Regulation of vascular smooth muscle cell calcification by syndecan-4/FGF-2/PKCα signalling and cross-talk with TGFβ

Adipocyte-derived shed Syndecan-4 suppresses lipolysis contributing to impaired adipose tissue browning and adaptive thermogenesis

Lipolysis in white adipose tissue (WAT) provides fatty acids as energy substrates for thermogenesis to increase energy expenditure. Syndecan-4 (Sdc4) is a transmembrane proteoglycan bearing heparan sulfate chains. Although single nucleotide polymorphisms (SNPs) of the Sdc4 gene have been identified linking to metabolic syndromes, its specific function in adipose tissue remains obscure. Here, we show that Sdc4 serves as a regulator of lipid metabolism and adaptive thermogenesis. Sdc4 expression and shedding are elevated in the white adipose tissue (WAT) of diet-induced obese mice. Adipocyte-specific deletion of Sdc4 promotes lipolysis and WAT browning, thereby raising whole-body energy expenditure to protect against diet-induced obesity. Mechanistically, fibroblast growth factor 2 (FGF2) is a paracrine factor that maintains energy homeostasis. Elevated shed Sdc4 concentrates and delivers FGF2 to fibroblast growth factor receptor 1 (FGFR1) on adipocytes, which in turn suppresses lipolysis by reducing hormone-sensitive lipase (HSL) activity, thus exaggerating adipose tissue dysfunction upon high-fat diet induction. Sdc4-deficient adipocytes show higher lipolytic and thermogenic capacity by enhancing HSL phosphorylation and UCP1 expression. Overall, our study reveals that adipocyte-derived shed Sdc4 is a novel suppressor of lipolysis, contributing to decreased energy expenditure, thus exaggerating obesity. Targeting shed Sdc4 is a potential therapeutic strategy for obesity.

Age Differences in Aortic Stenosis

Aortic stenosis (AS) is a significant and growing concern, with a prevalence of 2-3% in individuals aged over 65 years. Moreover, with an aging global population, the prevalence is anticipated to double by 2050. Indeed, AS can arise from various etiologies, including calcific trileaflets, congenital valve abnormalities (e.g., bicuspid and unicuspid valves), and post-rheumatic, whereby each has a distinct influence that shapes the onset and progression of the disease. The normal aortic valve has a trilaminar structure comprising the fibrosa, spongiosa, and ventricularis, which work together to maintain its function. In calcific AS, the disease begins with early calcification starting in high mechanical stress areas of the valve and progresses slowly over decades, eventually leading to extensive calcification resulting in impaired valve function. This process involves mechanisms similar to atherosclerosis, including lipid deposition, chronic inflammation, and mineralization. The progression of calcific AS is strongly associated with aging, with additional risk factors including male gender, smoking, dyslipidemia, and metabolic syndrome exacerbating the condition. Conversely, congenital forms of AS, such as bicuspid and unicuspid aortic valves, result in an earlier disease onset, typically 10-20 years earlier than that observed in patients with a normal tricuspid aortic valve. Rheumatic AS, although less common in developed countries due to effective antibiotic treatments, also exhibits age-related characteristics, with an earlier onset in individuals who experienced rheumatic fever in their youth. The only curative therapies currently available are surgical and transcatheter aortic valve replacement (TAVR). However, these options are sometimes too invasive for older patients; thus, management of AS, particularly in older patients, requires a comprehensive approach that considers age, disease severity, comorbidities, frailty, and each patient's individual needs. Although the valves used in TAVR demonstrate promising midterm durability, long-term data are still required, especially when used in younger individuals, usually with low surgical risk. Moreover, understanding the causes and mechanisms of structural valve deterioration is crucial for appropriate treatment selections, including valve selection and pharmacological therapy, since this knowledge is essential for optimizing the lifelong management of AS.

Super-Enhancer-Driven Syndecan-4 Regulates Intercellular Communication in Hypoxic Pulmonary Hypertension

BACKGROUND

Unveiling pro-proliferation genes involved in crosstalk between pulmonary artery endothelial cells and pulmonary artery smooth muscle cells (PASMCs) are important to improving the therapeutic outcome of pulmonary hypertension (PH). Although growing studies have shown that super-enhancers (SEs) play a pivotal role in pathological and physiological processes, the SE-associated genes in PH and their impact on PASMC proliferation remain largely unexplored.

METHODS AND RESULTS

We used serotype 5 adenovirus-associated virus to interfere with syndecan-4 and constructed an SU5416 combined with hypoxia-PH model. Chromatin immunoprecipitation sequencing analysis, chromatin immunoprecipitation quantitative polymerase chain reaction, and bioinformatics were used to confirm early growth response 1 was involved in regulating syndecan-4-associated SE in PASMCs. The effects of syndecan-4 and its underlying mechanisms were subsequently elucidated using Western blot, coimmunoprecipitation, and cell coculture assays. Herein, we identified a novel SE-associated gene, syndecan-4, in hypoxia-exposed PASMCs. Syndecan-4 was transcriptionally driven by early growth response 1 via an SE and was significantly overexpressed in hypoxic PASMCs and plasma from patients with PH. Mechanism studies revealed that syndecan-4 induces PASMC proliferation by interacting and regulating protein kinase C α ubiquitination. In addition, syndecan-4 was enriched in exosomes secreted from hypoxic PASMCs, which subsequently transported and led to pulmonary artery endothelial cell dysfunction. Syndecan-4 inhibition in hypoxia by serotype 5 adenovirus-associated virus treatment attenuated the pulmonary artery remodeling and development of PH in vivo.

CONCLUSIONS

Taken together, our results demonstrate that an SE-driven syndecan-4 modulates crosstalk of PASMCs and pulmonary artery endothelial cells and promotes vascular remodeling via the protein kinase C α and exosome pathway, thus providing potential targets for the early diagnosis and treatment of hypoxic PH.

Syndecan-4 inhibition attenuates cartilage degeneration in temporomandibular joint osteoarthritis

BACKGROUND

Syndecan 4 (SDC4), a type I transmembrane proteoglycan, serves as a critical link between chondrocytes and the extracellular matrix.

OBJECTIVE

This study aimed to explore the role of SDC4 in cartilage degeneration of temporomandibular joint osteoathritis (TMJOA).

METHODS

Condylar chondrocytes were stimulated with varying concentrations of recombinant rat interleukin-1β (rrIL-1β) and SDC4 small interfering RNA (si-SDC4). Anti-SDC4 ectodomain-specific antibodies or IgG were intra-articularly administrated in a TMJOA model rats. SDC4 conditional knockout (SDC4-cKO) and Sdc4flox/flox mice were induced TMJOA. Cartilage degeneration was assessed using haematoxylin & eosin (H&E) and safranin O (SO) staining. Protein levels of SDC4, matrix metalloproteinases (MMPs), a disintegrin and metalloproteinase with a thrombospondin motifs 5 (ADAMTS5), tumour necrosis factor α (TNFα), type II collagen (Col-II), aggrecan (ACAN), cleaved caspase 3 (CASP3), Ki67 and related pathways in condylar cartilage were evaluated by immunohistochemical (IHC) staining or western blot assays.

