Fibroblast growth factor 23/klotho axis in chronic kidney disease

Association between serum magnesium levels and cognitive function in patients undergoing hemodialysis

BACKGROUND

The relationship between chronic kidney disease-mineral and bone disorder (CKD-MBD) and cognitive function remains largely unknown. This cross-sectional study aimed to explore the association between CKD-MBD and cognitive function in patients on hemodialysis.

METHODS

Hemodialysis patients aged ≥ 65 years without diagnosed dementia were included. Cognitive function was assessed using the Montreal Cognitive Assessment (MoCA) and Mini-Mental State Examination (MMSE). CKD-MBD markers, serum magnesium, intact parathyroid hormone (PTH), 25-hydroxyvitamin D (25-OHD), fibroblast growth factor (FGF)-23, and soluble α-klotho were measured.

RESULTS

Overall, 390 patients with a median age of 74 (interquartile range, 70-80) years, mean serum magnesium level of 2.4 ± 0.3 mg/dL, and median MoCA and MMSE scores of 25 (22-26) and 28 (26-29), respectively, were analyzed. MoCA and MMSE scores were significantly higher (preserved cognitive function) in the high-magnesium group than in the low-magnesium group according to the unadjusted linear regression analysis (β coefficient [95% confidence interval (CI)] 1.05 [0.19, 1.92], P = 0.017 for MoCA; 1.2 [0.46, 1.94], P = 0.002 for MMSE) and adjusted multivariate analysis with risk factors for dementia (β coefficient [95% CI] 1.12 [0.22, 2.02], P = 0.015 for MoCA; 0.92 [0.19, 1.65], P = 0.014 for MMSE).

CONCLUSIONS

Higher serum magnesium levels might be associated with preserved cognitive function in hemodialysis patients. Conversely, significant associations were not observed between cognitive function and intact PTH, 25-OHD, FGF-23, or soluble α-klotho levels.

Secondary hyperparathyroidism in chronic kidney disease: pathophysiology, Current treatments and investigational drugs

INTRODUCTION

Secondary hyperparathyroidism (SHPT) is a common complication of chronic kidney disease (CKD). It begins as an adaptive increase in parathyroid hormone levels to prevent calcium and phosphate derangements. Over time, this condition becomes maladaptive and is associated with increased morbidity and mortality. Current therapies encompass phosphate-lowering strategies, vitamin D analogues, calcimimetics and parathyroidectomy. These approaches harbor inherent limitations, stimulating interest in the development of new drugs for SHPT to overcome these limitations and improve survival and quality of life among CKD patients.

AREAS COVERED

This review delves into the main pathophysiological mechanisms involved in SHPT, alongside the treatment options that are currently available and under active investigation. Data presented herein stem from a comprehensive search conducted across PubMed, Web of Science, ClinicalTrials.gov and International Clinical Trials Registry Platform (ICTRP) spanning from 2000 onwards.

EXPERT OPINION

The advancements in investigational drugs for SHPT hold significant promise for enhancing treatment efficacy while minimizing side effects associated with conventional therapies. Although several challenges still hinder their adoption in clinical practice, ongoing research will likely continue to expand the available therapeutic options, refine treatment strategies, and tailor them to individual patient profiles.

Establishing a Reference Interval for Fibroblast Growth Factor (FGF)-23 in Cats

Fibroblast growth factor (FGF)-23 is a phosphaturic hormone. An association between increasing FGF-23 levels and progression of chronic kidney disease (CKD) was documented in cats, dogs, and humans. The information regarding reference intervals (RIs) of FGF-23 in cats is limited. We aimed to establish RIs in a large cohort of clinically healthy cats and to investigate correlations with sex and age. A total of 118 cats with unremarkable complete blood count and serum chemistry profile were included. Clinically sick cats, cats with concurrent diseases, suspicion of CKD, or receiving renal diets were excluded. FGF-23 concentrations were measured with the FGF-23 ELISA Kit. RIs were calculated using the reference interval advisor software 2.1 (Microsoft Excel). FGF-23 concentrations were correlated with sex and age. The RI for FGF-23 concentrations spanned 85.8 to 387.0 pg/mL (90% confidence interval: lower limit 40.5 to 103.9 pg/mL, upper limit: 354.6 to 425.0 pg/mL). No significant relationships (r2 = 0.044) were detected with age (p = 0.081) or sex (p = 0.191). Other studies of the same diagnostic assay calculated RIs of 56 to 700 pg/mL in 79 cats and <336 pg/mL in 108 cats, and in concordance with the present study, did not detect any correlation with sex or age.

Alterations in regulators of the renal-bone axis, inflammation and iron status in older people with early renal impairment and the effect of vitamin D supplementation

CONTEXT

Chronic kidney disease (CKD) leads to alterations in fibroblast growth factor 23 (FGF23) and the renal-bone axis. This may be partly driven by altered inflammation and iron status. Vitamin D supplementation may reduce inflammation.

OBJECTIVE AND METHODS

Older adults with early CKD (estimated glomerular filtration rate (eGFR) 30-60 ml/min/1.73 m2; CKDG3a/b; n = 35) or normal renal function (eGFR >90 ml/min/1.73 m2; CKDG1; n = 35) received 12,000, 24,000 or 48,000 IU D3/month for 1 year. Markers of the renal-bone axis, inflammation and iron status were investigated pre- and post-supplementation. Predictors of c-terminal and intact FGF23 (cFGF23; iFGF23) were identified by univariate and multivariate regression.

RESULTS

Pre-supplementation, comparing CKDG3a/b to CKDG1, plasma cFGF23, iFGF23, PTH, sclerostin and TNFα were significantly higher and Klotho, 1,25-dihydroxyvitamin D and iron were lower. Post-supplementation, only cFGF23, 25(OH)D and IL6 differed between groups. The response to supplementation differed between eGFR groups. Only in the CKDG1 group, phosphate decreased, cFGF23, iFGF23 and procollagen type I N-propeptide increased. In the CKDG3a/b group, TNFα significantly decreased, and iron increased. Plasma 25(OH)D and IL10 increased, and carboxy-terminal collagen crosslinks decreased in both groups. In univariate models cFGF23 and iFGF23 were predicted by eGFR and regulators of calcium and phosphate metabolism at both time points; IL6 predicted cFGF23 (post-supplementation) and iFGF23 (pre-supplementation) in univariate models. Hepcidin predicted post-supplementation cFGF23 in multivariate models with eGFR.

CONCLUSION

Alterations in regulators of the renal-bone axis, inflammation and iron status were found in early CKD. The response to vitamin D3 supplementation differed between eGFR groups. Plasma IL6 predicted both cFGF23 and iFGF23 and hepcidin predicted cFGF23.

The influence of Klotho protein and prooxidant-antioxidant balance combination on the mortality of HD patients

PURPOSE

End-stage renal disease patients on chronic hemodialysis (HD) have a shortened life expectancy compared to the general population. The aim of this study was to evaluate a possible link between three new and emerging factors in renal pathophysiology: Klotho protein, telomere length in peripheral blood mononuclear cells (TL) and redox status parameters before HD (bHD) and after HD (aHD), and to test mortality prediction capability of these emerging parameters in a population of HD patients.

METHODS

The study included 130 adult patients with average age 66 (54-72), on HD (3 times per week; 4-5 h per session). Klotho level, TL, routine laboratory parameters, dialysis adequacy and redox status parameters: advanced oxidation protein products (AOPP), prooxidant-antioxidant balance (PAB), superoxide anion (O2.-), malondialdehyde (MDA), ischemia-modified albumin (IMA), total sulfhydryl group content (SHG), and superoxide dismutase (SOD) were determined.

RESULTS

Klotho concentration was significantly higher aHD; 68.2 (22.6-152.9) vs. bHD 64.2 (25.5-119.8) (p = 0.027). The observed increase in TL was not statistically significant. AOPP, PAB, SHG, and SOD activity were significantly increased aHD (p > 0.001). The patients with the highest mortality risk score (MRS) had significantly higher PAB bHD (p = 0.002). Significantly lower O2.- (p < 0.001), SHG content (p = 0.072), and IMA (p = 0.002) aHD were found in patients with the lowest MRS values. Principal component analysis revealed redox balance-Klotho factor as a significant predictor of high mortality risk (p = 0.014).

CONCLUSION

Decreased Klotho and TL attrition as well as redox status disturbance could be connected with higher mortality rate in HD patients.

Comparison of Three Different Diagnostic Assays for Fibroblast Growth Factor-23 (FGF-23) Measurements in Cats: A Pilot Study

Fibroblast growth factor-23 (FGF-23) is a phosphaturic hormone used to monitor chronic kidney disease (CKD) in humans. The aim of this pilot study was to compare three diagnostic assays and to assess how the results correlate with parameters of renal dysfunction in cats. Four groups of 10 cats each were formed retrospectively according to creatinine, based on IRIS staging. FGF-23 was measured using two different ELISAs (MyBioSource and Kainos ELISA FGF-23 Kit) and an automated assay on the DiaSorin Liaison platform. Measurements were performed in 40 cats. Spearman's rank correlation coefficient showed a strong correlation between the Kainos and DiaSorin assays (ρ = 0.742/p < 0.001) and a low correlation (ρ = 0.443/p = 0.005) between the Kainos and MyBioSource assays. The measurements with the Kainos assay strongly correlated with urea (ρ = 0.835/p < 0.001) and creatinine (ρ = 0.764/p < 0.001), and moderately correlated with SDMA (ρ = 0.580/p < 0.001) and phosphorus (ρ = 0.532/p < 0.001). The results of the MyBioSource and DiaSorin assays only showed a moderate correlation with urea (ρ = 0.624/0.572) and creatinine (ρ = 0.622/0.510) concentrations (p = 0.001 each). The Kainos assay showed the strongest correlation (ρ = 0.806) with the various creatinine concentrations according to the IRIS, followed by the MyBioSource (ρ = 0.663/p < 0.001) and DiaSorin assays (ρ = 0.580/p < 0.001). Overall, the Kainos assay demonstrated the best correlations with both biomarkers and various creatinine concentrations according to the IRIS. Individual assay-based reference values should be established to make a reliable interpretation of FGF-23 levels possible to diagnose or monitor feline CKD.

