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Antimicrobial Agents and Chemotherapy, June 2000, p. 1485-1493, Vol. 44, No. 6
Department of Oral Biology, State University
of New York at Buffalo, Buffalo, New York 14214
Received 29 October 1999/Returned for modification 10 December
1999/Accepted 6 March 2000
Human salivary histatin-5 (Hsn-5) is a 24-residue peptide that
possesses potent antifungal activity in vitro. The MUC7
gene encodes human salivary low-molecular-weight mucin (MG2). The
candidacidal activity of MUC7 domain 1 (MUC7 D1, the N-terminal
51 amino acid residues of MUC7) in vitro has also been
demonstrated. In this study, we have investigated the
antifungal therapeutic potential of Hsn-5, its two variants, R12I/K17N
and R12I/H21L, and MUC7 D1. First, these peptides were tested for
activities against different clinically important fungi. We found them
to possess broad-spectrum antifungal activities; specifically, most
exhibited excellent in vitro activity against eight clinically
important fungal strains tested, including Candida albicans
and Candida glabrata and their azole-resistant counterparts
and Cryptococcus neoformans and its amphotericin
B-resistant counterpart. These findings also suggest that the mechanism
of action of both Hsn-5 and MUC7 D1 for these fungi is different from
that of amphotericin B or azole antifungal agents. Second, we examined
the stability of these peptides in whole human saliva and human serum.
In saliva, the Hsn-5 variants R12I/K17N and R12I/H21L and MUC7 D1
degraded at a lower rate than Hsn-5. In human serum, MUC7 D1 was also
more stable than Hsn-5; both peptides were more stable in serum than in
saliva. Third, we examined the cytotoxicity of these peptides using
human erythrocytes and two human cell lines (KB and HSG). No (or very
low) hemolytic activity was observed with any of the four peptides,
even at the highest protein concentration tested (200 µM), while
amphotericin B caused 100% hemolysis at only 12.5 µM. The toxic
effects of Hsn-5 and MUC7 D1 toward KB and HSG cells were also much
lower than that of amphotericin B as measured by trypan blue exclusion. Together, these findings indicate that the investigated peptides possess high antifungal therapeutic potential, in particular for the
treatment of drug-resistant fungal strains associated with immunocompromised (particularly human immunodeficiency virus-infected) patients. The same peptides could also be used as components of artificial saliva for patients with salivary dysfunction.
0066-4804/00/$04.00+0
Copyright © 2000, American Society for Microbiology. All rights reserved.
In Vitro Assessment of Antifungal Therapeutic
Potential of Salivary Histatin-5, Two Variants of Histatin-5,
and Salivary Mucin (MUC7) Domain 1
*
Corresponding author. Mailing address: Department of
Oral Biology, State University of New York at Buffalo, 109 Foster Hall, 3435 Main St., Buffalo, NY 14214-3092. Phone: (716) 829-2465. Fax:
(716) 829-3942. E-mail:
libuse_bobek{at}sdm.buffalo.edu.
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