- Epidermal host
defense mechanisms: protease inhibitors and antimicrobial proteins
We identified several epidermal protease inhibitors (SKALP/elafin,
SLPI, cystatin M/E) that are involved in cutaneous host defense or
regulation of skin barrier function. These small proteins are produced
in large quantities in the differentiation programs associated with
disturbance of epidermal homeostasis. In skin diseases such as
psoriasis and atopic dermatitis, the regulation of keratinocyte
differentiation and proliferation is disturbed. Identification of the
regulatory steps in the activation of keratinocytes would allow
development of rational therapeutic agents in major skin diseases such
as psoriasis and chronic dermatitis. While studying these processes,
we have developed and extensively characterized culture models for
normal and activated epidermal keratinocytes. These models are
currently used to develop high throughput systems for pharmacological
and toxicological screening.
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Epidermal cell kinetics
Psoriasis research has been a major point of interest of our
department, focusing on the mechanisms involved in disturbance of
epidermal proliferation and differentiation. The effect of
conventional anti-psoriatic drugs and new experimental drugs on
clinical and cell biological parameters has been extensively studied.
Both in cell culture and in the skin of human volunteers we have
studied growth and cell cycle kinetics of epidermal keratinocytes
following exposure to trauma or inflammatory stimuli. We have
developed in vitro models to study recruitment of cells from
G0, and induction of quiescence or differentiation both for murine and
human keratinocytes. Currently we are investigating the stem cell and
transiently amplifying cell population, using flow cytometric
analysis.
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Novel methods for monitoring gene expression
Serial analysis of gene expression (SAGE) and gene-chip
technology are used to monitor the changes in gene expression patterns
in cultured keratinocytes and in biopsies of human skin, following
external stimuli and during disease. These powerful technologies can
be used to study effects of cellular stimuli or the effects of drugs
on cellular behaviour. SAGE libraries of cultured keratinocytes have
been prepared and analyzed. These data are available at the NCBI web
site. We are currently analyzing keratinocyte gene expression profiles
(cultured cells and skin biopsies) using a 19.000 60-mer oligo array.
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Dermal extracellular matrix proteins
We have recently elucidated a genetic cause
of a new type of Ehlers-Danlos syndrome (EDS) and hypermobility type
EDS. Both are caused by deficiencies for the matrix protein tenascin-X.
We are currently investigating the role of tenascin-X in assembly and
stability of collagen and elastic fibers in skin and joints.
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Tissue engineering
Three-dimensional, air-exposed culture models for
dermal fibroblasts and epidermal keratinocytes are used to study cell
biology of the skin in vitro. In addition, these constructs can be
used for drug screening and ultimately for reconstructive purposes
(burns, ulcers, large surgical defects).
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