Article on Free Fatt Acids/Lipids and AD
This looks interesting as well but it is pretty technical but it states that
a a deficiency in D 6 desaturase activity leads to pathogenesis of atopic
dermatitis–can anyone interpret this? Is it possible to increase the
activity of D 6 desaturase?
Biosynthesis of fatty acids in the skin and their role in epidermal barrier
funtion
By E. Proksch
Summary
Fatty acids and their derivatives are important cellular structural
components for mammalian cells: in the skin extracellular fatty acids are
also part of the intercellular stratum corneum lipid bilayers which regulate
cutaneous permeability barrier. The epidermal keratimocyte, the main cell
type in the epidermis, is highly active in the synthesis of several lipids
including free fatty acids. Skin contains free fatty acids as well as fatty
acids bound in triglycerides, phospholipids, glycosylceramides, and
ceramides (sphingolipids). The chain length of free fatty acids in the
epidermis ranges from C12 to C24. Fatty acids are synthesized by successive
condensation of two-carbon units starting with acetyl-CoA carboxylase. The
rate-limiting enzymes are acetyl-CoA carboxylase and fatty acid synthase.
Mammalian cells contain several distinct desaturase enzymes that insert
double bonds at specific position in fatty acid molecules. Virtually all
cells exhibit D 9 desaturase activity. A deficiency in D 6 desaturase
activity has been postulated to be important for the pathogenesis of atopic
dermatitis. Unsaturated fatty acids are converted by elongases to result in
arachidonate which is a substrate for cyclooxygenase and lipoxygenase
enzymes that produce eicosanoid, a diverse family of biologically potent
compounds. The skin is quantitatively an important site of de novo lipid
synthesis and regulated by permeability barrier function. After artificial
permeability barrier function an increase in epidermal lipid synthesis
including free fatty acid synthesis and an increase in the rate-limiting
enzymes fatty acid synthase and acetyl-CoA carboxylase has been described.
The signals for the increased lipid synthesis are only known in part and
related to calcium ion concentrations, cytokines and growth factors.
Keywords
fatty acid, sphingolipid, ceramide, skin permeability barrier, essential
fatty acid deficiency, epidermal lipid synthesis, linoleic acid,
gamma-linolenic acid
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