Circulation Journal
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Potential Clinical Implications of Senotherapies for Cardiovascular Disease
Masayoshi SudaGoro KatsuumiTamar TchkoniaJames L. KirklandTohru Minamino
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論文ID: CJ-23-0657

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Abstract

Aging is a major risk factor for cardiovascular diseases (CVDs) and accumulating evidence indicates that biological aging has a significant effect on the onset and progression of CVDs. In recent years, therapies targeting senescent cells (senotherapies), particularly senolytics that selectively eliminate senescent cells, have been developed and show promise for treating geriatric syndromes and age-associated diseases, including CVDs. In 2 pilot studies published in 2019 the senolytic combination, dasatinib plus quercetin, improved physical function in patients with idiopathic pulmonary fibrosis and eliminated senescent cells from adipose tissue in patients with diabetic kidney disease. More than 30 clinical trials using senolytics are currently underway or planned. In preclinical CVD models, senolytics appear to improve heart failure, ischemic heart disease, valvular heart disease, atherosclerosis, aortic aneurysm, vascular dysfunction, dialysis arteriovenous fistula patency, and pre-eclampsia. Because senotherapies are completely different strategies from existing treatment paradigms, they might alleviate diseases for which there are no current effective treatments or they could be used in addition to current therapies to enhance efficacy. Moreover, senotherapies might delay, prevent, alleviate or treat multiple diseases in the elderly and reduce polypharmacy, because senotherapies target fundamental aging mechanisms. We comprehensively summarize the preclinical evidence about senotherapies for CVDs and discuss future prospects for their clinical application.

Cardiovascular diseases (CVDs) remain the leading cause of morbidity and mortality among older people globally, claiming an estimated 17.9 million lives each year.1 The prevalence of the majority of CVDs such as heart attacks, coronary artery disease, hypertension, atherosclerosis, stroke, heart failure (HF), valvular heart diseases, aortic aneurysms, and arrhythmias, including atrial fibrillation (AF), increases steadily with patient age. Although the pathogenesis of CVDs is multifactorial and risk factors for CVDs such as diabetes and hypertension increase with age, aging appears to be an independent risk factor.2,3 Although CVD mortality rates are declining,4 despite aggressive control of risk factors as recommended in recent guidelines, the prevalence of CVDs has not improved dramatically and may be due to failure to intervene against a key underlying cause of CVD: biological aging.

Age-associated diseases and geriatric syndromes including CVDs are, in part, a consequence of biological aging. Targeting the hallmarks of biological aging may be a root-cause therapeutic approach for delaying the onset or alleviating multiple age-associated conditions; that is, the “geroscience hypothesis”.4 Moreover, intervening against any one of the biological aging mechanisms that underlie age-associated diseases and geriatric syndromes may affect many or most of the rest, a unitary theory of fundamental aging mechanisms.5

Senotherapies

The 3 approaches being investigated as potential senotherapies in preclinical models are: (1) elimination of persisting senescent cells (senolytics), (2) in vivo direct reprogramming of senescent cells, and (3) suppression of release of the senescence-associated secretory phenotype (SASP) factors by senescent cells (senomorphics) (Figure).

Figure.

Contributions of senescent cells to cardiovascular diseases (CVDs). Senescent cells accumulate during aging and are related to many forms of stress including DNA damage, mechanical/shear stress, reactive metabolites (e.g., reactive oxygen species), angiotensin II, hyperinsulinemia, and oxidized low-density lipoprotein. The cell cycle becomes arrested and so reduces the risk that damaged dysfunctional cells proliferate and give rise to cancers. However, persistent dysfunctional senescent cells can continue to release tissue-damaging SASP factors that induce inflammation, contributing to the pathology of CVDs. There are currently 3 strategies being investigated to attenuate unfavorable consequences of persistent, pro-inflammatory senescent cells: (1) senolytics that induce death of those senescent cells that are pro-apoptotic; (2) reprogramming to alter epigenetic programming through the Yamanaka factors (OSKM) to revert senescent cells into a non-senescent state; and (3) senomorphics that inhibit production of tissue-destructive SASP factors from senescent cells while not directly eliminating the senescent cells themselves. Metformin, rapamycin, and ruxolitinib are among the senomorphics in clinical use for various indications.

