Palmitic acid induces osteoblastic differentiation in vascular smooth muscle cells through ACSL3 and NF-κB, novel targets of eicosapentaenoic acid

The association between C-reactive protein and coronary artery calcification: a systematic review and meta-analysis

BACKGROUND

While coronary artery calcification (CAC) is recognized as a reliable marker for coronary atherosclerosis, the relationship between the concentration of C-reactive protein (CRP) and the incidence and progression of CAC remains controversial.

METHOD

PubMed, Embase, Web of Science, and Scopus were systematically searched to identify relevant observational studies until October 2023. The methodological quality of the included studies was evaluated using the Newcastle-Ottawa Scale (NOS). A random-effects meta-analysis was employed to calculate pooled odd ratios (OR) and corresponding 95% confidence intervals, considering heterogeneity among the studies.

RESULTS

Out of the 2545 records, 42 cross-sectional and 9 cohort studies were included in the systematic review. The meta-analysis on 12 eligible cross-sectional studies revealed no significant association between CAC and CRP [pooled OR: 1.03 (1.00, 1.06)]. Additionally, an insignificant association was found between CAC and CRP through meta-analysis on three eligible cohort studies [pooled OR: 1.05 (0.95, 1.15)] with no considerable heterogeneity across studies. Sensitivity analyses indicated that the meta-analysis models were robust. There was no evidence of publication bias.

CONCLUSION

Based on the meta-analysis findings, elevated levels of CRP did not emerge as a valuable prognostic maker for CAC incidence and progression prediction.

Activation of the IKK2/NF-κB pathway in VSMCs inhibits calcified vascular stiffness in CKD

IKK2/NF-κB pathway-mediated inflammation in vascular smooth muscle cells (VSMCs) has been proposed to be an etiologic factor in medial calcification and stiffness. However, the role of the IKK2/NF-κB pathway in medial calcification remains to be elucidated. In this study, we found that chronic kidney disease (CKD) induces inflammatory pathways through the local activation of the IKK2/NF-κB pathway in VMSCs associated with calcified vascular stiffness. Despite reducing the expression of inflammatory mediators, complete inhibition of the IKK2/NF-κB pathway in vitro and in vivo unexpectedly exacerbated vascular mineralization and stiffness. In contrast, activation of NF-κB by SMC-specific IκBα deficiency attenuated calcified vascular stiffness in CKD. Inhibition of the IKK2/NF-κB pathway induced cell death of VSMCs by reducing anti-cell death gene expression, whereas activation of NF-κB reduced CKD-dependent vascular cell death. In addition, increased calcification of extracellular vesicles through the inhibition of the IKK2/NF-κB pathway induced mineralization of VSMCs, which was significantly reduced by blocking cell death in vitro and in vivo. This study reveals that activation of the IKK2/NF-κB pathway in VSMCs plays a protective role in CKD-dependent calcified vascular stiffness by reducing the release of apoptotic calcifying extracellular vesicles.

Caspase-3/gasdermin-E axis facilitates the progression of coronary artery calcification by inducing the release of high mobility group box protein 1

Coronary artery calcification (CAC) is commonly observed in atherosclerotic plaques, which is a pathogenic factor for severe coronary artery disease (CAD). The phenotype changes of vascular smooth muscle cells (VSMCs) are found to participate in CAC progression, which is mainly induced by vascular inflammation and oxidative stress (OS). HMGB1, a critical inflammatory cytokine, is recently reported to induce arterial calcification, which is regulated by the Caspase-3/gasdermin-E (GSDME) axis. However, the function of the Caspase-3/GSDME axis in CAC is unknown. Herein, the involvement of the Caspase-3/GSDME axis in CAC was studied to explore the possible targets for CAC. CAC model was constructed in mice, which was verified by red cytoplasm in coronary artery tissues, increased macrophage infiltration, aggravated inflammation, and enhanced RAGE signaling, accompanied by an increased release of HMGB1 and an activated Caspase-3/ GSDME axis. In β-GP-treated MOVAS-1 cells, calcification, the ROS accumulation, enhanced LDH and HMGB1 release, enlarged macrophage production, aggravated inflammation, and activated RAGE signaling were observed, which were markedly abolished by the transfection of si-HMGB1 and si-GSDME. Moreover, the calcification deposition, the activity of Caspase-3/ GSDME axis, release of HMGB1, macrophage infiltration, cytokine production, and RAGE signaling in CAC mice were notably alleviated by VSMCs-specific GSDME knockdown, not by hematopoietic stem cells (HSCs)-specific GSDME knockdown. Collectively, Caspase-3/GSDME axis facilitated the progression of CAC by inducing the release of HMGB1.

Association between Eicosapentaenoic Acid to Arachidonic Acid Ratio and Characteristics of Plaque Rupture

AIMS

Eicosapentaenoic acid (EPA) has shown beneficial effects on coronary plaque stabilization. Based on our previous study, we speculated that EPA might be associated with the development of healed plaques and might limit thrombus size. This study aimed to elucidate the association between EPA and arachidonic acid (AA) ratios and various plaque characteristics in patients with plaque rupture.

METHODS

A total of 95 patients with acute coronary syndrome (ACS) caused by plaque rupture who did not take lipid-lowering drugs and underwent percutaneous coronary intervention using optical coherence tomography (OCT) were included. Clinical characteristics, lipid profiles, and OCT findings were compared between patients with lower and higher EPA/AA ratios (0.41) according to the levels in the Japanese general population.

RESULTS

In the high EPA/AA (n=29, 30.5%) and low EPA/AA (n=66, 69.5 %) groups, the high EPA/AA group was significantly older (76.1 vs. 66.1 years, P＜0.01) and had lower peak creatine kinase (556 vs. 1651 U/L, P=0.03) than those with low EPA/AA. Similarly, patients with high EPA/AA had higher prevalence of layered and calcified plaque (75.9 vs. 39.4 %, P＜0.01; 79.3 vs. 50.0 %, P＜0.01, respectively) than low EPA/AA group. Multivariate logistic regression analysis demonstrated that a high EPA/AA ratio was an independent factor in determining the development of layered and calcified plaques.

CONCLUSION

A high EPA/AA ratio may be associated with the development of layered and calcified plaques in patients with plaque rupture.

ACSL1 is a key regulator of inflammatory and macrophage foaming induced by short-term palmitate exposure or acute high-fat feeding

Foamy and inflammatory macrophages play pathogenic roles in metabolic disorders. However, the mechanisms that promote foamy and inflammatory macrophage phenotypes under acute-high-fat feeding (AHFF) remain elusive. Herein, we investigated the role of acyl-CoA synthetase-1 (ACSL1) in favoring the foamy/inflammatory phenotype of monocytes/macrophages upon short-term exposure to palmitate or AHFF. Palmitate exposure induced a foamy/inflammatory phenotype in macrophages which was associated with increased ACSL1 expression. Inhibition/knockdown of ACSL1 in macrophages suppressed the foamy/inflammatory phenotype through the inhibition of the CD36-FABP4-p38-PPARδ signaling axis. ACSL1 inhibition/knockdown suppressed macrophage foaming/inflammation after palmitate stimulation by downregulating the FABP4 expression. Similar results were obtained using primary human monocytes. As expected, oral administration of ACSL1 inhibitor triacsin-C in mice before AHFF normalized the inflammatory/foamy phenotype of the circulatory monocytes by suppressing FABP4 expression. Our results reveal that targeting ACSL1 leads to the attenuation of the CD36-FABP4-p38-PPARδ signaling axis, providing a therapeutic strategy to prevent the AHFF-induced macrophage foaming and inflammation.

Activation of the IKK2-NFκB pathway in VSMCs inhibits calcified vascular stiffness in CKD by reducing the secretion of calcifying extracellular vesicles

IKK2-NFκB pathway mediated-inflammation in vascular smooth muscle cells (VSMCs) has been proposed to be an etiologic factor in medial calcification and stiffness. However, the role of the IKK2-NFκB pathway in medial calcification remains to be elucidated. In this study, we found that CKD induces inflammatory pathways through the local activation of the IKK2-NFκB pathway in VMSCs associated with calcified vascular stiffness. Despite reducing the expression of inflammatory mediators, complete inhibition of the IKK2-NFκB pathway in vitro and in vivo unexpectedly exacerbated vascular mineralization and stiffness. In contrast, activation of NFκB by SMC-specific IκB deficiency attenuated calcified vascular stiffness in CKD. Inhibition of the IKK2-NFκB pathway induced apoptosis of VSMCs by reducing anti-apoptotic gene expression, whereas activation of NFκB reduced CKD-dependent vascular cell death. In addition, increased calcifying extracellular vesicles through the inhibition of the IKK2-NFκB pathway induced mineralization of VSMCs, which was significantly reduced by blocking cell death. This study reveals that activation of the IKK2-NFκB pathway in VSMCs plays a protective role in CKD-dependent calcified vascular stiffness by reducing the release of apoptotic calcifying extracellular vesicles.

