[Show abstract][Hide abstract] ABSTRACT: -Cells exhibiting dysregulated growth may express telomerase reverse transcriptase (TERT), whose dual function consists in maintaining telomere length, in association with the RNA template molecule TERC and controlling cell growth. Here, we investigated lung TERT in human and experimental pulmonary hypertension (PH) and its role in controlling pulmonary artery-smooth muscle cell (PA-SMC) proliferation.
-Marked TERT expression and/or activity were found in lungs from patients with idiopathic PH and from mice with PH induced by hypoxia or serotonin-transporter overexpression (SM22-5HTT+ mice), chiefly within PA-SMCs. In cultured mouse PA-SMCs, TERT was expressed upon growth stimulation by serum. The TERT inhibitor imetelstat and the TERT activator TA65 abrogated and stimulated PA-SMC growth, respectively. PA-SMCs from PH mice showed a heightened proliferative phenotype associated with increased TERT expression, which was suppressed by imetelstat treatment. TERC(-/-) mice at generation 2 (G2) and TERT(-/-) mice at G2, G3, and G4 developed less severe PH than did wild-type mice exposed to chronic hypoxia, with less distal pulmonary-artery muscularization and fewer Ki67-stained proliferating PA-SMCs. Telomere length differed between TERC(-/-) and TERT(-/-) mice, whereas PH severity was similar in the two strains and across generations. Chronic imetelstat treatment reduced hypoxia-induced PH in wild-type mice or partially reversed established PH in SM22-5HTT+ mice, while simultaneously decreasing TERT expression. Opposite effects occurred in mice treated with TA65.
-Telomerase exerts telomere-independent effects on PA-SMC growth in PH and may constitute a treatment target for PH.
[Show abstract][Hide abstract] ABSTRACT: Manufactured nanomaterials (MNMs) have the potential to improve everyday life as they can be utilised in numerous medical applications and day-to-day consumer products. However, this increased use has led to concerns about the potential environmental and human health impacts. The protein p53 is a key transcription factor implicated in cellular defence and reparative responses to various stress factors. Additionally, p53 has been implicated in cellular responses following exposure to some MNMs. Here, the role of the MNM mediated p53 induction and activation and its downstream effects following exposure to five well-characterised materials [namely two types of TiO2, two carbon black (CB), and one single-walled carbon nanotube (SWCNT)] were investigated. MNM internalisation, cellular viability, p53 protein induction and activation, oxidative stress, inflammation and apoptosis were measured in murine cell line and primary pulmonary macrophage models. It was observed that p53 was implicated in the biological responses to MNMs, with oxidative stress associated with p53 activation (only following exposure to the SWCNT). We demonstrate that p53 acted as an antioxidant and anti-inflammatory in macrophage responses to SWCNT and CB NMs. However, p53 was neither involved in MNM-induced cellular toxicity, nor in the apoptosis induced by these MNMs. Moreover, the physicochemical characteristics of MNMs seemed to influence their biological effects-SWCNT the materials with the largest surface area and a fibrous shape were the most cytotoxic in this study and were capable of the induction and activation of p53.
Archive für Toxikologie 08/2014; · 5.08 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Although major concerns exist regarding the potential consequences of human exposure to nanoparticles (NP), no human toxicological data is currently available. To address this issue, we took welders, who present various adverse respiratory outcomes, as a model population of occupational exposure to NP.The aim of this study was to evaluate if welding fume-issued NP could be responsible, at least partially, in the lung alterations observed in welders.
Particle and Fibre Toxicology 05/2014; 11(1):23. · 6.99 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Abstract Engineered nanoparticles are increasingly used in medical applications and day-to-day consumer products, leading to concerns about the potential environmental and human health impacts. Silver nanoparticles are particularly prevalent because of their use as anti-bacterial agents in many commonly available products. Nanoparticles (NPs) are believed to accumulate, often preferentially, in the liver. This study therefore investigates the effect of a silver NP (20 nm) on the liver, and in particular, the role of Kupffer cells (KCs; resident liver macrophages) in the overall inflammatory response in the organ. Cytokine expression in the normal liver was measured in terms of IL2, IL4, TNF-α, IFN-γ and IL10 released from the organ with significant up-regulation of TNF-α and IL10 being observed. For livers in which the KC population was specifically targeted and destroyed this cytokine increase was significantly decreased in comparison to the normal tissue. IL10 was secreted at approximately three times the concentration of TNF-α in all the test cases. The high levels of IL10 released from the normal tissue in comparison to the KC depleted livers suggest that the cytokine may help to protect against a pro-inflammatory response to these Ag NPs. This may indicate a potentially important role for KCs in the anti-inflammatory response and suggests that tolerance to the Ag NPs is favoured over a fully activated immune response. In addition, albumin production was measured as an indicator of hepatic function. It was noted that the liver function was unaffected by the Ag NPs.
