The analysis of the expression of TGF-β in human hair follicles in vivo

Abstract

Background: Although it is well known that transforming growth factor beta (TGF-β) may induce catagen change of hair follicles and inhibit hair growth, it is still unclear which subtype of TGF-β and its specified receptor might be expressed in human hair follicles of androgenetic alopecia (AGA) patients. Objective: To delineate precise expression of TGF-β subtype in human hair follicles of androgenetic alopecia patients. Methods: Immunohistochemical studies were performed on paraffin sections of human hair follicles by applying type 1, 2, and 3 TGF-β antibodies and type I and II receptor antibodies. We ascertained the expression of TGF-β subtype in hair follicles of androgenetic alopecia patients. We also compared the expression pattern of each type of TGF-β receptor. We evaluated the change of TGF-β expression of hair follicles in the catagen phase. Results: TGF-β1 was well-expressed in the outer area of the inner root sheath (IRS) or dermal connective sheath area. TGF-β2 was commonly expressed in the inner 1/2 of the outer root sheath (ORS). TGF-β3 was expressed in the hair cortex, IRS, and cuticle in normal hair follicles obtained from both the vertex and occipital area. On the contrary, in specimens from AGA, the enhanced expression of type 2 TGF-β or type II receptor was observed in the vertex area (bald) compared to the occipital area (non bald). When the expression patterns of TGF-β 1, 2, and 3 were compared between anagen and catagen phases, TGF-β2 and 3 were positively expressed in the epithelial strands and secondary hair germs in the catagen phase. The immunoreactivities of TGF-β 1 and 2 were intensified in the ORS areas of the catagen phase. Conclusion: The expression of type 1, 2 TGF-β and type I and II receptors in follicular epithelial cells might be related to catagen induction and development of androgenetic alopecia of human hair in vivo.