Wnt3a/β-catenin increases proliferation in heart valve interstitial cells

Pax6 regulates neuronal migration and cell proliferation via interacting with Wnt3a during cortical development

The paired box 6 (Pax6) gene encodes a highly conserved transcription factor, involved in the development of eyes, brain, and endocrine glands. Homozygous loss of Pax6 resulted in neonatal death in mice, plus loss of eyes and malformation of cerebral cortex. In patients with heterozygous Pax6 mutations, a reduction in thickness of the frontoparietal cortex was detected, which was also observed in small eye mice. In this study, we found that Pax6 overexpression increased the cortical thickness, especially in the intermediate zone of the cortex, which conflicts with the report of Manuel et al. Pax6 overexpression appears to detain neurons in the intermediate zone while promoting cell proliferation. It is worth noting that the impact of Pax6 overexpression on cortical thickness and neuronal migration was temporal, explaining the differences with other reports. We postulated that the alteration of Pax6 isoform ratio by autoregulation might be responsible for this. JASPAR analysis together with the results of qPCR, Western blot, CUT&Tag, and rescue experiments revealed that Pax6 regulates neuronal migration and cell proliferation by indirectly mediating Wnt3a expression. Therefore, we propose that Pax6 participates in corticogenesis via interaction with Wnt3a in regulating neuronal migration and cell proliferation.

The Role of Trace Elements in Cardiovascular Diseases

Essential trace elements play an important role in human physiology and are associated with various functions regulating cellular metabolism. Non-essential trace elements, on the other hand, often have well-documented toxicities that are dangerous for the initiation and development of diseases due to their widespread occurrence in the environment and their accumulation in living organisms. Non-essential trace elements are therefore regarded as serious environmental hazards that are harmful to health even in low concentrations. Many representatives of these elements are present as pollutants in our environment, and many people may be exposed to significant amounts of these substances over the course of their lives. Among the most common non-essential trace elements are heavy metals, which are also associated with acute poisoning in humans. When these elements accumulate in the body over years of chronic exposure, they often cause severe health damage in a variety of tissues and organs. In this review article, the role of selected essential and non-essential trace elements and their role in the development of exemplary pathophysiological processes in the cardiovascular system will be examined in more detail.

β-Catenin regulates endocardial cushion growth by suppressing p21

Endocardial cushion formation is essential for heart valve development and heart chamber separation. Abnormal endocardial cushion formation often causes congenital heart defects. β-Catenin is known to be essential for endocardial cushion formation; however, the underlying cellular and molecular mechanisms remain incompletely understood. Here, we show that endothelial-specific deletion of β-catenin in mice resulted in formation of hypoplastic endocardial cushions due to reduced cell proliferation and impaired cell migration. By using a β-catenin DM allele in which the transcriptional function of β-catenin is selectively disrupted, we further reveal that β-catenin regulated cell proliferation and migration through its transcriptional and non-transcriptional function, respectively. At the molecular level, loss of β-catenin resulted in increased expression of cell cycle inhibitor p21 in cushion endocardial and mesenchymal cells in vivo. In vitro rescue experiments with HUVECs and pig aortic valve interstitial cells confirmed that β-catenin promoted cell proliferation by suppressing p21. In addition, one savvy negative observation is that β-catenin was dispensable for endocardial-to-mesenchymal fate change. Taken together, our findings demonstrate that β-catenin is essential for cell proliferation and migration but dispensable for endocardial cells to gain mesenchymal fate during endocardial cushion formation. Mechanistically, β-catenin promotes cell proliferation by suppressing p21. These findings inform the potential role of β-catenin in the etiology of congenital heart defects.

Telocytes-derived extracellular vesicles alleviate aortic valve calcification by carrying miR-30b

AIMS

Calcific aortic valve disease (CAVD) is frequent in the elderly. Telocytes (TCs) are implicated in intercellular communication by releasing extracellular vesicles (EVs). This study investigated the role of TC-EVs in aortic valve calcification.

