REDUCED SKIN BARRIER FUNCTION PARALLELS ABNORMAL STRATUM-CORNEUM LIPID ORGANIZATION IN PATIENTS WITH LAMELLAR ICHTHYOSIS

Most patients with autosomal recessive lamellar ichthyosis are known t o have markedly impaired skin barrier function. We hypothesize that th is may be due to imperfections in the composition and fine structure o f the intercellular stratum corneum lipids. The aim of the present stu dy was to test this hypothesis. To characterize the barrier properties in three female patients with lamellar ichthyosis, the following para meters were used and compared with those of healthy volunteers: transe pidermal water loss, stratum corneum lipid profiles after topical acet one/ether extraction on the flexure side of the forearm, and small-ang le x-ray diffraction. The extracted lipids were separated using high p erformance thin-layer chromatography and quantified, and the ceramide profile was determined. Small-angle x-ray diffraction was used to obta in information on the molecular structure and organization of the inte rcellular lipid domains of stratum corneum using stratum corneum scale s collected by scraping. Transepidermal water loss was significantly i ncreased in all three patients, Lipid analysis showed significant diff erences in the relative amounts of ceramide fractions 2-3a-3b-4-5, fre e fatty acid-ceramide ratio, and free fatty acid-cholesterol ratio. Sm all-angle x-ray diffraction showed smaller repeated distances of lipid bilayers in stratum corneum samples of the patients compared with the healthy volunteers. An additional diffraction peak was found in the p atients compared with the healthy volunteers, which can be ascribed to crystalline cholesterol. These data suggest that there might be a rel ation between the impaired barrier function and stratum corneum lipid structural and composition changes.