Holtick Udo, Marshall Scott R, Wang Xiao-Nong, Hilkens Catharien M U, Dickinson Anne M
Haematological Sciences, Institute of Cellular Medicine, Newcastle University, Newcastle-upon-Tyne, United Kingdom.
Transplantation. 2008 Mar 15;85(5):757-66. doi: 10.1097/TP.0b013e31816650f6.
Extracorporeal Photopheresis (ECP) has been shown to be an effective treatment of graft-versus-host disease, solid organ graft rejection, and other T-cell-mediated diseases. The mechanisms of action of ECP include lymphocyte apoptosis, cytokine modulation, and the induction of regulatory T cells. It has been suggested that dendritic cells (DCs) are more resistant to ECP-induced apoptosis and might be directly modulated by ECP. We tested this hypothesis using in vitro Psoralen/UVA (PUVA) treatment as an in vitro model of ECP.
Monocyte-derived DCs (mo-DCs) were treated with 8-methoxypsoralen /UVA and analyzed for surface molecule expression, apoptosis markers, endocytosis, and migratory and immunostimulatory capacity. Mo-DC phenotype and cytokine secretion was tested after CD40L stimulation. Naive T cells stimulated with PUVA-treated mo-DCs were tested for Th1/Th2 cytokine secretion and associated chemokine receptor patterns.
DCs underwent apoptosis after in vitro PUVA and in vivo ECP. In vitro, the induction of apoptosis was preceded by partial maturation of immature mo-DCs. PUVA-treated immature mo-DCs also exhibited enhanced migratory and immunostimulatory capacity. However, mo-DCs stimulation through CD40 ligation was abrogated and interleukin (IL)-12 secretion was abolished 24 hr after PUVA treatment. PUVA-treated mo-DCs skewed naive T cells toward a Th2 response as defined by increased IL-4, IL-10, and IL-13 and decreased interferon-gamma levels, and the expression of the Th2-associated chemokine receptors CCR4 and CCR10. The observed Th2 shift was partially reversed by exogenous IL-12.
These data suggest that direct modulation of DC function as well as apoptosis contribute to the immunoregulatory effects of ECP.
体外光化学疗法（ECP）已被证明是治疗移植物抗宿主病、实体器官移植排斥反应及其他T细胞介导疾病的有效方法。ECP的作用机制包括淋巴细胞凋亡、细胞因子调节及调节性T细胞的诱导。有人提出，树突状细胞（DC）对ECP诱导的凋亡更具抗性，且可能受到ECP的直接调节。我们使用体外补骨脂素/紫外线A（PUVA）处理作为ECP的体外模型来验证这一假设。
用8-甲氧基补骨脂素/UVA处理单核细胞来源的DC（mo-DC），并分析其表面分子表达、凋亡标志物、内吞作用以及迁移和免疫刺激能力。在CD40L刺激后检测mo-DC表型和细胞因子分泌情况。用经PUVA处理的mo-DC刺激初始T细胞，检测其Th1/Th2细胞因子分泌及相关趋化因子受体模式。
体外PUVA处理及体内ECP处理后DC发生凋亡。在体外，未成熟mo-DC先部分成熟，随后诱导凋亡。经PUVA处理的未成熟mo-DC还表现出增强的迁移和免疫刺激能力。然而，PUVA处理24小时后，通过CD40连接刺激mo-DC的能力被消除，白细胞介素（IL）-12分泌也被阻断。经PUVA处理的mo-DC使初始T细胞偏向Th2反应，表现为IL-4、IL-10和IL-13水平升高，干扰素-γ水平降低，以及Th2相关趋化因子受体CCR4和CCR10表达增加。外源性IL-12可部分逆转观察到的Th2偏移。
这些数据表明，DC功能的直接调节以及凋亡都有助于ECP的免疫调节作用。