Role of Stearoyl-CoA Desaturase 1 in Cardiovascular Physiology

Stearoyl-CoA desaturase is a rate-limiting enzyme in the synthesis of monounsaturated fatty acids. Monounsaturated fatty acids limit the toxicity of exogenous saturated fats. Studies have shown that stearoyl-CoA desaturase 1 is involved in the remodeling of cardiac metabolism. The loss of stearoyl-CoA desaturase 1 reduces fatty acid oxidation and increases glucose oxidation in the heart. Such a change is protective under conditions of a high-fat diet, which reduces reactive oxygen species-generating β-oxidation. In contrast, stearoyl-CoA desaturase 1 deficiency predisposes individuals to atherosclerosis under conditions of hyperlipidemia but protects against apnea-induced atherosclerosis. Stearoyl-CoA desaturase 1 deficiency also impairs angiogenesis after myocardial infarction. Clinical data show a positive correlation between blood stearoyl-CoA Δ-9 desaturation rates and cardiovascular disease and mortality. Moreover, stearoyl-CoA desaturase inhibition is considered an attractive intervention in some obesity-associated pathologies, and the importance of stearoyl-CoA desaturase in the cardiovascular system might be a limitation for developing such therapy. This review discusses the role of stearoyl-CoA desaturase 1 in the regulation of cardiovascular homeostasis and the development of heart disease and presents markers of systemic stearoyl-CoA desaturase activity and their predictive potential in the diagnosis of cardiovascular disorders.

Saturated fatty acid promotes calcification via suppressing SIRT6 expression in vascular smooth muscle cells

BACKGROUND

This study aims to investigate the effects of saturated free fatty acid on calcification and SIRT6 expression in vascular smooth muscle cells (VSMCs) and the role of SIRT6 in regulating VSMC calcification.

METHODS

Sprague-Dawley rats were randomly allocated to two groups: rats with normal diet (ND) and high-fat diet (HFD) from 4 to 12 weeks. At 12 weeks, part rats randomly selected from ND and HFD were administrated with vitamin D3 and nicotine to establish a model of vascular calcification. Thoracic aortas were collected from treatment rats at 16 weeks for assaying vascular calcification and related protein expression. Primary VSMCs isolated from Sprague-Dawley rats were used for investigating the effects of palmitic acid on VSMCs' calcification, apoptosis and target protein expression.

RESULTS

HFD-facilitated calcification in medial aorta, with decreased SIRT6 expression in VSMCs of aortas. Palmitic acid decreased SIRT6 expression while increased calcification, apoptosis and protein expression of BMP2 and RUNX2 in primary VSMCs. Overexpression of SIRT6 could, partially or completely, rescue the palmitic acid-induced elevation of calcification, apoptosis and expression of BMP2 and RUNX2.

CONCLUSION

This study demonstrated that vascular calcification induced by HFD was linked to the palmitic acid-induced downregulation of SIRT6. Overexpression of SIRT6 could decrease palmitic acid-induced calcification and apoptosis in VSMCs.

Oleoylethanolamide alleviates hyperlipidaemia-mediated vascular calcification via attenuating mitochondrial DNA stress triggered autophagy-dependent ferroptosis by activating PPARα

Vascular calcification, a prevalent pathological alteration in metabolic syndromes, is tightly related with cardiometabolic risk events. Ferroptosis, a newly iron-dependent programmed cell death, induced by palmitic acid (PA), the major saturated free fatty acid in hyperlipidemia, is a vital mechanism of vascular calcification. Recent studies reported that ferroptosis is a distinctive type of cell death dependent on autophagy, with the lipotoxicity of PA on cell viability being closely linked with autophagy. Oleoylethanolamide (OEA), an endogenous bioactive mediator of lipid homeostasis, exerts vascular protection against intimal calcification, atherosclerosis; however, its beneficial effect on vascular smooth muscle cell (VSMC)-associated medial calcification has not been investigated. Our aim was to characterize the effect of OEA on vascular calcification and ferroptosis of VSMCs under hyperlipidaemia/PA exposure. In vivo, vascular calcification model was induced in rats by high-fat diet and vitamin D3 plus nicotine; in vitro, VSMCs ferroptosis was induced by PA or plus β-glycerophosphate mimicking vascular calcification. The calcium deposition in hyperlipidaemia-mediated rat thoracic aortas, the PA-induced ferroptosis and subsequent calcium deposition in VSMCs, were suppressed by OEA treatment. Additionally, CGAS-STING1-induced ferritinophagy, the main molecular mechanism of PA-triggered ferroptosis of VSMCs, was activated by mitochondrial DNA damage; however, early administration of OEA alleviated these phenomena. Intriguingly, overexpression of peroxisome proliferator activated receptor alpha (PPARα) contributed to a decrease in PA-induced ferroptosis, whereas PPARɑ knockdown inhibited the OEA-mediated anti-ferroptotic effects. Collectively, our study demonstrated that OEA serves as a prospective candidate for the prevention and treatment of vascular calcification in metabolic abnormality syndromes.

Role of the gut microbiota and their metabolites in hemodialysis patients

High serum phosphate levels in chronic kidney disease (CKD) are linked to adverse health outcomes, including cardiovascular disease, kidney disease progression, and all-cause mortality. This study is aimed to find out which microorganisms or microbial functions have a significant impact on higher calcium-phosphorus product (Ca x P) after they undergo hemodialysis (HD) treatment. Feces samples from 30 healthy controls, 15 dialysis patients with controlled Ca xP (HD), and 16 dialysis patients with higher Ca xP (HDHCP) were collected to perform in 16S amplicon sequencing. We found gut microbial composition was significantly different between hemodialysis patients and healthy controls. Three phyla including Firmicutes, Actinobacteria, and Proteobacteria were significantly enriched in hemodialysis patients. Although only one genus, Lachnospiraceae_FCS020_group, was significantly increased in higher Ca xP group, there were four metabolic pathways predicted by PICRUSt significantly increased in higher Ca xP group and associated with causing VC, including the pentose phosphate pathway, steroid biosynthesis, terpenoid backbone biosynthesis, and fatty acid elongation pathway. Characterizing dysbiosis of gut microbiome played the important role in hemodialysis patients.

Effects of dehydroabietic acid on nontarget lipidomics and proteomics of HepG2

Objective: Studies of the effects of dehydroabietic acid on the multiomics of HepG2 hepatoma carcinoma cells are currently lacking. In this study, the molecular mechanism of the influence of dehydroabietic acid on HepG2 cells was disclosed by studying lipidomics and proteomics. Correlations among multiomics conjoint analysis results were verified. Methods: First, proteomics analysis of HepG2 cells was carried out using dehydroabietic acid. Differentially expressed proteins were screened and analyzed. Pathway enrichment analyses of differential proteins were compared, and the molecular mechanism was disclosed. Second, lipidomics analysis of HepG2 cells was conducted using dehydroabietic acid. The influence of dehydroabietic acid on HepG2 cells was determined on the lipid molecular level. Finally, a conjoint analysis of data related to differentially expressed proteins of ferroptosis and differentially changing lipid molecules was implemented. Results: A total of 260 upregulated and 961 downregulated proteins were screened in the proteomics analysis. The top five significantly enriched pathways included ferroptosis, oxidative phosphorylation, and protein processing in the endoplasmic reticulum. In the lipidomics analysis, 30 significantly differential metabolites with upregulated and downregulated expression were identified, and differentially expressed lipids were mainly related to the metabolism of glyceryl phosphatide. According to the comprehensive multiomics analysis results, real-time quantitative PCR and the enzyme-linked immunosorbent assay (ELISA), ACSL3 participated in cardiolipin metabolism. Conclusion: Dehydroabietic acid influences HepG2 cells through the above biological pathways.

New insight into dyslipidemia‐induced cellular senescence in atherosclerosis

Atherosclerosis, characterized by lipid‐rich plaques in the arterial wall, is an age‐related disorder and a leading cause of mortality worldwide. However, the specific mechanisms remain complex. Recently, emerging evidence has demonstrated that senescence of various types of cells, such as endothelial cells (ECs), vascular smooth muscle cells (VSMCs), macrophages, endothelial progenitor cells (EPCs), and adipose‐derived mesenchymal stem cells (AMSCs) contributes to atherosclerosis. Cellular senescence and atherosclerosis share various causative stimuli, in which dyslipidemia has attracted much attention. Dyslipidemia, mainly referred to elevated plasma levels of atherogenic lipids or lipoproteins, or functional impairment of anti‐atherogenic lipids or lipoproteins, plays a pivotal role both in cellular senescence and atherosclerosis. In this review, we summarize the current evidence for dyslipidemia‐induced cellular senescence during atherosclerosis, with a focus on low‐density lipoprotein (LDL) and its modifications, hydrolysate of triglyceride‐rich lipoproteins (TRLs), and high‐density lipoprotein (HDL), respectively. Furthermore, we describe the underlying mechanisms linking dyslipidemia‐induced cellular senescence and atherosclerosis. Finally, we discuss the senescence‐related therapeutic strategies for atherosclerosis, with special attention given to the anti‐atherosclerotic effects of promising geroprotectors as well as anti‐senescence effects of current lipid‐lowering drugs.

