Vascular Calcification: New Insights Into BMP Type I Receptor A

Expression pattern of the bone morphogenetic protein-4 and its relationship with inflammation, vascular injury in patients suffered the arterial occlusive diseases

OBJECTIVES

Bone morphogenetic protein-4 (BMP4) has been proved to be an important regulatory factor for the pathological process of atherosclerosis (AS). However, there are few related clinical studies. This study aims to investigate the levels of plasma BMP4 in patients suffering from the arterial occlusive diseases (ACD) characterized by AS, and further to test the relationship between BMP4 and inflammation and vascular injury.

METHODS

A total of 38 ACD patients (the ACD group) and 38 healthy people for the physical examination (the control group) were enrolled. The plasma in each subject from both groups was obtained to test the levels of BMP4, tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), IL-10, and vascular endothelial cadherin (VE-cadherin), and the relationship between BMP4 and the detected indicators above were further analyzed.

RESULTS

Compared with the control group, the patients in the ACD group displayed significant elevations in the neutrophil to lymphocyte ratio [NLR, 1.63 (1.26, 1.91) vs 3.43 (2.16, 6.61)] and platelet to lymphocyte ratio [PLR, 6.37 (5.26, 7.74) vs 15.79 (7.97, 20.53)], while decrease in the lymphocyte to monocyte ratio [LMR, 5.67 (4.41, 7.14) vs 3.43 (2.07, 3.74)] (all P<0.05). Besides, the ACD patients displayed significant elevations in plasma BMP4 [581.26 (389.85, 735.64) pg/mL vs 653.97(510.95, 890.43) pg/mL], TNF-α [254.16 (182.96, 340.70) pg/mL vs 293.29(238.90, 383.44) pg/mL], and VE-cadherin [1.54 (1.08, 2.13) ng/mL vs 1.85 (1.30, 2.54) ng/mL], and decrease in IL-10 [175.89 (118.39, 219.25) pg/mL vs 135.92 (95.80, 178.04) pg/mL] (all P<0.05). While the levels of IL-1β remained statistically comparable between the 2 groups (P=0.09). Furthermore, the plasma BMP4 levels were further revealed to be positively correlated with the levels of IL-1β (r=0.35), TNF-α (r=0.31) and VE-cadherin (r=0.47), while they were negatively correlated with the levels of IL-10 (r=-0.37; all P<0.01).

CONCLUSIONS

After ACD occurrence, the patients' plasma concentrations of BMP4 would be upregulated, which may serve as a candidate to indicate the levels of inflammation and vascular injury.

Leucine-Rich Alpha-2 Glycoprotein 1 Accumulates in Complicated Atherosclerosis and Promotes Calcification

Atherosclerosis is the primary cause of cardiovascular disease. The development of plaque complications, such as calcification and neo-angiogenesis, strongly impacts plaque stability and is a good predictor of mortality in patients with atherosclerosis. Despite well-known risk factors of plaque complications, such as diabetes mellitus and chronic kidney disease, the mechanisms involved are not fully understood. We and others have identified that the concentration of circulating leucine-rich α-2 glycoprotein 1 (LRG1) was increased in diabetic and chronic kidney disease patients. Using apolipoprotein E knockout mice (ApoE-/-) (fed with Western diet) that developed advanced atherosclerosis and using human carotid endarterectomy, we showed that LRG1 accumulated into an atherosclerotic plaque, preferentially in calcified areas. We then investigated the possible origin of LRG1 and its functions on vascular cells and found that LRG1 expression was specifically enhanced in endothelial cells via inflammatory mediators and not in vascular smooth muscle cells (VSMC). Moreover, we identified that LRG1 was able to induce calcification and SMAD1/5-signaling pathways in VSMC. In conclusion, our results identified for the first time that LRG1 is a direct contributor to vascular calcification and suggest a role of this molecule in the development of plaque complications in patients with atherosclerosis.

Cationic proteins from eosinophils bind bone morphogenetic protein receptors promoting vascular calcification and atherogenesis

AIMS

Blood eosinophil count and eosinophil cationic protein (ECP) concentration are risk factors of cardiovascular diseases. This study tested whether and how eosinophils and ECP contribute to vascular calcification and atherogenesis.

METHODS AND RESULTS

Immunostaining revealed eosinophil accumulation in human and mouse atherosclerotic lesions. Eosinophil deficiency in ΔdblGATA mice slowed atherogenesis with increased lesion smooth muscle cell (SMC) content and reduced calcification. This protection in ΔdblGATA mice was muted when mice received donor eosinophils from wild-type (WT), Il4-/-, and Il13-/- mice or mouse eosinophil-associated-ribonuclease-1 (mEar1), a murine homologue of ECP. Eosinophils or mEar1 but not interleukin (IL) 4 or IL13 increased the calcification of SMC from WT mice but not those from Runt-related transcription factor-2 (Runx2) knockout mice. Immunoblot analyses showed that eosinophils and mEar1 activated Smad-1/5/8 but did not affect Smad-2/3 activation or expression of bone morphogenetic protein receptors (BMPR-1A/1B/2) or transforming growth factor (TGF)-β receptors (TGFBR1/2) in SMC from WT and Runx2 knockout mice. Immunoprecipitation showed that mEar1 formed immune complexes with BMPR-1A/1B but not TGFBR1/2. Immunofluorescence double-staining, ligand binding, and Scatchard plot analysis demonstrated that mEar1 bound to BMPR-1A and BMPR-1B with similar affinity. Likewise, human ECP and eosinophil-derived neurotoxin (EDN) also bound to BMPR-1A/1B on human vascular SMC and promoted SMC osteogenic differentiation. In a cohort of 5864 men from the Danish Cardiovascular Screening trial and its subpopulation of 394 participants, blood eosinophil counts and ECP levels correlated with the calcification scores of different arterial segments from coronary arteries to iliac arteries.