RESULTS

SDC4 expression was evidently increased in MIA-model animals compared to control groups. rrIL-1β stimulation increased the expression of SDC4, MMP3 and ADAMTS5 expression in chondrocytes, while decreasing the expression of Col-II. These effects were reversed by si-SDC4 in vitro. In vivo, SDC4 blockade reduced the death of chondrocytes and the loss of cartilage matrix, which was evidenced by increased expression of Col-II and ACAN, and a decrease in SDC4, MMP13 and cleaved-CASP3-positive cells. Furthermore, the protein levels of ACAN and Ki67 were elevated, and the ERK1/2 and P38 signalling pathways were activated following SDC4 inhibition.

CONCLUSIONS

SDC4 inhibition significantly ameliorates condylar cartilage degeneration, which was mediated, at least partly, through P38 and ERK1/2 signalling. Inhibition of SDC4 may be of great value for the treatment of TMJOA.

Effects of Empagliflozin on Vascular and Skeletal Mineralization in Hyperlipidemic Mice

Cardiovascular disease and osteoporosis, major causes of morbidity and mortality, are associated with hyperlipidemia. Recent studies show that empagliflozin (EMPA), an inhibitor of sodium-glucose cotransporter-2 (SGLT2), improves cardiovascular health. In preclinical animal studies, EMPA mitigates vascular calcification in the males but its effects in the females are not known. Thus, we used female mice to test the effects of EMPA on calcification in the artery wall, cardiac function, and skeletal bone. By serial in vivo microCT imaging, we followed the progression of aortic calcification and bone mineral density in young and older female Apoe-/- mice fed a high-fat diet with or without EMPA. The two different age groups were used to compare early vs. advanced stages of aortic calcification. Results show that EMPA treatment increased urine glucose levels. Aortic calcium content increased in both the controls and the EMPA-treated mice, and EMPA did not affect progression of aortic calcium content in both young and older mice. However, 3-D segmentation analysis of aortic calcium deposits on microCT images revealed that EMPA-treated mice had significantly less surface area and volume of calcified deposits as well as fewer numbers of deposits than the control mice. To test for direct effects on vascular cell calcification, we treated murine aortic smooth muscle cells with EMPA, and results showed a slight inhibition of alkaline phosphatase activity and inflammatory matrix calcification. As for skeletal bone, EMPA-treated mice had significantly lower BMD than the controls in both the lumbar vertebrae and femoral bones in both young and older mice. The findings suggest that, in hyperlipidemic female mice, unlike males, SGLT2 inhibition with empagliflozin does not mitigate progression of aortic calcification and may even lower skeletal bone density.

Associations between pan-immune-inflammation value and abdominal aortic calcification: a cross-sectional study

Background

Abdominal aortic calcification (AAC) pathogenesis is intricately linked with inflammation. The pan-immune-inflammation value (PIV) emerges as a potential biomarker, offering reflection into systemic inflammatory states and assisting in the prognosis of diverse diseases. This research aimed to explore the association between PIV and AAC.

Methods

Employing data from the National Health and Nutrition Examination Survey (NHANES), this cross-sectional analysis harnessed weighted multivariable regression models to ascertain the relationship between PIV and AAC. Trend tests probed the evolving relationship among PIV quartiles and AAC. The study also incorporated subgroup analysis and interaction tests to determine associations within specific subpopulations. Additionally, the least absolute shrinkage and selection operator (LASSO) regression and multivariable logistic regression were used for characteristics selection to construct prediction model. Nomograms were used for visualization. The receiver operator characteristic (ROC) curve, calibration plot and decision curve analysis were applied for evaluate the predictive performance.

Results

From the cohort of 3,047 participants, a distinct positive correlation was observed between PIV and AAC. Subsequent to full adjustments, a 100-unit increment in PIV linked to an elevation of 0.055 points in the AAC score (β=0.055, 95% CI: 0.014-0.095). Categorizing PIV into quartiles revealed an ascending trend: as PIV quartiles increased, AAC scores surged (β values in Quartile 2, Quartile 3, and Quartile 4: 0.122, 0.437, and 0.658 respectively; P for trend <0.001). Concurrently, a marked rise in SAAC prevalence was noted (OR values for Quartile 2, Quartile 3, and Quartile 4: 1.635, 1.842, and 2.572 respectively; P for trend <0.01). Individuals aged 60 or above and those with a history of diabetes exhibited a heightened association. After characteristic selection, models for predicting AAC and SAAC were constructed respectively. The AUC of AAC model was 0.74 (95%CI=0.71-0.77) and the AUC of SAAC model was 0.84 (95%CI=0.80-0.87). According to the results of calibration plots and DCA, two models showed high accuracy and clinical benefit.

Conclusion

The research findings illuminate the potential correlation between elevated PIV and AAC presence. Our models indicate the potential utility of PIV combined with other simple predictors in the assessment and management of individuals with AAC.

Vascular calcification: from the perspective of crosstalk

Vascular calcification (VC) is highly correlated with cardiovascular disease morbidity and mortality, but anti-VC treatment remains an area to be tackled due to the ill-defined molecular mechanisms. Regardless of the type of VC, it does not depend on a single cell but involves multi-cells/organs to form a complex cellular communication network through the vascular microenvironment to participate in the occurrence and development of VC. Therefore, focusing only on the direct effect of pathological factors on vascular smooth muscle cells (VSMCs) tends to overlook the combined effect of other cells and VSMCs, including VSMCs-VSMCs, ECs-VMSCs, Macrophages-VSMCs, etc. Extracellular vesicles (EVs) are a collective term for tiny vesicles with a membrane structure that are actively secreted by cells, and almost all cells secrete EVs. EVs docked on the surface of receptor cells can directly mediate signal transduction or transfer their contents into the cell to elicit a functional response from the receptor cells. They have been proven to participate in the VC process and have also shown attractive therapeutic prospects. Based on the advantages of EVs and the ability to be detected in body fluids, they may become a novel therapeutic agent, drug delivery vehicle, diagnostic and prognostic biomarker, and potential therapeutic target in the future. This review focuses on the new insight into VC molecular mechanisms from the perspective of crosstalk, summarizes how multi-cells/organs interactions communicate via EVs to regulate VC and the emerging potential of EVs as therapeutic methods in VC. We also summarize preclinical experiments on crosstalk-based and the current state of clinical studies on VC-related measures.

