Effect of B7-H3 protein on the expression of macrophage-inflammatory protein 2 mRNA in Streptococcus pneumococcal meningitis mouse models

Abstract

Objective To investigate the effect of B7-H3 protein, a collaborative signal molecule, on macrophage-inflammatory protein 2(MIP-2) mRNA level in Streptococcus pneumococcal meningitis mouse models. Methods Forty-eight healthy male BALB/C mice at the age of 1.5-2.0 months were randomly divided into 4 groups: 9 g/L saline group(NS group), B7-H3 protein group(B7-H3 group), Streptococcus neumonia group(SP group), and Streptococcus neumonia plus B7-H3 protein group(combination group), 12 mice in each group.Mouse models were established by intracerebral ventricular injection with 9 g/L saline, B7-H3 protein, Streptococcus neumonia type 3 or Streptococcus neumonia type 3 plus B7-H3 protein.Neurobehavior of different groups was evaluated according to loeffler rule after injection for 6 h and 24 h, then the mice were sacrificed and MIP-2 mRNA levels were tested by Real-time PCR.The results were analyzed by SPSS 18.0 software. Results Neurobehavior scoring results showed that there were no significant differences between B7-H3 group and NS group(P>0.05) after infection for 6 h and 24 h, while the score of SP group was decreased compared with that of NS group(P 0.05), while at 24 h post infection, the relative MIP-2 mRNA expressions in SP group were significantly increased compared with that of NS group(12.880±7.792 vs 1.000±0.091), the difference was significant (P 0.05); while at 24 h post infection, the difference was significant(38.760±6.601 vs 12.880±7.792)(P<0.05). Conclusion Collaborative signal molecule B7-H3 protein may increase MIP-2 mRNA level in Streptococcus pneumococcal meningitis mouse model, and exaggerate the clinical disease condition. Key words: Bacterial meningitis; Streptococcus pneumoniae; B7-H3 protein; Macrophage-inflammatory protein 2