Role of Sclerostin in Cardiovascular Disease

Localized delivery of anti-inflammatory agents using extracellular matrix-nanostructured lipid carriers hydrogel promotes cardiac repair post-myocardial infarction

A challenge in treating cardiac injury is the low heart-specificity of the drugs. Nanostructured lipid carriers (NLCs) are a relatively new format of lipid nanoparticles which have been used to deliver RNA and drugs. However, lipid nanoparticles exhibit higher affinity to the liver than the heart. To improve the delivery efficiency of NLCs into the heart, NLCs can be embedded into a scaffold and be locally released. In this study, a cardiac extracellular matrix (ECM) hydrogel-NLC composite was developed as a platform for cardiac repair. ECM-NLC composite gels at physiological conditions and releases payloads into the heart over weeks. ECM-NLC hydrogel carrying colchicine, an anti-inflammation agent, improved cardiac repair after myocardial infarction in mice. Transcriptome analysis indicated that Egfr downstream effectors participated in ECM-NLC-colchicine induced heart repair. In conclusion, ECM-NLC hydrogel is a potential platform for sustained and localized delivery of biomolecules into the heart, and loading appropriate medicines further increases the therapeutic efficacy of ECM-NLC hydrogel for cardiovascular diseases.

Sclerostin and Cardiovascular Disease

PURPOSE OF REVIEW

The role of wnt signalling in atherogenesis raises the possibility that the wnt inhibitor, sclerostin, provides a natural defence to this process, and that anti-sclerostin antibodies might increase the risk of atherosclerosis and associated conditions such as CVD. This article aims to triangulate evidence concerning possible adverse effects of sclerostin inhibition on CVD risk.

RECENT FINDINGS

Randomised controlled trials of treatment with the anti-sclerostin antibody, romosozumab, have yielded conflicting evidence with respect to possible adverse effects of sclerostin inhibition on CVD risk. To further examine the causal relationship between sclerostin inhibition and CVD risk, three Mendelian randomisation (MR) studies have examined effects of sclerostin lowering on CVD outcomes, using common genetic variants in the SOST gene which produces sclerostin, to mimic effects of a randomised trial. Concordant findings were seen in two studies, comprising an effect of sclerostin lowering on increased risk of MI and type II diabetes mellitus. One study also suggested that sclerostin lowering increases coronary artery calcification. Triangulation of evidence from different sources provides some suggestion that sclerostin lowering increases MI risk, supporting the need for CVD risk assessment when considering treatment with romosozumab.

Anti-sclerostin antibodies: a new frontier in fragility fractures treatment

Bone fragility is the determinant of the increased risk of minimal trauma fracture and must be treated with a multimodal approach that includes pharmacological therapy, physical exercise, and adequate nutrition. Pharmacological therapy, to date based on the administration of antiresorptive drugs, such as bisphosphonates and denosumab, or osteoanabolic drugs, such as teriparatide and abaloparatide, has shown to be effective in reducing the risk of fracture in osteoporotic patients. In the context of the cellular and molecular mechanisms that regulate bone metabolism, the discovery of the Wnt signaling pathway and its role in bone tissue homeostasis has allowed the identification of sclerostin as an inhibitor of osteoblastic activity and simultaneously as a stimulator of osteoclastic activity. Therefore, the use of a monoclonal antibody, romosozumab, against this protein has been tested as a potential drug with a dual action, stimulating bone neo-apposition and inhibiting bone resorption. The efficacy of romosozumab has been demonstrated in numerous clinical trials against both placebo and other drugs commonly used in the treatment of patients affected by osteoporosis. The advantages of this drug lie above all in its rapid action which makes it particularly suitable in clinical situations where it is necessary to improve bone strength very quickly due to the imminent risk of fragility fracture. Clinical studies and guidelines suggest romosozumab as an initial drug in an ideal sequential approach from osteoanabolic to antiresorptive drugs. Some aspects of cardiovascular safety remain to be fully investigated, therefore its use in osteoporotic patients at high cardiovascular risk should be avoided until further data become available.

Sustained release of a highly specific GSK3β inhibitor SB216763 in the PCL scaffold creates an osteogenic niche for osteogenesis, anti-adipogenesis, and potential angiogenesis