Early renal impairment affects hormonal regulators of calcium and bone metabolism and Wnt signalling and the response to vitamin D supplementation in healthy older adults

Bone and renal metabolism are regulated by common factors and there is extensive cross-talk between these organs (the 'renal-bone-axis'). Ageing is associated with physiological changes including reduced bone mass, renal function and tissue sensitivity to regulatory hormones, impacting the renal-bone axis. We aimed to investigate the influence of estimated Glomerular Filtration Rate (eGFR) on plasma concentrations of vitamin D metabolites, Wnt signalling and bone metabolism in a dose ranging vitamin D₃ RCT (12,000 IU, 24,000 IU, 48,000 IU/month for 1 year; n = 379, >70 y) with a baseline eGFR > 30 mL/min/1.73 m². Participants were categorised on basis of eGFR (≥60 or mL/min/1.73 m²) based on 5 commonly used algorithms for eGFR. Differences between eGFR categories were tested with ANCOVA. Before supplementation commenced, a lower eGFR was associated with significantly higher concentrations of c-terminal and intact Fibroblast Growth Factor-23 (cFGF23; iFGF23), intact Parathyroid Hormone (iPTH) and Sclerostin (SOST) and lower Klotho, 1,25-dihydroxy Vitamin D (1,25(OH)₂D) and Dickkopf-related Protein 1 (DKK1) concentrations. Differences between eGFR groups in 25-hydroxy Vitamin D (25(OH)D), 24,25-dihydroxy Vitamin D (24,25(OH)₂D) and iPTH were only detected with eGFR based on Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) and Modification in Diet for Renal Disease (MDRD-4) algorithms. Differences in Bone Mineral Density and Content (BMD; BMC) and bone turnover markers were detected only with Cockcroft-Gault (CG). Pre- and post- supplementation comparisons showed differences in the response to supplementation by eGFR group. Plasma 25(OH)D, 24,25(OH)₂D, 1,25(OH)₂D and DKK1 increased and iPTH and C-terminal telopeptide (CTX) decreased in both groups. Plasma iFGF23, bone specific alkaline phosphatase (BAP) and Procollagen 1 intact N-terminal Propeptide (PINP) increased and phosphate decreased only in the group with eGFR ≥ 60 mL/min/1.73 m². Findings were largely consistent across all eGFR algorithms. Post-supplementation, cFGF23, iFGF23, iPTH and SOST remained significantly higher in the lower eGFR group. Plasma 1,25(OH)₂D and Klotho did no longer differ between eGFR groups. This was found for all eGFR algorithms, with the exception of iPTH and iFGF23, which were not significantly different with eGFR based on CG. Differences in BMD and BMC were detected with CKD-EPI-creatinine and MDRD-4 but not GC. This study showed that even a moderate decline in eGFR is associated with alterations in vitamin D metabolism, Wnt signalling and bone turnover markers. Renal function influenced the response to vitamin D supplementation. Supplementation increased Vitamin D metabolites in the group with moderate renal impairment to concentrations comparable to those found in the group with normal renal function. However, although CTX decreased, an increase in bone formation markers was not found in the group with eGFR 60 mL/min/1.73 m². In conclusion, vitamin D supplementation had beneficial effects on markers of the renal-bone axis in older people with both normal and impaired renal function.

Relationship of fibroblast growth factor 21 with the prevalence and progression of vascular and valvular calcification: Multi-ethnic study of atherosclerosis

BACKGROUND

Elevated circulating levels of fibroblast growth factor 21 (FGF21) are associated with cardiovascular disease (CVD). Therefore, we investigated the relationship of plasma FGF21 with calcification at different vascular and valvular sites.

METHODS

A total of 5786 participants, free of clinically apparent CVD at baseline and with valid data on plasma FGF21 and calcification (Agatston score, volume and density) at coronary arteries, thoracic arteries, mitral and aortic valves, and aortic valve ring, were included in the analysis. Vascular calcification was measured at 2-3 follow-up visits.

RESULTS

At baseline, higher FGF21 levels were associated with prevalent descending thoracic aortic calcification (DTAC) (prevalence ratio = 1.06 [95% CI 1.01-1.11] per SD increase in log-transformed unit, P = 0.016). Among participants without prevalent calcification, higher FGF21 levels were associated with incident DTAC (relative risk [RR] = 1.13 [95% CI 1.04-1.22], P = 0.002). Among all participants, higher FGF21 levels were also associated with the progression of DTAC score and volume (RR = 1.07 [95% CI 1.03-1.12] and 1.08 [95% CI 1.03-1.12] respectively, both P < 0.01). No significant association of FGF21 was found for prevalence (prevalence ratio = 0.89-1.05), incidence (RR = 0.97-1.16) and progression of calcification (RR = 0.94-1.14) at the other sites.

CONCLUSION

Higher FGF21 levels were associated with the presence, incidence and progression of DTAC. However, the magnitude of this association was similar to those of the non-significant associations of FGF21 levels with calcifications at other sites. Further research is needed to assess the potential of FGF21 as a biomarker for vascular calcification.

Relationship between FGF 23, SDMA, Urea, Creatinine and Phosphate in Relation to Feline Chronic Kidney Disease

Chronic kidney disease (CKD) is a common diagnosis in older cats, and its prevalence increases with age. Conventional indirect biomarkers of glomerular filtration rate (GFR) have their limitations, and are not efficient in detecting early decreases in glomerular filtration rate. Recently, symmetric dimethylarginine (SDMA) concentrations have been proposed as a novel biomarker of GFR for the early detection of CKD. This study discusses the relationship between SDMA, FGF 23 and previously used indicators of kidney function, mainly creatinine, urea and phosphate. Ninety-nine cats were included in this study. Based on their SDMA values, 48 cats had CKD and the remaining 51 cats were used as a healthy control group. Serum of these cats was assayed for creatinine, urea and phosphate concentrations as well as FGF 23 values, and correlations between them were evaluated. Cats with CKD had higher FGF 23 concentrations than healthy cats, and no correlation was found between FGF 23 and SDMA, nor between FGF 23 and phosphate. On the other hand, phosphate strongly correlated with SDMA, urea and creatinine, making it a possible independent factor of CKD progression.

Stem Cell-Derived Extracellular Vesicles as Potential Therapeutic Approach for Acute Kidney Injury

Acute kidney injury is a frequent complication of hospitalized patients and significantly increases morbidity and mortality, worsening costs and length of hospital stay. Despite this impact on healthcare system, treatment still remains only supportive (dialysis). Stem cell-derived extracellular vesicles are a promising option as they recapitulate stem cells properties, overcoming safety issues related to risks or rejection or aberrant differentiation. A growing body of evidence based on pre-clinical studies suggests that extracellular vesicles may be effective to treat acute kidney injury and to limit fibrosis through direct interference with pathogenic mechanisms of vascular and tubular epithelial cell damage. We herein analyze the state-of-the-art knowledge of therapeutic approaches with stem cell-derived extracellular vesicles for different forms of acute kidney injury (toxic, ischemic or septic) dissecting their cytoprotective, regenerative and immunomodulatory properties. We also analyze the potential impact of extracellular vesicles on the mechanisms of transition from acute kidney injury to chronic kidney disease, with a focus on the pivotal role of the inhibition of complement cascade in this setting. Despite some technical limits, nowadays the development of therapies based on stem cell-derived extracellular vesicles holds promise as a new frontier to limit acute kidney injury onset and progression.

New Insights into the Role of FGF-23 and Klotho in Cardiovascular Disease in Chronic Kidney Disease Patients

Alterations of fibroblast growth factor 23 (FGF-23) and Klotho levels are considered to be the earliest biochemical abnormality of chronic kidney disease - mineral and bone disease (CKDMBD) syndrome. Moreover, emerging data suggests that the dysregulated FGF-23 and Klotho axis has many effects on the cardiovascular (CV) system and contributes significantly to the increased CV morbidity and mortality rates of CKD patients. This review examines recent evidence on the role of FGF-23 and Klotho in the development and progression of CV complications of uremia namely cardiac hypertrophy, uremic cardiomyopathy, and atherosclerotic and arteriosclerotic vascular lesions. Moreover, the available evidence on their associations with adverse clinical outcomes are summarized. Undoubtedly, more studies are needed to further elucidate the effects of FGF-23 and Klotho on the heart and vessels and to gain insights into their prognostic value as CV risk factors. Finally, large prospective studies are required to test the hypothesis that modification of their levels would have a favourable impact on the unacceptably high mortality rates of these patient populations.

