Abstract:

Abstract:Objective To investigate the expressions of tumor necrosis factor-α (TNF-α) in main organs and serum of mouse model infected by Ｍycoplasma pneumonia (MP)  and to clarify the  relationship between TNF-α and MP infection.Methods MP was cultured in the medium containing PPLO broth.Total 72 BABL/C mice were randomly divided into control group(non MP-infected mice，n=24),MP infection group (MP-infected mice，n=24)and  antibiotic treatment group(MP-infected mice treated with azithromycin，n=24).MP infection models were established with the method of dripping cultured MP into nasal cavity of mice.ELISA method was used to assay the levels of TNF-α in the serum of the mice in various groups.Total RNA in the lung tissue of mice was extracted and RT-PCR method was used to detect the expression levels of TNF-α mRNA.Immunohistochemical technique was applied to show the lesion of     lung,liver,kidney,and heart tissues in the MP-infected mice.Results The MP-infected mouse models were established successfully,and MP strains were dripped into the  respiratory system of mice.The activities of the mice in  MP infection group and antibiotic treatment group were reduced,and they showed poor eating,listlessness,nasal secretions,cough,piloerection,chills ect.Contrastly,there were no changes in eating,drinking and activity of the mice in control group.The ELISA results showed that the level of  serum TNF-α of the mice in  MP infection group was higher than those in antibiotic treatment group and control group(P<0.05）.At the same time,the level of serum TNF-α of the mice in antibiotic treatment group was higher than that in control group(P<0.05）.The RT-PCR results  showed the level of TNF-α mRNA in lung tissue of the mice in MP infection group was higher than those in control group and antibiotic treatment group(P<0.05),and  the level of TNF-α mRNA of the mice in MP treatment group was higher than that in  control group(P<0.05).The imunohistochemical  results showed the lesion of   lung tissue  of the mice in  MP infection group was heavier than those in  antibiotic  treatment group and control group,and  it was sligher in antibiotic treatment group  than   control group,while there was no    disease or minor lesion of lung tissue of the mice in control group（P<0.05）. The results from the three tests coincided with each other.Conclusion The positive  expression level of TNF-α is  related to the severity degree of MP infection.

Key words: Mycoplasma pneumoniae, tumor necrosis factor-&alpha, euzymelinked immunosorbent assay, immunohistochemical technology