Association between soluble α-klotho and mortality risk in middle-aged and older adults

Associations of serum Klotho with diabetic kidney disease prevalence and mortality: insights from a nationally representative U.S. cohort

BACKGROUND

Serum Klotho, a biomarker associated with anti-aging, has been implicated in kidney disease. However, there is a lack of robust evidence for the relationship between the serum Klotho and diabetic kidney disease (DKD). This study aimed to investigate the association of the serum Klotho levels with DKD and assess the relationship between serum Klotho and all-cause mortality in individuals with DKD.

METHODS

We utilized data from the 2007-2016 National Health and Nutrition Examination Survey (NHANES), incorporating both cross-sectional and cohort study designs. The association between the serum Klotho and DKD was examined using weighted logistic regression models. To estimate the hazard ratios (HRs) and 95% confidence intervals (95% CIs) for all-cause mortality, weighted Çox proportional hazards models were applied. Restricted cubic spline analysis was used to assess the linear or nonlinear relationships between the serum Klotho and DKD or all-cause mortality. Additionally, mediation analysis was conducted to determine whether the systemic immune-inflammatory index (SII) mediated the effect of serum Klotho on all-cause mortality.

RESULTS

Our findings revealed a significant reverse association between serum Klotho and DKD after adjusting for sociodemographic and lifestyle factors in Model 2 (odds ratio [OR] 0.65, 95% CI 0.47-0.90, P = 0.01). However, this association was attenuated and lost statistical significance after further adjustment for comorbidities, SII, estimated glomerular filtration rate, and urine albumin/creatinine ratio in Model 3 (OR 0.65, 95% CI 0.32-1.31, P = 0.2). During an average follow-up period of 76 months, a total of 795 individuals (34%) experienced mortality. Weighted multivariate Cox regression models indicated that each one-unit increase in the serum Klotho was associated with a reduced risk of all-cause mortality (HR 0.48, 95% CI 0.29-0.82, P = 0.008) in DKD patients. Furthermore, restricted cubic spline analysis identified a nonlinear relationship between the serum Klotho and DKD (P for nonlinearity < 0.001), while a linear relationship was observed between serum Klotho and all-cause mortality (P for nonlinearity = 0.3480) among DKD populations. Stratified and interaction analysis confirmed the robustness of these core findings. Additionally, SII was found to partially mediate the association between serum Klotho and all-cause mortality, accounting for 5.7% of the effect.

CONCLUSIONS

Serum Klotho is inversely associated with the prevalence of DKD and is also linked to reduced all-cause mortality in individuals with DKD.

Association between serum α-klotho levels and the incidence of diabetic kidney disease and mortality in type 2 diabetes: evidence from a Chinese cohort and the NHANES database

BACKGROUND

The α-klotho is crucial in diabetes and its related complications. This study seeks to explore the link between α-klotho levels and the risk of diabetic kidney disease (DKD) as well as all-cause and cardiovascular mortality among individuals with type 2 diabetes mellitus (T2DM).

METHODS

The investigation involved 126 Chinese T2DM patients and 4,451 individuals from the National Health and Nutrition Examination Survey (NHANES) database. To evaluate the relationship between α-klotho levels and DKD risk, multivariate logistic regression was utilized. Additionally, restricted cubic spline (RCS) regression analysis was conducted to examine the nonlinear relationship between α-klotho levels and DKD incidence. RCS analysis was employed to explore the correlation between α-klotho and both all-cause and cardiovascular mortality.

RESULTS

In the Chinese cohort, α-klotho levels were notably elevated in T2DM group compared to DKD group. The NHANES data revealed a significant inverse relationship between α-klotho levels and DKD risk. Nonlinear analysis further illustrated a substantial nonlinear connection between α-klotho levels and DKD risk. Serum α-klotho levels below 880.78 pg/mL were linked to increased DKD risk in T2DM patients. When compared to the T2DM group, the DKD group had markedly higher all-cause and cardiovascular mortality rates, with the α-klotho low group (e.g., Q1) exhibiting lower survival compared to other groups. Cox regression findings indicated that elevated α-klotho levels could mitigate all-cause mortality in T2DM patients. The relationship between α-klotho levels and all-cause mortality was also nonlinear, with the minimal risk found at α-klotho levels between 776.95 pg/mL and 812.69 pg/mL, varying by gender.