Aging and Renal Disease: Old Questions for New Challenges

Chronic kidney disease (CKD) is a growing problem among aging population, and the number of individuals at risk of end stage renal disease is rising. Part of the reason lies in incomplete understanding of the pathways underlying renal aging and kidney disease, as well as insufficient delivery of evidence-based treatment to elderly patients with CKD. This review aims to address these unsolved issues by delineating updated mechanisms of renal senescence and summarizing recent findings on key clinical aspects of CKD in the elderly. Challenges and obstacles in caring for older people with CKD are discussed, with an emphasis on modification of risk factors, prevention of acute kidney injury, stabilization of progression and decision on dialysis initiation.

FGF23, alpha-Klotho and vitamin D mediated calcium-phosphate metabolism in haemodialysis patients

Background

Klotho is a prote˝in that acts as a co-receptor for FGF23. FGF23-Klotho axis has great importance regarding the regulation of mineral metabolism by kidneys. In this study, we analysed FGF23, Klotho, 1,25-dihydroxyvitamin D3, 25-hydroxyvitamin D, parathormone, Calcium and Phosphate levels of haemodialysis patients in order to investigate the nature of the mineral metabolism disruption in chronic kidney diseases.

Methods

Sixty haemodialysis patients and 34 healthy controls were included in the study. Serum iFGF, cFGF, and soluble Klotho were analysed using ELISA kits. Moreover, 1,25-dihydroxyvitamin D3 was determined using LCMS/MS. Calcium, phosphate, iPTH and 25-hydroxyvitamin D were measured using autoanalyzers.

Results

In haemodialysis patients, iFGF23, cFGF23, iPTH and P levels were significantly higher, and 1,25-dihydroxyvitamin D3, Klotho and Ca levels were significantly lower compared with the control group. There was no significant difference in the 25-hydroxyvitamin D levels.

Conclusions

Our study showed that lack of sufficient amounts of Klotho is crucial for mineral metabolism disruptions seen as a complication of chronic kidney diseases. Despite the high levels of the hormone, FGF23 is unable to accomplish its function properly, likely due to deteriorated kidney function in haemodialysis patients.

Prevalence of abnormalities in electrocardiogram conduction in dialysis patients: a comparative study

ABSTRACT Background: The electrocardiogram (ECG) can aid in identification of chronic kidney disease (CKD) patients at high risk for cardiovascular diseases. Cohort studies describe ECG abnormalities in patients on hemodialysis (HD), but we did not find data comparing ECG abnormalities among patients with normal kidney function or peritoneal dialysis (PD) to those on hemodialysis. We hypothesized that ECG conduction abnormalities would be more common, and cardiac conduction interval times longer, among patients on hemodialysis vs. those on peritoneal dialysis and CKD 1 or 2. Methods: Retrospective review of adult inpatients’ charts, comparing those with billing codes for “Hemodialysis” vs. inpatients without those charges, and an outpatient peritoneal dialysis cohort. Patients with CKD 3 or 4 were excluded. Results: One hundred and sixty-seven charts were reviewed. ECG conduction intervals were consistently and statistically longer among hemodialysis patients (n=88) vs. peritoneal dialysis (n=22) and CKD stage 1 and 2 (n=57): PR (175±35 vs 160±44 vs 157±22 msec) (p=0.009), QRS (115±32 vs. 111±31 vs 91±18 msec) (p=0.001), QT (411±71 vs. 403±46 vs 374±55 msec) (p=0.006), QTc (487±49 vs. 464±38 vs 452±52 msec) (p=0.0001). The only significantly different conduction abnormality was prevalence of left bundle branch block: 13.6% among HD patients, 5% in PD, and 2% in CKD 1 and 2 (p=0.03). Conclusion: To our knowledge, this is the first study to report that ECG conduction intervals are significantly longer as one progresses from CKD Stage 1 and 2, to PD, to HD. These and other data support the need for future research to utilize ECG conduction times to identify dialysis patients who could potentially benefit from proactive cardiac evaluations and risk reduction.

Fibroblast growth factor-23 as an early marker of CKD-mineral bone disorder in dogs: preliminary investigation

OBJECTIVES

To examine the relationship between fibroblast growth factor-23 levels, chronic kidney disease severity and mineral metabolic disorders associated to chronic kidney disease in dogs.

MATERIALS AND METHODS

Fifteen control and 75 chronic kidney disease dogs were retrospectively included. Serum fibroblast growth factor-23 concentration and other phosphate metabolite parameters were compared between controls and each International Renal Interest Society stage. Multiple regression analysis was performed to determine the predictors of fibroblast growth factor-23.

RESULTS

Serum fibroblast growth factor-23 concentrations were significantly higher in dogs with IRIS stages 2, 3 and 4 chronic kidney disease than those in dogs in control group and with stage 1 and increased along with the severity of chronic kidney disease. Compared with control dogs, serum intact parathyroid hormone significantly increased from stage 2 and serum phosphorus concentrations increased in dogs with stage 4. In dogs with stage 2, fibroblast growth factor-23 levels significantly increased in those with hyperphosphatemia compared with those with normophosphatemia. While eight of 26 (30.8%) dogs with stage 2 developed hyperparathyroidism (intact parathyroid hormone>8.5 ng/L), 19 (73.1%) dogs with stage 2 had elevated fibroblast growth factor-23 levels above the reference range (>528 pg/mL). Log creatinine, log intact parathyroid hormone and log product of total calcium and phosphorus were independent predictors of log fibroblast growth factor-23.

CLINICAL SIGNIFICANCE

This preliminary study suggests that canine fibroblast growth factor-23 might be involved in mineral metabolic disorders associated to chronic kidney disease in dogs, and this factor could be potentially used as an early marker for this condition.

Dietary vitamin D interacts with high phosphate-induced cardiac remodeling in rats with normal renal function

BACKGROUND

Vitamin D (VD) and phosphate (Pi) load are considered as contributors to cardiovascular disease in chronic kidney disease and the general population, but interactive effects of VD and Pi intake on the heart are not clearly illustrated.

METHODS

We fed normal male rats with three levels of dietary VD (100, 1100 or 5000 IU/kg chow) and Pi (0.2, 0.6 or 1.6%) (3X3 design) for 8 weeks and examined renal and cardiac function and histology.

RESULTS

High dietary Pi decreased plasma and renal Klotho and plasma 25-hydroxyvitamin D, and increased plasma Pi, fibroblast growth factor 23 and parathyroid hormone without affecting renal function, while low Pi increased plasma and renal Klotho. Both low and high VD diets enhanced high Pi-reduced Klotho expression. Low dietary VD reduced-plasma Klotho was rescued by a low Pi diet. High dietary Pi reduced-cardiac ejection fraction was not modified by a low or high VD diet, but the dietary VD effects on cardiac pathologic changes were more complex. High dietary Pi-induced cardiac hypertrophy was attenuated by a low VD and exacerbated by a high VD diet. In contrast, high dietary Pi -induced cardiac fibrosis was magnified by a low VD and attenuated by a high VD diet.

CONCLUSIONS

High Pi diet induces hypertrophy and fibrosis in left ventricles, a low VD diet accelerates high Pi-induced fibrosis, and a high VD diet exacerbated high Pi -induced hypertrophy. Therefore, cardiac phosphotoxicity is exacerbated by either high or low dietary VD in rats with normal kidney function.

Chronic Kidney Disease as Oxidative Stress- and Inflammatory-Mediated Cardiovascular Disease

Generating reactive oxygen species (ROS) is necessary for both physiology and pathology. An imbalance between endogenous oxidants and antioxidants causes oxidative stress, contributing to vascular dysfunction. The ROS-induced activation of transcription factors and proinflammatory genes increases inflammation. This phenomenon is of crucial importance in patients with chronic kidney disease (CKD), because atherosclerosis is one of the critical factors of their cardiovascular disease (CVD) and increased mortality. The effect of ROS disrupts the excretory function of each section of the nephron. It prevents the maintenance of intra-systemic homeostasis and leads to the accumulation of metabolic products. Renal regulatory mechanisms, such as tubular glomerular feedback, myogenic reflex in the supplying arteriole, and the renin-angiotensin-aldosterone system, are also affected. It makes it impossible for the kidney to compensate for water-electrolyte and acid-base disturbances, which progress further in the mechanism of positive feedback, leading to a further intensification of oxidative stress. As a result, the progression of CKD is observed, with a spectrum of complications such as malnutrition, calcium phosphate abnormalities, atherosclerosis, and anemia. This review aimed to show the role of oxidative stress and inflammation in renal impairment, with a particular emphasis on its influence on the most common disturbances that accompany CKD.

Prevalence of abnormalities in electrocardiogram conduction in dialysis patients: a comparative study

BACKGROUND

The electrocardiogram (ECG) can aid in identification of chronic kidney disease (CKD) patients at high risk for cardiovascular diseases. Cohort studies describe ECG abnormalities in patients on hemodialysis (HD), but we did not find data comparing ECG abnormalities among patients with normal kidney function or peritoneal dialysis (PD) to those on hemodialysis. We hypothesized that ECG conduction abnormalities would be more common, and cardiac conduction interval times longer, among patients on hemodialysis vs. those on peritoneal dialysis and CKD 1 or 2.

METHODS

Retrospective review of adult inpatients' charts, comparing those with billing codes for "Hemodialysis" vs. inpatients without those charges, and an outpatient peritoneal dialysis cohort. Patients with CKD 3 or 4 were excluded.

