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Aging is a risk factor for various acute and chronic kidney injuries. Kidney aging is accompanied by the secretion of growth factors, proteases, and inflammatory cytokines, known as the senescence-associated secretory phenotype (SASP). These factors accelerate the aging process and senescence-associated changes. Delaying kidney senescence may prevent acute and chronic kidney injury. Methionine restriction (MR) was found to be an effective intervention for delaying senescence. However, the mechanism of MR remains unclear. In this study, we investigated the effect of MR on the survival rate and renal aging of C57BL/6 mice and examined the relevant mechanisms. MR increased the survival rate and decreased the levels of senescence markers in the aging kidney. Both in vivo and in vitro, MR upregulated the transsulfuration pathway to increase H 2 S production, downregulated senescence markers and the SASP, and activated AMPK. The ability of MR to delay aging was reduced when AMPK was inhibited. These results suggest that MR may slow animal aging and kidney senescence through H 2 S production and AMPK pathway activation. Abbreviations : DR: diet restriction; MR: methionine restriction; SASP: senescence-associated secretory phenotype; AL: ad libitum; CKD, chronic kidney disease; AKI: acute kidney disease; TSP: transsulfuration pathway; CGL: cystathionine g-lyase; H 2 S: hydrogen sulfide; AMPK: AMP-activated protein kinase; mTOR: mammalian target of rapamycin; IS: indoxyl sulfate; CC: compound C.

Introduction: The proportion of elderly people is steadily rising worldwide, especially in low-income and middle-income countries, including China. Chronic kidney disease (CKD) is a common disorder in older people. However, little is known about the epidemiology of CKD and its consequences among the elderly. Improvements on clinical guidelines and healthcare policies for this population are required. This study aims to examine the risk factors for progression of CKD among the elderly and develop models to identify subgroups who are at high risk., Methods and Analysis: This is a prospective, multicentre, cohort study. The study population comprises ~3000 patients with predialysis CKD, aged ≥65 years, recruited between March 2016 and December 2017. After the baseline assessments, these patients will be followed for 5 years or until the occurrence of primary outcomes. Assessments that include anthropomorphic measures, laboratory tests, questionnaires, and blood and urine specimen collection will be performed at baseline and at follow-ups. Data on demographic information, cognitive function, depression, risk of malnutrition, physical activity and quality of life will be collected. The primary outcomes are incidence of end-stage renal disease, loss of renal function (≥40% decline in glomerular filtration rate from baseline), and death. The secondary outcomes are acute coronary syndrome, hospitalisation for heart failure or unstable angina, cerebrovascular events, and peripheral arterial disease., Ethics and Dissemination: This study protocol has been approved by the ethics committees of the Chinese People's Liberation Army General Hospital and the participating centres. All the participants gave written informed consent before data collection. The findings of the study will be published in peer-reviewed journals and will be presented at national or international conferences., Trial Registration Number: NCT03246204; Pre-results., Competing Interests: Competing interests: None declared., (© Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.)

Renal fibrosis contributes to declining renal function in the elderly. What is unclear however, is whether epithelial-mesenchymal transition (EMT) contributes to this age-related renal fibrosis. Here, we analyzed indicators of EMT during kidney aging and investigated the protective effects and mechanisms of short-term regimens of caloric restriction (CR) or caloric restriction mimetics (CRMs), including resveratrol and metformin. High glucose was used to induce premature senescence and EMT in human primary proximal tubular cells (PTCs) in vitro. To test the role of AMPK-mTOR signaling, siRNA was used to deplete AMPK. Cellular senescence and AMPK-mTOR signaling markers associated with EMT were detected. CR or CRMs treatment alleviated age-related EMT in aging kidneys, which was accompanied by activation of AMPK-mTOR signaling. High glucose induced premature senescence and EMT in PTCs in vitro, which was accompanied by down-regulation of AMPK/mTOR signaling. CRMs alleviated high glucose-induced senescence and EMT via stimulation of AMPK/mTOR signaling. Activation of AMPK/mTOR signaling protected PTCs from high glucose-induced EMT and cellular senescence. Short-term regimens of CR and CRMs alleviated age-related EMT via AMPK-mTOR signaling, suggesting a potential approach to reducing renal fibrosis during aging.

