Elastin haploinsufficiency impedes the progression of arterial calcification in MGP-deficient mice

Matrix gla protein (MGP) is a potent inhibitor of extracellular matrix (ECM) mineralization. MGP-deficiency in humans leads to Keutel syndrome, a rare genetic disease hallmarked by abnormal soft tissue calcification. MGP-deficient (Mgp(-/-)) mice show progressive deposition of hydroxyapatite minerals in the arterial walls and die within 2 months of age. The mechanism of antimineralization function of MGP is not fully understood. We examined the progression of vascular calcification and expression of several chondrogenic/osteogenic markers in the thoracic aortas of Mgp(-/-) mice at various ages. Although cells with chondrocyte-like morphology have been reported in the calcified aorta, our gene expression data indicate that chondrogenic/osteogenic markers are not upregulated in the arteries prior to the initiation of calcification. Interestingly, arterial calcification in Mgp(-/-) mice appears first in the elastic laminae. Considering the known mineral scaffolding function of elastin (ELN), a major elastic lamina protein, we hypothesize that elastin content in the laminae is a critical determinant for arterial calcification in Mgp(-/-) mice. To investigate this, we performed micro-computed tomography (µCT) and histological analyses of the aortas of Mgp(-/-);Eln(+/-) mice and show that elastin haploinsufficiency significantly reduces arterial calcification in this strain. Our data suggest that MGP deficiency leads to alterations of vascular ECM that may in turn initiate arterial calcification.

A comparison of calcium to zoledronic acid for improvement of cortical bone in an animal model of CKD

Patients with chronic kidney disease (CKD) have increased risk of fractures, yet the optimal treatment is unknown. In secondary analyses of large randomized trials, bisphosphonates have been shown to improve bone mineral density and reduce fractures. However, bisphosphonates are currently not recommended in patients with advanced kidney disease due to concern about oversuppressing bone remodeling, which may increase the risk of developing arterial calcification. In the present study we used a naturally occurring rat model of CKD with secondary hyperparathyroidism, the Cy/+ rat, and compared the efficacy of treatment with zoledronic acid, calcium given in water to simulate a phosphate binder, and the combination of calcium and zoledronic acid. Animals were treated beginning at 25 weeks of age (approximately 30% of normal renal function) and followed for 10 weeks. The results demonstrate that both zoledronic acid and calcium improved bone volume by micro-computed tomography (µCT) and both equally suppressed the mineral apposition rate, bone formation rate, and mineralizing surface of trabecular bone. In contrast, only calcium treatment with or without zoledronic acid improved cortical porosity and cortical biomechanical properties (ultimate load and stiffness) and lowered parathyroid hormone (PTH). However, only calcium treatment led to the adverse effects of increased arterial calcification and fibroblast growth factor 23 (FGF23). These results suggest zoledronic acid may improve trabecular bone volume in CKD in the presence of secondary hyperparathyroidism, but does not benefit extraskeletal calcification or cortical biomechanical properties. Calcium effectively reduces PTH and benefits both cortical and trabecular bone yet increases the degree of extra skeletal calcification. © 2014 American Society for Bone and Mineral Research.

Association Between Abdominal Aortic Calcification, Bone Mineral Density, and Fracture in Older Women

Although a relationship between vascular disease and osteoporosis has been recognized, its clinical importance for fracture risk evaluation remains uncertain. Abdominal aortic calcification (AAC), a recognized measure of vascular disease detected on single-energy images performed for vertebral fracture assessment, may also identify increased osteoporosis risk. In a prospective 10-year study of 1024 older predominantly white women (mean age 75.0 ± 2.6 years) from the Perth Longitudinal Study of Aging cohort, we evaluated the association between AAC, skeletal structure, and fractures. AAC and spine fracture were assessed at the time of hip densitometry and heel quantitative ultrasound. AAC was scored 0 to 24 (AAC24) and categorized into low AAC (score 0 and 1, n = 459), moderate AAC (score 2 to 5, n = 373), and severe AAC (score >6, n = 192). Prevalent vertebral fractures were calculated using the Genant semiquantitative method. AAC24 scores were inversely related to hip BMD ( r _s = -0.077, p = 0.013), heel broadband ultrasound attenuation ( r _s = -0.074, p = 0.020), and the Stiffness Index ( r _s = -0.073, p = 0.022). In cross-sectional analyses, women with moderate to severe AAC were more likely to have prevalent fracture and lumbar spine imaging-detected lumbar spine fractures, but not thoracic spine fractures (Mantel-Haenszel test of trend p < 0.05). For 10-year incident clinical fractures and fracture-related hospitalizations, women with moderate to severe AAC (AAC24 score >1) had increased fracture risk (HR 1.48; 95% CI, 1.15 to 1.91; p = 0.002; HR 1.46; 95% CI, 1.07 to 1.99; p = 0.019, respectively) compared with women with low AAC. This relationship remained significant after adjusting for age and hip BMD for clinical fractures (HR 1.40; 95% CI, 1.08 to 1.81; p = 0.010), but was attenuated for fracture-related hospitalizations (HR 1.33; 95% CI, 0.98 to 1.83; p = 0.073). In conclusion, older women with more marked AAC are at higher risk of fracture, not completely captured by bone structural predictors. These findings further support the concept that vascular calcification and bone pathology may share similar mechanisms of causation that remain to be fully elucidated © 2019 American Society for Bone and Mineral Research.