RESULTS

One hundred and sixty-seven charts were reviewed. ECG conduction intervals were consistently and statistically longer among hemodialysis patients (n=88) vs. peritoneal dialysis (n=22) and CKD stage 1 and 2 (n=57): PR (175±35 vs 160±44 vs 157±22 msec) (p=0.009), QRS (115±32 vs. 111±31 vs 91±18 msec) (p=0.001), QT (411±71 vs. 403±46 vs 374±55 msec) (p=0.006), QTc (487±49 vs. 464±38 vs 452±52 msec) (p=0.0001). The only significantly different conduction abnormality was prevalence of left bundle branch block: 13.6% among HD patients, 5% in PD, and 2% in CKD 1 and 2 (p=0.03).

CONCLUSION

To our knowledge, this is the first study to report that ECG conduction intervals are significantly longer as one progresses from CKD Stage 1 and 2, to PD, to HD. These and other data support the need for future research to utilize ECG conduction times to identify dialysis patients who could potentially benefit from proactive cardiac evaluations and risk reduction.

Vitamin D Deficiency, Hypocalcemia, and Hearing Loss in Children

OBJECTIVE

Characterize relations between vitamin D deficiency (VDD), hypocalcemia, and hearing loss (HL) in children.

STUDY DESIGN

Retrospective review.

SETTING

Tertiary referral hospital.

PATIENTS

Children in the Audiological and Genetic Database with a diagnosis of VDD, rickets, or osteomalacia.

INTERVENTION

None.

MAIN OUTCOME MEASURES

Prevalence, type, severity (4-tone pure-tone average, PTA), and progression of HL. HL was defined as greater than 15 dB HL at any threshold by pure tone, greater than 20 dB HL by sound field audiometry, or greater than 25 dB in infants less than 1 year of age.

RESULTS

Of 888 children with VDD, 474 (53.4%) had HL, with 17% having moderate-profound HL. Compared with an age-matched cohort of 13,320 children drawn from the same database, children with VDD were significantly more likely to have sensorineural HL (SNHL) (adjusted odds ratios [aOR] 1.26 [95% confidence interval [CI] 1.01-1.58]). Among children with VDD, children with femur fracture had a significantly higher rate of HL (81% versus 53%, p = 0.008) and children with hypocalcemia had a significantly higher rate of moderate-profound HL (36% versus 18%, p = 0.016). Additionally, hypocalcemia with and without VDD was associated with SNHL (aOR 2.30 [1.07-4.56]).

CONCLUSIONS

Both vitamin D deficiency and hypocalcemia were found to be independently associated with SNHL, a type of HL that is less likely to improve over time. Recognition of VDD and hypocalcemia as independent risk factors for the development of SNHL could allow for better evaluation and treatment of this patient population. Routine audiological evaluation should be considered in this population.

Inflammaging and Complement System: A Link Between Acute Kidney Injury and Chronic Graft Damage

The aberrant activation of complement system in several kidney diseases suggests that this pillar of innate immunity has a critical role in the pathophysiology of renal damage of different etiologies. A growing body of experimental evidence indicates that complement activation contributes to the pathogenesis of acute kidney injury (AKI) such as delayed graft function (DGF) in transplant patients. AKI is characterized by the rapid loss of the kidney's excretory function and is a complex syndrome currently lacking a specific medical treatment to arrest or attenuate progression in chronic kidney disease (CKD). Recent evidence suggests that independently from the initial trigger (i.e., sepsis or ischemia/reperfusions injury), an episode of AKI is strongly associated with an increased risk of subsequent CKD. The AKI-to-CKD transition may involve a wide range of mechanisms including scar-forming myofibroblasts generated from different sources, microvascular rarefaction, mitochondrial dysfunction, or cell cycle arrest by the involvement of epigenetic, gene, and protein alterations leading to common final signaling pathways [i.e., transforming growth factor beta (TGF-β), p16 ink4a , Wnt/β-catenin pathway] involved in renal aging. Research in recent years has revealed that several stressors or complications such as rejection after renal transplantation can lead to accelerated renal aging with detrimental effects with the establishment of chronic proinflammatory cellular phenotypes within the kidney. Despite a greater understanding of these mechanisms, the role of complement system in the context of the AKI-to-CKD transition and renal inflammaging is still poorly explored. The purpose of this review is to summarize recent findings describing the role of complement in AKI-to-CKD transition. We will also address how and when complement inhibitors might be used to prevent AKI and CKD progression, therefore improving graft function.

Rostral ventrolateral medulla neuron activity is suppressed by Klotho and stimulated by FGF23 in newborn Wistar rats

Hypertension often occurs in patients with chronic kidney disease (CKD). Considering the decrease in serum Klotho and increase in serum FGF23 levels in such patients, decreased Klotho and increased FGF23 levels were thought to be associated with hypertension. Presympathetic neurons at the rostral ventrolateral medulla (RVLM) contribute to sympathetic activity and regulation of blood pressure. Therefore, we hypothesized that Klotho would reduce the activities of RVLM neurons and FGF23 would stimulate them. Accordingly, this study examined the effects of Klotho and FGF23 on bulbospinal neurons in the RVLM. We used a brainstem-spinal cord preparation to record from RVLM presympathetic neurons and to evaluate the effects of Klotho and FGF23 on firing rate and membrane potentials of these neurons. Our results showed that Klotho-induced RVLM neuron hyperpolarization, while ouabain, a Na⁺/K⁺-ATPase inhibitor, suppressed the effects of Klotho on such neurons. Moreover, FGF23 induced RVLM neuron depolarization, while SU5402, an FGF23 receptor (FGFR1) antagonist, induced RVLM neuron hyperpolarization. Histological examinations revealed that Klotho, Na⁺/K⁺-ATPase, FGF23, and FGFR1 were present in RVLM neurons and that Klotho was localized in the same neurons as FGFR1. These results suggest that Klotho and FG23 regulate the activity of RVLM neurons. Klotho may reduce the activity of RVLM neurons via stimulating Na⁺/K⁺-ATPase on those neurons while FGF23 may activate those neurons via FGFR1.

Comparison of fractional excretion of electrolytes in patients at different stages of chronic kidney disease: A cross-sectional study

Kidney handling of electrolytes varies in different stages of chronic kidney disease (CKD). Diabetes mellitus (DM) plays an important role in CKD. Fractional excretion (FE) is an important means in clinical practice. The relationship between FE of electrolytes in patients at different stages of CKD is worth further investigating.We designed a cross-sectional study in 1 teaching hospital, consecutive CKD patients were enrolled between February 2016 and January 2017. Including clinical demographic features, laboratory examination including spot urine electrolytes, blood biochemistries, and relevant medications were determined.A total of 762 CKD patients completed the study. Of these, 218 (28.6%) had DM. Participants were grouped according to estimated glomerular filtration rate into 7 categories: hyperfiltration (HF), CKD1, CKD2, CKD3a, CKD3b, CKD4, and CKD5. Groups HF, CKD1, 2, 3a, 3b, 4 and 5 contained 83, 143, 192, 94, 82, 82, and 86 patients, respectively. FE of electrolytes tended to increase along with the decline of renal function (CKD1-CKD5) (P < .001). The relationship was similar between the DM and non-DM groups. Diabetic patients demonstrated higher FE of magnesium compared with non-DM subjects at CKD2 and CKD5 (P < .05).CKD patients showed a progressive increase in the FE of electrolytes; FE of magnesium seemed to increase more among diabetic patients with CKD, and could be a potential predictor of CKD progression.

Cardio-ankle vascular index is linked to deranged metabolic status, especially high HbA1c and monocyte-chemoattractant-1 protein, in predialysis chronic kidney disease

INTRODUCTION AND PURPOSE

Arterial stiffness is an independent predictor of cardiovascular disease in chronic kidney disease (CKD). Cardio-ankle vascular index (CAVI) is a newly developed method used to assess arterial stiffness, independent of changes in blood pressure. CAVI reflects stiffness and atherosclerosis at the thoracic, abdominal, common iliac, femoral, and tibial artery levels. In predialysis stage 3-5 diabetic and nondiabetic CKD patients, CAVI levels and its relation to atherosclerosis-associated risk factors including monocyte-chemoattractant protein-1 (MCP-1), sclerostin, fibroblast growth factor-23 (FGF-23), Klotho, and 25-OH vitamin D were determined.

MATERIALS AND METHODS

The study was performed on three age-matched and gender-matched groups. Group 1 included 46 stage 3-5 nondiabetic CKD patients, group 2 included 44 stage 3-5 diabetic CKD patients, and group 3 included 44 non-uremic controls. All subjects underwent CAVI measurement. Serum glycated hemoglobin (HbA1c), total calcium, phosphorus, parathormone, FGF-23, Klotho, MCP-1, sclerostin, and 25-OH vitamin D were determined using standard methods.

