Transdifferentiation of endothelial cells to smooth muscle cells play an important role in vascular remodelling

Pulmonary artery remodelling it is a major feature of pulmonary hypertension (PH). It is characterised by cellular and structural changes of the pulmonary arteries causing higher pulmonar vascular resistance and right ventricular failure. Abnormal deposition of smooth muscle-like (SM-like) cells in normally non-muscular, small diameter vessels and a deregulated control of endothelial cells are considered pathological features of PH. The origin of the SM-like cells and the mechanisms underlying the development and progression of this remodelling process are not understood. Endothelial cells within the intima may migrate from their organised layer of cells and transition to mesenchymal or SM-like phenotype in a process called endothelial-mesenchymal transition (EnMT). Traditionally, Waddington's epigenetic landscape illustrates that fates of somatic cells are progressively determined to compulsorily follow a downhill differentiation pathway. EnMT induces the transformation of cells with stem cell traits, therefore contrasting Waddington's theory and confirming that cell fate seems to be far more flexible than previously thought. The prospect of therapeutic inhibition of EnMT to delay or prevent PH may represent a promising new treatment modality

Cigarette smoke challenges bone marrow mesenchymal stem cell capacities in guinea pig

BACKGROUND: Cigarette smoke (CS) is associated with lower numbers of circulating stem cells and might severely affect their mobilization, trafficking and homing. Our study was designed to demonstrate in an animal model of CS exposure whether CS affects the homing and functional capabilities of bone marrow-derived mesenchymal stem cells (BM-MSCs). METHODS: Guinea pigs (GP), exposed or sham-exposed to CS, were administered via tracheal instillation or by vascular administration with 2.5 × 106 BM-MSCs obtained from CS-exposed or sham-exposed animal donors. Twenty-four hours after cell administration, animals were sacrificed and cells were visualised into lung structures by optical microscopy. BM-MSCs from 8 healthy GP and from 8 GP exposed to CS for 1 month were isolated from the femur, cultured in vitro and assessed for their proliferation, migration, senescence, differentiation potential and chemokine gene expression profile. RESULTS: CS-exposed animals showed greater BM-MSCs lung infiltration than sham-exposed animals regardless of route of administration. The majority of BM-MSCs localized in the alveolar septa. BM-MSCs obtained from CS-exposed animals showed lower ability to engraft and lower proliferation and migration. In vitro, BM-MSCs exposed to CS extract showed a significant reduction of proliferative, cellular differentiation and migratory potential and an increase in cellular senescence in a dose dependent manner. CONCLUSION: Short-term CS exposure induces BM-MSCs dysfunction. Such dysfunction was observed in vivo, affecting the cell homing and proliferation capabilities of BM-MSCs in lungs exposed to CS and in vitro altering the rate of proliferation, senescence, differentiation and migration capacity. Additionally, CS induced a reduction in CXCL9 gene expression in the BM from CS-exposed animals underpinning a potential mechanistic action of bone marrow dysfunction

Imbalance between endothelial damage and repair capacity in chronic obstructive pulmonary disease

Background: Circulating endothelial microparticles (EMPs) and progenitor cells (PCs) are biological markers of endothelial function and endogenous repair capacity. The study was aimed to investigate whether COPD patients have an imbalance between EMPs to PCs compared to controls and to evaluate the effect of cigarette smoke on these circulating markers. Methods: Circulating EMPs and PCs were determined by flow cytometry in 27 nonsmokers, 20 smokers and 61 COPD patients with moderate to severe airflow obstruction. We compared total EMPs (CD31+CD42b-), apoptotic if they co-expressed Annexin-V+ or activated if they co-expressed CD62E+, circulating PCs (CD34+CD133+CD45+) and the EMPs/PCs ratio between groups. Results: COPD patients presented increased levels of total and apoptotic circulating EMPs, and an increased EMPs/PCs ratio, compared with nonsmokers. Women had less circulating PCs than men through all groups and those with COPD showed lower levels of PCs than both control groups. In smokers, circulating EMPs and PCs did not differ from nonsmokers, being the EMPs/PCs ratio in an intermediate position between COPD and nonsmokers. Conclusions: We conclude that COPD patients present an imbalance between endothelial damage and repair capacity that might explain the frequent concurrence of cardiovascular disorders. Factors related to the disease itself and gender, rather than cigarette smoking, may account for this imbalance

Slug is increased in vascular remodeling and induces a smooth muscle cell proliferative phenotype

