A Diet High in Lipid Soluble Forms of Choline Modulates Gut-Associated Immune Function in Sprague-Dawley Dams

Abstract

Objectives Oral tolerance is the state of unresponsiveness to dietary antigens that are not harmful to the host, a process that begins in the gut and influences both local and peripheral immune responses. Lipid soluble forms of choline have been shown to beneficial affect peripheral immune responses during pregnancy and lactation, yet little is known about the impact of the different choline forms on the gut-associate lymphoid tissue (GALT). Therefore, the objective of this study was to determine the effect of feeding buttermilk-derived choline forms on the GALT in lactating dams. Methods Sprague-Dawley dams were randomized to consume one of three diets, all containing 1.9 g/kg of total choline: 1-Control (100% free choline (FC)), 2-Buttermilk (37% phosphatidylcholine (PC), 34% sphingomyelin, 17% glycerophosphocholine (GPC), 7% FC, 5% phosphocholine) and 3-Placebo (50% PC, 25% FC, 25% GPC). Immune cell phenotypes of mesenteric lymph nodes (MLN) and Peyer's patches (PP) were measured by flow cytometry. Ex vivo cytokine production by immune cells isolated from MLN stimulated with Concanavalin A (ConA) and Ovalbumin (OVA) was measured by ELISA. Results In MLN, dams from the buttermilk and placebo groups had a higher production of IL-10 after both ConA and OVA stimulation and a higher proportion of helper T cells expressing co-inhibitory marker (CD4+CD152+) when compared to the control diet (both P < 0.05). No changes were found in IL-2, TNF-α, or IL-6 production and the proportion of regulatory T cells (CD3+CD4+CD25+FoxP3+) among groups. In PP, dams from the buttermilk group had a higher proportion of CD45RA + cells (B cells) compared to both the placebo and control diets and dams from the placebo diet had a higher proportion of dendritic cells (DC, OX62+OX6+) compared to both the buttermilk and control diets (both P < 0.05). Conclusions Compared to the control diet (only FC), the buttermilk and placebo diets appear to beneficially modulate oral tolerance by increasing the production of IL-10 (an important mediator) and could be partially explain by the higher proportion of CD4+CD152+cells in MLN. In PP, the higher proportion of B cells in the buttermilk and DC in the placebo groups, suggests that dams from these groups may have better antigen presentation function, which may further assist the induction of oral tolerance. Funding Sources Dairy Farmers of Canada, NSERC, CONACYT.