Carbamazepine transmits immune effect by activation of gut-liver axis and TLR signaling pathway from parental zebrafish to offspring

Abstract Carbamazepine (CBZ) has been identified in the aquatic environment as an emerging contaminant. Its immune effect across generations at environmentally relevant concentrations is little known. We aim to elucidate the effects of CBZ on the immune system in zebrafish (Danio rerio), hypothesizing the effects caused by CBZ exposure in the parental generation can be passed on to its offspring, leading to impairment of innate immune function and defense against pathogen weakened. A suite of bioassays (including a test with added lipopolysaccharide) was used to measure the effects of environmentally relevant levels of CBZ (1, 10, and 100 μg/l) on zebrafish at multiple biological levels, and across 2 successive generations (21 days exposure for F0; 5 and 21 days exposure or nonexposure for F1). The results showed that CBZ affected homeostasis in the immune system, caused liver vacuolization, increased the inflammation-related microbiota proportion in gut, and decreased reproduction, by induction of oxidative stress and modulation of Toll-like receptors (TLR) signaling pathway on gut-liver axis. The effects of exposure to CBZ over 21 days in F0 could be passed to the next generation. Intergenerational effects on TLR and antioxidant defense system were also observed in nonexposed F1 at 5 days post-fertilization (5 dpf), but diminished at 21 dpf. The finding provided evidence to unravel immune response by gut-liver axis mediated and oxidative stress under 4 test conditions. The study has raised a potential concern about the multigenerational immune effects of environmental pollutants and calls for a focus on the risk of synergetic pathogen infection.