Bone markers predict cardiovascular events in chronic kidney disease

Advanced glycosylation end products promote the progression of CKD-MBD in rats, and its natural inhibitor, quercetin, mitigates disease progression

Chronic kidney disease-mineral and bone metabolism disorder (CKD-MBD) is a common chronic kidney disease (CKD)-associated complication that increases the risk of metabolic bone diseases, fractures, osteoblastic trans-differentiation of vascular smooth muscle cells, and cardiovascular events. SD rats were randomised into five groups with six rats per group: sham, CKD, CKD + advanced glycosylation end products (AGEs), CKD + Quercetin, and CKD + AGEs + Quercetin. The protective effects of AGEs and quercetin on SD rats were assessed by renal function, renal pathology, bone metabolism, osteoblastic trans-differentiation of vascular smooth muscle cells, and the receptor for AGE (RAGE) expression. Compared with the control group, rats in the CKD and CKD + AGEs groups had significantly lower body weight, higher serum AGEs levels, impaired renal function, increased levels of oxidative stress in the kidney and bone marrow tissues, lower femoral bone mineral density (BMD), callus mineralised volume fraction (mineralised bone volume/total volume), abnormal serum bone metabolism levels, and increased renal tissue, bone tissue, and abdominal aorta RAGE expression levels, and the RAGE downstream NF-κB signalling pathway was upregulated. Quercetin significantly improved renal dysfunction, attenuated serum AGE levels, reduced oxidative stress levels in the kidney and bone marrow tissues, and downregulated RAGE expression in the kidney, bone, and abdominal aorta and the RAGE downstream NF-κB signalling pathway in rats with CKD. AGEs are involved in the pathogenesis of CKD-MBD by promoting osteoblastic trans-differentiation of vascular smooth muscle cells and abnormal bone metabolism. Quercetin plays a role in the prevention and treatment of CKD-MBD by reducing the production of AGEs.

Machine learning for identification of short-term all-cause and cardiovascular deaths among patients undergoing peritoneal dialysis

Although more and more cardiovascular risk factors have been verified in peritoneal dialysis (PD) populations in different countries and regions, it is still difficult for clinicians to accurately and individually predict death in the near future. We aimed to develop and validate machine learning-based models to predict near-term all-cause and cardiovascular death. Machine learning models were developed among 7539 PD patients, which were randomly divided into a training set and an internal test set by five random shuffles of 5-fold cross-validation, to predict the cardiovascular death and all-cause death in 3 months. We chose objectively collected markers such as patient demographics, clinical characteristics, laboratory data, and dialysis-related variables to inform the models and assessed the predictive performance using a range of common performance metrics, such as sensitivity, positive predictive values, the area under the receiver operating curve (AUROC), and the area under the precision recall curve. In the test set, the CVDformer models had a AUROC of 0.8767 (0.8129, 0.9045) and 0.9026 (0.8404, 0.9352) and area under the precision recall curve of 0.9338 (0.8134,0.9453) and 0.9073 (0.8412, 0.9164) in predicting near-term all-cause death and cardiovascular death, respectively. The CVDformer models had high sensitivity and positive predictive values for predicting all-cause and cardiovascular deaths in 3 months in our PD population. Further calibration is warranted in the future.

Association of mineral and bone biomarkers with adverse cardiovascular outcomes and mortality in the German Chronic Kidney Disease (GCKD) cohort

Mineral and bone disorder (MBD) in chronic kidney disease (CKD) is tightly linked to cardiovascular disease (CVD). In this study, we aimed to compare the prognostic value of nine MBD biomarkers to determine those associated best with adverse cardiovascular (CV) outcomes and mortality. In 5 217 participants of the German CKD (GCKD) study enrolled with an estimated glomerular filtration rate (eGFR) between 30-60 mL·min-1 per 1.73 m2 or overt proteinuria, serum osteoprotegerin (OPG), C-terminal fibroblast growth factor-23 (FGF23), intact parathyroid hormone (iPTH), bone alkaline phosphatase (BAP), cross-linked C-telopeptide of type 1 collagen (CTX1), procollagen 1 intact N-terminal propeptide (P1NP), phosphate, calcium, and 25-OH vitamin D were measured at baseline. Participants with missing values among these parameters (n = 971) were excluded, leaving a total of 4 246 participants for analysis. During a median follow-up of 6.5 years, 387 non-CV deaths, 173 CV deaths, 645 nonfatal major adverse CV events (MACEs) and 368 hospitalizations for congestive heart failure (CHF) were observed. OPG and FGF23 were associated with all outcomes, with the highest hazard ratios (HRs) for OPG. In the final Cox regression model, adjusted for CV risk factors, including kidney function and all other investigated biomarkers, each standard deviation increase in OPG was associated with non-CV death (HR 1.76, 95% CI: 1.35-2.30), CV death (HR 2.18, 95% CI: 1.50-3.16), MACE (HR 1.38, 95% CI: 1.12-1.71) and hospitalization for CHF (HR 2.05, 95% CI: 1.56-2.69). Out of the nine biomarkers examined, stratification based on serum OPG best identified the CKD patients who were at the highest risk for any adverse CV outcome and mortality.

[Diagnosis and treatment of osteoporosis in patients with chronic kidney disease : Joint guidelines of the Austrian Society for Bone and Mineral Research (ÖGKM), the Austrian Society of Physical and Rehabilitation Medicine (ÖGPMR) and the Austrian Society of Nephrology (ÖGN)]

DEFINITION AND EPIDEMIOLOGY

Chronic kidney disease (CKD): abnormalities of kidney structure or function, present for over 3 months. Staging of CKD is based on GFR and albuminuria (not graded). Osteoporosis: compromised bone strength (low bone mass, disturbance of microarchitecture) predisposing to fracture. By definition, osteoporosis is diagnosed if the bone mineral density T‑score is ≤ -2.5. Furthermore, osteoporosis is diagnosed if a low-trauma (inadequate trauma) fracture occurs, irrespective of the measured T‑score (not graded). The prevalence of osteoporosis, osteoporotic fractures and CKD is increasing worldwide (not graded). PATHOPHYSIOLOGY, DIAGNOSIS AND TREATMENT OF CHRONIC KIDNEY DISEASE-MINERAL AND BONE DISORDER (CKD-MBD): Definition of CKD-MBD: a systemic disorder of mineral and bone metabolism due to CKD manifested by either one or a combination of the following: abnormalities of calcium, phosphorus, PTH, or vitamin D metabolism; renal osteodystrophy; vascular calcification (not graded). Increased, normal or decreased bone turnover can be found in renal osteodystrophy (not graded). Depending on CKD stage, routine monitoring of calcium, phosphorus, alkaline phosphatase, PTH and 25-OH-vitamin D is recommended (2C). Recommendations for treatment of CKD-MBD: Avoid hypercalcemia (1C). In cases of hyperphosphatemia, lower phosphorus towards normal range (2C). Keep PTH within or slightly above normal range (2D). Vitamin D deficiency should be avoided and treated when diagnosed (1C).

DIAGNOSIS AND RISK STRATIFICATION OF OSTEOPOROSIS IN CKD

Densitometry (using dual X‑ray absorptiometry, DXA): low T‑score correlates with increased fracture risk across all stages of CKD (not graded). A decrease of the T‑score by 1 unit approximately doubles the risk for osteoporotic fracture (not graded). A T-score ≥ -2.5 does not exclude osteoporosis (not graded). Bone mineral density of the lumbar spine measured by DXA can be increased and therefore should not be used for the diagnosis or monitoring of osteoporosis in the presence of aortic calcification, osteophytes or vertebral fracture (not graded). FRAX can be used to aid fracture risk estimation in all stages of CKD (1C). Bone turnover markers can be measured in individual cases to monitor treatment (2D). Bone biopsy may be considered in individual cases, especially in patients with CKD G5 (eGFR < 15 ml/min/1.73 m2) or CKD 5D (dialysis).

SPECIFIC TREATMENT OF OSTEOPOROSIS IN PATIENTS WITH CKD

Hypocalcemia should be treated and serum calcium normalized before initiating osteoporosis therapy (1C). CKD G1-G2 (eGFR ≥ 60 ml/min/1.73 m2): treat osteoporosis as recommended for the general population (1A). CKD G3-G5D (eGFR < 60 ml/min/1.73 m2 to dialysis): treat CKD-MBD first before initiating osteoporosis treatment (2C). CKD G3 (eGFR 30-59 ml/min/1.73 m2) with PTH within normal limits and osteoporotic fracture and/or high fracture risk according to FRAX: treat osteoporosis as recommended for the general population (2B). CKD G4-5 (eGFR < 30 ml/min/1.73 m2) with osteoporotic fracture (secondary prevention): Individualized treatment of osteoporosis is recommended (2C). CKD G4-5 (eGFR < 30 ml/min/1.73 m2) and high fracture risk (e.g. FRAX score > 20% for a major osteoporotic fracture or > 5% for hip fracture) but without prevalent osteoporotic fracture (primary prevention): treatment of osteoporosis may be considered and initiated individually (2D). CKD G4-5D (eGFR < 30 ml/min/1.73 m2 to dialysis): Calcium should be measured 1-2 weeks after initiation of antiresorptive therapy (1C).

PHYSICAL MEDICINE AND REHABILITATION

Resistance training prioritizing major muscle groups thrice weekly (1B). Aerobic exercise training for 40 min four times per week (1B). Coordination and balance exercises thrice weekly (1B). Flexibility exercise 3-7 times per week (1B).

