Nephrology Department, Hospital Universitari de Bellvitge, IDIBELL, Universitat de Barcelona, Barcelona, Spain.
Unitat de Bioquímica, Departament de Ciències Fisiològiques, IDIBELL, Universitat de Barcelona, Barcelona, Spain.
Int Immunopharmacol. 2021 Feb;91:107025. doi: 10.1016/j.intimp.2020.107025. Epub 2020 Dec 22.
The ability of dendritic cells (DCs) to regulate adaptive immunity makes them interesting cells to be used as therapeutic targets modulating alloimmune responses. Mycophenolic acid (MPA) is an immunosuppressor commonly used in transplantation, and its effect on DCs has not been fully investigated.
Monocyte-derived DCs were obtained from healthy volunteers and cultured for 7 days. Cells were treated with MPA on day 2 and matured by lipopolysaccharide (LPS) stimulation. Functionality of mature DC (mDCs) was evaluated by allogeneic mixed lymphocytes reaction. Surface expression of maturation markers (CD40, CD83, CD86, and ICAM-1) was analyzed in both immature DCs (iDCs) and mDCs by flow cytometry. To assess transcriptional regulation and protein subcellular location, RT-PCR and confocal microscopy were used, respectively.
MPA decreased surface expression of all maturation markers in mDCs and significantly abrogated DCs-induced allogeneic T-cell proliferation after MPA pre-treatment. In iDCs, the reduced surface protein expression after MPA paralleled with mRNA downregulation of their genes. In mDCs, the mRNA levels of ICAM-1, CD40 and CD83 were enhanced in MPA-treated mDCs with an increase in the expression of CD83 and ICAM-1 near the Golgi compared to non-treated mDCs. In contrast, mRNA levels of CD86 were diminished after MPA treatment.
The reduced surface markers expression in mDCs exerted by MPA produced a decline in their capacity to activate immune responses. Moreover, the inhibition of guanosine-derived nucleotide biosynthesis by MPA treatment leads to DC maturation interference by two mechanisms depending on the marker, transcriptional downregulation or disrupted intracellular protein trafficking.
树突状细胞 (DC) 调节适应性免疫的能力使其成为有前途的治疗靶点，可用于调节同种免疫反应。霉酚酸 (MPA) 是一种常用于移植的免疫抑制剂，但其对 DC 的作用尚未得到充分研究。
从健康志愿者中获得单核细胞来源的 DC，并培养 7 天。第 2 天用 MPA 处理细胞，并通过脂多糖 (LPS) 刺激使其成熟。通过同种异体混合淋巴细胞反应评估成熟 DC (mDC) 的功能。通过流式细胞术分析未成熟 DC (iDC) 和 mDC 中成熟标志物 (CD40、CD83、CD86 和 ICAM-1) 的表面表达。分别使用 RT-PCR 和共聚焦显微镜评估转录调节和蛋白亚细胞定位。
MPA 降低了 mDC 表面所有成熟标志物的表达，并在 MPA 预处理后显著阻断了 DC 诱导的同种异体 T 细胞增殖。在 iDC 中，MPA 后表面蛋白表达减少与它们基因的 mRNA 下调平行。在 mDC 中，与未处理的 mDC 相比，MPA 处理的 mDC 中 ICAM-1、CD40 和 CD83 的 mRNA 水平增加，并且 CD83 和 ICAM-1 靠近高尔基体的表达增加。相比之下，CD86 的 mRNA 水平在 MPA 处理后降低。
MPA 降低 mDC 表面标志物的表达导致其激活免疫反应的能力下降。此外，MPA 治疗通过两种机制抑制鸟嘌呤核苷酸生物合成，导致 DC 成熟受到干扰，这取决于标志物，即转录下调或细胞内蛋白运输中断。
