Objective: To establish and evaluate an ovalbumin (OVA)-induced bronchial asthma model in mice with intrauterine growth retardation (IUGR), and to explore the molecular mechanism of relationship between IUGR and asthma.
Methods: A total of 16 pregnant BALB/c female mice were divided into a low-protein diet group (n=8) and a normal-protein diet group (n=8), which were fed with low-protein (8%) diet and normal-protein (20%) diet respectively. The neonatal mice were weighed 6 hours after birth. Sixteen male neonatal mice with IUGR were randomly chosen from the low-protein diet group and enrolled in the IUGR group, and 16 male neonatal mice from the normal-protein diet group were enrolled in the control group. Blood samples were collected from the mice in both groups for testing of blood glucose. Enzyme-linked immunosorbent assay (ELISA) was used to determine serum insulin level. The mice in the control group were randomized into a control + PBS group and a control + OVA group (n=8 each). The mice in the IUGR group were randomized into an IUGR + PBS group and an IUGR + OVA group (n=8 each). Six-week-old mice in the control + OVA and IUGR + OVA groups were subjected to intraperitoneal injection of 2 mg/mL OVA for sensitization and aerosol inhalation of 1% OVA for challenge. Mice in the control + PBS group and the IUGR + PBS group were treated with an equivalent amount of PBS. ELISA was used to determine serum IgE level in the mice in each group. Bronchoalveolar lavage fluid (BLF) was collected from the mice in each group for cell counting. The lung tissue of the mice in each group was stained with hematoxylin and eosin to observe pathological changes.
Results: The body weight at 6 hours after birth was significantly lower for neonatal mice in the low-protein diet group compared with those in the normal-protein diet group (P<0.01). The IUGR group had a significantly lower serum insulin level than the control group (P<0.01). The IUGR + PBS group had a significantly lower IgE level than the control + PBS group (P<0.01). Compared with the control + PBS and IUGR + PBS groups, the control + OVA and IUGR + OVA groups had a significantly increased IgE level, and the IgE level was significantly higher in the IUGR + OVA group than in the control + OVA group (P<0.01). Compared with the control + PBS and IUGR + PBS groups, the control + OVA and IUGR + OVA groups had significantly increased counts of leukocytes, eosinophils, lymphocytes, and macrophages in the BLF (P<0.01). The pulmonary alveoli of OVA-induced IUGR mice showed massive inflammatory cell infiltration and damage of intercellular continuity. Meanwhile, airway epithelial cell proliferation, bronchial wall thickening, bronchial lumen narrowing, and massive inflammatory cell infiltration around the bronchi and the vascular wall were observed.
Conclusions: An OVA-induced bronchial asthma model has been successfully established in the mice with IUGR induced by low-protein diet, which provides a basis for further study of the molecular mechanism of relationship between IUGR and airway inflammation.
目的: 为了研究宫内发育迟缓（IUGR）与哮喘发生的相关分子机制，本研究在IUGR模型基础上建立卵清蛋白（OVA）诱导的支气管哮喘小鼠模型，并且对此模型进行了评价。
方法: 将受孕后的16只BALB/c雌鼠分成低蛋白饮食组和正常蛋白饮食组（n=8）。分别接受8%低蛋白饮食和20%正常蛋白饮食。仔鼠出生后6 h称体重。随机选取低蛋白饮食组中符合IUGR标准的16只雄性仔鼠纳入IUGR组，正常蛋白饮食组中16只雄性小鼠纳入对照组。留取两组小鼠血样测定血糖，ELISA法检测血清胰岛素水平。将对照组小鼠随机分为对照+PBS组和对照+OVA组（n=8），将IUGR组小鼠随机分为IUGR+PBS组和IUGR+OVA组（n=8）。给予对照+OVA组和IUGR+OVA组6周龄小鼠腹腔注射2 mg/m LOVA致敏和雾化吸入1% OVA激发，对照+PBS组和IUGR+PBS组以等量PBS代替。ELISA法检测各组小鼠血清IgE水平；收集各组小鼠肺泡灌洗液行各类细胞计数；苏木素-伊红染色观察各组小鼠肺组织病理变化。
结果: 低蛋白饮食组仔鼠生后6 h体重低于正常蛋白饮食组（P < 0.01）。IUGR组小鼠血清胰岛素水平低于对照组（P < 0.01）。IUGR+PBS组IgE水平低于对照+PBS组（P < 0.01）；与对照+PBS组和IUGR+PBS组相比，对照+OVA组和IUGR+OVA组IgE水平均明显升高，且IUGR+OVA组IgE水平高于对照+OVA组（P < 0.01）。与对照+PBS组和IUGR+PBS组相比，对照+OVA组和IUGR+OVA组肺泡灌洗液中白细胞、嗜酸性粒细胞、淋巴细胞及巨噬细胞计数均明显升高（P < 0.01）。OVA诱导的IUGR小鼠肺泡组织呈现大量炎性细胞浸润，细胞间连续性被破坏；气道上皮细胞增生，支气管壁增厚，管腔狭窄；在支气管和血管壁周围亦观察到大量的炎性细胞浸润。
结论: 在低蛋白饮食建立的IUGR小鼠模型基础上，成功建立OVA诱导的支气管哮喘动物模型，为进一步研究IUGR和气道炎症之间的分子机制建立基础。