The Immune Expression Of DPPⅡ And DPPⅢ In The Normal Rat Eyeball Tissues

DPPII and DPPIII are members of the prolinespecific dipeptidyl peptidases (DPPs) which can hydrolyzed polypeptide section to release dipeptide. They were both intracellular proteases participating the hydrolization of some proteins. DPPII is a lysosome protease that localizes to the vesicular system. It releases, preferably at acidic pH, N-terminal dipeptides from oligopeptides with Pro or Ala in the penultimate position. The molecular mass (Mr) of native DPPII was reported tobe 100–130 kDa, with an Mr value for the subunits of 50–65 kDa. DPPII was also suggested to be involved in the processes of cell differentiation and in the protection from cell death, and to have a role in the degradation of collagen fragments, myofibrillar proteins and short neuropeptides. DPP III is a cytosolic zinc-exopeptidase involved in the intracellular protein catabolism of eukaryotes. The active site of DPPIII contains an essential serine residue. It had a molecular weight of 82845.6Da and played an important role in the breakdown metabolic process of intraocular proteins. It is one of the most important enkephalin-degrading enzymes in the centralnervous system, in human neutrophils. Changes in the activity of some endopeptidaseas such as DPPII , DPPIII in the mammals and human lens had been already studied in and abroad at present. Briefly, DPPII was present in all organs, tissues and fluids investigated, such as brain, kidney, muscles, reproductive organ, body fliud, hematopoietic cell and retinal pigment epithelium. It is demonstrated that DPPII was also in the other normal tissues of ocular region such as cornea and retina. DPPII was related in many pathology processes such as inflammation, degradation, cancer, rheumatoid arthritis, and play an important role in degradating glucoprotein, monosaccharose, amino acids and in the intracellular degradation of proteins at final stage. Someone found the expression of DPPII in the cornea and retina of mammals. The changes of DPPII in activity can also lead to the damage of phagocytic cell, decrease the phagocytotic function, insufficient circulation of extracellular matrix, bony remodeling and may be revolved in the pathology process of autoimmune disease. When speculating on DPPII's possible physiological role and taking in mind its localization and limited substrate selectivity, it's temptingto presume that DPPII has a role in the final steps of peptide degradation as a part of the autophagic process or the degradation of endocytosed protein.DPPIII was purified from cytolist and located in the placenta, erythrocyte, liver, sperm and other tissues of the animals participating the final process of intracellular proteins degradation. Some people inferred that DPPII and DPPIII may be involved in the occurrence and formation of cataract. Further, some scholars had proved that the immunological activity of DPPII and DPPIII in the lens of SCR congenital cataract rats were obviously enhanced compared to normal rats and supposed they were possible correlated with cataract formation.Although further studies were made about DPPII and DPPIII, the function and mechanism of them in the formation of various diseases in ocular organizations were not clear. We also didn't know the location and function of them in cornea, iris, ciliary body, retina and its'relationship with diseases, lacking systematic study in and abroad.The immunological expression of DPPII and DPPIII in thedifferent eyeball tissues of normal Wistar rats were investigated with ABC method to provide initial theoretical foundation for approaching biological effect of them in the eye organizations.Objective:To investigate the immune expression of DPPII and DPPIII in the normal eyeball tissues.Methods:40 normal Wistar rats of both sexes are divided into two groups. The eyes were removed afer the rats were sacrificed and postfixed with 10% formalin for 20h, dehydrated in ethanol, substituted with bezene, and embedded in paraffin wax. Paraffin srctions about 4μm thick were cut using a microtone and mounted on slides. Then, the immune expression of DPPII and DPPIII in the normal eyeball tissues were investigated with ABC method.Results: DPPII found in corneal epithelial cells, cornea stromal layer, corneal endothelial cells, ciliary non-pigment epithelial cells, iris epithelial cells, lens epithelial cells, lens fiber cells, retinal nerve fiber layer, ganglion cells, retinal pigment epithelium showed positive staining; DPPIII found in corneal epithelial cells, corneal endothelial cells, ciliary non-pigmentepithelial cells, iris epithelial cells, lens epithelial cells, lens fiber cells, retinal nerve fiber layer, ganglion cells, retinal pigment epithelium showed positive staining.Conclusion: DPPII were primarily in the corneal epithelium, corneal stroma, corneal endothelial cells. ciliary non-pigment epithelial cells, Iris epithelial cells, lens epithelial cells, the lens fiber cells, retinal nerve fiber layer, ganglion cells, retinal pigment epithelium; DPPIII were primarily in the corneal epithelium, corneal endothelial cells, the non-pigmented ciliary epithelial cells, Iris epithelial cells, lens epithelial cells, fibroblasts lens, retinal nerve fiber layer, ganglion cells, retinal pigment epithelium.