Severe abdominal aortic calcification in older men is negatively associated with DKK1 serum levels: the STRAMBO study

New Cardiovascular Risk Biomarkers in Rheumatoid Arthritis: Implications and Clinical Utility-A Narrative Review

Rheumatoid arthritis (RA) is a chronic autoimmune disease that not only causes joint inflammation but also significantly increases the risk of cardiovascular disease (CVD), leading to a higher morbidity and mortality. RA patients face an accelerated progression of atherosclerosis, attributed to both traditional cardiovascular risk factors and systemic inflammation. This review focuses on emerging biomarkers for cardiovascular risk assessment in RA, aiming to enhance early detection and treatment strategies. Specifically, we examine the roles of interleukin-32 (IL-32), Dickkopf-1 (DKK-1), galectin-3 (Gal-3), catestatin (CST), and fetuin-A (Fet-A) as potential markers for CVD in this patient population. IL-32, a proinflammatory cytokine, is elevated in RA patients and plays a significant role in inflammation and endothelial dysfunction, both of which contribute to atherosclerosis. DKK-1, a Wnt signaling pathway inhibitor, has been associated with both synovial inflammation and the development of atherosclerotic plaques. Elevated DKK-1 levels have been linked to an increased CV mortality and could serve as a marker for CVD progression in RA. Gal-3 is involved in immune modulation and fibrosis, with elevated levels in RA patients correlating with disease activity and cardiovascular outcomes. Catestatin, a peptide derived from chromogranin A, has protective anti-inflammatory and antioxidative properties, though its role in RA-related CVD remains under investigation. Finally, Fet-A, a glycoprotein involved in vascular calcification, shows potential as a biomarker for CV events in RA, though data on its role remain conflicting. These biomarkers provide deeper insights into the pathophysiology of RA and its cardiovascular comorbidities. Although some biomarkers show promise in improving CV risk stratification, further large-scale studies are required to validate their clinical utility. Currently, these biomarkers are in the research phase and are not yet implemented in standard care. Identifying and incorporating these biomarkers into routine clinical practice could lead to the better management of cardiovascular risk in RA patients, thus improving outcomes in this high-risk population. This review highlights the importance of continued research to establish reliable biomarkers that can aid in both diagnosis and the development of targeted therapies for cardiovascular complications in RA.

Inhibition of vascular calcification by Compound Danshen Dripping Pill through multiple mechanisms

BACKGROUND

Vascular calcification refers to the abnormal accumulation of calcium in the walls of blood vessels and is a risk factor often overlooked in cardiovascular disease. However, there is currently no specific drug for treating vascular calcification. Compound Danshen Dripping Pill (CDDP) is widely used to treat cardiovascular diseases, but its effect on vascular calcification has not been reported.

PURPOSE

We investigated the effects of CDDP on vascular calcification in ApoE-/- mice and in vitro and elucidated its mechanism of action.

STUDY DESIGN

Firstly, we found that CDDP has the potential to improve calcification based on network pharmacology analysis. Then, we performed the following experiments: in vivo, ApoE-/- mice were fed a high-fat diet randomly supplemented with CDDP for 16 weeks. Atherosclerosis and vascular calcification were determined. In vitro, human aortic smooth muscle cells (HASMCs), human umbilical vein endothelial cells (HUVECs), and human aortic endothelial cells (HAECs) were used to determine the mechanisms for CDDP-inhibited vascular calcification.

RESULTS

In this study, we observed that CDDP reduced intimal calcification in atherosclerotic lesions of ApoE-deficient mice fed a high-fat diet, as well as the calcification in cultured SMCs and ECs. Mechanistically, CDDP inhibited the Wnt/β-catenin pathway by up-regulating the expression of DKK1 and LRP6, which are upstream inhibitors of Wnt, leading to a reduction in the expression of osteoblastic transition markers (ALP, OPN, BMP2, and RUNX2). Furthermore, CDDP enhanced the secretion of DKK1, which plays a role in mediating EC-SMC crosstalk in calcification. Additionally, VC contributes to vascular aging by inhibiting Sirt1 and increasing senescence parameters (SA-β-gal, p21, and p16). However, CDDP reversed these changes by activating Sirt1. CDDP also reduced the levels of pro-inflammatory cytokines and the senescence-associated secretory phenotype in vivo and in vitro.

CONCLUSIONS

Our study suggests that CDDP reduces vascular calcification by regulating the DKK1/LRP6/β-catenin signaling pathway in ECs/SMCs and interactions with the crosstalk of ECs and SMCs. It also reduces the senescence of ECs/SMCs, contributing to the Sirt1 activation, indicating CDDP's novel role in ameliorating vascular calcification.

