Immune role of CD14+ & CD14- human skin dendritic cells

描述（由申请人提供）：外周组织驻留树突状细胞（dc）是专业抗原（Ag）呈递细胞（APCs），可启动原代T细胞免疫反应。为了实现这一目标，它们：i)吸收和处理Ags；Ii)从外周淋巴结向引流淋巴结迁移；iii)初始T细胞。除了具有强大的T细胞刺激功能外，外周组织驻地dc在稳态条件下维持外周耐受性方面起着关键作用。启动免疫或耐受的关键步骤是将初始CD4 T细胞启动并偏向于T辅助（Th） 1细胞（细胞免疫应答）、Th2细胞（体液免疫）或调节性T细胞（TR）（耐受）。dc对初始CD4 T细胞的激活和偏倚主要取决于：i) DC-T细胞突触的特性，ii) DC-T细胞接触过程中dc分泌的细胞因子的模式。外周组织DC活化过程中刺激（危险信号）的特性对DC表面T细胞刺激分子水平和DC细胞因子的模式有很大影响。例如，二硝基氯苯（DNCB）激活皮肤dc可诱导普遍的Th1反应，FITC激活dc可产生th2偏倚反应，皮肤UV-B照射有利于耐受性。相反，在没有组织损伤的情况下，触发dc从外周稳定迁移的刺激的性质仍然不清楚。此外，参与外周组织驻留dc启动T细胞反应的机制尚未在人类中进行分析。为了解决这些问题，一个离体人体皮肤移植模型将是理想的，该模型允许分析不同类型皮肤迁移（smi） dc的T细胞刺激功能以及免疫刺激（危险信号）或耐受性刺激可能对皮肤dc产生的影响。我们和其他人之前已经根据CD14分子的表达确定了两个皮肤迁移（smi） dc群体：i) smiCD14- dc，表现出成熟apc的表型和强大的幼稚T细胞刺激能力；ii)smiCD14+ dc，具有更不成熟的APC表型和较弱的幼稚T细胞刺激物。本研究拟：1)比较从人体皮肤外植体中自发动员的smiCD14+ dc和smiCD14- dc的免疫功能；2)确定暴露于DNCB （th1偏敏剂）、FITC （th2偏敏剂）或UV-B照射（tr驱动刺激）下的表皮/真皮外植体中smiCD14+ dc和smiCD14- dc的激活和功能。

DESCRIPTION (provided by applicant): Peripheral tissue-resident dendritic cells (DCs) are professional antigen (Ag) presenting cells (APCs) that initiate primary T cell immune responses. To achieve this, they: i) take up and process Ags; ii) migrate from periphery to draining lymph nodes; and iii) prime naive T cells. Besides their potent T cell stimulatory function, peripheral tissue resident-DCs play a key role in maintenance of peripheral tolerance in steady-state conditions. A crucial step for initiation of immunity or tolerance is the priming and biasing of naive CD4 T cells into T helper (Th) 1 cells (cellular immune response), Th2 cells (humoral immunity) or regulatory T cells (TR) (tolerance). Activation and biasing of naive CD4 T cells by DCs are determined mainly by: i) the characteristics of the DC-T cell synapse, and ii) the pattern of cytokines secreted by DCs during DC-T cell contact. The level of T cell stimulatory molecules on the DC surface and the pattern DC cytokines are influenced greatly by the characteristics of the stimuli (danger signals) during activation of DCs in peripheral tissues. As examples, activation of skin DCs by dinitrocholorobenzene (DNCB) induces a prevalent Th1 response, DC-activation by FITC generates a Th2-biased response and skin UV-B irradiation favors tolerance. Conversely, it is still not clear the nature of the stimuli that trigger steady migration of DCs from periphery in the absence of tissue damage. Moreover, the mechanisms involved in the initiation of T cell responses by peripheral tissue resident DCs have not been analyzed in humans. To address these questions a model of ex-vivo human skin explants that permits to analyze the T cell stimulatory function of different types of skin migratory (smi) DCs and the effect that immunostimulatorv (danger signals) or tolerogenic stimuli may exert on cutaneous DCs would be ideal. We and others have previously identified, based on the expression of the molecule CD14, two populations of skin migratory (smi)DCs: i) smiCD14- DCs, that exhibit phenotype of mature APCs and strong naive T cell stimulatory ability; and ii)smiCD14+ DCs, with a more immature APC phenotype and weak stimulators of naive T cells. In the present We propose to: 1) Compare the immune functions of smiCD14+DCs and smiCD14-DCs spontaneously mobilized from human skin explants, and 2) Determine activation and function of smiCD14+DCs and smiCD14-DCs from epidermal/dermal explants exposed to DNCB (a Th1-biasing sensitizer), FITC (a Th2-biasing sensitizer) or UV-B irradiation (TR-driving stimulus).