DIFFERENTIAL MODULATION OF TRANSFORMING GROWTH FACTOR-BETA-1 EXPRESSION AND MUCIN DEPOSITION BY RETINOIC ACID AND SODIUM LAURYL SULFATE IN HUMAN SKIN

Immunohistochemical staining of skin sections with two polyclonal antibodies (anti-CC 1-30 and anti-LC 1-30), specific for transforming growth factor-beta-1, revealed increased extracellular and decreased intracellular expression of transforming growth factor-beta-1 in retinoic acid-treated, compared to vehicle-treated, skin. Transforming growth factor-beta-1 staining, with both antibodies, was most marked in the upper layers of the epidermis, although dermal staining was also evident. The modulation of transforming growth factor-beta-1 expression by retinoic acid occurred in the absence of any change in its mRNA level. Transforming growth factor-beta-1 protein, as detected by rabbit polyclonal antibody (anti-LC 50-75) and mRNA, were only minimally detected in either retinoic acid- or vehicle-treated skin. Similar changes in TGF-beta-1 and TGF-beta-2 immunoreactivity and mRNA levels, as observed in retinoic acid-treated skin, were observed in skin following topical application of the irritant sodium lauryl sulfate, indicating that the alterations induced by retinoic acid were not specific. In contrast, mucin deposition, which is induced by transforming growth factor-beta, was elevated in retinoic acid-treated but not sodium lauryl sulfate-treated skin. Cultured adult human keratinocytes also expressed predominantly transforming growth factor-beta-1 protein, as measured by ELISA, and mRNA. Treatment of keratinocytes with retinoic acid resulted in a 50% induction of transforming growth factor-beta-1 protein, without any detectable change in transforming growth factor-beta-2. These data demonstrate disassociation of modulation of transforming growth factor-beta-1 expression and mucin deposition by retinoic acid and sodium lauryl sulfate in human skin in vivo. Whereas alterations in transforming growth factor-beta-1 expression were observed in both retinoic acid - and sodium lauryl sulfate-treated skin, accumulation of mucin was specific to retinoic acid-treated skin.