New Emerging Biomarkers for Bone Disease: Sclerostin and Dickkopf-1 (DKK1)

A healthy skeleton depends on a continuous renewal and maintenance of the bone tissue. The process of bone remodeling is highly controlled and consists of a fine-tuned balance between bone formation and bone resorption. Biochemical markers of bone turnover are already in use for monitoring diseases and treatment involving the skeletal system, but novel biomarkers reflecting specific biological processes in bone and interacting tissues may prove useful for diagnostic, prognostic, and monitoring purposes. The Wnt-signaling pathway is one of the most important pathways controlling bone metabolism and consequently the action of inhibitors of the pathway such as sclerostin and Dickkopf-related protein 1 (DKK1) have crucial roles in controlling bone formation and resorption. Thus, they might be potential markers for clinical use as they reflect a number of physiological and pathophysiological events in bone and in the cross-talk with other tissues in the human body. This review focuses on the clinical utility of measurements of circulating sclerostin and DKK1 levels based on preanalytical and analytical considerations and on evidence obtained from published clinical studies. While accumulating evidence points to clear associations with a number of disease states for the two markers, and thus, the potential for especially sclerostin as a biochemical marker that may be used clinically, the lack of standardization or harmonization of the assays still hampers the clinical utility of the markers.

Dickkopf1 (Dkk1) Alleviates Vascular Calcification by Regulating the Degradation of Phospholipase D1 (PLD1)

Vascular calcification (VC) is a significant risk factor for cardiovascular mortality and morbidity in patients with atherosclerosis (AS), chronic kidney disease, and diabetes. Dickkopf1 (Dkk1) is a multifunctional secreted glycoprotein that has been explored as a novel potential antitumor target. Recently, Dkk1 was shown to be closely associated with AS development. However, the role of Dkk1 in VC remains elusive. In this study, we explored the role and molecular mechanisms of Dkk1 in VC based on a smooth muscle-specific Dkk1-knockout (Dkk1SMKO) mouse model. Our data indicated that Dkk1 expression was decreased under calcifying conditions and that Dkk1 overexpression alleviated high phosphate-induced vascular calcification. In vivo, smooth muscle Dkk1-specific knockout aggravated vascular calcification in mice. However, phospholipase D1 (PLD1) overexpression partially weakened the protective effect of Dkk1 against vascular calcification. Mechanistically, Dkk1 slowed vascular calcification by promoting the degradation of PLD1 via the regulating autophagosome formation and maturation. In conclusion, we found that Dkk1 could alleviate vascular calcification by regulating the degradation of PLD1.

A Novel Quantitative Computer-Assisted Score Can Improve Repeatability in the Estimate of Vascular Calcifications at the Abdominal Aorta

In CKD and in the elderly, Vascular Calcifications (VC) are associated to cardiovascular events and bone fractures. VC scores at the abdominal aorta (AA) from lateral spine radiographs are widely applied (the 0-24 semiquantitative discrete visual score (SV) being the most used). We hypothesised that a novel continuum score based on quantitative computer-assisted tracking of calcifications (QC score) can improve the precision of the SV score. This study tested the repeatability and reproducibility of QC score and SV score. In forty-four patients with VC from an earlier study, five experts from four specialties evaluated the data twice using a dedicated software. Test-retest was performed on eight subjects. QC results were reported in a 0-24 scale to readily compare with SV. The QC score showed higher intra-operator repeatability: the 95% CI of Bland-Altman differences was almost halved in QC; intra-operator R2 improved from 0.67 for SV to 0.79 for QC. Inter-observer repeatability was higher for QC score in the first (Intraclass Correlation Coefficient 0.78 vs. 0.64), but not in the second evaluation (0.84 vs. 0.82), indicating a possible heavier learning artefact for SV. The Minimum Detectable Difference (MDD) was smaller for QC (2.98 vs. 4 for SV, in the 0-24 range). Both scores were insensitive to test-retest procedure. Notably, QC and SV scores were discordant: SV showed generally higher values, and an increasing trend of differences with VC severity. In summary, the new QC score improved the precision of lateral spine radiograph scores in estimating VC. We reported for the first time an estimate of MDD in VC assessment that was 25% lower for the new QC score with respect to the usual SV score. An ongoing study will determine whether this lower MDD may reduce follow-up times to check for VC progression.

ERK1/2 inhibition reduces vascular calcification by activating miR-126-3p-DKK1/LRP6 pathway

Rationale: Vascular microcalcification increases the risk of rupture of vulnerable atherosclerotic lesions. Inhibition of ERK1/2 reduces atherosclerosis in animal models while its role in vascular calcification and the underlying mechanisms remains incompletely understood.

Methods: Levels of activated ERK1/2, DKK1, LRP6 and BMP2 in human calcific aortic valves were determined. ApoE deficient mice received ERK1/2 inhibitor (U0126) treatment, followed by determination of atherosclerosis, calcification and miR-126-3p production. C57BL/6J mice were used to determine the effect of U0126 on Vitamin D₃ (VD₃)-induced medial arterial calcification. HUVECs, HAECs and HASMCs were used to determine the effects of ERK1/2 inhibitor or siRNA on SMC calcification and the involved mechanisms.

Results: We observed the calcification in human aortic valves was positively correlated to ERK1/2 activity. At cellular and animal levels, U0126 reduced intimal calcification in atherosclerotic lesions of high-fat diet-fed apoE deficient mice, medial arterial calcification in VD₃-treated C57BL/6J mice, and calcification in cultured SMCs and arterial rings. The reduction of calcification was attributed to ERK1/2 inhibition-reduced expression of ALP, BMP2 and RUNX2 by activating DKK1 and LRP6 expression, and consequently inactivating both canonical and non-canonical Wnt signaling pathways in SMCs. Furthermore, we determined ERK1/2 inhibition activated miR-126-3p production by facilitating its maturation through activation of AMPKα-mediated p53 phosphorylation, and the activated miR-126-3p from ECs and SMCs played a key role in anti-vascular calcification actions of ERK1/2 inhibition.

