Effects of L-Carnitine on Mineral Metabolism in the Multicentre, Randomized, Double Blind, Placebo-Controlled CARNIDIAL Trial

BACKGROUND

The use of L-carnitine has been proposed in haemodialysis (HD) when deficiency is present to improve anaemia resistant to erythropoietin stimulating agent, intradialytic hypotension or cardiac failure. We tested the effects of L-carnitine supplementation on parameters of chronic kidney disease-mineral bone disorder.

METHODS

CARNIDIAL was a randomized, double-blinded trial having included 92 incident HD subjects for a 1-year period to receive L-carnitine versus placebo. Determinant factors of C-terminal fibroblast growth factor 23 (cFGF23) and intact FGF23 were studied including Klotho level. The L-carnitine effect on mineral metabolism was analyzed between groups by mixed linear models for repeated measurements.

RESULTS

Klotho was below the lower limit of quantification (LLOQ) in 55% of the 163 samples. In multivariate analysis, cFGF23 was positively correlated with calcium and phosphate and was higher in subjects having Klotho > LLOQ. No correlation existed between Klotho and phosphate and phosphate was even higher in subjects having Klotho > LLOQ (p < 0.001). Both forms of FGF23 were not related to iron markers nor to IV iron dose. No L-carnitine effect was detected on parathyroid hormone (PTH) or FGF23 during the study period where PTH slightly decreased over time, whereas FGF23 increased. But calcium and phosphate increased more in the L-carnitine group.

CONCLUSION

L-carnitine supplementation increased calcium and phosphate plasma concentrations with no detected downregulation effect on PTH and FGF23. (Clinical Trial 00322322, May 5, 2006).

Association Between Plasma Concentration of Klotho Protein, Osteocalcin, Leptin, Adiponectin, and Bone Mineral Density in Patients with Chronic Kidney Disease

Patients with early-stage chronic kidney disease (CKD) are susceptible to changes in metabolic processes. Partial loss of kidney function leads to homoeostatic disturbances in bone and fatty tissue. The aim of this study was to investigate the association between plasma concentrations of Klotho protein, FGF23, leptin, adiponectin, osteocalcin, and bone mineral density (BMD) in patients with CKD in the pre-dialysis period. The study involved 52 patients with CKD and 23 patients with no kidney disease. In both groups, BMD, body mass index and serum or plasma concentrations of lipids, glucose, creatinine, calcium, phosphorus, parathormone, leptin, adiponectin, osteocalcin, Klotho, and FGF23 were measured. The group with CKD had statistically significant higher concentrations of leptin (p<0.001), parathormone (p<0.001), and osteocalcin (p<0.001) in comparison with the control group. Patients with CKD also had statistically significant lower BMD in the femoral neck in comparison with the control group. Osteocalcin correlated negatively with BMD. The results of our study suggest that elevated osteocalcin is the most sensitive marker of decreased bone mass in patients with CKD. Osteocalcin correlated negatively with BMD and GFR. The loss of bone mass in CKD patients was greatest in the femoral neck.

Clinical implication of alterations in serum Klotho levels in patients with type 2 diabetes mellitus and its associated complications

AIM

To investigate the clinical significance of serum α-Klotho and β-Klotho levels in patients with type 2 diabetes mellitus (T2DM) and its associated complications.

METHODS

Serum α-Klotho and β-Klotho levels were measured using an ELISA kit in 817 individuals, including 127 with T2DM, 106 with diabetic nephropathy, 99 with diabetic retinopathy, 108 with diabetic neuropathy, 102 with diabetic foot disease, 135 with T2DM and more than one complication and 140 healthy controls.

RESULTS

Both α-Klotho and β-Klotho levels were significantly decreased in the T2DM group and the groups with associated complications compared with the levels in control group. The differences between the T2DM group and the T2DM with complications groups were not significant, except between the diabetic nephropathy group and the other diabetic complications groups. In addition, α-Klotho and β-Klotho levels were negatively correlated with serum fructosamine and HbA1c but were not associated with serum glucose in the model including all participants. Moreover, decreases in α-Klotho and β-Klotho levels in the high glucose-exposed cell culture model, which was dependent on glucose exposure time, were confirmed.

CONCLUSIONS

Levels of α-Klotho and β-Klotho were downregulated in patients in the T2DM and complications groups. Our findings indicate that serum Klotho levels were associated with the development of T2DM, and long-term control of blood glucose will be beneficial in ameliorating changes to α-Klotho and β-Klotho levels in patients with T2DM and complications.

FGF23-klotho axis, bone fractures, and arterial stiffness in dialysis: a case-control study

We performed a case-control study on 130 age- and sex-matched hemodialysis patients. In multivariate analysis, we observed that FGF23 levels were associated with fracture incidence and that soluble α-klotho levels were associated with the aortic-brachial arterial stiffness ratio.

INTRODUCTION

New bone markers such as sclerostin, Dickkopf-related protein 1 (DKK1), fibroblast growth factor-23 (FGF23), and α-klotho have been identified as potential key players in bone and vascular abnormalities of chronic kidney disease. Therefore, we aimed to assess whether these markers are associated with fractures, bone metabolism, and vascular stiffness in dialysis patients.

