Total extracellular surfactant is increased but abnormal in a rat model of gram-negative bacterial pneumonia.
An in vivo rat model was used to evaluate the effects of Escherichia coli pneumonia on lung function and surfactant in bronchoalveolar lavage (BAL). Total extracellular surfactant was increased in infected rats compared with controls. BAL phospholipid content in infected rats correlated with the severity of alveolar-capillary leak as reflected in lavage protein levels (R(2) = 0.908, P < 0.0001). Western blotting showed that levels of surfactant protein (SP)-A and SP-D in BAL were significantly increased in both large and small aggregate fractions at 2 and 6 h postinstillation of E. coli. SP-B was also increased at these times in the large aggregate fraction of BAL, whereas SP-C levels were increased at 2 h and decreased at 6 h relative to controls. The small-to-large (S/L) aggregate ratio (a marker inversely proportional to surfactant function) was increased in infected rats with >50 mg total BAL protein. There was a significant correlation (R(2) = 0.885, P < 0.0001) between increasing S/L ratio in BAL and pulmonary damage assessed by total protein. Pulmonary volumes, compliance, and oxygen exchange were significantly decreased in infected rats with >50 mg of total BAL protein, consistent with surfactant dysfunction. In vitro surface cycling studies with calf lung surfactant extract suggested that bacterially derived factors may have contributed in part to the surfactant alterations seen in vivo.
Russo
Thomas A
TA
Department of Medicine, State University of New York at Buffalo, Buffalo 14214, USA. trusso@acsu.buffalo.edu
Bartholomew
Lori A
LA
Davidson
Bruce A
BA
Helinski
Jadwiga D
JD
Carlino
Ulrike B
UB
Knight
Paul R
PR
Beers
Michael F
MF
Atochina
Elena N
EN
Notter
Robert H
RH
Holm
Bruce A
BA
D000818:Animals; D001992:Bronchoalveolar Lavage Fluid / Q000737:chemistry; D015169:Colony Count, Microbial; D004926:Escherichia coli / Q000502:physiology; D005110:Extracellular Space / Q000378:metabolism*; D016905:Gram-Negative Bacterial Infections; D010743:Phospholipids / Q000032:analysis; D018410:Pneumonia, Bacterial / Q000378:metabolism* / Q000382:microbiology* / Q000503:physiopathology; D011506:Proteins / Q000032:analysis; D011663:Pulmonary Surfactants / Q000378:metabolism*; D051381:Rats; D020318:Rats, Long-Evans
D010743:Phospholipids; D011506:Proteins; D011663:Pulmonary Surfactants