Local synthesis of steroid hormones in human hair roots

Abstract

Hair loss displays a common symptom with a multitude of different origins that complexes diagnostics and therapy. <br /> The basis of the current project was the hypothesis, that hair loss may be correlated or even caused by an impaired local steroid hormone metabolism in scalp hair roots. It is known that human hair growth is regulated by hormones, including steroid hormones (Schweikert and Wilson 1974). In this context it was determined, if the local conversion of the steroid estrone-3-sulfate (E1S) into its products estrone (E1) and 17&beta;-estradiol (E2) may be impaired in hair growth disorders (androgenetic alopecia (AGA) and diffuse alopecia (DA)). Indeed, the conversion of [6,7-³H(N)] E1S into E2 was significantly decreased in the DA group in metabolite experiments. By the use of the steroid sulfatase (STS)-specific inhibitor estrone sulfamate, it was furthermore possible to inhibit the conversion of [6,7-³H(N)] E1S into E1 and E2, thereby confirming that the conversion occurs locally in isolated hair roots. Moreover, 3’-mRNA sequencing data revealed, that expression of the enzyme HSD17B7, which is involved in the conversion of E1 into E2, is decreased in telogen hair. <br /> It was not possible to confirm the hypothesis, that the conversion of dehydroepiandrosterone (DHEA) into androstenediol may be impaired in hair growth disorders. <br /> Concerning the comparison of healthy and disordered hair growth, transcript expression analysis revealed, that there are no significant differences between the control, AGA or DA groups on the gene expression level in general. But an explorative analysis shows, that fibroblast growth factor 5 (FGF5) and ectodysplasin A (EDA), both being candidate genes in male pattern baldness (MPB), are significantly lower expressed in DA. This may indicate similarities of AGA and/ or DA to MPB. <br /> Interestingly, found as a coincidence, the data set also suggested, that expression of several mitochondrial genes may be decreased in samples from hair growth disorders, which may open up the possibility for new research in the field of hair growth disorders.