No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
Evaluation of off-label rapamycin use to promote healthspan in 333 adults
Abstract
Rapamycin (sirolimus) is an FDA-approved drug with immune-modulating and growth-inhibitory properties. Preclinical studies have shown that rapamycin extends lifespan and healthspan metrics in yeast, invertebrates, and rodents. Several physicians are now prescribing rapamycin off-label as a preventative therapy to maintain healthspan. Thus far, however, there is limited data available on side effects or efficacy associated with use of rapamycin in this context. To begin to address this gap in knowledge, we collected data from 333 adults with a history of off-label use of rapamycin by survey. Similar data were also collected from 172 adults who had never used rapamycin. Here, we describe the general characteristics of a patient cohort using off-label rapamycin and present initial evidence that rapamycin can be used safely in adults of normal health status.
... Additionally, telemedicine services are beginning to launch that will increase accessibility to rapamycin. A recent observational study compared rapamycin users (n=333) to nonrapamycin users (n=172) [79]. Most users followed a weekly rapamycin dosing schedule, across a range of doses, for the purpose of "healthy longevity/antiaging." Mouth ulceration was the only self-reported adverse event (AE) that was greater in rapamycin vs. non-rapamycin users [79]. ...
... A recent observational study compared rapamycin users (n=333) to nonrapamycin users (n=172) [79]. Most users followed a weekly rapamycin dosing schedule, across a range of doses, for the purpose of "healthy longevity/antiaging." Mouth ulceration was the only self-reported adverse event (AE) that was greater in rapamycin vs. non-rapamycin users [79]. Interestingly, 50% of rapamycin users agreed that rapamycin improved their health while ~25-38% of rapamycin users felt younger, more confident, more energetic, and/or helped with other perceived health benefits. ...
... Interestingly, 50% of rapamycin users agreed that rapamycin improved their health while ~25-38% of rapamycin users felt younger, more confident, more energetic, and/or helped with other perceived health benefits. However, the remaining ~62-75% of rapamycin users did not perceive that rapamycin improved these domains [79]. Although difficult to assess without a doubleblinded, placebo-controlled study design, rapamycin users did report less abdominal cramps and pain, signs of depression, muscle tightness, anxiety, and eye pain. ...
Treatment with rapamycin, an inhibitor of the mechanistic Target Of Rapamycin Complex One (mTORC1) protein kinase, has been repeatedly demonstrated to extend lifespan and prevent or delay age-related diseases in diverse model systems. Concerns over the risk of potentially serious side effects in humans, including immunosuppression and metabolic disruptions, have cautiously limited the translation of rapamycin and its analogs as a treatment for aging associated conditions. During the last decade, we and others have developed a working model that suggests that while inhibition of mTORC1 promotes healthy aging, many of the negative side effects of rapamycin are associated with “off-target” inhibition of a second mTOR complex, mTORC2. Differences in the kinetics and molecular mechanisms by which rapamycin inhibits mTORC1 and mTORC2 suggest that a therapeutic window for rapamycin could be exploited using intermittent dosing schedules or alternative rapalogs that may enable more selective inhibition of mTORC1. However, the optimal dosing schedules and the long-term efficacy of such interventions in humans are unknown. Here, we highlight ongoing or upcoming clinical trials that will address outstanding questions regarding the safety, pharmacokinetics, pharmacodynamics, and efficacy of rapamycin and rapalogs on several clinically oriented outcomes. Results from these early phase studies will help guide the design of phase 3 clinical trials to determine whether rapamycin can be used safely to inhibit mTORC1 for the treatment and prevention of age-related diseases in humans.
... An extended list of diseases that can be treated with sirolimus can be found in Zuccato et al. and Gamberini et al. [19,32]. Moreover, sirolimus and mTOR inhibitors have been evaluated for the possible promotion of health span in adults [33]. ...
... An extended list of diseases that can be treated sirolimus can be found in Zuccato et al. and Gamberini et al. [19,32]. Moreover, siro and mTOR inhibitors have been evaluated for the possible promotion of health s adults [33]. ...
... A reduced immune response to anti-SARS-CoV-2 vaccination has been observed in organ recipients receiving immunosuppressant sirolimus-based treatment [33]. Therefore, there was some concern regarding the fact that monotherapy with sirolimus would reduce the antibody response after SARS-CoV-2 vaccination. ...
The β-thalassemias are a group of monogenic hereditary hematological disorders caused by deletions and/or mutations of the β-globin gene, leading to low or absent production of adult hemoglobin (HbA). For β-thalassemia, sirolimus has been under clinical consideration in two trials (NCT03877809 and NCT04247750). A reduced immune response to anti-SARS-CoV-2 vaccination has been reported in organ recipient patients treated with the immunosuppressant sirolimus. Therefore, there was some concern regarding the fact that monotherapy with sirolimus would reduce the antibody response after SARS-CoV-2 vaccination. In the representative clinical case reported in this study, sirolimus treatment induced the expected increase of fetal hemoglobin (HbF) but did not prevent the production of anti-SARS-CoV-2 IgG after vaccination with mRNA-1273 (Moderna). In our opinion, this case report should stimulate further studies on β-thalassemia patients under sirolimus monotherapy in order to confirm the safety (or even the positive effects) of sirolimus with respect to the humoral response to anti-SARS-CoV-2 vaccination. In addition, considering the extensive use of sirolimus for the treatment of other human pathologies (for instance, in organ transplantation, systemic lupus erythematosus, autoimmune cytopenia, and lymphangioleiomyomatosis), this case report study might be of general interest, as large numbers of patients are currently under sirolimus treatment.
... By repurposing such drugs for their potential to target the biology of aging and extend healthy longevity, clinical validation is fasttracked to permit a more immediate collection of application-specific efficacy data. Notable among these is rapamycin, which is widely used for its purported longevity and healthspan benefits within the prolongevity community [8]. While evidence supports a role for rapamycin in improving life-and health-spans in preclinical studies [9], little data exists on its clinical efficacy in normative aging humans. ...
... For example, Mannick et al. demonstrated that healthy elderly individuals taking 0.5 mg of a rapalog daily or 5 mg/week for 6 weeks mitigated age-related immune decline by enhancing the adaptive immune system's response to vaccination [39]. This supports our recent findings from a study of 333 low-dose rapamycin users indicating a high perceived QoL and improved health outcomes compared to non-users [8]. While such promising findings have encouraged some physicians to prescribe off-label rapamycin as a therapy to maintain healthspan, there are many open questions that require further study, particularly in a clinical setting. ...
... The rapalogs everolimus and temsirolimus are used to treat tuberous sclerosis complex (TSC) [11,12], which arises from TSC1/2 mutations that up-regulate the pathway, and some human cancers [13][14][15]. Rapamycin is also used off-label by some healthy adults for potential extension of health span and even life span [16]. Nonetheless, numerous authors express varying levels of concern about known side effects for both 2 rapamycin and rapalogs [9, [11][12][13][14][15], and the limited effectiveness of rapalogs against cancer has led to their being superseded by other modes of treatment in some cases [15,17] and to investigation of alternative means of inhibiting TOR activity [13,18]. ...
... Nonetheless, numerous authors express varying levels of concern about known side effects for both 2 rapamycin and rapalogs [9, [11][12][13][14][15], and the limited effectiveness of rapalogs against cancer has led to their being superseded by other modes of treatment in some cases [15,17] and to investigation of alternative means of inhibiting TOR activity [13,18]. In the context of aging, low or intermittent dosing of rapamycin is an option to minimize side effects [9,16]. In female w Dah Drosophila, treatment for 15-30 days in early adult life was sufficient to extend the median adult life span from 72 to 78-80 days [3]. ...
Various dietary supplements have been shown to extend the life span of Drosophila melanogaster, including several that promote autophagy, such as rapamycin and spermidine. The goal of the study presented here was to test numerous additional potential anti-aging supplements, primarily inhibitors of the target of rapamycin (TOR) and/or phosphatidylinositol 3-kinase (PI3K). Using a single, comparatively long-lived y w test strain, screening was performed in male flies supplemented either throughout adulthood or in a few cases beginning in middle or late adult life, with concentrations spanning 4-6 orders of magnitude in most cases. Supplementation with PP242 and deferiprone, an iron chelator, beginning in late adult life had no positive effect on life span. Lifelong supplementation with Ku-0063794, LY294002, PX-866-17OH, Torin2 and WYE-28 had no effect at any dose. Rapamycin, spermidine and wortmannin all had significant life-shortening effects at the highest doses tested. AZD8055, PI-103 hydrochloride and WYE-132 yielded slight beneficial effects at 1-2 doses, but only 100 nM AZD8055 was confirmed to have a minor (1.3%) effect in a replicate experiment, which was encompassed by other control groups within the same study. These compounds had no effect on fly fecundity (egg-laying) or fertility (development of progeny to adulthood), but equivalent doses of rapamycin abolished fertility. The solvent DMSO had no significant effect on life span at the concentrations used to solubilize most compounds in the fly medium, but it drastically curtailed both survival and fertility at higher concentrations. 2-hydroxypropyl-β-cyclodextrin also failed to extend the life span when provided throughout adulthood or beginning in mid-adult life. Collectively, the results suggest that inhibition of the TOR/PI3K pathway and autophagy through dietary intervention is not a straightforward anti-aging strategy in Drosophila, and that further extension of life is difficult in comparatively long-lived flies.
... The rapalogs everolimus and temsirolimus are used to treat tuberous sclerosis complex (TSC) [11,12], which arises from TSC1/2 mutations that up-regulate the pathway, and some human cancers [13][14][15]. Rapamycin is also used off-label by some healthy adults for the potential extension of health span and even life span [16]. Nonetheless, numerous authors express varying levels of concern about known side effects for both rapamycin and rapalogs [9,[11][12][13][14][15], and the limited effectiveness of rapalogs against cancer has led to their being superseded by other modes of treatment in some cases [15,17] and to the investigation of alternative means of inhibiting TOR activity [13,18]. ...
... Nonetheless, numerous authors express varying levels of concern about known side effects for both rapamycin and rapalogs [9,[11][12][13][14][15], and the limited effectiveness of rapalogs against cancer has led to their being superseded by other modes of treatment in some cases [15,17] and to the investigation of alternative means of inhibiting TOR activity [13,18]. In the context of aging, low or intermittent dosing of rapamycin is an option to minimize side effects [9,16]. In female w Dah Drosophila, treatment for 15-30 days in early adult life was sufficient to extend the median adult life span from 72 to 78-80 days [3]. ...
Various dietary supplements have been shown to extend the life span of Drosophila melanogaster, including several that promote autophagy, such as rapamycin and spermidine. The goal of the study presented here was to test numerous additional potential anti-aging supplements, primarily inhibitors of the target of rapamycin (TOR) and/or phosphatidylinositol 3-kinase (PI3K). Using a single, comparatively long-lived y w test strain, screening was performed in male flies supplemented either throughout adulthood or, in a few cases, beginning in middle or late adult life, with concentrations spanning 4–6 orders of magnitude in most cases. Supplementation with PP242 and deferiprone, an iron chelator, beginning in late adult life had no positive effect on life span. Lifelong supplementation with Ku-0063794, LY294002, PX-866-17OH, Torin2 and WYE-28 had no effect at any dose. Rapamycin, spermidine and wortmannin all had significant life-shortening effects at the highest doses tested. AZD8055, PI-103 hydrochloride and WYE-132 yielded slight beneficial effects at 1–2 doses, but only 100 nM AZD8055 was confirmed to have a minor (1.3%) effect in a replicate experiment, which was encompassed by other control groups within the same study. These compounds had no effect on fly fecundity (egg laying) or fertility (development of progeny to adulthood), but equivalent high doses of rapamycin abolished fertility. The solvent DMSO had no significant effect on life span at the concentrations used to solubilize most compounds in the fly medium, but it drastically curtailed both survival and fertility at higher concentrations. 2-Hydroxypropyl-β-cyclodextrin also failed to extend the life span when provided throughout adulthood or beginning in mid-adult life. Collectively, the results suggest that inhibition of the TOR/PI3K pathway and autophagy through dietary intervention is not a straightforward anti-aging strategy in Drosophila and that further extension of life is difficult in comparatively long-lived flies.
... Despite these unknowns, recent estimates suggest that over 2,000 people across the USA are currently taking rapamycin off-label [26,28]. Indeed, we recently described real-world data from a cohort of 333 participants using off-label rapamycin across a wide range of dosages, regimens, and formulations [29]. ...
... This study suggested rapamycin can be used safely in normative aging adults over extended periods of time with over one-third of rapamycin users self-reporting benefits in mood, pain, cognition, and fewer moderate to severe acute coronavirus disease 2019 (COVID-19) cases than non-users over the study time period [29]. While this initial evidence is promising, effective validation of rapamycin as a gerotherapeutic requires a deeper exploration of the bioavailability, kinetics, and therapeutic blood rapamycin levels that must be achieved in normative aging individuals for therapeutic effects. ...
