An innovative in vitro model of IBD to assess micro-/nano-plastics intestinal toxicity.

Introduction : Microplastics contaminations in our food has been reported in numerous studies. The risk linked to the ingestion of micro-/nano-plastics has raised concern among authorities such as the WHO or the European Food Safety Authority (EFSA). Studies on in vitro mammalian cells models and on in vivo rodent models are rising and show toxicological impacts such as inflammation, oxidative stress, metabolic changes, gastrointestinal and hepatic toxicity. Most of them are using high plastic concentrations and focus on a single type of plastic, mostly polystyrene beads. Few of them demonstrated a link between intestinal inflammation and micro-/nano-plastics. This suggest that a preliminary inflammatory intestinal state such is the case of patients with inflammatory bowel diseases (IBD) can promote toxicological effects of some micro and nano-plastics.
Aim : In our research we tried to find out if micro- and nano-plastics could have a greater toxicological impact in people with chronic intestinal inflammation. To do this, we first developed an in vitro model of inflamed intestine.
Methods : To generate a repeatable and close-to-physiopathology inflamed gut model, we generate a pro-inflammatory cytokine cocktail by stimulating THP-1 monocyte-like cell line. To evaluate the impact of micro-/nano-plastics on IBD ant their capacity to exacerbate the inflammation, we use the NF-κB reporter (Luc)-HCT-116 cell line exposed or not to our pro-inflammatory cocktail. Then, we exposed our intestinal cell model to polystyrene beads (100 & 500 nm) and PVC microparticles.
Results : Our results showed a production of pro-inflammatory cytokines (TNF-α, IL-1β and IL-6) by differentiated and LPS stimulated THP-1 in their supernatant. In addition, this cocktail induces the activation of NF-κB on HCT-116 cells. PS and PVC micro and nano-plastics increased the inflammation on the inflamed intestinal model but not in a healthy model.
Conclusion : Taken together, our results clearly highlighted the exacerbation of inflammation by micro-/nano-plastics through the NF-κB pathway under the conditions of our innovative in vitro model of IBD. These preliminary results support our hypothesis of a greater toxicological impact of micro-/nano-plastics when they are ingested by people with IBD.