The Effect Of Early-Life Streptococcus Pneumoniae Infection On TH17/IL17in Experimental Asthma

PART ONE:ESTABLISHMENT OF A NON-LETHA STREPTOCOCCUS PNEUMONIA INFECTION MODEL IN NEONATAL MICEStreptococcus pneumoniae(S.pneumoniae) colonization in the upper respiratory tract, can survive for several weeks in the nasopharynx mucosa, is the most common bacterial pathogens of children community-acquired respiratory infection. Establishment of adult mice to Streptococcus pneumoniae infection model is ripe, but how to create a model of neonatal mice non-letha S.pneumoniae infection has not been reported. This study investigated the establishment of neonatal BALB/c mice were non-fatal S.pneumoniae infection model, and to lay the model basis for later studies.Objective:To establish and assess the model of non-letha Streptococcus pneumonia infection in neonatal BALB/c mice.Methods:SPF(Specific pathogen Free) level neonatal BALB/c mice were randomized into streptococcus pneumonia infection one time group, streptococcus pneumonia infection two times group, and two control groups. Infection one time group mice were inoculated through intranasal10μl of streptococcus pneumonia with107、108、109and1010Colony-Forming Units(CFU) on the seventh day after birth. Infection two times group mice were inoculated through intranasal10μl of streptococcus pneumonia with107、108、109and1010CFU on the sixth and seventh days. Control one group mice were inoculated through intranasal10μl PBS on the seventh day, Control two group mice were inoculated through intranasal10μl PBS on the sixth and seventh days.10mice in each group were randomized sacrificed after24h of the final inoculated and the other10mice were followed for5days.Results:Infection two times group mice with109CFU streptococcus pneumonia appeard quiet, pale skin and little weight growth.The infection and survival rate of mice treated with109CFU on the sixth and seventh day were greater than85%; Mouse lung tissue were cultured and identificated to streptococcus pneumoniae,; Pathologic text revealed lung inflammation; the alveolar interval appeared to thickeness; inflammation cell infiltrated around blood vessels and bronchi in a certain level.Conclusion:Inoculated through intranasal with109CFU on the sixth and seventh day in neonatal is a reliable method to establishment the non-letha model of streptococcus pneumonia infection in neonatal BALB/c mice. PART TWO:EARLY-LIFE PNEUMOCOCCAL INFECTION LUNG INFECTION ENHANCES ALLERGIC AIRWAYS DISEASE THROUGH TH17/IL17Bronchial asthma is the most common chronic respiratory disease in children. Its nature is a chronic inflammation of the airways. The pathological change of asthma is closely related with immune system. But asthma is not simple attributed to the imbalance of Thl/Th2cell function, in recent years the study found that TH17/IL-17plays an apparently critical role in the pathogenesis of asthma disease. Th17cell which different from of Thl, Th2and Treg CD4T cell, mainly secrete proinflammatory cytokine IL-17, plays an important role in autoimmune diseases and infectious diseases. Streptococcus pneumoniae is the most common bacterial pathogens with community-acquired respiratory tract infection of children. A recent study indicates that the age of streptococcus pneumoniae colonization or infection is a key factor in subsequent wheeze and asthma development.This study aimed to investigate the effects of early-life streptococcus pneumoniae infection on TH17/IL17in expermental asthma.Objective:To investigate the effects of streptococcus pneumoniae infection at neonatal ages on allergic airways disease in later life.Methods:SPF (Specific pathogen Free) level neonatal BALB/c mice were randomized into streptococcus pneumonia infection and asthma group (S.p+OVA), streptococcus pneumonia infection group (S.p), athma group (OVA) and contoul group. Both infection groups mice were inoculated through intranasal10μl of streptococcus pneumonia with109Colony-Forming Units (CFU) on the sixth and seventh days; Control group were received PBS as the substitution of streptococcus pneumonia. S.p+OVA group and OVA group were sensitized (i.p.) with ovalbumin100μg at the first day of the fourth and sixth week, then challgened with ovalbumin for7days. S.p group and control group were received PBS as the substitution of ovalbumin. We measured the airway responsiveness and inflammation (H&E). Investigate the levels of INF-γ、IL-4、IL-5、IL-17、 TGF-B、IL-10in BALF and all groups of CD4+T cells in the lung.Results:We found S.p+OVA group mice wheezed apparently and their airway hyperresponsiveness were significantly higher than those of OVA mice. In S.p+OVA group and OVA group, the lung tissue have an inflammation, the alveolar septa were thickening, the inflammatory cell were infiltrated in perivascular and peribronchial;but S.p+OVA group is serious. In BALF of S.p+OVA group, the total cell number and the classification of the proportion of eosinophils, neutrophils, lymphocytes were increased, the most significant increase were neutrophils. In S.p+OVA group, TH1cells and IFN-y were decreased; TH17cells and IL-17significantly increased, TH2and Treg cytokines were no significant change.Conclusion:Early-life respiratory streptococcus pneumoniae infections modulate immune responses, alter lung function and structure, and enhance the severity of allergic airways disease in later life.