The Role of Osteoprotegerin and Its Ligands in Vascular Function

Unraveling the Intricacies of OPG/RANKL/RANK Biology and Its Implications in Neurological Disorders-A Comprehensive Literature Review

The OPG/RANKL/RANK framework, along with its specific receptors, plays a crucial role in bone remodeling and the functioning of the central nervous system (CNS) and associated disorders. Recent research and investigations provide evidence that the components of osteoprotegerin (OPG), receptor activator of NF-kB ligand (RANKL), and receptor activator of NF-kB (RANK) are expressed in the CNS. The CNS structure encompasses cells involved in neuroinflammation, including local macrophages, inflammatory cells, and microglia that cross the blood-brain barrier. The OPG/RANKL/RANK trio modulates the neuroinflammatory response based on the molecular context. The levels of OPG/RANKL/RANK components can serve as biomarkers in the blood and cerebrospinal fluid. They act as neuroprotectants following brain injuries and also participate in the regulation of body weight, internal body temperature, brain ischemia, autoimmune encephalopathy, and energy metabolism. Although the OPG/RANKL/RANK system is primarily known for its role in bone remodeling, further exploring deeper into its multifunctional nature can uncover new functions and novel drug targets for diseases not previously associated with OPG/RANKL/RANK signaling.

Extra-osseous Roles of the RANK-RANKL-OPG Axis with a Focus on Skeletal Muscle

PURPOSE OF REVIEW

This review aims to consolidate recent observations regarding extra-osseous roles of the RANK-RANKL-OPG axis, primarily within skeletal muscle.

RECENT FINDINGS

Preclinical efforts to decipher a common signalling pathway that links the synchronous decline in bone and muscle health in ageing and disease disclosed a potential role of the RANK-RANKL-OPG axis in skeletal muscle. Evidence suggests RANKL inhibition benefits skeletal muscle function, mass, fibre-type switching, calcium homeostasis and reduces fall incidence. However, there still exists ambiguity regarding the exact mechanistic actions and subsequent functional improvements. Other potential RANK-RANKL-OPG extra-osseous roles include regulation of neural-inflammation and glucose metabolism. Growing evidence suggests the RANK-RANKL-OPG axis may play a regulatory role in extra-osseous tissues, especially in skeletal muscle. Targeting RANKL may be a novel therapy in ameliorating loss of muscle mass and function. More research is warranted to determine the causality of the RANK-RANKL-OPG axis in extra-osseous tissues, especially those affected by aging.

Prevention of prostate cancer metastasis by a CRISPR-delivering nanoplatform for interleukin-30 genome editing

Prostate cancer (PC) is a leading cause of cancer-related deaths in men worldwide. Interleukin-30 (IL-30) is a PC progression driver, and its suppression would be strategic for fighting metastatic disease. Biocompatible lipid nanoparticles (NPs) were loaded with CRISPR-Cas9gRNA to delete the human IL30 (hIL30) gene and functionalized with anti-PSCA-Abs (Cas9hIL30-PSCA NPs). Efficiency of the NPs in targeting IL-30 and the metastatic potential of PC cells was examined in vivo in xenograft models of lung metastasis, and in vitro by using two organ-on-chip (2-OC)-containing 3D spheroids of IL30+ PC-endothelial cell co-cultures in circuit with either lung-mimicking spheroids or bone marrow (BM)-niche-mimicking scaffolds. Cas9hIL30-PSCA NPs demonstrated circulation stability, genome editing efficiency, without off-target effects and organ toxicity. Intravenous injection of three doses/13 days, or five doses/20 days, of NPs in mice bearing circulating PC cells and tumor microemboli substantially hindered lung metastasization. Cas9hIL30-PSCA NPs inhibited PC cell proliferation and expression of IL-30 and metastasis drivers, such as CXCR2, CXCR4, IGF1, L1CAM, METAP2, MMP2, and TNFSF10, whereas CDH1 was upregulated. PC-Lung and PC-BM 2-OCs revealed that Cas9hIL30-PSCA NPs suppressed PC cell release of CXCL2/GROβ, which was associated with intra-metastatic myeloid cell infiltrates, and of DKK1, OPG, and IL-6, which boosted endothelial network formation and cancer cell migration. Development of a patient-tailored nanoplatform for selective CRISPR-mediated IL-30 gene deletion is a clinically valuable tool against PC progression.

Short-term effects of dapagliflozin on biomarkers of bone and mineral metabolism in patients with diabetic kidney disease: A prospective observational study

BACKGROUND

There is still a lack of information regarding the impact of sodium-glucose cotransporter 2 inhibitors (SGLT2i) on bone and mineral metabolism in patients with diabetes and chronic kidney disease (CKD). Therefore, we aimed to investigate the effects of SGLT2i in a cohort of patients suffering from diabetic kidney disease (DKD).

METHODS

In this prospective observational study, patients with type 2 diabetes and biopsy-proven diabetic nephropathy or presumptive DKD with eGFR levels ≥20 ml/min/1.73m2 and 25-OH vitamin D levels ≥20 ng/dl were included. 41 used SGLT2i (study group) and 39 continued their current treatment regimens (control group). Serum FGF-23, sclerostin, osteoprotegerin (OPG), and hydroxyproline levels were measured at baseline, 1 month and 3 months after treatment.

RESULTS

Mean age of all patients was 67±9.3 years, and 48 (60%) were female. All patients in the study group used dapagliflozin. Taking into account the renal functions at the commencement of the study, the eGFR values for the study group and the control group were 51.2±15.6 and 44.6±16.9ml/min/1.73m2, respectively (p=0.01). After three months, these values were observed to be 47.4±16.7 and 44.3±18.8 ml/min/1.73m2 (p=0.43), respectively. At baseline, OPG levels were higher in the study group (p=0.025) but there were no differences between the groups in terms of FGF-23 and sclerostin levels (p=0.670 and p=0.467, respectively). Levels of OPG, FGF-23, and sclerostin significantly decreased throughout 3 months of treatment with dapagliflozin (p<0.001 for all). Hydroxyproline levels also declined but did not reach to statistical significance (p=0.075). Multiple linear regression models revealed that treatment with SGLT2i was associated with the change in levels of sclerostin (β=0.303, p=0.011) and OPG (β=0.210, p=0.010), but not with FGF-23 (β=0.089, p=0.150).

CONCLUSIONS

FGF-23, sclerostin and OPG levels significantly declined after treatment with dapagliflozin for 3 months.

Severe meningitis and infectious aneurysm rupture of the middle cerebral artery following mechanical thrombectomy in infective endocarditis: A case report

Introduction

Infective endocarditis (IE) is known to precipitate several severe complications, often culminating in dire outcomes. In this report, we present the case of a 33-year-old female with IE, which was further complicated by the occurrence of brain infarction, meningitis, and infectious aneurysm.

Case report

A 33-year-old female patient, presenting with left limb weakness persisting for a duration of 15 h, was admitted to our medical facility. A head MRI scan disclosed the presence of an acute cerebral infarction located in the left hemisphere, and subsequent CT angiography confirmed an occlusion of the M1 segment of the left middle cerebral artery. Consequently, the patient underwent mechanical thrombectomy as an intervention. Several days later, echocardiography revealed the presence of a 6.5 × 3.2 mm vegetation on the anterior mitral valve cusp, while blood cultures returned positive for Streptococcus mitis. A diagnosis of IE was established, and antibiotic therapy tailored to the microbiological sensitivities was promptly initiated. However, on the ninth day of her hospitalization, the patient's clinical condition deteriorated significantly due to the emergence of critical complications, including meningitis and a infectious aneurysm. Despite the implementation of aggressive antibiotic therapy, her condition continued to worsen, ultimately resulting in her demise on the sixteenth day of hospitalization, precipitated by the rupture of the infectious aneurysm.

Conclusions

The occurrence of infective endocarditis alongside brain infarction, meningitis, and infectious aneurysm in a single patient represents a rare, intricate, and gravely serious clinical scenario. In such instances, the responsibility for management should be vested in a multidisciplinary team of healthcare professionals.

Temporal changes in biomarker levels and their association with the early degeneration stage of transcatheter aortic valves in 18F-fluorodeoxyglucose and 18F-sodium fluoride positron emission tomography studies

Introduction

As transcatheter aortic valve implantation (TAVI) indications expand, understanding the valve degeneration process and potential influencing biomarkers becomes increasingly important.

Aim

To investigate temporal changes in biomarker levels and their potential association with 18F-fluorodeoxyglucose (18F-FDG) and 18F-sodium fluoride (18F-NaF) uptake, assessed using positron emission tomography/computed tomography (PET/CT) studies as markers for native aortic annulus calcifications and early-stage TAVI valve degeneration.

Material and methods

A total of 71 TAVI patients underwent blood sampling and transthoracic echocardiography at baseline (pre-TAVI) and 6, 12, 18, and 24 months after the procedure. PET/CT using 18F-NaF and 18F-FDG was performed at 6 and 24 months. Serum levels of matrix metalloproteinase-3 (MMP-3), matrix metalloproteinase-9 (MMP-9), and osteopontin (OPN) were measured. In addition, plasma levels of osteoprotegerin (OPG), lipoprotein a (Lp(a)), and oxidized LDL (ox-LDL) were assessed.

