| Objective: To explore the expression and mechanism of MIF in rabbit model of SSc-PAH induced by monocrotaline combined with bleomycin,and the efficacy of glucocorticoid in the treatment of SSc-PAH.Methods: PartⅠ:12 male rabbits were randomly divided into two groups: normal control group(n=4),model group(n=8).Rabbits in model group received intraperitoneal injection of 1% MCT at a dose of 50mg/kg at the first day and repeated injection of BLM at a dose of 100ul/d,nomal control group were given the same volume of sham solution,all for 21 days.Skin,heart,pulmonary artery and pulmonary samples were acquired on the next day after the final injection.Right ventricle hypertrophy index(RVHI)were measured.Paraffin-embedded tissue samples were prepared for H&E,Picrosirius Red and Masson’s trichrome staining according to standard protocols.PartⅡ:36 male rabbits were randomly divided into three groups: normal control group(n=12),model group(n=12),GC intervention group(n=12).Model group and GC intervention group were managed in the same way as describled above to establish the SSc-PAH model,while GC intervention group were treated with methylprednisolone at the same time,nomal control group were given the same volume of sham solution.After 3 weeks,RVHI were measured,H&E staining were conducted,western blotting were used to detect the expression of MIF in pulmonary tissues.Results: PartⅠ:After 2 weeks of injection,rabbits in model group began to moult at the abdomen continuously,local skin thickened.After 3 weeks,2 rabbits died in the model group,the rate of successfully establish an SSc-PAH animal model was 75%.In model group,RVHI were increased,the differences were statistically significant(P < 0.05)when compared with normal control group;Histopathological examination revealed definite dermal sclerosis characterized by epidermal thickness,thickened collagen bundles and deposition of homogenous materials in the thickened dermis,skin appendages were diminished,which mimicked the histologic features of human scleroderma;increase in wall thickness and occlusion of pulmonary arteries were the most prominent features of pulmonary pathology,inflammatory cells infiltration,interstitial thickness,effused red cells in alveolus were observed at the same time,Picrosirius Red and Masson’s trichrome stain showed adventitial fibrosis of pulmonary arteries and bronchi.While the pathologic changes were not observed in normal control group.PartⅡ:After 3 weeks,RVHI were increased in model group when compared with normal control group(P < 0.05),while in GC intervention group,RVHI were decreased statistically compared with model group,there was no difference between GC intervention group and normal control group(P>0.05).Histopathological examination showed epidermal and dermis thickness,dermis fibrosis,skin appendages diminished,increase in wall thickness and occlusion of pulmonary arteries and inflammatory cells infiltration.Western blotting indicated that the expression of MIF in pulmonary tissues in model group were higher than nomal control group(P < 0.001);the expression of MIF in GC intervention group were lower than model control group(P < 0.001),while had no significant difference from model control group(P>0.05).Conclusion: 1.Three weeks of monocrotaline combine bleomycin intraperitoneal injection can induce the histopathological changes which mimicks human scleroderma and PAH,indicating it may be an optional animal model of SSc-PAH.2.The expression of MIF in pulmonary tissues were higher in SSc-PAH model and GC can decrease it,indicating MIF might play a pivotal role in the progress of SSc-PAH.3.Glucocorticoid is efficacious when used from early stage of SSc-PAH,which might make effect by decreasing the expression of MIF. |
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