METHODS AND RESULTS

TCs were obtained and identified using enzymolysis method and flow cytometry. EVs were isolated from TCs using differential high-speed centrifugation method and identified using transmission electron microscope, western blot, and qNano analysis. The mouse model of CAVD was established. The changes of aortic valve activity-related indicators were analysed by ultrasound, and the expressions of TC markers CD34 and vimentin in mouse valve tissues were detected using RT-qPCR and western blot. The model mice were injected with TC-derived EVs. The expressions of Runx2, osteocalcin, and caspase-3 were detected using RT-qPCR and western blot. The calcification model of valvular interstitial cells (VICs) was established. TC-EVs were co-cultured with calcified VICs, and calcium deposition was detected using alizarin red S staining. miR-30b expression in calcified valvular tissues and cells was detected after EV treatment. miR-30b expression in TCs was knocked down and then EVs were extracted and co-cultured with calcified VICs. The target of miR-30b was predicted through bioinformatics website and verified using dual-luciferase assay. The levels of Wnt/β-catenin pathway-related proteins were detected. ApoE^-/- mice fed with a high-fat diet showed decreased aortic valve orifice area, increased aortic transvalvular pressure difference and velocity, reduced left ventricular ejection fraction, decreased CD34 and vimentin, and increased caspase-3, Runx2, and osteocalcin. The levels of apoptosis- and osteogenesis- related proteins were inhibited after EV treatment. TC-EVs reduced calcium deposition and osteogenic proteins in calcified VICs. EVs could be absorbed by VICs. miR-30b expression was promoted in calcified valvular tissues and cells after EV treatment. Knockdown of miR-30b weakened the inhibitory effects of TC-EVs on calcium deposition and osteogenic proteins. miR-30b targeted Runx2. EV treatment inhibited the Wnt/β-catenin pathway, and knockdown of miR-30b in TCs attenuated the inhibitory effect of TC-EVs on the Wnt/β-catenin pathway.

CONCLUSION

TC-EVs played a protective role in aortic valve calcification via the miR-30b/Runx2/Wnt/β-catenin axis.

Warfarin Induces Calcification of the Aortic Valve via ERK1/2 and β-Catenin Signaling

BACKGROUND

Recent clinical evidence suggests an association between warfarin use and calcification of the aortic valve. We sought to determine the effect of warfarin on aortic valve interstitial cell (AVIC) osteogenic protein expression and the signaling pathways by which this effect is mediated.

METHODS

Human AVICs were isolated from normal aortic valves of patients undergoing cardiac transplantation while diseased AVICs were isolated from patients undergoing aortic valve replacement for aortic stenosis. AVICs were treated with various anticoagulants and osteogenic protein expression was evaluated using immunoblotting. Phosphorylation of LRP6 and ERK1/2 was evaluated following treatment with warfarin. AVICs were pretreated with LRP6 inhibitor dkk1 and ERK1/2 inhibitor PD98059 followed by treatment with warfarin and osteogenic protein expression was evaluated.

RESULTS

Warfarin, but not heparin or dabigatran, significantly increased Runx-2 and Osx expression in both normal and diseased human AVICs. Upregulation of β-catenin protein expression and nuclear translocation occurred in diseased AVICs, but not normal AVICs after warfarin treatment. Warfarin induced phosphorylation of LRP6 in diseased AVICs only, and phosphorylation of ERK1/2 in both normal and diseased AVICs. LRP6 inhibition attenuated warfarin-induced Runx-2 expression in diseased AVICs. ERK1/2 inhibition attenuated warfarin-induced Runx-2 expression in both normal and diseased AVICs.

CONCLUSIONS

Warfarin induces osteogenic activity in normal and diseased isolated human AVICs. This effect is mediated by ERK1/2 in both diseased and normal AVICs, but in diseased AVICs, β-catenin signaling also plays a role. These results implicate the role of warfarin in aortic valve calcification and highlight potential mechanisms for warfarin-induced aortic stenosis.

Gefitinib suppresses cervical cancer progression by inhibiting cell cycle progression and epithelial-mesenchymal transition

Cervical cancer (CC) is the second most common malignant cancer among women. Gefitinib was one of the first-generation epidermal growth factor receptor-tyrosine kinase inhibitors in clinical trials. However, the underlying mechanism of gefitinib in regulating CC progression remains unknown. In the current study, two CC cell lines, HeLa and Siha, were used to investigate the effects of gefitinib. Cell counting kit-8 assays demonstrated that treatment with gefitinib exerted strong cytotoxicity in HeLa and Siha cells. Flow cytometry was used to examine cell cycle progression and apoptosis. Treatment with gefitinib enhanced the number of cells in the G₀/G₁ phase and increased apoptosis in HeLa and Siha cells. Furthermore, treatment with gefitinib decreased the protein expression level of Bcl-2 and increased the protein expression level of Bax. Taken together, these results suggest that gefitinib may suppress CC cell proliferation and induce cell cycle arrest and apoptosis. The current study also demonstrated that treatment with gefitinib suppressed epithelial-mesenchymal transition (EMT) as the expression level of the epithelial marker, E-cadherin was increased, while the expression level of the mesenchymal marker, vimentin was decreased. The current study demonstrated that treatment with gefitinib decreased the protein expression levels of phosphorylated-GSK3β and β-catenin, which suggests that gefitinib may be a potential novel therapeutic strategy in CC by suppressing the Wnt/β-catenin signaling pathway and EMT to inhibit tumor metastasis in CC cells. In conclusion, gefitinib may suppress the EMT process during cell invasion and induce cell apoptosis and cell cycle arrest via inhibition of the Wnt/β-catenin signaling pathway.

