The mitochondrial-lysosomal axis theory of aging: accumulation of damaged mitochondria as a result of imperfect autophagocytosis

Mitochondrial homeostasis in odontoblast: Physiology, pathogenesis and targeting strategies

Caries and pulpitis remain a major global disease burden and affect the quality of life of patients. Odontoblasts are key players in the progression of caries and pulpitis, not only secreting and mineralizing to form dentin, but also acting as a wall of defense to initiate immune defenses. Mitochondrion is an information processor for numerous cellular activities, and dysregulation of mitochondrion homeostasis not only affects cellular metabolism but also triggers a wide range of diseases. Elucidating mitochondrial homeostasis in odontoblasts can help deepen scholars' understanding of odontoblast-associated diseases. Articles on mitochondrial homeostasis in odontoblasts were evaluated for information pertinent to include in this narrative review. This narrative review focused on understanding the complex interplay between mitochondrial homeostasis in odontoblasts under physiological and pathological conditions. Furthermore, mitochondria-centered therapeutic strategies (including mitochondrial base editing, targeting platforms, and mitochondrial transplantation) were emphasized by resolving key genes that regulate mitochondrial function. Mitochondria are involved in odontoblast differentiation and function, and act as mitochondrial danger-associated molecular patterns (mtDAMPs) to mediate odontoblast pathological progression. Novel mitochondria-centered therapeutic strategies are particularly attractive as emerging therapeutic approaches for the maintenance of mitochondrial homeostasis. It is expected to probe key events of odontoblast differentiation and advance the clinical resolution of dentin formation and mineralization disorders and odontoblast-related diseases.

Aging-dependent mitochondrial bioenergetic impairment in the skeletal muscle of NNT-deficient mice

Overall health relies on features of skeletal muscle that generally decline with age, partly due to mechanisms associated with mitochondrial redox imbalance and bioenergetic dysfunction. Previously, aged mice genetically devoid of the mitochondrial NAD(P)+ transhydrogenase (NNT, encoded by the nicotinamide nucleotide transhydrogenase gene), an enzyme involved in mitochondrial NADPH supply, were shown to exhibit deficits in locomotor behavior. Here, by using young, middle-aged, and older NNT-deficient (Nnt-/-) mice and age-matched controls (Nnt+/+), we aimed to investigate how muscle bioenergetic function and motor performance are affected by NNT expression and aging. Mice were subjected to the wire-hang test to assess locomotor performance, while mitochondrial bioenergetics was evaluated in fiber bundles from the soleus, vastus lateralis and plantaris muscles. An age-related decrease in the average wire-hang score was observed in middle-aged and older Nnt-/- mice compared to age-matched controls. Although respiratory rates in the soleus, vastus lateralis and plantaris muscles did not significantly differ between the genotypes in young mice, the rates of oxygen consumption did decrease in the soleus and vastus lateralis muscles of middle-aged and older Nnt-/- mice. Notably, the soleus, which exhibited the highest NNT expression level, was the muscle most affected by aging, and NNT loss. Additionally, histology of the soleus fibers revealed increased numbers of centralized nuclei in older Nnt-/- mice, indicating abnormal morphology. In summary, our findings suggest that NNT expression deficiency causes locomotor impairments and muscle dysfunction during aging in mice.

Mechanisms of oxidative stress in interstitial cystitis/bladder pain syndrome

Interstitial cystitis/bladder pain syndrome (IC/BPS) is characterized by bladder and/or pelvic pain, increased urinary urgency and frequency and nocturia. The pathophysiology of IC/BPS is poorly understood, and theories include chronic inflammation, autoimmune dysregulation, bacterial cystitis, urothelial dysfunction, deficiency of the glycosaminoglycan (GAG) barrier and urine cytotoxicity. Multiple treatment options exist, including behavioural interventions, oral medications, intravesical instillations and procedures such as hydrodistension; however, many clinical trials fail, and patients experience an unsatisfactory treatment response, likely owing to IC/BPS phenotype heterogeneity and the use of non-targeted interventions. Oxidative stress is implicated in the pathogenesis of IC/BPS as reactive oxygen species impair bladder function via their involvement in multiple molecular mechanisms. Kinase signalling pathways, nociceptive receptors, mast-cell activation, urothelial dysregulation and circadian rhythm disturbance have all been linked to reactive oxygen species and IC/BPS. However, further research is necessary to fully uncover the role of oxidative stress in the pathways driving IC/BPS pathogenesis. The development of new models in which these pathways can be manipulated will aid this research and enable further investigation of promising therapeutic targets.

Mitochondrial Dysfunction and Protein Homeostasis in Aging: Insights from a Premature-Aging Mouse Model

Mitochondrial dysfunction has been implicated in aging and age-related disorders. Disturbed-protein homeostasis and clearance of damaged proteins have also been linked to aging, as well as to neurodegenerative diseases, cancers, and metabolic disorders. However, since mitochondrial oxidative phosphorylation, ubiquitin-proteasome, and autophagy-lysosome systems are tightly interdependent, it is not understood whether the facets observed in aging are the causes or consequences of one or all of these failed processes. We therefore used prematurely aging mtDNA-mutator mice and normally aging wild-type littermates to elucidate whether mitochondrial dysfunction per se is sufficient to impair cellular protein homeostasis similarly to that which is observed in aging. We found that both mitochondrial dysfunction and normal aging affect the ubiquitin-proteasome system in a tissue-dependent manner, whereas only normal aging markedly impairs the autophagy-lysosome system. Thus, our data show that the proteostasis network control in the prematurely aging mtDNA-mutator mouse differs in certain aspects from that found in normal aging. Taken together, our findings suggest that severe mitochondrial dysfunction drives an aging phenotype associated with the impairment of certain components of the protein homeostasis machinery, while others, such as the autophagy-lysosome system, are not affected or only minimally affected. Taken together, this shows that aging is a multifactorial process resulting from alterations of several integrated biological processes; thus, manipulating one process at the time might not be sufficient to fully recapitulate all changes associated with normal aging.

Biomolecules of Muscle Fatigue in Metabolic Myopathies

Metabolic myopathies are a group of genetic disorders that affect the normal functioning of muscles due to abnormalities in metabolic pathways. These conditions result in impaired energy production and utilization within muscle cells, leading to limitations in muscle function with concomitant occurrence of related signs and symptoms, among which fatigue is one of the most frequently reported. Understanding the underlying molecular mechanisms of muscle fatigue in these conditions is challenging for the development of an effective diagnostic and prognostic approach to test targeted therapeutic interventions. This paper outlines the key biomolecules involved in muscle fatigue in metabolic myopathies, including energy substrates, enzymes, ion channels, and signaling molecules. Potential future research directions in this field are also discussed.

What matters in aging is signaling for responsiveness

Biological responsiveness refers to the capacity of living organisms to adapt to changes in both their internal and external environments through physiological and behavioral mechanisms. One of the prominent aspects of aging is the decline in this responsiveness, which can lead to a deterioration in the processes required for maintenance, survival, and growth. The vital link between physiological responsiveness and the essential life processes lies within the signaling systems. To devise effective strategies for controlling the aging process, a comprehensive reevaluation of this connecting loop is imperative. This review aims to explore the impact of aging on signaling systems responsible for responsiveness and introduce a novel perspective on intervening in the aging process by restoring the compromised responsiveness. These innovative mechanistic approaches for modulating altered responsiveness hold the potential to illuminate the development of action plans aimed at controlling the aging process and treating age-related disorders.

