Idiopathic pulmonary fibrosis (IPF) is a fatal disease characterized by interstitial remodelling, leading to compromised lung function. Cellular senescence markers are detectable within IPF lung ...tissue and senescent cell deletion rejuvenates pulmonary health in aged mice. Whether and how senescent cells regulate IPF or if their removal may be an efficacious intervention strategy is unknown. Here we demonstrate elevated abundance of senescence biomarkers in IPF lung, with p16 expression increasing with disease severity. We show that the secretome of senescent fibroblasts, which are selectively killed by a senolytic cocktail, dasatinib plus quercetin (DQ), is fibrogenic. Leveraging the bleomycin-injury IPF model, we demonstrate that early-intervention suicide-gene-mediated senescent cell ablation improves pulmonary function and physical health, although lung fibrosis is visibly unaltered. DQ treatment replicates benefits of transgenic clearance. Thus, our findings establish that fibrotic lung disease is mediated, in part, by senescent cells, which can be targeted to improve health and function.
Cellular senescence is characterized by an irreversible cell cycle arrest and a pro‐inflammatory senescence‐associated secretory phenotype (SASP), which is a major contributor to aging and ...age‐related diseases. Clearance of senescent cells has been shown to improve brain function in mouse models of neurodegenerative diseases. However, it is still unknown whether senescent cell clearance alleviates cognitive dysfunction during the aging process. To investigate this, we first conducted single‐nuclei and single‐cell RNA‐seq in the hippocampus from young and aged mice. We observed an age‐dependent increase in p16Ink4a senescent cells, which was more pronounced in microglia and oligodendrocyte progenitor cells and characterized by a SASP. We then aged INK‐ATTAC mice, in which p16Ink4a‐positive senescent cells can be genetically eliminated upon treatment with the drug AP20187 and treated them either with AP20187 or with the senolytic cocktail Dasatinib and Quercetin. We observed that both strategies resulted in a decrease in p16Ink4a exclusively in the microglial population, resulting in reduced microglial activation and reduced expression of SASP factors. Importantly, both approaches significantly improved cognitive function in aged mice. Our data provide proof‐of‐concept for senolytic interventions' being a potential therapeutic avenue for alleviating age‐associated cognitive impairment.
Senescence is a major contributor to aging and age‐related diseases. However, it is still unknown whether senolytics impact on cognitive function during the aging process. We found that both pharmacogenetic clearance of p16Ink4a senescent cells or treatment with senolytic cocktail Dasatinib and Quercetin, reduced senescent microglia in the hippocampus and improved cognitive function in aged mice.
Full text
Available for:
DOBA, FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, UILJ, UKNU, UL, UM, UPUK
Chronic, low grade, sterile inflammation frequently accompanies aging and age-related diseases. Cellular senescence is associated with the production of proinflammatory chemokines, cytokines, and ...extracellular matrix (ECM) remodeling proteases, which comprise the senescence-associated secretory phenotype (SASP). We found a higher burden of senescent cells in adipose tissue with aging. Senescent human primary preadipocytes as well as human umbilical vein endothelial cells (HUVECs) developed a SASP that could be suppressed by targeting the JAK pathway using RNAi or JAK inhibitors. Conditioned medium (CM) from senescent human preadipocytes induced macrophage migration in vitro and inflammation in healthy adipose tissue and preadipocytes. When the senescent cells from which CM was derived had been treated with JAK inhibitors, the resulting CM was much less proinflammatory. The administration of JAK inhibitor to aged mice for 10 wk alleviated both adipose tissue and systemic inflammation and enhanced physical function. Our findings are consistent with a possible contribution of senescent cells and the SASP to age-related inflammation and frailty. We speculate that SASP inhibition by JAK inhibitors may contribute to alleviating frailty. Targeting the JAK pathway holds promise for treating age-related dysfunction.
Full text
Available for:
BFBNIB, NMLJ, NUK, PNG, SAZU, UL, UM, UPUK
Summary
Clearing senescent cells extends healthspan in mice. Using a hypothesis‐driven bioinformatics‐based approach, we recently identified pro‐survival pathways in human senescent cells that ...contribute to their resistance to apoptosis. This led to identification of dasatinib (D) and quercetin (Q) as senolytics, agents that target some of these pathways and induce apoptosis preferentially in senescent cells. Among other pro‐survival regulators identified was Bcl‐xl. Here, we tested whether the Bcl‐2 family inhibitors, navitoclax (N) and TW‐37 (T), are senolytic. Like D and Q, N is senolytic in some, but not all types of senescent cells: N reduced viability of senescent human umbilical vein epithelial cells (HUVECs), IMR90 human lung fibroblasts, and murine embryonic fibroblasts (MEFs), but not human primary preadipocytes, consistent with our previous finding that Bcl‐xl siRNA is senolytic in HUVECs, but not preadipocytes. In contrast, T had little senolytic activity. N targets Bcl‐2, Bcl‐xl, and Bcl‐w, while T targets Bcl‐2, Bcl‐xl, and Mcl‐1. The combination of Bcl‐2, Bcl‐xl, and Bcl‐w siRNAs was senolytic in HUVECs and IMR90 cells, while combination of Bcl‐2, Bcl‐xl, and Mcl‐1 siRNAs was not. Susceptibility to N correlated with patterns of Bcl‐2 family member proteins in different types of human senescent cells, as has been found in predicting response of cancers to N. Thus, N is senolytic and acts in a potentially predictable cell type‐restricted manner. The hypothesis‐driven, bioinformatics‐based approach we used to discover that dasatinib (D) and quercetin (Q) are senolytic can be extended to increase the repertoire of senolytic drugs, including additional cell type‐specific senolytic agents.