Rapamycin, also known as sirolimus, has demonstrated great potential for application in longevity medicine. However, the bioavailability of generic and compounded rapamycin at longevity doses in normative aging individuals remains unknown. We conducted a retrospective, real-world study determining the 24-hour blood rapamycin levels to establish the relative bioavailability, dose-to-blood level linearity and inter-individual heterogeneity in a normative aging cohort. Participants received either compounded rapamycin (n = 23, dosages 5, 10, or 15 mg) or generic rapamycin (n= 44, dosages 2, 3, 6, or 8 mg) once per week, and were asked to obtain a sirolimus level blood draw 24 hours after dose self-administration. Similar blood rapamycin levels and a linear dose-to-blood level relationship were observed for both formulations, although a higher bioavailability per milligram of rapamycin was noted for the generic formulation (compounded averaged 0.287 (28.7%) bioavailability relative to generic rapamycin in (ng/mL) / mg rapamycin). While substantial inter-individual heterogeneity in blood rapamycin levels was observed for both formulations, repeat tests for individuals demonstrated high test-retest reliability. As we detected no significant association between bioavailability and measures of body mass index (BMI), sex, age, or length of time taking rapamycin, we suggest that individualized dosing and routine monitoring of blood rapamycin levels should be applied to ensure optimal longevity efficacy. Finally, we contextualize our data with a brief review of the literature on the currently available knowledge of rapamycin's bioavailability in normative aging populations, and provide implications for the clinical use of rapamycin in longevity medicine moving forward.
... To gather real-world data on individuals using rapamycin off-label for healthspan benefits, we recently published one of the first reports on 333 participants taking rapamycin off-label [19]. Along with documenting positive user experiences, our findings revealed that approximately 26% of rapamycin users reported oral health changes. ...
... The study is a secondary data-analysis of previously collected survey data regarding participants who used off-label rapamycin to improve their health span [19]. The original study used convenience sampling from those who met the appropriate criteria via physician recommendation, social media posts, word of mouth, and advertisement in rapamycin related groups. ...
Rapamycin (sirolimus) is an FDA approved drug with immune modulating properties that is being prescribed off-label in adults as a preventative therapy to maintain healthspan. We recently published one of the first reports on 333 adults with a history of off-label rapamycin use. Along with presenting evidence that rapamycin can be used safely in adults of normal health status, we discovered that about 26% of rapamycin users also reported oral health changes. Given the recent evidence highlighting the potential benefits of rapamycin and its derivatives in enhancing oral health, we conducted a secondary data analysis to profile the oral health of off-label rapamycin users, the true incidence of mouth sores, and present specific case studies of periodontal bone loss quantification using an FDA-approved artificial intelligence platform. Contrary to expected findings and previous literature, dimensions of rapamycin usage (such as length of use, dosage, and interval) were not found to be related to the incidence of mouth ulcers in rapamycin users. Notably, among rapamycin users, the most deleterious forms of ulcers were found to be infrequent and not statistically linked to rapamycin usage, with most rapamycin users having a common transient form of mouth ulcers. Additionally, we describe the general oral health outcomes of off-label rapamycin users and provide recommendations for individuals engaging in off-label rapamycin to be regularly checked by a dentist or an oral health care provider. This report was limited by being a secondary data analysis taken from survey data that focused on a more holistic health model. Future studies will use a focused survey that collects data on more dimensions of oral health outcomes while including questions on oral health for non-rapamycin-using participants.
... In a study where doses of 2-6 mg/day were given for 48 weeks, a significantly higher number of adverse events were reported in the treatment group than in the placebo group; specifically, infections were the most common adverse events, 41 in accordance with empirical data on the occurrence of bacterial infections in users of off-label rapamycin. 70 In addition, in the EXIST-3 study, which included everolimus-treated patients with tuberous sclerosis complex, aged 2-65 years, the core phase (18 weeks) 71 reported a tolerable safety profile and no deaths; however, the subsequent extended phase (48 weeks) of the same study reported two treatmentrelated deaths attributed to pneumonia and septic shock in younger patients (aged <6 years) after the data cutoff date. 72,73 Five deaths due to serious adverse events suspected to be related to everolimus occurred in a study including postmenopausal women with breast cancer treated with everolimus (10 mg) and exemestane (25 mg) daily for 48 weeks or until disease progression, unacceptable toxicity, death, or discontinuation for any other reason; the causes of death were pneumonitis, bilateral pneumonia, and disease progression. ...
... Some participants reported taking high doses of rapamycin (20 mg/week). 70 No serious adverse events were reported in this study. However, it is possible that participants who experienced serious adverse events did not participate in this survey. ...
... Rapamycin was employed by different research groups using different dosages in different mouse strains with similar effects in increasing lifespan [68]. Starting from these pre-clinical studies concurrently demonstrating that mTOR is a key modulator of aging (but also of age-related diseases), Kaeberlein et al. evaluated the potential of rapamycin use to promote health span in human adults [69]. They collected data from 333 adults with a history of off-label use of rapamycin and made a comparison with data collected from 172 adults who had never used rapamycin. ...
... They collected data from 333 adults with a history of off-label use of rapamycin and made a comparison with data collected from 172 adults who had never used rapamycin. The results obtained further supported interventional studies based on rapamycin to improve the quality of life, especially in the elderly [69]. ...
Simple Summary
In this review article, we present the fascinating story of sirolimus (rapamycin), a drug known to be able to induce fetal hemoglobin, and for this reason of great interest for the treatment of β-thalassemia. In fact, high levels of fetal hemoglobin have been demonstrated to be beneficial for β-thalassemia patients. The story began in 1964, with METEI (Medical Expedition to Easter Island, Rapa Nui). During this expedition, samples of the soil from different parts of the island were collected and, from this material, an antibiotic-producing microorganism (Streptomyces hygroscopicus) was identified and rapamycin was extracted from the mycelium with organic solvents. The story continued with the finding that rapamycin was a very active anti-bacterial and anti-fungal agent. In addition, rapamycin was demonstrated to inhibit the cell growth of tumor cell lines. More importantly, rapamycin was found to be an immunosuppressive agent applicable to prevent kidney rejection after transplant. More recently, rapamycin was found to be a potent inducer of fetal hemoglobin both in vitro using cell lines, in vivo using experimental mice, and in patients treated with this compound. These studies were the basis for proposing clinical trials on β-thalassemia patients.
Abstract
In this review article, we present the fascinating story of rapamycin (sirolimus), a drug able to induce γ-globin gene expression and increased production of fetal hemoglobin (HbF) in erythroid cells, including primary erythroid precursor cells (ErPCs) isolated from β-thalassemia patients. For this reason, rapamycin is considered of great interest for the treatment of β-thalassemia. In fact, high levels of HbF are known to be highly beneficial for β-thalassemia patients. The story of rapamycin discovery began in 1964, with METEI, the Medical Expedition to Easter Island (Rapa Nui). During this expedition, samples of the soil from different parts of the island were collected and, from this material, an antibiotic-producing microorganism (Streptomyces hygroscopicus) was identified. Rapamycin was extracted from the mycelium with organic solvents, isolated, and demonstrated to be very active as an anti-bacterial and anti-fungal agent. Later, rapamycin was demonstrated to inhibit the in vitro cell growth of tumor cell lines. More importantly, rapamycin was found to be an immunosuppressive agent applicable to prevent kidney rejection after transplantation. More recently, rapamycin was found to be a potent inducer of HbF both in vitro using ErPCs isolated from β-thalassemia patients, in vivo using experimental mice, and in patients treated with this compound. These studies were the basis for proposing clinical trials on β-thalassemia patients.
... Coating NPs with macrophage membranes allows Ma@(MnO₂+RAPA) to evade the immune detection. [40][41][42][43] The immune system recognizes the macrophage-like membrane as a "self" component, thus extending the circulation time of the nanoparticles in the bloodstream. Consequently, they have a higher chance of reaching the target site, the ischemic intestine, and reducing the exposure of the drug to non-target tissues, which minimizes drug toxicity and side effects. ...
Background
Intestinal ischemia-reperfusion (I/R) injury is a common and severe clinical issue. With high morbidity and mortality, it burdens patients and the healthcare system. Despite the efforts in medical research, current treatment options are unsatisfactory, urging novel therapeutic strategies. Oxidative stress and dysregulated autophagy play pivotal roles in the pathogenesis of I/R injury, damaging intestinal tissues and disrupting normal functions. The aim of this study is to fabricate macrophage membrane-coated manganese dioxide nanospheres loaded with rapamycin [Ma@(MnO₂+RAPA)] for alleviating intestinal I/R injury.
Methods
We engineered honeycomb MnO2 nanospheres coated with a macrophage membrane to act as a drug delivery system, encapsulating RAPA. In vitro OGD/R model in IEC-6 cells and in vivo mouse I/R injury models were used. Targeting ability was evaluated through in-vivo imaging system. Effects on cell viability, reactive oxygen species (ROS) levels, oxygen generation, inflammatory factors, apoptosis, autophagy, and biocompatibility were detected by methods such as MTT assay, fluorescence microscopy, ELISA kit, TUNEL assay, Western blotting and histological analysis.
Results
In this study, Ma@(MnO₂+RAPA) efficiently deliver RAPA to damaged tissues and exhibited good ROS-responsive release. Our data showed that Ma@(MnO₂+RAPA) reduced ROS, increased O₂, inhibited inflammation, and promoted autophagy while reducing apoptosis in IEC-6 cells. In a mouse I/R model, Ma@(MnO₂+RAPA) significantly reduced Chiu’s score, improved tight conjunction proteins, decreased apoptosis, reduced levels of inflammatory cytokines and oxidative stress. RAPA released from the Ma@(MnO₂+RAPA), enhanced the expression of autophagy-regulated proteins p62, Beclin-1, and LC3II. The biocompatibility and safety of Ma@(MnO₂+RAPA) were confirmed through histological analysis and biochemical detection in mice.
Conclusion
Our results demonstrated that Ma@(MnO₂+RAPA) alleviated intestinal I/R injury by reducing oxidative stress, promoting autophagy, and inhibiting inflammation. This study offers a potential therapeutic strategy for the treatment of intestinal ischemia-reperfusion injury.
... Intermittent rapamycin dosing strategies more selectively inhibit mTORC1 and extend lifespan in female mice while circumventing metabolic side effects through reduced mTORC2 inhibition, (Arriola Apelo, Neuman, et al., 2016;Arriola Apelo, Pumper, Baar, Cummings, & Lamming, 2016). Due to these exciting data, an increasing number of physically active adults are now prophylactically taking rapamycin, largely using intermittent dosing schedules, even though the impact of rapamycin on the health benefits of regular physical activity and human healthspan remain unknown (Kaeberlein et al., 2023). ...
An increasing number of physically active adults are taking the mTOR inhibitor rapamycin off label with the goal of extending healthspan. However, frequent rapamycin dosing disrupts metabolic health during sedentary conditions and abates the anabolic response to exercise. Intermittent once weekly rapamycin dosing minimizes many negative metabolic side effects of frequent rapamycin in sedentary mice. However, it remains unknown how different rapamycin dosing schedules impact metabolic, physical, and skeletal muscle adaptations to voluntary exercise training. Therefore, we tested the hypothesis that intermittent rapamycin (2mg/kg; 1x/week) would avoid detrimental effects on adaptations to 8 weeks of progressive weighted wheel running (PoWeR) in adult female mice (5-month-old) by evading the sustained inhibitory effects on mTOR signaling by more frequent dosing schedules (2mg/kg; 3x/week). Frequent but not intermittent rapamycin suppressed skeletal muscle mTORC1 signaling in PoWeR trained mice. PoWeR improved maximal exercise capacity, absolute grip strength, and myofiber hypertrophy with no differences between vehicle or rapamycin treated mice. Conversely, frequent and intermittent rapamycin treated mice had impaired glucose tolerance and insulin sensitivity compared to vehicle treated mice after PoWeR; however, intermittent rapamycin reduced the impact on glucose intolerance versus frequent rapamycin. Collectively, these data in adult female mice suggest that 1) rapamycin is largely compatible with the physical and skeletal muscle benefits of PoWeR and 2) the detrimental effects of rapamycin on body composition and glucose metabolism in the context of voluntary exercise may be reduced by intermittent dosing.
... IGF-I rapidly increased p70 S6 kinase activity and phosphorylation of 4E-BP1 in HSCs. The addition of rapamycin, a specific inhibitor of mTOR [34][35][36][37], prevented the upregulation of p70 S6 kinase and 4E-BP1 activities but not Akt and ERK1/2 activities in the presence of IGF-I. Furthermore, rapamycin abrogated IGF-I-induced increases in MMP-2 and MMP-9 expression and decreases in TIMP-1 expression. ...
Aim: The liver is the major source of circulating insulin-like growth factor (IGF)-I. Serum IGF-I levels are decreased in cirrhotic patients depending on severity. IGF-I administration was shown to improve liver function in patients and animal models of liver cirrhosis. However, controversy exists as to whether IGF-I stimulates or reduces fibrosis in the liver. The effects of IGF-I on collagen accumulation by hepatic stellate cells (HSCs) and its mechanisms were studied. Methods: A moderately activated HSC clone was used to determine the effect of IGF-I administration on the collagen production system, including its degradation. The intracellular signaling system was also studied in the cells stimulated by IGF-I. Results: IGF-I treatment reduced total amounts of collagen deposition in a dose-related manner, while DNA synthesis was stimulated by IGF-I. IGF-I treatment did not affect transforming growth factor-beta levels and type I procollagen mRNA expression. Expression of matrix metalloproteinase (MMP)-2 and -9 was upregulated, and tissue inhibitor of metalloproteinase (TIMP)-1 expression was downregulated by IGF-I treatment. Rapamycin, an inhibitor of mammalian target of rapamycin (mTOR), suppressed phosphorylation of 70 kDa ribosomal protein S6 kinase and eukaryotic initiation factor 4E-binding protein 1, and abrogated IGF-I-induced increase in MMP-2 and -9 expression and decrease in TIMP-1 expression. Conclusions: IGF-I has the ability to stimulate the collagen degradation system by HSCs through an mTOR-dependent pathway independent of modulation of the activation state of HSCs.