Renal aging is always accompanied by increased oxidative stress. Hydrogen sulfide (H2S) can be up-regulated by 50% dietary restriction (DR) for 7-day and can block mitochondrial oxidative stress. H2S production exerts a critical role in yeast, worm, and fruit fly models of DR-mediated longevity. In this study, we found that renal aging could be attenuated by 30% DR for 6-month (DR-6M) and life-long (DR-LL), but not for 6-week (DR-6W). The expressions of cystathionine-γ-lyase (CGL) and cystathionine-β- synthase (CBS) were improved by DR-6M and DR-LL. Endogenous H2S production shared the same trend with CBS and CGL, while glutathione (GSH) didn't. When comparing efficiencies of DR for different durations, more evident production of H2S was found in DR-6M and DR-LL than in DR-6W. Finally the level of oxidative stress was improved by DR-6M and DR-LL rather than by DR-6W. It concluded that aged rats had the ability to produce enough H2S on 30% DR interventions protecting against renal aging, and the effect of DR for long-term were more significant than that of DR for short-term.

Background: Chronic inflammation is thought to be a determinant of the aging rate and longevity. Caloric restriction (CR) attenuates age-related increases in the systemic levels of several pro-inflammatory mediators, but the anti-inflammatory mechanisms of CR in the aging process remain unclear., Methods: Fisher 344 rats in a CR group were fed an amount of food corresponding to 60% of that fed to an ad libitum-fed (AL) group for 8 months. Biochemical analyses and renal pathological grading were used to analyze physiological status. Important signaling molecules in the Toll-like receptor/nuclear factor kappa-light-chain-enhancer of activated B cells (TLR/NF-κB) pathway were also analyzed by western blotting, immunofluorescence and immunohistochemistry., Results: 1) Compared with AL feeding, CR decreased aging-mediated increases in both biochemical marker levels and renal pathological grading. 2) Single immunoglobulin IL-1 (IL-1)-related receptor (SIGIRR) expression decreased with increasing age, but CR led to overexpression. 3) The expression of TLR4 was significantly higher in the CR group than in the AL group. 4) SIGIRR overexpression decreased the expression of the adaptor molecules myeloid differentiation factor 88 (MyD88), IL-1 receptor-associated kinase 4 (IRAK4) and tumor necrosis factor receptor-associated factor 6 (TRAF6). 5) The levels of the inflammatory markers phospho-IκBα and phospho-NF-κB p65 decreased in the CR group., Conclusions: The inflammatory response might be alleviated by SIGIRR via blockade of the TLR4/NF-κB signaling pathway. Therefore, CR can decrease inflammation via SIGIRR overexpression, and SIGIRR might be a new target to delay aging., (© 2015 S. Karger AG, Basel.)

Objectives: To investigate the relationship between telomere length in peripheral blood white cells and cardiovascular function in a healthy, aging Han Chinese population., Methods: In 2012, peripheral blood leukocytes were obtained from 139 healthy individuals in Beijing, China, and telomere restriction fragment (TRF) length was assayed using a digoxigenin-labeled hybridization probe in Southern blot assays. Indicators of cardiovascular function were also evaluated, including electrocardiograms (ECG), (RR, P, PR, QRS, ST and T intervals); blood pressure (BP), (SBP, DBP, PP, PPI); cardiovascular ultrasound (left ventricular ejection fraction, LVEF); mitral early and late diastolic peak flow velocity (MVE and MVA); and lipid indices (TC, TG, HDL, LDL, LCI). The relationships of these cardiovascular indictors to telomere length were evaluated., Results: No correlations were found between telomere length and ECG, BP or lipid indices even after adjustment for age. Correlations were found between TFR length and some cardiovascular ultrasound indictors (D, MVEA, MVEDT, MVES, MVEL, MVEI, IMT), but these were not seen after adjusting for age., Conclusions: We did not find that leukocyte TFR length was associated with cardiovascular ultrasound indictors, ECG, BP, or lipid indices in this population of healthy Han Chinese individuals. Telomere length may serve as a genetic factor in biological aging., (Copyright © 2014 Australian and New Zealand Society of Cardiac and Thoracic Surgeons (ANZSCTS) and the Cardiac Society of Australia and New Zealand (CSANZ). Published by Elsevier B.V. All rights reserved.)