CONCLUSION

There exists a notable association between α-klotho levels and DKD risk, along with mortality in T2DM patients, with varying effects based on gender. These results highlight the potential importance of α-klotho as both a biomarker and a therapeutic target.

A cohort study on the correlation between serum Klotho levels and all-cause mortality in American diabetic populations

BACKGROUND

The global prevalence of diabetes is on an upward trajectory. The management of complications related to the condition has seen limited progress in recent years. Klotho, characterized as an anti-aging protein that mitigates oxidative stress and inflammation, has previously been correlated with all-cause mortality in the broader United States population. The objective of this research was to investigate the persistence of this relationship among diabetic patients.

METHODS

This study meticulously analyzed data (2007-2016) sourced from the National Health and Nutrition Examination Survey, encompassing a cohort of 3,560 individuals. To elucidate the links of Klotho with all-cause mortality in diabetic patients, a multivariate Cox proportional hazards regression model was employed. The relationship was further explored using the restricted cubic spline model, threshold analysis, and subgroup analysis. Additionally, a mediation analysis was conducted to unravel the influence of age on the observed correlations.

RESULTS

Throughout the observation period, which had a median duration of 84 months, the incidence of all-cause mortality reached 18.511%. The Cox model analysis revealed a statistically significant association between Klotho levels and all-cause mortality. Further, the application of restricted cubic splines revealed a nuanced, nonlinear relationship between exposure factors and outcome across the entire study population (nonlinear P < 0.001), pinpointing a critical threshold at 829.138 pg/mL. Subgroup analyses showed consistent correlation between Klotho levels and mortality across various groups. Intriguingly, mediation analysis indicated that age was a significant mediator, accounting for 76.1% of the observed correlation of Klotho levels with all-cause mortality among diabetic patients.

CONCLUSIONS

Low levels of Klotho were found to be strongly associated with an increased risk of all-cause mortality in individuals with diabetes (Klotho levels < 829.138 pg/ml), and a nonlinear relationship was observed between these two variables. These associations were largely mediated by age.

Sex differences between atherogenic index of plasma and α-klotho levels in middle-aged and older adults: NHANES 2007-2016

Objective

Klotho is an anti-aging gene, and the α-klotho protein it encodes reportedly has cardiovascular protective effects. The atherogenic index of plasma (AIP) is a novel and comprehensive lipid index that correlates with atherosclerotic burden and is a critical risk factor for cardiovascular diseases. There are no studies examining the relationship between AIP and α-klotho; thus, we aimed to explore this potential association.

Methods

Data were extracted from the National Health and Nutrition Examination Survey 2007-2016 database, and the relationship between AIP and serum α-klotho levels was analyzed using weighted multivariate linear regression.

Results

After adjusting for risk factors, AIP showed a significant negative correlation with the logarithm of serum α-klotho levels in women. The trend analysis and smoothed curve fitting showed a nonlinear dose-response relationship. Threshold effect analysis showed a significant difference in the association between AIP and α-klotho before and after the AIP break point (0.434). Subgroup analyses demonstrated that the negative association of AIP with α-klotho was consistent across subgroups. However, the correlation between AIP and serum α-klotho in men was not significant.

Discussion

Our study provides new evidence for sex differences in the association between AIP and serum α-klotho levels.

Association of serum Klotho and fibroblast growth factor-23 levels with vascular calcification severity in patients with chronic kidney disease: an observational cohort study

PURPOSE

In patients with chronic kidney disease (CKD), vascular calcification (VC) is common and influences patient's outcome and prognosis. However, evaluation methods for VC severity are limited. Klotho and fibroblast growth factor-23 (FGF-23) are biomarkers associating with VC development. This study aimed to explore the association of serum Klotho and FGF-23 levels with VC severity in patients with non-dialysis CKD.