... Trials of rapamycin for dementia prophylaxis are ongoing [14], and one small randomized, placebocontrolled human trial (n = 115) showed effective prophylaxis against age-related pain in women after 48 weeks on a very low dose of rapamycin (p = 0.02) [15]. Optimal dose titration of rapamycin in the individual patient is even less well-studied than dose titration of lithium, with almost absent structured clinical data regarding side effects between doses typically used for healthy longevity patients (i.e., 1 mg) [16] and the higher doses (i.e., 3-5 mg) used for transplant rejection prophylaxis or systemic lupus erythematosus [17]. ...
... In addition, a recent systematic review of human studies supports that rapamycin or rapalog treatment can promote beneficial effects for the aging immune system [30]. In a survey study of off-label use of rapamycin (consisting primarily of once weekly dosing), there was a statistically significant increase in the incidence of mouth ulcers reported by rapamycin users compared to a control group, as well as a non-statistically significant trend toward higher infection rates [24]. These studies highlight that the FDA approval of rapamycin as an immunosuppressant is not sufficient to dismiss its use as a geroprotective agent, though concerns persist. ...
Inhibition of the target of rapamycin (TOR/mTOR) protein kinase by the drug rapamycin extends lifespan and health span across diverse species. However, rapamycin has potential off-target and side effects that warrant the discovery of additional TOR inhibitors. TOR was initially discovered in Saccharomyces cerevisiae (yeast) which contains two TOR paralogs, TOR1 and TOR2 . Yeast lacking functional Tor1 are viable but are hypersensitive to growth inhibition by TORC1 inhibitors, which is a property of yeast that can be exploited to identify TOR inhibitors. Additionally, yeast lacking FK506-sensitive proline rotamase ( FPR1 ) or containing a tor1-1 allele (a mutation in the Fpr1-rapamycin binding domain of Tor1) are robustly and selectively resistant to rapamycin and analogs that allosterically inhibit TOR activity via an FPR1 -dependent mechanism. To facilitate the identification of TOR inhibitors, we generated a panel of yeast strains with mutations in TOR pathway genes combined with the removal of 12 additional genes involved in drug efflux. This creates a drug-sensitive strain background that can sensitively and effectively identify TOR inhibitors. In a wild-type yeast strain background, 25 µM of Torin1 and 100 µM of GSK2126458 (omipalisib) are necessary to observe TOR1 -dependent growth inhibition by these known TOR inhibitors. In contrast, 100 nM Torin1 and 500 nM GSK2126458 (omipalisib) are sufficient to identify TOR1- dependent growth inhibition in the drug-sensitized background. This represents a 200-fold and 250-fold increase in detection sensitivity for Torin1 and GSK2126458, respectively. Additionally, for the TOR inhibitor AZD8055, the drug-sensitive system resolves that the compound results in TOR1- dependent growth sensitivity at 100 µM, whereas no growth inhibition is observed in a wild-type yeast strain background. Our platform also identifies the caffeine analog aminophylline as a TOR1 -dependent growth inhibitor via selective tor1 growth sensitivity. We also tested nebivolol, isoliquiritigenin, canagliflozin, withaferin A, ganoderic acid A, and taurine and found no evidence for TOR inhibition using our yeast growth-based model. Our results demonstrate that this system is highly effective at identifying compounds that inhibit the TOR pathway. It offers a rapid, cost-efficient, and sensitive tool for drug discovery, with the potential to expedite the identification of new TOR inhibitors that could serve as geroprotective and/or anti-cancer agents.
... Despite these unknowns, recent estimates suggest that thousands of people across the USA are currently taking rapamycin off-label at various longevity dosages [26,28]. Indeed, we recently described real-world data from a cohort of 333 participants using off-label rapamycin across a wide range of dosages, regimens, and formulations [29]. This study suggested rapamycin can be used safely in GeroScience Vol.: (0123456789) normative aging adults over extended periods of time with over one-third of rapamycin users self-reporting benefits in mood, pain, cognition, and fewer moderate to severe acute coronavirus disease 2019 (COVID-19) cases than non-users over the study time period. ...
Rapamycin, also known as sirolimus, has demonstrated great potential for application in longevity medicine. However, the dynamics of low-dose rapamycin bioavailability, and any differences in bioavailability for different formulations (e.g., compounded or commercial), remain poorly understood. We thus explored rapamycin bioavailability in two real-world cohorts to begin providing a foundational understanding of differences in effects between formulations over time. The small trial study cohort was utilized to explore the blood rapamycin levels of commercial ( n = 44, dosages 2, 3, 6, or 8 mg) or compounded ( n = 23, dosages 5, 10, or 15 mg) rapamycin 24 h after dose self-administration. Results suggested dose-to-blood level relationships were linear for both formulations, though compounded had a lower bioavailability per milligram of rapamycin (estimated to be 31.03% of the same dose of commercial). While substantial inter-individual heterogeneity in blood rapamycin levels was observed for both formulations, repeat tests for individuals over time demonstrated relative consistency. Extending exploration to 316 real-world longevity rapamycin users from the AgelessRx Observational Research Database produced similar findings, and additionally suggested that blood rapamycin levels peak after 2 days with gradual decline thereafter. Taken together, our findings suggest that individualized dosing and routine monitoring of blood rapamycin levels should be utilized to ensure optimal dosing and efficacy for healthy longevity.
... Blagosklonny's view remains controversial, as many researchers, including those working in the field of geroscience, emphasize the importance of validating efficacy and safety in humans before recommending rapamycin for longevity purposes [129]. Nevertheless, Blagosklonny's advocacy has catalyzed significant interest and momentum in aging research, sparking increased funding and studies into rapamycin's applications [32,58,64,71,72,95,110,120,[130][131][132][133][134][135][136][137][138][139][140][141][142][143][144]. By championing a "pragmatic use" approach, Blagosklonny has opened pathways for informed, personalized decision-making between patients and healthcare providers. ...
The untimely passing of Dr. Mikhail "Misha" Blagosklonny has left a lasting void in geroscience and oncology. This review examines his profound contributions, focusing on his pioneering the Hyperfunction Theory and his advocacy for rapamycin, an mTOR inhibitor, as a therapeutic agent for lifespan extension. Contrary to traditional damage-centric models, the Hyperfunction Theory rejects damage accumulation as the primary driver of aging. Instead, it redefines aging as a quasi-programmed process driven by the persistent, excessive activity of growth-promoting pathways beyond their developmental roles, leading to age-related pathologies. We explore how Blagosklonny's insights predict rapamycin's ability to decelerate aging by modulating excessive mTOR signaling, supported by empirical evidence across multiple physiological systems, including immune, cardiovascular, cognitive, and oncologic health. His forward-thinking approach, advocating for the cautious clinical use of rapamycin and suggesting personalized, preventive, and combination therapy strategies, has catalyzed interest in translational geroscience. This review synthesizes Blagosklonny's legacy, presenting rapamycin as a foundational pharmacological intervention with potential in managing age-related decline and extending healthspan, and underlines his impact in shifting aging research from theoretical frameworks to actionable interventions. Blagosklonny's work remains an enduring inspiration, paving the way toward treating aging as a modifiable condition.
... This approach is preferred primarily because of the significant adverse effects associated with systemic administration, including myelosuppression, paresthesias, gastrointestinal toxicity, and hepatic and renal impairment. [4][5][6] Therefore, there is considerable research interest in exploring safer natural products as alternative clinical agents for treating vascular restenosis. 7 Similar to animal cells, plant cells also release nanoscale vesicles known as plant-derived exosome-like nanovesicles (PELNs). ...
Exosome-like nanovesicles derived from Solanum lycopersicum show potential to inhibit vascular restenosis. The underlying mechanism involves activation of the Keap1/Nrf2 signaling pathway by miRNA164a/b-5p.
... Rapamycin has been shown to increase life span in mice, with relatively greater efficacy in females relative to males [44,45]. Rapamycin also shows favourable effects on ageing phenotypes in humans [46,47]. ...
The drugs mifepristone and rapamycin were compared for their relative ability to increase the life span of mated female Drosophila melanogaster. Titration of rapamycin indicated an optimal concentration of approximately 50 μM, which increased median life span here by average +81%. Meta-analysis of previous mifepristone titrations indicated an optimal concentration of approximately 466 μM, which increased median life span here by average +114%. Combining mifepristone with various concentrations of rapamycin did not produce further increases in life span, and instead reduced life span relative to either drug alone. Assay of maximum midgut diameter indicated that rapamycin was equally efficacious as mifepristone in reducing mating-induced midgut hypertrophy. The mito-QC mitophagy reporter is a previously described green fluorescent protein (GFP)–mCherry fusion protein targeted to the outer mitochondrial membrane. Inhibition of GFP fluorescence by the acidic environment of the autophagolysosome yields an increased red/green fluorescence ratio indicative of increased mitophagy. Creation of a multi-copy mito-QC reporter strain facilitated assay in live adult flies, as well as in dissected midgut tissue. Mifepristone was equally efficacious as rapamycin in activating the mito-QC mitophagy reporter in the adult female fat-body and midgut. The data suggest that mifepristone and rapamycin act through a common pathway to increase mated female Drosophila life span, and implicate increased mitophagy and decreased midgut hypertrophy in that pathway.
... Despite the fact that most studies about the effects on longevity haven´t been investigated in human, many people take rapamycin off-label [28]. Recently, Kaeberlein et al. performed an observational study comparing rapamycin users to non-rapamycin users for perceived health benefits and adverse events [128]. Mouth ulceration was the only self-reported significantly different adverse event in rapamycin users. ...
Background
Sex differences exist in the prevalence and progression of major glomerular diseases. Podocytes are the essential cell-type in the kidney which maintain the physiological blood-urine barrier, and pathological changes in podocyte homeostasis are critical accelerators of impairment of kidney function. However, sex-specific molecular signatures of podocytes under physiological and stress conditions remain unknown. This work aimed at identifying sexual dimorphic molecular signatures of podocytes under physiological condition and pharmacologically challenged homeostasis with mechanistic target of rapamycin (mTOR) inhibition. mTOR is a crucial regulator involved in a variety of physiological and pathological stress responses in the kidney and inhibition of this pathway may therefore serve as a general stress challenger to get fundamental insights into sex differences in podocytes.
Methods
The genomic ROSAmT/mG-NPHS2 Cre mouse model was used which allows obtaining highly pure podocyte fractions for cell-specific molecular analyses, and vehicle or pharmacologic treatment with the mTOR inhibitor rapamycin was performed for 3 weeks. Subsequently, deep RNA sequencing and proteomics were performed of the isolated podocytes to identify intrinsic sex differences. Studies were supplemented with metabolomics from kidney cortex tissues.
Results
Although kidney function and morphology remained normal in all experimental groups, RNA sequencing, proteomics and metabolomics revealed strong intrinsic sex differences in the expression levels of mitochondrial, translation and structural transcripts, protein abundances and regulation of metabolic pathways. Interestingly, rapamycin abolished prominent sex-specific clustering of podocyte gene expression and induced major changes only in male transcriptome. Several sex-biased transcription factors could be identified as possible upstream regulators of these sexually dimorphic responses. Concordant to transcriptomics, metabolomic changes were more prominent in males. Remarkably, high number of previously reported kidney disease genes showed intrinsic sexual dimorphism and/or different response patterns towards mTOR inhibition.
Conclusions
Our results highlight remarkable intrinsic sex-differences and sex-specific response patterns towards pharmacological challenged podocyte homeostasis which might fundamentally contribute to sex differences in kidney disease susceptibilities and progression. This work provides rationale and an in-depth database for novel targets to be tested in specific kidney disease models to advance with sex-specific treatment strategies.
... If a highquality RCT demonstrates that rapamycin triggers health benefits, it could be recommended to an individual as long as the biomarker context matches sufficiently well. In contrast, observational studies may face confounding variables; for instance, health-conscious individuals taking rapamycin and engaging in other health-seeking behaviors, complicating causal links to rapamycin's effects 13 . ...
The field of aging and longevity research is overwhelmed by vast amounts of data, calling for the use of Artificial Intelligence (AI), including Large Language Models (LLMs), for the evaluation of geroprotective interventions. Such evaluations should be correct, useful, comprehensive, explainable, and they should consider causality, interdisciplinarity, adherence to standards, longitudinal data and known aging biology. In particular, comprehensive analyses should go beyond comparing data based on canonical biomedical databases, suggesting the use of AI to interpret changes in biomarkers and outcomes. Our requirements motivate the use of LLMs with Knowledge Graphs and dedicated workflows employing, e.g., Retrieval-Augmented Generation. While naive trust in the responses of AI tools can cause harm, adding our requirements to LLM queries can improve response quality, calling for benchmarking efforts and justifying the informed use of LLMs for advice on longevity interventions.
