Nano-silica Particles Exposure Affects Pollen-Sensitized Mice via Nicotinamide Metabolism.

Introduction: The proportion of patients with pollinosis is relatively high within the allergic disease population. Climate change and air pollution negatively affect allergic respiratory diseases. Therefore, further studies are necessary to clarify the effects of pollen grains and air pollution on allergic diseases.

Methods: Building on our previous research, we established an Artemisia pollen-sensitized mouse model and evaluated the impact of nano-SiO2 particle exposure on pollen allergy in this study. Serum samples were collected to detect specific IgE levels and cytokines and conduct metabolomic analysis. Single-cell suspensions were prepared from mouse spleens, and the Th1/Th2 cell ratio was analyzed by flow cytometry. We utilized RBL-2H3 cells, mouse bone marrow-derived mast cells (BMMCs), and the passive cutaneous anaphylaxis (PCA) model to investigate the effects of the most significant metabolites on allergic reactions.

Results: Exposure to nano-SiO₂ particles can exacerbate the damage to the nasal mucosal epithelial cells of pollen-sensitized mice, disrupt the integrity of the nasal mucosal epithelium, promote goblet cell hyperplasia, elevate serum levels of IL-4 and IL-6, and intensify the imbalance between Th1 and Th2 cells. Metabolomic analysis revealed that exposure to nano-SiO₂ particles in pollen-sensitized mice significantly enriched the niacin and nicotinamide metabolism pathways. Nicotinamide was demonstrated to inhibit mast cell degranulation in RBL-2H3 and BMMCs, and to reduce IgE-mediated allergic reactions in the PCA model.

Conclusion: Pollen-sensitized mice exposed to nano-SiO2 particles can aggravate allergic reactions and induce dysregulation of the metabolism characterized by niacin and nicotinamide. Nicotinamide could stabilize mast cells and may serve as a potential therapeutic strategy for allergic diseases. Further in-depth investigations are needed.