Assessment of the toxicity and carcinogenicity of double-walled carbon nanotubes in the rat lung after intratracheal instillation: a two-year study

Dina Mourad Saleh; Shengyong Luo; Omnia Hosny Mohamed Ahmed; David B Alexander; William T Alexander; Sivagami Gunasekaran; Ahmed M El-Gazzar; Mohamed Abdelgied; Takamasa Numano; Hiroshi Takase; Makoto Ohnishi; Susumu Tomono; Randa Hussein Abd El Hady; Katsumi Fukamachi; Jun Kanno; Akihiko Hirose; Jiegou Xu; Shugo Suzuki; Aya Naiki-Ito; Satoru Takahashi; Hiroyuki Tsuda

doi:10.1186/s12989-022-00469-8

Assessment of the toxicity and carcinogenicity of double-walled carbon nanotubes in the rat lung after intratracheal instillation: a two-year study

Part Fibre Toxicol. 2022 Apr 22;19(1):30. doi: 10.1186/s12989-022-00469-8.

Authors

Dina Mourad Saleh^{1

2

3}, Shengyong Luo⁴, Omnia Hosny Mohamed Ahmed^{1

2

5}, David B Alexander⁶, William T Alexander¹, Sivagami Gunasekaran^{1

2}, Ahmed M El-Gazzar⁷, Mohamed Abdelgied^{8

9}, Takamasa Numano¹, Hiroshi Takase¹⁰, Makoto Ohnishi¹¹, Susumu Tomono¹², Randa Hussein Abd El Hady³, Katsumi Fukamachi¹³, Jun Kanno¹⁴, Akihiko Hirose¹⁴, Jiegou Xu^{1

15}, Shugo Suzuki¹⁶, Aya Naiki-Ito², Satoru Takahashi², Hiroyuki Tsuda¹⁷

Affiliations

¹ Nanotoxicology Lab Project, Nagoya City University, 3-1 Tanabe-Dohri, Mizuho-ku, Nagoya, 467-8603, Japan.
² Department of Experimental Pathology and Tumor Biology, Graduate School of Medical Sciences, Nagoya City University, Nagoya, Japan.
³ Department of Forensic Medicine and Clinical Toxicology, Faculty of Medicine, Assuit University, Assuit, Egypt.
⁴ College of Basic Medical Sciences, Anhui Medical University, Hefei, China.
⁵ Department of Forensic Medicine and Clinical Toxicology, Faculty of Medicine, Aswan University, Aswan, Egypt.
⁶ Nanotoxicology Lab Project, Nagoya City University, 3-1 Tanabe-Dohri, Mizuho-ku, Nagoya, 467-8603, Japan. dalexand@phar.nagoya-cu.ac.jp.
⁷ Department of Forensic Medicine and Toxicology, Faculty of Veterinary Medicine, Alexandria University, Alexandria, Egypt.
⁸ Department of Forensic Medicine and Toxicology, Faculty of Veterinary Medicine, Beni-Suef University, Beni-Suef, Egypt.
⁹ Department of Pediatrics and Human Development, Michigan State University, Michigan, USA.
¹⁰ Core Laboratory, Graduate School of Medicine, Nagoya City University, Nagoya, Japan.
¹¹ Japan Industrial Safety and Health Association, Japan Bioassay Research Center, Hadano, Kanagawa, Japan.
¹² Department of Microbiology and Immunology, Aichi Medical University School of Medicine, Nagakute, Japan.
¹³ Department of Neurotoxicology, Graduate School of Medical Sciences, Nagoya City University, Nagoya, Japan.
¹⁴ National Institute Hygienic Sciences, Kawasaki, Japan.
¹⁵ Department of Immunology, School of Basic Medical Sciences, Anhui Medical University, Hefei, China.
¹⁶ Department of Molecular Pathology, Osaka Metropolitan University Graduate School of Medicine, Osaka, Japan.
¹⁷ Nanotoxicology Lab Project, Nagoya City University, 3-1 Tanabe-Dohri, Mizuho-ku, Nagoya, 467-8603, Japan. htsuda@phar.nagoya-cu.ac.jp.

Abstract

Background: Considering the expanding industrial applications of carbon nanotubes (CNTs), safety assessment of these materials is far less than needed. Very few long-term in vivo studies have been carried out. This is the first 2-year in vivo study to assess the effects of double walled carbon nanotubes (DWCNTs) in the lung and pleura of rats after pulmonary exposure.

Methods: Rats were divided into six groups: untreated, Vehicle, 3 DWCNT groups (0.12 mg/rat, 0.25 mg/rat and 0.5 mg/rat), and MWCNT-7 (0.5 mg/rat). The test materials were administrated by intratracheal-intrapulmonary spraying (TIPS) every other day for 15 days. Rats were observed without further treatment until sacrifice.

Results: DWCNT were biopersistent in the rat lung and induced marked pulmonary inflammation with a significant increase in macrophage count and levels of the chemotactic cytokines CCL2 and CCL3. In addition, the 0.5 mg DWCNT treated rats had significantly higher pulmonary collagen deposition compared to the vehicle controls. The development of carcinomas in the lungs of rats treated with 0.5 mg DWCNT (4/24) was not quite statistically higher (p = 0.0502) than the vehicle control group (0/25), however, the overall incidence of lung tumor development, bronchiolo-alveolar adenoma and bronchiolo-alveolar carcinoma combined, in the lungs of rats treated with 0.5 mg DWCNT (7/24) was statistically higher (p < 0.05) than the vehicle control group (1/25). Notably, two of the rats treated with DWCNT, one in the 0.25 mg group and one in the 0.5 mg group, developed pleural mesotheliomas. However, both of these lesions developed in the visceral pleura, and unlike the rats administered MWCNT-7, rats administered DWCNT did not have elevated levels of HMGB1 in their pleural lavage fluids. This indicates that the mechanism by which the mesotheliomas that developed in the DWCNT treated rats is not relevant to humans.

Conclusions: Our results demonstrate that the DWCNT fibers we tested are biopersistent in the rat lung and induce chronic inflammation. Rats treated with 0.5 mg DWCNT developed pleural fibrosis and lung tumors. These findings demonstrate that the possibility that at least some types of DWCNTs are fibrogenic and tumorigenic cannot be ignored.

Keywords: Carcinogenicity; Double walled carbon nanotubes; Rats; Toxicity; Two-year study.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Animals
Inhalation Exposure / adverse effects
Lung
Lung Neoplasms* / chemically induced
Lung Neoplasms* / pathology
Mesothelioma* / pathology
Nanotubes, Carbon* / toxicity
Pleura
Rats

Substances

Nanotubes, Carbon