Association between Soluble α-Klotho Protein and Metabolic Syndrome in the Adult Population

Association between adult body shape index and serum levels of the anti-aging protein Klotho in adults: a population-based cross-sectional study of the NHANES from 2007 to 2016

Purpose

Adult body shape index (ABSI) is widely recognized as a reliable indicator for evaluating body fat distribution and dysfunction. However, the relationship between ABSI and Klotho protein, known for its anti-aging biological function, has not yet been investigated. Therefore, the aim of this study was to assess the correlation between ABSI and serum Klotho levels in adults residing in the United States.

Methods

A cross-sectional study of participants was conducted based on the 2007-2016 National Health and Nutrition Examination Survey. Visceral adiposity was determined using the ABSI score, and Klotho protein concentration was measured using an enzyme-linked immunosorbent assay kit. Multiple regression models were used to estimate the association between ABSI and Klotho protein after adjusting for several potential confounding variables. Subgroup analysis of ABSI and Klotho was performed using restricted cubic splines.

Result

A total of 11,070 adults were eligible for participation, with a mean ABSI of 8.28 ± 0.45 and a mean Klotho protein concentration of 853.33 ± 309.80 pg/mL. Multivariate regression analysis showed that participants with high ABSI scores had lower serum Klotho protein concentrations. When ABSI was divided into quartiles, after full adjustment, Klotho protein levels were lower in participants in the fourth fully adjusted ABSI quartile (Q4: -0.352 pg/ml) than in those in the lowest quartile (Q1) (P<0.0001).

Conclusion

There was a negative linear correlation between ABSI score and serum Klotho concentration. Higher ABSI was associated with lower serum Klotho concentrations; however, this association did not seem to be significant in subjects with BMI ≥30 kg/m2.Further study is needed to verify the causality of this association and elucidate the underlying mechanisms.

Sex differences in the association between serum α-Klotho levels and hyperlipidemia: a cross-sectional study from NHANES 2013-2016

This study assessed the association between serum α-Klotho levels and hyperlipidemia. The aim was to ascertain the potential of serum α-Klotho levels as a predictive biomarker for hyperlipidemia. The research employed data from the National Health and Nutrition Examination Survey (NHANES) between 2013 and 2016. Weighted logistic regression analyses were employed to investigate the association between serum α-Klotho levels and hyperlipidemia. Restricted cubic spline (RCS) analyses were executed for males and females to scrutinize the non-linear correlation between α-Klotho levels and hyperlipidemia. Subsequently, piecewise logistic regression analysis was carried out based on the RCS findings. In females, the levels of α-Klotho were notably lower in those with hyperlipidemia in comparison to those without this condition (P < 0.05), No significant variation was demonstrated in α-Klotho levels between males with and without hyperlipidemia (P > 0.05). The participants were stratified by sex and subjected to analysis by logistic regression model. When α-Klotho was log2-transformed, it was significantly negatively associated with the risk of hyperlipidemia in females, even after adjusting for all of the covariates (OR 0.45, 95% CI 0.24-0.82), which was not observed in males (OR 1.14, 95% CI 0.63-2.06). The same results were observed in the third tertile of α-Klotho. Moreover, RCS analysis suggested a nonlinear correlation between serum α-Klotho levels and hyperlipidemia in females (P < 0.01). The inflection point of α-Klotho was found to be 1106.87 pg/mL. The piecewise logistic regression model revealed that when α-Klotho levels exceeded 1106.87 pg/mL, the link between α-Klotho and hyperlipidemia was no longer significant (P > 0.05). This investigation highlights the sex-based variation in the link between serum α-Klotho levels and hyperlipidemia. In females, α-Klotho exhibited negative association with hyperlipidemia, displaying a saturation effect. Serum α-Klotho emerges as a promising biological marker for the risk of hyperlipidemia among females.

