Potential molecular mechanism underlying the harmed haemopoiesis upon Benzo[a]pyrene exposure in Chlamys farreri

• Published in: Fish & shellfish immunology Vol. 141; p. 109032
• Main Authors: Zhang, Ning, Pan, Luqing, Liao, Qilong, Tong, Ruixue, li, Yaobing
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.10.2023
• Subjects: B[a]P; C. farreri; Differentiation; Haematopoietic tissue; Immunotoxicity; Proliferation; C. farreri; Proliferation; Haematopoietic tissue; Differentiation; B[a]P; Immunotoxicity
• ISSN: 1050-4648; 1095-9947
• DOI: 10.1016/j.fsi.2023.109032

Benzo[a]pyrene (B[a]P), a ubiquitous contamination in the marine environments, has the potential to impact the immune response of bivalves by affecting the hemocyte parameters, especially total hemocyte count (THC). THC is mainly determined by haematopoietic mechanisms and apoptosis of hemocytes. Many studies have found that B[a]P can influence the proliferation and differentiation of hemocytes. However, the link between the toxic mechanisms of haematopoietic and environmental pollutants is not explicitly stated. This study is to investigate the toxic effects of B[a]P on haematopoietic mechanisms in C. farreri. Through the tissue expression distribution experiment and EDU assay, gill is identified as a potential haematopoietic tissue in C. farreri. Subsequently, the scallops were exposed to B[a]P (0.05, 0.5, 5 μg/L) for 1d, 3d, 6d, 10d and 15d. Then BPDE content, DNA damage, gene expression of haematopoietic factors and haematopoietic related pathways were determined in gill and hemocytes. The results showed that the expression of CDK2 was significantly decreased under B[a]P exposure through three pathways: RYR/IP3-calcium, BPDE-CHK1 and Notch pathway, resulting in cell cycle arrest. In addition, B[a]P also significantly reduced the number of proliferating hemocytes by affecting the Wnt pathway. Meanwhile, B[a]P can significantly increase the content of ROS, causing a downregulation of FOXO gene expression. The gene expression of Notch pathway and ERK pathway was also detected. The present study suggested that B[a]P disturbed differentiation by multiple pathways. Furthermore, the expression of SOX11 and CD9 were significantly decreased, which directly indicated that differentiation of hemocytes was disturbed. In addition, phagocytosis, phenoloxidase activity and THC were also significant decreased. In summary, the impairment of haematopoietic activity in C. farreri further causes immunotoxicity under B[a]P exposure. This study will improve our understanding of the immunotoxicity mechanism of bivalve under B[a]P exposure. [Display omitted] •Identifying gill as potential haematopoietic tissue of Chlamys farreri.•First clarified the influence of B[a]p on pro-hemocytes proliferation in C.farreri.•B[a]p is shown to interfere with the differentiation of pro-hemocytes in C.farreri.•B[a]p affects immunity in bivalves by affecting haematopoietic activity.