... These lines of evidence might suggest the prolongevity effect of CR is mediated through the modulated gut microbiota. In addition to CR, owing to their roles in increasing the lifespan and healthspan in mice and healthspan in primates and humans, supplementation of metformin or rapamycin is also determined to be a promising prolongevity intervention (Kaeberlein et al., 2023;Kulkarni et al., 2020). Although less studied compared to CR, several studies have also supported that supplementation of metformin or rapamycin can remodel gut microbial composition with preservation of gut microbial homeostasis, an increase of gut microbial diversity, and high abundance of probiotics and SCFAs-producing bacteria as well as restoration of gut microbiota to a youth-like composition (Pavlo et al., 2023;Xu et al., 2020). ...
Recent progress on the underlying biological mechanisms of healthy longevity has propelled the field from elucidating genetic modification of healthy longevity hallmarks to defining mechanisms of gut microbiota influencing it. Importantly, the role of gut microbiota in the healthy longevity of the host may provide unprecedented opportunities to decipher the plasticity of lifespan on a natural evolutionary scale and shed light on using microbiota-targeted strategies to promote healthy aging and combat age-related diseases. This review investigates how gut microbiota affects healthy longevity, focusing on the mechanisms through which gut microbiota modulates it. Specifically, we focused on the ability of gut microbiota to enhance the intestinal barrier integrity, provide protection from inflammaging, ameliorate nutrientsensing pathways, optimize mitochondrial function, and improve defense against age-related diseases, thus participating in enhancing longevity and healthspan.
... The mTORC1 inhibitor rapamycin is known to mitigate the advancement of neurodegenerative disorders by bolstering autophagy, alleviating chronic inflammation, diminishing β-amyloid (Aβ) accumulation, and curbing the hyperphosphorylation of tau protein [39]. Nevertheless, rapamycin's adverse side effects, such as immune suppression, oral ulcers, and hyperglycemia, are linked to the inhibition of mTORC2 [40,41]. Therefore, the selective targeting of mTORC1 through specific drugs is of considerable importance [42]. ...
Background
Diabetes-associated cognitive impairment (DACI) poses a significant challenge to the self-management of diabetes, markedly elevating the risk of adverse complications. A burgeoning body of evidence implicates microglia as a central player in the pathogenesis of DACI.
Methods
We utilized proteomics to identify potential biomarkers in high glucose (HG)-treated microglia, followed by gene knockdown techniques for mechanistic validation in vitro and in vivo.
Results
Our proteomic analysis identified a significant upregulation of AKAP8L in HG-treated microglia, with concurrent dysregulation of autophagy and inflammation markers, making AKAP8L a novel biomarker of interest. Notably, the accumulation of AKAP8L was specific to HG-treated microglia, with no observed changes in co-cultured astrocytes or neurons, a pattern that was mirrored in streptozotocin (STZ)-induced diabetic mice. Further studies through co-immunoprecipitation and proximity ligation assay indicated that the elevated AKAP8L in HG-treated microglial cells interacts with the mTORC1. In the STZ mouse model, we demonstrated that both AKAP8L knockdown and rapamycin treatment significantly enhanced cognitive function, as evidenced by improved performance in the Morris water maze, and reduced microglial activation. Moreover, these interventions effectively suppressed mTORC1 signaling, normalized autophagic flux, mitigated neuroinflammation, and decreased pyroptosis.
Conclusions
Our findings highlight the critical role of AKAP8L in the development of DACI. By interacting with mTORC1, AKAP8L appears to obstruct autophagic processes and initiate a cascade of neuroinflammatory responses. The identification of AKAP8L as a key mediator in DACI opens up new avenues for potential therapeutic interventions.
... As Rapamycin is FDA-approved, it presents an appealing option for repurposing and off-label use in new therapeutic applications. A clinical study has indicated that a loading dose of 6-15 mg of Rapamycin, followed by daily doses of 2-5 mg, could be effective in treating patients with lymph-angioleiomyomatosis Kaeberlein et al., 2023). A more frequently used regimen for Rapamycin in promoting longevity is a weekly dose of 5-7 mg. ...
Autophagy is a crucial process involved in the degradation and recycling of cytoplasmic components which are transported to the lysosomal compartment by autophagosomes. Exosomes are an important means of communication and signaling in both normal and diseased states, and they have a significant role in the transmission and propagation of proteins, especially proteins implicated in neurodegenerative disorders. Autophagy may affect exosomal processing, but whether autophagy controls the release of aggregated β-amyloid and tau proteins in exosomes of Alzheimer disease (AD) is unclear. Therefore, our study aimed to investigate how modulating autophagy affects the exosomal release of these proteins in animal models of AD. Isolated exosomes from brain tissues of 48 male albino mice were divided into four groups (Negative control, LPS, rapamycin (RAPA), and chloroquine (CQ). LC3 I and LC3 II as well as Aβ and Tau proteins levels were determined. All mice undergone Neuro-behavioral tests (Morris Water maze test, Y-maze test, and Novel Object Recognition). Both LPS and CQ groups showed reduced expression levels of LC3 II and LC3 II/LC3 I ratio. In contrast, RAPA group showed a significant increase in both LC3-II expression and LC3-II/LC3-I ratio. The levels of both Aβ & Tau in exosomes of CQ & LPS groups were higher. While RAPA group showed a significant diminished levels of tau & Aβ proteins. In conclusion, our findings suggest that autophagy alterations in AD can influence the release of Aβ and tau proteins through exosomes, which may impact the spread of misfolded proteins in AD. These results highlight a potential innovative therapeutic approach for combating AD.
... Remarkably, rapamycin was a prediction of the hyperfunction theory of aging [10]. Rapamycin is increasingly used by thousands of people as an anti-aging drug (off-label) without side effects [12] https://rapamycintherapy.com/. ...
In January 2023, diagnosed with numerous metastases of lung cancer in my brain, I felt that I must accomplish a mission. If everything happens for a reason, my cancer, in particular, I must find out how metastatic cancer can be treated with curative intent. This is my mission now, and the reason I was ever born. In January 2023, I understood the meaning of life, of my life. I was born to write this article. In this article, I argue that monotherapy with targeted drugs, even when used in sequence, cannot cure metastatic cancer. However, preemptive combinations of targeted drugs may, in theory, cure incurable cancer. Also, I share insights on various topics, including rapamycin, an anti-aging drug that can delay but not prevent cancer, through my personal journey.
... Due to the profound impact of rapamycin on lifespan extension in model systems, there is significant interest among the general public and the scientific community in translating these insights to human application. A recent survey study of 333 self-reported healthy and physically active adults prophylactically taking rapamycin with the goal of healthy longevity/anti-aging indicated that a fraction of rapamycin users (25-38%) reported overall improvements to quality of life related to physical health, emotional wellbeing, brain function, and aches and pains [143]. Overall, the majority of participants reported that the most common dose was 6 mg once weekly. ...
Physical activity and several pharmacological approaches individually combat age-associated conditions and extend healthy longevity in model systems. It is tantalizing to extrapolate that combining geroprotector drugs with exercise could extend healthy longevity beyond any individual treatment. However, the current dogma suggests that taking leading geroprotector drugs on the same day as exercise may limit several health benefits. Here, we review leading candidate geroprotector drugs and their interactions with exercise and highlight salient gaps in knowledge that need to be addressed to identify if geroprotector drugs can have a harmonious relationship with exercise.
... Two of the most promising geroprotective (protective against adverse effects of aging) agents, metformin and rapamycin, are already being prescribed off-label to slow aging despite a paucity of evidence showing safety and efficacy. [4][5][6][7][8] Sodium-glucose cotransporter inhibitor/inhibition (SGLTi) works by blocking reuptake of filtered glucose in the proximal tubule of the nephron. These agents all block the SGLT2, but sotogliflozin also blocks SGLT1, which is primarily located in the intestinal wall. ...
... Based on "side" and therapeutic effect-avoidance, the most popular schedule of rapamycin for longevity is 5-7 mg once a week. The schedule is well tolerated and lacks side effects except of rare mouth sores [40]. It is based on the assumption that the intermittent schedule has fewer side effects than everyday doses. ...
Both individuals taking rapamycin, an anti-aging drug, and those not taking it will ultimately succumb to age-related diseases. However, the former, if administered disease-oriented dosages for a long time, may experience a delayed onset of such diseases and live longer. The goal is to delay a particular disease that is expected to be life-limiting in a particular person. Age-related diseases, quasi-programmed during development, progress at varying rates in different individuals. Rapamycin is a prophylactic anti-aging drug that decelerates early development of age-related diseases. I further discuss hyperfunction theory of quasi-programmed diseases, which challenges the need for the traditional concept of aging itself.
Companion dogs are a powerful model for aging research given their morphologic and genetic variability, risk for age-related disease, and habitation of the human environment. In addition, the shorter life expectancy of dogs compared to human beings provides a unique opportunity for an accelerated timeline to test interventions that might extend healthy lifespan. The Test of Rapamycin In Aging Dogs (TRIAD) randomized clinical trial is a parallel-group, double-masked, randomized, placebo-controlled, multicenter trial that will test the ability of rapamycin to prolong lifespan and improve several healthspan metrics in healthy, middle-aged dogs recruited from Dog Aging Project participants. Here, we describe the rationale, design, and goals of the TRIAD randomized clinical trial, the first rigorous test of a pharmacologic intervention against biological aging with lifespan and healthspan metrics as endpoints to be performed outside of the laboratory in any species.
Metabolic syndrome is a multifactorial process characterized by obesity, hypertension, hyperlipidemia, hyperglycemia, and insulin resistance, significantly increasing the risk of cardiovascular disease (CVD), type 2 diabetes mellitus, and other chronic health conditions. The prevalence of metabolic syndrome is rising globally due to sedentary lifestyles and poor dietary habits. Inflammatory skin diseases, including psoriasis, atopic dermatitis (AD), rosacea, acne vulgaris, lichen planus, acanthosis nigricans, androgenetic alopecia and hidradenitis suppurativa are closely linked to metabolic syndrome and mitochondrial dysfunction. These skin conditions are characterized by dysregulated immune responses and increased activation of inflammatory cytokines and immune cells. Additionally, mechanisms resulting in the induction of mitochondrial apoptosis influence the pathogenesis of these inflammatory skin diseases, while oxidative stress, inflammation and insulin resistance further interlink mitochondrial dysfunction and metabolic syndrome. Understanding the role of mitochondrial dysfunction in the pathogenesis of metabolic syndrome and inflammatory skin diseases is crucial for developing targeted therapies. Further research is needed to explore the contributing pathophysiology and develop strategies for preventing and treating these conditions. Genomic studies have also identified mutations associated with mitochondrial dysfunction and insulin resistance, offering potential targets for personalized therapies. Key words: Mitochondrial dysfunction, Metabolic syndrome, Insulin resistance, Autoinflammatory skin disease, Oxidative stress
Objective
Rapamycin, a powerful geroprotective drug, can have detrimental effects when administered chronically. We determined whether intermittent treatment of mice can reduce negative effects while maintaining benefits of chronic treatment.
Methods
From 6 months of age, male and female C3B6F1 hybrid mice were either continuously fed with 42 mg/kg rapamycin, or intermittently fed by alternating weekly feeding of 42 mg/kg rapamycin food with weekly control feeding. Survival of these mice compared to control animals was measured. Furthermore, longitudinal phenotyping including metabolic (body composition, GTT, ITT, indirect calorimetry) and fitness phenotypes (treadmil, rotarod, electrocardiography and open field) was performed. Organ specific pathology was assessed at 24 months of age.
Results
Chronic rapamycin treatment induced glucose intolerance, which was partially ameliorated by intermittent treatment. Chronic and intermittent rapamycin treatments increased lifespan equally in males, while in females chronic treatment resulted in slightly higher survival. The two treatments had equivalent effects on testicular degeneration, heart fibrosis and liver lipidosis. In males, the two treatment regimes led to a similar increase in motor coordination, heart rate and Q-T interval, and reduction in spleen weight, while in females, they equally reduced BAT inflammation and spleen weight and maintained heart rate and Q-T interval. However, other health parameters, including age related pathologies, were better prevented by continuous treatment.
Conclusions
Intermittent rapamycin treatment is effective in prolonging lifespan and reduces some side-effects of chronic treatment, but chronic treatment is more beneficial to healthspan.
Common chronic diseases represent the greatest driver of rising healthcare costs, as well as declining function, independence, and quality of life. Geroscience‐guided approaches seek to delay the onset and progression of multiple chronic conditions by targeting fundamental biological pathways of aging. This approach is more likely to improve overall health and function in old age than treating individual diseases, by addressing aging the largest and mostly ignored risk factor for the leading causes of morbidity in older adults. Nevertheless, challenges in repurposing existing and moving newly discovered interventions from the bench to clinical care have impeded the progress of this potentially transformational paradigm shift. In this article, we propose the creation of a standardized process for evaluating FDA‐approved medications for their geroscience potential. Criteria for systematically evaluating the existing literature that spans from animal models to human studies will permit the prioritization of efforts and financial investments for translating geroscience and allow immediate progress on the design of the next Targeting Aging with MEtformin (TAME)‐like study involving such candidate gerotherapeutics. Geroscience‐guided approaches seek to delay the onset and progression of chronic conditions by targeting the pathways of aging. This approach is likely to improve overall health in old age by addressing aging—the largest risk factor for the leading causes of morbidity. Here, we propose the creation of a standardized process for evaluating FDA‐approved drugs for their geroscience potential, permitting the prioritization of efforts and investments for translating geroscience discoveries.
