The Longevity Protein Klotho: A Promising Tool to Monitor Lifestyle Improvements

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.

The associations between oxidative balance score and serum Klotho level in the U.S. population aged 40-79 years

The relationship between the oxidative balance score (OBS) and the serum Klotho level has yet to be defined. We sought to investigate the potential relationship between OBS and the serum Klotho level in the U.S. population aged 40-79 years. This study included 8,145 participants from the National Health and Nutrition Examination Surveys (NHANES) database spanning from 2007 to 2016. The OBS consisted of the dietary OBS and the lifestyle OBS, based on 16 dietary components and 4 lifestyle components. Weighted multiple linear regressions were performed to explore the association between OBS and serum Klotho level. Furthermore, nonlinear relationships were analyzed through the application of restricted cubic splines (RCS). In the multivariate linear regression model with adjustment for such as demographics, economic income and dietary intake, a higher OBS was associated with a higher serum Klotho, with the beta estimate and 95%CI of 2.85 (1.03-4.68, p < 0.01). Compared with the lowest tertile group, the highest group was associated with a higher Klotho level (30.35, 3.43-57.28, p < 0.05). Furthermore, higher dietary OBS and lifestyle OBS were similarly associated with higher Klotho level (beta (95%CI): 1.27 (0.79-3.32); 14.23 (9.53-18.92), respectively). The RCS exhibited a linear dose-response association between OBS, dietary OBS and lifestyle OBS with serum Klotho concentration (Pnon-linearity>0.05). The association between OBS and serum Klotho level was consistent across age, sex, education, marital status, energy intake and poverty income ratio (PIR) (Pinteraction>0.05). The study reported significant association between OBS and klotho, indicating that adherence to antioxidant behaviors may be linked to slower aging and better health.

Gender differences in the relationship between the triglyceride-glucose index and serum Klotho concentrations among the middle-aged and elderly: a cross-sectional analysis

BACKGROUND

The triglyceride-glucose (TyG) index is recognized as a robust indicator for evaluating insulin resistance (IR). Despite the well-documented anti-aging biological functions of Klotho protein, its correlation with the TyG index remains unexplored.

METHODS

A cross-sectional analysis was conducted involving participants from the National Health and Nutrition Examination Surveys (NHANES) 2007-2016. The TyG index was computed using laboratory data, while serum Klotho concentrations was determined using ELISA kit. After adjusting potential confounding variables, multivariate regression models were employed to evaluate the association between the TyG index and Klotho protein levels among middle-aged and elderly females and males separately. Additionally, smooth curve fitting and segmented regression model were applied to investigate potential threshold effects and identify the inflection point.

RESULTS

A total of 6,573 adults qualified for inclusion, comprising 3,147 (47.88%) males and 3,426 (52.12%) females. Multivariate regression analysis revealed that females with a higher TyG index exhibited significantly lower serum Klotho concentrations (β=-83.41, 95% CI: -124.23 to -42.60, P < 0.0001). This association was not statistically significant in males (β = 15.40, 95% CI: -19.16 to 49.95, P = 0.3827). Subgroup analyses revealed a significant interaction effect by diabetes status in females (P-interaction = 0.0121), where non-diabetic females showed a stronger negative association between TyG index and serum Klotho levels compared to diabetic females. In the female group, when TyG index was divided into quartiles, individuals in the highest quartile of TyG index exhibited reduced levels of Klotho protein (Q4: -88.77 pg/ml) compared to those in the lowest quartile (Q1) after full adjustment (P = 0.0041). Segmented regression analysis indicated a turning point value of 9.4 in females. Notably, a 1-unit increase in TyG index was significantly associated with a decrease in Klotho levels by -111.43 pg/ml (95% CI: -157.34 to -65.52, P < 0.0001) when TyG index was below 9.4, while above this threshold, the association was not significant (Log likelihood ratio test: 0.009).

CONCLUSIONS

The findings highlight a non-linear correlation between the TyG index and serum Klotho concentrations among females, indicative of a saturation effect. This relationship was particularly pronounced in non-diabetic women. In contrast, no statistically significant association was observed in male participants.