RESULTS

CAVI level was 8.22 ± 0.18 m/s in diabetic CKD patients and significantly higher than in nondiabetic CKD (7.61 ± 0.18 m/s) and control (7.59 ± 0.17 m/s) patients. FGF-23 level was higher in the CKD groups than controls but not statistically significant. MCP-1 level was significantly higher in diabetic CKD patients. Klotho and sclerostin levels were significantly lower in diabetic CKD patients. In the whole cohort, CAVI showed positive correlations with age (r = 0.447, p < 0.0001), smoking (r = 0.331, p = 0.035), mean arterial blood pressure (MABP; r = 0.327, p < 0.0001), fasting blood glucose (r = 0.185, p = 0.033), and HbA1c (r = 0.258, p = 0.003). Stepwise regression analysis revealed that age (p = 0.0001, B = 0.461), MABP (p < 0.0001, B = 0.365), HbA1c (p = 0.003, B = 0.251), and MCP-1 (p = 0.013, B = 0.214) independently predicted CAVI levels.

CONCLUSION

Our results indicate higher CAVI levels, therefore, resulting in increased arterial stiffness in the setting of diabetic CKD. Apart from age and MABP, deranged metabolic status, especially increased HbA1c and MCP-1 levels, is also independently associated with increasing CAVI levels in CKD patients. These results emphasize the importance of metabolic control in the development of arterial stiffness in CKD patients, which is an early predictor of developing cardiovascular complications.

Klotho Deficiency Accelerates Stem Cells Aging by Impairing Telomerase Activity

Understanding the effect of molecular pathways involved in the age-dependent deterioration of stem cell function is critical for developing new therapies. The overexpression of Klotho (KL), an antiaging protein, causes treated animal models to enjoy extended life spans. Now, the question stands: Does KL deficiency accelerate stem cell aging and telomere shortening? If so, what are the specific mechanisms by which it does this, and is cycloastragenol (CAG) treatment enough to restore telomerase activity in aged stem cells? We found that KL deficiency diminished telomerase activity by altering the expression of TERF1 and TERT, causing impaired differentiation potential, pluripotency, cellular senescence, and apoptosis in stem cells. Telomerase activity decreased with KL-siRNA knockdown. This suggests that both KL and telomeres regulate the stem cell aging process through telomerase subunits TERF1, POT1, and TERT using the TGFβ, Insulin, and Wnt signaling. These pathways can rejuvenate stem cell populations in a CD90-dependent mechanism. Stem cell dysfunctions were largely provoked by KL deficiency and telomere shortening, owing to altered expression of TERF1, TGFβ1, CD90, POT1, TERT, and basic fibroblast growth factor (bFGF). The CAG treatment partially rescued telomerase deterioration, suggesting that KL plays a critical role in life-extension by regulating telomere length and telomerase activity.

Cardiac FGF23: new insights into the role and function of FGF23 after acute myocardial infarction

OBJECTIVE

We aimed to elucidate the local role of FGF23 after myocardial infarction in a mouse model induced by left anterior descending artery (LAD) ligation. APPROACH AND RESULTS: (C57BL/6 N) mice underwent MI via LAD ligation and were sacrificed at different time-points post MI. The expression and influence of FGF23 on fibroblast and macrophages was also analyzed using isolated murine cells. We identified enhanced cardiac FGF23 mRNA expression in a time-dependent manner with an early increase, already on the first day after MI. FGF23 protein expression was abundantly detected in the infarcted area during the inflammatory phase. While described to be primarily produced in bone or macrophages, we identified cardiac fibroblasts as the only source of local FGF23 production after MI. Inflammatory mediators, such as IL-1β, IL-6 and TNF-α, were able to induce FGF23 expression in these cardiac fibroblasts. Interestingly, we were not able to detect FGF23 at later time points after MI in mature scar tissue or remote myocardium, most likely due to TGF-β1, which we have shown to inhibit the expression of FGF23. We identified FGFR1c to be the most abundant receptor for FGF23 in infarcted myocardium and cardiac macrophages and fibroblasts. FGF23 increased migration of cardiac fibroblast, as well as expression of Collagen 1, Periostin, Fibronectin and MMP8. FGF23 also increased expression of TGF-β1 in M2 polarized macrophages.

CONCLUSION

In conclusion, cardiac fibroblasts in the infarcted myocardium produce and express FGF23 as well as its respective receptors in a time-dependent manner, thus potentially influencing resident cell migration. The transitory local expression of FGF23 after MI points towards a complex role of FGF23 in myocardial ischemia and warrants further exploration, considering its role in ventricular remodeling.

Fractional excretion of phosphorus and vascular calcification in stage 3 chronic kidney disease

The role of renal excretion of Pi in relation to vascular calcification (VC) in patients in the early stages of chronic kidney disease (CKD) is controversial. Thus, we determine the relation between fractional excretion of phosphorus (FEP) and VC, measured using two methods in a cross-sectional study of patients with stage 3 CKD. We recorded demographic data, anthropometry, comorbidities and active treatment. We measured 24-hour urine FEP and, in serum, measured fibroblast growth factor 23 (FGF23), α-Klotho, intact parathyroid hormone (iPTH), calcium and phosphorus. VC was measured by lateral abdominal radiography (Kauppila index (KI)) and CT of the abdominal aorta (measured in Agatston units). In 57% of subjects, abnormal VC was present when measured using CT, and in only 17% using lateral abdominal radiography. Factors associated with VC using CT were age, cardiovascular risk factors, vascular comorbidity, microalbuminuria and levels of FGF23, phosphorus and calcium x phosphorus product (CaxP); although only age (OR 1.25, 95% CI 1.11 to 1.41), smoking (OR 21.2, CI 4.4 to 100) and CaxP (OR 1.21, CI 1.06 to 1.37) maintained the association in a multivariate analysis. By contrast, only age (OR 1.35, 95% CI 1.07 to 1.74), CaxP (OR 1.14, CI 1.13 to 1.92) and FEP (OR 1.07,95% CI 1004 to 1.14) were associated with abnormal VC in the lateral abdominal radiography. In conclusion, in patients with stage 3 CKD, the detection of VC by abdominal CT is more sensitive than conventional X-rays. Moreover, CaxP is associated with cardiovascular risk factors and vascular comorbidity; quantification of FEPi in these patients provides additional clinical information in advanced VC detected by KI.

The FGF-23/klotho axis and its relationship with phosphorus, calcium, vitamin D, PTH, aldosterone, severity of disease, and outcome in hospitalised foals

BACKGROUND

Fibroblast growth factor-23 (FGF-23) and klotho are key regulators of vitamin D and parathyroid hormone (PTH) synthesis as well as phosphorus and calcium homeostasis; however, information on the FGF-23/klotho axis in healthy and hospitalised foals is lacking.

OBJECTIVES

The aims of this study were to measure serum FGF-23 and klotho concentrations and determine their association with serum phosphorus, total calcium (TCa), vitamin D metabolite [25(OH)D, 1,25(OH)₂ D], PTH, and aldosterone concentrations, disease severity, and mortality in hospitalised foals.

STUDY DESIGN

Prospective, multicentre, cross-sectional study.

METHODS

A total of 91 foals ≤72 h old were classified as hospitalised (n = 81; 58 septic; 23 sick non-septic [SNS]) and healthy (n = 10). Blood samples were collected on admission. Hormone concentrations were determined by immunoassays.

RESULTS

Serum FGF-23, PTH, phosphorus, and aldosterone concentrations were higher while klotho, 25(OH)D, 1,25(OH)₂ D, and TCa concentrations were lower in septic and SNS compared to healthy foals (P<0.05). In hospitalised and septic foals, increased FGF-23 and aldosterone concentrations were associated with high phosphorus and PTH but not with TCa and vitamin D metabolite concentrations. Hospitalised foals with the highest FGF-23 and lowest klotho concentrations were more likely to die (odds ratio (OR): 3.3; 95% confidence interval (CI): 1.1-10.3 and OR: 3.1; CI: 1.1-8.0, respectively).

MAIN LIMITATIONS

Blood gas, ionised calcium, blood culture information not being available for many foals, and use of the sepsis score to classify hospitalised foals.

CONCLUSIONS

Imbalances in the FGF-23/klotho axis may contribute to mineral dyshomeostasis and disease progression in critically ill foals. Elevated FGF-23 and reduced klotho, together with high phosphorus and PTH concentrations suggests FGF-23 resistance. FGF-23 and klotho are good markers of disease severity and likelihood of mortality in hospitalised foals. Aldosterone may influence phosphorus and PTH dynamics in hospitalised foals. Routine measurement of phosphorus concentrations in sick foals is recommended.

Serum sclerostin: relation with mortality and impact of hemodiafiltration

Background

The glycoprotein sclerostin (Scl; 22 kDa), which is involved in bone metabolism, may play a role in vascular calcification in haemodialysis (HD) patients. In the present study, we investigated the relation between serum Scl (sScl) and mortality. The effects of dialysis modality and the magnitude of the convection volume in haemodiafiltration (HDF) on sScl were also investigated.

Methods

In a subset of patients from the CONTRAST study, a randomized controlled trial comparing HDF with HD, sScl was measured at baseline and at intervals of 6, 12, 24 and 36 months. Patients were divided into quartiles, according to their baseline sScl. The relation between time-varying sScl and mortality with a 4-year follow-up period was investigated using crude and adjusted Cox regression models. Linear mixed models were used for longitudinal measurements of sScl.

Results

The mean (±standard deviation) age of 396 test subjects was 63.6 (±13.9 years), 61.6% were male and the median follow-up was 2.9 years. Subjects with the highest sScl had a lower mortality risk than those with the lowest concentrations [adjusted hazard ratio 0.51 (95% confidence interval, CI, 0.31-0.86, P = 0.01)]. Stratified models showed a stable sScl in patients treated with HD (Δ +2.9 pmol/L/year, 95% CI -0.5 to +6.3, P = 0.09) and a decreasing concentration in those treated with HDF (Δ -4.5 pmol/L/year, 95% CI -8.0 to -0.9, P = 0.02). The relative change in the latter group was related to the magnitude of the convection volume.

