Persistence of both peripheral and non-peripheral corneodesmosomes in the upper stratum corneum of winter xerosis skin versus only peripheral in normal skin

To understand the biochemical abnormalities that underlie the reduced desqu amation observed in dry skin, we analyzed corneodesmosome degradation in no rmal and winter xerosis skin, Western blotting of total proteins from corne ocytes obtained by varnish-strippings from the legs of 56 volunteers with n ormal (26) or xerotic (30) skin was performed using antibodies specific for (corneo)desmosome proteins. In the whole population, the amounts of desmog lein 1 and plakoglobin were found to be correlated, but were not related to the amounts of corneodesmosin. This suggests simultaneous proteolysis for the former proteins differing from that of corneodesmosin. Neither entire d esmoplakins nor any proteolysis-derived fragments were detected. The amount s of corneodesmosin, desmoglein 1, and plakoglobin detected were found to b e significantly higher in xerotic compared with normal skin extracts. Conve ntional and freeze-fracture electron microscopy showed the absence of nonpe ripheral corneodesmosomes in the upper stratum corneum of normal skin but t he presence of a significant number of these structures in the same layer o f winter xerosis skin. These results provide a more precise description of the proteolysis of corneodesmosome components in the upper cornified layer of the epidermis. They support previous studies demonstrating the importanc e of corneodesmosome degradation in desquamation and reveal that the nonper ipheral corneodesmosomes, which are totally degraded during maturation of t he stratum corneum in normal skin, persist in winter xerosis, probably lead ing to abnormal desquamation.