bims-senagi Biomed News
on Senescence and aging
Issue of 2021–08–08
38 papers selected by
Maria Grazia Vizioli, Mayo Clinic
  1. Breathe it in - spotlight on senescence and regeneration in the lung.
  2. Impact of Senescent Cell Subtypes on Tissue Dysfunction and Repair: Importance and Research Questions.
  3. The Emergence of Senescent Surface Biomarkers as Senotherapeutic Targets.
  4. mTOR Activity and Autophagy in Senescent Cells, a Complex Partnership.
  5. The Role of T Cell Senescence in Neurological Diseases and Its Regulation by Cellular Metabolism.
  6. Ouabain and chloroquine trigger senolysis of BRAF-V600E-induced senescent cells by targeting autophagy.
  7. Role of Cellular Senescence in Type II Diabetes.
  8. Monoallelic IDH1 R132H mutation mediates glioma cell response to anti-cancer therapies via induction of senescence.
  9. Deficiency of Heat shock factor 4 promotes lens epithelial cell senescence through upregulating p21cip1 expression.
  10. Extracellular vesicles released from stress-induced premature senescent myoblasts impair endothelial function and proliferation.
  11. Chronological Age Affects MSC Senescence In Vitro-A Systematic Review.
  12. Aging and neuroinflammation: Changes in immune cell responses, axon integrity, and motor function in a viral model of progressive multiple sclerosis.
  13. Klotho inhibits neuronal senescence in human brain organoids.
  14. Alpha-Synuclein Preformed Fibrils Induce Cellular Senescence in Parkinson's Disease Models.
  15. Curcumol inhibits ferritinophagy to restrain hepatocyte senescence through YAP/NCOA4 in non-alcoholic fatty liver disease.
  16. CCM2-deficient endothelial cells undergo a ROCK-dependent reprogramming into senescence-associated secretory phenotype.
  17. Aging influences the cardiac macrophage phenotype and function during steady state and during inflammation.
  18. Age-related changes of human serum Sirtuin6 in adults.
  19. Youthful and age-related matreotypes predict drugs promoting longevity.
  20. Role of Melatonin in Angiotensin and Aging.
  21. Acute ischemic stroke triggers a cellular senescence-associated secretory phenotype.
  22. Premature Senescence of T-cells Favors Bone Loss During Osteolytic Diseases. A New Concern in the Osteoimmunology Arena.
  23. Leukemia-Induced Cellular Senescence and Stemness Alterations in Mesenchymal Stem Cells Are Reversible upon Withdrawal of B-Cell Acute Lymphoblastic Leukemia Cells.
  24. Higher senescence associated secretory phenotype and lower defense mediator in urinary extracellular vesicles of elders with and without Parkinson disease.
  25. The role of retrotransposable elements in ageing and age-associated diseases.
  26. Instability in NAD+ metabolism leads to impaired cardiac mitochondrial function and communication.
  27. Effects and Mechanisms of Resveratrol on Aging and Age-Related Diseases.
  28. tRNA-derived fragments as New Hallmarks of Aging and Age-related Diseases.
  29. An Overview of NO Signaling Pathways in Aging.
  30. Telomere Length Shortening in Microglia: Implication for Accelerated Senescence and Neurocognitive Deficits in HIV.
  31. Biological age in healthy elderly predicts aging-related diseases including dementia.
  32. Systematic Review of Studies on Telomere Length in Patients with Multiple Sclerosis.
  33. Exploring ER stress response in cellular aging and neuroinflammation in Alzheimer's disease.
  34. Microglia and the Aging Brain: Are Geriatric Microglia Linked to Poor Sleep Quality?
  35. Genetic insights into biological mechanisms governing human ovarian ageing.
  36. Immune Checkpoint Inhibitors in the Aged.
  37. Impact of aging and exercise on skeletal muscle mitochondrial capacity, energy metabolism, and physical function.
  38. The Role of SGLT2 Inhibitors in Vascular Aging.
  1. Mech Ageing Dev. 2021 Aug 02. pii: S0047-6374(21)00122-6. [Epub ahead of print] 111550
    Breathe it in - spotlight on senescence and regeneration in the lung.
    Julia Majewska, Valery Krizhanovsky.
      Cellular senescence, a highly coordinated and programmed cellular state, has a functional role in both lung physiology and pathology. While the contribution of senescent cells is recognized in the context of ageing and age-related pulmonary diseases, relatively less is known how cellular senescence of functionally distinct cell types leads to the progression of these pathologies. Recent advances in tools to track and isolate senescent cells from tissues, shed a light on the identity, behavior and function of senescent cells in vivo. The transient presence of senescent cells has an indispensable role in limiting lung damage and contributes to organ regenerative capacity upon acute stress insults. In contrast persistent accumulation of senescent cells is a driver of age-related decline in organ function. Here we discuss lung physiology and pathology as an example of seemingly contradictory role of senescence in structural and functional integrity of the tissue upon damage, and in age-related pulmonary diseases.
    Keywords:  aging; lung; regeneration; senescence
    DOI:  https://doi.org/10.1016/j.mad.2021.111550
  2. Mech Ageing Dev. 2021 Aug 02. pii: S0047-6374(21)00120-2. [Epub ahead of print]198 111548
    Impact of Senescent Cell Subtypes on Tissue Dysfunction and Repair: Importance and Research Questions.
    Utkarsh Tripathi, Avanish Misra, Tamar Tchkonia, James L Kirkland.
      Cellular senescence, first observed and defined through cell culture studies, is a cell fate associated with essentially permanent cell cycle arrest and that can be triggered by a variety of inducers. Emerging evidence suggests senescence is a dynamic process with diverse functional characteristics. Depending on the tissue, type of inducer, and time since induction, senescent cells can promote tissue repair and re-modeling, prevent tumor development, or contribute to age-related disorders and chronic diseases, including cancers. Senescent cell characteristics appear to depend on multiple factors and be influenced by the milieu and other senescent cells locally and at a distance. We review diverse phenotypes of senescent cells originating from different cell types, senescence inducers over time since induction of senescence, and across conditions and diseases. This background is essential to inform further understanding about senescent cell subtypes and will point towards rational senescence-modulating strategies for achieving therapeutic benefit.
    Keywords:  Cellular senescence; Deleterious senescent cell subtype; Helper senescent cell subtype; Senolytics
    DOI:  https://doi.org/10.1016/j.mad.2021.111548
  3. Cells. 2021 Jul 09. pii: 1740. [Epub ahead of print]10(7):
    The Emergence of Senescent Surface Biomarkers as Senotherapeutic Targets.
    Martina Rossi, Kotb Abdelmohsen.
      Senescence is linked to a wide range of age-associated diseases and physiological declines. Thus, senotherapeutics are emerging to suppress the detrimental effects of senescence either by senomorphics or senolytics. Senomorphics suppress the traits associated with senescence phenotypes, while senolytics aim to clear senescent cells by suppressing their survival and enhancing the apoptotic pathways. The main goal of these approaches is to suppress the proinflammatory senescence-associated secretory phenotype (SASP) and to promote the immune recognition and elimination of senescent cells. One increasingly attractive approach is the targeting of molecules or proteins specifically present on the surface of senescent cells. These proteins may play roles in the maintenance and survival of senescent cells and hence can be targeted for senolysis. In this review, we summarize the recent knowledge regarding senolysis with a focus on novel surface biomarkers of cellular senescence and discuss their emergence as senotherapeutic targets.
    Keywords:  senescence; senescent cell clearance; senolysis; senolytics; senostatic; senotherapeutics; senotherapy; surface proteins; surfaceome
    DOI:  https://doi.org/10.3390/cells10071740
  4. Int J Mol Sci. 2021 Jul 29. pii: 8149. [Epub ahead of print]22(15):
    mTOR Activity and Autophagy in Senescent Cells, a Complex Partnership.
    Angel Cayo, Raúl Segovia, Whitney Venturini, Rodrigo Moore-Carrasco, Claudio Valenzuela, Nelson Brown.
