Milk fat globule membrane from cow, goat, and human differentially modulate Lacticaseibacillus rhamnosus GG: Proteomic insights from human MFGM

The milk fat globule membrane (MFGM) contains bioactive components with established immune health benefits. However, its role in modulating probiotic functionality and its species specific influence remain incompletely understood. In this study, we compared the effects of bovine, caprine and human MFGM on the probiotic strain Lactobacillus rhamnosus GG (LGG) using a cell line model. Specifically, MFGM treatment was associated with enhanced probiotic functionality, including increased adhesion to intestinal epithelial cells (∼3-4 fold), auto-aggregation (∼1.85-2.24 fold), cell surface hydrophobicity (∼9-27% increase), and co-aggregation with pathogens (∼10-27% increase), along with a ∼45% reduction in pro-inflammatory TNF-α levels in LPS-stimulated cells. Among the treatments, human MFGM consistently demonstrated the most pronounced effects across major parameters compared to the untreated LGG strain. Label-free proteomic analysis suggested that human MFGM exposure is associated with alterations in bacterial metabolic pathways, including increased abundance of proteins involved in amino acid and pyrimidine biosynthesis, alongside a reduction in proteins linked to energy-intensive processes. These alterations may contribute to enhanced stress tolerance and improved survivability. Furthermore, proteomic profiling identified MFGM-associated proteins that could modulate bacterial surface properties, thereby potentially enhancing adhesion and immunomodulatory activity; however, the observed effects may also involve additional MFGM components. Overall, these findings indicate that the species origin of MFGM is a key determinant of probiotic functionality, with human-derived MFGM exerting the most pronounced effects on LGG. Collectively, the results generate new hypotheses regarding probiotic-MFGM interactions and underscore the potential for leveraging species-specific MFGM in the development of targeted functional foods and early-life nutritional formulations.