Graduate School of Environmental and Life Science, Okayama University, Okayama, 700-8530, Japan.
Research Faculty of Agriculture, Hokkaido University, Sapporo, 060-8589, Japan.
Mol Nutr Food Res. 2024 Aug;68(15):e2400078. doi: 10.1002/mnfr.202400078. Epub 2024 Jul 4.
Immunoglobulin A (IgA) selectively coats gut bacteria and contributes to regulatory functions in gastrointestinal inflammation and glucose metabolism. Excess intake of lard leads to decrease in the IgA coating of gut bacteria, although the underlying mechanisms remain unknown. This study validates how unabsorbed fat derived from a high-lard diet in the gut affects the IgA coating of bacteria, as assessed in mouse models using three types of dietary fat (lard, medium-, and long-chain triglycerides [MLCTs], and medium-chain triglycerides [MCTs]) exhibiting different digestibilities.
C57BL/6J mice are maintained on diets containing lard, MLCTs, or MCTs at 7% or 30% w/w for 10 weeks (n = 6 per group). The fecal fatty acid concentration is measured to quantify unabsorbed fat content. The ratio of IgA-coated bacteria to total bacteria (IgA coating ratio) in the feces is measured by flow cytometry. Compared to lard-fed mice, MLCT- and MCT-fed mice exhibit lower fecal concentrations of palmitic acid, stearic acid, and oleic acid and higher IgA coating ratios at both 7% and 30% dietary fat, and these parameters exhibit significant negative correlations.
Unabsorbed fat content in the gut may result in attenuated IgA coating of bacteria in high-lard diet-fed mice.
免疫球蛋白 A（IgA）选择性地覆盖肠道细菌，并有助于胃肠道炎症和葡萄糖代谢的调节功能。猪油的过量摄入会导致肠道细菌的 IgA 涂层减少，尽管其潜在机制尚不清楚。本研究通过使用三种不同消化率的膳食脂肪（猪油、中链和长链甘油三酯[MLCT]和中链甘油三酯[MCT]）的小鼠模型，验证了肠道中来自高脂肪饮食的未被吸收的脂肪如何影响细菌的 IgA 涂层。
C57BL/6J 小鼠分别以 7%或 30%w/w 的猪油、MLCT 或 MCT 喂养 10 周（每组 6 只）。通过测量粪便中脂肪酸的浓度来定量未被吸收的脂肪含量。通过流式细胞术测量粪便中 IgA 包被细菌与总细菌的比值（IgA 包被比）。与猪油喂养的小鼠相比，MLCT 和 MCT 喂养的小鼠在 7%和 30%的饮食脂肪水平下，粪便中棕榈酸、硬脂酸和油酸的浓度较低，IgA 包被比值较高，且这些参数呈显著负相关。
肠道中未被吸收的脂肪含量可能导致高脂肪饮食喂养的小鼠肠道细菌的 IgA 涂层减弱。