The purpose of this study is to build a biological age (BA) equation combining telomere length with chronological age (CA) and associated aging biomarkers. In total, 139 healthy volunteers were recruited from a Chinese Han cohort in Beijing. A genetic index, renal function indices, cardiovascular function indices, brain function indices, and oxidative stress and inflammation indices (C-reactive protein [CRP]) were measured and analyzed. A BA equation was proposed based on selected parameters, with terminal telomere restriction fragment (TRF) and CA as the two principal components. The selected aging markers included mitral annulus peak E anterior wall (MVEA), intima-media thickness (IMT), cystatin C (CYSC), D-dimer (DD), and digital symbol test (DST). The BA equation was: BA = −2.281TRF + 26.321CYSC + 0.025DD − 104.419MVEA + 34.863IMT − 0.265DST + 0.305CA + 26.346. To conclude, telomere length and CA as double benchmarks may be a new method to build a BA.

To explore the effect of short-term calorie restriction (CR) on renal aging, 8-week CR with 60% of the food intake of the ad libitum group was administered in 25-month-old male Sprague-Dawley rats. Aged rats subjected to short-term CR had lower body weight, level of triglycerides and ratio of urine protein to urine creatinine, respectively. Short-term CR blunted the increased glomerular volume, the degree of fibrosis, p16 and the positive rate of senescence-associated β-galactosidase staining of the kidneys in old ad libitum group. Light chain 3/Atg8 as an autophagy marker exhibited a marked decline in aged kidneys, which was increased by short-term CR. The levels of p62/SQSTM1 and polyubiquitin aggregates, which were increased in older kidneys, were blunted by short-term CR. Short-term CR retarded the level of 8-hydroxydeoxyguanosine, a marker of mitochondrial DNA oxidative damage. Moreover, we found an increased level of SIRT1 and AMPK, and a decreased level of mTOR in aged kidneys after short-term CR. These results suggested that short-term CR could be considered as a potential intervention for retardation of renal senescence by increasing autophagy and subsequently reducing oxidative damage. Three master regulators of energy metabolism, SIRT1, AMPK and mTOR are associated with these effects., (Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.)

Background: There has been considerable interest in whether old age is associated with IgA nephropathy (IgAN) progression, which is still controversial., Methods: We searched multiple databases for studies published from 1980 to 2012. The inclusion criteria were case-control, cohort studies published in any language. The included studies needed to have an older group. IgAN was proven by biopsy., Results: We included 9 studies with a total of 6,543 patients. The meta-analyses of other risk factors between the older group (>50 years old) and the non-older group (15-50 years old) found significant differences in the presence of hypertension, proteinuria, serum cholesterol levels and baseline renal function. In the overall analysis, compared to the non-older group, older age significantly increased the incidence of developing end-stage renal disease [ESRD; relative risk (RR) random model 1.95; 95% CI: 1.27-3.01]. In the subgroup analyses, we found the age limit and traditional risk factors of IgAN may be the sources of heterogeneity between studies. Moreover, the RR (2.56) of the Asian countries was much higher than the RR (1.11) of the European countries., Conclusions: This comprehensive review revealed that old age is a real risk factor for IgAN progression to ESRD. The incidence of ESRD in the older IgAN patients was 1.95 times higher than that in the non-older IgAN patients. Moreover, the risk of IgAN progression to ESRD of the older patients in Asia was higher than that of the older patients in Europe., (Copyright © 2013 S. Karger AG, Basel.)

Objective: To explore the expression and role of integrin-linking kinase (ILK) in aging rats subjected to unilateral ureteral obstruction (UUO)., Methods: The UUO model and sham-operated rats (SHAM) were established with 3-month-old rats and 26-month-old rats and the rats were sacrificed before UUO and after UUO at 3, 7 and 14 days. Immunofluorescent staining, Western blot, RT-PCR, etc were applied to detect the expressions of ILK and fibronectin (FN) in the renal of UUO rat at each time point., Results: With the time of UUO, the relative interstitial areas and tubulointerstitial fibrotic areas in 26-month-old rats were significantly higher than those in 3-month-old ones at each time point (P < 0.01) and the mRNA and protein levels of ILK and FN are increasing with the time of UUO in both groups (P < 0.01). ILK mRNA semi-quantitative values of 26-month and 3-month rats were 0.98 +/- 0.06 vs 0.72 +/- 0.06, 3 days after UUO (P < 0.01), 1.49 +/- 0.05 vs 1.03 +/- 0.04, 14 days after UUO (P < 0.01), respectively. ILK proteinsemi-quantitative values of 26-month and 3-month rats were 0.57 +/- 0.04 vs 0.52 +/- 0.03, 3 days after UUO (P < 0.01), 0.76 +/- 0.04 vs 0.63 +/- 0.03, 14 days after UUO (P < 0.01), respectively. The expressions of ILK mRNA and protein level were positively correlated with the relatively renal interstitial areas (r = 0.71, P < 0.05 and r = 0.80, P < 0.05, respectively). And the whole levels of ILK and FN in 26-month-old rats are higher than those of 3-month-old rats., Conclusion: With aging, the expressions of ILK and FN increase progressively in UUO rat, and the over-expression of ILK probably promotes renal tubulointerstitial fibrosis and aging.

