Resveratrol increases anti-aging Klotho gene expression via the activating transcription factor 3/c-Jun complex-mediated signaling pathway

A possible important regulatory role of estrogen in obstructive sleep apnea hypoventilation syndrome

Obstructive sleep apnea-hypoventilation syndrome (OSAHS) is a prevalent clinical sleep breathing disorder that affects both pediatric and adult populations. If left untreated, OSAHS can induce or aggravate systemic dysfunction across multiple organ systems, with a particularly pronounced impact on cardiovascular health, thereby posing a substantial threat to overall human well-being. Notably, there exists a significant sex disparity in the prevalence and severity of OSAHS, with a higher incidence and greater severity observed in males. However, this disparity tends to diminish post-menopause. Research indicates that sex differences in OSAHS are associated with gonadal function, wherein estrogen exerts a protective effect by modulating pharyngeal muscle tone and mitigating oxidative stress. This regulatory role of estrogen partially reduces the incidence of OSAHS and attenuates its pathological impact. Conversely, OSAHS may adversely affect gonadal function, resulting in decreased estrogen levels, which can exacerbate the condition. This review examines the beneficial role of estrogen in the progression of OSAHS and explores the potential impact of OSAHS on estrogen levels.

Mechanistic and therapeutic role of NLRP3 inflammasome in the pathogenesis of Alzheimer's disease

Alzheimer's disease (AD), a progressive neurodegenerative disorder, has emerged as the most common form of dementia in the elderly. Several pathological hallmarks have been identified, including neuroinflammation. A comprehensive insight into the underlying mechanisms that can fuel the development of novel therapeutic approaches is necessary because of the alarmingly rapid increase in the frequency of incidence. Recently, NLRP3 inflammasome was identified as a critical mediator of neuroinflammation. Activation of nucleotide-binding domain (NOD)-like receptor protein 3 (NLRP3) inflammasome by amyloid, neurofibrillary tangles, impaired autophagy and endoplasmic reticulum stress, triggers the release of pro-inflammatory cytokines such as IL-1β and IL-18. Subsequently, these cytokines can promote neurodegeneration and cognitive impairment. It is well established that genetic or pharmacological ablation of NLRP3 alleviates AD-related pathological features in in vitro and in vivo models. Therefore, several synthetic and natural compounds have been identified that exhibit the potential to inhibit NLRP3 inflammasome and alleviate AD-associated pathology. The current review article will highlight the various mechanisms by which activation of NLRP3 inflammation occurs during Alzheimer's disease, and how it influences neuroinflammation, neurodegeneration and cognitive impairment. Moreover, we will summarise the different small molecules that possess the potential to inhibit NLRP3 and can pave the path for developing novel therapeutic interventions for AD.

Triiodothyronine enhances various forms of kidney-specific Klotho protein and suppresses the Wnt/β-catenin pathway: Insights from in-vitro, in-vivo and in-silico investigations

Age-related diseases are intricately linked to the molecular processes underlying aging, with the decline of the antiaging protein Klotho being a key factor. Investigating these processes is crucial for developing therapeutic strategies. The age-associated reduction in Klotho expression, coupled with a decline in the endocrine hormone triiodothyronine (T3), prompted a detailed exploration of their potential interplay. Our research, conducted through both in-vitro and in-vivo studies on BALB/c mice, unveiled a significant capacity of T3 to upregulate various forms of Klotho via ATF-3/p-c-Jun transcription factor. This effect was particularly noteworthy in aged individuals, where Klotho expression had waned compared to their younger counterparts. Importantly, T3 demonstrated a promising therapeutic impact in rejuvenating Klotho expression in this context. Further investigations elucidated the molecular mechanisms underlying T3's impact on aging-related pathways. In-vitro and in-vivo experiments established T3's ability to downregulate the Wnt/β-Catenin pathway by enhancing Klotho expression. In-silico analyses provided insights into Klotho's intricate role, showing its capacity to inhibit Wnt ligands such as Wnt3 and Wnt8a, consequently disrupting their interaction with the Wnt receptor. Additionally, T3 was found to downregulate kidney-specific GSK-3β expression through the augmentation of Klotho expression. The study also highlighted T3's role in maintaining calcium and phosphate homeostasis via Klotho. This comprehensive investigation not only sheds light on the intricate mechanisms governing aging processes but also presents promising avenues for therapeutic interventions targeting the Wnt/β-Catenin pathway implicated in various age-associated diseases.

Revisiting the mechanisms linking blood glucose to cognitive impairment: new evidence for the potential important role of klotho

Background

The association between blood glucose and cognition is controversial. Klotho is an anti-aging protein with neural protective effects. This study aimed to use a population-based study to disentangle the relationship between blood glucose levels and cognitive function in older adults, and to explore the role of klotho in it.

Methods

A total of 1445 eligible participants from National Health and Nutrition Examination Survey (NHANES) 2011-2014 were included in our study. Cognitive function was assessed by Digit Symbol Substitution Test (DSST) and categorized into four quartiles (Q1-Q4). General characteristics and laboratory test results including serum klotho concentration and blood glucose levels were collected. Associations of cognitive function and klotho levels with blood glucose concentrations were explored through multivariate linear regression models. Mediation models were constructed to figure out the mediating role of klotho.

Results

All three multivariate linear regression models showed a negative correlation between blood glucose and cognitive function. (Model 1, β=-0.149, 95%CI: -0.202,-0.096, p=0.001; Model 2, β=-0.116, 95%CI: -0.167,-0.065, p=0.001; Model 3, β=-0.007, 95%CI: -0.118,-0.023, p=0.003). Mediation analysis showed that klotho mediated the statistical association between blood glucose level and cognitive function with proportions (%) of 12.5.

Conclusion

Higher blood glucose levels are associated with poorer cognitive performance in non-diabetic older adults, partially mediated through lower klotho levels.

SIRT1 activated by AROS sensitizes glioma cells to ferroptosis via induction of NAD+ depletion-dependent activation of ATF3

Ferroptosis is a type of programmed cell death resulting from iron overload-dependent lipid peroxidation, and could be promoted by activating transcription factor 3 (ATF3). SIRT1 is an enzyme accounting for removing acetylated lysine residues from target proteins by consuming NAD+, but its role remains elusive in ferroptosis and activating ATF3. In this study, we found SIRT1 was activated during the process of RSL3-induced glioma cell ferroptosis. Moreover, the glioma cell death was aggravated by SIRT1 activator SRT2183, but suppressed by SIRT inhibitor EX527 or when SIRT1 was silenced with siRNA. These indicated SIRT1 sensitized glioma cells to ferroptosis. Furthermore, we found SIRT1 promoted RSL3-induced expressional upregulation and nuclear translocation of ATF3. Silence of ATF3 with siRNA attenuated RSL3-induced increases of ferrous iron and lipid peroxidation, downregulation of SLC7A11 and GPX4 and depletion of cysteine and GSH. Thus, SIRT1 promoted glioma cell ferroptosis by inducting ATF3 activation. Mechanistically, ATF3 activation was reinforced when RSL3-induced decline of NAD+ was aggravated by FK866 that could inhibit NAD + synthesis via salvage pathway, but suppressed when intracellular NAD+ was maintained at higher level by supplement of exogenous NAD+. Notably, the NAD + decline caused by RSL3 was enhanced when SIRT1 was further activated by SRT2183, but attenuated when SIRT1 activation was inhibited by EX527. These indicated SIRT1 promoted ATF3 activation via consumption of NAD+. Finally, we found RSL3 activated SIRT1 by inducing reactive oxygen species-dependent upregulation of AROS. Together, our study revealed SIRT1 activated by AROS sensitizes glioma cells to ferroptosis via activation of ATF3-dependent inhibition of SLC7A11 and GPX4.

Interaction of Klotho and sirtuins

OBJECTIVE

In this article, we review the articles that have reported the interaction between Klotho and sirtuins.

RECENT FINDINGS

Sirtuins are a family of histone deacetylase enzymes that are considered to be the main regulators of biological processes. This family is one of the essential factors for postponing aging and increasing the life span of organisms. Sirtuins play a role in regulating the function of various cellular processes such as cellular metabolism, oxidative stress, apoptosis, and inflammation. It has also been shown that various diseases are related to these enzymes. Klotho is an anti-aging protein that exists as a membrane protein as well as a soluble circulating form. The membrane type of this protein acts as a co-receptor of the FGF endocrine family. It has been shown that the Klotho gene is related to age-related diseases, including osteoporosis, coronary artery, brain diseases, diabetes, etc. At the same time, it is difficult to separate the actions of Klotho and endocrine FGFs. Several studies have shown that Klotho and sirtuins interact with each other at different regulatory levels. However, it is necessary to carry out more in-vivo investigations to create new windows towards the treatment or prevention of various diseases.

