The Cytotoxicity of Suilysin, the Pore-Forming Toxin of Streptococcus suis on the Central Nervous System Cells

Streptococcus suis (S. suis)-induced meningitis is a catastrophic neurological disorder with high morbidity rates. Several studies have mentioned that Suilysin (SLY), the only toxin of S. suis, interacts with the cells in either human or swine Central Nervous System (CNS) cells and trigger destructing inflammatory events in them. However, the pathogenesis of cytotoxicity is currently an unresolved question. This review highlights current literature emphasizing the role of SLY in causing cytotoxicity of Brain Microvascular Endothelial Cells (BMEC), Choroid Plexus Epithelial Cells (CPEC), and astrocytes along with the proposed pathological mechanisms. SLY has been considered to be the key player in various pathological mechanisms related to CNS cell death, including alteration of tight junction, barrier integrity, inflammatory response, and activation of RhoA GTPase as the newly recognized mechanism. These findings should be taken into consideration in order to design novel therapeutic options for S. suis meningitis. Although the exact mechanism of SLY-induced cytotoxicity is still plausible, the possible neurobiological pathways may further help to dissect the biological role of SLY during S. suis meningitis.