Differential bone remodeling mechanism in hindlimb unloaded and hibernating Daurian ground squirrels: a comparison between artificial and natural disuse within the same species

Loss of bone mass can occur in mammals after prolonged disuse but the situation for hibernators that are in a state of torpor for many months of the year is not yet fully understood. The present study assesses the bone remodeling mechanisms present in Daurian ground squirrels (Spermophilus dauricus) during hibernation as compared with a model of hindlimb disuse. Differences in microstructure, mechanical properties, bone remodeling-related proteins (Runx2, OCN, ALP, RANKL, CTK and MMP-9) and key proteins of Wnt/β-catenin signaling pathway (GSK-3β and phospho-β-catenin) were evaluated in ground squirrels under 3 conditions: summer active (SA) vs. hibernation (HIB) vs. hindlimb unloaded (HLU). The results indicated that the body weight in HLU ground squirrels was lower than the SA group, and the middle tibia diameter in the HLU group was lower than that in SA and HIB groups. The thickness of cortical and trabecular bone in femurs from HLU ground squirrels was lower than in SA and HIB groups. Most parameters of the tibia in the HLU group were lower than those in SA and HIB groups, which indicated cortical bone loss in ground squirrels. Moreover, our data showed that the changes in microscopic parameters in the femur were more obvious than those in the tibia in HLU and HIB ground squirrels. The levels of Runx2 and ALP were lower in HLU ground squirrels than SA and HIB groups. The protein levels of OCN were unchanged in the three groups, but the protein levels of ALP were lower in the HLU group than in SA and HIB groups. RANKL, CTK and MMP-9 protein levels were significantly decreased in tibia of HLU ground squirrels as compared with SA and HIB groups. In addition, the protein expression levels of RANKL, CTK and MMP-9 showed no statistical difference between SA and HIB ground squirrels. Thus, the mechanisms involved in the balance between bone formation and resorption in hibernating and hindlimb unloading ground squirrels may be different. The present study showed that in femur, the Wnt signaling pathway was inhibited, the protein level of GSK-3β was increased, and the protein expression of phospho-β-catenin was decreased in the HIB group as compared with the SA group, which indicates that the Wnt signaling pathway has a great influence on the femur of the HIB group. In conclusion, the natural anti-osteoporosis properties of Daurian ground squirrels are seasonal. The squirrels do not experience bone loss when they are inactive for a long time during hibernation, but the mechanisms of anti-osteoporosis did not work in HLU summer active squirrels.

Bone adaptation and osteoporosis prevention in hibernating mammals

Hibernating bears and rodents have evolved mechanisms to prevent disuse osteoporosis during the prolonged physical inactivity that occurs during hibernation. Serum markers and histological indices of bone remodeling in bears indicate reduced bone turnover during hibernation, which is consistent with organismal energy conservation. Calcium homeostasis is maintained by balanced bone resorption and formation since hibernating bears do not eat, drink, urinate, or defecate. Reduced and balanced bone remodeling protect bear bone structure and strength during hibernation, unlike the disuse osteoporosis that occurs in humans and other animals during prolonged physical inactivity. Conversely, some hibernating rodents show varying degrees of bone loss such as osteocytic osteolysis, trabecular loss, and cortical thinning. However, no negative effects of hibernation on bone strength in rodents have been found. More than 5000 genes in bear bone tissue are differentially expressed during hibernation, highlighting the complexity of hibernation induced changes in bone. A complete picture of the mechanisms that regulate bone metabolism in hibernators still alludes us, but existing data suggest a role for endocrine and paracrine factors such as cocaine- and amphetamine-regulated transcript (CART) and endocannabinoid ligands like 2-arachidonoyl glycerol (2-AG) in decreasing bone remodeling during hibernation. Hibernating bears and rodents evolved the capacity to preserve bone strength during long periods of physical inactivity, which contributes to their survival and propagation by allowing physically activity (foraging, escaping predators, and mating) without risk of bone fracture following hibernation. Understanding the biological mechanisms regulating bone metabolism in hibernators may inform novel treatment strategies for osteoporosis in humans.

Alkaline Phosphatase: An Old Friend as Treatment Target for Cardiovascular and Mineral Bone Disorders in Chronic Kidney Disease

Alkaline phosphatase (ALP) is an evolutionary conserved enzyme and widely used biomarker in clinical practice. Tissue-nonspecific alkaline phosphatase (TNALP) is one of four human isozymes that are expressed as distinct TNALP isoforms after posttranslational modifications, mainly in bone, liver, and kidney tissues. Beyond the well-known effects on bone mineralization, the bone ALP (BALP) isoforms (B/I, B1, B1x, and B2) are also involved in the pathogenesis of ectopic calcification. This narrative review summarizes the recent clinical investigations and mechanisms that link ALP and BALP to inflammation, metabolic syndrome, vascular calcification, endothelial dysfunction, fibrosis, cardiovascular disease, and mortality. The association between ALP, vitamin K, bone metabolism, and fracture risk in patients with chronic kidney disease (CKD) is also discussed. Recent advances in different pharmacological strategies are highlighted, with the potential to modulate the expression of ALP directly and indirectly in CKD–mineral and bone disorder (CKD-MBD), e.g., epigenetic modulation, phosphate binders, calcimimetics, vitamin D, and other anti-fracture treatments. We conclude that the significant evidence for ALP as a pathogenic factor and risk marker in CKD-MBD supports the inclusion of concrete treatment targets for ALP in clinical guidelines. While a target value below 120 U/L is associated with improved survival, further experimental and clinical research should explore interventional strategies with optimal risk–benefit profiles. The future holds great promise for novel drug therapies modulating ALP.

Low Turnover Renal Osteodystrophy With Abnormal Bone Quality and Vascular Calcification in Patients With Mild-to-Moderate CKD

Introduction

Limited information is available on renal osteodystrophy (ROD) and vascular calcification (VC) during early chronic kidney disease (CKD). This study was designed to evaluate ROD and VC in 32 patients with CKD stages II to IV.

Methods

Patients underwent dual-energy X-ray absorptiometry (DXA) for assessment of bone mineral density (BMD) and trabecular bone score (TBS), thoracic computed tomography for VC scoring using the Agatston method, and anterior iliac crest bone biopsy for mineralized bone histology, histomorphometry, and Fourier transform infrared spectroscopy (FTIR). Classical and novel bone markers were determined in the blood.

Results

Mean estimated glomerular filtration rate (eGFR) was 44 ± 16 ml/min per 1.73 m2. Of the patients, 84% had low bone turnover. In Whites, eGFR correlated negatively with the turnover parameter activation frequency (Ac.f) (r -0.48, P = 0.019) and with parameters of bone formation. Most patients had VC (>80%) which correlated positively with levels of phosphorus, c-terminal fibroblast growth factor-23, and activin. Aortic calcifications (ACs) correlated negatively with bone formation rate (BFR) and Ac.f (rho -0.62, -0.61, P < 0.001). TBS correlated negatively with coronary calcification (rho -0.42, P = 0.019) and AC (rho -0.57, P = 0.001). These relationships remained after adjustment of age. The mineral-to-matrix ratio, an FTIR metric reflecting bone quality, was negatively related to Ac.f and positively related to AC.

Conclusion

Low bone turnover and VC are predominant in early stages of CKD. This is the first study demonstrating mineral abnormalities indicating reduced bone quality in these stages of CKD.

Usefulness of the trabecular bone score in maintenance dialysis patients : A single center observational study

Background

The number of dialysis patients is steadily increasing. Associated comorbidities include impaired bone and mineral metabolism, termed chronic kidney disease-mineral and bone disorder (CKD-MBD), leading to a high fracture risk, increased morbidity and mortality and impaired quality of life. While the bone density is assessed with dual-energy X‑ray absorptiometry (DXA), the trabecular bone score (TBS) captures the image texture as a potential index of skeletal microarchitecture. The aim of this study was to evaluate the clinical relevance of DXA and TBS in dialysis patients with and without prevalent fractures.

Methods

Bone disorders were evaluated in 82 dialysis patients (37% female) at the University Hospital of Graz, Austria, by DXA including the assessment of the TBS based on a patient interview and the local routine patient database software. The patient cohort was stratified by having sustained a fragility fracture in the past or not. Descriptive statistics, t‑tests for continuous variables and χ²-tests for nominal variables including results of DXA and TBS were performed to compare these groups considering the dialysis modality and duration as well as the number of kidney transplantations.

Results

Of the 82 patients, 32 (39%) had a positive history of fractures. There was a significant association between dialysis duration and fracture prevalence (p < 0.05) as well as musculoskeletal pain (p < 0.01). No significant correlation between DXA/TBS parameters and musculoskeletal pain could be established. The DXA scores did not correlate with fracture prevalence with the exception of DXA radius measurements; however, fracture prevalence significantly correlated inversely with TBS (p < 0.001).

Conclusion

The use of DXA has a limited role in fracture prediction in dialysis patients; however, the TBS seems to add information as an additional tool for fracture risk estimation in this patient population.

An open-label phase 2 trial to assess the efficacy, safety and pharmacokinetics of lanthanum carbonate in hyperphosphatemic children and adolescents with chronic kidney disease undergoing dialysis

BACKGROUND

This study assessed the efficacy, tolerability and pharmacokinetics (PK) of lanthanum carbonate (LC) in hyperphosphatemic children and adolescents with chronic kidney disease (CKD) undergoing dialysis.

