Development of lipid therapeutics for fatty acid 2-hydroxylase deficiency

描述(申请人提供)：脑白质营养不良是一组影响髓鞘的疾病。大多数脑白质营养不良症是遗传性的，导致脑白质进行性退化。目前，还没有任何脑白质营养不良的治疗方法。这个项目的重点是最近发现的一种脑白质营养不良症，它是由脂肪酸2-羟基酶(FA2H)基因突变引起的，这种突变导致缺乏一种髓鞘脂类。由于这种疾病是由脂质缺乏引起的，因此有一种明显的可能性，即可以通过补充缺失的脂质来治疗它。这项研究的最终目标是开发合成脂质疗法，可以纠正患者髓鞘脂类的不足，从而防止白质退化。该项目是一项临床前研究，旨在利用Fa2h基因敲除小鼠模型开发潜在的脂类疗法。FA2H是一种脂质生物合成酶，负责合成主要的髓鞘鞘脂。含半乳糖的神经鞘脂脂约占髓磷脂总量的30%。超过一半的髓鞘半乳糖脂含有2-羟基脂肪酸(HFA)作为其N-酰基链(HFA-半乳糖脂)。FA2H是在髓鞘形成细胞中负责合成前体HFA的酶。FA2H缺乏导致髓鞘半乳糖脂中HFA的丢失，最终导致白质退化。如果髓鞘形成细胞被外源性提供足够的HFA，那么致残性脑白质营养不良是有可能被预防的。为了探索这种可能性，将通过饮食给Fa2h基因敲除小鼠注射合成HFA-脂类。这些实验旨在解决以下三个问题：1)HFA脂类物质被吸收了吗？2)外源性HFA是否结合到髓鞘半乳糖脂中？3)长期服用HFA类脂类物质是否会引起任何不良反应？研究将分三个阶段进行。在初始阶段，将添加各种合成三酰甘油(HFA-TAG)的碾磨饲料(HFA-TAG)饲喂断奶仔猪5天，以确定受试脂肪是否被吸收。将采集血样以确定血浆HFA水平。这些被吸收的HFA-TAG将被测试是否将HFA输送到髓鞘。在这一阶段的研究中，将饲喂添加HFA-TAG的碾磨饲料，饲喂Fa2h+/+和Fa2h/-断奶仔猪4周。在4周结束时，将对脑脂类进行分析，以确定HFA-半乳糖脂的存在。然后将对阳性化合物进行长期效果测试。如果成功，这项研究将导致潜在的治疗方法的开发，将预防和治愈FA2H缺乏引起的脑白质营养不良。 公共卫生相关性：FA2H缺乏的儿童患有毁灭性的脑白质营养不良。幸运的是，最近确定了疾病的原因：患者缺乏一种组成髓鞘的脂肪酸。该项目的目标是开发治疗方法，为患者的髓鞘提供缺失的脂肪酸，以预防和治愈疾病。

DESCRIPTION (provided by applicant): The leukodystrophies are a group of disorders that affect myelin. Most of the leukodystrophies are hereditary and cause progressive degeneration of the white matter. Currently, there are no cures for any of the leukodystrophies. The focus of this project is a recently identified leukodystrophy caused by mutations in the fatty acid 2-hydroxylase (FA2H) gene, which result in lack of a type of myelin lipids. Because this disease is caused by a lipid deficiency, there is a distinct possibility that it could be treatable by replacing the missing lipids. The ultimate goal of this study is to develop synthetic lipid therapeutics that can rectify the deficit in patients' myelin lipids, thereby preventing degeneration of the white matter. This project is a preclinical study aimed at developing potential lipid therapeutics using a Fa2h knockout mouse model. FA2H is a lipid biosynthetic enzyme responsible for the synthesis of major myelin sphingolipids. Galactose-containing sphingolipids (galactolipids) make up approximately 30% of total myelin lipids. More than half of the myelin galactolipids contain 2-hydroxy fatty acids (hFA) as their N-acyl chains (hFA-galactolipids). FA2H is the enzyme responsible for the synthesis of the precursor hFA in myelin-forming cells. FA2H deficiency results in loss of hFA in myelin galactolipids, which eventually leads to degeneration of the white matter. There is a possibility that the disabling leukodystrophy could be prevented if myelin-forming cells are exogenously provided with sufficient hFA. To explore this possibility, synthetic hFA-lipids will be administered to Fa2h- knockout mice through the diet. The experiments are designed to address the following three questions: 1) Are the hFA-lipids absorbed? 2) Are the exogenous hFA incorporated into myelin galactolipids? 3) Does long-term administration of the hFA-lipids cause any adverse effects? The study will be conducted in three phases. In the initial phase, Fa2h+/+ and Fa2h-/- weanlings will be fed milled chow supplemented with various synthetic triacylglycerols containing hFA (hFA-TAG) for 5 days to determine whether the test lipid can be absorbed. Blood samples will be collected to determine plasma hFA levels. Those hFA-TAG that are absorbed will be tested for delivery of hFA to myelin. In this phase of the study, Fa2h+/+ and Fa2h-/- weanlings will be fed milled chow supplemented with the hFA-TAG for 4 weeks. At the end of the 4-week period, brain lipids will be analyzed to determine the presence of hFA-galactolipids. Positive compounds will then be tested for long-term effects. If successful, this study will lead to development of potential therapeutics that will prevent and cure the leukodystrophy caused by FA2H deficiency. PUBLIC HEALTH RELEVANCE: Children with FA2H deficiency suffer from a devastating leukodystrophy. Fortunately, the cause of disease has recently been identified: the patients lack a type of fatty acids that make up myelin sheath. The goal of this project is to develop therapeutics to provide the missing fatty acids to patients' myelin to prevent and cure the disease.