Multi-Scale Label-Free Human Brain Imaging with Integrated Serial Sectioning Polarization Sensitive Optical Coherence Tomography and Two-Photon Microscopy

The study of aging and neurodegenerative processes in the human brain requires a comprehensive understanding of cytoarchitectonic, myeloarchitectonic, and vascular structures. Recent computational advances have enabled volumetric reconstruction of the human brain using thousands of stained slices, however, tissue distortions and loss resulting from standard histological processing have hindered deformation-free reconstruction. Here, the authors describe an integrated serial sectioning polarization-sensitive optical coherence tomography (PSOCT) and two photon microscopy (2PM) system to provide label-free multi-contrast imaging of intact brain structures, including scattering, birefringence, and autofluorescence of human brain tissue. The authors demonstrate high-throughput reconstruction of 4 × 4 × 2cm3 sample blocks and simple registration between PSOCT and 2PM images that enable comprehensive analysis of myelin content, vascular structure, and cellular information. The high-resolution 2PM images provide microscopic validation and enrichment of the cellular information provided by the PSOCT optical properties on the same sample, revealing the densely packed fibers, capillaries, and lipofuscin-filled cell bodies in the cortex and white matter. It is  shown that the imaging system enables quantitative characterization of various pathological features in aging process, including myelin degradation, lipofuscin accumulation, and microvascular changes, which opens up numerous opportunities in the study of neurodegenerative diseases in the future.

Brain macrophage development, diversity and dysregulation in health and disease

Brain macrophages include microglia in the parenchyma, border-associated macrophages in the meningeal-choroid plexus-perivascular space, and monocyte-derived macrophages that infiltrate the brain under various disease conditions. The vast heterogeneity of these cells has been elucidated over the last decade using revolutionary multiomics technologies. As such, we can now start to define these various macrophage populations according to their ontogeny and their diverse functional programs during brain development, homeostasis and disease pathogenesis. In this review, we first outline the critical roles played by brain macrophages during development and healthy aging. We then discuss how brain macrophages might undergo reprogramming and contribute to neurodegenerative disorders, autoimmune diseases, and glioma. Finally, we speculate about the most recent and ongoing discoveries that are prompting translational attempts to leverage brain macrophages as prognostic markers or therapeutic targets for diseases that affect the brain.

ANT2 Accelerates Cutaneous Wound Healing in Aged Skin by Regulating Energy Homeostasis and Inflammation

An effective healing response is critical to healthy aging. In particular, energy homeostasis has become increasingly recognized as a factor in effective skin regeneration. ANT2 is a mediator of adenosine triphosphate import into mitochondria for energy homeostasis. Although energy homeostasis and mitochondrial integrity are critical for wound healing, the role played by ANT2 in the repair process had not been elucidated to date. In our study, we found that ANT2 expression decreased in aged skin and cellular senescence. Interestingly, overexpression of ANT2 in aged mouse skin accelerated the healing of full-thickness cutaneous wounds. In addition, upregulation of ANT2 in replicative senescent human diploid dermal fibroblasts induced their proliferation and migration, which are critical processes in wound healing. Regarding energy homeostasis, ANT2 overexpression increased the adenosine triphosphate production rate by activating glycolysis and induced mitophagy. Notably, ANT2-mediated upregulation of HSPA6 in aged human diploid dermal fibroblasts downregulated proinflammatory genes that mediate cellular senescence and mitochondrial damage. This study shows a previously uncharacterized physiological role of ANT2 in skin wound healing by regulating cell proliferation, energy homeostasis, and inflammation. Thus, our study links energy metabolism to skin homeostasis and reports, to the best of our knowledge, a previously unreported genetic factor that enhances wound healing in an aging model.

Aging, longevity, and the role of environmental stressors: a focus on wildfire smoke and air quality

Aging is a complex biological process involving multiple interacting mechanisms and is being increasingly linked to environmental exposures such as wildfire smoke. In this review, we detail the hallmarks of aging, emphasizing the role of telomere attrition, cellular senescence, epigenetic alterations, proteostasis, genomic instability, and mitochondrial dysfunction, while also exploring integrative hallmarks - altered intercellular communication and stem cell exhaustion. Within each hallmark of aging, our review explores how environmental disasters like wildfires, and their resultant inhaled toxicants, interact with these aging mechanisms. The intersection between aging and environmental exposures, especially high-concentration insults from wildfires, remains under-studied. Preliminary evidence, from our group and others, suggests that inhaled wildfire smoke can accelerate markers of neurological aging and reduce learning capabilities. This is likely mediated by the augmentation of circulatory factors that compromise vascular and blood-brain barrier integrity, induce chronic neuroinflammation, and promote age-associated proteinopathy-related outcomes. Moreover, wildfire smoke may induce a reduced metabolic, senescent cellular phenotype. Future interventions could potentially leverage combined anti-inflammatory and NAD + boosting compounds to counter these effects. This review underscores the critical need to study the intricate interplay between environmental factors and the biological mechanisms of aging to pave the way for effective interventions.

Antioxidants Prevent Iron Accumulation and Lipid Peroxidation, but Do Not Correct Autophagy Dysfunction or Mitochondrial Bioenergetics in Cellular Models of BPAN

Neurodegeneration with brain iron accumulation (NBIA) is a group of rare neurogenetic disorders frequently associated with iron accumulation in the basal nuclei of the brain. Among NBIA subtypes, β-propeller protein-associated neurodegeneration (BPAN) is associated with mutations in the autophagy gene WDR45. The aim of this study was to demonstrate the autophagic defects and secondary pathological consequences in cellular models derived from two patients harboring WDR45 mutations. Both protein and mRNA expression levels of WDR45 were decreased in patient-derived fibroblasts. In addition, the increase of LC3B upon treatments with autophagy inducers or inhibitors was lower in mutant cells compared to control cells, suggesting decreased autophagosome formation and impaired autophagic flux. A transmission electron microscopy (TEM) analysis showed mitochondrial vacuolization associated with the accumulation of lipofuscin-like aggregates containing undegraded material. Autophagy dysregulation was also associated with iron accumulation and lipid peroxidation. In addition, mutant fibroblasts showed altered mitochondrial bioenergetics. Antioxidants such as pantothenate, vitamin E and α-lipoic prevented lipid peroxidation and iron accumulation. However, antioxidants were not able to correct the expression levels of WDR45, neither the autophagy defect nor cell bioenergetics. Our study demonstrated that WDR45 mutations in BPAN cellular models impaired autophagy, iron metabolism and cell bioenergetics. Antioxidants partially improved cell physiopathology; however, autophagy and cell bioenergetics remained affected.

Lipofuscin Granule Accumulation Requires Autophagy Activation

Lipofuscins are oxidized lipid and protein complexes that accumulate during cellular senescence and tissue aging, regarded as markers for cellular oxidative damage, tissue aging, and certain aging-associated diseases. Therefore, understanding their cellular biological properties is crucial for effective treatment development. Through traditional microscopy, lipofuscins are readily observed as fluorescent granules thought to accumulate in lysosomes. However, lipofuscin granule formation and accumulation in senescent cells are poorly understood. Thus, this study examined lipofuscin accumulation in human fibroblasts exposed to various stressors. Our results substantiate that in glucose-starved or replicative senescence cells, where elevated oxidative stress levels activate autophagy, lipofuscins predominately appear as granules that co-localize with autolysosomes due to lysosomal acidity or impairment. Meanwhile, autophagosome formation is attenuated in cells experiencing oxidative stress induced by a doxorubicin pulse and chase, and lipofuscin fluorescence granules seldom manifest in the cytoplasm. As Torin-1 treatment activates autophagy, granular lipofuscins intensify and dominate, indicating that autophagy activation triggers their accumulation. Our results suggest that high oxidative stress activates autophagy but fails in lipofuscin removal, leaving an abundance of lipofuscin-filled impaired autolysosomes, referred to as residual bodies. Therefore, future endeavors in treating lipofuscin pathology-associated diseases and dysfunctions through autophagy activation demand meticulous consideration.

