction between Nrf2 and mitochondria that influence the rate of aging and the lifespan. Experimental data accumulated so far show that the Nrf2 activity positively affects both the mitochondrial dynamics and mitochondrial quality control. Nrf2 influences the mitochondrial function through various mechanisms, e.g., regulation of nuclear genome-encoded mitochondrial proteins and changes in the balance of ROS or other metabolites that affect the functioning of mitochondria. In turn, multiple regulatory proteins functionally associated with the mitochondria affect the Nrf2 activity and even form mutual regulatory loops with Nrf2. We believe that these loops enable the fine-tuning of the cellular redox balance and, possibly, of the cellular metabolism as a whole. It has been commonly accepted for a long time that all mitochondrial regulatory signals are mediated by the nuclear genome-encoded proteins, whereas the mitochondrial genome encodes only a few respiratory chain proteins and two ribosomal RNAs. Relatively recently, mtDNA-encoded signal peptides have been discovered. In this review, we discuss the data on their interactions with the nuclear regulatory systems, first of all, Nrf2, and their possible involvement in the regulation of the aging rate. The interactions between regulatory cascades that link the programs ensuring the maintenance of cellular homeostasis and cellular responses to the oxidative stress are a significant part of both aging and anti-aging programs. Therefore, understanding these interactions will be of great help in searching for the molecular targets to counteract aging-associated diseases and aging itself.

Health and wellness for disadvantaged older adults: The AFRESH pilot study

Introduction

Older adults are unaware of the biological mechanisms that contribute to the development of disabilities, chronic conditions, and frailty, yet, when made aware, desire to employ lifestyle changes to mitigate these conditions. We developed the AFRESH health and wellness program and report on pilot testing undertaken in a local older adults apartment community.

Materials and methods

After program development, pilot testing was conducted. Participants: Older adults (N = 20; age 62+) residing in an apartment community. Procedures: Collection of baseline objective and self-report measures with a focus on physical activity; administration of the 10-week AFRESH program via weekly sessions; collection of follow-up data 12 and 36 weeks after baseline data collection. Data analysis: Descriptive statistics, growth curve analyses.

Results

Significant increases were observed for grip strength (lbs) (T1:56.2; T2:65.0 [d = 0.77]; T3:69.4 [d = 0.62], p = .001), the 6-min walk test (meters) (T1:327m: T2:388.7 m [d = 0.99]; T3:363.3 m [d = 0.60], p = .001), the Rapid Assessment of Physical Activity (RAPA) strength and flexibility score, and the Pittsburg Sleep Quality Index (PSQI) global score. These effects showed some attenuation by the final time point.

Conclusion

By combining novel educational content (bioenergetics), facilitation of physical activity, and habit formation, AFRESH is a multicomponent intervention that shows promise for future research.

Impact of aging on mitochondrial respiration in various organs

Mitochondria are considered central regulator of the aging process; however, majority of studies dealing with the impact of age on mitochondrial oxygen consumption focused on skeletal muscle concluding (although not uniformly) a general declining trend with advancing age. In addition, gender related differences in mitochondrial respiration have not been satisfactorily described yet. The aim of the present study was to evaluate mitochondrial oxygen consumption in various organs of aging male and female Fischer 344 rats at the ages of 6, 12 and 24 months. Mitochondrial respiration of homogenized (skeletal muscle, left and right heart ventricle, hippocampus, cerebellum, kidney cortex), gently mechanically permeabilized (liver) tissue or intact cells (platelets) was determined using high-resolution respirometry (oxygraphs O2k, Oroboros, Austria). The pattern of age-related changes differed in each tissue: in the skeletal muscle and kidney cortex of both sexes and in female heart, parameters of mitochondrial respiration significantly declined with age. Resting respiration of intact platelets displayed an increasing trend and it did not correlate with skeletal muscle respiratory states. In the heart of male rats and brain tissues of both sexes, respiratory states remained relatively stable over analyzed age categories with few exceptions of lower mitochondrial oxygen consumption at the age of 24 months. In the liver, OXPHOS capacity was higher in females than in males with either no difference between the ages of 6 and 24 months or even significant increase at the age of 24 months in the male rats. In conclusion, the results of our study indicate that the concept of general pattern of age-dependent decline in mitochondrial oxygen consumption across different organs and tissues could be misleading. Also, the statement of higher mitochondrial respiration in females seems to be conflicting, since the gender-related differences may vary with the tissue studied, combination of substrates used and might be better detectable at younger ages than in old animals.