The Pulmonary Endothelial Glycocalyx Modifications in Glypican 1 Knockout Mice Do Not Affect Lung Endothelial Function in Physiological Conditions

The endothelial glycocalyx is a dynamic signaling surface layer that is involved in the maintenance of cellular homeostasis. The glycocalyx has a very diverse composition, with glycoproteins, proteoglycans, and glycosaminoglycans interacting with each other to form a mesh-like structure. Due to its highly interactive nature, little is known about the relative contribution of each glycocalyx constituent to its overall function. Investigating the individual roles of the glycocalyx components to cellular functions and system physiology is challenging, as the genetic manipulation of animals that target specific glycocalyx components may result in the development of a modified glycocalyx. Thus, it is crucial that genetically modified animal models for glycocalyx components are characterized and validated before the development of mechanistic studies. Among the glycocalyx components, glypican 1, which acts through eNOS-dependent mechanisms, has recently emerged as a player in cardiovascular diseases. Whether glypican 1 regulates eNOS in physiological conditions is unclear. Herein, we assessed how the deletion of glypican 1 affects the development of the pulmonary endothelial glycocalyx and the impact on eNOS activity and endothelial function. Male and female 5-9-week-old wild-type and glypican 1 knockout mice were used. Transmission electron microscopy, immunofluorescence, and immunoblotting assessed the glycocalyx structure and composition. eNOS activation and content were assessed by immunoblotting; nitric oxide production was assessed by the Griess reaction. The pulmonary phenotype was evaluated by histological signs of lung injury, in vivo measurement of lung mechanics, and pulmonary ventilation. Glypican 1 knockout mice showed a modified glycocalyx with increased glycocalyx thickness and heparan sulfate content and decreased expression of syndecan 4. These alterations were associated with decreased phosphorylation of eNOS at S1177. The production of nitric oxides was not affected by the deletion of glypican 1, and the endothelial barrier was preserved in glypican 1 knockout mice. Pulmonary compliance was decreased, and pulmonary ventilation was unaltered in glypican 1 knockout mice. Collectively, these data indicate that the deletion of glypican 1 may result in the modification of the glycocalyx without affecting basal lung endothelial function, validating this mouse model as a tool for mechanistic studies that investigate the role of glypican 1 in lung endothelial function.

Myocardial fibrosis and calcification are attenuated by microRNA-129-5p targeting Asporin and Sox9 in cardiac fibroblasts

Myocardial fibrosis and calcification associate with adverse outcomes in nonischemic heart failure. Cardiac fibroblasts (CF) transition into myofibroblasts (MF) and osteogenic fibroblasts (OF) to promote myocardial fibrosis and calcification. However, common upstream mechanisms regulating both CF-to-MF transition and CF-to-OF transition remain unknown. microRNAs are promising targets to modulate CF plasticity. Our bioinformatics revealed downregulation of miR-129-5p and upregulation of its targets small leucine-rich proteoglycan Asporin (ASPN) and transcription factor SOX9 as common in mouse and human heart failure (HF). We experimentally confirmed decreased miR-129-5p and enhanced SOX9 and ASPN expression in CF in human hearts with myocardial fibrosis and calcification. miR-129-5p repressed both CF-to-MF and CF-to-OF transition in primary CF, as did knockdown of SOX9 and ASPN. Sox9 and Aspn are direct targets of miR-129-5p that inhibit downstream β-catenin expression. Chronic Angiotensin II infusion downregulated miR-129-5p in CF in WT and TCF21-lineage CF reporter mice, and it was restored by miR-129-5p mimic. Importantly, miR-129-5p mimic not only attenuated progression of myocardial fibrosis, calcification marker expression, and SOX9 and ASPN expression in CF but also restored diastolic and systolic function. Together, we demonstrate miR-129-5p/ASPN and miR-129-5p/SOX9 as potentially novel dysregulated axes in CF-to-MF and CF-to-OF transition in myocardial fibrosis and calcification and the therapeutic relevance of miR-129-5p.

A nonobstructive condition: Medial arterial calcification

Vascular calcification, including intimal and medial calcification, is closely associated with a significant increase in cardiovascular diseases. Although increased understandings were achieved, people still know much more about intimal calcification than medial calcification because the latter doesn't obstruct the arterial lumen, commonly considered as a non-significant finding. We clarified the pathologic characteristic of medial calcification, its difference from intimal calcification, principally focused on its clinical relevance, such as diagnosis, nosogenesis, and hemodynamics. We underline the importance of identifying and distinguishing medial calcification, understanding its effect to local/systematic arterial compliance, and relationship to diabetic neuropathy. Recent studies emphasize do not ignore its predictive role in cardiovascular mortality. It is of great clinical significance to summarize the mechanisms of occurrence, lesion characteristics, diagnostic methods, pathogenic mechanisms, hemodynamic changes, and the distinction as well as association of intimal calcification with intimal calcification.

Copper-containing chitosan-based hydrogels enabled 3D-printed scaffolds to accelerate bone repair and eliminate MRSA-related infection

Bone defect combined with drug-resistant bacteria-related infection is a thorny challenge in clinic. Herein, 3D-printed polyhydroxyalkanoates/β-tricalcium phosphate (PHA/β-TCP, PT) scaffolds were prepared by fused deposition modeling. Then copper-containing carboxymethyl chitosan/alginate (CA/Cu) hydrogels were integrated with the scaffolds via a facile and low-cost chemical crosslinking method. The resultant PT/CA/Cu scaffolds could not only promote proliferation but also osteogenic differentiation of preosteoblasts in vitro. Moreover, PT/CA/Cu scaffolds exhibited a strong antibacterial activity towards a broad-spectrum of bacteria including methicillin-resistant Staphylococcus aureus (MRSA) through inducing the intercellular generation of reactive oxygen species. In vivo experiments further demonstrated that PT/CA/Cu scaffolds significantly accelerated bone repair of cranial defects and efficiently eliminated MRSA-related infection, showing potential for application in infected bone defect therapy.

The role of the glypican and syndecan families of heparan sulfate proteoglycans in cardiovascular function and disease

Heparan sulfate proteoglycans (HSPGs) are proteoglycans formed by a core protein to which one or multiple heparan sulfate chains are covalently bound. They are ubiquitously expressed in cellular surfaces and can be found in the extracellular matrix and secretory vesicles. The cellular effects of HSPGs comprehend multiple functionalities that include 1) the interaction with other membrane surface proteins to act as a substrate for cellular migration, 2) acting as a binding site for circulating molecules, 3) to have a receptor role for proteases, 4) to act as a coreceptor that can provide finetuning of growth factor receptor activity threshold, and 5) to activate intracellular signaling pathways (Sarrazin S, Lamanna WC, Esko JD. Cold Spring Harb Perspect Biol 3: a004952, 2011). Among the different families of HSPGs, the syndecan and glypican families of HSPGs have gained increased attention in relation to their effects on cardiovascular cells and potential role in disease progression. In this review, we will summarize the effects of syndecan and glypican homologs on the different cardiovascular cell types and discuss their contribution to common processes found in cardiovascular diseases (inflammation, hypertrophy, and vascular remodeling) as well as their potential role in the development and progression of specific diseases including hypertension, heart failure, and atherosclerosis.