APOE ε4 allele, along with G206D-PSEN1 mutation, alters mitochondrial networks and their degradation in Alzheimer's disease

Introduction

Alzheimer's disease remains the most common neurodegenerative disorder, depicted mainly by memory loss and the presence in the brain of senile plaques and neurofibrillary tangles. This disease is related to several cellular alterations like the loss of synapses, neuronal death, disruption of lipid homeostasis, mitochondrial fragmentation, or raised oxidative stress. Notably, changes in the autophagic pathway have turned out to be a key factor in the early development of the disease. The aim of this research is to determine the impact of the APOE allele ε4 and G206D-PSEN1 on the underlying mechanisms of Alzheimer's disease.

Methods

Fibroblasts from Alzheimer's patients with APOE 3/4 + G206D-PSEN1 mutation and homozygous APOE ε4 were used to study the effects of APOE polymorphism and PSEN1 mutation on the autophagy pathway, mitochondrial network fragmentation, superoxide anion levels, lysosome clustering, and p62/SQSTM1 levels.

Results

We observed that the APOE allele ε4 in homozygosis induces mitochondrial network fragmentation that correlates with an increased colocalization with p62/SQSTM1, probably due to an inefficient autophagy. Moreover, G206D-PSEN1 mutation causes an impairment of the integrity of mitochondrial networks, triggering high superoxide anion levels and thus making APOE 3/4 + PSEN1 fibroblasts more vulnerable to cell death induced by oxidative stress. Of note, PSEN1 mutation induces accumulation and clustering of lysosomes that, along with an increase of global p62/SQSTM1, could compromise lysosomal function and, ultimately, its degradation.

Conclusion

The findings suggest that all these modifications could eventually contribute to the neuronal degeneration that underlies the pathogenesis of Alzheimer's disease. Further research in this area may help to develop targeted therapies for the treatment of Alzheimer's disease.

Oxidative Stress-Induced Cellular Senescence: Is Labile Iron the Connecting Link?

Cellular senescence, a cell state characterized by a generally irreversible cell cycle arrest, is implicated in various physiological processes and a wide range of age-related pathologies. Oxidative stress, a condition caused by an imbalance between the production and the elimination of reactive oxygen species (ROS) in cells and tissues, is a common driver of cellular senescence. ROS encompass free radicals and other molecules formed as byproducts of oxygen metabolism, which exhibit varying chemical reactivity. A prerequisite for the generation of strong oxidizing ROS that can damage macromolecules and impair cellular function is the availability of labile (redox-active) iron, which catalyzes the formation of highly reactive free radicals. Targeting labile iron has been proven an effective strategy to counteract the adverse effects of ROS, but evidence concerning cellular senescence is sparse. In the present review article, we discuss aspects of oxidative stress-induced cellular senescence, with special attention to the potential implication of labile iron.

Aging - what it is and how to measure it

The current understanding of the biology of aging is largely based on research aimed at identifying factors that influence lifespan. However, lifespan as a sole proxy measure of aging has limitations because it can be influenced by specific pathologies (not generalized physiological deterioration in old age). Hence, there is a great need to discuss and design experimental approaches that are well-suited for studies targeting the biology of aging, rather than the biology of specific pathologies that restrict the lifespan of a given species. For this purpose, we here review various perspectives on aging, discuss agreement and disagreement among researchers on the definition of aging, and show that while slightly different aspects are emphasized, a widely accepted feature, shared across many definitions, is that aging is accompanied by phenotypic changes that occur in a population over the course of an average lifespan. We then discuss experimental approaches that are in line with these considerations, including multidimensional analytical frameworks as well as designs that facilitate the proper assessment of intervention effects on aging rate. The proposed framework can guide discovery approaches to aging mechanisms in all key model organisms (e.g., mouse, fish models, D. melanogaster, C. elegans) as well as in humans.

Multi-Scale Label-free Human Brain Imaging with Integrated Serial Sectioning Polarization Sensitive Optical Coherence Tomography and Two-Photon Microscopy

The study of neurodegenerative processes in the human brain requires a comprehensive understanding of cytoarchitectonic, myeloarchitectonic, and vascular structures. Recent computational advances have enabled volumetric reconstruction of the human brain using thousands of stained slices, however, tissue distortions and loss resulting from standard histological processing have hindered deformation-free reconstruction of the human brain. The development of a multi-scale and volumetric human brain imaging technique that can measure intact brain structure would be a major technical advance. Here, we describe the development of integrated serial sectioning Polarization Sensitive Optical Coherence Tomography (PSOCT) and Two Photon Microscopy (2PM) to provide label-free multi-contrast imaging, including scattering, birefringence and autofluorescence of human brain tissue. We demonstrate that high-throughput reconstruction of 4×4×2cm3 sample blocks and simple registration of PSOCT and 2PM images enable comprehensive analysis of myelin content, vascular structure, and cellular information. We show that 2μm in-plane resolution 2PM images provide microscopic validation and enrichment of the cellular information provided by the PSOCT optical property maps on the same sample, revealing the sophisticated capillary networks and lipofuscin filled cell bodies across the cortical layers. Our method is applicable to the study of a variety of pathological processes, including demyelination, cell loss, and microvascular changes in neurodegenerative diseases such as Alzheimer's disease (AD) and Chronic Traumatic Encephalopathy (CTE).

Autophagy, innate immunity, and cardiac disease

Autophagy is an evolutionarily conserved mechanism of cell adaptation to metabolic and environmental stress. It mediates the disposal of protein aggregates and dysfunctional organelles, although non-conventional features have recently emerged to broadly extend the pathophysiological relevance of autophagy. In baseline conditions, basal autophagy critically regulates cardiac homeostasis to preserve structural and functional integrity and protect against cell damage and genomic instability occurring with aging. Moreover, autophagy is stimulated by multiple cardiac injuries and contributes to mechanisms of response and remodeling following ischemia, pressure overload, and metabolic stress. Besides cardiac cells, autophagy orchestrates the maturation of neutrophils and other immune cells, influencing their function. In this review, we will discuss the evidence supporting the role of autophagy in cardiac homeostasis, aging, and cardioimmunological response to cardiac injury. Finally, we highlight possible translational perspectives of modulating autophagy for therapeutic purposes to improve the care of patients with acute and chronic cardiac disease.

Nigella sativa seeds mitigate the hepatic histo-architectural and ultrastructural changes induced by 4-nonylphenol in Clarias gariepinus

Due to its prevalence in aquatic environments and potential cytotoxicity, 4-nonylphenol (4-NP) has garnered considerable attention. As a medicinal plant with numerous biological activities, Nigella sativa (black seed or black cumin) seed (NSS) is widely utilized throughout the world. Consequently, this study aimed to examine the potential protective effects of NSS against 4-NP-induced hepatotoxicity in African catfish (Clarias gariepinus). To achieve this objective, 18 fish (351 ± 3 g) were randomly divided into three equal groups for 21 days. The first group serves as a control which did not receive any treatment except the basal diet. The second and third groups were exposed to 4-NP at a dose of 0.1 mg L^-1 of aquarium water and fed a basal diet only or supplemented with 2.5% NSS, respectively. The histological, histochemical, and ultrastructural features of the liver were subsequently evaluated as a damage biomarker of the hepatic tissue. Our results confirmed that 4-NP was a potent hepatotoxic agent, as 4-NP-intoxicated fish exhibited many lesions. Steatohepatitis, ballooning degeneration, sclerosing cholangitis, and coagulative necrosis of melanomacrophagecenters (MMCs) were observed. Hemosiderin, lipofuscin pigments, and proliferation of fibroblasts, kupffer cells, and telocytes were also demonstrated in the livers of 4-NP-intoxicated fish. In addition, decreased glycogen content and increased collagen deposition were observed in the hepatic tissue. Hepatocytes exhibited ultrastructural alterations in the chromatin, rough endoplasmic reticulum, smooth endoplasmic reticulum, mitochondria, lysosomes, and peroxisomes. Co-administration of 2.5% NSS to 4-NP-intoxicated fish significantly reduced these hepatotoxic effects. It nearly preserved the histological, histochemical, and ultrastructural integrity of hepatic tissue.

