Intersections of matrix biology with inflammation in a new model of gout

高尿酸血症是促进组织沉积物形成和积累的基础， 痛风是退伍军人中的一种高患病率疾病。尿酸盐结晶沉积在关节处 通过多种途径促进疼痛和失能性炎性关节炎的急性发作。最 重要是，尿酸盐晶体诱导单核细胞和巨噬细胞NLRP 3炎性小体介导的IL-1b释放， 以及吞噬细胞流入和激活。慢性炎症是急性痛风发作的基础，包括 关节痛风石，引起持续性滑膜炎和脂膜样侵蚀性关节疾病。然而，几个关键 痛风的发病机制仍不清楚。在这种情况下，无症状的高尿酸血症超过5倍， 在痛风中，关节液尿酸盐相对于血清尿酸盐富集。因此，无源滤波 进入过量循环尿酸盐的关节 不是促进组织尿酸盐晶体沉积的唯一因素， 痛风的症状性关节炎此外，除了高身体尿酸盐负担，仅限制约15%的天然因素， 痛风患者在“痛风石样痛风”中发生可触知痛风石的可能性尚不清楚。更好地理解 限制痛风石及其生物标志物，是至关重要的，因为与侵蚀性关节损伤。 为了研究新的痛风预防和治疗靶点，我们建议测试一个范式转换的核心， 通过炎症与细胞外基质稳态改变的交叉调节痛风的假说 基质O-糖蛋白边界润滑剂润滑素。我们明确指出，主要的痛风性关节炎NLRP 3/IL- 1b驱动器与润滑素的稳态相交，以增加关节尿酸盐晶体沉积，炎症， 以及痛风的疾病进展。Lubricin是一种公认的实验性痛风的组成性抑制剂 炎症我们观察到IL-1b诱导巨噬细胞产生黄嘌呤氧化酶和尿酸， 作用被外源性润滑素阻断。我们发现，润滑素显着抑制尿酸盐晶体形成在体外。 我们还对一名22岁的女性进行了一次引人注目的“自然实验”， 高尿酸血症，发展为快速进行性晶体证实的痛风，伴有经典和频繁的急性发作， 以及侵蚀性、破坏性关节炎，影响足部、手腕和臀部。先证者的可遗传NLRP 3增益为 功能变异，血清生物标志物和全血转录组的炎症特征，减弱 血清润滑素水平，以及与改变的润滑素稳态一致的集体证据。我们的模型是， 由于异质性机制，“普通痛风”中缺乏润滑素， 增加了关节中形成结晶的能力。因此我们将关节润滑 可通过注射润滑素补充剂抑制的缺乏，促进更严重的急性和慢性痛风 体内表型。具有转化影响力的研究将通过从体外转移到小鼠， 人类研究在这样做的过程中，我们将测试和比较粘蛋白，N-和C-末端结构域的要求， 润滑素，以限制尿酸盐晶体形成和巨噬细胞黄嘌呤氧化酶活性，并抑制所选择的 巨噬细胞中的痛风促炎机制。我们将检验润滑素缺乏症 促进IL-1b和尿酸晶体诱导的急性关节炎性反应的无效消退。最后， 在一个大的，横断面分析血清，我们将测试的关系，更频繁的痛风性关节炎耀斑 和痛风石样痛风与低血清润滑素水平，和某些全新的血清润滑素生物标志物 与痛风有关的体内平衡，包括润滑素降解组织蛋白酶G活性，组织蛋白酶G共激活剂 乳铁蛋白，润滑素降解蛋白酶的两种抑制剂（血小板反应蛋白1（TSP 1/THBS 1）和SERPINB 6）， 和组织蛋白酶G底物APP（淀粉样前体蛋白）。预计这项工作完成后， 阐明新的血清生物标志物，以帮助指导痛风治疗策略和强度，以及新的治疗靶点 限制尿酸盐结晶沉积、急性和慢性滑膜炎以及疾病中的关节损伤。

Hyperuricemia is fundamental in promoting the formation and accumulation of tissue deposits of monosodium urate crystals in gout, a high prevalence disease in Veterans. Urate crystals deposited in the joint promote acute, episodic flares of painful and incapacitating inflammatory arthritis by multiple pathways. Most importantly, urate crystals induce monocyte and macrophage NLRP3 inflammasome-mediated IL-1b release, and phagocyte influx and activation. Chronic inflammation lies beneath acute gout flares, including formation of articular tophi, which cause persistent synovitis and pannus-like erosive joint disease. However, several key aspects of gout pathogenesis remain unclear. In this light, asymptomatic hyperuricemia is over 5 times as prevalent than gout, and synovial fluid urate is enriched relative to serum urate in gout. Thus, passive filtering into the joint of excess circulating urate cannot be the only factor promoting tissue urate crystal deposition and symptomatic arthritis in gout. Furthermore, beyond high body urate burden, native factors that limit only ~15% of gout patients to develop palpable tophi in “tophaceous gout” are unclear. Better understanding factors that limit tophaceous gout, and their biomarkers, is vital due to association with erosive joint damage. To study novel gout prevention and therapy targets, we propose to test a paradigm-shifting core hypothesis for a gout regulation via intersection of inflammation with altered homeostasis of the extracellular matrix O-glycoprotein boundary lubricant lubricin. We specifically posit that the major gouty arthritis NLRP3/IL- 1b driver intersects with the homeostasis of lubricin to increase articular urate crystal deposition, inflammation, and disease progression in gout. Lubricin is an established, constitutive suppressor of experimental gouty inflammation. We observe that IL-1b induces xanthine oxidase and uric acid generation by macrophages, an effect blocked by exogenous lubricin. We find that lubricin markedly suppresses urate crystal formation in vitro. We also have characterized a remarkable “experiment of nature” in a 22 year old female female without hyperuricemia, who developed rapidly progressive crystal-proven gout, with classic and frequent acute flares, and erosive, destructive arthritis, affecting the feet, wrist, and hip. The proband had a heritable NLRP3 gain of function variant, an inflammatory profile of serum biomarkers and the whole blood transcriptome, attenuated serum levels of lubricin, and collective evidence consistent with altered lubricin homeostasis. Our model is that paucity of lubricin in “common gout”, due to heterogeneous mechanisms, enhances articular uric acid and increases the capacity of monosodium urate crystals to form in the joint. We thereby posit that articular lubricin deficiency, suppressible by injectable lubricin supplementation, promotes more severe acute and chronic gouty phenotypes in vivo. Translationally impactful studies will test our model by moving from in vitro to mouse to human studies. In doing so, we will test and compare mucin, and N- and C-terminal domain requirements for lubricin to limit urate crystal formation and macrophage xanthine oxidase activity, and to suppress selected gout pro-inflammatory mechanisms in macrophages. We will test the specific hypothesis that lubricin deficiency promotes ineffective resolution of IL-1b and urate crystal-induced acute articular inflammatory responses. Last, in a large, cross-sectional analysis of sera, we will test for relationships of more frequent gouty arthritis flares and tophaceous gout with low serum levels of lubricin, and certain entirely novel serum biomarkers of lubricin homeostasis pertinent to gout, including lubricin-degrading Cathepsin G activity, the Cathepsin G co-activator Lactoferrin, two inhibitors (Thrombospondin1 (TSP1/THBS1) and SERPINB6) of lubricin-degrading proteases, and the Cathepsin G substrate APP (Amyloid Precursor Protein). Completion of this work is projected to elucidate novel serum biomarkers to help guide gout treatment strategy and intensity, and new therapy targets to limit urate crystal deposition, acute and chronic synovitis, and joint damage in the disease.