Y. Tsuji, T. Soma, L. Raftery, and T. Hibino – Shiseido Life Science Research Center, Yokohama and MGH/Harvard Cutaneous Biology Research Center, Charlestown, MA, USA
Hair loss is the result of premature entry into catagen by various causes. In male pattern baldness, we have hypothesized the involvement of ?catagen cascade’, in which a TGF-ß family member promotes caspase activation, resulting in the apoptosis of epithelial cells.
In the previous study, we showed that TGF-2 was localized at the boundary area between germinative cells and DPC during the transition phase from late anagen to catagen.
In the epithelial strand TGF-ß 2 was detected in the regressing hair follicle.
TUNEL-positive apoptotic cells and active caspase’3 and ?9 were also observed in the area.
In this study, we examined the role of TGF-ß 2 in relation to apoptosis.
Human hair follicles were cultured in the presence of TGF-ß 2.
Using active caspase-9 and ?3 specific antibodies, we found that TGF-ß 2 enhances the activation of these caspases in two regions, including the lower part of germinative matrix cells and outer most layer of outer root sheath cells.
Dual staining for active caspase-9 and TUNEL demonstrated that active caspase-9 and TUNEL-staining mostly co-localized.
Active caspase-3 positive cells were detected in the same region.
We evaluated 400 plant extracts for activity in a TGF- b suppression assay.
An extract from Hydrangea macrophylla strongly inhibited TGF-ß induction in this assay and also promoted hair elongation in a hair follicle organ culture system. We tested the effect of the extract in vivo by applying it onto C57BL6 mouse for 10 days and scored the catagen stage of each hair follicle morphologically.
Topical application of the extract remarkably delayed the progression of catagen.
We isolated an active substance from the extract using a TGF-ß suppression assay.
This substance showed a strong potential for hair elongation and also reduced caspase activation in cultured follicles.
Collectively our results suggest that TGF-ß 2 can enhance the induction of catagen via activation of caspases and that the suppressor of TGF-ß could be effective for the prevention of male pattern baldness.
We are presently investigating the role of TGF-ß family members and their signal pathways in the endogenous mouse hair cycle.