痛风患者NLRP3炎性体基因转录剪接体的研究

Gout is a disorder about purine metabolism disorder and/or decreased uric acid excretion caused precipitation and deposition of monosodium urate (MSU) to tissue and organ. About 10% hyperuricemia progress to gout, but pathogenesis of gout is unclear. MSU are a virtual constant in acute gouty arthritis and activates NLRP3 (NLR family, pyrin domain containing 3) inflammasome to trigger inflammatory response. Our former researches discovered that expression of PYCARD [PYRIN-PAAD-DAPIN domain (PYD) and a C-terminal caspaserecruitment domain (CARD)] mRNA with gout patients was higher than healthy individuals, but both CASP1 [caspase 1, apoptosis-related cysteine peptidase (interleukin 1, beta, convertase)] and NLRP3 mRNA decreased remarkably in gout. In this project, we plan to study mRNA change of NLRP3 inflammasome in gout patients caused by expression of NLRP3、PYCARD and CASP1 transcript variants through peripheral blood mononuclear cell (PBMC) of gout patients and stimulated by MSU or lipopolysaccharide (LPS) to explore relationship between characteristic expression of NLRP3、PYCARD and CASP1 transcript variants and pathological changes of gout, to know similarities and differences of NLRP3 inflammasome activation in PBMC of MSU-stimulated gout patients and healthy individuals, and to provide a new strategy to gout for diagnosis, treatment and prevention.

痛风是血尿酸持续升高而导致尿酸盐结晶(monosodium urate, MSU)析出并沉积于组织或器官引起的一组症候群，至今其发病机制尚未完全明确。MSU存在于急性痛风性关节炎中，并且能激活核苷酸结合寡聚化结构域样受体3(NLRP3)炎性体触发炎症反应。我们前期研究发现痛风患者单个核细胞凋亡相关斑点样蛋白(PYCARD)的mRNA表达水平比健康人显著增高，而半胱天冬酶1(CASP1)和NLRP3的mRNA表达量均明显降低。本项目拟通过痛风患者以及用MSU或LPS刺激的外周血单个核细胞，研究痛风患者NLRP3炎性体mRNA表达量变是否由于特征性NLRP3、PYCARD和CASP1转录剪接体的表达引起，探索NLRP3、PYCARD和CASP1转录剪接体的表达特点与痛风病变的关系，了解MSU刺激健康人与痛风患者外周血单个核细胞NLRP3炎性体的活化异同，为痛风的诊断、治疗和预防提供新的思路。

NLRP3识别并结合尿酸盐结晶(monosodium urate, MSU)，使无活性状态的NLRP3炎性体活化，活化的NLRP3炎性体导致IL-1β和IL-18成熟和分泌而引起炎症反应，但痛风患者是否有NLRP3炎性体的转录剪接体mRNA组成异常并影响痛风的发生发展过程未见研究报道。本研究结果提示在痛风患者的PBMC中，不但有NLRP3、PYCARD、CASP1的表达量变化，而且其转录剪接体mRNA组成也表达异常，从而可能导致NLRP3、PYCARD、CASP1的蛋白量表达异常，影响痛风性关节炎的发生发展。初步研究表明miR-146a 在MSU诱导的炎症反应中表达增高，miR-146a敲除加重MSU诱导的小鼠关节炎症，miR-146a失去对TRAF6和IRAK1的靶向性抑制从而增强MSU诱导的炎症反应，miR-146a在痛风性关节能够继发性上调 NALP3炎性体表达。深入研究痛风患者NLRP3炎性体基因转录剪接体mRNA组成异常的形成过程，将有助于阐明痛风的发病机制。