Abstract
Milk protein sensitivity is a major challenge in infant feeding, especially for infants who cannot receive adequate breastfeeding. Hydrolyzed milk protein is a mainstream way to address this difficulty. The aim of this study was to assess the effect of differences in whey protein concentrate (WPC) source and the degree of hydrolysis on blocking allergy and to analyze the possible mechanisms by which hydrolyzed infant formula (IF) blocks allergy through colony-metabolism-immunity response. First, we prepared six groups of goat's milk IF with unhydrolyzed, partially, and extensively hydrolyzed WPC, which come from cow's milk WPC and goat's milk WPC. Subsequently, we evaluated their effects on allergy. The results showed that the hydrolyzed IF improved the allergic characteristics of mice, including low levels of total immunoglobulin E (IgE), specific IgE, histamine, and mucosal mast cell protease-1 (mMCP-1). Furthermore, the hydrolyzed IF promoted the immune response of T helper 1 (Th1) and regulatory T (Treg) cells by enhancing the messenger RNA (mRNA) expression of T-box transcription factor 21 (T-bet) and forkhead box protein P3 (Foxp3), which in turn suppressed the T helper 2 (Th2) overexpressed immune response in allergy (GATA-binding protein 3 (GATA-3) and retinoic-acid-receptor-related orphan receptor gamma t (RORγt) mRNA expression, as well as interleukin 4 (IL-4) and interleukin 5 (IL-5) levels). Hydrolyzed IF promoted an increase in beneficial gut microbe Lactobacillus and Alistipes, which in turn promoted an increase in intestinal butyrate levels. The beneficial bacteria and their metabolized butyrate may have suppressed the abundance of the allergy-characterizing bacterium Rikenellaceae-RC9-gut-group. The final result we obtained was that for both cow's milk WPC and goat's milk WPC, at similar levels of hydrolysis, they did not bring about a significant effect on allergy symptoms. The hydrolyzed IF improved the allergic characteristics of mice, the deeper the degree of hydrolysis of WPC, the more obvious the effect of reducing allergic symptoms in model mice.