Results

Finally, 31 patients (median age: 84.0 years) completed the study. Valve function improved after TAVI and remained stable during follow-up. Over 24 months, OPN levels decreased (p = 0.010), while MMP-3 and MMP-9 levels increased (p = 0.046 and p = 0.041). MMP-3 and MMP-9 showed multiple positive correlations across time points. OPN, ox-LDL, and OPG demonstrated significant negative correlations with follow-up effective orifice area index and effective orifice area (EOA). No significant correlations were found between biomarkers and PET/CT uptake.

Conclusions

Significant biomarker changes over 24 months and negative correlations with EOA suggest potential roles in aortic valve function. However, no correlations between biomarkers and PET/CT results were observed.

Biomarkers That Seem to Have the Greatest Impact on Promoting the Formation of Atherosclerotic Plaque in Current Scientific Research

Atherosclerosis is a chronic inflammatory disease that causes degenerative and productive changes in the arteries. The resulting atherosclerotic plaques restrict the vessel lumen, causing blood flow disturbances. Plaques are formed mainly in large- and medium-sized arteries, usually at bends and forks where there is turbulence in blood flow. Depending on their location, they can lead to various disease states such as myocardial infarction, stroke, renal failure, peripheral vascular diseases, or sudden cardiac death. In this work, we reviewed the literature on the early detection of atherosclerosis markers in the application of photodynamic therapy to atherosclerosis-related diseases. Herein, we described the roles of C-reactive protein, insulin, osteopontin, osteoprotegerin, copeptin, the TGF-β cytokine family, and the amino acid homocysteine. Also, we discuss the role of microelements such as iron, copper, zinc, and Vitamin D in promoting the formation of atherosclerotic plaque. Dysregulation of the administered compounds is associated with an increased risk of atherosclerosis. Additionally, taking into account the pathophysiology of atherosclerotic plaque formation, we believe that maintaining homeostasis in the range of biomarkers mentioned in this article is crucial for slowing down the process of atherosclerotic plaque development and the stability of plaque that is already formed.

The essential role of dual-energy x-ray absorptiometry in the prediction of subclinical cardiovascular disease

Subclinical cardiovascular disease (Sub-CVD) is an early stage of cardiovascular disease and is often asymptomatic. Risk factors, including hypertension, diabetes, obesity, and lifestyle, significantly affect Sub-CVD. Progress in imaging technology has facilitated the timely identification of disease phenotypes and risk categorization. The critical function of dual-energy x-ray absorptiometry (DXA) in predicting Sub-CVD was the subject of this research. Initially used to evaluate bone mineral density, DXA has now evolved into an indispensable tool for assessing body composition, which is a pivotal determinant in estimating cardiovascular risk. DXA offers precise measurements of body fat, lean muscle mass, bone density, and abdominal aortic calcification, rendering it an essential tool for Sub-CVD evaluation. This study examined the efficacy of DXA in integrating various risk factors into a comprehensive assessment and how the application of machine learning could enhance the early discovery and control of cardiovascular risks. DXA exhibits distinct advantages and constraints compared to alternative imaging modalities such as ultrasound, computed tomography, magnetic resonance imaging, and positron emission tomography. This review advocates DXA incorporation into cardiovascular health assessments, emphasizing its crucial role in the early identification and management of Sub-CVD.

Reduction of osteoclast formation and survival following suppression of cytokines by diacerein in periodontitis

Periodontitis causes an increase in several bioactive agents such as interleukins (IL), tumor necrosis factor (TNF)-α and receptor activator of NF-kB ligand (RANKL), which induce the osteoclast formation and activity. Since diacerein exerts anti-TNF-α and anti-IL-1 effects, alleviating bone destruction in osteoarthritis, we investigated whether this drug inhibits the formation and survival of osteoclast in the periodontitis. Rats were distributed into 3 groups: 1) group with periodontitis treated with 100 mg/kg diacerein (PDG), 2) group with periodontitis treated with saline (PSG) and group control (CG) without any treatment. After 7, 15 and 30 days, the maxillae were collected for light and transmission electron microscopy analyses. Gingiva samples were collected to evaluate the mRNA levels for Tnf, Il1b, Tnfsf11 and Tnfrsf11b by RT-qPCR. In PDG, the expression of Tnf and Il1b genes reduced significantly compared to PSG, except for Tnf expression at 7 days. The number of osteoclasts reduced significantly in the PDG in comparison with PSG at 7 and 15 days. In all periods, the IL-6 immunoexpression, RANKL/OPG immunoexpression and mRNA levels of Tnfsf11/Tnfrsf11b ratio were significantly lower in PDG than in PSG. PDG exhibited significantly higher frequency of TUNEL-positive osteoclasts than in PSG and CG at all time points. Osteoclasts with caspase-3-immunolabelled cytoplasm and nuclei with masses of condensed chromatin were observed in PDG, confirming osteoclast apoptosis. Diacerein inhibits osteoclastogenesis by decreasing Tnf and Il1b mRNA levels, resulting in decreased RANKL/OPG ratio, and induces apoptosis in osteoclasts of alveolar process of rat molars with periodontitis.

Converging Mechanisms of Vascular and Cartilaginous Calcification

Physiological calcification occurs in bones and epiphyseal cartilage as they grow, whereas ectopic calcification occurs in blood vessels, cartilage, and soft tissues. Although it was formerly thought to be a passive and degenerative process associated with aging, ectopic calcification has been identified as an active cell-mediated process resembling osteogenesis, and an increasing number of studies have provided evidence for this paradigm shift. A significant association between vascular calcification and cardiovascular risk has been demonstrated by various studies, which have shown that arterial calcification has predictive value for future coronary events. With respect to cartilaginous calcification, calcium phosphate or hydroxyapatite crystals can form asymptomatic deposits in joints or periarticular tissues, contributing to the pathophysiology of osteoarthritis, rheumatoid arthritis, ankylosing spondylitis, tendinitis, and bursitis. The risk factors and sequence of events that initiate ectopic calcification, as well as the mechanisms that prevent the development of this pathology, are still topics of debate. Consequently, in this review, we focus on the nexus of the mechanisms underlying vascular and cartilaginous calcifications, trying to circumscribe the similarities and disparities between them to provide more clarity in this regard.

Osteoprotegerin (OPG) and its ligands RANKL and TRAIL in falciparum, vivax and knowlesi malaria: correlations with disease severity, and B cell production of OPG

Osteoprotegerin (OPG) is a soluble decoy receptor for receptor activator of NF-ƙB ligand (RANKL) and TNF-related apoptosis-inducing ligand (TRAIL), and is increasingly recognised as a marker of poor prognosis in a number of diseases. Here we demonstrate that in Malaysian adults with falciparum and vivax malaria, OPG is increased, and its ligands TRAIL and RANKL decreased, in proportion to disease severity. In volunteers experimentally infected with P. falciparum and P. vivax, RANKL was suppressed, while TRAIL was unexpectedly increased, suggesting binding of OPG to RANKL prior to TRAIL. We also demonstrate that P. falciparum stimulates B cells to produce OPG in vitro, and that B cell OPG production is increased ex vivo in patients with falciparum, vivax and knowlesi malaria. Our findings provide further evidence of the importance of the OPG/RANKL/TRAIL pathway in pathogenesis of diseases involving systemic inflammation, and may have implications for adjunctive therapies. Further evaluation of the role of B cell production of OPG in host responses to malaria and other inflammatory diseases is warranted.

Osteoprotegerin Is Essential for the Development of Endothelial Dysfunction Induced by Angiotensin II in Mice

Opinions on the effects of osteoprotegerin (OPG) have evolved over the years from a protein protecting the vasculature from calcification to a cardiovascular risk factor contributing to inflammation within the vascular wall. Nowadays, the link between OPG and angiotensin II (Ang II) appears to be particularly important. In this study, the endothelial function was investigated in OPG-knockout mice (B6.129.S4-OPG, OPG-) and wild-type (C57BL/6J, OPG+) mice under basic conditions and after Ang II exposure by assessing the endothelium-dependent diastolic response of aortic rings to acetylcholine in vitro. A further aim of the study was to compare the effect of Ang II on the expression of cytokines in the aortic wall of both groups of mice. Our study shows that rings from OPG- mice had their normal endothelial function preserved after incubation with Ang II, whereas those from OPG+ mice showed significant endothelial dysfunction. We conclude that the absence of OPG, although associated with a pro-inflammatory cytokine profile in the vascular wall, simultaneously protects against Ang II-induced increases in pro-inflammatory cytokines in the murine vascular wall. Our study also demonstrates that the absence of OPG can result in a decrease in the concentration of pro-inflammatory cytokines in the vascular wall after Ang II exposure. The presence of OPG is therefore crucial for the development of Ang II-induced inflammation in the vascular wall and for the development of Ang II-induced endothelial dysfunction.

