RESUMO
Matrix metalloproteinases [MMP] have been associated with neonatal lung morbidity and MMP dysregulation contributes to the pathology of chronic and acute lung disorders. Most of the previous studies were performed in the 1[st] weeks of life of the preterm newborns. There are no data on the serum levels of MMP-2, MMP-9 or tissue inhibitors of matrix metalloproteinases [TIMP-1] from preterm infants recovering from lung morbidities. We aimed to compare MMP-2, MMP-9 and TIMP-1 levels in preterm and term infants hospitalized with their first episode of wheezing. We prospectively evaluated 18 preterm infants with a history of chronic lung disease, respiratory distress syndrome or oxygen therapy and 14 age- and sex-matched term infants who were admitted for a first episode of wheezing. We quantified total serum concentrations of MMP-2, MMP-9 and TIMP-1 to assess whether these serum markers levels were associated with the first episode of wheezing in infants with a history of oxygen therapy during the neonatal period. Upon hospitalization, MMP-2 and TIMP-1 levels were higher in preterm infants than in term infants. In contrast, there was no significant relationship between MMP-9 levels or the MMP-9/TIMP-1 ratio between preterm and term infants. The area under the receiver operating characteristic curve for MMP-2 was 0.70 [95% confidence interval [CI] 0.51-0.89]. The area under the curve for TIMP-1 was 0.78 [95% CI 0.61-0.94]. MMP-9, MMP-2 and TIMP-1 levels did not correlate with gestational age, gender or severity of wheezing. The negative proportion of MMP-9 to TIMP-1 that we detected in term infants was not present in preterm infants. The balance of MMP-9 to TIMP-1 may have been disrupted by lung damage in the premature infants. Overproduction of MMP-2 and TIMP-1 in the serum may be associated with the pathogenesis of wheezing in preterm infants