      Cellular senescence is a form of proliferative arrest triggered in response to a wide variety of stimuli and characterized by unique changes in cell morphology and function. Although unable to divide, senescent cells remain metabolically active and acquire the ability to produce and secrete bioactive molecules, some of which have recognized pro-inflammatory and/or pro-tumorigenic actions. As expected, this "senescence-associated secretory phenotype (SASP)" accounts for most of the non-cell-autonomous effects of senescent cells, which can be beneficial or detrimental for tissue homeostasis, depending on the context. It is now evident that many features linked to cellular senescence, including the SASP, reflect complex changes in the activities of mTOR and other metabolic pathways. Indeed, the available evidence indicates that mTOR-dependent signaling is required for the maintenance or implementation of different aspects of cellular senescence. Thus, depending on the cell type and biological context, inhibiting mTOR in cells undergoing senescence can reverse senescence, induce quiescence or cell death, or exacerbate some features of senescent cells while inhibiting others. Interestingly, autophagy-a highly regulated catabolic process-is also commonly upregulated in senescent cells. As mTOR activation leads to repression of autophagy in non-senescent cells (mTOR as an upstream regulator of autophagy), the upregulation of autophagy observed in senescent cells must take place in an mTOR-independent manner. Notably, there is evidence that autophagy provides free amino acids that feed the mTOR complex 1 (mTORC1), which in turn is required to initiate the synthesis of SASP components. Therefore, mTOR activation can follow the induction of autophagy in senescent cells (mTOR as a downstream effector of autophagy). These functional connections suggest the existence of autophagy regulatory pathways in senescent cells that differ from those activated in non-senescence contexts. We envision that untangling these functional connections will be key for the generation of combinatorial anti-cancer therapies involving pro-senescence drugs, mTOR inhibitors, and/or autophagy inhibitors.
    Keywords:  autophagy; mTOR; senescence
    DOI:  https://doi.org/10.3390/ijms22158149
  5. Front Immunol. 2021 ;12 706434
    The Role of T Cell Senescence in Neurological Diseases and Its Regulation by Cellular Metabolism.
    Johannes Fessler, Stefano Angiari.
      Immunosenescence is a state of dysregulated leukocyte function characterised by arrested cell cycle, telomere shortening, expression of markers of cellular stress, and secretion of pro-inflammatory mediators. Immunosenescence principally develops during aging, but it may also be induced in other pathological settings, such as chronic viral infections and autoimmune diseases. Appearance of senescent immune cells has been shown to potentially cause chronic inflammation and tissue damage, suggesting an important role for this process in organismal homeostasis. In particular, the presence of senescent T lymphocytes has been reported in neurological diseases, with some works pointing towards a direct connection between T cell senescence, inflammation and neuronal damage. In this minireview, we provide an overview on the role of T cell senescence in neurological disorders, in particular in multiple sclerosis and Alzheimer disease. We also discuss recent literature investigating how metabolic remodelling controls the development of a senescence phenotype in T cells. Targeting metabolic pathways involved in the induction of senescent T cells may indeed represent a novel approach to limit their inflammatory activity and prevent neuroinflammation and neurodegeneration.
    Keywords:  T cell; immunometabolism; immunosenescence; neurodegeneration; neuroinflammation
    DOI:  https://doi.org/10.3389/fimmu.2021.706434
  6. Aging Cell. 2021 Aug 06. e13447
    Ouabain and chloroquine trigger senolysis of BRAF-V600E-induced senescent cells by targeting autophagy.
    Valentin L'Hôte, Régis Courbeyrette, Guillaume Pinna, Jean-Christophe Cintrat, Gwenaëlle Le Pavec, Agnès Delaunay-Moisan, Carl Mann, Jean-Yves Thuret.
      The expression of BRAF-V600E triggers oncogene-induced senescence in normal cells and is implicated in the development of several cancers including melanoma. Here, we report that cardioglycosides such as ouabain are potent senolytics in BRAF senescence. Sensitization by ATP1A1 knockdown and protection by supplemental potassium showed that senolysis by ouabain was mediated by the Na,K-ATPase pump. Both ion transport inhibition and signal transduction result from cardioglycosides binding to Na,K-ATPase. An inhibitor of the pump that does not trigger signaling was not senolytic despite blocking ion transport, demonstrating that signal transduction is required for senolysis. Ouabain triggered the activation of Src, p38, Akt, and Erk in BRAF-senescent cells, and signaling inhibitors prevented cell death. The expression of BRAF-V600E increased ER stress and autophagy in BRAF-senescent cells and sensitized the cell to senolysis by ouabain. Ouabain inhibited autophagy flux, which was restored by signaling inhibitors. Consequently, we identified autophagy inhibitor chloroquine as a novel senolytic in BRAF senescence based on the mode of action of cardioglycosides. Our work underlies the interest of characterizing the mechanisms of senolytics to discover novel compounds and identifies the endoplasmic reticulum stress-autophagy tandem as a new vulnerability in BRAF senescence that can be exploited for the development of further senolytic strategies.
    Keywords:  Na,K-ATPase; Src; cardioglycosides; cellular senescence; endoplasmic reticulum stress; melanoma; senolytic
    DOI:  https://doi.org/10.1111/acel.13447
  7. Endocrinology. 2021 Aug 07. pii: bqab136. [Epub ahead of print]
    Role of Cellular Senescence in Type II Diabetes.
    Akilavalli Narasimhan, Rafael R Flores, Paul D Robbins, Laura J Niedernhofer.
      Cellular senescence is a cell fate that occurs in response to numerous types of stress and can promote tissue repair or drive inflammation and disruption of tissue homeostasis depending on the context. Aging and obesity lead to an increase in the senescent cell burden in multiple organs. Senescent cells release a myriad of senescence-associated secretory phenotype factors that directly mediate pancreatic β-cell dysfunction, adipose tissue dysfunction, and insulin resistance in peripheral tissues, which promote the onset of type II diabetes mellitus. In addition, hyperglycemia and metabolic changes seen in diabetes promote cellular senescence. Diabetes-induced cellular senescence contributes to various diabetic complications. Thus, T2D is both a cause and consequence of cellular senescence. This review summarizes recent studies on the link between aging, obesity, and diabetes, focusing on the role of cellular senescence in disease processes.
    Keywords:  Diabetes; aging; cellular senescence; inflammation; obesity; senotherapeutics
    DOI:  https://doi.org/10.1210/endocr/bqab136
  8. Mol Cancer Res. 2021 Aug 04. pii: molcanres.0284.2021. [Epub ahead of print]
    Monoallelic IDH1 R132H mutation mediates glioma cell response to anti-cancer therapies via induction of senescence.
    Daqian Zhan, Ding Ma, Shuang Wei, Bachchu Lal, Yi Fu, Charles Eberhart, John Laterra, Mingyao Ying, Yunqing Li, Alan Meeker, Hernando Lopez-Bertoni, Shuli Xia.
      Heterozygous IDH R132H mutation is an early event during gliomagenesis. Clinically, glioma patients carrying mutant IDH1 respond better to anti-tumor therapies. However, the mechanism by which IDH1 mutations contribute to gliomagenesis and therapeutic response remains elusive. Here we report that senescence is involved in the improved therapeutic responses of mutant IDH1 glioma cells. Knocking-in IDH1R132H/WT in glioma cells significantly enhanced glioma cell senescence in response to temozolomide and radiation via a DNA-damage mediated mechanism. We further asked if senescence plays a role in IDH1R132H/WT-induced gliomagenesis. Together with ATRX knockout and p53/RB loss, IDH1R132H/WT transformed non-neoplastic human astroglial cells to form tumors in mouse brains. In-depth characterization revealed that a subset of these pre-cancerous cells underwent senescence-like phenotypic changes, including flat and enlarged cell morphology, increased senescence marker expression, decreased cell proliferation, and cell cycle arrest at the G2/M phase. Mechanistic studies indicated that the combination of glioma driver genes (p53/RB/IDH1/ATRX) dramatically increased DNA damage and activated DNA damage response pathways ATR/ATR and Chk1/Chk2 in senescent cells. To determine how senescent cells drive tumor formation, we investigated non-cell-autonomous mechanisms such as senescence-associated secretory phenotype (SASP), a panel of pro-inflammatory and tissue-remodeling factors implicated in a tumor-permissive microenvironment. We found that astroglial cells carrying p53/RB/ATRX loss and IDH1R132H/WT upregulated key factors in SASP via an epigenetic-mediated mechanism. Our work suggests that drugs that specifically eliminate senescent cells could help kill pre-cancerous cells and senescent tumor cells following anti-tumor therapies. Implications: This work reveals senescence as a novel mechanism of IDH mutant-mediated biological impact and describes new therapeutic opportunities concerning IDH1 mutant gliomas.
    DOI:  https://doi.org/10.1158/1541-7786.MCR-21-0284
  9. Biochim Biophys Acta Mol Basis Dis. 2021 Jul 30. pii: S0925-4439(21)00166-6. [Epub ahead of print] 166233
    Deficiency of Heat shock factor 4 promotes lens epithelial cell senescence through upregulating p21cip1 expression.
    Xiukun Cui, Chunxiao Du, Simin Wan, Dandan Wu, Longjun Yan, Jing Zhang, Jing Li, Hui Li, Zhengyan Yang, Hailong Zhang, Jun Zhang, Hongmei Mu, Fengyan Zhang, Xuyan Peng, Mugen Liu, Yanzhong Hu.
