Micro/nanoplastic-induced gut dysbiosis: A key driver of systemic toxicity via the gut-organ axes in animals.

Micro/nanoplastics (M/NPs) are ubiquitous emerging contaminants that have permeated all trophic levels of global ecosystems. The gut microbiota, which serves as the central hub for host metabolic homeostasis, immune defense, and neuromodulation, is a confirmed critical amplifier of M/NP-induced toxic effects. This review describes the links between M/NP exposure, gut dysbiosis, intestinal barrier impairment, and systemic multiorgan injury. We compared microbial changes across diverse aquatic and terrestrial animal taxa. These microbial shifts are characterized by the enrichment of opportunistic pathogens (e.g., Vibrio and Proteobacteria) and the depletion of beneficial commensal bacteria (e.g., Lactobacillus). We analyzed four primary pathways through which M/NPs perturb the gut microecology, including physical damage, chemical leaching of additives, immune activation, and the Trojan horse effect. We explain the molecular mechanisms through which gut dysbiosis mediates host neurobehavioral abnormalities, metabolic reprogramming, and reproductive dysfunction through the gut-brain, gut-liver, gut-kidney, and gut-reproductive axes. Importantly, this study connects laboratory data with real-world human exposure and clinical findings. It also highlights the significance of exploring emerging cross-organ axes, such as the gut-lung and gut-heart axes. Finally, health risks are assessed under the One Health framework, and targeted strategies are proposed to mitigate the toxic effects of M/NPs.