The upregulation of pro-inflammatory cytokines in the rabbit uterus under the lipopolysaccaride-induced reversible immunoresponse state

- The objective of this study was (1) to provide a suitable intravenous injection dose of lipopolysaccharides (LPS) instead of Gram-negative bacterial infection for inducing a reversible immunoresponse state and (2) to examine the expression levels of pro-inflammatory cytokines in the uterus of rabbits under immunoresponse state.
- In the study, We firstly reported that (1) 0.5 mg/kg b.w. of LPS induce a reversible immunoresponse of female rabbit within 24 h, and (2) under the reversible immunoresponse state, the expression of IL-1β, IL-6 and TNF-α in the uterus of rabbit was upregulated. (3) The significance of the study is to set up an animal model to explore the genital tract immuodefense under the reversible inflammatory state, especially in silent infection of reproductive tract.

The reproductive organs are more likely to develop gram-negative bacterial infection than other internal organs because of direct access to the body surface. The objective of this study was (1) to provide a suitable intravenous injection dose of lipopolysaccharides (LPS) instead of gram-negative bacterial infection in order to induce a reversible immunoresponse state and (2) to examine the expression levels of pro-inflammatory cytokines in the uterus of rabbits while in an immunoresponse state. Two series of experiments were performed to accomplish these objectives. In the first series, 20 healthy New Zealand White female rabbits were divided into 5 homogeneous groups (n = 4), and intravenously injected with 0, 0.5, 1, 2, or 4 mg/kg body weight (BW) of LPS derived from Escherichia coli dissolved in 2 ml of sterile saline (LPS carrier). The control group received only saline. The concentrations of IL-1β, IL-6, and TNF-α in serum and the white blood cell count changed with time after LPS stimulation, and certain doses of LPS led to the death of some rabbits. The results suggested that a dose of 0.5 mg/kg of LPS induced a reversible immunoresponse state. In the second series, 4 rabbits were not injected (0 h), 16 rabbits were injected with 0.5 mg/kg LPS, and 16 rabbits in the control group were injected with 2 ml of sterile saline. Tissues of the uterine horn, uterine body, and cervix from the 36 rabbits were collected at 0, 1.5, 3, 6, and 12 h (n = 4) postinjection for examination of the expression levels of IL-1β, IL-6, and TNF-α by quantitative real-time PCR (qRT-PCR). The results suggested that 0.5 mg/kg of LPS upregulated the expression levels of IL-1β, IL-6 and TNF-α in the uterine body and uterine horn, and IL-6 in the cervix. In conclusion, the expression levels of IL-1β, IL-6 and TNF-α were upregulated in the uterus of rabbits under the reversible immunoresponse state induced by 0.5 mg/kg of LPS-injection.