METHODS

In a prospective hemodialysis cohort, where plasma samples and vascular assessment were performed at baseline, we matched patients who experienced a fracture during follow-up with sex- and age-matched non-fractured patients on a 1:4 ratio. Sclerostin, DKK1, α-klotho, FGF23, and markers of bone formation (alkaline phosphatase and procollagen type 1-N terminal propeptide [P1NP]) and bone resorption (tartrate-resistant acid phosphatase 5b [TRAP5b]) were measured in baseline plasma samples. Aortic-brachial pulse wave velocity ratio, a blood pressure independent measure of arterial stiffness, was used to assess vascular stiffness at baseline.

RESULTS

We included 130 hemodialysis patients (26 fractured, 104 non-fractured) with a median follow-up of 42 months and a median age of 72 years. In multivariate Cox regression models, high FGF23 levels were associated with increased fracture incidence (adjusted HR = 2.97; 95% CI 1.18, 7.43). α-Klotho levels were associated with bone formation but not resorption markers. In both univariate and multivariable adjusted models, α-klotho levels were inversely associated with the aortic-brachial pulse wave velocity ratio (β = - 0.070; 95% CI - 0.133, - 0.006).

CONCLUSIONS

These results suggest a role for FGF23/klotho axis on bone and vascular metabolism in dialysis populations.

Effect of Sevelamer on Serum Levels of Klotho and Soluble Tumor Necrosis Factor-like Weak Inducer of Apoptosis in Rats With Adenine-induced Chronic Kidney Disease

INTRODUCTION

Nontraditional risk factors for cardiovascular disease (CVD), including mineral disorder, high fibroblast growth factor 23 (FGF23), low klotho, and low soluble TWEAK could predict the incipient risk of CVD in chronic kidney disease (CKD). The present study evaluates the effect of sevelamer on soluble tumor necrosis factor-like weak inducer of apoptosis (TWEAK), and klotho levels in adenine-induced CKD rats.

METHODS AND MATERIALS

Normal control rats without sevelamer were compared with 3 groups of adenine-induced CKD rats, including CKD rats without sevelamer, CKD rats treated with 3% sevelamer, and rats receiving adenine and 3% sevelamer concurrently. After 4 weeks of sevelamer treatment, serum levels of klotho and soluble TWEAK were measured, along with biochemical parameters related to kidney function.

RESULTS

Sevelamer significantly reduced serum levels of phosphate and increased serum levels of klotho and soluble TWEAK. Decreased levels of phosphate were negatively correlated with elevated levels of klotho and soluble TWEAK (r = -0.70, P = .003; r = -0.58, P = .02; respectively) in serum.

CONCLUSIONS

Sevelamer successfully reduced serum levels of phosphate, and meanwhile, it led to an elevation in serum levels of klotho and soluble TWEAK in rat models of CKD.

Optimization of the method for α-l-fucosidase, β-d-galactosidase and β-d-glucuronidase determination in serum from hemolyzed blood

PURPOSE

Adaptation of the colorimetric method for the determination of β-d-galactosidase, β-d-glucuronidase and α-l-fucosidase activities in serums from hemolyzed blood, the material currently being discarded.

MATERIALS AND METHODS

The materials included serums from hemolyzed and non-hemolyzed blood, obtained from 26 healthy volunteers. The adaptation of the method involved precipitation of the proteins with trichloroacetic acid after incubating serums with substrates, but before determining the products of enzymatic reactions.

RESULTS

In serums from hemolyzed and non-hemolyzed blood of the same persons, we found high correlations among the results obtained using hemolyzed blood (with adapted) and non-hemolyzed blood (with non-adapted) methods.

CONCLUSION

We are able to determine the β-d-galactosidase, β-d-glucuronidase and α-l-fucosidase activities in serums from hemolyzed blood (with adapted) and non-hemolyzed blood (with non-adapted) methods, with the same accuracy and precision.

Analysis of endocrine hormone metabolism level in a Chinese patient with mucopolysaccharidosis IVA: A case report

RATIONALE

Mucopolysaccharidosis IVA (Morquio A) is a catabolic mucopolysaccharide disorder caused by galactose-6-sulfate sulfatase deficiency. It is an autosomal recessive inherited disease. Previous reports on clinical characteristics of Morquio A mainly focused on growth retardation, skeletal deformities, and organ damage in children and adolescents, while the effects of mucopolysaccharide metabolism disorders on endocrine hormone metabolism level have not been reported. Herein, we reported the endocrine hormone metabolism in a case diagnosed as Morquio A.

PATIENT CONCERNS

The patient was a 17-year-old girl with growth retardation, hearing loss, and severe skeletal dysplasia(scoliosis and chicken breast), and was evaluated to have normal nervous system function and intelligence by physicians.

DIAGNOSES

She was diagnosed as Morquio A based on gene analysis, mucopolysaccharide-related enzymes and her clinical features.

INTERVENTIONS

The patient didn't accepted the enzyme replacement therapy.

