Degree of Enzymatic Hydrolysis Determines Tolerogenic Efficacy: Partial Hydrolysis of Ovalbumin Suppresses Th2 Responses and Mast Cell Activation

Enzymatic hydrolysis effectively reduces allergenicity, yet the impact of hydrolysis degree on tolerance induction remains unclear. In this study, we evaluated the tolerogenic efficacy of ovalbumin (OVA) hydrolysates prepared by papain, alcalase, and their combination in a murine model of oral tolerance. We found that extensive hydrolysis, despite maximally reducing antigenicity, failed to induce oral tolerance. In contrast, partial hydrolysis by papain successfully prevented allergic diarrhea and systemic anaphylaxis, comparable to intact OVA. Mechanistically, this protection was associated with the preservation of CD103+ dendritic cells, which subsequently suppressed Th2 polarization, mast cell activation, and the aberrant overexpression of Gsdmc family genes in the gut. This study demonstrates that extensive enzymatic cleavage, despite enhancing safety, may compromise efficacy by destroying essential immunogenic signals. Consequently, optimizing the degree of hydrolysis is crucial for developing safe and effective hypoallergenic formulas for oral tolerance induction.