TGF-Beta 1 appears to inhibit the rate of hair follicle lengthening in vitro and in vivo in mice to promote the regression phase of the organ culture of human hair follicles. Thus, TGF-Beta 1 is considered as a catagen induction marker in hair follicle. TGF-Beta 1 was shown to induce a rapid fibrotic response in vivo.
Moreover, chronic expression of TGF- Beta1 in adult dermal fibroblasts caused severe alopecia characterized by epidermal and follicular hyperproliferation, apoptosis, as well as dermal fibrosis and inflammation. Inui et al demonstrated that androgen induced TGF- Beta 1 from the balding dermal papilla cells plays an important role in miniaturization of hair shaft. Also, a key function for TGF-Beta 1 in wound healing and fibrosis to regulate the expression of proteins of the fibrillar collagens and fibronectin.
TGF-Beta 1 is considered a potent anabolic factor that enhances connective tissue deposition and repair and which sustained signaling likely leads to the development of tissue fibrosis. Therefore, it can be inferred that the Testosterone-induced TGF- Beta 1 expression may induce perifollicular fibrosis the dermal fibroblasts, accelerate hair follicles into moving on catagen phase of hair cycle, and inhibits epithelial growth, which brings all together out miniaturization of hair follicles in AGA.
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