This study investigated the immunomodulatory effects of
ferulic acid (FA) on
antigen-presenting dendritic cells (DCs) in vitro and its
antiallergic effects against
ovalbumin- (OVA-) induced Th2-mediated allergic
asthma in mice. The activation of FA-treated bone marrow-derived DCs by
lipopolysaccharide (LPS) stimulation induced a high level of
interleukin- (
IL-) 12 but reduced the expression levels of the proinflammatory
cytokines IL-1β,
IL-6, and
tumor necrosis factor- (TNF-) α. Compared to control-treated DCs, FA significantly enhanced the expressions of Notch
ligand Delta-like 4 (Dll4), MHC class II, and CD40 molecules by these DCs. Furthermore, these FA-treated DCs enhanced T-cell proliferation and Th1 cell polarization. In animal experiments,
oral administration of FA reduced the levels of OVA-specific
immunoglobulin E (
IgE) and
IgG1 and enhanced
IgG2a antibody production in serum. It also ameliorated
airway hyperresponsiveness and attenuated eosinophilic pulmonary infiltration in dose-dependent manners. In addition, FA treatment inhibited the production of eotaxin, Th2
cytokines (IL-4, IL-5, and IL-13), and proinflammatory
cytokines but promoted the Th1
cytokine interferon- (IFN-) γ production in bronchoalveolar lavage fluid (BALF) and the culture supernatant of spleen cells. These findings suggest that FA exhibits an
antiallergic effect via restoring Th1/Th2 imbalance by modulating DCs function in an asthmatic mouse model.