[Show abstract][Hide abstract] ABSTRACT: Carbon monoxide-releasing molecules (CORMs) represent a pharmacological alternative to CO gas inhalation. Here, we questioned whether CORM-3, a well-characterized water-soluble CORM, could prevent and reverse pulmonary hypertension (PH) in chronically hypoxic mice and in smooth muscle promoter 22 serotonin transporter mice overexpressing the serotonin transporter in smooth muscle cells (SMCs).
Treatment with CORM-3 (50 mg/kg per day once daily) for 3 weeks prevented PH, right ventricular hypertrophy, and distal pulmonary artery muscularization in mice exposed to chronic hypoxia and partially reversed PH in smooth muscle promoter 22 serotonin transporter mice by reducing Ki67 dividing pulmonary artery SMCs (PA-SMCs). In these models, CORM-3 markedly increased lung p21 mRNA and protein levels and p21-stained PA-SMCs. These effects contrasted with the transient pulmonary vasodilatation and rise in lung cGMP levels induced by a single injection of CORM-3 in mice exposed to acute hypoxia. Studies in cultured rat PA-SMCs revealed that the inhibitory effects of CORM-3 on cell growth were independent of cGMP formation but associated with increased p21 mRNA and protein levels. Protection against PH by CORM-3 required increased lung expression of p21, as indicated by the inability of CORM-3 to prevent chronic hypoxia-induced PH in p21-deficient mice and to alter the growth of PA-SMCs derived from p21-deficient mice. CORM-3-induced p21 overexpression was linked to p53 activation as assessed by the inability of CORM-3 to prevent PH and induce p21 expression in p53-deficient mice and in PA-SMCs derived from p53-deficient mice.
CORM-3 inhibits pulmonary vascular remodeling via p21, which may represent a useful approach for treating PH.
Arteriosclerosis Thrombosis and Vascular Biology 12/2013; · 6.34 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: In the last few years questions have been raised regarding the potential toxicity of carbon nanotubes (CNT) to human and environment. It is believed that the physico-chemical characteristics of these materials are key determinants of CNT interaction with living organisms, and hence determine their toxicity. As for other nanomaterials, the most important of these characteristics are the length, diameter, surface area, tendency to agglomerate, bio-durability, presence and nature of catalyst residues as well as chemical functionalization of the CNT. This review highlights the recent advancements in the understanding of the CNT properties which are essential in determining CNT toxicity. Hence the focus is on CNT dimensions, surface properties, bio-durability and corona formation as these fields have evolved greatly in recent years. A deeper understanding of these events and their underlying mechanisms could provide a molecular explanation of the biological and physiological responses following CNT administration and therefore help in the development of safe by design materials.
Advanced drug delivery reviews 08/2013; · 11.96 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Carbon nanotubes (CNT) are a family of materials featuring a large range of length, diameter, numbers of walls and, quite often metallic impurities coming from the catalyst used for their synthesis. They exhibit unique physical properties, which have already led to an extensive development of CNT for numerous applications. Because of this development and the resulting potential increase of human exposure, an important body of literature has been published with the aim to evaluate the health impact of CNT. However, despite evidences of uptake and long-term persistence of CNT within macrophages and the central role of those cells in the CNT-induced pulmonary inflammatory response, a limited amount of data is available so far on the CNT fate inside macrophages. Therefore, the overall aim of our study was to investigate the fate of pristine single walled CNT (SWCNT) after their internalization by macrophages.
To achieve our aim, we used a broad range of techniques that aimed at getting a comprehensive characterization of the SWCNT and their catalyst residues before and after exposure of murine macrophages: X-ray diffraction (XRD), High Resolution (HR) Transmission Electron Microscopy (TEM), High Angle Annular Dark Field-Scanning TEM (HAADF-STEM) coupled to Electron Energy Loss Spectroscopy (EELS), as well as micro-X-ray fluorescence mapping (muXRF), using synchrotron radiation.
