Relationship of low-circulating "anti-aging" klotho hormone with disability in activities of daily living among older community-dwelling adults.

The aging suppressor gene klotho encodes a single-pass transmembrane protein klotho that in mice is known to extend life span when overexpressed and to resemble accelerated aging, with skeletal muscle atrophy and decreased bone mineral density, when expression is disrupted. We sought to examine the relationship between plasma klotho and disability in activities of daily living (ADL) in older community-dwelling adults. In a cross-sectional study, plasma klotho was measured in a population-based sample of 802 adults, ≥ 65 years, who participated in the "Invecchiare in Chianti" (Aging in the Chianti Area) (InCHIANTI) study in Tuscany, Italy. The overall proportion of adults with ADL disability was 11.9%. Mean (standard deviation) klotho concentrations were 689 (238) pg/mL. From the lowest to the highest tertile of plasma klotho, 16.1%, 9.7%, and 5.6% of participants, respectively, had ADL disability (p=0.0004). Plasma klotho, per 1 standard deviation increase, was associated with ADL disability (odds ratio=0.57, 95% confidence interval 0.35-0.93, p=0.02) in a multivariate logistic regression model adjusting for age, education, cognition, physical activity, physical performance, total cholesterol, alcohol and tobacco use, and chronic diseases. Low plasma klotho concentrations were independently associated with ADL disability among older community-dwelling men and women.

Relationship of serum fibroblast growth factor 21 with abnormal glucose metabolism and insulin resistance: the Baltimore Longitudinal Study of Aging.

CONTEXT: The relationship of fibroblast growth factor 21 (FGF21) with glucose metabolism and insulin resistance has not been well characterized in community-dwelling adults. OBJECTIVE: The objective of the study was to examine the relationship of FGF21 with glucose metabolism and insulin resistance. DESIGN: Serum FGF21, fasting plasma glucose (FPG), glucose tolerance, and insulin resistance were measured in a cross-sectional study, 2002-2007. SETTING: The study was the Baltimore Longitudinal Study of Aging, a natural history cohort study of aging in community-dwelling men and women. PARTICIPANTS: Seven hundred adults, mean age 63.3 yr, participated in the study. MAIN OUTCOME MEASURES: FPG, 2-h plasma glucose, homeostasis model of insulin resistance, whole-body insulin sensitivity (Matsuda index), glucose area under the curve (AUC), and insulin AUC were measured. RESULTS: Overall, the median (25th and 75th percentiles) FGF21 concentration was 225 (126, 370) pg/ml. The proportion of adults with normal, impaired, and diabetic FPG was 77.0, 21.4, and 1.6%, and those with normal, impaired, and diabetic 2-h plasma glucose was 76.7, 19.1, and 4.1%, respectively. Log serum FGF21 (picograms per milliliter), per 1 sd increase, was associated with an FPG (odds ratio 1.43, 95% confidence interval 1.15, 1.77, P = 0.001) and with 2-h plasma glucose (odds ratio 1.39, 95% confidence interval 1.12, 1.73, P = 0.003), in respective multivariate, ordered logistic regression models, adjusted for potential confounders. Serum FGF21 (picograms per milliliter) was associated with the homeostasis model of insulin resistance, the Matsuda index, glucose AUC, and insulin AUC (all P < 0.0001) in respective multivariable linear regression models adjusted for potential confounders. CONCLUSIONS: Higher serum FGF21 concentrations were associated with abnormal glucose metabolism and insulin resistance in community-dwelling adults.

Relationship of low plasma klotho with poor grip strength in older community-dwelling adults: the InCHIANTI study.

Handgrip strength is a strong indicator of total body muscle strength and is a predictor of poor outcomes in older adults. The aging suppressor gene klotho encodes a single-pass transmembrane protein that is secreted as a circulating hormone. In mice, disruption of klotho expression results in a syndrome that includes sarcopenia, atherosclerosis, osteoporosis, and shortened lifespan, and conversely, overexpression of klotho leads to a greater longevity. The objective was to determine whether plasma klotho levels are related to skeletal muscle strength in humans. We measured plasma klotho in 804 adults, ≥65 years, in the InCHIANTI study, a longitudinal population-based study of aging in Tuscany, Italy. Grip strength was positively correlated with plasma klotho at threshold <681 pg/mL. After adjusting for age, sex, education, smoking, physical activity, cognition, and chronic diseases, plasma klotho (per 1 standard deviation increase) was associated with grip strength (beta = 1.20, standard error = 0.35, P = 0.0009) in adults with plasma klotho <681 pg/mL. These results suggest that older adults with lower plasma klotho have poor skeletal muscle strength.

Serum fibroblast growth factor-23 and risk of incident chronic kidney disease in older community-dwelling women.

