Innate Immunity in gouty Inflammation

描述（由申请人提供）：在痛风中，沉积在关节中的尿酸盐（MSU）晶体刺激急性嗜酸性炎症和慢性滑膜炎，可能导致骨和软骨破坏。MSU晶体在很大程度上通过其直接激活细胞（包括滑膜衬里细胞和吞噬细胞）的能力引发炎症。然而，惰性MSU晶体诱导痛风炎症的细胞识别因子的精确分子身份仍然不清楚。我们最近发现，先天免疫模式识别受体（PRRs）质膜TLR 2，TLR 4，和它们共同的细胞内衔接蛋白MyD 88介导的惰性，无内毒素制剂的MSU晶体在体外的细胞识别，并确定在体内的炎症潜力的MSU晶体。此外，我们观察到另一种PRR CD 14，TLR 2和TLR 4辅助分子，在体外直接结合MSU晶体，并在体内介导MSU晶体诱导的炎症反应。此外，我们现在观察到cryopyrin/NALPS，一种细胞内PRR，在促进MSU晶体诱导的体内炎症中也起重要作用。因此，本研究的中心目的是检验以下假设：特异性细胞外（CD 14、TLR 2和TLR 4）和细胞内（cryopyrin/NALP 3）先天免疫PRR的桥接协调地调节并连接细胞外接合和摄取与对MSU晶体的细胞内应答，这是痛风炎症的核心。为此，我们将从两个方面来检验这个假设。在目标1中，我们将检验CD 14、TLR 2和TLR 4对MSU晶体的细胞外接合对于MSU晶体诱导的吞噬细胞炎症反应是必不可少的这一假设。在目的2中，我们将检验两种不同的细胞内先天免疫机制支配由MSU晶体诱导的炎症反应的假设：（1）通过TLR衔接蛋白MyD 88的典型TLR 2和TLR 4信号传导导致NF-κ B调节的炎症细胞因子的表达。(2)cryopyrin/NALPS炎性体途径依赖于内化的（MSU晶体结合的）CD 14、TLR 2或TLR 4的MyD 88非依赖性细胞内参与介导IL-1 β成熟和分泌这项工作的完成将有助于进一步了解急性痛风性炎症的机制，如何控制痛风性关节炎和潜在的其他形式的晶体诱导的炎症。

DESCRIPTION (provided by applicant): In gout, monosodium urate (MSU) crystals deposited in the joint stimulate both acute neutrophilic inflammation and chronic synovitis that may lead to bone and cartilage destruction. MSU crystals trigger inflammation in large part via their capacity to directly activate cells, including synovial lining cells and phagocytes. However, the precise molecular identity of the cell recognition factors for inert MSU crystals to induce gouty inflammation has remained unclear. We recently discovered that the innate immune pattern recognition receptors (PRRs) plasma membrane TLR2, TLR4, and their common intracellular adapter protein MyD88 mediate cellular recognition of inert, endotoxin-free preparations of MSU crystals in vitro, and determine the inflammatory potential of MSU crystals in vivo. In addition, we observed that another PRR CD14, the TLR2 and TLR4 accessory molecule, directly binds MSU crystals in vitro, and mediates MSU crystal-induced inflammatory responses in vivo. Moreover, we now observe that cryopyrin/NALPS, an intracellular PRR, also plays an important role in promoting MSU crystal-induced inflammation in vivo. Thus, the central objective of this study is to test the hypothesis that the bridging of specific extracellular (CD14, TLR2, and TLR4) and intracellular (cryopyrin/NALP3) innate immune PRRs coordinately transduce and link extracellular engagement and uptake to intracellular responses to MSU crystals, which are central to gouty inflammation. To do so, we will test the hypothesis in two aims. In aim 1, we will test the hypothesis that extracellular engagement of MSU crystals by CD14, TLR2, and TLR4 is essential for MSU crystal-induced inflammatory responses in phagocytes. In Aim 2, we will test the hypothesis that two distinct intracellular innate immune mechanisms govern inflammatory responses induced by MSU crystals: (1) canonical TLR2 and TLR4 signaling through the TLR adapter protein MyD88 leads to expression of NF-kappaB regulated inflammatory cytokines. (2) MyD88-independent intracellular engagement of the cryopyrin/NALPS inflammasome pathway dependent on internalized (MSU crystal-bound) CD14, TLR2 or TLR4 mediates IL-1beta maturation and seretion. Completion of this work will help further understanding the mechanisms of acute gouty inflammation, how to control gouty arthritis and potentially other forms of crystal-induced inflammation.