Abstract
Transforming growth factor beta (TGF-beta) is a family of potent growth inhibitor proteins, often produced as a precursor and often secreted in a complex with the latent TGF-beta binding protein (LTBP). We investigated the expression of TGF-beta 1, -beta 2, -beta 3, LTBP, TGF-beta receptor proteins type I and type II (T beta R-I and -II) during induced hair growth in C57 BL-6 mice. We here demonstrated that TGF betas and T beta R-I are expressed in hair follicle epithelium and have found a positive reactivity for LTBP and T beta R-I in ++sebocytes. Dermal tissue was weakly stained for LTBP and TGF-beta 3. In early anagen the inner hair root sheath epithelium expressed TGF-beta 1, whereas outer hair root was positive for T beta R-I during anagen/catagen switch. T beta R-II was found in sebaceous glands without significant variations during the hair cycle. We may conclude that in follicle epithelium TGF-beta 1 is not produced in a complex together with LTBP. On the other hand, it is possible that other types of LTBP, like LTBP-2 and LTBP-3, are present, which are not detected by the antibody we used. Furthermore, a very rapid secretion of LTBP from producing cells may prevent immunohistochemical detection. TGF-beta 1 released by inner hair root sheath may regulate outer root sheath growth. A bidirectional interaction of sebocytes and hair follicle epithelium in the TGF-beta/LTBP seems possible. Sebocytes can be considered to be a target for TGFs since they express both T beta R++-I and -II. The general properties of TGF-beta as a growth inhibitor of epithelial cells may suggest a possible involvement in either the abrogation of extensive growth at the end of anagen or the initiation of catagen for the follicle epithelium as well as growth control for sebaceous glands.
