Expression of fractalkine in acute lung injury induced by paraquat in rats

Abstract

Objective To observe the expression of fractalkine (FKN or CX3CL1) in serum and lung tissue in early phases after paraquat (PQ) poisoning in rats, and to analyze the effect of FKN on acute lung injury induced by PQ. Methods A total of 66 SD rats were randomly(random number) divided into two groups, namely PQ group(n=36) and control group(n=30). Through intra-peritoneal route, PQ (22 mg/kg) was administered to PQ group, and an equal volume of normal saline to control group instead. Rats were separately sacrificed at 6 h, 12 h, 24 h, 72 h and 120 h after poisoning. Lung coefficient was determined. The levels of FKN in serum and lung tissue homogenate were detected by ELISA. Lung pathological changes were observed by HE staining. FKN changes were investigated by immunohistochemistry staining. Data was analyzed by SPSS 19.0. Results From 6 h to 120 h after poisoning, parameter determined in PQ group had great changes, compared with the control group. At 6 h, 12 h, 24 h, 72 h and 120 h, lung coefficients in PQ group were 5.03±0.07, 5.17±0.10, 5.46±0.10, 5.68±0.15 and 5.83±0.11, respectively , which were significantly higher than those(4.49±0.20, 4.28±0.13, 4.45±0.17, 4.31±0.19 and 4.31±0.16) in control group(P<0.01). Levels of FKN(pg/mL) in serum were 140.9±15.8, 157.9±17.6, 188.8±24.8, 224.4±18.1 and 229.9±10.0, respectively, significantly higher than those(121.7±12.8, 121.6±12.1, 118.3±14.0, 122.8±12.4 and 120.5±8.8) in control group(6 h P<0.05, others P<0.01). Levels of FKN(pg/mL) in lung tissue homogenate were 4 222.0±641.1, 5 021.0±514.5, 5 911.6±478.1, 7 092.2±652.9 and 7 639.3±666.6, respectively, significantly higher than those(2 860.2±477.3, 3 068.9±446.0, 3 168.7±728.5, 3 178.0±488.2 and 3 147.3±426.6) in control group(P<0.01). In PQ group, pathological changes manifested themselves in inflammatory cell infiltration, congestion, edema, structural damage, etc. The lung injury aggravated gradually from 6 h to 120 h. In control group, there was no significant change. FKN expressed mainly in bronchial cells, alveolar epithelial cells and pulmonary artery endothelial cells. Where there was higher expression of FKN, there were more inflammatory cells infiltrated. The level of FKN in lung tissue homogenate was positively correlated with lung coefficient(r= 0.937). The level of FKN in serum was positively related to that in lung tissue homogenate(r=0.968). Conclusion There is correlation between FKN and acute lung injury induced by PQ in rats. Key words: Paraquat; Poisoning; Fractalkine; Lung injury; Rat