Programmed ageing: decline of stem cell renewal, immunosenescence, and Alzheimer's disease

The characteristic maximum lifespan varies enormously across animal species from a few hours to hundreds of years. This argues that maximum lifespan, and the ageing process that itself dictates lifespan, are to a large extent genetically determined. Although controversial, this is supported by firm evidence that semelparous species display evolutionarily programmed ageing in response to reproductive and environmental cues. Parabiosis experiments reveal that ageing is orchestrated systemically through the circulation, accompanied by programmed changes in hormone levels across a lifetime. This implies that, like the circadian and circannual clocks, there is a master 'clock of age' (circavital clock) located in the limbic brain of mammals that modulates systemic changes in growth factor and hormone secretion over the lifespan, as well as systemic alterations in gene expression as revealed by genomic methylation analysis. Studies on accelerated ageing in mice, as well as human longevity genes, converge on evolutionarily conserved fibroblast growth factors (FGFs) and their receptors, including KLOTHO, as well as insulin-like growth factors (IGFs) and steroid hormones, as key players mediating the systemic effects of ageing. Age-related changes in these and multiple other factors are inferred to cause a progressive decline in tissue maintenance through failure of stem cell replenishment. This most severely affects the immune system, which requires constant renewal from bone marrow stem cells. Age-related immune decline increases risk of infection whereas lifespan can be extended in germfree animals. This and other evidence suggests that infection is the major cause of death in higher organisms. Immune decline is also associated with age-related diseases. Taking the example of Alzheimer's disease (AD), we assess the evidence that AD is caused by immunosenescence and infection. The signature protein of AD brain, Aβ, is now known to be an antimicrobial peptide, and Aβ deposits in AD brain may be a response to infection rather than a cause of disease. Because some cognitively normal elderly individuals show extensive neuropathology, we argue that the location of the pathology is crucial - specifically, lesions to limbic brain are likely to accentuate immunosenescence, and could thus underlie a vicious cycle of accelerated immune decline and microbial proliferation that culminates in AD. This general model may extend to other age-related diseases, and we propose a general paradigm of organismal senescence in which declining stem cell proliferation leads to programmed immunosenescence and mortality.

Upstream and downstream regulators of Klotho expression in chronic kidney disease

Klotho is a critical protein that protects the kidney. Klotho is severely downregulated in chronic kidney disease (CKD), and its deficiency is implicated in the pathogenesis and progression of CKD. Conversely, an increase in Klotho levels results in improved kidney function and delays CKD progression, supporting the notion that modulating Klotho levels could represent a possible therapeutic strategy for CKD treatment. Nevertheless, the regulatory mechanisms responsible for the loss of Klotho remain elusive. Previous studies have demonstrated that oxidative stress, inflammation, and epigenetic modifications can modulate Klotho levels. These mechanisms result in a decrease in Klotho mRNA transcript levels and reduced translation, thus can be grouped together as upstream regulatory mechanisms. However, therapeutic strategies that aim to rescue Klotho levels by targeting these upstream mechanisms do not always result in increased Klotho, indicating the involvement of other regulatory mechanisms. Emerging evidence has shown that endoplasmic reticulum (ER) stress, the unfolded protein response, and ER-associated degradation also affect the modification, translocation, and degradation of Klotho, and thus are proposed to be downstream regulatory mechanisms. Here, we discuss the current understanding of upstream and downstream regulatory mechanisms of Klotho and examine potential therapeutic strategies to upregulate Klotho expression for CKD treatment.

Turning Back the Clock: A Retrospective Single-Blind Study on Brain Age Change in Response to Nutraceuticals Supplementation vs. Lifestyle Modifications

BACKGROUND

There is a growing consensus that chronological age (CA) is not an accurate indicator of the aging process and that biological age (BA) instead is a better measure of an individual's risk of age-related outcomes and a more accurate predictor of mortality than actual CA. In this context, BA measures the "true" age, which is an integrated result of an individual's level of damage accumulation across all levels of biological organization, along with preserved resources. The BA is plastic and depends upon epigenetics. Brain state is an important factor contributing to health- and lifespan.

METHODS AND OBJECTIVE

Quantitative electroencephalography (qEEG)-derived brain BA (BBA) is a suitable and promising measure of brain aging. In the present study, we aimed to show that BBA can be decelerated or even reversed in humans (N = 89) by using customized programs of nutraceutical compounds or lifestyle changes (mean duration = 13 months).

RESULTS

We observed that BBA was younger than CA in both groups at the end of the intervention. Furthermore, the BBA of the participants in the nutraceuticals group was 2.83 years younger at the endpoint of the intervention compared with their BBA score at the beginning of the intervention, while the BBA of the participants in the lifestyle group was only 0.02 years younger at the end of the intervention. These results were accompanied by improvements in mental-physical health comorbidities in both groups. The pre-intervention BBA score and the sex of the participants were considered confounding factors and analyzed separately.

CONCLUSIONS

Overall, the obtained results support the feasibility of the goal of this study and also provide the first robust evidence that halting and reversal of brain aging are possible in humans within a reasonable (practical) timeframe of approximately one year.

Effects of resveratrol supplementation on cardiac remodeling in hypertensive patients: a randomized controlled clinical trial

Resveratrol (RES) has been demonstrated to be protective in the cardiovascular system in animal studies, but the evidence is limited in humans. The purpose of the study was to evaluate the effect of RES supplementation on cardiac remodeling in patients with hypertension. Eighty Subjects were randomly divided into RES group (plus RES 400 mg/d in addition to conventional therapy, n = 43) and control group (conventional therapy, n = 37). The main outcomes of the study were changes within cardiac-remodeling parameters. Secondary outcomes were changes in anthropometric parameters, arterial stiffness parameters and mechanism indices. There was no statistically significant difference between the RES group and control group in terms of baseline characteristics. After 6 months, the RES group had smaller left atrial, lower E/e', higher left ventricular global longitudinal strain and lower biomarkers indicating cardiac fibrosis (expressed by decreases in procollagen type I C-peptide and galectin-3) compared to the control group. However, there was no significant difference in left ventricular structure between the two groups. Although the RES group showed a significant decrease in brachial-ankle pulse wave velocity compared to the pre-intervention value, the difference between the RES and the control groups was not obvious. What's more, compared with the control group, the serum levels of sirtuin3, superoxide dismutase and klotho were significantly increased in the RES group. In conclusion, RES supplementation can alleviate left atrial remodeling, improve left ventricular diastolic function and may alleviate cardiac fibrosis in hypertensive patients, and could be used as an adjunct to conventional therapies of hypertensive heart disease.

Roles of NAD+ in Acute and Chronic Kidney Diseases

Nicotinamide adenine dinucleotide (oxidized form, NAD⁺) is a critical coenzyme, with functions ranging from redox reactions and energy metabolism in mitochondrial respiration and oxidative phosphorylation to being a central player in multiple cellular signaling pathways, organ resilience, health, and longevity. Many of its cellular functions are executed via serving as a co-substrate for sirtuins (SIRTs), poly (ADP-ribose) polymerases (PARPs), and CD38. Kidney damage and diseases are common in the general population, especially in elderly persons and diabetic patients. While NAD⁺ is reduced in acute kidney injury (AKI) and chronic kidney disease (CKD), mounting evidence indicates that NAD⁺ augmentation is beneficial to AKI, although conflicting results exist for cases of CKD. Here, we review recent progress in the field of NAD⁺, mainly focusing on compromised NAD⁺ levels in AKI and its effect on essential cellular pathways, such as mitochondrial dysfunction, compromised autophagy, and low expression of the aging biomarker αKlotho (Klotho) in the kidney. We also review the compromised NAD⁺ levels in renal fibrosis and senescence cells in the case of CKD. As there is an urgent need for more effective treatments for patients with injured kidneys, further studies on NAD⁺ in relation to AKI/CKD may shed light on novel therapeutics.