      Genetic mutations in heat shock factor 4 (Hsf4) is associated with both congenital and age-related cataracts. Hsf4 regulates lens development through its ability to both activate and inhibit transcription. Previous studies suggested Hsf4 is involved in modulating cellular senescence depending on p21cip1 and p27 kip1 expression in MEF cells. Here, we found that Hsf4 acts as a suppressor of p21cip1 expression and plays an anti-senescence role during lens development. Knocking out Hsf4 facilitated UVB-induced cellular senescence in mouse lens epithelial cells (mLECs). p21cip1 was upregulated at both the mRNA and protein levels in HSF4-/- mLECs under control and UVB-treated conditions, and knockdown of p21cip1 by siRNA alleviated UVB-induced cellular senescence. HSF4 directly bound to the p21cip1 promoter and increased H3K27m3 levels at the p21cip1 proximal promoter region by recruiting the methyltransferase EZH2. In animal models, p21cip1 was gradually upregulated in wild-type mouse lenses with increasing age, while Hsf4 levels decreased. We generated a Hsf4 mutant mice line (Hsf4del-42) which displayed obvious congenital cataract phenotype. The expression of p21cip1 and senescence-associated cytokines were induced in the cataractous lenses of Hsf4del-42 mice. H3K27m3 and EZH2 levels decreased in p21cip1 promoters in the lenses of Hsf4del-42 mice. The SA-β-Gal activities was positive in lens epithelia of aged Hsf4null zebrafish compared to wild-type lenses. p21cip1 and senescence-associated cytokines levels were also upregulated in lenses of Hsf4null zebrafish. Accordingly, we propose that HSF4 plays a protective role in lens epithelial cells against cellular senescence during lens development and aging, partly by fine-tuning p21cip1 expression.
    Keywords:  H3K27m3; HSF4; cellular senescence; ocular lens; p21(cip1); transcription
    DOI:  https://doi.org/10.1016/j.bbadis.2021.166233
  10. Exp Physiol. 2021 Aug 01.
    Extracellular vesicles released from stress-induced premature senescent myoblasts impair endothelial function and proliferation.
    Zachary R Hettinger, Christopher K Kargl, Jonathan H Shannahan, Shihuan Kuang, Timothy P Gavin.
       NEW FINDINGS: What is the central question of this study? What is the impact of stress-induced premature senescence on skeletal muscle myoblast-derived extracellular vesicles and myoblast-endothelial cell crosstalk? What is the main finding and its importance? Hydrogen peroxide treatment of human myoblasts induced stress-induced premature senescence (SIPS) and increased the release of exosome-sized extracellular vesicles (30-150 nm in size) 5-fold compared to untreated controls. Treatment of SIPS myoblast-derived EVs on endothelial cells increased senescent markers and decreased proliferation. Gene expression analysis of SIPS myoblast-derived EVs revealed a 4-fold increase in senescent factor transforming growth factor-β. These results highlight potential mechanisms by which senescence imparts deleterious effects on the cellular microenvironment.
    ABSTRACT: Cellular senescence contributes to numerous diseases through the release of pro-inflammatory factors as part of the senescence-associated secretory phenotype (SASP). In skeletal muscle, resident muscle progenitor cells (satellite cells) express markers of senescence with advancing age and in response to various pathologies, which contributes to reduced regenerative capacities in vitro. Satellite cells regulate their microenvironment in part through the release of extracellular vesicles (EVs), but the effect of senescence on EV signaling is unknown. Primary human myoblasts were isolated following biopsies of the vastus lateralis from young healthy subjects. Hydrogen peroxide (H2 O2 ) treatment was used to achieve stress-induced premature senescence (SIPS) of myoblasts. Extracellular vesicles secreted by myoblasts with and without H2 O2 treatment were isolated, analyzed, and used to treat human umbilical vein endothelial cells (HUVECs) to assess senescent and angiogenic impact. H2 O2 treatment of primary human myoblasts in vitro increased markers of senescence (β-Galactosidase and p21Cip1 ), decreased proliferation, and increased exosome-like EV (30-150 nm) release approximately 5-fold. In HUVECs, EV treatment from H2 O2 treated myoblasts increased markers of senescence (β-Galactosidase and TGF-β), decreased proliferation, and impaired HUVEC tube formation. Analysis of H2 O2 treated myoblast-derived EV mRNA revealed a nearly 4-fold increase in TGF-β expression. Our novel results highlight the impact of SIPS on myoblast communication and identify a VasoMyo Crosstalk (VMC) by which SIPS myoblast-derived EVs impair endothelial cell function in vitro. This article is protected by copyright. All rights reserved.
    Keywords:  aging; angiogenesis; endothelial cells; extracellular vesicles; satellite cells; senescence
    DOI:  https://doi.org/10.1113/EP089423
  11. Int J Mol Sci. 2021 Jul 26. pii: 7945. [Epub ahead of print]22(15):
    Chronological Age Affects MSC Senescence In Vitro-A Systematic Review.
    Konstantinos Kapetanos, Dimitrios Asimakopoulos, Neophytos Christodoulou, Antonia Vogt, Wasim Khan.
      The use of mesenchymal stromal cells (MSCs) in regenerative medicine and tissue engineering is well established, given their properties of self-renewal and differentiation. However, several studies have shown that these properties diminish with age, and understanding the pathways involved are important to provide regenerative therapies in an ageing population. In this PRISMA systematic review, we investigated the effects of chronological donor ageing on the senescence of MSCs. We identified 3023 studies after searching four databases including PubMed, Web of Science, Cochrane, and Medline. Nine studies met the inclusion and exclusion criteria and were included in the final analyses. These studies showed an increase in the expression of p21, p53, p16, ROS, and NF-κB with chronological age. This implies an activated DNA damage response (DDR), as well as increased levels of stress and inflammation in the MSCs of older donors. Additionally, highlighting the effects of an activated DDR in cells from older donors, a decrease in the expression of proliferative markers including Ki67, MAPK pathway elements, and Wnt/β-catenin pathway elements was observed. Furthermore, we found an increase in the levels of SA-β-galactosidase, a specific marker of cellular senescence. Together, these findings support an association between chronological age and MSC senescence. The precise threshold for chronological age where the reported changes become significant is yet to be defined and should form the basis for further scientific investigations. The outcomes of this review should direct further investigations into reversing the biological effects of chronological age on the MSC senescence phenotype.
    Keywords:  ageing; biomarkers; human; mesenchymal stromal cells; senescence; systematic review
    DOI:  https://doi.org/10.3390/ijms22157945
  12. Aging Cell. 2021 Aug 06. e13440
    Aging and neuroinflammation: Changes in immune cell responses, axon integrity, and motor function in a viral model of progressive multiple sclerosis.
    Leyre Mestre, Graciela Alonso, Ana Feliú, Miriam Mecha, Carolina Martín, Luisa M Villar, Carmen Guaza.
      Although aggravated multiple sclerosis (MS) disability has been reported in aged patients, the aging impact on immune cells remodeling within the CNS is not well understood. Here, we investigated the influence of aging on immune cells and the neuroinflammatory and neurodegenerative processes that occur in a well-established viral model of progressive MS. We found an anomalous presence of CD4+ T, CD8+ T, B cells, and cells of myeloid lineage in the CNS of old sham mice whereas a blunted cellular innate and adaptive immune response was observed in Theiler's murine encephalomyelitis virus (TMEV) infected old mice. Microglia and macrophages show opposite CNS viral responses regarding cell counts in the old mice. Furthermore, enhanced expression of Programmed Death-ligand 1 (PD-L1) was found in microglia isolated from old TMEV-infected mice and not in isolated CNS macrophages. Immunocytochemical staining of microglial cells confirms the above differences between young and old mice. Age-related axonal loss integrity in the mouse spinal cord was found in TMEV mice, but a less marked neurodegenerative process was present in old sham mice compared with young sham mice. TMEV and sham old mice also display alterations in innate and adaptive immunity in the spleen compared to the young mice. Our study supports the need of new or adapted pharmacological strategies for MS elderly patients.
    Keywords:  Theiler's virus; aging; cellular innate and adaptive immunity; neuroinflammation; progressive multiple sclerosis
    DOI:  https://doi.org/10.1111/acel.13440
  13. NPJ Aging Mech Dis. 2021 Aug 02. 7(1): 18
    Klotho inhibits neuronal senescence in human brain organoids.
    Mohammed R Shaker, Julio Aguado, Harman Kaur Chaggar, Ernst J Wolvetang.
