Cell surface glycans in the human stratum corneum: distribution and depth‐related changes

Abstract

During the formation of the stratum corneum (SC) barrier, the extracellular spaces of viable epidermis, rich in glycans, are filled with a highly organized lipid matrix and the plasma membranes of keratinocytes are replaced by cornified lipid envelopes. These structures comprise cross‐linked proteins, including transmembrane glycoproteins and proteoglycans, covalently bound to a monolayer of cell surface ceramides. Little is known about the presence and distribution of glycans on the SC corneocytes despite their possible involvement in SC hydration, cohesion and desquamation. In this work, we visualized ultrastructurally and quantified the distribution of glycans on the surface of native and delipidated corneocytes. The cells were harvested at different depths of the SC, allowing us to define the relationship between the distribution of various glycans, proteoglycans and glycoproteins, and other changes occurring in SC. At the cell periphery, we found a correlation between the depth‐related alterations of corneodesmosome glycoproteins and α‐d‐mannosyl and N‐acetyl‐d‐glucosamine‐labelling patterns. Elimination of the terminal sugars, α‐linked fucose and α‐(2,3) linked sialic acid, was less abrupt, but also the initial extent of their peripheral distribution was overall lower than that of concanavalin A and wheat germ agglutinin lectin‐detected glycans. Diffuse labelling of heparan sulphate glycosaminoglycans disappeared completely from the outermost corneocytes, whereas that of several simple carbohydrates could be detected at all SC levels. Our results suggest that specific glycan distribution may participate in the progressive changes of SC, as it evolves from the SC compactum to the SC disjunctum, towards desquamation.

Crocin, a natural molecule with potentially beneficial effects against skin ageing

“…Considering that (i) profound changes in the synthesis and degradation of skin glycosaminoglycans and related proteoglycans occur during ageing , (ii) glycans must be considered as key actors of skin biology and (iii) crocin is a di‐gentiobiosyl derivative of crocetin, the possible role of crocin in skin glycobiology was further investigated.…”

Assessing the skin barrier via corneocyte morphometry

“…As they appear on the basolateral side, the layer‐to‐layer coherence is involved—consequently affecting the desquamation . Other important molecule classes may contribute to local organization of the fine structure, like surface glycans, which have been found associated to corneodesmosomes and disappear upon corneocyte maturation …”

Molecular basis of the skin barrier structures revealed by electron microscopy

“…It is transported via LGs and associated with corneodesmosomes together with its inhibitor cystatin M/E . As another regulator of corneodesmosome degradation, cell surface glycans have been proposed as well …”