Changes of MMP-8 and TIMP-2 expression in the lung tissue of neonatal rats with hyperoxia induced lung injury

Objective To investigate the dynamic changes of matrix metalloproteinase-8(MMP-8) and tissue inhibitors of metalloproteinase-2(TIMP-2) in lungs of neonatal rats with lung injury induced by hyperoxia and their effects on fibrosis of CLD.Methods Full-term newborn rats were continuously exposed to oxygen(0.90～0.95) or room air(0.21 O2) after birth within 12 hours.Using Masson staining,the areas of collagenic fibres were measured by imaging analysis;the changes of MMP-8 and TIMP-2 mRNA and protein expression were measured by RT-PCR and immunohistochemical method on days 1,3,7,14 and 21 in two groups.Results After 7 d of hyperoxia exposure,collagenic fibres began to deposit in interstitum,the areas were larger than those in room air groups;expression of MMP-8 mRNA and protein was decreased from 7 d to 21 d in hyperoxia groups;expression of TIMP-2 mRNA and protein showed no change all the time.Conclusion With prolonged hyperoxia exposure,the balance of MMP-8/TIMP-2 can not be kept,collagen breakdown is inhibited,which maybe leads to collagen deposition in lung interstitium.