Intersection of the Orphan G Protein-Coupled Receptor, GPR19, with the Aging Process

G protein-coupled receptors (GPCRs) represent one of the most functionally diverse classes of transmembrane proteins. GPCRs and their associated signaling systems have been linked to nearly every physiological process. They also constitute nearly 40% of the current pharmacopeia as direct targets of remedial therapies. Hence, their place as a functional nexus in the interface between physiological and pathophysiological processes suggests that GPCRs may play a central role in the generation of nearly all types of human disease. Perhaps one mechanism through which GPCRs can mediate this pivotal function is through the control of the molecular aging process. It is now appreciated that, indeed, many human disorders/diseases are induced by GPCR signaling processes linked to pathological aging. Here we discuss one such novel member of the GPCR family, GPR19, that may represent an important new target for novel remedial strategies for the aging process. The molecular signaling pathways (metabolic control, circadian rhythm regulation and stress responsiveness) associated with this recently characterized receptor suggest an important role in aging-related disease etiology.

Actin-Related Protein 4 and Linker Histone Sustain Yeast Replicative Ageing

Ageing is accompanied by dramatic changes in chromatin structure organization and genome function. Two essential components of chromatin, the linker histone Hho1p and actin-related protein 4 (Arp4p), have been shown to physically interact in Saccharomyces cerevisiae cells, thus maintaining chromatin dynamics and function, as well as genome stability and cellular morphology. Disrupting this interaction has been proven to influence the stability of the yeast genome and the way cells respond to stress during chronological ageing. It has also been proven that the abrogated interaction between these two chromatin proteins elicited premature ageing phenotypes. Alterations in chromatin compaction have also been associated with replicative ageing, though the main players are not well recognized. Based on this knowledge, here, we examine how the interaction between Hho1p and Arp4p impacts the ageing of mitotically active yeast cells. For this purpose, two sets of strains were used—haploids (WT(n), arp4, hho1Δ and arp4 hho1Δ) and their heterozygous diploid counterparts (WT(2n), ARP4/arp4, HHO1/hho1Δ and ARP4 HHO1/arp4 hho1Δ)—for the performance of extensive morphological and physiological analyses during replicative ageing. These analyses included a comparative examination of the yeast cells’ chromatin structure, proliferative and reproductive potential, and resilience to stress, as well as polysome profiles and chemical composition. The results demonstrated that the haploid chromatin mutants arp4 and arp4 hho1Δ demonstrated a significant reduction in replicative and total lifespan. These findings lead to the conclusion that the importance of a healthy interaction between Arp4p and Hho1p in replicative ageing is significant. This is proof of the concomitant importance of Hho1p and Arp4p in chronological and replicative ageing.

Superoxide Dismutases in Eukaryotic Microorganisms: Four Case Studies

Various components in the cell are responsible for maintaining physiological levels of reactive oxygen species (ROS). Several different enzymes exist that can convert or degrade ROS; among them are the superoxide dismutases (SODs). If left unchecked, ROS can cause damage that leads to pathology, can contribute to aging, and may, ultimately, cause death. SODs are responsible for converting superoxide anions to hydrogen peroxide by dismutation. Here we review the role of different SODs on the development and pathogenicity of various eukaryotic microorganisms relevant to human health. These include the fungal aging model, Podospora anserina; various members of the genus Aspergillus that can potentially cause aspergillosis; the agents of diseases such as Chagas and sleeping disease, Trypanosoma cruzi and Trypanosoma brucei, respectively; and, finally, pathogenic amoebae, such as Acanthamoeba spp. In these organisms, SODs fulfill essential and often regulatory functions that come into play during processes such as the development, host infection, propagation, and control of gene expression. We explore the contribution of SODs and their related factors in these microorganisms, which have an established role in health and disease.

Standpoints in mitochondrial dysfunction: Underlying mechanisms in search of therapeutic strategies

Mitochondrial dysfunction has been defined as a reduced efficiency of mitochondria to produce ATP given by a loss of mitochondrial membrane potential, alterations in the electron transport chain (ETC) function, with increase in reactive oxygen species (ROS) generation and decrease in oxygen consumption. During the last decades, mitochondrial dysfunction has been the focus of many researchers as a convergent point for the pathophysiology of several diseases. Numerous investigations have demonstrated that mitochondrial dysfunction is detrimental to cells, tissues and organisms, nevertheless, dysfunctional mitochondria can signal in a particular way in response to stress, a characteristic that may be useful to search for new therapeutic strategies with a common feature. The aim of this review addresses mitochondrial dysfunction and stress signaling as a promising target for future drug development.

