Treatment Of Noninfectious Cornea Ulceration With Topical Autologous Serum And Glucocorticoid

Corneal ulceration is a devastating disorder that that involves thedegradation of corneal stroma associated with either sterile or infectiousinflammation. It can cause blindness.Studies have identified the enzymesinvolved as specific members of the matrix metalloproteinase (MMP)family,which produce by living cell and effect to corneal stroma collagen. AllMMPs activated can be inhibited by tissue inhibitors of matrixmetalloproteinases (TIMPs).Keratocytes, which are the only cells of the corneal stroma, play animportant role in collagen metabolism. These cells thus both synthesize anddegrade collagen fibrils. Keratocytes can produce MMPs, and MMPs candigest collagens. The opportunistic Gram-negative pathogen Pseudomonas aeruginosa is acausative agent of severe keratitis. That is mediated by both pseudomonal andhost factors. We think that the elastase from P. aeruginosa and the MMPs fromthe cells of host has stimulatory effect on collagin degradation. Serum havedistinct biology properties bionomics properties and physiologic function. Itcontains the inhibitors of collagenase -α1,α2 macroglobulin and TIMP-1.Adequate expression of TIMP-1 protects against corneal Basement membraneand stromal degradation via multiple processes. In addition to directlyprotecting extracellular matrix components from active matrixmetalloproteinases, TIMP-1 may either directly or indirectly influencerecruitment of PMNs into infected cornea.We devise this experiment toinvestigation the effection of serum on collagen degradation by keratocytescultured in a three-dimensional collagen gels.Method: Type Ⅰcollagen gels with or without suspended keratocyteswere incubated and treated with 10% pseudomonal culture medium anddifferent concentrations of serum for 24 hours .Then the amount ofhydroxyproline was measured spectrophotometrically.Results: In the presence of keratocyte collagen degradation wasdecreased significantly with the increasing of serum concentration ,but cannoteffect collagen degradation without keratocyte.Discussion: Excessive degradation of collagen in the corneal stroma,mediated in part by MMPs, results in corneal ulceration. Keratocytes play animportant role in collagen metabolism. In healthy cornea, keratocytes are in thestate of stillness relatively and non-activation.When cornea ulcer occur,keratocytes are Activated. Activated keratocytes migrate to the area of absenceof matrix, proliferate and Synthesize ECM and MMPs. Excess expression ofMMPs would result in collagen excess degradation,then come into beingcornea ulceration. MMPs are synthesized and secreted by multiple cell types,including neutrophil ,corneal epithelial cells and fibroblasts. Stroma fibroblastsis the major Source in the present experiment .MMPs are synthesized and secreted as inactive proenzymes that areactivated by serine proteinases, such as plasmin, in the extracellular space. P.aeruginosa both degrades TypeⅠ collagen directly and promotes collagendegradation mediated by keratocytes,the latter effect being likelyattributable,at least in part, to the activation of proMMPs. .Those plays animportant role on corneal ulceration and stromal destruction. Pseudomonalelastase reportedly activates proMMP-1,-8 and -9 produced by limitedproteolysis.The culture supernatant of P. aeruginosa (elastase) may activatesproMMPs produced by keratocytes in the present studies.All MMPs activated can be inhibited by tissue inhibitors of matrixmetalloproteinases (TIMPs). TIMPs are endogenous inhibitors ofMMPs,which inhibits specially the activaty of MMPs. Serum contain a largevariety growth factors, such as transforming growth factor(TGF), fibroblastgrowth factor (FGF),epidermal growth factor (EGF), Insulin-like growthfachor (IGF), nerve growth factor (NGF) and fibronectin(FN),and wereprevented from corneal ulceration and perforation in clinic.Conclusion: Serum inhibites collagen degradation mediated bykeratocytes significantly in a dose-dependent fashion, but cannot effectcollagen degradation without keratocyte. This hints us that certain activecomponent of serum may attribute to the inhibition effect on the expressionand activation of MMPs, thus prevented collagen degradation produced bykeratocytes. The present studies provide a theory base for the treatmentinfectious cornea ulceration and noninfectious cornea ulceration that induce bycollagen degradation.