      Aging is a major risk factor for many neurodegenerative diseases. Klotho (KL) is a glycosylated transmembrane protein that is expressed in the choroid plexus and neurons of the brain. KL exerts potent anti-aging effects on multiple cell types in the body but its role in human brain cells remains largely unclear. Here we show that human cortical neurons, derived from human pluripotent stem cells in 2D cultures or in cortical organoids, develop the typical hallmarks of senescent cells when maintained in vitro for prolonged periods of time, and that moderate upregulation or repression of endogenous KL expression in cortical organoids inhibits and accelerates senescence, respectively. We further demonstrate that KL expression alters the expression of senescence-associated genes including, extracellular matrix genes, and proteoglycans, and can act in a paracrine fashion to inhibit neuronal senescence. In summary, our results establish an important role for KL in the regulation of human neuronal senescence and offer new mechanistic insight into its role in human brain aging.
    DOI:  https://doi.org/10.1038/s41514-021-00070-x
  14. Cells. 2021 Jul 05. pii: 1694. [Epub ahead of print]10(7):
    Alpha-Synuclein Preformed Fibrils Induce Cellular Senescence in Parkinson's Disease Models.
    Dinesh Kumar Verma, Bo Am Seo, Anurupa Ghosh, Shi-Xun Ma, Karina Hernandez-Quijada, Julie K Andersen, Han Seok Ko, Yong-Hwan Kim.
      Emerging evidence indicates that cellular senescence could be a critical inducing factor for aging-associated neurodegenerative disorders. However, the involvement of cellular senescence remains unclear in Parkinson's disease (PD). To determine this, we assessed the effects of α-synuclein preformed fibrils (α-syn PFF) or 1-methyl-4-phenylpyridinium (MPP+) on changes in cellular senescence markers, employing α-syn PFF treated-dopaminergic N27 cells, primary cortical neurons, astrocytes and microglia and α-syn PFF-injected mouse brain tissues, as well as human PD patient brains. Our results demonstrate that α-syn PFF-induced toxicity reduces the levels of Lamin B1 and HMGB1, both established markers of cellular senescence, in correlation with an increase in the levels of p21, a cell cycle-arrester and senescence marker, in both reactive astrocytes and microglia in mouse brains. Using Western blot and immunohistochemistry, we found these cellular senescence markers in reactive astrocytes as indicated by enlarged cell bodies within GFAP-positive cells and Iba1-positive activated microglia in α-syn PFF injected mouse brains. These results indicate that PFF-induced pathology could lead to astrocyte and/or microglia senescence in PD brains, which may contribute to neuropathology in this model. Targeting senescent cells using senolytics could therefore constitute a viable therapeutic option for the treatment of PD.
    Keywords:  HMGB1; Lamin B1; SATB1; alpha-synuclein preformed fibrils; cellular senescence; microglia activation; p21; reactive astrocytes
    DOI:  https://doi.org/10.3390/cells10071694
  15. Cell Prolif. 2021 Aug 03. e13107
    Curcumol inhibits ferritinophagy to restrain hepatocyte senescence through YAP/NCOA4 in non-alcoholic fatty liver disease.
    Xiaoyu Qi, Anping Song, Mingyue Ma, Peipei Wang, Xinbei Zhang, Chunfeng Lu, Junxiu Zhang, Shuguo Zheng, Huanhuan Jin.
       OBJECTIVES: In recent years, cellular senescence has attracted a lot of interest in researchers due to its involvement in non-alcoholic fatty liver disease (NAFLD). However, the mechanism of cellular senescence is not clear. The purpose of this study was to investigate the effect of curcumol on hepatocyte senescence in NAFLD and the molecular mechanisms implicated.
    MATERIALS AND METHODS: LVG Golden Syrian hamsters, C57BL/6J mice and human hepatocyte cell line LO2 were used. Cellular senescence was assessed by analyses of senescence marker SA-β-gal, p16 and p21, H3K9me3, γ-H2AX and telomerase activity.
    RESULTS: The results showed that curcumol could inhibit hepatocyte senescence in both in vivo and in vitro NAFLD models, and the mechanism might be related to its regulation of ferritinophagy and subsequent alleviation of iron overload. Moreover, overexpression of nuclear receptor coactivator 4 (NCOA4) weakened the effect of curcumol on ferritinophagy-mediated iron overload and cellular senescence. Furthermore, we demonstrated that curcumol reduced the expression of NCOA4 by Yes-associated protein (YAP). In addition, depression of YAP could impair the effect of curcumol on iron overload and cellular senescence.
    CONCLUSION: Our results clarified the mechanism of curcumol inhibition of hepatocyte senescence through YAP/NCOA4 regulation of ferritinophagy in NAFLD. These findings provided a promising option of curcumol to regulate cellular senescence by target YAP/NCOA4 for the treatment of NAFLD.
    Keywords:  Yes-associated protein; cellular senescence; curcumol; ferritinophagy; iron overload; non-alcoholic fatty liver disease; nuclear receptor coactivator 4
    DOI:  https://doi.org/10.1111/cpr.13107
  16. Angiogenesis. 2021 Aug 03.
    CCM2-deficient endothelial cells undergo a ROCK-dependent reprogramming into senescence-associated secretory phenotype.
    Daphné Raphaëlle Vannier, Apeksha Shapeti, Florent Chuffart, Emmanuelle Planus, Sandra Manet, Paul Rivier, Olivier Destaing, Corinne Albiges-Rizo, Hans Van Oosterwyck, Eva Faurobert.
      Cerebral cavernous malformation (CCM) is a cerebrovascular disease in which stacks of dilated haemorrhagic capillaries form focally in the brain. Whether and how defective mechanotransduction, cellular mosaicism and inflammation interplay to sustain the progression of CCM disease is unknown. Here, we reveal that CCM1- and CCM2-silenced endothelial cells expanded in vitro enter into senescence-associated secretory phenotype (SASP) that they use to invade the extracellular matrix and attract surrounding wild-type endothelial and immune cells. Further, we demonstrate that this SASP is driven by the cytoskeletal, molecular and transcriptomic disorders provoked by ROCK dysfunctions. By this, we propose that CCM2 and ROCK could be parts of a scaffold controlling senescence, bringing new insights into the emerging field of the control of ageing by cellular mechanics. These in vitro findings reconcile the known dysregulated traits of CCM2-deficient endothelial cells into a unique endothelial fate. Based on these in vitro results, we propose that a SASP could link the increased ROCK-dependent cell contractility in CCM2-deficient endothelial cells with microenvironment remodelling and long-range chemo-attraction of endothelial and immune cells.
    Keywords:  Cerebral cavernous malformations; Mechanotransduction; Microenvironment remodeling; ROCK; Senescence associated secretory phenotype
    DOI:  https://doi.org/10.1007/s10456-021-09809-2
  17. Aging Cell. 2021 Aug 02. e13438
    Aging influences the cardiac macrophage phenotype and function during steady state and during inflammation.
    Noushin Saljoughian Esfahani, Qian Wu, Naresh Kumar, Latha Prabha Ganesan, William P Lafuse, Murugesan V S Rajaram.
      Aging-mediated immune dysregulation affects the normal cardiac immune cell phenotypes and functions, resulting in cardiac distress. During cardiac inflammation, immune activation is critical for mounting the regenerative responses to maintain normal heart function. We investigated the impact of aging on myeloid cell phenotype and function during cardiac inflammation induced by a sub-lethal dose of LPS. Our data show that hearts of old mice contain more myeloid cells than the hearts of young mice. However, while the number of monocytic-derived suppressor cells did not differ between young and old mice, monocytic-derived suppressor cells from old mice were less able to suppress T-cell proliferation. Since cardiac resident macrophages (CRMs) are important for immune surveillance, clearance of dead cells, and tissue repair, we focused our studies on CRMs phenotype and function during steady state and LPS treatment. In the steady state, we observed significantly more MHC-IIlow and MHC-IIhigh CRMs in the hearts of old mice; however, these populations were decreased in both young and aged mice upon LPS treatment and the decrease in CRM populations correlated with defects in cardiac electrical activity. Notably, mice treated with a liver X receptor (LXR) agonist showed an increase in MerTK expression in CRMs of both young and old mice, which resulted in the reversal of cardiac electrical dysfunction caused by lipopolysaccharide (LPS). We conclude that aging alters the phenotype of CRMs, which contributes to the dysregulation of cardiac electrical dysfunction during infection in aged mice.
    Keywords:  aging; cardiac macrophages; infection and inflammation
    DOI:  https://doi.org/10.1111/acel.13438
  18. BMC Geriatr. 2021 08 04. 21(1): 452
    Age-related changes of human serum Sirtuin6 in adults.
    Ying Zhao, Xiangli Bai, Xiong Jia, Yajing Lu, Wenzhuo Cheng, Meng Shu, Yan Zhu, Lin Zhu, Li Wang, Yan Shu, Yi Song, Si Jin.
