Galectin-3 induces vascular smooth muscle cells calcification via AMPK/TXNIP pathway

Myocardin related transcription factor and galectin-3 drive lipid accumulation in human blood vessels

OBJECTIVE

Diabetes and hypertension are important risk factors for vascular disease, including atherosclerosis. A driving factor in this process is lipid accumulation in smooth muscle cells of the vascular wall. The glucose- and mechano-sensitive transcriptional coactivator, myocardin-related transcription factor A (MRTF-A/MKL1) can promote lipid accumulation in cultured human smooth muscle cells and contribute to the formation of smooth muscle-derived foam cells. The purpose of this study was to determine if intact human blood vessels ex vivo can be used to evaluate lipid accumulation in the vascular wall, and if this process is dependent on MRTF and/or galectin-3/LGALS3. Galectin-3 is an early marker of smooth muscle transdifferentiation and a potential mediator for foam cell formation and atherosclerosis.

APPROACH AND RESULTS

Human mammary arteries and saphenous veins were exposed to altered cholesterol and glucose levels in an organ culture model. Accumulation of lipids, quantified by Oil Red O, was increased by cholesterol loading and elevated glucose concentrations. Pharmacological inhibition of MRTF with CCG-203971 decreased lipid accumulation, whereas adenoviral-mediated overexpression of MRTF-A had the opposite effect. Cholesterol-induced expression of galectin-3 was decreased after inhibition of MRTF. Importantly, pharmacological inhibition of galectin-3 with GB1107 reduced lipid accumulation in the vascular wall after cholesterol loading.

CONCLUSION

Ex vivo organ culture of human arteries and veins can be used to evaluate lipid accumulation in the intact vascular wall, as well as adenoviral transduction and pharmacological inhibition. Although MRTF and galectin-3 may have beneficial, anti-inflammatory effects under certain circumstances, our results, which demonstrate a significant decrease in lipid accumulation, support further evaluation of MRTF- and galectin-3-inhibitors for therapeutic intervention against atherosclerotic vascular disease.

L-type calcium ion channel-mediated activation of autophagy in vascular smooth muscle cells via thonningianin A (TA) alleviates vascular calcification in type 2 diabetes mellitus

Vascular calcification (VC) is associated with increased morbidity and mortality, especially among people with type 2 diabetes mellitus (T2DM). The pathogenesis of vascular calcification is incompletely understood, and until now, there have been no effective therapeutics for vascular calcification. The L-type calcium ion channel in the cell membrane is vital for Ca2+ influx. The effect of L-type calcium ion channels on autophagy remains to be elucidated. Here, the natural compound thonningianin A (TA) was found to ameliorate vascular calcification in T2DM via the activation of L-type calcium ion channels. The results showed that TA had a concentration-dependent ability to decrease the transcriptional and translational expression of the calcification-related proteins runt-related transcription factor 2 (RUNX2), bone morphogenetic protein 2 (BMP2) and osteopontin (OPN) (P < 0.01) via ATG7-dependent autophagy in β-glycerophosphate (β-GP)- and high glucose (HG)-stimulated primary mouse aortic smooth muscle cells (MASMCs) and alleviate aortic vascular calcification in VitD3-stimulated T2DM mice. However, nifedipine, an inhibitor of L-type calcium ion channels, reversed TA-induced autophagy and Ca2+ influx in MASMCs. Molecular docking analysis revealed that TA was located in the hydrophobic pocket of Cav1.2 α1C and was mainly composed of the residues Ile, Phe, Ala and Met, which confirmed the efficacy of TA in targeting the L-type calcium channel of Cav1.2 on the cell membrane. Moreover, in an in vivo model of vascular calcification in T2DM mice, nifedipine reversed the protective effects of TA on aortic calcification and the expression of the calcification-related proteins RUNX2, BMP2 and OPN (P < 0.01). Collectively, the present results reveal that the activation of cell membrane L-type calcium ion channels can induce autophagy and ameliorate vascular calcification in T2DM. Thonningianin A (TA) can target and act as a potent activator of L-type calcium ion channels. Thus, this research revealed a novel mechanism for autophagy induction via L-type calcium ion channels and provided a potential therapeutic for vascular calcification in T2DM.