METHODS

This was a three-part, multicenter, open-label study of LC (oral powder formulation) in patients 10 to < 18 years old with CKD undergoing dialysis. In part 1, the single-dose PK of LC (500 mg, ≤12 years old; 1000 mg, > 12 years old) were summarized. In part 2, patients received calcium carbonate (CC [chewable tablet formulation]) (1500-6500 mg [total daily dose]) followed by LC (powder formulation) (1500-3000 mg [total daily dose]), or LC only (1500-3000 mg [total daily dose]), each for 8 weeks. During part 3, patients received LC (1500-3000 mg [total daily dose]) for up to 6 months. The primary efficacy endpoint was the proportion of LC-treated patients achieving serum phosphorus control after 8 weeks during parts 2 and/or 3, defined as: ≤1.94 mmol/L, < 12 years old; ≤1.78 mmol/L, ≥12 years old. Secondary efficacy endpoints included: the proportion of patients who achieved serum phosphorus control after 8 weeks of treatment with CC followed by 8 weeks of treatment with LC (with a washout period between treatments). The safety of LC and CC was also evaluated.

RESULTS

In part 1, 20 patients received a single dose of LC. In part 2, 53 and 51 patients were treated with CC and LC for 8 weeks, respectively. During part 3, 42 patients received LC for up to 6 months. Most patients were white and male. For the primary efficacy endpoint, 50% (17/34) of patients who received LC for 8 weeks during parts 2 and/or 3 achieved serum phosphorus control. After 8 weeks of treatment with CC, 58.8% of patients achieved serum phosphorus control; after a subsequent washout period and 8 weeks of treatment with LC, 70.6% of patients achieved serum phosphorus control. T_max and t_1/2 occurred within 3-8 h and ~ 19 h, respectively; however, variability was observed. LC and CC were generally well tolerated.

CONCLUSIONS

These data support the use of LC to manage hyperphosphatemia in pediatric patients with CKD undergoing dialysis.

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT01696279; EudraCT identifier: 2012-000171-17. Date of registration: 01/10/2012.

Evocalcet with vitamin D receptor activator treatment for secondary hyperparathyroidism

This ad hoc analysis of a previously conducted phase 3 head-to-head comparison study of evocalcet and cinacalcet in secondary hyperparathyroidism patients undergoing maintenance hemodialysis evaluated the efficacy and safety of combined once-daily oral evocalcet and intravenous vitamin D receptor activator treatment stratified by weekly vitamin D receptor activator dose (117, 45, and 91 patients in no, low [< 1.5 μg], and high [≥ 1.5 μg] dose groups, respectively). Effects of vitamin D receptor activator were assessed on the basis of intact parathyroid hormone, corrected calcium, phosphorus, and fibroblast growth factor-23 levels; percent changes from baseline; proportions of patients who achieved target intact parathyroid hormone, corrected calcium, and phosphorus at Weeks 28–30; and adverse drug reactions. Intact parathyroid hormone, corrected calcium, phosphorus, and fibroblast growth factor-23 levels decreased in all groups; phosphorus and fibroblast growth factor-23 levels remained high in the high dose group. In the low and high dose groups, greater proportions of patients achieved the corrected calcium target compared with the no dose group (p = 0.043). Ratios of intact-to-C-terminal fibroblast growth factor-23 decreased in all groups. In low and high dose groups, hypocalcemia was less common than in the no dose group (p = 0.014). Evocalcet with concomitant vitamin D receptor activator demonstrated benefits such that more patients achieved the corrected calcium target and exhibited decreased fibroblast growth factor-23 synthesis; the incidence of hypocalcemia also decreased.

Clinical trial registration: ClinicalTrials.gov (NCT02549391) and JAPIC (JapicCTI-153013).

Educational Attainment Is Associated With Kidney and Cardiovascular Outcomes in CKD

Introduction

Prospective data on impact of educational attainment on prognosis in patients with chronic kidney disease (CKD) are scarce. We investigated the association between educational attainment and all-cause mortality, major adverse cardiovascular (CV) events (MACEs), kidney failure requiring dialysis, and CKD etiology.

Methods

Participants (N = 5095, aged 18–74 years) of the ongoing multicenter German Chronic Kidney Disease (GCKD) cohort, enrolled on the basis of an estimated glomerular filtration rate (eGFR) of 30 to 60 ml/min (stages G3, A1–A3) or overt proteinuria (stages G1–G2, A3), were divided into 3 categories according to their educational attainment and were followed for 6.5 years.

Results

Participants with low educational attainment (vs. high) had a higher risk for mortality (hazard ratio [HR] 1.48, 95% CI: 1.16–1.90), MACE (HR 1.37, 95% CI: 1.02–1.83), and kidney failure (HR 1.54, 95% CI: 1.15–2.05). Mediators between low educational attainment and mortality were smoking, CV disease (CVD) at baseline, low income, higher body mass index, and higher serum levels of CRP, high-density lipoprotein cholesterol, uric acid, NGAL, BAP, NT-proBNP, OPN, H-FABP, and urea. Low educational attainment was positively associated with diabetic nephropathy (odds ratio [OR] 1.65, 95% CI: 1.36–2.0) and CKD subsequent to acute kidney injury (OR 1.56, 95% CI: 1.03–2.35), but negatively associated with IgA nephropathy (OR 0.68, 95% CI: 0.52–0.90).

Conclusion

Low educational attainment is associated with adverse outcomes and CKD etiology. Lifestyle habits and biomarkers mediate associations between low educational attainment and mortality. Recognition of the role of educational attainment and the associated health-relevant risk factors is important to optimize the care of patients with CKD and improve prognosis.

Efficacy of Evocalcet in Previously Cinacalcet-Treated Secondary Hyperparathyroidism Patients

Introduction

Evocalcet is a recently approved calcimimetic agent for secondary hyperparathyroidism (SHPT). In this study, the efficacy and safety of once-daily oral evocalcet were evaluated in patients without prior cinacalcet use (nonusers) and previously treated patients (users).

Methods

This post hoc analysis of a previous phase III head-to-head comparison study included SHPT patients treated with evocalcet with or without prior cinacalcet use. Endpoints included trends in the median intact and whole parathyroid hormone (PTH), mean corrected calcium, phosphate, and bone metabolic markers, and whole-to-intact PTH ratios throughout the 30-week study period; proportions of patients achieving target intact PTH, corrected calcium, and phosphate at weeks 28 to 30; and adverse drug reactions (ADRs).

Results

This study included 127 nonusers and 190 users with significant differences in age; duration of dialysis; use of intravenous vitamin D receptor activators; levels of intact PTH, corrected calcium, tartrate-resistant acid phosphatase 5b, procollagen type 1 N-terminal-propeptide; and largest parathyroid gland volume (P < 0.05 for all characteristics) between 2 groups at baseline. Users required higher evocalcet dosages than nonusers. Similar efficacy results were found in the 2 groups except for a significantly higher proportion of nonusers achieving the intact PTH target (81.6% vs 67.1%, difference [95% confidence interval], −14.5% [−24.59, −3.34]), and a significant reduction in largest parathyroid gland volume from week 0 to week 30 (−120.6 [567.2] mm³, P = 0.043). No difference was found in ADRs between the 2 groups.

Conclusion

Treatment with evocalcet is effective and safe irrespective of prior cinacalcet treatment in SHPT patients.

Differentiating the causes of adynamic bone in advanced chronic kidney disease informs osteoporosis treatment

Patients with chronic kidney disease (CKD) have an increased fracture risk because of impaired bone quality and quantity. Low bone mineral density predicts fracture risk in all CKD stages, including advanced CKD (CKD G4-5D). Pharmacological therapy improves bone mineral density and reduces fracture risk in moderate CKD. Its efficacy in advanced CKD remains to be determined, although pilot studies suggest a positive effect on bone mineral density. Currently, antiresorptive agents are the most commonly prescribed drugs for the prevention and therapy of osteoporosis. Their use in advanced CKD has been limited by the lack of large clinical trials and fear of causing kidney dysfunction and adynamic bone disease. In recent decades, adynamic bone disease has evolved as the most predominant form of renal osteodystrophy, commonly associated with poor outcomes, including premature mortality and progression of vascular calcification. Evolving evidence indicates that reduction of bone turnover by parathyroidectomy or pharmacological therapies, such as calcimimetics and antiresorptive agents, are not associated with premature mortality or accelerated vascular calcification in CKD. In contrast, chronic inflammation, oxidative stress, malnutrition, and diabetes can induce low bone turnover and associate with poor prognosis. Thus, the conditions causing suppression of bone turnover rather than the low bone turnover per se may account for the perceived association with outcomes. Anabolic treatment, in contrast, has been suggested to improve turnover and bone mass in patients with advanced CKD and low bone turnover; however, uncertainty about safety even exceeds that of antiresorptive agents. Here, we critically review the pathophysiological concept of adynamic bone disease and discuss the effect of low bone turnover on the safety and efficacy of anti-osteoporosis pharmacotherapy in advanced CKD.

