Role of IL-37 Genetic Variants in Modulating Innate Immune Resp to Periodontal Pa

描述（由申请人提供）：牙周炎是对口腔细菌植物群的炎症反应，是人类最常见的感染之一。大约90%的人口表现出某种形式的早期疾病（牙龈炎），48%的美国成年人口患有牙周炎，15- 20%的人患有严重的牙周炎。牙周病是一种多基因疾病，与对牙龈生物膜的过度炎症反应相关，导致生物膜-牙龈界面处的慢性生物膜生态失调。龈沟液（GCF）白细胞介素1 β（IL-1？）水平升高先前已被确定为高炎症表型和介导严重炎症、骨丢失和牙周病进展的稳健生物标志物。我们最近完成了一项对4910名已知GCF-IL-1水平的高加索人的全基因组关联研究（GWAS），以确定与高水平GCF-IL-1相关的基因座。我们在抗炎基因IL 37的编码区发现了两个具有错义多态性的新的数量性状基因座，这两个基因座均与高GCF-IL-1水平（定义为上四分位数或连续变量）统计学显著相关，p=6.8 X10-21。在两个IL-37位点的这些错义多态性存在于30%和8.5%的人群中。这两个位点不仅与局部高IL-1水平密切相关，而且还与更严重的牙周病相关。在正常条件下，IL-37激活Smad 3并减弱对TLR激动剂的先天免疫应答，包括抑制IL-1、IL-1、TNF、IL-6、MIP-2（CXCL 2）和GM-CSF。因此，我们的中心假设是这些IL-37 SNP变体引起IL-37的功能缺陷（通过改变的mRNA剪接、蛋白质合成、活化和/或生物活性），这导致对口腔的牙周生物体的过度促炎性先天免疫应答，从而诱导更大的临床炎症、骨丢失和更严重的临床牙周病。由于小鼠不表达hIL-37的鼠同源物，我们提出了在鼠模型中的两个目的，以理解两种IL-37变体是否表现出受损的IL-37功能，即SMAD 3激活和先天免疫应答的抑制。首先，我们将用人野生型[IL 37 wt]或两种IL 37变体IL 37 v1或IL 37 v2转染鼠单核细胞RAW细胞，以评估这些突变对IL-37功能的影响，用一系列TLR激动剂刺激细胞。将在人单核细胞系THP-1中证实用IL 37 v1或IL 37 v2进行的这些实验。我们预期，与hIL-37 wt相比，变体将具有高度炎症特性，测量上面列出的介质的水平作为读数。我们还将创建IL 37变体转基因小鼠，以使用皮下腔室模型和口腔骨丢失模型测量对牙龈卟啉单胞菌攻击的反应。最后，我们将建立一个新的IL-37基因分型的受试者队列，使用分离的人PBMC和hTERT永生化细胞研究和确认这两种IL-37变体对IL-37功能和对TLR激发应答的作用。预计了解这种新变体作为与严重牙周病相关的潜在高度炎症特征的潜在原因的作用，将最终改善诊断，预防和治疗。

DESCRIPTION (provided by applicant): Periodontitis is an inflammatory response to the commensal oral bacterial flora and represents one of the most prevalent infections in humans. Approximately 90% of the population exhibits some form of early disease (gingivitis), with 48% of the US adult population having periodontitis and the severe form of the disease affecting 15-20%. Periodontal disease is a polygenic condition that is associated with an exaggerated inflammatory response to the commensal biofilm that drives chronic biofilm dysbiosis at the biofilm-gingival interface. An elevated level of gingival crevicular fluid (GCF) interleukin 1beta (IL-1¿) has previously been established as a robust biomarker for a hyper- inflammatory phenotype and for mediating severe inflammation, bone loss and periodontal disease progression. We have recently completed a genome-wide association study (GWAS) of 4910 Caucasians with known levels of GCF-IL-1¿ to identify loci that are associated with high levels of GCF-IL-1¿. We have identified two novel quantitative trait loci with missense polymorphisms within the coding region of the anti-inflammatory gene IL37 that are both statistically significanty associated with high GCF-IL-1¿ levels (defined as upper quartile or as a continuous variable), p=6.8 X10-21. These missense polymorphisms at two IL-37 loci, are present in 30% and 8.5% of the population. Not only are both loci strongly associated with high local IL-1¿ levels, but the are also associated with more severe periodontal disease. Under normal conditions IL-37 activates Smad3 and attenuates the innate immune response to TLR agonists to include suppression of IL-1¿, IL-1¿, TNF¿, IL-6, MIP-2 (CXCL2) and GM-CSF. Thus, our central hypothesis is that these IL37 SNP variants cause a functional defect in IL-37 (either via altered mRNA splicing, protein synthesis, activation and/or bioactivity) that results in an excessive pro-inflammatory innate immune response to the commensal organisms of the oral cavity, thereby inducing greater clinical inflammation, bone loss and more severe clinical periodontal disease. Since mice do not express a murine homologue to hIL-37 we propose two aims in murine models to understand whether the two IL37 variants demonstrate impaired IL-37 function I.e. SMAD3 activation and suppression of the innate immune response. First we will transfect murine monocytic RAW cells with the human wild-type [IL37wt] or the two IL37 variants, IL37v1 or IL37v2, to assess the effects of these mutations on IL-37 function, stimulating cells with a range of TLR agonists. These experiments transfecting with IL37v1 or IL37v2 will be confirmed in the human monocytic line THP-1. We expect that the variants will have a hyper-inflammatory trait compared to hIL-37wt, measuring the levels of the mediators listed above, as the read-out. We will also create IL37 variant transgenic mice to measure the response to challenge with P gingivalis using a subcutaneous chamber model and an oral bone loss model. Finally, we will establish a new IL-37 genotyped cohort of subjects to study and confirm the role of these two IL37 variants on IL-37 function and response to TLR challenge using isolated human PBMC and hTERT immortalized cells. It is expected that understanding the role of this novel variant as a potential cause of the underlying hyper-inflammatory trait associated with severe periodontal disease, will ultimately improve diagnosis, prevention and treatment.