QCT Volumetric Bone Mineral Density and Vascular and Valvular Calcification: The Framingham Study

There is increasing evidence that bone and vascular calcification share common pathogenesis. Little is known about potential links between bone and valvular calcification. The purpose of this study was to determine the association between spine bone mineral density (BMD) and vascular and valvular calcification. Participants included 1317 participants (689 women, 628 men) in the Framingham Offspring Study (mean age 60 years). Integral, trabecular, and cortical volumetric bone density (vBMD) and arterial and valvular calcification were measured from computed tomography (CT) scans and categorized by sex-specific quartiles (Q4 = high vBMD). Calcification of the coronary arteries (CAC), abdominal aorta (AAC), aortic valve (AVC), and mitral valve (MVC) were quantified using the Agatston Score (AS). Prevalence of any calcium (AS >0) was 69% for CAC, 81% for AAC, 39% for AVC, and 20% for MVC. In women, CAC increased with decreasing quartile of trabecular vBMD: adjusted mean CAC = 2.1 (Q4), 2.2 (Q3), 2.5 (Q2), 2.6 (Q1); trend p = 0.04. However, there was no inverse trend between CAC and trabecular vBMD in men: CAC = 4.3 (Q4), 4.3 (Q3), 4.2 (Q2), 4.3 (Q1); trend p = 0.92. AAC increased with decreasing quartile of trabecular vBMD in both women (AAC = 4.5 [Q4], 4.8 [Q3], 5.4 [Q2], 5.1 [Q1]; trend p = 0.01) and men (AAC = 5.5 [Q4], 5.8 [Q3], 5.9 [Q2], 6.2 [Q1]; trend p = 0.01). We observed no association between trabecular vBMD and AVC or MVC in women or men. Finally, cortical vBMD was unrelated to vascular calcification and valvular calcification in women and men. Women and men with low spine vBMD have greater severity of vascular calcification, particularly at the abdominal aorta. The inverse relation between AAC and spine vBMD in women and men may be attributable to shared etiology and may be an important link on which to focus treatment efforts that can target individuals at high risk of both fracture and cardiovascular events.

Effect of Advanced Glycation End-Products (AGE) Lowering Drug ALT-711 on Biochemical, Vascular, and Bone Parameters in a Rat Model of CKD-MBD

Chronic kidney disease-mineral bone disorder (CKD-MBD) is a systemic disorder that affects blood measures of bone and mineral homeostasis, vascular calcification, and bone. We hypothesized that the accumulation of advanced glycation end-products (AGEs) in CKD may be responsible for the vascular and bone pathologies via alteration of collagen. We treated a naturally occurring model of CKD-MBD, the Cy/+ rat, with a normal and high dose of the AGE crosslink breaker alagebrium (ALT-711), or with calcium in the drinking water to mimic calcium phosphate binders for 10 weeks. These animals were compared to normal (NL) untreated animals. The results showed that CKD animals, compared to normal animals, had elevated blood urea nitrogen (BUN), PTH, FGF23 and phosphorus. Treatment with ALT-711 had no effect on kidney function or PTH, but 3 mg/kg lowered FGF23 whereas calcium lowered PTH. Vascular calcification of the aorta assessed biochemically was increased in CKD animals compared to NL, and decreased by the normal, but not high dose of ALT-711, with parallel decreases in left ventricular hypertrophy. ALT-711 (3 mg/kg) did not alter aorta AGE content, but reduced aorta expression of receptor for advanced glycation end products (RAGE) and NADPH oxidase 2 (NOX2), suggesting effects related to decreased oxidative stress at the cellular level. The elevated total bone AGE was decreased by 3 mg/kg ALT-711 and both bone AGE and cortical porosity were decreased by calcium treatment, but only calcium improved bone properties. In summary, treatment of CKD-MBD with an AGE breaker ALT-711, decreased FGF23, reduced aorta calcification, and reduced total bone AGE without improvement of bone mechanics. These results suggest little effect of ALT-711 on collagen, but potential cellular effects. The data also highlights the need to better measure specific types of AGE proteins at the tissue level in order to fully elucidate the impact of AGEs on CKD-MBD. © 2019 American Society for Bone and Mineral Research.