Differential bone remodeling mechanism in hindlimb unloaded rats and hibernating Daurian ground squirrels: a comparison between artificial and natural disuse

To determine that differential bone remodeling mechanism (especially Wnt signaling) in hindlimb unloaded rats and hibernating Daurian ground squirrels, the bone microstructure, mechanical properties, and expression levels of bone remodeling related proteins and key proteins of Wnt/β-catenin signaling were analyzed in this study. The thickness of cortical and trabecular bone was decreased in femur of hindlimb unloaded rats, while it was maintained in femur of hibernating ground squirrels. Interestingly, the ultimate bending energy and ultimate normalized displacement were reduced and the bending rigidity was increased in tibia of hibernating ground squirrels. Besides, the protein level of Runx2 was decreased in femur and tibia of unloaded rats, while it was maintained in tibia and even increased in femur of hibernating ground squirrels. The protein levels of RANKL and MMP-9 were increased in femur and tibia in unloaded rats, while they were maintained in both femur and tibia of hibernating ground squirrels. The protein level of GSK-3β was increased in femur and tibia of unloaded rats, while it was maintained in both femur and tibia of hibernating ground squirrels. The phospho-β-catenin expression was increased in both femur and tibia of unloaded rats, while it was only decreased in femur, but maintained in tibia of hibernating ground squirrels. In conclusion, the femur and tibia in hindlimb unloaded rats showed obvious bone loss, while they mitigated disuse-induced bone loss in hibernating ground squirrels, involving differential protein expression of key molecules in bone remodeling. In comparison with hindlimb unloaded rats, promoting osteoblast differentiation through activating canonical GSK-3β/β-catenin signaling involving Runx2 might be an adaptation to natural disuse in femur of hibernating Daurian ground squirrels. However, there was no statistical change in the protein levels of bone formation related proteins, GSK-3β and phospho-β-catenin in tibia of hibernating Daurian ground squirrels.

The Non-invasive Diagnosis of Bone Disorders in CKD

Abnormal bone metabolism is an integral part of the chronic kidney disease-mineral bone disorder (CKD-MBD). For several reasons, the difficult bone compartment was neglected for some time, but there has been renewed interest as a result of the conception of bone as a new endocrine organ, the increasing recognition of the cross-talk between bone and vessels, and, especially, the very high risk of osteoporotic fractures (and associated mortality) demonstrated in patients with CKD. Therefore, it has been acknowledged in different guidelines that action is needed in respect of fracture risk assessment and the diagnosis and treatment of osteoporosis in the context of CKD and CKD-MBD, even beyond renal osteodystrophy. These updated guidelines clearly underline the need to improve a non-invasive approach to these bone disorders in order to guide treatment decisions aimed at not only controlling CKD-MBD but also decreasing the risk of fracture. In this report, we review the current role of the most often clinically used or promising biochemical circulating biomarkers such as parathyroid hormone, alkaline phosphatases, and other biochemical markers of bone activity as alternatives to some aspects of bone histomorphometry. We also mention the potential role of classic and new imaging techniques for CKD patients. Information on many aspects is still scarce and heterogeneous, but many of us consider that it is indeed time for action, recognizing our definitely limited ability to base certain treatment decisions only on our current non-comprehensive knowledge.

Prognostic models for chronic kidney disease: a systematic review and external validation

BACKGROUND

Accurate risk prediction is needed in order to provide personalized healthcare for chronic kidney disease (CKD) patients. An overload of prognosis studies is being published, ranging from individual biomarker studies to full prediction studies. We aim to systematically appraise published prognosis studies investigating multiple biomarkers and their role in risk predictions. Our primary objective was to investigate if the prognostic models that are reported in the literature were of sufficient quality and to externally validate them.

METHODS

We undertook a systematic review and appraised the quality of studies reporting multivariable prognosis models for end-stage renal disease (ESRD), cardiovascular (CV) events and mortality in CKD patients. We subsequently externally validated these models in a randomized trial that included patients from a broad CKD population.

RESULTS

We identified 91 papers describing 36 multivariable models for prognosis of ESRD, 50 for CV events, 46 for mortality and 17 for a composite outcome. Most studies were deemed of moderate quality. Moreover, they often adopted different definitions for the primary outcome and rarely reported full model equations (21% of the included studies). External validation was performed in the Multifactorial Approach and Superior Treatment Efficacy in Renal Patients with the Aid of Nurse Practitioners trial (n = 788, with 160 events for ESRD, 79 for CV and 102 for mortality). The 24 models that reported full model equations showed a great variability in their performance, although calibration remained fairly adequate for most models, except when predicting mortality (calibration slope >1.5).

CONCLUSIONS

This review shows that there is an abundance of multivariable prognosis models for the CKD population. Most studies were considered of moderate quality, and they were reported and analysed in such a manner that their results cannot directly be used in follow-up research or in clinical practice.

High alkaline phosphatase and low intact parathyroid hormone associate with worse clinical outcome in peritoneal dialysis patients

OBJECTIVE

Alkaline phosphatase (ALP) is used as a biomarker to monitor the chronic kidney disease-mineral bone disorder (CKD-MBD) and high levels of parathyroid hormone (PTH) that were reported to be related to increased mortality in CKD patients. Therefore, we conducted this longitudinal cohort study to evaluate the relations between ALP and intact PTH (iPTH) and the associations with all-cause and cardiovascular mortality in peritoneal dialysis (PD) patients.

METHODS

In 1276 incident PD patients (median age 50 years, 56% males), baseline serum ALP, iPTH, and metabolic biomarkers potentially linked to CKD-MBD were analyzed in relation to mortality during follow-up period of up to 60 months. All-cause and cardiovascular mortality risk of ALP and iPTH were analyzed with competing-risks regression models with transplantation as competing risk adjusting for all covariates.

RESULTS

After adjustments for confounders by logistic regression model, older age, higher change level to levels of iPTH, S-albumin, calcium, alanine transaminase (ALT), and lower level of phosphorus were associated with higher ALP level (>79 U/L), and female gender, non-diabetes mellitus, younger age, lower calcium, higher ALT, total bilirubin, phosphorus, and ALP were associated with higher iPTH level (>300 pg/mL). During 60 months (median 44 months) of follow-up, the all-cause mortality rate was 16%, and 91 (46%) of the 199 deaths were caused by cardiovascular disease. In competing-risks regression analysis, "high ALP + low iPTH" was independently associated with all-cause and cardiovascular mortality after adjustment for age, gender, presence of diabetes, and cardiovascular disease, the calendar year of recruitment and vitamin D therapy in PD patients. The subhazard ratio (sHR) of group "high ALP + low iPTH" was 1.96 times and 3.35 times higher than sHR of group "low ALP + high iPTH" for all-cause mortality and cardiovascular mortality, respectively.

CONCLUSIONS

The combination of high ALP and low iPTH was independently associated with increased all-cause and cardiovascular mortality in PD patients, suggesting that ALP and iPTH have the potential to predict clinical outcomes and might be useful risk assessment tools in PD patients. Further studies exploring the observed association between combination of ALP with iPTH and mortality are warranted.

Bone alkaline phosphatase: An important biomarker in chronic kidney disease - mineral and bone disorder

Increased cardiovascular morbidity and mortality in chronic kidney disease (CKD) represents an emerging major health problem. Indeed, disturbances in mineral and bone metabolism occur frequently in CKD and are termed chronic kidney disease - mineral and bone disorder (CKD-MBD). These can lead to cardiovascular pathology, resulting in an increased cardiovascular risk. Bone alkaline phosphatase (BALP) is essential for biomineralization. Recent findings demonstrate a crucial role for BALP in the pathogenesis of vascular calcification and identified it as a promising predictor of mortality in CKD. In conjunction with parathyroid hormone (PTH), serum BALP has been suggested as a biomarker of bone turnover in CKD-MBD. In contrast to PTH, serum BALP demonstrates a lower variability and may thus be better suited for the diagnosis and longitudinal follow-up of bone turnover. The linear association with mortality, compared to the U-shaped curve for PTH, is an additional advantage, making BALP more suitable than PTH as a treatment target in CKD. Here we review the main characteristics of alkaline phosphatase isozymes/isoforms and the various assays currently used in clinical routine laboratories. We also discuss the role of BALP in both physiological and pathological mineralization, and the clinical benefit of BALP determination in CKD.

Association between mineral and bone disorder in patients with acute kidney injury following cardiac surgery and adverse outcomes

BACKGROUND

Numerous studies have evaluated the prevalence and importance of mineral and bone disorders among patients with chronic kidney disease (CKD) and end-stage renal disease (ESRD). However, little is known about dysregulated mineral and bone metabolism in acute kidney injury (AKI).

METHODS

We evaluated the association between mineral and bone metabolites and clinical outcomes in 158 patients who underwent cardiac surgery and developed AKI between June 2014 and January 2016. The baseline characteristics of the patients were recorded, and the levels of mineral and bone metabolites, including calcium, phosphate, intact parathyroid hormone (iPTH), 25-hydroxyvitamin D (25D), bone-specific alkaline phosphatase (BAP), tartrate-resistant acid phosphatase 5b (TRACP-5b) and C-terminal fibroblast growth factor 23 (cFGF23) were measured within 12 h after establishing the clinical diagnosis.

RESULTS

The serum phosphate, iPTH and cFGF23 levels were significantly associated with the 28-day mortality (phosphate: Hazard Ratio [HR] =2.620, 95% CI: 1.083 to 6.338, p = 0.035; iPTH: HR = 1.044, 95% CI: 1.001 to 1.090, p = 0.046; cFGF23: HR = 1.367, 95% CI: 1.168 to 1.599, p < 0.001). Moreover, higher serum cFGF23 and BAP levels were independently associated with an increased risk of adverse outcomes. Additionally, we found that the serum cFGF23 levels rose most significantly and were associated with the severity of AKI (P < 0.001).

CONCLUSIONS

Mineral and bone metabolites are dysregulated and are associated with adverse clinical outcomes among patients with AKI.

TRIAL REGISTRATION

www.clinicaltrials.gov NCT00953992. Registered 6 August 2009.