OUTCOMES

She had a homozygous mutation of the GALNS gene. The b-glucuronidase content in the blood was reduced. The serum sodium, serum adrenocorticotropic hormone, and cortisol rhythms (8 AM) were decreased. The levels of PRA(plasma renin activity) , PAII(plasma angiotensin II), and PALD(plasma aldosterone) were elevated. Bone mineral density suggests osteoporosis. There were no abnormalities in bone metabolism indicators, growth hormone, thyroid hormone, and sex hormones. In summary, the level of endocrine hormones in patients with mucopolysaccharidosis IV changes.

LESSONS

This is the report on endocrine hormone level in a patient with mucopolysaccharidosis IV in China. Due to the disease may have relatively incomplete adrenal function, which provides a basis for future understanding and diagnosis of this disease.

Impact of cigarette smoking cessation on plasma α-klotho levels

Smoking cessation reduces the risk of cardiovascular disease and improves clinical outcomes. We studied the effect of smoking cessation on plasma levels of α-klotho, which is an antiaging protein. We treated 28 smokers (male:female = 23:5, 46 ± 12 years) with varenicline (n = 14) or a transdermal nicotine patch (n = 14) as part of a 12-week smoking cessation program (the VN-SEESAW Study). Pulse rate, blood pressure, plasma levels of α-klotho, fibroblast growth factor (FGF)-19, FGF-21, hemoglobin (Hb), and expiratory carbon monoxide (CO) concentration were measured before and after the antismoking intervention. Smoking cessation significantly decreased pulse rate, α-klotho, Hb, and CO concentration, but not FGF-19 or FGF-21 in all subjects. On the contrary, body mass index significantly increased after the intervention. Changes in α-klotho levels (values at week 12 - values at week 0) were negatively associated with α-klotho levels at week 0 and positively associated with changes in Hb levels. In addition, the successful smoking cessation group (n = 21) showed significant reductions in pulse rate, systolic blood pressure, α-klotho, Hb, and CO concentration. In conclusion, smoking cessation significantly decreased serum levels of the antiaging molecule α-klotho. Our results are consistent with a previous report that an increase in α-klotho might be a compensatory response to smoking stress.

Circulating Klotho levels can predict long-term macrovascular outcomes in type 2 diabetic patients

BACKGROUND AND AIMS

Type 2 diabetes is a global health problem that is associated with a wide variety of vascular complications and associated morbidity and mortality. Klotho is an enzyme and transmembrane protein, and increasing evidence suggests that Klotho may contribute to reduced oxidative stress, improved endothelial function, and vasoprotection. To date, the physiological role of Klotho in vascular complications associated with diabetes is unclear.

METHODS

We prospectively recruited 252 patients with type 2 diabetes, who visited an outpatient clinic at our hospital between 2009 and 2011. Patients in the top and bottom tertiles of circulating Klotho levels were enrolled for analysis.

RESULTS

Of the 168 patients enrolled, 45.8% were male, the mean age was 57.2 years, and the average duration of diabetes was 7.58 years. In multiple regression analysis, a high Klotho level was associated with a reduced risk of developing coronary artery disease and cerebrovascular accidents. Klotho level was also an independent predictor for the development of macroangiopathies within the 7-year study period.

CONCLUSIONS

Our results suggest that circulating Klotho level is a predictor of long-term macrovascular outcomes in patients with type 2 diabetes.

Circulating α-Klotho is Related to Plasma Aldosterone and Its Follow-Up Change Predicts CKD Progression

BACKGROUND/AIMS

We aimed to determine if soluble α-klotho level was an indicator of chronic kidney disease (CKD) progression and whether α-klotho interacted with aldosterone during the course of further renal damage.

METHODS

112 adults with stages 1-5 CKD were enrolled into our cohort study. All of the patients were followed up for 6 years (from January 2010 to December 2015). Serum soluble α-klotho and aldosterone were measured at baseline and at 1.5-years follow-up. The primary outcome was the initiation of renal replacement therapy (RRT) and the secondary outcome was the occurrence of cardio-cerebrovascular events. Long-term progression to RRT and cardio-cerebrovascular events in patients was analyzed with a risk-adjusted Cox proportional hazards regression model. Adjustment included age, gender, eGFR, mean arterial pressure, 24-h protein excretion and the change in α-klotho level from baseline at 1.5-years follow-up.

RESULTS

Baseline circulating α-klotho levels were positively associated with baseline estimated glomerular filtration rate (eGFR; r = 0.224, p = 0.017), but not age, calcium, phosphate, or parathyroid hormone levels. The change in α-klotho level from baseline at 1.5-years follow-up (p = 0.002) was independently associated with renal replace treatment (RRT) initiation after adjustment for age, gender, eGFR, mean arterial pressure, and 24-h protein excretion in Cox regression analysis. Aldosterone levels were positively associated with CKD stage, and were inversely correlated with circulating α-klotho levels.

CONCLUSION

The change in concentration of soluble α-klotho during the 1.5-years follow-up was an indicator of CKD progression. Renal damage associated with a reduction of α-klotho may involve the upregulation of plasma aldosterone. Future studies are needed to validate our findings, and to investigate the underlying mechanism by which α-klotho and aldosterone may cause renal damage.

