Particulate matter 2.5 promotes inflammation and cellular dysfunction via reactive oxygen species/p38 MAPK pathway in primary rat corneal epithelial cells.

Purpose: Numerous studies have linked particulate matter2.5 (PM _2.5 ) to ocular surface diseases, but few studies have been conducted on the biological effect of PM _2.5 on the cornea. The objective of this study was to evaluate the harmful effect of PM2.5 on primary rat corneal epithelial cells (RCECs) in vitro and identify the toxic mechanism involved.
Materials and Methods: Primary cultured RCECs were characterized by pan-cytokeratin (CK) staining. In PM2.5-exposed RCECs, cell viability, microarray gene expression, inflammatory cytokine levels, mitochondrial damage, DNA double-strand break, and signalling pathway were investigated.
Results: Exposure to PM _2.5 induced cytotoxicity and morphological changes in RCECs. In addition, PM _2.5 markedly up-regulated pro-inflammatory mediators but down-regulated the wound healing-related transforming growth factor-β. Furthermore, PM _2.5 promoted mitochondrial reactive oxygen species (ROS) production and mediated cellular damage to mitochondria and DNA, whereas these cellular alterations induced by PM _2.5 were markedly suppressed by a potential ROS scavenger. Noteworthy, removal of ROS selectively down-regulated the phosphorylation of p38 mitogen-activated protein kinase (MAPK) and the activation of the nuclear factor-κB (NF-κB) p65 in PM _2.5 -stimulated cells. Additionally, SB203580, a p38 MAPK inhibitor, markedly suppressed these PM _2.5 -mediated cellular dysfunctions.
Conclusions: Taken together, our findings show that PM _2.5 can promote the ROS/p38 MAPK/NF-κB signalling pathway and lead to mitochondrial damage and DNA double-strand break, which is ultimately caused inflammation and cytotoxicity in RCECs. These findings indicate that the ROS/p38 MAPK/NF-κB signalling pathway is one mechanism involved in PM _2.5 -induced ocular surface disorders.