Conclusions

(i) A high sScl is associated with a lower mortality risk in patients with end-stage kidney disease; (ii) treatment with HDF causes sScl to fall; and (iii) the relative decline in patients treated with HDF is dependent on the magnitude of the convection volume.

High calcium diet alleviates 5/6 nephrectomy-induced bone deteriorations of lumbar vertebrae in mice

Dietary calcium (Ca) supplementation has beneficial effects on bone health. However, it is not clear whether a high calcium diet (HCD) following 5/6 nephrectomy (5/6 Nx) is beneficial to bone health. The aim of the present study was to examine the effects of an HCD on bone metabolism using a chronic kidney disease (CKD) mouse model. Male C57BL/6J mice were divided into three groups: Sham group, 5/6 Nx group and 5/6 Nx + HCD group. Mice were sacrificed 12 weeks post-surgery. Calcium (Ca) and creatinine (Cr) were measured using standard colorimetric methods and picric acid methods, respectively. Bone metabolism-associated markers, FGF-23, PTH, ALP-b and TRAP-5b were measured using ELISA kits. Lumbar vertebrae histomorphological analysis was performed using hematoxylin and eosin staining. The expression of osteoprotegerin (OPG) and receptor activator of nuclear factor κB ligand (RANKL) mRNA was detected using reverse transcription-quantitative polymerase chain reaction. Impaired renal function and histopathological damage was indicated in 5/6 Nx mice. However, HCD had no significant effects on these changes in 5/6 Nx mice. Notably, mineral metabolism disorder and histopathological damage to lumbar vertebrae were markedly improved in HCD-treated 5/6 Nx mice. Compared with 5/6 Nx mice, HCD supplementation significantly elevated the ratio of OPG/RANKL and inhibited RANKL mRNA expression in lumbar vertebrae. To conclude, the present findings indicated that increased Ca intake is effective in increasing bone mineral content of the lumbar vertebrae in 5/6 Nx mice. These results may provide a basis for the clinical use of dietary Ca supplementation as a therapeutic approach to treat CKD-induced disturbance of mineral metabolism and bone loss.

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.

Serum Klotho, vitamin D, and homocysteine in combination predict the outcomes of Chinese patients with multiple system atrophy

AIMS

Neuroinflammation contributed to the pathogenesis of multiple system atrophy (MSA). We aimed to detect the correlation between inflammatory mediators, such as Klotho (Klt), vitamin D (25(OH)D) and homocysteine (Hcy), and disease severity among MSA patients.

METHODS

A total of 53 MSA patients, 65 PD patients, and 62 normal subjects were recruited in our cross-sectional study. Serum Klotho (Klt), vitamin D (25(OH)D), and homocysteine (Hcy) levels were measured. Several scales were undertaken to assess the motor/nonmotor function and cognitive impairment of MSA.

RESULTS

Decreased Serum Klt and 25(OH)D levels and increased Hcy levels were found in patients with MSA, compared with healthy controls. These results were more pronounced in male patients. The three biomarkers also displayed differences between MSA and PD subgroups based on genders. Interestingly, Klt, 25(OH)D and Hcy levels associated with cognition impairment, motor dysfunction, mood/cardiovascular disorder among MSA patients. In addition, the combination of Klt, 25(OH)D and Hcy had a better diagnostic ability for distinguishing MSA patients from healthy subjects, as well as distinguishing male MSA patients from male PD patients.

CONCLUSION

This study suggested that Klt, 25(OH)D and Hcy levels could be a potential predictor for MSA severity evaluation.

Fibroblast Growth Factor-23 Concentration in Dogs with Chronic Kidney Disease

Background

Chronic kidney disease (CKD) is associated with hyperphosphatemia, decreased vitamin D metabolite concentrations, and hyperparathyroidism. This syndrome is known as CKD‐mineral bone disorder (CKD‐MBD). Recently, it has been shown that an increase in fibroblast growth factor‐23 (FGF‐23) concentration is an early biomarker of CKD in people. It is an independent risk factor for both progression of renal disease and survival time in humans and cats with CKD. Information about FGF‐23 in healthy dogs and those with CKD is lacking.

Objectives

To measure FGF‐23 concentration in dogs with different stages of CKD and determine its association with factors involved in CKD‐MBD, including serum phosphorus and parathyroid hormone (PTH) concentrations. A secondary aim was to validate an ELISA for measurement of plasma FGF‐23 concentration in dogs.

Animals

Thirty‐two client‐owned dogs with naturally occurring CKD and 10 healthy control dogs.

Methods

Prospective cross‐sectional study. An FGF‐23 ELISA was used to measure plasma FGF‐23 concentration in dogs and their association with serum creatinine, phosphorus, calcium, and PTH concentrations.

Results

Plasma FGF‐23 concentrations increased with severity of CKD and were significantly different between IRIS stages 1 and 2 versus stages 3 and 4 (P < .0001). Increases in FGF‐23 concentrations were more frequent than hyperparathyroidism or hyperphosphatemia in this cohort. Serum creatinine and phosphorus concentrations were the strongest independent predictors of FGF‐23 concentration.

Conclusions and clinical importance

Plasma FGF‐23 concentrations increase in dogs with CKD as disease progresses. Plasma FGF‐23 concentrations appear to be useful for further study of the pathophysiology of CKD‐MBD in dogs.

Role of Vitamin D in Uremic Vascular Calcification

The risk of cardiovascular death is 10 times higher in patients with CKD (chronic kidney disease) than in those without CKD. Vascular calcification, common in patients with CKD, is a predictor of cardiovascular mortality. Vitamin D deficiency, another complication of CKD, is associated with vascular calcification in patients with CKD. GFR decline, proteinuria, tubulointerstitial injury, and the therapeutic dose of active form vitamin D aggravate vitamin D deficiency and reduce its pleiotropic effect on the cardiovascular system. Vitamin D supplement for CKD patients provides a protective role in vascular calcification on the endothelium by (1) renin-angiotensin-aldosterone system inactivation, (2) alleviating insulin resistance, (3) reduction of cholesterol and inhibition of foam cell and cholesterol efflux in macrophages, and (4) modulating vascular regeneration. For the arterial calcification, vitamin D supplement provides adjunctive role in regressing proteinuria, reverse renal osteodystrophy, and restoring calcification inhibitors. Recently, adventitial progenitor cell has been linked to be involved in the vascular calcification. Vitamin D may provide a role in modulating adventitial progenitor cells. In summary, vitamin D supplement may provide an ancillary role for ameliorating uremic vascular calcification.

The effect of nephrectomy on Klotho, FGF-23 and bone metabolism

Background

Increased concentration of fibroblast growth factor 23 (FGF-23) and decreased levels of soluble Klotho (sKL) are linked to negative clinical outcomes among patients with chronic kidney disease and acute kidney injury. Therefore, it is reasonable to hypothesize that GFR reduction caused by nephrectomy might alter mineral metabolism and induces adverse consequences. Whether nephrectomy due to urological indications causes derangements in FGF-23 and sKL has not been studied. The aim of the study was to evaluate the effect of acute GFR decline due to unilateral nephrectomy on bone metabolism, FGF-23 and sKL levels.

Methods

This is a prospective, single-centre observational study of patients undergoing nephrectomy due to urological indications. Levels of C-terminal FGF-23 (c-FGF-23), sKL and bone turnover markers [β-crosslaps (CTX), bone-specific alkaline phosphatase (bALP) and tartrate-resistant acid phosphatase 5b (TRAP 5b)] were measured before and after surgery (5 ± 2 days).

Results

Twenty-nine patients were studied (14 females, age 63.0 ± 11.6, eGFR 87.3 ± 19.2 ml/min/1.73 m²). After surgery, eGFR significantly declined (p < 0.0001). Nephrectomy significantly decreased sKL level [709.8 (599.9–831.2) vs. 583.0 (411.7–752.6) pg/ml, p < 0.001] and did not change c-FGF-23 concentration [70.5 (49.8–103.3) vs. 77.1 (60.5–109.1) RU/ml, p = 0.9]. Simultaneously, alterations in bone turnover markers were observed. Serum concentration of CTX increased [0.49 (0.4–0.64) vs. 0.59 (0.46–0.85) ng/ml, p = 0.001], while bALP and TRAP 5b decreased [23.6 (18.8–31.4) vs. 17.9 (15.0–22.0) U/l, p < 0.0001 and 3.3 (3.0–3.7) vs. 2.8 (2.3–3.2) U/l, p < 0.001, respectively].

Conclusions

Nephrectomy among patients with preserved renal function before surgery does not increase c-FGF-23 but reduces sKL. Moreover, nephrectomy results in derangements in bone turnover markers in short-term follow-up. These changes may participate in pathogenesis of bone disease after nephrectomy.