       BACKGROUND: Aging is a natural life process and with an aging population, age-related diseases (e.g. type 2 diabetes mellitus (T2DM), atherosclerosis-based cardiovascular diseases) are the primary mortality cause in older adults. Telomerase is often used as an aging biomarker. Detection and characterization of novel biomarkers can help in a more specific and sensitive identification of a person's aging status. Also, this could help in age-related diseases early prevent, ultimately prolonging the population's life span. Sirtuin 6 (Sirt6) - a member of the Sirtuins NAD+-dependent histone deacetylases family - is mainly intracellularly expressed, and is reported to be involved in the regulation of aging and aging-related diseases. Whether serum Sirt6 is correlated with aging and could be used as an aging biomarker is unknown. In the present study, we aimed to investigate the age-related Sirt6 changes in the serum of human adults.
    METHODS: Participants were divided into three groups according to age: 20-30 years (Young); 45-55 years (Middle-aged); and ≥ 70 years (Old). The Sirt6 and telomerase serum concentrations were determined by ELISA. The Sirt6 and human telomerase reverse transcriptase (hTERT) expression in vessels from amputated human lower limbs were analyzed using real-time quantitative PCR (RT-qPCR) and immunohistochemical staining. The relationships between variables were evaluated by Pearson correlation analysis.
    RESULTS: The Sirt6 and telomerase serum levels reduced with an increase in age. A similar tendency was observed for Sirt6 and hTERT in the vessel. Serum levels of Sirt6 were higher in females compared with males. Pearson's regression analysis revealed that the Sirt6 serum level positively correlated with telomerase (r = 0.5743) and both were significantly negatively correlated with age (r = - 0.5830 and r = - 0.5993, respectively).
    CONCLUSIONS: We reported a negative correlation between serum Sirt6 concentration and aging in human beings. Therefore, the Sirt6 serum level is a potential sex-specific aging marker.
    Keywords:  Aging; Biomarker; Sirt6; Telomerase
    DOI:  https://doi.org/10.1186/s12877-021-02399-0
  19. Aging Cell. 2021 Aug 04. e13441
    Youthful and age-related matreotypes predict drugs promoting longevity.
    Cyril Statzer, Elisabeth Jongsma, Sean X Liu, Alexander Dakhovnik, Franziska Wandrey, Pavlo Mozharovskyi, Fred Zülli, Collin Y Ewald.
      The identification and validation of drugs that promote health during aging ("geroprotectors") are key to the retardation or prevention of chronic age-related diseases. Here, we found that most of the established pro-longevity compounds shown to extend lifespan in model organisms also alter extracellular matrix gene expression (i.e., matrisome) in human cell lines. To harness this observation, we used age-stratified human transcriptomes to define the age-related matreotype, which represents the matrisome gene expression pattern associated with age. Using a "youthful" matreotype, we screened in silico for geroprotective drug candidates. To validate drug candidates, we developed a novel tool using prolonged collagen expression as a non-invasive and in-vivo surrogate marker for Caenorhabditis elegans longevity. With this reporter, we were able to eliminate false-positive drug candidates and determine the appropriate dose for extending the lifespan of C. elegans. We improved drug uptake for one of our predicted compounds, genistein, and reconciled previous contradictory reports of its effects on longevity. We identified and validated new compounds, tretinoin, chondroitin sulfate, and hyaluronic acid, for their ability to restore age-related decline of collagen homeostasis and increase lifespan. Thus, our innovative drug screening approach-employing extracellular matrix homeostasis-facilitates the discovery of pharmacological interventions promoting healthy aging.
    Keywords:  CMap; GTEx; aging; collagen; drug repurposing; extracellular matrix; geroprotector; longevity; matrisome; pharmacology
    DOI:  https://doi.org/10.1111/acel.13441
  20. Molecules. 2021 Jul 31. pii: 4666. [Epub ahead of print]26(15):
    Role of Melatonin in Angiotensin and Aging.
    Ahmet Ozer Sehirli, Serkan Sayıner, Ugochukwu Chukwunyere, Nedime Serakinci.
      The cellular utilization of oxygen leads to the generation of free radicals in organisms. The accumulation of these free radicals contributes significantly to aging and several age-related diseases. Angiotensin II can contribute to DNA damage through oxidative stress by activating the NAD(P)H oxidase pathway, which in turn results in the production of reactive oxygen species. This radical oxygen-containing molecule has been linked to aging and several age-related disorders, including renal damage. Considering the role of angiotensin in aging, melatonin might relieve angiotensin-II-induced stress by enhancing the mitochondrial calcium uptake 1 pathway, which is crucial in preventing the mitochondrial calcium overload that may trigger increased production of reactive oxygen species and oxidative stress. This review highlights the role and importance of melatonin together with angiotensin in aging and age-related diseases.
    Keywords:  aging; angiotensin; inflammation; melatonin; oxidative stress
    DOI:  https://doi.org/10.3390/molecules26154666
  21. Sci Rep. 2021 Aug 03. 11(1): 15752
    Acute ischemic stroke triggers a cellular senescence-associated secretory phenotype.
    Coral Torres-Querol, Pascual Torres, Noemí Vidal, Manel Portero-Otín, Gloria Arque, Francisco Purroy.
      Senescent cells are capable of expressing a myriad of inflammatory cytokines and this pro-inflammatory phenomenon is known as senescence-associated secretory phenotype (SASP). The contribution of this phenomenon in brain ischemia was scarce. A mouse model of transient focal cerebral ischemia by compressing the distal middle cerebral artery (tMCAo) for 60 min was used. SASP, pro-inflammatory cytokines and cell cycle mRNAs levels were quantified at 30-min and 72 h post-surgery. Immunohistochemistry in paraffin embedded human brain slides and mouse brain tissue was performed. Our results showed an increase of both p16 and p21 mRNA restricted to the infarct area in the tMCAo brain. Moreover, there was an induction of Il6, Tnfa, Cxc11, and its receptor Cxcr2 mRNA pro-inflammatory cytokines with a high positive correlation with p16/p21 mRNA levels. The p16 was mainly shown in cytoplasm of neurons and cytoplasm/membrane of microglial cells. The p21 was observed in membrane of neurons and also it showed a mixed cytoplasmic and membranous pattern in the microglial cells. In a human stroke patient, an increase of P16 in the perimeter of the MCA infarct area was observed. These suggest a role of SASP in tMCAo mouse model and in human brain tissue. SASP potentially has a physiological role in acute ischemic stroke and neurological function loss.
    DOI:  https://doi.org/10.1038/s41598-021-95344-5
  22. Aging Dis. 2021 Aug;12(5): 1150-1161
    Premature Senescence of T-cells Favors Bone Loss During Osteolytic Diseases. A New Concern in the Osteoimmunology Arena.
    Luis González-Osuna, Alfredo Sierra-Cristancho, Carolina Rojas, Emilio A Cafferata, Samanta Melgar-Rodríguez, Angélica M Cárdenas, Rolando Vernal.
      Cellular senescence is a biological process triggered in response to time-accumulated DNA damage, which prioritizes cell survival over cell function. Particularly, senescent T lymphocytes can be generated prematurely during chronic inflammatory diseases regardless of chronological aging. These senescent T lymphocytes are characterized by the loss of CD28 expression, a co-stimulatory receptor that mediates antigen presentation and effective T-cell activation. An increased number of premature senescent CD4+CD28- T lymphocytes has been frequently observed in osteolytic diseases, including rheumatoid arthritis, juvenile idiopathic arthritis, ankylosing spondylitis, osteopenia, osteoporosis, and osteomyelitis. Indeed, CD4+CD28- T lymphocytes produce higher levels of osteoclastogenic molecular mediators directly related to pathologic bone loss, such as tumor necrosis factor (TNF)-α, interleukin (IL)-17A, and receptor-activator of nuclear factor κB ligand (RANKL), as compared with regular CD4+CD28+ T lymphocytes. In addition, premature senescent CD8+CD28- T lymphocytes have been negatively associated with bone healing and regeneration by inhibiting osteoblast differentiation and mesenchymal stromal cell survival. Therefore, accumulated evidence supports the role of senescent T lymphocytes in osteoimmunology. Moreover, premature senescence of T-cells seems to be associated with the functional imbalance between the osteolytic T-helper type-17 (Th17) and bone protective T regulatory (Treg) lymphocytes, as well as the phenotypic instability of Treg lymphocytes responsible for its trans-differentiation into RANKL-producing exFoxp3Th17 cells, a key cellular phenomenon directly related to bone loss. Herein, we present a framework for the understanding of the pathogenic characteristics of T lymphocytes with a premature senescent phenotype; and particularly, we revise and discuss their role in the osteoimmunology of osteolytic diseases.
