To observe the effect of dexamethasone on airway remodeling and to explore significance of the balance between matrix metalloproteinase and tissue inhibitor of metalloproteinase.
Thirty male Wistar rats were randomly divided into asthmatic group (n=10), dexamethasone group (n=10) and control group (n=10). Lung tissues were sliced and stained with H.E. The following parameters that reflects thickness of airway wall were measured by image analysis system: bronchial basement membrane perimeter (Pbm), total bronchial wall area (WAt), inner wall area (WAi) and smooth muscle area (WAm). Expression levels of MMP-2 and TIMP-1 mRNA in the lungs were assessed by semiquantitative reverse transcription-polymerase chain reaction (RT-PCR).
(1) WAt/Pbm,WAi/Pbm and WAm/Pbm in asthmatic group [(25.3±2.1)μm2/μm, (20.4±2.3)μm2/μm, (4.2±2.0)μm2/μm, respectively] were significantly higher than that in control group [(20.8±1.3)μm2/μm,(15.3±2.1)μm2/μm, (3.1±1.1)μm2/μm](p<0.01). The differences between control and dexamethasone group [(21.3±2.4)μm2/μm, (14.2±2.5)μm2/μm, (3.2±1.0)μm2/μm] were not statistically significant (p>0.05). (2) MMP-2 and TIMP-1mRNA levels in asthmatic group [(0.68±0.14), (0.56±0.10)] and dexamethasone group [(0.37±0.11), (0.31±0.10)] were significantly higher than that in control group [(0.14±0.03), (0.11±0.05)]. The differences between asthmatic group and dexamethasone group were also significant (p<0.01). (3) In control and dexamethasone group (r=0.67,0.58.p<0.05) but not in asthmatic group (r=0.24, p>0.05), there was a significantly positive correlation between MMP-2 and TIMP-1 mRNA.
Dexamethasone could prevent airway remodeling by downregulating expression of MMP and TIMP and restoring the balance between MMP and TIMP.
Selective MMP inhibitors may provide a novel strategy for treatment of asthma.
Y. Yuan, None.