Upregulation of Oxidative Stress Related Genes in a Chronic Kidney Disease Attributed to Specific Geographical Locations of Sri Lanka

Objective. To infer the influence of internal and external oxidative stress in chronic kidney disease patients of unknown etiology (CKDu) in Sri Lanka, by analyzing expression of genes related directly or indirectly to oxidative stress: glutamate-cysteine ligase catalytic subunit (GCLC), glutathione S-transferase mu 1 (GSTM1), glucose-6-phosphate dehydrogenase (G6PD), fibroblast growth factor-23 (FGF23), and NLR family pyrin domain containing 3 (NLRP3). Methods. Reverse transcription quantitative polymerase chain reaction (RT-qPCR) was carried out for the selected populations: CKDu patients (n = 43), chronic kidney disease patients (CKD; n = 14), healthy individuals from a CKDu endemic area (GHI; n = 9), and nonendemic area (KHI; n = 16). Fold changes were quantified relative to KHI. Results. GCLC had greater than threefold upregulation in all three study groups, with a maximum of 7.27-fold upregulation in GHI (p = 0.000). GSTM1 was not expressed in 25.6% of CKDu and 42.9% of CKD patients, but CKDu patients expressing GSTM1 showed upregulation of 2.60-fold (p < 0.05). Upregulation of FGF23 and NLRP3 genes in CKD and CKDu was observed (p < 0.01), with greater fold changes in CKD. Conclusion. Results suggest higher influence of external sources of oxidative stress in CKDu, possibly owing to environmental conditions.

Renal Aging: Causes and Consequences

Individuals age >65 years old are the fastest expanding population demographic throughout the developed world. Consequently, more aged patients than before are receiving diagnoses of impaired renal function and nephrosclerosis-age-associated histologic changes in the kidneys. Recent studies have shown that the aged kidney undergoes a range of structural changes and has altered transcriptomic, hemodynamic, and physiologic behavior at rest and in response to renal insults. These changes impair the ability of the kidney to withstand and recover from injury, contributing to the high susceptibility of the aged population to AKI and their increased propensity to develop subsequent progressive CKD. In this review, we examine these features of the aged kidney and explore the various validated and putative pathways contributing to the changes observed with aging in both experimental animal models and humans. We also discuss the potential for additional study to increase understanding of the aged kidney and lead to novel therapeutic strategies.

Circulating fibroblast growth factor-23 plasma levels predict adverse cardiovascular outcomes in patients with diabetes mellitus with coronary artery disease

BACKGROUND

Abnormalities of fibroblast growth factor-23 (FGF-23) plasma levels predict adverse outcomes in patients with coronary artery disease. However, FGF-23 has a different behaviour in the presence of type 2 diabetes mellitus (T2D). We explored whether the presence of T2D affects the predictive power of FGF-23.

METHODS

In 704 patients with stable coronary artery disease, FGF-23, calcidiol, parathormone (PTH) and phosphate plasma levels were prospectively assessed. The primary outcome was the development of acute ischemic events (acute coronary syndrome, stroke or transient ischemic attack), heart failure or death.

RESULTS

One hundred seventy-three (24.6%) patients had T2D, without differences in age, sex or estimated glomerular filtration rate as compared with non-diabetic patients. Serum PTH was lower and phosphate higher in T2D than in non-diabetic patients, without differences in FGF-23 or calcidiol levels. During follow-up (2.15 ± 0.99 years), 26 (15.2%) T2D and 51 (9.6%) non-diabetic patients developed the outcome (p = 0.048). T2D patients who developed the outcome had higher FGF-23 [112.0 (59.9, 167.6) vs 68.9 (54.2, 93.0) RU/mL; p = 0.002], PTH [71.3 (47.3, 106.6) vs 51.9 (40.8, 66.2) pg/mL; p = 0.004) and phosphate (3.53 ± 0.71 vs 3.25 ± 0.50 mg/dL; p = 0.017) levels than T2D subjects who remained stable. These differences were not significant in non-diabetic patients. By multivariable Cox proportional hazard model, FGF-23 predicted independently the outcome in T2D patients [hazard ratio = 1.277; 95% CI (1.132, 1.442)] but not in those without T2D.

CONCLUSIONS

FGF-23 plasma levels predict adverse cardiovascular outcomes in coronary artery disease patients who have T2D but not in those without T2D. This finding should be confirmed in larger studies. Copyright © 2016 John Wiley & Sons, Ltd.

The Three Sisters of Fate in Multiple Sclerosis: Klotho (Clotho), Fibroblast Growth Factor-23 (Lachesis), and Vitamin D (Atropos)

BACKGROUND

The klotho (Klt)-fibroblast growth factor-23 (FGF-23)-vitamin D axis is the main component of calcium (Ca) and phosphorus (P) metabolisms; on the contrary, it is also secreted from the choroid plexus (CP).

PURPOSE

This study is aimed at evaluating serum soluble Klt (sKlt), FGF-23, and 25-(OH)-vitamin D levels in multiple sclerosis (MS) patients.

METHODS

Thirty-two relapsing-remitting MS patients (11 males and 21 females; mean age 38.3 years) and 31 age-sex matched healthy controls (12 males and 19 females; median age 38.5 years) were included in this study. All patients were diagnosed with MS according to the criteria of McDonald.

RESULTS

Serum sKlt, FGF-23, and P levels were significantly higher in MS patients compared to the control group (p < 0.01, p < 0.01, and p = 0.02, respectively). Serum 25-(OH)-vitamin D and Ca levels were significantly lower in MS patients (p < 0.01 and p = 0.04, respectively).

CONCLUSION

Klt, which is secreted from CP, could be a response to the inflammatory condition in MS. Elevated FGF-23 levels suppress 1α-hydroxylase and upregulates 24α-hydroxylase, which results in a decrease in 1,25-(OH)₂D₃ levels. Thus, the neuroprotective and immunomodulatory effects of vitamin D might not be seen in MS patients.

Vascular calcification: When should we interfere in chronic kidney disease patients and how?

Chronic kidney disease (CKD) patients are endangered with the highest mortality rate compared to other chronic diseases. Cardiovascular events account for up to 60% of the fatalities. Cardiovascular calcifications affect most of the CKD patients. Most of this calcification is related to disturbed renal phosphate handling. Fibroblast growth factor 23 and klotho deficiency were incriminated in the pathogenesis of vascular calcification through different mechanisms including their effects on endothelium and arterial wall smooth muscle cells. In addition, deficient klotho gene expression, a constant feature of CKD, promotes vascular pathology and shares in progression of the CKD. The role of gut in the etio-pathogenesis of systemic inflammation and vascular calcification is a newly discovered mechanism. This review will cover the medical history, prevalence, pathogenesis, clinical relevance, different tools used to diagnose, the ideal timing to prevent or to withhold the progression of vascular calcification and the different medications and medical procedures that can help to prolong the survival of CKD patients.

Hypermethylation of the CaSR and VDR genes in the parathyroid glands in chronic kidney disease rats with high-phosphate diet

Chronic kidney disease (CKD) disrupts mineral homeostasis and its representative pathosis is defined as secondary hyperparathyroidism (SHPT). SHPT occurs during the early course of progressive renal insufficiency, and is associated with mortality and cardiovascular events. SHPT results in reduction of calcium-sensing receptor (CaSR) and vitamin D receptor (VDR) in the parathyroid glands during CKD. However, the precise mechanism of CaSR and VDR reduction is largely unknown. CKD was induced through two-step 5/6 nephrectomy, and then CKD rats and sham-operated rats were maintained for 8 weeks on diets containing 0.7 % phosphorus (normal phosphate) or 1.2 % phosphorus (high phosphate). In gene expression analysis, TaqMan probes were used for quantitative real-time polymerase chain reaction. Finally, CaSR and VDR protein expressions were analyzed using immunohistochemistry. DNA methylation analysis was performed using a restriction digestion and quantitative PCR. CaSR and VDR mRNA were reduced only in CKD rats fed the high-phosphorus diets (CKD HP), then CaSR and VDR immunohistochemical expressions were compatible with gene expression assay. SHPT was then confirmed only in CKD HP rats. Furthermore, sole CKD HP rats showed the hypermethylation in CaSR and VDR genes; however, the percentage methylation of both genes was low. Although CaSR and VDR hypermethylation was demonstrated in PTGs of CKD HP rats, the extent of hypermethylation was insufficient to support the relevance between hypermethylation and down-regulation of gene expression because of the low percentage of methylation. Consequently, our data suggest that mechanisms, other than DNA hypermethylation, were responsible for the reduction in mRNA and protein levels of CaSR and VDR in PTGs of CKD HP rats.

Interorgan handling of fibroblast growth factor-23 in humans

Fibroblast growth factor-23 (FGF-23) accumulates in blood of patients with chronic kidney disease (CKD) and is associated both with cardiovascular complications and disease progression. However, our knowledge of the sites and mechanisms that regulate plasma FGF-23 is still incomplete. We measured plasma intact FGF-23 across the kidney, splanchnic organs, and lung in 11 patients [estimated glomerular filtration rate (eGFR) 60 ± 6 ml/min] during elective diagnostic cardiac catheterizations. In these patients FGF-23 was removed by the kidney, with a fractional extraction (FE) of ∼22%. The FE of FGF-23 across the kidney was similar to that of creatinine (∼17%, P = NS). In addition, the FGF-23 FE by the kidney was significantly directly related to eGFR (r = 0.709 P = 0.018) and to kidney creatinine FE (r = 0.736 P = 0.013) but only as a trend to plasma phosphate levels (r = 0.55, P = 0.18). There was no difference in FGF-23 levels in blood perfusing splanchnic organs and cardiopulmonary bed. However, the arterial-venous difference of FGF-23 across the lung was directly related to FGF-23 pulmonary artery levels, suggesting that the lung, and possibly the heart, participate in the homeostasis of plasma FGF-23 when its systemic levels are increased. Our data show that the human kidney is the only site for FGF-23 removal from blood and suggest that FGF-23 is predominantly removed by glomerular filtration. The kidney ability to remove FGF-23 from the circulation likely accounts for the early increase in blood of FGF-23 in patients with CKD.