We showed 1) the rapid detachment of part of the iron nanoparticles initially attached to SWCNT which appeared as free iron nanoparticles in the cytoplasm and nucleus of CNT-exposed murine macrophages, and 2) that blockade of intracellular lysosomal acidification prevented iron nanoparticles detachment from CNT bundles and protected cells from CNT downstream toxicity.
The present results, while obtained with pristine SWCNT, could likely be extended to other catalyst-containing nanomaterials and surely open new ways in the interpretation and understanding of CNT toxicity.
Particle and Fibre Toxicology 06/2013; 10(1):24. · 6.99 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: ABSTRACT The mucociliary system, consisting of mucus-secreting goblet cells and ciliated cells, generates a constant overturning layer of protective mucus that lines the airway epithelium. Mucus hypersecretion and the pathophysiological changes associated are hallmarks of many pulmonary diseases including asthma, chronic obstructive pulmonary disease, and cystic fibrosis. Excessive mucus production leads to airway obstruction and, because there is currently no effective treatment, contributes to morbidity and mortality of many patients. Goblet cell differentiation and mucus production are subject to extensive control. An emerging concept is that not all goblet cells are phenotypically identical suggesting that specific molecular pathways orchestrate mucin overproduction. This paper attempts to describe the cellular and molecular mechanisms governing the differentiation of goblet cells in pulmonary diseases, a prerequisite for the development of new therapeutic agents.
Experimental Lung Research 05/2013; · 1.75 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Aims: Heme oxygenase-1 (HO-1, HMOX1) can prevent tumor initiation while in various tumors it has been demonstrated to promote growth, angiogenesis and metastasis. Here we investigated whether HMOX1 can modulate microRNAs and regulate human non-small cell lung cancer (NSCLC) development. Results: Stable HMOX1 overexpression in NSCLC NCI-H292 cells upregulated tumor suppressive microRNAs, whereas significantly diminished expression of oncomirs and angiomirs. The most potently downregulated was miR-378. HMOX1 also upregulated p53, downregulated Ang-1 and MUC5AC, reduced proliferation, migration and diminished angiogenic potential. Carbon monoxide was a mediator of HMOX1 effects on proliferation, migration and miR-378 expression. In contrast, stable miR-378 overexpression decreased HMOX1 and p53, while enhanced expression of MUC5AC, VEGF, IL-8 and Ang-1 and consequently increased proliferation, migration and stimulation of endothelial cells. Adenoviral delivery of HMOX1 reversed miR-378 effect on proliferation and migration of cancer cells. In vivo, HMOX1 overexpressing tumors were smaller, less vascularized and oxygenated and less metastatic. Overexpression of miR-378 exerted opposite effects. Accordingly, in patients with NSCLC, HMOX1 expression was lower in metastases to lymph nodes than in primary tumors. Innovation and Conclusion: In vitro and in vivo data indicate that the interplay between HMOX1 and miR-378 significantly modulates NSCLC progression and angiogenesis, suggesting miR-378 as a new therapeutic target. Rebound Track: This work was rejected during standard peer review and rescued by Rebound Peer Review (Antoxid Redox Signal 16: 293-296, 2012) with the following serving as open reviewers: James F. George, Mahin D. Maines, Justin C. Mason and Yasufumi Sato.
[Show abstract][Hide abstract] ABSTRACT: BACKGROUND: Induction of cellular senescence through activation of the p53 tumor suppressor protein is a new option for treating proliferative disorders. Nutlins prevent the ubiquitin ligase MDM2 (murine double minute 2), a negative p53 regulator, from interacting with p53. We hypothesized that cell senescence induced by Nutlin-3a exerted therapeutic effects in pulmonary hypertension (PH) by limiting the proliferation of pulmonary-artery smooth muscle cells (PA-SMCs). METHODS AND RESULTS: Nutlin-3a treatment of cultured human PA-SMCs resulted in cell growth arrest with the induction of senescence but not apoptosis; increased phosphorylated p53 protein levels; and expression of p53 target genes including p21, Bax, BTG2, and MDM2. Daily intraperitoneal Nutlin-3a treatment for 3 weeks dose-dependently reduced PH, right ventricular hypertrophy, and distal pulmonary artery muscularization in mice exposed to chronic hypoxia or SU5416/hypoxia. Nutlin-3a treatment also partially reversed PH in chronically hypoxic or transgenic mice overexpressing the serotonin-transporter in SMCs (SM22-5HTT+ mice). In these mouse models of PH, Nutlin-3a markedly increased senescent p21-stained PA-SMCs; lung p53, p21, and MDM2 protein levels; and p21, Bax, PUMA, BTG2, and MDM2 mRNA levels; but induced only minor changes in control mice without PH. Marked MDM2 immunostaining was seen in both mouse and human remodeled pulmonary vessels, supporting the use of Nutlins as a PH-targeted therapy. PH prevention or reversal by Nutlin-3a required lung p53 stabilization and increased p21 expression, as indicated by the absence of Nutlin-3a effects in hypoxia-exposed p53(-/-) and p21(-/-) mice. CONCLUSIONS: Nutlin-3a may hold promise as a prosenescence treatment targeting PA-SMCs in PH.