Aging and obesity are common risk factors for numerous chronic pathologies, and the compounding effects of old age and increased adiposity pose a serious threat to public health. Starting from the assumption that aging and obesity may have shared underpinnings, we investigated the antiobesogenic potential of a successful longevity intervention, the mTORC1 inhibitor rapamycin. We find that rapamycin prevents diet-induced obesity in mice and increases the activity of C/EBP-β LAP, a transcription factor that regulates the metabolic shift to lipid catabolism observed in response to calorie restriction. Independent activation of C/EBP-β LAP with the antiretroviral drug adefovir dipivoxil recapitulates the anti-obesogenic effects of rapamycin without reducing signaling through mTORC1 and increases markers of fat catabolism in the liver. Our findings support a model that C/EBP-β LAP acts downstream of mTORC1 signaling to regulate fat metabolism and identifies a novel drug that may be exploited to treat obesity and decrease the incidence of age-related disease.
Age-related changes to histone levels are seen in many species. However, it is unclear whether changes to histone expression could be exploited to ameliorate the effects of ageing in multicellular organisms. Here we show that inhibition of mTORC1 by the lifespan-extending drug rapamycin increases expression of histones H3 and H4 post-transcriptionally, through eIF3-mediated translation. Elevated expression of H3/H4 in intestinal enterocytes in Drosophila alters chromatin organization, induces intestinal autophagy through transcriptional regulation, prevents age-related decline in the intestine. Importantly, it also mediates rapamycin-induced longevity and intestinal health. Histones H3/H4 regulate expression of an autophagy cargo adaptor Bchs (WDFY3 in mammals), increased expression of which in enterocytes mediates increased H3/H4-dependent healthy longevity. In mice, rapamycin treatment increases expression of histone proteins and Wdfy3 transcription , and alters chromatin organisation in the small intestine, suggesting the mTORC1-histone axis is at least partially conserved in mammals and may offer new targets for anti-ageing interventions.
Background
The COVID-19 pandemic highlights the need for therapies that improve immune function in older adults, including interferon (IFN)-induced antiviral immunity that declines with age. In a previous phase 2a trial, RTB101 (previously known as BEZ235), an oral mechanistic target of rapamycin (mTOR) inhibitor, was observed to increase IFN-induced antiviral gene expression and decrease the incidence of respiratory tract infections (RTIs) in older adults. Therefore, we aimed to investigate whether oral RTB101 upregulated IFN-induced antiviral responses and decreased the incidence of viral RTIs when given once daily for 16 weeks during winter cold and flu season.
Methods
We did a phase 2b and a phase 3 double-blind, randomised, placebo-controlled trial in adults aged at least 65 years enrolled in New Zealand, Australia, and the USA at 54 sites. In the phase 2b trial, patients were aged 65–85 years, with asthma, type 2 diabetes, chronic obstructive pulmonary disease (COPD), congestive heart failure, were current smokers, or had an emergency room or hospitalisation for an RTI within the past 12 months. In the phase 3 trial, patients were aged at least 65 years, did not have COPD, and were not current smokers. In the phase 2b trial, patients were randomly assigned to using a validated automated randomisation system to oral RTB101 5 mg, RTB101 10 mg once daily, or placebo in part 1 and RTB101 10 mg once daily, RTB101 10 mg twice daily, RTB101 10 mg plus everolimus once daily, or matching placebo in part 2. In the phase 3 trial, patients were randomly assigned to RTB101 10mg once daily or matching placebo. The phase 2b primary outcome was the incidence of laboratory-confirmed RTIs during 16 weeks of winter cold and influenza season and the phase 3 primary outcome was the incidence of clinically symptomatic respiratory illness defined as symptoms consistent with an RTI, irrespective of whether an infection was laboratory-confirmed. Patients, investigators, and sponsor were masked to treatment assignments. All patients who received at least part of one dose of study drug were included in the primary and safety analyses. The phase 2b trial was registered with ANZCTR, ACTRN12617000468325, ClinicalTrials.gov, NCT03373903, and the phase 3 trial was registered with ANZCTR, ACTRN12619000628145.
Findings
In the phase 2b trial, we recruited 652 participants in total between May 16, 2017, and Jan 10, 2018, 179 participants to part 1 of the study (randomly assigned 1:1:1 to RTB101 5 mg once daily [61 participants], RTB101 10 mg once daily [58 participants], or matching placebo [60 participants]) and 473 patients to part 2 (randomly assigned 1:1:1:1 to RTB101 10 mg once daily [118 participants], RTB101 10 mg twice daily [120 participants], RTB101 10 mg in combination with everolimus 0·1 mg daily [115 participants] or matching placebo [120 participants]). In our first prespecified statistical analysis of the primary efficacy endpoint for part 2 of the phase 2b trial efficacy of RTB101 10 mg in combination with everolimus 0·1 mg once daily compared with placebo did not meet statistical significance but, in our second prespecified analysis, which included data from part 1 and part 2, we found a statistically significant reduction in the proportion of patients who had one or more laboratory-confirmed RTIs in the RTB101 10 mg once daily treatment group (34 [19%] of 176) compared with the pooled placebo group (50 [28%] of 180; odds ratio [OR] 0·601 [90% CI 0·391–0·922]; p=0·02). In the phase 3 trial, we enrolled 1024 patients between May 7, 2018, and July 19, 2019. 513 (50·1%) participants were randomly assigned to RTB101 10 mg once daily and 510 (49·9%) to placebo. In the full analysis set of the phase 3 trial, RTB101 did not reduce the proportion of patients with clinically symptomatic respiratory illness (134 [26%] of 511 patients in the RTB101 treatment group vs 125 [25%] 510 patients in the placebo treatment group; OR 1·07 [90% CI 0·80–1·42]; p=0·65). In both trials, significantly more IFN-induced antiviral genes were upregulated in patients treated with RTB101 as compared with placebo. The study drug was found to be safe and well-tolerated across trials and treatment groups. Only one patient in the placebo group in the phase 3 trial had serious adverse events (nausea, fatigue, hyponatraemia, and arthralgia) which were considered related to study drug treatment. Three patients died in the phase 2b trial and one in the phase 3 trial but no deaths were considered related to study treatment.
Interpretation
The combined results indicate that low doses of the mTOR inhibitor RTB101 are well tolerated and upregulate IFN-induced antiviral responses in older adults. Further refinement of clinical trial endpoints and patient populations might be required to identify whether upregulation of IFN responses by mTOR inhibitors consistently decreases the incidence or severity of viral infections in older adults.
Funding
resTORbio and the National Institute on Aging.
Our previous study demonstrated rapamycin added to diet at 4 months of age had significantly less age-related outer hair cell loss in the basal half of the cochlea at 22 months of age compared to mice without rapamycin. The present study tested adding rapamycin to diet later in life, at 14 months of age, and added a longitudinal assessment of auditory brain stem response (ABR). The present study used UMHET4 mice, a 4 way cross in which all grandparental strains lack the Cdh23 753A allele that predisposes to early onset, progressive hearing loss. UMHET4 mice typically have normal hearing until 16–17 months, then exhibit threshold shifts at low frequencies/apical cochlea and later in more basal high frequency regions. ABR thresholds at 4, 12, 24, and 48 kHz were assessed at 12, 18, and 24 months of age and compared to baseline ABR thresholds acquired at 5 months of age to determine threshold shifts (TS). There was no TS at 12 months of age at any frequency tested. At 18 months of age mice with rapamycin added to diet at 14 months had a significantly lower mean TS at 4 and 12 kHz compared to mice on control diet with no significant difference at 24 and 48 kHz. At 24 months of age, the mean 4 kHz TS in rapamycin diet group was no longer significantly lower than the control diet group, while the 12 kHz mean remained significantly lower. Mean TS at 24 and 48 kHz in the rapamycin diet group became significantly lower than in the control diet group at 24 months. Hair cell counts at 24 months showed large loss in the apical half of most rapamycin and control diet mice cochleae with no significant difference between groups. There was only mild outer hair cell loss in the basal half of rapamycin and control diet mice cochleae with no significant difference between groups. The results show that a later life addition of rapamycin can decrease age-related hearing loss in the mouse model, however, it also suggests that this decrease is a delay/deceleration rather than a complete prevention.
COVID-19 disproportionately affects older people, with likelihood of severe complications and death mirroring that of other age-associated diseases. Inhibition of the mechanistic target of rapamycin complex 1 (mTORC1) has been shown to delay or reverse many age-related phenotypes, including declining immune function. Rapamycin (sirolimus) and rapamycin derivatives are US Food and Drug Administration-approved inhibitors of mTORC1 with broad clinical utility and well established dosing and safety profiles. Based on preclinical and clinical evidence, a strong case can be made for immediate large-scale clinical trials to assess whether rapamycin and other mTORC1 inhibitors can prevent COVID-19 infection in these populations and also to determine whether these drugs can improve outcomes in patients with severe COVID-19.
COVID-19 is not deadly early in life, but mortality increases exponentially with age, which is the strongest predictor of mortality. Mortality is higher in men than in women, because men age faster, and it is especially high in patients with age-related diseases, such as diabetes and hypertension, because these diseases are manifestations of aging and a measure of biological age. At its deepest level, aging (a program-like continuation of developmental growth) is driven by inappropriately high cellular functioning. The hyperfunction theory of quasi-programmed aging explains why COVID-19 vulnerability (lethality) is an age-dependent syndrome, linking it to other age-related diseases. It also explains inflammaging and immunosenescence, hyperinflammation, hyperthrombosis, and cytokine storms, all of which are associated with COVID-19 vulnerability. Anti-aging interventions, such as rapamycin, may slow aging and age-related diseases, potentially decreasing COVID-19 vulnerability.
Periodontal disease is an age-associated disorder clinically defined by periodontal bone loss, inflammation of the specialized tissues that surround and support the tooth, and microbiome dysbiosis. Currently, there is no therapy for reversing periodontal disease, and treatment is generally restricted to preventive measures or tooth extraction. The FDA-approved drug rapamycin slows aging and extends lifespan in multiple organisms, including mice. Here, we demonstrate that short-term treatment with rapamycin rejuvenates the aged oral cavity of elderly mice, including regeneration of periodontal bone, attenuation of gingival and periodontal bone inflammation, and revertive shift of the oral microbiome toward a more youthful composition. This provides a geroscience strategy to potentially rejuvenate oral health and reverse periodontal disease in the elderly.
Periodontal disease is an age-associated disorder clinically defined by periodontal bone loss, inflammation of the specialized tissues that surround and support the tooth, and microbiome dysbiosis. Currently, there is no therapy for reversing periodontal disease, and treatment is generally restricted to preventive measures or tooth extraction. The FDA-approved drug rapamycin slows aging and extends lifespan in multiple organisms, including mice. Here, we demonstrate that short-term treatment with rapamycin rejuvenates the aged oral cavity of elderly mice, including regeneration of periodontal bone, attenuation of gingival and periodontal bone inflammation, and revertive shift of the oral microbiome toward a more youthful composition. This provides a geroscience strategy to potentially rejuvenate oral health and reverse periodontal disease in the elderly.
IntroductionIn general, women more often experience metformin-associated adverse drug reactions (ADRs) than men.Objectives
We aimed to assess whether sex differences in reported ADRs for metformin are observed at different times after initiation, and to explore their concurrence with sex differences in the dose of metformin over time. This may guide future studies in assessing the involved mechanisms of sex differences in metformin-associated ADRs and may guide sex-specific management of ADRs in clinical practice.Methods
This study has a longitudinal design using data about patients initiating metformin collected by the Dutch National Pharmacovigilance Center Lareb through their Intensive Monitoring program. Patients were asked to complete a web-based questionnaire six times after initiation (i.e., at 2 weeks, 6 weeks and at 3, 6, 9, and 12 months). The outcome variables were the proportion of patients reporting any ADR (primary) and the dose of metformin (secondary). Sex differences in the proportions of ADRs and in the dose were tested at each assessment using Pearson Chi-Squared tests and Wilcoxon rank-sum tests, respectively. Using Bonferroni adjustment for multiple testing, a p value < 0.01 was considered statistically significant.ResultsThe number of included patients was 1712 (40.9% women). Women reported an ADR more often than men, which was statistically significant at the assessment at 2 weeks (34% vs 25%, p < 0.001), and 6 weeks (37% vs 28%, p = 0.001) after initiation. In general, women were reported to be prescribed a lower dose than men, which became statistically significant at the 9-month assessment (p < 0.01).Conclusions
Sex differences in reported ADRs were seen in the first weeks after metformin initiation, whereas statistically significant differences in self-reported prescribed dosing were observed after several months. Patients, in particular women, might benefit from being prescribed lower metformin doses at treatment initiation.