Systemic immune-inflammation index mediates the association between abdominal obesity and serum klotho levels

The weight-adjusted waist index (WWI) has emerged as a reliable indicator of abdominal obesity. α-Klotho, a transmembrane protein, functions as a suppressor of aging. However, the relationship between these two factors remains underexplored. This study aims to investigate the association between WWI and serum α-Klotho levels in middle-aged and elderly Americans, with a focus on exploring the potential mediating role of the systemic immune inflammation index (SII). A cross-sectional study was conducted using data from 6997 middle-aged and elderly Americans participating in the National Health and Nutrition Examination Surveys (NHANES) between 2011 and 2016. Multiple linear regression analysis was employed to assess the relationship between WWI and serum α-Klotho concentrations. Additionally, mediation analysis was performed to investigate the mediating effect of SII on the relationships. Our analysis revealed a significant negative correlation between WWI and serum α-Klotho levels in the survey-weighted multiple linear regression models (adjusted percent change: -7.79; 95% CI: -10.15, -5.37). Mediation analysis demonstrated that the association between WWI and α-Klotho levels was partially mediated by SII (adjusted percent change: -0.88; 95% CI: -1.24, -0.45), with the proportion of mediation amounting to 11.6%. Further age-stratified results showed that the mediating role of SII was more pronounced among individuals aged ≥ 60 years, exhibiting a mediating effect of 26.3%, in contrast to 4.2% for those < 60 years. The findings suggest that WWI is inversely associated with serum α-Klotho concentrations and that this association is partially mediated by SII, especially in older people.

Relationship of α-Klotho with Frailty Index and Sarcopenia: A Bidirectional Mendelian Randomization Study

Previous studies have established associations between α-Klotho and frailty or sarcopenia; however, the causal nature of these relationships remains unclear. This study investigates the causal effects of α-Klotho on frailty and sarcopenia-related traits using Mendelian randomization (MR). Genetic instruments for circulating α-Klotho concentrations, frailty index (FI), low grip strength (LGS), appendicular lean mass (ALM), and walking pace were developed based on data from large genome-wide association studies. Two-sample MR analyses were performed, supplemented by sensitivity analyses to ensure the robustness of the findings. Reverse MR analyses were also conducted to explore potential reverse causation. The findings demonstrated an inverse causal relationship of circulating α-Klotho levels with FI (β = -0.020, 95% confidence interval [95% CI] = -0.036 to -0.004; p = 0.017) and LGS (β = -0.033, 95% CI = -0.061 to -0.004; p = 0.023). However, no causal relationship was observed between circulating α-Klotho levels and ALM or walking pace. Additionally, no evidence of reverse causation was identified between FI or sarcopenia-related traits and circulating α-Klotho levels. In conclusion, this MR analysis establishes an inverse causal relationship of circulating α-Klotho levels with both FI and LGS.

Correlation of the weight-adjusted waist circumference index with Klotho in the United States: differences by sex

The relationship between the weight-adjusted waist circumference index (WWI) and the senescence-inhibitory protein Klotho remains unknown. Therefore, this study aimed to investigate the relationship between WWI and soluble Klotho (s-Klotho). This study analyzed 9,928 participants based on the 2007-2016 National Health and Nutrition Examination Survey (NHANES). Three multiple linear regression models and a restricted cubic spline (RCS) were constructed to assess the association between WWI and s-Klotho levels. Further stratified analyses and interaction tests were performed to evaluate the stability of this association. Piecewise multivariate regression modeling was applied to detect threshold effects. The fully adjusted model showed a negative correlation between continuous WWI and s-Klotho levels (β = -23.65, 95% CI: -36.55, -10.76, P < 0.001). When WWI was grouped into quartiles, participants in the highest quartile had significantly lower circulating s-Klotho levels than those in the lowest quartile (β = -40.65, 95% CI: -64.20, -17.10, P = 0.001). The RCS curves showed a linear negative correlation between WWI and s-Klotho. Further stratified analyses showed that the correlation between WWI and s-Klotho remained stable in most conditions, except for gender. A nonlinear relationship and saturation effect were observed between WWI and s-Klotho in females, with an inflection point of 11.38 cm/√kg (P for overall < 0.001; P for non-linearity = 0.013). However, no significant correlation was observed in males. There is a significant negative correlation between WWI and s-Klotho levels. Proper management of central obesity in middle-aged and older women may be beneficial in delaying senescence.