The phototoxicity action spectra of visible light in HaCaT keratinocytes

Visible light (VL) surely affects human skin in several ways, exerting positive (tissue regeneration, pain relief) and negative (oxidation, inflammation) effects, depending on the radiation dose and wavelength. Nevertheless, VL continues to be largely disregarded in photoprotection strategies, perhaps because the molecular mechanisms occurring during the interaction of VL with endogenous photosensitizers (ePS) and the subsequent biological responses are still poorly understood. Besides, VL encompass photons with different properties and interaction capacities with the ePS, but there are no quantitative comparisons of their effects on humans. Here, we studied the effects of physiologically relevant doses of four wavelengths ranges of VL, i.e. (in nm), 408-violet, 466/478-blue, 522-green, 650-red, in immortalized human skin keratinocytes (HaCaT). The level of cytotoxicity/damage follows the order: violet>blue >green>red. Violet and blue light induced the highest levels of Fpg-sensitive lesions in nuclear DNA, oxidative stress, lysosomal and mitochondrial damage, disruption of the lysosomal-mitochondrial axis of cell homeostasis, blockade of the autophagic flux, as well as lipofuscin accumulation, greatly increasing the toxicity of wideband VL to human skin. We hope this work will stimulate in development of optimized sun protection strategies.

CryoET reveals organelle phenotypes in huntington disease patient iPSC-derived and mouse primary neurons

Huntington's disease (HD) is caused by an expanded CAG repeat in the huntingtin gene, yielding a Huntingtin protein with an expanded polyglutamine tract. While experiments with patient-derived induced pluripotent stem cells (iPSCs) can help understand disease, defining pathological biomarkers remains challenging. Here, we used cryogenic electron tomography to visualize neurites in HD patient iPSC-derived neurons with varying CAG repeats, and primary cortical neurons from BACHD, deltaN17-BACHD, and wild-type mice. In HD models, we discovered sheet aggregates in double membrane-bound organelles, and mitochondria with distorted cristae and enlarged granules, likely mitochondrial RNA granules. We used artificial intelligence to quantify mitochondrial granules, and proteomics experiments reveal differential protein content in isolated HD mitochondria. Knockdown of Protein Inhibitor of Activated STAT1 ameliorated aberrant phenotypes in iPSC- and BACHD neurons. We show that integrated ultrastructural and proteomic approaches may uncover early HD phenotypes to accelerate diagnostics and the development of targeted therapeutics for HD.

H-2 increases oxidative stress resistance through DAF-16/FOXO pathways in Caenorhabditis elegans: A new approach to vitiligo treatment

Oxidative stress disrupts the homeostasis of the redox state in cells and induces apoptosis. Prolonged oxidative stress can impair the normal function of cells, tissues, and organs and lead to the development of several diseases. H-2 was synthesized by derivatising N-Alkylamides (NAAs) from Anacyclus pyrethrum (L.) DC, which is commonly used in the treatment of vitiligo in Uyghurs. The antioxidant activity and potential molecular mechanisms of H-2 were investigated using Caenorhabditis elegans (C. elegans) and mouse melanoma cell B16-F10 models. The in vivo anti-vitiligo activity of H-2 was studied using C57BL/6 mice. The results showed that H-2 could increase the survival time of nematodes under oxidative stress, promote the nuclear localization of DAF-16, and enhance the expression of Superoxide Dismutase 3 (SOD-3) in nematodes thereby activating the antioxidant enzyme system. H-2 could affect the survival rate of age-1 and akt-1 mutants under oxidative stress. H-2 could reverse the oxidative stress damage by reducing the reactive oxygen species (ROS) content in the Hydrogen peroxide (H₂O₂) -induced oxidative stress damage model of mouse melanoma cells B16-F10. In addition, it was also able to increase the number of melanocytes in the hair follicles of vitiligo model mice and improve the phenomenon of skin damage in mice. In conclusion, our findings suggest that H-2 can alleviate oxidative stress damage in C. elegans and B16-F10, which may be associated with oxidative stress, suppression of antioxidant defences, and transcription factors DAF-16/FOXO, providing beneficial evidence for the application of H-2 in the vitiligo treatment.

Ageing, Metabolic Dysfunction, and the Therapeutic Role of Antioxidants

The gradual ageing of the world population has been accompanied by a dramatic increase in the prevalence of obesity and metabolic diseases, especially type 2 diabetes. The adipose tissue dysfunction associated with ageing and obesity shares many common physiological features, including increased oxidative stress and inflammation. Understanding the mechanisms responsible for adipose tissue dysfunction in obesity may help elucidate the processes that contribute to the metabolic disturbances that occur with ageing. This, in turn, may help identify therapeutic targets for the treatment of obesity and age-related metabolic disorders. Because oxidative stress plays a critical role in these pathological processes, antioxidant dietary interventions could be of therapeutic value for the prevention and/or treatment of age-related diseases and obesity and their complications. In this chapter, we review the molecular and cellular mechanisms by which obesity predisposes individuals to accelerated ageing. Additionally, we critically review the potential of antioxidant dietary interventions to counteract obesity and ageing.

Ultrastructural evidence of four types of lipofuscins in the melanomacrophagic centers in hepatocytes of zebrafish (Denio rerio)

Melanomacrophagic centers (MMCs) were studied in the hepatocytes of zebrafish using transmission electron microscope (TEM). The MMCs with irregular or amoeboid nucleus were located in the hepatocytes adjacent to the bile canaliculi. Several engulfed structures were present in the cytoplasm of MMCs. The most frequent observation was the presence of mitochondria, ranging in size from small to giant, with distorted shape and inconspicuous cristae. Occasionally the fragments of erythrocytes were found. The rough endoplasmic reticulum (rER) showed whirling around the mitochondria and lipid droplets, forming membrane-like structures. The damaged mitochondria were invaded by the lysosomes, and this was covered by a membrane led to the formation of lipofuscin. Four different types of lipofuscins were observed; namely, (1) granular with/without vacuoles of high electron-density, (2) homogenous surrounded by indistinct limiting membrane, (3) lamellated structures similar to inner matrix and cristae of mitochondria, and, (4) compound structure made by the combinations of first 3 types, (granular and homogenous, granular and lamellated, homogenous and lamellated). The present evidence suggests that MMCs in the hepatocytes of zebrafish perform continuous functions of removal of the damaged cellular organelles. The lipofuscin formation work in coordination with the cellular players of immune system and remove pathogens and maintain the internal homeostasis of cells.

Fluorescence intensity and lifetime imaging of lipofuscin-like autofluorescence for label-free predicting clinical drug response in cancer

Conventional techniques for in vitro cancer drug screening require labor-intensive formalin fixation, paraffin embedding, and dye staining of tumor tissues at fixed endpoints. This way of assessment discards the valuable pharmacodynamic information in live cells over time. Here, we found endogenous lipofuscin-like autofluorescence acutely accumulated in the cell death process. Its unique red autofluorescence could report the apoptosis without labeling and continuously monitor the treatment responses in 3D tumor-culture models. Lifetime imaging of lipofuscin-like red autofluorescence could further distinguish necrosis from apoptosis of cells. Moreover, this endogenous fluorescent marker could visualize the apoptosis in live zebrafish embryos during development. Overall, this study validates that lipofuscin-like autofluorophore is a generic cell death marker. Its characteristic autofluorescence could label-free predict the efficacy of anti-cancer drugs in organoids or animal models.

