Unabsorbed Fecal Fat Content Correlates with a Reduction of Immunoglobulin a Coating of Gut Bacteria in High‐Lard Diet‐Fed Mice

• Published in: Molecular nutrition & food research 2024-08, Vol.68 (15), p.e2400078-n/a
• Main Authors: Katsumata, Emiko, Tsuruta, Takeshi, Sonoyama, Kei, Yoshida, Takashi, Sasaki, Mio, Teraoka, Mao, Wang, Tianyang, Nishino, Naoki
• Format: Article
• Language: English
• Subjects: Animal models; Animals; Bacteria; Coating; Coatings; Diet; Diet, High-Fat - adverse effects; Dietary Fats; Dietary intake; Digestive system; Fat metabolism; Fatty Acids; Feces; Feces - chemistry; Feces - microbiology; Flow cytometry; Gastrointestinal Microbiome - drug effects; Gastrointestinal Microbiome - physiology; Gastrointestinal tract; Glucose metabolism; gut bacteria; High fat diet; Immunoglobulin A; Immunoglobulin A - metabolism; Immunoglobulins; lard; Male; Mice; Mice, Inbred C57BL; Oils & fats; Oleic acid; Palmitic acid; Stearic acid; Triglycerides; Triglycerides - metabolism
• ISSN: 1613-4125; 1613-4133; 1613-4133
• DOI: 10.1002/mnfr.202400078

Scope 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. Methods and results 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. Conclusion Unabsorbed fat content in the gut may result in attenuated IgA coating of bacteria in high‐lard diet‐fed mice. Gut immunoglobulin A (IgA) selectively coats gut bacteria. IgA coating of bacteria is decreased in animals maintained on high‐lard diets, compared to that in animals maintained on diets rich in medium‐ and long‐chain triglycerides (MLCTs), or in medium‐chain triglycerides (MCTs). IgA coating of gut bacteria is negatively associated with the animal's fecal content of unabsorbed palmitic, stearic, and oleic acids.