Glycyrrhiza uralensis ethanol extract inhibits dendritic cell maturation and ameliorates asthma / 国际生物医学工程杂志

ABSTRACT

Objective:To investigate the immunoregulatory effects of Glycyrrhiza uralensis ethanol extract(GUEE) on the maturation of dendritic cells (DCs) and the adjuvant effect of GUEE on OVA in na?ve BALB/c mice and an ovalbumin (OVA)-induced asthma mouse model. Methods:GUEE was prepared, and the effects of different concentrations of GUEE on the maturation of DCs and the secreted cytokines as well as the effects of GUEE on bacterial lipopolysaccharide (LPS)-induced DC maturation were examined in vitro. The effect of GUEE on the morphology of mouse bone marrow derived DCs was observed using microscopy. Molecular expression levels on the surface of DCs were detected using flow cytometry. The levels of interleukin-1β (IL-1β), IL-6, IL-12, and tumor necrosis factor-α (TNF-α) in the supernatant of DCs cultures were measured by enzyme-linked immunosorbent assay (ELISA). The maturation status of DCs was detected by flow cytometry by injecting different concentrations of GUEE into the paws of mice and isolating the draining lymph nodes 24 h later. The naive BALB/c mice were co-immunized with OVA, and the changes in regulatory T cells (Treg) were detected by flow cytometry. An OVA-protein-induced mouse asthma model was established to investigate whether GUEE as a tolerogenic adjuvant has an antigen-specific therapeutic effect on asthmatic mice. Pulmonary pathological changes were analyzed by hematoxylin-eosin staining (HE) and PAS staining. OVA-specific antibodies in serum and the frequencies of Tregs, CD4 + IFN-γ + and CD4 + IL-4 + T cells in the spleen were detected by ELISA and flow cytometry, respectively. Results:GUEE suppressed DCs maturation induced by LPS both in vitro and in vivo (all P<0.05), and reduced proinflammatory cytokine production, including IL-1β, IL-6, IL-12 and TNF-α in the absence or presence of LPS (all P<0.05). Moreover, co-immunization with OVA and GUEE increased the amount of Tregs in na?ve BALB/c mice ( P<0.05). In OVA-induced asthmatic mice, OVA and GUEE co-immunization and GUEE alone treatment substantially ameliorated the inflammation of lung tissues, decreased the levels of IgG 1 and the amount of CD4 + IL-4 + T cells, and increased the amount of Tregs (all P<0.05). Conclusions:GUEE alone or as the tolerogenic adjuvant can ameliorate allergic diseases through inhibition of DC maturation and type 2 helper T cell responses and induction of Tregs.