Reduced Levels of Anti-Ageing Hormone Klotho Predict Renal Function Decline in Type 2 Diabetes

CONTEXT AND OBJECTIVE

Soluble Klotho (sKlotho) is a circulating hormone with cardiovascular-renal protective effects. Whether sKlotho predicts estimated glomerular filtration rate (eGFR) decline in patients with type 2 diabetes mellitus (T2DM) with relatively preserved renal function is unknown.

DESIGN, SETTING, PARTICIPANTS, AND MEASUREMENTS

Single-center observational follow-up study of 101 patients with T2DM and eGFR >45 mL/min [91% on renin angiotensin system (RAS) blockade] followed for a median of 9 years (range, 2 to 13 years).

MAIN OUTCOME

Primary outcome was a >50% decline in eGFR. sKlotho, serum phosphorus, serum calcium, and fibroblast growth factor-23 levels were measured from stored samples collected at baseline. Patients were followed up with standardized clinical and biochemical measurements.

RESULTS

Patients with residual microalbuminuria (MA) despite RAS blockade (n = 53) had significantly lower levels of sKlotho [median, 184.7 pg/mL; interquartile range (IQR), 130.5 to 271.8 pg/mL) compared with patients without MA (n = 39; median, 235.2 pg/mL; IQR, 172.0 to 289.4 pg/mL; P = 0.03). Of the cohort, 21% reached the primary outcome. In a competing risk analysis, a 10% higher sKlotho level reduced the incidence of the primary outcome by 12% (hazard ratio, 0.27; 95% confidence interval, 0.15 to 0.52; P < 0.001] independent of traditional risk factors. Patients with sKlotho below the median of 204.4 pg/mL had nearly a fourfold higher cumulative incidence of the primary outcome compared with those above the median (24% vs 6.2%; P = 0.01).

CONCLUSIONS

In patients with T2DM with relatively preserved eGFR, reduced levels of sKlotho predict renal function decline independent of traditional risk markers. sKlotho is a biomarker of renal dysfunction and a potential treatment target for renoprotection in T2DM.

Klotho and activin A in kidney injury: plasma Klotho is maintained in unilateral obstruction despite no upregulation of Klotho biosynthesis in the contralateral kidney

In a new paradigm of etiology related to chronic kidney disease-mineral and bone disorder (CKD-MBD), kidney injury may cause induction of factors in the injured kidney that are released into the circulation and thereby initiate and maintain renal fibrosis and CKD-MBD. Klotho is believed to ameliorate renal fibrosis and CKD-MBD, while activin A might have detrimental effects. The unilateral ureter obstruction (UUO) model is used here to examine this concept by investigating early changes related to renal fibrosis in the obstructed kidney, untouched contralateral kidney, and vasculature which might be affected by secreted factors from the obstructed kidney, and comparing with unilateral nephrectomized controls (UNX). Obstructed kidneys showed early Klotho gene and protein depletion, whereas plasma Klotho increased in both UUO and UNX rats, indicating an altered metabolism of Klotho. Contralateral kidneys had no compensatory upregulation of Klotho and maintained normal expression of the examined fibrosis-related genes, as did remnant UNX kidneys. UUO caused upregulation of transforming growth factor-β and induction of periostin and activin A in obstructed kidneys without changes in the contralateral kidneys. Plasma activin A doubled in UUO rats after 10 days while no changes were seen in UNX rats, suggesting secretion of activin A from the obstructed kidney with potentially systemic effects on CKD-MBD. As such, increased aortic sclerostin was observed in UUO rats compared with UNX and normal controls. The present results are in line with the new paradigm and show very early vascular effects of unilateral kidney fibrosis, supporting the existence of a new kidney-vasculature axis.

Growth Hormone (GH) and Cardiovascular System

This review describes the positive effects of growth hormone (GH) on the cardiovascular system. We analyze why the vascular endothelium is a real internal secretion gland, whose inflammation is the first step for developing atherosclerosis, as well as the mechanisms by which GH acts on vessels improving oxidative stress imbalance and endothelial dysfunction. We also report how GH acts on coronary arterial disease and heart failure, and on peripheral arterial disease, inducing a neovascularization process that finally increases flow in ischemic tissues. We include some preliminary data from a trial in which GH or placebo is given to elderly people suffering from critical limb ischemia, showing some of the benefits of the hormone on plasma markers of inflammation, and the safety of GH administration during short periods of time, even in diabetic patients. We also analyze how Klotho is strongly related to GH, inducing, after being released from the damaged vascular endothelium, the pituitary secretion of GH, most likely to repair the injury in the ischemic tissues. We also show how GH can help during wound healing by increasing the blood flow and some neurotrophic and growth factors. In summary, we postulate that short-term GH administration could be useful to treat cardiovascular diseases.