Exogenous hydrogen sulfide inhibits the senescence of cardiomyocytes through modulating mitophagy in rats

Hydrogen sulfide (H2S), a gaseous molecule, has been shown to be involved in the regulation of body pathophysiological processes. Aging is related to structural and functional alterations within the heart. There is evidence that diminished mitophagy accelerates the aging process. Studies in recent years have revealed that plasma levels of H2S in humans and old rats decrease with age, and H2S acts as a cytoprotective mediator in the aging process. However, it is unclear whether H2S can delay the senescence of cardiomyocytes by regulating mitophagy. Our present results showed that exogenous H2S inhibited mitochondrial damage, oxidative stress and cell apoptosis, and enhanced mitophagy through upregulating the SIRT1-PINK1-parkin pathway in myocardial tissues of aged rats and cultured aged cardiomyocytes. Furthermore, the effect of exogenous H2S on the above indicators was the same as that of SRT1720 (a SIRT1 agonist) and kinetin (a PINK1 activator). Our findings suggest that exogenous H2S inhibits the senescence of cardiomyocytes by increasing mitophagy via upregulation of the SIRT1-PINK1-parkin pathway in rats.

Ventilator-induced lung injury results in oxidative stress response and mitochondrial swelling in a mouse model

Background

Mechanical ventilation is a life-saving therapy for critically ill patients, providing rest to the respiratory muscles and facilitating gas exchange in the lungs. Ventilator-induced lung injury (VILI) is an unfortunate side effect of mechanical ventilation that may lead to serious consequences for the patient and increase mortality. The four main injury mechanisms associated with VILI are: baro/volutrauma caused by overstretching the lung tissues; atelectrauma, caused by repeated opening and closing of the alveoli resulting in shear stress; oxygen toxicity due to use of high ratio of oxygen in inspired air, causing formation of free radicals; and biotrauma, the resulting biological response to tissue injury, that leads to a cascade of events due to excessive inflammatory reactions and may cause multi-organ failure. An often-overlooked part of the inflammatory reaction is oxidative stress. In this research, a mouse model of VILI was set up with three tidal volume settings (10, 20 and 30 mL/kg) at atmospheric oxygen level. Airway pressures and heart rate were monitored and bronchoalveolar lavage fluid (BALF) and lung tissue samples were taken.

Results

We show a correlation between increased inflammation and barrier failure, and higher tidal volumes, evidenced by increased IL-6 expression, high concentration of proteins in BALF along with changes in expression of adhesion molecules. Furthermore, swelling of mitochondria in alveolar type II cells was seen indicating their dysfunction and senescence-like state. RNA sequencing data present clear increases in inflammation, mitochondrial biogenesis and oxidative stress as tidal volume is increased, supported by degradation of Keap1, a redox-regulated substrate adaptor protein.

Conclusions

Oxidative stress seems to be a more prominent mechanism of VILI than previously considered, indicating that possible treatment methods against VILI might be identified by impeding oxidative pathways.

The Role of Mitochondrial Enzymes, Succinate-Coupled Signaling Pathways and Mitochondrial Ultrastructure in the Formation of Urgent Adaptation to Acute Hypoxia in the Myocardium

The effect of a single one-hour exposure to three modes of hypobaric hypoxia (HBH) differed in the content of O₂ in inhaled air (FiO₂-14%, 10%, 8%) in the development of mitochondrial-dependent adaptive processes in the myocardium was studied in vivo. The following parameters have been examined: (a) an urgent reaction of catalytic subunits of mitochondrial enzymes (NDUFV2, SDHA, Cyt b, COX2, ATP5A) in the myocardium as an indicator of the state of the respiratory chain electron transport function; (b) an urgent activation of signaling pathways dependent on GPR91, HIF-1α and VEGF, allowing us to assess their role in the formation of urgent mechanisms of adaptation to hypoxia in the myocardium; (c) changes in the ultrastructure of three subpopulations of myocardial mitochondria under these conditions. The studies were conducted on two rat phenotypes: rats with low resistance (LR) and high resistance (HR) to hypoxia. The adaptive and compensatory role of the mitochondrial complex II (MC II) in maintaining the electron transport and energy function of the myocardium in a wide range of reduced O₂ concentrations in the initial period of hypoxic exposure has been established. The features of urgent reciprocal regulatory interaction of NAD- and FAD-dependent oxidation pathways in myocardial mitochondria under these conditions have been revealed. The data indicating the participation of GPR91, HIF-1a and VEGF in this process have been obtained. The ultrastructure of the mitochondrial subpopulations in the myocardium of LR and HR rats differed in normoxic conditions and reacted differently to hypoxia of varying severity. The parameters studied together are highly informative indicators of the quality of cardiac activity and metabolic biomarkers of urgent adaptation in various hypoxic conditions.

Vicious cycle of lipid peroxidation and iron accumulation in neurodegeneration

Lipid peroxidation and iron accumulation are closely associated with neurodegenerative diseases, such as Alzheimer's, Parkinson's, and Huntington's diseases, or neurodegeneration with brain iron accumulation disorders. Mitochondrial dysfunction, lipofuscin accumulation, autophagy disruption, and ferroptosis have been implicated as the critical pathomechanisms of lipid peroxidation and iron accumulation in these disorders. Currently, the connection between lipid peroxidation and iron accumulation and the initial cause or consequence in neurodegeneration processes is unclear. In this review, we have compiled the known mechanisms by which lipid peroxidation triggers iron accumulation and lipofuscin formation, and the effect of iron overload on lipid peroxidation and cellular function. The vicious cycle established between both pathological alterations may lead to the development of neurodegeneration. Therefore, the investigation of these mechanisms is essential for exploring therapeutic strategies to restrict neurodegeneration. In addition, we discuss the interplay between lipid peroxidation and iron accumulation in neurodegeneration, particularly in PLA2G6-associated neurodegeneration, a rare neurodegenerative disease with autosomal recessive inheritance, which belongs to the group of neurodegeneration with brain iron accumulation disorders.

Telomeres and Telomerase in the Control of Stem Cells

Stem cells serve as a source of cellular material in embryogenesis and postnatal growth and regeneration. This requires significant proliferative potential ensured by sufficient telomere length. Telomere attrition in the stem cells and their niche cells can result in the exhaustion of the regenerative potential of high-turnover organs, causing or contributing to the onset of age-related diseases. In this review, stem cells are examined in the context of the current telomere-centric theory of cell aging, which assumes that telomere shortening depends not just on the number of cell doublings (mitotic clock) but also on the influence of various internal and external factors. The influence of the telomerase and telomere length on the functional activity of different stem cell types, as well as on their aging and prospects of use in cell therapy applications, is discussed.

