Homocysteine in androgenetic alopecia: A case control study and observational experiments on mice.

Objective: To investigate the relationship between homocysteine (HCY) and androgenetic alopecia (AGA).

Methods: A case control study and two observational experiments on mice were conducted. In the first part, a total of 528 Chinese AGA patients and 500 age-matched healthy controls were included. Serum HCY levels of AGA and controls were compared. In the second part, eight mice were divided into two groups. Both groups of mice had their hair removed. AGA group received a DHT injection, and the other as control group. HCY levels in hair follicles (HFs) were detected by ELISA and compared. In the third part, twelve mice were divided into three groups and fed with different concentrations of methionine. After 4 weeks, serum HCY levels, parameters related to hair growth through observation and HE staining, and expression of immunohistochemistry (IHC) hair-growth-related markers Ki67, VEGF, IGF-1, Krt27, FGF9, and TGF-β1 were compared among the three groups.

Results: In the first part, HCY levels were higher in AGA than the controls of both genders. However, there was no difference in HCY levels between groups with varying severity. Rates of hyperhomocysteinemia was higher in AGA patients than the controls. Logistic regression analysis showed serum HCY levels was positively correlated with the incidence of AGA. In the second part, HCY of the HFs in the AGA group was significantly higher than that in the control group. The third part showed that the increase in serum HCY levels inhibited the growth of mice hair, with the less expressed stimulative markers Ki67, VEGF, IGF-1, Krt27, and FGF9, while there was no difference in the expression of inhibitory markers TGF-β1.

Conclusion: There is a potential relationship between HCY and AGA. HCY had an inhibitory effect on hair growth. Further studies are necessary to explore the specific mechanism.