Induction of normal and psoriatic phenotypes in submerged keratinocyte cultures

Abstract

Lesional psoriatic epidermis displays a number of phenotypic changes that are distinct from the differentiation program found in normal interfollicular epidermis. In psoriatic epidermis, keratinocytes are hyperproliferative and several differentiation-associated molecules are expressed that are absent in normal skin (e.g., cytokeratins (CK) 6, 16, and 17, and the epidermal proteinase inhibitor SKALP/ elafin). In addition, several molecules which are normally restricted to the stratum granulosum are strongly upregulated in the stratum spinosum (e.g., psoriasis-associated fatty acid binding protein (PA-FABP), psoriasin, involucrin, and transglutaminase). The aim of this study was to develop in vitro culture systems which (a) would allow to study the induction of normal and psoriatic differentiation pathways, and (b) would be amenable for screening of antipsoriatic drugs. Here we have investigated several models for induction of differentiation with respect to the expression of markers for the normal and psoriatic phenotype. Cell cycle parameters and expression levels of CK1, CK10, CK16, SKALP/elafin, transglutaminase, involucrin, psoriasin, and PA-FABP were assessed in these models using flow cytometry, immunocytochemistry, and Northern blot analysis. We observed that induction of differentiation with fetal calf serum resembled the psoriatic phenotype (sustained hyperproliferation; high levels of CK16, SKALP/elafin, transglutaminase, and involucrin; moderate psoriasin expression), whereas differentiation induced by growth factor depletion in a confluent culture resembled the normal differentiation phenotype (low proliferative rate; high expression levels of CK1 and CK10; moderate expression of involucrin and transglutaminase; low expression levels of SKALP/elafin and CK16; absence of psoriasin). We propose that these models can be used to study expression and pharmacological modulation of selected differentiation genes and the coordinated expression of sets of genes associated with epidermal differentiation programs.

The changes in the expression levels of follicular markers in keratoacanthoma depend on the stage: keratoacanthoma is a follicular neoplasm exhibiting infundibular/isthmic differentiation without expression of CK15

“…CK16 and CK17 tended to be negative in the suprabasal cells of this part, confirming the infundibular differentiation. However, they were positive for the whole areas in some early or proliferative stage lesions, which may suggest either the hyperproliferative nature of this stage of lesions 46 or the beginning of the outer sheath differentiation in the invaginated part.…”

A Comprehensive Analysis of Pattern Recognition Receptors in Normal and Inflamed Human Epidermis: Upregulation of Dectin-1 in Psoriasis

“…AD, atopic dermatitis; NS, normal skin; PS, psoriasis. (van Ruissen et al, 1996;Zeeuwen et al, 2008). In differentiated keratinocyte cultures that show a normal skin phenotype, dectin-1 mRNA expression levels were low.…”

Identification of avarol derivatives as potential antipsoriatic drugs using an in vitro model for keratinocyte growth and differentiation

“…The evaluation of avarol and derivatives in keratinocyte differentiation models Using our keratinocyte differentiation culture models (van Ruissen et al, 1996;Pol et al, 2002), the effects of avarol and its 14 avarol derivatives (Fig. 1) on normal and psoriasis-like keratinocyte differentiation were evaluated.…”

“…Potential drugs for this skin disease can be identified by measuring their effects on normal and psoriasis-like differentiation of submerged confluent keratinocyte cultures. In a 96-well format, upregulation of CK10 expression is used as a marker for normal differentiation (van Ruissen et al, 1996), whereas the expression and secretion of SKALP/Elafin is used as a marker for stressed epidermal differentiation (Alkemade et al, 1995;van Ruissen et al, 1996). An interesting drug candidate should dose-dependently suppress SKALP/Elafin expression, show little to no cytotoxicity at the pharmacological concentration range of 0.1-10 μM and preferably should not affect normal epidermal differentiation as determined by CK10 expression.…”

“…To substantiate a potential therapeutic application in psoriasis, we evaluated avarol and 14 derivatives of avarol in submerged keratinocyte differentiation culture systems. By changing the culture conditions at the moment of confluence, epidermal differentiation is induced, mimicking the normal or psoriatic phenotype of human epidermis (van Ruissen et al, 1996(van Ruissen et al, , 1998Pol et al, 2002). The expression of cytokeratin 10 (CK10) and SKALP/Elafin were used as markers for normal and psoriatic keratinocyte differentiation, respectively.…”