Inflammation: a putative link between phosphate metabolism and cardiovascular disease

Dietary habits in the western world lead to increasing phosphate intake. Under physiological conditions, extraosseous precipitation of phosphate with calcium is prevented by a mineral buffering system composed of calcification inhibitors and tight control of serum phosphate levels. The coordinated hormonal regulation of serum phosphate involves fibroblast growth factor 23 (FGF23), αKlotho, parathyroid hormone (PTH) and calcitriol. A severe derangement of phosphate homeostasis is observed in patients with chronic kidney disease (CKD), a patient collective with extremely high risk of cardiovascular morbidity and mortality. Higher phosphate levels in serum have been associated with increased risk for cardiovascular disease (CVD) in CKD patients, but also in the general population. The causal connections between phosphate and CVD are currently incompletely understood. An assumed link between phosphate and cardiovascular risk is the development of medial vascular calcification, a process actively promoted and regulated by a complex mechanistic interplay involving activation of pro-inflammatory signalling. Emerging evidence indicates a link between disturbances in phosphate homeostasis and inflammation. The present review focuses on critical interactions of phosphate homeostasis, inflammation, vascular calcification and CVD. Especially, pro-inflammatory responses mediating hyperphosphatemia-related development of vascular calcification as well as FGF23 as a critical factor in the interplay between inflammation and cardiovascular alterations, beyond its phosphaturic effects, are addressed.

Serum free fatty acids are associated with severe coronary artery calcification, especially in diabetes: a retrospective study

Background

Serum free fatty acid (FFA) concentrations are associated with coronary heart disease and diabetes mellitus (DM). Few studies focused on the relationship between serum FFA levels and coronary artery calcification (CAC).

Methods

This was a retrospective, single-centered study recruiting patients underwent FFA quantification, coronary angiography and intravascular ultrasound (IVUS). CAC severity was assessed with the maximum calcific angle (arc) of the calcified plaque scanned by IVUS. Patients with an arc ≥ 180° were classified into the severe CAC (SCAC) group, and those with an arc < 180° were classified into the non-SCAC group. Clinical characteristics, serum indices were compared between 2 groups. Logistic regression, receiver operating characteristic (ROC) curves and area under the curves (AUC) were performed.

Results

Totally, 426 patients with coronary artery disease were consecutively included. Serum FFA levels were significantly higher in the SCAC group than non-SCAC group (6.62 ± 2.17 vs. 5.13 ± 1.73 mmol/dl, p < 0.001). Logistic regression revealed that serum FFAs were independently associated with SCAC after adjusting for confounding factors in the whole cohort (OR 1.414, CI 1.237–1.617, p < 0.001), the non-DM group (OR 1.273, CI 1.087–1.492, p = 0.003) and the DM group (OR 1.939, CI 1.388–2.710, p < 0.001). ROC analysis revealed a serum FFA AUC of 0.695 (CI 0.641–0.750, p < 0.001) in the whole population. The diagnostic predictability was augmented (AUC = 0.775, CI 0.690–0.859, p < 0.001) in the DM group and decreased (AUC = 0.649, CI 0.580–0.718, p < 0.001) in the non-DM group.

Conclusions

Serum FFA levels were independently associated with SCAC, and could have some predictive capacity for SCAC. The association was strongest in the DM group.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12872-021-02152-w.

Natural compounds from Leea macrophylla enhance phagocytosis and promote osteoblasts differentiation by alkaline phosphatase, type 1 collagen, and osteocalcin gene expression

The current study investigated the immunomodulating and osteoblast differentiation potential of the natural compounds from Leea macrophylla (LMN). Immunomodulatory effects have been investigated by the phagocytosis of Candida albicans using polymorphonuclear neutrophil cells in the in vitro slide method. A bioactivity-guided fractionation technique was used to evaluate the stimulating effect of L. macrophylla methanol extract on osteoblast differentiation using mouse osteoblastic cells. A low dose of LMN was found to stimulate the phagocytic effect better than a higher dose. The natural compounds from L. macrophylla have significantly increased alkaline phosphatase (ALP) and osteocalcin activities. The LMN promoted the osteoblast differentiation through upregulation of ALP, osteocalcin, and type 1 collagen in a dose-dependent manner. These natural compounds also upregulated ALP, osteocalcin, and type 1 collagen gene expressions. The data suggest that LMN has potential anabolic sequel on bone formation and osteoblast differentiation.

Regular Dietary Intake of Palmitate Causes Vascular and Valvular Calcification in a Rabbit Model

Aims: Palmitic acid (PA) and oleic acid (OA) are two main dietary fatty acids. Dietary intake of PA has been associated with cardiovascular disease risk, and the effect of OA remains uncertain. Our study aimed to assess the effect of a short-term intake of lard, as source of PA and OA, on aorta and aortic valve.

Methods and Results: Rabbits were fed with two lard-enriched diets, containing either elevated levels of PA or of both PA and OA as compared to chow diet. After 16 weeks of each diet, calcification was observed in the aortic intima and in the aortic valve. The extent of calcification did not differ between the two diets. In contrast, rabbits fed chow diet did not develop any calcification. In blood, PA enrichment resulted in decreased lymphocyte and monocyte counts and increased levels of hemoglobin and haematocrit. Levels of the calcification inhibitor fetuin-A were also diminished, whereas creatinine levels were raised. Of note, none of the diets changed cholesterol levels in LDL or HDL. Comprehensive quantitative lipidomics analysis identified diet-related changes in plasma lipids. Dietary PA enrichment led to a drop of polyunsaturated fatty acids (PUFA), in particular of linoleic acid in cholesteryl esters, triglycerides and diacylglycerols (DAG). Ratios of PA to 18-carbon PUFA in DAG were positively correlated with the extent of aortic valve calcification, and inversely with monocyte counts. PA content in blood correlated with aorta calcification.

Conclusions: Regular dietary PA intake induces vascular and valvular calcification independently of traditional risk factors. Our findings raise awareness about PA-rich food consumption and its potential deleterious effect on cardiovascular health.

Omics Profiling of S2P Mutant Fibroblasts as a Mean to Unravel the Pathomechanism and Molecular Signatures of X-Linked MBTPS2 Osteogenesis Imperfecta

Osteogenesis imperfecta (OI) is an inherited skeletal dysplasia characterized by low bone density, bone fragility and recurrent fractures. The characterization of its heterogeneous genetic basis has allowed the identification of novel players in bone development. In 2016, we described the first X-linked recessive form of OI caused by hemizygous MBTPS2 missense variants resulting in moderate to severe phenotypes. MBTPS2 encodes site-2 protease (S2P), which activates transcription factors involved in bone (OASIS) and cartilage development (BBF2H7), ER stress response (ATF6) and lipid metabolism (SREBP) via regulated intramembrane proteolysis. In times of ER stress or sterol deficiency, the aforementioned transcription factors are sequentially cleaved by site-1 protease (S1P) and S2P. Their N-terminal fragments shuttle to the nucleus to activate gene transcription. Intriguingly, missense mutations at other positions of MBTPS2 cause the dermatological spectrum condition Ichthyosis Follicularis, Atrichia and Photophobia (IFAP) and Keratosis Follicularis Spinulosa Decalvans (KFSD) without clinical overlap with OI despite the proximity of some of the pathogenic variants. To understand how single amino acid substitutions in S2P can lead to non-overlapping phenotypes, we aimed to compare the molecular features of MBTPS2-OI and MBTPS2-IFAP/KFSD, with the ultimate goal to unravel the pathomechanisms underlying MBTPS2-OI. RNA-sequencing-based transcriptome profiling of primary skin fibroblasts from healthy controls (n = 4), MBTPS2-OI (n = 3), and MBTPS2-IFAP/KFSD (n = 2) patients was performed to identify genes that are differentially expressed in MBTPS2-OI and MBTPS2-IFAP/KFSD individuals compared to controls. We observed that SREBP-dependent genes are more downregulated in OI than in IFAP/KFSD. This is coupled to alterations in the relative abundance of fatty acids in MBTPS2-OI fibroblasts in vitro, while no consistent alterations in the sterol profile were observed. Few OASIS-dependent genes are suppressed in MBTPS2-OI, while BBF2H7- and ATF6-dependent genes are comparable between OI and IFAP/KFSD patients and control fibroblasts. Importantly, we identified genes involved in cartilage physiology that are differentially expressed in MBTPS2-OI but not in MBTPS2-IFAP/KFSD fibroblasts. In conclusion, our data provide clues to how pathogenic MBTPS2 mutations cause skeletal deformities via altered fatty acid metabolism or cartilage development that may affect bone development, mineralization and endochondral ossification.

Metformin attenuates hyperlipidaemia-associated vascular calcification through anti-ferroptotic effects

Ferroptosis is a form of regulated cell death that involves metabolic dysfunction resulting from iron-dependent excessive lipid peroxidation. Elevated plasma levels of free fatty acids are tightly associated with cardiometabolic risk factors in patients with obesity, diabetes mellitus, and metabolic syndrome. Metformin (Met) is an antidiabetic drug with beneficial cardiovascular disease effects. The aim of this study was to determine the effects of Met on ferroptosis induced by lipid overload and the effects of these changes on vascular smooth muscle cells (VSMCs) calcification. We developed a hyperlipidaemia-related vascular calcification in vivo model with rats fed a high-fat diet combined with vitamin D3 plus nicotine, and palmitic acid (PA), the most abundant long-chain saturated fatty acid in plasma, was used to induce lipid overload and develop an oxidative stress-related calcification model in vitro. The results showed that Met inhibits hyperlipidaemia-associated calcium deposition in the rat aortic tissue. In vitro, treatment of VSMCs with PA stimulates ferroptosis concomitant with increased calcium deposition in VSMCs, while pretreatment with Met attenuates these effects. Furthermore, PA also promotes the protein expression of the extracellular matrix protein periostin (POSTN) and its secretion into the extracellular environment. More importantly, upregulation of POSTN increased the sensitivity of cells to ferroptosis. Mechanistically, upregulation of POSTN suppresses SLC7A11 expression through the inhibition of p53 in VSMCs, which contributes to a decrease in glutathione synthesis and therefore triggers ferroptosis. Interestingly, overexpression of p53 attenuates the inhibitory effect of POSTN on SLC7A11 expression, accompanied by increased Gpx4 expression. Furthermore, p53 knockdown suppresses Met-mediated anti-ferroptosis effects in PA-treated VSMCs, which may be related to the downregulation of SLC7A11 expression. In addition, supplementation of VSMCs with Met enhances the antioxidative capacity of VSMCs through Nrf2 signalling activation. Collectively, targeting POSTN in VSMCs may provide a new strategy for vascular calcification prevention or treatment.

