Dynamic Changes In IL-18mRNA Expression And Its Implication In Ct-infected Rats

Objective: Interleukin-18 is a cylokine that is found recently. It has some immune regulative action that induced T lymphocyte and nature killer cell to produce IFN- Y and strengthen cytotoxity of T lymphocyte and mature killer cell. It has probable apply prospect in the treatment of tumor, infection of pathogenic microbiology, hypersensitivity and so on. Then IFN- γ plays an important role in the process of immunoprotecive and lesion after infection of CT at genital tract, such as anti-infection during the earlier period and participating in the damage to host by delayed-type hypersensitivity (DTH) and so on, of which mechanism is related with various inflammation medium after stimulating the host. So, as the stimulating factor to IFN- γ interleukin-18 also takes part in the process of damage and fibrosis of host after infection. In this article by using a rat model of CT infection we investigate the dynamic changes in IL-18 mRNA expression and medium effect in the different stages of the first infection.Methods: Forty-eight adult female SD rats (200~230g body weight) were inoculated into the ovarian bursa with C. trachomatis, immunotype D which was transfered of culture in Henrietta Lacks strain of cancer cells (Hela), and were killed on 3rd, 7th and 14th day postinfection respectively. RT-PCR using β -actin as an internal standard was used to semi-quantitate IL-18mRNA and IFN- γ mRNA expression in the oviduct. Enzyme-linked immunosorbent assay (ELISA) was performed for interferon- γ (IFN- γ) measurement. The FasL expression in the oviduct mucosa was detected by streptavidin proxidase method (S-P method).Results: 1. IL-18 and IFN- γ mRNA expression significantly increased to compare with un-infected group after infection, peaking at the third day, and a high level was maintained till the seventh day. The expressions obviously declined about two weeks. 2. IFN- γ didn't appear significantly at un-infected group, but increased at infected group, peaking at the third day, and a high level was maintained till the seventh day. Thevariations of IFN- y kept pace with that of the IL-18 mRNA after CT infections.3. The average optical density of oviductal mucosa with FasL didn't change obviously. Then the expression increased after infection, peaking at the third day, and a high level was maintained till the seventh day. The expressions obviously declined at about two weeks.4. The positive correlation was outstanding between IL-18mRNA expression and IFN- Y mRNA expression, between IL-18mRNA expression and IFN- Y , and between IL-18mRNA expression and FasL.Conclusion: IL-18mRNA expression of oviduct has a marked elevation after CT infection, and has trend to farther increase; IL-18mRNA expression after infection is influence on synthesis and release of IFN- y , and expression of FasL.