Conclusions: Our study demonstrates that activation of miR-126-3p production in ECs/SMCs and interactions between ECs and SMCs play an important role in reduction of vascular calcification by ERK1/2 inhibition.

The Interplay of WNT and PPARγ Signaling in Vascular Calcification

Vascular calcification (VC), the ectopic deposition of calcium phosphate crystals in the vessel wall, is one of the primary contributors to cardiovascular death. The pathology of VC is determined by vascular topography, pre-existing diseases, and our genetic heritage. VC evolves from inflammation, mediated by macrophages, and from the osteochondrogenic transition of vascular smooth muscle cells (VSMC) in the atherosclerotic plaque. This pathologic transition partly resembles endochondral ossification, involving the chronologically ordered activation of the β-catenin-independent and -dependent Wingless and Int-1 (WNT) pathways and the termination of peroxisome proliferator-activated receptor γ (PPARγ) signal transduction. Several atherosclerotic plaque studies confirmed the differential activity of PPARγ and the WNT signaling pathways in VC. Notably, the actively regulated β-catenin-dependent and -independent WNT signals increase the osteochondrogenic transformation of VSMC through the up-regulation of the osteochondrogenic transcription factors SRY-box transcription factor 9 (SOX9) and runt-related transcription factor 2 (RUNX2). In addition, we have reported studies showing that WNT signaling pathways may be antagonized by PPARγ activation via the expression of different families of WNT inhibitors and through its direct interaction with β-catenin. In this review, we summarize the existing knowledge on WNT and PPARγ signaling and their interplay during the osteochondrogenic differentiation of VSMC in VC. Finally, we discuss knowledge gaps on this interplay and its possible clinical impact.

Association between Serum Dickkopf-1 (DKK-1) Glycoprotein and Calcific Deposits on Cardiac Valves and Carotid Intimal-Medial Thickness in Hemodialysis Patients

BACKGROUND

Cardiac valve calcification (CVC) is common in hemodialysis (HD) patients, and associated with cardiovascular and all-cause mortality. Once believed to be a passive process, it is now understood that the Wnt signaling pathway has a major role. The aim of the current study was to assess the relationship between circulating DKK-1, a negative regulator of the Wnt signaling pathway, and CVC, as well as carotid intimal-medial thickness (CIMT) in HD patients.

METHODS

We enrolled 74 consecutive adults on maintenance HD. Echocardiographic calcification of the mitral valve (MV) and aortic valve (AV) were detected according to Wilkins score (range 0-4), and the study of Tenenbaum et al. [Int J Cardiol. 2004 Mar;94(1):7-13] (range 0-4), respectively. CVC severity was calculated by a supposed score (range 0-8) that represents the sum of calcification grade of MV and AV. CVC severity was classified into absent (CVC score = 0), mild (CVC score = 1-2), moderate (CVC score = 3-4), and severe (CVC score ≥5). Demographic and biochemical data were collected in addition to serum DKK-1 levels and CIMT.

RESULTS

CVC was present in 67 patients (91.0%). There was a highly significant negative correlation between serum DKK-1 level and CVC score (r = -0.492; p ≤ 0.001), as well as CIMT (r = -0.611; p ≤ 0.001). Age and CIMT were independent determinants of CVC.

CONCLUSIONS

CVC is almost present in all HD patients. DKK-1 seems to have a direct relation with CVC and CIMT in HD patients. Age is the strongest independent determinant of CVC.

Serum Sclerostin But Not DKK-1 Correlated with Central Arterial Stiffness in End Stage Renal Disease Patients

Sclerostin and dickkopf-1 (DKK1) played a role in the development of cardiovascular diseases and arterial stiffness in chronic kidney disease (CKD) patients but with controversial results of patients in end-stage renal disease (ESRD) including hemodialysis (HD) and peritoneal dialysis (PD). This study aimed to examine the association between the mode of dialysis or the values of sclerostin or DKK1 and carotid-femoral pulse wave velocity (cfPWV) in ESRD patients. There were 122 HD and 72 PD patients enrolled in this study. By a validated tonometry system, cfPWV was measured and then segregated patients into values of >10 m/s as the high central arterial stiffness (AS) group and values ≤ 10 m/s as the control group. Serum levels of sclerostin and DKK1 were measured using a commercial enzyme-linked immunosorbent assay kit. Possible risk factors for the development of AS were analyzed by logistic regression analysis. There were 21 (29.2%) of PD and 53 (43.4%) of HD in the high AS group. Compared to patients in the control group, those in the high AS group were older, had more comorbidities, had higher systolic blood pressure, and had higher serum levels of fasting glucose, C-reactive protein, and sclerostin. Levels of sclerostin (adjusted OR 1.012, 95% CI. 1.006–1.017, p = 0.0001) was found to be an independent predictor of high AS in ESRD patients by multivariate logistic regression analysis. Furthermore, receiver operating characteristic curve analysis showed the optimal cut-off values of sclerostin for predicting AS was 208.64 pmol/L (Area under the curve 0.673, 95% CI: 0.603–0.739, p < 0.001). This study showed that serum levels of sclerostin, but not DKK1 or mode of dialysis, to be a predictor for high central AS in ESRD patients.