Resveratrol attenuates cigarette smoke extract induced cellular senescence in human airway epithelial cells by regulating the miR-34a/SIRT1/NF-κB pathway

Chronic obstructive pulmonary disease (COPD) is characterized by accelerated lung aging. Smoking is the critical risk factor for COPD. Cellular senescence of airway epithelial cells is the cytological basis of accelerated lung aging in COPD, and the regulation of microRNAs (miRNAs) is the central epigenetic mechanism of cellular senescence. Resveratrol (Res) is a polyphenol with anti-aging properties. This study investigated whether Res attenuates cigarette smoke extract (CSE)-induced cellular senescence in human airway epithelial cells (BEAS-2B) through the miR-34a/SIRT1/nuclear factor-kappaB (NF-κB) pathway. BEAS-2B cells were treated with Res, CSE and transfected with miR-34a-5p mimics. Cellular senescence was evaluated by senescence -related β-galactosidase (SA-β-gal) staining and expression of senescence-related genes (p16, p21, and p53). The expressions of miR-34a-5p, SIRT1, and NF-κB p65 were examined using quantitative real time polymerase chain reaction and western blotting. The senescence-associated secretory phenotype (SASP) cytokines (IL-1β, IL-6, IL-8, TNF-α) were assessed by enzyme-linked immunosorbent assay. The binding between miR-34a-5p and SIRT1 was confirmed by dual-luciferase reporter assay. The results showed that CSE dose-dependently decreased cell viability and elevated cellular senescence, characterized by increased SA-β-gal staining and senescence-related gene expressions (p16, p21, and p53). Further, CSE dose-dependently increased the expression of miR-34a-5p and SASP cytokines (IL-1β, IL-6, IL-8, TNF-α) in BEAS-2B cells. Pretreatment with Res inhibited CSE-induced cellular senescence and secretion of SASP cytokines (IL-1β, IL-6, IL-8, TNF-α) in a dose-dependent manner. Moreover, Res reversed the CSE-induced down-regulation of SIRT1 and up-regulation of miR-34a-5p and NF-κB p65. SIRT1 is a target of miR-34a-5p. Overexpression of miR-34a-5p via transfection with miR-34a-5p mimic in BEAS-2B cells attenuated the inhibitory effect of Res on cellular senescence, accompanied by reversing the expression of SIRT1 and NF-κB p65. In conclusion, Res attenuated CSE-induced cellular senescence in BEAS-2B cells by regulating the miR-34a/SIRT1/NF-κB pathway, which may provide a new approach for COPD treatment.

ER stress in cardiac aging, a current view on the D-galactose model

Longitudinal studies are mandatory to study aging, however, they have certain drawbacks, for example, they require strict maintenance that is expensive given the breeding time (approximately 2 years) and with a low survival rate, having some animals to study very limitedly. In vitro studies provide useful and invaluable information on the cellular and molecular mechanisms that help understand the aging process to overcome these aspects. In particular, the model of premature aging induced by chronic exposure to D-galactose (D-Gal) offers a very similar picture to that which occurs in natural aging. This model mimics most of the old animals' cellular processes, such as oxidative stress, mitochondrial dysfunction, increased advanced glycation end products (AGEs), inflammation, and senescence-associated secretory phenotype (SASP). However, the information related to the endoplasmic reticulum (ER) stress and, subsequently, the unfolded protein response (UPR) is not fully elucidated. Therefore, this review brings together the most current information on this response in the D-Gal-induced aging model and its effect on cardiac structure and function.

Pathobiology of the Klotho Antiaging Protein and Therapeutic Considerations

The α-Klotho protein (henceforth denoted Klotho) has antiaging properties, as first observed in mice homozygous for a hypomorphic Klotho gene (kl/kl). These mice have a shortened lifespan, stunted growth, renal disease, hyperphosphatemia, hypercalcemia, vascular calcification, cardiac hypertrophy, hypertension, pulmonary disease, cognitive impairment, multi-organ atrophy and fibrosis. Overexpression of Klotho has opposite effects, extending lifespan. In humans, Klotho levels decline with age, chronic kidney disease, diabetes, Alzheimer’s disease and other conditions. Low Klotho levels correlate with an increase in the death rate from all causes. Klotho acts either as an obligate coreceptor for fibroblast growth factor 23 (FGF23), or as a soluble pleiotropic endocrine hormone (s-Klotho). It is mainly produced in the kidneys, but also in the brain, pancreas and other tissues. On renal tubular-cell membranes, it associates with FGF receptors to bind FGF23. Produced in bones, FGF23 regulates renal excretion of phosphate (phosphaturic effect) and vitamin D metabolism. Lack of Klotho or FGF23 results in hyperphosphatemia and hypervitaminosis D. With age, human renal function often deteriorates, lowering Klotho levels. This appears to promote age-related pathology. Remarkably, Klotho inhibits four pathways that have been linked to aging in various ways: Transforming growth factor β (TGF-β), insulin-like growth factor 1 (IGF-1), Wnt and NF-κB. These can induce cellular senescence, apoptosis, inflammation, immune dysfunction, fibrosis and neoplasia. Furthermore, Klotho increases cell-protective antioxidant enzymes through Nrf2 and FoxO. In accord, preclinical Klotho therapy ameliorated renal, cardiovascular, diabetes-related and neurodegenerative diseases, as well as cancer. s-Klotho protein injection was effective, but requires further investigation. Several drugs enhance circulating Klotho levels, and some cross the blood-brain barrier to potentially act in the brain. In clinical trials, increased Klotho was noted with renin-angiotensin system inhibitors (losartan, valsartan), a statin (fluvastatin), mTOR inhibitors (rapamycin, everolimus), vitamin D and pentoxifylline. In preclinical work, antidiabetic drugs (metformin, GLP-1-based, GABA, PPAR-γ agonists) also enhanced Klotho. Several traditional medicines and/or nutraceuticals increased Klotho in rodents, including astaxanthin, curcumin, ginseng, ligustilide and resveratrol. Notably, exercise and sport activity increased Klotho. This review addresses molecular, physiological and therapeutic aspects of Klotho.

Association between Dietary Inflammatory Index and serum Klotho concentration among adults in the United States

Background

Klotho is a hormone that emerges as an antiaging biomarker. However, the influence of the dietary pattern’s inflammatory potential on serum Klotho levels in human populations, especially in a general adult population, remains unknown. This study aimed to evaluate the relationship between the dietary inflammatory index (DII) and serum Klotho concentrations in individuals living in the United States. 

Methods 

From the 2007–2016 National Health and Nutrition Examination Survey database, data of participants who completed the full 24-h dietary history and underwent serum Klotho testing were analyzed. The association between DII and serum Klotho concentrations was estimated using multivariable linear regression models. We also conducted segmented regression model to examine the threshold effect of DII on serum Klotho concentrations.

Results

A total of 10,928 participants were included, with a median serum Klotho concentration of 805.20 pg/mL (IQR: 657.58 − 1001.12) and a median DII of 1.43 (IQR: − 0.16 − 2.82). Multivariable regression showed that participants with high DII scores were associated with low serum Klotho concentrations; when classifying DII into quartiles, after full adjustment, participants in DII quartiles 3 and 4 showed a decrease in Klotho levels (25.27 and 12.44 pg/ml, respectively) compared with those in the lowest quartile (quartile 1) (95% CI: − 41.80, − 8.73 and − 29.83, 4.95, respectively; P for trend = 0.036). The segmented regression showed that the turning point value of DII was − 1.82 (95% CI: − 2.32, − 0.80). A 1-unit increase in DII was significantly associated with lower Klotho levels by − 33.05 (95% CI: − 52.84, − 13.27; P = 0.001) when DII ranges from − 5.18 to − 1.82; however, the relationship was not significant when DII ranges from − 1.82 to 5.42 (P > 0.05). Furthermore, stratified analyses indicated that the observed associations between DII and serum Klotho concentration were stronger among those aged ≥ 56 years, those with normal weight, and those without chronic kidney disease (P for interaction = 0.003, 0.015, and 0.041, respectively).

Conclusions

In summary, we indicated that there was a dose–response relationship between DII and serum Klotho concentrations, suggesting that adhering to an anti-inflammatory diet has beneficial effects on aging and health by increasing the serum Klotho concentration.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12877-022-03228-8.

klotho deficiency linked to multiple premature-aging syndromes and a short lifespan

Proinflammatory cytokines, including TNF-α, IFN-γ, and IL-6, downregulate α-Klotho gene expression

Dietary Inflammatory Index was developed as a tool to determine the inflammatory potential of diet

We found that there was a dose–response relationship between DII and circulating concentrations of klotho in a nationally representative population of American adults.

Recent Advances in Epigenetics of Age-Related Kidney Diseases

Renal aging has attracted increasing attention in today’s aging society, as elderly people with advanced age are more susceptible to various kidney disorders such as acute kidney injury (AKI) and chronic kidney disease (CKD). There is no clear-cut universal mechanism for identifying age-related kidney diseases, and therefore, they pose a considerable medical and public health challenge. Epigenetics refers to the study of heritable modifications in the regulation of gene expression that do not require changes in the underlying genomic DNA sequence. A variety of epigenetic modifiers such as histone deacetylases (HDAC) inhibitors and DNA methyltransferase (DNMT) inhibitors have been proposed as potential biomarkers and therapeutic targets in numerous fields including cardiovascular diseases, immune system disease, nervous system diseases, and neoplasms. Accumulating evidence in recent years indicates that epigenetic modifications have been implicated in renal aging. However, no previous systematic review has been performed to systematically generalize the relationship between epigenetics and age-related kidney diseases. In this review, we aim to summarize the recent advances in epigenetic mechanisms of age-related kidney diseases as well as discuss the application of epigenetic modifiers as potential biomarkers and therapeutic targets in the field of age-related kidney diseases. In summary, the main types of epigenetic processes including DNA methylation, histone modifications, non-coding RNA (ncRNA) modulation have all been implicated in the progression of age-related kidney diseases, and therapeutic targeting of these processes will yield novel therapeutic strategies for the prevention and/or treatment of age-related kidney diseases.

