Serum α-Klotho Levels Research Articles

The Effects of Cholecalciferol Supplementation on FGF23 and α-Klotho in Hemodialysis Patients With Hypovitaminosis D: A Randomized, Double-Blind, Placebo-Controlled Trial

Vitamin D-fibroblast growth factor-23 (FGF-23)-klotho forms an axis that takes part at least in cardiovascular complications in patients with chronic kidney disease. This study aimed to assess the effects of cholecalciferol supplementation on FGF23 and α-klotho in patients with hypovitaminosis D requiring hemodialysis. In a single-center, parallel-arm, randomized, double-blind, placebo-controlled trial, 86 patients with hypovitaminosis D requiring hemodialysis were enrolled. The patients were randomized into 2 groups (n=43 each) to receive either 50,000 IU of cholecalciferol or placebo every week for 12weeks. Accordingly, the serum levels of FGF23 and klotho were measured by ELISA and compared between both groups. Serum 25OH(D) levels increased in participants who received cholecalciferol supplementation compared with participants who received placebo (P=.006). In addition, serum FGF23 decreased and α-klotho levels increased in the supplemented group compared with placebo. However, the before-after differences between cholecalciferol supplement and placebo were significant only for α-klotho (P=.035). These effects were not accompanied by changes in the levels of phosphate, total and ionized calcium, and intact parathyroid hormone. Cholecalciferol supplementation of 50,000 IU for 12weeks increases α-klotho levels in the serum of kidney failure patients undergoing hemodialysis. This may suggest that patients receiving maintenance hemodialysis can benefit from using cholecalciferol supplementation and increase in serum α-klotho levels.

Serum αKlotho as a Predictor of Graft Dysfunction After Kidney Transplantation

ObjectiveTo improve the long-term survival rate after kidney transplantation (KTx), allograft injury should be identified as soon as possible. Regardless of aggressive immunosuppressive therapies, recipients of kidney transplants still have a significant risk of graft failure. No specific predictor for the progression of chronic kidney disease (CKD) after KTx has yet been found. Aberrant molecular mechanisms involving the αKlotho-fibroblast growth factor (FGF) 23 axis may be a useful determinant of renal impairment and graft failure over time. MethodsPlasma and spot urine samples were collected from 47 patients 1 year after KTx. Evaluation of renal function after KTx was performed using levels of biomarkers including serum intact FGF23, soluble αKlotho, 25(OH) vitamin D (25(OH)D), and the difference in the estimated glomerular filtration rate (eGFR) between the first and third year after KTx (ΔeGFR). ResultsThe median serum αKlotho, intact FGF23, and 25(OH)D were 516.3 pg/mL, 58.7 pg/mL, and 5.7 ng/mL, respectively. No marked changes in the standard biomarkers that regulate phosphate homeostasis were found. Serum αKlotho levels were associated with ΔeGFR. Multivariate regression analysis revealed that serum αKlotho levels significantly predicted a decrease in eGFR in the graft kidney 2 years after KTx, but serum 25(OH)D and FGF23 levels were not significant. Serum αKlotho levels showed an inverse correlation with fractional excretion of magnesium, which reflects tubular injury in the early stage of CKD. ConclusionMeasurement of serum αKlotho may serve as a useful predictor of KTx patients who require initiation of pre-emptive medication.

High-intensity physical exercise increases serum α-klotho levels in healthy volunteers

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High-intensity physical exercise increases serum α-klotho levels in healthy volunteers.