Caloric restriction (CR) increases the preservation of the ovarian primordial follicular reserve, which can potentially delay menopause. Rapamycin also increases preservation on the ovarian reserve, with similar mechanism to CR. Therefore, the aim of our study was to evaluate the effects of rapamycin and CR on metabolism, ovarian reserve, and gene expression in mice. Thirty-six female mice were allocated into three groups: control, rapamycin-treated (4 mg/kg body weight every other day), and 30% CR. Caloric restricted females had lower body weight (P < 0.05) and increased insulin sensitivity (P = 0.003), while rapamycin injection did not change body weight (P > 0.05) and induced insulin resistance (P < 0.05). Both CR and rapamycin females displayed a higher number of primordial follicles (P = 0.02 and 0.04, respectively), fewer primary, secondary, and tertiary follicles (P < 0.05) and displayed increased ovarian Foxo3a gene expression (P < 0.05). Despite the divergent metabolic effects of the CR and rapamycin treatments, females from both groups displayed a similar increase in ovarian reserve, which was associated with higher expression of ovarian Foxo3a.
Significant progress in defining the biology of aging, particularly in animal models, supports the geroscience hypothesis, which posits that by therapeutically targeting biological aging, the onset of multiple age-related diseases can be delayed 'en suite'. Geroscience investigators are preparing to test this hypothesis in humans for the first time. In this review, we describe development of large-scale clinical trials designed to determine whether multiple age-related health conditions can be simultaneously alleviated with interventions targeting the underlying biology of aging. We describe the rationale and collaborative, consensus building approach used to design the first aging outcome trial called Targeting Aging with Metformin. Through this case study, we outline features that could be more broadly extended to other geroscience-guided clinical trials, including a process for selecting biochemical and molecular markers of biologic age and we provide a perspective on the potential impact of clinical trials targeting aging.
Translational geroscience is an interdisciplinary field descended from basic gerontology that seeks to identify, validate, and clinically apply interventions to maximize healthy, disease-free lifespan. In this review, we describe a research pipeline for the identification and validation of lifespan extending interventions. Beginning in invertebrate model systems, interventions are discovered and then characterized using other invertebrate model systems (evolutionary translation), models of genetic diversity, and disease models. Vertebrate model systems, particularly mice, can then be utilized to validate interventions in mammalian systems. Collaborative, multi-site efforts, like the Interventions Testing Program (ITP), provide a key resource to assess intervention robustness in genetically diverse mice. Mouse disease models provide a tool to understand the broader utility of longevity interventions. Beyond mouse models, we advocate for studies in companion pets. The Dog Aging Project is an exciting example of translating research in dogs, both to develop a model system and to extend their healthy lifespan as a goal in itself. Finally, we discuss proposed and ongoing intervention studies in humans, unmet needs for validating interventions in humans, and speculate on how differences in survival among human populations may influence intervention efficacy. Keywords: Translational geroscience, Healthspan, Longevity, Aging, Rapamycin, Metformin, mTOR, Companion animals
Inhibition of the mechanistic target of rapamycin (mTOR) protein kinase extends life span and ameliorates aging-related pathologies including declining immune function in model organisms. The objective of this phase 2a randomized, placebo-controlled clinical trial was to determine whether low-dose mTOR inhibitor therapy enhanced immune function and decreased infection rates in 264 elderly subjects given the study drugs for 6 weeks. A low-dose combination of a catalytic (BEZ235) plus an allosteric (RAD001) mTOR inhibitor that selectively inhibits target of rapamycin complex 1 (TORC1) downstream of mTOR was safe and was associated with a significant (P = 0.001) decrease in the rate of infections reported by elderly subjects for a year after study drug initiation. In addition, we observed an up-regulation of antiviral gene expression and an improvement in the response to influenza vaccination in this treatment group. Thus, selective TORC1 inhibition has the potential to improve immune function and reduce infections in the elderly.
Rapalogs, inhibitors of mTORC1 (mammalian target of rapamycin complex 1), increase lifespan and delay age-related phenotypes in many species. However the molecular mechanisms have not been fully elucidated. We determined gene expression changes comparing 6 and 24-month old rats in the kidney, liver and skeletal muscle, and asked which of these changes were counter-regulated by a clinically-translatable (short-term and low-concentration) treatment, with a rapalog (RAD001). Surprisingly, RAD001 had a more pronounced effect on the kidney under this regimen in comparison to the liver or skeletal muscle. Histologic evaluation of kidneys revealed that the severity of chronic progressive nephropathy lesions was lower in kidneys from 24-month old rats treated with RAD001 compared with vehicle. In addition to other gene expression changes, c-Myc, which has been shown to regulate aging, was induced by aging in the kidney and counter-regulated by RAD001. RAD001 caused a decrease in c-Myc protein, which could be rescued by a proteasome inhibitor. These findings point to settings for use of mTORC1 inhibitors to treat age-related disorders, and highlight c-Myc regulation as one of the potential mechanisms by which mTORC1 inhibition is perturbing age-related phenotypes.
Age is the single greatest risk factor for most causes of morbidity and mortality in humans and their companion animals. As opposed to other model organisms used to study aging, dogs share the human environment, are subject to similar risk factors, receive comparable medical care, and develop many of the same age-related diseases humans do. In this study, 24 middle-aged healthy dogs received either placebo or a non-immunosuppressive dose of rapamycin for 10 weeks. All dogs received clinical and hematological exams before, during and after the trial and echocardiography before and after the trial. Our results showed no clinical side effects in the rapamycin treated group compared to dogs receiving the placebo. Echocardiography suggested improvement in both diastolic and systolic age-related measures of heart function (E/A ratio, fractional shortening, and ejection fraction) in the rapamycin-treated dogs. Hematological values remained within the normal range for all parameters studied; however, mean corpuscular volume (MCV) was decreased in rapamycin-treated dogs. Based on these results, we will test rapamycin on a larger dog cohort for a longer period of time in order to validate its effects on cardiac function and to determine whether it can significantly improve healthspan and reduce mortality in companion dogs.
Keywords: dogs, cardiac aging, rapamycin, echocardiogram, blood chemistry, healthspan, sirolimus
Rapamycin, an inhibitor of mTOR signaling, has been shown to reverse diastolic dysfunction in old mice in 10 weeks, highlighting its therapeutic potential for a poorly treatable condition. However, the mechanisms and temporal regulation of its cardiac benefits remain unclear. We show that improved diastolic function in old mice begins at 2-4 weeks, progressing over the course of 10-week treatment. While TORC1-mediated S6 phosphorylation and TORC2 mediated AKT and PKCα phosphorylation are inhibited throughout the course of treatment, rapamycin inhibits ULK phosphorylation and induces autophagy during just the first week of treatment, returning to baseline at two weeks and after. Concordantly, markers of mitochondrial biogenesis increase over the first two weeks of treatment and return to control levels thereafter. This transient induction of autophagy and mitochondrial biogenesis suggests that damaged mitochondria are replaced by newly synthesized ones to rejuvenate mitochondrial homeostasis. This remodeling is shown to rapidly reverse the age-related reduction in fatty acid oxidation to restore a more youthful substrate utilization and energetic profile in old isolated perfused hearts, and modulates the myocardial metabolomein vivo. This study demonstrates the differential and dynamic mechanisms following rapamycin treatment and highlights the importance of understanding the temporal regulation of rapamycin effects.
Age is the greatest risk factor for nearly every major cause of mortality in developed nations. Despite this, most biomedical
research focuses on individual disease processes without much consideration for the relationships between aging and disease.
Recent discoveries in the field of geroscience, which aims to explain biological mechanisms of aging, have provided insights
into molecular processes that underlie biological aging and, perhaps more importantly, potential interventions to delay aging
and promote healthy longevity. Here we describe some of these advances, along with efforts to move geroscience from the bench
to the clinic. We also propose that greater emphasis should be placed on research into basic aging processes, because interventions
that slow aging will have a greater effect on quality of life compared with disease-specific approaches.
Inhibition of the mammalian target of rapamycin (mTOR) pathway extends life span in all species studied to date, and in mice delays the onset of age-related diseases and comorbidities. However, it is unknown if mTOR inhibition affects aging or its consequences in humans. To begin to assess the effects of mTOR inhibition on human aging-related conditions, we evaluated whether the mTOR inhibitor RAD001 ameliorated immunosenescence (the decline in immune function during aging) in elderly volunteers, as assessed by their response to influenza vaccination. RAD001 enhanced the response to the influenza vaccine by about 20% at doses that were relatively well tolerated. RAD001 also reduced the percentage of CD4 and CD8 T lymphocytes expressing the programmed death-1 (PD-1) receptor, which inhibits T cell signaling and is more highly expressed with age. These results raise the possibility that mTOR inhibition may have beneficial effects on immunosenescence in the elderly.
Copyright © 2014, American Association for the Advancement of Science.
Mammalian aging can be delayed with genetic, dietary, and pharmacologic approaches. Given that the elderly population is dramatically increasing and that aging is the greatest risk factor for a majority of chronic diseases driving both morbidity and mortality, it is critical to expand geroscience research directed at extending human healthspan.
The "mechanistic target of rapamycin" (mTOR) is a central controller of growth, proliferation and/or motility of various cell-types ranging from adipocytes to immune cells, thereby linking metabolism and immunity. mTOR signaling is overactivated in obesity, promoting inflammation and insulin resistance. Therefore, great interest exists in the development of mTOR inhibitors as therapeutic drugs for obesity or diabetes. However, despite a plethora of studies characterizing the metabolic consequences of mTOR inhibition in rodent models, its impact on immune changes associated with the obese condition has never been questioned so far. To address this, we used a mouse model of high-fat diet (HFD)-fed mice with and without pharmacologic mTOR inhibition by rapamycin. Rapamycin was weekly administrated to HFD-fed C57BL/6 mice for 22 weeks. Metabolic effects were determined by glucose and insulin tolerance tests and by indirect calorimetry measures of energy expenditure. Inflammatory response and immune cell populations were characterized in blood, adipose tissue and liver. In parallel, the activities of both mTOR complexes (e. g. mTORC1 and mTORC2) were determined in adipose tissue, muscle and liver. We show that rapamycin-treated mice are leaner, have enhanced energy expenditure and are protected against insulin resistance. These beneficial metabolic effects of rapamycin were associated to significant changes of the inflammatory profiles of both adipose tissue and liver. Importantly, immune cells with regulatory functions such as regulatory T-cells (Tregs) and myeloid-derived suppressor cells (MDSCs) were increased in adipose tissue. These rapamycin-triggered metabolic and immune effects resulted from mTORC1 inhibition whilst mTORC2 activity was intact. Taken together, our results reinforce the notion that controlling immune regulatory cells in metabolic tissues is crucial to maintain a proper metabolic status and, more generally, comfort the need to search for novel pharmacological inhibitors of the mTOR signaling pathway to prevent and/or treat metabolic diseases.
Chronic caloric restriction (CR) and rapamycin inhibit the mechanistic target of rapamycin (mTOR) signaling, thereby regulating metabolism and suppressing protein synthesis. Caloric restriction or rapamycin extends murine lifespan and ameliorates many aging-associated disorders; however, the beneficial effects of shorter treatment on cardiac aging are not as well understood. Using a recently developed deuterated-leucine labeling method, we investigated the effect of short-term (10 weeks) CR or rapamycin on the proteomics turnover and remodeling of the aging mouse heart. Functionally, we observed that short-term CR and rapamycin both reversed the pre-existing age-dependent cardiac hypertrophy and diastolic dysfunction. There was no significant change in the cardiac global proteome (823 proteins) turnover with age, with a median half-life 9.1 days in the 5-month-old hearts and 8.8 days in the 27-month-old hearts. However, proteome half-lives of old hearts significantly increased after short-term CR (30%) or rapamycin (12%). This was accompanied by attenuation of age-dependent protein oxidative damage and ubiquitination. Quantitative proteomics and pathway analysis revealed an age-dependent decreased abundance of proteins involved in mitochondrial function, electron transport chain, citric acid cycle, and fatty acid metabolism as well as increased abundance of proteins involved in glycolysis and oxidative stress response. This age-dependent cardiac proteome remodeling was significantly reversed by short-term CR or rapamycin, demonstrating a concordance with the beneficial effect on cardiac physiology. The metabolic shift induced by rapamycin was confirmed by metabolomic analysis.
Target of Rapamycin (TOR) is involved in cellular and organismal aging. Rapamycin extends lifespan and delays cancer in mice. It is important to determine the minimum effective dose and frequency of its administration that still extends lifespan and prevents cancer. Previously we tested 1.5 mg/kg of rapamycin given subcutaneously 6 times per two weeks followed by a two-week break (1.5 × 6/bi-weekly schedule: total of 6 injections during a 4-week period). This intermittent treatment prolonged lifespan and delayed cancer in cancer-prone female FVB/N HER-2/neu mice. Here, the dose was decreased from 1.5 mg/kg to 0.45 mg/kg per injection. This treatment was started at the age of 2 months (group Rap-2), 4 months (Rap-4), and 5 months (Rap-5). Three control groups received the solvent from the same ages. Rapamycin significantly delayed cancer and decreased tumor burden in Rap-2 and Rap-5 groups, increased mean lifespan in Rap-4 and Rap-5 groups, and increased maximal lifespan in Rap-2 and Rap-5 groups. In Rap-4 group, mean lifespan extension was achieved without significant cancer prevention. The complex relationship between life-extension and cancer-prevention depends on both the direct effect of rapamycin on cancer cells and its anti-aging effect on the organism, which in turn prevents cancer indirectly. We conclude that total doses of rapamycin that are an order of magnitude lower than standard total doses can detectably extend life span in cancer-prone mice.
