The oral mucosal surface represents an interface with the external environment, and as such, is a first line of defense against microbial colonization and infection. Lipids at the mucosal surface and in saliva are thought to underlie at least part of an antimicrobial barrier. Some of these lipids are synthesized in the epithelium and are carried to the surface as cells differentiate, while others are secreted onto the surface from sebaceous glands. Published reports and preliminary data indicate that free sphingoid bases have broad antimicrobial activity, and our previous studies demonstrate the presence of these bases at the mucosal surface and in saliva. In addition, our preliminary results demonstrate potent antibacterial activity associated with a specific fatty acid (C16:1_6) derived from sebaceous triglycerides. C16:1_6 has been shown to act synergistically with low concentrations of ethanol and is capable of killing an isolate of Staphylococcus aureus that is resistant to both methicillin and mupirocin. The proposed studies are designed to better develop our understanding and ability to exploit these natural antimicrobials through pursuit of four Specific Aims: 1. To determine the variability in the quantity and composition of lipids in the oral cavity in a human population. 2. To delineate antimicrobial activity of C16:1_6 and free long-chain bases (sphingosine, dihydrosphingosine, phytosphingosine and 6-hydroxysphingosine) against selected strains of the periodontal pathogens Porphyromonas gingivalis and Actinobacillus actinomycetemcomitans. 3. To document the bactericidal effects of C16:1_6, sphingosine, dihydrosphingosine and 6-hydroxysphingosine, in combination with antimicrobial peptides or permeabilizing agents such as ethanol, against the test microorganisms. 4. To identify mechanisms by which the antimicrobial lipids act. Effects of the antimicrobial lipids on overall appearance and biochemistry of test bacteria in culture will be determined, and the interaction of these lipids with model membranes will be studied. The proposed studies could lead to a significant set of tools for combating bacterial infections, including periodontal disease, and could provide new tools to use against increasingly antibiotic-resistant bacteria.This project will test the hypothesis that certain lipids present at the oral mucosal surfaces and in saliva are antimicrobials effective against periodontal pathogens. To test this hypothesis a series of studies will be conducted to document variation in the concentrations of lipid and their activity mechanisms of action against selected bacteria when used alone or in combination with other antimicrobials.

Agency
National Institute of Health (NIH)
Institute
National Institute of Dental & Craniofacial Research (NIDCR)
Type
Research Project (R01)
Project #
5R01DE018032-02
Application #
7670503
Study Section
Oral, Dental and Craniofacial Sciences Study Section (ODCS)
Program Officer
Lunsford, Dwayne
Project Start
2008-09-01
Project End
2011-08-31
Budget Start
2009-09-01
Budget End
2010-08-31
Support Year
2
Fiscal Year
2009
Total Cost
$262,500
Indirect Cost
Name
University of Iowa
Department
Dentistry
Type
Schools of Dentistry
DUNS #
062761671
City
Iowa City
State
IA
Country
United States
Zip Code
52242
Fischer, Carol L; Dawson, Deborah V; Blanchette, Derek R et al. (2016) Protein Analysis of Sapienic Acid-Treated Porphyromonas gingivalis Suggests Differential Regulation of Multiple Metabolic Pathways. J Bacteriol 198:157-67
Poulsen, Christopher; Mehalick, Leslie A; Fischer, Carol L et al. (2015) Differential cytotoxicity of long-chain bases for human oral gingival epithelial keratinocytes, oral fibroblasts, and dendritic cells. Toxicol Lett 237:21-9
Fischer, Carol L; Blanchette, Derek R; Brogden, Kim A et al. (2014) The roles of cutaneous lipids in host defense. Biochim Biophys Acta 1841:319-22
Dawson, D V; Drake, D R; Hill, J R et al. (2013) Organization, barrier function and antimicrobial lipids of the oral mucosa. Int J Cosmet Sci 35:220-3
Fischer, Carol L; Walters, Katherine S; Drake, David R et al. (2013) Oral mucosal lipids are antibacterial against Porphyromonas gingivalis, induce ultrastructural damage, and alter bacterial lipid and protein compositions. Int J Oral Sci 5:130-40
Fischer, C L; Walters, K S; Drake, D R et al. (2013) Sphingoid bases are taken up by Escherichia coli and Staphylococcus aureus and induce ultrastructural damage. Skin Pharmacol Physiol 26:36-44
Brogden, N K; Mehalick, L; Fischer, C L et al. (2012) The emerging role of peptides and lipids as antimicrobial epidermal barriers and modulators of local inflammation. Skin Pharmacol Physiol 25:167-81
Fischer, Carol L; Drake, David R; Dawson, Deborah V et al. (2012) Antibacterial activity of sphingoid bases and fatty acids against Gram-positive and Gram-negative bacteria. Antimicrob Agents Chemother 56:1157-61
Brasser, Andrew J; Barwacz, Christopher A; Dawson, Deborah V et al. (2011) Presence of wax esters and squalene in human saliva. Arch Oral Biol 56:588-91
Wertz, P W (2009) Essential fatty acids and dietary stress. Toxicol Ind Health 25:279-83