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Infection and Immunity, December 2000, p. 6611-6617, Vol. 68, No. 12
Department of Pediatrics, Pennsylvania State
University College of Medicine, Hershey, Pennsylvania 17033
Received 12 July 2000/Returned for modification 11 August
2000/Accepted 6 September 2000
Pulmonary surfactant protein A (SP-A) is involved in innate
immunity in the lung. In this study we investigated the interaction of
SP-A with different serotypes of lipopolysaccharide (LPS) on the
regulation of inflammatory cytokines in vitro. In the human monocytic
cell line, THP-1, combining SP-A with lipid A or rough LPS further
enhanced lipid A- or rough LPS-stimulated tumor necrosis factor alpha
(TNF-
0019-9567/00/$04.00+0
Copyright © 2000, American Society for Microbiology. All rights reserved.
Interaction of Surfactant Protein A with Lipopolysaccharide and
Regulation of Inflammatory Cytokines in the THP-1 Monocytic
Cell Line
) mRNA levels, while SP-A-elicited increases in TNF-
mRNA
levels were partially neutralized. In contrast, the combination of
smooth LPS and SP-A resulted in additive effects on TNF-
mRNA
levels. We also demonstrated that there was cross-tolerance between
SP-A and LPS in THP-1 cells. Pretreatment of THP-1 cells with LPS
modestly inhibited the response of these cells to subsequent challenge
with SP-A, with regard to the production of TNF-
, whereas there was
no or little effect on the production of interleukin-1
(IL-1
) and
IL-8. Conversely, pretreatment of THP-1 cells with SP-A markedly
increased the response to subsequent challenge with LPS with regard to
the production of IL-1
and IL-8, although the production of TNF-
was modestly decreased. However, a synergistic stimulatory effect was
observed when the two agents were added simultaneously to the cells.
NF-
B formation was downregulated in SP-A- but not in LPS-induced
tolerant cells. These results suggested that SP-A exhibits different
interactions with distinct serotypes of LPS. In addition, SP-A is
different from LPS with regard to the induction of cross-tolerance, and
these actions may be mediated, at least in part, through different mechanisms.
*
Corresponding author. Mailing address: Department of
Pediatrics, Rm. C7814, The Pennsylvania State University College of
Medicine, P.O. Box 850, Hershey, PA 17033. Phone: (717) 531-5925. Fax:
(717) 531-8985. E-mail: dsp4{at}psu.edu.
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