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Multi-walled carbon nanotubes translocate into the pleural cavity and induce visceral mesothelial proliferation in rats.

ABSTRACT: Multi-walled carbon nanotubes have a fibrous structure similar to asbestos and induce mesothelioma when injected into the peritoneal cavity. In the present study, we investigated whether carbon nanotubes administered into the lung through the trachea induce mesothelial lesions. Male F344 rats were treated with 0.5 mL of 500 ?g/mL suspensions of multi-walled carbon nanotubes or crocidolite five times over a 9-day period by intrapulmonary spraying. Pleural cavity lavage fluid, lung and chest wall were then collected. Multi-walled carbon nanotubes and crocidolite were found mainly in alveolar macrophages and mediastinal lymph nodes. Importantly, the fibers were also found in the cell pellets of the pleural cavity lavage, mostly in macrophages. Both multi-walled carbon nanotube and crocidolite treatment induced hyperplastic proliferative lesions of the visceral mesothelium, with their proliferating cell nuclear antigen indices approximately 10-fold that of the vehicle control. The hyperplastic lesions were associated with inflammatory cell infiltration and inflammation-induced fibrotic lesions of the pleural tissues. The fibers were not found in the mesothelial proliferative lesions themselves. In the pleural cavity, abundant inflammatory cell infiltration, mainly composed of macrophages, was observed. Conditioned cell culture media of macrophages treated with multi-walled carbon nanotubes and crocidolite and the supernatants of pleural cavity lavage fluid from the dosed rats increased mesothelial cell proliferation in vitro, suggesting that mesothelial proliferative lesions were induced by inflammatory events in the lung and pleural cavity and likely mediated by macrophages. In conclusion, intrapulmonary administration of multi-walled carbon nanotubes, like asbestos, induced mesothelial proliferation potentially associated with mesothelioma development.

SUBMITTER: Xu J

PROVIDER: S-EPMC7659236 | biostudies-literature | 2012 Dec

REPOSITORIES: biostudies-literature

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Multi-walled carbon nanotubes translocate into the pleural cavity and induce visceral mesothelial proliferation in rats.

Xu Jiegou J Futakuchi Mitsuru M Shimizu Hideo H Alexander David B DB Yanagihara Kazuyoshi K Fukamachi Katsumi K Suzui Masumi M Kanno Jun J Hirose Akihiko A Ogata Akio A Sakamoto Yoshimitsu Y Nakae Dai D Omori Toyonori T Tsuda Hiroyuki H

Cancer science 20121010 12

Multi-walled carbon nanotubes have a fibrous structure similar to asbestos and induce mesothelioma when injected into the peritoneal cavity. In the present study, we investigated whether carbon nanotubes administered into the lung through the trachea induce mesothelial lesions. Male F344 rats were treated with 0.5 mL of 500 μg/mL suspensions of multi-walled carbon nanotubes or crocidolite five times over a 9-day period by intrapulmonary spraying. Pleural cavity lavage fluid, lung and chest wall ...[more]