Development of calcific aortic valve disease: Do we know enough for new clinical trials?

Calcific aortic valve disease (CAVD), previously thought to represent a passive degeneration of the valvular extracellular matrix (VECM), is now regarded as an intricate multistage disorder with sequential yet intertangled and interacting underlying processes. Endothelial dysfunction and injury, initiated by disturbed blood flow and metabolic disorders, lead to the deposition of low-density lipoprotein cholesterol in the VECM further provoking macrophage infiltration, oxidative stress, and release of pro-inflammatory cytokines. Such changes in the valvular homeostasis induce differentiation of normally quiescent valvular interstitial cells (VICs) into synthetically active myofibroblasts producing excessive quantities of the VECM and proteins responsible for its remodeling. As a result of constantly ongoing degradation and re-deposition, VECM becomes disorganised and rigid, additionally potentiating myofibroblastic differentiation of VICs and worsening adaptation of the valve to the blood flow. Moreover, disrupted and excessively vascularised VECM is susceptible to the dystrophic calcification caused by calcium and phosphate precipitating on damaged collagen fibers and concurrently accompanied by osteogenic differentiation of VICs. Being combined, passive calcification and biomineralisation synergistically induce ossification of the aortic valve ultimately resulting in its mechanical incompetence requiring surgical replacement. Unfortunately, multiple attempts have failed to find an efficient conservative treatment of CAVD; however, therapeutic regimens and clinical settings have also been far from the optimal. In this review, we focused on interactions and transitions between aforementioned mechanisms demarcating ascending stages of CAVD, suggesting a predisposing condition (bicuspid aortic valve) and drug combination (lipid-lowering drugs combined with angiotensin II antagonists and cytokine inhibitors) for the further testing in both preclinical and clinical trials.

Nigericin Inhibits Epithelial Ovarian Cancer Metastasis by Suppressing the Cell Cycle and Epithelial-Mesenchymal Transition

Epithelial ovarian cancer (EOC) has the highest mortality among various types of gynecological malignancies. Most patients die of metastasis and recurrence due to cisplatin resistance. Thus, it is urgent to develop novel therapies to cure this disease. CCK-8 assay showed that nigericin exhibited strong cytotoxicity on A2780 and SKOV3 cell lines. Flow cytometry indicated that nigericin could induce cell cycle arrest at G0/G1 phase and promote cell apoptosis. Boyden chamber assay revealed that nigericin could inhibit migration and invasion in a dose-dependent manner by suppressing epithelial-mesenchymal transition (EMT) in EOC cells. These effects were mediated, at least partly, by the Wnt/β-catenin signaling pathway. Our results demonstrated that nigericin could inhibit EMT during cell invasion and metastasis through the canonical Wnt/β-catenin signaling pathway. Nigericin may prove to be a novel therapeutic strategy that is effective in patients with metastatic EOC.

Inflammation Drives Retraction, Stiffening, and Nodule Formation via Cytoskeletal Machinery in a Three-Dimensional Culture Model of Aortic Stenosis

