N-acetylglucosamine-1-Phosphate Transferase Suppresses Lysosomal Hydrolases in Dysfunctional Osteoclasts: A Potential Mechanism for Vascular Calcification

Nε-Carboxymethyl-Lysine Mediates Vascular Calcification in Diabetes Caused by Impaired Osteoclastic Resorption Activity Through NFATc1-GNPTAB

Nε-carboxymethyl-lysine (CML) is closely associated with vascular calcification in diabetes. Osteoclasts are the only cells with bone resorption activity that have the potential to reverse calcification. This study aimed to investigate the mechanism of CML in the bone resorption activity of macrophage-derived osteoclasts in diabetic calcified plaques. Macrophage-derived osteoclasts were found to be present in calcified plaques of the anterior tibial artery in patients with diabetic amputation. Furthermore, in vitro studies showed that CML induced the differentiation of macrophages into osteoclasts, although, the bone resorption activity of these macrophage-derived osteoclasts was impaired. CML significantly increased the levels of NFATc1and GNPTAB. In vivo studies showed that there was more calcium deposition and less TRAP was less in the CML group while this effect was reversed after silencing of NFATc1. In conclusion, CML mediates NFATc1-GNPTAB to regulate bone resorption activity of osteoclasts in diabetic calcified plaques. CML promotes macrophage differentiation into osteoclasts, but their function is impaired in diabetic calcified plaques through NFATc1-GNPTAB, which eventually leads to the further progression of vascular calcification in diabetes.

The Cell Origin and Role of Osteoclastogenesis and Osteoblastogenesis in Vascular Calcification

Arterial calcification refers to the abnormal deposition of calcium salts in the arterial wall, which results in vessel lumen stenosis and vascular remodeling. Studies increasingly show that arterial calcification is a cell mediated, reversible and active regulated process similar to physiological bone mineralization. The osteoblasts and chondrocytes-like cells are present in large numbers in the calcified lesions, and express osteogenic transcription factor and bone matrix proteins that are known to initiate and promote arterial calcification. In addition, osteoclast-like cells have also been detected in calcified arterial walls wherein they possibly inhibit vascular calcification, similar to the catabolic process of bone mineral resorption. Therefore, tilting the balance between osteoblast-like and osteoclast-like cells to the latter maybe a promising therapeutic strategy against vascular calcification. In this review, we have summarized the current findings on the origin and functions of osteoblast-like and osteoclast-like cells in the development and progression of vascular progression, and explored novel therapeutic possibilities.

New Insights into the Roles of Monocytes/Macrophages in Cardiovascular Calcification Associated with Chronic Kidney Disease

Cardiovascular disease (CVD) is an important cause of death in patients with chronic kidney disease (CKD), and cardiovascular calcification (CVC) is one of the strongest predictors of CVD in this population. Cardiovascular calcification results from complex cellular interactions involving the endothelium, vascular/valvular cells (i.e., vascular smooth muscle cells, valvular interstitial cells and resident fibroblasts), and monocyte-derived macrophages. Indeed, the production of pro-inflammatory cytokines and oxidative stress by monocyte-derived macrophages is responsible for the osteogenic transformation and mineralization of vascular/valvular cells. However, monocytes/macrophages show the ability to modify their phenotype, and consequently their functions, when facing environmental modifications. This plasticity complicates efforts to understand the pathogenesis of CVC-particularly in a CKD setting, where both uraemic toxins and CKD treatment may affect monocyte/macrophage functions and thereby influence CVC. Here, we review (i) the mechanisms by which each monocyte/macrophage subset either promotes or prevents CVC, and (ii) how both uraemic toxins and CKD therapies might affect these monocyte/macrophage functions.

WITHDRAWN: Catalytically inactive phosphatase MTMR12 is a novel regulator of osteoclast function through F-actin ring formation

This article has been withdrawn as it was submitted without the knowledge of several co-authors. Under journal policies, all listed authors must have provided final approval of the submitted manuscript and the Corresponding Author is asked to confirm this approval during the submission process. Several of the listed co-authors have stated that they were not involved in the drafting of the manuscript and were not made aware of their inclusion as authors. Therefore they have been removed from this record. The Publisher apologizes for any inconvenience this may cause. The full Elsevier Policy on Article Withdrawal can be found at https://www.elsevier.com/about/our-business/policies/article-withdrawal.

Interferon-γ Released by Activated CD8+ T Lymphocytes Impairs the Calcium Resorption Potential of Osteoclasts in Calcified Human Aortic Valves

In calcific aortic valve disease (CAVD), activated T lymphocytes localize with osteoclast regions; however, the functional consequences of this association remain unknown. We hypothesized that CD8+ T cells modulate calcification in CAVD. CAVD valves (n = 52) dissected into noncalcified and calcified portions were subjected to mRNA extraction, real-time quantitative PCR, enzyme-linked immunosorbent assay, and immunohistochemical analyses. Compared with noncalcified portions, calcified regions exhibited elevated transcripts for CD8, interferon (IFN)-γ, CXCL9, Perforin 1, Granzyme B, and heat shock protein 60. Osteoclast-associated receptor activator of NK-κB ligand (RANKL), tartrate-resistant acid phosphatase (TRAP), and osteoclast-associated receptor increased significantly. The stimulation of tissue with phorbol-12-myristate-13-acetate and ionomycin, recapitulating CAVD microenvironment, resulted in IFN-γ release. Real-time quantitative PCR detected mRNAs for CD8+ T-cell activation (Perforin 1, Granzyme B). In stimulated versus unstimulated organoid cultures, elevated IFN-γ reduced the mRNAs encoding for RANKL, TRAP, and Cathepsin K. Molecular imaging showed increased calcium signal intensity in stimulated versus unstimulated parts. CD14+ monocytes treated either with recombinant human IFN-γ or with conditioned media-derived IFN-γ exhibited low levels of Cathepsin K, TRAP, RANK, and tumor necrosis factor receptor-associated factor 6 mRNAs, whereas concentrations of the T-cell co-activators CD80 and CD86 increased in parallel with reduced osteoclast resorptive function, effects abrogated by neutralizing anti-IFN-γ antibodies. CD8+ cell-derived IFN-γ suppresses osteoclast function and may thus favor calcification in CAVD.