Role of Mast Cells in NLRP3-Mediated Skin Inflammation

描述（由申请人提供）： Cryopyrin相关的周期性综合征（CAPS）包括自身炎症性疾病家族性寒冷自身炎症性综合征（FACS）、Muckle-Wells综合征（MWS）和脑源性多系统炎性疾病（NOMID），由NLRP 3基因中的显性遗传错义突变引起。CAPS代表了疾病严重程度的连续性，从反复发作的发热和荨麻疹性皮疹到持续的全身性炎症，导致在不存在自身免疫或感染的情况下的变形性关节病和神经损伤。NLRP 3是NOD样受体（NLR）家族的成员，其参与识别微生物和内源性刺激以及激活炎症途径。包括我们自己的实验室在内的几个实验室的最新研究表明，NLRP 3通过与衔接分子ASC相互作用和炎性体的形成，对caspase-1的活化至关重要，炎性体是一种驱动caspase-1活化以及IL-12和IL-18加工和分泌的分子平台。令人惊讶的是，我们发现肥大细胞（MC）是具有NLRP 3突变的CAPS患者皮肤中成熟IL-12的主要细胞来源。与正常皮肤不同，具有NLRP 3突变的患者的真皮组成性地产生成熟的IL-12，其与急性炎性细胞的显著浸润相关。因此，我们发现MCs表达炎性小体成分并响应Toll样受体（TLR）配体和ATP或R837产生IL- 12。在NLRP 3或ASC缺陷的MC中，由LPS和ATP或R837触发的caspase-1和IL-12分泌的加工被取消。值得注意的是，来自通过同源重组将常见疾病相关的NLRP 3突变引入NLRP 3基因座的小鼠的MC在不存在ATP或R837刺激的情况下分泌成熟IL-12。这些结果表明，MCs作为哨兵在皮肤中识别环境刺激，通过激活炎性小体，这种功能是失调的CAPS患者与NLRP 3突变。本研究的目的是为了更好地了解MCs在调节IL-12和皮肤炎症以及CAPS发病机制中的作用。将采用生物化学、遗传学和细胞学方法来研究NLRP 3在MC中的功能。鉴于IL-12和MCs在免疫和炎症性疾病中的重要作用，对参与caspase-1活化和IL-12通过NLRP 3产生的机制的理解预计将在医学领域产生重大影响

DESCRIPTION (provided by applicant): Cryopyrin-associated periodic syndromes (CAPS) that include the autoinflammatory disorders familial cold autoinflammatory syndrome (FACS), Muckle-Wells syndrome (MWS), and neonatal-onset multiple-system inflammatory disease (NOMID) are caused by dominantly inherited missense mutations in the NLRP3 gene. CAPS represent a continuum of disease severity from recurrent episodes of fever and urticarial skin rash to continous systemic inflammation leading to deforming arthropathy and neurological impairment in the absence of autoimmunity or infection. NLRP3 is a member of the NOD-like receptor (NLR) family that is involved in the recognition of microbial and endogenous stimuli and activation of inflammatory pathways. Recent work from several laboratories including our own indicate that NLRP3 is critical for the activation of caspase-1 through its interaction with the adaptor molecule ASC and the formation of the inflammasome, a molecular platform that drives caspase-1 activation and processing and secretion of IL-12 and IL-18. Surprisingly, we found that mast cells (MCs) are the main cellular source of mature IL-12 in the skin of CAPS patients with NLRP3 mutations. Unlike normal skin, the dermis of patients with NLRP3 mutations produced mature IL-12 constitutively which is associated with marked infiltration of acute inflammatory cells. Consistently, we found that MCs express inflammasome components and produce IL- 12 in response to Toll-like receptor (TLR) ligands and ATP or R837. In MCs deficient in NLRP3 or ASC, processing of pro-caspase-1 and IL-12 secretion triggered by LPS and ATP or R837 was abolished. Notably, MCs from mice in which a common disease- associated NLRP3 mutation was introduced into the NLRP3 locus by homologous recombination secrete mature IL-12 in the absence of ATP or R837 stimulation. These results suggest that MCs act as sentinels in the skin for the recognition of environmental stimuli through the activation of the inflammasome and this function is dysregulated in CAPS patients with NLRP3 mutations. The goal of this proposal is to provide a better understanding of the function of MCs for the regulation of IL-12 and inflammation in the skin as well as the pathogenesis of CAPS. Biochemical, genetic, and cellular approaches will be employed to study the function of NLRP3 in MCs. Given the important role of IL-12 and MCs in immunity and inflammatory disease, understanding of the mechanisms involved in caspase-1 activation and IL-12 production via NLRP3 is expected to have a significant impact in the medical field