In calcific aortic valve disease, the valve cusps undergo retraction, stiffening, and nodular calcification. The inflammatory cytokine, tumor necrosis factor (TNF)-α, contributes to valve disease progression; however, the mechanisms of its actions on cusp retraction and stiffening are unclear. We investigated effects of TNF-α on murine aortic valvular interstitial cells (VICs) within three-dimensional, free-floating, compliant, collagen hydrogels, simulating their natural substrate and biomechanics. TNF-α increased retraction (percentage of diameter), stiffness, and formation of macroscopic, nodular structures with calcification in the VIC-laden hydrogels. The effects of TNF-α were attenuated by blebbistatin inhibition of myosin II-mediated cytoskeletal contraction. Inhibition of actin polymerization with cytochalasin-D, but not inhibition of Rho kinase with Y27632, blocked TNF-α-induced retraction in three-dimensional VIC hydrogels, suggesting that actin stress fibers mediate TNF-α-induced effects. In the hydrogels, inhibitors of NF-κB blocked TNF-α-induced retraction, whereas simultaneous inhibition of c-Jun N-terminal kinase was required to block TNF-α-induced stiffness. TNF-α also significantly increased collagen deposition, as visualized by Masson's trichrome staining, and up-regulated mRNA expression of discoidin domain receptor tyrosine kinase 2, fibronectin, and α-smooth muscle actin. In human aortic valves, calcified cusps were stiffer and had more collagen deposition than noncalcified cusps. These findings suggest that inflammation, through stimulation of cytoskeletal contractile activity, may be responsible for valvular cusp retraction, stiffening, and formation of calcified nodules.

Heart valve health, disease, replacement, and repair: a 25-year cardiovascular pathology perspective

The past several decades have witnessed major advances in the understanding of the structure, function, and biology of native valves and the pathobiology and clinical management of valvular heart disease. These improvements have enabled earlier and more precise diagnosis, assessment of the proper timing of surgical and interventional procedures, improved prosthetic and biologic valve replacements and repairs, recognition of postoperative complications and their management, and the introduction of minimally invasive approaches that have enabled definitive and durable treatment for patients who were previously considered inoperable. This review summarizes the current state of our understanding of the mechanisms of heart valve health and disease arrived at through innovative research on the cell and molecular biology of valves, clinical and pathological features of the most frequent intrinsic structural diseases that affect the valves, and the status and pathological considerations in the technological advances in valvular surgery and interventions. The contributions of many cardiovascular pathologists and other scientists, engineers, and clinicians are emphasized, and potentially fruitful areas for research are highlighted.

Iron alters valvular interstitial cell function and is associated with calcification in aortic stenosis

Aims

Aortic valve stenosis (AS) is the most common valvulopathy and is characterized by inflammation, extracellular matrix (ECM) remodelling and calcification, causing a narrowing of the valve and the consequential obstruction of the cardiac outflow. Although intraleaflet haemorrhage is associated with AS progression, the mechanisms involved are not known. The aims of this study were to identify valvular iron in relation to pathological changes associated with AS and the effects on valvular interstitial cells (VIC) in terms of iron uptake and iron-induced responses.

Methods and results

Valvular iron accumulation was detected by Perls' staining on aortic valve sections and shown to increase with the extent of calcification. Furthermore, qRT–PCR analysis revealed that iron-containing valve regions exhibited increased expression of genes involved in ECM remodelling and calcification. In addition, we demonstrate that iron transporters are regulated by pathways with major impact on AS and that VIC can take up and accumulate iron, which resulted in increased proliferation and decreased elastin production.

Conclusion

Iron, which may accumulate in the aortic valve by means of intraleaflet haemorrhages, can be taken up by VIC in a pro-inflammatory environment and actively contribute to VIC proliferation, ECM remodelling and calcification. These findings suggest a possible mechanism through which iron uptake by VIC may favour AS progression.

Wnt3a suppresses Pseudomonas aeruginosa-induced inflammation and promotes bacterial killing in macrophages

Pseudomonas aeruginosa (PA) is a common Gram‑negative bacterium and can cause serious infections, including hospital‑acquired pneumonia, suppurative bacterial keratitis and acute burn wound infection. The pathogenesis of PA infections is closely associated with excessive inflammatory responses and bacterial virulence factors. Wingless‑type MMTV integration site family, member 3A (Wnt3a), an upstream mediator in the canonical Wnt signaling pathway, has been implicated as a regulator of inflammation. However, its role in PA‑induced inflammation and bacterial clearance remains unknown. In the present study, the efficacy of Wnt3a conditioned media (Wnt3a‑CM) was assessed using western blotting and immunofluorescence, which showed that β‑catenin, a downstream molecule of Wnt3a, was upregulated and translocated to the nucleus following exposure to 50% Wnt3a‑CM for 6 h. To explore the role of Wnt3a in PA‑induced inflammation, the mRNA levels of pro‑inflammatory cytokines and apoptosis in macrophages were measured using reverse transcription‑quantitative polymerase chain reaction and flow cytometry, respectively. This indicated that Wnt3a suppressed inflammation by reducing the production of pro‑inflammatory cytokines and by promoting apoptosis in macrophages. Furthermore, the mechanism of macrophage‑mediated bacterial killing was investigated, and the results indicated that Wnt3a enhanced macrophage‑mediated intracellular bacterial killing via the induction of the production of cathelicidin‑related antimicrobial peptide and β‑defensins 1. Taken together, the current study explored the role of Wnt3a in inflammation and bacterial invasion, which may provide an improved understanding of host resistance to PA infection.

