CERAMIDE COMPOSITION OF THE PSORIATIC SCALE

This paper investigates the ceramide composition of the psoriatic scal e compared with that of normal human SC. A method was optimalized, bas ed on TLC separation followed by densitometry, allowing the provision of good resolution and quantification of ceramide fractions from both normal and pathological specimens. Seven ceramide fractions were isola ted and submitted to compositional analysis. The obtained results sugg ested a revisitation of previous ceramide designation. Therefore a sim ple classification is suggested, based on grouping ceramides carrying structural similarities under common codes. According to these rules, ceramides were grouped into five classes designated as: (1) Cer[EOS], which contains ester-linked fatty acids, omega-OH fatty acids and sphi ngosines; (2) Cer[NS], which contains non-OH fatty acids and sphingosi nes; (3) Cer[NP], which contains non-OH fatty acids and phytosphingosi nes; (4) Cer[AS], which contains alpha-OH fatty acids and sphingosines ; (5) Cer[AP], which contains alpha-OH fatty acids and phytosphingosin es. Analysis of ceramides from the psoriatic scale, compared to those from normal human SC, resulted in an impairment of the Cer[EOS] conten t as well as of the ceramides containing phytosphingosine, with concur rent increase in ceramides containing sphingosine, being the total amo unt maintained identical. Since one of the suggested pathways for phyt osphingosine biosynthesis involves the water addition to the correspon ding sphingosine double bond, we can speculate that the observed alter ation is due to a deranged water bioavailability, associated with psor iasis.