Circular RNAs in stem cell differentiation: a sponge-like role for miRNAs

Circular RNAs (circRNAs) are novel endogenous non-coding RNAs that play a critical role during cellular signal transduction, gene transcription and translation. With the rapid advancement of bioinformatics analysis tools and high-throughput RNA sequencing, numerous circRNAs with important biological features have been identified. They function as competing endogenous RNAs (ceRNAs) of microRNAs and as such exhibit the potential to act as biomarkers for stem cell differentiation. In the recent past, several studies have shown the involvement of circRNAs in stem cells differentiation. The present review summarizes the molecular characteristics, biogenesis and mechanisms of newly identified circRNAs in the differentiation of stem cells. In conclusion, circRNAs regulate the stem cells differentiation via their ambient binding efficacy to modulate miRNA expression, as well as related gene translation. We believe that this review will provide reference guidance for future studies on stem cell differentiation.

Distinguish fatty acids impact survival, differentiation and cellular function of periodontal ligament fibroblasts

Alveolar bone (AB) remodeling is necessary for the adaption to mechanical stimuli occurring during mastication and orthodontic tooth movement (OTM). Thereby, bone degradation and assembly are strongly regulated processes that can be altered in obese patients. Further, increased fatty acids (FA) serum levels affect bone remodeling cells and we, therefore, investigated whether they also influence the function of periodontal ligament fibroblast (PdLF). PdLF are a major cell type regulating the differentiation and function of osteoblasts and osteoclasts localized in the AB. We stimulated human PdLF (HPdLF) in vitro with palmitic (PA) or oleic acid (OA) and analyzed their metabolic activity, growth, survival and expression of osteogenic markers and calcium deposits. Our results emphasize that PA increased cell death of HPdLF, whereas OA induced their osteoblastic differentiation. Moreover, quantitative expression analysis of OPG and RANKL revealed altered levels in mechanically stimulated PA-treated HPdLF. Furthermore, osteoclasts stimulated with culture medium of mechanical stressed FA-treated HPdLF revealed significant changes in cell differentiation upon FA-treatment. For the first time, our results highlight a potential role of specific FA in the function of HPdLF-modulated AB remodeling and help to elucidate the complex interplay of bone metabolism, mechanical stimulation and obesity-induced alterations.

Circulating Receptor Activator of Nuclear Factor kB Ligand and triglycerides are associated with progression of lower limb arterial calcification in type 2 diabetes: a prospective, observational cohort study

Background

Lower limb arterial calcification is a frequent, underestimated but serious complication of diabetes. The DIACART study is a prospective cohort study designed to evaluate the determinants of the progression of lower limb arterial calcification in 198 patients with type 2 diabetes.

Methods

Lower limb arterial calcification scores were determined by computed tomography at baseline and after a mean follow up of 31.20 ± 3.86 months. Serum RANKL (Receptor Activator of Nuclear factor kB Ligand) and bone remodeling, inflammatory and metabolic parameters were measured at baseline. The predictive effect of these markers on calcification progression was analyzed by a multivariate linear regression model.

Results

At baseline, mean ± SD and median lower limb arterial calcification scores were, 2364 ± 5613 and 527 respectively and at the end of the study, 3739 ± 6886 and 1355 respectively. Using multivariate analysis, the progression of lower limb arterial log calcification score was found to be associated with (β coefficient [slope], 95% CI, p-value) baseline log(calcification score) (1.02, 1.00–1.04, p < 0.001), triglycerides (0.11, 0.03–0.20, p = 0.007), log(RANKL) (0.07, 0.02–0.11, p = 0.016), previous ischemic cardiomyopathy (0.36, 0.15–0.57, p = 0.001), statin use (0.39, 0.06–0.72, p = 0.023) and duration of follow up (0.04, 0.01–0.06, p = 0.004).

Conclusion

In patients with type 2 diabetes, lower limb arterial calcification is frequent and can progress rapidly. Circulating RANKL and triglycerides are independently associated with this progression. These results open new therapeutic perspectives in peripheral diabetic calcifying arteriopathy.

Trial registration NCT02431234

Evolution, expression profile, and regulatory characteristics of ACSL gene family in chicken (Gallus gallus)

Long chain acyl-CoA synthetases (ACSLs), which drive the conversion of long chain fatty acid into acyl-CoA, an ingredient of lipid synthesis, have been well-acknowledged to exert an indispensable role in many metabolic processes in mammals, especially lipid metabolism. However, in chicken, the evolutionary characteristics, expression profiles and regulatory mechanisms of ACSL gene family are rarely understood. Here, we analyzed the genomic synteny, gene structure, evolutionary event and functional domains of the ACSL gene family members using bioinformatics methods. The spatiotemporal expression profiles of ACSL gene family, and their regulatory mechanism were investigated via bioinformatics analysis incorporated with in vivo and in vitro estrogen-treated experiments. Our results indicated that ACSL2 gene was indeed evolutionarily lost in the genome of chicken. Chicken ACSLs shared an AMP-binding functional domain, as well as highly conversed ATP/AMP and FACS signature motifs, and were clustered into two clades, ACSL1/5/6 and ACSL3/4, based on high sequence similarity, similar gene features and conversed motifs. Chicken ACSLs showed differential tissue expression distributions, wherein the significantly decreased expression level of ACSL1 and the significantly increased expression level of ACSL5 were found, respectively, the expression levels of the other ACSL members remained unchanged in the liver of peak-laying hens versus pre-laying hens. Moreover, the transcription activity of ACSL1, ACSL3 and ACSL4 was silenced and ACSL6 was activated by estrogen, but no response to ACSL5. In conclusion, though having highly conversed functional domains, chicken ACSL gene family is organized into two separate groups, ACSL1/5/6 and ACSL3/4, and exhibits varying expression profiles and estrogen effects. These results not only pave the way for better understanding the specific functions of ACSL genes in avian lipid metabolism, but also provide a valuable evidence for gene family characteristics.

Effects of Eicosapentaenoic Acid on Arterial Calcification

Arterial calcification is a hallmark of advanced atherosclerosis and predicts cardiovascular events. However, there is no clinically accepted therapy that prevents progression of arterial calcification. HMG-CoA reductase inhibitors, statins, lower low-density lipoprotein-cholesterol and reduce cardiovascular events, but coronary artery calcification is actually promoted by statins. The addition of eicosapentaenoic acid (EPA) to statins further reduced cardiovascular events in clinical trials, JELIS and REDUCE-IT. Additionally, we found that EPA significantly suppressed arterial calcification in vitro and in vivo via suppression of inflammatory responses, oxidative stress and Wnt signaling. However, so far there is a lack of evidence showing the effect of EPA on arterial calcification in a clinical situation. We reviewed the molecular mechanisms of the inhibitory effect of EPA on arterial calcification and the results of some clinical trials.

Omega-3 fatty acids in pathological calcification and bone health

Omega-3 fatty acids (ω-3FAs) such as Docosahexaenoic acid (DHA) and Eicosapentanoic acid (EPA), are active ingredient of fish oil, which have larger health benefits against various diseases including cardiovascular, neurodegenerative, cancers and bone diseases. Substantial studies documented a preventive role of omega-3 fatty acids in pathological calcification like vascular calcification and microcalcification in cancer tissues. In parallel, these fatty acids improve bone quality probably by preventing bone decay and augmenting bone mineralization. This study also addresses that the functions of ω-3FAs not only depend on tissue types, but also work through different molecular mechanisms for preventing pathological calcification in various tissues and improving bone health. PRACTICAL APPLICATIONS: Practical applications of the current study are to improve the knowledge about the supplementation of omega-3 fatty acids. This study infers that supplementation of omega-3 fatty acids aids in bone preservation in elder females at the risk of osteoporosis and also, on the contrary, omega-3 fatty acids interfere with pathological calcification of vascular cells and cancer cells. Omega-3 supplementation should be given to the cardiac patients because of its cardio protective role. In line with this, omega-3 supplementation should be included with chemotherapy for cancer patients as it can prevent osteoblastic potential of breast cancer patients, responsible for pathological mineralization, and blocks off target toxicities. Administration of omega-3 fatty acid with chemotherapy will not only improve survival of cancer patients, but also improve the bone quality. Thus, this study allows a better understanding on omega-3 fatty acids in combating pathological complications such as osteoporosis, vascular calcification, and breast microcalcification.

