Objective To investigate the impact of B7 homolog 3( B7 - H3) on inflammatory response and blood - brain barrier integrity during streptococcus pneumoniae (SP) meningitis, and explore its mechanism. Methods SP meningitis was established by intracerebral ventricular injection of SP suspension. Wild — type mice were randomly divided into 5 groups and received following injections:PBS,SP alone,SP plus recombinant murine B7 — H3 ,SP plus control IgG mAb, or SP plus anti — B7 — H3 blocking mAb. Toll — like receptor 2( TI.R2) - deficient mice were divided into 3 groups and received PBS.SP alone,or SP plus recombinant murine B7 - H3 injection. At 6 h, 18 h.and 30 h post infection,mice anesthetized,blood sample in mice eyes and brains were collected,and brain homogenates were prepared. Tumor necrosis factor-alpha(TNF-α) ,interleukin -6( IL-6) ,interleukin - 1 beta (IL - 1β), and monocyte chemoattractant protein - 1 ( MCP - 1 ) levels in serum, and albumin and IgG levels in brain homogenates were assessed by enzyme — linked immunosorbent assay ( ELISA). Results 1. In wild - type mice, injection with SP alone and SP plus recombinant murine B7 - H3 led to higher TN F — α, IL — 6 and MCP - 1 levels in serum at 18 h,and higher TNF -α,IL -6,IL - 1β and MCP-1 levels in serum at 30 h,as compared with PBS injection group(Pa ＜0.05). Compared with SP injection group,levels of any cytokines in serum at each time point were not changed after SP plus control IgG mAb group ( Pa ＞0.05). SP plus recombinant murine B7 - H3 injection induced higher MCP - 1 level at 18 h ,and higher TNF - a and IL30 h in serum,as compared with SP injection group[ MCP - 1: (42.010 ±3.880) ng · L-1 vs (29.620 ±3. 830) ng · L-l ;TNF-α:(37.550 ± 3.232) ng · L-1 vs (24.570 ±2. 377) ng · L-1 ;IL -6: (66. 160 ±5.766) ng · L-1 us (48.630 ±4.418) ng · L-1 ,P. ＜0. 05 ]. 2. In SP plus anti -B7 -H3 blocking mAb group,at 30 h,TNF-ex and IL-6 levels in serum were lower than those in SP injection groupf (18.680 ± 1.798) ng · L-1 vs (24.570±2.377) ng · L-1;(37. 180 ±3. 150) ng · L-1 vs (48.630 ±4.418) ng · L-1,P. ＜0.05] ;injection with SP alone and SP plus recombinant murine B7 -H3 led to higher levels of albumin and IgG in serum at 18,30 h,as compared with PBS injection group(P, ＜0.05). Compared with SP injection group,levels of albumin and IgG in brain at each time point were not changed after SP plus control IgG mAb injection group(Pa ＞0.05). SP plus recombinant murine B7 - H3 injection increased albumin level at 18,30 h,and IgG level at 30 h in brain,as compared with SP injection groupf albumin: (59.090 ±4. 184) μg · g-1 vs (35.450 ±4.256) μg · g-1 ; (59. 890 ± 4.701) μg·g-1 vs (43.790 ±3.508) μg · g-1;IgG:( 36.220 ±2.775) μg · g-1 vs (25.440±2.620) μg · g-1 ,Pa ＜0.05]. In SP plus anti -B7 - H3 blocking mAb group, levels of albumin at 18,30 h,and IgG at 30 h in brain were lower than those in SP injection group [ Albumin; (20.590 ± 1.720) μg·g-1 vs (35.450 ±4.256) μg · g-1;(28.650±3.063) μg · g-1 vs (43.790 ±3.508) μg · g-1 ;IgG:(17.380 ± 1.595) μg · g-1 vs (25.440 ±2.620) μg · g-1 ,P, ＜0. 05]. 3. In TI.R2 -deficient mice.SP plus recombinant murine B7 - H3 injection failed to further enhance proinflammatory cytokines further,albumin and IgG release in serum and brain homogenates compared with SP injection alone group( P. ＞0.05). Conclusions B7 - H3 enhances inflammatory response and exacerbates blood - brain barrier injury via a TLR2 -dependent mechanism during SP meningitis in mice.%目的 探讨B7同源体3(B7 - H3)对肺炎链球菌(SP)脑膜炎大鼠的炎性反应和血脑屏障完整性的影响及其机制.方法 经小鼠侧脑室穿刺注入SP悬液,制备脑膜炎模型.野生型鼠分5组,分别为PBS组、SP组、SP+B7 -H3组、SP+同型单抗组、SP+B7 - H3阻断性单抗组.Toll样受体2基因剔除(TLR2-KO)鼠分3组:PBS组、SP组、SP+ B7 - H3蛋白组.术后6h、18h、30 h,麻醉其下眼眶采血法收集血清,取脑组织,制备脑组织匀浆.ELISA检测其血清TNF-α、IL-6、IL-1β和单核细胞趋化因子蛋白-1(MCP-1)水平以及脑组织匀浆中血清蛋白( Albumin)和IgG水平.结果 1.ELISA检测野生型鼠血清SP组、SP+ B7 - H3组注射18 h后TNF-α、IL-6和MCP-1的表达及30 h后TNF-α、IL-6、IL-1β和MCP-1的表达均较PBS组显著升高(Pa＜0.05)；SP+同型单抗组与SP组比较,各时间点各炎性因子的表达差异均无统计学意义(Pa＞0.05)；SP +B7- H3组注射18h后MCP-1的表达及30 h后TNF-α和IL-6表达均显著高于SP组[(42.010±3.883) ng·L-1vs(29.620±3.830) ng· L-1；(37.550±3.232)ng· L-1vs (24.570±2.377) ng·L-1；(66.160±5.766) ng·L-1vs (48.630±4.418) ng·L-1,Pa＜0.05]；SP+ B7 - H3阻断性单抗组注射30h后,TNF-α和IL-6的表达均显著低于SP组[(18.680±1.798) ng·L-1vs(24.570±2.377) ng·L-1；( 37.180±3.150) ng·L- 1vs (48.630±4.418) ng· L-1,Pa＜0.05].2.ELISA检测脑组织匀浆:SP组、SP+ B7 - H3组注射18h、30h后Albumin、IgG的表达较PBS组均显著升高(Pa＜0.05)；SP+同型单抗组与SP组比较,各时间点Albumin、IgG的表达差异均无统计学意义(Pa＞0.05)；SP+ B7 - H3组注射18 h、30 h后脑组织匀浆Albumin的表达及30 h后脑组织匀浆IgG的表达均显著高于SP组[(59.090±4.184) μg· g-1vs ( 35.450±4.256) μg·g-1;( 59.890±4.701)μg·g-1 vs (43.790±3.508) μg·g-1;(36.220±2.775)μg·g-1 vs(25.440±2.620)μg·g-1,Pa＜0.05].3.SP+ B7 - H3阻断性单抗组注射后18 h、30 h Albumin的表达及30 h IgG的表达显著低于SP组[(20.590±1.720) μg·g-1vs(35.450±4.256) μg·g-1；(28.650±3.063) μg· g-1vs(43.790±3.508)μg·g-1;(17.380±1.595) μg·g-1vs(25.440±2.620) μg·g-1,Pa＜0.05].3.TLR2-KO鼠血清和脑组织匀浆的ELISA检测显示:SP +B7-H3组较SP组各监测指标的表达在任何时间点的差异均无统计学意义(Pa＞0.05).结论 B7 - H3通过TLR2依赖性机制促进SP诱导的脑膜炎小鼠的炎性反应和血脑屏障的破坏.
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