    Keywords:  CD28; RANKL; T-lymphocytes; bone loss; osteoimmunology; senescence
    DOI:  https://doi.org/10.14336/AD.2021.0110
  23. Int J Mol Sci. 2021 Jul 29. pii: 8166. [Epub ahead of print]22(15):
    Leukemia-Induced Cellular Senescence and Stemness Alterations in Mesenchymal Stem Cells Are Reversible upon Withdrawal of B-Cell Acute Lymphoblastic Leukemia Cells.
    Natalia-Del Pilar Vanegas, Paola Fernanda Ruiz-Aparicio, Gloria Inés Uribe, Adriana Linares-Ballesteros, Jean-Paul Vernot.
      Leukemic cell growth in the bone marrow (BM) induces a very stressful condition. Mesenchymal stem cells (MSC), a key component of this BM niche, are affected in several ways with unfavorable consequences on hematopoietic stem cells favoring leukemic cells. These alterations in MSC during B-cell acute lymphoblastic leukemia (B-ALL) have not been fully studied. In this work, we have compared the modifications that occur in an in vitro leukemic niche (LN) with those observed in MSC isolated from B-ALL patients. MSC in this LN niche showed features of a senescence process, i.e., altered morphology, increased senescence-associated β-Galactosidase (SA-βGAL) activity, and upregulation of p53 and p21 (without p16 expression), cell-cycle arrest, reduced clonogenicity, and some moderated changes in stemness properties. Importantly, almost all of these features were found in MSC isolated from B-ALL patients. These alterations rendered B-ALL cells susceptible to the chemotherapeutic agent dexamethasone. The senescent process seems to be transient since when leukemic cells are removed, normal MSC morphology is re-established, SA-βGAL expression is diminished, and MSC are capable of re-entering cell cycle. In addition, few cells showed low γH2AX phosphorylation that was reduced to basal levels upon cultivation. The reversibility of the senescent process in MSC must impinge important biological and clinical significance depending on cell interactions in the bone marrow at different stages of disease progression in B-ALL.
    Keywords:  B-cell acute lymphoblastic leukemia (B-ALL); bone marrow microenvironment; leukemic niche (LN); mesenchymal stem cells (MSC); reversible senescence; senescence
    DOI:  https://doi.org/10.3390/ijms22158166
  24. Sci Rep. 2021 Aug 04. 11(1): 15783
    Higher senescence associated secretory phenotype and lower defense mediator in urinary extracellular vesicles of elders with and without Parkinson disease.
    Shu-Hui Yeh, Chia-Hsueh Lin, Yun-Jung Yang, Li-Wei Lin, Chih-Wen Tseng, Kuender D Yang.
      Youth fountain and aging culprits are usually sought and identified in blood but not urine. Extracellular vesicles (EVs) possess parental cell properties, circulate in blood, CSF and urine, and provide paracrine and remote cell-cell communication messengers. This study investigated whether senescence-associated secretory phenotype (SASP) and immune defense factors in EVs of urine could serve as biomarkers in elderly individuals with and without a comorbidity. Urine samples from young adults and elderly individuals with and without Parkinson disease (PD) were collected and stored at - 80 °C until studies. Urine EVs were separated from a drop-through solution and confirmed by verifying CD9, CD63, CD81 and syntenin expression. The EVs and drop-through solution were subjected to measurement of SASP cytokines and defense factors by Milliplex array assays. Many SASP cytokines and defense factors could be detected in urinary EVs but not urinary solutions. Elderly individuals (age > 60) had significantly higher levels of the SASP-associated factors IL-8, IP-10, GRO, and MCP-1 in EVs (p < 0.05). In contrast, some defense factors, IL-4, MDC and IFNα2 in EVs had significantly lower levels in elderly adults than in young adults (age < 30). Patients with and without PD exhibited a similar SASP profile in EVs but significantly lower levels of IL-10 in the EVs from patients with PD. This study used a simple device to separate urinary EVs from solution for comparisons of SASP and defense mediators between young adults and elders with and without PD. Results from this study indicate that aging signature is present in EVs circulating to urine and the signatures include higher inflammatory mediators and lower defense factors in urinary EVs but not solutions, suggesting a simple method to separate urinary EVs from solutions for searching aging mechanistic biomarkers may make prediction of aging and monitoring of anti-senolytic interventions possible.
    DOI:  https://doi.org/10.1038/s41598-021-95062-y
  25. Nature. 2021 Aug;596(7870): 43-53
    The role of retrotransposable elements in ageing and age-associated diseases.
    Vera Gorbunova, Andrei Seluanov, Paolo Mita, Wilson McKerrow, David Fenyö, Jef D Boeke, Sara B Linker, Fred H Gage, Jill A Kreiling, Anna P Petrashen, Trenton A Woodham, Jackson R Taylor, Stephen L Helfand, John M Sedivy.
      The genomes of virtually all organisms contain repetitive sequences that are generated by the activity of transposable elements (transposons). Transposons are mobile genetic elements that can move from one genomic location to another; in this process, they amplify and increase their presence in genomes, sometimes to very high copy numbers. In this Review we discuss new evidence and ideas that the activity of retrotransposons, a major subgroup of transposons overall, influences and even promotes the process of ageing and age-related diseases in complex metazoan organisms, including humans. Retrotransposons have been coevolving with their host genomes since the dawn of life. This relationship has been largely competitive, and transposons have earned epithets such as 'junk DNA' and 'molecular parasites'. Much of our knowledge of the evolution of retrotransposons reflects their activity in the germline and is evident from genome sequence data. Recent research has provided a wealth of information on the activity of retrotransposons in somatic tissues during an individual lifespan, the molecular mechanisms that underlie this activity, and the manner in which these processes intersect with our own physiology, health and well-being.
    DOI:  https://doi.org/10.1038/s41586-021-03542-y
  26. Elife. 2021 Aug 03. pii: e59828. [Epub ahead of print]10
    Instability in NAD+ metabolism leads to impaired cardiac mitochondrial function and communication.
    Knut H Lauritzen, Maria Belland Olsen, Mohammed Shakil Ahmed, Kuan Yang, Johanne Egge Rinholm, Linda H Bergersen, Qin Ying Esbensen, Lars Jansen Sverkeli, Mathias Ziegler, Håvard Attramadal, Bente Halvorsen, Pål Aukrust, Arne Yndestad.
      Poly(ADP-ribose) polymerase (PARP) enzymes initiate (mt)DNA repair mechanisms and use nicotinamide adenine dinucleotide (NAD+) as energy source. Prolonged PARP activity can drain cellular NAD+ reserves, leading to de-regulation of important molecular processes. Here, we provide evidence of a pathophysiological mechanism that connects mtDNA damage to cardiac dysfunction via reduced NAD+ levels and loss of mitochondrial function and communication. Using a transgenic model, we demonstrate that high levels of mice cardiomyocyte mtDNA damage cause a reduction in NAD+ levels due to extreme DNA repair activity, causing impaired activation of NAD+-dependent SIRT3. In addition, we show that myocardial mtDNA damage in combination with high dosages of nicotinamideriboside (NR) causes an inhibition of sirtuin activity due to accumulation of nicotinamide (NAM), in addition to irregular cardiac mitochondrial morphology. Consequently, high doses of NR should be used with caution, especially when cardiomyopathic symptoms are caused by mitochondrial dysfunction and instability of mtDNA.
    Keywords:  DNA repair; NAD+; SIRT3; biochemistry; cardiovascular disease; chemical biology; human; mitochondrial dna; mouse; nicotinamide riboside
    DOI:  https://doi.org/10.7554/eLife.59828
  27. Oxid Med Cell Longev. 2021 ;2021 9932218
    Effects and Mechanisms of Resveratrol on Aging and Age-Related Diseases.
    Dan-Dan Zhou, Min Luo, Si-Yu Huang, Adila Saimaiti, Ao Shang, Ren-You Gan, Hua-Bin Li.
      The aging of population has become an issue of great concern because of its rapid increase. Aging is an important risk factor of many chronic diseases. Resveratrol could be found in many foods, such as grapes, red wine, peanuts, and blueberries. Many studies reported that resveratrol possessed various bioactivities, such as antioxidant, anti-inflammatory, cardiovascular protection, anticancer, antidiabetes mellitus, antiobesity, neuroprotection, and antiaging effects. The antiaging mechanisms of resveratrol were mainly ameliorating oxidative stress, relieving inflammatory reaction, improving mitochondrial function, and regulating apoptosis. Resveratrol could be an effective and safe compound for the prevention and treatment of aging and age-related diseases. In this review, we summarize the effects of resveratrol on aging, life extension, and several age-related diseases, with special attention paid to the mechanisms of antiaging action.
