Biochemistry and Biophysics of the Preocular Tear Film

描述(申请人提供)：干眼症(DE)及其主要形式之一-慢性后眼睑炎(CPB)-是一种广泛存在的多因素疾病，通过损害视力而降低数百万人的生活质量，特别是老年人、妇女和生活在恶劣气候中的人。高达30%的总人口受到DE的影响。目前还没有有效的治疗DE的药物，FDA批准的治疗DE和CPB的唯一药物Restasis(R)对15%的患者有效，而安慰剂组的有效率为5%。这种疾病与被称为泪膜(TF)的非常薄的富含脂肪和蛋白质的眼表结构的变化有关。我们项目的长期目标是：1)重新定义转铁蛋白的生化组成和三维结构，以及2)确定稳定或不稳定转铁蛋白的主要生化和生物物理因素，从而确定那些对体外循环和DE的发展至关重要的成分。我们的一般假设是：1)转铁蛋白的脂组成比以前认为的更精细；2)由于非常特殊的脂/脂和脂/蛋白相互作用，转铁蛋白的结构是稳定的；以及3)转铁蛋白不是完全液态的，而是具有液晶状或凝胶状结构，由逐渐插入的层和区域组成，富含特定类型的分子和超分子络合物。该项目的目标如下。目的1.通过比较MGS和AT的脂类组成，确定Tf的脂成分及其可能的来源，鉴定和评价关键脂组分在Tf的形成和维持中的作用，对目前关于人Tf主要由MGS形成的生化组成的观点提出质疑。目的2.验证以下假设：正常的转铁蛋白不是完全液态的，而是具有液晶状或凝胶状的动态纳米结构，由逐渐插入的层和区域组成，富含特定类型的分子和超分子复合体，该复合体通过脂类、蛋白质和其他分子之间的离子和亲水/疏水相互作用而稳定，其结构容易因其脂类和蛋白质组成、泪液渗透压、眼温、混合、环境因素的变化而变化。目的3.探讨体外循环患者血管紧张素转换酶(AT)脂类和微血管密度(MGS)是否存在周期性的定性和定量变化，这些变化可能与CPB患者DE症状和TF不稳定的周期性增加有关。 与公共卫生相关：干眼症(DE)及其主要形式之一--慢性后眼睑炎(CPB)--是一种广泛传播的疾病，通过损害视力严重恶化数百万人的生活质量。目前还没有有效的治疗DE的方法，FDA批准的治疗CPB的唯一处方药Restasis(R)对15%的患者有效，而安慰剂组的患者有效率为5%。这种疾病与眼前泪膜(TF)中的脂质和蛋白质的异常变化有关。该项目的目的是研究体外循环中人房水泪液和汗腺分泌物中脂质成分的生化变化以及相应的转铁蛋白的生物物理变化，以揭示其机制并开发更有效的诊断试验和治疗方法。

DESCRIPTION (provided by applicant): Dry eye (DE), and one of its major forms - chronic posterior blepharitis (CPB) - is a widespread multifactorial disease that diminishes the quality of life of millions of people, especially elderly, women, and those who live in adverse climates, by impairing their vision. Up to 30% of the general population is affected by DE. No effective treatment for DE exists at present with the only FDA-approved drug for treating DE and CPB, Restasis(R), having a therapeutic effect in 15% of patients vs. 5% in the placebo group. The disease is linked to changes in the very thin lipid- and protein rich ocular surface structure called tear film (TF). The long-term goals of our project are: 1) to redefine the biochemical composition and 3-D structure of TF, and 2) to determine the major biochemical and biophysical factors that stabilize or destabilize TF and hence those components important for the development of CPB and DE in general. Our general hypotheses are that: 1) the lipid composition of TF is more elaborate than previously thought; 2) the TF structure is stabilized due to very specific lipid/lipid and lipid/protein interactions; and, 3) TF is not quite liquid but instead has either a liquid crystal-like, or a gel-like structure and is composed of gradually intercalating layers and zones enriched with particular types of molecules and supramolecular complexes. The aims of the project are as follows. Aim 1. To challenge the current views on the biochemical composition of human TF as formed primarily of MGS by comparatively characterizing the lipids of MGS and AT, determining the lipid components of TF and their likely sources, and identifying and evaluating the roles of the critical lipid components in the formation and maintaining of TF. Aim 2. To test the hypothesis that normal TF is not quite liquid but instead has an either liquid crystal-like or a gel- like dynamic nanostructure composed of gradually intercalating layers and zones enriched with particular types of molecules and supramolecular complexes which is stabilized by ionic and hydrophilic/hydrophobic interactions between lipids, proteins, and other molecules and whose structure is susceptible to changes due to alterations in its lipid and protein compositions, tear osmolality, ocular temperature, mixing, environmental factors, etc. Aim 3. To determine whether or not there are cyclic qualitative and quantitative changes in human AT lipids and MGS that could be associated with the cyclic increase of DE symptoms and TF instability in CPB patients compared with normal subjects. PUBLIC HEALTH RELEVANCE: Dry eye syndrome (DE) in general, and one of its major forms - chronic posterior blepharitis (CPB) - is a wide- spread condition that severely deteriorates the quality of life of millions of people by impairing their vision. No effective treatment for DE exists at present with the only FDA approved prescription drug for treating CPB, Restasis(R), having a therapeutic effect in 15% of patients vs. 5% in the placebo group. The disease is related to abnormal changes in lipids and proteins in the preocular tear film (TF). The goal of the project is to investigate the biochemical changes in lipid composition of human aqueous tears and meibomian gland secretions and the corresponding biophysical changes in TF that occur in CPB in order to uncover their mechanisms and develop more effective diagnostic tests and treatments of this condition.