Dietary Lactic Acid Attenuates Ovalbumin-Induced Food Allergy in Mice via Orchestrating Dendritic Cell and T Cell Immune Tolerance.

Food allergies have become a global public health problem, but effective interventions are limited. Lactic acid (LA), a major bioactive compound in fermented foods, possesses immunomodulatory potential, but its role in food allergies is poorly defined. LA at 50, 100, and 200 mM alleviated allergic symptoms in OVA-induced allergic mice. LA suppressed type 2 immunity, with significantly reduced serum OVA-specific IgE (P < 0.0001) and mMCPT-1 by 63.6, 77.6, and 90.5% (all P < 0.0001), respectively. Upon OVA restimulation, MLNs showed significantly reduced IL-4, IL-5, and IL-13 (all P < 0.0001). LA also restored the intestinal barrier, increasing the level of Occludin-1 expression and decreasing the level of Claudin-2 expression. Mechanistically, LA targeted dendritic cells (DCs), suppressing OVA uptake and presentation by bone-marrow-derived DCs. Collectively, our study reveals that LA mitigates food allergy by reprogramming innate immune sensing by DCs to foster adaptive tolerance. This positions LA as a potent food-derived immunomodulator for the prevention of food allergy.