"Impact of chronic dietary intake of Bacillus thuringiensis insecticides on the gut environment and susceptibility to chronic inflammatory bowel diseases"

Abstract :

"Bacillus thuringiensis (Bt) spore-based bioinsecticides are widely used in agriculture to target specific insect pests. However, due to their resilience and persistence, Bt spores are now widespread in the environment and food chain. Bt belongs to the Bacillus cereus (Bc) group, which includes opportunistic pathogens that cause food poisoning and are a major cause of foodborne outbreaks in France. The presence of opportunistic pathogens in the gut is known to promote inflammation, and when this inflammation becomes chronic, it can contribute to the development of inflammatory bowel diseases (IBD). They can also disrupt the balance of the gut microbiota (dysbiosis). While short-term studies suggest that Bt spores may not harm non-target organisms, their long-term effects on the digestive system and gut microbiota, particularly the potential risk of chronic inflammation in genetically predisposed individuals, remain unclear. Therefore, investigating the long-term impact of Bt spores on gut health is crucial.

To investigate the impact of the chronic ingestion of Bt spores on gut physiology, we used adult Drosophila melanogaster as a non-target insect model. Our results reveal that Bt spore ingestion changes gut morphology by inducing dysplasia and altering septate junction integrity, thereby amplifying gut permeability. These changes are accompanied by elevated levels of inflammatory signaling and reactive oxygen species, as well as metabolic changes in glucose and lipid pathways. Further analyses, including dysbiosis assays and experiments on axenic and immunocompromised flies, are ongoing to better understand the underlying mechanisms affecting gut physiology. Overall, chronic ingestion of Bt spores induces inflammation and oxidative stress, leading to premature gut aging and early mortality in Drosophila."