The two facets of receptor tyrosine kinase in cardiovascular calcification-can tyrosine kinase inhibitors benefit cardiovascular system?

Tyrosine kinase inhibitors (TKIs) are widely used in cancer treatment due to their effectiveness in cancer cell killing. However, an off-target of this agent limits its success. Cardiotoxicity-associated TKIs have been widely reported. Tyrosine kinase is involved in many regulatory processes in a cell, and it is involved in cancer formation. Recent evidence suggests the role of tyrosine kinase in cardiovascular calcification, specifically, the calcification of heart vessels and valves. Herein, we summarized the accumulating evidence of the crucial role of receptor tyrosine kinase (RTK) in cardiovascular calcification and provided the potential clinical implication of TKIs-related ectopic calcification. We found that RTKs, depending on the ligand and tissue, can induce or suppress cardiovascular calcification. Therefore, RTKs may have varying effects on ectopic calcification. Additionally, in the context of cardiovascular calcification, TKIs do not always relate to an unfavored outcome-they might offer benefits in some cases.

Distinct role of mitochondrial function and protein kinase C in intimal and medial calcification in vitro

Introduction

Vascular calcification (VC) is a major risk factor for cardiovascular morbidity and mortality. Depending on the location of mineral deposition within the arterial wall, VC is classified as intimal and medial calcification. Using in vitro mineralization assays, we developed protocols triggering both types of calcification in vascular smooth muscle cells (SMCs) following diverging molecular pathways.

Materials and methods and results

Human coronary artery SMCs were cultured in osteogenic medium (OM) or high calcium phosphate medium (CaP) to induce a mineralized extracellular matrix. OM induces osteoblast-like differentiation of SMCs-a key process in intimal calcification during atherosclerotic plaque remodeling. CaP mimics hyperphosphatemia, associated with chronic kidney disease-a risk factor for medial calcification. Transcriptomic analysis revealed distinct gene expression profiles of OM and CaP-calcifying SMCs. OM and CaP-treated SMCs shared 107 differentially regulated genes related to SMC contraction and metabolism. Real-time extracellular efflux analysis demonstrated decreased mitochondrial respiration and glycolysis in CaP-treated SMCs compared to increased mitochondrial respiration without altered glycolysis in OM-treated SMCs. Subsequent kinome and in silico drug repurposing analysis (Connectivity Map) suggested a distinct role of protein kinase C (PKC). In vitro validation experiments demonstrated that the PKC activators prostratin and ingenol reduced calcification triggered by OM and promoted calcification triggered by CaP.

Conclusion

Our direct comparison results of two in vitro calcification models strengthen previous observations of distinct intracellular mechanisms that trigger OM and CaP-induced SMC calcification in vitro. We found a differential role of PKC in OM and CaP-calcified SMCs providing new potential cellular and molecular targets for pharmacological intervention in VC. Our data suggest that the field should limit the generalization of results found in in vitro studies using different calcification protocols.

Basic fibroblast growth factor inhibits aortic valvular interstitial cells calcification via Notch1 pathway

Calcific aortic valve disease (CAVD) is an active pathological process mediated by abnormal activation and transdifferentiation of valvular interstitial cells (VICs). The present study aims to investigate the function and underlying mechanism of the basic fibroblast growth factor (BFGF) on osteogenic differentiation of VICs. Porcine VICs cultured with osteogenic induction medium are supplemented with or without BFGF. Morphology of VICs is identified by fluorescein isothiocyanate-labeled phalloidin, the cell viability is assessed by the cell counting kit-8 method, and protein and mRNA expression level of osteogenic differentiation markers, including Runx2, osteopontin, and Sp7, are verified by western blot analysis and quantitative real-time PCR, respectively. RNA sequencing is used to identify changes in gene profiles. Alizarin Red S staining is used to measure calcium deposition. The results demonstrate that the content of calcium deposition and the expression level of osteogenic markers are downregulated by supplementing BFGF. Notch1 signaling pathway is extracted as a candidate target after bioinformatics analysis by RNA sequencing. The transfection of si-Notch1 abolishes the calcification inhibitory effect of BFGF. Taken together, our findings shed the light on the mechanism and potential therapeutics of BFGF for CAVD.

Integrative analysis of transcriptome-wide association study and mRNA expression profile identified candidate genes and pathways associated with aortic aneurysm and dissection

BACKGROUND

Aortic aneurysm and dissection (AAD) are a set of life-threatening diseases. This study aimed to investigate the genetic mechanisms of AAD by integrating transcriptome-wide association study (TWAS) and mRNA expression profile.

METHODS

The genome-wide association study (GWAS) summary data of AAD was obtained from the UK Biobank, which contains 452,264 White British individuals, including 1470 AAD patients. The TWAS analysis was performed by integrating expression quantitative trait loci (eQTL) data of aorta and the GWAS dataset of AAD using the FUSION software. The TWAS significant genes and differentially expressed genes (DEGs) identified by mRNA expression profile of aortic dissection were integrated to find common genes and biological process. For TWAS significant genes, protein-protein interaction (PPI) network analysis was further conducted based on STRING database.

RESULTS

TWAS identified 423 genes with P < 0.05. After comparing the results of TWAS and mRNA expression profile, 11 overlapping genes (PDE8B, IKBKE, HMGA1, PKM, CHST1, DUS3L, S100A16, PTGS1, RAB38, PDLIM5, NOL6) and 15 common gene ontology (GO) terms (including extracellular matrix organization, external encapsulating structure organization, cell-substrate adhesion, actin filament-based process, focal adhesion, protein kinase activity) were identified. 9 hub genes of the TWAS results were identified via PPI network analysis, including RPS9, RPS18, RSRC1, DNAJC3, HBS1L, PRKCA, NCAM1, ITGB3, FTSJ3.

CONCLUSION

Multiple candidate genes and biological processes associated with AAD were identified by the present integrative study of TWAS and mRNA expression profile. Further studies are needed to elucidate the genetic mechanisms of AAD.

Glypican 1 and syndecan 1 differently regulate noradrenergic hypertension development: Focus on IP3R and calcium

BACKGROUND

Vascular dysfunction is a checkpoint to the development of hypertension. Heparan sulfate proteoglycans (HSPG) participate in nitric oxide (NO) and calcium signaling, key regulators of vascular function. The relationship between HSPG-mediated NO and calcium signaling and vascular dysfunction has not been explored. Likewise, the role of HSPG on the control of systemic blood arterial pressure is unknown. Herein, we sought to determine if the HSPG syndecan 1 and glypican 1 control systemic blood pressure and the progression of hypertension.