Dual effects of supplemental oxygen on pulmonary infection, inflammatory lung injury, and neuromodulation in aging and COVID-19

Clinical studies have shown a significant positive correlation between age and the likelihood of being infected with SARS-CoV-2. This increased susceptibility is positively correlated with chronic inflammation and compromised neurocognitive functions. Postmortem analyses suggest that acute lung injury (ALI)/acute respiratory distress syndrome (ARDS), with systemic and lung hyperinflammation, can cause significant morbidity and mortality in COVID-19 patients. Supraphysiological supplemental oxygen, also known as hyperoxia, is commonly used to treat decreased blood oxygen saturation in COVID-19 patients. However, prolonged exposure to hyperoxia alone can cause oxygen toxicity, due to an excessive increase in the levels of reactive oxygen species (ROS), which can overwhelm the cellular antioxidant capacity. Subsequently, this causes oxidative cellular damage and increased levels of aging biomarkers, such as telomere shortening and inflammaging. The oxidative stress in the lungs and brain can compromise innate immunity, resulting in an increased susceptibility to secondary lung infections, impaired neurocognitive functions, and dysregulated hyperinflammation, which can lead to ALI/ARDS, and even death. Studies indicate that lung inflammation is regulated by the central nervous system, notably, the cholinergic anti-inflammatory pathway (CAIP), which is innervated by the vagus nerve and α7 nicotinic acetylcholine receptors (α7nAChRs) on lung cells, particularly lung macrophages. The activation of α7nAChRs attenuates oxygen toxicity in the lungs and improves clinical outcomes by restoring hyperoxia-compromised innate immunity. Mechanistically, α7nAChR agonist (e.g., GAT 107 and GTS-21) can regulate redox signaling by 1) activating Nrf2, a master regulator of the antioxidant response and a cytoprotective defense system, which can decrease cellular damage caused by ROS and 2) inhibiting the activation of the NF-κB-mediated inflammatory response. Notably, GTS-21 has been shown to be safe and it improves neurocognitive functions in humans. Therefore, targeting the α7nAChR may represent a viable therapeutic approach for attenuating dysregulated hyperinflammation-mediated ARDS and sepsis in COVID-19 patients receiving prolonged oxygen therapy.

A racemosin B derivative, C25, suppresses breast cancer growth via lysosomal membrane permeabilization and inhibition of autophagic flux

Breast cancer is the most common malignancy among women worldwide. As conventional therapies are only partially successful in eradicating breast cancer, the development of novel strategies is a top priority. We previously showed that C25, a new racemosin B derivative, exerts its anti-cancer activity through inhibition of autophagy, but the underlying mechanism remained unknown. Here we show that C25 inhibits the growth of diverse breast cancer cell subtypes and effectively suppresses tumor progression in a xenotransplantation model of triple negative breast cancer. C25 acts as a lysosomotropic agent to induce lysosomal membrane permeabilization and inhibit autophagic flux, resulting in cathepsin release and cell death. In accordance, RNA sequencing and gene set enrichment analysis revealed that C25 induces pathways consistent with autophagy inhibition, cell cycle arrest and senescence. Interestingly, knockdown of TFEB or SQSTM1 reduced cell death induced by C25 treatment. Finally, we show that C25 synergizes with the chemo-therapeutics etoposide and paclitaxel to further limit breast cancer cell growth. Thus, C25 alone or in combination with other anti-neoplastic agents offers a novel therapeutic strategy for aggressive forms of breast cancer and possibly other malignancies.

Engineering Closed-Loop, Autoregulatory Gene Circuits for Osteoarthritis Cell-Based Therapies

PURPOSE OF REVIEW

Genetic engineering offers the possibility to simultaneously target multiple cellular pathways in the joints affected by osteoarthritis (OA). The purpose of this review is to summarize the ongoing efforts to develop disease-modifying osteoarthritis drugs (DMOADs) using genetic engineering, including targeting approaches, genome editing techniques, and delivery methods.

RECENT FINDINGS

Several gene circuits have been developed that reprogram cells to autonomously target inflammation, and their efficacy has been demonstrated in chondrocytes and stem cells. Gene circuits developed for metabolic disorders, such as those targeting insulin resistance and obesity, also have the potential to mitigate the impact of these conditions on OA onset and/or progression. Despite the strides made in characterizing the inflammatory environment of the OA joint, our incomplete understanding of how the multiple regulators interact to control signal transduction, gene transcription, and translation to protein limits the development of targeted disease-modifying therapeutics. Continuous advances in targeted genome editing, combined with online toolkits that simplify the design and production of gene circuits, have the potential to accelerate the discovery and clinical application of multi-target gene circuits with disease-modifying properties for the treatment of OA.

Vitamin E prevents lipid peroxidation and iron accumulation in PLA2G6-Associated Neurodegeneration

BACKGROUND

PLA2G6-Associated Neurodegeneration (PLAN) is a rare neurodegenerative disease with autosomal recessive inheritance, which belongs to the NBIA (Neurodegeneration with Brain Iron Accumulation) group. Although the pathogenesis of the disease remains largely unclear, lipid peroxidation seems to play a central role in the pathogenesis. Currently, there is no cure for the disease.

OBJECTIVE

In this work, we examined the presence of lipid peroxidation, iron accumulation and mitochondrial dysfunction in two cellular models of PLAN, patients-derived fibroblasts and induced neurons, and assessed the effects of α-tocopherol (vitamin E) in correcting the pathophysiological alterations in PLAN cell cultures.

METHODS

Pathophysiological alterations were examined in fibroblasts and induced neurons generated by direct reprograming. Iron and lipofuscin accumulation were assessed using light and electron microscopy, as well as biochemical analysis techniques. Reactive Oxygen species production, lipid peroxidation and mitochondrial dysfunction were measured using specific fluorescent probes analysed by fluorescence microscopy and flow cytometry.

RESULTS

PLAN fibroblasts and induced neurons clearly showed increased lipid peroxidation, iron accumulation and altered mitochondrial membrane potential. All these pathological features were reverted with vitamin E treatment.

CONCLUSIONS

PLAN fibroblasts and induced neurons reproduce the main pathological alterations of the disease and provide useful tools for disease modelling. The main pathological alterations were corrected by Vitamin E supplementation in both models, suggesting that blocking lipid peroxidation progression is a critical therapeutic target.

Mitochondria, energy, and metabolism in neuronal health and disease

Mitochondria are associated with various cellular activities critical to homeostasis, particularly in the nervous system. The plastic architecture of the mitochondrial network and its dynamic structure play crucial roles in ensuring that varying energetic demands are rapidly met to maintain neuronal and axonal energy homeostasis. Recent evidence associates ageing and neurodegeneration with anomalous neuronal metabolism, as age-dependent alterations of neuronal metabolism are now believed to occur prior to neurodegeneration. The brain has a high energy demand, which makes it particularly sensitive to mitochondrial dysfunction. Distinct cellular events causing oxidative stress or disruption of metabolism and mitochondrial homeostasis can trigger a neuropathology. This review explores the bioenergetic hypothesis for the neurodegenerative pathomechanisms, discussing factors leading to age-related brain hypometabolism and its contribution to cognitive decline. Recent research on the mitochondrial network in healthy nervous system cells, its response to stress and how it is affected by pathology, as well as current contributions to novel therapeutic approaches will be highlighted.

Principles of brain aging: Status and challenges of modeling human molecular changes in mice

Due to the extension of human life expectancy, the prevalence of cognitive impairment is rising in the older portion of society. Developing new strategies to delay or attenuate cognitive decline is vital. For this purpose, it is imperative to understand the cellular and molecular events at the basis of brain aging. While several organs are directly accessible to molecular analysis through biopsies, the brain constitutes a notable exception. Most of the molecular studies are performed on postmortem tissues, where cell death and tissue damage have already occurred. Hence, the study of the molecular aspects of cognitive decline largely relies on animal models and in particular on small mammals such as mice. What have we learned from these models? Do these animals recapitulate the changes observed in humans? What should we expect from future mouse studies? In this review we answer these questions by summarizing the state of the research that has addressed cognitive decline in mice from several perspectives, including genetic manipulation and omics strategies. We conclude that, while extremely valuable, mouse models have limitations that can be addressed by the optimal design of future studies and by ensuring that results are cross-validated in the human context.

