An Experimental Study On The Effects Of Il-ra On Cytokines (IL-1β,TNF-α) Of High-risk Corneal Graft In Rat And Their Relationship With Penetrating Keratoplasty Rejection

Background:The corneal transplant rejection is the major reason of failure for corneal transplantation, especially of patients with cornea neovascularization who are named as high-risk penetrating keratoplasty. The graft is always destructed early and severely. High-risk corneal transplant rejection is a complex process and needs further research on the cytokines involved. Cytokine research is one of the hottest areas of life sciences. Therefore, in-depth research on cytokines is useful in studying the immunopathologic process of rejection and paving new ways to probe the more effective treatment.Interluekin-1 receptor antagonist(IL-lra) was the first antagonist ever found. It is a kind of protein that comes from monomacrophage and has homogeneity for Interluekin-l(IL-l). It acts as a pure antagonist of biologically active IL-l.IL-lra blocks cellular responses to IL-1 by binding almost irreversibly to the BL-1 receptor without triggering signal transduction. Animal experiments indicated that IL-lra can markly prolong the survival time of corneal allografts by inhibiting graft rejection, and prevent vascular growth of corneal allografts, although the mechanism is still unclear.IL-1 is a critical multifunctional cytokine released by mononuclear-6-phagocyte. It has a wide range of activities, including the critical mediation of the acute phase response, chemotaxis and activation of inflammatory and antigen-presenting cells, up-regulation of adhesion molecules on cells, and stimulation of neovascularization. There are two types that IL-loand IL-l. Both these types can bind with the same cytomembrane receptor, but the main role is induced by DL-lp. By measuring levels of Tumor necrosis factor-a (TNF-a) , the earlist cytokine released at the beginning of inflammation, IL-lra has been shown to not only evocate and regulat release of many kinds of cytokines, but also play a main function in the process of immune response. Some researchers have already begun to detect the content of TNF-a after cornea! allgraft.This experiment established a model of high-risk penertrating keratoplasty of rat to study the effects of IL-lra on CNV and expression of cytokines (IL-lp\ TNF-a) . The relationship between IL-lra and high-risk cornea! allografts rejection is discussed.Objective:1. To investigate the expression of cytokines(IL-lp\ TNF-a) after treated with IL-lra on the CNV in rat, and analyze their relationship;2. To investigate the expression of cytokines(IL- TNF-a) after treated with IL-lra and CsA on the high-risk cornea allografts in rat, and analysis their relationship;3. To study comparatively the immunosuppressive effect of IL-lra and CsA on the rejection during the high-risk immune rejection in experiment penetrating keratoplasty in rat model.Methods:1. CNV was induced by 10-0 nylon stitch on 20 SD rats that was randomly assigned to two groups: group I was treated by N.S; group n was treated by IL-lra . Treatments began on the first postoperative day. The change of the area of CNV was observed at different times with 5 rats each-7-group. The other eyes on ld4d and lOd respectively. Cellular and morphologic changes of cornea! buttons were evaluated by light microscope examination. IL-1P and TNF-a mRNA levels were determined by in situ hybridization combined with computer-assisted image analysis. Immunohistochemistry combined with computer-assisted image analysis was adopted to examine the expression and distribution of IL-1P and TNF-a proteins in CNV rats;2. High-risk cornea! transplantation was performed orthotopically from Wistar rats to SD rats of CNV. Recipients were randomly assigned to three groups: group I was treated by N.S; group n was treated by CsA;. group HI was treated by IL-lra; Treatments began on the first postoperative day. Mean survival times .neovascular area, and rejection index were determined. Cellular and morphologic changes of cornea! buttons were evaluated by light microscope examination. EL-lp and TNF-a mRNA levels were determined by in situ hybridization combin...