Full text
Available for:
DOBA, FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, UILJ, UKNU, UL, UM, UPUK
Summary
While reports suggest a single dose of senolytics may improve vasomotor function, the structural and functional impact of long‐term senolytic treatment is unknown. To determine whether ...long‐term senolytic treatment improves vasomotor function, vascular stiffness, and intimal plaque size and composition in aged or hypercholesterolemic mice with established disease. Senolytic treatment (intermittent treatment with Dasatinib + Quercetin via oral gavage) resulted in significant reductions in senescent cell markers (TAF+ cells) in the medial layer of aorta from aged and hypercholesterolemic mice, but not in intimal atherosclerotic plaques. While senolytic treatment significantly improved vasomotor function (isolated organ chamber baths) in both groups of mice, this was due to increases in nitric oxide bioavailability in aged mice and increases in sensitivity to NO donors in hypercholesterolemic mice. Genetic clearance of senescent cells in aged normocholesterolemic INK‐ATTAC mice phenocopied changes elicited by D+Q. Senolytics tended to reduce aortic calcification (alizarin red) and osteogenic signaling (qRT–PCR, immunohistochemistry) in aged mice, but both were significantly reduced by senolytic treatment in hypercholesterolemic mice. Intimal plaque fibrosis (picrosirius red) was not changed appreciably by chronic senolytic treatment. This is the first study to demonstrate that chronic clearance of senescent cells improves established vascular phenotypes associated with aging and chronic hypercholesterolemia, and may be a viable therapeutic intervention to reduce morbidity and mortality from cardiovascular diseases.
Full text
Available for:
DOBA, FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, UILJ, UKNU, UL, UM, UPUK
Senescent cells accumulate in fat with aging. We previously found genetic clearance of senescent cells from progeroid INK-ATTAC mice prevents lipodystrophy. Here we show that primary human senescent ...fat progenitors secrete activin A and directly inhibit adipogenesis in non-senescent progenitors. Blocking activin A partially restored lipid accumulation and expression of key adipogenic markers in differentiating progenitors exposed to senescent cells. Mouse fat tissue activin A increased with aging. Clearing senescent cells from 18-month-old naturally-aged INK-ATTAC mice reduced circulating activin A, blunted fat loss, and enhanced adipogenic transcription factor expression within 3 weeks. JAK inhibitor suppressed senescent cell activin A production and blunted senescent cell-mediated inhibition of adipogenesis. Eight weeks-treatment with ruxolitinib, an FDA-approved JAK1/2 inhibitor, reduced circulating activin A, preserved fat mass, reduced lipotoxicity, and increased insulin sensitivity in 22-month-old mice. Our study indicates targeting senescent cells or their products may alleviate age-related dysfunction of progenitors, adipose tissue, and metabolism.
1 Obesity Research Center, 2 Department of Medicine and Department of Genetics and Genomics, Boston University, Boston, Massachusetts; 3 Department of Surgery, Creighton University, Omaha, Nebraska; ...4 Division of Gastroenterology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston Massachusetts; and 5 Mayo Clinic Foundation, Rochester, Minnesota
Submitted 26 April 2006
; accepted in final form 6 September 2006
Anatomically separate fat depots differ in size, function, and contribution to pathological states, such as the metabolic syndrome. We isolated preadipocytes from different human fat depots to determine whether the basis for this variation is partly attributable to differences in inherent properties of fat cell progenitors. We found that genome-wide expression profiles of primary preadipocytes cultured in parallel from abdominal subcutaneous, mesenteric, and omental fat depots were distinct. Interestingly, visceral fat was not homogeneous. Preadipocytes from one of the two main visceral depots, mesenteric fat, had an expression profile closer to that of subcutaneous than omental preadipocytes, the other main visceral depot. Expression of genes that regulate early development, including homeotic genes, differed extensively among undifferentiated preadipocytes isolated from different fat depots. These profiles were confirmed by real-time PCR analysis of preadipocytes from additional lean and obese male and female subjects. We made preadipocyte strains from single abdominal subcutaneous and omental preadipocytes by expressing telomerase. Depot-specific developmental gene expression profiles persisted for 40 population doublings in these strains. Thus, human fat cell progenitors from different regions are effectively distinct, consistent with different fat depots being separate mini-organs.
