摘要:Objective To investigate the therapeutic effects of anti-B7-H3 blocking monoclonal antibody(McAb) in a murine model of neutrophilic asthma. Methods Twenty-four female BALB/c mice were randomly divided into four groups: PBS control group (group A), neutrophilic asthma group (group B),anti-B7-H3 McAb group (group C) and IgG isotype control group (group D). Those in group A were sensitized by injection of PBS and challenged with PBS through inhalation,while the other mice were sensi-tized by injection of ovalbumin (OVA) plus airway instillation of lipopolysaccharide(LPS),and then chal-lenged with OVA. Moreover,mice in group C and group D were respectively injected with anti-B7-H3 McAb and IgG isotype control in the induction period. Each mouse′s performance was observed. Samples of bron-choalveolar lavage fluid (BALF) and lung tissues were collected. Total and differential cell counts in BALF were determined by using microscope. Levels of cytokines including IFN-γ,IL-4,IL-6,IL-17,tumor nec-rosis factor-α (TNF-α) and granulocyte colony stimulating factor (G-CSF) in BALF were measured by ELISA. Lung sections were stained with hematoxylin and eosin (HE) and periodic acid-Schiff (PAS) to identify tissue inflammation and mucus production,respectively. Immunohistochemistry was used to measure the expression of B7-H3 in frozen mouse lung sections. Results Mice in group B and group D showed asth-matic symptoms such as breathlessness,dysphoria and incontinence after nebulization,while these symptoms in group C were alleviated due to anti-B7-H3 McAb treatment. No abnormalities were observed in group A. Compared with group A,the other three groups showed increased total cell count in BALF and higher per-centages of neutrophil and eosinophil(P<0.05). These three indicators in group C were lower than those in group B and group D (P<0.05). With regard to lung infiltration by Th1,Th2 and Th17 cells,the levels of IFN-γ,IL-4,IL-6,IL-17,TNF-α and G-CSF in BALF were increased in group B,group C and group D as compared with those in group A. Compared with group C,group B and group D showed higher levels of IL-6, TNF-α,IL-17 and G-CSF(P<0.05),but lower level of IL-4(P<0.05). No statistical difference in the level of IFN-γ was observed among group B, group C and group D. Histological staining of lung sections showed that no obvious inflammatory cells and mucus secretion was observed in group A. Massive infiltration of inflammatory cells and neutrophils and mucus hypersecretion were detected in group B and group D. Treatment with anti-B7-H3 McAb inhibited the accumulation of neutrophils and mucus hypersecretion in lung tissues of group C. Compared with group A, levels of B7-H3-positive cells were significantly increased in group B and group D. Anti-B7-H3-treated mice showed reduced levels of B7-H3-positive cells in lung tissues as compared with those in group B and group D(P<0.05). Conclusion Treatment with anti-B7-H3 bloc-king McAb in an early stage can relieve the asthmatic syndrome, reduce airway inflammatory cells, inhibit mucus production and down-regulate Th17 cell-related cytokine secretion,which helps to alleviate airway and systematic inflammation in mice with NA,and partially inhibit the development of NA.%目的 探讨阻断型抗小鼠B7-H3单克隆抗体对中性粒细胞哮喘(neutrophilic asthma, NA)小鼠模型的干预作用.方法 BALB/c雌性小鼠24只,随机分成4组,分别为磷酸缓冲盐溶液(PBS)对照组(A组)、中性粒细胞哮喘组(B组)、抗B7-H3单克隆抗体干预组(C组)、同型对照IgG组(D组).B、C、D组均给予OVA联合LPS致敏,OVA雾化激发,A组给予同等剂量的PBS注射和激发,C组和D组在诱导期分别注射50 μg抗B7-H3单克隆抗体和同型对照IgG.观察各组小鼠雾化时的症状;收集支气管肺泡灌洗液(BALF)和肺组织;显微镜下进行BALF细胞总数及分类计数;采用酶联免疫吸附试验(ELISA)检测小鼠BALF上清中IFN-γ、IL-4、IL-6、IL-17、TNF-α、G-CSF细胞因子的水平;小鼠肺组织病理切片HE染色观察肺组织病理改变;PAS染色观察气道黏液的分泌;同时肺组织免疫组化法检测B7-H3表达水平.结果 (1)B组和D组小鼠雾化激发后出现呼吸急促、烦躁不安、频繁搔抓头面部等表现,C组喘息症状较B组有所缓解,A组活动自如.(2)B组、C组、D组BALF细胞总数、中性粒细胞百分比及嗜酸性粒细胞百分比较A组均明显升高(P均<0.05);C组BALF细胞总数、中性粒细胞百分比和嗜酸性粒细胞百分比较B组、D组降低(P均<0.05);B组与D组比较无显著差异.(3)B组、C组、D组BALF中IFN-γ、IL-4、IL-6、IL-17、TNF-α、G-CSF水平较A组均显著性上升,其中B组、D组IL-6、TNF-α、IL-17和G-CSF水平比C组明显增高(P均<0.05);IL-4水平B组和D组低于C组(P均<0.05).(4)A组肺组织病理染色示无明显炎症细胞及黏液分泌;B组和D组炎症细胞、中性粒细胞浸润和黏液分泌较A组明显增多,C组较B组、D组有所减轻.(5)肺组织免疫组化显示A组几乎无表达B7-H3阳性细胞,B组和D组B7-H3阳性细胞数明显增多,C组较B组、D组阳性细胞数明显减少(P<0.05).结论 阻断型抗小鼠B7-H3单克隆抗体通过早期阻断B7-H3表达能够减轻NA小鼠喘息症状,减少肺组织炎症细胞浸润和黏液的分泌,下调Th17相关细胞因子分泌,从而减轻NA小鼠肺组织炎症损伤、全身炎症反应,部分阻断NA免疫致病机制的发生发展.