D-Galactose-Induced Accelerated Aging Model on Auditory Cortical Neurons by Regulating Oxidative Stress and Apoptosis in Vitro

OBJECTIVES

Age-related hearing loss (ARHL) is much more prevalent with age, affecting not only peripheral but central auditory system. We have previously established an aging model of peripheral auditory system in vitro using cultured cochlear basilar membrane. However, there is no ideal accelerated aging model on central auditory system in vitro. To establish the aging model, auditory cortical neurons (ACNs) were primary cultured and treated with either vehicle or different doses of D-galactose (D-gal). We studied the effect of D-gal on ACNs by evaluating the hallmarks of aging, including cell proliferation, oxidative stress, mitochondrial function, and neuronal apoptosis. Compared with the control group, cell viability was significantly inhibited in the D-gal-treated group in a dose-dependent manner. The production of reactive oxygen species was strongly increased in the D-gal-treated group. Meanwhile, the level of 8-hydroxy-2'-deoxyguanosine, which is a biomarker of DNA oxidative damage, was even higher in the D-gal-treated group than that in the control group. Conversely, the levels of ATP and mitochondrial membrane potential were notably decreased in the D-gal-treated group contrast to that in the control group. Furthermore, the number of neuronal apoptosis in the D-gal-treated group, compared with that in the control group, was dramatically increased in a dose-dependent approach. Together, our results demonstrate that ACNs treated with D-gal in vitro display senescence characteristics by regulating oxidative stress and apoptosis, indicating accelerated aging model on ACNs are successfully established. And the model provides a promising approach for exploring underlying mechanisms of the ARHL.

Strategies to protect against age-related mitochondrial decay: Do natural products and their derivatives help?

Mitochondria serve vital roles critical for overall cellular function outside of energy transduction. Thus, mitochondrial decay is postulated to be a key factor in aging and in age-related diseases. Mitochondria may be targets of their own decay through oxidative damage. However, treating animals with antioxidants has been met with only limited success in rejuvenating mitochondrial function or in increasing lifespan. A host of nutritional strategies outside of using traditional antioxidants have been devised to promote mitochondrial function. Dietary compounds are under study that induce gene expression, enhance mitochondrial biogenesis, mitophagy, or replenish key metabolites that decline with age. Moreover, redox-active compounds may now be targeted to mitochondria which improve their effectiveness. Herein we review the evidence that representative dietary effectors modulate mitochondrial function by stimulating their renewal or reversing the age-related loss of key metabolites. While in vitro evidence continues to accumulate that many of these compounds benefit mitochondrial function and/or prevent their decay, the results using animal models and, in some instances human clinical trials, are more mixed and sometimes even contraindicated. Thus, further research on optimal dosage and age of intervention are warranted before recommending potential mitochondrial rejuvenating compounds for human use.

FOXO3 regulates a common genomic program in aging and glioblastoma stem cells

Background

Glioblastoma (GBM) is an aggressive, age-associated malignant glioma that contains populations of cancer stem cells. These glioma stem cells (GSCs) evade therapeutic interventions and repopulate tumors due to their existence in a slowly cycling quiescent state. Although aging is well known to increase cancer initiation, the extent to which the mechanisms supporting GSC tumorigenicity are related to physiological aging remains unknown.

Aims

Here, we investigate the transcriptional mechanisms by which Forkhead Box O3 (FOXO3), a transcriptional regulator that promotes healthy aging, affects GSC function and the extent to which FOXO3 transcriptional networks are dysregulated in aging and GBM.

Methods and results

We performed transcriptome analysis of clinical GBM tumors and observed that high FOXO3 activity is associated with gene expression signatures of stem cell quiescence, reduced oxidative metabolism, and improved patient outcomes. Consistent with these findings, we show that elevated FOXO3 activity significantly reduces the proliferation of GBM-derived GSCs. Using RNA-seq, we find that functional ablation of FOXO3 in GSCs rewires the transcriptional circuitry associated with metabolism, epigenetic stability, quiescence, and differentiation. Since FOXO3 has been implicated in healthy aging, we then investigated the extent to which it regulates common transcriptional programs in aging neural stem cells (NSCs) and GSCs. We uncover a shared transcriptional program and, most strikingly, find that FOXO3-regulated pathways are associated with altered mitochondrial functions in both aging and GBM.

Conclusions

This work identifies a FOXO-associated transcriptional program that correlates between GSCs and aging NSCs and is enriched for metabolic and stemness pathways connected with GBM and aging.