PURPOSE

To determine the mechanisms whereby glypican 1 and syndecan 1 regulate vascular tone and contribute to the development of noradrenergic hypertension.

EXPERIMENTAL APPROACH AND KEY RESULTS

By assessing systemic arterial blood pressure we observed that syndecan 1 (Sdc1-/-) and glypican 1 (Gpc1-/-) knockout mice show a similar phenotype of decreased systolic blood pressure that is presented in a striking manner in the Gpc1-/- strain. Gpc1-/- mice are also uniquely protected from a norepinephrine hypertensive challenge failing to become hypertensive. This phenotype was associated with impaired calcium-dependent vasoconstriction and altered expression of calcium-sensitive proteins including SERCA and calmodulin. In addition, Gpc1-/- distinctively showed decreased IP3R activity and increased calcium storage in the endoplasmic reticulum.

CONCLUSIONS AND IMPLICATIONS

Glypican 1 is a trigger for the development of noradrenergic hypertension that acts via IP3R- and calcium-dependent signaling pathways. Glypican 1 may be a potential target for the development of new therapies for resistant hypertension or conditions where norepinephrine levels are increased.

Two-faced Janus: The dual role of macrophages in atherosclerotic calcification

Calcification is an independent predictor of atherosclerosis-related cardiovascular events. Microcalcification is linked to inflamed, unstable lesions, in comparison to the fibrotic stable plaque phenotype generally associated with advanced calcification. This paradox relates to recognition that calcification presents in a wide spectrum of manifestations that differentially impact plaque’s fate. Macrophages, the main inflammatory cells in atherosclerotic plaque, have a multifaceted role in disease progression. They crucially control the mineralization process, from microcalcification to the osteoid metaplasia of bone-like tissue. It is a bilateral interaction that weighs heavily on the overall plaque fate but remains rather unexplored. This review highlights current knowledge about macrophage phenotypic changes in relation to and interaction with the calcifying environment. On the one hand, macrophage-led inflammation kickstarts microcalcification through a multitude of interlinked mechanisms, which in turn stimulates phenotypic changes in vascular cell types to drive microcalcification. Macrophages may also modulate the expression/activity of calcification inhibitors and inducers, or eliminate hydroxyapatite nucleation points. Contrarily, direct exposure of macrophages to an early calcifying milieu impacts macrophage phenotype, with repercussions for plaque progression and/or stability. Macrophages surrounding macrocalcification deposits show a more reparative phenotype, modulating extracellular matrix, and expressing osteoclast genes. This phenotypic shift favours gradual displacement of the pro-inflammatory hubs; the lipid necrotic core, by macrocalcification. Parallels to bone metabolism may explain many of these changes to macrophage phenotype, with advanced calcification able to show homeostatic osteoid metaplasia. As the targeted treatment of vascular calcification developing in atherosclerosis is thus far severely lacking, it is crucial to better understand its mechanisms of development.

Role of Glycosylation in Vascular Calcification

Glycosylation is an important step in post-translational protein modification. Altered glycosylation results in an abnormality that causes diseases such as malignancy and cardiovascular diseases. Recent emerging evidence highlights the importance of glycosylation in vascular calcification. Two major types of glycosylation, N-glycosylation and O-glycosylation, are involved in vascular calcification. Other glycosylation mechanisms, which polymerize the glycosaminoglycan (GAG) chain onto protein, resulting in proteoglycan (PG), also have an impact on vascular calcification. This paper discusses the role of glycosylation in vascular calcification.

Multiple functions of autophagy in vascular calcification

Background

Vascular calcification is a closely linked to cardiovascular diseases, such as atherosclerosis, chronic kidney disease, diabetes, hypertension and aging. The extent of vascular calcification is closely correlate with adverse clinical events and cardiovascular all-cause mortality. The role of autophagy in vascular calcification is complex with many mechanistic unknowns.

Methods

In this review, we analyze the current known mechanisms of autophagy in vascular calcification and discuss the theoretical advantages of targeting autophagy as an intervention against vascular calcification.

Results

Here we summarize the functional link between vascular calcification and autophagy in both animal models of and human cardiovascular disease. Firstly, autophagy can reduce calcification by inhibiting the osteogenic differentiation of VSMCs related to ANCR, ERα, β-catenin, HIF-1a/PDK4, p62, miR-30b, BECN1, mTOR, SOX9, GHSR/ERK, and AMPK signaling. Conversely, autophagy can induce osteoblast differentiation and calcification as mediated by CREB, degradation of elastin, and lncRNA H19 and DUSP5 mediated ERK signaling. Secondly, autophagy also links apoptosis and vascular calcification through AMPK/mTOR/ULK1, Wnt/β-catenin and GAS6/AXL synthesis, as apoptotic cells become the nidus for calcium-phosphate crystal deposition. The failure of mitophagy can activate Drp1, BNIP3, and NR4A1/DNA‑PKcs/p53 mediated intrinsic apoptotic pathways, which have been closely linked to the formation of vascular calcification. Additionally, autophagy also plays a role in osteogenesis by regulating vascular calcification, which in turn regulates expression of proteins related to bone development, such as osteocalcin, osteonectin, etc. and regulated by mTOR, EphrinB2 and RhoA. Furthermore, autophagy also promotes vitamin K2-induced MC3T3 E1 osteoblast differentiation and FGFR4/FGF18- and JNK/complex VPS34–beclin-1-related bone mineralization via vascular calcification.

Conclusion

The interaction between autophagy and vascular calcification are complicated, with their interaction affected by the disease process, anatomical location, and the surrounding microenvironment. Autophagy activation in existent cellular damage is considered protective, while defective autophagy in normal cells result in apoptotic activation. Identifying and maintaining cells at the delicate line between these two states may hold the key to reducing vascular calcification, in which autophagy associated clinical strategy could be developed.

Molecular mechanisms of osteogenesis and antibacterial activity of Cu-bearing Ti alloy in a bone defect model with infection in vivo

OBJECTIVE

The antibacterial activity of copper (Cu)-alloy biomaterials has shown a great potential in clinical application. Here, we evaluated the osteogenesis and antibacterial effects of Ti6Al4V-6.5wt%Cu alloy in an in vivo model of infected bone defects and determine their responsible proteins and pathways using proteomics.

METHODS

After bone defects were filled with Ti6Al4V and Ti6Al4V-6.5wt%Cu implants for 6 week, the tissue and bone samples around the implants were harvested for radiographic, micro-CT, histological, and bone-related gene expression analyses. An iTRAQ-based protein identification/quantification approach was used to analyze the osteogenic and antibacterial effects of Ti6Al4V-6.5wt%Cu alloy.