The Role of Sirtuin 1 in Palmitic Acid-Induced Endoplasmic Reticulum Stress in Cardiac Myoblasts

Background: Lipotoxicity causes endoplasmic reticulum (ER) stress, leading to cell apoptosis. Sirtuin 1 (Sirt1) regulates gene transcription and cellular metabolism. In this study, we investigated the role of Sirt1 in palmitate-induced ER stress. Methods: Both H9c2 myoblasts and heart-specific Sirt1 knockout mice fed a palmitate-enriched high-fat diet were used. Results: The high-fat diet induced C/EBP homologous protein (CHOP) and activating transcription factor 4 (ATF4) expression in both Sirt1 knockout mice and controls. The Sirt1 knockout mice showed higher CHOP and ATF4 expression compared to those in the control. Palmitic acid (PA) induced ATF4 and CHOP expression in H9c2 cells. PA-treated H9c2 cells showed decreased cytosolic NAD⁺/NADH alongside reduced Sirt1′s activity. The H9c2 cells showed increased ATF4 and CHOP expression when transfected with plasmid encoding dominant negative mutant Sirt1. Sirt1 activator SRT1720 did not affect CHOP and ATF4 expression. Although SRT1720 enhanced the nuclear translocation of ATF4, the extent of the binding of ATF4 to the CHOP promoter did not increase in PA treated-H9c2 cells. Conclusion: PA-induced ER stress is mediated through the upregulation of ATF4 and CHOP. Cytosolic NAD⁺ concentration is diminished by PA-induced ER stress, leading to decreased Sirt1 activity. The Sirt1 activator SRT1720 promotes the nuclear translocation of ATF4 in PA-treated H9c2 cells.

Association of Energy and Macronutrients Intake with S-Klotho Plasma Levels in Middle-Aged Sedentary Adults: A Cross-Sectional Study

BACKGROUND

The ageing process can be influenced by energy intake and different macronutrients within the diet. The soluble form of the α-Klotho gene (called S-Klotho) is widely considered as a powerful anti-ageing biomarker.

OBJECTIVE

To analyze the association of energy, dietary energy density and macronutrient intake with S-Klotho plasma levels in middle-aged sedentary adults.

METHODS

A total of 72 (52.8% women) middle-aged sedentary adults (53.7 ± 5.2 years old) participated in the study. Energy and macronutrients intake (i.e. fat, carbohydrate and protein) were assessed using three non-consecutive 24-h recalls. S-Klotho plasma levels were measured in the Ethylenediaminetetraacetic acid (EDTA) plasma using a solid-phase sandwich enzyme-linked immunosorbent assay.

RESULTS

No association was observed between energy, dietary energy density or macronutrient intake and S-Klotho plasma levels in men (all P≥ 0.1). We found an inverse association between energy, protein and carbohydrate intake with S-Klotho plasma levels in women (all P≤0.043), which disappeared after controlling for age, lean mass index and sedentary time. An inverse association was observed between dietary energy density and S-Klotho plasma levels in women after controlling for covariates (all P≤0.05).

CONCLUSION

In summary, the present study showed an inverse association of dietary energy density with S-Klotho plasma levels in middle-aged women. In addition, our data suggest that the associations between energy and macronutrient intake could be highly dependent on lean mass and sedentary time.

Resveratrol (RV): A pharmacological review and call for further research

Resveratrol (RV) is a well-known polyphenolic compound in various plants, including grape, peanut, and berry fruits, which is quite famous for its association with several health benefits such as anti-obesity, cardioprotective neuroprotective, antitumor, antidiabetic, antioxidants, anti-age effects, and glucose metabolism. Significantly, promising therapeutic properties have been reported in various cancer, neurodegeneration, and atherosclerosis and are regulated by several synergistic pathways that control oxidative stress, cell death, and inflammation. Similarly, RV possesses a strong anti-adipogenic effect by inhibiting fat accumulation processes and activating oxidative and lipolytic pathways, exhibiting their cardioprotective effects by inhibiting platelet aggregation. The RV also shows significant antibacterial effects against various food-borne pathogens (Listeria, Campylobacter, Staphylococcus aureus, and E. coli) by inhibiting an electron transport chain (ETC) and F0F1-ATPase, which decreases the production of cellular energy that leads to the spread of pathogens. After collecting and analyzing scientific literature, it may be concluded that RV is well tolerated and favorably affects cardiovascular, neurological, and diabetic disorders. As such, it is possible that RV can be considered the best nutritional additive and a complementary drug, especially a therapeutic candidate. Therefore, this review would increase knowledge about the blend of RV as well as inspire researchers around the world to consider RV as a pharmaceutical drug to combat future health crises against various inhumane diseases. In the future, this article will be aware of discoveries about the potential of this promising natural compound as the best nutraceuticals and therapeutic drugs in medicine.

Comprehensive metabolite profile of multi-bioactive extract from tree peony (Paeonia ostii and Paeonia rockii) fruits based on MS/MS molecular networking

Tree peony seed, traditionally used for edible oil production, is rich in α-linolenic acid. However, little attention is given to the fruit by-products during seed oil production. The present work aimed to comprehensively investigate the phytochemical constituents and multiple biological activities of different parts of tree peony fruits harvested from Paeonia ostii and Paeonia rockii. 130 metabolites were rapidly identified through UPLC-Triple-TOF-MS on the basis of MS/MS molecular networking. Metabolite quantification was performed through the targeted approach of HPLC-ESI-QQQ-MS. Eight chemical markers were screened via principal component analysis (PCA) for distinguishing species and tissues. Interestingly, two dominant compounds, paeoniflorin and trans-resveratrol, are specially localized in seed kernel and seed coat, respectively. Unexpectedly, the extracts of fruit pod and seed coat showed significantly stronger antioxidant, antibacterial, and anti-neuroinflammatory activities than seed kernel from both P. ostii and P. rockii. Our work demonstrated that tree peony fruit is promising natural source of bioactive components and provided its potential utilization in food and pharmaceutical industries.

NAicotinamide retains Klotho expression and ameliorates rhabdomyolysis-induced acute kidney injury

OBJECTIVES

Acute kidney injury (AKI) is a severe complication of rhabdomyolysis that significantly increases mortality. Unfortunately, the therapeutic approach is limited. Inflammation plays a critical role in the pathogenesis of rhabdomyolysis-induced AKI, which is a potential therapeutic target. Nicotinamide, a form of vitamin B3 and a precursor of nicotinamide adenine dinucleotide, has been shown to have potent antiinflammation effects. Klotho is a tubular highly expressed renoprotective protein. Therefore, we explored the effect of nicotinamide on rhabdomyolysis-induced AKI and the underlying mechanisms.

METHODS

We intramuscularly injected glycerol to induce rhabdomyolysis, and intraperitoneally administrated nicotinamide to observe the effect on kidney injury. Interleukin-1 beta, tumor necrosis factor alpha, nuclear factor kappa B (NF-κB), and Klotho were determined by Western blot. Chromatin immunoprecipitation was used to assess the interaction of NF-κB, nuclear receptor corepressor, and histone deacetylase 1 with Klotho promoters. Small interfering RNA was used to evaluate the role of Klotho in nicotinamide-related renoprotection.

RESULTS

The results showed that nicotinamide attenuated renal pathologic morphology, kidney functional abnormalities, and kidney inflammatory response in rhabdomyolysis. Moreover, nicotinamide effectively blocked the recruitment of NF-κB, nuclear receptor corepressor, and histone deacetylase 1 to the promoter of Klotho, and preserved Klotho expression. More importantly, the renoprotection effect of nicotinamide was abrogated when Klotho was knocked down by small interfering RNA in rhabdomyolysis mice.

CONCLUSIONS

Our study demonstrated that Klotho preservation is essential for the renoprotection effect of nicotinamide, and provides a new preventive strategy for rhabdomyolysis-induced AKI.

