Modification of late epidermal differentiation in photoaged skin treated with topical retinoic acid cream.
BACKGROUND
Retinoic acid (RA) cream treatment alters epidermal proliferation and differentiation in photoaged skin.


OBJECTIVE
To study the changes in the expression of markers of epidermal differentiation in photoaged skin following RA cream treatment.


METHODS
Ten subjects with photoaged skin were examined before treatment and at regular intervals during 12 months of once daily application of 0.05% tretinoin cream over the left forearm. Paraffin-embedded biopsy sections from the forearm were stained with loricrin, filaggrin, involucrin and cornifin antisera in addition to hematoxylin and eosin. The various layers were measured using a calibrated optical micrometer.


RESULTS
The thickness of the epidermis increased rapidly, reaching a substantial increase after 1 month of retinoid cream application and retaining it during the following 12 months. The stratum granulosum achieved a transient but substantial increase after 1 and 3 months. Except involucrin, the ratio between the layers expressing the various markers of epidermal differentiation and the epidermis significantly increased following tretinoin cream treatment.


CONCLUSIONS
RA cream treatment not only increases the thickness of the epidermis but also the programming of late terminal epidermal differentiation, as expressed by the markers studied. Thus, RA appears to affect both proliferation and differentiation of keratinocytes in vivo.
Tur
E
E
Department of Dermatology, Tel Aviv Sourasky Medical Center, Tel Aviv University, Israel.
Hohl
D
D
Jetten
A
A
Panizzon
R
R
Frenk
E
E
D000287:Administration, Topical; D000368:Aged; D000369:Aged, 80 and over; D002454:Cell Differentiation / Q000187:drug effects; D055233:Cornified Envelope Proline-Rich Proteins; D004817:Epidermis / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D000091344:Filaggrin Proteins; D006801:Humans; D007150:Immunohistochemistry; D007381:Intermediate Filament Proteins / Q000378:metabolism; D007641:Keratolytic Agents / Q000008:administration & dosage / Q000494:pharmacology*; D008565:Membrane Proteins / Q000378:metabolism; D011498:Protein Precursors / Q000378:metabolism; D015595:Skin Aging / Q000187:drug effects* / Q000473:pathology; D014212:Tretinoin / Q000008:administration & dosage / Q000494:pharmacology*
D055233:Cornified Envelope Proline-Rich Proteins; C000717249:FLG protein, human; D000091344:Filaggrin Proteins; D007381:Intermediate Filament Proteins; D007641:Keratolytic Agents; D008565:Membrane Proteins; D011498:Protein Precursors; C064554:loricrin; D014212:Tretinoin; C032253:involucrin