Serial Biomarkers of De Novo Lipogenesis Fatty Acids and Incident Heart Failure in Older Adults: The Cardiovascular Health Study

Background De novo lipogenesis (DNL) is an endogenous pathway that converts excess dietary starch, sugar, protein, and alcohol into specific fatty acids (FAs). Although elevated DNL is linked to several metabolic abnormalities, little is known about how long-term habitual levels and changes in levels of FAs in the DNL pathway relate to incident heart failure (HF). Methods and Results We investigated whether habitual levels and changes in serial measures of FAs in the DNL pathway were associated with incident HF among 4249 participants free of HF at baseline. Plasma phospholipid FAs were measured at baseline, 6 years, and 13 years using gas chromatography, and risk factors for HF were measured using standardized methods. Incident HF was centrally adjudicated using medical records. We prospectively evaluated associations with HF risk of (1) habitual FA levels, using cumulative updating to assess long-term exposure, and (2) changes in FA levels over time. During 22.1 years of follow-up, 1304 HF cases occurred. After multivariable adjustment, habitual levels and changes in levels of palmitic acid (16:0) were positively associated with incident HF (interquintile hazard ratio [95% CI]=1.17 [1.00-1.36] and 1.26 [1.03-1.55], respectively). Changes in levels of 7-hexadecenoic acid (16:1n-9) and vaccenic acid (18:1n-7) were each positively associated with risk of HF (1.36 [1.13-1.62], and 1.43 [1.18-1.72], respectively). Habitual levels and changes in levels of myristic acid (14:0), palmitoleic acid (16:1n-7), stearic acid (18:0), and oleic acid (18:1n-9) were not associated with incident HF. Conclusions Both habitual levels and changes in levels of 16:0 were positively associated with incident HF in older adults. Changes in 16:1n-9 and 18:1n-7 were also positively associated with incident HF. These findings support a potential role of DNL or these DNL-related FAs in the development of HF.

Palmitate induces apoptosis and inhibits osteogenic differentiation of human periodontal ligament stem cells

OBJECTIVE

The aim of the present study was to investigate the effect of palmitate on human periodontal ligament stem cells (PDLSCs).

DESIGN

PDLSCs were isolated from the third molars of healthy adult donors, and cultured in normal or osteogenic medium supplemented with palmitate (0, 100, or 250 μM) for 21 days. Cell proliferation was evaluated by measuring the amount of formazan at 6, 24, 48, and 72 h. Apoptosis was detected by ELISA and terminal deoxynucleotidyl transferase dUTP nick end labeling assay at days 3 and 7. Osteogenic differentiation was evaluated by measuring the alkaline phosphatase (ALP) activity, production of procollagen type I C-peptide and osteocalcin, mineralization, and mRNA expression of Runx2 at days 3, 7, 14, and 21. In addition, mRNA expression of IL-6 and IL-8 was measured at day 3.

RESULTS

Palmitate inhibited the proliferation, ALP activity, production of procollagen type I C-peptide and osteocalcin, mineralization, and mRNA expression of Runx2 in the cultured PDLSCs. Palmitate also induced apoptosis and mRNA expression of IL-6 and IL-8 in the PDLSCs.

CONCLUSIONS

The results of the present study demonstrate that palmitate induces apoptosis and inhibits osteogenic differentiation of PDLSCs. These findings may help clarify the relationship between palmitate and periodontal tissue regeneration.

Long-Chain Acyl-CoA Synthetase 1 Role in Sepsis and Immunity: Perspectives From a Parallel Review of Public Transcriptome Datasets and of the Literature

A potential role for the long-chain acyl-CoA synthetase family member 1 (ACSL1) in the immunobiology of sepsis was explored during a hands-on training workshop. Participants first assessed the robustness of the potential gap in biomedical knowledge identified via an initial screen of public transcriptome data and of the literature associated with ACSL1. Increase in ACSL1 transcript abundance during sepsis was confirmed in several independent datasets. Querying the ACSL1 literature also confirmed the absence of reports associating ACSL1 with sepsis. Inferences drawn from both the literature (via indirect associations) and public transcriptome data (via correlation) point to the likely participation of ACSL1 and ACSL4, another family member, in inflammasome activation in neutrophils during sepsis. Furthermore, available clinical data indicate that levels of ACSL1 and ACSL4 induction was significantly higher in fatal cases of sepsis. This denotes potential translational relevance and is consistent with involvement in pathways driving potentially deleterious systemic inflammation. Finally, while ACSL1 expression was induced in blood in vitro by a wide range of pathogen-derived factors as well as TNF, induction of ACSL4 appeared restricted to flagellated bacteria and pathogen-derived TLR5 agonists and IFNG. Taken together, this joint review of public literature and omics data records points to two members of the acyl-CoA synthetase family potentially playing a role in inflammasome activation in neutrophils. Translational relevance of these observations in the context of sepsis and other inflammatory conditions remain to be investigated.

Obesity Mediates Apoptosis and Extracellular Matrix Metabolic Imbalances via MAPK Pathway Activation in Intervertebral Disk Degeneration

Obesity may promote intervertebral disc degeneration (IDD) by non-mechanical means, by influencing levels of free fatty acids which could impair cell metabolism. This study aims to establish metabolic factors in obesity-related IDD independent of mechanical loading. In clinical study, we retrospectively reviewed 128 volunteers (73 males, 55 females, aged 29-88 years) and compared their grades of disk degeneration with obesity-related factors such as body weight, BMI, and serum lipid levels. Clinically, the IDD group showed increased age, BMI and serum triglyceride. Triglyceride was a significant risk factor for IDD even after correction for BMI and age (P = 0.007). In obesity animal model, rats were fed a high-fat diet (HFD) in order to study its effects on disk metabolism and apoptosis. HFD rats had significantly higher serum levels of lipids, including triglyceride and non-esterified fatty acid, and showed significantly decreased markers of anabolism, increased catabolism and apoptosis in disk. Finally, rat nucleus pulposus (NP) cells were stimulated in vitro with a fatty acid (palmitic acid, PA) to gauge its effects on cell metabolism and apoptosis. Cell culture studies showed that NP cells exposed to PA showed increased apoptosis for activation of caspase 3, 7, 9, and PARP, which was primarily via the MAPK signal pathway, especially ERK pathway. In conclusion, hypertriglyceridemia can lead to IDD, independently of age and BMI. Hypertriglyceridemia appears to mediate disk cell apoptosis and matrix catabolism primarily via the ERK pathway.

Recent Advances on Relationship Between Inorganic Phosphate and Pathologic Calcification: Is Calcification After Breast Augmentation with Fat Grafting Correlated with Locally Increased Concentration of Inorganic Phosphate?

BACKGROUND

Pathologic calcification has frequently occurred after breast augmentation with fat grafting as well as other conditions such as breast cancer, trauma, myocardial infarction, arteriosclerosis and even after reduction mammoplasty. Inorganic phosphate, correlated with fat metabolism, is an important factor that induces pathologic calcification such as vascular calcification.

METHODS

A literature search was conducted using PubMed with the keywords: calcification, inorganic phosphate, fat. Studies related to the process of pathologic calcification, correlation between inorganic phosphate and pathologic calcification, between inorganic phosphate and fat metabolism in pathologic calcification were collected.

RESULTS

Various mechanisms were referred to in pathologic calcification among which inorganic phosphate played an important role. Inorganic phosphate could be liberated, under the effect of various enzymes, in the process of fat metabolism. The authors hypothesized that a large-scale necrotizing zone, which could occur in fat grafting with large amounts per cannula, might provide a high-phosphate environment which might contribute to differentiation of surrounding cells such as stem cells or regenerated vessel cells into osteoblast-like cells that induce pathologic calcification.

CONCLUSION

Inorganic phosphate, which was correlated with fat metabolism, played a significant role in pathologic calcification. We firstly hypothesize that calcification after fat grafting may be related to locally increasing concentrations of phosphate in a necrotizing zone. Further research should be conducted to verify this hypothesis.

LEVEL OF EVIDENCE V

This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Upregulation of free fatty acid receptors in periodontal tissues of patients with metabolic syndrome and periodontitis

BACKGROUND AND OBJECTIVE

Metabolic syndrome (MetS) exacerbates periodontitis. Since saturated fatty acid (SFA) is increased in MetS and enhances lipopolysaccharide (LPS)-induced proinflammatory cytokine expression in macrophages, it has been considered to play a role in MetS-exacerbated periodontitis. However, it remains unknown how fatty acid receptors, which mediate the interaction of cells with SFA and uptake of SFA, are expressed and regulated in the periodontal tissue. In this study, we tested our hypothesis that the periodontal expression of fatty acid receptors GPR40 and CD36 is increased in patients with both MetS and periodontitis. We also determined the effect of SFA and LPS on GPR40 and CD36 expression in vitro.

MATERIAL AND METHODS

Periodontal tissue specimens were collected from 11 participants without MetS and periodontitis, 12 participants with MetS, 11 participants with periodontitis, and 14 participants with both MetS and periodontitis after surgeries. The tissues were processed, and GPR40 and CD36 were detected by immunohistochemistry. Furthermore, cultured macrophages and gingival fibroblasts were treated with LPS, palmitate, a major SFA, or LPS plus palmitate and the expression of GPR40 and CD36 was then quantified.

RESULTS

Analysis of clinical data showed that age, smoker, gender, and race/ethnicity were not significantly different among 4 groups. Immunohistochemistry showed that GPR40 and CD36 were expressed by epithelial cells, fibroblasts, and immune cells. Quantitative data showed that GPR40 expression is increased in patients with periodontitis, MetS, or both periodontitis and MetS while CD36 expression is increased only in patients with both periodontitis and MetS. The in vitro studies showed that the expression of GPR40 and CD36 in macrophages and fibroblasts was upregulated by the combination of LPS and palmitate.