Objective Previous studies have confirmed Slug as a key player in regulating phenotypic changes in several cell models, however, its role in smooth muscle cells (SMC) has never been assessed. The purpose of this study was to evaluate the expression of Slug during the phenotypic switch of SMC in vitro and throughout the development of vascular remodeling. Methods and Results Slug expression was decreased during both cell-to-cell contact and TGFβ1 induced SMC differentiation. Tumor necrosis factor-α (TNFα), a known inductor of a proliferative/dedifferentiated SMC phenotype, induces the expression of Slug in SMC. Slug knockdown blocked TNFα-induced SMC phenotypic change and significantly reduced both SMC proliferation and migration, while its overexpression blocked the TGFβ1-induced SMC differentiation and induced proliferation and migration. Genome-wide transcriptomic analysis showed that in SMC, Slug knockdown induced changes mainly in genes related to proliferation and migration, indicating that Slug controls these processes in SMC. Notably, Slug expression was significantly up-regulated in lungs of mice using a model of pulmonary hypertension-related vascular remodeling. Highly remodeled human pulmonary arteries also showed an increase of Slug expression compared to less remodeled arteries. Conclusions Slug emerges as a key transcription factor driving SMC towards a proliferative phenotype. The increased Slug expression observed in vivo in highly remodeled arteries of mice and human suggests a role of Slug in the pathogenesis of pulmonary vascular diseases

MicroRNA Dysregulation in Pulmonary Arteries from COPD: Relationships with Vascular Remodeling

Pulmonary vascular remodeling is an angiogenic-related process involving changes in smooth muscle cell (SMC) homeostasis, which is frequently observed in chronic obstructive pulmonary disease (COPD). MicroRNAs (miRNAs) are small, noncoding RNAs that regulate mRNA expression levels of many genes, leading to the manifestation of cell identity and specific cellular phenotypes. Here, we evaluate the miRNA expression profiles of pulmonary arteries (PAs) of patients with COPD and its relationship with the regulation of SMC phenotypic change. miRNA expression profiles from PAs of 12 patients with COPD, 9 smokers with normal lung function (SK), and 7 nonsmokers (NS) were analyzed using TaqMan Low-Density Arrays. In patients with COPD, expression levels of miR-98, miR-139-5p, miR-146b-5p, and miR-451 were upregulated, as compared with NS. In contrast, miR-197, miR-204, miR-485-3p, and miR-627 were downregulated. miRNA-197 expression correlated with both airflow obstruction and PA intimal enlargement. In an in vitro model of SMC differentiation, miR-197 expression was associated with an SMC contractile phenotype. miR-197 inhibition blocked the acquisition of contractile markers in SMCs and promoted a proliferative/migratory phenotype measured by both cell cycle analysis and wound-healing assay. Using luciferase assays, Western blot, and quantitative PCR, we confirmed that miR-197 targets the transcription factor E2F1. In PAs from patients with COPD, levels of E2F1 were increased as compared with NS. In PAs of patients with COPD, remodeling of the vessel wall is associated with downregulation of miR-197, which regulates SMC phenotype. The effect of miR-197 on PAs might be mediated, at least in part, by the key proproliferative factor, E2F1

Mecanismes moleculars i expressió de miRNAs durant la diferenciació de la cèl·lula muscular llisa en el remodelat vascular