METHODS

Patients with non-dialysis CKD were enrolled during hospitalization and were divided into the following four groups on the basis of their coronary artery calcification (CAC) scores: non-VC (CAC scores = 0), mild VC (0 < CAC scores ≤ 100), moderate VC (100 < CAC scores ≤ 400), and severe VC groups (CAC scores > 400). Serum Klotho and FGF-23 levels among the different groups were compared.

RESULTS

A total of 154 non-dialysis CKD patients were enrolled. Correlation analysis showed that serum FGF-23 level (rho = 0.185, p = 0.022) was positively correlated with VC severity, whereas serum Klotho level (rho =  -  0.196, p = 0.015) was negatively correlated with VC severity in patients with CKD. Multivariable regression analysis showed that Klotho level [odd ratio (OR) = 0.998, 95% confidence interval (CI) 0.996-0.999, p = 0.001] served as a protective factor for VC severity in patients with CKD, whereas FGF-23 level (OR = 1.005, 95% CI 1.001-1.009, p = 0.020) was identified as risk factor for VC severity.

CONCLUSION

Serum Klotho and FGF-23 levels are potential predictors of VC severity in patients with non-dialysis CKD.

The inflection point: α-Klotho levels and the risk of all-cause mortality

Purpose

The controversial nature of the association between α-Klotho and mortality risk in the general population warrants further investigation. This study aims to examine the correlation between circulating α-Klotho levels and the risk of all-cause mortality.

Methods

A sample size of 13,748 individuals from the NAHNES 2005-2016 cycles was included in this study. The effect of different α-Klotho levels (divided into quartiles) on survival was assessed using Kaplan-Meier (KM) curves. Cox proportional hazards models were used to analyze the linear relationship between log α-Klotho and the risk of all-cause mortality. Restricted cubic spline Cox proportional hazards regression model was used to analyze the non-linear relationship between log α-Klotho and risk of all-cause mortality. Threshold effect analysis was performed to determine the most favorable inflection point for log α-Klotho. Stratification and sensitivity analyses were performed to assess the robustness of the results.

Results

A total of 1,569 deaths were reported during the median follow-up period of 5.33 years (2.83-7.83 years). Among the log α-Klotho quartile groups, quartile 1 had the highest mortality rate compared to quartiles 2, 3, and 4. Multifactorial Cox regression analysis revealed a weak association between log α-Klotho and a 44% reduction in the risk of all-cause mortality (p=0.0473). We also found a U-shaped non-linear association between log α-Klotho and risk of all-cause mortality, with an optimal inflection point identified at 2.89 pg/mL. The stability of the U-shaped association between log α-Klotho and mortality risk was observed in various stratification and sensitivity analyses.

Conclusion

This study identified a U-shaped association between circulating α-Klotho levels and risk of all-cause mortality, with a notable inflection point at 2.89 pg/mL. Further investigation is warranted to fully elucidate the potential mechanisms underlying the association between α-Klotho and risk of all-cause mortality in the broader population.

Association of α-klotho concentrations with cardiovascular and all-cause mortality in American adults with depression: a national prospective cohort study

This study examines α-klotho levels in depressed American adults and their association with cardiovascular disease and all-cause mortality, utilizing data from the National Health and Nutrition Examination Survey (2007-2016) and mortality details from the National Death Index up to December 31, 2019. Including 3329 participants with depression, findings revealed 485 all-cause and 113 cardiovascular deaths. To investigate the nonlinear association between α-klotho and mortality, the Cox proportional hazards regression model, restricted cubic splines, and two-piecewise Cox proportional hazards model were developed. Analyzes indicated an "L-shaped" relationship between ln-transformed α-klotho levels and all-cause mortality, with a significant threshold effect at 6.53 ln(pg/ml). Below this threshold, ln-transformed α-klotho levels were inversely related to all-cause mortality (adjusted HR 0.33, 95%CI = 0.19-0.56), with no significant association above it (adjusted HR 1.41, 95%CI = 0.84-2.36). Cardiovascular mortality showed no link to α-klotho levels. Subgroup analysis shown that, the association between ln-transformed α-klotho concentration and all-cause mortality was consistent in subgroups according to gender, age, BMI, race, and depression(adjusted P > 0.05). The study uncovers a non-linear "L-shaped" association between ln-transformed α-klotho levels and all-cause mortality in depressed individuals, suggesting α-klotho assessment as a tool for identifying high-risk patients and guiding preventive strategies to enhance survival.