BACKGROUND AND OBJECTIVES: Elevated circulating fibroblast growth factor 23 (FGF23) predicts progression of CKD, but it is unknown whether circulating FGF23 independently predicts incident CKD. This study aimed to determine whether circulating FGF23 predicts incident CKD in community-dwelling women. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: This study examined the relationship of intact serum FGF23, 1,25-dihydroxyvitamin D(3) (1,25[OH](2)D), 25-hydroxyvitamin D (25[OH]D), parathyroid hormone, calcium, and phosphate with prevalent and incident CKD in 701 disabled women, ≥65 years of age, from the Women's Health and Aging Study I in Baltimore, Maryland, from 1993 to 1997. Incident CKD was defined as a low estimated GFR (eGFR) <60 ml/min per 1.73 m(2) only, low eGFR <60 ml/min per 1.73 m(2) and a ≥25% decline in eGFR from baseline, and an increase in serum creatinine (≥0.4 mg/dl) at follow-up. RESULTS: At baseline, 381 women (54.3%) had stage 3 CKD. Of 307 women without CKD at baseline, 63 (20.5%) developed stage 3 CKD over 24 months of follow-up. After excluding prevalent cases of CKD, FGF23 (per 1 SD increase) was associated with incident stage 3 CKD (hazard ratio [HR], 1.51; 95% confidence interval [95% CI], 1.06, 2.16; P=0.02), low and declining eGFR (HR, 3.69; 95% CI, 1.68, 8.11; P=0.001), and increase in serum creatinine (HR, 5.35; 95% CI, 1.27, 22.54; P=0.02) in respective multivariable Cox proportional hazards models adjusting for baseline eGFR, age, race, phosphate, 1,25-dihydroxyvitamin D(3), parathyroid hormone, and other potential confounders. CONCLUSIONS: Elevated FGF23 is an independent risk factor for incident CKD in older, disabled, community-dwelling women.

Plasma klotho and cardiovascular disease in adults.

OBJECTIVES: To determine whether plasma klotho, a recently discovered hormone that has been implicated in atherosclerosis, is related to prevalent cardiovascular disease (CVD) in adults. DESIGN: Cross-sectional. SETTING: Population-based sample of adults residing in Tuscany, Italy. PARTICIPANTS: One thousand twenty-three men and women aged 24 to 102 participating in the Invecchiare in Chianti (InCHIANTI) study. MEASUREMENTS: Anthropometric measures, plasma klotho, fasting plasma total, high-density lipoprotein cholesterol (HDL-C), triglycerides, glucose, creatinine, C-reactive protein (CRP). Clinical measures: medical assessment, diabetes mellitus, hypertension, coronary heart disease, heart failure, stroke, peripheral artery disease, cancer, chronic kidney disease. Logistic regression models were used to examine the relationship between plasma klotho and prevalent CVD. RESULTS: Of 1,023 participants, 259 (25.3%) had CVD. Median (25th, 75th percentile) plasma klotho concentrations were 676 pg/mL (530, 819 pg/mL). Plasma klotho was correlated with age (correlation coefficient (r) = -0.14, P < .001), HDL-C (r = 0.11, P<.001), and CRP (r = -0.10, P < .001) but not systolic blood pressure, fasting plasma glucose, or renal function. Plasma klotho age-adjusted geometric means were 626 pg/mL (95% confidence interval (CI) = 601-658 pg/mL) in participants with CVD and 671 pg/mL (95% CI = 652-692 pg/mL) in those without CVD (P = .001). Adjusting for traditional cardiovascular risk factors (age, sex, smoking, total cholesterol, HDL-C, systolic blood pressure, and diabetes mellitus), log plasma klotho was associated with prevalent CVD (odds ratio per 1 standard deviation increase = 0.85, 95% CI = 0.72-0.99). CONCLUSION: In community-dwelling adults, higher plasma klotho concentrations are independently associated with a lower likelihood of having CVD.

Relationship of serum fibroblast growth factor 23 with cardiovascular disease in older community-dwelling women.

OBJECTIVE: Although fibroblast growth factor 23 (FGF23) has been implicated in the pathogenesis of cardiovascular disease, the relationship between FGF23 and cardiovascular disease has not been well characterized in the general population. The aim of this study was to determine whether serum FGF23 is independently associated with cardiovascular disease in older community-dwelling women. DESIGN AND METHODS: A cross-sectional design was used to examine the relationship between serum FGF23 and cardiovascular disease. The subjects consisted of a population-based sample of 659 women, aged 70-79 years, who participated in the Women's Health and Aging Studies in Baltimore, Maryland. Prevalent cardiovascular disease (coronary heart disease, stroke, congestive heart failure, and peripheral artery disease) was assessed through diagnostic algorithms and physician adjudication. RESULTS: Of the 659 women, 185 (28.1%) had cardiovascular disease. Median (25th, 75th percentile) intact serum FGF23 was 34.6 (25.2, 46.2) pg/ml. The prevalence of cardiovascular disease in the lowest, middle, and highest tertile of serum FGF23 was 22.6, 24.9, and 36.7% respectively (P=0.002). Serum log FGF23 was associated with cardiovascular disease (odds ratio per 1 s.d. increase=1.23, 95% confidence interval 1.17, 1.30; P<0.0001) in a multivariable logistic regression model, adjusting for age, race, smoking, education, body mass index, cognition, diabetes, hypertension, physical activity, total cholesterol, high-density lipoprotein cholesterol, and renal function. CONCLUSION: Elevated serum FGF23 concentrations are independently associated with prevalent cardiovascular disease in older community-dwelling women. Further studies are needed to elucidate the potential biological mechanisms by which FGF23 may be involved in the pathogenesis of cardiovascular disease.

