骨髓间充质干细胞通过PGE2调节斑秃Th17/Treg细胞平衡的治疗作用及机制研究

The pathogenesis of alopecia areata (AA) is not yet clearly understood. Without effective treatment strategy, AA corrodes patients’ self-confidence and life quality greatly severely. Bone marrow mesenchymal stem cells (BM-MSCs), a kind of multipotent stem cells exhibiting low immunogenicity and immunomodulatory potential and secreting several immunoregulatory factors, such as prostaglandin E2 (PGE2) and indoleamine 2,3-dioxygenase (IDO), can regulate the proliferation and differentiation of T cells. BM-MSCs may be a new treatment for AA. Our initial work reveled that Th17 levels were significantly higher in patients, whereas Treg levels were lower by comparison. Moreover, Th17 levels in patients with disease of short duration or in the active phase were significantly higher, relative to their respective counterparts. While Treg levels were higher in severe AA than in mild AA. In advance, we investigate the effect of Th17/Treg on human hair follicular epithelial cells. Besides, we explore the therapeutic and immunomodulatory effects of BM-MSCs on Th17/Treg cells of AA animals and compare them in different route of administration. We hypothesize that BM-MSCs might regulate the differentiation of Th17/Treg by secreting PGE2. Furthermore, we will co-incubate BM-MSCs and patients’ naive CD4+ T cells in vitro to investigate how BM-MSCs influence the differentiation, proliferation, and apoptosis of Th17/Treg cells via PGE2. Our research may provide the basis for new treatment of AA.

斑秃具体发病机制不明，治疗方法有限，严重损害生活质量。骨髓间充质干细胞除了可多向分化还具有免疫抑制的特点，分泌多种免疫调控因子，如PGE2、IDO等调节T细胞亚群的分化增殖功能，骨髓间充质干细胞或可成为斑秃免疫治疗的新手段。我们前期工作已发现斑秃患者体内存在Th17/Treg细胞免疫失衡，特别是活动期、病程短的患者Th17升高，脱发面积大者Treg增加，Th17/Treg失衡或与斑秃发病有关。本课题拟进一步观察Th17/Treg细胞对毛囊上皮细胞功能的作用。并利用间充质干细胞对斑秃动物进行治疗，观察其疗效与Th17/Treg细胞平衡的影响。我们推测间充质干细胞可通过分泌PGE2调节Th17/Treg的分化功能，进一步利用间充质干细胞及斑秃初始CD4+T细胞体外共培养实验，观察间充质干细胞通过PGE2对斑秃Th17/Treg细胞分化、分泌、增殖、凋亡的影响。为寻找新的治疗方案提供依据。

斑秃是一种自身免疫性疾病，具体发病机制不明，治疗方法有限且效果不佳。本研究检测斑秃患者外周血及皮损中Th17/Treg细胞比例、相关转录因子、细胞因子，发现斑秃患者体内存在Th17/Treg细胞免疫失衡，特别是活动期、病程短的患者Th17细胞升高，脱发面积大者Treg细胞增加。并建立C3H/HeJ斑秃小鼠模型，利用骨髓间充质干细胞（bone marrow-derived mesenchymal stem cells，BM-MSC）对斑秃动物进行治疗，发现尾静脉注射比局部皮损内注射毛发再生效果更明显。抑制前列腺素E2（Prostaglandin E2，PGE2）可以影响BM-MSC对斑秃小鼠的治疗作用，使Th17细胞比例升高。在重症斑秃CD4阳性T细胞和BM-MSC体外共培养实验中我们发现，BM-MSC可下调Th17细胞比例，上调Treg细胞。且BM-MSC对Treg细胞的增加有剂量效应，高浓度BM-MSC细胞较低浓度BM-MSC效果更明显。若在CD4阳性T细胞和BM-MSC共培养时添加PGE2抑制剂，会提高Th17细胞分化比例，降低Treg细胞比例。本课题观察到斑秃患者存在Th17/Treg细胞失衡现象，明确BM-MSC在斑秃治疗的有效性及探索有效治疗途径，并阐明BM-MSC可通过PGE2对Th17/Treg细胞失衡进行调节作用，为BM-MSC在斑秃的治疗方案提供研究基础。

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