Senolytics was proposed as a therapeutic strategy of inducing cell death in senescent cells. The first senolytic, a combination of dasatinib and quercetin (D+Q), reduced the senescent cell burden in naturally aged mice,69 and alleviated age-related metabolic dysfunction.10 A causal role for cellular senescence in the generation of age-related phenotypes was further demonstrated by showing that transplantation of small numbers of senescent cells into middle-aged mice can cause frailty-like physical dysfunction and multiple age-associated diseases.11 These findings support the potential of senolytics as a root-cause treatment for many age-associated disorders and diseases. Based on the first study of senolytics, more have since been identified4,10,1231 (Table 1). To date, senolytics appear to alleviate multiple conditions, including cardiac dysfunction,5,7,3235 vascular diseases,34,35 frailty,3638 cognitive impairment,3943 renal dysfunction,44 pulmonary diseases,38 osteoporosis,28,45,46 and hepatic steatosis.47

Table 1.

List of Senotherapies

Senolytic Target molecules Localization
Dasatinib Src kinase, Tyrosine kinase, etc Plasma membrane
Quercetin Bcl-2 family, p53/p21/serpine, PI3K/AKT Cytoplasm, Mitochondria, Nuclei
Fisetin PI3K/AKT Cytoplasm
Navitoclax (ABT-263) Bcl-2 family (Bcl-2, Bcl-xl, Bcl-w) Cytoplasm, Mitochondria
PZ15227 Bcl-xl Cytoplasm, Mitochondria
TW-37 Bcl-2 family (Bcl-2, Bcl-xl, Mcl-1) Cytoplasm, Mitochondria
ABT-737 Bcl-xl, Bcl-w Cytoplasm, Mitochondria
Luteolin Bcl-2 family (Bcl-xl) Cytoplasm, Mitochondria
Curcumin, Curcumin analog EF24 Bcl-2 family (Bcl-xl) Cytoplasm, Mitochondria
A1331852 Bcl-2 family (Bcl-xl) Cytoplasm, Mitochondria
A1155463 Bcl-2 family (Bcl-xl) Cytoplasm, Mitochondria
Piperlongumine p53/p21, Bcl-2 family (PUMA) Cytoplasm, Mitochondria, Nuclei
FOXO4-DRI FOXO-p53 interaction Nuclei
Nutlin3a p53 Nuclei
UBX0101 p53-MDM2 / p21 Nuclei
Panobinostat Histon deacetylase Nuclei
ARV825 BET family protein, NHEJ Cytoplasm
AT-406 IAP1/2/XIAP Cytoplasm
Fenofibrate PPARα Cytoplasm
Alvespimycin (17-DMAG) HSP90 Cytoplasm
Tanespimycin (17-AAG) HSP90 Cytoplasm
Geldanamycin HSP90 Cytoplasm
Digoxin (cardiac glycosides) Na+/K+ ATPase pump Plasma membrane
BPTES GLS1 Lysosome
Galactose-modified duocarmycin (GMD) Lysosomal β-galactosidase Lysosome
SSK1-Gemcitabine Lysosomal β-galactosidase Lysosome
2-DG Lysosomal V-ATPases Lysosome
GPNMB vaccine GPNMB Plasma membrane, lysosome
CD153 vaccine CD153 Plasma membrane
ADC against B2M β2 microglobulin (B2M) Plasma membrane
uPAR specific CAR T Urokinase-type plasminogen
activator receptor (uPAR)
Plasma membrane
Senomorphics Target molecules Localization
Rapamycin mTOR Cytoplasm
Metformin AMPK Cytoplasm
Ruxolitinib JAK 1/2 Cytoplasm
NBD peptide/mimetics NF-κB Cytoplasm

2-DG, 2-deoxy-d-glucose; 17-DMAG, 17-dimethylaminoethylamino-17-demethoxygeldanamycin; NHEJ, non-homologous end joining.