Osteogenesis of heterotopically transplanted mesenchymal stromal cells in rat models of chronic kidney disease

The current study is based on the hypothesis of mesenchymal stromal cells (MSCs) contributing to soft-tissue calcification and ectopic osteogenesis in chronic kidney disease (CKD). Rat MSCs were transplanted intraperitoneally in an established three-dimensional collagen-based model in healthy control animals and two rat models of CKD and vascular calcification: (1) 5/6 nephrectomy + high phosphorus diet; and (2) adenine nephropathy. As internal controls, collagen gels without MSCs were transplanted in the same animals. After 4 and 8 weeks, MSCs were still detectable and proliferating in the collagen gels (fluorescence-activated cell sorting [FACS] analysis and confocal microscopy after fluorescence labeling of the cells). Aortas and MSC-containing collagen gels in CKD animals showed distinct similarities in calcification (micro-computed tomography [µCT], energy-dispersive X-ray [EDX] analysis, calcium content), induction of osteogenic markers, (ie, bone morphogenic protein 2 [BMP-2], Runt related transcription factor 2 [Runx2], alkaline phosphatase [ALP]), upregulation of the osteocytic marker sclerostin and extracellular matrix remodeling with increased expression of osteopontin, collagen I/III/IV, fibronectin, and laminin. Calcification, osteogenesis, and matrix remodeling were never observed in healthy control animals and non-MSC-containing collagen gels in all groups. Paul Karl Horan 26 (PKH-26)-labeled, 3G5-positive MSCs expressed Runx2 and sclerostin in CKD animals whereas PKH-26-negative migrated cells did not express osteogenic markers. In conclusion, heterotopically implanted MSCs undergo osteogenic differentiation in rat models of CKD-induced vascular calcification, supporting our hypothesis of MSCs as possible players in heterotopic calcification processes of CKD patients.

Disturbances in Bone Largely Predict Aortic Calcification in an Alternative Rat Model Developed to Study Both Vascular and Bone Pathology in Chronic Kidney Disease

Because current rat models used to study chronic kidney disease (CKD)-related vascular calcification show consistent but excessive vascular calcification and chaotic, immeasurable, bone mineralization due to excessive bone turnover, they are not suited to study the bone-vascular axis in one and the same animal. Because vascular calcification and bone mineralization are closely related to each other, an animal model in which both pathologies can be studied concomitantly is highly needed. CKD-related vascular calcification in rats was induced by a 0.25% adenine/low vitamin K diet. To follow vascular calcification and bone pathology over time, rats were killed at weeks 4, 8, 10, 11, and 12. Both static and dynamic bone parameters were measured. Vascular calcification was quantified by histomorphometry and measurement of the arterial calcium content. Stable, severe CKD was induced along with hyperphosphatemia, hypocalcemia as well as increased serum PTH and FGF23. Calcification in the aorta and peripheral arteries was present from week 8 of CKD onward. Four and 8 weeks after CKD, static and dynamic bone parameters were measurable in all animals, thereby presenting typical features of hyperparathyroid bone disease. Multiple regression analysis showed that the eroded perimeter and mineral apposition rate in the bone were strong predictors for aortic calcification. This rat model presents a stable CKD, moderate vascular calcification, and quantifiable bone pathology after 8 weeks of CKD and is the first model that lends itself to study these main complications simultaneously in CKD in mechanistic and intervention studies.

