Many hair loss disorders, including non-scaring alopecia, are caused by the arrest of hair follicles at the telogen phase, and the failure to enter the growth phase. Several studies report the efficacy of tofacitinib in promoting hair growth, by mechanisms not precisely known. The aim of this study was to identify other mechanisms by which tofacitinib, applied topically, promotes hair growth. The results showed that histopathological studies in mice treated topically with tofacitinib increased number of hair follicles, ratio of hair follicles in anagen phase, and length of hair infundibulum, and a reduced interfollicular epidermal thickness, compared to DMSO-treated mice. RT-PCR experiments showed significant increases in the expression of noggin (P < 0.05) and BMP4 (P < 0.05) mRNAs, which were greater than those in the vehicle-controlled group. Moreover, the expression of noggin and BMP4 mRNAs was significantly higher in the tofacitinib-treated group than in the minoxidil-treated group. This study would help understand the efficacy and mechanism by which tofacitinib, applied topically, triggers noggin and BMP4 mRNA expression, both being important molecules involved in the onset of the growth phase of hair growth cycles.
Keywords: BMP4; Hair growth; Noggin; Tofacitinib.