Study Of The Pneumocystis Carinii Pneumonia Therapy Effect Of Short Interfering RNA Targeting Pneumocystis Carinii Major Surface Glycoprotein Gene's Upstream Conserved Sequence

Objective : To study the pneumocystis carinii pneumonia (PCP) therapy effect of short interfering RNA targeting pneumocystis carinii major surface glycoprotein (MSG) gene's upstream conserved sequence (UCS).Methods: Rat PCP model was established by hypodermic injection of dexamethasone twice a week for 8 weeks. 20 rats with PCP were randomly divided into 4 groups:in plasmid PC MSG-UCS treatment group (pPC-UCS group), rats were injected with short interfering RNA expressing plasmid PC MSG-UCS 500μg/kg per day, about 70μg every rat everyday for eight days; in plasmid TZU6+1 treatment group (pTZU6+1 group), rats were injected with empty plasmid TZU6+1 500μg/kg per day, about 70μg every rat everyday for eight days;in sulfadiazine treatment group, rats were treated with compound sulfadiazine 120mg/kg per day for eight days;and in PCP control group, rats were not given any treatment. For each group, rat survival rate, rat body weight, pathological changes in rat lung tissues, the number of PC cysts in rat lung tissues, the surface structure changes of PC under scanning electron microscopy, interleukin 8 and tumour necrosis factor alpha (TNF-a) in the serum of rats were tested.Results: All of the rats in each group survived at the end of treatment,rat survival rate had no significant difference between groups. All of the rats in each group got weight during the course of treatment. The mean increased body weight of rats in pPC-UCS group, sulfadiazine treatment group, pTZU6+1 group and PCP control group were 13.16±3.97g, 14.21±3.9g, 5.38±1.19g and 4.32±2.06g, respectively. Those in pPC-UCS group and sulfadiazine treatment group were significantly higher than those in pTZU6+1 group and PCP control group. The inflammation of rat lung tissues in pPC-UCS group and sulfadiazine treatment group were less than those in pTZU6+1 group and PCP control group. Under light microscopy the mean PC cyst number per field in the rat lung tissues in pPC-UCS group and Sulfadiazine treatment group were 3.61±0.4 and 3.17±0.28, respectively, significantly less than those in pTZU6+1 group, 8.74±0.55, and PCP control group, 8.34±0.57. Under scanning electron microscopy, PC in pTZU6+1 group and PCP control group had intact surface with dense microvillus structure. On the contrary, in pPC-UCS group and sulfadiazine treatment group, the PC surface appeared no microvillus but deep gap. Interleukin 8 in rat serum of pPC-UCS group and sulfadiazine treatment group were 232.5±36.27pg/ml and 201.15±34.52pg/ml, respectively, significantly lower than those of pTZU6+1 group, 596.85±61.72pg/ml and PCP control group, 555.1±54.31pg/ml. TNF-a in rat serum of pPC-UCS group and sulfadiazine treatment group were 145.2±80.72pg/ml and 131.57±38.32pg/ml, respectively, significantly higher than those of pTZU6+1 group, 39.49±12.03pg/ml and PCP control group, 31.58±8.47pg/ml.Conclusion: Short interfering RNA targeting pneumocystis carinii major surface glycoprotein gene's upstream conserved sequence is effective in the treatment of rat pneumocystis carinii pneumonia.