Sevelamer Use, Vitamin K Levels, Vascular Calcifications, and Vertebral Fractures in Hemodialysis Patients: Results from the VIKI Study

Hyperphosphatemia is a risk factor for vascular calcifications (VCs), which are part of the chronic kidney disease-mineral and bone disorders (CKD-MBD). Vitamin K-dependent proteins such as matrix Gla protein (MGP) and bone Gla proteins (BGP, or osteocalcin) can inhibit VCs and regulate bone mineralization. In this analysis of the Vitamin K Italian (VIKI) study, the relationship between vitamin K status, vertebral fractures (VFs) and VCs in 387 hemodialysis (HD) patients with (N = 163; 42.1%) or without N = 224; 57.9%) sevelamer was evaluated. Levels of vitamin K vitamers K1 and K2 or menaquinones (MK; MK4-7), total and undercarboxylated (uc) forms for both BGP and MGP were determined. Although no differences in clinical characteristics were noted, lower levels of MK4 (0.45 versus 0.6 ng/mL, p = .01) and a greater MK4 deficiency was observed in sevelamer-treated patients (13.5% versus 5.4%, p = .005). Multivariate logistic regression revealed that MK4 deficiency was associated with sevelamer use (odds ratio [OR] = 2.64, 95% confidence interval [CI] 1.25-5.58, p = .011) and aortic calcification (OR = 8.04, 95% CI 1.07-60.26, p = .04). In the same logistic model, sevelamer amplified the effect of total BGP levels on the odds of VFs in patients with total BGP <150 μg/L compared with those with total BGP ≥150 μg/L (OR = 3.15, 95% CI 1.46-6.76, p = .003). In contrast, there was no such effect in those untreated (total BGP <150 μg/L versus total BGP ≥150 μg/L: OR = 1.21, 95% CI 0.66-2.23, p = .54]; p = .049 for effect modification by sevelamer). Sevelamer may interfere with MK4 levels in HD patients and interact with low BGP levels to increase bone fractures in CKD patients. © 2020 American Society for Bone and Mineral Research (ASBMR).

Nedd4 Deficiency in Vascular Smooth Muscle Promotes Vascular Calcification by Stabilizing pSmad1

The nonosseous calcification process such as atherosclerosis is one of the major complications in several types of metabolic diseases. In a previous study, we uncovered that aberrant activity of transforming growth factor β (TGF-β) signaling pathway could contribute to the vascular smooth muscle cells' (VSMCs) calcification process. Also, we identified NEDD4 E3 ligase as a key suppressor of bone morphogenetic protein (BMP)/Smad pathway via a polyubiquitination-dependent selective degradation of C-terminal phosphorylated Smad1 (pSmad1) activated by TGF-β. Here, we further validated and confirmed the role of Nedd4 in in vivo vascular calcification progression. First, Nedd4 deletion in SM22α-positive mouse tissues (Nedd4^fl/fl ;SM22α-Cre) showed deformed aortic structures with disarranged elastin fibers at 24 weeks after birth. Second, vitamin D-induced aorta vascular calcification rate in Nedd4^fl/fl ;SM22α-Cre mice was significantly higher than their wild-type littermates. Nedd4^fl/fl ;SM22α-Cre mice showed a development of vascular calcification even at very low-level injection of vitamin D, but this was not exhibited in wild-type littermates. Third, we confirmed that TGF-β1-induced pSmad1 levels were elevated in Nedd4-deficient primary VSMCs isolated from Nedd4^fl/fl ;SM22α-Cre mice. Fourth, we further found that Nedd4^fl/fl ;SM22α-Cre mVSMCs gained mesenchymal cell properties toward osteoblast-like differentiation by a stable isotope labeling in cell culture (SILAC)-based proteomics analysis. Finally, epigenetic analysis revealed that methylation levels of human NEDD4 gene promoter were significantly increased in atherosclerosis patients. Collectively, abnormal expression or dysfunction of Nedd4 E3 ligase could be involved in vascular calcification of VSMCs by activating bone-forming signals during atherosclerosis progression. © 2016 American Society for Bone and Mineral Research.