Rapamycin was found to increase (11% to 16%) the lifespan of male and female C57BL/6J mice most likely by reducing the increase in the hazard for mortality (i.e., the rate of aging) term in the Gompertz mortality analysis. To identify the pathways that could be responsible for rapamycin's longevity effect, we analyzed the transcriptome of liver from 25-month-old male and female mice fed rapamycin starting at 4 months of age. Few changes (<300 transcripts) were observed in transcriptome of rapamycin-fed males; however, a large number of transcripts (>4,500) changed significantly in females. Using multidimensional scaling and heatmap analyses, the male mice fed rapamycin were found to segregate into two groups: one group that is almost identical to control males (Rapa-1) and a second group (Rapa-2) that shows a change in gene expression (>4,000 transcripts) with more than 60% of the genes shared with female mice fed Rapa. Using ingenuity pathway analysis, 13 pathways were significantly altered in both Rapa-2 males and rapamycin-fed females with mitochondrial function as the most significantly changed pathway. Our findings show that rapamycin has a major effect on the transcriptome and point to several pathways that would likely impact the longevity.
The mechanistic target of rapamycin (mTOR) is a highly conserved protein that regulates growth and proliferation in response to environmental and hormonal cues. Broadly speaking, organisms are constantly faced with the challenge of interpreting their environment and making a decision between "grow or do not grow." mTOR is a major component of the network that makes this decision at the cellular level and, to some extent, the tissue and organismal level as well. Although overly simplistic, this framework can be useful when considering the myriad functions ascribed to mTOR and the pleiotropic phenotypes associated with genetic or pharmacological modulation of mTOR signaling. In this review, I will consider mTOR function in this context and attempt to summarize and interpret the growing body of literature demonstrating interesting and varied effects of mTOR inhibitors. These include robust effects on a multitude of age-related parameters and pathologies, as well as several other processes not obviously linked to aging or age-related disease.
Rapamycin, an inhibitor of mTOR kinase, increased median lifespan of genetically heterogeneous mice by 23% (males) to 26% (females) when tested at a dose three-fold higher than that used in our previous studies; maximal longevity was also increased in both sexes. Rapamycin increased lifespan more in females than in males at each dose evaluated, perhaps reflecting sexual dimorphism in blood levels of this drug. Some of the endocrine and metabolic changes seen in diet-restricted mice are not seen in mice exposed to rapamycin, and the pattern of expression of hepatic genes involved in xenobiotic metabolism is also quite distinct in rapamycin-treated and diet restricted mice, suggesting that these two interventions for extending mouse lifespan differ in many respects. This article is protected by copyright. All rights reserved.
Aging is a major risk factor for a large number of disorders and functional impairments. Therapeutic targeting of the aging process may therefore represent an innovative strategy in the quest for novel and broadly effective treatments against age-related diseases. The recent report of lifespan extension in mice treated with the FDA-approved mTOR inhibitor rapamycin represented the first demonstration of pharmacological extension of maximal lifespan in mammals. Longevity effects of rapamycin may, however, be due to rapamycin's effects on specific life-limiting pathologies, such as cancers, and it remains unclear if this compound actually slows the rate of aging in mammals. Here, we present results from a comprehensive, large-scale assessment of a wide range of structural and functional aging phenotypes, which we performed to determine whether rapamycin slows the rate of aging in male C57BL/6J mice. While rapamycin did extend lifespan, it ameliorated few studied aging phenotypes. A subset of aging traits appeared to be rescued by rapamycin. Rapamycin, however, had similar effects on many of these traits in young animals, indicating that these effects were not due to a modulation of aging, but rather related to aging-independent drug effects. Therefore, our data largely dissociate rapamycin's longevity effects from effects on aging itself.
Chronic treatment of mice with an enterically released formulation of rapamycin (eRapa) extends median and maximum life span, partly by attenuating cancer. The mechanistic basis of this response is not known. To gain a better understanding of thesein vivo effects, we used a defined preclinical model of neuroendocrine cancer, Rb1+/- mice. Previous results showed that diet restriction (DR) had minimal or no effect on the lifespan of Rb1+/- mice, suggesting that the beneficial response to DR is dependent on pRb1. Since long-term eRapa treatment may at least partially mimic chronic DR in lifespan extension, we predicted that it would have a minimal effect in Rb1+/- mice. Beginning at 9 weeks of age until death, we fed Rb1+/- mice a diet without or with eRapa at 14 mg/kg food, which results in an approximate dose of 2.24 mg/kg body weight per day, and yielded rapamycin blood levels of about 4 ng/ml. Surprisingly, we found that eRapa dramatically extended life span of both female and male Rb1+/- mice, and slowed the appearance and growth of pituitary and decreased the incidence of thyroid tumors commonly observed in these mice. In this model, eRapa appears to act differently than DR, suggesting diverse mechanisms of action on survival and anti-tumor effects. In particular the beneficial effects of rapamycin did not depend on the dose of Rb1.
Many experts in the biology of ageing believe that pharmacological interventions to slow ageing are a matter of 'when' rather than 'if'. A leading target for such interventions is the nutrient response pathway defined by the mechanistic target of rapamycin (mTOR). Inhibition of this pathway extends lifespan in model organisms and confers protection against a growing list of age-related pathologies. Characterized inhibitors of this pathway are already clinically approved, and others are under development. Although adverse side effects currently preclude use in otherwise healthy individuals, drugs that target the mTOR pathway could one day become widely used to slow ageing and reduce age-related pathologies in humans.
TOR (Target of Rapamycin) pathway accelerates cellular and organismal aging. Similar to rapamycin, p53 can inhibit the mTOR pathway in some mammalian cells. Mice lacking one copy of p53 (p53+/- mice) have an increased cancer incidence and a shorter lifespan. We hypothesize that rapamycin can delay cancer in heterozygous p53+/- mice. Here we show that rapamycin (given in a drinking water) extended the mean lifespan of p53+/- mice by 10% and when treatment started early in life (at the age less than 5 months) by 28%. In addition, rapamycin decreased the incidence of spontaneous tumors. This observation may have applications in management of Li-Fraumeni syndrome patients characterized by heterozygous mutations in the p53 gene.
The world continues to contend with successive waves of coronavirus disease 2019 (COVID-19), fueled by the emergence of viral variants. At the same time, persistent, prolonged and often debilitating sequelae are increasingly recognized in convalescent individuals, named ‘post-COVID-19 syndrome’ or ‘long-haul COVID’. Clinical symptomatology includes fatigue, malaise, dyspnea, defects in memory and concentration and a variety of neuropsychiatric syndromes as the major manifestations, and several organ systems can be involved. The underlying pathophysiological mechanisms are poorly understood at present. This Review details organ-specific sequelae of post-COVID-19 syndromes and examines the underlying pathophysiological mechanisms available so far, elaborating on persistent inflammation, induced autoimmunity and putative viral reservoirs. Finally, we propose diagnostic strategies to better understand this heterogeneous disorder that continues to afflict millions of people worldwide. It is increasingly obvious that individuals are experiencing post-COVID-19 syndromes, or ‘long-haul COVID’. Here, Merad and Mehandru eview currently available knowledge of the underlying pathophysiological mechanisms of these sequelae, elaborating on persistent inflammation, induced autoimmunity and putative viral reservoirs.
Cellular senescence and the hallmarks of aging contribute to age-related disease and dysfunction. The Unitary Theory of Fundamental Aging Mechanisms highlights the interdependence among the hallmarks of aging and suggests that by intervening in one fundamental aging process, most or all of the other processes could be impacted. Accumulation of senescent cells is associated with frailty, cardiovascular disease, obesity, diabetes, cognitive decline, and other age- and/or chronic disease-related disorders, suggesting that senescent cells are a target for intervention. Early preclinical data using senolytics, agents that target senescent cells, show promising results in several aging and disease models. The first in-human trials using the senolytic combination of Dasatinib and Quercetin indicated reduced senescent cell burden in adipose tissue of diabetic kidney disease patients and improved physical function in patients with idiopathic pulmonary fibrosis. Clinical trials with other senolytics, including the flavonoid Fisetin and BCL-xL inhibitors, are underway. These results from preclinical and early clinical trials illustrate the potential of senolytics to alleviate age-related dysfunction and diseases. However, multiple clinical trials across different aging and disease models are desperately needed. Parallel trials across institutions through the Translational Geroscience Network are facilitating testing to determine whether senolytics can be translated into clinical application.
Background:
Cell senescence is implicated in numerous age-related conditions. Drugs and nutritional supplements developed for a variety of purposes kill senescent cells (senolytics) or suppress their secretions (senomorphics). There is interest in repurposing such drugs to treat or prevent age-related diseases. To date, only small-scale preliminary trials have been conducted.
Methods:
At a workshop convened by the National Institute on Aging in August 2019, academic, industry and government scientists reviewed issues for Phase II trials of potentially repurposable drugs, or dietary supplements, to assess benefits and risks of their senolytic (killing senescent cells) or senomorphic (altering senescent cells' phenotypes) effects in treating or preventing age-related conditions.
Results:
Participants reviewed mechanisms and effects of cellular senescence, senolytics and senomorphics of several classes and their potential role in treating or preventing disease, modulators of the senescence-associated secretory phenotype (SASP), needs for senescence markers, data and specimen resources, infrastructure for planning trials, and potential effects on outcomes in older patients with multimorbidity and polypharmacy.
Conclusions:
Participants noted the importance of considering potential effects of candidate drugs on multiple aging outcomes. It is important to assess drugs' specificity for killing senescent cells and the balance between senolytic and cytotoxic effects. Markers of specific senescent cell types are needed to assess intervention responses. There are potential interactions with coexisting diseases and their treatments in older persons. Standardized measures could enhance comparisons and pooling of data. Additional characterization of human cell senescent phenotypes is needed for developing better and more specific senolytics and senomorphics.
The steady rise in life expectancy occurred across all developed countries during the last century. This demographic trend is, however, not accompanied by the same healthspan extension. This is since aging is the main risk factor for all age‐associated pathological conditions. Therefore, slowing the rate of aging is suggested to be more efficient in preventing or delaying age‐related diseases than treat them one by one, which is the common approach in a current pharmacological disease‐oriented paradigm. To date, a variety of medications designed to treat particular pathological conditions have been shown to exhibit pro‐longevity effects in different experimental models. Among them, there are many commonly used prescription and over‐the‐counter pharmaceuticals such as metformin, rapamycin, aspirin, statins, melatonin, vitamin antioxidants, etc. All of them are being increasingly investigated in preclinical and clinical trials with the aim of determine whether they have potential for extension of human healthspan. The results from these trials are frequently inconclusive and fall short of initial expectations, suggesting that innovative research ideas and additional translational steps are required to overcome obstacles for implementation of such approaches in clinical practice. In this review, recent advances and challenges in the field of repurposing widely used conventional pharmaceuticals to target the aging process are summarized and discussed.
Background:
It is important to understand patients' experiences of statin-associated adverse effects to potentially identify those at risk for stopping treatment.
Objective:
The goal of the STatin Adverse Treatment Experience survey was to describe patients' experiences after reporting ≥1 recent statin-associated adverse event and identify opportunities to improve adherence and outcomes.
Methods:
The survey was developed in 3 stages: qualitative item development, pilot evaluation of initial item performance, and quantitative evaluation using a large commercial sample. Respondents with self-reported high cholesterol who had taken a statin in the past 2 years and experienced ≥1 statin-associated symptom in the past 6 months were included (N = 1500).
Results:
Mean age was 58 years, 40.3% were men, and 43.2% had tried ≥2 statins. Many had clinical comorbidities associated with increased risk for cardiovascular disease (atherosclerotic cardiovascular disease, 22.5%; diabetes, 25.8%; hypertension, 56.0%). The most important patient-reported reasons for continuing current statin therapy (n = 1168; 77.9%) were avoiding a heart attack or stroke, lowering cholesterol, and doctor recommendation. Being bothered by and not being able to tolerate side effects were the main reasons respondents discontinued statins (n = 332; 22.1%). Respondents who discontinued statins reported significantly higher mean Symptom Severity (10.6 vs 8.7, P < .001) and Impact Severity scores (11.8 vs 9.8, P < .001) compared with those who continued.
Conclusion:
The STatin Adverse Treatment Experience survey highlights the importance of patients' adverse experiences with statins and how symptom and impact scores affect decisions to continue or discontinue therapy. These data provide a foundation to increase providers' awareness of statin tolerability from the patient's perspective and encourage benefit-risk discussions.
The FDA approved drug rapamycin increases lifespan in rodents and delays age-related dysfunction in rodents and humans. Nevertheless, important questions remain regarding the optimal dose, duration, and mechanisms of action in the context of healthy aging. Here we show that 3 months of rapamycin treatment is sufficient to increase life expectancy by up to 60% and improve measures of healthspan in middle-aged mice. This transient treatment is also associated with a remodeling of the microbiome, including dramatically increased prevalence of segmented filamentous bacteria in the small intestine. We also define a dose in female mice that does not extend lifespan, but is associated with a striking shift in cancer prevalence toward aggressive hematopoietic cancers and away from non-hematopoietic malignancies. These data suggest that a short-term rapamycin treatment late in life has persistent effects that can robustly delay aging, influence cancer prevalence, and modulate the microbiome.
