The “Butterfly Effect” of heart failure: Induced by the combination of polylactic acid nanoplastics and copper from the perspective of gut microbiome

Plastic and heavy metal pollution have received extensive attention, but there is relatively little research on the damage to the gut-heart axis induced by the co-exposure to plastics and heavy metals. This study investigated the impact of the co-exposure of Polylactic acid nanoplastics (PLA-NPs) and copper (Cu) on heart failure (HF) in mice and explored the role of the gut microbiota in mediating this adverse outcome. Male C57BL/6J mice were divided into four groups: the Control group, the PLA-NPs group, the Cu group, and the Co-exposure group (PLA-NPs + Cu group). A 28-day exposure experiment was conducted. The research results indicate that, compared with the Single-exposure groups (PLA-NPs and Cu groups), the mice of Co-exposure group exhibited more severe toxic effects, including more pronounced myocardial hypertrophy and more severe myocardial fibrosis. These damages might be caused by increasing the heart's sensitivity to ferroptosis. Additionally, the co-exposure caused significant damage to the gut barrier and remarkable dysbiosis in the gut microbiota, such as a reduction in the abundances of beneficial bacteria like Lactobacillus. The fecal Microbiota Transplantation experiment confirmed that the alterations in gut microbiota play a pivotal role in the synergistic toxicity induced by PLA-NPs and Cu. This study for the first time reveals the mechanism of the combined effect of PLA-NPs and Cu on cardiac damage and emphasizes the crucial role of gut microbiota in this process.