The role of lymphatic clearance in brain TB

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PROJECT SUMMARY/ABSTRACT Brain tuberculosis (TB), the most severe form of tuberculosis, is associated with a complex inflammatory response, tissue damage and cerebral edema. Typically, management of fluid, waste, and immune- surveillance in the periphery is performed by tissue infiltrating lymphoid vessels. While the brain parenchyma does not have lymphoid vessels, recent research has identified that brain fluids (cerebrospinal fluid and interstitial fluid) are collected by meningeal and cribriform lymphoid vessels surrounding the brain, which are crucial for waste clearance and tissue homeostasis in the CNS. It has been shown that inhibition of lymphatic transport accelerates disease pathology and cognitive decline in Alzheimer’s disease, traumatic brain injury, and Parkinson’s disease, but little is known about the potential modulatory role of lymphoid vessels in CNS tuberculosis. Recently we reported that autoimmune inflammation induces lymphangiogenesis at the cribriform plate through the production of VEGFC from inflammatory dendritic cells. Functionally, the induction of new lymphoid vessels upregulates immunoregulatory molecules, and blocking new lymphoid vessel formation has consequences in regulating the severity of the autoimmune disease. In this proposal, we will test how CNS tuberculosis affects meningeal and cribriform lymphoid vessels formation and consequently, their fluid and cell draining function (Aim 1) To understand the impacts on immune-surveillance, we will study how CNS mycobacterial tuberculosis (Mtb) infection alters the expression of immune regulatory molecules on draining lymphoid vessels and how these lymphoid vessels modify brain-derived dendritic cells and their ability to influence downstream T cell priming in the lymph node (Aim 2). Lastly, we will use agents that block or promote lymphangiogenesis to test how brain inflammation, bacterial load, dissemination, and anti-bacterial immunity are affected by alterations of brain drainage with the hope of decreasing CNSTB associated pathologies (Aim 3). CNS tuberculosis is one of the most common bacterial infections of the brain with high mortality with a pressing need for new therapies, and these studies will lead to novel therapeutic strategies in CNSTB. The objectives of this proposal are (1) to test whether infiltrating or resident immune cells produce VEGFC that contributes to cribriform plate-associated, dorsal meningeal, or basal meningeal lymphangiogenesis during central nervous system tuberculosis (CNSTB) (Aim 1); to define cellular and bacterial interaction between Mtb- infected dendritic cells, Mtb, and lymphoid endothelial cells (LECs) (Aim 2); and to understand the translational value of lymphangiogenesis regulators on CNSTB pathogenesis, bacterial control, anti-bacterial responses, and bacterial dissemination (Aim 3). These studies will lead to a new aspect of brain TB pathology and reveal novel information comparing lymphatic vessel responses and brain drainage in different brain inflammations. These studies' long- term objective is to define how the lymphatic system represents a novel target in combating CNSTB.