VDD在脊柱结核感染中促进树突状细胞分泌IL-4的机制研究

Spinal tuberculosis is a major public-health problem, the pathogenesis is lined with cellular immunity. Vitamin D Deficiency (VDD) increased the expression of IL-4 secreted by dendritic cells in spinal tuberculosis, which results in the inbalance of Th1 and Th2, but the mechanism is unclear.VDR and CYP27B1 are the nuclear receptor and OHase enzyme, the expression of them depends on the vitamin D, and 1,25(OH)2D3 decreased the expression of IL-4. We guess the expression of VDR and CYP27B1 synthesised by dendritic cells was decreased under VDD condition, which cause the disorder of T cells. In this study, the serum-free medium(±vitamin D) was used to culture the DCs and was matured by BCG, the expression of VDR and CYP27B1 were tested by Western blot and Real time PCR ,and the 1,25(OH)2D3 synthesis, as estimated by thin layer chromatography; RNA interfere verified the expression of IL-4 was modulated by VDR and CYP27B1; Last,the interaction of VDR and CYP27B1 was tested by ChIP. The aim is to indentify the pathogenesis of IL-4 secreted by DCs, and provide the new clues for the treatment of tuberculosis.

脊柱结核乃影响人类健康的全球难题，其发病与细胞免疫有关。我们前期发现维生素D缺乏（VDD）在结核杆菌感染时促进树突状细胞（DC）分泌IL-4，致Th1和Th2失衡，但机制不清。VDR 和CYP27B1是维生素D与DC作用的核心受体和羟化酶，二者的表达与维生素D的多少密切相关，且1,25（OH）2D3下调IL-4的表达。推测VDD降低DC的VDR 和CYP27B1表达，致1,25（OH）2D3合成减少，IL-4上调，出现T细胞功能紊乱。本项目拟用无血清培养基（±维生素D）培养DC，BCG刺激成熟，蛋白印迹和实时PCR检测VDR 和CYP27B1的表达差异，薄层层析法检测1,25（OH）2D3合成差异；利用RNA干扰进一步证实VDR 和CYP27B1参与IL-4的调控；最后用染色体IP法检测VDR 和CYP27B1的相互作用。旨在阐明VDD影响DC分泌IL-4机制，为结核的发病机制提供新线索。