Association of Klotho and Gout in Middle-Aged and Older Adults: National Health and Nutrition Survey (2007-2016)

BACKGROUND

Klotho, which is known to negatively regulate metabolic disorders and kidney disease, has a role in gout that remains unclear. This research explored how klotho levels correlate with the prevalence of gout.

METHODS

Participants aged 40 to 79 from the National Health and Nutrition Examination Survey (2007-2016) were examined in both lines. The connection between klotho levels and gout was analyzed through weighted multivariate logistic regression. Restricted cubic splines were used to assess linearity and investigate the dose-response relationship. To ensure the stability of the results, subgroup and sensitivity analyses were conducted.

RESULTS

In total, 9660 individuals participated, with the weighted sample size calculated at 88,892,738.77. The group included 47.79% males (4793), with the median age being 57.00 years. Upon adjusting for all covariates, the multivariate analysis indicated an odds ratio of 0.51 (95% confidence interval [CI]: 0.33~0.78, p = 0.003) for the likelihood of occurrence of gout. When compared with the lowest klotho quartile Q1 (≥151.3, <655.3 pg/mL), the adjusted odds ratios for the subsequent quartiles Q2 (≥655.5, <800.9 pg/mL), Q3 (≥801.0, <991.6 pg/mL), and Q4 (≥991.7, ≤3998.5 pg/mL) were 0.97 (95% CI: 0.68~1.38), 0.78 (95% CI: 0.50~1.21), and 0.48 (95% CI: 0.32~0.73), respectively. Analyses focusing on subgroups and sensitivity confirmed these results.

CONCLUSIONS

This research found a negative correlation between serum α-klotho concentrations and the occurrence of gout. Those with the highest levels of klotho exhibited the lowest likelihood of gout, indicating potential importance for future studies and clinical uses.

The relationship between serum α-Klotho with all-cause and cause-specific mortality

AIMS

The relationship between α-Klotho (αK) and mortality is controversial and has not been examined in a large, diverse cohort. We investigated the association between serum αK protein levels with all-cause and cause-specific mortality in a cohort representative of the US population.

METHODS

We used National Health and Nutrition Examination Survey (NHANES) data from 2007 to 2016. A nonlinear association between mortality and αK levels as a quadratic variable were examined using Cox proportional hazard models and competing risk models. Multivariable models were adjusted for age, gender, race, hypertension, diabetes, smoking, alcohol use, physical activity, body mass index (BMI), serum cholesterol, estimated glomerular filtration rate, highest educational status attained and family income to poverty threshold ratio.

RESULTS

Of the 13 749 participants, 1569 (11%) died, 7092 (52%) were female, and 5918 (43%) were Caucasian. The mean (SD) of age was 58 (11) years, BMI 29.7 (6.7) kg/m2, and αK was 0.85 (0.31) ng/mL. In the adjusted Cox proportional hazards model with quadratic αK, we found a U-shaped relationship between all-cause mortality and αK levels (continuous αK hazard ratio [HR] = 0.56, 95% confidence interval [CI]: 0.37, 0.85; P = .007; squared-αK HR = 1.25, 95% CI: 1.11, 1.41; P < 0.001). A similar U-shaped relationship was noted between αK and cancer mortality in the adjusted Cox proportional hazards model (continuous αK HR = 0.45, 95% CI: 0.19, 1.06; P = 0.07; squared αK HR = 1.32, 95% CI: 1.07, 1.61; P = 0.009). No relationship was present with cardiovascular or other-cause mortality.

CONCLUSIONS

In this large diverse cohort, we report a U-shaped relationship between αK with all-cause and cancer mortality. Further research to elucidate the underlying biological mechanism of these relationships is needed.

