Study On The Variation Of MMP-9、MMP-2in The Development Of Silicosis

[Objective]In this study,we divided the whole experiment into two parts:animal experimentand population study.we observed the variation of MMP-9、MMP-2of pulmonaryinflammatory response and fibrosis caused by free silica.Exploring the changing rulesof MMP-9、MMP-2in the occurrence and development of silicosis.We study the earlydiagnosis of biological markers in pulmonary fibrosis from the protein level.Toprovide evidence for the prevention of silicosis level.[Methods]1.Animal experiments:We selected84male rats of Wistar and they wererandomly divided into control group and exposed to silica group (50mg/ml). The ratswere set up the Silicosis model by non-indiscretion.We randomly selected7rats afterexposed to silica dust on the3th,7th,14th,21th,28th,60thday in each group and the ratswere sacrificed.(1)we collected BALF about3-5ml,counting the inflammatorycells;Measured the content of MMP-2、MMP-9by ELISA.(2)The lung tissues wereselected and stained by HE.Determinating the expression of MMP-2、MMP-9in lungtissue with immunohistochmistry SABC.2.Field detection method:We selected logistics staff without dust exposurehistory,workers exposure to silica and patients with silicosis respectively as controlgroup、dust exposure group、silicosis Ⅰ of group and silicosis Ⅱ of silicosis.Forthe four groups,conducted a questionnaire survey,sputum induction,processing sputumin the laboratory.then,measured the content of MMP-2、MMP-9in induced sputum ofdifferent stages of silicosis and workers exposed to dust respectively with ELISA. [Results]1.The variation of content of MMP-9、MMP-2in BALF of rats exposed to silicaIn BALF,compared with the control group,the content of MMP-9is significantlyhiger on7thand14th,the difference is significant(p<0.05),the increasing trend hasslowed down on21th、28thand60th,the difference was not significant(p>0.05).thecontent of MMP-2was significantly higher on14th、21thand28th,the difference wassignificant(p<0.05).the increasing trend has slowed down on60th，the difference is notsignificant(p>0.05).2.The variation of content of MMP-9、MMP-2in serum of rats exposed to silicaIn serum,the content of MMP-9is significantly higher on3th,7th,14thand21th,the difference is significant(p<0.05),the increasing trend has slowed down on28thand60th.the difference is not significant(p>0.05);the content of MMP-2issignificantly higher on7thand14th，the difference is significant(p<0.05),there was nosignificant0difference on other time points(p>0.05).3.the variation of inflammatory cells in BALF of rats exposed to silicaCompared with the control group,macrophages,neuteophils,lymphocytes and dustcells are all significantly higher on3th,7th,14th,21th,28thand60thafter rats staineddust.macrophages were significantly higher on3th,7th,14thand21th,the difference wassignificant(p<0.05),neuteophils were significantly higher on3th,7thand14th(p<0.05),lymphocytes were significantly higher on7th,14th,21thand28th(p<0.05),thenumber of dust cells were significantly increased on each time point.4.the expression of MMP-9、MMP-2in lung tissue of rats exposed silica byimmunohistochemistryMMP-9was weakly positive expression in some bronchial epithilial cells in thecontrol group.In dust exposure group,there are strong expression in mesenchymal cells of the pulmonary interstitium, alveolar septa,bronchial epithelial cells andmacrophages of the alveolar space on3th,7thand14th.On21th、28thand60th.there wasstill high expression,but compared with the first few times the number has shown aweaking trend.There was slight expression of MMP-2in lung tissue of control groupoccasionally. A small amount of expression around bronchi and alveolar septa on3thand7th.The positive expression of MMP-2showing a significant increasing trend on14th,21thand28th, the main expression sites were alveolar interstitial cells,alveolarmacrophages and alveolar septa.the positive expression was weakned on60th.5.Observations of the pathological changes of lung tissueIn control group,the lung tissue was congestived and inflammatory cells ocurredoccasionally, inflammatory response soon disappeared.In model group;On3th,the lungtissue begin congestiving and inflammatory cells infiltrationed;On7th,alveolar septawidened,edema significantly,inflammatory cells aggregation,macrophages andneutrophils were the main inflammatory cells;On14th,part of the lung tissue structurewere damaged;On21thand28th,alveolar septum were fractured,lymphocytes weremain inflammatory cells,fibroblasts can be seen occasionally.On60th,the alveolarstructure were severely damaged,and we can see a large number of fibroblastsappeared.6.The content of MMP-9、MMP-2in induced sputum of dust exposed workersIt appears the positive correlation between the level of MMP-9in the inducedsputum of dust exposed workers and the quantity of dust(p<0.05).7.the content of MMP-9、MMP-2in induced sputum of different development stagesof silicosisCompared with the control group and dust exposed worker group,the content ofMMP-9was significantly higher in ⅠandⅡ case group,the difference wassignificant(p<0.05),the defference between control group and dust exposed workergroup was not significant(p>0.05); the content of MMP-2also shows the same result with MMP-9.[Conclusions]1.we measured the content of MMP-9and MMP-2in BALF and serum of ratsexposed to silica,the results shows that:MMP-9was significantly increased in theearly inflammatory stage in rats,and MMP-2was significantly increased in the lateinflammatory stage.with the extension of time of dying dust,the content of MMP-9and MMP-2have shown a decreasing trend,at last,the level is the same as the controlgroup. The results prompt that MMP-9may be associated with epithilial basementmenmbrane injury,and MMP-2may play an important role in the regeneration ofalveolar epithelial cells and in the abnoumal repair of lung tissue.2.immunohistochemical results also show consistent results with the BALF andserum.the positive expression mainly in alveolar interstitial cells, alveolarmacrophages, alveolar type Ⅱ epithelial cells,lung bronchial epithelial cells andalveolar septa. It shows largely consistency of positive expression of cell type anddistribution zone.3.The pathological changes of lung tissue shows that: inflammatory cells infiltrationedand gathered,alveolar septal become thicked, fibrous tissue started proliferating,alveolar normal tissue structure has been severely damaged,it appeared fibrosis.4.The inflammatory response is the main expression in early stage of rats exposed tosilica,inflammatory cells(macrophages,neutrophils,lymphocytes and dust cells)changed regularly.It has great significance to the prevention and early diagnosis ofsilicosis.5.The change of MMP-2、MMP-9in induced sputum of dust exposed workers andsilicosis may reflect the degree of change of the pulmonary inflammatory response inthe development of silicosis.If the expression is too high in patients,we can selectsome matrix metalloproteinase inhibitor to reduce the degree of fibrosis.