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

项目摘要/摘要 在瓣膜重塑过程中正常的心脏瓣膜结构和成分发展，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，细胞增殖减少。先天性瓣膜畸形包括 瓣膜重塑异常，如细胞外基质破坏和组织破坏。先天性心脏瓣膜 ECM基因突变和缺陷引起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，粘多糖替代和 蛋白多糖、小叶增厚和功能不全，但调节进展瓣膜的机制 退行性疾病仍然未知，也没有预防或逆转MVD的治疗方法。最近，我们的团队 正常主动脉瓣和二尖瓣中以树突状细胞为主的免疫细胞群 和髓系细胞。我们发现，在马凡综合征小鼠模型中，Fbn1C1039G/+，伴MVD的二尖瓣 瓣膜在出生后经历细胞外基质的异常成熟，并伴随着免疫细胞的增加 胶原蛋白分解和蛋白多糖膨胀的区域。发现CCR2+渗入不足。 单核细胞抑制MFS小鼠粘液瘤的发生，并使其数量减少。 巨噬细胞和瓣膜增厚减少，提示免疫原性ECM成分和免疫细胞 可能是MVD进展的关键驱动因素。基于出生后几天正常小鼠心脏瓣膜的RNA测序 7和30，树突状细胞(DC)是唯一的CCR2+免疫细胞亚群，作为TOP 20的基因标志 相关基因[6]，提示树突状细胞在瓣膜ECM重塑中的潜在作用。因此，我们假设 未成熟的Xcr1树突状细胞在二尖瓣生后ECM重塑过程中介导动态平衡 当激活时，MFS成熟，但会导致MVD进展。我们提出了两个目的来阐明这一角色 树突状细胞在ECM重构、成熟和疾病中的作用。 在目标1中，我们将确定激活的单核细胞是否足以驱动ECM重塑、成熟 在注射脂多糖(LPS)的小鼠模型中，MFS二尖瓣的MVD进展。这个 DC的定位和激活将通过评估DC激活、形态计量学ECM变化、 DC敲入小鼠模型的炎症反应。在目标2中，我们将确定二尖瓣中的Xcr1树突状细胞 是通过访问DC激活、形态计量ECM而在MFS中进行ECM重塑和MVD进展所必需的 DC敲入和敲除后的变化、炎症反应及功能和生物力学变化 小鼠与纤维蛋白1突变小鼠杂交。了解DC在MFS和疾病中对MVD的贡献 进展将推动旨在预防或逆转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.