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Objective To study the effect of Streptococcus pneumoniae pneumonia (S.pp) on the lung structure and function of mice. Methods Fifty neonatal BALB/c mice (1-week-old) were randomly divided into S.pp group and control group (25 each).Mice in S.pp group were infected intranasally with 2×107 cfu of S. pneumoniae (D39) in 5 μl to establish the S.pp model, same dosage of PBS were used synchronously to treat the mice in control group. Three and five weeks after treatment, lung tissues and bronchoalveolar lavage fluid (BALF) of the two groups were collected, HE staining was performed to detect the pathological changes of lung tissue and alveolar structure; the collagen fiber deposition around alveoli was identified by Masson staining; the levels of IL-25, IL-33 and thymic stromal lymphopoietin (TSLP) in BALF were examined by ELISA. Five weeks after the infection, lung resistance was evaluated by EMKA pulmonary system. Results HE staining showed that, compared with control group, the radial alveolar count (RAC) decreased significantly in infancy and adult S.pp group (8.00±1.10 vs. 3.53±0.35, P=0.018; 13.73±2.49 vs.4.02±0.21, P=0.018), the mean linear intercept (MLI) increased obviously (88.99±5.55 vs. 127.10±9.54, P=0.006; 74.45±4.84 vs. 131.30±17.86, P=0.020), and the alveolar septum thickness increased markedly [(2.38±0.18) μm vs. (3.28±0.13) μm,P=0.002; (3.41±0.60) μm vs. (5.78±0.75) μm, P=0.023]. Compared with control group, the mean alveolar diameter (MAD)increased significantly in infancy S.pp group [(167.00±8.85) μm vs. (193.40±5.14) μm, P=0.042], but no significant difference existed between control group and adult S.pp group. The infiltration of inflammatory cells around alveoli increased obviously in infancy and adult S.pp group compared with that in control group (1.68±0.24 vs. 0.72±0.12, P=0.002; 1.88±0.30 vs.0.67±0.23, P=0.006). Compared with control group, the concentrations of IL-25, IL-33 and TSLP in BALF of adult S.pp group increased significantly [(36.16±2.80) pg/ml vs. (45.16±1.74) pg/ml, P=0.024; (52.06±1.70) pg/ml vs. (61.42±1.50) pg/ml,P=0.004; (13.32±0.74) pg/ml vs. (16.71±0.54) pg/ml, P=0.007]; Collagen fiber deposition around alveoli increased markedly[(0.01±0.01) mm2 vs. (0.44±0.01) mm2, P<0.001], and the airway resistance increased significantly when the concentration of inhaled aerosolized methacholine reached to 12.5–50.0 mg/ml in adult S.pp group mice (P<0.001). Conclusion Streptococcus pneumoniae pneumonia may induce the decrease of mean alveolar count, the increase of MLI, the alveolar septum thickness and airway resistance in BALB/c mice, thus lead to abnormal lung tissue structure and function.
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| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |
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