Efficacy and safety of once-monthly risedronate in osteoporosis subjects with mild-to-moderate chronic kidney disease: a post hoc subgroup analysis of a phase III trial in Japan

Limited data are available on the safety and efficacy of anti-resorptive agents, particularly once-monthly bisphosphonates, for use in osteoporotic patients with chronic kidney disease (CKD). We conducted a post hoc analysis of data from a 12-month, randomized, double-blind, phase III study to evaluate the safety and efficacy of once-monthly risedronate (RIS-OM) 75 mg tablets in Japanese osteoporosis patients with mild-to-moderate CKD. Patients who received RIS-OM 75 mg were stratified by baseline estimated glomerular filtration rate (eGFR; ≥ 90, ≥ 60 to < 90, or ≥ 30 to < 60 mL/min/1.73 m²). Safety endpoints were incidence of adverse events (AEs) and percent change from baseline in eGFR, serum creatinine, calcium, and phosphorus. Efficacy endpoints were percent change from baseline in lumbar spine bone mineral density (BMD) and bone turnover markers (BTMs). In 420 patients included (age 67.7 ± 6.7 years, women 98.8%), the incidence of all AEs, gastrointestinal disorders, acute phase reaction, non-vertebral fractures, and renal and urinary disorders was not significantly different among subgroups. Interaction between subgroups and time was significant for eGFR (p = 0.010) and serum creatinine (p = 0.001) but considered to be regression to the mean and clinically insignificant. BMD significantly increased while BTMs significantly decreased from baseline with a similar degree of change among the subgroups. In conclusion, RIS-OM 75 mg showed consistent safety and efficacy in suppressing bone turnover and increasing BMD in Japanese primary osteoporosis patients with mild-to-moderate CKD. These results should, however, be interpreted with caution because the number of patients with moderate CKD was limited.

Circulating bone-specific alkaline phosphatase and abdominal aortic calcification in maintenance hemodialysis patients

AIM

To explore the relationship between circulating bone-specific alkaline phosphatase (BALP) levels and abdominal aortic calcification (AAC) in patients receiving maintenance hemodialysis (MHD).

METHODS

A total of 156 MHD patients were enrolled. Serum BALP levels were measured using ELISA, and AAC was assessed via lateral abdominal radiography.

RESULTS

BALP was positively correlated with AAC score (r = 0.389; p < 0.01). Multivariate logistic regression analysis showed that high-sensitivity C-reactive protein, dialysis vintage and BALP were independent risk factors for AAC in MHD patients. Receiver-operating characteristic analysis indicated that the area under the curve of BALP for the prediction of AAC was 0.737 (95% CI: 0.619-0.855; p < 0.01). When the detection cut-off level was 17.55 μg/l, its sensitivity was 81.7% and specificity was 74.5%.

CONCLUSION

Serum BALP is closely correlated with vascular calcification in MHD patients.

Effects of parathyroidectomy on blood bone markers and heart rate variability in patients with stage 5 chronic kidney disease

PURPOSE

Decreased heart rate variability (HRV) is closely related to abnormal cardiac autonomic nervous function, especially sympathetic hyperactivity, which intensifies the risk of cardiovascular events and sudden death. HRV parameters are lower in chronic kidney disease (CKD) and parathyroidectomy (PTX) can improve these abnormalities in severe secondary hyperparathyroidism (SHPT) patients. However, few studies have evaluated correlations between circulating bone markers and HRV in CKD patients.

METHODS

We conducted a cross-sectional study including 134 stage 5 CKD patients with 100 controls and a prospective study of 29 PTX patients with follow-up. Circulating bone biomarkers included: (1) intact parathyroid hormone (iPTH) as bone remodeling regulator; (2) bone-specific alkaline phosphatase (BAP), representing bone formation; (3) tartrate-resistant acid phosphatase 5b (TRACP-5b), indicating bone resorption; and (4) bone-derived hormone, fibroblast growth factor 23 (FGF23).

RESULTS

Stage 5 CKD patients had higher circulating iPTH, BAP, TRACP-5b, and FGF23 than controls and these bone markers were significantly elevated in SHPT patients. Baseline iPTH, BAP, and lnFGF23 were independently associated with HRV in CKD patients. After PTX with a follow-up (median interval: 6.7 months), high blood iPTH, BAP, TRACP-5b, FGF23, and attenuated HRV were ameliorated. Furthermore, improved HRV indices were associated with reduced iPTH, BAP, TRACP-5b, and FGF23.

CONCLUSIONS

Circulating bone markers are correlated with HRV in CKD 5 patients and PTX can improve decreased HRV, which are associated with corrected bone markers in severe SHPT patients. Thus, we propose that PTH increases sympathetic tone and both high circulating PTH levels and sympathetic hyperactivity increase bone turnover, and that the products of bone turnover influence HRV.

Potential Role for Osteocalcin in the Development of Atherosclerosis and Blood Vessel Disease

There is increasing evidence for the involvement of the skeleton in the regulation of atherosclerotic vascular disease. Osteocalcin, an osteoblast derived protein, exists in two forms, carboxylated and undercarboxylated osteocalcin. Undercarboxylated osteocalcin has been linked to the regulation of metabolic functions, including glucose and lipid metabolism. Features of atherosclerosis have been associated with circulating osteocalcin; however, this association is often conflicting and unclear. Therefore, the aim of this review is to examine the evidence for a role of osteocalcin in atherosclerosis development and progression, and in particular endothelial dysfunction and vascular calcification. The current literature suggests that undercarboxylated osteocalcin stimulates the phosphoinositide 3-kinase/protein kinase B (PI3K/Akt) signaling pathway to upregulate nitric oxide and nuclear factor kappa β (NF-кβ) in vascular cells, possibly protecting endothelial function and preventing atherogenesis. However, this effect may be mediated by metabolic factors, such as improvements in insulin signaling, rather than through a direct effect on the vasculature. Total osteocalcin is frequently associated with vascular calcification, an association that may occur as a result of vascular cells eliciting an osteogenic phenotype. Whether osteocalcin acts as a mediator or a marker of vascular calcification is currently unclear. As such, further studies that examine each form of osteocalcin are required to elucidate if it is a mediator of atherogenesis, and whether it functions independently of metabolic factors.

Alkaline Phosphatases in the Complex Chronic Kidney Disease-Mineral and Bone Disorders

Alkaline phosphatases (APs) remove the phosphate (dephosphorylation) needed in multiple metabolic processes (from many molecules such as proteins, nucleotides, or pyrophosphate). Therefore, APs are important for bone mineralization but paradoxically they can also be deleterious for other processes, such as vascular calcification and the increasingly known cross-talk between bone and vessels. A proper balance between beneficial and harmful activities is further complicated in the context of chronic kidney disease (CKD). In this narrative review, we will briefly update the complexity of the enzyme, including its different isoforms such as the bone-specific alkaline phosphatase or the most recently discovered B1x. We will also analyze the correlations and potential discrepancies with parathyroid hormone and bone turnover and, most importantly, the valuable recent associations of AP's with cardiovascular disease and/or vascular calcification, and survival. Finally, a basic knowledge of the synthetic and degradation pathways of APs promises to open new therapeutic strategies for the treatment of the CKD-Mineral and Bone Disorder (CKD-MBD) in the near future, as well as for other processes such as sepsis, acute kidney injury, inflammation, endothelial dysfunction, metabolic syndrome or, in diabetes, cardiovascular complications. However, no studies have been done using APs as a primary therapeutic target for clinical outcomes, and therefore, AP's levels cannot yet be used alone as an isolated primary target in the treatment of CKD-MBD. Nonetheless, its diagnostic and prognostic potential should be underlined.

Two-year cortical and trabecular bone loss in CKD-5D: biochemical and clinical predictors

This prospective two-year study of patients on chronic dialysis measured changes in bone mineral density (BMD). Patients with higher baseline BMD and shorter dialysis vintage lost more bone. Treatment with anti-hypertensives acting on the central nervous system was protective against bone loss. Baseline serum levels of sclerostin and bone-specific alkaline phosphatase predicted bone loss.

INTRODUCTION

This prospective 2-year study of chronic kidney disease on dialysis (CKD-5D) patients assessed trabecular and cortical bone loss at the hip and spine and examined potential demographic, clinical, and serum biochemical predictors of bone loss.

METHODS

Eighty-nine CKD-5D patients had baseline, year 1, and year 2 bone mineral density (BMD) measurements using dual X-ray absorptiometry (DXA) and quantitative computed tomography (QCT); concurrent blood samples were drawn and clinical variables recorded. No study treatments occurred.

RESULTS

The 2-year total hip BMD change was - 5.9% by QCT and - 3.1% by DXA (p < 0.001). Spinal BMD was unchanged. QCT total hip cortical mass and volume decreased (- 7.3 and - 10.0%); trabecular volume increased by 5.9% (ps < 0.001). BMD changes did not vary with age, BMI, race, diabetes, smoking, or exercise. Patients with higher baseline BMD and shorter dialysis vintage lost more bone (p < 0.05). Vitamin D analogs and phosphate binders were not protective against bone loss; cinacalcet was protective by univariate but not by multivariable analysis. CNS-affecting antihypertensives were protective against loss of BMD, cortical mass, cortical volume (ps < 0.05) and trabecular mass (p = 0.007). These effects remained after adjustment. BSAP correlated with changes in BMD, cortical mass, and volume (p < 0.01) as did sclerostin (inversely).

CONCLUSIONS

There was severe cortical bone loss at the hip best recognized by QCT. Patients with shorter dialysis vintage and less pre-existing bone loss lost more bone, while treatment with CNS-acting antihypertensives was protective. BSAP and sclerostin were useful markers of bone loss.