Systemic immune-inflammation mediates the association between Klotho protein and metabolic syndrome: findings from a large-scale population-based study

BACKGROUND

This study utilized large-scale population data from the National Health and Nutrition Examination Survey (NHANES) to elucidate the relationship between the Klotho protein and metabolic syndrome along with its components. We further investigated the possible mediating effect of inflammation on these relationships. Our objective was to identify biomarkers for risk stratification and potential therapeutic targets for metabolic syndrome.

METHODS

This study enrolled 13,119 participants aged 40-79 years, spanning five NHANES cycles from 2007 to 2016, with complete information on metabolic syndrome and the Klotho protein. The definition of metabolic syndrome followed the criteria of the National Cholesterol Education Program-Adult Treatment Panel III. Survey-weighted logistic regression and subgroup analysis were used to explore the associations between serum Klotho protein levels and metabolic syndrome, along with its components. Mediation analysis was performed to investigate the mediating effects of inflammation-related markers, including white blood cells, neutrophils, lymphocytes, monocytes, the neutrophil-to-lymphocyte ratio (NLR), the platelet-to-lymphocyte ratio (PLR), the systemic immune-inflammation index (SII) and the monocyte-to-HDL ratio (MHR), with the aim of elucidating how the Klotho protein influences the onset and progression of metabolic syndrome.

RESULTS

The study participants had an average age of 56.06 years (95% CI: 55.76-56.37), with a Klotho protein concentration of 798.10 pg/ml (95% CI: 656.50-980.50) and a 43.77% prevalence of metabolic syndrome (n = 5742). In the crude model, Klotho was negatively correlated with metabolic syndrome and its components, including central obesity, hypertension, and hypertriglyceridemia. After adjusting for all confounding factors, Klotho was demonstrated to be negatively associated only with metabolic syndrome (OR: 0.82, 95% CI: 0.70-0.97), hypertension (OR: 0.83, 95% CI: 0.70-0.98), and hypertriglyceridemia (OR: 0.78, 95% CI: 0.67-0.91). Subgroup and interaction analyses revealed significant interactions between age, sex, race/ethnicity, body mass index, and Klotho. Additionally, mediation analysis demonstrated that leukocytes, neutrophils and monocytes accounted for 34.78%, 31.91% and 7.13%, respectively, of the associations between Klotho and metabolic syndrome.

CONCLUSION

The serum concentration of Klotho protein was negatively associated with metabolic syndrome, with the relationship being partly mediated by systemic immune inflammation. The findings of this research revealed that the Klotho protein may be a valuable biomarker for risk stratification and a potential therapeutic target for metabolic syndrome.

Gender-specific association between circulating serum Klotho and metabolic components in adults

BACKGROUND

Klotho plays a pivotal role in human aging. Metabolic syndrome (MetS) is composed of multiple conditions that are also risk factors for cardiovascular disease and diabetes. We try to discuss gender-specific differences in Klotho and the associations between Klotho and MetS components.

MATERIALS AND METHODS

The National Health and Nutrition Examination Survey database from cycle 2015-2016 was analyzed. MetS was defined according to the 2005 updated criteria by the American Heart Association and National Heart Lung and Blood Institute. Gender-specific differences in serum Klotho, and associations between Klotho level and MetS components were examined.

RESULTS

A total of 2475 participants (40-79 years old) with comprehensive data were included (52% women). In general, lower Klotho was associated with advanced age, male sex, tobacco use, elevated triglycerides, renal insufficiency, inflammation, low estradiol, and low sex hormone-binding globulin (SHBG). The correlation between MetS and Klotho was more obvious in women, mainly in waist circumference and triglyceride. There were no gender-specific differences in the associations between Klotho and renal dysfunction, but multivariate linear regression analysis showed gender differences in other factors associated with Klotho. Estradiol, SHBG, high-density lipoprotein cholesterol (HDL), and high-sensitivity C-reactive protein (CRP) were associated with Klotho levels independent of age and renal function in men, whereas in women, Klotho was independently associated with triglycerides and white blood cell count.

