| ObjectiveTo explore the effect and the possible mechanism of suplatast tosilate of prevention and treatment on asthma by observing the changes of the airway inflammation, the gene expression of interleukin-5 in the lung tissues and concentration of IL-5 in bronchoalveolar lavage fluids before and after suplatast tosilate intervention.Methods1. Fifty adult male Sprague-Dawley (SD) rats (4-week- old and weight 200±20g ) were divided randomly into five groups: Model group, Control group, Budesonide (BUD) group, Suplatast tosilate early intervention group[IPD(A)group] and Suplatast tosilate late intervention group[IPD(B)group], 10 rats in each group.2. The numbers and the percentages of eosinophil in peripheral blood were counted on day 0(before the sensitization). Except the Control group, the other four groups were sensitized by intraperitioneally injected with 10% OVA (1ml) including 10% aluminium hydroxide and the inactive pertussis bacillus on the first day and the 8th day. Two weeks later, they were challenged with 2% OVA by pump atomization, ten minutes each time, once a day, lasting seven days to induce the rat asthma Model . The Control group was sensitized and challenged by normal saline. The IPD(A) group and IPD(B) group were treated with suplatast tosilate (50 mg/kg·d) administered intragastrically (solved into water ) , while the BUD group were inhaled with budesonide by pump atomization before sensitization and challenge.3. All rats were anesthetized within 24 hours after the last challenge. The numbers and the percentages of eosinophil in peripheral blood were counted again,then the airway resistances of rats were assessed after intubation through provocated by histamine hydrochloric acid. Bronchial alveolar lavage fluid (BALF) of rats were acquired to count the number of cells and the percentage of eosinophil and detect the levels of IL-5 by ELISA tests. The lung tissues were removed to detect the lung histomorphology and the gene expression of IL-5 by reverse transcription-polymerase chain reaction (RT-PCR). Study the correlation between IL-5,EOS and AHR . The relationships between the levels of IL-5, the numbers of EOS and the values of airway resistances respectively were investigated.Results1. Establishment of rat Model of asthma: In the challenge process, the Model group rats displayed the symptoms of the dysphoria, scratching the nose, shortness of breath , breathing nodding, cyanosis, eating little, quiescence, piloerection even depilation; 7days after the challenge, the airway responsiveness airway hyperactivity of the Model group is higher than that of the Control groups(P<0.05); the histopathology of lung tissue manifested significantly inflammation around the airway, bronchial wall thickening, stenosis, airway epithelial cell shedding, mucus secretion increased significantly; their percentage of eosinophil was obviously increased (P<0.05), which indicated that the rat Model of asthma was established successfully.2. Determination of airway hyper responsiveness: Rats in each group were stimulated with histamine hydrochloride. When excited at the same concentration, the airway resistances of the Model group,the BUD group,the IPD(A) group and the IPD(B) group were significantly higher than those of Control group (P< 0.05), but the airway resistances of IPD(A) group, the IPD(B) group or BUD were significantly less than those of Model group respectively (P all<0.05). but those were not statistical different between IPD(A)group and the BUD group.( P>0.05).3. The histopathology of lung tissue: The histopathology of lung tissue of the Model group manifested significantly inflammation around the airway, bronchial wall thickening, stenosis, airway epithelial cell shedding, mucus secretion increased significantly; however, significantly reduced inflammation around the airway, airway inflammatory cell infiltration around the airway secretions decrease, bronchial wall thickening and epithelial cell detachment behavior improved significantly after rat treated by IPD or BUD .4. The assessment of cytological in bronchoalveolar lavage fluids(BALF) suggested that the number of Inflammatory cells and percentage of eosinophil in BALF of rats treated by IPD or BUD were significantly lesser than the Model group (P<0.05). However, those were not statistical different between the IPD(A) group and the BUD group (P>0.05).5. The number and the percentage of EOS in peripheral blood: Before the experimental treat(before the sensitization), there was no difference in the five groups(P>0.05).After the experimental treat(7 days after the challenge),the counts and the percentage of EOS in peripheral blood of rats treated by IPD or BUD were significantly lesser than those of the Model group (P<0.05). However, those were not statistical different in rats treated by IPD or BUD (P>0.05).6. The level of interleukin 5(IL-5) in BALF: The levels of IL-5 of Model group were obviously increased compared with the Control group (P<0.05).But the levels of IL-5 in IPD(A) group, IPD(B) group and BUD group were obviously decreased respectively (P>0.05) .However, those were not statistical different between the IPD(A) group and the BUD group (P>0.05).7. The expression of IL-5mRNA in lung tissues: The levels of expression of IL-5 mRNA in lung tissues in Model group were obviously increased compared with the Control group (P<0.05).But the levels of expression of IL-5 mRNA in lung tissues in IPD(A) group, IPD(B) group and BUD group were obviously decreased respectively (P>0.05), but,those were not statistical different between the IPD(A) group and the BUD group (P>0.05).8. The level of interleukin 5(IL-5) in BALF was positive correlated with the degree of airway resistance(r=0.919, P<0.01)and the expression of IL-5mRNA in lung tissue was positive correlated with the degree of airway resistance(r=0.909, P<0.01).The level of interleukin 5(IL-5) in BALF was positive correlated with the percentage of eosinophil in BALF (r=0.955,P<0.01).The percentage of eosinophil in BALF was positive correlated the degree of airway resistance (r=0.865, P<0.01).The level of interleukin 5(IL-5) in BALF was positive correlated with the number of cells in BALF(r=0.955,P<0.01); the expression of IL-5mRNA in lung tissue was positive correlated with the level of interleukin 5(IL-5) in BALF (r=0.973,P<0.01)Conclusion1. IPD can reduce airway hyperresponsiveness of the asthmatic rat, partly inhibited airway inflammation and inhibit recruitment of EOS.2. IPD can inhibit the IL-5 gene expression in the lung tissue, and reduce the levels of IL-5 of BALF.3. The anti-inflammatory effect of early intervention of IPD and BUD was similar .The late intervention of IPD has prompted anti-inflammatory effects. 4. IPD can reduce airway hyper responsiveness and inhibit airway inflammation, which maybe achieve by reducing the synthesis of IL-5 at the gene transcriptional level.
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