| Pulmonary fibrosis is a serious disease which is harming for humanhealth.It’s usually caused by severe injury,infection, spontaneous immune reaction, toxic substances, and adverse drug reaction, leading to persistant lung damage, accumulation of extracellular matrix and excessive reconstruction.At last normal lung tissue structure will be changed and normal lung function will be lost. Pulmonary fibrosis is a complex pathological process, each process has a variety of cells and cytokines involved in.Until now,the pathogenesis of pulmonary fibrosis is not fully understood.Previous studies of the pathogenesis of pulmonary fibrosis frequently focused on regulation of the activation of proliferation, differentiation and collagen-secreting of myofibroblasts. Recent years a large number of clinical and experimental studies have identified that the number of inflammatory cells, proteins and enzymes, cytokines in BALF has abnormally increased during pulmonary fibrosis. It suggested that the interaction between them and the lung tissue cells plays an important role in the formation process of pulmonary fibrosis, and inhibition of early inflammatory reaction may also be a kind of effective means to prevent fibrosis formation.MLN4924 was a specific inhibitor of NEDD8 activation enzyme(NAE). It is AMP analogues, and inhibits the NAE activity via forming a complex with NAE. Thereby it inhibits Cullin-Ring E3 ligase (CRL) activity, blocks cullin neddylation, which leads to the accumulation of multiple CRL substrates. The CRL substrates includes DNA replication licensing protein CDT1 and ORC1, cell cycle inhibitors such asp21, p27and Wee1. Previously, reports about MLN4924 frequently concentrated on its antitumor properties. Yet the role of MLN4924 in inflammatory reponse remains elusive, and through looking up the literature we found that IκB-α is also one substrate of CRL, which is the inhibitor of NF-κB pathway. This interesting report suggests us that MLN4924 should have a certain role in the inflammatory response.In this study, we established acute lung injury and pulmonary fibrosis animal models, and chose MLN4924 which has been proved posses antitumor activity to test its fuctions and mechanism in pulmonary fibrosis.Here are the main points of the dissertation as below.1. MLN4924 can effectively suppress the pulmonary fibrosis lesion in mice induced by bleomycinPulmonary fibrosis model was established through intratracheal instillation of bleomycin (15mg/kg) in mice, MLN4924 was administrated through intraperitoneal injection the second day after that. At 28d, lung tissues were collected. Right lung received HE andMasson staining, the changes in structure was observed under microscope. Left lung was used to detect the content of HYP and collagens through acid olysis method. The results show that, compared with the control group, administration of MLN4924 can significantly improve the symptoms of pulmonary fibrosis caused by bleomycin in mice.2. MLN4924 inhibits the symptoms of acute lung injury in the early stage of pulmonary fibrosis Mice were subjected to LPS injection with or without MLN4924 treatments to induce ALI model.In 12h,24h,48h, lung tissues were collected for HE staining detection of wet weight to dry weight ration.At the same time,the BALF was collected for detecting the contents of total protein, nucleated cells cell, neutrophils and macrophages. The physiological indexes and the experimental results show that the MLN4924 can effectively reduce acute lung injury in mice induced by LPS.3.The molecular mechanisms of the suppressive effect of MLN4924 on aute lung injury in miceAs we know, nuclear transcription factor NF-κB plays an extremely important role in regulating the inflammatory response, and its inhibitors IκB-α is one of the CRL substrates. So it’s easy to think of MLN4924 may have a certain role in early inflammation of pulmonary fibrosis through interacting with NF-κB pathway. At the same time the MAPK signal pathway also play an important role in the immune response. In this section, we mainly explore impact of MLN4924 on NF-κB and MAPK signal pathway in inflammatory stages. By western blot experiments we are surprised to find that, MLN4924 treatment can significantly inhibit the degradation of IκB-α, which inhibits the activity of the NF-κB signaling pathways, but for the MAPK signaling pathway there is no obvious effect.From what has been discussed above, we draw the following conclusions:1.MLN4924 can reduce the pulmonary fibrosis lesions through inhibiting early inflammatory response2.The suppressive effect of MLN4924 on inflammatory was through NF-κB pathway. |
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