RANKL, but Not R-Spondins, Is Involved in Vascular Smooth Muscle Cell Calcification through LGR4 Interaction

Vascular calcification has a global health impact that is closely linked to bone loss. The Receptor Activator of Nuclear Factor Kappa B (RANK)/RANK ligand (RANKL)/osteoprotegerin (OPG) system, fundamental for bone metabolism, also plays an important role in vascular calcification. The Leucine-rich repeat-containing G-protein-coupled receptor 4 (LGR4), a novel receptor for RANKL, regulates bone remodeling, and it appears to be involved in vascular calcification. Besides RANKL, LGR4 interacts with R-spondins (RSPOs), which are known for their roles in bone but are less understood in vascular calcification. Studies were conducted in rats with chronic renal failure fed normal or high phosphorus diets for 18 weeks, with and without control of circulating parathormone (PTH) levels, resulting in different degrees of aortic calcification. Additionally, vascular smooth muscle cells (VSMCs) were cultured under non-calcifying (1 mM phosphate) and calcifying (3 mM phosphate) media with different concentrations of PTH. To explore the role of RANKL in VSMC calcification, increasing concentrations of soluble RANKL were added to non-calcifying and calcifying media. The effects mediated by RANKL binding to its receptor LGR4 were investigated by silencing the LGR4 receptor in VSMCs. Furthermore, the gene expression of the RANK/RANKL/OPG system and the ligands of LGR4 was assessed in human epigastric arteries obtained from kidney transplant recipients with calcification scores (Kauppila Index). Increased aortic calcium in rats coincided with elevated systolic blood pressure, upregulated Lgr4 and Rankl gene expression, downregulated Opg gene expression, and higher serum RANKL/OPG ratio without changes in Rspos gene expression. Elevated phosphate in vitro increased calcium content and expression of Rankl and Lgr4 while reducing Opg. Elevated PTH in the presence of high phosphate exacerbated the increase in calcium content. No changes in Rspos were observed under the conditions employed. The addition of soluble RANKL to VSMCs induced genotypic differentiation and calcification, partly prevented by LGR4 silencing. In the epigastric arteries of individuals presenting vascular calcification, the gene expression of RANKL was higher. While RSPOs show minimal impact on VSMC calcification, RANKL, interacting with LGR4, drives osteogenic differentiation in VSMCs, unveiling a novel mechanism beyond RANKL-RANK binding.

[miRNA Is Involved in the Pathogenesis of Multiple Diseases by Targeting Osteoprotegerin]

As a member of the tumor necrosis factor receptor family, osteoprotegerin (OPG) is highly expressed in adults in the lung, heart, kidney, liver, spleen, thymus, prostate, ovary, small intestines, thyroid gland, lymph nodes, trachea, adrenal gland, the testis, and bone marrow. Together with the receptor activator of nuclear factor-κB (RANK) and the receptor activator of nuclear factor-κB ligand (RANKL), it forms the RANK/RANKL/OPG pathway, which plays an important role in the molecular mechanism of the development of various diseases. MicroRNAs (miRNAs) are a class of endogenous non-coding RNAs performing regulatory functions in eukaryotes, with a size of about 20-25 nucleotides. miRNA genes are transcribed into primary transcripts by RNA polymerase, bind to RNA-induced silencing complexes, identify target mRNAs through complementary base pairing, with a single miRNA being capable of targeting hundreds of mRNAs, and influence the expression of many genes through pathways involved in functional interactions. In recent years, a large number of studies have been done to explore the mechanism of action of miRNA in diseases through miRNA isolation, miRNA quantification, miRNA spectrum analysis, miRNA target detection, in vitro and in vivo regulation of miRNA levels, and other technologies. It was found that miRNA can play a key role in the pathogenesis of osteoporosis, rheumatoid arthritis, and other diseases by targeting OPG. The purpose of this review is to explore the interaction between miRNA and OPG in various diseases, and to propose new ideas for studying the mechanism of action of OPG in diseases.

MicroRNAs regulate the vicious cycle of vascular calcification-osteoporosis in postmenopausal women

Menopause is a normal physiological process accompanied by changes in various physiological states. The incidence of vascular calcification (VC) increases each year after menopause and is closely related to osteoporosis (OP). Although many studies have investigated the links between VC and OP, the interaction mechanism of the two under conditions of estrogen loss remains unclear. MicroRNAs (miRNAs), which are involved in epigenetic modification, play a critical role in estrogen-mediated mineralization. In the past several decades, miRNAs have been identified as biomarkers or therapeutic targets in diseases. Thus, we hypothesize that these small molecules can provide new diagnostic and therapeutic approaches. In this review, we summarize the close interactions between VC and OP and the role of miRNAs in their interplay.

Osteoprotegerin and Inflammation in Incident Peritoneal Dialysis Patients

Objectives: Osteoprotegerin (OPG) is a member of the tumor necrosis factor receptor family involved in processes in many inflammatory states. OPG concentration is enhanced in the majority of chronic kidney disease (CKD) patients and those undergoing renal replacement therapy. The aim of the study was to assess the relation of OPG and chronic inflammation in peritoneal dialysis (PD) patients and to evaluate whether OPG concentrations in plasma and dialysate were related to plasma and dialysate levels of proinflammatory mediators (interleukin 6 (IL-6), high-sensitivity C-reactive protein (hsCRP), interleukin 33 (IL-33) and interleukin 1 receptor-like 1IL-1RL1 (IL-1RL1, sST2)). Methods: The study included 37 patients of the Peritoneal Dialysis Center, Department of Nephrology, Transplantology and Internal Medicine, Szczecin, Poland, 4-6 weeks after the onset of peritoneal dialysis therapy. During a peritoneal equilibration test, plasma (at 2 h) and dialysate (at 4 h) OPG, IL-33, 1IL-1RL1 (sST2), IL-6 and hsCRP concentrations were determined. Results: Plasma concentration of OPG did not correlate with dialysate OPG level (Rs = 0.04, p = 0.8). There was a strong positive correlation between plasma OPG concentrations and plasma IL-1RL1 (sST2) (Rs = 0.41; p = 0.01), plasma IL-6 (Rs = 0.38; p = 0.01) and plasma hsCRP (Rs = 0.35; p = 0.02). Dialysate OPG concentrations were positively associated with dialysate IL-1RL1 (sST2) (Rs = 0.37; p = 0.02) and dialysate IL-6 levels (Rs = 0.44; p = 0.005). Multivariate analysis showed that higher IL-1RL1 (sST2) (ß = +0.38, p = 0.006), higher plasma hsCRP (ß = +0.32, p = 0.02) and older age (ß = +0.35, p = 0.01) were independent determinants of higher plasma OPG concentration and that higher concentrations of dialysate IL-6 (ß = +0.37, p = 0.02) were independent determinants of higher dialysate OPG concentration. Conclusions: Both plasma and dialysate OPG levels are associated with the severity of systemic and local inflammation illustrated by the plasma and dialysate concentrations of IL-1RL1 (sST2), hsCRP and IL-6, suggesting that OPG might have a pivotal role in explaining the milieu of systemic and intraperitoneal inflammation.

Molecular Pathways of Vulnerable Carotid Plaques at Risk of Ischemic Stroke: A Narrative Review

The concept of vulnerable carotid plaques is pivotal in understanding the pathophysiology of ischemic stroke secondary to large-artery atherosclerosis. In macroscopic evaluation, vulnerable plaques are characterized by one or more of the following features: microcalcification; neovascularization; lipid-rich necrotic cores (LRNCs); intraplaque hemorrhage (IPH); thin fibrous caps; plaque surface ulceration; huge dimensions, suggesting stenosis; and plaque rupture. Recognizing these macroscopic characteristics is crucial for estimating the risk of cerebrovascular events, also in the case of non-significant (less than 50%) stenosis. Inflammatory biomarkers, such as cytokines and adhesion molecules, lipid-related markers like oxidized low-density lipoprotein (LDL), and proteolytic enzymes capable of degrading extracellular matrix components are among the key molecules that are scrutinized for their associative roles in plaque instability. Through their quantification and evaluation, these biomarkers reveal intricate molecular cross-talk governing plaque inflammation, rupture potential, and thrombogenicity. The current evidence demonstrates that plaque vulnerability phenotypes are multiple and heterogeneous and are associated with many highly complex molecular pathways that determine the activation of an immune-mediated cascade that culminates in thromboinflammation. This narrative review provides a comprehensive analysis of the current knowledge on molecular biomarkers expressed by symptomatic carotid plaques. It explores the association of these biomarkers with the structural and compositional attributes that characterize vulnerable plaques.

Pathological progression of osteoarthritis: a perspective on subchondral bone

Osteoarthritis (OA) is a degenerative bone disease associated with aging. The rising global aging population has led to a surge in OA cases, thereby imposing a significant socioeconomic burden. Researchers have been keenly investigating the mechanisms underlying OA. Previous studies have suggested that the disease starts with synovial inflammation and hyperplasia, advancing toward cartilage degradation. Ultimately, subchondral-bone collapse, sclerosis, and osteophyte formation occur. This progression is deemed as "top to bottom." However, recent research is challenging this perspective by indicating that initial changes occur in subchondral bone, precipitating cartilage breakdown. In this review, we elucidate the epidemiology of OA and present an in-depth overview of the subchondral bone's physiological state, functions, and the varied pathological shifts during OA progression. We also introduce the role of multifunctional signal pathways (including osteoprotegerin (OPG)/receptor activator of nuclear factor-kappa B ligand (RANKL)/receptor activator of nuclear factor-kappa B (RANK), and chemokine (CXC motif) ligand 12 (CXCL12)/CXC motif chemokine receptor 4 (CXCR4)) in the pathology of subchondral bone and their role in the "bottom-up" progression of OA. Using vivid pattern maps and clinical images, this review highlights the crucial role of subchondral bone in driving OA progression, illuminating its interplay with the condition.

