Chitosan oligosaccharides alleviate PM_2.5-induced lung inflammation in rats

Air pollution of particulate matter (PM), especially PM_2.5, has become a major public health problem in China. Exploration of therapeutic and preventive measures against PM_2.5 toxicity is of practical significance. The aim of this study was to examine the inhibitory effects of chitosan oligosaccharides (COS) on PM_2.5-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, PM_2.5 group, and PM_2.5+COS group. COS was pre-administered to rats by gavage at a single dose of 500 mg/kg 2 h before intratracheal instillation of PM_2.5 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 PM_2.5, 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 PM_2.5 group significantly increased in comparison with those of the control group. Pre-treatment of rats with COS markedly blocked PM_2.5-induced increase in LDH, IL-8, and TNF-ɑ levels in BALF. In conclusion, PM_2.5 exposure induces rat lung inflammation, which could be ameliorated by the pre-treatment of COS.