Evaluation of apoptosis regulatory markers in androgenetic alopecia

Androgenetic alopecia (AGA) is a common androgen-induced progressive disorder; the pathways of which are regulated by local genetic codes and hormonal control. Meanwhile, it is unclear whether an altered proliferation or increased apoptosis could contribute to its pathogenesis.

To evaluate the role of some apoptosis regulatory markers and follicular proliferation in the pathogenesis of AGA.

Thirty biopsies were taken from the frontal (bald) area and occipital (hair-bearing) area of 15 male patients with AGA, as well as five specimens from the frontal area of five age-matched controls. The biopsies were stained with apoptosis regulatory markers (Bcl-2, p53, Bax & Fas) and PCNA (proliferating cell nuclear antigen), as well as TUNEL (terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end-labeling) staining for the detection of DNA fragmentation in apoptotic cells.

Bcl-2 expression was localized to epidermal basal layer and follicular dermal papilla with highly significant correlation with PCNA expression (P < 0.001). Perifollicular lymphocytic infiltrate of the bald area showed significant expression of Bcl-2. However, pro-apoptotic Bax and Fas were expressed in the epidermis and not in the hair follicles which does not show any apoptotic keratinocytes by TUNEL staining.

The low proliferation rate in the bald area of patients, together with persistent perifollicular inflammatory infiltrate as evidenced by the anti-apoptotic Bcl-2 expression in dermal lymphocytes, would result in follicular miniaturization and fibrosis.