Improved carotid intima-media thickness-induced high-intensity interval training associated with decreased serum levels of Dkk-1 and sclerostin in type 2 diabetes

AIMS

Carotid intima-media thickness (cIMT) is a validated surrogate marker of atherosclerosis. Dickkopf-1 (Dkk-1) and sclerostin modulate wingless signaling, which is involved in atherosclerosis. The purpose of this study was to investigate whether 12 weeks of high-intensity interval training (HIIT) would improve cIMT and serum Dkk-1 and sclerostin levels in patients with type 2 diabetes.

METHODS

Seventy-four sedentary patients with type 2 diabetes were randomly divided into HIIT and control groups. The HIIT group intervention was 6 intervals (4 min) at 85%-90% HR_max separated by 3 min at 45%-50% HR_max in 3 sessions/week for 12 weeks. Before and after the intervention, cIMT, artery diameter and wall/lm ratio were recorded with high-resolution ultrasound. Serum sclerostin and Dkk-1 were measured by enzyme-linked immunosorbent assay (ELISA).

RESULTS

cIMT decreased significantly in the HIIT group (0.83 ± 0.17 baseline, 0.71 ± 0.14 follow-up) compared to the control group (0.84 ± 0.20 baseline, 0.85 ± 0.19 follow-up) (P < .05). Dkk-1 and sclerostin decreased significantly after 12 weeks of HIIT (P < .01). In addition, VO_2peak was increased in the HIIT group than the control group (by 6.2 mL/kg/min) (P < .05). There was a positive correlation between percent changes in cIMT and percent changes in Dkk-1 and sclerostin (both P < .01). Additionally, there were a negative correlation between percent changes VO2peak and cIMT (r = - 0.740, P = .003), Dkk-1 (r = - 0.844, P < .001) and sclerostin (r = - 0.575, P = .001) in HIIT group.

CONCLUSION

Our results indicate that HIIT decreases cIMT, serum levels of Dkk-1 and sclerostin and improves VO_2peak in patients with type 2 diabetes.

Dkk (Dickkopf) Proteins

Clinical and preclinical studies over the past 3 decades have uncovered a multitude of signaling pathways involved in the initiation and progression of atherosclerosis. From these studies, signaling by proteins of the Wnt family has recently emerged as an important player in the development of atherosclerosis. Wnt signaling is characterized by a large number of ligands, receptors, and coreceptors and can be regulated at many different levels. Among Wnt modulators, the evolutionary conserved Dkk (Dickkopf) proteins, and especially Dkk-1, the founding member of the family, are the best characterized. The role of Dkks in the pathophysiology of the arterial wall is only partially understood, but their involvement in atherosclerosis is becoming increasingly evident. This review introduces recent key findings on Dkk proteins and their functions in atherosclerosis and discusses the potential importance of modulating Dkk signaling as part of a novel, improved strategy for preventing and treating atherosclerosis-related diseases.

Visual Overview—

An online visual overview is available for this article.

Dickkopf1: An immunomodulatory ligand and Wnt antagonist in pathological inflammation

The Wnt signaling pathway plays essential roles in tissue or organ homeostasis by regulating cell proliferation and differentiation. Upon tissue or organ injury, inflammation is coupled with tissue repair and regeneration process. The canonical Wnt signaling transduction pathway is crucial for cell proliferation, cell differentiation, and tissue regeneration. Dickkopf1 (DKK1) is a quintessential Wnt antagonist that inhibits the Wnt-mediated tissue repair process. Recent studies reported increased levels of DKK1 in many diseases such as cancer, infection, and musculoskeletal diseases. In many cases, the role of DKK1 has been identified as a pro-inflammatory ligand and the expression levels are associated with poor disease outcomes. A variety of cell types including platelets, endothelial cells, and cancer cells secrete DKK1 upon stimuli. This puts DKK1 in a unique place to view immune responses from multicellular interactions in tissue injury and repair process. In this review, we discuss recent efforts to address the underlying mechanism regarding the pro-inflammatory role of DKK1 in cancer, bone diseases, and other inflammatory diseases.

Clinical advantages and disadvantages of anabolic bone therapies targeting the WNT pathway

The WNT signalling pathway is a key regulator of bone metabolism, particularly bone formation, which has helped to define the role of osteocytes - the most abundant bone cells - as orchestrators of bone remodelling. Several molecules involved in the control of the WNT signalling pathway have been identified as potential targets for the development of bone-building therapeutics for patients with osteoporosis. Several of these molecules have been investigated in animal models, but only inhibitors of sclerostin (which is produced by osteocytes) have been investigated in phase III clinical studies. Here, we review the rationale for these developments and the specificity and potential off-target actions of WNT-based therapeutics. We also describe the available preclinical and clinical studies and discuss the benefits and risks of using sclerostin inhibitors for the management of patients with osteoporosis.

