TIM1与TIM4对小鼠食物过敏模型中CD4+CD25+调节性T细胞功能的影响

TIM4 modulates antigen-specific Th2 cell differentiation in mice with food allergy

AIM: To evaluate the modulatory effect of microbial products on the expression of T cell immunoglobulin and mucin domain 4 (TIM4) in dendritic cells (DCs) and to determine the role of TIM4 in modulating CD4+ T cell activation in allergic response induced by exposure to microbial products.

METHODS: Bone marrow-derived DCs were isolated from Balb/c mice and cultured in vitro. Cultured DCs were divided into control group and Staphylococcal enterotoxin B (SEB)-stimulated group. The expression of TIM4 mRNA in different groups of DCs was measured by reverse transcription-polymerase chain reaction (RT-PCR). The expression of CD11c, MHC-II and CD86 on DCs were measured by flow cytometry. DCs co-cultured with CD4+ T cells in vitro were divided into five groups: control group, SEB group, OVA group, SEB plus ovalbumin (OVA) group, and anti-TIM4 antibody plus SEB and OVA group. Different sets of DCs were co-cultured for 48 h with CD4+ T cells that were obtained from the spleen of allergic mice. Levels of interleukin-4 (IL-4) and interferon-γ (IFN-γ) in culture medium were evaluated by enzyme-linked immunosorbent assay (ELISA).

RESULTS: Compared with the control group, the expression of TIM4 mRNA in DCs was increased significantly in the SEB-stimulated group (0.941 ± 0.018 vs 0.422 ± 0.083, P < 0.05), and SEB up-regulated the expression of TIM-4 in a dose-dependent manner. SEB stimulation also significantly increased the expression of MHC-II and the costimulatory molecule CD86 on DCs compared with control cells (MHC-II: 76.684% ± 3.1803% vs 52.984% ± 3.6026%, P = 0.000; CD86: 89.746% ± 2.113% vs 67.558% ± 0.4341%, P = 0.000). Compared with control DCs co-cultured with CD4+ T cells, the level of IL-4 in culture medium increased significantly (295.834 ± 20.408 vs 78.335 ± 13.109, P < 0.05) and that of IFN-γ decreased significantly (362.109 ± 92.271 vs 761.897 ± 102.967, P < 0.05) in the SEB plus OVA group. The levels of IL-4 and IFN-γ in the SEB group and OVA group showed no significant differences with those in the control group. In contrast, the expression level of IL-4 was significantly lower and that of IFN-γ was significantly higher in the anti-TIM4 antibody group than in the SEB plus OVA group (P < 0.05). The levels of IL-4 and IFN-γ in the anti-TIM4 antibody group showed no significant differences with those in the control group, SEB group and OVA group (90.511 ± 15.500 vs 295.834 ± 20.408; 807.734 ± 95.436 vs 362.109 ± 92.271, both P < 0.05).

CONCLUSION: TIM4 is involved in the pathogenesis of food allergy induced by concurrent exposure to microbial products and food antigen. Inhibition of TIM4 expression can significantly inhibit Th2 cell polarization, effectively correct Th1/Th2 imbalance and thereby prevent the development of allergic reaction.