Objective: To explore the imbalance between the expression of metalloproteinases (MMPs) and that of tissue type inhibitors of metalloproteinase (TIMPs) in the renal tubulointerstitial lesions of aging rats and the potential role of this imbalance., Methods: Forty-eight male 26-month-old Wistar rats were randomly divided into 2 groups of 24 rats: unilateral ureteral obstruction (UUO) group with the left ureter ligated and excised and false operation group used as control group. Forty-eight male 3-month-old Wistar rats were randomly divided into 2 groups of 24 rats: UUO group and false operation group just as in the 26-month-old rats. Every group was randomly divided into 3 subgroups of 8 rats: 3-day group, 7-day group, and 14-day group to be killed 2, 7, and 14 days after the operation respectively. The 2 kidneys of each rat were taken out. Routine pathological examination and immunofluorescence (IF) examination were made to calculate the area of renal tubulointerstitial fibrosis and the expression of IV type collagen. RT-PCR and Western blotting were used to detect the expressions of mRNA and protein of TIMP-1, TIMP-2, MMP-2, and MMP-9 in the kidney at different time points. Gelatin zymography was used to detect the proteolytic activity of MMP-2 and MMP-9., Results: The renal interstitial lesion was more significantly in the 26-month-old UUO rats than in the 3-month-old UUO rats since the 3rd day after operation. Both the expression of MMP-2 mRNA and the expression of MMP-9 mRNA were not different between the 2 control groups. In the control groups, TIMP-1 and TIMP-2 Both MMP-2 mRNA and MMP-9 mRNA were expressed in both control groups, without significant differences between these 2 control groups. TIMP-1 mRNA and TIMP-2 mRNA were only weakly expressed in the renal tissues of the 3-month-old control group, however, the expressions of both TIMP-1 and TIMP-2 were significantly stronger in the 16-month-old control group than in the 3-month-old control group. The expressions of TIMP-1 mRNA and TIMP-2 mRNA at different time points were significantly stronger in the obstructed side than in the healthy side in the UUO groups, and significantly stronger in the 26-month-old rats than in the 3-month-old rats. MMP-2 protein and MMP-9 protein were expressed in the 3-month-old and 26-month-old controls without difference between them. The expressions of MMP-2 protein and MMP-9 protein at different time points were significantly stronger in the obstructed side than in the healthy side in the UUO groups, without significant difference between the 26-month-old UUO rats and the 3-month-old UUO rats. The expressions of TIMP-1 protein and TIMP-2 protein were very weak at different time points in the renal tissues of the 3-month-old controls and were significantly stronger in the 26-month-old control rats. In the UUO rats the expressions of TIMP-1 protein and TIMP-2 protein in the renal tissues of the obstructed side at different time points were all significantly stronger for both age groups in comparison with the control groups of the same age and were significantly stronger in the 26-month-old UUO rats than in the 3-month-old UUO rats without significant difference between the 26-month-old UUO rats and the 3-month-old UUO rats. The MMP-2 activity and MMP-9 activity of the 26-month-old rats were both significantly lower than those of the 3-month-old control rats. The MMP-2 activity and MMP-9 activity at different time points of the 2 UUO groups were all significantly lower than those of the control groups of the same age, and those of the 26-month-old were significantly lower than those of the 3-month-old rats The MMP-2 activity and MMP-9 activity were negatively correlated with the expressions of TIMP-2 and TIMP-1., Conclusion: The abnormal expression of MMPs/TIMPs including higher expression of TIMPs and decreased proteolytic activity of MMPs induced by aging may be one of the factors aggravating the renal tubulointerstitial lesions of aging rats.