TGF-Beta Signaling in Bone with Chronic Kidney Disease

Transforming growth factor (TGF)-β signaling is not only important in skeletal development, but also essential in bone remodeling in adult bone. The bone remodeling process involves integrated cell activities induced by multiple stimuli to balance bone resorption and bone formation. TGF-β plays a role in bone remodeling by coordinating cell activities to maintain bone homeostasis. However, mineral metabolism disturbance in chronic kidney disease (CKD) results in abnormal bone remodeling, which leads to ectopic calcification in CKD. High circulating levels of humoral factors such as parathyroid hormone, fibroblast growth factor 23, and Wnt inhibitors modulate bone remodeling in CKD. Several reports have revealed that TGF-β is involved in the production and functions of these factors in bone. TGF-β may act as a factor that mediates abnormal bone remodeling in CKD.

Bone metabolism in patients with anorexia nervosa and amenorrhoea

PURPOSE

Aim of this study is focusing on bone metabolism in AN patients with amenorrhoea and related estrogen deficiency effects.

METHODS

AN patients were compared both with healthy females and with postmenopausal women (reference model for estrogen deficiency). The study sample included 81 females with AN. Laboratory tests [25-OH vitamin D, bone turnover markers, intact parathyroid hormone, sclerostin (SOST) and dickkopf-related protein (DKK1)] and dual energy X-ray absorptiometry (DXA) were taken into account.

RESULTS

AN patients had higher levels of C-terminal telopeptide of type I collagen (CTX) than both control groups. AN adolescents had CTX higher than AN young adults. In postmenopausal women, intact N-propeptide of type I collagen was higher if compared with each other group. In AN groups, Dickkopf-related protein 1 was significantly lower than the two control groups. No differences were found in sclerostin except in adolescents. In AN adolescents, DXA values at femoral sites were higher than in AN young adults and a positive correlation was found with body weight (p < 0.01) and with fat mass evaluated using DXA (p < 0.01).

CONCLUSIONS

AN women with amenorrhoea have an increased bone resorption like postmenopausal women but bone formation is depressed. The consequent remodeling uncoupling is considerably more severe than that occurring after menopause.

Prediction of Fractures and Major Cardiovascular Events in Men Using Serum Osteoprotegerin Levels: The Prospective STRAMBO Study

Fragility fractures and cardiovascular diseases often coincide. However, data on shared risk factors and markers are scarce. Our aim was to assess the independent associations of serum osteoprotegerin (OPG) levels with the risk of fracture and cardiovascular outcomes (acute coronary syndrome, cardiac death) in older men. A cohort of 819 home-dwelling men aged 60 to 87 years was followed prospectively for 8 years. Serum OPG was measured at baseline by ELISA. Bone mineral density (BMD) at femoral neck and Trabecular Bone Score (TBS) were assessed by DXA. Clinical risk factors and Fracture Risk Assessment Tool (FRAX) were assessed. The incident events (self-reported peripheral fractures and acute coronary syndrome, cardiac death reported by a proxy) confirmed by a health professional were retained for the statistical analysis. Incident vertebral fractures were assessed on lateral DXA scans after 4 and 8 years. Hazard risk (HR) was assessed using the Cox model. After adjustment for FRAX corrected for femoral neck BMD and TBS, diabetes mellitus, ischemic heart disease, and prior falls, the risk of fracture was twofold higher in the highest versus the lowest OPG quartile (HR 2.35; 95% CI, 1.35 to 4.10). The risk of vertebral and nonvertebral fracture was higher in the highest versus the lowest OPG quartile (OR 2.76 [95% CI, 1.08 to 7.05] and HR 2.46 [95% CI, 1.23 to 4.92]). The risk of major osteoporotic fracture was higher in the fourth versus the first OPG quartile (HR 2.43; 95% CI, 1.16 to 5.10). The risk of cardiovascular outcome (adjusted for confounders) was higher in the highest versus the lowest OPG quartile (HR 3.93; 95% CI, 1.54 to 10.04). The risk of fracture and cardiovascular outcome was higher in the highest OPG quartile versus the lower quartiles combined (HR 2.06 [95% CI, 1.35 to 3.14] and HR 2.98 [95% CI, 1.60 to 5.54], respectively). In conclusion, in older men, higher serum OPG levels represent an independent risk factor for cardiovascular and fracture risk. © 2017 American Society for Bone and Mineral Research.

Association of Circulating Wnt Antagonists With Severe Abdominal Aortic Calcification in Elderly Women

Context

There is great interest in the biology of vascular calcification. Wnt/β-catenin signaling is an important mediator of mineralization and may play a role in vascular calcification.

Objective

We assessed the association between circulating Wnt antagonists and abdominal aortic calcification (AAC) severity in elderly women.

Design

This was a cross-sectional analysis of the Calcium Intake Fracture Outcome Study.

Setting

The participants were recruited from the community-dwelling elderly population.

Participants

We examined 768 women aged over 70 years.

Interventions

We collected blood samples, and lateral spine images captured during bone density assessment were used to score AAC with a validated 24-point scale.

Main Outcome Measures

We tested the hypothesis that low Wnt antagonist levels of Dickkopf-1 (DKK1), secreted frizzled related protein 3 (sFRP3), and Wnt inhibitory factor 1 (WIF1) are associated with severe AAC (AAC24 score > 5).

