Chitosan oligosaccharides alleviate PM2.5-induced lung inflammation in rats.

Air pollution of particulate matter (PM), especially PM2.5, has become a major public health problem in China. Exploration of therapeutic and preventive measures against PM2.5 toxicity is of practical significance. The aim of this study was to examine the inhibitory effects of chitosan oligosaccharides (COS) on PM2.5-induced lung inflammation in rats. Forty SPF (specific pathogen-free) male Wistar rats weighing 200-220 g were randomly divided into four groups: control group, COS group, PM2.5 group, and PM2.5+COS group. COS was pre-administered to rats by gavage at a single dose of 500 mg/kg 2 h before intratracheal instillation of PM2.5 at a single dose of 1.2 mg/kg daily for 3 consecutive days. Normal saline (NS) was used as negative control. Twenty-four hours after the last instillation of PM2.5, rats were sacrificed and subjected to bronchoalveolar lavage (BAL). The BAL fluids (BALF) were collected for measurement of levels of total proteins, lactate dehydrogenase (LDH), interleukin-1 (IL-1β), IL-8, and tumor necrosis factor-ɑ (TNF-ɑ) using colorimetric or ELISA kits. Levels of total proteins, LDH activities, and pro-inflammatory mediators including IL-1β, IL-8, and TNF-ɑ in BALF of rats in PM2.5 group significantly increased in comparison with those of the control group. Pre-treatment of rats with COS markedly blocked PM2.5-induced increase in LDH, IL-8, and TNF-ɑ levels in BALF. In conclusion, PM2.5 exposure induces rat lung inflammation, which could be ameliorated by the pre-treatment of COS.