CONCLUSION

Periodontal expression of GPR40 and CD36 was upregulated in patients with both MetS and periodontitis, and GPR40 and CD36 in macrophages and fibroblasts were upregulated in vitro by the combination of LPS and palmitate, suggesting that GPR40 and CD36 may be involved in MetS-exacerbated periodontitis.

Roles of Long-chain Acyl Coenzyme A Synthetase in Absorption and Transport of Fatty Acid

Long-chain acyl coenzyme A synthetase (ACSL) is a member of the synthetase family encoded by a multigene family; it plays an important role in the absorption and transport of fatty acid. Here we review the roles of ACSL in the regulating absorption and transport of fatty acid, as well as the connection between ACSL and some metabolic diseases.

LPS and palmitate synergistically stimulate sphingosine kinase 1 and increase sphingosine 1 phosphate in RAW264.7 macrophages

It has been well established that patients with diabetes or metabolic syndrome (MetS) have increased prevalence and severity of periodontitis, an oral infection initiated by bacteria and characterized by tissue inflammation and destruction. To understand the underlying mechanisms, we have shown that saturated fatty acid (SFA), which is increased in patients with type 2 diabetes or MetS, and LPS, an important pathogenic factor for periodontitis, synergistically stimulate expression of proinflammatory cytokines in macrophages by increasing ceramide production. However, the mechanisms by which increased ceramide enhances proinflammatory cytokine expression have not been well understood. Since sphingosine 1 phosphate (S1P) is a metabolite of ceramide and a bioactive lipid, we tested our hypothesis that stimulation of ceramide production by LPS and SFA facilitates S1P production, which contributes to proinflammatory cytokine expression. Results showed that LPS and palmitate, a major SFA, synergistically increased not only ceramide, but also S1P, and stimulated sphingosine kinase (SK) expression and membrane translocation in RAW264.7 macrophages. Results also showed that SK inhibition attenuated the stimulatory effect of LPS and palmitate on IL-6 secretion. Moreover, results showed that S1P enhanced the stimulatory effect of LPS and palmitate on IL-6 secretion. Finally, results showed that targeting S1P receptors using either S1P receptor antagonists or small interfering RNA attenuated IL-6 upregulation by LPS and palmitate. Taken together, this study demonstrated that LPS and palmitate synergistically stimulated S1P production and S1P in turn contributed to the upregulation of proinflammatory cytokine expression in macrophages by LPS and palmitate.

Selenoprotein S inhibits inflammation-induced vascular smooth muscle cell calcification

Vascular calcification is a prominent feature of many diseases including atherosclerotic cardiovascular disease (CVD), leading to high morbidity and mortality rates. A significant association of selenoprotein S (SelS) gene polymorphism with atherosclerotic CVD has been reported in epidemiologic studies, but the underlying mechanism is far from clear. To investigate the role of SelS in inflammation-induced vascular calcification, osteoblastic differentiation and calcification of vascular smooth muscle cells (VSMCs) induced by lipopolysaccharide (LPS) or tumor necrosis factor (TNF)-α were compared between the cells with and without SelS knockdown. LPS or TNF-α induced osteoblastic differentiation and calcification of VSMCs, as showed by the increases of runt-related transcription factor 2 (Runx2) protein levels, Runx2 and type I collagen mRNA levels, alkaline phosphatase activity, and calcium deposition content. These changes were aggravated when SelS was knocked down by small interfering RNA. Moreover, LPS activated both classical and alternative pathways of nuclear factor-κB (NF-κB) signaling in calcifying VSMCs, which were further enhanced under SelS knockdown condition. SelS knockdown also exacerbated LPS-induced increases of proinflammatory cytokines TNF-α and interleukin-6 expression, as well as increases of endoplasmic reticulum (ER) stress markers glucose-regulated protein 78 and inositol-requiring enzyme 1α expression in calcifying VSMCs. In conclusion, the present study suggested that SelS might inhibit inflammation-induced VSMC calcification probably by suppressing activation of NF-κB signaling pathways and ER stress. Our findings provide new understanding of the role of SelS in vascular calcification, which will be potentially beneficial to the prevention of atherosclerotic CVD.

Saturated fatty acids bound to albumin enhance osteopontin expression and cleavage in renal proximal tubular cells

Osteopontin (OPN) is one of the proinflammatory cytokines upregulated in the kidneys of diabetic animals and patients with nephropathy. An increase in urinary albumin and albumin-bound fatty acids (FA) presents a proinflammatory environment to the proximal tubules in proteinuric kidney diseases including diabetic nephropathy. This study was designed to examine if FA overload could stimulate OPN expression and cleavage in renal tubule epithelial cells. OPN gene and protein expression was examined in the kidney of Zucker diabetic (ZD) rats and cultured proximal tubular cells exposed to either bovine serum albumin (BSA) or BSA conjugated with palmitic acid (PA), the most abundant saturated plasma FA. Real-time PCR analysis confirmed an upregulation of renal cortical OPN gene correlated with albuminuria and nephropathy progression in ZD rats at the age of 7-20 weeks. Immunofluorescence staining of kidney sections revealed a massive induction of OPN protein in albumin-overloaded proximal tubules of ZD rats. A significant increase in both intact and cleaved OPN proteins was further demonstrated in the diabetic kidney and urine samples, which was attenuated by antiproteinuric treatment with losartan, an angiotensin II receptor blocker. When exposed to fatty acid-free BSA, NRK-52E cells exhibited an increase in protein levels of full-length and cleaved OPN. Moreover, the increase in OPN fragments was greatly enhanced in the presence of PA (250-500 µM). Together, our results support a stimulatory effect of albumin and conjugated FA on OPN expression and cleavage in renal tubule epithelial cells. Thus, besides lowering albuminuria/proteinuria, mitigating circulating FAs may be an effective intervention for preventing and slowing down the progression of nephropathy associated with obesity and type 2 diabetes.

Downregulated Serum 14, 15-Epoxyeicosatrienoic Acid Is Associated With Abdominal Aortic Calcification in Patients With Primary Aldosteronism

Patients with primary aldosteronism (PA) have increased risk of target-organ damage, among which vascular calcification is an important indicator of cardiovascular mortality. 14, 15-Epoxyeicosatrienoic acid (14, 15-EET) has been shown to have beneficial effects in vascular remodeling. However, whether 14, 15-EET associates with vascular calcification in PA is unknown. Thus, we aimed to investigate the association between 14, 15-EET and abdominal aortic calcification (AAC) in patients with PA. Sixty-nine patients with PA and 69 controls with essential hypertension, matched for age, sex, and blood pressure, were studied. 14, 15-Dihydroxyeicosatrienoic acid (14, 15-DHET), the inactive metabolite from 14, 15-EET, was estimated to reflect serum 14, 15-EET levels. AAC was assessed by computed tomographic scanning. Compared with matched controls, the AAC prevalence was almost 1-fold higher in patients with PA (27 [39.1%] versus 14 [20.3%]; P=0.023), accompanied by significantly higher serum 14, 15-DHET levels (7.18±4.98 versus 3.50±2.07 ng/mL; P<0.001). Plasma aldosterone concentration was positively associated with 14, 15-DHET (β=0.444; P<0.001). Multivariable logistic analysis revealed that lower 14, 15-DHET was an independent risk factor for AAC in PA (odds ratio, 1.371; 95% confidence interval, 1.145-1.640; P<0.001), especially in young patients with mild hypertension and normal body mass index. In conclusion, PA patients exibited more severe AAC, accompanied by higher serum 14, 15-DHET levels. On the contrary, decreased 14, 15-EET was significantly associated with AAC prevalence in PA patients, especially in those at low cardiovascular risk.

Microcalcifications, Their Genesis, Growth, and Biomechanical Stability in Fibrous Cap Rupture

For many decades, cardiovascular calcification has been considered as a passive process, accompanying atheroma progression, correlated with plaque burden, and apparently without a major role on plaque vulnerability. Clinical and pathological analyses have previously focused on the total amount of calcification (calcified area in a whole atheroma cross section) and whether more calcification means higher risk of plaque rupture or not. However, this paradigm has been changing in the last decade or so. Recent research has focused on the presence of microcalcifications (μCalcs) in the atheroma and more importantly on whether clusters of μCalcs are located in the cap of the atheroma. While the vast majority of μCalcs are found in the lipid pool or necrotic core, they are inconsequential to vulnerable plaque. Nevertheless, it has been shown that μCalcs located within the fibrous cap could be numerous and that they behave as an intensifier of the background circumferential stress in the cap. It is now known that such intensifying effect depends on the size and shape of the μCalc as well as the proximity between two or more μCalcs. If μCalcs are located in caps with very low background stress, the increase in stress concentration may not be sufficient to reach the rupture threshold. However, the presence of μCalc(s) in the cap with a background stress of about one fifth to one half the rupture threshold (a stable plaque) will produce a significant increase in local stress, which may exceed the cap rupture threshold and thus transform a non-vulnerable plaque into a vulnerable one. Also, the classic view that treats cardiovascular calcification as a passive process has been challenged, and emerging data suggest that cardiovascular calcification may encompass both passive and active processes. The passive calcification process comprises biochemical factors, specifically circulating nucleating complexes, which would lead to calcification of the atheroma. The active mechanism of atherosclerotic calcification is a cell-mediated process via cell death of macrophages and smooth muscle cells (SMCs) and/or the release of matrix vesicles by SMCs.