Another strategy to mitigate the adverse effects of senescent cells is to reprogram them using the Yamanaka factors, Oct4, Sox2, Klf4, and c-Myc (OSKM), the discovery of which led to a Nobel prize in 2012.48 This approach allows cells, including senescent cells, to be converted to a state akin to pluripotency that might be applicable to counteract the effect of biological aging,4955 as well as regenerative medicine and development of new drugs. This field is evolving, and the long-term effects and the risk for adverse events have not yet been fully elucidated. Enabling potentially cancerous mutation-harboring senescent cells to escape replicative arrest is a concern.

The third approach to targeting cellular senescence is to use SASP inhibitors, senomorphics. This approach is different from the other two, because it does not target senescent cells themselves but rather the release of detrimental, inflammatory SASP factors by senescent cells. Several agents that are senomorphic, including metformin, ruxolitinib, and rapamycin, are in clinical use, with data available from post-marketing surveillance56 and retrospective studies.5764 A clinical trial using low-dose rapamycin for coronary artery disease (Cardiac Rehabilitation And Rapamycin in Elderly [CARE]) was conducted to test the safety and feasibility of low-dose rapamycin and effects on both SASP and frailty in elderly subjects undergoing cardiac rehabilitation. Intriguingly, rapamycin suppressed some of markers of senescent cells in adipose tissue, although it failed to alleviate frailty.65 Another clinical trial, TAME (Targeting Aging with Metformin), will test if metformin delays the appearance of a second age-associated disease.59,66 A challenge in using senomorphic drugs is modulating potential off-target effects on non-senescent cells and potential side effects from suppressing the physiological inflammation that may be necessary for resolving certain acute diseases or promoting tissue repair. Additionally, senomorphic treatment allows senescent cells themselves to persist, potentially necessitating more continuous administration of SASP inhibitors that senolytics, which could increase off-target and side effects.

Preclinical Evidence of Senolytics for CVDs

In preclinical studies of CVDs there is mounting evidence of the potential benefits of senolytics (Table 2). D+Q,7 quercetin,67,68 and navitoclax69,70 have improved cardiac function in aged mice and several HF models. In older humans, diastolic dysfunction, also known as HF with preserved ejection fraction (HFpEF), is a major problem.7174 An effect of senolytics on HFpEF may be also expected. In addition, D+Q prolongs survival of cardiac allografts from old mice,69 with a reduction in senescent cell burden and inflammation, suggesting senolytics may be of benefit in the case of organ transplantation or cell-based therapies to increase their viability.7577 Moreover, D+Q, by eliminating senescent cells, improved human induced pluripotent stem (iPS) cells-derived cardiomyocyte survival.78 Senolytics may be potentially useful in ischemic heart disease. D+Q activated approximately 10% of cardiac resident cardiac progenitor cells (CPCs) and increased differentiation from CPCs,32 in association with an improvement of cardiac repair.79 Navitoclax alleviated increased the left ventricular EF, enhanced myocardial vascularization in an ischemia-reperfusion model in mice and rats, and increased survival after myocardial infarction in aged mice.33,80,81 Navitoclax-coated stents were associated with reduced stenotic area in rabbits on a high cholesterol diet.82

Table 2.