Bone marrow adipocytes and lung cancer bone metastasis: unraveling the role of adipokines in the tumor microenvironment

Bone is a common site of metastasis for lung cancer. The "seed and soil" hypothesis suggests that the bone marrow microenvironment ("soil") may provide a conducive survival environment for metastasizing tumor cells ("seeds"). The bone marrow microenvironment, comprising a complex array of cells, includes bone marrow adipocytes (BMAs), which constitute about 70% of the adult bone marrow volume and may play a significant role in tumor bone metastasis. BMAs can directly provide energy for tumor cells, promoting their proliferation and migration. Furthermore, BMAs participate in the tumor microenvironment's osteogenesis regulation, osteoclast(OC) regulation, and immune response through the secretion of adipokines, cytokines, and inflammatory factors. However, the precise mechanisms of BMAs in lung cancer bone metastasis remain largely unclear. This review primarily explores the role of BMAs and their secreted adipokines (leptin, adiponectin, Nesfatin-1, Resistin, chemerin, visfatin) in lung cancer bone metastasis, aiming to provide new insights into the mechanisms and clinical treatment of lung cancer bone metastasis.

Assessment of osteoprotegerin and RANKL levels and several cardiovascular risk scoring systems in acromegaly

PURPOSE

The OPG/RANKL (osteoprotegerin/receptor activator of nuclear factor kappa-B) system, which plays a crucial role in bone metabolism, is also associated with vascular calcification. Acromegaly is characterized by excessive secretion of growth hormone and insulin-like growth factor, and studies have demonstrated an elevated risk of cardiovascular disease in individuals with acromegaly. In this study, our objective was to investigate the relationship between OPG/RANKL and various cardiovascular risk scoring systems.

METHODS

We recruited 44 consecutive acromegaly patients and 41 healthy controls with a similar age and gender distribution for this study.

RESULTS

While RANKL levels were significantly higher in the acromegaly group compared to the controls, OPG levels were not found to be significantly different between the two groups. Furthermore, within the acromegaly group, RANKL levels were significantly higher in patients with active acromegaly compared to those with controlled acromegaly. Osteoprotegerin levels showed a positive correlation with the Framingham risk score (FRS) in the acromegaly group. Linear regression analysis revealed an association of OPG with FRS (adjusted R2 value of 21.7%).

CONCLUSION

OPG and RANKL may serve as potential markers for assessment of cardiovascular calcification and prediction of the cardiovascular risk status in acromegalic patients.

Nano-hydroxyapatite structures for bone regenerative medicine: Cell-material interaction

Bone tissue engineering holds great promise for the regeneration of damaged or severe bone defects. However, several challenges hinder its translation into clinical practice. To address these challenges, interdisciplinary efforts and advances in biomaterials, cell biology, and bioengineering are required. In recent years, nano-hydroxyapatite (nHA)-based scaffolds have emerged as a promising approach for the development of bone regenerative agents. The unique similarity of nHA with minerals found in natural bones promotes remineralization and stimulates bone growth, which are crucial factors for efficient bone regeneration. Moreover, nHA exhibits desirable properties, such as strong chemical interactions with bone and facilitation of tissue growth, without inducing inflammation or toxicity. It also promotes osteoblast survival, adhesion, and proliferation, as well as increasing alkaline phosphatase activity, osteogenic differentiation, and bone-specific gene expression. However, it is important to note that the effect of nHA on osteoblast behavior is dose-dependent, with cytotoxic effects observed at higher doses. Additionally, the particle size of nHA plays a crucial role, with smaller particles having a more significant impact. Therefore, in this review, we highlighted the potential of nHA for improving bone regeneration processes and summarized the available data on bone cell response to nHA-based scaffolds. In addition, an attempt is made to portray the current status of bone tissue engineering using nHA/polymer hybrids and some recent scientific research in the field.

The Role of the Receptor Activator of Nuclear Factor Kappa-B Ligand/Osteoprotegerin Ratio in Vascular Diseases: A Therapeutic Approach

Cardiovascular and bone diseases contribute independently to mortality and global health. The exact mechanisms involved in the pathophysiology shared between bone and vascular diseases are not well defined. Endothelial cells and osteoblasts communicate during osteogenesis, thus establishing a connection between angiogenesis and osteogenesis. One shared mechanism may involve osteoprotegerin (OPG) and its ligand Receptor Activator of NF-κB Ligand (RANKL). The RANKL/OPG ratio is an important modulator for the skeletal, immunological, and vascular systems. OPG levels are elevated due to either osteogenic causes or inflammatory responses in the vasculature. The data obtained from clinical and in vitro studies support the role of the RANKL/OPG ratio as a potential marker for the progression of endothelial damage. Therefore, determining the therapeutic approaches for the targeting RANKL/OPG ratio and evaluating its usage as a biomarker in cardiovascular and bone pathophysiology are needed. By integrating the protective and disease-causing role of OPG with its ligand, this review outlines the role of the RANKL/OPG ratio at the molecular level. We also consider targeted therapeutic approaches.

Factors associated with patent foramen ovale-related stroke: SAFAS study

BACKGROUND

Persistent foramen ovale (PFO) contributes to cryptogenic stroke and is associated with stroke recurrence, although the exact mechanism of ischemic events is not fully understood. Several biomarkers have been developed for the prediction of atrial fibrillation after stroke, but there are currently only limited data on their potential value for the diagnosis of PFO-related stroke.

METHODS

This study was a prospective single-center study that included all patients hospitalized between March 31, 2018, and January 18, 2020, in the stroke department of the Dijon University Hospital for ischemic stroke without obvious cause and without a history of atrial fibrillation. PFO was systematically screened by transthoracic echocardiography and images were reviewed by an independent cardiologist blinded from clinical data. PFO was defined according to the CLOSE trial criteria: PFO associated with interatrial septal aneurysm or significant interatrial shunt (> 30 microbubbles in the left atrium within three cardiac cycles after right atrial opacification). The potential association of PFO-related stroke with biomarkers of cardiac fibrosis and inflammation such as galectin-3, GDF-15, ST-2, osteoprotegerin and NT-proBNP was tested using multivariate backward stepwise logistic regression.

RESULTS

Of the 240 patients included in the SAFAS study, 229 had complete echocardiographic data, and 23 (10%) had PFO-related stroke. Patients with PFO-related stroke were significantly younger (58±14 vs. 69±14, P<0.001), had less frequent previous arterial hypertension (30 vs. 60%, P=0.008), and more frequent cerebellar territory involvement (26 vs. 9%, P=0.014) compared to the other patients. In addition, they had less frequently left atrial dilatation (left atrial index volume>34mL/m2 [9 vs. 35%, P=0.009]). After ROC curve analysis for definition of thresholds, PFO-related stroke patients more often had galectin-3<9.5ng/mL (59 vs. 27%, P=0.002), ST2<13380pg/ml (23 vs. 50%, P=0.007), GDF-15<1200ng/mL (59 vs. 27%, P=0.002), osteoprotegerin<1133pg/mL (82 vs. 58%, P=0.033) and NT-proBNP<300pg/mL (88 vs. 55%, P=0.009). After multivariate analysis, only galectin-3<9.5ng/mL (OR [95% CI] 3.4 [1.18; 9.8], P=0.024) and osteoprotegerin<1133pg/L (OR [95% CI] 5.0 [1.1; 22.9], P=0.038) were independently associated with PFO-related stroke.

CONCLUSION

Patients in whom cryptogenic stroke is attributed to a significant PFO have a specific clinical and biological phenotype. Low levels of galectin-3 and osteoprotegerin may help identify patients with PFO-related strokes.

Integrated procedures for accelerating, deepening, and leading genetic inquiry: A first application on human muscle secretome

PURPOSE

Beyond classical procedures, bioinformatic-assisted approaches and computational biology offer unprecedented opportunities for scholars. However, these amazing possibilities still need epistemological criticism, as well as standardized procedures. Especially those topics with a huge body of data may benefit from data science (DS)-assisted methods. Therefore, the current study dealt with the combined expert-assisted and DS-assisted approaches to address the broad field of muscle secretome. We aimed to apply DS tools to fix the literature research, suggest investigation targets with a data-driven approach, predict possible scenarios, and define a workflow.

METHODS

Recognized scholars with expertise on myokines were invited to provide a list of the most important myokines. GeneRecommender, GeneMANIA, HumanNet, and STRING were selected as DS tools. Networks were built on STRING and GeneMANIA. The outcomes of DS tools included the top 5 recommendations. Each expert-led discussion has been then integrated with an DS-led approach to provide further perspectives.

RESULTS

Among the results, 11 molecules had already been described as bona-fide myokines in literature, and 11 molecules were putative myokines. Most of the myokines and the putative myokines recommended by the DS tools were described as present in the cargo of extracellular vesicles.

CONCLUSIONS

Including both supervised and unsupervised learning methods, as well as encompassing algorithms focused on both protein interaction and gene represent a comprehensive approach to tackle complex biomedical topics. DS-assisted methods for reviewing existent evidence, recommending targets of interest, and predicting original scenarios are worth exploring as in silico recommendations to be integrated with experts' ideas for optimizing molecular studies.