[cat] En la malaltia pulmonar obstructiva crònica (MPOC), el remodelat vascular, és un dels trets més destacats. Aquest procés és caracteritza per una proliferació desmesurada de cèl·lules musculars llises (SMC) pobrament diferenciades, i un increment de la deposició de components de matriu cel·lular com la fibronectina, elastina o col·lagen afavorint un engruiximent de la íntima arterial. La SMC s’encarrega principalment de la contracció del vas i s’ha demostrat que té capacitat de canviar el seu fenotip segons determinats estímuls com la hipòxia, inflamació etc. Aquest tipus cel·lular pot passar d’un fenotip contràctil i diferenciat a un fenotip sintètic, proliferatiu i dediferenciat característic del remodelat vascular. Aquestes SMC dediferenciades poden tenir diferents orígens com els miofibroblasts, el fibroblasts residents de l’adventícia, una dediferenciació de la SMC de la media, progenitores circulants o residents o a partir de cèl·lules endotelials. Els microRNAs (miRNAs) són petits ARNs no-codificants que regulen l’expressió gènica, inhibint-la. L’estudi de determinats factors de transcripció relacionats amb processos de diferenciació cel·lular o bé la de reguladors post- transcripcionals com els miRNAs poden ser d’interès per establir noves dianes terapèutiques en el remodelat vascular associat a la MPOC. En aquesta tesi doctoral hem demostrat que el factor de transcripció SLUG, un factor íntimament lligat a processos de diferenciació cel·lular, modula la proliferació y la diferenciació de la SMC promovent el fenotip sintètic i migratori cap a la íntima arterial. També hem demostrat que existeix un perfil específic d’expressió de miRNAs a les artèries pulmonars dels pacients amb MPOC. De tots ells, el miR-197 regula l’expressió del factor pro-proliferatiu E2F1, que promourà l’increment de la proliferació de les SMC i afavorint el remodelat vascular. S’han descrit doncs, dues noves dianes relacionades amb la transició fenotípica de la SMC durant l’engruiximent intimal. [[eng] Vascular remodelling is one of the most outstanding features in chronic obstructive pulmonary disease (COPD). This process is characterized by an excessive proliferation of poorly differentiated smooth muscle cells (SMC) and increased deposition of cellular matrix components such as fibronectin, collagen and elastin promoting an intimal enlargement. The SMC is the mainly responsible of vessel contraction and it has been demonstrated the ability to change its phenotype from a contractile, differentiated phenotype to a synthetic or dediferentiated phenotype according to certain stimuli such as hypoxia, inflammation etc. These dedifferentiated SMC may have different origins in vascular remodelling as myofibroblasts, resident adventitial fibroblast, SMC from media layer, circulating or resident progenitors cells and from endothelial cells. MicroRNAs (miRNAs) are small non-coding RNAs that inhibit gene expression. The study of certain transcription factors strongly related to cell differentiation processes or post-transcriptional regulators such as miRNAs might play a key role in vascular remodelling associated to COPD and help to establish new therapeutic targets. In this thesis, we have shown that the transcription factor SLUG, a factor closely linked to processes of cell differentiation, modulates the proliferation and differentiation of SMC promoting migration to intima layer. We have also shown that there is a miRNAs specific expression profile in pulmonary arteries of COPD patients. Among all of this, miR-197 regulates the expression of pro-proliferative factor E2F1, which will promote the increase of SMC proliferation and the intimal thickening. In this work it has been described two new targets related to proliferation and SMC phenotypic transition during intimal thickening

Transdifferentiation of endothelial cells to smooth muscle cells play an important role in vascular remodelling

Pulmonary artery remodelling it is a major feature of pulmonary hypertension (PH). It is characterised by cellular and structural changes of the pulmonary arteries causing higher pulmonar vascular resistance and right ventricular failure. Abnormal deposition of smooth muscle-like (SM-like) cells in normally non-muscular, small diameter vessels and a deregulated control of endothelial cells are considered pathological features of PH. The origin of the SM-like cells and the mechanisms underlying the development and progression of this remodelling process are not understood. Endothelial cells within the intima may migrate from their organised layer of cells and transition to mesenchymal or SM-like phenotype in a process called endothelial-mesenchymal transition (EnMT). Traditionally, Waddington's epigenetic landscape illustrates that fates of somatic cells are progressively determined to compulsorily follow a downhill differentiation pathway. EnMT induces the transformation of cells with stem cell traits, therefore contrasting Waddington's theory and confirming that cell fate seems to be far more flexible than previously thought. The prospect of therapeutic inhibition of EnMT to delay or prevent PH may represent a promising new treatment modality

Slug Is Increased in Vascular Remodeling and Induces a Smooth Muscle Cell Proliferative Phenotype.

Previous studies have confirmed Slug as a key player in regulating phenotypic changes in several cell models, however, its role in smooth muscle cells (SMC) has never been assessed. The purpose of this study was to evaluate the expression of Slug during the phenotypic switch of SMC in vitro and throughout the development of vascular remodeling.Slug expression was decreased during both cell-to-cell contact and TGFβ1 induced SMC differentiation. Tumor necrosis factor-α (TNFα), a known inductor of a proliferative/dedifferentiated SMC phenotype, induces the expression of Slug in SMC. Slug knockdown blocked TNFα-induced SMC phenotypic change and significantly reduced both SMC proliferation and migration, while its overexpression blocked the TGFβ1-induced SMC differentiation and induced proliferation and migration. Genome-wide transcriptomic analysis showed that in SMC, Slug knockdown induced changes mainly in genes related to proliferation and migration, indicating that Slug controls these processes in SMC. Notably, Slug expression was significantly up-regulated in lungs of mice using a model of pulmonary hypertension-related vascular remodeling. Highly remodeled human pulmonary arteries also showed an increase of Slug expression compared to less remodeled arteries.Slug emerges as a key transcription factor driving SMC towards a proliferative phenotype. The increased Slug expression observed in vivo in highly remodeled arteries of mice and human suggests a role of Slug in the pathogenesis of pulmonary vascular diseases

Correction: Slug Is Increased in Vascular Remodeling and Induces a Smooth Muscle Cell Proliferative Phenotype.

[This corrects the article DOI: 10.1371/journal.pone.0159460.]