Genetic instability of lung induced by carbon black nanoparticles is related with Plk1 signals changes.

As a possible carcinogen, carbon black has threatened public health. However, the evidences are insufficient and the mechanism of carcinogenesis is still not specified. Thirty rats were randomly divided into 3 groups, namely 0, 5 and 30 mg/m3 Carbon Black nanoparticles (CBNPs) groups, respectively. Rats were treated with CBNPs by nose-only inhalation for 28 days, 6 h/day. The human bronchial epithelial (16HBE) cells were treated with 0, 50, 100 and 200 µg/mL CBNPs for 24 h. Polo-like kinase 1 (PLK1) overexpression cell line was established by pcDNA3.1-PLK1 stable transfection. Our results showed that CBNPs exposure could induce DNA damage and genetic changes as well as apoptosis in vivo and in vitro. The DNA repair ability increased after CBNPs exposure. Cell cycle process was retarded at the G2/M phases in 16HBE cells after CBNPs treatment. The PLK1, ChK2 GADD45α and XRCC1 expression levels changed in rat lung and 16HBE cells after CBNPs treatment. Compared with NC 16HBE cells, DNA damage and repair, numbers of apoptotic cells and micronucleus (MN) rates, as well as the ChK2, GADD45α, XRCC1 expression levels decreased, whereas cytokinesis block proliferation index (CBPI) and replicative index (RI) increase in PLK overexpression (PLK+/+) cells after CBNPs treatment. This study highlighted that PLK1 related with the genetic toxicity of CBNPs in vitro and in vivo. Our results provided evidences supporting reclassification of carbon black as a human possible carcinogen.

Carbon black nanoparticles induce pulmonary fibrosis through NLRP3 inflammasome pathway modulated by miR-96 targeted FOXO3a.

Carbon black nanoparticle (CBNP) is a core constituent of air pollutants like fine particulate matter (PM2.5) as well as a common manufactural material. It was proved to pose adverse effects on lung function and even provoke pulmonary fibrosis. However, the underlying mechanisms of CBNPs-induced pulmonary fibrosis remain unclear. The present study aimed to investigate the mechanism of fibrotic effects caused by CBNPs in rat lung and human bronchial epithelial (16HBE) cells. Forty-nine male rats were randomly subjected to 7 groups, means the 14-day exposure group (30 mg/m3), the 28-day exposure groups (5 mg/m3 and 30 mg/m3), the 90-day exposure group (30 mg/m3) and their respective controls. Rats were nose-only-inhaled CBNPs. 16HBE cells were treated with 0, 50, 100 and 200 µg/mL CBNPs respectively for 24 h. Besides, Forkhead transcription factor class O (FOXO)3a and miR-96 overexpression or suppression 16HBE cells were established to reveal relative mechanisms. Our results suggested CBNPs induced pulmonary fibrosis in time- and dose-dependent manners. CBNPs induced persisting inflammation in rat lung as observed by histopathology and cytology analyses in whole lung lavage fluid (WLL). Both in vivo and in vitro, CBNPs exposure significantly increased the expression of NLRP3 inflammasome, accompanied by the increased reactive oxygen species (ROS), decreased miR-96 and increased FOXO3a expressions dose -and time-dependently. MiR-96 overexpression or FOXO3a suppression could partially rescue the fibrotic effects through inhibiting NLRP3 inflammasome. Conclusively, our research show that CBNPs-induced pulmonary fibrosis was at least partially depended on activation of NLRP3 inflammasome which modulated by miR-96 targeting FOXO3a.