Multifaceted interaction of bone, muscle, lifestyle interventions and metabolic and cardiovascular disease: role of osteocalcin

Undercarboxylated osteocalcin (ucOC) may play a role in glucose homeostasis and cardiometabolic health. This review examines the epidemiological and interventional evidence associating osteocalcin (OC) and ucOC with metabolic risk and cardiovascular disease. The complexity in assessing such correlations, due to the observational nature of human studies, is discussed. Several studies have reported that higher levels of ucOC and OC are correlated with lower fat mass and HbA1c. In addition, improved measures of glycaemic control via pharmacological and non-pharmacological (e.g. exercise or diet) interventions are often associated with increased circulating levels of OC and/or ucOC. There is also a relationship between lower circulating OC and ucOC and increased measures of vascular calcification and cardiovascular disease. However, not all studies have reported such relationship, some with contradictory findings. Equivocal findings may arise because of the observational nature of the studies and the inability to directly assess the relationship between OC and ucOC on glycaemic control and cardiovascular health in humans. Studying OC and ucOC in humans is further complicated due to numerous confounding factors such as sex differences, menopausal status, vitamin K status, physical activity level, body mass index, insulin sensitivity (normal/insulin resistance/T2DM), tissue-specific effects and renal function among others. Current observational and indirect interventional evidence appears to support a relationship between ucOC with metabolic and cardiovascular disease. There is also emerging evidence to suggest a direct role of ucOC in human metabolism. Further mechanistic studies are required to (a) clarify causality, (b) explore mechanisms involved and

Alkaline phosphatase: a novel treatment target for cardiovascular disease in CKD

Cardiovascular disease is the main cause of early death in the settings of chronic kidney disease (CKD), type 2 diabetes mellitus (T2DM), and ageing. Cardiovascular events can be caused by an imbalance between promoters and inhibitors of mineralization, which leads to vascular calcification. This process is akin to skeletal mineralization, which is carefully regulated and in which isozymes of alkaline phosphatase (ALP) have a crucial role. Four genes encode ALP isozymes in humans. Intestinal, placental and germ cell ALPs are tissue-specific, whereas the tissue-nonspecific isozyme of ALP (TNALP) is present in several tissues, including bone, liver and kidney. TNALP has a pivotal role in bone calcification. Experimental overexpression of TNALP in the vasculature is sufficient to induce vascular calcification, cardiac hypertrophy and premature death, mimicking the cardiovascular phenotype often found in CKD and T2DM. Intestinal ALP contributes to the gut mucosal defence and intestinal and liver ALPs might contribute to the acute inflammatory response to endogenous or pathogenic stimuli. Here we review novel mechanisms that link ALP to vascular calcification, inflammation, and endothelial dysfunction in kidney and cardiovascular diseases. We also discuss new drugs that target ALP, which have the potential to improve cardiovascular outcomes without inhibiting skeletal mineralization.

Teriparatide treatment in a heart transplant patient with a chronic kidney disease and a low-turnover bone disease: a case report

Low-turnover bone disease is a complication of chronic kidney disease and a long-term steroid therapy. Currently, the only bone anabolic treatment available is teriparatide (TPTD). So far, no data exist in heart transplant patients, and only one single case with histomorphometric analysis of a dialysis patient with a low-turnover bone disease has been published. The current report shows the effect of a 1-year TPTD therapy in a cardiac transplant patient with 10 vertebral and 3 peripheral fractures who had developed a chronic kidney failure while receiving triple immunosuppressive therapy. A transiliac bone biopsy following tetracycline labeling was performed prior and after 1 year of treatment, showing an increase in the bone formation and improvement of the structural indices (20-fold increase of osteoid volume/bone volume, fourfold increase of osteoid surface/bone surface and increases of wall thickness (+15%), trabecular thickness (+9%), and trabecular number (+38%)). Bone mineral density was stable, no new vertebral fractures had occurred, the therapy was well-tolerated, and the patient improved clinically.

Suppressed bone remodeling in black bears conserves energy and bone mass during hibernation

Decreased physical activity in mammals increases bone turnover and uncouples bone formation from bone resorption, leading to hypercalcemia, hypercalcuria, bone loss and increased fracture risk. Black bears, however, are physically inactive for up to 6 months annually during hibernation without losing cortical or trabecular bone mass. Bears have been shown to preserve trabecular bone volume and architectural parameters and cortical bone strength, porosity and geometrical properties during hibernation. The mechanisms that prevent disuse osteoporosis in bears are unclear as previous studies using histological and serum markers of bone remodeling show conflicting results. However, previous studies used serum markers of bone remodeling that are known to accumulate with decreased renal function, which bears have during hibernation. Therefore, we measured serum bone remodeling markers (BSALP and TRACP) that do not accumulate with decreased renal function, in addition to the concentrations of serum calcium and hormones involved in regulating bone remodeling in hibernating and active bears. Bone resorption and formation markers were decreased during hibernation compared with when bears were physically active, and these findings were supported by histomorphometric analyses of bone biopsies. The serum concentration of cocaine and amphetamine regulated transcript (CART), a hormone known to reduce bone resorption, was 15-fold higher during hibernation. Serum calcium concentration was unchanged between hibernation and non-hibernation seasons. Suppressed and balanced bone resorption and formation in hibernating bears contributes to energy conservation, eucalcemia and the preservation of bone mass and strength, allowing bears to survive prolonged periods of extreme environmental conditions, nutritional deprivation and anuria.

[Biochemical markers of bone metabolism and their importance]

Laboratory analyses of biochemical markers for bone and mineral metabolism can play a key role in the assessment of patients with osteoporosis. They may help to assess bone turnover in the diagnostic work-up and aid decision-making as well as selection of pharmaceutical therapy options. Recent publications on therapy response have shown that biochemical markers of bone turnover are valuable tools for the evaluation of therapy success in individual osteoporosis patients and the assessment of bone mineral density gain during therapy.

αKlotho and Chronic Kidney Disease

Alpha-Klotho (αKlotho) protein is encoded by the gene, Klotho, and functions as a coreceptor for endocrine fibroblast growth factor-23. The extracellular domain of αKlotho is cleaved by secretases and released into the circulation where it is called soluble αKlotho. Soluble αKlotho in the circulation starts to decline in chronic kidney disease (CKD) stage 2 and urinary αKlotho in even earlier CKD stage 1. Therefore soluble αKlotho is an early and sensitive marker of decline in kidney function. Preclinical data from numerous animal experiments support αKlotho deficiency as a pathogenic factor for CKD progression and extrarenal CKD complications including cardiac and vascular disease, hyperparathyroidism, and disturbed mineral metabolism. αKlotho deficiency induces cell senescence and renders cells susceptible to apoptosis induced by a variety of cellular insults including oxidative stress. αKlotho deficiency also leads to defective autophagy and angiogenesis and promotes fibrosis in the kidney and heart. Most importantly, prevention of αKlotho decline, upregulation of endogenous αKlotho production, or direct supplementation of soluble αKlotho are all associated with attenuation of renal fibrosis, retardation of CKD progression, improvement of mineral metabolism, amelioration of cardiac function and morphometry, and alleviation of vascular calcification in CKD. Therefore in rodents, αKlotho is not only a diagnostic and prognostic marker for CKD but the enhancement of endogenous or supplement of exogenous αKlotho are promising therapeutic strategies to prevent, retard, and decrease the comorbidity burden of CKD.

The potential use of antisclerostin therapy in chronic kidney disease-mineral and bone disorder

PURPOSE OF REVIEW

Sclerostin is a regulator of the osteoanabolic canonical Wnt signaling pathway, and thus helps to govern rates of bone formation. The Wnt pathway is also recognized as playing an important role in the pathophysiology of the chronic kidney disease-mineral and bone disorder (CKD-MBD). It also may serve as an interface between bone and the vascular system. Pharmacological inhibition of sclerostin has shown promise as an osteoanabolic approach to the treatment of osteoporosis. Inhibition of sclerostin is a potentially useful but unproven strategy in the management of CKD-MBD.

RECENT FINDINGS

Clinical trials with humanized monoclonal sclerostin antibodies (Scl-Ab) have shown a rapid initial increase in bone formation and a marked increase in bone mineral density. Although clinical data, to this point, in CKD are not available, animal models of low bone turnover CKD show that Scl-Ab improves trabecular bone volume and mineralization without affecting biochemical indices.

SUMMARY

Targeted clinical trials are needed to evaluate the potential effectiveness of Scl-Ab in CKD. Based upon the available data, there is potential not only for this new therapeutic class to improve skeletal health but perhaps also to have substantial cardiovascular benefits in CKD.

Bone metabolism and arterial stiffness after renal transplantation

BACKGROUND/AIMS

To assess the relationship between bone and vascular disease and its changes over time after renal transplantation. Metabolic bone disease (MBD) is common in chronic kidney disease (CKD) and is associated with cardiovascular (CV) disease. Following transplantation (Tx), improvement in CV disease has been reported; however, data regarding changes in bone disease remain controversial.

METHODS

Bone turnover and arterial stiffness (pulse wave velocity (PWV)) were assessed in 47 Tx patients (38 (3-191) months after Tx).

RESULTS

Bone alkaline phosphatase (BALP), osteocalcin (OC) and beta-crosslaps were significantly higher in Tx patients, and decreased significantly after one year. There was a negative correlation between BALP, OC and steroid administered (r = -0.35; r = -0.36 respectively). PWV increased in the Tx group (1.15 SD). In patients with a follow up of <24 months, PWV was correlated with BALP and beta-crosslaps (r=0.53; r = 0.69 respectively) while in the ≥24 months group, PWV was correlated with cholesterol (r=0.38).

