Deficient production of hexadecenoic acid in the skin is associated in part with the vulnerability of atopic dermatitis patients to colonization by Staphylococcus aureus.
OBJECTIVE
As one of the major skin fatty acids, cis-6-hexadecenoic acid (C16:1Delta6) exhibits a specific antibacterial activity and might play a specific role in the defense mechanism against Staphylococcus aureus, in healthy subjects whereas S. aureus frequently colonizes the skin of patients with atopic dermatitis (AD).


METHODS
Fatty acid composition of sebum at the recovery level was analyzed by gas chromatography and S. aureus colonizing the skin was assessed by the 'cup-scrub' method (9 patients and 10 healthy controls). To evaluate in vivo effect of C16:1Delta6 on colonization, C16:1Delta6 was applied for 2 weeks on the upper arm skin of another group of AD patients (11 patients).


RESULTS
Analysis of sebum lipids revealed that there is a significant lower free C16:1Delta6 content in nonlesional skin from AD patients compared with healthy controls. This lower content is also accompanied by a significantly lower level of C16:1Delta6 in the total fatty acid composition of sebum (analyzed following hydrolysis). The lower level of free C16:1Delta6 correlated significantly (R(2) = 0.41, p < 0.01) with the numbers of S. aureus colonizing nonlesional skin. Topical application of free C16:1Delta6 on the skin of AD patients for 2 weeks abolished the markedly increased bacterial count in 6 out of the 8 AD patients tested.


CONCLUSIONS
Free C16:1Delta6 may be involved in the defense mechanism against S. aureus in healthy skin and this deficit triggers the susceptibility of the skin to colonization by S. aureus in AD.
Takigawa
Hirofumi
H
Biological Science Laboratories, Kao Corporation, Tochigi, Japan.
Nakagawa
Hidemi
H
Kuzukawa
Michiya
M
Mori
Hajime
H
Imokawa
Genji
G
D000328:Adult; D000900:Anti-Bacterial Agents / Q000378:metabolism* / Q000494:pharmacology; D003876:Dermatitis, Atopic / Q000150:complications / Q000188:drug therapy / Q000378:metabolism*; D004198:Disease Susceptibility; D005260:Female; D006801:Humans; D008297:Male; D010169:Palmitic Acids / Q000378:metabolism* / Q000494:pharmacology; D012629:Sebum / Q000378:metabolism; D012867:Skin / Q000378:metabolism / Q000503:physiopathology; D013203:Staphylococcal Infections / Q000150:complications*; D013211:Staphylococcus aureus / Q000187:drug effects*
D000900:Anti-Bacterial Agents; D010169:Palmitic Acids; C093821:hexadecenoic acid