I. Hagemann et E. Proksch, TOPICAL TREATMENT BY UREA REDUCES EPIDERMAL HYPERPROLIFERATION AND INDUCES DIFFERENTIATION IN PSORIASIS, Acta dermato-venereologica, 76(5), 1996, pp. 353-356
The mechanisms of action of urea-containing ointments in the treatment
of eczema, ichthyosis and psoriasis are only partly known and related
to proteolysis and keratinolysis, In this study, we have examined the
effects of topical urea on epidermal proliferation and differentiatio
n in 10 patients with psoriasis, Plaque type lesions were treated for
2 weeks with an ointment containing 10% urea with the vehicle alone, o
r left untreated, Clinical score, hydration of the stratum corneum, tr
ansepidermal water loss (TEWL), and immunohistochemical studies were p
erformed, Epidermal proliferation was assessed using the Ki-S3 prolife
ration-associated nuclear antigen. For epidermal differentiation antib
odies against involucrin and against keratins CK 5, 6, 17 and CK 1, 5,
10, 14 were used. The patients showed a reduction of the clinical sco
re (>50%), a 2-fold increase in stratum corneum hydration (p<0.01), an
d a small decrease in TEWL (N.S.) on the urea- treated compared to the
untreated site, Light microscopy studies revealed a 29% reduction in
epidermal thickness (p<0.01); epidermal proliferation was decreased by
51% (p<0.005), The altered expression of involucrin and of cytokerati
ns (reduction of CK 5, 1 and 10 and induction of CK 6 and 17) was part
ially reversed, The ointment base also improved psoriasis, but urea wa
s significantly better than the vehicle (urea: 40% reduction in epider
mal proliferation vs, vehicle), In summary, these studies show that ur
ea influences epidermal proliferation and differentiation in psoriasis
.