    DOI:  https://doi.org/10.1155/2021/9932218
  28. Aging Dis. 2021 Aug;12(5): 1304-1322
    tRNA-derived fragments as New Hallmarks of Aging and Age-related Diseases.
    Ya Yuan, Jiamei Li, Zhi He, Xiaolan Fan, Xueping Mao, Mingyao Yang, Deying Yang.
      tRNA-derived fragments (tRFs), which are non-coding RNAs produced via tRNA cleavage with lengths of 14 to 50 nucleotides, originate from precursor tRNAs or mature tRNAs and exist in a wide range of organisms. tRFs are produced not by random fracture of tRNAs but by specific mechanisms. Considerable evidence shows that tRFs are detectable in model organisms of different ages and are associated with age-related diseases in humans, such as cancer and neurodegenerative diseases. In this literature review, the origin and classification of tRFs and the regulatory mechanisms of tRFs in aging and age-related diseases are summarized. We also describe the available tRF databases and research techniques and lay a foundation for the exploration of tRFs as biomarkers for the diagnosis and treatment of aging and age-related diseases.
    Keywords:  age-related diseases; aging; regulation mechanisms; tRFs
    DOI:  https://doi.org/10.14336/AD.2021.0115
  29. Molecules. 2021 Jul 27. pii: 4533. [Epub ahead of print]26(15):
    An Overview of NO Signaling Pathways in Aging.
    Ali Mohammad Pourbagher-Shahri, Tahereh Farkhondeh, Marjan Talebi, Dalia M Kopustinskiene, Saeed Samarghandian, Jurga Bernatoniene.
      Nitric Oxide (NO) is a potent signaling molecule involved in the regulation of various cellular mechanisms and pathways under normal and pathological conditions. NO production, its effects, and its efficacy, are extremely sensitive to aging-related changes in the cells. Herein, we review the mechanisms of NO signaling in the cardiovascular system, central nervous system (CNS), reproduction system, as well as its effects on skin, kidneys, thyroid, muscles, and on the immune system during aging. The aging-related decline in NO levels and bioavailability is also discussed in this review. The decreased NO production by endothelial nitric oxide synthase (eNOS) was revealed in the aged cardiovascular system. In the CNS, the decline of the neuronal (n)NOS production of NO was related to the impairment of memory, sleep, and cognition. NO played an important role in the aging of oocytes and aged-induced erectile dysfunction. Aging downregulated NO signaling pathways in endothelial cells resulting in skin, kidney, thyroid, and muscle disorders. Putative therapeutic agents (natural/synthetic) affecting NO signaling mechanisms in the aging process are discussed in the present study. In summary, all of the studies reviewed demonstrate that NO plays a crucial role in the cellular aging processes.
    Keywords:  NO signaling pathways; aging; nitric oxide; nitric oxide synthase; senescence; therapeutic agents
    DOI:  https://doi.org/10.3390/molecules26154533
  30. Vaccines (Basel). 2021 Jul 01. pii: 721. [Epub ahead of print]9(7):
    Telomere Length Shortening in Microglia: Implication for Accelerated Senescence and Neurocognitive Deficits in HIV.
    Chiu-Bin Hsiao, Harneet Bedi, Raquel Gomez, Ayesha Khan, Taylor Meciszewski, Ravikumar Aalinkeel, Ting Chean Khoo, Anna V Sharikova, Alexander Khmaladze, Supriya D Mahajan.
      The widespread use of combination antiretroviral therapy (cART) has led to the accelerated aging of the HIV-infected population, and these patients continue to have a range of mild to moderate HIV-associated neurocognitive disorders (HAND). Infection results in altered mitochondrial function. The HIV-1 viral protein Tat significantly alters mtDNA content and enhances oxidative stress in immune cells. Microglia are the immune cells of the central nervous system (CNS) that exhibit a significant mitotic potential and are thus susceptible to telomere shortening. HIV disrupts the normal interplay between microglia and neurons, thereby inducing neurodegeneration. HIV cART contributes to the inhibition of telomerase activity and premature telomere shortening in activated peripheral blood mononuclear cells (PBMC). However, limited information is available on the effect of cART on telomere length (TL) in microglia. Although it is well established that telomere shortening induces cell senescence and contributes to the development of age-related neuro-pathologies, the effect of HIV-Tat on telomere length in human microglial cells and its potential contribution to HAND are not well understood. It is speculated that in HAND intrinsic molecular mechanisms that control energy production underlie microglia-mediated neuronal injury. TL, telomerase and mtDNA expression were quantified in microglial cells using real time PCR. Cellular energetics were measured using the Seahorse assay. The changes in mitochondrial function were examined by Raman Spectroscopy. We have also examined TL in the PBMC obtained from HIV-1 infected rapid progressors (RP) on cART and those who were cART naïve, and observed a significant decrease in telomere length in RP on cART as compared to RP's who were cART naïve. We observed a significant decrease in telomerase activity, telomere length and mitochondrial function, and an increase in oxidative stress in human microglial cells treated with HIV Tat. Neurocognitive impairment in HIV disease may in part be due to accelerated neuro-pathogenesis in microglial cells, which is attributable to increased oxidative stress and mitochondrial dysfunction.
    Keywords:  HIV-associated neurocognitive disorders (HAND); microglia; neuro-inflammation; oxidative stress; telomerase; telomere length
    DOI:  https://doi.org/10.3390/vaccines9070721
  31. Sci Rep. 2021 Aug 05. 11(1): 15929
    Biological age in healthy elderly predicts aging-related diseases including dementia.
    Julia W Wu, Amber Yaqub, Yuan Ma, Wouter Koudstaal, Albert Hofman, M Arfan Ikram, Mohsen Ghanbari, Jaap Goudsmit.
      Application of biological age as a measure of an individual´s health status offers new perspectives into extension of both lifespan and healthspan. While algorithms predicting mortality and most aging-related morbidities have been reported, the major shortcoming has been an inability to predict dementia. We present a community-based cohort study of 1930 participants with a mean age of 72 years and a follow-up period of over 7 years, using two variants of a phenotypic blood-based algorithm that either excludes (BioAge1) or includes (BioAge2) neurofilament light chain (NfL) as a neurodegenerative marker. BioAge1 and BioAge2 predict dementia equally well, as well as lifespan and healthspan. Each one-year increase in BioAge1/2 was associated with 11% elevated risk (HR 1.11; 95%CI 1.08-1.14) of mortality and 7% elevated risk (HR 1.07; 95%CI 1.05-1.09) of first morbidities. We additionally tested the association of microRNAs with age and identified 263 microRNAs significantly associated with biological and chronological age alike. Top differentially expressed microRNAs based on biological age had a higher significance level than those based on chronological age, suggesting that biological age captures aspects of aging signals at the epigenetic level. We conclude that accelerated biological age for a given age is a predictor of major age-related morbidity, including dementia, among healthy elderly.
    DOI:  https://doi.org/10.1038/s41598-021-95425-5
  32. Aging Dis. 2021 Aug;12(5): 1272-1286
    Systematic Review of Studies on Telomere Length in Patients with Multiple Sclerosis.
    Jan Bühring, Michael Hecker, Brit Fitzner, Uwe Klaus Zettl.
      Telomeres are protective cap structures at the end of chromosomes that are essential for maintaining genomic stability. Accelerated telomere shortening is related to premature cellular senescence. Shortened telomere lengths (TL) have been implicated in the pathogenesis of various chronic immune-mediated and neurological diseases. We aimed to systematically review the current literature on the association of TL as a measure of biological age and multiple sclerosis (MS). A comprehensive literature search was conducted to identify original studies that presented data on TL in samples from persons with MS. Quantitative and qualitative information was extracted from the articles to summarize and compare the studies. A total of 51 articles were screened, and 7 of them were included in this review. In 6 studies, average TL were analyzed in peripheral blood cells, whereas in one study, bone marrow-derived cells were used. Four of the studies reported significantly shorter leukocyte TL in at least one MS subtype in comparison to healthy controls (p=0.003 in meta-analysis). Shorter telomeres in patients with MS were found to be associated, independently of age, with greater disability, lower brain volume, increased relapse rate and more rapid conversion from relapsing to progressive MS. However, it remains unclear how telomere attrition in MS may be linked to oxidative stress, inflammation and age-related disease processes. Despite few studies in this field, there is substantial evidence on the association of TL and MS. Variability in TL appears to reflect heterogeneity in clinical presentation and course. Further investigations in large and well-characterized cohorts are warranted. More detailed studies on TL of individual chromosomes in specific cell types may help to gain new insights into the pathomechanisms of MS.
    Keywords:  biological aging; immune cells; immunosenescence; multiple sclerosis; telomere length measurement; telomeres
    DOI:  https://doi.org/10.14336/AD.2021.0106
  33. Ageing Res Rev. 2021 Jul 31. pii: S1568-1637(21)00164-1. [Epub ahead of print]70 101417
    Exploring ER stress response in cellular aging and neuroinflammation in Alzheimer's disease.