Plasma klotho and mortality risk in older community-dwelling adults.

BACKGROUND: The aging-suppressor gene klotho encodes a single-pass transmembrane protein that in mice is known to extend life span when overexpressed and resemble accelerated aging when expression is disrupted. It is not known whether there is a relationship between plasma levels of secreted klotho protein and longevity in humans. METHODS: We measured plasma klotho in 804 adults, greater than or equal to 65 years, in the InCHIANTI study, a longitudinal population-based study of aging in Tuscany, Italy. RESULTS: During 6 years of follow-up, 194 (24.1%) of the participants died. In a multivariate Cox proportional hazards model, adjusting for age, sex, education, body mass index, physical activity, total cholesterol, high-density lipoprotein cholesterol, cognition, 25-hydroxyvitamin D, parathyroid hormone, serum calcium, mean arterial pressure, and chronic diseases, participants in the lowest tertile of plasma klotho (<575 pg/mL) had an increased risk of death compared with participants in the highest tertile of plasma klotho (>763 pg/mL; hazards ratio 1.78, 95% confidence interval 1.20-2.63). CONCLUSIONS: In older community-dwelling adults, plasma klotho is an independent predictor of all-cause mortality. Further studies are needed to elucidate the potential biological mechanisms by which circulating klotho could affect longevity in humans.

Endogenous secretory receptor for advanced glycation end products and chronic kidney disease in the elderly population.

BACKGROUND/AIMS: The relationship of circulating endogenous secretory receptor for advanced glycation end products (esRAGE) and chronic kidney disease (CKD) has not been well characterized. The aim of the study was to determine whether plasma esRAGE is associated with CKD and is predictive of developing CKD in older adults. METHODS: The relationship between plasma esRAGE and CKD (more than stage 3 of the National Kidney Foundation classification; estimated glomerular filtration rate <60 ml/min/1.73 m(2)) and CKD over 6 years of follow-up was examined in a cross-sectional and prospective study design in 1,016 men and women, ≥65 years, in the InCHIANTI study, a population-based cohort study of aging in Tuscany, Italy. RESULTS: At enrollment, 158 (15.5%) had CKD. Mean (SD) plasma esRAGE was 0.45 (0.24) ng/ml. Plasma esRAGE (ng/ml) was associated with CKD (odds ratio per 1 SD = 1.30; 95% CI 1.1-1.6; p < 0.005) in a multivariable logistic regression model, adjusting for potential confounders. Plasma esRAGE was an independent predictor of incident CKD over 6 years of follow-up (hazard ratio per 1 SD = 1.37; 95% CI 1.1-1.7; p < 0.008) in a multivariable Cox proportional hazards model, adjusting for potential confounders. CONCLUSIONS: Elevated plasma esRAGE is independently associated with CKD and is an independent predictor of incident CKD in older community-dwelling adults.

Endogenous secretory receptor for advanced glycation end products is associated with low serum interleukin-1 receptor antagonist and elevated IL-6 in older community-dwelling adults.

BACKGROUND: Advanced glycation end products (AGEs) are thought to cause inflammation through interaction with the receptor for AGEs (RAGE), therefore contributing to adverse aging-related processes. The relationship between AGEs, RAGE, and inflammation has not been well characterized. METHODS: We examined the relationship of plasma endogenous secretory RAGE (esRAGE); carboxymethyl-lysine (CML), a circulating AGE; and inflammatory mediators in 1,298 adults, 20-97 years, who participated in the InCHIANTI study in Tuscany, Italy. Blood levels of esRAGE, CML, interleukin-1 receptor antagonist (IL-1RA), IL-1ß, tumor necrosis factor-α (TNF-α), IL-6, IL-6 receptor (IL-6R), IL-18, C-reactive protein (CRP), transforming growth factor-ß (TGF-ß), and fibrinogen were measured. RESULTS: Log plasma esRAGE was associated with log IL-1RA (ß = -0.069, SE = 0.036, p = .05) and log IL-6 (ß = 0.077, SE = 0.035, p = .03), respectively, in separate multivariable linear regression models, adjusting for potential confounders. Log plasma esRAGE was also negatively associated with log TGF-ß but did not reach statistical significance (ß = -0.091, SE = 0.053, p = .09). Log plasma esRAGE was not significantly associated with log IL-1ß, log TNF-α, IL-6R, log IL-18, or CRP. Log plasma CML was not associated with any of the inflammatory mediators except for IL-6R (ß = -14.10, SE = 5.94, p = .02) and fibrinogen (ß = 13.95, SE = 7.21, p = .05) in separate multivariable models, adjusting for potential confounders. CONCLUSIONS: Plasma esRAGE is correlated with higher IL-6 and lower IL-1RA. These findings suggest that plasma esRAGE plays a role in modulating inflammation, although the exact mechanisms remain to be elucidated.