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Infection and Immunity, May 2001, p. 3248-3254, Vol. 69, No. 5
Department of Preventive Science, School of
Dentistry, University of Minnesota, Minneapolis, Minnesota 55455
Received 26 June 2000/Returned for modification 7 September
2000/Accepted 19 January 2001
Calprotectin, a heterodimer of MRP8 and MRP14 with antimicrobial
properties, is found in the cytosol of neutrophils, monocytes, and
human gingival keratinocytes. During inflammation of the oral mucosa,
the expression of immunoreactive calprotectin appears upregulated.
Given the possible cell sources, we sought to learn if epithelial cells
upregulate calprotectin in response to proinflammmatory agents. First,
human gingival keratinocytes were maintained in primary culture until
senescence. At each passage, cells were harvested and analyzed for
quantitative expression of MRP8 and MRP14 subunit mRNA by RNase
protection assays and calprotectin complex by enzyme-linked
immunosorbent assay. Calprotectin expression was constitutive in the
primary gingival keratinocytes, but calprotectin-specific mRNA and
protein tended to increase as the cells neared senescence. To test
whether calprotectin expression was inducible, immortalized gingival
keratinocyte cultures were treated for 2 to 4 h with lipopolysaccharide (LPS) or interleukin-1
0019-9567/01/$04.00+0 DOI: 10.1128/IAI.69.5.3248-3254.2001
Copyright © 2001, American Society for Microbiology. All rights reserved.
Calprotectin Expression by Gingival
Epithelial Cells
(IL-1
). As a positive control for inducible expression, immortalized keratinocytes were incubated with phorbol myristate acetate (PMA) (50 ng/ml) for 24 h. Incubation with PMA stimulated increased expression of MRP8 and
MRP14 mRNA within 2 h, peaking within 5 h. MRP8- and
MRP14-specific mRNA expression by immortalized keratinocytes appeared
to be unaffected by LPS or IL-1
. In contrast, LPS, IL-1
, and PMA
each upregulated IL-8. These data show that calprotectin mRNA is
expressed constitutively in cultured keratinocytes, while expression by
immortalized cells appears to be independent of the exogenous
proinflammatory agents LPS and IL-1
.
*
Corresponding author. Mailing address: Department of
Preventive Science, School of Dentistry, University of Minnesota,
17-164 Moos Tower, 515 Delaware St., SE, Minneapolis, MN 55455-0348. Phone: (612) 625-8404. Fax: (612) 626-2651. E-mail:
mcherzb{at}tc.umn.edu.
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