Virus Infections In The Eye

我们对病毒和寄生虫在眼微环境中复制时发生的各种病毒学和免疫病理过程的研究包括四个方面：(1)病毒诱导的视网膜退行性过程；(2)病毒在人类疾病中的可能作用；(3)人巨细胞病毒（CMV）感染的分子诊断与发病机制；(4)眼部疱疹病毒感染。我们建立了研究视网膜退行性疾病的模型系统——实验性冠状病毒视网膜病变（ECOR）。该病毒能够在轻度视网膜血管炎症的情况下诱发急性感染。最初的视网膜损伤随后是感染性病毒的清除和进行性视网膜变性。这是第一个证明病毒诱导变性、病毒持久性、病毒诱导组织损伤的遗传易感性和病毒引发自身免疫反应的视网膜模型。我们的目标是确定病理生理机制和识别基因参与视网膜退行性疾病。在过去一年中，我们取得了以下主要成果。我们评估了非常早期的细胞因子和趋化因子谱，作为测量视网膜变性易感和视网膜变性抵抗背景的冠状病毒感染小鼠免疫反应性强度的指标。这些研究确定了两种小鼠品系产生的早期免疫反应的明显差异。这些差异在ifn - γ和ifn - γ触发的两种趋化因子CXCL9和CXCL10的产生中被注意到。在第2天和第3天，BALB/c小鼠血清中高水平的ifn - γ、CXCL9和CXCL10。与此同时，在CD-1小鼠的血清中检测到的这些分子水平明显较低。此外，对视网膜进行实时PCR分析发现，与CD-1小鼠相比，BABL/c小鼠视网膜中CXCL9和CXCL10基因的表达显著增加。这些研究确实令人兴奋，并确定了允许BALB/c小鼠具有可能触发自身免疫成分的强大免疫反应的可能机制。CXCL9和CXCL10是与活化T细胞和NK细胞上存在的CXCR3相互作用的强效趋化因子。它们引导迁移并刺激这些细胞的粘附。这些T细胞参与免疫反应，对抗视网膜内的感染和自身目标。这些趋化因子已被证明是诸如HSV角膜炎和SARS等病毒感染的关键因素。事实上，在SARS中，感染后早期检测血清CXCL10浓度是疾病结局的独立预后指标。

Our studies of various virologic and immunopathologic processes that occur when viruses and parasites replicate in the ocular microenvironment comprise four areas: (1) virus induced retinal degenerative processes; (2) the possible roles of viruses in human diseases; (3) molecular diagnosis and pathogenesis of cytomegalovirus (CMV) infections in man; and (4) herpesvirus infections of the eye. We have established a model system for studying retinal degenerative diseases, experimental coronavirus retinopathy (ECOR). The virus is capable of inducing an acute infection in the presence of mild retinal vascular inflammation. Initial retinal damage is followed by clearance of infectious virus and progressive retinal degeneration. This is the first retinal model to demonstrate a virus induced degeneration, viral persistence, a genetic predisposition to virus induced tissue damage and a virus triggered autoimmune response. Our goal is to determine the pathophysiological mechanisms and to identify genes involved in the retinal degenerative disease. During the past year we have made the following key findings. We evaluated very early cytokine and chemokine profiles as a measure of intensity of immune reactivity in coronavirus infected mice with a retinal degeneration susceptible and a retinal degeneration resistant background. These studies identified a distinct difference in the early immune response that is generated by the two mouse strains. These differences are noted in the production of IFN-gamma and the two chemokines triggered by IFN-gamma, CXCL9 and CXCL10. At day 2 and 3 PI, BALB/c mice have high levels of IFN-gamma, CXCL9 and CXCL10 in their sera. At the same time, significantly lower levels of these molecules are detected in sera from CD-1 mice. Moreover, real time PCR analysis of retinas identified that CXCL9 and CXCL10 gene expression is significantly greater in retinas from BABL/c mice in comparison to CD-1 mice. These studies are truly exciting and identify possible mechanisms that allow the BALB/c mouse to have a robust immune response that could trigger an autoimmune component. CXCL9 and CXCL10 are potent chemokines that interact with CXCR3 present on activated T cells and NK cells. They direct the migration and stimulate the adhesion of these cells. These T cells participate in immune reactivity against infected and self targets within the retina. These chemokines have been shown to be key elements in virus infections such as HSV keratitis and SARS. In fact, in SARS, serum concentrations of CXCL10 detected early after infection is an independent prognostic indicator of disease outcome. Corneal herpes infection elicits a robust inflammatory response and eventually leads to a vision-threatening stromal keratitis as a sequela of frequent reactivation of latent virus. The aetiology of herpetic stromal keratitis is thought to be an aberrant Th1 cytokine mediated immunopathology. We evaluated HSV infection in human corneal epithelial and corneal fibroblast cells. We found that HSV DNA resulted in augmented TLR-3 and 9 gene expression and IL-6 release. As virus is frequently in the form of neutralized virus immune complexes, the ability of these immune complexes to interact with TLRs and trigger IL-6 production was evaluated. We found that HSV-anti-HSV IgG complexes were as potent as HSV DNA in their ability to induce IL-6. These phenomena were mediated via augmented TLR-3 and .9 gene expression. These studies indicate that viral DNA and/or immune complexes deposited in corneal stroma may continue to trigger stromal inflammation by excessive cytokine release via TLR3 and 9 long after the initial acute viral insult has subsided.