Synergistic Effects of Medium-chain and Omega-3 Triglycerides on Cellular Omega-3 Fatty Acid Enrichment: Characterization, Mechanisms, and Optimization

不良的炎症反应会导致细胞死亡和器官功能障碍。我们将研究急性静脉注射(IV)含有富含二十碳五烯酸(EPA)和二十二碳六烯酸(DHA)的中链甘油三酯(MCT)和omega-3(n-3)TG的脂肪乳剂是否提供了一种新的治疗方法，通过靶向快速浓缩细胞n-3FA膜来缓解不良炎症反应。N-3脂肪酸(FA)因其促进愈合和抗炎作用、抗细胞凋亡、产生自由基和促炎二十烷类化合物而日益被认为是静脉喂养的有效补充剂。在实验动物模型上的研究表明，团注n-3富含甘油三酯的乳胶颗粒(TGRP)在减少中风后脑死亡和发病率方面具有治疗保护作用。我们发现，同时含有MCT和鱼油TG(8：2wt/wt)的TGRP以n-3FA比其他TGRP更有效地富含白细胞和内皮细胞的细胞膜。利用核磁共振技术，我们报道了将MCT包含在模型TGRP中促进了模型膜脂代谢紊乱，这可能加速了n-3递送速率，突出了团注用于n-3FA浓缩的优势。然而，很少有研究涉及急性IVn-3给药的急性抗炎作用。目前，还没有关于MCT和n-3TG的最佳混合物以达到最迅速和最大幅度的抗炎作用的数据。我们的中心假设是，同时含有MCT和n-3TG的TGRPs团注将协同影响膜动力学，加速n-3FA进入细胞膜，从而启动n-3介导的抗炎和抗凋亡作用。这些将在三个具体目标下进行研究。在目标1下，我们将使用生物物理方法和基于质谱学的脂质组学相结合的方法来表征不同n-3Tg含量的含有MCT的TGRP的生物物理性质，以评估特定MCT：含有DHA和/或EPA的N-3TGRP介导的膜结构和活性的变化。在目标2中，我们将定义负责特定MCT的内化和代谢利用的细胞摄取途径：在培养的免疫效应巨噬细胞和小鼠模型中，目标1中表征的N-3 TGRP。然后，在目标3下，我们将在小鼠模型中研究MCT：N-3TGRP细胞内化如何影响单核细胞和巨噬细胞在急性免疫刺激(LPS)下的功能活动。拟议的细胞和动物模型研究将建立创新的方法，适用于将亲脂和疏水的治疗剂定向、快速地输送到特定的器官或组织。我们将发现MCT和n-3TG之间调节膜脂组成、细胞脂代谢和免疫反应的新协同作用。我们的研究将对许多领域具有很高的意义，包括对感染和炎症相关组织损伤和器官功能障碍的免疫反应。

Adverse inflammatory response leads to cell death and organ dysfunction. We will investigate whether acute intravenous (IV) treatments of lipid emulsions containing medium-chain triglycerides (TG) (MCT) and omega-3 (n-3) TG enriched in eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) provide a new therapeutic approach to ameliorate adverse inflammatory responses by targeting rapid cellular n-3 FA membrane enrichment. n-3 fatty acids (FA) are increasingly recognized as a potent supplement in IV feeding because of their pro-healing and anti-inflammatory effects against apoptosis and production of free radicals and pro- inflammatory eicosanoids. Studies in experimental animal models demonstrate that bolus injections of n-3 TG- rich emulsion particles (TGRP) are therapeutically protective in decreasing brain death and morbidity after stroke. We have discovered that TGRP containing both MCT and fish oil TG (8:2 wt/wt) enriched cell membranes of white blood cells and endothelial cells with n-3 FA more efficiently than other TGRP. Using nuclear magnetic resonance (NMR), we reported that the inclusion of MCT into model TGRP promotes model membrane lipid disorder that may accelerate n-3 delivery rates, highlighting the advantage of bolus injection for n-3 FA enrichment. However, very few studies have addressed the acute anti-inflammatory effects of acute IV n-3 administration. Currently, there is no data on optimal mixtures of MCT with n-3 TG to achieve the most rapid and highest-magnitude anti-inflammatory action. Our central hypothesis is that bolus injections of TGRPs containing both MCT and n-3 TG will cooperatively affect membrane dynamics to accelerate n-3 FA incorporation into cell membranes, which will initiate n-3-mediated anti-inflammatory and anti-apoptotic actions. These will be studied under 3 Specific Aims. Under Aim 1, we will characterize biophysical properties of MCT-containing TGRP with different n-3 TG contents using biophysical approaches coupled with mass spectrometry-based lipidomics to assess alteration in membrane structure and activity mediated by specific MCT:n-3 TGRP containing DHA, EPA, or both. In Aim 2, we will define cellular uptake pathways responsible for internalization and metabolic utilization of specific MCT:n-3 TGRP characterized in Aim 1 in cultured immune-effector macrophages and in mouse models. We will then investigate under Aim 3 how MCT:n-3 TGRP cellular internalization affects functional activities of monocytes and macrophages in response to an acute immune stimulus (LPS) in mouse models. The proposed studies in cells and animal models will establish innovative methods that are adaptable for targeted, rapid delivery of lipophilic and hydrophobic therapeutic agents to specific organs or tissues. We will uncover novel synergies between MCT and n-3 TG that modulate membrane lipid composition, cell lipid metabolism, and immune responses. Our studies will be of high significance to many fields, including immune responses to infection and inflammation-related tissue injury and organ dysfunction.