Preclinical Studies of Senolytics for Cardiovascular Diseases

Disease targeted Results of senolytic therapy Senolytics Senolytic model Disease model
Heart failure Alleviated impaired ejection fraction
Activated resident CPCs and
increased cardiomyocyte proliferation
Reduced myocardial
hypertrophy and fibrosis
D+Q7,32
Navitoclax33
INK-ATTAC32,33 Aged (mouse)
Attenuated cardiac systolic dysfunction
Normalized hypertrophy
Reduced cardiac fat and fibrosis
Increased proliferation of
CPCs and cardiac repair
Q67,68
D+Q79
Navitoclax70,119
  High fat diet-induced
Angiotensin II
(Ang II)-induced
Doxorubicin
(DOX)-induced
(Mouse or rat)
Heart transplantation Prolonged the survival of
cardiac allografts from aged mice
D+Q69   Aged (mouse)
Hypertension Improved vascular relaxation
Alleviated aortic calcification
and improved vasomotor function
D+Q7,34 INK-ATTAC34 Aged (mouse)
Pulmonary arterial hypertension Improved hemodynamic and
structural changes
associated with severe PAH
Navitoclax97   MCT and shunt-induced
PAH (rat)
Ischemic heart diseases Reduced myocardial
hypertrophy and fibrosis
Alleviated impaired ejection fraction
Increased myocardial vascularization
Increased survival after myocardial infarction
D+Q120
Navitoclax81,121,122
  Ischemia-reperfusion or
myocardial infarction
model (mouse or rat)
Atherosclerosis Reduced atherosclerotic
plaque formation and instability
Increased thickness of the fibrous cap
Navitoclax35,91,95
GPNMB-vaccine26
Digoxin93
17-DMAG94
BPTES24
INK-ATTAC35,95
p16-3MR35,91,95
Ldlr KO or ApoE KO
(mouse)
Coronary artery stent restenosis Reduced stenosis area of
senolytic-coated stent
Navitoclax82   Cholesterol diet (rabbit)
Abdominal aortic aneurysm Reduced size of AAA D+Q96   Angiotensin II (Ang II)
administrated in aged
(mouse)
Atrial fibrillation Ameliorated atrial fibrosis
Shorten AF duration
Fisetin89
Q88
  Myocardial infarction (rat)
Isoproterenol (rat)
Chronic kidney disease Decreased senescent cells burden D+Q99   Dialysis arteriovenous
fistula (mouse)
Diabetic retinal angiopathy Attenuated ischemic retinopathy UBX1967100 INK-ATTAC100 Oxygen-induced
retinopathy (mouse)
Eye tissue (human)

The incidence of AF increases with aging.83,84 Senescent cell accumulation in the atrium with aging has been demonstrated in rodents and humans.8587 There are 2 preclinical studies with either quercetin88 or fisetin89 that demonstrated potential alleviation of AF and fibrosis, although in those studies the drugs were used as antifibrotics and senescent cell removal was not specifically examined. The results obtained in rodent models may not fully reflect the underlying mechanisms of AF in humans, because AF is not a naturally occurring condition in rodents.90

Senolytic therapies have also been tested in preclinical models of vascular diseases with promising results. Senolytics such as anti-Gpnmb vaccination, navitoclax, digoxin, BPTES, and 17-DMAG (alvespimycin) have reduced atherosclerotic plaque formation and inflammation,2224,35,9194 alleviated fibrous capsule thinning of atherosclerotic plaques,95 and attenuated vascular calcification.34 D+Q might attenuate hypertension in the elderly because it improves vasorelaxation and vasomotor function in aged mice.7,34 Also, in aged mice with abdominal aortic aneurysms (AAA), D+Q reduced the size of the AAA.96 In addition to these effects, senolytics has been tested for efficacy in the diseases such as pulmonary arterial hypertension (PAH),97,98 hemodialysis shunt survival,99 and ischemic retinopathy100 (Table 2).

Clinical Trials of Senolytics

More than 30 clinical trials of senolytics, including phase 2 randomized, double-blinded, placebo-controlled trials, are already underway or planned based on the promising results in preclinical experiments.4 D+Q was used in 2 pilot studies of senolytics because 1 approach is to use senolytic compounds already approved for other uses or natural products with established safety data in the early studies and already favorable results have been reported.101,102 In the field of CVDs, translation of antisenescence drugs into the clinic has lagged, although, there are current studies planned or beginning with senolytic drugs targeting cardiac and arterial diseases.103 One is the Q-CABG study, testing oral quercetin monotherapy as a senolytic in patients undergoing coronary artery bypass graft (CABG) surgery. More clinical studies are being planned, including for HF with different causes, arrhythmias such as AF, and maintaining arteriovenous dialysis fistula patency, among other CVDs.