Cooperative stimulation of atherogenesis by lipopolysaccharide and palmitic acid-rich high fat diet in low-density lipoprotein receptor-deficient mice

BACKGROUND AND AIMS

Either lipopolysaccharide (LPS) or high-fat diet (HFD) enriched with saturated fatty acid (SFA) promotes atherosclerosis. In this study, we investigated the effect of LPS in combination with SFA-rich HFD on atherosclerosis and how LPS and SFA interact to stimulate inflammatory response in vascular endothelial cells.

METHODS

Low-density lipoprotein receptor-deficient (LDLR^-/-) mice were fed a low-fat diet (LFD), HFD with low palmitic acid (PA) (LP-HFD), or HFD with high PA (HP-HFD) for 20 weeks. During the last 12 weeks, half mice received LPS and half received PBS. After treatment, metabolic parameters and aortic atherosclerosis were analyzed. To understand the underlying mechanisms, human aortic endothelial cells (HAECs) were treated with LPS and/or PA and proinflammatory molecule expression was quantified.

RESULTS

The metabolic study showed that LPS had no significant effect on cholesterol, triglycerides, free fatty acids, but increased insulin and insulin resistance. Both LP-HFD and HP-HFD increased body weight and cholesterol while LP-HFD increased glucose and HP-HFD increased triglycerides, insulin, and insulin resistance. Analysis of aortic atherosclerosis showed that HP-HFD was more effective than LP-HFD in inducing atherosclerosis and LPS in combination with HP-HFD increased atherosclerosis in the thoracic aorta, a less common site for atherosclerosis, as compared with LPS or HP-HFD. To understand the mechanisms, results showed that LPS and PA synergistically upregulated adhesion molecules and proinflammatory cytokines in HAECs.

CONCLUSIONS

LPS and PA-rich HFD cooperatively increased atherogenesis in the thoracic aorta. The synergy between LPS and PA on proinflammatory molecules in HAECs may play an important role in atherogenesis.

Suppression of Wnt Signaling and Osteogenic Changes in Vascular Smooth Muscle Cells by Eicosapentaenoic Acid

Vascular medial calcification is often observed in patients with arteriosclerosis. It is also associated with systolic hypertension, wide pulse pressure, and fluctuation of blood pressure, which results in cardiovascular events. Eicosapentaenoic acid (EPA) has been shown to suppress vascular calcification in previous animal experiments. We investigated the inhibitory effects of EPA on Wnt signaling, which is one of the important signaling pathways involved in vascular calcification. Intake of food containing 5% EPA resulted in upregulation of the mRNA expression of Klotho, an intrinsic inhibitor of Wnt signaling, in the kidneys of wild-type mice. Expression levels of β-catenin, an intracellular signal transducer in the Wnt signaling pathway, were increased in the aortas of Klotho mutant (kl/kl) mice compared to the levels in the aortas of wild-type mice. Wnt3a or BIO, a GSK-3 inhibitor that activates β-catenin signaling, upregulated mRNA levels of AXIN2 and LEF1, Wnt signaling marker genes, and RUNX2 and BMP4, early osteogenic genes, in human aorta smooth muscle cells. EPA suppressed the upregulation of AXIN2 and BMP4. The effect of EPA was cancelled by T0070907, a PPARγ inhibitor. The results suggested that EPA could suppress vascular calcification via the inhibition of Wnt signaling in osteogenic vascular smooth muscle cells via PPARγ activation.

Eicosapentaenoic acid prevents arterial calcification in klotho mutant mice

BACKGROUND

The klotho gene was identified as an "aging-suppressor" gene that accelerates arterial calcification when disrupted. Serum and vascular klotho levels are reduced in patients with chronic kidney disease, and the reduced levels are associated with arterial calcification. Intake of eicosapentaenoic acid (EPA), an n-3 fatty acid, reduces the risk of fatal coronary artery disease. However, the effects of EPA on arterial calcification have not been fully elucidated. The aim of this study was to determine the effect of EPA on arterial calcification in klotho mutant mice.

METHODS AND RESULTS

Four-week-old klotho mutant mice and wild-type (WT) mice were given a diet containing 5% EPA (EPA food, klotho and WT: n = 12, each) or not containing EPA (control food, klotho and WT: n = 12, each) for 4 weeks. Calcium volume scores of thoracic and abdominal aortas assessed by computed tomography were significantly elevated in klotho mice after 4 weeks of control food, but they were not elevated in klotho mice after EPA food or in WT mice. Serum levels of EPA and resolvin E1, an active metabolite of EPA, in EPA food-fed mice were significantly increased compared to those in control food-fed mice. An oxidative stress PCR array followed by quantitative PCR revealed that NADPH oxidase-4 (NOX4), an enzyme that generates superoxide, gene expression was up-regulated in arterial smooth muscle cells (SMCs) of klotho mice. Activity of NOX was also significantly higher in SMCs of klotho mice than in those of WT mice. EPA decreased expression levels of the NOX4 gene and NOX activity. GPR120, a receptor of n-3 fatty acids, gene knockdown by siRNA canceled effects of EPA on NOX4 gene expression and NOX activity in arterial SMCs of klotho mice.

CONCLUSIONS

EPA prevents arterial calcification together with reduction of NOX gene expression and activity via GPR120 in klotho mutant mice.

Collagen XIV and a related recombinant fragment protect human vascular smooth muscle cells from calcium-/phosphate-induced osteochondrocytic transdifferentiation

Transdifferentiation of vascular smooth muscle cells (VSMC) promotes the development of vascular calcifications such as arteriosclerosis. The aim was to investigate effects of specific extracellular matrix (ECM) components on transdifferentiation of VSMC to identify novel ECM-based therapeutic tools. Human collagens I & IV (CI, CIV) along with collagen XIV (CXIV) and a CXIV-derived fragment (CXIV-F), both of which induce differentiation, were applied in an in-vitro model of calcium-/phosphate (Ca/P)-induced osteochondrocytic transdifferentiation of human and murine VSMC. Transdifferentiation was determined by RT-PCR and calcium contents of VSMC cultures. Signaling pathways involved were determined by western-blot and luciferase reporter plasmid assays. Under normal culture conditions, CI induced VSMC proliferation and a more epithelioid/synthetic phenotype while CIV and predominantly CXIV provoked opposite effects. CIV and CXIV further blocked Ca/P-induced osteochondrocytic transdifferentiation of VSMC displayed e.g. by reduced gene expressions of Runx2, Sox9, osterix and increased expressions of αSMA and SM22α. This involved impaired activation of ERK1/2, NF-ĸB and Wnt-signaling. Similar preventive effects were achieved by applying CXIV-F. Impaired preventive effects of CXIV by co-treatment with a cluster of differentiation (CD)44 agonist propose CD44 as a CXIV-target structure on VSMC. In conclusion, CXIV and CXIV-F interfere with osteochondrocytic transdifferentiation of VSMC and should be further explored as potential therapeutic tools in vascular calcification.

Kuei-Lu-Er-Xian-Jiao extract enhances BMP-2 production in osteoblasts

Osteoporosis is a common skeletal disorder, resulting from an imbalance in bone resorption relative to formation. Bone morphogenetic protein (BMP) is a key regulator in bone formation and osteoblastic differentiation. Hence, compounds that promote BMP expression may be suitable candidates for osteoporosis treatment. This study examined the effects of the traditional Chinese medicinal agent, Kuei-Lu-Er-Xian-Jiao (KLEXJ), on BMP-2 production in osteoblasts. We found that KLEXJ extract promoted osteoblastic differentiation marker ALP activity and increased BMP-2 production; pretreatment with PI3K and Akt inhibitors, or small interfering RNA (siRNA), reduced these effects. KLEXJ also enhanced PI3K and Akt phosphorylation. Treatment of osteoblastic cells with NF-κB inhibitors (TPCK or PDTC) markedly inhibited KLEXJ-enhancement of ALP activity and BMP-2 production. KLEXJ also significantly promoted p65 phosphorylation, while treatment with PI3K and Akt inhibitors antagonized KLEXJ-enhanced p65 phosphorylation. Thus, KLEXJ enhances ALP activity and BMP-2 production of osteoblasts through the PI3K/Akt/ NF-κB signaling pathway and hence may be suitable in the treatment of osteoporosis.

