Polyunsaturated fatty acids, vitamin E and lycopene alleviate ambient particulate matter organic extracts-induced oxidative stress in canine lung cells via the Nrf2/HO-1 pathway.

Exposure to environmental particulate matter (PM) causes lung damage in humans, but it is not sufficiently studied in companion animals. In this work, we found that organic extracts (OE) of PM induced oxidative stress and were more cytotoxic than water-soluble extracts (WE) of PM in canine (Canis familiaris) pulmonary alveolar type II epithelial (PAE) cells. Subsequently, we evaluated the alleviating effects of polyunsaturated fatty acid mixtures (eicosapentaenoic and docosahexaenoic acids), vitamin E, and lycopene on OE-exposed PAE cells. The results indicated that the three nutrients attenuated OE-induced oxidative stress. Compared with OE-exposed PAE cells, cells pretreated with the three nutrients exhibited a 1.7 ~ 2.2-fold reduction in reactive oxygen species, 15.58% ~ 19.96% increase in cell viability, 26.19% ~ 29.32% reduction in lactate dehydrogenase release and 33.87% ~ 40.10% reduction in intracellular malondialdehyde. Meanwhile, the activities of superoxide dismutase, catalase, and glutathione peroxidase increased by 35.22% ~ 47.70%, 45.36% ~ 64.13%, and 48.56% ~ 68.18%. Besides, microscopic observation revealed that nutrients improved cell morphology, as evidenced by reduced cell shrinkage and increased apposition. Finally, the mechanisms of OE toxicity and antioxidant nutrients were explored respectively. The results revealed that OE triggered cytotoxicity by directly disrupting antioxidant enzyme activity through activation of ROS, while nutrients inhibited OE-induced cellular oxidative stress via upregulation of the Nrf2/HO-1 signaling pathway. The present study may provide significant insights into the prevention of PM-induced lung diseases by antioxidant supplementation in animals.