RESULTS

Imaging and histological results showed Ti6Al4V alloy induced a stronger inflammatory response than Ti6Al4V-6.5wt%Cu alloy; imaging results and osteogenic protein levels showed Ti6Al4V-6.5wt%Cu alloy exerted a stronger osteogenic effect. In vitro experiment, we found the Ti6Al4V-6.5wt%Cu had significant antibacterial effects and inhibited the activity of Staphylococcus aureus in the early stage. In addition, the bacterial biofilm formed in Ti6Al4V-6.5wt%Cu group was significantly lower than that in Ti6Al4V group. Proteomic screening of 4279 proteins resulted in 35 differentially expressed proteins for further examination which were mainly associated with the cellular process, metabolic process, stimulus response, and cellular component organization. In further exploration of the mechanism of osteogenic mineralization of Ti6Al4V-6.5wt%Cu alloy, we found out SDC4 and AGRN were the top two target proteins associated with osteogenic differentiation and bone mineralization.

CONCLUSION

Ti6Al4V-6.5wt%Cu alloy shows a great potential as a bone implant material due to its positive effects against bacterial infection and on bone formation.

THE TRANSLATIONAL POTENTIAL OF THIS ARTICLE

At present, titanium alloys and other non-antibacterial metal materials are used in orthopedic internal fixation operations. Our study demonstrates that Ti6Al4V-6.5wt%Cu alloy has good antibacterial and osteogenic effects in vivo and in vitro. This means that Ti6Al4V-6.5wt%Cu alloy may become a new kind of antimicrobial metallic material as internal fixation material to continuously exert its antimicrobial effects and reduce the infection rate after clinical internal fixation.

Dermatologic Adverse Events Associated with Selective Fibroblast Growth Factor Receptor Inhibitors: Overview, Prevention, and Management Guidelines

Fibroblast growth factor receptor (FGFR) tyrosine kinases, which are expressed on the cell membrane, are involved in a wide range of biological functions such as cell proliferation, survival, migration, and differentiation. The identification of FGFR fusions and other alterations in a wide range of solid tumors, including cholangiocarcinoma and bladder cancer, has resulted in the development of several selective FGFR inhibitors for use in these indications, for example, infigratinib, erdafitinib, derazantinib, pemigatinib, and futibatinib. In addition to the typical adverse events associated with tyrosine kinases, the FGFR inhibitors appear to give rise to a number of adverse events affecting the skin. Here we describe these skin events, which include the more common nail adverse events (e.g., onycholysis), palmar-plantar erythrodysesthesia syndrome, and stomatitis, as well as less common reactions such as calciphylaxis. This review aims to provide oncologists with an understanding of these dermatologic events and proposes guidelines for the management of treatment-emergent dermatologic adverse events. Awareness of possible adverse events associated with specific drugs should allow physicians to educate patients as to what to expect and implement effective management plans at the earliest possible opportunity, thereby preventing premature discontinuation while maintaining patient quality of life. IMPLICATIONS FOR PRACTICE: Identification of fibroblast growth factor receptor (FGFR) aberrations in cholangiocarcinoma and bladder cancer led to development of selective FGFR inhibitors for these indications, based on clinical benefit and safety profiles. The most frequent adverse events (AEs) include those affecting skin, hair, and nails, a unique class effect of these agents. These are usually mild to moderate in severity. This work reviewed skin AEs reported with FGFR inhibitors and provides management guidelines for physicians, aiming to increase awareness of skin events and provide effective treatment strategies. Early intervention and effective management may improve treatment adherence, optimize outcomes, and improve quality of life.

Syndecan 4 contributes to osteoclast differentiation induced by RANKL through enhancing autophagy

Periodontitis is a common chronic disease. Osteoclast differentiation contributes to alveolar bone resorption which is a distinct phenomenon during periodontitis. Syndecan 4 (SDC4), a member of the syndecan family, was found to be highly expressed during periodontitis. However, little is known about its role in periodontitis. Herein, we explored the role of SDC4 in osteoclast differentiation. An experimental periodontitis rat model was established by ligating the right first molar. The SDC4 expression in periodontium was detected by western blot and immunofluorescence. Our study demonstrated that SDC4 was highly expressed in the periodontium of periodontitis rats. It was positively transcriptionally regulated by NF-κB. SDC4 silencing abrogated osteoclast differentiation induced by RANKL, while SDC4 overexpression enhanced osteoclast differentiation. Moreover, SDC4 enhanced autophagy induced by RANKL. 3-MA, an autophagy inhibitor, was employed to explore whether SDC4 impacts osteoclast differentiation through activating autophagy. Treatment with 3-MA abolished osteoclast differentiation which was enhanced by SDC4, indicating that SDC4 promotes osteoclast differentiation through activating autophagy. This study reveals that SDC4 may contribute to osteoclast differentiation during periodontitis through activating autophagy. It sheds light on the important role of SDC4 in periodontitis.

The Interplay of WNT and PPARγ Signaling in Vascular Calcification

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

X-ray Micro-Computed Tomography: An Emerging Technology to Analyze Vascular Calcification in Animal Models

Vascular calcification describes the formation of mineralized tissue within the blood vessel wall, and it is highly associated with increased cardiovascular morbidity and mortality in patients with chronic kidney disease, diabetes, and atherosclerosis. In this article, we briefly review different rodent models used to study vascular calcification in vivo, and critically assess the strengths and weaknesses of the current techniques used to analyze and quantify calcification in these models, namely 2-D histology and the o-cresolphthalein assay. In light of this, we examine X-ray micro-computed tomography (µCT) as an emerging complementary tool for the analysis of vascular calcification in animal models. We demonstrate that this non-destructive technique allows us to simultaneously quantify and localize calcification in an intact vessel in 3-D, and we consider recent advances in µCT sample preparation techniques. This review also discusses the potential to combine 3-D µCT analyses with subsequent 2-D histological, immunohistochemical, and proteomic approaches in correlative microscopy workflows to obtain rich, multifaceted information on calcification volume, calcification load, and signaling mechanisms from within the same arterial segment. In conclusion we briefly discuss the potential use of µCT to visualize and measure vascular calcification in vivo in real-time.

A LCMS-based untargeted lipidomics analysis of cleft palate in mouse

BACKGROUND

Recent studies have shown that lipid metabolism was abnormal during the formation of cleft palate. However, the composition of these lipid species remains unclear.

OBJECTIVE

Aims of this study were to identify the lipid species components and reveal the key lipid metabolic disorders in cleft palate formation.

METHODS

The pregnant mice were divided into experimental group exposed to all-trans retinoic acid (RA-treated group) (n = 12) and control group (n = 12) at embryonic gestation day 10.5 (E0.5). The component of the palatal tissue metabolome was analyzed using a LCMS-based nontargeted lipidomics approach. Multivariate statistical analysis was then carried out to assess the differences between the RA-treated group and the control group.