Randomized Clinical Trial of Sevelamer Carbonate on Serum Klotho and Fibroblast Growth Factor 23 in CKD

BACKGROUND AND OBJECTIVES

Epidemiologic studies suggest that higher serum phosphaturic hormone fibroblast growth factor 23 levels are associated with increase morbidity and mortality. The aim of the FGF23 Reduction Efficacy of a New Phosphate Binder in CKD Trial was to evaluate the effect of sevelamer carbonate on serum C-terminal fibroblast growth factor 23 levels in normophosphatemic patients with CKD stage 3b/4.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Patients with CKD, eGFR between 45 and 15 ml/min per 1.73 m2, fasting serum phosphate concentration >3.1 mg/dl, and serum C-terminal fibroblast growth factor 23 >80 relative units/ml were included in our double-blind, placebo-controlled, randomized multicenter study. All patients received 100,000 IU cholecalciferol at time of randomization. Participants received either placebo or sevelamer carbonate 4.8 g daily during a 12-week period. Biologic parameters, including serum C-terminal fibroblast growth factor 23, intact fibroblast growth factor 23, and α-klotho, were evaluated at baseline and 12 weeks after inclusion.

RESULTS

Of 96 screened patients, 78 (mean±SD age: 63±13 years old; 70% men; mean eGFR: 27±9 ml/min per 1.73 m2) met the inclusion criteria. At baseline, mean eGFR was 27±9 ml/min per 1.73 m2, mean serum phosphate level was 3.8±0.5 mg/dl, and median (interquartile range) serum C-terminal fibroblast growth factor 23 level was 157 (120-241) relative units/ml. After 12 weeks of treatment, urinary phosphate-to-creatinine ratio fell significantly in the sevelamer group. The sevelamer and placebo groups did not differ significantly in terms of median change in serum C-terminal fibroblast growth factor 23 levels: the median (interquartile range) change was 38 (-13-114) relative units/ml in the placebo group and 37 (-1-101) relative units/ml in the sevelamer group (P=0.77). There was no significant difference in serum intact fibroblast growth factor 23, α-klotho, or phosphate levels changes between the two groups. Serum total and LDL cholesterol levels fell significantly in the sevelamer group.

CONCLUSIONS

In our double-blind, placebo-controlled, randomized study performed in normophosphatemic patients with CKD, a 12-week course of sevelamer carbonate significantly reduced phosphaturia without changing serum phosphorus but did not significantly modify serum C-terminal fibroblast growth factor 23 and intact fibroblast growth factor 23 or α-klotho levels.

[Correlations of FGF23 and Klotho with cardiovascular injury in chronic kidney disease patients]

To analyze the levels of serum calcium, phosphate, fibroblast growth factor 23 (FGF23), and Klotho proteins in patients with chronic kidney disease (CKD), and to investigate the correlations of FGF23 and Klotho proteins with cardiac complicates in patients with chronic kidney disease-mineral and bone disorder (CKD-MBD).
 Methods: A total of 180 CKD-MBD patients were enrolled for this study. Among them, 60 patients underwent regular hemodialysis, 60 patients did not undergo renal replacement therapy and 60 patients were diagnosed as second hyperparathyroidism (SHPT). Thirty age and gender-matched health volunteers served as controls. Serum samples were collected and tested, and the demographical, clinical and biochemical data were all recorded. FGF23 and Klotho levels in serum samples were analyzed by enzyme-linked immunosorbent assay. Data of echocardiography and plain abdominal X rays were collected as well. The influential factors for cardiovascular injury, the relationship between biochemical indexes and ectopic calcification, and the correlations of FGF23 and Klotho with cardiac complicates were analyzed
 Results: Patients, who kept hemodialysis, especially those with SHPT, exhibited an increase in serum FGF23 level while a decrease in serum Klotho protein levels (P<0.01). Patients with higher levels of serum FGF23 were more likely to have ectopic calcification (OR=4.667), while patients with lower levels of serum Klotho had high risks to get myocardial hypertrophy (OR=3.496). Receiver operator characteristic (ROC) curve analysis showed that the area under the curve (AUC) for FGF23 was 0.778 (P<0.01) while for Klotho was 0.715 (P<0.01).
 Conclusion: Patients, who kept hemodialysis, especially those with SHPT, have a significant increase in serum FGF23 protein levels and a significant decrease in serum Klotho protein levels. Serum FGF23 and Klotho protein levels are closely correlated with left ventricular enlargement and hypertrophy. Serum FGF23 and Klotho protein are risk factors for heart.

Circulating Klotho Associates With Cardiovascular Morbidity and Mortality During Hemodialysis

BACKGROUND

Klotho gene was identified as an aging suppressor. In animals, klotho overexpression extends life span, and defective klotho results in rapid aging and early death. The kidney is the main contributor to circulating klotho levels, and, during chronic kidney disease, renal klotho gene expression is drastically reduced in animals and humans as well.

OBJECTIVE

We aimed to determine the consequences of a serum klotho (seKL) defect on cardiovascular morbidity and mortality during chronic dialysis.

DESIGN

The ARNOGENE study was designed to prospectively follow a cohort of hemodialysis patients for 2 years without specific intervention. A total of 769 patients was recruited and followed from the end of 2008 until January 2011. A total of 238 patients was analyzed due to a technical sample conservation issue with other samples.