Progressive reorganization of mitochondrial apparatus in aging skeletal muscle of naked mole rats (Heterocephalus glaber) as revealed by electron microscopy: potential role in continual maintenance of muscle activity

The authors examined the ultrastructure of mitochondrial apparatus of skeletal muscles of naked mole rats (Heterocephalus glaber) from the age of 6 months to 11 years. The obtained results have demonstrated that the mitochondria in skeletal muscles of naked mole rats aged below 5 years is not well-developed and represented by few separate small mitochondria. Mitochondrial reticulum is absent. Starting from the age of 5 years, a powerful mitochondrial structure is developed. By the age of 11 years, it become obvious that the mitochondrial apparatus formed differs from that in the skeletal muscle of adult rats and mice, but resembles that of cardiomyocytes of rats or naked mole rats cardiomyocytes. From the age of 6 months to 11 years, percentage area of mitochondria in the skeletal muscle of naked mole rat is increasing by five times. The growth of mitochondria is mainly driven by increased number of organelles. Such significant growth of mitochondria is not associated with any abnormal changes in mitochondrial ultrastructure.

We suppose that specific structure of mitochondrial apparatus developed in the skeletal muscle of naked mole rats by the age of 11 years is necessary for continual skeletal muscle activity of these small mammals burrowing very long holes in stony earth, resembling continual activity of heart muscle. In any case, ontogenesis of naked mole rat skeletal muscles is much slower than of rats and mice (one more example of neoteny).

Claudin-1-Targeted Nanoparticles for Delivery to Aging-Induced Alterations in the Blood-Brain Barrier

Aging-induced alterations to the blood-brain barrier (BBB) are increasingly being seen as a primary event in chronic progressive neurological disorders that lead to cognitive decline. With the goal of increasing delivery into the brain in hopes of effectively treating these diseases, a large focus has been placed on developing BBB permeable materials. However, these strategies have suffered from a lack of specificity toward regions of disease progression. Here, we report on the development of a nanoparticle (C1C2-NP) that targets regions of increased claudin-1 expression that reduces BBB integrity. Using dynamic contrast enhanced magnetic resonance imaging, we find that C1C2-NP accumulation and retention is significantly increased in brains from 12 month-old mice as compared to nontargeted NPs and brains from 2 month-old mice. Furthermore, we find C1C2-NP accumulation in brain endothelial cells with high claudin-1 expression, suggesting target-specific binding of the NPs, which was validated through fluorescence imaging, in vitro testing, and biophysical analyses. Our results further suggest a role of claudin-1 in reducing BBB integrity during aging and show altered expression of claudin-1 can be actively targeted with NPs. These findings could help develop strategies for longitudinal monitoring of tight junction protein expression changes during aging as well as be used as a delivery strategy for site-specific delivery of therapeutics at these early stages of disease development.

The relationship between melanin production and lipofuscin formation in Tyrosinase gene knockout melanocytes using CRISPR/Cas9 system

Age spots are a significant phenotypic marker of aging formed by lipofuscin. Melanin is another skin pigment molecule responsible for skin aging. The present study aims to investigate the relationship between melanin production and lipofuscin synthesis in normal mouse melanoma cell line B16F1 cells and Tyrosinase (TYR) gene knockout cells. TYR gene KO cells were successfully developed using CRISPR/Cas9 system and confirmed by Sanger DNA sequencing analysis. Furthermore, the melanin production and lipofuscin formation were validated through RT-PCR and Western blot analysis. The expression levels of gene microphthalmia-associated transcription factor (MITF), Tyrosinase, tyrosine-related protein-1 (TRP-1), tyrosine-related protein-2 (TRP-2), and antioxidant proteins such as methionine sulfoxide reductase A (MSRA), Catalase and Glutathione reductase (GR) related to melanogenesis was found to be decreased in TYR gene KO cells compared with normal cells. Moreover, lipofuscin formation was increased in TYR gene KO cells compared to normal cells. Therefore, the above findings suggest that melanin production and lipofuscin formation could be linked by the TYR gene in melanocytes.

Allostatic Load, Mobility Disability, and Viral Effects in Cancer: A Structural Equation Model

A growing number of cancers have been linked to specific oncogenic viruses and physiological stress. Recently, two separate studies linked mobility limitations to allostatic load and four major cancer types. The objective of this study was to determine if cancer occurrence regresses on three latent domains of Allostatic Load, Level of Physical Functioning (i.e., Mobility Disability), and Viral Exposure. We compared several structural equation models using adult participant (n = 17,969) data from three National Health and Nutrition Examination Survey (NHANES) periods. The primary two-level model with three exogenous latent factors and a single Cancer endogenous latent factor demonstrated a strong fit (GFI = 0.948, RMSEA = 0.024), and the model had a non-significant Chi-Square indicative of a strong model.What is already known on this subjectAllostatic load represents how the body responds to physiological stress and is associated with increased morbidity/mortality, including cancers.Viruses are the causative agents of 15-20% of cancers and can be stress activated.People with mobility limitations experience significantly higher allostatic loads and secondary health conditions, and one recent study indicates a heightened risk for certain cancers.What this study addsThis study is original in its testing of a conceptual model that links together cancer outcomes with latent factors/variables including disability/mobility limitations, allostatic load, and viral exposure.The study indicates that there might be important associations between allostatic load, disability burden, and viral exposure/activation on the occurrence of cancer.The research suggests the need for stress reduction, preventative health interventions, and additional supports for people with disabilities and their caregivers.

Involvement of Autophagy in Ageing and Chronic Cholestatic Diseases

Autophagy is a “housekeeping” lysosomal degradation process involved in numerous physiological and pathological processes in all eukaryotic cells. The dysregulation of hepatic autophagy has been described in several conditions, from obesity to diabetes and cholestatic disease. We review the role of autophagy, focusing on age-related cholestatic diseases, and discuss its therapeutic potential and the molecular targets identified to date. The accumulation of toxic BAs is the main cause of cell damage in cholestasis patients. BAs and their receptor, FXR, have been implicated in the regulation of hepatic autophagy. The mechanisms by which cholestasis induces liver damage include mitochondrial dysfunction, oxidative stress and ER stress, which lead to cell death and ultimately to liver fibrosis as a compensatory mechanism to reduce the damage. The stimulation of autophagy seems to ameliorate the liver damage. Autophagic activity decreases with age in several species, whereas its basic extends lifespan in animals, suggesting that it is one of the convergent mechanisms of several longevity pathways. No strategies aimed at inducing autophagy have yet been tested in cholestasis patients. However, its stimulation can be viewed as a novel therapeutic strategy that may reduce ageing-dependent liver deterioration and also mitigate hepatic steatosis.

Inflammatory Molecular Mediators and Pathways Involved in Vascular Aging and Stroke: A Comprehensive Review

There is an increase in the incidence of cardiovascular diseases with aging and it is one of the leading causes of death worldwide. The main cardiovascular pathologies include atherosclerosis, stroke, myocardial infarction, hypertension and stroke. Chronic inflammation is one of the significant contributors to the age-related vascular diseases. Therefore, it is important to understand the molecular mechanisms of the persistent inflammatory conditions occurring in the blood vessels as well as the signaling pathways involved. Herein, we performed an extant search of literature involving PubMed, ISI, WoS and Scopus databases for retrieving all relevant articles with the most recent findings illustrating the potential role of various inflammatory mediators along with their proposed activated pathways in the pathogenesis and progression of vascular aging. We also highlight the major pathways contributing to age-related vascular disorders. The outlined molecular mechanisms, pathways and mediators of vascular aging represent potential drug targets that can be utilized to inhibit and/or slow the pathogenesis and progression of vascular aging.