CONCLUSION

Klotho levels had gender disparities regardless of age, renal function, and sex hormones. In the current cohort, triglycerides were the major component of MetS that was independently associated with serum Klotho levels, and the association was particularly seen in women. However, HDL was found to be the male-specific MetS component independently associated with Klotho.

Insulin Resistance, a Risk Factor for Alzheimer's Disease: Pathological Mechanisms and a New Proposal for a Preventive Therapeutic Approach

Peripheral insulin resistance (IR) is a well-documented, independent risk factor for the development of type 2 diabetes, cardiovascular disease, cancer and cellular senescence. Recently, the brain has also been identified as an insulin-responsive region, where insulin acts as regulator of the brain metabolism. Despite the clear link between IR and the brain, the exact mechanisms underlying this relationship remain unclear. Therapeutic intervention in patients showing symptoms of neurodegenerative diseases has produced little or no results. It has been demonstrated that insulin resistance plays a significant role in the pathogenesis of neurodegenerative diseases, particularly cognitive decline. Peripheral and brain IR may represent a modifiable state that could be used to prevent major brain disorders. In this review, we will analyse the scientific literature supporting IR as a risk factor for Alzheimer's disease and suggest some therapeutic strategies to provide a new proposal for the prevention of brain IR and its consequences.

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.

Bibliometric study and review of Klotho research: global characteristics and trends from 2000 to 2023

BACKGROUND

Although Klotho-related research has seen a significant upsurge, the field lacks comprehensive analytical representation and in-depth exploration of pertinent areas such as prevailing research trends and key focus areas.

METHOD

This review presents a bibliometric analysis of literature data gathered from the Web of Science Core Collection databases from January 1, 2000, to April 30, 2023. Parameters such as co-authorship, co-citation, co-occurrence, and the emergence of publications, countries, categories, references, and keywords were scrutinized predominantly using Citespace software.

RESULTS

Our investigation amassed a total of 3548 papers, with the United States leading in the quantity of publications (1175, accounting for 33.12%), followed by China (867, representing 24.44%), and Japan (439, accounting for 12.37%). While the United States is preeminent in the overall volume of publications, Scotland holds prominence in terms of centrality. Out of a total of 96 subject categories, urology and nephrology (573), and endocrinology and metabolism (542) were the two leading domains of Klotho-related publications. The 2011 paper titled "FGF23 induces left ventricular hypertrophy" by Faul C et al. holds the distinction of being the most frequently cited. The keywords "fibroblast growth factor 23," "phosphate homeostasis," and "functional variants" demonstrated the highest intensity, underscoring the potential of these research areas.

CONCLUSION

As the volume of literature grows, the role of Klotho in disease management and its applicability as a marker in disease progression warrant vigilant tracking and study.

U-shaped association between serum Klotho and accelerated aging among the middle-aged and elderly US population: a cross-sectional study

BACKGROUND

Phenotypic age acceleration, which reflects the difference between phenotypic age and chronological age, is an assessment to measure accelerated aging. Klotho is a protein related to slower aging, but its association with accelerated aging remains unclear.

METHODS

Based on data from the 2007-2010 National Health and Nutrition Examination Survey, phenotypic age was calculated using chronological age and 9 aging-related biomarkers. A total of 4388 participants aged 40 to 79 years with measured serum Klotho and calculated phenotypic age were enrolled. The association between serum Klotho and phenotypic age acceleration was estimated using multivariable linear regression models. The possible nonlinear relationship was examined with smooth curve fitting. We also conducted a segmented regression model to examine the threshold effect.

RESULTS

The association between serum Klotho and phenotypic age acceleration followed a U-shaped curve (p for nonlinearity < 0.001), with the inflection point at 870.7 pg/ml. The phenotypic age acceleration significantly decreased with the increment of serum Klotho (per SD increment: β -1.77; 95% CI, -2.57 ~ -0.98) in participants with serum Klotho < 870.7 pg/ml, and increased with the increment of serum Klotho (per SD increment:β, 1.03; 95% CI: 0.53 ~ 1.54) in participants with serum Klotho ≥ 870.7 pg/ml.