Results

Severe AAC was present in 146 women (19%). Lower levels of DKK1, but not WIF1 and sFRP3, were associated with higher odds of severe AAC. Per standard deviation decrease in DKK1 was associated with increased multivariable-adjusted odds ratio (OR) of severe AAC [OR, 1.26; 95% confidence interval (CI), 1.04 to 1.52; P = 0.017]. In quartile analyses, the lowest and second-lowest quartiles of DKK1 had increased multivariable-adjusted odds of severe AAC vs the highest quartile (OR, 2.05; 95% CI, 1.18 to 3.56; P = 0.011 and OR, 1.83; 95% CI, 1.05 to 3.19; P = 0.035).

Conclusions

In elderly women, DKK1, but not sFRP3 or WIF1, is associated with severe AAC. This study supports the concept that Wnt/β-catenin signaling is an important regulator of vascular mineral metabolism and is independent of other risk factors.

Cigarette Smoking-Induced Cardiac Hypertrophy, Vascular Inflammation and Injury Are Attenuated by Antioxidant Supplementation in an Animal Model

Background: Cardiovascular diseases are the leading causes of morbidity and mortality worldwide. Cigarette smoking remains a global health epidemic with associated detrimental effects on the cardiovascular system. In this work, we investigated the effects of cigarette smoke exposure on cardiovascular system in an animal model. The study then evaluated the effects of antioxidants (AO), represented by pomegranate juice, on cigarette smoke induced cardiovascular injury. This study aims at evaluating the effect of pomegranate juice supplementation on the cardiovascular system of an experimental rat model of smoke exposure.

Methods: Adult rats were divided into four different groups: Control, Cigarette smoking (CS), AO, and CS + AO. Cigarette smoke exposure was for 4 weeks (5 days of exposure/week) and AO group received pomegranate juice while other groups received placebo. Assessment of cardiovascular injury was documented by assessing different parameters of cardiovascular injury mediators including: (1) cardiac hypertrophy, (2) oxidative stress, (3) expression of inflammatory markers, (4) expression of Bradykinin receptor 1 (Bdkrb1), Bradykinin receptor 2 (Bdkrb2), and (5) altered expression of fibrotic/atherogenic markers [(Fibronectin (Fn1) and leptin receptor (ObR))].

Results: Data from this work demonstrated that cigarette smoke exposure induced cardiac hypertrophy, which was reduced upon administration of pomegranate in CS + AO group. Cigarette smoke exposure was associated with elevation in oxidative stress, significant increase in the expression of IL-1β, TNFα, Fn1, and ObR in rat's aorta. In addition, an increase in aortic calcification was observed after 1 month of cigarette smoke exposure. Furthermore, cigarette smoke induced a significant up regulation in Bdkrb1 expression level. Finally, pomegranate supplementation exhibited cardiovascular protection assessed by the above findings and partly contributed to ameliorating cardiac hypertrophy in cigarette smoke exposed animals.

Conclusion: Findings from this work showed that cigarette smoking exposure is associated with significant cardiovascular pathology such as cardiac hypertrophy, inflammation, pro-fibrotic, and atherogenic markers and aortic calcification in an animal model as assessed 1 month post exposure. Antioxidant supplementation prevented cardiac hypertrophy and attenuated indicators of atherosclerosis markers associated with cigarette smoke exposure.

Lower leg arterial calcification assessed by high-resolution peripheral quantitative computed tomography is associated with bone microstructure abnormalities in women

In older women, the presence of lower leg arterial calcification assessed by high-resolution peripheral quantitative computed tomography is associated with relevant bone microstructure abnormalities at the distal tibia and distal radius.

INTRODUCTION

Here, we report the relationships of bone geometry, volumetric bone mineral density (BMD) and bone microarchitecture with lower leg arterial calcification (LLAC) as assessed by high-resolution peripheral quantitative computed tomography (HR-pQCT).

METHODS

We utilized the Hertfordshire Cohort Study (HCS), where we were able to study associations between measures obtained from HR-pQCT of the distal radius and distal tibia in 341 participants with or without LLAC. Statistical analyses were performed separately for women and men. We used linear regression models to investigate the cross-sectional relationships between LLAC and bone parameters.

RESULTS

The mean (SD) age of participants was 76.4 (2.6) and 76.1 (2.5) years in women and men, respectively. One hundred and eleven of 341 participants (32.6 %) had LLAC that were visible and quantifiable by HR-pQCT. The prevalence of LLAC was higher in men than in women (46.4 % (n = 83) vs. 17.3 % (n = 28), p < 0.001). After adjustment for confounding factors, we found that women with LLAC had substantially lower Ct.area (β = -0.33, p = 0.016), lower Tb.N (β = -0.54, p = 0.013) and higher Tb.Sp (β = 0.54, p = 0.012) at the distal tibia and lower Tb.Th (β = -0.49, p = 0.027) at the distal radius compared with participants without LLAC. Distal radial or tibial bone parameter analyses in men according to their LLAC status revealed no significant differences with the exception of Tb.N (β = 0.27, p = 0.035) at the distal tibia.

CONCLUSION

In the HCS, the presence of LLAC assessed by HR-pQCT was associated with relevant bone microstructure abnormalities in women. These findings need to be replicated and further research should study possible pathophysiological links between vascular calcification and osteoporosis.