PMID: 22938569

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Project description:Pleural fibrosis is characterized by severe inflammation of the pleural space and pleural reorganization. Subsequent thickening of the visceral pleura contributes to lung stiffness and impaired lung function. Pleural mesothelial cells (PMCs) can become myofibroblasts via mesothelial-mesenchymal transition (MesoMT) and contribute to pleural organization, fibrosis, and rind formation. However, the mechanisms that underlie MesoMT remain unclear. Here, we investigated the role of myocardin in the induction of MesoMT. Transforming growth factor β (TGF-β) and thrombin induced MesoMT and markedly upregulated the expression of myocardin, but not myocardin-related transcription factor A (MRTF-A) or MRTF-B, in human PMCs (HPMCs). TGF-β stimulation notably induced the nuclear translocation of myocardin in HPMCs, whereas nuclear translocation of MRTF-A and MRTF-B was not observed. Several genes under the control of myocardin were upregulated in cells undergoing MesoMT, an effect that was accompanied by a dramatic cytoskeletal reorganization of HPMCs consistent with a migratory phenotype. Myocardin gene silencing blocked TGF-β- and thrombin-induced MesoMT. Although myocardin upregulation was blocked, MRTF-A and MRTF-B were unchanged. Myocardin, α-SMA, calponin, and smooth muscle myosin were notably upregulated in the thickened pleura of carbon black/bleomycin and empyema mouse models of fibrosing pleural injury. Similar results were observed in human nonspecific pleuritis. In a TGF-β mouse model of pleural fibrosis, PMC-specific knockout of myocardin protected against decrements in lung function. Further, TGF-β-induced pleural thickening was abolished by PMC-specific myocardin knockout, which was accompanied by a marked reduction of myocardin, calponin, and α-SMA expression compared with floxed-myocardin controls. These novel results show that myocardin participates in the development of MesoMT in HPMCs and contributes to the pathogenesis of pleural organization and fibrosis.

Project description:Multi-walled carbon nanotubes (MWCNTs) are among the most promising nanomaterials because of their physical and chemical properties. However, since they are biopersistent fiber-like materials which share similarities with asbestos, concerns have arisen about their health effects. With their various industrial usages, occupational exposure to MWCNTs may occur mainly by inhalation as these nanomaterials can get aerosolised. The number of toxicological studies on CNTs has steadily increased for the last decades. Different works showed that MWCNT exposure by inhalation or intratracheal instillation could lead to pulmonary toxicity, such as lung inflammation, genotoxicity, fibrosis or lung cancer (Kasai et al. 2015, Kasai et al. 2016, Porter et al. 2013, Suzui et al. 2016). To date, only one MWCNT (MWNT-7) has been classified as possibly carcinogen to human (Group 2B) while the others have not been as classifiable as to their carcinogenicity to humans (Group 3) because of the lack of data on their carcinogenic potential (IARC 2017). Because of the wide variety of CNTs with various length, diameter or functionalisation, additional effort is required to assess their pulmonary toxicity. As a complementary approach to conventional toxicological assays, the omics methods are useful technologies for the mechanistic understanding of the toxicological effects observed following exposure to chemicals and particulate matters. Importantly, they can also be used as predictive tools for identifying the mode of action of other particles with similar physical and chemical characteristics. These molecular approaches may also be used for the discovery of exposure markers or early markers of adverse effects, before the appearance of clinical signs of a disease (Rahman et al. 2017). Several studies assessed gene expression alteration following in vivo exposure to CNTs (Poulsen et al. 2015, Snyder-Talkington et al. 2013, Ellinger-Ziegelbauer and Pauluhn 2009). These omics approaches were used to identify genes and pathways modulated in response to exposure. However, there are still too few studies to assess the link between MWCNT physico-chemical properties, global gene or protein expression profiles, and long-term effects. In a previous study, we showed that inhalation of two pristine MWCNTs, the long and thick NM-401, and the short and thin NM-403, induced alveolar neutrophilic granulocyte influx, a hallmark of inflammation, which was proportional to the lung CNT BET surface deposited dose (Gate et al. 2019). However, due to their different physical and chemical properties, one could assume that these two CNTs may have diverse toxicological profiles, but the conventional toxicology approaches used in this early work were probably not sensitive enough to identify such differences. In order to gain additional insight about their toxicological properties, in the current study, we compare the alteration induced by the two MWCNTs on the transcriptome in the lung tissue and the proteome in the broncho-alveolar lavage fluid (BALF) after rat exposure by inhalation. The omics analyses were performed from 3 days up to 180 days.

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Multi-walled carbon nanotubes translocate into the pleural cavity and induce visceral mesothelial proliferation in rats.

Publications

Multi-walled carbon nanotubes translocate into the pleural cavity and induce visceral mesothelial proliferation in rats.

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