Systematic Analysis of Gene Expression Alterations and Clinical Outcomes for Long-Chain Acyl-Coenzyme A Synthetase Family in Cancer

Dysregulated lipid metabolism contributes to cancer progression. Our previous study indicates that long-chain fatty acyl-Co A synthetase (ACSL) 3 is essential for lipid upregulation induced by endoplasmic reticulum stress. In this report, we aimed to identify the role of ACSL family in cancer with systematic analysis and in vitro experiment. We explored the ACSL expression using Oncomine database to determine the gene alteration during carcinogenesis and identified the association between ACSL expression and the survival of cancer patient using PrognoScan database. ACSL1 may play a potential oncogenic role in colorectal and breast cancer and play a potential tumor suppressor role in lung cancer. Co-expression analysis revealed that ACSL1 was coexpressed with MYBPH, PTPRE, PFKFB3, SOCS3 in colon cancer and with LRRFIP1, TSC22D1 in lung cancer. In accordance with PrognoScan analysis, downregulation of ACSL1 in colon and breast cancer cell line inhibited proliferation, migration, and anchorage-independent growth. In contrast, increase of oncogenic property was observed in lung cancer cell line by attenuating ACSL1. High ACSL3 expression predicted a better prognosis in ovarian cancer; in contrast, high ACSL3 predicted a worse prognosis in melanoma. ACSL3 was coexpressed with SNUPN, TRIP13, and SEMA5A in melanoma. High expression of ACSL4 predicted a worse prognosis in colorectal cancer, but predicted better prognosis in breast, brain and lung cancer. ACSL4 was coexpressed with SERPIN2, HNRNPCL1, ITIH2, PROCR, LRRFIP1. High expression of ACSL5 predicted good prognosis in breast, ovarian, and lung cancers. ACSL5 was coexpressed with TMEM140, TAPBPL, BIRC3, PTPRE, and SERPINB1. Low ACSL6 predicted a worse prognosis in acute myeloid leukemia. ACSL6 was coexpressed with SOX6 and DARC. Altogether, different members of ACSLs are implicated in diverse types of cancer development. ACSL-coexpressed molecules may be used to further investigate the role of ACSL family in individual type of cancers.

Omega-3 fatty acids differentially modulate enzymatic anti-oxidant systems in skeletal muscle cells

During physical activity, increased reactive oxygen species production occurs, which can lead to cell damage and in a decline of individual's performance and health. The use of omega-3 polyunsaturated fatty acids as a supplement to protect the immune system has been increasing; however, their possible benefit to the anti-oxidant system is not well described. Thus, the aim of this study was to evaluate whether the omega-3 fatty acids (docosahexaenoic acid and eicosapentaenoic acid) can be beneficial to the anti-oxidant system in cultured skeletal muscle cells. C2C12 myocytes were differentiated and treated with either eicosapentaenoic acid or docosahexaenoic acid for 24 h. Superoxide content was quantified using the dihydroethidine oxidation method and superoxide dismutase, catalase, and glutathione peroxidase activity, and expression was quantified. We observed that the docosahexaenoic fatty acids caused an increase in superoxide production. Eicosapentaenoic acid induced catalase activity, while docosahexaenoic acid suppressed superoxide dismutase activity. In addition, we found an increased protein expression of the total manganese superoxide dismutase and catalase enzymes when cells were treated with eicosapentaenoic acid. Taken together, these data indicate that the use of eicosapentaenoic acid may present both acute and chronic benefits; however, the treatment with DHA may not be beneficial to muscle cells.

Saturated phosphatidic acids mediate saturated fatty acid-induced vascular calcification and lipotoxicity

Recent evidence indicates that saturated fatty acid-induced (SFA-induced) lipotoxicity contributes to the pathogenesis of cardiovascular and metabolic diseases; however, the molecular mechanisms that underlie SFA-induced lipotoxicity remain unclear. Here, we have shown that repression of stearoyl-CoA desaturase (SCD) enzymes, which regulate the intracellular balance of SFAs and unsaturated FAs, and the subsequent accumulation of SFAs in vascular smooth muscle cells (VSMCs), are characteristic events in the development of vascular calcification. We evaluated whether SMC-specific inhibition of SCD and the resulting SFA accumulation plays a causative role in the pathogenesis of vascular calcification and generated mice with SMC-specific deletion of both Scd1 and Scd2. Mice lacking both SCD1 and SCD2 in SMCs displayed severe vascular calcification with increased ER stress. Moreover, we employed shRNA library screening and radiolabeling approaches, as well as in vitro and in vivo lipidomic analysis, and determined that fully saturated phosphatidic acids such as 1,2-distearoyl-PA (18:0/18:0-PA) mediate SFA-induced lipotoxicity and vascular calcification. Together, these results identify a key lipogenic pathway in SMCs that mediates vascular calcification.

A Lindera obtusiloba Extract Blocks Calcium-/Phosphate-Induced Transdifferentiation and Calcification of Vascular Smooth Muscle Cells and Interferes with Matrix Metalloproteinase-2 and Metalloproteinase-9 and NF-κB

Vascular calcifications bear the risk for cardiovascular complications and have a high prevalence among patients with chronic kidney disease. Central mediators of vascular calcifications are vascular smooth muscle cells (VSMC). They transdifferentiate into a synthetic/osteoblast-like phenotype, which is induced, for example, by elevated levels of calcium and phosphate (Ca/P) due to a disturbed mineral balance. An aqueous extract from Lindera obtusiloba (LOE) is known to exert antifibrotic and antitumor effects or to interfere with the differentiation of preadipocytes. Using murine and rat VSMC cell lines, we here investigated whether LOE also protects VSMC from Ca/P-induced calcification. Indeed, LOE effectively blocked Ca/P-induced calcification of VSMC as shown by decreased VSMC mineralization and secretion of alkaline phosphatase. In parallel, mRNA expression of the calcification markers osterix and osteocalcin was reduced. Vice versa, the Ca/P-induced loss of the VSMC differentiation markers alpha smooth muscle actin and smooth muscle protein 22-alpha was rescued by LOE. Further, LOE blocked Ca/P-induced mRNA expressions and secretions of matrix metalloproteinases-2/-9 and activation of NF-κB, which are known contributors to vascular calcification. In conclusion, LOE interferes with the Ca/P-induced transdifferentiation/calcification of VSMC. Thus, LOE should be further analysed regarding a potential complementary treatment option for cardiovascular diseases including vascular calcifications.

Cellular and Molecular Mechanisms of Chronic Kidney Disease with Diabetes Mellitus and Cardiovascular Diseases as Its Comorbidities

Chronic kidney disease (CKD), diabetes mellitus (DM), and cardiovascular diseases (CVD) are complex disorders of partly unknown genesis and mostly known progression factors. CVD and DM are the risk factors of CKD and are strongly intertwined since DM can lead to both CKD and/or CVD, and CVD can lead to kidney disease. In recent years, our knowledge of CKD, DM, and CVD has been expanded and several important experimental, clinical, and epidemiological associations have been reported. The tight cellular and molecular interactions between the renal, diabetic, and cardiovascular systems in acute or chronic disease settings are becoming increasingly evident. However, the (patho-) physiological basis of the interactions of CKD, DM, and CVD with involvement of multiple endogenous and environmental factors is highly complex and our knowledge is still at its infancy. Not only single pathways and mediators of progression of these diseases have to be considered in these processes but also the mutual interactions of these factors are essential. The recent advances in proteomics and integrative analysis technologies have allowed rapid progress in analyzing complex disorders and clearly show the opportunity for new efficient and specific therapies. More than a dozen pathways have been identified so far, including hyperactivity of the renin–angiotensin (RAS)–aldosterone system, osmotic sodium retention, endothelial dysfunction, dyslipidemia, RAS/RAF/extracellular-signal-regulated kinase pathway, modification of the purinergic system, phosphatidylinositol 3-kinase (PI 3-kinase)-dependent signaling pathways, and inflammation, all leading to histomorphological alterations of the kidney and vessels of diabetic and non-diabetic patients. Since a better understanding of the common cellular and molecular mechanisms of these diseases may be a key to successful identification of new therapeutic targets, we review in this paper the current literature about cellular and molecular mechanisms of CKD.

Inflammation: a culprit for vascular calcification in atherosclerosis and diabetes

It is today acknowledged that aging is associated with a low-grade chronic inflammatory status, and that inflammation exacerbates age-related diseases such as osteoporosis, Alzheimer's disease, atherosclerosis and type 2 diabetes mellitus (T2DM). Vascular calcification is a complication that also occurs during aging, in particular in association with atherosclerosis and T2DM. Recent studies provided compelling evidence that vascular calcification is associated with inflammatory status and is enhanced by inflammatory cytokines. In the present review, we propose on one hand to highlight the most important and recent findings on the cellular and molecular mechanisms of vascular inflammation in atherosclerosis and T2DM. On the other hand, we will present the effects of inflammatory mediators on the trans-differentiation of vascular smooth muscle cell and on the deposition of crystals. Since vascular calcification significantly impacts morbidity and mortality in affected individuals, a better understanding of its induction and development will pave the way to develop new therapeutic strategies.

Vascular calcification in chronic kidney disease: an update

Cardiovascular calcification is both a risk factor and contributor to morbidity and mortality. Patients with chronic kidney disease (and/or diabetes) exhibit accelerated calcification of the intima, media, heart valves and likely the myocardium as well as the rare condition of calcific uraemic arteriolopathy (calciphylaxis). Pathomechanistically, an imbalance of promoters (e.g. calcium and phosphate) and inhibitors (e.g. fetuin-A and matrix Gla protein) is central in the development of calcification. Next to biochemical and proteinacous alterations, cellular processes are also involved in the pathogenesis. Vascular smooth muscle cells undergo osteochondrogenesis, excrete vesicles and show signs of senescence. Therapeutically, measures to prevent the initiation of calcification by correcting the imbalance of promoters and inhibitors appear to be essential. In contrast to prevention, therapeutic regression of cardiovascular calcification in humans has been rarely reported. Measures to enhance secondary prevention in patients with established cardiovascular calcifications are currently being tested in clinical trials.