CONCLUSION

There was a U-shaped association between serum Klotho and accelerated aging among the middle-aged and elderly US population.

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

Aging is not a disease; it is a natural evolution of human physiology. Medical advances have extended our life expectancy, but chronic diseases and geriatric syndrome continue to affect the increasingly aging population. Yet modern medicine perpetuates an approach based on treatment rather than prevention and education. In order to help solve this ever-growing problem, a new discipline has emerged: lifestyle medicine. Nutrition, physical activity, stress management, restorative sleep, social connection, and avoidance of risky substances are the pillars on which lifestyle medicine is founded. The aim of this discipline is to increase healthspan and reduce the duration of morbidity by making changes to our lifestyle. In this review, we propose the use of klotho protein as a novel biomarker for lifestyle medicine in order to quantify and monitor the health status of individuals, as no integrative tool currently exists.

Emerging role of α-Klotho in energy metabolism and cardiometabolic diseases

BACKGROUND AND AIM

Klotho was first identified as a gene associated with aging and longevity in 1997. α-Klotho is an anti-aging protein and its role in energy metabolism, various cardiovascular diseases (CVDs), and metabolic disorders is increasingly being recognized. In this review, we aimed to outline the potential protective role and therapeutic prospects of α-Klotho in energy metabolism and cardiometabolic diseases (CMDs).

METHODS

We comprehensively reviewed the relevant literature in PubMed using the keywords 'Klotho', 'metabolism', 'cardiovascular', 'diabetes', 'obesity', 'metabolic syndrome', and 'nonalcoholic fatty liver disease'.

RESULTS

α-Klotho can be divided into membrane-bound Klotho, secreted Klotho, and the most studied circulating soluble Klotho that can act as a hormone. Klotho gene polymorphisms have been implicated in energy metabolism and CMDs. α-Klotho can inhibit insulin/insulin growth factor-1 signaling and its overexpression can lead to a 'healthy insulin resistance' and may exert beneficial effects on the regulation of glycolipid metabolism and central energy homeostasis. α-Klotho, mainly serum Klotho, has been revealed to be protective against CVDs, diabetes and its complications, obesity, and nonalcoholic fatty liver disease. Human recombinant Klotho protein/Klotho gene delivery, multiple drugs, or natural products, and exercise can increase α-Klotho expression.

CONCLUSION

Overall, α-Klotho has demonstrated its potential as a promising target for modulating energy metabolism and CMDs, and further research is needed to explore its utilization in clinical practice in the future.

Birth size and the serum level of biological age markers in men

Previous studies showed that intrauterine growth restrictions, resulting in smaller body size at birth, are associated with altered development and the risk of age-related diseases in adult life. Thus, prenatal development may predict aging trajectories in humans. The study aimed to verify if body size at birth is related to biological age in adult men. The study sample consisted of 159 healthy, non-smoking men with a mean age of 35.24 (SD 3.44) years. Birth weight and length were taken from medical records. The ponderal index at birth was calculated. Biological age was evaluated based on serum levels of s-Klotho, hsCRP, DHEA/S, and oxidative stress markers. Pregnancy age at birth, lifestyle, weight, cortisol, and testosterone levels were controlled. The results showed no relationship between birth size and s-Klotho, DHEA/S level, inflammation, or oxidative stress. Also, men born as small-for-gestational-age (N = 49) and men born as appropriate-for-gestational-age (N = 110) did not differ in terms of biological age markers levels. The results were similar when controlled for pregnancy week at birth, chronological age, BMI, testosterone, or cortisol level. The results suggest that there is no relationship between intrauterine growth and biomarkers of aging in men aged 30-45 years from the affluent population.

The association of serum Klotho concentrations with hyperlipidemia prevalence and lipid levels among US adults: a cross-sectional study

BACKGROUND

Klotho has anti-oxidative and anti-inflammatory properties. However, little is known about whether high Klotho concentrations were associated with reduced hyperlipidemia risk and improved plasma lipid levels.

