The Expressions Of Monocyte Chemoattactant Protein-1 And Metalloproteinase-9 In The Lung Tissue Of Emphysema Rat Models

Objective Emphysema refers to the abnormity of the outlaying airway and the consistent enlargement accompanied by the destruction of alveolus wall at the end of the thin bronchia. Its pathogenesis has not been clarified up to now; it is generally considered that many factors cooperate with each other to cause the emphysema. Each factor causing chronic bronchia like infection, smoking, air pollution, long inhalation of vocational dust and bad gas, allergy may cause emphysema, in which the most dangerous one is smoking. This research is to establish emphysema rat models by smoking as well as intratracheal instillation lipolysaccharide (LPS) respectively, and to study the express of Monocyte chemoattractant protein-1(MCP-1) and metalloproteinase-9(MMP-9) in lung tissue, and the correlations among them and alveolar macrophage (AM) number in BALF, and to explore the role of MCP-1 and MMP-9 in the pathogenesis of emphysema and the effects of doxycycline on it.Methods The first is that 32 Wistar male healthy rats, with 12-week life, and the weight of 230 grams each (more or less 20 grams), were randomly divided into four groups (Group A: Normal control group,Group B: emphysema model group, Group C: doxycycline-treatment group, Group D: doxycycline-prevention group). The emphysema rat models which was established by intratracheal instillation of 200μ g/200μ l lipopolysaccharide once for every two weeks (twice) , and exposed to smoke for 2h per day for 4 weeks. Doxycycline was given to the rats of Group C through stomach injection at a dose of 25mg/kg just before exposure to cigarettes smoke everyday from the 15th day. Its smoking condition and lasting time is the same with Group B; the same was done to Group D from three days before establish the rat models.The second is that bronchial alveolar lavage (BAL) were performed as usual. Total cell number and AM number in BALF were counted using a hemacytometer. The pathological changes were observed. The expressions of MCP-1 and MMP-9 in lung tissue were detected by immunohistochemistry. The correlations among the expression of MCP-1, the expression of MMP-9 and AM number in emphysema model were analyzed.The third is that the data from the experiment were processed by using the SPSS10.0 statistical software and a equals 0.05 was taken as the testing standard of whether the difference having statistical significance.Results The first is to establish emphysema rat models by smoking as well as intratracheal instillation lipolysaccharide (LPS) respectively. The pathological changes of bronchi shows in emphysema rat models that the alveolus antrums irregularly expanded to some extent. Alveolus structure was disorganized, the space between alveolus became thinner or breaks, breathing thin bronchia expanded as theca, some alveoli syncretized into big alveolus, which was similar to those of the emphysema patients.The second is that the total cell number in BALF of each group respectively is (2.45 ± 0.72) ×108/L, (5.56±1. 10) ×108/L, (4.26 ± 0.97)×108/L, (3. 96±0. 44) ×108/L; AM number in BALF of each group respectively is (1.90±0. 36) × 108/L, (5. 03 ± 0. 43)× 108/L, (3.67±0. 22) ×108/L, (3. 34 ±0.44) ×108/L. The total cell number and AM number in BALF of Group B significantly increased than those of Group A(P<0.01); The total cell number and AM number in BALF of Group C, D significantly decreased than those of Group B(P<0.01).The third is that the expression of MCP-1 in each group is 1.94 ± 0.52, 3. 20±0. 55, 2. 69 ± 0. 45, 2.22 ± 0.60; the expression of MMP-9 in each group is 1.27 ± 0.45, 3.04 ± 0.62, 2.64 ± 0.57, 1.85 ± 0.70. The expressions of MCP-1, MMP-9 in Group B were significantly increased than those in Group A( P<0.01) ; The expressions of MCP-1, MMP-9 in Group C, D were decreased than those in Group B(P<0.05); The expressions of MCP-1, MMP-9 in Group D were decreased than those in Group C(P<0.01) .The fourth is that positive correlations were demonstrated not only between the expressions of MCP-1 and AM number, the expressions of MMP-9 and AM number respectively (r=0.832, P<0.01; r=0.882, P<0.01), but also between the expression of MCP-1 and MMP-9 (r=0. 917, P<0.01) in emphysema model group.Conclusion The first is that the experiment establishes emphysema rat models by smoking to cigarette for 4 weeks as well as intratracheal instillation lipolysaccharide (LPS) respectively. Its pathological changes accord with the emphysema, which demonstrates the copy of model succeeds.The second is that MCP-1 and MMP-9 expresses clearly in emphysema wall, alveolar macrophage and airway wall in emphysema model group. The difference between MCP-1 and MMP-9 in each experiment group and control group have statistical significance, which proves that MCP-1 and MMP-9 is crucial in the formation of emphysema.The third is that MCP-1 may contribute to the development of emphysemaby recruiting and activating AM to enter lung on secreting inflammatory cytokines. The ECM degradation and deposition were imbalanced and abnormally activated by MMP-9. The cooperation of MCP-1, MMP-9 and AM may be responsible for the development in emphysema.The fourth is that doxycycline may inhibit the activity of MCP-1 and MMP-9.The expression magnitude has statistical significance between doxycycline-treatment group and doxycycline-prevention group. Therefore doxycycline should be taken in a long term to relieve the inflammation reaction in the lung and the tissue destruction, and to decrease the decomposing of ECM in alveolar wall and the possibility of getting emphysema by smoking. The treatment time is better to choose the time of quitting smoking, and the earlier the better, which provides the new idea for the treatment of emphysema and the new direction for the COPD.