Sex differences in mortality risk and U-shaped relationship with klotho levels: A long-term cohort study

BACKGROUNDS

It remains unclear whether there are sex differences in the correlation between klotho and mortality risk. The purpose of our study is to investigate the relationship between klotho levels and all-cause mortality, specifically examining potential sex disparities.

METHODS

The study utilized data from the National Health and Nutrition Examination Survey. The study employed the Cox proportional hazards model and Kaplan-Meier survival curves to conduct multivariate analyses investigating the associations between klotho and mortality. The impact of klotho level on mortality was assessed by a restricted cubic spline curve.

RESULTS

Our study included 13,748 participants. The hazard ratios (HR) for all-cause mortality were found to be higher in males compared to females. The risk of all-cause mortality decreased until the klotho level reached 959 pg/mL in all-cause mortality, then increased thereafter in females (P value for nonlinearity = 0.01, P overall = 0.02); no curved relationship was observed in males.

CONCLUSION

Klotho levels and mortality follow a U-shaped curve, with sex differences in the relationship. Males with higher klotho levels have a higher risk of all-cause death than females.

The role of Klotho and sirtuins in sleep-related cardiovascular diseases: a review study

The prevalence of sleep disorders has been reported from 1.6% to 56.0%, worldwide. Sleep deprivation causes cardiovascular diseases (CVDs) including atherosclerosis, vascular aging, hypertension, heart dysfunction, reduced heart rate variability, and cardiac arrhythmia. Reduced tissue oxygen causes various CVDs by activating pro-inflammatory factors and increasing oxidative stress. Sleep disorders are more important and prevalent in older people and cause more severe cardiovascular complications. On the other hand, the reduction of Klotho level, an age-dependent protein whose expression decreases with age, is associated with age-related diseases. Sirtuins, class III histone deacetylases, also are among the essential factors in postponing cellular aging and increasing the lifespan of organisms, and they do this by regulating different pathways in the cell. Sirtuins and Klotho play an important role in the pathophysiology of CVDS and both have anti-oxidative stress and anti-inflammatory activity. Studies have shown that the levels of Klotho and sirtuins are altered in sleep disorders. In this article, alterations of Klotho and sirtuins in sleep disorders and in the development of sleep-related CVDs were reviewed and the possible signaling pathways were discussed. The inclusion criteria were studies with keywords of different types of sleep disorders and CVDs, klotho, SIRT1-7, and sirtuins in PubMed, Scopus, Embase، Science Direct، Web of Sciences and Google Scholar by the end of 2023. The studies revealed there is a bidirectional relationship between sleep disorders and the serum and tissue levels of Klotho and sirtuins and sleep related-CVDs.

Relationship between uric acid to high-density cholesterol ratio (UHR) and circulating α-klotho: evidence from NHANES 2007-2016

OBJECTIVE

To investigate the relationship between uric acid to high-density lipoprotein cholesterol ratio (UHR) and circulating α-klotho levels in U.S. adults.

METHODS

A cross-sectional study used data from the National Health and Nutrition Examination Survey (NHANES) from 2007 to 2016. Circulating α-klotho was defined as the dependent variable and UHR was defined as the independent variable. Multivariable linear regression was performed to assess the relationship between the independent and dependent variables. The nonlinear relationship and effect size between UHR and α-klotho were evaluated using smooth curve fitting and threshold effect analysis. Subgroup analysis and sensitivity analysis were conducted to determine the stability of the results. The diagnostic performance of UHR and α-klotho in common elderly diseases was compared using ROC (Receiver Operating Characteristic) analysis.

RESULTS

Among 12,849 participants, there was a negative relationship between the UHR and circulating α-klotho. In the fully adjusted overall model, each unit increase in UHR was associated with a decrease of 4.1 pg/mL in α-klotho. The threshold effect analysis showed that before the inflection point of 8.2, each unit increase in UHR was associated with a decrease of 15.0 pg/mL in α-klotho; beyond the inflection point of 8.2, each unit increase in UHR was associated with a decrease of 2.8 pg/mL in α-klotho. Subgroup analyses and sensitivity analysis indicated that the relationship between UHR and α-klotho remained stable across most populations. The ROC diagnostic test indicated that the evaluative efficacy of UHR in diagnosing age-related diseases was comparable to that of α-klotho.

