Direct and phagocyte-mediated lipid peroxidation of lung surfactant by group B streptococci.
In newborn infants, group B streptococci (GBS) often cause pneumonia, with polymorphonuclear leukocytes (PMN) migrating into the lungs. Because surfactant therapy may be needed in such patients, we evaluated the interaction between GBS or GBS-stimulated PMN and a surfactant preparation (Curosurf) in vitro. The superoxide production of GBS strains or GBS-activated PMN was measured, using the nitroblue tetrazolium (NBT) test and the subsequent lipid peroxidation (LPO) as the content of malondialdehyde (MDA) and 4-hydroxyalkenals (4-HNE). The growth of GBS in surfactant was determined and related to the LPO. Finally, the effect of LPO on surfactant activity, caused by GBS-stimulated PMN, was assessed by measuring dynamic surface tension in a pulsating bubble surfactometer. Curosurf diminished the NBT reduction by both live GBS and GBS-stimulated PMN. Surfactant was peroxidized by reactive oxygen species (ROS) from both GBS and GBS-stimulated PMN in a time-dependent manner. Vitamin E significantly reduced the peroxidation level of surfactant in both cases. Surfactant peroxidation was associated with a reduction in the number of live bacteria. The biophysical activity of Curosurf was impaired by GBS-stimulated PMN, as reflected by increased minimum surface tension during cyclic compression. These findings indicate that Curosurf undergoes LPO by ROS produced by GBS and/or PMN. We speculate that exogenous surfactant preparations should be supplemented with vitamin E or another antioxidant, when given to infants with GBS pneumonia.
Bouhafs
R K
RK
Department of Immunology, Microbiology, Pathology and Infectious Diseases, Division of Oral and Clinical Bacteriology, Karolinska Institutet, Huddinge Hospital, Stockholm, Sweden.
Rauprich
P
P
Herting
E
E
Schröder
A
A
Robertson
B
B
Jarstrand
C
C
D000328:Adult; D001688:Biological Products; D006801:Humans; D015227:Lipid Peroxidation; D008315:Malondialdehyde / Q000378:metabolism; D018375:Neutrophil Activation / Q000502:physiology*; D009504:Neutrophils / Q000378:metabolism* / Q000382:microbiology; D010743:Phospholipids; D011663:Pulmonary Surfactants / Q000378:metabolism*; D017382:Reactive Oxygen Species / Q000378:metabolism*; D013292:Streptococcus agalactiae / Q000502:physiology*; D013481:Superoxides / Q000378:metabolism; D013997:Time Factors; D014810:Vitamin E / Q000494:pharmacology
D001688:Biological Products; D010743:Phospholipids; D011663:Pulmonary Surfactants; D017382:Reactive Oxygen Species; D013481:Superoxides; D014810:Vitamin E; D008315:Malondialdehyde; C068291:poractant alfa