Localization and activity of recombinant human cu/zn superoxide
dismutase following intratracheal administration.
Sahgal, Namita, Jonathan M. Davis, Carolyn Robbins, Stuart Horowitz,
Edward G. Langenback, Robert H. Perry, David Colflesh, Joan Tierney,
Sanford R. Simon.
The Department of Pediatrics (Neonatology) and the CardioPulmonary
Research Institute, Winthrop University Hospital, SUNY Stony Brook
School of Medicine, Mineola, NY and Departments of Medicine
(Pulmonary) and Pathology, SUNY Health Science Center, Stony Brook,
NY
APStracts 3:0055L, 1996.
Hyperoxia and mechanical ventilation cause acute lung injury which may
be mitigated by prophylactic intratracheal (IT) administration of
recombinant human Cu/Zn superoxide dismutase (rhSOD). However, little
is known about the localization, activity and metabolism of rhSOD
after IT administration by instillation or nebulization. Twenty-six
newborn piglets were intubated and mechanically ventilated. rhSOD
(5mg/kg) was labeled with a fluorescent dye, purified and
administered IT by instillation or nebulization. Animals received
either rhSOD (n=22) or placebo (n=4). Animals treated with rhSOD were
sacrificed after 1, 6 or 12 h, while the control animals were
sacrificed immediately. Lung tissue was homogenized in detergent.
Intact fluorescent-rhSOD was expressed as % total fluorescence in the
supernatant still associated with macromolecules. Results indicate
that after 1 h of administration (89.8 + 3.2%) and 6 h (84.2 + 6.3%),
fluorescence was still present in the lung and associated with rhSOD.
By 12 h, only 42.0 + 4.0% of the fluorscence was still associated
with rhSOD. When first measured at 1 h, total lung SOD activity
increased by 100% compared to untreated control values (12.3 + 2.0 to
24.6 + 1.5 U/mg protein), with activity remaining significantly
elevated at 6 h (16.8 + 2.4) and 12 h (16.6 + 1.4). Lung tissue was
examined by laser confocal microscopy which showed that at 1 h,
labeled rhSOD was found throughout the lung, inside a variety of cell
types of airways, respiratory bronchioles and alveoli. Deposition was
more homogeneous following nebulization. Negative controls had
minimal background fluorescence. These data indicate that a portion
of the administered rhSOD is incorporated into cells in the lung
within one hour, approximately doubling lung SOD activity for up to
12 h. These observations have important implications for the clinical
use of rhSOD in human trials.
Received 5 September 1995; accepted in final form 28 March 1996.
APS Manuscript Number L269-5.
Article publication pending Am. J. Physiol. (Lung Cell. Mol.
Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 16 April 96