Background:
A common class-specific toxicity of mammalian target of rapamycin (mTOR) inhibitors is stomatitis. Some patients experience a severe form of mTOR inhibitor-associated stomatitis (mIAS) that can have a negative effect on nutritional status, compromise quality of life, and potentially lead to nonadherence, reducing the efficacy of cancer therapy.
Objectives:
This article aims to address an unmet need for education about mIAS among oncology nurses and patients and to share findings about everolimus-related stomatitis from the SWISH trial.
Methods:
The authors reviewed the literature on mIAS and selected a case series of experiences to illustrate successes and clinical challenges that an oncology nurse might encounter when caring for patients with advanced breast cancer who may develop everolimus-related stomatitis.
Findings:
Recommendations are provided for oncology nurses to educate patients on prevention, early detection, monitoring, and management strategies to mitigate the incidence and severity of everolimus-related stomatitis.
Inhibition of the mechanistic target of rapamycin (mTOR) pathway by rapamycin (RAPA), an FDA-approved immunosuppressive drug used as a clinical therapy to prevent solid organ allograft rejection, enhances longevity in mice. Importantly, RAPA was efficacious even when initiated in relatively old animals, suggesting that mTOR inhibition could potentially slow the progression of aging-associated pathologies in older humans (Harrison et al., 2009; Miller et al., 2011). However, the safety and tolerability of RAPA in older human subjects have not yet been demonstrated. Towards this end, we undertook a placebo-controlled pilot study in 25 generally healthy older adults (aged 70-95 years); subjects were randomized to receive either 1 mg RAPA or placebo daily. Although three subjects withdrew, 11 RAPA and 14 controls completed at least 8 weeks of treatment and were included in the analysis. We monitored for changes that would indicate detrimental effects of RAPA treatment on basic metabolism, including both standard clinical laboratory assays (CBC, CMP, HbA1c) and oral glucose tolerance tests. In addition, we asked whether there were RAPA-induced modifications in parameters typically associated with aging. These included cognitive function which was assessed by three different tools: Executive Interview-25 (EXIT25); Saint Louis University Mental Status Exam (SLUMS); and Texas Assessment of Processing Speed (TAPS). In addition, physical performance was measured by handgrip strength and 40-foot timed walks. Lastly, changes in general parameters of healthy immune aging, including serum pro-inflammatory cytokine levels and blood cell subsets, were assessed. Five subjects reported potential adverse side effects; in the RAPA group, these were limited to facial rash (1 subject), stomatitis (1 subject) and gastrointestinal issues (2 subjects) whereas placebo treated subjects only reported stomatitis (1 subject). Although no other adverse events were reported, statistically significant decrements in several erythrocyte parameters including hemoglobin (HgB) and hematocrit (Hct) as well as in red blood cell count (RBC), red blood cell distribution width (RDW), mean corpuscular volume (MCV), and mean corpuscular hemoglobin (MCH) were observed in the RAPA-treatment group. None of these changes manifested clinically significant effects during the short duration of this study. Similarly, no changes were noted in any other clinical laboratory, cognitive, physical performance, or self-perceived health status measure over the study period. Immune parameters were largely unchanged as well, possibly due to the advanced ages of the cohort (70-93 years; mean age 80.5). RAPA-associated increases in a myeloid cell subset and in TREGS were detected, but changes in most other PBMC cell subsets were not statistically significant. Importantly, the OGTTs revealed no RAPA-induced increase in blood glucose concentration, insulin secretion, and insulin sensitivity. Thus, based on the results of our pilot study, it appears that short-term RAPA treatment can be used safely in older persons who are otherwise healthy; a larger trial with a larger samples size and longer treatment duration is warranted.
Interventions that target biological mechanisms of aging have great potential to enhance quality of life by delaying morbidity and mortality. The FDA-approved drug rapamycin is a compelling candidate for such an intervention. In a previous study, it was reported that 3 months of rapamycin treatment is sufficient to increase life expectancy and remodel the gut microbiome in aged mice. Transient treatment with rapamycin or a rapamycin derivative has also been shown to delay immune stem cell senescence and rejuvenate immune function in aged mice and elderly people. Periodontal disease is an important age-related disease involving altered immune function, pathological changes to the oral microbiome, and systemic inflammation. Periodontal disease is defined clinically by loss of alveolar bone and by connective tissue degeneration. Here, we describe significant alveolar bone loss during aging in two different mouse strain backgrounds and report that rapamycin treatment is sufficient to reverse age-associated periodontal disease in mice. Partial restoration of youthful levels of alveolar bone is observed in 22-month-old rapamycin-treated mice as rapidly as 8 weeks after initiation of treatment. To the best of our knowledge, this represents the first intervention shown to substantially prevent or reverse age-associated alveolar bone loss. These findings suggest the possibility that inhibition of mTOR with rapamycin or other pharmacological agents may be useful to treat a clinically relevant condition for which there is currently no effective treatment.
Age is by far the major risk factor for most chronic diseases. This has been common knowledge since time immemorial. Aging encompasses the biological changes most often seen as declines of function and increasing burden of disease. The close linkage of these two has led people to believe that aging, like age, is immutable. It is only recently that research into the basic molecular and cellular mechanisms of aging has led to potential interventions that increase lifespan and appear to increase healthspan, as well. Geroscience is an interdisciplinary field that aims to understand the relationship between the biology of aging and the biology of age-related diseases. The “geroscience hypothesis” posits that manipulation of aging will delay (in parallel) the appearance or severity of many chronic diseases because these diseases share the same underlying major risk factor (age). The hope is that this will lead to health improvements in the older population with perhaps greater efficiency than can be achieved through the successful cure and management of diseases of aging as they arise individually or as comorbidities.
Since the discovery that rapamycin, a small molecule inhibitor of the protein kinase mTOR (mechanistic target of rapamycin), can extend the lifespan of model organisms including mice, interest in understanding the physiological role and molecular targets of this pathway has surged. While mTOR was already well known as a regulator of growth and protein translation, it is now clear that mTOR functions as a central coordinator of organismal metabolism in response to both environmental and hormonal signals. This review discusses recent developments in our understanding of how mTOR signaling is regulated by nutrients and the role of the mTOR signaling pathway in key metabolic tissues. Finally, we discuss the molecular basis for the negative metabolic side effects associated with rapamycin treatment, which may serve as barriers to the adoption of rapamycin or similar compounds for the treatment of diseases of aging and metabolism.
Research on the biology of aging has accelerated rapidly in the last two decades. It is nowat the pointwhere translation of the findings into useful approaches to improve the health of the elderly population seems possible. In trying to fill that gap, a new field termed geroscience will be articulated here that attempts to identify the biological underpinnings for the agedependency of most chronic diseases. Herein, I will review the major conceptual issues leading to the formulation of geroscience as a field, as well as give examples of current areas of inquiry in which basic aging biology research could lead to therapeutic approaches to address age-related chronic diseases, not one at a time, but most of them in unison. © 2016 Cold Spring Harbor Laboratory Press; All rights reserved.
Rapamycin extends mouse life span, but the extent to which rapamycin prevents aging-associated changes in specific tissues
remains unclear. Stiffness increases and collagen turnover decreases in mouse tendon with aging; thus, our aim was to determine
the effect of long-term rapamycin treatment on the mechanical and structural properties of tendons from old mice. Tendons
were harvested from female UM-HET3 mice maintained on a standard chow diet for 4 (adult) or 22 (old) months or fed chow containing
polymer-encapsulated rapamycin (eRAPA) from 9 to 22 months of age (old RAPA). Stiffness was twofold higher for tendons of
old compared with adult mice, but in old RAPA mice, tendon stiffness was maintained at a value not different from that of
adults. Additionally, expression of collagen decreased, expression of matrix metalloproteinase-8 increased, and total hydroxyproline
content trended toward decreased levels in tendons of old eRAPA-fed mice compared with controls. Finally, age-associated calcification
of Achilles tendons and accompanying elevations in expression of chondrocyte and osteoblast markers were all lower in old
eRAPA-fed mice. These results suggest that long-term administration of rapamycin alters the molecular pathways responsible
for aging of tendon extracellular matrix, resulting in tissue that is structurally and mechanically similar to tendons in
adult mice.
Elucidating the signalling mechanisms by which obesity leads to impaired insulin action is critical in the development of therapeutic strategies for the treatment of diabetes. Recently, mice deficient for S6 Kinase 1 (S6K1), an effector of the mammalian target of rapamycin (mTOR) that acts to integrate nutrient and insulin signals, were shown to be hypoinsulinaemic, glucose intolerant and have reduced beta-cell mass. However, S6K1-deficient mice maintain normal glucose levels during fasting, suggesting hypersensitivity to insulin, raising the question of their metabolic fate as a function of age and diet. Here, we report that S6K1-deficient mice are protected against obesity owing to enhanced beta-oxidation. However on a high fat diet, levels of glucose and free fatty acids still rise in S6K1-deficient mice, resulting in insulin receptor desensitization. Nevertheless, S6K1-deficient mice remain sensitive to insulin owing to the apparent loss of a negative feedback loop from S6K1 to insulin receptor substrate 1 (IRS1), which blunts S307 and S636/S639 phosphorylation; sites involved in insulin resistance. Moreover, wild-type mice on a high fat diet as well as K/K A(y) and ob/ob (also known as Lep/Lep) mice-two genetic models of obesity-have markedly elevated S6K1 activity and, unlike S6K1-deficient mice, increased phosphorylation of IRS1 S307 and S636/S639. Thus under conditions of nutrient satiation S6K1 negatively regulates insulin signalling.
We examined the effect of rapamycin on the life span of a mouse model of type 2 diabetes, db/db mice. At 4 months of age, male and female C57BLKSJ-lepr
db/db mice (db/db) were placed on either a control diet, lacking rapamycin or a diet containing rapamycin and maintained on these diets over
their life span. Rapamycin was found to reduce the life span of the db/db mice. The median survival of male db/db mice fed the control and rapamycin diets was 349 and 302 days, respectively, and
the median survival of female db/db mice fed the control and rapamycin diets was 487 and 411 days, respectively. Adjusting for gender differences, rapamycin
increased the mortality risk 1.7-fold in both male and female db/db mice. End-of-life pathological data showed that suppurative inflammation was the main cause of death in the db/db mice, which is enhanced slightly by rapamycin treatment.
Aging is characterized by a progressive loss of physiological integrity, leading to impaired function and increased vulnerability to death. This deterioration is the primary risk factor for major human pathologies, including cancer, diabetes, cardiovascular disorders, and neurodegenerative diseases. Aging research has experienced an unprecedented advance over recent years, particularly with the discovery that the rate of aging is controlled, at least to some extent, by genetic pathways and biochemical processes conserved in evolution. This Review enumerates nine tentative hallmarks that represent common denominators of aging in different organisms, with special emphasis on mammalian aging. These hallmarks are: genomic instability, telomere attrition, epigenetic alterations, loss of proteostasis, deregulated nutrient sensing, mitochondrial dysfunction, cellular senescence, stem cell exhaustion, and altered intercellular communication. A major challenge is to dissect the interconnectedness between the candidate hallmarks and their relative contributions to aging, with the final goal of identifying pharmaceutical targets to improve human health during aging, with minimal side effects.
Rapamycin has been shown to extend lifespan in numerous model organisms including mice, with the most dramatic longevity effects reported in females. However, little is known about the functional ramifications of this longevity-enhancing paradigm in mammalian tissues. We treated 24-month old female C57BL/6J mice with rapamycin for 3 months, and determined health outcomes via a variety of non-invasive measures of cardiovascular, skeletal, and metabolic health for individual mice. We determined that while rapamycin has mild transient metabolic effects, there are significant benefits to late-life cardiovascular function with a reversal or attenuation of age-related changes in the heart. RNA-seq analysis of cardiac tissue after treatment indicated inflammatory, metabolic, and anti-hypertrophic expression changes in cardiac tissue as potential mechanisms mediating the functional improvement. Rapamycin treatment also resulted in beneficial behavioral, skeletal, and motor changes in these mice compared to those fed a control diet. From these findings, we propose that late-life rapamycin therapy not only extends the lifespan of mammals, but also confers functional benefits to a number of tissues, and mechanistically implicates an improvement in contractile function and anti-hypertrophic signaling in the aged heart with a reduction in age-related inflammation. This article is protected by copyright. All rights reserved.
Target of rapamycin inhibition by rapamycin feeding has previously been shown to extend life in genetically heterogeneous mice. To examine whether it similarly affected mouse health, we fed encapsulated rapamycin or a control diet to C57BL/6Nia mice of both sexes starting at 19 months of age. We performed a range of health assessments 6 and 12 months later. Rapamycin feeding significantly reduced mTOR activity in most but not all tissues. It also reduced total and resting metabolic rate during the light (inactive) phase of the light:dark cycle in females only but had no effect on spontaneous activity or metabolism during the dark (active) phase of either sex. Males only had less fragmented sleep when fed rapamycin, whereas stride length and rotarod performance were improved in both sexes. Survival was also improved by this late-life rapamycin feeding, and some pathological lesions were delayed. We found no adverse health consequences associated with rapamycin treatment.