Distribution Of RPSA In Mouse Tissue And Immune Cells And Its Role In SS2 Infection

Objective:Streptococcus suis type 2(SS2)is a common pathogen of human animal-derived meningitis.Ribosomal protein SA(RPSA)is a pleomorphic,multi-site,multifunctional,highly conserved ribosomal protein that is widely expressed in a variety of cells.Our previous research work found that RPSA mediated SS2 crossing the blood-brain barrier.However,studies on RPSA related to infection are currently rare,and the histological distribution of this protein has not been reported.RPSA distribution is the basis of functional studies and is important for infection mechanisms and immune interaction mechanisms.Therefore,the primary objective of this study was to investigate the tissue distribution of RPSA during SS2infection and its relationship to inflammatory response.Methods:In this study,ICR mice were infected with SS2 strain JZLQ022,and the expression changes of RPSA in various organs of mice and the expression changes in peripheral blood immune cells were analyzed by immunohistochemistry and flow cytometry.HE staining was used to compare the pathological changes of mice infected with S.Suis2.Finally,at the cellular level,the mouse microglial cell line BV2 was used as the research object,and the relationship between RPSA and TLR was explored by qRT-PCR.Results:(1)Heart,liver,brain and small intestine are the main susceptible organs of SS2 infection in mice.After infection,different degrees of lesions appeared.The expression of RPSA in heart and small intestine was decreased significantly after infection for 1 day(P<0.01).The expression of RPSA was increased significantly after 1 day after infection,especially in brain tissue(P<0.001).(2)In the peripheral blood of mice,RPSA was found on the surface of T cells,B cells and NK cells.The expression of CD4~+T cells was increased after 3 days of infection(P<0.01),while CD8~+T cells,B cells and NK cells showed a downward trend after 3 days of infection(P<0.01).(3)The transcription levels of TLR2,TLR5,TLR6,and TLR9 in BV2 cells were significantly increased after SS2 infection(P<0.05).After blocking the surface of RPSA with antibody and re-infecting SS2,the transcription level of TLR2 decreased(P<0.05).At the same time,the cytokines IL-1?and TNF-?,which are increased in transcription after BV2activation,also showed reduced transcription(P<0.01).Conclusion:After SS2 infection,the brain tissue was most severely affected and the expression of RPSA was the most obvious.It was also found that RPSA promoted the expression of TLR2.Targeting blocked cell surface RPSA may be one of the prevention and treatment methods of bacterial meningitis.This finding provides new ideas for the prevention and treatment of SS2infection and SS2 meningitis.