The recently discovered klotho proteins have roles in a diverse range of metabolic processes with the oldest protein, α-klotho, implicated in various cellular pathways in energy, glucose, and phosphate metabolism. Circulating soluble klotho (sKl), derived from membrane α-klotho cleavage, not only has effects on ion channels and insulin signaling pathways, but is inversely associated with mortality. Effects of physical exercise on sKl have not been well studied. The effect of a single high-intensity standardized exercise on sKl and serum phosphate (sPi) levels in healthy adults was investigated. A standard Bruce protocol treadmill exercise was undertaken by 10 fasting healthy volunteers. sKl, sPi, and blood glucose levels were measured in samples collected 1-week prior, immediately pre (T pre), 0 (T post), 30 (T 30), 240 (T 240) min, and 1-week after exercise. Median (interquartile range) age of participants was 47.5 (44–51) years; five (50%) were male. All study participants achieved at least 90% predicted maximum heart rate (MHR). sKl increased acutely after exercise (T pre median 448 pg/mL vs. T post median 576 pg/mL; p < 0.01). There was a nonsignificant sPi decline at T 30 (T pre 0.94 ± 0.12 mmol/L vs. T 30 0.83 ± 0.22 mmol/L). Exercise led to a reduction in blood glucose by T 240 with median glucose levels at T pre, T post, T 30, and T 240 of 6.0, 6.5, 6.3, and 5.7 mmol/L, respectively. In conclusion, a single high-intensity exercise session is associated with a transient increase in sKl, a delayed reduction in blood glucose, and a nonsignificant decrease in sPi levels in healthy adults. The evaluation of long-term effects of cardiovascular fitness programs on sKl and sPi in healthy individuals and disease cohorts are required to identify potential lifestyle modifications to help improve chronic disease management and long-term outcomes.

Endothelin-1, α-Klotho, 25(OH) Vit D levels and severity of disease in scleroderma patients.

Considering the role of endothelin-1 (ET-1) in tissue remodeling and fibrosis during the development of scleroderma as well as the effect of α-Klotho in pathogenesis of calcinosis and/or endothelial cell injury and its correlation with severity of disease, this study aimed to evaluate serum ET-1, α-Klotho and 25(OH) vitamin D levels in patients with limited and diffuse scleroderma compared to healthy subjects. In this cross-sectional study, 60 scleroderma patients according to the ACR/EULAR 2013 criteria and 60 age- and sex-matched healthy controls were included. In patients, clinical examination was performed and Medsger severity scale was assessed. Serum ET-1, soluble α-Klotho and 25(OH)D3 levels were measured using ELISA kits. The mean±SD age of patients and controls was 46.2±9.6 and 47.2±7.0years, respectively. Compared to healthy controls, serum ET-1 was significantly higher in SSc patients (p=0.001); whilst serum α-Klotho and 25(OH)D3 were significantly lower in patients (p=0.001). The most common organs involved in patients were skin, lung, peripheral vascular and gastrointestinal system and the severity of involvement was mainly mild and/or moderate. There were no significant differences in serum ET-1 and α-Klotho levels according to the severity of different organ involvement (p>0.05). There was no significant correlation between presence or absence of calcinosis and negative or positivity of auto-antibodies with ET-1, α-Klotho and 25(OH)D3 levels. Although our study revealed higher serum ET-1 and lower serum α-Klotho levels in SSc patients compared to healthy controls, there were not any significant correlations between their serum levels with severity of organ involvement.

Serum α-klotho levels are not informative for the evaluation of growth hormone secretion in short children.

α-Klotho is a transmembrane protein that can be cleaved and act as a circulating hormone (s-klotho). s-Klotho serum levels seem to reflect growth hormone (GH) secretory status. We investigated the role of s-klotho as a reliable marker of GH secretion in short children and the factors influencing its secretion. We enrolled 40 short Egyptian children (20 GH deficiency [GHD] and 20 idiopathic short stature [ISS]). They underwent a pegvisomant-primed insulin tolerance test (ITT) and were accordingly reclassified as 16 GHD and 24 ISS. The samples obtained before and 3 days after pegvisomant administration, prior to the ITT, were used for assaying insulin-like growth factor (IGF)-I and s-klotho. IGF-I and s-klotho serum levels were not significantly different (p=0.059 and p=0.212, respectively) between GHD and ISS. After pegvisomant, a significant reduction in IGF-I and s-klotho levels was found in both groups. s-Klotho significantly correlated only with IGF-I levels in both groups. s-Klotho mainly reflects the IGF-I status and cannot be considered a reliable biomarker for GH secretion in children.

Intact FGF23 and α-Klotho during acute inflammation/sepsis in CKD patients.

