Negative Air Ions Alleviate Particulate Matter-Induced Inflammation and Oxidative Stress in the Human Keratinocyte Cell Line HaCaT

BACKGROUND: Recent studies have revealed that particulate matter induces inflammation, oxidative stress, and several skin diseases. Experimental results have also shown that negative air ions are highly effective in removing particulate matter-induced inflammation. OBJECTIVE: The present study aimed to investigate whether negative air ions can inhibit inflammatory responses and reduce oxidative stress in HaCaT cells exposed to particulate matters. METHODS: HaCaT cells were treated with particulate matter in the presence or absence of negative air ions and the viability was evaluated by the MTT assay. Reactive oxygen species (ROS) generation was quantified by the dichlorodihydrofluorescein diacetate assay. The expression of genes and proteins was analyzed by real-time polymerase chain reaction and Western blot. Levels of inflammatory cytokines were quantified by enzyme-linked immunosorbent assay. RESULTS: Negative air ions were observed to downregulate the mRNA and protein levels of particulate matter-induced pro-inflammatory cytokines in HaCaT cells. In addition, negative air ion treatment suppressed particulate matter-induced intracellular ROS generation, p38 mitogen-activated protein kinase activation, and activator protein 1 (c-Fos and c-Jun) activation. CONCLUSION: Our findings indicate that negative air ions exert anti-inflammatory and antioxidant effects in HaCaT cells exposed to particulate matter. Therefore, negative air ions can be used for the prevention and treatment of particulate matter-related inflammatory skin diseases.