Type H vessels in osteogenesis, homeostasis, and related disorders

The vascular system plays a crucial role in bone tissue. Angiogenic and osteogenic processes are coupled through a spatial-temporal connection. Recent studies have identified three types of capillaries in the skeletal system. Compared with type L and E vessels, type H vessels express high levels of CD31 and endomucin, and function to couple angiogenesis and osteogenesis. Endothelial cells in type H vessels interact with osteolineage cells (e.g., osteoblasts, osteoclasts, and osteocytes) through cytokines or signaling pathways to maintain bone growth and homeostasis. In imbalanced bone homeostases, such as osteoporosis and osteoarthritis, it may be a new therapeutic strategy to regulate the endothelial cell activity in type H vessels to repair the imbalance. Here, we reviewed the latest progress in relevant factors or signaling pathways in coupling angiogenesis and osteogenesis. This review would contribute to further understanding the role and mechanisms of type H vessels in coupling angiogenic and osteogenic processes. Furthermore, it will facilitate the development of therapeutic approaches for bone disorders by targeting type H vessels.

Association of rs2073618 polymorphism and osteoprotegerin levels with hypertension and cardiovascular risks in patients with type 2 diabetes mellitus

There are reports of link of osteoprotegerin (OPG) gene polymorphism to type-2 diabetes (T2D) and hypertension (HTN). The objective of the study was to assess the allele frequency of OPG (rs2073618) gene polymorphism and its association with heart rate variability (HRV) and blood pressure variability profile as CVD risks in diabetes mellitus patients with hypertension undergoing treatment. T2D patients on treatment without hypertension (n = 172), with hypertension (n = 177) and 191 healthy volunteers were recruited for the study. Their blood pressure variability including baroreflex sensitivity (BRS), heart rate variability (HRV), OPG, insulin, lipid profile, receptor-activator for NFkB (RANK), receptor-activator for NFkB-Ligand (RANKL), and tumor necrosis factor-α (TNF-α) were estimated. Allele frequency of OPG (rs2073618) gene polymorphism was assessed from the DNA samples. BRS and HRV indices were decreased, and RANKL/OPG and TNF-α were increased in T2D and T2D + HTN groups, respectively compared to healthy control group. The reduction in BRS was contributed by increased inflammation and reduced SDNN of HRV in GG genotype in T2D + HTN. In GG + GC subgroup, it was additionally contributed by rise in RANKL/OPG level (β - 0.219; p 0.008). Presence of mutant GG genotype contributed to the risk of hypertension among T2D patients (OR 3.004) as well as in general population (OR 2.79). It was concluded that CV risks are more in T2D patients with HTN expressing OPG rs2073618 gene polymorphism.

Serum Osteoprotegerin Levels and the Vascular Reactivity Index in Patients with Hypertension

Background and Objectives: Osteoprotegerin (OPG), a soluble glycoprotein found in serum, has been associated with both the presence and severity of atherosclerosis. OPG is regarded as the mediator in the process of vascular endothelial dysfunction. Impaired endothelial function has an intimate link with hypertension (HTN) and is associated with significant morbidity and mortality. This study was to investigate the connection between OPG and endothelial dysfunction in patients having HTN. Materials and Methods: There are 102 patients with HTN included. For the purpose of determining the levels of OPG, a commercial enzyme-linked immunosorbent test kit was applied. The vascular reactivity index (VRI), which is assessed via the digital thermal monitoring, provides information on endothelial function. Results: Ten patients with HTN (9.8%) were classified as having poor vascular reactivity (VRI < 1.0), 46 HTN patients (45.1%) as having intermediate vascular reactivity (1.0 ≤ VRI < 2.0), and 46 HTN patients (45.1%) were classified as having high vascular reactivity (VRI ≥ 2.0). A greater serum OPG level (p < 0.001) and older age (p = 0.022) were linked to impaired vascular reactivity. The estimated glomerular filtration rate (r = 0.196, p = 0.048) was positively correlated with VRI values in hypertensive participants, while advanced age (r = -0.222, p = 0.025) and the log-transformed OPG level (log-OPG, r = -0.357, p < 0.001) were negatively correlated with VRI. Serum log-OPG level was shown to be strongly and independently correlated with VRI values in HTN individuals after multivariable forward stepwise linear regression analysis (β = -0.357, adjusted R2 change = 0.119, p < 0.001). Conclusions: In patients with HTN, serum OPG levels were adversely correlated with VRI and probably had a role in endothelial dysfunction.

OPG gene-modified adipose-derived stem cells improve bone formation around implants in osteoporotic rat maxillae

Background

Osteoporosis is a significant barrier to the use of dental implants in the elderly for the treatment of tooth defects. Adipose derived stem cells (ADSCs) have demonstrated extensive potential for tissue repair and regeneration. The present study aimed to investigate the effectiveness of ADSCs engineered to express high levels of osteoprotegerin (OPG) for the treatment of bone loss in implant dentistry caused by estrogen deficiency.

Methods

A rat model of osteoporosis was established through double oophorectomy, and the rats were treated by gene modified cells Adv-OPG-ADSCs. The effects of the treatment on maxilla tissue changes were evaluated using HE staining and micro-CT. Additionally, ALP and TRAP staining were used to assess osteoblast and osteoclast alterations. Finally, the changes in related osteoblast and osteoclast indicators were measured by RT-qPCR, Western blot, and ELISA.

Results

The successfully generated high-OPG-expressing ADSCs led to increase of cell viability, proliferation, and osteoblast differentiation. Treatment with Adv-OPG-ADSCs significantly ameliorated maxillary morphology, trabecular volume reduction, and bone mineral density decline in the model of estrogen-deficient maxillary implant dentistry. Furthermore, the treatment was beneficial to promoting the generation of osteoblasts and inhibiting the generation of osteoclast. Adv-OPG-ADSCs increased OPG, ALP, OCN, and Runx-2 expressions in the maxilla while suppressing RANKL expression, and also increased the concentration of COL I and PINP, as well as decreased the concentration of CTX-1.

Conclusion

Adv-OPG-ADSCs promote the formation of osteoblasts and inhibit the generation of osteoclasts, thereby inhibiting bone absorption, facilitating bone formation, and promoting the repair of maxillary bone after dental implantation in the presence of osteoporosis-related complications, especially in the setting of estrogen deficiency, providing scientific basis for the application of Adv-OPG-ADSCs in the treatment of implant related osteoporosis.

Plasma osteoprotegerin predicts adverse cardiovascular events in stable coronary artery disease: the PEACE trial

Background

Osteoprotegerin (OPG) is a secretory glycoprotein and participates in the progression of atherosclerotic lesions. We aim to explore the relationship between OPG and the prognosis of coronary artery disease (CAD).

Methods

Plasma OPG concentrations were measured in 3,766 patients with stable CAD enrolled in the PEACE trial. The PEACE trial (NCT00000558) group followed up the patients and examined their future clinical outcomes.

Results

In summary, 208 (5.5%) primary outcomes occurred, 295 patients (7.8%) died from all-cause death, 128 (3.4%) died from cardiovascular causes, and 94 (2.5%) experienced heart failure during a median follow-up of 1,892 days. In addition, we found that higher plasma levels of OPG were associated with a higher incidence of all-cause death, cardiovascular death, and heart failure, even after adjusting clinical cofounders.

Conclusion

It was demonstrated that elevated plasma OPG levels were associated with an increased incidence of all-cause death, cardiovascular death, and heart failure in patients with stable CAD.

Systematic Review Registration

https://clinicaltrials.gov/ct2/show/NCT00000558?term=NCT00000558&draw=2&rank=1, identifier: NCT00000558.

Role of osteoprotegerin rs3102735 gene polymorphism in acute ischemic stroke patients

Background

Ischemic stroke ranks third among leading causes of death and disability. Both endothelial and vascular smooth muscle cells generate osteoprotegerin (OPG). Ischemic stroke and its severity may be enhanced by the OPG rs3102735 gene polymorphism. Our research aims to investigate OPG rs3102735 gene polymorphism role in ischemic stroke risk and to assess its association with stroke severity at presentation and degree of vascular stenosis and evaluate its potential as a predictor of stroke severity. Fifty people with acute ischemic stroke as well as fifty controls were studied. The NIHSS and ASPECTS were utilized to evaluate stroke severity and the infarction size, respectively. All subjects underwent extracranial carotid duplex study and molecular assessment for genotyping of OPG rs3102735) gene polymorphism.

Results

Stroke patients had markedly higher concentrations of OPG in the plasma than controls (311.60 ± 109.48 versus 240.20 ± 75.96 mmol/ml, p = 0.001). The optimal plasma OPG cutoff value for the predicting the occurrence of stroke was determined to be > 250 mmol/ml, the 95% confidence interval (CI) was (0.625–0.843), sensitivity was 68% and specificity was 72%. Ischemic stroke had a significantly different genotype distribution for the OPG rs3102735 gene polymorphism than did controls (36 CC, 13 CT, and 1 TT) versus (28 CC, 15 CT, and 7 TT) respectively. Stroke patients had a significantly greater CC + CT genotype than controls did (P = 0.041), also they had a higher propensity for carrying the C allele than the T allele (P = 0.017). Carotid intima medium thickness and the NIHSS both had positive correlations with OPG serum level (r = 0.39, p = 0.02 and r = 0.4, p = 0.02, respectively), whereas ASPECTS had an inversed correlation (r = − 0.65, p = 0.001).