Eotaxin Augments Calcification in Vascular Smooth Muscle Cells

Calcification of atherosclerotic plaques in elderly patients represents a potent risk marker of cardiovascular events. Plasma analyses of patients with or without calcified plaques reveal significant differences in chemokines, particularly eotaxin, which escalates with increased calcification. We therefore, hypothesize that eotaxin in circulation augments calcification of vascular smooth muscle cells (VSMCs) possibly via oxidative stress in the vasculature. We observe that eotaxin increases the rate of calcification significantly in VSMCs as evidenced by increased alkaline phosphatase activity, calcium deposition, and osteogenic marker expression. In addition, eotaxin promotes proliferation in VSMCs and triggers oxidative stress in a NADPH oxidase dependent manner. These primary novel observations support our proposition that in the vasculature eotaxin augments mineralization. Our findings suggest that eotaxin may represent a potential therapeutic target for prevention of cardiovascular complications in the elderly. J. Cell. Biochem. 118: 647-654, 2017. © 2016 Wiley Periodicals, Inc.

Acute Tissue Mineral Deposition in Response to a Phosphate Pulse in Experimental CKD

Pathogenic accumulation of calcium (Ca) and phosphate (PO₄ ) in vasculature is a sentinel of advancing cardiovascular disease in chronic kidney disease (CKD). This study sought to characterize acute distribution patterns of radiolabeled ³³ PO₄ and ⁴⁵ Ca in cardiovascular tissues of rats with CKD (0.25% dietary adenine). The disposition of ³³ PO₄ and ⁴⁵ Ca was assessed in blood and 36 tissues after a 10-minute intravenous infusion of one of the following: (i) PO₄  pulse + tracer ³³ PO₄ ; (ii) PO₄  pulse + tracer ⁴⁵ Ca; or (iii) saline + tracer ⁴⁵ Ca in CKD and non-CKD animals. After the infusion, ³³ PO₄ in blood was elevated (2.3× at 10 minutes, 3.5× at 30 minutes, p < 0.05) in CKD compared with non-CKD. In contrast, there was no difference in clearance of ⁴⁵ Ca from the blood. Compared with controls, CKD rats had a markedly increased ³³ PO₄ incorporation in several tissues (skeletal muscle, 7.8×; heart, 5.5×), but accrual was most pronounced in the vasculature (24.8×). There was a significant, but smaller, increase in ⁴⁵ Ca accrual in the vasculature of CKD rats (1.25×), particularly in the calcified rat, in response to the acute phosphate load. Based on the pattern of tissue uptake of ³³ PO₄ and ⁴⁵ Ca, this study revealed that an increase in circulating PO₄ is an important stimulus for the accumulation of these minerals in vascular tissue in CKD. This response is further enhanced when vascular calcification is also present. The finding of enhanced vascular mineral deposition in response to an acute PO₄  pulse provides evidence of significant tissue-specific susceptibility to calcification. © 2018 American Society for Bone and Mineral Research.

Bone From Blood: Characteristics and Clinical Implications of Circulating Osteogenic Progenitor (COP) Cells

Circulating osteogenic progenitor (COP) cells are a population of cells in the peripheral blood with the capacity for bone formation, as well as broader differentiation into mesoderm-like cells in vitro. Although some of their biological characteristics are documented in vitro, their role in diseases of the musculoskeletal system remains yet to be fully evaluated. In this review, we provide an overview of the role of COP cells in a number of physiological and pathological conditions, as well as identify areas for future research. In addition, we suggest possible areas for clinical utilization in the management of musculoskeletal diseases. © 2020 American Society for Bone and Mineral Research (ASBMR).

Sixty-Two-Year-Old Male Suffering From Uremic Leontiasis Ossea Caused by Severe Secondary Hyperparathyroidism

Secondary hyperparathyroidism (SHPT) is a long‐term complication of chronic kidney disease–mineral and bone disorder (CKD‐MBD). SHPT is characterized by hyperplasia of the parathyroid glands and abnormal secretion of parathyroid hormones (PTH), calcium and phosphorous metabolic disorders, renal osteodystrophy, vascular and soft tissue calcification, malnutrition, and other multiple system complications, which can seriously affect the quality of life of the patient and increase the risk of cardiovascular disease and mortality rate. Uremic leontiasis ossea (ULO) is a medical condition only rarely encountered clinically. SHPT causes craniofacial bone deformity accompanied by lesions of the nerve, cardiovascular, respiratory, bone, or other systems within the body. The case discussed here is related to severe SHPT. A 62‐year‐old male patient was suffering from leontiasis ossea, pectus excavatum, vascular calcification, spontaneous bone fractures, and lower limb deformities. He was undergoing hemodialysis and given total parathyroidectomy (TPTX) with autotransplantation (AT). We further analyzed the multivariate therapeutic effects of TPTX on this patient in order to provide clinical data for standardized treatment of individuals with CKD‐MBD. © 2018 The Authors JBMR Plus published by Wiley Periodicals, Inc. on behalf of American Society for Bone and Mineral Research.

