Expression of Transforming Growth Factor-β1 in Mouse Skin During the Acute Phase of Radiation Damage

Abstract

Transforming growth factor-β (TGF β1) plays a central role in wound healing, so its perturbation by radiation may contribute to the acute and late effects seen in irradiated skin. TGFβ1 mRNA expression was measured by PCR, in the skin of the CD1 and CBA mouse, exposed to Sr-90 β from an 11-mm diameter source. TGFβ1 mRNA expression increased sharply after doses between 1 and 10 Gy and plateaued at ∼ 200% above controls after doses between 20 and 50 Gy. Immunohistochemistry showed that the TGFβ1 protein was confined to the dermis and suprabasal cells with none in basal cells. A dose of 50 Gy produces an acute desquamative reaction in 100% of mice that is resolved in 30 days. After the same dose, TGFβ1 mRNA expression fell below the controls at 3 h (− 9·4% in the CD1 and − 44% in the CBA mouse); rose sharply at 6–12 h (+ 124% CD1, + 230% CBA), returned to control levels by 24–48 h, then rose progressively to ∼ 200% above the controls between days 7 and 14. TGFβ1 mRNA expression remained elevated at 100–200% above controls until the end of the experiment at 55 days. The significance of these changes in TGFβ1 is discussed in the context of the early stress response reaction to radiation, the acute inflammatory and the later chronic fibrosis of the skin.