Conclusions

The current study shows that as an independent risk factor, increased plasma OPG level, may participate in the atherothrombotic ischemic stroke pathophysiology, in addition, genetic variants in the OPG gene (rs3102735) are a separate risk factor for large artery atherosclerosis and plasma OPG level can serve as a biomarker to determine the severity of a stroke.

Apoptotic Vesicles Regulate Bone Metabolism via the miR1324/SNX14/SMAD1/5 Signaling Axis

Mesenchymal stem cells (MSCs) are widely used in the treatment of diseases. After their in vivo application, MSCs undergo apoptosis and release apoptotic vesicles (apoVs). This study investigates the role of apoVs derived from human bone marrow mesenchymal stem cells (hBMMSCs) in bone metabolism and the molecular mechanism of the observed effects. The results show that apoVs can promote osteogenesis and inhibit osteoclast formation in vitro and in vivo. ApoVs may therefore attenuate the bone loss caused by primary and secondary osteoporosis and stimulate bone regeneration in areas of bone defect. The mechanisms responsible for apoV-induced bone regeneration include the release of miR1324, which inhibit expression of the target gene Sorting Nexin 14 (SNX14) and thus activate the SMAD1/5 pathway in target cells. Given that MSC-derived apoVs are easily obtained and stored, with low risks of immunological rejection and neoplastic transformation, The findings suggest a novel therapeutic strategy to treat bone loss, including via cell-free approaches to bone tissue engineering.

Association of osteocalcin, osteoprotegerin, and osteopontin with cardiovascular disease and retinopathy in type 2 diabetes

BACKGROUND

Novel biomarkers of vascular disease in diabetes could help identify new mechanistic pathways. Osteocalcin, osteoprotegerin, and osteopontin are key molecules involved in bone and vascular calcification processes, both of which are compromised in diabetes. We aimed to evaluate possible associations of osteocalcin, osteoprotegerin, and osteopontin with cardiovascular disease (CVD) and diabetic retinopathy (DR) among people with type 2 diabetes (T2D).

MATERIALS AND METHODS

Osteocalcin, osteoprotegerin, and osteopontin concentrations were measured at enrolment in 848 participants with T2D from the Sapienza University Mortality and Morbidity Event Rate (SUMMER) Study (ClinicalTrials.gov: NCT02311244). Logistic regression models and propensity score matching were used to assess possible associations of osteocalcin, osteoprotegerin, and osteopontin with a history of CVD and with evidence of any grade of DR adjusting for confounders.

RESULTS

Previous CVD was reported in 139 (16.4%) participants, while 144 (17.0%) had DR. After adjusting for possible confounders, osteocalcin but not osteoprotegerin or osteopontin concentrations were associated with a history of CVD (Odds Ratio [OR] and 95% CI for one standard deviation (SD) increase in osteocalcin concentrations (natural log): 1.35 (1.06-1.72), p = 0.014). Associations with prevalent DR were seen for osteoprotegerin (OR for one SD increase in osteoprotegerin concentrations (natural log): 1.25 (1.01-1.55), p = 0.047) and osteopontin (OR for one SD increase in osteopontin concentrations (natural log): 1.25 (1.02-1.53), p = 0.022), but not osteocalcin.

CONCLUSIONS

In T2D, higher serum osteocalcin concentrations are associated with macrovascular complications and higher osteoprotegerin and osteopontin concentrations with microvascular complications, suggesting that these osteokines might be involved in pathways directly related to vascular disease.

Correlation between osteoprotegerin and coronary artery calcification in diabetic subjects: a systematic review of observational studies

Coronary artery calcification (CAC) is one of the critical cardiovascular complications that lead to elevated morbidity and mortality among patients with type 2 diabetes (T2M). The association between osteoprotegerin (OPG) and CAC could potentially provide a reasonable chance for preventive therapy in type 2 diabetic patients and benefit the rate of mortality. Since measurement of CAC score is relatively expensive and requires radiation exposure, the current systematic review aims to provide clinical evidence for evaluating the prognostic role of OPG in determining CAC risk among subjects with T2M. Web of Science, PubMed, Embase, and Scopus, were investigated until July 2022. We assessed human studies investigating the association of OPG with CAC in type 2 diabetic patients. Quality assessment was performed by Newcastle-Ottawa quality assessment scales (NOS). Out of 459 records, 7 studies remained eligible to be included. Observational studies that provided odds ratio (OR) estimates with 95% confidence intervals (CIs) for the association between OPG and the risk of CAC were analyzed by random-effects model. In order to provide a visual summary of our findings, the estimation of pooled OR from cross-sectional studies was reported as 2.86 [95% CI 1.49-5.49], which is consistent with the findings of the cohort study. Results revealed that the association between OPG and CAC was significant among diabetic patients. OPG is hypothesized to be a potential marker in predicting the presence of high coronary calcium score among subjects with T2M that could be recognized as a novel target for further pharmacological investigations.

Osteoporosis and cardiovascular disease: a review

BACKGROUND

Osteoporosis and cardiovascular disease are common diseases encountered globally, especially with advancing age. Osteoporosis occurs when there is a loss of bone mineral density leading to increased predisposition to fragility fracture. The conventional perception of osteoporosis is purely as a metabolic bone disease. However, there are mounting reports from recent studies that osteoporosis could be seen as a risk factor for cardiovascular disease just like other traditional risk factors such as hypertension, dyslipidaemia and diabetes. This is a paradigm shift with regards to the outlook of osteoporosis. Osteoporosis and cardiovascular disease have similar risk factors, including diabetes, smoking, excess alcohol, sedentary lifestyle, ageing and dyslipidaemia. This may partly explain the link between osteoporosis and cardiovascular disease. In addition, both osteoporosis and atherosclerosis, which underlies most cardiovascular disease, are both characterized by low grade chronic inflammation. Moreover, the processes involved in the calcification of atheroma are similar to what is seen in bone remodeling. Both processes also involve similar regulators such as osteoprotegerin and related proteins such as osteonectin, osteopontin and type 1 collagen are found in bone matrix and atheromatous plaques.

CONCLUSION

There is emerging evidence that individuals with osteoporosis are also at an increased risk of coronary artery disease and stroke even after controlling for other factors. The traditional risk factors for cardiovascular disease also predispose people to developing osteoporosis, suggesting that the same mechanism may be causing the two. Moreover, a number of anti-osteoporotic drugs have also been largely linked with cardiovascular disease. This calls for a change in the view of osteoporosis as a metabolic disease but as a cardio-metabolic disorder thereby emphasizing the need for intensified preventive strategies for the disease.

Endothelial cell activation, Weibel-Palade body secretion, and enhanced angiogenesis in severe COVID-19

Background

Severe COVID-19 is associated with marked endothelial cell (EC) activation that plays a key role in immunothrombosis and pulmonary microvascular occlusion. However, the biological mechanisms through which SARS-CoV-2 causes EC activation and damage remain poorly defined.

Objectives

We investigated EC activation in patients with acute COVID-19, and specifically focused on how proteins stored within Weibel-Palade bodies may impact key aspects of disease pathogenesis.

Methods

Thirty-nine patients with confirmed COVID-19 were recruited. Weibel-Palade body biomarkers (von Willebrand factor [VWF], angiopoietin-2 [Angpt-2], and osteoprotegerin) and soluble thrombomodulin (sTM) levels were determined. In addition, EC activation and angiogenesis were assessed in the presence or absence of COVID-19 plasma incubation.

Results

Markedly elevated plasma VWF antigen, Angpt-2, osteoprotegerin, and sTM levels were observed in patients with acute COVID-19. The increased levels of both sTM and Weibel-Palade body components (VWF, osteoprotegerin, and Angpt-2) correlated with COVID-19 severity. Incubation of COVID-19 plasma with ECs triggered enhanced VWF secretion and increased Angpt-2 expression, as well as significantly enhanced in vitro EC tube formation and angiogenesis.

Conclusion

We propose that acute SARS-CoV-2 infection leads to a complex and multifactorial EC activation, progressive loss of thrombomodulin, and increased Angpt-2 expression, which collectively serve to promote a local proangiogenic state.

Bone disease in patients with cirrhosis of different etiology and severity; are Klotho protein and osteoprotegerin potential biomarkers?

BACKGROUND AND AIMS

Cirrhosis is associated with increased risk for osteoporosis and osteopenia. This study aims to further investigate this relationship by examining if etiology and severity of cirrhosis are independent predictors of bone mineral density (BMD) loss. Furthermore we examined the serum levels of osteoprotegerin (OPG) and Klotho proteins that have been involved in bone metabolism.

METHODS

Seventy-four patients with cirrhosis of different etiology and 25 matched healthy controls were included in this study. Bone mineral densitometry at both lumbar spine and femoral neck was measured. Serum total OPG, Klotho protein and vitamin D levels were also determined. Comparisons were performed according to etiology and severity of cirrhosis.

RESULTS

Decreased bone density was observed in cirrhotic patients compared to healthy controls with T = -1.46 and T = -1.37 in lumbar spine and femoral bone respectively compared to T = -0.396 and T = -0.672 in the control group. In the cirrhotic group, osteopenia was observed in 46% in lumbar spine and 51% in femoral bone whereas osteoporosis was observed in 20% in lumbar spine and 9% in femoral bone. Decreased bone density was confirmed, regardless of cirrhosis etiology or stage of liver function. Patients were found to have higher levels of OPG than the control group (136 pg/ml vs. 67 pg/ml, p < 0.001), but lower levels of Klotho protein (1051 pg/ml vs. 1842 pg/ml, p < 0.001) regardless etiology and severity of cirrhosis. High OPG levels were found to be associated with low femoral bone density.

