Interactions between platelets and leukocytes in pathogenesis of multiple sclerosis

Neurodegenerative diseases are an increasing problem in the modern world. Multiple sclerosis (MS) is a major human demyelinating and degenerative disease of the central nervous system (CNS). There are many reports that point to the significant role of platelet–leukocyte interaction in neurodegenerative diseases and cardiovascular disturbances. Epidemiological studies confirm the high risk of cardiovascular diseases in patients with MS. The pathophysiology mechanisms of this multi-component disease are very complex and involve various types of cells. There is increasing evidence that some co-stimulatory pathways affect the function of inflammatory cells, both in the periphery and in the CNS. Interactions of leukocytes and endothelial cells (ECs) could be significantly modulated in the presence of activated blood platelets. The supposed role of activated platelets in the development of vessel inflammatory response is due to their ability to adhere to inflamed ECs or proteins included in the subendothelial layer of the blood vessel wall, as well as to the ability of platelets to form aggregates with leukocytes. Blood platelets are able to directly activate leukocytes through a receptor-dependent mechanism or, indirectly, by biologically active compounds secreted from their granules. Cell–cell interactions provide critical mechanisms by which platelets link thrombosis, inflammation and related processes, such as diapedesis and leukocyte infiltration, to the affected vessel. Determining the relationship between platelet–leukocyte interactions and the development of neuroinflammation in the course of MS may provide new therapeutic targets in the future.