The safe and effective use of Wnt signaling is a hot topic in developing osteogenic drugs. SB216763 (S33) is a widely used highly specific GSK3β inhibitor. Here, we show that S33 initiates canonical Wnt signaling by inhibiting GSK3β activity in the bone marrow stromal cell line ST2 and increases osteoblast marker alkaline phosphatase activity, osteoblast marker gene expression including Alpl, Col1α1, and Runx2, promoting osteogenic differentiation and mineralization of ST2 cells. In addition, S33 suppressed the expression of adipogenic transcription factors Pparg and Cebpa in ST2 cells to suppress adipogenesis. ICRT-14, a specific transcriptional inhibitor of Wnt signaling, reversed the effects of S33 on the differentiation of ST2 cells. S33 also increased the expression of osteoclast cytokines RANKL and Opg but decreased the RANKL/Opg ratio and had the potential to inhibit osteoclast differentiation. In addition, we printed the PSCI3D (polycaprolactone, S33, cell-integrated 3D) scaffolds using a newly established integrated 3D printing system for hard materials and cells. S33 sustained release in the hydrogel of the scaffold with 25.4% release on day 1% and 81.7% release over 7 days. Cells in the scaffolds had good cell viability. The ratio of live/dead cells remained above 94% for 7 days, while the cells in the scaffolds proliferated linearly, and the proliferative activity of the PSCI3D scaffold group increased 1.4-fold and 1.7-fold on days 4 and 7, respectively. Similarly, in PSCI3D scaffolds, osteogenic differentiation of st2 cells was increased. The alkaline phosphatase activity increased 1.4- and 4.0-fold on days 7 and 14, respectively, and mineralization increased 1.7-fold at 21 days. In addition, PSCI3D conditioned medium promoted migration and tubulogenesis of HUVECs, and S33 upregulated the expression of Vegfa, a key factor in angiogenesis. In conclusion, our study suggests that S33 functions in osteogenesis, anti-adipogenesis, and potential inhibition of osteoclast differentiation. And the sustained release of S33 in PSCI3D scaffolds creates a safe osteogenic niche, which promotes cell proliferation, osteogenesis, and angiogenesis and has application prospects.

Regulation of the Osteocyte Secretome with Aging and Disease

As the most numerous and long-lived of all bone cells, osteocytes have essential functions in regulating skeletal health. Through the lacunar-canalicular system, secreted proteins from osteocytes can reach cells throughout the bone. Furthermore, the intimate connectivity between the lacunar-canalicular system and the bone vasculature allows for the transport of osteocyte-secreted factors into the circulation to reach the entire body. Local and endocrine osteocyte signaling regulates physiological processes such as bone remodeling, bone mechanoadaptation, and mineral homeostasis. However, these processes are disrupted by impaired osteocyte function induced by aging and disease. Dysfunctional osteocyte signaling is now associated with the pathogenesis of many disorders, including chronic kidney disease, cancer, diabetes mellitus, and periodontitis. In this review, we focus on the targeting of bone and extraskeletal tissues by the osteocyte secretome. In particular, we highlight the secreted osteocyte proteins, which are known to be dysregulated during aging and disease, and their roles during disease progression. We also discuss how therapeutic or genetic targeting of osteocyte-secreted proteins can improve both skeletal and systemic health.

Updates in the chronic kidney disease-mineral bone disorder show the role of osteocytic proteins, a potential mechanism of the bone-Vascular paradox, a therapeutic target, and a biomarker

The chronic kidney disease-mineral bone disorder (CKD-MBD) is a complex multi-component syndrome occurring during kidney disease and its progression. Here, we update progress in the components of the syndrome, and synthesize recent investigations, which suggest a potential mechanism of the bone-vascular paradox. The discovery that calcified arteries in chronic kidney disease inhibit bone remodeling lead to the identification of factors produced by the vasculature that inhibit the skeleton, thus providing a potential explanation for the bone-vascular paradox. Among the factors produced by calcifying arteries, sclerostin secretion is especially enlightening. Sclerostin is a potent inhibitor of bone remodeling and an osteocyte specific protein. Its production by the vasculature in chronic kidney disease identifies the key role of vascular cell osteoblastic/osteocytic transdifferentiation in vascular calcification and renal osteodystrophy. Subsequent studies showing that inhibition of sclerostin activity by a monoclonal antibody improved bone remodeling as expected, but stimulated vascular calcification, demonstrate that vascular sclerostin functions to brake the Wnt stimulation of the calcification milieu. Thus, the target of therapy in the chronic kidney disease-mineral bone disorder is not inhibition of sclerostin function, which would intensify vascular calcification. Rather, decreasing sclerostin production by decreasing the vascular osteoblastic/osteocytic transdifferentiation is the goal. This might decrease vascular calcification, decrease vascular stiffness, decrease cardiac hypertrophy, decrease sclerostin production, reduce serum sclerostin and improve skeletal remodeling. Thus, the therapeutic target of the chronic kidney disease-mineral bone disorder may be vascular osteoblastic transdifferentiation, and sclerostin levels may be a useful biomarker for the diagnosis of the chronic kidney disease-mineral bone disorder and the progress of its therapy.

