The VraSR two-component signal transduction system contributes to the damage of blood-brain barrier during Streptococcus suis meningitis.

Streptococcus suis (S. suis) is an important zoonotic pathogen that can cause high morbidity and mortality in both humans and swine. As the most important life-threatening infection of the central nervous system (CNS), meningitis is an important syndrome of S. suis infection. The vancomycin resistance associated sensor/regulator (VraSR) is a critical two-component signal transduction system that affects the ability of S. suis to resist the host innate immune system and promotes its ability to adhere to brain microvascular endothelial cells (BMECs). Prior work also found mice infected with Δ vraSR had no obvious neurological symptoms, unlike mice infected with wild-type SC19. Whether and how VraSR participates in the development of S. suis meningitis remains unknown. Here, we found Δ vraSR -infected mice did not show obvious meningitis, compared with wild-type SC19-infected mice. Moreover, the proinflammatory cytokines and chemokines in serum and brains of Δ vraSR- infected mice, including IL-6, TNF-α, MCP-1 and IFN-γ, were significantly lower than wild-type infected group. Besides, blood-brain barrier (BBB) permeability also confirmed that the mutant had lower ability to disrupt BBB. Furthermore, in vivo and in vitro experiments showed that SC19 could increase BBB permeability by downregulating tight junction (TJ) proteins such as ZO-1, β-Catenin, Occludin, and Clauidn-5, compared with mutant Δ vraSR. These findings provide new insight into the influence of S. suis VraSR on BBB disruption during the pathogenic process of streptococcal meningitis, thereby offering potential targets for future preventative and therapeutic strategies against this disease. • VraSR regulatory system is a two-component signal transduction system that can affect disease progression. • Wild-type SC19 does cause serious inflammatory lesions in the brain tissues and neurological symptoms compared with vraSR gene mutant infected group. • Wild-type SC19 induces high level of cytokines and chemokines compared with mutant. • VraSR contributes to S. suis -induced meningitis by enhancing BBB permeability. • VraSR is important for S. suis to increase BBB permeability through downregulating the TJ proteins. [ABSTRACT FROM AUTHOR]