peptides (defensin-1 and -2) and monosaturated fatty
particularly skimmed milk, is the most common food
implicated in acne flares.
acids (palmitic, oleic and sapienic acids) that have a bactericidal potential against gram-positive microorganisms. Toll-like receptors are also responsible for the subsequent activation of adaptive immunity with inflammatory cell (macrophages and granulocytes) recruitment and consequent production of other molecules that potentiate acne lesion inflammation with
Milk, and induction of
rapture of follicular walls and tissue matrix
metalloproteinases that enhance scar formation. The presence of acetylcholine receptors on these cells can also explain the ability of nicotine to cause infundibular epithelial hyperplasia and follicular plugging, suggesting the possible aetiological role of smoking in acne. Androgens have a significant role in acne
pathogenesis. While hormonal serum levels do not correlate with disease severity, they may have a permissive role in the onset of the pathology. The most widely accepted hypothesis, however, is that local overproduction of androgens and high expression and activity of androgen receptors can determine acne lesions2
. The sebaceous glands are capable, thanks
to the specific enzyme 5α-reductase, of biosynthesising testosterone from circulating dehydroepiandrosterone (DHEA) or from cholesterol ingested with food. These hormones cause sebocyte proliferation, differentiation, lipogenesis and intrainfundibular hyperproliferation, and hyperkeratinisation, which lead to microcomedone formation. In a stressed environment, different inflammatory cytokines/chemokines, such as interleukin-alpha (IL-α), tumour necrosis factor-alpha (TNF-α), IL-6, IL-8, lymphotoxin beta-4 (LTB4) and recently, some P. acnes extracts have been reported to have a central role in comedogenesis. As previously detailed, not only is increased sebum production typical of acne patients, but a number of variations in lipid metabolism are also seen, with desaturation of sebaceous fatty acids and a decreased amount of linoleic acid. Acne sebum is accompanied by the presence of lipoperoxides (mainly from squalene peroxidation and
42 ❚
decreased levels of the antioxidant vitamin E), which are capable of inducing intrafundibular cell proliferations and the production of proinflammatory cytokines, as well as the activation of
July/August 2012 |
prime-journal.com
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