    Md Sahab Uddin, Wing Shan Yu, Lee Wei Lim.
      One evident hallmark of Alzheimer's disease (AD) is the irregular accumulation of proteins due to changes in proteostasis involving endoplasmic reticulum (ER) stress. To alleviate ER stress and reinstate proteostasis, cells undergo an integrated signaling cascade called the unfolded protein response (UPR) that reduces the number of misfolded proteins and inhibits abnormal protein accumulation. Aging is associated with changes in the expression of ER chaperones and folding enzymes, leading to the impairment of proteostasis, and accumulation of misfolded proteins. The disrupted initiation of UPR prevents the elimination of unfolded proteins, leading to ER stress. In AD, the accumulation of misfolded proteins caused by sustained cellular stress leads to neurodegeneration and neuronal death. Current research has revealed that ER stress can trigger an inflammatory response through diverse transducers of UPR. Although the involvement of a neuroinflammatory component in AD has been documented for decades, whether it is a contributing factor or part of the neurodegenerative events is so far unknown. Besides, a feedback loop occurs between neuroinflammation and ER stress, which is strongly associated with neurodegenerative processes in AD. In this review, we focus on the current research on ER stress and UPR in cellular aging and neuroinflammatory processes, leading to memory impairment and synapse dysfunction in AD.
    Keywords:  Aging; Alzheimer’s disease; ER stress; Endoplasmic reticulum; Neuroinflammation; Unfolded protein response
    DOI:  https://doi.org/10.1016/j.arr.2021.101417
  34. Int J Mol Sci. 2021 Jul 22. pii: 7824. [Epub ahead of print]22(15):
    Microglia and the Aging Brain: Are Geriatric Microglia Linked to Poor Sleep Quality?
    Mohammed E Choudhury, Kazuya Miyanishi, Haruna Takeda, Junya Tanaka.
      Poor sleep quality and disrupted circadian behavior are a normal part of aging and include excessive daytime sleepiness, increased sleep fragmentation, and decreased total sleep time and sleep quality. Although the neuronal decline underlying the cellular mechanism of poor sleep has been extensively investigated, brain function is not fully dependent on neurons. A recent antemortem autographic study and postmortem RNA sequencing and immunohistochemical studies on aged human brain have investigated the relationship between sleep fragmentation and activation of the innate immune cells of the brain, microglia. In the process of aging, there are marked reductions in the number of brain microglial cells, and the depletion of microglial cells disrupts circadian rhythmicity of brain tissue. We also showed, in a previous study, that pharmacological suppression of microglial function induced sleep abnormalities. However, the mechanism underlying the contribution of microglial cells to sleep homeostasis is only beginning to be understood. This review revisits the impact of aging on the microglial population and activation, as well as microglial contribution to sleep maintenance and response to sleep loss. Most importantly, this review will answer questions such as whether there is any link between senescent microglia and age-related poor quality sleep and how this exacerbates neurodegenerative disease.
    Keywords:  aging; circadian rhythm; microglia; sleep; synapse
    DOI:  https://doi.org/10.3390/ijms22157824
  35. Nature. 2021 Aug 04.
    Genetic insights into biological mechanisms governing human ovarian ageing.
    Biobank-based Integrative Omics Study (BIOS) Consortium
      Reproductive longevity is essential for fertility and influences healthy ageing in women1,2, but insights into its underlying biological mechanisms and treatments to preserve it are limited. Here we identify 290 genetic determinants of ovarian ageing, assessed using normal variation in age at natural menopause (ANM) in about 200,000 women of European ancestry. These common alleles were associated with clinical extremes of ANM; women in the top 1% of genetic susceptibility have an equivalent risk of premature ovarian insufficiency to those carrying monogenic FMR1 premutations3. The identified loci implicate a broad range of DNA damage response (DDR) processes and include loss-of-function variants in key DDR-associated genes. Integration with experimental models demonstrates that these DDR processes act across the life-course to shape the ovarian reserve and its rate of depletion. Furthermore, we demonstrate that experimental manipulation of DDR pathways highlighted by human genetics increases fertility and extends reproductive life in mice. Causal inference analyses using the identified genetic variants indicate that extending reproductive life in women improves bone health and reduces risk of type 2 diabetes, but increases the risk of hormone-sensitive cancers. These findings provide insight into the mechanisms that govern ovarian ageing, when they act, and how they might be targeted by therapeutic approaches to extend fertility and prevent disease.
    DOI:  https://doi.org/10.1038/s41586-021-03779-7
  36. Curr Oncol Rep. 2021 Aug 03. 23(10): 115
    Immune Checkpoint Inhibitors in the Aged.
    James Isaacs, Scott Antonia, Jeffrey Clarke.
       PURPOSE OF REVIEW: Large phase III trials have established the benefit of checkpoint blockade across multiple tumor types, but patient representation is limited in some subgroups including the aged population. There are several changes in the immune system that occur with age (termed immunosenescence) that could potentially limit efficacy in aged populations.
    RECENT FINDINGS: Despite the concerns stated above, available evidence from prospective trials, retrospective cohorts, and registry data suggest that elderly patients achieve similar benefit with immune checkpoint blockade in comparison to the general population and do not have increased toxicity. However, as patients age, they are at higher risk of developing a decline in multiple physiologic systems (including the immune system) and reduced ability to recover from illness. Clinical evidence shows that patients who have a poor performance status have inferior outcomes and limited clinical benefit from checkpoint blockade. Clinicians should take an individualized approach that accounts for each patient's health status rather than considering age alone when determining who should be offered checkpoint blockade therapy.
    Keywords:  Aged; Anti-CTLA4; Anti-PD-1; Cytokines; Geriatric assessment; Immune age; Immune checkpoint blockade; Immunosenescence; Memory T cells; Toxicity
    DOI:  https://doi.org/10.1007/s11912-021-01106-x
  37. Nat Commun. 2021 Aug 06. 12(1): 4773
    Impact of aging and exercise on skeletal muscle mitochondrial capacity, energy metabolism, and physical function.
    L Grevendonk, N J Connell, C McCrum, C E Fealy, L Bilet, Y M H Bruls, J Mevenkamp, V B Schrauwen-Hinderling, J A Jörgensen, E Moonen-Kornips, G Schaart, B Havekes, J de Vogel-van den Bosch, M C E Bragt, K Meijer, P Schrauwen, J Hoeks.
      The relationship between the age-associated decline in mitochondrial function and its effect on skeletal muscle physiology and function remain unclear. In the current study, we examined to what extent physical activity contributes to the decline in mitochondrial function and muscle health during aging and compared mitochondrial function in young and older adults, with similar habitual physical activity levels. We also studied exercise-trained older adults and physically impaired older adults. Aging was associated with a decline in mitochondrial capacity, exercise capacity and efficiency, gait stability, muscle function, and insulin sensitivity, even when maintaining an adequate daily physical activity level. Our data also suggest that a further increase in physical activity level, achieved through regular exercise training, can largely negate the effects of aging. Finally, mitochondrial capacity correlated with exercise efficiency and insulin sensitivity. Together, our data support a link between mitochondrial function and age-associated deterioration of skeletal muscle.
    DOI:  https://doi.org/10.1038/s41467-021-24956-2
  38. Aging Dis. 2021 Aug;12(5): 1323-1336
    The Role of SGLT2 Inhibitors in Vascular Aging.
    Le Liu, Yu-Qing Ni, Jun-Kun Zhan, You-Shuo Liu.
      Vascular aging is defined as organic and functional changes in blood vessels, in which decline in autophagy levels, DNA damage, MicroRNA (miRNA), oxidative stress, sirtuin, and apoptosis signal-regulated kinase 1 (ASK1) are integral thereto. With regard to vascular morphology, the increase in arterial stiffness, atherosclerosis, vascular calcification and high amyloid beta levels are closely related to vascular aging. Further closely related thereto, at the cellular level, is the aging of vascular endothelial cells (ECs) and vascular smooth muscle cells (VSMCs). Vascular aging seriously affects the health, economy and life of patients, but can be delayed by SGLT2 inhibitors through the improvement of vascular function. In the present article, a review is conducted of recent domestic and international progress in research on SGLT2 inhibitors,vascular aging and diseases related thereto, thereby providing theoretical support and guidance for further revealing the relationship between SGLT2 inhibitors and diseases related to vascular aging.
    Keywords:  arterial stiffness; endothelial cells; sodium-dependent glucose transporters 2 inhibitor; vascular aging; vascular smooth muscle cells
    DOI:  https://doi.org/10.14336/AD.2020.1229
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