CONCLUSION

This study revealed that the UHR was associated with the circulating α-klotho concentration, with a negative association observed in most cases. This finding suggested that the UHR might be a promising indicator for evaluating circulating α-klotho levels.

Associations between the TyG index and the ɑ-Klotho protein in middle-aged and older population relevant to diabetes mellitus in NHANES 2007-2016

BACKGROUND

The anti-aging protein Klotho has diverse functions in antioxidative stress and energy metabolism through several pathways. While it has been reported that α-Klotho is downregulated in patients with insulin resistance (IR), the association between Klotho and IR is complex and controversial. The triglyceride-glucose (TyG) index has provided a practical method for assessing IR. With this in mind, our study aimed to investigate the relationship between the TyG index and soluble α-Klotho protein levels in US populations, both with and without diabetes mellitus.

METHODS

This cross-sectional study analyzed data from middle-aged and older participants in the National Health and Nutrition Examination Survey (NHANES) conducted between 2007 and 2016. The participants were divided into two groups based on their diabetes mellitus status: those with diabetes and those without diabetes. To evaluate the relationship between the TyG index and the concentration of the α-Klotho protein in each group, a series of survey-weighted multivariable linear regression models were employed. Furthermore, to examine the association between these two variables, multivariable-adjusted restricted cubic spline curves and subgroup analysis were generated.

RESULTS

The study involved 6,439 adults aged 40 years or older, with a mean age of 57.8 ± 10.9 years. Among them, 1577 (24.5%) had diabetes mellitus. A subgroup analysis indicated that the presence of diabetes significantly affected the relationship between the TyG index and the α-Klotho level. After considering all covariables, regression analysis of the participants without diabetes revealed that the α-Klotho concentration decreased by 32.35 pg/ml (95% CI: -50.07, -14.64) with each one unit increase in TyG (p < 0.001). The decline in α-Klotho levels with elevated TyG was more pronounced in the female population. In patients with diabetes mellitus, a non-linear association between the TyG index and α-Klotho was observed. There was no significant correlation observed between the two when TyG index were below 9.7. However, there was an increase in klotho levels of 106.44 pg/ml for each unit increase in TyG index above 9.7 (95% CI: 28.13, 184.74) (p = 0.008).

CONCLUSION

Our findings suggested that the presence of diabetes may influence the relationship between the TyG index and soluble α-Klotho. Furthermore, there seem to be sex differences in individuals without diabetes. Further studies are necessary to validate these findings.

U-shaped association between serum Klotho and all-cause mortality in US cardiovascular patients: a prospective cohort study

Background

Increased levels of serum Klotho have been associated with a reduced risk of several cardiovascular diseases (CVD). However, limited studies exist on the association between serum Klotho and mortality in patients with CVD.

Methods

We collected data from CVD patients in the National Health and Nutrition Examination Survey (NHANES) spanning 2007 to 2016. We linked NHANES data with the National Death Index to determine the survival status of participants. Univariate and multivariable Cox regression models were used to investigate the relationship between serum Klotho levels and mortality in CVD patients. The relationship between serum Klotho quartiles and mortality in CVD patients was visualized using Kaplan-Meier (KM) curves and restricted cubic spine. Finally, subgroup analyses were used to examine the association between serum Klotho and all-cause mortality in different populations.

Results

1905 patients with CVD were finally enrolled in our study with a mean follow-up of 7.1 years. The average age of the participants was 63.4 years, with 58.40% being male. KM showed that lower Klotho levels were associated with lower survival rates. After adjusting for potential confounders, patients with higher serum Klotho levels had lower all-cause mortality (Q1: 1.00, Q2: 0.58 (0.42-0.80), Q3: 0.69 (0.47-1.01), and Q4:0.64 (0.45-0.92). However, the relationship between serum Klotho levels and cardiovascular mortality was not statistically significant. Dose-response analysis shows a U-shaped relationship between serum Klotho levels and all-cause mortality in patients with CVD (P nonlinear=0.002). Subgroup analysis indicated that participants with a history of hypertension had a higher risk of all-cause mortality in serum Klotho Q4 compared to Q1 (P trend <0.05).

