The role of FcgRIIb in dendritic cell function in atherosclerosis

描述(申请人提供)：动脉粥样硬化的一个显著特征是产生对oxLDL的抗体。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的形成。总体而言，数据表明，oxLDL的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表面表达的Fc受体相互作用来调节炎症，特别是树突状细胞(DC)。这项建议的总体目的是了解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。树突状细胞在动脉粥样硬化形成中的作用尚未完全阐明。此外，虽然FCR与巨噬细胞摄取oxLDL免疫复合体(IC)和调节炎症途径有关，但oxLDL/IC通过FCRs调节DC功能的作用尚未被研究。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FcRIIb通过FcRI/III和TLR4下调DC对oxLDL/IC的炎症反应，从而保护DC免受动脉粥样硬化的影响。为了验证这一点，我们提出了以下特定目标：特定目标1.验证oxLDL免疫复合体激活DC促炎途径的假设。为此，我们将使用野生型小鼠的骨髓来源的DC来确定热聚集的oxLDL/IC在体外刺激是否诱导DC的激活。具体目的2.验证抑制性FcRIIb下调DC对oxLDL免疫复合体的炎症反应的假设。在这一目标中，我们将确定FcRIIb是否通过TLR4和FcRI/III使用来自野生型和TLR4、FcRI/III和FcRIIb缺陷小鼠的骨髓来源的DC下调oxLDL/IC阳性信号。具体目的3.评价FCR介导的树突状细胞信号转导在动脉粥样硬化免疫反应中的作用。为了确定FcRIIb是否通过下调体内DC的激活来保护动脉粥样硬化，我们将体外产生的野生型、FcRI/III缺陷、FcRIIb缺陷和TLR4缺陷的DC过继转移到CD11c-/-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CD11c-/-apoE-/-小鼠体内。据我们所知，这是第一个关于免疫复合体介导的DC信号和动脉粥样硬化调节的研究。本文提出的实验将有助于阐明对oxLDL的抗体反应在动脉粥样硬化中的作用，因为它们在DC功能中的作用。我们的结果将有助于识别细胞(DC)和/或分子(FCR)治疗对动脉粥样硬化的调节作用。 公共卫生相关性：本文提出的实验将提供数据，支持DC响应oxLDL和/或oxLDL/IC调节动脉粥样硬化的假设，潜在地导致识别新的治疗靶点，以防止动脉粥样硬化斑块的进展。

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.