METHODS

Participants with complete data on serum Klotho and plasma lipid concentrations from the 2007-2016 National Health and Nutrition Examination Survey were included. Weighted regression models were fitted to explore the association of Klotho concentrations with hyperlipidemia risk and plasma lipid levels while restricted cubic spline models were applied to explore the dose-response relationship. Additionally, we assessed the mediating effects of C-reaction protein (CRP) on the foregoing association.

RESULTS

Individuals in the fourth and fifth quintile of serum Klotho had an adjusted odds ratio (OR) of 0.77 (95%CI: 0.65, 0.93) and 0.67 (95%CI: 0.65, 0.93) for hyperlipidemia. Doubling of serum Klotho concentrations was associated with decreased hyperlipidemia risk (OR = 0.81; 95%CI: 0.68, 0.95) and triglyceride levels (13.25 mg/dL; 95%CI: 4.02, 22.47), with a monotonic dose-response relationship. Individuals in the fourth and fifth quintile of serum Klotho had a 0.07 (95%CI: 0.002, 0.13), 0.08 (95%CI: 0.02, 0.15) and 0.05 (95%CI: -0.03, 0.12) mg/dL decreased CRP levels, with a marginally significant trend (Ptrend = 0.05).

CONCLUSIONS

Higher Klotho concentrations were associated with reduced hyperlipidemia risk and triglyceride levels. Klotho supplementation maybe a promising method to intervene and prevent hyperlipidemia, but the underlying mechanism should be further explored.

The role of Klotho and FGF23 in cardiovascular outcomes of diabetic patients with chronic limb threatening ischemia: a prospective study

Cardiovascular complications after lower extremity revascularization (LER) are common in diabetic patients with peripheral arterial disease (PAD) and chronic limb threatening ischemia (CLTI). The Klotho-fibroblast growth factor 23 (FGF23) axis is associated with endothelial injury and cardiovascular risk. We aimed to analyze the relationship between Klotho and FGF23 serum levels and the incidence of major adverse cardiovascular events (MACE) and major adverse limb events (MALE) after LER in diabetic patients with PAD and CLTI. Baseline levels of Klotho and FGF23, and their association with subsequent incidence of MACE and MALE were analyzed in a prospective, non-randomized study in a population of diabetic patients with PAD and CLTI requiring LER. A total of 220 patients were followed for 12 months after LER. Sixty-three MACE and 122 MALE were recorded during follow-up period. Baseline lower Klotho serum levels (295.3 ± 151.3 pg/mL vs. 446.4 ± 171.7 pg/mL, p < 0.01), whereas increased serum levels FGF23 (75.0 ± 11.8 pg/mL vs. 53.2 ± 15.4 pg/mL, p < 0.01) were significantly associated with the development of MACE. Receiver operating characteristic (ROC) analysis confirmed the predictive power of Klotho and FGF23 baseline levels. Furthermore, decreased Klotho levels were associated with the occurrence of MALE after LER (329.1 ± 136.8 pg/mL vs 495.4 ± 183.9 pg/mL, p < 0.01). We found that Klotho and FGF23 baseline levels are a potential biomarker for increased cardiovascular risk after LER in diabetic patients with PAD and CLTI.

Serum klotho concentrations in older men with hypertension or type 2 diabetes during prolonged exercise in temperate and hot conditions

PURPOSE

Klotho is a cytoprotective protein that increases during acute physiological stressors (e.g., exercise heat stress), although age-related declines in klotho may underlie cellular vulnerability to heat stress. The present study aimed to compare serum klotho in healthy older men and men with type 2 diabetes (T2D) or hypertension (HTN) during prolonged exercise in temperate or hot conditions.

METHODS

We evaluated serum klotho in 12 healthy older men (mean [SD]; 59 years [4]), 10 men with HTN (60 years [4]), and 9 men with T2D (60 years [5]) before and after 180 min of moderate-intensity (fixed metabolic rate of 200 W/m²; ~ 3.4 METs) exercise and 60 min of recovery in temperate (wet-bulb globe temperature (WBGT) 16 °C) and hot (WBGT 32 °C) environments. Core temperature (rectal), heart rate (HR), and heart rate reserve (HRR) were measured continuously while klotho was measured at the end of baseline, exercise, and recovery.