High FGF23 and low α-Klotho levels associate with systemic inflammation and reduced nitric oxide (NO) bioavailability, but the dynamics of this relationship in patients with CKD has not been investigated. We sequentially measured serum intact FGF23 and carboxyl-terminal (iFGF23, cFGF23), the iFGF23/cFGF23 ratio, αKlotho, biomarkers of inflammation (hs-CRP, IL-6 and TNF-α) and sepsis (procalcitonin), nitrotyrosine (reflecting NO synthesis and oxidative stress), serum iron and ferritin and CKD-MBD biomarkers, PTH, 25(OH)VD, 1,25(OH)2 VD at peak of intercurrent sepsis and after complete resolution in a series of 17 patients with CKD. At peak infection, biomarkers of inflammation/sepsis, ferritin and nitrotyrosine were all very high (all P < 0·01) and declined towards the normal range thereafter (P < 0·01). iFGF23 was 191 ± 10 pg/ml (geometric mean, SD) and doubled to 371 ± 8 pg/ml (P = 0·003) after the resolution of infection, while cFGF23 did not change (246 ± 5 pg/mL vs. 248 ± 5 pg/mL, P = 0·50). As a consequence, the iFGF23/cFGF23 ratio, an indicator of the proteolytic cleavage of the FGF23 molecule, was 0·78 ± 3·87 at peak infection and increased to 1·49 ± 3·00 after resolution of infection (P < 0·001). In contrast, serum α-Klotho levels were upregulated at peak infection (peak infection: 526 ± 4 pg/ml, postinfection: 447 ± 4 pg/ml, P = 0·001). The eGFR, PTH and vitamin D did not change significantly throughout. Acute inflammation/sepsis suppresses the active form of FGF23 and activates α-Klotho, the latter effect being likely attributable to enhance proteolysis of FGF23 molecule. iFGF23 downregulation and α-Klotho upregulation during acute sepsis may participate into the counter-regulatory response to severe inflammation in CKD patients with sepsis.

Impact of anemia correction on the production of the circulating morphogenetic protein α-Klotho in patients with Stages 3B-4 chronic kidney disease: A new direction of cardionephroprotection

To investigate the impact of anemia correction with erythropoiesis stimulants on the serum level of the circulating morphogenetic protein α-Klotho in patients with Stages 3B--4 chronic kidney disease (CKD). 64 patients aged 42±8 years with Stages 3B--4 nondiabetic CKD were examined and divided into 2 groups: 1) 32 patients with anemia (the target hemoglobin levels could be achieved and kept with erythropoietin and iron saccharate in 20 patients (Group A) and those could not be done in 12 patients (Group 1B). A control group (Group 2) consisted of 32 non-anemic patients matched for gender, age, and degree of a glomerular filtration rate (GFR) reduction. Along with iron exchange indicators, the time course of changes in serum Klotho levels were examined in all the 64 patients during screening and one year after the end of the study. For correction of anemia, 32 patients with this condition (Groups 1A and 1B) took short-acting epoetin (hypodermic recormon 2,000 IU thrice per week + iron (intravenous venofer 5 ml of 100 mg once per week)) under control of hemoglobin levels and serum transferrin iron and ferritin saturation. After achieving the target hemoglobin level of 110-120 g/l, for its keeping, all the patients received, instead of short-acting epoetin, long-acting hypodermic darbepoetin-α 1.5 µg once every 2 months and intravenous iron saccharate 100 mg once every 2 weeks. Among the 32 anemic patients in Group 1, 20 (63%) (Group 1 A) could achieve the target hemoglobin level (110--120 g/l) and maintain it within this range, by performing therapy with epoitin-β + iron saccharate; anemia (the hemoglobin level of <110 g/l) persisted in 12 (37%) patients (Group 1B) despite the fact that epoetin and iron saccharate had been administered. Group 1A was noted to have an increase in α-Klotho concentrations by an average of 100±11.6-pg/ml as compared to Group 1B (by only 72±4.2 pg/ml). At the same time, the α-Klotho levels in the control group by the end of the follow-up decreased by an average of 210±12.9 pg/ml as compared to the prescreening value. There was a direct correlation between hemoglobin and serum ferritin concentrations and iron ferritin saturation percentage and α-Klotho levels. It was ascertained that the hemoglobin concentration of ≥110 g/l with a sensitivity of 89% and a specificity of 75% could predict higher serum α-Klotho levels in CKD. The same patients were found to have an inverse relationship between the serum level of α-Klotho and the risk of cardiovascular events. The serum level of the protein Klotho is not only a marker for the severity of CKD and its complications (anemia, left ventricular hypertrophy, and heart failure), but also a pathogenetic factor of CKD progression. Anemia correction with erythropoiesis stimulants has been shown to enhance the renal and extrarenal production of α-Klotho.