Purpose: The prevalence of depression and the relationship between depression and kidney function and health-related quality of life (HRQOL) are not well understood in elderly patients with predialysis chronic kidney disease (CKD). This study aimed to evaluate the prevalence of depression and the association between depression and kidney function and HRQOL. Patients and methods: In this cross-sectional study, 1079 elderly participants with CKD were recruited at 32 clinical centers located within 26 cities throughout 24 provinces in China. Demographic information and laboratory analyses were collected. Symptoms of depression were assessed using the 15-item Geriatric Depression Scale (GDS-15). HRQOL was evaluated using the Kidney Disease Quality of Life-36 (KDQOL-36) instrument. Results: The prevalence of depression was 23.0%. The estimated glomerular filtration rate (eGFR) was negatively correlated with the GDS score whether it was treated as a categorical variable (r=−0.097, P=0.001) or as a continuous variable (r=−0.100, P=0.001). Marital status, education level, history of CVD and diabetes, CKD stage and proteinuria confirmed to be independent and significant predictors of depression in patients with CKD. Compared with CKD 1–2 patients, we observed an increase of 0.541 and 4.171 in the odds for developing depression in patients CKD 4 (odds ratio [OR] =1.541; P=0.031) and CKD 5 (odds ratio [OR] =5.171; P<0.001), respectively. We observed negative and significant correlations with the GDS score for the following components: PCS (r=−0.370, P<0.001), MCS (r=−0.412, P<0.001), burden of kidney disease (r=−0.403, P<0.001), symptoms and problems of kidney disease (r=−0.360, P<0.001) and effects of kidney disease (r=−0.355, P<0.001). Depression was an independent and significant predictor of all the subcomponents of the HRQOL. Conclusions: The prevalence of depression in elderly patients with CKD was high and was negatively correlated with kidney function. Depression had a major negative impact on HRQOL. [ABSTRACT FROM AUTHOR]

Energy restriction (ER) has been widely studied as a novel intervention, and its ability to prolong life has been fully demonstrated. For example, ER can significantly extend the lifespans of model flies, worms, rodents and other mammals. The role of ER in renal protection has also been elucidated. In preclinical studies, adjusting total energy intake or consumption of specific nutrients has prophylactic or therapeutic effects on ageing-related kidney disease and acute and chronic kidney injury. Amino acid restriction has gradually attracted attention. ER mimetics have also been studied in depth. The protective mechanisms of ER and ER mimetics for renal injury include increasing AMP-activated protein kinase and sirtuin type 1 (Sirt1) levels and autophagy and reducing mammalian target of rapamycin, inflammation and oxidative stress. However, the renal protective effect of ER has mostly been investigated in rodent models, and the role of ER in patients cannot be determined due to the lack of large randomised controlled trials. To protect the kidney, the mechanism of ER must be thoroughly researched, and more accurate diet or drug interventions need to be identified. [ABSTRACT FROM AUTHOR]

Background: Renal toxicity limits the clinical use of platinum-based therapy in the elderly. In order to clarify the impact of aging on the risk of platinum-related nephrotoxicity, the following meta-analysis was performed.Methods: We searched multiple databases for studies published before January 2017. The inclusion criteria were case-control, cohort studies published in any language.Results: The risk of platinum-induced nephrotoxicity in the older group was 1.43 times (risk rate) higher than in the non-older group. Platinum-induced nephrotoxicity in older patients was mainly I/II. There was no significant difference in the incidence of grade III/IV renal toxicity between groups. The risk for elderly patients in Asia was significantly higher than in Europe and North America. Carboplatin had a lower risk of renal toxicity and only half of the amount of moderate and severe nephrotoxicity than cisplatin. In the age stratification analysis, the RR values were 1.43, 1.51 and 1.35 respectively for the elderly group (55, 60, 70 years old), and all had significant differences. The risk of platinum-related nephrotoxicity in elderly patients was significantly increased in the high comorbidity rate group. Moreover, the RR values of the normal renal function group were significantly higher than that of the 'no mention or renal insufficiency' subgroup.Conclusions: Aging increased the risk of platinum-induced nephrotoxicity by 43%, partly due to more comorbidities in elderly patients, and mild renal toxicity was dominant. The risk of renal toxicity of the elderly patients in Asian countries was much higher than that of in European countries and North America. [ABSTRACT FROM AUTHOR]