A Study On The Effect Of MMPs In The Pathogenesis Of Pulmonary Fibrosis And Regulating

Part I Effect of silicon dioxide on the expreeion of MT1-MMP inmacrophageObjective To investigate the expression of MT1-MMP under the stimulation ofsilicon dioxide in the primary macrophages in vitro.Methods Celiac macrophage were primary cultured, western-blot and RT-PCRanalysis were used to detect the expressions of MT1-MMP protein and the dynamicchange of MT1-MMPmRNA in the primary macrophages which were treated withsilicon dioxide within 0h, 2h, 6h, 12h, 18h, 24h.Results In the cells which were stimulated by silicon dioxide, there were increasedexpressions of MT1-MMP proteins and transcriptions of MT1-MMP during 2 to 24hours. The expression levels peaked at the 12th hour. Both the mRNAs and theproteins appeared to be the same tendency.Conclusions Silicon dioxide induced the expression of MT1-MMPmRNA andproteins, which might contribute to the mechanism of pulmonary fibrosis.Part II EGR-1 mediate SiO2 driven transcription of membranetype I matrix metalloproteinase in macrophageObjective To study the up-regulation mechanism of membrane type I matrix metalloproteinase (MT1-MMP) in macrophage stimulated by silica in vitro, and the contribution of early growth response 1 (Egr-1) transcription factor in the gene expression pathway.Methods Macrophages stimulated by silica were treated with Egr-1 antibody or Egr-1 decoy oligodeoxynucleotides(ODN). The levels of MT1-MMP proteins were determined by western blot and the expression of MT1-MMP mRNAs was detected by RT-PCR. Results Compared with control macrophages, silica stimulated group showed up-regulated gene expression of MT1-MMP via Egr-1(p<0.01). Compared with silica-stimulated macrophages untreated with antibody, the cells treated with 5μg/ml Egr-1 antibody were associated with reduced expression of MT1-MMP proteins(p<0.01) and mRNAs(p<0.05). Compared with silica-stimulated untransfected group, the Egr-1 "decoy" ODN group was associated with reduction in expression of MT1-MMP proteins and mRNAs(p<0.01).Conclusions Gene expression of MT1-MMP which may play a critical role in silicosis was up-regulated by silica in macrophage. Egr-1 participated in the expression of MT1-MMP and positively regulated the expression. Both Egr-1 antibody and Egr-1 decoy ODN suppressed the expression of MT1-MMP through the Egr-1 pathway and may become a potential therapeutic tool in the management of silicosis in the future. PartIII Study on the treatment mechanism of Pentoxifylline to thepulmonary fibrosisObjective To investigate the treatment Pentoxifylline to the mouse with pulmonary fibrosis and to study the mechanism.Methods Thirty Spague-Dawley rats were randomly divided into three groups. The model group and the treatment group were injected with bleomycin endotracheally, while empty group with normal saline instead in the same condition. From the second day the treatment groups were injected with Pentoxifylline endoceliacly with 6mg/kg.d. while the other groups with normal saline instead. On the seventh day and the twenty-eighth day the lungs were isolated. The mRNA expression of MMP-2 and TIMP-1 were evaluated by RT-PCR quantity analysis also the immunohistochemical method was used to investigate the change of MMP-2 and TIMP-1. Results The MMP-2 and TIMP-1 gene expression of the Pentoxifylline treatment groups decreased on the 7th and 28th day and the immunohistochemical showed the same result.Conclusions The treatment mechanism of Pentoxifylline to pulmonary fibrosis is probably that it can adjust the ratio of MMP-2 /TIMP-1 and make the ratio to a state of balance, to make the process of pulmonary fibrosis go slowly and even block it.