Effect of resveratrol on the repair of kidney and brain injuries and its regulation on klotho gene in d-galactose-induced aging mice

Resveratrol is a natural polyhydroxy trans-stilbene product with many biological activities. One of the most striking biological activities of it is its anti-aging potential. Resveratrol can exhibit anti-aging activity via a variety of signaling pathways, however, the repair effect of it on kidney and brain injury in aging mice induced by d-galactose and its regulation on klotho gene expression have not been reported. Herein, the anti-aging activity of resveratrol and its effect on the repair of kidney and brain injuries in d-galactose-induced aging mice, as well as its regulation of klotho gene expression in these two tissues were investigated. The results indicated that resveratrol could significantly increase the aged cell viability and improve the pathological status of aging mice via inhibiting the formation of malondialdehyde and enhancing the activities of superoxide dismutase and catalase. The histological analysis suggested that resveratrol could remarkably repair the damages of kidney and brain tissues in aging mice. Moreover, PCR and western blot have shown that resveratrol could obviously increase the anti-aging klotho gene expression in the above tissues. The data in this paper further revealed and enriched the anti-aging mechanism of resveratrol, and the methods established in this study can be used as a tool to evaluate the anti-aging activity of drugs to a certain extent.

Epigenetic modifications of Klotho expression in kidney diseases

Developments of many renal diseases are substantially influenced by epigenetic modifications of numerous genes, mainly mediated by DNA methylations, histone modifications, and microRNA interference; however, not all gene modifications causally affect the disease onset or progression. Klotho is a critical gene whose repressions in various pathological conditions reportedly involve epigenetic regulatory mechanisms. Klotho is almost unexceptionally repressed early after acute or chronic renal injuries and its levels inversely correlated with the disease progression and severity. Moreover, the strategies of Klotho derepression via epigenetic modulations beneficially change the pathological courses both in vitro and in vivo. Hence, Klotho is not only considered a biomarker of the renal disease but also a potential or even an ideal target of therapeutic epigenetic intervention. Here, we summarize and discuss studies that investigate the Klotho repression and intervention in renal diseases from an epigenetic point of view. These information might shed new sights into the effective therapeutic strategies to prevent and treat various renal disorders.

The pleiotropic neuroprotective effects of resveratrol in cognitive decline and Alzheimer's disease pathology: From antioxidant to epigenetic therapy

While the elderly segment of the population continues growing in importance, neurodegenerative diseases increase exponentially. Lifestyle factors such as nutrition, exercise, and education, among others, influence ageing progression, throughout life. Notably, the Central Nervous System (CNS) can benefit from nutritional strategies and dietary interventions that prevent signs of senescence, such as cognitive decline or neurodegenerative diseases such as Alzheimer's disease and Parkinson's Disease. The dietary polyphenol Resveratrol (RV) possesses antioxidant and cytoprotective effects, producing neuroprotection in several organisms. The oxidative stress (OS) occurs because of Reactive oxygen species (ROS) accumulation that has been proposed to explain the cause of the ageing. One of the most harmful effects of ROS in the cell is DNA damage. Nevertheless, there is also evidence demonstrating that OS can produce other molecular changes such as mitochondrial dysfunction, inflammation, apoptosis, and epigenetic modifications, among others. Interestingly, the dietary polyphenol RV is a potent antioxidant and possesses pleiotropic actions, exerting its activity through various molecular pathways. In addition, recent evidence has shown that RV mediates epigenetic changes involved in ageing and the function of the CNS that persists across generations. Furthermore, it has been demonstrated that RV interacts with gut microbiota, showing modifications in bacterial composition associated with beneficial effects. In this review, we give a comprehensive overview of the main mechanisms of action of RV in different experimental models, including clinical trials and discuss how the interconnection of these molecular events could explain the neuroprotective effects induced by RV.

Hydroxypropyl-β-Cyclodextrin-Complexed Resveratrol Enhanced Antitumor Activity in a Cervical Cancer Model: In Vivo Analysis

Trans-resveratrol (RES) exhibits a wide range of biological activities. Various methodological approaches have been established to improve the pharmacokinetic properties of RES. Moreover, additional in vivo studies are required to support clinical application. In this study, RES/HP-β-CD (RHSD) inclusion complex was prepared and characterized by FTIR, PXRD, DSC and NMR data. The effect and potential mechanism of RHSD against cervical cancer were investigated in a mouse xenograft tumor model by qPCR assay, Western blot assay, and immunohistochemical assay. Results showed that RHSD significantly decreased tumor growth compared with free RES, while the effect of preventing tumor growth was more prominent in vivo. Notably, RHSD could inhibit tumor development by suppressing the expression of HPV E6 and E7 oncogenes and upregulating P53 and Rb1 protein in cervical cancer. These findings demonstrated that RHSD was safe and potential for development of a new oral administration drug to treat cervical cancer.

Impact of Polyphenolic-Food on Longevity: An Elixir of Life. An Overview

Aging and, particularly, the onset of age-related diseases are associated with tissue dysfunction and macromolecular damage, some of which can be attributed to accumulation of oxidative damage. Recently, growing interest has emerged on the beneficial effects of plant-based diets for the prevention of chronic diseases including obesity, diabetes, and cardiovascular disease. Several studies collectively suggests that the intake of polyphenols and their major food sources may exert beneficial effects on improving insulin resistance and related diabetes risk factors, such as inflammation and oxidative stress. They are the most abundant antioxidants in the diet, and their intake has been associated with a reduced aging in humans. Polyphenolic intake has been shown to be effective at ameliorating several age-related phenotypes, including oxidative stress, inflammation, impaired proteostasis, and cellular senescence, both in vitro and in vivo. In this paper, effects of these phytochemicals (either pure forms or polyphenolic-food) are reviewed and summarized according to affected cellular signaling pathways. Finally, the effectiveness of the anti-aging preventive action of nutritional interventions based on diets rich in polyphenolic food, such as the diets of the Blue zones, are discussed.

Activating transcription factor 3 involved in Pseudomonas aeruginosa PAO1-induced macrophage senescence

Pseudomonas aeruginosa (PA) is one of the most prevalent pathogens that cause nosocomial infection in critical patients. Previously, we reported PA induced macrophage to senescence under the circumstance of infection. As an oxidative stress responsiveness element, activating transcription factor 3 (ATF3) might be involved in the macrophage senescence process. To test this presumption, we manipulated the expression of ATF3 in macrophage by using a PAO1 infection system. In the present study, ATF3 expression in macrophage was increased, following the duration and colony counts of PAO1 infection. Knockdown of ATF3 in macrophage resulted in increased percentage of senescent macrophage under PAO1 infection, while overexpressing ATF3 partly blocked PAO1-induced macrophage senescence. In accordance with the senescent phenotype, elevated reactive oxygen species (ROS) production was shown in ATF3 knockdown macrophages. Also, capacity of phagocytosis was also affected by manipulation of ATF3 expression in macrophages, and increased phagocytosed fluorescent beads was found in ATF3 knockdown macrophage. ATF3 might regulate the senescence process through influence on NF-κB translocation. During infection, the overexpression or downregulation of ATF3 in macrophage negatively modulated the translocation of NF-κB p65 and its phosphorylation at Ser-536. As a result, IL-6 and TNFα was elevated, while IL-10 decreased in case of ATF3 knockdown. In conclusion, ATF3 negatively regulates NF-κB translocation and activation, and participates in PA-induced macrophage senescence. As oxidative stress and inflammation induced element, ATF3 may modulate macrophage-related host defense.

Redirecting drug repositioning to discover innovative cosmeceuticals

Skin appearance is essential for self-esteem and quality of life; consequently, skin care products represent a huge market. In particular, cosmeceuticals constitute a hybrid category of skin care formulations, at the interphase of cosmetics and pharmaceuticals, rationally designed to target (patho) physiological mechanisms aiming to enhance skin health and appearance. Cosmeceuticals are marketed as anti-ageing, anti-wrinkle, hair regrowth, skin whitening and wound healing agents with special emphasis on scar-free healing. An overview on recent cutting-edge advances concerning the discovery and development of enhanced performance cosmeceuticals by drug repositioning approaches is presented here. In this context, we propose "target repositioning," a new term, to highlight that druggable protein targets implicated in multiple diseases (hubs in the diseasome) can be exploited to accelerate the discovery of molecularly targeted cosmeceuticals that can promote skin health as an added benefit, which is a novel concept not described before. In this direction, emphasis is placed on the role of mouse models, for often untreatable skin diseases, as well as recent breakthroughs on monogenic rare skin syndromes, in promoting compound repositioning to innovative cosmeceuticals.

CREB/ATF3 signaling mediates indoxyl sulfate-induced vascular smooth muscle cell proliferation and neointimal formation in uremia

BACKGROUND AND AIMS

Uremic patients are characterized by an increased risk of atherosclerotic cardiovascular diseases. Vascular smooth muscle cell (VSMC) proliferation contributes to neointimal formation, a main pathological feature in atherosclerosis. Activation of CREB/ATF3 signaling is pivotal in VSMC proliferation, yet its role in uremic atherosclerosis is unknown. This study aimed to explore whether CREB/ATF3 signaling is involved in the molecular mechanism underlying neointimal formation in uremia.

