The role of FcgRIIb in dendritic cell function in atherosclerosis

描述（由申请人提供）：动脉粥样硬化的一个突出特征是产生oxLDL抗体。大量研究表明oxLDL抗体具有动脉粥样硬化保护作用，但最近的证据表明B细胞反应可促进动脉粥样硬化形成。总体而言，数据表明oxLDL抗体可以调节动脉粥样硬化。这些抗体可以通过与各种免疫细胞（特别是树突细胞（DC））表面上表达的Fc受体相互作用来调节炎症。本研究的总体目标是了解oxLDL抗体如何通过调节DC功能来调节动脉粥样硬化中的炎症反应。DC在动脉粥样硬化形成中的作用尚未完全阐明。此外，虽然FcR已涉及巨噬细胞中oxLDL免疫复合物（IC）的摄取和炎症途径的调节，但oxLDL/IC通过FcR调节DC功能的作用尚未研究。我们假设a）oxLDL免疫复合物通过与FcR相互作用激活DC，以及B）抑制性FcRIIb通过下调DC对通过FcRI/III和TLR 4传递的oxLDL/IC的炎症反应来保护免受动脉粥样硬化。为了验证这一点，我们提出了以下具体目标：具体目标1。检验oxLDL-免疫复合物激活DC中促炎途径的假设。在这个目标中，我们将使用骨髓来源的DC从野生型小鼠，以确定是否在体外刺激与热聚集oxLDL/IC诱导激活的DC。具体目标2。检验抑制性FcRIIb下调DC对oxLDL-免疫复合物的炎症反应的假设。在这个目标中，我们将确定FcRIIb是否通过TLR 4和FcRI/III使用来自野生型和TLR 4-、FcRI/III-和FcRIIb-缺陷小鼠的BM衍生的髓样DC下调oxLDL/IC阳性信号传导。具体目标3。评价DC中FcR介导的信号转导在体内动脉粥样硬化免疫应答调节中的作用。为了确定FcRIIb是否通过下调体内DC活化来保护动脉粥样硬化，我们将体外产生的野生型、FcRI/III缺陷型、FcRIIb缺陷型和TLR 4缺陷型DC过继转移到CD 11 c-/-apoE-/-小鼠中。为了进一步研究FcR介导的DC功能调节在动脉粥样硬化中的作用，我们将体外用oxLDL/IC激活的DC过继转移到CD 11 c-/-apoE-/-小鼠中。 据我们所知，这是第一个研究解决免疫复合物介导的信号转导DC和动脉粥样硬化的调制。本文提出的实验将有助于阐明抗体反应oxLDL在动脉粥样硬化中的作用，解决其在DC功能。我们的研究结果将导致识别的细胞（DC）和/或分子（FcRs）治疗动脉粥样硬化的调制。 公共卫生相关性：本文提出的实验将提供数据来支持DC响应于oxLDL和/或oxLDL/IC而调节动脉粥样硬化的假设，从而潜在地导致在预防动脉粥样硬化斑块的进展中鉴定新的治疗靶点。

DESCRIPTION (provided by applicant): A prominent feature of atherosclerosis is the production of antibodies to oxLDL. Numerous studies suggest that antibodies to oxLDL can be atheroprotective, but recent evidence demonstrates that B cell responses can promote atherogenesis. Overall, the data suggest that antibodies to oxLDL can modulate atherosclerosis. These antibodies can modulate inflammation by interacting with Fc receptors expressed on the surface of various immune cells, in particular, dendritic cells (DC). The overall aim of this proposal is to understand how antibodies to oxLDL can regulate the inflammatory response in atherosclerosis by modulating DC function. The role of DC in atherogenesis has not been fully elucidated. Furthermore, while FcRs have been implicated in the uptake of oxLDL immune complexes (IC) and modulation of inflammatory pathways in macrophages, the role of oxLDL/IC in modulating DC function through FcRs has not been investigated. We hypothesized that a) oxLDL immune complexes activate DC by interacting with FcRs, and that b) the inhibitory FcRIIb protects against atherosclerosis by downmodulating DC inflammatory responses to oxLDL/IC conveyed through FcRI/III and TLR4. To test this, we propose the following specific aims: Specific Aim 1. To test the hypothesis that oxLDL-immune complexes activate a pro- inflammatory pathway in DC. In this aim, we will use bone marrow-derived DC from wild type mice to determine whether in vitro stimulation with heat-aggregated oxLDL/IC induce activation of DC. Specific Aim 2. To test the hypothesis that the inhibitory FcRIIb downregulates inflammatory responses by DC in response to oxLDL-immune complexes. In this aim we will determine whether FcRIIb downregulates oxLDL/IC positive signaling through TLR4 and FcRI/III using BM-derived myeloid DC from wild type and TLR4-, FcRI/III- and FcRIIb-deficient mice. Specific Aim 3. To evaluate the contribution of FcR-mediated signaling in DC in modulating immune responses in atherosclerosis in vivo. To determine whether FcRIIb protects against atherosclerosis by downregulating DC activation in vivo, we will adoptively transfer in vitro generated wild type, FcRI/III-deficient, FcRIIb-deficient and TLR4-deficient DC into CD11c-/-apoE-/- mice. To further investigate the role of FcR-mediated modulation of DC function in atherosclerosis, we will adoptively transfer DC that have been activated in vitro with oxLDL/IC into CD11c-/-apoE-/- mice. To our knowledge, this is the first study addressing immune complex-mediated signaling on DC and modulation of atherosclerosis. The experiments proposed herein will help elucidate the role of antibody responses to oxLDL in atherosclerosis by addressing their effect in DC function. Our results will lead to the identification of cellular (DC) and/or molecular (FcRs) therapeutics for the modulation of atherosclerosis. PUBLIC HEALTH RELEVANCE: The experiments proposed herein will provide data to support the hypothesis that DC modulate atherosclerosis in response to oxLDL and/or oxLDL/IC, potentially leading to the identification of new therapeutic targets in preventing the progression of atherosclerotic plaques.