Histo-immunological Aspects of ZnO Nanoparticles in Mice (Mus musculus)

This study aimed to investigate the histo-immunological aspects of zinc oxide nanoparticles (ZnO-NPs) in mice (Mus musculus), focusing on the thymus and spleen as the two main target organs involved in the immune system. A group of 75 BALB/c male mice of ca. 6 weeks of age were placed in glass cages held at a room temperature of 20±2°C, a 12:12 light/dark cycle and 50-70% relative humidity. After a 2-week acclimation period, the mice were randomly divided into two groups (n=25): a control group and a ZnO-NPs orally-administered group. The animals were fasted overnight before treatments were offered. Sampling was performed on days 1, 7 and 14 of the experiment. An effect of ZnO-NP exposure was reflected in the lymphocyte count, where the total number of lymphocytes decreased, suggesting inflammatory reactions. The ZnO-NPs were also associated with increased TGF-β levels. Histological assessment of thymus and spleen used to verify the toxicity of ZnO-NPs demonstrated that ZnO-NPs induce diverse pathological lesions in both organs. This study suggests that exposure to ZnO-NPs can induce inflammation in the thymus and spleen tissues, as two main target organs involved in the immune system.