CONCLUSIONS

BMD is lower in cirrhotic patients regardless etiology and severity of liver disease with osteopenia and osteoporosis be present in 50% and 20%, respectively. Higher levels of OPG and lower levels of Klotho protein were observed in cirrhotic patients regardless etiology and severity in comparison to matched healthy group.

Hantaan virus-induced elevation of plasma osteoprotegerin and its clinical implications in hemorrhagic fever with renal syndrome

OBJECTIVES

The bleeding tendency is a hallmark of hemorrhagic fever with renal syndrome (HFRS) after Hantaan virus (HTNV) infection. Growing reports indicate the importance of osteoprotegerin (OPG) in vascular homeostasis, implying OPG might be involved in the pathogenesis of coagulopathy in patients with HFRS.

METHODS

Acute and convalescence plasmas of 32 patients with HFRS were collected. Enzyme-linked immunosorbent assays (ELISA) were used to detect plasma OPG levels and other parameters. The human umbilical vein endothelial cells were stimulated with HTNV and/or tumor necrosis factor-α (TNF-α) to explore the source of OPG.

RESULTS

Plasma OPG levels of patients with HFRS were elevated and correlated positively with the severity of HFRS and negatively with platelet counts. Abundant OPG was released from endothelial cells in response to TNF-α stimuli, along with HTNV infection, which was in accordance with the findings of positive correlations between plasma OPG and TNF-α or c-reactive protein. Importantly, plasma OPG levels correlated positively with activated partial thromboplastin time and the content of d-dimer.

CONCLUSION

These findings suggested that increased plasma OPG levels induced by HTNV might be an important factor for the severity of HFRS, and was likely involved in endothelium dysfunction and hemorrhagic disorder of HFRS, which might contribute to the pathogenesis of hemorrhage in HFRS.

Strategies of Macrophages to Maintain Bone Homeostasis and Promote Bone Repair: A Narrative Review

Bone homeostasis (a healthy bone mass) is regulated by maintaining a delicate balance between bone resorption and bone formation. The regulation of physiological bone remodeling by a complex system that involves multiple cells in the skeleton is closely related to bone homeostasis. Loss of bone mass or repair of bone is always accompanied by changes in bone homeostasis. However, due to the complexity of bone homeostasis, we are currently unable to identify all the mechanisms that affect bone homeostasis. To date, bone macrophages have been considered a third cellular component in addition to osteogenic spectrum cells and osteoclasts. As confirmed by co-culture models or in vivo experiments, polarized or unpolarized macrophages interact with multiple components within the bone to ensure bone homeostasis. Different macrophage phenotypes are prone to resorption and formation of bone differently. This review comprehensively summarizes the mechanisms by which macrophages regulate bone homeostasis and concludes that macrophages can control bone homeostasis from osteoclasts, mesenchymal cells, osteoblasts, osteocytes, and the blood/vasculature system. The elaboration of these mechanisms in this narrative review facilitates the development of macrophage-based strategies for the treatment of bone metabolic diseases and bone defects.

Markers of extracellular matrix remodeling and systemic inflammation in patients with heritable thoracic aortic diseases

Background

In approximately 20% of patients with thoracic aortic aneurysms or dissections a heritable thoracic aortic disease (HTAD) is suspected. Several monogenic connective tissue diseases imply high risk of aortic disease, including both non-syndromic and syndromic forms. There are some studies assessing inflammation and extracellular matrix remodeling in patients with non-hereditary aortic disease, but such studies in patients with hereditary diseases are scarce.

Aims

To quantify markers of extracellular matrix (ECM) and inflammation in patients with vascular connective tissue diseases versus healthy controls.

Methods

Patients with Loeys-Dietz syndrome (LDS, n = 12), Marfan syndrome (MFS, n = 11), and familial thoracic aortic aneurysm 6 (FTAA6, n = 9), i.e., actin alpha 2 (ACTA2) pathogenic variants, were recruited. Exome or genome sequencing was performed for genetic diagnosis. Several markers of inflammation and ECM remodeling were measured in plasma by enzyme immunoassays. Flow cytometry of T-cell subpopulations was performed on a subgroup of patients. For comparison, blood samples were drawn from 14 healthy controls.

Results

(i) All groups of HTAD patients had increased levels matrix metalloproteinase-9 (MMP-9) as compared with healthy controls, also in adjusted analyses, reflecting altered ECM remodeling. (ii) LDS patients had increased levels of pentraxin 3 (PTX3), reflecting systemic inflammation. (iii) LDS patients have increased levels of soluble CD25, a marker of T-cell activation.

Conclusion

Our data suggest that upregulated MMP-9, a matrix degrading enzyme, is a common feature of several subgroups of HTAD. In addition, LDS patients have increased levels of PTX3 reflecting systemic and in particular vascular inflammation.

Left Ventricular Diastolic Dysfunction in Chronic Kidney Disease Patients Not Treated with Dialysis

BACKGROUND

Left ventricular diastolic dysfunction (LVDD) is observed in the early stages of chronic kidney disease (CKD) and may lead to heart failure with preserved ejection fraction (HFpEF). The purpose of our study was to investigate the association between metabolic, nutritional and inflammatory parameters and LVDD in CKD and non-CKD patients.

METHODS

Two groups of patients were recruited to the study: 93 men with CKD and eGFR lower than 60 mL/min/1.73 m2 and 40 men without kidney function decrease with eGFR ≥ 60 mL/min/1.73 m2. Transthoracic echocardiography was performed to evaluate the diastolic function of the left ventricle. Bioimpedance spectroscopy (BIS) was used to measure overhydration and lean body mass. We also measured the serum concentrations of albumin, glucose, haemoglobin A1c (HgbA1c), fibrinogen, C-reactive protein (CRP), tumor necrosis factor-alpha (TNF-alpha) and osteoprotegerin (OPG).

RESULTS

We observed that elevated serum fibrinogen and glucose concentrations were associated with LVDD independently of CKD status. Serum fibrinogen concentrations increased with the advancement of LVDD. Low albumin concentrations in CKD were related with LVDD. In the control group, lower muscle mass presented as lean tissue index (LTI) and lean tissue mass (LTM), and overhydration were associated with LVDD. In the group of patients without kidney function decrease the OPG concentrations were significantly higher in those with LVDD, and they rose with the advancement of LVDD.

CONCLUSIONS

Elevated inflammatory parameters, increased serum glucose concentrations and worse nutritional status are the states that may impair the diastolic function of the left ventricle in CKD and non-CKD patients. Serum OPG levels are elevated in patients without kidney function decrease and LVDD and its concentrations rise with the advancement of LVDD.

Estrogen Receptor Subtypes Elicit a Distinct Gene Expression Profile of Endothelial-Derived Factors Implicated in Atherosclerotic Plaque Vulnerability

In the presence of established atherosclerosis, estrogens are potentially harmful. MMP-2 and MMP-9, their inhibitors (TIMP-2 and TIMP-1), RANK, RANKL, OPG, MCP-1, lysyl oxidase (LOX), PDGF-β, and ADAMTS-4 play critical roles in plaque instability/rupture. We aimed to investigate (i) the effect of estradiol on the expression of the abovementioned molecules in endothelial cells, (ii) which type(s) of estrogen receptors mediate these effects, and (iii) the role of p21 in the estrogen-mediated regulation of the aforementioned factors. Human aortic endothelial cells (HAECs) were cultured with estradiol in the presence or absence of TNF-α. The expression of the aforementioned molecules was assessed by qRT-PCR and ELISA. Zymography was also performed. The experiments were repeated in either ERα- or ERβ-transfected HAECs and after silencing p21. HAECs expressed only the GPR-30 estrogen receptor. Estradiol, at low concentrations, decreased MMP-2 activity by 15-fold, increased LOX expression by 2-fold via GPR-30, and reduced MCP-1 expression by 3.5-fold via ERβ. The overexpression of ERα increased MCP-1 mRNA expression by 2.5-fold. In a low-grade inflammation state, lower concentrations of estradiol induced the mRNA expression of MCP-1 (3.4-fold) and MMP-9 (7.5-fold) and increased the activity of MMP-2 (1.7-fold) via GPR-30. Moreover, p21 silencing resulted in equivocal effects on the expression of the abovementioned molecules. Estradiol induced different effects regarding atherogenic plaque instability through different ERs. The balance of the expression of the various ER subtypes may play an important role in the paradoxical characterization of estrogens as both beneficial and harmful.

Crosstalk between bone and other organs

Bone has long been considered as a silent organ that provides a reservoir of calcium and phosphorus, traditionally. Recently, further study of bone has revealed additional functions as an endocrine organ connecting systemic organs of the whole body. Communication between bone and other organs participates in most physiological and pathological events and is responsible for the maintenance of homeostasis. Here, we present an overview of the crosstalk between bone and other organs. Furthermore, we describe the factors mediating the crosstalk and review the mechanisms in the development of potential associated diseases. These connections shed new light on the pathogenesis of systemic diseases and provide novel potential targets for the treatment of systemic diseases.

