A comprehensive evaluation of the effects of feeding cow's milk supplemented diets on gut health in aging mice

Thirty-nine Balb-c mice (20 months old) were randomly allotted to three nutritionally balanced, isocaloric and isoproteic diets. Mice were fed for 30 days, with a 22% w/w substitution of the protein content (AA mix from casein hydrolysate - diet A) or with cow's milk containing either the A1/A2 ?-casein (diet B) or the A2/A2 ?-casein (diet C). Following gut inflammatory status and gastrointestinal function were evaluated: intestinal lymphocyte subpopulations quantitation (by flow cytometry targeting CD3, CD4, CD8, CD19, CD45, panNK, TCR??, TCR??); DPP IV activity in jejunal extracts (by fluorimetric activity assay kit). Samples of duodenum and ileum were processed for histomorphological investigations. Gut morphology was evaluated through morphometric measurements of villus height (Vh), crypt depth (Cd) and villus height to crypt depth ratio (Vh/Cd). Histopathological alterations were scored using a semiquantitative scoring system (0-3). Fecal SCFA content was assessed by HPLC-UV. Data were analysed by univariate and multivariate statistics. The study gives preliminary evidences of a positive effect of diet supplementation with A2/A2 ?-casein milk on some gut health associated parameters, in aging mice. The results also suggest intriguing insights on the role of microbial SCFA on the differentiation of intestinal lymphocytes sub-populations.