Soluble Serum αKlotho Is a Potential Predictive Marker of Disease Progression in Clear Cell Renal Cell Carcinoma.

Renal cell carcinoma (RCC) accounts for approximately 3% of adult malignancies, and clear cell RCC (ccRCC), that has a high metastatic index and high relapse rate, is the most common histological subtype. The identification of new biomarkers in ccRCC is fundamental for stratifying patients into prognostic risk groups and to guide therapy. The renoprotective antiaging gene, αKlotho, has recently been found to work as a tumor suppressor in different human cancers. Here, we evaluated αKlotho expression in tissue and serum of ccRCC patients and correlated it with disease progression. Tissue αKlotho expression was studied by quantitative RT-PCR and immunohistochemistry. In addition, soluble serum αKlotho levels were preoperatively measured in 160 patients who underwent nephrectomy for RCC with ELISA. Estimates of cancer-specific (CSS) and progression-free survival (PFS) were calculated according to the Kaplan–Meier method. Multivariate analysis was performed to identify the most significant variables for predicting CSS and PFS. αKlotho protein levels were significantly decreased in RCC tissues compared with normal tissues (P < 0.01) and the more advanced the disease, the more evident the down-regulation. This trend was also observed in serum samples. Statistically significant differences resulted between serum αKlotho levels and tumor size (P = 0.003), Fuhrman grade (P = 0.007), and clinical stage (P = 0.0004). CSS and PFS were significantly shorter in patients with lower levels of αKlotho (P < 0.0001 and P = 0.0004, respectively). At multivariate analysis low serum levels of αKlotho were independent adverse prognostic factors for CSS (HR = 2.11; P = 0.03) and PFS (HR = 2.18; P = 0.03).These results indicate that a decreased αKlotho expression is correlated with RCC progression, and suggest a key role of declining αKlotho in the onset of cancer metastasis.

Serum α-klotho levels during the follicular phase of preimplantation are associated with aging or quality of human oocytes and clinical pregnancy rates

Serum α-klotho levels during the follicular phase of preimplantation are associated with aging or quality of human oocytes and clinical pregnancy rates

Circulating α-Klotho Levels in CKD and Relationship to Progression

α-Klotho is reported to have protective effects against kidney injury, and its renal expression is decreased in many experimental models of kidney disease. However, circulating α-klotho levels in human chronic kidney disease (CKD) and the relationship to progression are unknown. Post hoc analysis of a prospective cohort study. 243 of 301 participants from a CKD cohort at our institution between January 2006 and December 2011 were eligible for the study. Baseline α-klotho levels. Primary outcome was the composite of doubling of baseline serum creatinine concentration, end-stage renal disease, or death. End-stage renal disease was defined as onset of treatment by renal replacement therapy. Serum α-klotho and fibroblast growth factor 23 (FGF-23) were measured using enzyme-linked immunosorbent assay. Lower serum α-klotho levels were associated with more severe CKD stage in the cross-sectional analysis of the baseline data (P for trend < 0.001). In the adjusted multivariable linear regression model, log(α-klotho) was associated independently with estimated glomerular filtration rate (β = 0.154; P = 0.001). Cox regression analysis showed that baseline α-klotho level independently predicted the composite outcome after adjustment for age, diabetes, blood pressure, estimated glomerular filtration rate, proteinuria, parathyroid hormone level, and FGF-23 level (HR per 10-pg/mL increase, 0.96; 95% CI, 0.94-0.98; P < 0.001). When patients were categorized into 2 groups according to baseline median α-klotho value, 43 (35.2%) patients with α-klotho levels ≤396.3 pg/mL reached the primary composite outcome compared with 19 (15.7%) with α-klotho levels >396.3 pg/mL (HR, 2.03; 95% CI, 1.07-3.85; P = 0.03). Uncontrolled dietary phosphorus intake and use of frozen samples. This observational study showed that low circulating α-klotho levels were associated with adverse kidney disease outcome, suggesting that α-klotho is a novel biomarker for CKD progression. More data from larger prospective longitudinal studies are required to validate our findings.