SOCS1基因沉默调控树突状细胞分化并发挥抗白念珠菌适应性免疫作用的机制研究

The opportunistic infection with Candida albicans among immunocompromised patients is being increasingly paid attention. The innate immunity as well as adaptive immunity and the ability of hosts play a key role in determining occurrence, development, and outcome of the opportunistic infection. Dendritic cells (DCs) play an important role in initiating and orchestrating antifungal immunity. The suppressor of cytokine signaling-1 (SOCS1) has emerged as a critical inhibitory molecule for controlling the cytokine response and antigen presentation by DCs, thereby regulating the magnitude of both innate and adaptive immunity. Some studies suggested that lack of SOCS1 gene might enhance the ability of DCs to activate naïve T cells and induced stronger Th1-type responses both in vitro and in vivo. Our previous studies showed that SOCS1-silencing enhanced expression of CD80, CD40, CD86 and MHC II, which had the maturation phenotype; enhanced the capacity of phagocytosis and killing. In this proposal, we aim to use DC-targeting approach to delivering small interfering RNA (siRNA) against SOCS1 to murine bone marrow-DCs, and to observing the maturation/action of DC and the fine-tuning of the consecutive T-cell response in response to Candida albicans in vitro. SOCS1-silencing DC reinfusing to systemic Candida albicans infection in mice models is to observe the activation of DCs, the difference of CD4+ T cells and its role in the process of Candida albicans infection, which is expected to clarify the adaptive immune system mechanism of anti-Candida albicans and to provide a theoretical basis for future development of anti-Candida DC vaccine.

免疫受损患者的机会性念珠菌感染正日渐引起重视，宿主的先天性免疫和适应性免疫状态和能力决定着感染的发生发展和转归。树突状细胞（DC）则在其中扮演着十分重要的角色。细胞因子信号转导抑制因子-1（SOCS1），目前证实其可抑制DC的成熟；下调SOCS1的表达有利于DC的成熟，增强其免疫原性。我们的前期研究表明SOCS1沉默后DC，经白念珠菌刺激后，其表型成熟，且对白念珠菌的吞噬、杀伤能力增强。本研究拟在干扰小鼠DC的SOCS1表达基础上，先体外实验观察SOCS1沉默后DC与白念珠菌作用后，DC活性的变化及其对CD4+T细胞分化增殖和CD4+T细胞分泌细胞因子的影响。后将SOCS1沉默DC回输到小鼠白念珠菌系统性感染的模型，观察其对DC活化、CD4+T细胞分化的影响及在白念珠菌感染进程中的作用，以期明确其抗白念珠菌适应性免疫作用的机制，为今后抗念珠菌DC疫苗研制提供理论依据。

树突状细胞(Dendritic cell，DC)作为机体免疫的第一道防线，其免疫状态在白念珠菌感染过程中的作用至关重要。如何激活免疫受损患者DC对白念珠菌的免疫防御功能，是预防、治疗和控制白念珠菌病发生发展的关键之一。细胞因子信号转导抑制因子-1（Suppressors of cytokine signaling-1，SOCS1）是细胞因子信号转导通路Janus Kinase/Signal Transduction and Activators of Transcription的一个负性调控分子，目前研究证实其可抑制DC的成熟。相反，下调SOCS1基因表达有利于DC的活化成熟，增强其免疫原性。.本研究在RNA干扰技术抑制小鼠骨髓DC SOCS1基因表达的基础上，体外实验观察SOCS1基因沉默后的DC与白念珠菌作用后，DC生物活性的变化以及其对Th1、Th2、Th17、调节性T细胞活化增殖和对IFN-γ、IL-17、IL-6、IL-10、IL-12、和 TGF-β等细胞因子分泌的影响。在体实验SOCS1沉默后DC输入白念珠菌系统性感染小鼠，观察其是否具有抗白念珠菌感染作用及可能的机制。我们体外实验研究表明采用RNA干扰技术能够有效沉默DC中SOCS1在mRNA及蛋白水平的表达。SOCS1沉默后DC，经白念珠菌刺激后，DC表面分子CD40、CD80、CD86、MHC II的表达增加，其表型成熟；分泌的细胞因子IL-12、IFN-γ增加，IL-4分泌减少， IL-10、TGF-β 和 IL-6的分泌无明显变化；且其对白念珠菌的吞噬、杀伤能力增强。SOCS1沉默后的DC经白念珠菌刺激后，再与CD4+ T细胞共同孵育后，刺激CD4+ T细胞增殖；并促进CD4+ T细胞向IFN-γ-CD4+ T细胞分化，促进CD4+ T淋巴细胞向Th1型细胞分化。在体动物实验证实，SOCS1沉默后的DC可以延长系统性白念珠菌感染小鼠的生存时间，降低肾脏组织的菌载量，初步证实了SOCS1沉默后DC对小鼠系统性白念珠感染的保护性作用。.我们通过体内外实验证实，SOCS1能够有效调控DC的成熟状态，SOCS1干扰后能够提高DC的免疫原性，增强其抗白念珠菌感染的能力，SOCS1干扰后能够提高DC的免疫原性，增强其抗白念珠菌感染的能力，SOCS1沉默DC有望成为治疗白念珠菌感染的新型疫苗。