Sclerostin as a biomarker of cardiovascular risk in women with systemic lupus erythematosus

Cardiovascular disease is one of the main causes of death in patients with systemic lupus erythematosus (SLE). On the other hand, sclerostin is a reliable and early biomarker of vascular calcification. This study aimed to estimate the association between sclerostin and two markers of cardiovascular risk, carotid atherosclerotic plaque (CP) and carotid-femoral pulse wave velocity (PWV), in women with SLE. The presence of CP (determined by carotid artery ultrasound) and PWV were measured in 68 women with SLE and preserved renal function. None of the participants had a history of cardiovascular disease. Serum levels of sclerostin were determined using the ELISA method. Other factors associated with increased cardiovascular risk were also measured. The association between sclerostin, CP and PWV was assessed using Receiver Operating Characteristic (ROC) curves and multivariate regression models. The area under the ROC curve was 0.785 (95% confidence interval [CI] 0.662-0.871) for CP and 0.834 (95% CI 0.729-0.916) for dichotomized PWV. After adjusting for other cardiovascular risk factors, it was found that a 10-units increase in sclerostin values was associated with a 44% increase in the odds of CP (95% CI 1-105), but no adjusted association was observed between sclerostin and PWV. Predictive models included age (for both outcomes), hypertension, Framingham risk score and C-reactive protein (for PWV), but not sclerostin. Sclerostin is associated with the presence of CP in women with SLE. Further research should confirm its possible role as a biomarker of cardiovascular risk in these patients.

Exploring the Role of Sclerostin as a Biomarker of Cardiovascular Disease and Mortality: A Scoping Review

Sclerostin is most recognized for its role in controlling bone formation; however, it is also expressed in the heart, aorta, coronary, and peripheral arteries. Human studies have associated high circulating sclerostin levels with the presence of different cardiovascular diseases (CVD), surrogate CVD markers, and a high risk of cardiovascular events in some populations. However, this is still a matter of scientific debate, as the results have been very heterogeneous among studies. In the present review, the association between serum sclerostin levels and CVD and/or cardiovascular mortality was analyzed. For this purpose, a scoping review was performed in which articles measuring serum sclerostin levels and cardiovascular risk in patients were selected. Eleven articles answered the research question; of these articles, 8/11 evaluated the association between sclerostin and CVD, of which 4/8 found a positive association, 2/8 found a negative association, and 2/8 found no association between variables. Five (5/11) of the articles included in the study evaluated cardiovascular mortality, of which 3/5 found a positive association, 1/5 found a negative association, and 1/5 found no association between variables. In conclusion, we did not find sufficient results to be able to demonstrate an association between elevated sclerostin levels and the development of CVD and/or cardiovascular mortality in the general population due to heterogeneity in the results. However, there seems to be a tendency to consider increased sclerostin levels as a risk factor for both the development of cardiovascular events and cardiovascular mortality in specific populations. Further studies in this field will help to solve some of the inconsistencies found during this scoping review and allow for the future use of sclerostin measurement as a strategy in the prevention and diagnosis of CVD and/or cardiovascular mortality.

Romosozumab for the treatment of osteoporosis in women: Efficacy, safety, and cardiovascular risk

Increased understanding of the Wnt signaling pathway has led to the development of romosozumab, one of the most potent osteoanabolic agents to date for osteoporosis treatment. Romosozumab is a monoclonal antibody that inhibits sclerostin, a natural inhibitor of the Wnt signaling pathway. Romosozumab, by inhibiting sclerostin activates the Wnt signaling pathway, leading to increased bone formation and decreased bone resorption. The pivotal ARCH and FRAME studies established romosozumab’s fracture reduction efficacy. Romosozumab was superior to alendronate in fracture reduction and bone mineral density gain in the ARCH study. Romosozumab treatment should be followed sequentially with a potent antiresorptive agent. The antifracture efficacy gained from romosozumab is maintained or improved after transitioning to an antiresorptive agent. As one of the most potent osteoanabolic agents, the introduction of romosozumab has significantly increased our ability to treat osteoporosis. Studies have provided important information on using romosozumab with other osteoporosis medications to optimize osteoporosis treatment. Romosozumab used before antiresorptive medications is associated with more significant bone mineral density increases than when an antiresorptive agent is used before romosozumab. Romosozumab is recommended for osteoporosis treatment in patients at very high risk for fracture with low cardiovascular risk. Romosozumab is generally well tolerated, with 4%–5% of patients having injection site reactions. The ARCH trial showed a higher risk of cardiovascular events in patients receiving romosozumab. Romosozumab carries a black box warning that romosozumab should not be initiated in patients with myocardial infarction or stroke in the preceding year. However, the information on romosozumab and increased cardiovascular risk is conflicting. The risk of cardiovascular disease with romosozumab is unclear. While romosozumab has demonstrated significant osteoanabolic effect and antifracture efficacy and will benefit high fracture risk patients, further studies are needed to investigate the cardiovascular safety of romosozumab.