(P30-029-23) Comparing the Immunomodulatory Effect of Egg- and Soy- Derived Phosphatidylcholine Under the Context of Obesity

Objectives: Obesity is associated with a diminished immune response, despite increased systemic inflammation. Phosphatidylcholine (PC), a lipid-soluble form of choline, may support immune function through maintaining immune cell membrane integrity. PC is found in both animal sources, such as eggs, and plant sources, such as soybeans. Our group has shown that feeding PC from both plant and animal sources improves immune function in early life. However, it is unclear if PC from animal and plant sources provide similar immunomodulatory benefits under the context of obesity. Thus, the objective of this study was to determine how PC derived from eggs and soy affect immune cell function.

Methods: Male Wistar rats were randomized to consume one of 4 nutritionally complete, fatty acid composition matched diets (n=10/group) for 12 weeks, all containing 1.9g of total choline/kg of diet but differing in choline forms: 1- Control Low Fat (CLF, 20% fat, 100% free choline (FC)); 2- Control High Fat (CHF, 50% fat, 100% FC); 3- High fat Egg-derived PC (EPC, 50% fat, 100% Egg-PC); 4- High fat Soy-derived PC (SPC, 50% fat, 100% Soy-PC). Immune cell functions and phenotypes were measured in splenocytes by ex vivo cytokine production after PMA+I and pokeweed mitogen (PWM) stimulation and flow cytometry, respectively.

Results: After PMA+I stimulation, the CHF-fed rats had a lower production of IL-2 compared to the CLF group which was normalized by feeding EPC and SPC (all p > 0.05). After PWM stimulation, the CHF-fed rats had a lower production of IL-1β, IL-10 and TNF-α vs. the CLF group and feeding EPC normalized the production of IL-10 and TNF-α (all p > 0.05) while SPC did not. Both the CLF and CHF fed groups had lower proportions of B cells (CD45RA+) compared to the two PC diets (p < 0.05).

Conclusions: Our results suggest that both egg- and soy-derived PC may attenuate obesity induced T cell dysfunction while egg-PC appears to improve antigen-presenting cells function to a greater extent than soy-PC. Since the fatty acid composition of egg-PC and soy-PC molecules differ, this may explain at least in part their differential effect on immune function which will be further investigated.

Funding Sources: Egg Farmers of Canada, NSERC