Expression of toll-like receptor 4/NF-κB signaling pathway in acute necrotizing pancreatitis-associated lung injury and intervention of lipoxin A4 analogue

Abstract

Objective To explore the role of toll-like receptor 4 (TLR4)/NF-κB signaling pathway in acute necrotizing pancreatitis (ANP)-associated lung injury and the intervention of lipoxin A4 (LXA4) analogue. Methods Forty-five Sprague-Dawley rats were randomly(random number)divided into the sham operation group, experimental group, and intervention group, each group containing 15 rats. ANP animal models were prepared by injecting sodium taurocholate into biliopancreatic tube in the experimental group. No sodium taurocholate was injected into biliopancreatic duct in the sham operation group. After the preparation of ANP animal models in the intervention group, LXA4 was injected through the tail vein. Rats in each group were randomly divided into 3 subgroups (n=5 each subgroup). The serum amylase, TNF- α, IL-1β, IL-6 and endotoxin levels were detected 6, 12 and 24 h after the operation. The lung injury scores were assessed and the lung wet/dry weight ratio was calculated. The expressions of TLR4 and NF-κB p65 in lung tissues were detected by Western blot. Results Serum levels of amylase, TNF-α, IL-1β, IL-6 and endotoxin in the experimental and intervention groups were significantly higher than those in the sham operation group, while the levels of the above indicators in the intervention group was significantly lower than those in the experimental group, and the differences were statistically significant (P 0.05), while lung wet/dry weight ratio in the intervention group 6 h after operation, and lung injury scores and lung wet/dry weight ratio in the intervention group 12 h or 24 h respectively after operation were significantly higher than those in the sham operation group, with statistically significant differences (P<0.05). Postoperative lung injury scores and lung wet/dry weight ratio in the intervention group were significantly lower than those in the experimental group, and the differences were statistically significant (P<0.05). The expressions of TLR4 and p65 in the lung tissues of the experimental and intervention groups were significantly higher than those of the sham operation group, and the expressions of TLR4 and p65 in the lung tissues of the intervention group were significantly lower than those of the experimental group, with statistically significant differences (P<0.05). Conclusions LXA4 can reduce the severity of acute necrotizing pancreatitis-associated lung injury, and its mechanism is related to reducing the stimulation of endotoxin, thus inhibiting TLR4 signaling pathway and the activation of p65 to down-regulate the level of pro-inflammatory cytokines. Key words: TLR4; Lipoxin A4; Acute necrotizing pancreatitis; Acute lung injury