C. Delacourt et al., INCREASED 92-KD GELATINASE ACTIVITY FROM ALVEOLAR MACROPHAGES IN NEWBORN RATS, American journal of respiratory and critical care medicine, 151(6), 1995, pp. 1939-1945
Citations number
44
Categorie Soggetti
Emergency Medicine & Critical Care","Respiratory System
The functional immaturity of neonatal alveolar macrophages (AM) may co
ntribute to the increased susceptibility of neonates to lung injury. B
ecause the secretion of proteinases by neonatal AMs may be involved in
normal postnatal lung development and in repair after lung injury, we
evaluated the capacity of neonatal AMs to secrete 92 kD Type IV colla
genase. AMs were obtained by bronchoalveolar lavage from newborn rats
at different postnatal ages. Total gelatinase activity was measured by
zymography in AM-conditioned media. Spontaneous secretion of gelatina
se from AMs varied significantly with age, the highest levels being fo
und immediately after birth. Stimulation of AMs by PMA induced a four-
to fivefold greater increase in total gelatinase activity during the
first 10 d of postnatal life compared with adulthood. Using [H-3]gelat
in as the substrate, we found high free gelatinase activity only withi
n 24 h after birth; data obtained after exposing cells to natural surf
actant suggested that surfactant may account in part for this increase
in free gelatinase activity. No secretion of tissue inhibitor of meta
lloproteinases (TIMP) by AMs was detectable in newborns within 24 h af
ter birth. We conclude that AMs from newborn rats are able to secrete
more gelatinase than AMs from adults, and this enzyme production profi
le during the neonatal period may contribute to the fact that newborns
with lung injury are at high risk for extracellular matrix degradatio
n.