Anti-Inflammatory Role of the Klotho Protein and Relevance to Aging

The α-Klotho protein (hereafter Klotho) is an obligate coreceptor for fibroblast growth factor 23 (FGF23). It is produced in the kidneys, brain and other sites. Klotho insufficiency causes hyperphosphatemia and other anomalies. Importantly, it is associated with chronic pathologies (often age-related) that have an inflammatory component. This includes atherosclerosis, diabetes and Alzheimer's disease. Its mode of action in these diseases is not well understood, but it inhibits or regulates multiple major pathways. Klotho has a membrane form and a soluble form (s-Klotho). Cytosolic Klotho is postulated but not well characterized. s-Klotho has endocrine properties that are incompletely elucidated. It binds to the FGF receptor 1c (FGFR1c) that is widely expressed (including endothelial cells). It also attaches to soluble FGF23, and FGF23/Klotho binds to FGFRs. Thus, s-Klotho might be a roaming FGF23 coreceptor, but it has other functions. Notably, Klotho (cell-bound or soluble) counteracts inflammation and appears to mitigate related aging (inflammaging). It inhibits NF-κB and the NLRP3 inflammasome. This inflammasome requires priming by NF-κB and produces active IL-1β, membrane pores and cell death (pyroptosis). In accord, Klotho countered inflammation and cell injury induced by toxins, damage-associated molecular patterns (DAMPs), cytokines, and reactive oxygen species (ROS). s-Klotho also blocks the TGF-β receptor and Wnt ligands, which lessens fibrotic disease. Low Klotho is associated with loss of muscle mass (sarcopenia), as occurs in aging and chronic diseases. s-Klotho counters the inhibitory effects of myostatin and TGF-β on muscle, reduces inflammation, and improves muscle repair following injury. The inhibition of TGF-β and other factors may also be protective in diabetic retinopathy and age-related macular degeneration (AMD). This review examines Klotho functions especially as related to inflammation and potential applications.

Maintaining ideal cardiovascular health is associated with higher serum anti-aging protein klotho in the middle-aged and older populations

OBJECTIVES

Maintaining ideal cardiovascular health (CVH) is believed to have potential anti-aging benefits. The American Heart Association (AHA) recently updated the "Life's Essential 8 (LE8)" metrics to measure ideal CVH, but its connection with the anti-aging protein klotho is still unclear. We aimed to explore the relationship between ideal cardiovascular health and serum anti-aging protein klotho in a nationally representative US middle-aged and older population.

DESIGN

A cross-sectional study.

SETTING

The National Health and Nutrition Examination Survey (2007-2016).

PARTICIPANTS

A total of 9457 middle-aged and older participants.

MEASUREMENTS

Ideal CVH scores and their components were defined according to the guidelines set by the AHA. Serum klotho detected by enzyme-linked immunosorbent assay. Weighted multivariable linear regression and restricted cubic spline were employed to examine the association between CVH score and klotho. Subgroup analyses were conducted, stratified by age (40-59 and 60-79), sex (Male and Female), race (Mexican American, non-Hispanic White, non-Hispanic Black, and Others) and chronic kidney disease (Yes and No) in fully adjusted models.

RESULTS

A total of 9457 middle-aged and older participants were included in this study, with a mean age of 55.27 ± 0.17 years. The mean serum klotho level in the population was 849.33 ± 5.39 pg/mL. After controlling for potential confounders, the LE8 score showed a positive correlation with serum klotho levels (β: 1.32; 95% CI 0.73, 1.91), and a non-linear dose-response relationship was observed. Furthermore, we also discovered a positive relationship between health behaviors score and health factors score and serum klotho levels (β: 0.48; 95% CI 0.07, 0.88 and β: 1.05; 95% CI 0.54, 1.56, respectively), particularly a stronger correlation between health factors and serum klotho. In the subgroup analysis, we observed a significant interaction between LE8 score and sex and race. (P for interaction <0.05).

CONCLUSIONS

LE8 and its subscale scores were positively associated with serum klotho levels in the middle-aged and older populations. Promoting the maintenance of ideal CVH can contribute to delaying the aging process.