Toxic effects of UV-329 on the immune system of adult marine medaka (<italic>Oryzias melastigma</italic>)

Ultraviolet absorbers, represented by UV-329, are widely present in aquatic environments and pose potential threats to ecosystems. This study systematically evaluated the immunotoxic effects of different concentrations of UV-329 (5, 50, 100, 200, 500, 1000, 2500 μg·L−1) on adult marine medaka (Oryzias melastigma) through a 28-day exposure experiment. ELISA analysis revealed that UV-329 exposure significantly inhibited the expression of immune-related factors AhR and CYP1A1 in the intestines, kidneys, and liver, while markedly reducing the levels of immune proteins Ig-G and IL-17A. Additionally, histopathological analysis showed that UV-329 exposure induced pathological damage in the intestines, including villus atrophy, goblet cell reduction, and epithelial vacuolation, further confirming the immunosuppressive effects of UV-329. This study demonstrates that UV-329 suppresses the expression of key immune factors and induces intestinal damage in marine fish, highlighting its potential immunotoxicity and providing critical data for assessing its ecological risks to marine organisms.