Minoxidil Downregulates Interleukin-1 Alpha Gene Expression in HaCaT Cells

Minoxidil has been used topically to stimulate hair growth for male androgenetic alopecia (AGA) for more than 3 decades. It is currently being used for female AGA and alopecia areata (AA) as well. Although much time has passed since its first use, our understanding of its mechanism of action is highly limited. Therefore, we examined the inflammatory properties of AGA and AA, two entities in which minoxidil is being used as a therapeutic agent. We investigated the in vitro expression levels of cytokine interleukin-1 alpha (IL-1α), a potent inhibitor of hair growth, in minoxidil-treated human keratinocyte (HaCaT) cells to determine whether this molecule exerts anti-inflammatory effects.

Cellular proliferation was examined using the Cell Proliferation Kit II (XTT) reagent. After determining a noncytotoxic concentration, HaCaT cells were treated with minoxidil. RNA was isolated from both untreated and treated cells with TRI Reagent^®. Expression of the IL-1α gene was determined by reverse transcription quantitative polymerase chain reaction analysis and is reported relative to glyceraldehyde-3-phosphate dehydrogenase (GAPDH), which served as a control.

Results are presented as IL-1α/GAPDH fold change. Minoxidil treatment downregulated IL-1α expression by 0.3433-fold compared with untreated cells (P = 0.001).

This anti-inflammatory effect of minoxidil, as evidenced by significant downregulation of IL-1α gene expression in HaCaT cells, may represent one of its mechanisms of action in alopecia.