Serum and tissue angiotensin-converting enzyme in patients with alopecia areata

Alopecia areata is an immune-dependent disorder characterized by the interaction of T-lymphocytes with follicular antigens. Recent studies have shown the existence of a local renin-angiotensin system in the skin, where angiotensin-converting enzyme (ACE) plays a role in autoimmunity and inflammation.The objective of this study was to evaluate serum and tissue ACE activity in patients with alopecia areata.This case-control study was conducted on patients with alopecia areata and healthy controls. Serum and tissue ACE activity were assessed and compared between the two groups.Twenty-five alopecia areata patients (60% male, mean age 32.1 ± 9.9 years) and 24 controls (50% male, mean age 37.4 ± 8.8 years) were included. Mean serum ACE activity was 52.1 ± 9 U/L in cases and 55.3 ± 14.7 U/L in controls (P = 0.37). Tissue ACE activity was significantly lower in cases in all parts of the skin i.e. epidermis (P = 0.016), follicular epithelium (P = 0.004), and endothelium (P = 0.037). Among cases, serum ACE activity was significantly higher in patients with more severe disease (P = 0.030), nonpatchy alopecia areata (alopecia universalis; ophiasis, patchy and ophiasis, diffuse) (P = 0.029), and with nail involvement (P = 0.027).The sample size was too small to draw definite conclusions. Further, most of the patients had only mild or moderate alopecia areata.Unlike in some other inflammatory diseases, the tissue level of ACE seems to be significantly lower in alopecia areata compared to normal controls. Serum ACE was significantly higher in patients with more severe disease.