METHODS AND RESULTS

Treatment of VSMCs with uremic toxin (indoxyl sulfate [IS]) activated cAMP/CREB/ATF3/cyclin D signaling, which was reflected by increased VSMC proliferation. Blocking cAMP/PKA/CREB/ATF3 signaling attenuated the promoting effect of IS on cyclin D1 expression and VSMC proliferation. Loss-of-function and time-dependent experiments showed that ATF3 lies downstream of the CREB signaling. Mutational analysis of cyclin D1 promoter along with chromatin immunoprecipitation assays showed that CREB/ATF3 signaling participated in IS-induced cyclin D transcription. In vivo, phosphorylated CREB (an active form of CREB) and ATF3 were prominently upregulated in the neointima of experimental uremic rats, the atherosclerotic plaques of uremic ApoE^-/- mice, and the iliac arteries of uremic patients. Notably, the use of lentivirus to knock down ATF3 in the neointima of balloon-injured arteries could suppress the effect of uremia in vivo, including neointimal formation and cyclin D expression.

CONCLUSIONS

In this study, we demonstrated that CREB/ATF3-related signaling may be involved in IS-induced VSMC proliferation and the pathogenesis of neointimal formation during uremia.

Epigenetic and non-epigenetic regulation of Klotho in kidney disease

Klotho is a novel renoprotective anti-aging protein available in membrane-bound or soluble form. Klotho is expressed in brain, pancreas, and other solid organs but shows highest expression levels in the kidney. Klotho sustains normal kidney physiology but Klotho regulation also contributes to the progression of kidney disease. Systemic and intrarenal levels of Klotho fall drastically during acute kidney injury, kidney fibrosis, diabetic nephropathy, and other forms of chronic kidney disease, etc. Moreover, exogenous supplementation or overexpression of endogenous Klotho attenuates kidney disease. The regulation of endogenous Klotho expression involves epigenetic as well as non-epigenetic mechanisms. The epigenetic modifications such as DNA methylation, post-translational histone modifications, miRNAs regulate the change in Klotho expression in kidney disease. Non-epigenetic mechanisms such as ER stress, Wnt signaling, activation of the renin angiotensin system (RAS), excessive reactive oxygen species and cytokine generation, albumin overload, and PPAR-γ signaling also contribute to Klotho regulation. Evolving evidence highlight the capacity of natural products to regulate Klotho expression in kidney disease. All these preclinical data suggest that Klotho could be a novel biomarker as well as therapeutic target. Here we review the different mechanisms of Klotho regulation in the context of Klotho as a biomarker and potential therapeutic agent.

Resveratrol Pretreatment Ameliorates Concanavalin A-Induced Advanced Renal Glomerulosclerosis in Aged Mice through Upregulation of Sirtuin 1-Mediated Klotho Expression

Aging kidneys are characterized by an increased vulnerability to glomerulosclerosis and a measurable decline in renal function. Evidence suggests that renal and systemic klotho and sirtuin 1 (SIRT1) deficiencies worsen kidney damage induced by exogenous stresses. The aim of this study was to explore whether resveratrol would attenuate concanavalin A (Con A)-induced renal oxidative stress and advanced glomerulosclerosis in aged mice. Aged male C57BL/6 mice were treated orally with resveratrol (30 mg/kg) seven times (12 h intervals) prior to the administration of a single tail-vein injection of Con A (20 mg/kg). The plasma and urinary levels of kidney damage markers were evaluated. The kidney histopathology, renal parameters, and oxidative stress levels were measured. Furthermore, klotho was downregulated in mouse kidney mesangial cells that were pretreated with 25 µM resveratrol followed by 20 µg/mL Con A. The urinary albumin/creatinine ratio, blood urea nitrogen, kidney mesangial matrix expansion, tubulointerstitial fibrosis, and renal levels of α-smooth muscle actin, transforming growth factor beta, fibronectin, procollagen III propeptide, and collagen type I significantly increased in Con A-treated aged mice. Aged mice kidneys also showed markedly increased levels of 8-hydroxydeoxyguanosine (8-OH-dG) and reactive oxygen species (ROS), with reduced superoxide dismutase activity and levels of glutathione, klotho, and SIRT1 after Con A challenge. Furthermore, in kidney mesangial cells, klotho silencing abolished the effects of resveratrol on the Con A-mediated elevation of the indices of oxidative stress and the expression of glomerulosclerosis-related factors. These findings suggest that resveratrol protects against Con A-induced advanced glomerulosclerosis in aged mice, ameliorating renal oxidative stress via the SIRT1-mediated klotho expression.

The Role of Sirtuins in Kidney Diseases

Sirtuins (SIRTs) are class III histone deacetylases (HDACs) that play important roles in aging and a wide range of cellular functions. Sirtuins are crucial to numerous biological processes, including proliferation, DNA repair, mitochondrial energy homeostasis, and antioxidant activity. Mammals have seven different sirtuins, SIRT1–7, and the diverse biological functions of each sirtuin are due to differences in subcellular localization, expression profiles, and cellular substrates. In this review, we summarize research advances into the role of sirtuins in the pathogenesis of various kidney diseases including acute kidney injury, diabetic kidney disease, renal fibrosis, and kidney aging along with the possible underlying molecular mechanisms. The available evidence indicates that sirtuins have great potential as novel therapeutic targets for the prevention and treatment of kidney diseases.

Klotho, Aging, and the Failing Kidney

Klotho has been recognized as a gene involved in the aging process in mammals for over 30 years, where it regulates phosphate homeostasis and the activity of members of the fibroblast growth factor (FGF) family. The α-Klotho protein is the receptor for Fibroblast Growth Factor-23 (FGF23), regulating phosphate homeostasis and vitamin D metabolism. Phosphate toxicity is a hallmark of mammalian aging and correlates with diminution of Klotho levels with increasing age. As such, modulation of Klotho activity is an attractive target for therapeutic intervention in the diseasome of aging; in particular for chronic kidney disease (CKD), where Klotho has been implicated directly in the pathophysiology. A range of senotherapeutic strategies have been developed to directly or indirectly influence Klotho expression, with varying degrees of success. These include administration of exogenous Klotho, synthetic and natural Klotho agonists and indirect approaches, via modulation of the foodome and the gut microbiota. All these approaches have significant potential to mitigate loss of physiological function and resilience accompanying old age and to improve outcomes within the diseasome of aging.

Stabilization of telomere by the antioxidant property of polyphenols: Anti-aging potential

Aging is a form of a gradual loss of physiological integrity that results in impaired cellular function and ultimately increased vulnerability to disease and death. This process is a significant risk factor for critical age-related disorders such as cancer, diabetes, cardiovascular disease, and neurological conditions. Several mechanisms contribute to aging, most notably progressive telomeres shortening, which can be counteracted by telomerase enzyme activity and increasing in this enzyme activity associated with partly delaying the onset of aging. Individual behaviors and environmental factors such as nutrition affect the life-span by impact the telomerase activity rate. Healthy eating habits, including antioxidant intakes, such as polyphenols, can have a positive effect on telomere length by this mechanism. In this review, after studying the underlying mechanisms of aging and understanding the relationships between telomeres, telomerase, and aging, it has been attempted to explain the effect of polyphenols on reversing the oxidative stress and aging process.

Resveratrol loaded glycyrrhizic acid-conjugated human serum albumin nanoparticles for tail vein injection II: pharmacokinetics, tissue distribution and bioavailability

There are many kinds of biological activities of resveratrol itself, but its clinical application is limited by its poor solubility in water and low bioavailability. Therefore, we have prepared glycyrrhizic acid-conjugated human serum albumin nanoparticles wrapping resveratrol nanoparticles (GL-HSA-RESNPs). The purpose of this study was to investigate the bioavailability, pharmacokinetics and tissue distribution of resveratrol in rats after single-dose tail vein injection administration of GL-HSA-RESNPs. A sensitive and reliable high performance liquid chromatography (HPLC) method was established to verify the content of resveratrol in rat plasma and organs. The C_max value after GL-HSA-RESNPs administration was significantly higher than that of resveratrol suspension (933 ± 76.64 ng/mL vs. 618 ± 42.54 ng/mL, p < .01). The T_max value obtained after GL-HSA-RESNPs administration was significantly shorter than that after resveratrol suspension administration (0.17 ± 0.01 h vs. 0.25 ± 0.01 h, p < .001). The bioavailability of GL-HSA-RESNPs was 4.25 times higher than that of the pure resveratrol. The concentration of resveratrol in the main organs of rats treated with the GL-HSA-RESNPs was higher than that in rats treated with the pure resveratrol. Rats treated with GL-HSA-RESNPs had the highest concentration of resveratrol in their liver. It is indicated that GL-HSA-RESNPs is a promising liver-targeted delivery system that improves the in vivo bioavailability of resveratrol.

