Lymphatic pumping and lymphatic transport of antigen to lymph node

淋巴管在维持体液平衡和促进免疫防御方面起着重要作用。虽然心脏跳动以驱动血液循环，但淋巴输送主要依赖于淋巴管泵送。淋巴泵由淋巴平滑肌细胞（SMC）收缩驱动。淋巴泵的功能是推动淋巴和细胞转运到引流淋巴结（LN）。当抗原和树突状细胞通过传入淋巴管到达引流淋巴结（LN）时，它们必须离开血管并迁移到LN深处以激活T细胞应答。然而，目前尚不清楚淋巴流量的变化如何影响LN中的抗原递送和抗原呈递。在我以前的研究中，我开发了一种活体成像模型来研究小鼠的淋巴泵。使用这个模型，我证明了一氧化氮（NO）是需要通过激活内皮源性一氧化氮合酶（eNOS），以维持淋巴泵在生理条件下。相反，诱导型一氧化氮合酶（iNOS）负责抑制恶唑酮皮肤致敏诱导的炎症（OX-炎症）中的淋巴泵。我们假设NO调节淋巴泵，从而调节淋巴流速和流动模式，并影响淋巴结中的抗原递送。* 具体目标 **探讨NO是如何调节淋巴管SMC从而控制淋巴泵的。我们将研究NO是否直接作用于SMC引起SMC松弛或通过间接阻断SMC与淋巴管内皮细胞（LEC）的相互作用。我们将使用eNOS-/-小鼠，或广泛的NOS抑制剂L-NMMA或iNOS-/-小鼠来阻断NOS，并研究淋巴SMC在生理和OX炎症中如何调节。* 目标2。确定淋巴泵如何控制淋巴流速和流动模式。我们将在生理和炎症条件下测量野生型、eNOS-/-和iNOS-/-小鼠的淋巴流量。我们将研究淋巴流如何调节LEC基因的表达与细胞培养，使用流动室来操纵淋巴流速和流动模式在不同的条件下。 * 目标3。确定淋巴泵如何操纵抗原递送到引流LN。游离形式的小抗原沿着LN导管系统行进，并被淋巴结驻留树突状细胞（DC）快速捕获。我们将使用荧光标记的卵白蛋白作为小抗原来测量在不同条件下淋巴泵受损时引流LN中的抗原递送。我们将研究这些变化将如何改变LN DC的抗原捕获效率和T细胞应答的启动。* 我研究的长期目标将解决淋巴泵送和抗原淋巴运输到引流淋巴结的基本问题，以便有效地呈现抗原并产生免疫防御。**

Lymphatic vessels play essential roles in maintaining fluid balance and facilitating immune defense. While the heart beats to drive blood circulation, lymph transport primarily relies on lymphatic vessel pumping. Lymphatic pumping is driven by lymphatic smooth muscle cell (SMC) contraction. The function of lymphatic pumping is to propel lymph and cells transport to the draining lymph node (LN). When antigen and dendritic cells reach the draining lymph node (LN) through afferent lymphatic vessels, they must exit the vessels and migrate deep into the LN to activate T cell responses. However, it is not clear how changes in lymph flow may affect antigen delivery and antigen presentation in LN. In my previous studies, I have developed an intravital imaging model to study lymphatic pumping in mice. Using this model, I demonstrated that nitric oxide (NO) is required to maintain lymphatic pumping in physiological condition via the activation of the endothelial-derived nitric oxide synthase (eNOS). In contrast, the inducible nitric oxide synthase (iNOS) is responsible for the inhibition of lymphatic pumping in oxazolone skin sensitization induced inflammation (OX-inflammation). We hypothesize that NO regulates lymphatic pumping, which consequently modulates lymph flow velocity and flow pattern, and affect antigen delivery in lymph node. ***OBJECTIVES***Objective 1. To determine how NO regulates lymphatic SMC to control lymphatic pumping. We will study if NO directly signals on SMCs to cause SMC relaxation or via indirectly interrupt SMC and lymphatic endothelial cell (LEC) interaction. We will use eNOS-/- mice, or broad NOS inhibitor L-NMMA or iNOS-/- mice to block NOSs and study how lymphatic SMCs are regulated in physiological and OX-inflammation. ***Objective 2. To determine how lymphatic pumping controls the lymph flow velocity and flow pattern. We will measure the lymph flow in wild type, eNOS-/- and iNOS-/- mice in physiological and inflammatory conditions. We will study how lymph flow regulated LEC gene expression with cell culture using flow chamber to manipulate lymph flow velocity and flow pattern in variant conditions. ***Objective 3. To determine how lymphatic pumping manipulates antigen delivery to the draining LN. Free form of small antigens travel along the LN conduit system and are quickly captured by lymph node resident dendritic cells (DCs). We will use fluorescently labeled ovabulmin as small antigen to measure the antigen delivery in the draining LN when lymphatic pumping is impaired in variant conditions. We will study how these changes will alter the efficiency of antigen capture by LN DCs and initiation of T cell responses. ***The long-term goal of my studies will address fundamental questions of lymphatic pumping and lymphatic transport of antigen to the draining lymph node in order to efficiently present antigen and generate immune defense.**