Nonbiased Molecular Screening Identifies Novel Molecular Regulators of Fibrogenic and Proliferative Signaling in Myxomatous Mitral Valve Disease

BACKGROUND

Pathological processes underlying myxomatous mitral valve degeneration (MMVD) remain poorly understood. We sought to identify novel mechanisms contributing to the development of this condition.

METHODS AND RESULTS

Microarrays were used to measure gene expression in 11 myxomatous and 11 nonmyxomatous human mitral valves. Differential gene expression (thresholds P<0.05; fold-change >1.5) and pathway activation (Ingenuity) were confirmed using quantitative reverse transcriptase polymerase chain reaction and immunohistochemistry. Contributions of bone morphogenetic protein 4 and transforming growth factor (TGF)-β2 to differential gene expression were evaluated in vitro. Contributions of angiotensin II to differential pathway activation were examined in mice in vivo. A total of 2602 genes were differentially expressed between myxomatous and nonmyxomatous valves. Canonical TGF-β signaling was increased in MMVD because of increased ligand expression and derepression of SMA mothers against decapentaplegic 2/3 signaling and was confirmed with quantitative reverse transcriptase polymerase chain reaction and immunohistochemistry. Myxomatous valves demonstrated activation of canonical bone morphogenetic protein and Wnt/β-catenin signaling and upregulation of their common target runt-related transcription factor 2. Our data set provided transcriptional and immunohistochemical evidence for activated immune cell infiltration. In vitro treatment of mitral valve interstitial cells with TGF-β2 increased β-catenin signaling at mRNA and protein levels, suggesting interactions between TGF-β2 and Wnt signaling. In vivo infusion of mice with angiotensin II recaptured several changes in signaling pathways characteristic of human MMVD.

CONCLUSIONS

These data support a new disease framework whereby activation of TGF-β2, bone morphogenetic protein 4, Wnt/β-catenin, or immune signaling plays major roles in the pathogenesis of MMVD. We propose these pathways act in a context-dependent manner to drive phenotypic changes that fundamentally differ from those observed in aortic valve disease and open novel avenues guiding future research into the pathogenesis of MMVD.

COX2 inhibition reduces aortic valve calcification in vivo

OBJECTIVE

Calcific aortic valve disease (CAVD) is a significant cause of morbidity and mortality, which affects ≈1% of the US population and is characterized by calcific nodule formation and stenosis of the valve. Klotho-deficient mice were used to study the molecular mechanisms of CAVD as they develop robust aortic valve (AoV) calcification. Through microarray analysis of AoV tissues from klotho-deficient and wild-type mice, increased expression of the gene encoding cyclooxygenase 2 (COX2; Ptgs2) was found. COX2 activity contributes to bone differentiation and homeostasis, thus the contribution of COX2 activity to AoV calcification was assessed.

APPROACH AND RESULTS

In klotho-deficient mice, COX2 expression is increased throughout regions of valve calcification and is induced in the valvular interstitial cells before calcification formation. Similarly, COX2 expression is increased in human diseased AoVs. Treatment of cultured porcine aortic valvular interstitial cells with osteogenic media induces bone marker gene expression and calcification in vitro, which is blocked by inhibition of COX2 activity. In vivo, genetic loss of function of COX2 cyclooxygenase activity partially rescues AoV calcification in klotho-deficient mice. Moreover, pharmacological inhibition of COX2 activity in klotho-deficient mice via celecoxib-containing diet reduces AoV calcification and blocks osteogenic gene expression.

CONCLUSIONS

COX2 expression is upregulated in CAVD, and its activity contributes to osteogenic gene induction and valve calcification in vitro and in vivo.

Mechanisms of calcification in aortic valve disease: role of mechanokinetics and mechanodynamics

The aortic valve is highly responsive to cyclical and continuous mechanical forces, at the macroscopic and cellular levels. In this report, we delineate mechanokinetics (effects of mechanical inputs on the cells) and mechanodynamics (effects of cells and pathologic processes on the mechanics) of the aortic valve, with a particular focus on how mechanical inputs synergize with the inflammatory cytokine and other biomolecular signaling to contribute to the process of aortic valve calcification.