Myeloid Cells in Multiple Sclerosis

Abstract

In steady state, the central nervous system (CNS) houses a variety of myeloid cells, such as microglia, non-parenchymal macrophages and dendritic cells (DCs), and granulocytes. Most of these cells enter the CNS during embryogenesis and are crucial for proper CNS development. In adulthood, these resident myeloid cells exert crucial homeostatic functions. In neuroinflammatory conditions, like multiple sclerosis (MS), both lymphoid and myeloid cells from the periphery infiltrate the tissue and cause local damage. Although lymphocytes are undeniably important players in MS, CNS-resident and CNS-infiltrating myeloid cells have recently gained much-deserved attention for their roles in disease progression. Here, we will review significant advances made in recent years delineating myeloid cell functions within the CNS both in homeostasis and MS. We will also discuss how these cells are affected by currently employed therapeutics for MS patients.