Vol. 284, Issue 1, L69-L76, January 2003
Fibrinolysis-inhibitory capacity of clot-embedded surfactant
is enhanced by SP-B and SP-C
Philipp
Markart,
Clemens
Ruppert,
Friedrich
Grimminger,
Werner
Seeger, and
Andreas
Günther
Department of Internal Medicine,
Justus-Liebig-University-Giessen, D-35385 Giessen, Germany
Incorporation of pulmonary surfactant into
fibrin inhibits its plasmic degradation. In the present study we
investigated the influence of surfactant proteins (SP)-A, SP-B, and
SP-C on the fibrinolysis-inhibitory capacity of surfactant
phospholipids. Plasmin-induced fibrinolysis was quantified by means of
a 125I-fibrin plate assay, and surfactant incorporation
into polymerizing fibrin was analyzed by measuring the incorporation of
3H-labeled L-
-dipalmitoylphosphatidylcholine into the
insoluble clot material. Incorporation of a calf lung surfactant
extract (Alveofact) and an organic extract of natural rabbit large
surfactant aggregates (LSA) into a fibrin clot revealed a stronger
inhibitory effect on plasmic cleavage of this clot than a synthetic
phospholipid mixture (PLX) and unprocessed LSA. Reconstitution of PLX
with SP-B and SP-C increased, whereas reconstitution with SP-A
decreased, the fibrinolysis-inhibitory capacity of the phospholipids.
The SP-B effect was paralleled by an increased incorporation of
phospholipids into fibrin. We conclude that the inhibitory effect of
surfactant incorporation into polymerizing fibrin on its susceptibility
to plasmic cleavage is enhanced by SP-B and SP-C but reduced by SP-A. In the case of SP-B, increased phospholipid incorporation may underlie
this finding.
hyaline membrane; coagulation; pulmonary surfactant; surfactant
protein; acute respiratory distress syndrome; fibrosis
