Comparison Of Inflammatory Cytokines Secretion Induced By Meningitis And Non-meningitis Streptococcus Suis

Streptococcus suis serotype is a gram-positive cocci, which can cause acute hemorrhagic septicemia, pneumonia, endocarditis, meningitis and arthritis in human and porcine, and its main clinical symptoms is meningitis. Many countries in the world have reported it. However, immunological pathogenesis of Streptococcus suis meningitis remains unclear. In general, Upregulation of pro-inflammatory and an increasing leukocytes may be one of the factors leading to the occurrence of meningitis.For the study of differences inflammatory cytokines induced by meningitis and non-meningitis Streptococcus suis, a mice model of Streptococcus suis infection was constructed in the experiment. The secretion levels of cytokines were detected after Streptococcus suis infection and compared whether there are differences between Streptococcus suis meningitis and non-Streptococcus suis meningitis. The results showed that the expression levels of IL-6, IL-8 and IL-17 of Streptococcus suis meningitis significantly were higher expression of non-Streptococcus suis meningitis in a mouse model, and IL-6 was the most obvious at different times. Major colonization sites, pathological changes are the brain in Streptococcus suis meningitis, Meanwhile,MPO and IL-6 levels of brain in meningitis group were significantly higher than non-meningitis group, and a negative correlation with the amount of Streptococcus suis colonization. It showed IL-6, to a certain extent, reflects infection process of Streptococcus suis meningitis.On this basis, the miniature pigs model of Streptococcus suis meningitis was established and correlation immune indexes were detected. The miniature pigs were infected by JZLQ022 and JZLQ001 and observed clinical symptoms and pathological changes. The results showed that JZLQ022 group appears typical meningitis neurological symptoms and pathological changes. During the early infection, peripheral blood leukocytes and neutrophils in meningitis group were significantly higher than non-meningitis group, However, leukocytes and neutrophils significantly decreased inthe late infection. While further study showed endogenous Ig G content within brain in meningitis group was significantly higher than non-meningitis group, suggesting that meningitis group increased BBB opening degree, BBB was destroyed. IL-6, IL-8 and IL-17 levels of Peripheral blood and CSF in meningitis group were significantly higher expression than non-meningitis group, the results are consistent with mice infection model. Therefore, further confirmed that IL-6, IL-8 and IL-17 may act as early diagnostic markers for Streptococcus suis meningitis.To demonstrate secretion levels of IL-6 whether is related with some components of Streptococcus suis, Sly was soluble expressed in E.coil BL21 Codon Plus(DE3), and the expression level of IL-6 of Sly-stimulated lymphocytes from Streptococcus suis infection in meningitis group was significantly higher than non-meningitis group.In this study, in infectious mice model and miniature pigs model, we confirmed that IL-6, IL-8 and IL-17 increased significantly in Streptococcus suis meningitis. And Sly from Streptococcus suis can specifically stimulate lymphocytes from infected with Streptococcus suis to secrete high levels of IL-6. It may indicate that Sly enhanced BBB permeability inducing high levels of inflammatory cytokines. The study supplements a essential immunological data for better understand to the pathogenesis of Streptococcus suis meningitis.