RESULTS

The median seKL was markedly reduced, 360.4 ng/L (interquartile range 176.5) as compared with nondialysis chronic kidney disease patients or healthy volunteers. Patients with a seKL above the first quartile (≥280 ng/L) had a significantly reduced occurrence of outcome combining cardiovascular events and cardiovascular death [odds ratio (OR) = 0.39; 0.19 to 0.78, P = 0.008] compared with patient with klotho <280 ng/L. This effect persisted (OR = 0.86; 0.76 to 0.99, P = 0.03) after adjustment on age, sex, diabetes, cardiac insufficiency, dialysis vintage, and serum hemoglobin, albumin, fibroblast growth factor-23, phosphate, and calcium.

CONCLUSIONS

These results suggest that, during chronic hemodialysis, conservation of seKL >280 ng/L is associated with a better 2-year cardiovascular protection. Thus, a preserved klotho function supports cardiovascular protection and may represent a prognostic tool and therapeutic target for cardiovascular disease.

Association between Soluble Klotho and Change in Kidney Function: The Health Aging and Body Composition Study

CKD appears to be a condition of soluble klotho deficiency. Despite known associations between low soluble klotho levels and conditions that promote kidney damage, such as oxidative stress and fibrosis, little information exists regarding the longitudinal association between soluble klotho levels and change in kidney function. We assayed serum soluble α-klotho in 2496 participants within the Health Aging and Body Composition study, a cohort of older adults. The associations between soluble klotho levels and decline in kidney function (relative decline: eGFR decline ≥30%; absolute decline: eGFR decline >3 ml/min per year) and incident CKD (incident eGFR <60 ml/min per 1.73 m2 and >1 ml/min per year decline) were evaluated. We adjusted models for demographics, baseline eGFR, urine albumin-to-creatinine ratio, comorbidity, and measures of mineral metabolism. Among participants, the mean (SD) age was 75 (3) years, 52% were women, and 38% were black. Median (25th, 75th percentiles) klotho level was 630 (477, 817) pg/ml. In fully adjusted models, each two-fold higher level of klotho associated with lower odds of decline in kidney function (odds ratio, 0.78 [95% confidence interval, 0.66 to 0.93] for 30% decline in eGFR, and 0.85 [95% confidence interval, 0.73 to 0.98] for >3 ml/min per year decline in eGFR), but not of incident CKD (incident rate ratio, 0.90 [95% confidence interval, 0.78 to 1.04]). Overall, a higher soluble klotho level independently associated with a lower risk of decline in kidney function. Future studies should attempt to replicate these results in other cohorts and evaluate the underlying mechanism.

Perturbations of the anti-ageing hormone Klotho in patients with type 1 diabetes and microalbuminuria

AIMS/HYPOTHESIS

Patients with type 1 diabetes and microalbuminuria are at high risk of cardiovascular disease (CVD) and end-stage renal disease. Soluble Klotho is an anti-ageing circulating hormone involved in phosphate metabolism and vascular homeostasis through protective effects on the endothelium and antioxidant actions. The role of soluble Klotho in patients with type 1 diabetes and microalbuminuria is unknown.

METHODS

In a cross-sectional single-centre study we evaluated the levels of circulating serum soluble Klotho in 33 participants with type 1 diabetes and a history of microalbuminuria (receiving renin-angiotensin system [RAS] inhibitors) and 45 participants with type 1 diabetes without a history of microalbuminuria (not receiving RAS or other antihypertensive drugs). All participants had an eGFR >45 ml/min, duration of diabetes >20 years and no history of CVD. Serum soluble Klotho levels were measured by a validated immunoassay.

RESULTS

Participants with microalbuminuria had significantly lower levels of serum Klotho compared with those without microalbuminuria (median [interquartile range], 659.3 [525.3, 827.6] vs 787.7 [629.5, 1007]; p = 0.023). This difference persisted after adjustment for variables including age and eGFR. In a subgroup of 30 individuals with and without microalbuminuria, other markers of phosphate balance were not significantly different.

CONCLUSIONS/INTERPRETATION

In individuals with type 1 diabetes, microalbuminuria is associated with soluble Klotho deficiency. Further studies are required to determine whether soluble Klotho is causally related to the development of cardio-renal disease in type 1 diabetes.

Serum klotho protein levels and their correlations with the progression of type 2 diabetes mellitus

AIM

To investigate the associations of serum α-Klotho and β-Klotho levels with type 2 diabetes mellitus (T2DM) progression.

METHODS

We evaluated 106 healthy controls and 261 cases of T2DM with or without diabetic complications (range: 45-84years). Serum α-Klotho and β-Klotho levels were analyzed using enzyme-linked immunosorbent assays.