Future Directions

Senolytics, as a novel class of drugs, might be effective in diseases for which no good treatments currently exist, such as HFpEF. Senolytics may have the potential for synergistic beneficial effects if combined with current therapies that are known to improve the prognosis of CVDs.104 The effectiveness of senolytics might also be enhanced when used in combination with other interventions, such as lifestyle changes (e.g., caloric restriction, exercise), that target interlinked fundamental aging processes. Senolytics might also alleviate more than one pathology associated with aging at the same time. Such multimorbidity is often a problem for older patients with CVDs.105,106

The senotherapy field is new and there are important steps that need to be taken to efficiently discover new, safe senolytics and senomorphics and translate them into agents for clinical use. Preclinical and early clinical trials suggested short-term safety and target engagement for senolytics, but it will be important to conduct further studies to test for potential long-term side effects. Another need is to identify gerodiagnostic biomarkers that can be tested in body fluids such as blood, urine, saliva or tears to monitor senescent cell abundance. Among such gerodiagnostics are CD3-positive T cells expressing p16INK4a in peripheral blood,107,108 and α-Klotho in urine.109 SASP factors in circulating blood, tissue or cells might also be used for estimating senescent cell burden. Although a single SASP factor may not be highly sensitive or specific, combinations of such indicators might be better.69,101,102,110,111 In addition to protein and peptide SASP factors, blood non-coding nucleotide SASP factors (microRNAs [miRNA], short non-coding RNAs,112,113 small extracellular vesicles,114,115 and mitochondrial DNAs69) are emerging as gerodiagnostic markers. One difficulty is that senescent cells are highly heterogeneous: they release different factors depending on the cell type that became senescent, the inducer of senescence, how long the cell has been senescent, and the tissue microenvironment.116118

Conclusions

Senotherapies are an emerging strategy for intervening against fundamental aging mechanisms to potentially prevent and treat multiple disorders and diseases and extend health span. Because senotherapies allow targeting of the underlying causes of aging, rather than treating disorders and diseases individually, they could reduce polypharmacy, which is a cause of the attendant risks of adverse events and drug interactions. Senolytics are particularly attractive because they seem to be effective even when given intermittently, despite having short elimination half-lives, thereby minimizing potential toxic effects.

Although clinical studies of senotherapies for CVDs are limited so far, promising evidence from preclinical studies suggests senolytic agents might become a novel strategy for delaying, preventing, alleviating or treating CVDs. Further research is needed to identify the combinations of gerodiagnostic markers for monitoring target engagement during clinical trials and potentially for identifying which senolytics to use, when, and for how long to customize treatment for each patient. It must be borne in mind that treatments that appear to be highly promising in rodents frequently fail in clinical trials, especially in the cases of disorders such as AF, which do not occur naturally in rodents. It will be important to conduct validation studies for these diseases in large animal CVD models such rabbits, dogs, pigs, and monkeys. Because clinical studies of senolytics and senomorphics have already begun for other indications, it will be helpful to closely monitor cardiovascular effects and side effects in those studies. If eventually shown to be safe and effective, senolytics might one day be indicated for a number of CVDs.

Acknowledgments

This work was supported by the US National Institutes of Health (grants R37AG013925, R33AG061456, R01AG072301, R01AG061414, R01DK120292, R01AG68048, R01AG 64165, P01AG062413, and UH3AG056933), the Connor Fund, Robert J. and Theresa W. Ryan, the Noaber Foundation, a Grant-in-Aid for Scientific Research (A) (20H00533) and Grant-in-Aid for Challenging Research (Pioneering) (22K18389) from MEXT, AMED-CREST (JP22 gm1110012), and the Moonshot Research and Development Program (22zf0127003s0201).

Disclosure Summary

M.S., G.K. have no disclosures. T.M. is a member of Circulation Journal’s Editorial Team. T.T., J.L.K. have a financial interest related to this research, including patents and pending patents covering senolytic drugs and their uses that are held by Mayo Clinic. This research has been reviewed by the Mayo Clinic Conflict of Interest Review Board and was conducted in compliance with Mayo Clinic conflict of interest policies.

Author Contributions

T.M. conceptualized this review, M.S. wrote the original manuscript, and G.K., T.T., and J.L.K. edited and reviewed it. All authors read and agreed to the final version.

References
 
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