CONCLUSIONS

Increased bone turnover and arterial stiffness are present following kidney transplantation. While bone turnover decreases with time, arterial stiffness correlates initially with bone turnover, after which the influence of cholesterol becomes significant. Non-invasive estimation of bone metabolism and arterial stiffness may help to assess CKD-MBD following renal transplantation.

News on biomarkers in CKD-MBD

The increased awareness of the potential role played by mineral and bone disorder in the appearance of cardiovascular disease in renal patients has produced research efforts aimed at discovering possible pathogenic links. Accordingly, the diagnostic significance of the classic bone markers of mineral disorders and of the new markers in the setting of chronic kidney disease-mineral and bone disorders (CKD-MBD) needs to be re-evaluated along with increasing information. In this article we include classic markers of bone metabolism and some of the noncollagenous bone proteins that are gaining experimental and clinical significance in CKD-MBD. Among classic markers of secondary hyperparathyroidism and of renal osteodystrophy, we analyzed parathyroid hormone, alkaline phosphatase, tartrate-resistant acid phosphatase, and bone collagen-derived peptides. We underlined, for each, the relevance of parent proteins (peptides or isoforms) that affect assay methods and, eventually, the diagnostic or prognostic significance. Also, we considered their relationship with cardiovascular mortality. Among the numerous noncollagenous bone proteins, we examined matrix Gla protein (MGP), osteocalcin (OC), osteoprotegerin, and the small integrin-binding ligand N-linked glycoprotein family. For MGP and OC we report the relevant involvement with the process of calcification (MGP) and with glucose and energy metabolism (OC). Both of these proteins require vitamin K to become active and this is a specific problem in renal patients who frequently are deficient of this vitamin. Finally, recent acquisitions on the fascinating family of the small integrin-binding ligand N-linked glycoprotein proteins are recapitulated briefly to underline their potential clinical interest and their complex involvement with all aspects of CKD-MBD. Their diagnostic role in clinical practice awaits further studies.

Paricalcitol for secondary hyperparathyroidism in renal transplantation

Secondary hyperparathyroidism contributes to post-transplant CKD mineral and bone disorder. Paricalcitol, a selective vitamin D receptor activator, decreased serum parathyroid hormone levels and proteinuria in patients with secondary hyperparathyroidism. This single-center, prospective, randomized, crossover, open-label study compared the effect of 6-month treatment with paricalcitol (1 μg/d for 3 months and then uptitrated to 2 µg/d if tolerated) or nonparicalcitol therapy on serum parathyroid hormone levels (primary outcome), mineral metabolism, and proteinuria in 43 consenting recipients of renal transplants with secondary hyperparathyroidism. Participants were randomized 1:1 according to a computer-generated sequence. Compared with baseline, median (interquartile range) serum parathyroid hormone levels significantly declined on paricalcitol from 115.6 (94.8-152.0) to 63.3 (52.0-79.7) pg/ml (P<0.001) but not on nonparicalcitol therapy. At 6 months, levels significantly differed between treatments (P<0.001 by analysis of covariance). Serum bone-specific alkaline phosphatase and osteocalcin decreased on paricalcitol therapy only and significantly differed between treatments at 6 months (P<0.001 for all comparisons). At 6 months, urinary deoxypyridinoline-to-creatinine ratio and 24-hour proteinuria level decreased only on paricalcitol (P<0.05). L3 and L4 vertebral mineral bone density, assessed by dual-energy x-ray absorption, significantly improved with paricalcitol at 6 months (P<0.05 for both densities). Paricalcitol was well tolerated. Overall, 6-month paricalcitol supplementation reduced parathyroid hormone levels and proteinuria, attenuated bone remodeling and mineral loss, and reduced eGFR in renal transplant recipients with secondary hyperparathyroidism. Long-term studies are needed to monitor directly measured GFR, ensure that the bone remodeling and mineral effects are sustained, and determine if the reduction in proteinuria improves renal and cardiovascular outcomes.

Association of serum alkaline phosphatase with mortality in non-selected European patients with CKD5D: an observational, three-centre survival analysis

OBJECTIVES

For characterisation of mineral bone disease in chronic kidney disease (CKD), laboratory surrogates have been suggested. This observational should investigate the association of total and skeletal alkaline phosphatase (AP) with mortality of patients undergoing maintenance renal replacement therapy.

SETTING

Three renal outpatient centers in eastern-central Germany (secondary and tertiary care).

PARTICIPANTS

Complete survival and laboratory datasets were available in 407 of 493 patients. Age and gender distribution was equivalent to a general population with end-stage CKD (CKD5D). Patients were included between 2008 and 2010 if at least 2 weeks of maintenance treatment were documented.

PRIMARY OUTCOME MEASURES

Mortality was estimated by setting the end of dialysis date as event date. Events other than death (change to another centre, life-sustaining renal function or transplantation) were censored.

RESULTS

The OR to die within follow-up for patients in the higher of two total AP strata was 2.70 (95% CI 1.76 to 4.15). In univariate Kaplan-Meier analysis, total AP had a strong association with all-cause mortality (LogRank=24.1, p<0.001). Mean total AP and individual lowest skeletal AP, but not mean skeletal AP entered step-wise Cox models for survival from dialysis start (χ(2)=22.4; p<0.001) after adjusting for age, Kt/V, diabetes and vintage. Mean values of skeletal, total AP and parathyroid hormone were 14.8±8.9 µg/L, 91.9±55.3 U/L and 188±164 ng/L, respectively. Skeletal and total AP were highly correlated (R=0.86; p<0.001).

CONCLUSIONS

This unselected CKD5D population exhibited a clinical significant association of total AP with crude mortality and a stronger death risk association of total AP and individual lowest skeletal AP with crude mortality.

Comparative mortality-predictability using alkaline phosphatase and parathyroid hormone in patients on peritoneal dialysis and hemodialysis

BACKGROUND

In hemodialysis (HD) patients, serum alkaline phosphatase (ALP) and parathyroid hormone (PTH) derangements are associated with mortality, but outcome-predictability using ALP and PTH in peritoneal dialysis (PD) patients remains uncertain.

METHODS

In a cohort of 9244 adult PD patients from a large national dialysis organization (entry period 2001 - 2006, with follow-up through 2009), we used multivariable Cox models adjusted for case-mix and laboratory covariates to examine the associations of time-averaged ALP and PTH with all-cause mortality. We then compared mortality-predictability using ALP and PTH in 9244 PD and 99 323 HD patients.

RESULTS

In PD patients, ALP concentrations exceeding 150 U/L were associated with increased mortality (reference ALP: 70 to <90 U/L). Hazard ratios (HRs) and 95% confidence intervals (CIs) were 1.18 (1.03 to 1.36), 1.27 (1.08 to 1.50), 1.49 (1.23 to 1.79), and 1.35 (1.19 to 1.53) for ALP concentrations of 150 to <170 U/L, 170 to <190 U/L, 190 to <210 U/L, and ≥210 U/L respectively. In contrast, we observed a U-shaped association between PTH concentration and death risk in PD patients, with PTH concentrations of less than 200 pg/mL and 700 pg/mL or more associated with increased mortality (reference PTH: 200 to <300 pg/mL). Hazard ratios and 95% CIs were 1.25 (1.12 to 1.41), 1.12 (1.02 to 1.23), 1.06 (0.96 to 1.18), 1.09 (0.97 to 1.24), 1.12 (0.97 to 1.29), 1.18 (0.99 to 1.40), and 1.23 (1.09 to 1.38) for PTH concentrations of <100 pg/mL, 100 to <200 pg/mL, 300 to <400 pg/mL, 400 to <500 pg/mL, 500 to <600 pg/mL, 600 to <700 pg/mL, and ≥700 pg/mL respectively. Compared with PD patients having serum concentrations of ALP and PTH within reference ranges, patients on HD experienced increased mortality across all ALP and PTH concentrations, particularly those in the lowest and highest categories.

CONCLUSIONS

In summary, higher ALP concentrations are associated with increased mortality, and lower and higher PTH concentrations are both associated with death risk in PD patients. The utility of ALP in the management of chronic kidney disease mineral bone disorders in PD patients warrants further study.

Poststroke hip fracture: prevalence, clinical characteristics, mineral-bone metabolism, outcomes, and gaps in prevention

Objective. To assess the prevalence, clinical and laboratory characteristics, and short-term outcomes of poststroke hip fracture (HF). Methods. A cross-sectional study of 761 consecutive patients aged ≥60 years (82.3 ± 8.8 years; 75% females) with osteoporotic HF. Results. The prevalence of poststroke HF was 13.1% occurring on average 2.4 years after the stroke. The poststroke group compared to the rest of the cohort had a higher proportion of women, subjects with dementia, history of TIA, hypertension, coronary artery disease, secondary hyperparathyroidism, higher serum vitamin B12 levels (>350 pmol/L), walking aid users, and living in residential care facilities. The majority of poststroke HF patients had vitamin D insufficiency (68%) and excess bone resorption (90%). This group had a 3-fold higher incidence of postoperative myocardial injury and need for institutionalisation. In multivariate analysis, independent indicators of poststroke HF were female sex (OR 3.6), history of TIA (OR 5.2), dementia (OR 4.1), hypertension (OR 3.2), use of walking aid (OR 2.5), and higher vitamin B12 level (OR 2.3). Only 15% of poststroke patients received antiosteoporotic therapy prior to HF. Conclusions. Approximately one in seven HFs occurs in older stroke survivors and are associated with poorer outcomes. Early implementation of fracture prevention strategies is needed.