Conclusion

The relationship between serum Klotho levels and all-cause mortality in CVD patients exhibits a U-shaped association. The underlying mechanisms of this association need further investigation.

Serum klotho levels and mortality patterns in frail individuals: unraveling the u-shaped association

BACKGROUND

Frailty, a clinical syndrome intricately linked with the aging process, stands as a harbinger of numerous adverse outcomes, most notably mortality. This study aimed to elucidate the association between serum α-klotho concentration and mortality patterns, including all-cause and cause-specific mortality, in patients with frailty.

METHODS

The study employed Cox proportional hazard models, smoothed curve fitting, and supplementary analyses, encompassing threshold effect analysis, subgroup and sensitivity analyses, to explore the relationship between α-klotho levels and mortality, including all-cause, CVD, and cancer-related mortality.

RESULTS

Among the 2,608 frail individuals (mean age: 60.78 [SD 10.48] years; 59.89% female), the mortality stood at 25.35% during a median follow-up period of 6.95 years. Both unadjusted and adjusted models revealed a significant inverse association between higher serum α-klotho levels and the risk of all-cause and CVD-related mortality ([mean(95% CI) 0.68 (0.55, 0.83)] for all-cause mortality; [mean(95% CI) 0.48 (0.32, 0.74)] for CVD-related mortality, all P for trend < 0.001). Notably, log2-klotho displayed a U-shaped correlation with all-cause mortality and cancer mortality, characterized by thresholds of 9.48 and 9.55, respectively. The robustness of these findings was consistently supported by subgroup and sensitivity analyses.

CONCLUSION

This study unveils a U shaped association between serum α-klotho levels and both all-cause and cancer-related mortality among middle-aged and elderly individuals with frailty in the United States. The identified serum α-klotho thresholds, at 714.8 pg/ml for all-cause mortality and 750.6 pg/ml for cancer-related mortality, hold promise as potential targets for interventions aimed at mitigating the risks of premature death and cancer within this vulnerable population.

Klotho exerts protection in chronic kidney disease associated with regulating inflammatory response and lipid metabolism

BACKGROUND

The anti-aging protein Klotho plays a protective role in kidney disease, but its potential as a biomarker for chronic kidney disease (CKD) is controversial. Additionally, the main pathways through which Klotho exerts its effects on CKD remain unclear. Therefore, we used bioinformatics and clinical data analysis to determine its role in CKD.

RESULTS

We analyzed the transcriptomic and clinical data from the Nephroseq v5 database and found that the Klotho gene was mainly expressed in the tubulointerstitium, and its expression was significantly positively correlated with estimated glomerular filtration rate (eGFR) and negatively correlated with blood urea nitrogen (BUN) in CKD. We further found that Klotho gene expression was mainly negatively associated with inflammatory response and positively associated with lipid metabolism in CKD tubulointerstitium by analyzing two large sample-size CKD tubulointerstitial transcriptome datasets. By analyzing 10-year clinical data from the National Health and Nutrition Examination Survey (NHANES) 2007-2016, we also found that Klotho negatively correlated with inflammatory biomarkers and triglyceride and positively correlated with eGFR in the CKD population. Mediation analysis showed that Klotho could improve renal function in the general population by modulating the inflammatory response and lipid metabolism, while in the CKD population, it primarily manifested by mediating the inflammatory response. Restricted cubic spline (RCS) analysis showed that the optimal concentration range for Klotho to exert its biological function was around 1000 pg/ml. Kaplan-Meier curves showed that lower cumulative hazards of all-cause mortality in participants with higher levels of Klotho. We also demonstrated that Klotho could reduce cellular inflammatory response and improve cellular lipid metabolism by establishing an in vitro model similar to CKD.

CONCLUSIONS

Our results suggest that Klotho exerts protection in CKD, which may be mainly related to the regulation of inflammatory response and lipid metabolism, and it can serve as a potential biomarker for CKD.