# Milk Fat Globule Membrane-Containing Protein Powder Promotes Fitness in Caenorhabditis elegans

## TL;DR

A milk protein powder boosts fitness in worms but weakens their immune response, possibly through a gene linked to human cathepsin B.

## Contribution

Shows MProPow improves worm fitness by downregulating cpr-3, a gene related to human cathepsin B.

## Key findings

- MProPow does not affect lifespan but increases worm fitness.
- MProPow reduces innate immunity gene expression and survival on pathogenic bacteria.
- cpr-3 knockdown boosts fitness, but not in MProPow-treated worms.

## Abstract

Milk-derived peptides and milk fat globule membrane (MFGM) have gained interest as health-promoting food ingredients. However, the mechanisms by which these nutraceuticals modulate the function of biological systems often remain unclear. We utilized Caenorhabditis elegans to elucidate how MFGM-containing protein powder (MProPow), previously used in a clinical trial, affect the physiology of this model organism. Our results demonstrate that MProPow does not affect lifespan but promotes the fitness of the animals. Surprisingly, gene expression analysis revealed that MProPow decreases the expression of genes functioning on innate immunity, which also translates into reduced survival on pathogenic bacteria. One of the innate immunity-associated genes showing reduced expression upon MProPow supplementation is cpr-3, the homolog of human cathepsin B. Interestingly, knockdown of cpr-3 enhances fitness, but not in MProPow-treated animals, suggesting that MProPow contributes to fitness by downregulating the expression of this gene. In summary, this research highlights the value of C. elegans in testing the biological activity of food supplements and nutraceuticals. Furthermore, this study should encourage investigations into whether milk-derived peptides and MFGM mediate their beneficial effects through the modulation of cathepsin B expression in humans.