| ObjectiveTo investigate the effect of mouse IL-12 gene expressive plasmid (mIL-12 plasmid) intramuscularly administrated on the airway hyperresponsiveness (AHR), inflammation and the cytokines level in sensitized mouse and to investigate the probable mechanism and provide experimental proofs for it's immunological genetic therapy. Methods(1) The effect of mIL-12 plasmid on the airway hyperresponsiveness in sensitized mouse: Thirty-nine BALB/c mice were divided into four groups including sensitized plus challenged group (n=10, sensitized with OVA plus challenging with OVA by aerosol), empty plasmid treatment control group (n=10, empty plasmid 100μg per mouse respectively administrated intramuscularly on day 14,day 16 and day 18), mIL-12 plasmid treatment group (n=9, mIL-12 plasmid 100μg per mouse respectively administrated intramuscularly on day 14, day 16 and day 18), andpositive control group treatment with DXM (n=10, intraperitoneal injection of DXM with the dose of O.Smg.kg"1 once a day from day 14 to the end of the experiment. Airway responsiveness was measured in vivo 24h after the last aerosol exposure by means of plethysmography.(2) The effect of mIL-12 plasmid on the inflammation and the cytokines levels in sensitized mouse: Forty-one BALB/c mice were divided into six groups including sensitized plus challenged group (n=8), sensitized but unchallenged group (n=6, sensitized with OVA plus aerosolizing with normal saline), mIL-12 plasmid preventive group (n=8, mIL-12 plasmid 100μg per mouse respectively administrated intramuscularly on day 1, day 3 and day 5), mIL-12 plasmid treatment group (n=8), empty plasmid preventive control group (n=5, empty plasmid 100μg per mouse respectively administrated intramuscularly on day l,day 3 and day 5), and empty plasmid treatment control group (n=6). Right lungs were lavaged at 24h after the last aerosol exposure, the numbers of inflationary cell in the mouse bronchoalveolar lavage fluids (BALF) were counted with microscope, and the levels of IL-4, IL-5 and IFN-r were also detected by means of ELISA. Made the pathological section with the left lungs fixed by 10% formalin, and then investigated the changes of inflammation in lung tissue after stained with hematoxyline-eosin (HE). Results(1) The effect of mIL-12 plasmid on the airway hyperresponsiveness in sensitized mouse: The inhibition of hyperresponsiveness induced by Mch in both the mIL-12 plasmid treatment group and the positive control group treatment with DXM were more than that in the sensitized plus challenged group and the empty plasmid treatment control group , a significantly difference was observed(P <0.01 or P <0.05 ).The dose of Mch inducing a 100% increases of Raw (PC100) in the mIL-12 plasmid treatment group (0.378± 0.112) μg/kg and the positive control group treatment with DXM (0.503 ±0.129) μg/kg were significantly higher than that in the sensitized plus challenged group(0.187 ±0.071)μg/kg and the empty plasmidtreatment control group(0.205±0.059)μg/kg (P <0.01 or P <0.05). The dose of Mch inducing a 25% decrease of Cdyn(PC25)in the mIL-12 plasmid treatment group (0.219 ±0.074)μg/kg and the positive control group treatment with DXM (0.232 ± 0.083) μg/kg was also higher than that in the sensitized plus challenged group(0.175 ± 0.057) μg/kg and the empty plasmid treatment control group(0.178 ±0.049) μg/kg, there also show a statistically significantly difference (P <0.01).(2) The effect of mIL-12 plasmid on the inflammation and the cytokines levels in sensitized mouse: The numbers of total cells, EOS and the levels of IL-4, IL-5 and IFN-r in BALF from the sensitized but unchallenged group were respectively (1.48±0.3) 108/L, (0.01±0.03) × 108/L, (23.6±4.1)pg/ml, (33.2±5.6) pg/ml and (725.0±59.4 )pg/ml, those from the mIL-12 plasmid preventive group were (2.01±0.31)× 108/L, (0.06±0.04)× 108 /L, (42.6±13.1) pg/ml, (62.6±10.2)pg/ml, and (626.0±60.1)pg/ml, and those from the mIL-12plasmid treatment group were (2.17±0.49)×108/L... |
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