Serum levels of Dkk-1, sclerostin and VEGF in patients with ankylosing spondylitis and their association with smoking, and clinical, inflammatory and radiographic parameters

OBJECTIVE

To evaluate serum Dickkopf-1 (Dkk-1), sclerostin and vascular endothelial growth factor (VEGF) levels in patients with ankylosing spondylitis (AS) compared to healthy controls as well as their association with smoking, and clinical, inflammatory and radiographic parameters.

METHODS

Serum samples for total Dkk-1, sclerostin and VEGF were obtained from 57 tumour necrosis factor (TNF) inhibitor naïve patients with AS and 34 sex-, age- and body mass index (BMI)-matched controls. The erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), Bath AS Disease Activity Index (BASDAI), Bath AS Functional Index (BASFI), modified Stroke AS Spine Score (mSASSS) and smoking status were assessed for each patient.

RESULTS

There was no significant difference in serum bone metabolism markers between AS patients and controls. Dkk-1 levels were significantly (P<0.05) higher in AS patients with elevated ESR and CRP and no syndesmophytes, and were significantly (P<0.001) correlated with sclerostin levels (r=0.592). VEGF levels were significantly (P<0.05) higher in AS patients with current and ever smoking, elevated ESR and CRP, and high BASDAI and BASFI, and were significantly (P<0.05) correlated with ESR (r=0.284), CRP (r=0.285), BASDAI (r=0.349) and BASFI (r=0.275). In multivariate regression analyses, high Dkk-1 levels were significantly (P≤0.001) associated with elevated ESR and CRP, no syndesmophytes and high sclerostin levels, and high VEGF levels significantly (P<0.05) with ever smoking, and elevated ESR and CRP.

CONCLUSION

In AS, serum Dkk-1 concentrations appear to be related not only to syndesmophyte formation but also to systemic inflammation. Furthermore, high VEGF levels may be associated with smoking exposure.

Association of bone-derived biomarkers with vascular calcification in chronic hemodialysis patients

BACKGROUND

Abdominal aortic calcification (AAC) is commonly observed in chronic dialysis patients and is associated with cardiovascular and all-cause mortality. We investigated the factors associated with AAC and analyze the relationship between bone-derived biomarkers and AAC.

METHODS

We enrolled 227 stable hemodialysis patients. Vascular calcifications were assessed using lateral lumbar radiography of the abdominal aorta. Demographic data were collected and serum levels of biochemical and bone-derived biomarkers, including sclerostin, Dickkopf-1 (DKK-1), and fibroblast growth factor 23 (FGF23), were measured.

RESULTS

One hundred sixty-one patients (71.0%) had AAC. Patients with AAC score≧13 were older, with higher body mass index (BMI), serum calcium, calcium phosphate product, high-sensitivity C-reactive protein (hsCRP), and FGF23 levels. Sclerostin and DKK-1 levels were inversely associated with AAC severity, and FGF23 was directly related to vascular calcification. Hypertension, vascular disease, hsCRP, FGF23, and sclerostin were independent AAC determinants.

CONCLUSIONS

Chronic hemodialysis patients have a high prevalence of vascular calcifications. Levels of circulating sclerostin, DKK-1, and FGF23 were related to AAC severity. Sclerostin and FGF23 were independently associated with AAC.

Serum fetuin-A levels and abdominal aortic calcification in healthy men - The STRAMBO study

Vascular calcification results from an imbalance between increased extracellular levels of calcium and phosphate, reduced solubility, and low levels of calcification inhibitors in blood or the vascular wall. Fetuin-A is a major circulating calcification inhibitor. Rodent models of fetuin-A deficit indicate its calcification inhibiting potential. Clinical studies suggest its role as a biomarker in vascular disease. This cross-sectional study was performed in a cohort of 974 men aged ≥ 40 years (average 68 years) consisting of men holding health insurance cover with Mutuelle des Travailleurs de la Région Lyonnaise. Abdominal aortic calcification (AAC) was assessed semi-quantitatively on lateral dual energy X-ray absorptiometry (DXA) spine scans. Serum fetuin-A was measured by an immunoassay. After adjustment for confounders (age, lifestyle, body composition, health status, treatment, glomerular filtration rate [GFR], hormones, and cytokines), prevalence of severe AAC (AAC score>4) decreased with increasing fetuin-A levels (OR=0.68 per SD increase, 95% CI: 0.54-0.84, p<0.001). After adjustment for confounders, low fetuin-A and hypertension were each associated with higher odds of AAC>4. Coexistence of low serum fetuin-A levels and heavy smoking, elevated fibroblast growth factor 23 levels or low serum dickkopf-1 levels were associated with higher odds of AAC>4. Similar results were obtained for 789 men with GFR>60 mL/min/1.73 m(2). Similar results were obtained when severe AAC was defined as AAC score >3 or AAC>5. Thus, lower serum fetuin-A levels are associated with severe AAC, suggesting that poor calcification inhibitory potential contributes to vascular calcification, independently of renal impairment.

Ischemic heart disease is associated with lower cortical volumetric bone mineral density of distal radius

In this study, high-resolution peripheral quantitative computed tomography (HR-pQCT) was used to investigate geometric, volumetric and microstructural parameters at the distal radius and at the distal tibia in participants with ischaemic heart disease. We found that, compared with participants without ischaemic heart disease, they had substantially lower cortical volumetric bone mineral density (BMD) at the distal radius.