CONCLUSION

Eosinophils release cationic proteins that can promote SMC calcification and atherogenesis using the BMPR-1A/1B-Smad-1/5/8-Runx2 signalling pathway.

Vascular calcification: Molecular mechanisms and therapeutic interventions

Vascular calcification (VC) is recognized as a pathological vascular disorder associated with various diseases, such as atherosclerosis, hypertension, aortic valve stenosis, coronary artery disease, diabetes mellitus, as well as chronic kidney disease. Therefore, it is a life-threatening state for human health. There were several studies targeting mechanisms of VC that revealed the importance of vascular smooth muscle cells transdifferentiating, phosphorous and calcium milieu, as well as matrix vesicles on the progress of VC. However, the underlying molecular mechanisms of VC need to be elucidated. Though there is no acknowledged effective therapeutic strategy to reverse or cure VC clinically, recent evidence has proved that VC is not a passive irreversible comorbidity but an active process regulated by many factors. Some available approaches targeting the underlying molecular mechanism provide promising prospects for the therapy of VC. This review aims to summarize the novel findings on molecular mechanisms and therapeutic interventions of VC, including the role of inflammatory responses, endoplasmic reticulum stress, mitochondrial dysfunction, iron homeostasis, metabolic imbalance, and some related signaling pathways on VC progression. We also conclude some recent studies on controversial interventions in the clinical practice of VC, such as calcium channel blockers, renin-angiotensin system inhibitions, statins, bisphosphonates, denosumab, vitamins, and ion conditioning agents.

Recent progress in the biology and physiology of BMP-8a

PURPOSE

BMP-8a is a member of bone morphogenetic proteins (BMPs) and plays a regulatory role in human growth and development as a transcription regulator. This review aims to summarize the current research on the impact and mechanism of BMP-8a in female and male reproduction, formation and eruption of teeth, bone and cartilage development, tissue differentiation, disease occurrence, progression and prognosis.

METHODS

The phrases "BMP-8a," "BMPs," "regulator," "mechanism," "osteoblast," "cartilage," "cancer," "disease," and "inflammation" were searched in the PubMed database. The abstracts were evaluated, and a series of original publications and reviews were examined.

RESULTS

According to the search, BMP-8a affects the development of the uterus by inhibiting luteinization and plays an important role in late spermatogenesis. It is highly expressed in osteogenesis and differentially expressed in chondrogenesis. Furthermore, BMP-8a has a significant impact on the occurrence, development and prognosis of various diseases.

CONCLUSIONS

BMP-8a regulates important factors and pathways, such as SMAD2/3 and SMAD1/5/8, to promote or inhibit the developmental processes of human reproductive organs. BMP-8a is also a member of the BMP family of proteins that regulates chondrogenesis and osteogenesis. In addition to its osteoinductive capabilities, BMP-8a is involved in the progression of diverse cancers.

Fibroblast growth factor 8 (FGF8) up-regulates gelatinase expression in chondrocytes through nuclear factor-κB p65

INTRODUCTION

Gelatinases, namely MMP2 and MMP9, are involved in the natural turnover of articular cartilage, as well as the loss of the cartilage matrix in osteoarthritis (OA). Studies have reported that fibroblast growth factor 8 (FGF8) promoted the degradation of cartilage in OA. In the present study, we predicted that FGF8 promoted chondrocyte expression and secretion of gelatinases by activating NF-κB p65 signaling.

MATERIALS AND METHODS

Primary chondrocytes from C57 mice were cultured with recombinant FGF8. RNA sequencing was employed to explore the gene expression changes of gelatinases. Gelatin zymography was used to determine the activation of gelatinases. Western blot was used to investigate the expression of the gelatinases and NF-κB p65 signaling pathways, and immunofluorescence staining and NF-κB inhibitor assays were performed to confirm the activation of NF-κB p65 signaling.

RESULTS

FGF8 could increase the expression and activity of gelatinases in primary chondrocytes. And FGF8-induced expression of gelatinases was regulated through activation of NF-κB signaling with acetylated p65 accumulating in the cell nucleus. We further found that the NF-κB inhibitor, BAY 11-7082, could suppress up-regulation of gelatinase induced by FGF8.

CONCLUSION

FGF8 enhanced the expression and activity of MMP2 and MMP9 in chondrocytes via NF-κB p65 signaling.

Case report: A primary calcified cardiac mass in right atrium partially obstructs the tricuspid valve in a patient on hemodialysis

Primary cardiac calcification is a rare benign mass in patients with end-stage renal disease. A few cases have been reported in the literatures. In this case study, during a routine checkup for hemodialysis, a transthoracic echocardiography on a 19-year-old male showed a cardiac mass in the right atrium that was partially obstructing the tricuspid valve. Cardiac magnetic resonance imaging showed a well-circumscribed, homogeneous “shadow” in the right atrium; it measured 29 × 27 mm, had equal T1- and T2-weighted signal intensities, and was adjacent to the tricuspid valve. According to 18F-fluorodeoxyglucose positron emission tomography combined with computed tomography, there was a dense circular shadow in the right atrium abutting the tricuspid valve, but there was no increase in glucose metabolism. Median sternotomy was performed for the surgical resection of the mass, and a cardiopulmonary bypass was completed. The mass was completely removed. The patient recovered well and was discharged 10 days after the surgery. Histological examination showed that the mass contained multiple calcified nodules. No mass recurrence was found by echocardiography during the 12th-month follow-up.