RESULTS

Twenty-nine lipid species were found to discriminate between RA-treated and control embryos. Among them, 28 lipid species increased and 1 lipid species decreased in the RA-treated group. Among these lipids, 13 were triglycerides, 9 were PEs, 3 were PCs, 2 were PSs, 2 were DGs. Further analysis of the number of carbons and unsaturated bond of triglycerides showed that TGs with high unsaturated bonds constituted a higher fraction in the RA-treated group. A higher amount of triglycerides containing 52, 54, 56, 58, 60 carbons, and 1 to 8 unsaturated bonds. Of note, under RA treatment, TG 50:1, 52:2, 56:6and 60:8 became the most prominent.

CONCLUSION

Lipid metabolism is significantly different in the formation of cleft palate induced by RA, and the unsaturated triglycerides increased in the RA-treated group may play an important role in the formation of cleft palate.

An overview of the mechanisms in vascular calcification during chronic kidney disease

PURPOSE OF REVIEW

Chronic kidney disease (CKD) facilitates a unique environment to strongly accelerate vascular calcification - the pathological deposition of calcium-phosphate in the vasculature. These calcifications are associated with the excessive cardiovascular mortality of CKD patients.

RECENT FINDINGS

Vascular calcification is a multifaceted active process, mediated, at least partly, by vascular smooth muscle cells. These cells are able to transdifferentiate into cells with osteo/chondrogenic properties, which exert multiple effects to facilitate vascular tissue mineralization. As the understanding of the underlying pathophysiology increases, first therapeutic concepts begin to emerge.

SUMMARY

This brief review provides an overview on the so far known mechanisms involved in the initiation and progression of vascular calcification in CKD.

The biology of vascular calcification

Vascular calcification (VC), characterized by different mineral deposits (i.e., carbonate apatite, whitlockite and hydroxyapatite) accumulating in blood vessels and valves, represents a relevant pathological process for the aging population and a life-threatening complication in acquired and in genetic diseases. Similarly to bone remodeling, VC is an actively regulated process in which many cells and molecules play a pivotal role. This review aims at: (i) describing the role of resident and circulating cells, of the extracellular environment and of positive and negative factors in driving the mineralization process; (ii) detailing the types of VC (i.e., intimal, medial and cardiac valve calcification); (iii) analyzing rare genetic diseases underlining the importance of altered pyrophosphate-dependent regulatory mechanisms; (iv) providing therapeutic options and perspectives.

Innate and adaptive immunity in cardiovascular calcification

Despite the focus placed on cardiovascular research, the prevalence of vascular and valvular calcification is increasing and remains a leading contributor of cardiovascular morbidity and mortality. Accumulating studies provide evidence that cardiovascular calcification is an inflammatory disease in which innate immune signaling becomes sustained and/or excessive, shaping a deleterious adaptive response. The triggering immune factors and subsequent inflammatory events surrounding cardiovascular calcification remain poorly understood, despite sustained significant research interest and support in the field. Most studies on cardiovascular calcification focus on innate cells, particularly macrophages' ability to release pro-osteogenic cytokines and calcification-prone extracellular vesicles and apoptotic bodies. Even though substantial evidence demonstrates that macrophages are key components in triggering cardiovascular calcification, the crosstalk between innate and adaptive immune cell components has not been adequately addressed. The only therapeutic options currently used are invasive procedures by surgery or transcatheter intervention. However, no approved drug has shown prophylactic or therapeutic effectiveness. Conventional diagnostic imaging is currently the best method for detecting, measuring, and assisting in the treatment of calcification. However, these common imaging modalities are unable to detect early subclinical stages of disease at the level of microcalcifications; therefore, the vast majority of patients are diagnosed when macrocalcifications are already established. In this review, we unravel the current knowledge of how innate and adaptive immunity regulate cardiovascular calcification; and put forward differences and similarities between vascular and valvular disease. Additionally, we highlight potential immunomodulatory drugs with the potential to target calcification and propose avenues in need of further translational inquiry.

The Vicious Cycle of Arterial Stiffness and Arterial Media Calcification

Arterial media calcification and arterial stiffness are independent predictors of cardiovascular mortality. Both processes reinforce one another, creating a vicious cycle in which transdifferentiation of endothelial cells and vascular smooth muscle cells play a central role. Physiological functioning of vascular smooth muscle cells in the arterial medial layer greatly depends on normal endothelial cell behavior. Endothelial or intimal layer cells are the primary sensors of pathological triggers circulating in the blood during, for example, ageing or inflammation, and often can be seen as initiators of this vicious cycle. As such, the search for treatment of arterial media calcification, which until now has been mainly concentrated at the level of the vascular smooth cell, may need to be expanded to intimal layer targets.

Interactive and Multifactorial Mechanisms of Calcific Vascular and Valvular Disease

Calcific vascular and valvular disease (CVVD) is widespread and has major health consequences. Although coronary artery calcification has long been associated with hyperlipidemia and increased mortality, recent evidence suggests that its progression is increased in association with cholesterol-lowering HMG-CoA reductase inhibitors ('statins') and long-term, high-intensity exercise. A nationwide trial showed no cardiovascular benefit of vitamin D supplements. Controversy remains as to whether calcium deposits in plaque promote or prevent plaque rupture. CVVD appears to occur through mechanisms similar to those of intramembranous, endochondral, and osteophytic skeletal bone formation. New evidence implicates autotaxin, endothelial-mesenchymal transformation, and microRNA and long non-coding RNA (lncRNA) as novel regulatory factors. New therapeutic options are being developed.

Serum untargeted lipidomic profiling reveals dysfunction of phospholipid metabolism in subclinical coronary artery disease

Purpose: Disturbed metabolism of cholesterol and triacylglycerols (TGs) carries increased risk for coronary artery calcification (CAC). However, the exact relationship between individual lipid species and CAC remains unclear. The aim of this study was to identify disturbances in lipid profiles involved in the calcification process, in an attempt to propose potential biomarker candidates.

Patients and methods: We studied 70 patients at intermediate risk for coronary artery disease who had undergone coronary calcification assessment using computed tomography and Agatston coronary artery calcium score (CACS). Patients were divided into three groups: with no coronary calcification (NCC; CACS: 0; n=26), mild coronary calcification (MCC; CACS: 1–250; n=27), or severe coronary calcification (SCC; CACS: >250; n=17). Patients’ serum samples were analyzed using liquid chromatography-mass spectrometry in an untargeted lipidomics approach.