Low Dentin Matrix Protein 1 Is Associated With Incident Cardiovascular Events in Peritoneal Dialysis Patients

Recent reports demonstrated that dentin matrix protein 1 (DMP1) acts as an inhibitor of vascular calcification and might be a potential biomarker for chronic kidney disease-mineral and bone disorder; however, no clinical investigations regarding DMP1 have been performed in dialysis patients. We investigated the prognostic value of DMP1 on cardiovascular outcomes in prevalent peritoneal dialysis patients. We recruited 223 prevalent peritoneal dialysis patients and divided them into high and low DMP1 groups according to log-transformed plasma DMP1 levels. Lateral lumbar spine radiographs were used for measurement of vascular calcification. Major cardiovascular events were compared between the two groups. A Cox proportional hazards analysis determined DMP1 was independently associated with cardiovascular outcomes. In vitro mouse osteocytes were cultured in media containing indoxyl sulfate (IS), and the expressions of DMP1 were examined. The mean age was 52.1 ± 11.8 years, and 116 (52.0%) patients were male. The median value of log DMP1 was 0.91 (0.32-2.81 ng/mL). The multiple logistic regression analysis indicated that DMP1 levels were independently associated with the presence of vascular calcification after adjustment for multiple confounding factors (odds ratio = 0.719; 95% confidence interval [CI] 0.522-0.989; p = 0.043). During a mean follow-up duration of 34.6 months, incident cardiovascular events were observed in 41 (18.4%) patients. A Kaplan-Meier plot showed that the low DMP1 group had a significantly higher rate of incident cardiovascular events compared with the high DMP1 group (log-rank test, p = 0.026). In addition, multiple Cox analysis showed that low DMP1 was significantly associated with incident cardiovascular events (log 1 increase: hazard ratio = 0.855; 95% CI 0.743-0.984; p = 0.029) after adjustment for multiple confounding factors. In IS-stimulated osteocytes, mRNA and protein expression levels of DMP1 were significantly decreased compared with control osteocytes. We showed that low DMP1 levels were significantly associated with presence of vascular calcification and were independently associated with the incident cardiovascular events in prevalent peritoneal dialysis patients. DMP1 might be a potential factor contributing to cardiovascular complications in dialysis patients. © 2016 American Society for Bone and Mineral Research.

Non-Additive Effects of Combined NOX1/4 Inhibition and Calcimimetic Treatment on a Rat Model of Chronic Kidney Disease-Mineral and Bone Disorder (CKD-MBD)

Chronic kidney disease-mineral and bone disorder (CKD-MBD) increases cardiovascular calcification and skeletal fragility in part by increasing systemic oxidative stress and disrupting mineral homeostasis through secondary hyperparathyroidism. We hypothesized that treatments to reduce reactive oxygen species formation and reduce parathyroid hormone (PTH) levels would have additive beneficial effects to prevent cardiovascular calcification and deleterious bone architecture and mechanics before end-stage kidney disease. To test this hypothesis, we treated a naturally progressive model of CKD-MBD, the Cy/+ rat, beginning early in CKD with the NADPH oxidase (NOX1/4) inhibitor GKT-137831 (GKT), the preclinical analogue of the calcimimetic etelcalcetide, KP-2326 (KP), and their combination. The results demonstrated that CKD animals had elevated blood urea nitrogen, PTH, fibroblast growth factor 23 (FGF23), and phosphorus. Treatment with KP reduced PTH levels compared with CKD animals, whereas GKT treatment increased C-terminal FGF23 levels without altering intact FGF23. GKT treatment alone reduced aortic calcification and NOX4 expression but did not alter the oxidative stress marker 8-OHdG in the serum or aorta. KP treatment reduced aortic 8-OHdG and inhibited the ability for GKT to reduce aortic calcification. Treatments did not alter heart calcification or left ventricular mass. In the skeleton, CKD animals had reduced trabecular bone volume fraction and trabecular number with increased trabecular spacing that were not improved with either treatment. The cortical bone was not altered by CKD or by treatments at this early stage of CKD. These results suggest that GKT reduces aortic calcification while KP reduces aortic oxidative stress and reduces PTH, but the combination was not additive. © 2022 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

