Investigation of CARDS TX in a resistant Streptococcus pneumoniae pneumonia model in BALB/c mice

LI Ying; ZHAO Kai-shun; YU Yan-fang; TU Chun-lin

doi:10.13820/j.cnki.gdyx.20241337

Abstract：Objective To clarify the role of community-acquired respiratory Distress syndrome toxin(CARDS TX,referred to as CT)in a resistant Streptococcus pneumoniae(SP)mouse model.Methods Using BamHI and EcoRI cloning methods,we constructed the CT pET28-a+vector and expressed and purified the CT protein.Sixty female BALB/c mice aged 5-8 weeks,weighing(20±2)g,were randomly assigned to four groups:a blank control group(control group),a single SP model group(SP group),a Mycoplasma pneumoniae(MP)+SP co-infection group(MP+SP group),and a single SP+CT treatment group(SP+CT group).Azithromycin intervention began on the 4th day post-model establishment.On days 4,5,and 6,five mice from each group were anesthetized to collect bronchoalve-olar lavage fluid(BALF)for SP culture,cell sedimentation for Giemsa staining,and lung tissue for HE staining and cyto-kine analysis[interferon-y(IFN-γ),tumor necrosis factor-α(TNF-α),interleukin(IL)-6,IL-17,transfor-ming growth factor-β(TGF-β),and IL-10)].Results Post-treatment,the SP+MP group and SP+CT group ex-hibited significantly higher levels of IFN-γ,TNF-α,IL-6,IL-17,and TGF-β compared to the SP group and con-trol group,while IL-10 levels were significantly lower.Histological analysis revealed greater leukocyte infiltration in the SP+MP and SP+CT groups.SP growth in culture showed a declining trend post-Azithromycin treatment,with the SP+MP group and SP+CT group faring better than the SP group.Conclusion In the BALB/c mouse pneumonia model,CT provides protective effects against the co-infectious pathogen SP,prolonging SP's response time to Azithromycin and reducing its detrimental effects,thereby contributing to the development of resistant pneumonia.