RESULTS

Total exercise duration was reduced during the hot condition in older men with HTN and T2D than healthy older men (both p ≤ 0.049), despite similar core temperatures, HR, and HRR. Klotho was higher than rest following exercise in the heat in healthy older men (+ 191 pg/mL [189]; p < 0.001) and responses were greater (p = 0.036) than men with HTN (+ 118 pg/mL [49]; p = 0.030), although klotho did not increase in men with T2D (+ 4 pg/mL [71]; p ≥ 0.638).

CONCLUSION

Given klotho's role in cytoprotection, older men with HTN and especially T2D may be at increased cellular vulnerability to prolonged exercise or physically demanding exercise in the heat.

The Association of Obesity and the Antiaging Humoral Factor Klotho in Middle-Aged and Older Adults

Objectives

Previous studies have reported conflicting results regarding the relationship between obesity and the antiaging humoral factor klotho. Thus, the present study aimed to examine the association of anthropometric measurements, weight history change, and vitamin D status with serum klotho levels.

Methods

The National Health and Nutrition Examination Survey data were used to compare sex-specific logarithm transformed serum klotho levels across standardized anthropometric measurements and weight change history in subjects aged 40-79 years. The baseline measured height, and self-reported weight were used to calculate the body mass index (BMI) at two-time intervals: age 25 and ten years before the measured BMI. Subjects were then categorized as never obese, obese to nonobese, nonobese to obese, and always obese.

Results

Of 4,971 participants, the prevalence of general obesity was 41%, and abdominal obesity (waist circumference ≥88 cm) was present in 75% of women. Overall, lower serum klotho levels were seen in older adults, men, nonsmokers, alcohol users, and those with an estimated glomerular filtration rate (eGFR) < 60 ml/min. Multivariate models demonstrated that general and abdominal obesity in women was inversely associated with serum klotho levels. Moreover, women who developed obesity from age 25 and ten years before the baseline BMI had significantly lower mean klotho levels at 765.0 and 757.4 pg/ml compared with 820.5 pg/ml (p < 0.05) among those that were never obese, respectively. In contrast, serum klotho levels did not significantly differ among men, irrespective of their weight history. In a subanalysis, higher klotho levels were seen in participants with an adequate vitamin D status (≥50 nmol/L) than their overweight and obese counterparts (p < 0.05).

Conclusions

Obesity among women was significantly and inversely associated with serum klotho levels. Similarly, women who developed obesity during their lifetime had consistently lower klotho levels than their never-obese counterparts.

References Values of Soluble α-Klotho Serum Levels Using an Enzyme-Linked Immunosorbent Assay in Healthy Adults Aged 18-85 Years

α-Klotho protein is a powerful predictor of the aging process and lifespan. Although lowered circulating soluble α-Klotho levels have been observed in aged non-healthy individuals, no specific reference values across a wide range of ages and sex using an enzyme-linked immunosorbent assay (ELISA) are available for larger cohorts of healthy individuals. The present analytical cross-sectional study was aimed to establish the reference values of soluble α-Klotho serum levels in healthy adults by age and sex groups. A total of 346 (59% women) healthy individuals aged from 18 to 85 years were recruited. Subjects were divided by sex and age as: (i) young (18−34.9 years), (ii) middle-aged (35−54.9 years), and (iii) senior (55−85 years) individuals. The soluble α-Klotho levels were measured in serum using ELISA. Senior adults were the age-group that presented the lowest soluble α-Klotho serum levels (p < 0.01), with age showing a negative association with soluble α-Klotho serum levels (p < 0.001). No differences between sexes were observed. Therefore, soluble α-Klotho levels were especially decreased—regardless of sex—in our cohort of healthy individuals because of the physiological decline derived from the aging process. We recommend routine assessments of soluble α-Klotho levels using ELISA as a simple and cheap detectable marker of aging that improves quality of life in the elderly.