Polystyrene microplastics exposure increases the disruption of intestinal barrier integrity and gut microbiota homeostasis during obesity and aging

The global rise in intestinal dysfunction has been linked to modifiable risk factors including high-fat diet (HFD)-induced obesity/diabetes, microplastics (MPs) and aging, yet their combined effects remain unclear. This study examined the combined effects of chronic low dose polystyrene MPs (∼25 µg/(kg·day)) with HFD or aging on intestinal barrier function in C57BL/6 J mice over 14 weeks. Juvenile mice receiving either normal chow (NCD) or HFD, along with aged NCD-fed mice, were subjected to MPs exposure. Results demonstrated that MPs exposure or HFD feeding (and aging) significantly exacerbated the pathological changes developed in colon tissues of mice relative to those of control mice, including gut permeability, oxidative stress, pro-inflammatory response and apoptosis. Moreover, combination of MPs exposure with HFD feeding (and aging) further potentiated the harmful effects on colon dysfunctions, clearly showing a synergistic deterioration effect ('double hit'). More importantly, we found that the recovery of colon damages resulting from MPs exposure and HFD feeding was disrupted after their withdrawal, leading to the worse effects on gut microbiota dysbiosis and intestinal function. Furthermore, oral administration of Akkermansia muciniphila prevented intestinal barrier dysfunction and decreased intestinal permeability from MPs exposure and HFD feeding co-exposure. Our findings in this study emphasized the important role of avoiding MPs exposure in the prevention and treatment of intestinal-related dysfunctions, and provided potential therapeutic approaches. The oral administration of gut microbiota, such as Akkermansia muciniphila, contributed to restoration of intestinal barrier function, uncovering a new landscape for treating intestinal disabilities caused by MPs exposure.