visceral fat; homeotic genes; telomerase; metabolic syndrome
Address for reprint requests and other correspondence: J. L. Kirkland, Boston University Medical Center, 88 East Newton St., Boston, MA 02118
Fat Depot–Specific Characteristics Are Retained in Strains Derived From Single Human Preadipocytes
Tamara Tchkonia 1 ,
Nino Giorgadze 1 ,
Tamar Pirtskhalava 1 ,
Thomas Thomou 1 ,
Matthew DePonte 2 ,
...Ada Koo 2 ,
R. Armour Forse 3 ,
Dharmaraj Chinnappan 1 ,
Carmen Martin-Ruiz 4 ,
Thomas von Zglinicki 4 and
James L. Kirkland 1 5
1 Department of Medicine, Boston University, Boston, Massachusetts
2 AdipoGenix, Boston, Massachusetts
3 Department of Surgery, Creighton University, Omaha, Nebraska
4 Henry Wellcome Biogerontology Laboratory, Institute for Ageing and Health, University of Newcastle, Newcastle, U.K
5 Department of Biochemistry, Boston University, Boston, Massachusetts
Address correspondence and reprint requests to James L. Kirkland, MD, PhD, Boston University, 88 East Newton St., Robinson
2, Boston, MA 02118. E-mail: kirkland{at}bu.edu
Abstract
Fat depots vary in size, function, and potential contribution to disease. Since fat tissue turns over throughout life, preadipocyte
characteristics could contribute to this regional variation. To address whether preadipocytes from different depots are distinct,
we produced preadipocyte strains from single abdominal subcutaneous, mesenteric, and omental human preadipocytes by stably
expressing human telomere reverse transcriptase (hTERT). These strains could be subcultured repeatedly and retained capacity
for differentiation, while primary preadipocyte adipogenesis and replication declined with subculturing. Primary omental preadipocytes,
in which telomeres were longest, replicated more slowly than mesenteric or abdominal subcutaneous preadipocytes. Even after
40 population doublings, replication, abundance of the rapidly replicating preadipocyte subtype, and resistance to tumor necrosis
factor α–induced apoptosis were highest in subcutaneous, intermediate in mesenteric, and lowest in omental hTERT-expressing
strains, as in primary preadipocytes. Subcutaneous hTERT-expressing strains accumulated more lipid and expressed more adipocyte
fatty acid–binding protein (aP2), peroxisome proliferator–activated receptor γ2, and CCAAT/enhancer-binding protein α than
omental cells, as in primary preadipocytes, while hTERT abundance was similar. Thus, despite dividing 40 population doublings,
hTERT strains derived from single preadipocytes retained fat depot–specific cell dynamic characteristics, consistent with
heritable processes contributing to regional variation in fat tissue function.
C/EBPα, CCAAT/enhancer-binding protein α
FBS, fetal bovine serum
G3PD, glycerol-3-phosphate dehydrogenase
hTERT, human telomere reverse transcriptase
mRNA, messenger RNA
PPAR, peroxisome proliferator–activated receptor
TNF, tumor necrosis factor
Footnotes
Additional information on this article can be found in an online appendix at http://diabetes.diabetesjournals.org .
The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore
be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
Accepted June 8, 2006.
Received April 20, 2006.
DIABETES
1 Evans Department of Medicine and Departments of
3 Surgery and 5 Biochemistry, Boston
University Medical Center, Boston, Massachusetts 02118;
2 Division of Endocrinology and Metabolism,
...Department of Internal Medicine, the Mayo Clinic, Rochester,
Minnesota 55905; and 4 AdipoGenix, Boston, Massachusetts
02118
Fat distribution varies among
individuals with similar body fat content. Innate differences in
adipose cell characteristics may contribute because lipid accumulation
and lipogenic enzyme activities vary among preadipocytes
cultured from different fat depots. We determined expression of the
adipogenic transcription factors peroxisome proliferator activated
receptor- (PPAR- ) and CCAAT/enhancer binding protein-
(C/EBP- ) and their targets in abdominal subcutaneous, mesenteric,
and omental preadipocytes cultured in parallel from obese subjects.
Subcutaneous preadipocytes, which had the highest lipid accumulation,
glycerol-3-phosphate dehydrogenase (G3PD) activity, and adipocyte fatty
acid binding protein (aP2) abundance, had highest PPAR- and
C/EBP- expression. Levels were intermediate in mesenteric
and lowest in omental preadipocytes. Overexpression of C/EBP- in
transfected omental preadipocytes enhanced differentiation. The
proportion of differentiated cells in colonies derived from single
subcutaneous preadipocytes was higher than in mesenteric or omental
clones. Only cells that acquired lipid inclusions exhibited C/EBP-
upregulation, irrespective of depot origin. Thus regional variation in
adipogenesis depends on differences at the level of transcription
factor expression and is a trait conferred on daughter cells.
adipocyte fatty acid binding protein; fatty acid binding protein; peroxisome proliferator activated receptor- ; CCAAT/enhancer binding
protein-
PDF