RESULTS

Compared to the healthy controls, α-Klotho and β-Klotho levels were significantly lower among patients with T2DM and with or without diabetic complications (P<0.05). Furthermore, α-Klotho levels were lower in the microalbuminuric and macroalbuminuric groups, compared to the normoalbuminuric group. However, β-Klotho levels were only lower in the macroalbuminuric group (P<0.05). Multiple linear regression analyses revealed that α-Klotho and β-Klotho levels were positively correlated with the creatinine clearance rate, and negatively correlated with the urinary albumin to creatinine ratio and randomly sampled serum levels of creatinine, blood urea nitrogen, and blood glucose. Moreover, α-Klotho and β-Klotho levels were positively correlated among patients with T2DM (r=0.693, P<0.001).

CONCLUSIONS

Serum levels of α-Klotho and β-Klotho are down-regulated in patients with T2DM. Thus, these proteins may participate in the pathological mechanism of diabetes, and the positive correlation of α-Klotho and β-Klotho levels indicates that they might have similar mechanisms in T2DM.

Relationship of Serum Klotho Level With ACE Gene Polymorphism in Stable Kidney Allograft Recipients

INTRODUCTION

The kidney is the main source of serum Klotho production. Immunosuppressive agents could affect the kidney in this regard. The effect of the ACE gene polymorphism on Klotho production is a less studied area. This study aimed to assess serum Klotho and ACE gene in a group of stable kidney transplant recipients.

MATERIALS AND METHODS

In a cross-sectional study, 30 kidney transplant recipients with stable allograft function and 27 healthy young individuals were assessed for their serum Klotho levels. The ACE gene polymorphisms were studied in both groups.

RESULTS

Klotho level was higher in kidney transplant recipients than the controls, but the difference was not significant (2.76 ± 2.41 ng/mL versus 2.01 ± 1.41 ng/mL, respectively). In both groups, serum Klotho level was higher in those with the I>I polymorphism, the men, those with higher glomerular filtration rate, and younger individuals, but the differences did not reach a significant level. Higher body mass index was significantly associated with lower serum Klotho level in both groups.

CONCLUSIONS

Klotho level after kidney transplantation meets the range in healthy individuals, and it is not affected by the ACE gene polymorphism.

Klotho and fibroblast growth factor 23 in cerebrospinal fluid in children

The fibroblast growth factor (FGF) 23/Klotho axis is a principal regulator of phosphate hemostasis and vitamin D metabolism, but limited data is available on its role in the central nervous system. Here, we investigate soluble α-Klotho (sKlotho) and C-terminal as well as intact FGF23 in cerebrospinal fluid (CSF) and plasma and their relationship to mineral metabolism parameters in humans. In 39 children aged 0.3-16.8 years undergoing lumbar puncture for the exclusion of inflammatory neurological disease, sKlotho and FGF23 were investigated by Western blot analysis, followed by ELISA quantification in CSF and plasma. The percentage of intrathecal synthesis of both proteins was calculated by measuring both the expected and observed CSF/plasma ratios of sKlotho and FGF23. The secreted (KL1) and cleaved (KL1+KL2) isoforms of sKlotho, and FGF23 were clearly detected in CSF in all subjects, although protein levels were lower compared to those of plasma samples (each p < 0.01). The intrathecal percentage of CSF sKlotho and FGF23 synthesis amounted to 98 and 99 %, respectively. CSF sKlotho levels were higher in boys than in girls (p < 0.01), and correlated positively with plasma C-terminal FGF23 concentrations (p < 0.05) and standardized height (p < 0.01). Importantly, there were no significant correlations between plasma and CSF levels of sKlotho or FGF23. Plasma sKlotho as well as C-terminal and intact FGF23, respectively, were associated with parameters of mineral metabolism These results provide evidence that cleaved and secreted sKlotho and FGF23 are present in CSF, mainly derived from brain and affected by sex, height, and mineral metabolism parameters in children. Nevertheless, the absence of significant associations between plasma and CSF levels of Klotho and FGF23, respectively, suggest that the regulation of Klotho and FGF23 may be different between organs secreting these hormones into blood and CSF.

Adiponectin alters renal calcium and phosphate excretion through regulation of klotho expression

The kidney controls systemic calcium and phosphate levels and disturbances of its control mechanisms can lead to a variety of diseases. The insulin-sensitizing adipokine adiponectin is renoprotective and accelerates functional recovery following renal injury. However, unlike other adipokines, adiponectin is reduced in obesity. High adiponectin levels are also correlated with bone loss, suggestive of an additional action in mineral metabolism. Using knockout, wild-type, and adiponectin-overexpressing transgenic mice, we sought to identify the mechanistic basis for adiponectin's ability to regulate calcium and phosphate balance at the level of the kidney. Adiponectin knockout mice exhibited lower serum calcium, lower urinary calcium excretion, and markedly lower serum fibroblast growth factor 23 (FGF23) levels, although circulating klotho concentrations were significantly higher than in wild-type littermates. The transgenic mice exhibited lower bone mass and strength, particularly compared to adiponectin knockout mice. The transgenic mice were hyper-responsive to a 2% phosphate-enriched diet, exhibiting 2-fold higher serum FGF23 and concomitantly higher fractional phosphate excretion. These mice also excreted more calcium with calcium-enriched diet and had less renal klotho protein expression. In contrast, the knockout mice exhibited a smaller increase in FGF23 and maintained elevated klotho levels on both mineral challenges. Kidney-specific adiponectin expression in doxycycline-inducible adiponectin mice and adiponectin addition in vitro confirmed adiponectin's ability to reduce tubular epithelial cell klotho secretion. Thus, adiponectin alters calcium and phosphate balance and renal mineral excretion, in part, through klotho. This work highlights the profound effects of adipose tissue on renal function and has identified a new mechanism by which adiponectin may regulate bone mass.