Results: We identified 103 lipids within the glycerolipid, glycerophospholipid, sphingolipid, and sterol lipid classes. After false discovery rate correction, phosphatidylcholine (PC)(16:0/20:4) in higher levels and PC(18:2/18:2), PC(36:3), and phosphatidylethanolamine(20:0/18:2) in lower levels were identified as correlates with SCC compared to NCC. There were no significant differences in the levels of individual TGs between the three groups; however, clustering the lipid profiles showed a trend for higher levels of saturated and monounsaturated TGs in SCC compared to NCC. There was also a trend for lower TG(49:2), TG(51:1), TG(54:5), and TG(56:8) levels in SCC compared to MCC.

Conclusion: In this study we investigated the lipidome of patients with coronary calcification. Our results suggest that the calcification process may be associated with dysfunction in autophagy. The lipidomic biomarkers revealed in this study may aid in better assessment of patients with subclinical coronary artery disease.

Novel contribution to clubfoot pathogenesis: The possible role of extracellular matrix proteins

Idiopathic pes equinovarus (clubfoot) is a congenital deformity of the feet and lower legs. Clubfoot belongs to a group of fibro-proliferative disorders but its origin remains unknown. Our study aimed to achieve the first complex proteomic comparison of clubfoot contracted tissue of the foot (medial side; n = 16), with non-contracted tissue (lateral side; n = 13). We used label-free mass spectrometry quantification and immunohistochemistry. Seven proteins were observed to be significantly upregulated in the medial side (asporin, collagen type III, V, and VI, versican, tenascin-C, and transforming growth factor beta induced protein) and four in the lateral side (collagen types XII and XIV, fibromodulin, and cartilage intermediate layer protein 2) of the clubfoot. Comparison of control samples from cadavers brought only two different protein concentrations (collagen types I and VI). We also revealed pathological calcification and intracellular positivity of transforming growth factor beta only in the contracted tissue of clubfoot. Most of the 11 differently expressed proteins are strongly related to the extracellular matrix architecture and we assume that they may play specific roles in the pathogenesis of this deformity. These proteins seem to be promising targets for future investigations and treatment of this disease. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res.

Hypertension: Focus on autoimmunity and oxidative stress

Understanding the causal role of the immune and inflammatory responses in hypertension has led to questions regarding the links between hypertension and autoimmunity. Immune pathology in primary hypertension mimics several autoimmune mechanisms observed in the pathogenesis of systemic lupus erythematosus, psoriasis, systemic sclerosis, rheumatoid arthritis and periodontitis. More importantly, the prevalence of hypertension in patients with these autoimmune diseases is significantly increased, when compared to control populations. Clinical and epidemiological evidence is reviewed along with possible mechanisms linking hypertension and autoimmunity. Inflammation and oxidative stress are linked in a self-perpetuating cycle that significantly contributes to the vascular dysfunction and renal damage associated with hypertension. T cell, B cell, macrophage and NK cell infiltration into these organs is essential for this pathology. Effector cytokines such as IFN-γ, TNF-α and IL-17 affect Na⁺/H⁺ exchangers in the kidney. In blood vessels, they lead to endothelial dysfunction and loss of nitric oxide bioavailability and cause vasoconstriction. Both renal and vascular effects are, in part, mediated through induction of reactive oxygen species-producing enzymes such as superoxide anion generating NADPH oxidases and dysfunction of anti-oxidant systems. These mechanisms have recently become important therapeutic targets of novel therapies focused on scavenging oxidative (isolevuglandin) modification of neo-antigenic peptides. Effects of classical immune targeted therapies focused on immunosuppression and anti-cytokine treatments are also reviewed.

FTI-277 inhibits smooth muscle cell calcification by up-regulating PI3K/Akt signaling and inhibiting apoptosis

Background

Vascular calcification is associated with increased cardiovascular morbidity and mortality in patients with atherosclerosis, diabetes and chronic kidney disease. However, no viable treatments for this condition have been identified. This study aimed to determine whether farnesyl transferase inhibitors (FTIs) can reduce vascular calcification and the mechanism by which this reduction occurs.

Results

We demonstrate that FTI-277 significantly inhibits phosphate-induced mineral deposition by vascular smooth muscle cells (VSMC) in vitro, prevents VSMC osteogenic differentiation, and increases mRNA expression of matrix Gla protein (MGP), an inhibitor of mineralization. FTI-277 increases Akt signaling in VSMC in short-term serum-stimulation assays and in long-term mineralization assays. In contrast, manumycin A has no effect on Akt signaling or mineralization. Co-incubation of VSMC with FTI-277 and SH6 (an Akt inhibitor) significantly reduces the inhibitory effect of FTI-277 on mineralization, demonstrating that FTI-277 inhibits calcification by activating Akt signaling. Over-expression of the constitutively active p110 sub-unit of PI3K in VSMC using adenovirus activates Akt, inhibits mineralization, suppresses VSMC differentiation and significantly enhances MGP mRNA expression. FTI-277 also inhibits phosphate-induced activation of caspase 3 and apoptosis of VSMC, and these effects are negated by co-incubation with SH6. Finally, using an ex vivo model of vascular calcification, we demonstrate that FTI-277 inhibits high phosphate-induced mineralization in aortic rings derived from rats with end-stage renal failure.

Conclusions

Together, these results demonstrate that FTI-277 inhibits VSMC mineral deposition by up-regulating PI3K/Akt signaling and preventing apoptosis, suggesting that targeting farnesylation, or Akt specifically, may have therapeutic potential for the prevention of vascular calcification.

Sphingosine 1-phosphate activation of ERM contributes to vascular calcification

Vascular calcification is the deposition of mineral in the artery wall by vascular smooth muscle cells (VSMCs) in response to pathological stimuli. The process is similar to bone formation and is an independent risk factor for cardiovascular disease. Given that ceramide and sphingosine 1-phosphate (S1P) are involved in cardiovascular pathophysiology and biomineralization, their role in VSMC matrix mineralization was investigated. During phosphate-induced VSMC mineralization, endogenous S1P levels increased accompanied by increased sphingosine kinase (SK) activity and increased mRNA expression of SK1 and SK2. Consistent with this, mineralization was increased by exogenous S1P, but decreased by C2-ceramide. Mechanistically, exogenous S1P stimulated ezrin-radixin-moesin (ERM) phosphorylation in VSMCs and ERM phosphorylation was increased concomitantly with endogenous S1P during mineralization. Moreover, inhibition of acid sphingomyelinase and ceramidase with desipramine prevented increased S1P levels, ERM activation, and mineralization. Finally, pharmacological inhibition of ERM phosphorylation with NSC663894 decreased mineralization induced by phosphate and exogenous S1P. Although further studies will be needed to verify these findings in vivo, this study defines a novel role for the SK-S1P-ERM pathways in phosphate-induced VSMC matrix mineralization and shows that blocking these pathways with pharmacological inhibitors reduces mineralization. These results may inform new therapeutic approaches to inhibit or delay vascular calcification.