Sclerostin, TNF-alpha and Interleukin-18 Correlate and are Together with Klotho Related to Other Growth Factors and Cytokines in Haemodialysis Patients

Patients with chronic renal failure are known to have renal osteodystrophy (bone disease) and increased calcification of vessels. A new marker of bone disease, sclerostin, the two pro-inflammatory cytokines tumour necrosis factor-alpha (TNF-alpha) and interleukin-18 (IL-18), and the fibroblast growth factor-23 (FGF-23) receptor-associated marker Klotho were tested in 84 haemodialysis (HD) patients and in healthy controls. The patients had significantly higher levels of the three former markers than of the controls while Klotho was significantly higher in the controls. Low level, but significant, correlations were observed in the patient group when the levels of these four markers were compared to each other and to those of 5 cytokines and growth factors tested earlier; high-sensitive CRP (hsCRP), interleukin-6 (IL-6), hepatocyte growth factor (HGF), fibroblast growth factor-23 (FGF-23) and soluble urokinase plasminogen activator (suPAR). Ln sclerostin correlated positively to Ln hsTNF-alpha, Ln HGF and Ln suPAR. Ln hsTNF-alpha correlated positively to Ln sclerostin, Ln hsCRP, Ln IL-6, Ln FGF-23, Ln suPAR and Ln IL-18. Ln IL-18 correlated positively to Ln suPAR and Ln TNF-alpha. Ln Klotho correlated negatively to Ln hsCRP but did not correlate to Ln FGF-23. The markers studied here may be involved in the calcification of vessels seen in HD patients due to a combination of inflammation and bone disease. The mechanisms are still not fully known but may be of importance for future therapeutic possibilities in this group of patients.

New Insights into the Molecular Mechanisms Targeting Tubular Channels/Transporters in PKD Development

BACKGROUND

Autosomal dominant polycystic kidney disease (PKD) or autosomal recessive PKD is caused by a mutation in the PKD1, PKD2 or PKHD1 gene, which encodes polycystin-1, polycystin-2 or fibrocystin, respectively. Embryonic and postnatal mutation studies show that transport or channel function is dysregulated before the initiation of cystogenesis, suggesting that the abnormality of transport or channel function plays a critical role in the pathology of PKD.

SUMMARY

Polycystin-2 by itself is a calcium-permeable cation channel, and its channel function can be regulated by polycystin-1 or fibrocystin. In this paper, we reviewed the current knowledge about calcium transports and cyclic adenosine monophosphate (cAMP)-driven chloride transports in PKD. In addition, the function and the underlining mechanism of glucose transporters, phosphate transporters and water channels in PKD are also discussed.

KEY MESSAGES

Abnormalities in calcium handling and exuberant cAMP-dependent cystic fibrosis transmembrane conductance regulator-mediated fluid secretion in the collecting duct are the most important issues in the pathogenesis of PKD.

Iron-based phosphate binders--a new element in management of hyperphosphatemia

INTRODUCTION

Management of serum phosphorus in patients with chronic kidney disease remains a significant clinical challenge. A pivotal component of the clinical approach to maintaining serum phosphorus concentrations towards the normal range is the use of phosphate binding agents in addition to comprehensive dietary counseling. The available agents work similarly by capitalizing on a cation within the agent to bind negatively charged phosphorus, forming an insoluble complex and reducing ingested phosphorus absorption. Despite several effective options for phosphate binder therapies, patient adherence remains an issue, mainly due to adverse effect profiles and large daily pill burdens.

AREAS COVERED

Two new iron-based phosphate binder therapies have recently become available in the United States, sucroferric oxyhydroxide and ferric citrate. These agents have both been shown to effectively reduce serum phosphorus comparably to widely used calcium-based binders and sevelamer salts.

EXPERT OPINION

The two new iron-based binders differ substantially with regard to phosphate binding chemistry and iron absorption profiles. Their place in therapy is still evolving and the impact of pill burden, gastrointestinal adverse effect profiles, potential cost reduction of anemia therapies and physiologic effects of long-term iron exposure need to be further evaluated.

Deregulated Renal Calcium and Phosphate Transport during Experimental Kidney Failure

Impaired mineral homeostasis and inflammation are hallmarks of chronic kidney disease (CKD), yet the underlying mechanisms of electrolyte regulation during CKD are still unclear. Here, we applied two different murine models, partial nephrectomy and adenine-enriched dietary intervention, to induce kidney failure and to investigate the subsequent impact on systemic and local renal factors involved in Ca(2+) and Pi regulation. Our results demonstrated that both experimental models induce features of CKD, as reflected by uremia, and elevated renal neutrophil gelatinase-associated lipocalin (NGAL) expression. In our model kidney failure was associated with polyuria, hypercalcemia and elevated urinary Ca(2+) excretion. In accordance, CKD augmented systemic PTH and affected the FGF23-αklotho-vitamin-D axis by elevating circulatory FGF23 levels and reducing renal αklotho expression. Interestingly, renal FGF23 expression was also induced by inflammatory stimuli directly. Renal expression of Cyp27b1, but not Cyp24a1, and blood levels of 1,25-dihydroxy vitamin D3 were significantly elevated in both models. Furthermore, kidney failure was characterized by enhanced renal expression of the transient receptor potential cation channel subfamily V member 5 (TRPV5), calbindin-D28k, and sodium-dependent Pi transporter type 2b (NaPi2b), whereas the renal expression of sodium-dependent Pi transporter type 2a (NaPi2a) and type 3 (PIT2) were reduced. Together, our data indicates two different models of experimental kidney failure comparably associate with disturbed FGF23-αklotho-vitamin-D signalling and a deregulated electrolyte homeostasis. Moreover, this study identifies local tubular, possibly inflammation- or PTH- and/or FGF23-associated, adaptive mechanisms, impacting on Ca(2+)/Pi homeostasis, hence enabling new opportunities to target electrolyte disturbances that emerge as a consequence of CKD development.

Elevated Fibroblast Growth Factor 23 Concentration: Prediction of Mortality among Chronic Kidney Disease Patients

BACKGROUND

The osteocyte-derived hormone, fibroblast growth factor 23 (FGF23), regulates the phosphorus metabolism and suppresses 1,25-dihydroxyvitamin D production, thereby mitigating hyperphosphatemia in patients with renal disorders. An elevated FGF23 level is suggested to be an early biomarker of altered phosphorus metabolism in the initial stages of chronic kidney disease (CKD) and acts as a strong predictor of mortality in dialysis patients. In the Saudi population, there is no report on the FGF23 level in CKD patients to date. This study aims to estimate the plasma FGF23 levels in the Saudi population and to correlate it with its clinical manifestations in order to ascertain its role in the pathogenesis of CKD patients.

METHODS

The FGF23 level in the plasma samples was determined using ELISA in a diverse cohort of 89 cases with stage 3-5 CKD and 100 healthy subjects. The plasma FGF23 level was correlated with other biochemical parameters.

RESULTS

The results revealed that the FGF23 level was markedly elevated among CKD patients compared to the control group, and a significant inverse correlation was observed between the FGF23 level and glomerular filtration rate. FGF23 elevation was approximately 40-fold among stage 5 patients compared to the control, while the elevation of phosphate, parathyroid hormone (PTH) and alkaline phosphatase was 2-, 3- and 8-fold in this stage, respectively.

CONCLUSION

Elevated FGF23 levels may have a strong correlation with the disease pathogenesis. In addition, FGF23 might be a future therapeutic target to intervene against the progression of CKD as well as to increase patient survivability.

From variome to phenome: Pathogenesis, diagnosis and management of ectopic mineralization disorders

Ectopic mineralization - inappropriate biomineralization in soft tissues - is a frequent finding in physiological aging processes and several common disorders, which can be associated with significant morbidity and mortality. Further, pathologic mineralization is seen in several rare genetic disorders, which often present life-threatening phenotypes. These disorders are classified based on the mechanisms through which the mineralization occurs: metastatic or dystrophic calcification or ectopic ossification. Underlying mechanisms have been extensively studied, which resulted in several hypotheses regarding the etiology of mineralization in the extracellular matrix of soft tissue. These hypotheses include intracellular and extracellular mechanisms, such as the formation of matrix vesicles, aberrant osteogenic and chondrogenic signaling, apoptosis and oxidative stress. Though coherence between the different findings is not always clear, current insights have led to improvement of the diagnosis and management of ectopic mineralization patients, thus translating pathogenetic knowledge (variome) to the phenotype (phenome). In this review, we will focus on the clinical presentation, pathogenesis and management of primary genetic soft tissue mineralization disorders. As examples of dystrophic calcification disorders Pseudoxanthoma elasticum, Generalized arterial calcification of infancy, Keutel syndrome, Idiopathic basal ganglia calcification and Arterial calcification due to CD73 (NT5E) deficiency will be discussed. Hyperphosphatemic familial tumoral calcinosis will be reviewed as an example of mineralization disorders caused by metastatic calcification.