Klotho regulation by albuminuria is dependent on ATF3 and endoplasmic reticulum stress

Proteinuria is associated with renal function decline and cardiovascular mortality. This association may be attributed in part to alterations of Klotho expression induced by albuminuria, yet the underlying mechanisms are unclear. The presence of albumin decreased Klotho expression in the POD-ATTAC mouse model of proteinuric kidney disease as well as in kidney epithelial cell lines. This downregulation was related to both decreased Klotho transcription and diminished protein half-life, whereas cleavage by ADAM proteases was not modified. The regulation was albumin specific since it was neither observed in the analbuminemic Col4α3^-/- Alport mice nor induced by exposure of kidney epithelial cells to purified immunoglobulins. Albumin induced features of ER stress in renal tubular cells with ATF3/ATF4 activation. ATF3 and ATF4 induction downregulated Klotho through altered transcription mediated by their binding on the Klotho promoter. Inhibiting ER stress with 4-PBA decreased the effect of albumin on Klotho protein levels without altering mRNA levels, thus mainly abrogating the increased protein degradation. Taken together, albuminuria decreases Klotho expression through increased protein degradation and decreased transcription mediated by ER stress induction. This implies that modulating ER stress may improve proteinuria-induced alterations of Klotho expression, and hence renal and extrarenal complications associated with Klotho loss.

αKlotho-FGF23 interactions and their role in kidney disease: a molecular insight

Following the serendipitous discovery of the ageing suppressor, αKlotho (αKl), several decades ago, a growing body of evidence has defined a pivotal role for its various forms in multiple aspects of vertebrate physiology and pathology. The transmembrane form of αKl serves as a co-receptor for the osteocyte-derived mineral regulator, fibroblast growth factor (FGF)23, principally in the renal tubules. However, compelling data also suggest that circulating soluble forms of αKl, derived from the same source, may have independent homeostatic functions either as a hormone, glycan-cleaving enzyme or lectin. Chronic kidney disease (CKD) is of particular interest as disruption of the FGF23-αKl axis is an early and common feature of disease manifesting in markedly deficient αKl expression, but FGF23 excess. Here we critically discuss recent findings in αKl biology that conflict with the view that soluble αKl has substantive functions independent of FGF23 signalling. Although the issue of whether soluble αKl can act without FGF23 has yet to be resolved, we explore the potential significance of these contrary findings in the context of CKD and highlight how this endocrine pathway represents a promising target for novel anti-ageing therapeutics.

Neferine Attenuates Acute Kidney Injury by Inhibiting NF-κB Signaling and Upregulating Klotho Expression

Purpose: Morbidity associated with and mortality from acute kidney injury (AKI) is gradually increasing, and no efficient drug is available. We explored whether neferine, a bisbenzylisoquinoline alkaloid, attenuated AKI, and the possible mechanisms in play in vivo and in vitro.

Methods: We induced AKI using ischemia-reperfusion (I/R) or lipopolysaccharide (LPS) in vivo. C57 BL/6 male mice were randomized into two groups each containing four subgroups: control, neferine, I/R or LPS, and I/R or LPS + neferine. Mice were sacrificed 24 h after AKI induction and kidneys and sera were collected. NRK-52E cells were exposed to hypoxia/reoxygenation (H/R) or LPS in vitro.

Results: Neferine pretreatment significantly alleviated kidney functional loss and pathological damage. In the AKI mouse models induced by I/R or LPS, neferine inhibited the infiltration of inflammatory cells, including granulocytes and macrophages. Both in vivo and in vitro, neferine attenuated apoptosis, suppressed inflammatory cytokine production, decreased degradation of IκB-α, and inhibited nuclear translocation of NF-κB. Furthermore, it also upregulated Klotho expression in AKI.

Conclusion: Neferine mitigated renal injury in AKI models, perhaps by suppressing the activation of NF-κB and upregulating the expression of Klotho.

Resveratrol and 1,25-dihydroxyvitamin D co-administration protects the heart against D-galactose-induced aging in rats: evaluation of serum and cardiac levels of klotho

The current study investigates the cooperative cardioprotective effect of calcitriol (active form of vitamin D) combined with resveratrol in a rat model of D-galactose (D.gal)-induced aging. Male Wistar rats received resveratrol (D.gal + Res), calcitriol (D.gal + Cal), or a combination of them (D.gal + Res + Cal). Intact animals served as control (Ctl). Blood pressure (BP) was recorded by cannulation of the left carotid artery. Fibrosis and cell size were assessed by Masson's trichrome and hematoxylin-eosin staining, respectively. Cardiac and serum level of antiaging protein, klotho, was measured by ELISA assay method. Gene expression was evaluated by real-time RT-PCR. Biochemical tests were performed according to the standardized method. In D.gal + Res + Cal group, BP, heart weight-to-body weight ratio, and cardiomyocytes size decreased significantly compared with D-gal group. The cardiac transcription levels of catalase and superoxide dismutase 1 and 2 were upregulated in D.gal + Res + Cal compared to the D.gal group (P < 0.001, P < 0.05, P < 0.05, respectively). Increased level of malondialdehyde was observed in D.gal group (P < 0.01 vs. Ctl) which was normalized partially in D.gal + Res + Cal group (P < 0.05). Catalase and superoxide dismutase activity also increased in D.gal + Res + Cal group (P < 0.01 vs. D.gal). Cardiac Klotho, as the antiaging protein, remained unchanged at mRNA and protein levels among the experimental groups. The serum level of Klotho did not change significantly in D.gal group; however, in D.gal + Res + Cal group, serum klotho concentration was increased (P < 0.05 vs. D.gal). It could be concluded that co-administration of resveratrol and vitamin D protects the heart against aging-induced damage by the modulation of hemodynamic parameters and antioxidant status of the heart. Furthermore, increased serum level of klotho could be a novel mechanism for antiaging effects of resveratrol and vitamin D.

Phytochemicals as Novel Therapeutic Strategies for NLRP3 Inflammasome-Related Neurological, Metabolic, and Inflammatory Diseases

Several lines of evidence point out the relevance of nucleotide-binding oligomerization domain leucine-rich repeat and pyrin domain-containing protein 3 (NLRP3) inflammasome as a pivotal player in the pathophysiology of several neurological and psychiatric diseases (i.e., Parkinson's disease (PD), Alzheimer's disease (AD), multiple sclerosis (MS), amyotrophic lateral sclerosis, and major depressive disorder), metabolic disorders (i.e., obesity and type 2 diabetes) and chronic inflammatory diseases (i.e., intestinal inflammation, arthritis, and gout). Intensive research efforts are being made to achieve an integrated view about the pathophysiological role of NLRP3 inflammasome pathways in such disorders. Evidence is also emerging that the pharmacological modulation of NLRP3 inflammasome by phytochemicals could represent a promising molecular target for the therapeutic management of neurological, psychiatric, metabolic, and inflammatory diseases. The present review article has been intended to provide an integrated and critical overview of the available clinical and experimental evidence about the role of NLRP3 inflammasome in the pathophysiology of neurological, psychiatric, metabolic, and inflammatory diseases, including PD, AD, MS, depression, obesity, type 2 diabetes, arthritis, and intestinal inflammation. Special attention has been paid to highlight and critically discuss current scientific evidence on the effects of phytochemicals on NLRP3 inflammasome pathways and their potential in counteracting central neuroinflammation, metabolic alterations, and immune/inflammatory responses in such diseases.

Intracerebroventricular injection of resveratrol ameliorated Aβ-induced learning and cognitive decline in mice

Resveratrol (RSV) is a natural plant polyphenol compound which consists in red grape skins and wine in general. Plenty of previous studies have shown that resveratrol has neuroprotective effects. The primary object of this research was to study the effects of RSV on improving the cognitive function and neurodegeneration in the mouse model of Alzheimer's disease induced by Aβ_1-42, and the possible mechanism about targeting on Sirt1, which results in attenuating inflammatory response and mitochondrial dysfunction. We established the AD model of intracerebroventricular (i.c.v.) injection of Aβ_1-42 and it was observed that the significant decrease in alternately of Y Maze and the quadrant dwell time percentage of Morris water maze test. Furthermore, there were significant upregulations of AMPK/ PGC-1α and downregulations of NF-κB/ IL-1β/ NLRP3 signaling pathways in the hippocampus and prefrontal cortex in AD mice. The treatments with RSV and Donepezil could significantly ameliorate all the behavioral and biochemical changes induced by Aβ_1-42. It also noticeably improved the histopathological changes in the hippocampus and cortex. The results suggested that RSV might protect against cognitive deficits and neurodegeneration induced by Aβ_1-42, and serve as a potential agent in treatment of AD.

