Effects of Forming Lactoferrin-Milk Protein Complexes on Lactoferrin Functionality and Intestinal Development in Infancy.

Background/objectives: Lactoferrin (Lf) is an iron-binding glycoprotein with multiple bioactivities, including promotion of cell proliferation and differentiation, immunomodulation, and antimicrobial activity. Lf, a basic glycoprotein, can bind to α-lactalbumin (α-Lac), an acidic whey protein. The current study aimed to evaluate whether Lf forms protein complexes with α-Lac and proteins/peptides from whey protein hydrolysate (WPH) and nonfat bovine milk powder (MP) and whether forming protein complexes influences resistance to gastrointestinal digestion and affects the bioactivities of Lf in human intestinal epithelial cells (HIECs and differentiated Caco-2 cells).

Methods: Lf was blended with α-Lac, WPH, or MP. Assays were conducted to evaluate the bioactivities of proteins (Lf, α-Lac, WPH, or MP) and Lf-protein blends on HIECs and Caco-2 cells.

Results: (1) Lf forms complexes with α-Lac and proteins/peptides from WPH and MP; (2) compared with Lf alone, complexed Lf shows greater resistance to in vitro digestion; (3) forming protein complexes does not affect Lf's binding to the Lf receptor or its uptake by HIECs; and (4) forming protein complexes does not impact Lf's bioactivities, including the promotion of cell proliferation and differentiation, reduction of cell permeability by upregulating tight-junction proteins, immune modulation through the regulation of IL-18, inhibition of enteropathogenic growth, and modulation of immune responses to EPEC infection.

Conclusions: Lf forms complexes with α-Lac and other milk proteins/peptides from WPH and MP in protein blends, and forming complexes does not affect the functionalities of Lf.