Osteoprotegerin/receptor activator of nuclear factor‑κB ligand are involved in periodontitis‑promoted vascular calcification

The present study explored the potential role of osteoprotegerin (OPG)/receptor activator of nuclear factor-κB (RANK)/receptor activator of nuclear factor-κB ligand (RANKL) in promoting vascular calcification by periodontitis. Thirty-six male Wistar rats were randomly assigned to four groups to establish animal models as follows: the sham group (group C), vascular calcification group (group VDN), periodontitis group (group CP), and test group (group CP+VDN). After eight weeks, all the rats were sacrificed. The periodontal and vascular calcification indices were detected. Quantitative polymerase chain reaction (qPCR), immunohistochemistry, western blot analysis, and enzyme-linked immunosorbent assay (ELISA) were used to quantify OPG/RANK/RANKL expression in vascular tissue and serum. Protein expression analyses revealed the expression of OPG and RANKL in the vascular tissues of the four groups. The expression of OPG in group C was the highest, which was similar to group CP+VDN, and the expression of OPG in groups CP and VDN were lower. However, the expression of RANKL was inversely correlated with OPG, and the ratio of RANKL/OPG was also higher in groups CP and VDN than that in groups C and CP+VDN. In conclusion, OPG/RANK/RANKL may play an essential role in the promotion of vascular calcification by periodontitis. However, the expression levels of OPG and RANKL were not simply superimposed when periodontitis and vascular calcification co-existed.

Laboratory Predictors of Prognosis in Cardiogenic Shock Complicating Acute Myocardial Infarction

Cardiogenic shock is a state of reduced cardiac output leading to hypotension, pulmonary congestion, and hypoperfusion of tissues and vital organs. Despite the advances in intensive care over the last years, the morbidity and mortality of patients remain high. The available studies of patients with cardiogenic shock suggest a connection between clinical variables, the level of biomarkers, the results of imaging investigations, strategies of management and the outcome of this group of patients. The management of patients with cardiogenic shock initially complicating acute myocardial infarction is challenging, and the number of studies in this area is growing fast. The purpose of this review is to summarize the currently available evidence on cardiogenic shock initially complicating acute myocardial infarction with particular attention to predictors of prognosis, focusing on laboratory variables (established and new), and to discuss the practical implementation. Currently available scoring systems developed during the past few decades predict the clinical outcome of this group of patients using some of the established biomarkers among other variables. With the new laboratory biomarkers that have shown their predictive value in cardiogenic shock outcomes, a new design of scoring systems would be of interest. Identifying high-risk patients offers the opportunity for early decision-making.

The Roles of RANK/RANKL/OPG in Cardiac, Skeletal, and Smooth Muscles in Health and Disease

Although their physiology and functions are very different, bones, skeletal and smooth muscles, as well as the heart have the same embryonic origin. Skeletal muscles and bones interact with each other to enable breathing, kinesis, and the maintenance of posture. Often, muscle and bone tissues degenerate synchronously under various conditions such as cancers, space travel, aging, prolonged bed rest, and neuromuscular diseases. In addition, bone tissue, skeletal and smooth muscles, and the heart share common signaling pathways. The RANK/RANKL/OPG pathway, which is essential for bone homeostasis, is also implicated in various physiological processes such as sarcopenia, atherosclerosis, and cardiovascular diseases. Several studies have reported bone-skeletal muscle crosstalk through the RANK/RANKL/OPG pathway. This review will summarize the current evidence indicating that the RANK/RANKL/OPG pathway is involved in muscle function. First, we will briefly discuss the role this pathway plays in bone homeostasis. Then, we will present results from various sources indicating that it plays a physiopathological role in skeletal, smooth muscle, and cardiac functions. Understanding how the RANK/RANKL/OPG pathway interferes in several physiological disorders may lead to new therapeutic approaches aimed at protecting bones and other tissues with a single treatment.

The association of plasma osteoprotegerin levels and functional outcomes post endovascular thrombectomy in acute ischemic stroke patients: a retrospective observational study

Background

Osteoprotegerin (OPG), also known as osteoclastogenesis inhibitory factor, is a tumor necrosis factor receptor superfamily component. There is an established relationship between OPG and cardiovascular disease. We hypothesized that plasma OPG levels are associated with functional outcomes in acute ischemic stroke patients who have undergone endovascular thrombectomy (EVT).

Methods

From April 2014 through December 2020, a total of 360 acute ischemic stroke patients who underwent EVT were prospectively included in this retrospective observational study. Plasma OPG was measured after fasting for 12 postoperative hours after EVT. A modified Rankin Scale (mRS) was used to assess functional outcomes 3 months after index stroke occurrence. Univariate and multivariate binary logistic regression and ordinal logistic regression analyses were performed to investigate the association of plasma OPG levels with poor functional outcomes.

Results

Overall, 145 (40.2%) patients had poor (mRS > 2) outcomes. The mean ± standard deviation plasma OPG level was 200.2 ± 74.4 pg/mL. Multivariate analysis after adjusting for sex, body mass index, and variables with p < 0.1 in the preceding univariate analysis revealed high plasma OPG levels were independently associated with poor functional outcomes (highest tertile vs. lowest tertile of OPG; odds ratios (OR) 2.121, 95% confidence interval (CI) [1.089-4.191], p = 0.037 in binary logistic regression, OR 2.102, 95% CI [1.301-3.412], p = 0.002 in ordinal logistic regression analysis).

Conclusions

This study demonstrated that higher plasma OPG levels were associated with poor functional outcomes in acute ischemic stroke patients who underwent EVT.

Effects of local cryotherapy on systemic endothelial activation, dysfunction, and vascular inflammation in adjuvant-induced arthritis (AIA) rats

Aim

This study explored the systemic vascular effects of local cryotherapy with a focus on endothelial changes and arterial inflammation in the model of rat adjuvant-induced arthritis (AIA).

Methods

Cryotherapy was applied twice a day on hind paws of AIA rats from the onset of arthritis to the acute inflammatory phase. Endothelial activation was studied in the aorta by measuring the mRNA levels of chemokines (CXCL-1, MCP-1 (CCL-2), MIP-1α (CCL-3)) and adhesion molecules (ICAM-1, VCAM-1) by qRT-PCR. Endothelial dysfunction was measured in isolated aortic and mesenteric rings. Aortic inflammation was evaluated via the mRNA expression of pro-inflammatory cytokines (TNF-α, IL-6) by qRT-PCR and leucocyte infiltration analysis (flow cytometry). Plasma levels of TNF-α, IL-6, IL-1β, IL-17A, and osteoprotegerin (OPG) were measured using Multiplex/ELISA.

Results

AIA was associated with an increased aortic expression of CXCL-1 and ICAM-1 as well as an infiltration of leucocytes and increased mRNA expression of IL-6, IL-1β, and TNF-α. Local cryotherapy, which decreased arthritis score and structural damages, reduced aortic mRNA expression of CXCL-1, IL-6, IL-1β, and TNF-α, as well as aortic infiltration of leucocytes (T lymphocytes, monocytes/macrophages, neutrophils) and improved acetylcholine-induced vasorelaxation in the aorta and mesenteric arteries. Plasma levels of IL-17A and OPG were significantly reduced by cryotherapy, while the number of circulating leucocytes was not. IL-17A levels positively correlated with endothelial activation and dysfunction.

Conclusion

In the AIA model, local cryotherapy reduced systemic endothelial activation, immune cell infiltration, and endothelial dysfunction. Mechanistically, the reduction of circulating levels of IL-17A appears as the possible link between joint cooling and the remote vascular effects.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13075-022-02774-1.

Association Between Serum Selenium Concentration and OPG/RANKL/RANK Axis in Patients with Arterial Hypertension

The aim of the study was to determine the relationship between the serum selenium concentration (Se-S) and the blood concentrations of osteoprotegerin (OPG), receptor activator of nuclear factor kappa-Β ligand (RANKL) and the OPG/RANKL ratio in patients with arterial hypertension. The study group comprised 138 patients with arterial hypertension (age: 56.04 ± 11.59 years). Se-S was determined in all the subjects. Based on the Se-S, the following subgroups were distinguished: a subgroup of patients with a lower Se-S ("low-Se", Se-S < median) and a subgroup of patients with a higher Se-S ("high-Se", Se-S ≥ median). Moreover, the blood concentrations of the parameters of bone metabolism and extraskeletal calcification were assessed: OPG and RANKL. The OPG/RANKL ratio was calculated. In the "low-Se" subgroup, the RANKL concentration was statistically significantly lower, and the OPG/RANKL ratio was statistically significantly higher than in the patients in the "high-Se" subgroup. The correlation analysis showed the negative linear relationships between Se-S and OPG (r = - 0.25, p < 0.05) and between Se-S and OPG/RANKL (r = - 0.47, p < 0.05). Moreover, Se-S positively correlated with RANKL (r = 0.33, p < 0.05). In regression analysis, higher body mass index (BMI), smoking and lower Se-S were independently associated with a higher OPG/RANKL ratio, while lower BMI, use of diuretics, β-blockers and ACE inhibitors and lower OPG/RANKL ratio with effective blood pressure control. In summary, in the group of patients with arterial hypertension, lower Se-S is associated with an unfavourable prognostic panel of parameters of bone metabolism and extraskeletal calcification. Lower Se-S is an independent risk factor for a higher OPG/RANKL ratio, which is an independent prediction factor of ineffective blood pressure control in patients with hypertension.