Expressions of Lipocalin 2 and Its Relative Cytokines in Endotoxic Mice

  Objective  To explore the influence of an endotoxin lipopolysaccharide (LPS) injection on the expressions of lipocalin 2 (LCN2) and its relative cytokines in mice.

  Methods  C57BL/6 mice were randomly divided into 3 groups (n=8 each) according to the serial LPS dosages of 10, 20, and 30 mg/kg. The control group (n=8) received only isotonic saline injection. Twenty-four hours later, cecum and blood samples were collected, and enzyme-linked immunosorbent assay (ELISA) and Western blot were performed to detect the serum levels of interleukin(IL)-1β, IL-6, IL-17A, and LCN2, and real-time polymerase chain reaction (PCR) to determine the LCN2 mRNA level in cecum lysate.

  Results  The serum levels of IL-6 and LCN2 and the levels of IL-1β, IL-6, IL-17A, and LCN2 in cecum lysate in two large-dosage LPS groups (20 mg/kg and 30 mg/kg) were significantly higher than their counterparts in control group (P < 0.05). Compared with the 10 mg/kg LPS group, the levels of IL-6 and LCN2 in serum and the levels of IL-1β, IL-17A, and LCN2 in cecum lysate significantly increased in the 30 mg/kg LPS group (P < 0.05). 2^-ΔΔCT was used to indicate fold changes of LCN2 mRNA in intestine. The results expressed as mean±standard deviation were as follows:1.548±0.417 for con-trol group, 3.184±0.716 for 10 mg/kg LPS group, 4.875±0.547 for 20 mg/kg LPS group, and 7.489±0.820 for 30 mg/kg LPS group, and the difference was significant between either two groups (P < 0.05).

  Conclusions  LPS dose-dependently increases the level of LCN2 expression in cecum. The serum IL-6 level as well as the cecum IL-1β and IL-17A levels have certain correlations with the LCN2 level.