Establishing the essentiality of fats in the postnatal diet for optimal development

我的NSERC计划的总体目标是确定饮食脂肪对产后早期免疫力的重要性。我们将研究三种特定的脂肪，二十二碳六烯酸（DHA），花生四烯酸（AA）和磷脂酰胆碱（PC），它们是免疫系统所需要的，但目前在饮食中并不被认为是必需的。哺乳期和断奶期都是免疫系统成熟和动物产生口服耐受（OT）的关键时期，即区分有害和无害口腔抗原的能力。我们已经证明，在营养充足的饮食中添加DHA或PC可以改善免疫成熟和功能。******在接下来的5年里，我的NSERC项目将重点关注4个目标：***1)确定免疫发育过程中AA的膳食重要性***2)优化免疫发育过程中AA/DHA的比例***3)确定免疫发育过程中饲粮中PC的含量。***4)确定血浆和免疫磷脂（PL）的变化作为摄入的生物标志物******我们将研究雄性和雌性Sprague-Dawley和过敏原敏感的Brown Norway大鼠在哺乳和断奶期间饲料中AA、DHA/AA比值和PC含量的变化对免疫功能的影响。在哺乳研究中，我们将通过改变幼犬的饮食来改变幼犬的摄入量。为了测试AA的重要性（低于母乳中的水平），我们将使用人工饲养模型。将使用诱导对食物蛋白卵清蛋白（OVA）的全身或粘膜耐受的方法来研究OT。诱导OT后，测定ova特异性IgE和IgG的血浆浓度。从脾脏中分离出免疫细胞并对其进行表征（通过流式细胞术），然后使用有丝分裂原或卵细胞蛋白评估其产生细胞因子（Th1或Th2模式）以应对“正常生理挑战”的能力。通过测量血浆、母乳、免疫细胞PL（含量、脂肪酸组成）和胆碱（含量、组成）的变化，我们建议鉴定预测免疫功能的生物标志物，并将为开发新型PC补充剂提供靶点。******假设：1)需要AA；2) AA:DHA的比例为1:2，可优化免疫成熟；3)从游离胆碱和PC中提取的胆碱（25:75）为最佳；4)血浆PC的含量和脂肪酸组成将成为监测LCPUFA状态与最佳免疫发育相关的理想生物标志物。******这些基础知识是建立免疫发育对这些脂质的饮食需求所必需的。此外，我们将确定预测免疫功能的生物标志物，并开发一种PC补充剂来提供所有3种脂质。我的NSERC项目将有助于在营养免疫学领域对不同类型的HPQ进行独特的培训。

The overall goal of my NSERC program is to establish the essentiality of dietary fats for immunity in the early postnatal period. We will study 3 specific fats,,docosahexaenoic acid (DHA), arachidonic acid (AA) and phosphatidylcholine (PC), for which a supply is needed by the immune system, but they are not currently considered essential in the diet. The suckling period and the weaning period are both critical stages when the immune system matures and the animal develops oral tolerance (OT), the ability to distinguish between harmful and harmless oral antigens. We have demonstrated that adding DHA or PC to otherwise nutritionally adequate diets improves immune maturation and function. ******During the next 5y, my NSERC program will focus on 4 objectives:***1) Establishing the dietary essentiality of AA during immune development ***2) Optimizing dietary AA/DHA ratio for immune development ***3) Establishing the amount of PC in the diet for immune development, then using this PC to deliver/improve the supply of long chain polyunsaturated fatty acids (LCPUFA) to immune cells ***4) Identifying the change in plasma and immune phospholipids (PL) as a biomarker of intake******Using male and female Sprague-Dawley and allergen sensitive Brown Norway rats, we will study how changes in the AA, DHA/AA ratio and the PC content of the diet influence immune function during suckling and weaning. For the suckling studies we will change pups' intake through changing their dams' diets. For testing the essentiality of AA (below levels in breast milk) we will use an artificial rearing model. OT will be studied using methods that induce systemic or mucosal tolerance to the food protein ovalbumin (OVA). After inducing OT, plasma concentrations of OVA-specific IgE and IgG are measured. Immune cells are isolated from the spleen and characterized (by flow cytometry) then used to assess their ability to produce cytokines (Th1 or Th2 pattern) to ‘normal physiological challenges' using mitogens or OVA. By measuring the change in plasma, breast milk, immune cell PL (content, fatty acid composition) and choline (content, composition) we propose to identify biomarkers that predict immune function and will provide targets for developing a novel PC supplement.******Hypothesizes: 1) AA is required; 2) a ratio of 1:2 (AA:DHA) will optimize immune maturation; 3) choline coming from free choline and PC (25:75) is optimal; and 4) the content and fatty acid composition of plasma PC will be an ideal biomarker to monitor LCPUFA status associated with optimal immune development.******This fundamental knowledge is needed to establish the dietary need of these lipids for immune development. Additionally, we will identify biomarkers that predict immune function and develop a PC supplement to provide all 3 lipids. My NSERC program will contribute to the unique training of different types of HPQ in the field of nutritional immunology.