Nociceptors are Sufficient for Cutaneous Inflammation

项目摘要 皮肤具有双重功能，作为免疫屏障和身体与皮肤之间的感觉界面。 环境对入侵病原体的保护是通过以下因素之间的协调相互作用来实现的： 皮肤中的免疫细胞，其异常活动可引起病理性炎症。越来越多的证据 证明了疼痛感应纤维或伤害感受器在皮肤免疫反应中的独特作用。简言之， 发现Trpv 1+伤害感受器是皮肤γ δ细胞产生IL-17的IL-23依赖性所必需的。 CD 4 T细胞缺乏这些伤害性感受器的小鼠更容易受到C。白色念珠菌皮肤感染， 在17型银屑病样炎症的IMQ小鼠模型中减少病理学。的要求 皮肤免疫的伤害感受器表明，神经元激活本身可能足以影响皮肤免疫。 保护性宿主防御和病理性炎症之间的平衡。为了测试伤害感受器是否足够， 皮肤炎症，我们开发了一种光遗传学小鼠模型，其允许选择性激活 具有高时间和空间精度的伤害感受器。我们发现Trpv 1+神经的激活足以 涉及IL-23、IL-6和TNFα产生以及IL-17产生T细胞浸润的皮肤炎症。 有趣的是，表达MrgprD的不同伤害感受器的激活诱导2型而不是17型的表达。 细胞因子总之，伤害感受器调节皮肤免疫的充分性突出了伤害感受器 作为治疗靶点以增强宿主防御或限制皮肤中的病理性炎症。我们假设 Trpv 1+伤害感受器的激活足以激活以CGRP激活开始的级联事件， cDC 2，其又释放诱导T细胞产生IL-17的细胞因子。我们预计这架Type-17 免疫应答将提供对表皮S.金黄色葡萄球菌感染。最后，我们假设 17型免疫的诱导对Trpv 1+伤害感受器是特异性的，而表达MrgprD的纤维的激活 就足以产生2型免疫反应我们将在三个具体目标中解决这些问题。目标1： 检验Trpv 1+伤害感受器激活驱动cDC 2分泌IL-23、IL-6和TNFα的假设。 将对Trpv 1-Ai 32（Chr 2-YFP）小鼠进行光刺激。将通过流式细胞术分析组织， IL-23、IL-6和TNFα的qPCR。最后，将产生一系列骨髓嵌合体， cDC 2的耗竭以证明功能性非冗余。目的2：检验Trpv 1 + 伤害感受器是宿主保护免受S.金黄色葡萄球菌感染。消融小鼠 的Trpv 1+伤害感受器或光刺激的Trpv 1-Ai 32小鼠将被S.金黄色。CFU 通过流式细胞术分析17型炎症的免疫参数。目标3：测试 假设MrgprD+伤害感受器足以用于2型炎症。MrgprD-Ai 32小鼠将 光遗传学活化并通过流式细胞术和mRNA表达测定2型炎症。

PROJECT SUMMARY The skin serves a dual function as an immunological barrier and a sensory interface between the body and environment. Protection against invading pathogens is accomplished by coordinated interactions between immune cells in the skin whose aberrant activity can provoke pathologic inflammation. Increasing evidence has demonstrated a unique role of pain sensing fibers, or nociceptors, in cutaneous immune responses. Briefly, Trpv1+ nociceptors were found to be required for IL-23-dependant production of IL-17 by dermal gamma delta and CD4 T-cells. Mice deficient in these nociceptors are more susceptible to C. albicans skin infection but have diminished pathology in an IMQ mouse model of Type-17 psoriasaform inflammation. The requirement of nociceptors for cutaneous immunity suggests that neuronal activation by itself may be sufficient to affect the balance between protective host defense and pathologic inflammation. To test the sufficiency of nociceptors for skin inflammation, we developed an optogenetic murine model which allows for selective activation of nociceptors with high temporal and spatial precision. We found that activation of Trpv1+ nerves is sufficient for skin inflammation involving production of IL-23, IL-6, and TNFα and infiltration of IL-17 producing T-cells. Interestingly, activation of distinct nociceptors expressing MrgprD induces expression of Type-2 but not Type-17 cytokines. Taken together, the sufficiency of nociceptors to modulate cutaneous immunity highlights nociceptors as a therapeutic target to enhance host defense or limit pathologic inflammation in the skin. We hypothesize that activation of Trpv1+ nociceptors is sufficient to activate a cascade of events starting with CGRP activation of cDC2 which in turn release cytokines that induce IL-17 production from T-cells. We anticipate that this Type-17 immune response will provide protection to epicutaneous S. aureus infection. Finally, we hypothesize that induction of Type-17 immunity is specific for Trpv1+ nociceptors whereas activation of MrgprD-expressing fibers will be sufficient for Type-2 immune responses. We will address these questions in three specific aims. Aim 1: Test the hypothesis that Trpv1+ nociceptor activation drives IL-23, IL-6 and TNFα secretion from cDC2. Trpv1-Ai32(Chr2-YFP) mice will be cutaneously photostimulated. Tissue will be analyzed by flow cytometry and qPCR for IL-23, IL-6 and TNFα. Finally, a series bone marrow chimeras will be generated allowing for the depletion of cDC2 to demonstrate functional non-redundancy. Aim 2: Test the hypothesis that Trpv1+ nociceptors are sufficient and required for host-protection against S. aureus infection. Mice with ablation of Trpv1+ nociceptors or photostimulated Trpv1-Ai32 mice will be epicutaneously infected with S. aureus. CFU and immune parameters for Type-17 inflammation will be analyzed by flow cytometry. Aim 3: Test the hypothesis that MrgprD+ nociceptors are sufficient for Type-2 inflammation. MrgprD-Ai32 mice will be optogenetically activated and assayed for Type-2 inflammation by flow cytometry and mRNA expression.