A High-Fat Diet Containing 50% Egg-Phosphatidylcholine Increased the Proportion of T Cells Expressing a Memory Marker in Male Wistar Rats

Abstract

ObjectivesStudies have suggested that high-fat (HF) diets are associated with immune dysfunction, which results in a lower production of IL-2 and a lower proportion of helper T cells. Providing a diet containing 100% phosphatidylcholine (PC), a form of choline mainly found in eggs, has been shown to increase IL-2 production early in life. However, this is of no relevance for human consumption since no human diet will contain 100% PC. Therefore, the objective of this study was to determine the dose effect of egg-PC added to a high fat diet compared to a control high fat and low fat diets on T cell function in male Wistar rats. MethodsAt four weeks of age, male Wistar rats were randomized to consume one of 6 diets: 1- Control low fat (CLF, 10%wt/wt fat, 100% free choline (FC), n = 10); 2- Control high fat (CHF, 25% wt/wt fat, 100% FC, n = 10); 3- 100% PCHF (100PCHF, 25% wt/wt fat, 100% PC, n = 10); 4- 75% PCHF (75PCHF, 25% wt/wt fat, 75% PC, 25% FC, n = 10); 5- 50% PCHF (50PCHF, 25% wt/wt fat, 50% PC, 50% FC, n = 10); 6- 25% PCHF (25PCHF; 25% wt/wt fat, 25% PC, 75% FC, n = 10). Fatty acid composition was closely matched in all of the diets. Anthropometric data was collected through the duration of the study (12 weeks). At the end of the study, splenocytes phenotypes were measured by flow cytometry. ResultsFrom week 1 to week 10 there was no difference in body weight between the diets. Starting from week 2 the CLF group had a higher food intake compared to the other groups. The 50PCHF diet had a higher proportion of helper T cells (CD4+) compared to the CLF and CHF diets. In addition, 50PCHF had a higher proportion of helper T cells expressing IL-2 receptors (CD4+CD25+) compared to 25PCHF (P < 0.05). 50PCHF also had a higher proportion of T cells expressing a memory marker (CD3+CD27+) compared with all HF diets (all P < 0.05) but not the CLF diet. ConclusionsOur results suggest that a diet providing 50% of total choline in the form of egg-PC normalizes the proportion of T cells expressing CD27 in the context of a HF diet which may lead to a better immune response if a second exposure to a pathogen occurs. Whether the higher proportion of helper T cells expressing the IL-2 receptor in the 50PCHF group is associated with better T cell response upon challenge remains to be investigated. Funding SourcesEgg farmers of Canada, NSERC.