From defense to disease: the multifaceted role of lymphatics during infection.

The lymphatics are a system of vessels that traffic lymph and immune cells throughout the body to maintain fluid balance and aid in the response to infection and injury. Although the lymphatics are often thought of as a passive conduit, this review will demonstrate that the lymphatics are an active component of the immune system. By connecting peripheral tissue to draining lymph nodes (dLNs), the lymphatic system plays a pivotal role in initiating the adaptive immune response, promoting pathogen clearance, restricting pathogen dissemination, and controlling immunopathology. Extensive research has focused on lymphatic endothelial cells (LECs) within dLNs. Instead, this review focuses on the dynamic lymphatics in peripheral tissues. We concentrate on post-natal lymphatic remodeling in response to infection, as other reviews have summarized the lymphatics during development and cancer. We highlight recent studies that explore infection-induced alterations in lymphatic remodeling in peripheral tissues, including lymphangiogenesis (the growth of new vessels) and lymphangiectasia (vessel dilation). While our primary focus is on parasitic infections, we also discuss bacterial and viral infections.