Mechanisms of augmented UVB immunosuppressive responses by polyaromatic hydrocarbons

摘要 人类每天都会受到多种且往往同时存在的环境压力的影响。然而，这个建筑群 这些因素的相互作用仍然是一个研究较少的领域。值得注意的是，紫外线辐射(UVR)具有深远的 对皮肤的影响，并产生全身后果，从发烧到对维生素D的免疫抑制 制作。UVR同时作为免疫抑制剂和诱变剂的能力允许这种环境因子 成为一种完全的致癌物，是非黑色素瘤皮肤癌和黑色素瘤的原因。再说了， 环境污染物多环芳烃(PAH)普遍存在，具有免疫调节作用 以及促癌作用，在很大程度上是通过充当芳烃受体(AHR)的激动剂。 然而，在紫外线和污染物之间的相互作用方面存在着很大的知识差距。特别是，作为UVB 光生物学中的一个主要问题是，UVB治疗的皮肤如何发出全身信号，这一问题仅能穿透表皮。 最近的研究表明，与膜结合的小泡称为微泡颗粒(MVP)。 细胞对各种应激源的反应所释放的物质可以作为有效的信号媒介，这是因为它们能够携带 核质成分。我们已经演示了UVB(不是UVA)通过以下方式生成MVP版本 上皮细胞和皮肤，这可能为UVB介导的全身信号提供一个潜在的机制。我们的 研究小组和其他人已经证明，UVB(而不是UVA)会产生高水平的脂质介质--血小板激活 酶促因子(PAF)和氧化型PAF激动剂(非酶促活氧) 种(ROS)。利用PAFR表达/空细胞系及其药物/遗传抑制作用的研究进展 ROS和酸性鞘磷脂酶(ASMase)参与了PAF受体的作用 (PAFR)信号导致UVB产生的MVP(UVB-MVP)中的aSMase激活。我们提供证据证明 UVB-MVP携带有生物活性的PAF激动剂，我们推测它们介导了迟发性免疫抑制效应 UVB的。重要的是，我们发现多环芳烃苯并[a]芘(BaP)与UVB的相互作用释放出高水平的 并产生更多的PAF激动剂。计划有两个目标来检验这一假设 BaP+UVR(UVA与UVB)导致ROS的协同产生，从而产生PAF和UVR-MVP 以AHR非依赖的方式增强全身免疫抑制。AIM 1将使用体外细胞系，例如 体内皮肤移植和体内小鼠遗传学和药理学模型研究BaP的作用机制 UVB-MVP和PAF生成的增强以及定义PAFR在BaP与UVR协同中的作用 可同时发射UVA和UVB光通量的模拟太阳光源(SSL)。目标2将定义增强版的角色 中波紫外线-MVP的产生及其与IL-10、转化生长因子β等细胞因子的关系 免疫抑制作用。这一项目的成功完成将(I)确定一种新的机制，通过这种机制 多环芳烃污染物可以增强紫外线诱导的效应；以及ii)解决了光生物学中的一个重要问题 角质形成细胞特异性刺激如何产生全身信号效应。

Abstract Humans are subjected daily to multiple and often simultaneous environmental stressors. Yet the complex interaction of these agents remains an understudied area. Notably, ultraviolet radiation (UVR) has profound effects on the skin and generates systemic consequences from fever to immunosuppression to vitamin D production. The ability of UVR to act as both immunosuppressant and mutagen allows this environmental agent to become a complete carcinogen and is the cause for non-melanoma skin cancer and melanoma. Besides, environmental pollutants, polycyclic aromatic hydrocarbons (PAH) are ubiquitous and exert immunomodulatory as well as pro-carcinogenic effects, in great part via acting as agonists for the aryl hydrocarbon receptor (AHR). However, there is a significant knowledge gap of interactions between UVR and pollutants. In particular, as UVB only penetrates the epidermis, a major question in photobiology is how UVB-treated skin sends systemic signals. Recent studies have indicated that small membrane-bound vesicles known as microvesicle particles (MVP) released from cells in response to various stressors can act as potent signaling agents due to their ability to carry nuclear and cytoplasmic components. We have demonstrated that UVB (not UVA) generates MVP release from epithelial cells and skin, which could provide a potential mechanism for UVB-mediated systemic signaling. Our group and others have shown that UVB (not UVA) generates high levels of the lipid mediator Platelet-activating factor (PAF) produced enzymatically and oxidized PAF agonists produced non-enzymatically via reactive oxygen species (ROS). Recent studies using PAFR-expressing/null cell lines and pharmacologic/genetic inhibition of ROS, and the enzyme acid sphingomyelinase (aSMase) have implicated the involvement of the PAF-receptor (PAFR) signaling resulting in aSMase activation in UVB generated MVP (UVB-MVP). We provide evidence that UVB-MVP carry bioactive PAF agonists, which we hypothesize mediate the delayed immunosuppressive effects of UVB. Importantly, we discovered that the PAH Benzo[a]pyrene (BaP) interaction with UVB releases high levels of UVB-MVP and generate increased levels of PAF agonists. Two aims are planned to test the hypothesis that BaP+UVR (UVA vs UVB) results in a synergistic production of ROS that generate PAF and UVR-MVP resulting in enhanced systemic immunosuppression in an AHR-independent manner. Aim 1 will use in vitro cell lines, ex vivo skin explants and in vivo murine genetic and pharmacologic models to determine the mechanisms of BaP augmentation of UVB-MVP and PAF generation as well as define PAFR role in BaP synergy with UVR using a simulated solar light (SSL) source that emits both UVA and UVB fluences. Aim 2 will define the roles of enhanced UVB-MVP generation by BaP and the involvement of Tregs and cytokines, including IL-10 and TGFβ in delayed immunosuppressive effects. Successful completion of this project will (i) define a novel mechanism by which a PAH pollutant can augment UVR-induced effects; and ii) address an important question in photobiology as to how a keratinocyte-specific stimulus can generate systemic signaling effects.