Protective effects of quercetin on intestinal barrier and cellular viability against silver nanoparticle exposure: insights from an intestinal co-culture model

The intestinal epithelium plays a pivotal role as a vital barrier between the external environment and the human body, regulating nutrient absorption and preventing the entry of harmful substances. The human oral exposure to silver nanoparticles (AgNP) raises concerns about their potential toxicity, especially at the intestinal level. The objective of this work was to investigate the potential pro-inflammatory effects of polyvinylpyrrolidone (PVP)-AgNP of two different sizes, 5 and 50 nm, at the intestinal level, while also assessing the protective ability of quercetin against these effects. To address this, an intestinal co-culture model comprising C2BBe1 cells and THP-1 derived macrophages was established, and the effects of 5 or 50 nm PVP-AgNP were studied, alone or in combination with quercetin, over two-time points, 4 and 24 hours. PVP-AgNP, of both sizes, disrupted the barrier integrity within 4 hours of exposure. However, a notable intensification in pro-inflammatory effects was evident only after 24 hours of exposure, especially with smaller PVP-AgNP (5 nm). This resulted in heightened cellular death, increased levels of reactive species, activation of nuclear factor kappa B (NF-кB), and production of interleukin (IL)-8. Quercetin demonstrates the ability to maintain barrier integrity and mitigate oxidative stress, thereby offering protection against the detrimental effects induced by AgNP at the intestinal level.