Racial Differences in Biomarkers and Therapeutic Targets for Chronic Itch

瘙痒或瘙痒症是一种常见的症状，在美国每年有超过700万的临床医生就诊。 美国的事实上，世界卫生组织的全球疾病负担研究将瘙痒归类为 在全球最流行的50种疾病中。瘙痒很难控制，因为治疗方法有限。 在皮肤病如特应性皮炎（AD）和结节性黑热病中， (PN)，这不成比例地影响非洲裔美国人（AA）。AD更可能是丘疹，影响伸肌 区域，与黑人相比，黑人中与聚丝蛋白功能丧失突变相关的可能性较小。 白种人本研究将探讨人类AD和PN患者的新型瘙痒受体和细胞因子谱 以提供生物标志物和未来治疗的潜在靶点。 我们的第一个目标集中在最近发现的一组瘙痒受体，称为马斯相关的G蛋白- 偶联受体（Mrs.）。在人类中，有4个Mrgpr基因（MrgprX 1 -4）。三个MrgprX的角色 已经阐明了人类的基因：MrgprX 1介导氯喹诱导的瘙痒， 影响AA，MrgprX 2是假性过敏反应的调节剂，我们最近的研究表明， MrgprX 4作为胆红素受体介导胆汁淤积性瘙痒，但MrgprX 3的功能尚不清楚。基于 初步数据显示，在病变、皮炎、PN皮肤中MrgprX 3显著上调， MrgprX 3是角质形成细胞中最高表达的Mrgpr，这一目的将决定细胞定位， PN和AD患者中MrgprX 3表达的多态性和表型差异， 瘙痒的强度和比赛。 我们的第二个目标是描述PN和AD患者IL-22细胞因子通路的上调 根据种族和痒的强度。我们的初步数据显示，Th 22相关的 与健康皮肤相比，病变PN和AD皮肤中的基因。此外，我们还发现了IL-22的强表达， 与健康对照相比，PN患者的人外周血单核细胞。所以针对本 目的：我们将在一个更大的实验室中测定血浆和外周血单核细胞中IL-22的循环水平。 PN和AD患者样本的种族和不同瘙痒强度。我们还将确定 IL-22和Th 22相关基因在PN和AD皮损中的表达和细胞定位。 最后，我们将检验MrgprX 3表达受IL-22和Th 22相关基因调控的假设。 该项目将为MrpgrX 3，IL-22的作用以及它们之间的相互作用提供重要的见解。 在非裔美国人和白人患者中，这些介质参与AD和PN的瘙痒发病机制。 重要的是，结果将与种族相关，以确定发病机制和新的治疗靶点 在特定的患者群体中。从这些研究中获得的知识将确定可能受益的患者 未来针对AD和PN瘙痒的治疗方法。

Itch, or pruritus, is a commonly reported symptom with over 7 million clinician visits annually in the United States. Indeed, the Global Burden of Disease Study by the World Health Organization categorized itch in the top 50 most prevalent diseases worldwide. Itch is difficult to manage, as there are limited therapeutics. There are also racial differences in itch in skin diseases such as atopic dermatitis (AD) and prurigo nodularis (PN), which disproportionately affect African Americans (AA). AD is more likely to be papular, affect extensor areas, and less likely to be associated with filaggrin loss-of-function mutations in blacks as compared to Caucasians. This study will investigate novel itch receptors and cytokine profiles in human AD and PN patients with respect to race to provide biomarkers and potential targets for future therapeutics. Our first aim focuses on a recently discovered group of itch receptors, known as Mas-related G protein- coupled receptors (Mrgprs). In humans, there are 4 Mrgpr genes (MrgprX1-4). A role for three of the MrgprX genes in humans has been elucidated: MrgprX1 mediates chloroquine-induced itch, which disproportionally affects AA, MrgprX2 is a regulator of pseudoallergic reactions, and our recent study demonstrated a role for MrgprX4 as a bilirubin receptor mediating cholestatic pruritus, but the function of MrgprX3 is unknown. Based on preliminary data showing dramatic upregulation of MrgprX3 in lesional, pruritic, PN skin and because MrgprX3 is the most highly expressed Mrgpr in keratinocytes, this aim will determine the cellular localization, polymorphisms, and phenotypic differences in the expression of MrgprX3 in PN and AD patients with respect to itch intensity and race. Our second aim will characterize upregulation of the IL-22 cytokine pathway in PN and AD patients according to race and itch intensity. Our preliminary data reveals significant upregulation of Th22-associated genes in lesional PN and AD skin as compared to healthy skin. Further, we found robust IL-22 expression from human blood peripheral blood mononuclear cells in PN patients as compared to healthy controls. Thus, in this aim we will determine circulating levels of IL-22 from plasma and peripheral blood mononuclear cells in a larger sample of PN and AD patients with respect to race and varying itch intensity. We will also determine the expression and cellular localization of IL-22 and Th22-associated related genes in PN and AD lesional skin. Finally, we will test the hypothesis that MrgprX3 expression is regulated by IL-22 and Th22 associated genes. This project will provide important insights into the role of MrpgrX3, IL-22, and the interplay between these mediators into the pathogenesis of itch in AD and PN in African American and Caucasian patients. Importantly, the results will be correlated with race to determine the pathogenesis and novel therapeutic targets in specific patient populations. The knowledge gained from these studies will identify patients likely to benefit from future treatments aimed at targeting itch in AD and PN.