The role of dendritic cells in heart valve extracellular matrix remodeling, homeostasis, and disease

项目总结/摘要 正常心脏瓣膜结构和组成在瓣膜重塑过程中的发展，从晚期开始 胚胎阶段，并在出生后继续成熟。瓣膜重塑导致细胞外基质分层 (ECM)细胞密度降低和细胞增殖减少。先天性瓣膜畸形包括 瓣膜重塑异常，如ECM破坏和紊乱。先天性心脏瓣膜 由于ECM基因突变和缺陷导致的异常，常导致粘液瘤性瓣膜病（MVD）。 进行性MVD的特征是胶原纤维断裂，粘多糖替代， 蛋白多糖，小叶增厚和功能不全，但介导进行性瓣膜 然而，MVD的变性仍然是未知的，并且没有预防或逆转MVD的疗法。最近，我们集团 在正常主动脉瓣和二尖瓣中鉴定的主要由树突状细胞组成的免疫细胞群 和骨髓细胞。我们发现，在马凡氏综合征的小鼠模型中，Fbn 1C 1039 G/+，与MVD相比， 瓣膜经历ECM的异常出生后成熟，伴随着免疫细胞的增加， 胶原蛋白分解和蛋白多糖扩张的区域。结果发现，浸润性CCR 2+缺乏 单核细胞抑制MFS小鼠粘液瘤生成的进展， 巨噬细胞和减少瓣膜增厚，表明免疫原性ECM成分和免疫细胞 可能是MVD进展的关键驱动因素。基于出生后正常小鼠瓣膜的RNA测序 如图7和30所示，树突状细胞（DC）是唯一的CCR 2+免疫细胞亚群，作为前20名的基因签名 相关基因[6]，表明DC在瓣膜ECM重塑中的潜在作用。因此，我们假设 未成熟的Xcr 1 DCs介导出生后二尖瓣ECM重塑过程中的稳态， 在MFS中，当被激活时，微血管成熟但导致MVD进展。我们提出两个目标来阐明的作用 DC在ECM重塑、成熟和疾病中的作用。 在目标1中，我们将确定活化的单核细胞是否足以驱动ECM重塑、成熟和/或分化。 和注射脂多糖（LPS）的小鼠模型中MFS二尖瓣的MVD进展。的 DC的定位和活化将通过评估DC活化，形态测量ECM变化， DC基因敲入小鼠模型中的炎症反应。在目标2中，我们将确定二尖瓣中的Xcr 1 DC是否 是MFS中ECM重塑和MVD进展所必需的，通过访问DC激活，形态测量ECM DC敲入和DC敲除的变化、炎症反应以及功能和生物力学变化 小鼠与突变小鼠杂交。了解MFS和疾病中DC对MVD的贡献 进展将推进旨在预防或逆转MVD的治疗策略。

Project Summary/Abstract Normal heart valve structure and composition development during valve remodeling, starting at late embryonic stages and continues to mature postnatally. Valve remodeling results in a stratified extracellular matrix (ECM), decreased cell density and reduction in cell proliferation. Congenital valve malformations include abnormalities in valve remodeling such as ECM disruption and disorganization. Congenital heart valve abnormalities due to ECM gene mutations and defects, often lead to myxomatous valve disease (MVD). Progressive MVD is characterized by collagen fiber fragmentation, replacement of mucopolysaccharides and proteoglycans, leaflet thickening, and insufficiency, but the mechanisms mediating progressive valve degeneration remain unknown and there are no therapies to prevent or reverse MVD. Recently, our group identified immune cell populations in normal aortic and mitral valves composed of predominantly dendritic cells and myeloid cells. We found that in a murine model of Marfan Syndrome, Fbn1C1039G/+, with MVD that the mitral valve undergoes abnormal postnatal maturation of the ECM accompanied by an increase in immune cells near regions of collagen breakdown and proteoglycan expansion. It was found that deficiency of infiltrating CCR2+ monocytes inhibited the progression of myxomatous generation in MFS mice, with decreased numbers of macrophages and reduced valve thickening, suggesting that immunogenic ECM components and immune cells may be key drivers of MVD progression. Based on RNA sequencing of normal murine valves at postnatal days 7 and 30, dendritic cells (DCs) are the only CCR2+ immune cell subpopulation as a gene signature of top 20 correlated genes [6], suggesting a potential role of DCs in valvular ECM remodeling. Therefore, we hypothesize that immature Xcr1 DCs mediate homeostasis during mitral valve postnatal ECM remodeling and maturation but lead to MVD progression in MFS when activated. We propose two aims to elucidate the role of DCs in ECM remodeling, maturation and disease. In Aim 1, we will determine if activated monocytes are sufficient to drive ECM remodeling, maturation and MVD progression in MFS mitral valves in a murine model injected with Lipopolysaccharide (LPS). The localization and activate of DCs will be determined by assessing DC activation, morphometric ECM changes, inflammatory response in DC knock-in mice models. In Aim 2, we will determine if Xcr1 DCs in the mitral valves are required for ECM remodeling and MVD progression in MFS by accessing DC activation, morphometric ECM changes, inflammatory response and functional and biomechanical changes in DC knock-in and DC knockout mice crossed with fibrillin 1 mutant mice. Understanding DC contributions to MVD in MFS and disease progression will advance therapeutic strategies aimed at preventing or reversing MVD.