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。当心脏跳动驱动血液循环时，淋巴运输主要依靠淋巴管泵送。淋巴泵送是由淋巴平滑肌细胞（SMC）收缩驱动的。淋巴泵送的功能是推动淋巴和细胞运输到引流淋巴结（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，它们必须离开淋巴管并深入LN以激活T细胞反应。然而，目前尚不清楚淋巴流动的变化如何影响LN中抗原的传递和递呈。在我之前的研究中，我开发了一种活体成像模型来研究小鼠的淋巴泵。使用该模型，我证明了生理状态下需要一氧化氮（NO）通过激活内皮源性一氧化氮合酶（eNOS）来维持淋巴泵送。相反，诱导型一氧化氮合酶（iNOS）负责在恶唑酮皮肤致敏诱导炎症（ox -炎症）中抑制淋巴泵送。我们假设NO调节淋巴泵送，从而调节淋巴流速和流动模式，并影响抗原在淋巴结中的传递。* * * * * *目标目标1。探讨NO如何调节淋巴SMC以控制淋巴泵送。我们将研究一氧化氮是否直接在SMC上发出信号导致SMC松弛或通过间接中断SMC和淋巴内皮细胞（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-/-小鼠阻断NOS，研究淋巴SMCs在生理和ox -炎症中的调节作用。* * *目标2。确定淋巴泵送如何控制淋巴流速和流动模式。我们将测量野生型、eNOS-/-和iNOS-/-小鼠在生理和炎症条件下的淋巴流量。我们将通过细胞培养研究淋巴流动如何调节LEC基因的表达，使用流动室在不同条件下操纵淋巴流动速度和流动模式。* * *目标3。确定淋巴泵送如何操纵抗原递送到引流淋巴结。自由形式的小抗原沿着LN导管系统移动，并迅速被淋巴结驻留树突状细胞（dc）捕获。我们将使用荧光标记的卵黄蛋白作为小抗原来测量在不同条件下淋巴泵送受损时引流LN中的抗原递送。我们将研究这些变化将如何改变LN dc捕获抗原的效率和T细胞反应的启动。***我研究的长期目标是解决淋巴泵送和淋巴运输抗原到引流淋巴结的基本问题，以便有效地呈递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.**