Oral Calcitriol Use, Vertebral Fractures, and Vitamin K in Hemodialysis Patients: A Cross-Sectional Study

Fractures and vascular calcifications (VCs) are common in patients with chronic kidney disease (CKD). They are related to abnormalities in vitamin D metabolism, calcium, phosphorus, parathyroid hormone, and fibroblast growth factor 23 (FGF23)/Klotho that occur with CKD. Impaired vitamin D metabolism and abnormal levels of calcium, phosphate, parathyroid hormone (PTH), and FGF23/Klotho drive bone and vascular changes in CKD. It is unclear if oral calcitriol safely mitigates fracture risk without increasing the burden of calcifications. Therefore, we investigated whether treatment with calcitriol affected the prevalence of fractures and VC progression in hemodialysis (HD) patients. This report is a secondary analysis of the Vitamin K Italian (VIKI) study, a cross-sectional study involving 387 HD patients. We assessed vitamin 25(OH)D, alkaline phosphatase, PTH, calcium, phosphate, osteocalcin or bone Gla protein, matrix Gla protein, and vitamin K levels. Vertebral fractures (VFs) and VCs were determined by spine radiograph. A reduction of >20% of vertebral body height was considered a VF. VCs were quantified by the length of calcific lesions along the arteries. The patients treated with oral calcitriol were 177 of 387 patients (45.7%). The prevalence of VF was lower in patients receiving oral calcitriol than in those untreated (48.6% versus 61.0%, p = 0.015), whereas the presence of aortic and iliac calcifications was similar (aortic: 81.9% versus 79.5%, respectively, p = 0.552; iliac: 52.0% and 59.5%, respectively, p = 0.167). In multivariable logistic regression analysis, oral calcitriol was associated with a 40.2% reduced odds of fracture (OR 0.598; 95% confidence interval [CI], 0.363-0.985; p = 0.043). In conclusion, we found a significant association between oral calcitriol and lower VF in HD patients without an increase in the burden of VC. Further prospective and interventional studies are needed to confirm these findings. © 2021 American Society for Bone and Mineral Research (ASBMR).

Machine-Learning Assessed Abdominal Aortic Calcification is Associated with Long-Term Fall and Fracture Risk in Community-Dwelling Older Australian Women

Abdominal aortic calcification (AAC), a recognized measure of advanced vascular disease, is associated with higher cardiovascular risk and poorer long-term prognosis. AAC can be assessed on dual-energy X-ray absorptiometry (DXA)-derived lateral spine images used for vertebral fracture assessment at the time of bone density screening using a validated 24-point scoring method (AAC-24). Previous studies have identified robust associations between AAC-24 score, incident falls, and fractures. However, a major limitation of manual AAC assessment is that it requires a trained expert. Hence, we have developed an automated machine-learning algorithm for assessing AAC-24 scores (ML-AAC24). In this prospective study, we evaluated the association between ML-AAC24 and long-term incident falls and fractures in 1023 community-dwelling older women (mean age, 75 ± 3 years) from the Perth Longitudinal Study of Ageing Women. Over 10 years of follow-up, 253 (24.7%) women experienced a clinical fracture identified via self-report every 4-6 months and verified by X-ray, and 169 (16.5%) women had a fracture hospitalization identified from linked hospital discharge data. Over 14.5 years, 393 (38.4%) women experienced an injurious fall requiring hospitalization identified from linked hospital discharge data. After adjusting for baseline fracture risk, women with moderate to extensive AAC (ML-AAC24 ≥ 2) had a greater risk of clinical fractures (hazard ratio [HR] 1.42; 95% confidence interval [CI], 1.10-1.85) and fall-related hospitalization (HR 1.35; 95% CI, 1.09-1.66), compared to those with low AAC (ML-AAC24 ≤ 1). Similar to manually assessed AAC-24, ML-AAC24 was not associated with fracture hospitalizations. The relative hazard estimates obtained using machine learning were similar to those using manually assessed AAC-24 scores. In conclusion, this novel automated method for assessing AAC, that can be easily and seamlessly captured at the time of bone density testing, has robust associations with long-term incident clinical fractures and injurious falls. However, the performance of the ML-AAC24 algorithm needs to be verified in independent cohorts. © 2023 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).