Effects of paricalcitol on calcium and phosphate metabolism and markers of bone health in patients with diabetic nephropathy: results of the VITAL study

Background

Chronic kidney disease (CKD) is associated with elevations in serum phosphate, calcium–phosphorus product and bone-specific alkaline phosphatase (BAP), with attendant risks of cardiovascular and bone disorders. Active vitamin D can suppress parathyroid hormone (PTH), but may raise serum calcium and phosphate concentrations. Paricalcitol, a selective vitamin D activator, suppressed PTH in CKD patients (stages 3 and 4) with secondary hyperparathyroidism (SHPT) with minimal changes in calcium and phosphate metabolism.

Methods

The VITAL study enrolled patients with CKD stages 2–4. We examined the effect and relationship of paricalcitol to calcium and phosphate metabolism and bone markers in a post hoc analysis of VITAL. The study comprised patients with diabetic nephropathy enrolled in a double-blind, placebo-controlled, randomized trial of paricalcitol (1 or 2 μg/day). Urinary and serum calcium and phosphate, serum BAP, and intact PTH (iPTH) concentrations were measured throughout the study.

Results

Baseline demographics and calcium, phosphate, PTH (49% with iPTH <70 pg/mL), and BAP concentrations were similar between groups. A transient, modest yet significant increase in phosphate was observed for paricalcitol 2 μg/day (+0.29 mg/dL; P < 0.001). Dose-dependent increases in serum and urinary calcium were observed; however, there were few cases of hypercalcemia: one in the 1-μg/day group (1.1%) and three in the 2-μg/day group (3.2%). Significant reductions in BAP were observed that persisted for 60 days after paricalcitol discontinuation (P < 0.001 for combined paricalcitol groups versus placebo). Paricalcitol dose-dependent reductions in iPTH were observed. Paricalcitol in CKD patients (±SHPT) was associated with modest increases in calcium and phosphate.

Conclusion

Paricalcitol reduces BAP levels, which may be beneficial for reducing vascular calcification.

Trial registration

Trial is registered with ClinicalTrials.gov, number NCT00421733.

Prognostic importance of serum alkaline phosphatase in CKD stages 3-4 in a clinical population

BACKGROUND

Elevated total serum alkaline phosphatase (ALP) levels have been associated with mortality in the general population and in dialysis patients.

STUDY DESIGN

Retrospective cohort study.

SETTING & PARTICIPANTS

28,678 patients with chronic kidney disease (CKD) stages 3 and 4 (estimated glomerular filtration rate, 15-59 mL/min/1.73 m(2)) were identified using the Cleveland Clinic CKD Registry. CKD was defined as 2 estimated glomerular filtration rate values <60 mL/min/1.73 m(2) drawn more than 90 days apart using the CKD-EPI (CKD Epidemiology Collaboration) creatinine equation.

PREDICTOR

ALP levels measured using the calorimetric assay were examined as quartiles (quartile [Q]1, <66 U/L; Q2, 66-81 U/L; Q3, 82-101 U/L; and Q4, ≥102 U/L) and as a continuous measure.

OUTCOMES & MEASUREMENTS

All-cause mortality and end-stage renal disease (ESRD) were ascertained using the Social Security Death Index and US Renal Data System.

RESULTS

After a median follow-up of 2.2 years, 588 patients progressed to ESRD and 4,755 died. There was a graded increase in risk of mortality with higher ALP quartiles (Q2, Q3, and Q4) compared to the reference quartile (Q1) after adjusting for demographics, comorbid conditions, use of relevant medications, and liver function test results. The highest ALP quartile was associated with an HR for ESRD of 1.38 (95% CI, 1.09-1.76). Each 1-SD (42.7 U/L) higher ALP level was associated with 15% (95% CI, 1.09-1.22) and 16% (95% CI, 1.14-1.18) increased risk of ESRD and mortality, respectively.

LIMITATIONS

Single-center observational study; lack of complete data, including parathyroid hormone level, for all study participants, and attrition bias.

CONCLUSIONS

Higher serum ALP levels in patients with CKD stages 3-4 were associated independently with all-cause mortality and ESRD.

Cardiovascular diseases in older patients with osteoporotic hip fracture: prevalence, disturbances in mineral and bone metabolism, and bidirectional links

BACKGROUND

Considerable controversy exists regarding the contribution of mineral/bone metabolism abnormalities to the association between cardiovascular diseases (CVDs) and osteoporotic fractures.

AIMS AND METHODS

To determine the relationships between mineral/bone metabolism biomarkers and CVD in 746 older patients with hip fracture, clinical data were recorded and serum concentrations of parathyroid hormone (PTH), 25-hydroxyvitamin D, calcium, phosphate, magnesium, troponin I, parameters of bone turnover, and renal, liver, and thyroid functions were measured.

RESULTS

CVDs were diagnosed in 472 (63.3%) patients. Vitamin D deficiency was similarly prevalent in patients with (78.0%) and without (82.1%) CVD. The CVD group had significantly higher mean PTH concentrations (7.6 vs 6.0 pmol/L, P < 0.001), a higher prevalence of secondary hyperparathyroidism (SPTH) (PTH > 6.8 pmol/L, 43.0% vs 23.3%, P < 0.001), and excess bone resorption (urinary deoxypyridinoline corrected by creatinine [DPD/Cr] > 7.5 nmol/μmol, 87.9% vs 74.8%, P < 0.001). In multivariate regression analysis, SHPT (odds ratio [OR] 2.6, P = 0.007) and high DPD/Cr (OR 2.8, P = 0.016) were independent indictors of CVD. Compared to those with both PTH and DPD/Cr in the normal range, multivariate-adjusted ORs for the presence of CVD were 17.3 (P = 0.004) in subjects with SHPT and 9.7 (P < 0.001) in patients with high DPD/Cr. CVD was an independent predicator of SHPT (OR 2.8, P = 0.007) and excess DPD/Cr (OR 2.5, P = 0.031). CVD was predictive of postoperative myocardial injury, while SHPT was also an independent predictor of prolonged hospital stay and in-hospital death.

CONCLUSION

SHPT and excess bone resorption are independent pathophysiological mediators underlying the bidirectional associations between CVD and hip fracture, and therefore are important diagnostic and therapeutic targets.

Relation of vitamin D and parathyroid hormone to cardiac biomarkers and to left ventricular mass (from the Cardiovascular Health Study)

Vitamin D and parathyroid hormone (PTH) may affect cardiovascular health in patients with kidney disease and in the general population. The aim of this study was to investigate associations of serum 25-hydroxyvitamin D (25(OH)D) and PTH concentrations with a comprehensive set of biochemical, electrocardiographic, and echocardiographic measurements of cardiac structure and function in the Cardiovascular Health Study. A total of 2,312 subjects who were free of cardiovascular disease at baseline were studied. Serum 25(OH)D and intact PTH concentrations were measured using mass spectrometry and a 2-site immunoassay. Outcomes were N-terminal pro-B-type natriuretic peptide, cardiac troponin T, electrocardiographic measures of conduction, and echocardiographic measures of left ventricular mass and diastolic dysfunction. At baseline, subjects had a mean age of 73.9 ± 4.9 years, 69.7% were women, and 21% had chronic kidney disease (glomerular filtration rate <60 ml/min). Mean 25(OH)D was 25.2 ± 10.2 ng/ml, and median PTH was 51 pg/ml (range 39 to 65). After adjustment, 25(OH)D was not associated with any of the biochemical, conduction, or echocardiographic outcomes. Serum PTH levels ≥65 pg/ml were associated with greater N-terminal pro-B-type natriuretic peptide, cardiac troponin T, and left ventricular mass in patients with chronic kidney disease. The regression coefficients were: 120 pg/ml (95% confidence interval 36.1 to 204), 5.2 pg/ml (95% confidence interval 3.0 to 7.4), and 17 g (95% confidence interval 6.2 to 27.8) (p <0.001). In subjects with normal kidney function, PTH was not associated with the outcomes. In conclusion, in older adults with chronic kidney disease, PTH excess is associated with higher N-terminal pro-B-type natriuretic peptide, cardiac troponin T, and left ventricular mass. These findings suggest a role for PTH in cardiovascular health and the prevention of cardiac diseases.

Calcifying human aortic smooth muscle cells express different bone alkaline phosphatase isoforms, including the novel B1x isoform

BACKGROUND

Vascular calcification, causing cardiovascular morbidity and mortality, is associated with hyperphosphatemia in chronic kidney disease (CKD). In vitro, phosphate induces transdifferentiation of vascular smooth muscle cells to osteoblast-like cells that express alkaline phosphatase (ALP). In vivo, raised serum ALP activities are associated with increased mortality. A new bone ALP isoform (B1x) has been identified in serum from CKD patients. The present study investigated the different ALP isoforms in calcifying human aortic smooth muscle cells (HAoSMCs).

METHODS

HAoSMCs were cultured for 30 days in medium containing 5 or 10 mmol/l β-glycerophosphate in the presence or absence of the ALP-specific inhibitor tetramisole.

RESULTS

All known bone-specific ALP (BALP) isoforms (B/I, B1x, B1 and B2) were identified in HAoSMCs. β-Glycerophosphate stimulated calcification of HAoSMCs, which was associated with increased BALP isoforms B/I, B1x and B2. Tetramisole inhibited the β-glycerophosphate-induced HAoSMC calcification, which was paralleled by the inhibition of the B1x and B/I, but not the other isoforms.

CONCLUSIONS

HAoSMCs express the four known BALP isoforms. B/I, B1x and B2 could be essential for soft tissue calcification. B/I and B1x were more affected by tetramisole than the other isoforms, which suggests different biological functions during calcification of HAoSMCs.