Figure 4.

Nano- and microplastics—impact on gut homeostasis. The impact of nano- and micro-sized plastic particles on the intestine is controversially discussed, and the number of studies investigating these relations is limited. It is assumed that small plastic particles take the same routes as TiO₂ nanoparticles and penetrate the intestinal epithelium. Although two publications did not detect any effects of NP or MP on intestinal health and/or inflammation, respectively, conflicting studies report alteration of the gut homeostasis upon plastic administration in mouse models. Several studies describe adverse effects on the gut microbiome, reduced mucus secretion, and damage of barrier integrity upon administration of MP particles. Li et al. describe the reduction in regulatory T-cells (Treg) and Th17 cells, increased Toll-like receptor 4 (TLR4) downstream signaling, and IL1α expression, suggesting activation of pro-inflammatory cascades and translocation of bacterial products into the system [28,29,30,31,32,217,218].