Pathogenic mitochondrial dysfunction and metabolic abnormalities

Herein we trace links between biochemical pathways, pathogenesis, and metabolic diseases to set the stage for new therapeutic advances. Cellular and acellular microorganisms including bacteria and viruses are primary pathogenic drivers that cause disease. Missing from this statement are subcellular compartments, importantly mitochondria, which can be pathogenic by themselves, also serving as key metabolic disease intermediaries. The breakdown of food molecules provides chemical energy to power cellular processes, with mitochondria as powerhouses and ATP as the principal energy carrying molecule. Most animal cell ATP is produced by mitochondrial synthase; its central role in metabolism has been known for >80 years. Metabolic disorders involving many organ systems are prevalent in all age groups. Progressive pathogenic mitochondrial dysfunction is a hallmark of genetic mitochondrial diseases, the most common phenotypic expression of inherited metabolic disorders. Confluent genetic, metabolic, and mitochondrial axes surface in diabetes, heart failure, neurodegenerative disease, and even in the ongoing coronavirus pandemic.

Multifunctional AIE iridium (III) photosensitizer nanoparticles for two-photon-activated imaging and mitochondria targeting photodynamic therapy

Developing novel photosensitizers for deep tissue imaging and efficient photodynamic therapy (PDT) remains a challenge because of the poor water solubility, low reactive oxygen species (ROS) generation efficiency, serve dark cytotoxicity, and weak absorption in the NIR region of conventional photosensitizers. Herein, cyclometalated iridium (III) complexes (Ir) with aggregation-induced emission (AIE) feature, high photoinduced ROS generation efficiency, two-photon excitation, and mitochondria-targeting capability were designed and further encapsulated into biocompatible nanoparticles (NPs). The Ir-NPs can be used to disturb redox homeostasis in vitro, result in mitochondrial dysfunction and cell apoptosis. Importantly, in vivo experiments demonstrated that the Ir-NPs presented obviously tumor-targeting ability, excellent antitumor effect, and low systematic dark-toxicity. Moreover, the Ir-NPs could serve as a two-photon imaging agent for deep tissue bioimaging with a penetration depth of up to 300 μm. This work presents a promising strategy for designing a clinical application of multifunctional Ir-NPs toward bioimaging and PDT.

Association between serum advanced oxidation protein products and mortality risk in maintenance hemodialysis patients

BACKGROUND

The association between serum advanced oxidation protein products (AOPP) and mortality risk remains equivocal. We aimed to assess the correlation of serum AOPP levels with the risk of all-cause mortality in hemodialysis (HD) patients.

METHODS

A total of 1394 maintenance HD patients with complete data on AOPP and related parameters were included from China Collaborative Study on Dialysis (CCSD), a multi-center, prospective cohort study. The primary outcome was all-cause mortality, the secondary outcome was cardiovascular disease (CVD) mortality.

RESULTS

During a median follow-up duration of 5.2 years (IQR, 2.1-5.4), all-cause mortality occurred in 492 (31.4%) participants. Overall, there was a reversed L-shaped association between serum AOPP and all-cause mortality in HD patients (P for nonlinearity = 0.04), with an inflection point at 87 µmol/L. Accordingly, there was no significant association between serum AOPP and all-cause mortality (per SD increment; HR, 0.94; 95%CI, 0.84, 1.05) in participants with AOPP < 87 µmol/L. However, there was a positive relationship of serum AOPP and all-cause mortality (per SD increment; HR, 1.24; 95%CI, 1.08, 1.42) in those with AOPP ≥ 87 µmol/L. Moreover, a similar trend was found for CVD mortality.

CONCLUSIONS

Elevated serum AOPP levels were associated with higher risk of all-cause mortality in Chinese maintenance HD patients.

Mitochondrial nanomedicine: Subcellular organelle-specific delivery of molecular medicines

As mitochondria network together to act as the master sensors and effectors of apoptosis, ATP production, reactive oxygen species management, mitophagy/autophagy, and homeostasis; this organelle is an ideal target for pharmaceutical manipulation. Mitochondrial dysfunction contributes to many diseases, for example, β-amyloid has been shown to interfere with mitochondrial protein import and induce apoptosis in Alzheimer's Disease while some forms of Parkinson's Disease are associated with dysfunctional mitochondrial PINK1 and Parkin proteins. Mitochondrial medicine has applications in the treatment of an array of pathologies from cancer to cardiovascular disease. A challenge of mitochondrial medicine is directing therapies to a subcellular target. Nanotechnology based approaches combined with mitochondrial targeting strategies can greatly improve the clinical translation and effectiveness of mitochondrial medicine. This review discusses mitochondrial drug delivery approaches and applications of mitochondrial nanomedicines. Nanomedicine approaches have the potential to drive the success of mitochondrial therapies into the clinic.