Studies on the anti-aging activity of a glycoprotein isolated from Fupenzi (Rubus chingii Hu.) and its regulation on klotho gene expression in mice kidney

In this study, a novel glycoprotein with molecular weight of 22.0 kDa was isolated and purified from Fupenzi (a kind of unripe fruits of Rubus chingii Hu.) by means of anion-exchange (DEAE-52) and gel column chromatography (Sephadex G-100). The glycoprotein consists of a carbohydrate component (81.42 ± 0.96%) and protein component (14.56 ± 1.21%). The anti-aging capability was measured in d‑galactose induced aging mice model, and the experimental data showed that the glycoprotein could significantly inhibit the formation of malondialdehyde (MDA) and raise the activities of superoxide dismutase (SOD) and catalase (CAT) in mice kidney and serum. The reverse transcription polymerase chain reaction (RT-PCR), quantitative real time polymerase chain reaction (Q-PCR) and western blots showed that the glycoprotein significantly increase the expression of anti-aging gene klotho in mice kidney. The results suggested that the anti-aging mechanism of FPZ might be achieved by improving the klotho gene expression and repairing the renal function. This study will provide a scientific basis for the view of traditional Chinese medicine that tonifying kidney is the basic way of anti-aging. In addition, the glycoprotein could be exploited as a potent dietary supplement to attenuate aging and prevent age-related diseases in humans.

Klotho preservation by Rhein promotes toll-like receptor 4 proteolysis and attenuates lipopolysaccharide-induced acute kidney injury

Renal anti-aging protein Klotho exhibits impressive properties of anti-inflammation and renal protection, however is suppressed early after renal injury, making Klotho restoration an attractive strategy of treating renal inflammatory disorders. Here, we reported that Klotho is enriched in macrophages and Klotho preservation by Rhein, an anthraquinone derived from medicinal plant rhubarb, attenuates lipopolysaccharide (LPS)-induced acute inflammation essentially via promoting toll-like receptor 4 (TLR4) degradation. LPS-induced pro-inflammatory NF-κB signaling and cytokine expressions coincided with Klotho repression and toll-like receptor 4 (TLR4) elevation in macrophages, renal epithelial cells, and acutely- inflamed kidney. Intriguingly, Rhein treatment effectively corrected the inverted alterations of Klotho and TLR4 and mitigated the TLR4 downstream inflammatory response in a Klotho restoration and TLR4 repression-dependent manner. Klotho inducibly associated with TLR4 after LPS stimulation and suppressed TLR4 protein abundance mainly via a proteolytic process sensitive to the inhibition of Klotho's putative β-glucuronidase activity. Consistently, Klotho knockdown by RNA interferences largely diminished the anti-inflammatory and renal protective effects of Rhein in a mouse model of acute kidney injury incurred by LPS. Thus, Klotho suppression of TLR4 via deglycosylation negatively controls TLR-associated inflammatory signaling and the endogenous Klotho preservation by Rhein or possibly other natural or synthetic compounds possesses promising potentials in the clinical treatment of renal inflammatory disorders.

KEY MESSAGES

• Klotho is highly expressed in macrophages and repressed by LPS in vitro and in vivo. • Klotho inhibits LPS-induced TLR4 accumulation and the downstream signaling. • Klotho decreases TLR4 via a deglycosylation-associated proteolytic process. • Rhein effectively prevents acute inflammation-incurred Klotho suppression. • Rhein reversal of Klotho attenuates LPS-induced acute inflammation and kidney injury.

Effects of resveratrol, curcumin, berberine and other nutraceuticals on aging, cancer development, cancer stem cells and microRNAs

Natural products or nutraceuticals have been shown to elicit anti-aging, anti-cancer and other health-enhancing effects. A key target of the effects of natural products may be the regulation of microRNA (miR) expression which results in cell death or prevents aging, diabetes, cardiovascular and other diseases. This review will focus on a few natural products, especially on resveratrol (RES), curcumin (CUR) and berberine (BBR). RES is obtained from the skins of grapes and other fruits and berries. RES may extend human lifespan by activating the sirtuins and SIRT1 molecules. CUR is isolated from the root of turmeric (Curcuma longa). CUR is currently used in the treatment of many disorders, especially in those involving an inflammatory process. CUR and modified derivatives have been shown to have potent anti-cancer effects, especially on cancer stem cells (CSC). BBR is also isolated from various plants (e.g., Coptis chinensis) and has been used for centuries in traditional medicine to treat diseases such as adult- onset diabetes. Understanding the benefits of these and other nutraceuticals may result in approaches to improve human health.

Dietary Resveratrol Does Not Affect Life Span, Body Composition, Stress Response, and Longevity-Related Gene Expression in Drosophila melanogaster

In this study, we tested the effect of the stilbene resveratrol on life span, body composition, locomotor activity, stress response, and the expression of genes encoding proteins centrally involved in ageing pathways in the model organism Drosophila melanogaster. Male and female w¹¹¹⁸ D. melanogaster were fed diets based on sucrose, corn meal, and yeast. Flies either received a control diet or a diet supplemented with 500 µmol/L resveratrol. Dietary resveratrol did not affect mean, median, and maximal life span of male and female flies. Furthermore, body composition remained largely unchanged following the resveratrol supplementation. Locomotor activity, as determined by the climbing index, was not significantly different between control and resveratrol-supplemented flies. Resveratrol-fed flies did not exhibit an improved stress response towards hydrogen peroxide as compared to controls. Resveratrol did not change mRNA steady levels of antioxidant (catalase, glutathione-S-transferase, NADH dehydrogenase, glutathione peroxidase, superoxide dismutase 2) and longevity-related genes, including sirtuin 2, spargel, and I'm Not Dead Yet. Collectively, present data suggest that resveratrol does not affect life span, body composition, locomotor activity, stress response, and longevity-associated gene expression in w¹¹¹⁸ D. melanogaster.

Metabolism and pharmacokinetics of resveratrol and pterostilbene

Beneficial properties of resveratrol and pterostilbene, a dimethyl ether analog of resveratrol, have attracted increasing interest in recent years. Resveratrol and pterostilbene exhibit many pharmacological similarities and both of them are generally considered to be safe for human consumption. Beyond the structural and general bioactivity similarities between them, large amounts of data are now available to reveal the metabolic fate and pharmacological differences between them. Pterostilbene was found to be more metabolically stable and usually exhibited stronger pharmacological activities than that of resveratrol. As a contribution to clarify and compare aspects like metabolic stability and pharmacokinetics of resveratrol and pterostilbene, as well as explain the pharmacological similarities and differences between them, this review presents and compares recent data on the metabolism and pharmacokinetics of resveratrol and pterostilbene. © 2018 BioFactors, 44(1):16-25, 2018.

Indoxyl sulfate upregulates the cannabinoid type 1 receptor gene via an ATF3/c-Jun complex-mediated signaling pathway in the model of uremic cardiomyopathy

BACKGROUND

The risk of cardiovascular disease is notably increased in patients with chronic kidney disease (CKD) and cannabinoid receptor type 1 (CB1R) plays an important role in the development of uremic cardiomyopathy. However, the molecular mechanism underlying the uremic toxin-induced upregulation of CB1R remains elusive.

METHODS

The expression of the ATF3/c-Jun complex and CB1R in both in vivo and in vitro models of CKD were measured. We also determined the impact of the ATF3/c-Jun complex on CB1R expression by transfecting H9c2 cells with dominant negative mutants of ATF3 or c-Jun. Inhibitors of organic anion transport, specific MAPK pathways and oxidative DNA damage were also used to assess the pathways mediating the effects of indoxyl sulfate (IS).

RESULTS

CB1R upregulation was associated with increased ATF3 expression and c-Jun phosphorylation in CKD both in vivo and in vitro. Expression of dominant-negative ATF3 or c-Jun mutants in IS-treated cells significantly reduced CB1R mRNA levels. Moreover, Co-IP revealed that the ATF3/c-Jun complex is formed and ChIP confirmed its binding to the CB1R promoter, suggesting that this complex directly stimulates CB1R transcription in CKD. Blocking the cellular entry of IS using an organic anion transport inhibitor, as well as inhibiting the ERK1/2 and/or JNK pathways, abrogated the effects of IS on CB1R, ATF3, and c-Jun expression. The IS-induced reactive oxygen species (ROS) was observed in the mitochondria.

CONCLUSIONS

We demonstrate that uremic toxins induce ATF3/c-Jun complex-mediated CB1R expression both in vivo and in vitro, possibly by modulating the ERK1/2 and JNK signaling pathways and ROS.