[EVALUATION OF CARDIOVASCULAR RISKS WITH THE USE OF MORPHOGENETIC KLOTHO PROTEIN IN PATIENTS WITH CHRONIC RENAL DISEASE]

THE AIM

of the study was to explore the Klotho protein significance in patients with different stages of chronic kidney disease (CKD) and to assess the influence of antihypertensive therapy on Klotho protein serum levels.

MATERIALS AND METHODS

130 patients with stage 5 CKD1 were included in the study. Serum PTH, calcium and phosphorus were measured. ELISA was used to determine serum soluble alpha Klotho. Blood pressure including brachial and central (aortic) pressure was measured in all patients together with pulse wave velocity (using a «Sfigmokor» device); in addition, echocardiography (EchoCG), and X-ray examination of the abdominal aorta by Kauppila method were performed.

RESULTS

The dynamic study of serum Klotho level showed that it changes with decreasing glomerular filtration rate faster than a rise in phosphate and PTH levels starting from stage 3A of CKD. The two later variables increased at stages 4-5.According to the ROC analysis, the values of serum Klotho below 387 pg /ml suggested enhanced risk of myocardial calcification with 80% sensitivity and 76% specificity. In addition, the highest Klotho serum levels were observed in patients whose target BP values were achieved with angiotensin receptor blockers (ARB) compared to those who used other drugs [р<0,01] or failed to reached target BP levels [p=0,008].

CONCLUSION

The study showed the possibility of practical use of Klotho protein as an early diagnostic marker of cardiovascular risk. Reduced serum Klotho was less pronounced in patients who used ARB for correction of high blood pressure. Normal Klotho protein levels in serum have been associated with a lower frequency of heart and vessels calcification in CKD patients.

Serum Klotho (but not haplotypes) associate with the post-myocardial infarction status of older adults

OBJECTIVES:

The number of deaths from vascular diseases is incredibly high worldwide, and reliable markers for major events are still needed. The current cross-sectional study investigated the association of Klotho haplotypes and Klotho serum levels with classic risk factors and a clinical history of vascular events.

METHODS:

Clinical, anthropometric, biochemical and nutritional assessments were conducted with 168 older adults, complemented by genotyping (rs9536314 and rs9527025) and the detection of serum Klotho (ELISA).

RESULTS:

Klotho levels and haplotypes did not associate with most classic risk factors for vascular events, including markers such as C-reactive protein and homocysteine. A positive association was only found between Klotho levels and the previous occurrence of a myocardial infarction by both correlational (p=0.006) and variance analyses (p<0.001), and these associations were independent of the context.

CONCLUSION:

Our results suggest that serum Klotho is higher in individuals with a clinical history of myocardial infarction but not with a history of coronary artery disease or stroke. None of the Klotho haplotypes were associated with the variables investigated herein.

Effects of Angiotensin II Receptor Blockade on Soluble Klotho and Oxidative Stress in Calcineurin Inhibitor Nephrotoxicity in Rats

INTRODUCTION

Calcineurin inhibitor nephrotoxicity is major problem after organ transplantation. It is multifactorial, but oxidative stress may have an important role in this process. It has been shown that angiotensin II receptor blockers have renoprotective effects but their molecular mechanism is largely unknown. Antioxidative effect is an important role of the recently known anti-aging protein, klotho. This study aimed to evaluate effect of valsartan in alleviation of cyclosporine A nephrotoxicity via a probable increase in serum klotho levels or decreasing oxidative stress.

MATERIALS AND METHODS

Thirty-two Sprague-Dawley rats were divided into 4 groups to receive 1 mL/kg/d of olive oil as control; 30 mg/kg/d of cyclosporine; 30 mg/kg/d of cyclosporine and 50 mg/kg/d of valsartan; and 50 mg/kg/d of valsartan. After the 6 weeks of administration period, serum levels of klotho and 8-hydroxydeoxyguanosine were measured using an enzyme-linked immunosorbent assay. Serum malondialdehyde level was measured spectrophotometrically.

RESULTS

The mean serum level of klotho was significantly lower in the cyclosporine group compared with control and valsartan groups. Klotho level in the valsartan group was significantly higher than those in the other groups. The cyclosporine group was detected to have significantly higher serum 8-hydroxydeoxyguanosine and malondialdehyde levels compared with the other study groups. The levels of klotho were negatively correlated with 8-hydroxydeoxyguanosine and malondialdehyde levels.

CONCLUSIONS

Administration of valsartan may lead to attenuation of the nephrotoxic side effect of cyclosporine via enhancing klotho and decreasing oxidative stress levels.