[Show abstract][Hide abstract] ABSTRACT: Rationale. Chronic obstructive pulmonary disease (COPD) is associated with lung fibroblast senescence, a process characterized by the irreversible loss of replicative capacity associated with the secretion of inflammatory mediators. However, the mechanisms of this phenomenon remain poorly defined. Objectives. The aim of this study was to analyze the role of prostaglandin E2 (PGE2), a prostaglandin known to be increased in COPD lung fibroblasts, in inducing senescence and related inflammation in vitro in lung fibroblasts and in vivo in mice. Methods and main results. Lung fibroblasts from COPD patients exhibited higher expression of PGE2 receptors EP2 and EP4 as compared to non-smoker and smoker controls. Compared to both non-smoker and smoker controls, during long-term culture, COPD fibroblasts displayed increased senescent markers (increased senescence associated-β galactosidase activity, p16 and p53 expression and lower proliferative capacity), and an increased PGE2, IL6, IL8, GRO, CX3CL1 and MMP2 protein and COX2 and mPGES-1 mRNA expression. Using in vitro pharmacological approaches and in vivo experiments in wild type and p53 -/- mice we demonstrated that PGE2 produced by senescent COPD fibroblasts is responsible of the increased senescence and related inflammation. PGE2 acts either paracrinally or autocrinally via a pathway involving EP2 and EP4 prostaglandin receptors, COX2-dependent reactive oxygen species production and signaling, and consecutive p53 activation. Conclusion. PGE2 is a critical component of an amplifying and self-perpetuating circle inducing senescence and inflammation in COPD fibroblasts. Modulating the described PGE2 signaling pathway could provide new basis to dampen senescence and senescence-associated inflammation in COPD.
American Journal of Respiratory and Critical Care Medicine 01/2013; · 11.04 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Exposure to titanium dioxide (TiO2) nanoparticles (NP) can be associated to lung remodeling, but the underlying mechanisms are yet unknown. Matrix metalloprotease (MMP)-1 is an important actor of matrix homeostasis and could therefore participate in TiO2 NP effects. Our aim was to evaluate the effects of TiO2 NP on MMP-1 expression and activity in lung pulmonary fibroblasts, in addition to understand the underlying mechanisms and assess the importance of the physicochemical characteristics of the particles in these effects. Human pulmonary fibroblasts (MRC-5 cell line and primary cells) were exposed to 10 or 100 µg/cm² TiO2 (2 anatases, 2 anatase/rutile mix, 1 rutile NP, and 1 micrometric), and carbon black (CB) NP for 6 to 48h. We examined cell viability, MMP-1 expression and activity, as well as the implication of oxidative stress, transforming growth factor (TGF)-β, extracellular MMP inducer (EMMPRIN) and interleukin (IL)-1β in MMP-1 expression. All TiO2 NP induce MMP-1 (mRNA and protein expression), repression of procollagen-1 and α-actin expression, but only the 2 anatase/rutile mix induced MMP-1 activity. Micrometric TiO2 had smaller effects than TiO2 NP, and CB NP didn't induce MMP-1. MMP-1 induction by TiO2 NP was not related to TGF-ß, oxidative stress or EMPRIN expression, but was related to IL-1ß expression, which partly drives MMP-1 induction by 2 TiO2 NP (1 anatase/rutile mix and the rutile one). Taken together, our results show that TiO2 NP are potent inducers and regulators of MMP-1 expression and activity, partly via an IL-1β-dependent mechanism. This may explain TiO2 lung remodeling effects.
American Journal of Respiratory Cell and Molecular Biology 12/2012; · 4.15 Impact Factor