INTRODUCTION

HR-pQCT captures novel aspects of bone geometry and volumetric bone mineral density (vBMD) and offers the ability to measure bone microarchitecture, but data relating measures obtained from this technique in patients with ischemic heart disease (IHD) are lacking.

METHODS

Here, we report an analysis from the Hertfordshire Cohort Study, where we were able to study associations between measures obtained from HR-pQCT of distal radius and distal tibia in 350 participants (184 men and 166 women) aged 71.5-80.5 years with or without IHD (e.g. heart attack, angina or heart failure; n = 75 and n = 275, respectively).

RESULTS

Analyses for all participants (men and women together) revealed that cortical vBMD (Ct.vBMD) was lower (p < 0.001) and cortical thickness (Ct.th) was not different (p = 0.519), whereas cortical porosity (Ct.Po) was higher (p = 0.016) in participants with IHD at the distal radius. Moreover, trabecular microarchitectural parameters were not significantly different in patients with IHD (p > 0.05 for all). Adjustment for a priori confounders (age, gender, body mass index, smoking status, alcohol consumption, high blood pressure and diabetes mellitus) did not materially affect the relationship described for Ct.vBMD (p = 0.002), but differences in Ct.Po were attenuated. Analyses in men alone revealed that only Ct.vBMD was lower at the distal radius in participants with IHD with and without adjustment for a priori confounders (p = 0.0002 and p = 0.004, respectively), whereas no statistical differences were found in women, although patterns of differences were similar in both sexes. Moreover, no association was found between IHD and bone parameters at the distal tibia either in men or women.

CONCLUSIONS

We have demonstrated that IHD is associated with lower Ct.vBMD of the distal radius.

Sclerostin and DKK1: new players in renal bone and vascular disease

For more than a decade, the Wnt-β-catenin pathway has been the focus of intense basic and clinical research in the bone field because of its importance in skeletal development and maintenance of bone mass. Wnt activation increases bone formation and decreases bone resorption. The Wnt-β-catenin signaling pathway is tightly regulated by several inhibitors, among which Dickkopf-related protein 1 (DKK1) and sclerostin have been most comprehensively studied. Mounting evidence indicates that a disturbed Wnt-β-catenin signaling is also implicated in the pathogenesis of the chronic kidney disease-associated bone and mineral disorder (CKD-MBD) and affects its various components. DKK1 and sclerostin, more specifically, may be involved in the intense cross-talk between the kidneys, vasculature, and bone. Studies exploring clinical correlates of circulating sclerostin and DKK1 levels so far yielded conflicting results. Biological variability and analytical issues account at least partly for this inconsistency. Antibodies neutralizing Wnt inhibitors may be an appealing strategy to prevent or treat CKD-MBD. Caution is however warranted as sclerostin not only opposes mineralization in the bone but possibly also in the vasculature. Additional studies are required to define determinants of Wnt inhibitors in CKD and to evaluate the efficacy and safety of recently introduced pharmaceuticals targeting these inhibitors.

Circulating dickkopf-1 in diabetes mellitus: association with platelet activation and effects of improved metabolic control and low-dose aspirin

Background

Dickkopf‐1 (DKK‐1) is a major regulator of the Wnt signaling pathway, involved in inflammation, atherogenesis, and the regulation of glucose metabolism. Because platelets are major contributors to circulating levels of DKK‐1 in other clinical settings, we aimed at characterizing the platelet contribution to DKK‐1 in type 2 diabetes mellitus (T2DM) and evaluating associations of DKK‐1 with glucose metabolism, platelet activation, and endothelial dysfunction.

Methods and Results

A cross‐sectional comparison of DKK‐1, soluble CD40L (sCD40L; reflecting platelet‐mediated inflammation), asymmetric dimethylarginine (ADMA; marker of endothelial dysfunction), and urinary 11‐dehydro‐thromboxane B₂ (in vivo marker of platelet activation) was performed among 214 diabetic patients (90 receiving aspirin at 100 mg/day) and 30 healthy controls. Plasma DKK‐1 levels were markedly higher in patients with T2DM than in healthy patients (P<0.0001). DKK‐1 levels were significantly lower in diabetic patients receiving compared with those not on aspirin treatment (P=0.008); in the latter, DKK‐1 was significantly correlated with 11‐dehydro‐thromboxane B₂, ADMA, and CD40L (ρ=0.303. P<0.0001, ρ=0.45. P<0.0001, and ρ=0.37, P<0.0001, respectively) but not with glycemic control or DM duration. Among patients not receiving aspirin, improvement of metabolic control in a subgroup of newly diagnosed patients treated with acarbose for 20 weeks and in a group treated with rosiglitazone for 24 weeks was associated with concurrent significant reductions in DKK‐1 (P=0.005 and P=0.004) and 11‐dehydro‐thromboxane B₂ (P=0.005 and P=0.004).

Conclusions

Circulating DKK‐1 is increased in T2DM and associated with endothelial dysfunction and platelet activation. Plasma DKK‐1 levels are reduced with improvement of glycemic control and low‐dose aspirin treatment.