Rosiglitazone Ameliorates Bleomycin-induced Rats' Pulmonary Fibrosis By Adjusting MicroRNAs Expression

Background and Objective:Idiopathic pulmonary fibrosis(IPF)is a chronic,progressive interstitial lung disease of unknown etiology,and there is no sufficient evidence to support the use of any specific pharmacologic therapy.Due to progressive dyspnea and intractable cough,the patients with IPF have a poor quality of life.At present,due to no effective treatment,the IPF patients have a poor prognosis and the median survival after diagnosis is 3-5 years.It is reported that the incidence of IPF is increasing worldwide,but its pathophysiological mechanism is not clear and IPF is lack of effective treatment.The pathophysiology of IPF and the therapeutic agents have been the focus of research at home and abroad.Micro RNAs(miRNAs)is a class of non coding RNAs composed of about 19-22 nucleotides,which regulates gene expression at the post transcriptional level.The aberrant expressions of miRNAs,such as let-7d,mi RNA-21,mi RNA-155,play an important role in the pathogenesis of pulmonary fibrosis.These miRNAs provide a new way to understand the pathogenesis and clinical treatment of pulmonary fibrosis,and might be novel potential targets.Rosiglitazone(RSG)belonging to TZDS,is a new type of insulin sensitization agent and the synthetic ligands of peroxisome proliferator activated receptor gamma(PPAR?)synthetic ligand.Rosiglitazone usually is used for the treatment of type 2 diabetes in clinical.In recent years,it has been found that PPAR? and its ligands may participate in the occurrence and development of fibrosis in kidney,liver and lung.Researchers have used different techniques to clear and define the beneficial effect of rosiglitazone on pulmonary fibrosis.It has been reported that the synthetic ligand of PPAR can block the TGF-?1/Smad signaling pathway and inhibit the fibrosis induced by TGF-?1.However,the molecular mechanism of rosiglitazone in the treatment of pulmonary fibrosis is still unclear and needs further study.Through this experiment we can observe whether the aberrant expres sions of miRNAs have a hand in the process of the attenuation of bleo mycin-induced rats' pulmonary fibrosis,and to explore whether this expr-ession change of miRNAs is related to the TGF-?1 signaling system.Method:54 male and healthy Wistar rats weighed 120-130 g,were randomly allocated to 3 groups that contained 18 mice per group: Control group,bleomycin group(BLM group),bleomycin + rosiglitazone group(BLM+RSG group).The latter two groups of rats received a single intratracheal injection bleomycin(5mg/kg)to establish a rat model of pulmonary fibrosis.Control rats received an equal volume of normal saline only.After 24 hours,the rats in group BLM+RSG were treated with RSG(3mg/kg.d).The rats in the remaining two groups were treated with the same volume of normal saline.Six animals in each group were sacrificed on days7,14 and28.Then the middle lobe of right lung was used for pathological observation by hematoxylin and eosin(HE)staining and Masson's trichrome staining.Superior lobe of right lung was used to measure expressions of mi RNA-21,mi RNA-155 and let-7d by Real time RT-PCR and to detect the expression of TGF-?1 by immunohistochemistry.SPSS21 statistical software was used for statistical analysis of test data,and P<0.05 was statistically significant.Result:1 The results of pulmonary pathology: On day 7,14 and 28,the Control group had normal alveolar structure and a few collagen fibers.On 7th day,compared with the Control group,the degree of alveolitis of BLM group was more serious(P<0.05).Compared with the Control group,the degree of pulmonary fibrosis was aggravated gradually in the BLM group on the 14 th day and 28 th day(P<0.05).Thus the model of BLM-induced pulmonary fibrosis in rats was reproduced successfully.After RSG treatment,the degrees of alveolitis and pulmonary fibrosis in the lungs of the rats in BLM+RSG group were remarkably ameliorated compared with those in BLM group(P <0.05).2 Real time RT-PCR results: On day 7,14 and 28,the expressions of mi RNA-21 and mi RNA-155 in BLM group were significantly higher than that in Control group(P<0.05),While let-7d expression decreased(P<0.05).After RSG treatment,the expressions of mi RNA-21 and mi RNA-155 in the BLM+RSG group were significantly lower than that in the BLM group on each time point(P<0.05),While the expression level of let-7d expression increased(P<0.05).3 The results of immunohistochemistry: On day 7,14 and 28,the expression level of TGF-?1 in BLM group was significantly higher than that in the Control group(P<0.05).After RSG treatment,the expression level of TGF-?1 in the BLM+RSG group was lower than that in the BLM group on each time point(P<0.05).4 Correlation analysis between TGF-?1 and miRNAs: The expressions of mi RNA-21 and mi RNA-155 in BLM group and BLM+RSG group on day 7,14 and 28 were positively correlated with TGF-?1(P<0.05),while the expression of let-7d was negatively correlated with TGF-?1(P<0.05).Conclusion:1 Rosiglitazone can attenuate bleomycin-induced rats' pulmonary fibrosis.2 In the treatment of pulmonary fibrosis with rosiglitazone,the expressions of mi RNA-21 and mi RNA-155 were up-regulated,and the expression of let-7d was down regulated.3 Rosiglitazone may alleviate bleomycin-induced pulmonary fibrosis in rats by regulating miRNAs and TGF-?1 signaling pathway.