Role of galectin-3 in vascular calcification

Vascular calcification is an abnormal process in which bone specific hydroxyapatite crystals are actively deposited on the vascular wall mediated by phenotypic differentiated smooth muscle cells and other mesenchymal cells under various pathological conditions. It is one of the important characteristics in the occurrence and development of atherosclerosis, prevalent in patients with type 2 diabetes and advanced chronic kidney disease, especially those requiring maintenance hemodialysis, with severely threatening human health. Previous studies have shown that the early diagnosis and control of vascular calcification is of great significance for cardiovascular risk stratification, prevention of acute cardiovascular events, which can greatly improve the prognosis and quality of life of patients. Galectins are a family of lectin superfamily. It is widely distributed in various animals and plays an important role in many physiological and pathological processes, such as cell adhesion, apoptosis, inflammatory response, tumor metastasis and so on. Many biomarker-and association-related studies and Preclinical-mechanistic studies have suggested that galactose-specific lectin-3 (galectin-3) plays an important role in vascular calcification and vascular intimal calcification (VIC) calcification induced by Wnt/βcatenin signaling pathway, NF-κB signaling pathway and ERK1/2 signaling pathway. This paper mainly expounds the role and mechanism of galectin-3 in vascular calcification under different pathological conditions including atherosclerosis, diabetes and chronic kidney disease.

TXNIP Suppresses the Osteochondrogenic Switch of Vascular Smooth Muscle Cells in Atherosclerosis

BACKGROUND

The osteochondrogenic switch of vascular smooth muscle cells (VSMCs) is a pivotal cellular process in atherosclerotic calcification. However, the exact molecular mechanism of the osteochondrogenic transition of VSMCs remains to be elucidated. Here, we explore the regulatory role of TXNIP (thioredoxin-interacting protein) in the phenotypical transitioning of VSMCs toward osteochondrogenic cells responsible for atherosclerotic calcification.

METHODS

The atherosclerotic phenotypes of Txnip^-/- mice were analyzed in combination with single-cell RNA-sequencing. The atherosclerotic phenotypes of Tagln-Cre; Txnip^flox/flox mice (smooth muscle cell-specific Txnip ablation model), and the mice transplanted with the bone marrow of Txnip^-/- mice were analyzed. Public single-cell RNA-sequencing dataset (GSE159677) was reanalyzed to define the gene expression of TXNIP in human calcified atherosclerotic plaques. The effect of TXNIP suppression on the osteochondrogenic phenotypic changes in primary aortic VSMCs was analyzed.

RESULTS

Atherosclerotic lesions of Txnip^-/- mice presented significantly increased calcification and deposition of collagen content. Subsequent single-cell RNA-sequencing analysis identified the modulated VSMC and osteochondrogenic clusters, which were VSMC-derived populations. The osteochondrogenic cluster was markedly expanded in Txnip^-/- mice. The pathway analysis of the VSMC-derived cells revealed enrichment of bone- and cartilage-formation-related pathways and bone morphogenetic protein signaling in Txnip^-/- mice. Reanalyzing public single-cell RNA-sequencing dataset revealed that TXNIP was downregulated in the modulated VSMC and osteochondrogenic clusters of human calcified atherosclerotic lesions. Tagln-Cre; Txnip^flox/flox mice recapitulated the calcification and collagen-rich atherosclerotic phenotypes of Txnip^-/- mice, whereas the hematopoietic deficiency of TXNIP did not affect the lesion phenotype. Suppression of TXNIP in cultured VSMCs accelerates osteodifferentiation and upregulates bone morphogenetic protein signaling. Treatment with the bone morphogenetic protein signaling inhibitor K02288 abrogated the effect of TXNIP suppression on osteodifferentiation.

CONCLUSIONS

Our results suggest that TXNIP is a novel regulator of atherosclerotic calcification by suppressing bone morphogenetic protein signaling to inhibit the transition of VSMCs toward an osteochondrogenic phenotype.

The Endothelial Transcription Factor ERG Mediates a Differential Role in the Aneurysmatic Ascending Aorta with Bicuspid or Tricuspid Aorta Valve: A Preliminary Study

The pathobiology of ascending aorta aneurysms (AAA) onset and progression is not well understood and only partially characterized. AAA are also complicated in case of bicuspid aorta valve (BAV) anatomy. There is emerging evidence about the crucial role of endothelium-related pathways, which show in AAA an altered expression and function. Here, we examined the involvement of ERG-related pathways in the differential progression of disease in aortic tissues from patients having a BAV or tricuspid aorta valve (TAV) with or without AAA. Our findings identified ERG as a novel endothelial-specific regulator of TGF-β-SMAD, Notch, and NO pathways, by modulating a differential fibrotic or calcified AAA progression in BAV and TAV aortas. We provided evidence that calcification is correlated to different ERG expression (as gene and protein), which appears to be under control of Notch signaling. The latter, when increased, associated with an early calcification in aortas with BAV valve and aneurysmatic, was demonstrated to favor the progression versus severe complications, i.e., dissection or rupture. In TAV aneurysmatic aortas, ERG appeared to modulate fibrosis. Therefore, we proposed that ERG may represent a sensitive tissue biomarker to monitor AAA progression and a target to develop therapeutic strategies and influence surgical procedures.