Single-nucleus transcriptomic landscape of primate hippocampal aging

The hippocampus plays a crucial role in learning and memory, and its progressive deterioration with age is functionally linked to a variety of human neurodegenerative diseases. Yet a systematic profiling of the aging effects on various hippocampal cell types in primates is still missing. Here, we reported a variety of new aging-associated phenotypic changes of the primate hippocampus. These include, in particular, increased DNA damage and heterochromatin erosion with time, alongside loss of proteostasis and elevated inflammation. To understand their cellular and molecular causes, we established the first single-nucleus transcriptomic atlas of primate hippocampal aging. Among the 12 identified cell types, neural transiently amplifying progenitor cell (TAPC) and microglia were most affected by aging. In-depth dissection of gene-expression dynamics revealed impaired TAPC division and compromised neuronal function along the neurogenesis trajectory; additionally elevated pro-inflammatory responses in the aged microglia and oligodendrocyte, as well as dysregulated coagulation pathways in the aged endothelial cells may contribute to a hostile microenvironment for neurogenesis. This rich resource for understanding primate hippocampal aging may provide potential diagnostic biomarkers and therapeutic interventions against age-related neurodegenerative diseases.

Signaling Role of Mitochondrial Enzymes and Ultrastructure in the Formation of Molecular Mechanisms of Adaptation to Hypoxia

This study was the first comprehensive investigation of the dependence of mitochondrial enzyme response (catalytic subunits of mitochondrial complexes (MC) I-V, including NDUFV2, SDHA, Cyt b, COX1 and ATP5A) and mitochondrial ultrastructure in the rat cerebral cortex (CC) on the severity and duration of in vivo hypoxic exposures. The role of individual animal's resistance to hypoxia was also studied. The respiratory chain (RC) was shown to respond to changes in environmental [O2] as follows: (a) differential reaction of mitochondrial enzymes, which depends on the severity of the hypoxic exposure and which indicates changes in the content and catalytic properties of mitochondrial enzymes, both during acute and multiple exposures; and (b) ultrastructural changes in mitochondria, which reflect various degrees of mitochondrial energization. Within a specific range of reduced O2 concentrations, activation of the MC II is a compensatory response supporting the RC electron transport function. In this process, MC I develops new kinetic properties, and its function recovers in hypoxia by reprograming the RC substrate site. Therefore, the mitochondrial RC performs as an in vivo molecular oxygen sensor. Substantial differences between responses of rats with high and low resistance to hypoxia were determined.

Extended criteria grafts and emerging therapeutics strategy in liver transplantation. The unstable balance between damage and repair

Due to increasing demand for donor organs, "extended criteria" donors are increasingly considered for liver transplantation, including elderly donors and donors after cardiac death. The grafts of this subgroup of donors share a major risk to develop significant features of ischemia reperfusion injury, that may eventually lead to graft failure. Ex-situ machine perfusion technology has gained much interest in liver transplantation, because represents both a useful tool for improving graft quality before transplantation and a platform for the delivery of therapeutics directly to the organ. In this review, we survey ongoing clinical evidences supporting the use of elderly and DCD donors in liver transplantation, and the underlying mechanistic aspects of liver aging and ischemia reperfusion injury that influence graft quality and transplant outcome. Finally, we highlight evidences in the field of new therapeutics to test in MP in the context of recent findings of basic and translational research.

Redox changes in obesity, metabolic syndrome, and diabetes

"Life is an instantaneous encounter of circulating matter and flowing energy" (Jean Giaja, Serbian physiologist), is one of the most elegant definitions not only of life but the relationship of redox biology and metabolism. Their evolutionary liaison has created inseparable yet dynamic homeostasis in health, which, when disrupted, leads to disease. This interconnection is even more pertinent today, in an era of increasing metabolic diseases of epidemic proportions such as obesity, metabolic syndrome, and diabetes. Despite great advances in understanding the molecular mechanisms of redox and metabolic regulation, we face significant challenges in preventing, diagnosing, and treating metabolic diseases. The etiological association and temporal overlap of these syndromes present significant challenges for the discrimination of appropriate clinical biomarkers for diagnosis, treatment, and outcome prediction. These multifactorial, multiorgan metabolic syndromes with complex etiopathogenic mechanisms are accompanied by disturbed redox equilibrium in target tissues and circulation. Free radicals and reactive species are considered both a causal factor and a consequence of disease status. Thus, determining the subtypes and levels of free radicals and reactive species, oxidatively damaged biomolecules (lipids, proteins, and nucleic acids) and antioxidant defense components as well as redox-sensitive transcription factors and fluxes of redox-dependent metabolic pathways will help define existing and establish novel redox biomarkers for stratifying metabolic diseases. This review aims to discuss diverse redox/metabolic aspects in obesity, metabolic syndrome, and diabetes, with the imperative to help establish a platform for emerging and future redox-metabolic biomarkers research in precision medicine. Future research warrants detailed investigations into the status of redox biomarkers in healthy subjects and patients, including the use of emerging 'omic' profiling technologies (e.g., redox proteomes, lipidomes, metabolomes, and transcriptomes), taking into account the influence of lifestyle (diet, physical activity, sleep, work patterns) as well as circadian ~24h fluctuations in circulatory factors and metabolites.

Metabolic Complications in Cardiac Aging

Aging is a process that can be accompanied by molecular and cellular alterations that compromise cardiac function. Although other metabolic disorders with increased prevalence in aged populations, such as diabetes mellitus, dyslipidemia, and hypertension, are associated with cardiovascular complications; aging-related cardiomyopathy has some unique features. Healthy hearts oxidize fatty acids, glucose, lactate, ketone bodies, and amino acids for producing energy. Under physiological conditions, cardiac mitochondria use fatty acids and carbohydrate mainly to generate ATP, 70% of which is derived from fatty acid oxidation (FAO). However, relative contribution of nutrients in ATP synthesis is altered in the aging heart with glucose oxidation increasing at the expense of FAO. Cardiac aging is also associated with impairment of mitochondrial abundance and function, resulting in accumulation of reactive oxygen species (ROS) and activation of oxidant signaling that eventually leads to further mitochondrial damage and aggravation of cardiac function. This review summarizes the main components of pathophysiology of cardiac aging, which pertain to cardiac metabolism, mitochondrial function, and systemic metabolic changes that affect cardiac function.

The Subtle Role of Para-inflammation in Modulating the Progression of Dry Eye Disease

In patients with DED, the continuous stimuli induced by excessive or persistent cold fiber sensors and overstimulation of nociceptors, as well as tear hyperosmolarity induced by evaporative stress, induce a transitory protective adaptation response called para-inflammation to restore ocular surface homeostasis. This mild subclinical inflammatory status (a type of hormetic response) can become chronic if the stimuli or tissue malfunction is present for a sustained period, causing persistent symptoms and damage to ocular surface epithelia.We review the mechanisms that characterize the transition from para-inflammation to a persistent inflammatory status of the ocular surface, including accumulation of biological waste and damaged/dysfunctional proteins, which, in normal conditions, are eliminated by autophagy, activation of the inflammasomes, and what is currently known about their role in DED pathogenesis. Furthermore, we analyze current treatments that can modulate the inflammatory response of the ocular surface and speculate about new possible therapies to treat para-inflammation.

Role of Oxidative Stress in Reperfusion following Myocardial Ischemia and Its Treatments

Myocardial ischemia is a disease with high morbidity and mortality, for which reperfusion is currently the standard intervention. However, the reperfusion may lead to further myocardial damage, known as myocardial ischemia/reperfusion injury (MI/RI). Oxidative stress is one of the most important pathological mechanisms in reperfusion injury, which causes apoptosis, autophagy, inflammation, and some other damage in cardiomyocytes through multiple pathways, thus causing irreversible cardiomyocyte damage and cardiac dysfunction. This article reviews the pathological mechanisms of oxidative stress involved in reperfusion injury and the interventions for different pathways and targets, so as to form systematic treatments for oxidative stress-induced myocardial reperfusion injury and make up for the lack of monotherapy.