The Microbiome Drives Masts Cell Recruitment in the Skin

描述(申请人提供)：尽管肥大细胞(MC)在先天性和获得性免疫中很重要，但它们在皮肤中的发育和募集还不是很清楚。我们的发现表明，皮肤微生物群对迁移，特别是皮肤中成熟的MC有很大的影响。根据我们的初步数据，我们已经证明皮肤表面的细菌产物参与了MC抗菌功能的调节， 归巢到皮肤，帮助他们对他们的生存生长因子，干细胞因子做出反应。更重要的是，微生物组能够诱导人类MC上的抗炎表型，有助于维持皮肤动态平衡，这有助于避免不必要的炎症。抗生素暴露和伪无菌环境有可能选择性地改变皮肤微生物群，并可能是特应性皮炎等人类疾病发病率上升的原因。我们假设细菌产物增加了肥大细胞的募集，并负责维持高水平的抗菌肽(AMP)和低的促炎细胞因子谱。人源化的小鼠模型系统将能够同时研究人类MC迁移途径和TLR在遗传适应性有机体中的先天免疫反应，从而将我们的发现转化为人类皮肤。我们建议如下：a)确定正常肥大细胞的定位和功能是否需要来自皮肤微生物组的细菌产物。使用无菌和抗生素处理的小鼠将使我们能够测试正常皮肤微生物组的破坏是否会导致体内不正确的定位和功能，以及重建微生物组是否可以逆转这些影响。由于人类MC可能对微生物群具有不同的敏感性，我们将在人类MC(HuMC)上测试我们的发现，为未来的翻译研究提供基础。B)阐明负责MC感知皮肤微生物组的信号通路，以及这些通路的激活如何影响MC功能。我们将重点研究参与感知细菌副产物的MC受体的特性。有待研究的方面：1.MC受体(TLR配体)的直接共生活性，2.产生MC受体配体(SCF、IL-1和S1P)的角质形成细胞的共生活性，3.产生MC受体配体的内皮细胞(SCF)的共生活性。C)确定MC与微生物组的相互作用如何调节皮肤MC的细胞内通路并影响其功能。我们的初步数据表明，细菌副产物通过NF-kB、S1P和细胞内Sphks(Sphks)途径调节huMCs的成熟和激活，产生S1P；我们发现LTA和其他共生部分诱导特定miRNAs的表达，干扰TLR-NF-kB信号。

DESCRIPTION (provided by applicant): Despite the importance of mast cells (MCs) in innate and acquired immunity, their development and recruitment into the skin is not well understood. Our findings suggest that the skin microbiome has a strong influence on migrating and, in particular, maturing MCs in the skin. Based on our preliminary data, we have demonstrated that bacterial products at the skin surface participate in the regulation of MC antimicrobial functions, homing to the skin, and help them respond to their survival growth factor, SCF. Even more important is the ability of the microbiome to induce an anti-inflammatory phenotype on human MCs that contributes to maintaining skin homeostasis, which helps avoid unnecessary inflammation. Antibiotic exposure, and a pseudo-aseptic environment, have the potential to alter the skin microbiome selectively and may be the cause of the increasing incidence of human disorders such as atopic dermatitis. We hypothesize that bacterial products, increase mast cell recruitment and are responsible for maintaining high levels of antimicrobial peptides (AMPs) and a low pro-inflammatory cytokine profile. A humanized mouse model system will enable the simultaneous study of both human MC migration pathways and TLR innate immune responses in a genetically adaptable organism, thereby translating our findings to human skin. We propose the following: a) Determine whether bacterial products from the skin microbiome are required for normal mast cell localization and function. The use of germ free and antibiotic treated mice will allow us to test whether disruption of the normal skin microbiome results in improper localization and function in vivo and whether reconstituting the microbiome can reverse these effects. Because human MCs may have a different sensitivity to the microbiome, we will test our findings on human MCs (huMCs) to provide a foundation for future translational research. b) Clarify the signaling pathways that are responsible for MC sensing the skin microbiome and how activation of these pathways affects MC function. We will focus on characterizing the MC receptors involved in sensing bacterial byproducts. The aspects to be studied: 1. Commensal activity directly on MC receptors (TLR ligands), 2. Commensal activity on keratinocytes that generate ligands (SCF, IL-1, and S1P) for MC receptors, and 3. Commensal activity on Endothelial cells (SCF) that generate ligands for MC receptors. c) Determine how MC interaction with the microbiome modulates intracellular pathways in skin MCs and affects their function. Our preliminary data show that bacterial byproducts modulate huMCs maturation and activation through NF-kB, S1P and intracellular sphingokinases (Sphks) pathways to produce S1P; we have found that LTA and other commensal fractions induce the expression of specific miRNAs that interfere with TLR-NF-kB signaling.