| Objective:This study aimed to observe the effect of low molecular weight heparin(LMWH) on bleomycin-induced pulmonary interstitial fibrosis in rats. Detecting the levels of acidic fibroblast growth factor(aFGF) and hydroxyproline(HYP) in the tissue of the rats and detecting the levels of transforming growth factor-β1(TGF-β1) in the blood serum ,lung tissue and bronchoalveolar lavage fluid (BALF) of rats, which rats were separated into normal control group, bleomycin group, dexamethasone group and low molecular weight heparin group. From the detecting, we can explore the probalble mechanism of low molecular weight heparin to the pulmonary fibrosis and develop the new ideas for the use of LMWH on the patients.Methods:120 male Sprague Dawley (SD) rats were randomly divided into four groups: normal control group(A group), bleomycin group (B group), dexamethasone group (C group)and LMWH group (D group) and . In B,C and D groups, IPF was induced in rats by intratracheal injection of blemycinA5, and in A groups,rats were treated by normal sodium in the same way. Every day,the rats in C group were received 0.5mg/kg dexa- methasone by intramuscular injection , in D group the rats were received 1000u LMWH by subcutaneous injection, and in A group the rats were received normal sodium by subcutaneous injection. On 1,3,7,14,28 day after bleomycin instillation, we sacrificed 6 rats respectively,and make tissue slices of the lung tissue. We observed the slices by staining of HE and Masson and immunohistochemistry of TGF-β1 and aFGF. Positive rate of TGF-β1 and aFGF determined by sem quantitative picture analysis system. At the same time, we determined the quantity of the collagen in the lung. The levels of TGF-β1 were detected in blood serum and alveolar lavage fluid. We observed the effects of therapy of LMWH to the lung fibrosis.Results:1 HE Staining on the lung tissueThe lung of normal control group rat had no change lesion in every point, but that of B group showed acute inflammation: there were a few of macrophage and neutrophil in alveolar space on the 1st day. On the 3rd day macrophage, neutrophil and lymphocyte infiltrating to be increased, and alveolitis becomed more serious. On the 7th day, there were a great deal of polycytes and monocytes infiltration in alveolar space and fibroblasts begin to proliferat, with alveoli normal structure was destructed in the severe areas. On the 14th day, alveolitis relieved, but hemorrhage and edema were still existing, with fibroblast increasing, interval widening obviously, collagen deposited and patches of fibrosis. On the 28th day, alveolitis did not relieved obviously. Alveola structure was destructed with fibroblast aggravated and alveolar space vanished. Inflammatory cells and the degree of fibrosis in the C and D group was obviously less than those in the B group .2 Masson Staining on the lung tissueThere was little collogen which color was blue in the microscope in the A group. In the B group, there was more collogen than that in the A group, which collogen was obviously increased with the time going. In the C and D groups, this appearanc was slightly increaing, and it was less than that in the A group.3 Concentration of HYPThe concentrations of HYP in B,C and D groups were little higher than those in A group on 1st day and 3rd day, but there was no statistical significance between every two groups(P>0.05). In the B group, concentrations of HYP increas- ed obviously with the time going after bleomycin instillation.At the same time, in the C and D group,the increasings were slower than that in the B group. There were obvious statistical significance on the 7th,14th,28th between every two groups of B,C and D group(P<0.01). Every group between C and D group on the same day, there were no statistical significance (P>0.05).4 Concentration and percentage of TGF-β1 The concentrations of TGF-β1 in blood serum of B group on all the time points except the 1st day point were all higher than normal A group,C group and D group(P<0.01). That of B group was higher than that of the others groups on the 1st day, but there was no statistical significance between them(P>0.05). TGF-β1 concentration in blood serum of D group on every time was higher than A group(P<0.01); there was no statistical significance between C and D group(P>0.05).There was the same tendency of changes in bronchoalveolar lavage fluid (BALF) as that in blood serum. In the tissue, there were the same tendency than TGF-β1 in the serum.5 aFGF in lung tissue percentageOn the 1st and 3rd day point,there was no statistical signifi- cance between A and D group and between B and C group (P>0.05).But there was statistical significance between other every two groups(P<0.01). On the 7th,14th and 28th day point,there was statistical significance between every two groups(P<0.01). And in these groups ,the percentage of aFGF in the B group was the most high.The quantity of cells which express aFGF in the B group were the most large than that in other groups. In the D group , aFGF was mostly expressed in macrophagus,and in A group ,there was little in the A group.Conclusions:1 LMWH can reduce the degree of fibrosis of the rats.2 TGF-β1 has a great role in the process of pulmonary fibrosis.3 There is the same tendency between the degree of pulmonary and the content of the aFGF of the tissue.4 The functiong of LMWH reducing the degree of pulmonary fibrosis of rats might have the relation of the function of aFGF inhibiting tissue damage.
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