Expression of interleukins in adult female acne: evaluating the effects of azelaic acid

Background Adult female acne (AFA) is a multifactorial skin condition that affects women aged > 25 years, with inflammation playing a central role in its aetiopathogenesis. However, most research has primarily focused on severe acne vulgaris, while the immunological mechanisms underlying AFA remain poorly understood. Objectives To analyse interleukin (IL)-6 and IL-8 expression in inflammatory lesions of AFA, before and after treatment with topical azelaic acid (AZA) 15% gel, and compare the findings with healthy skin; and to evaluate the efficacy of AZA based on clinical response and histopathological findings. Methods Twenty women with mild-to-moderate AFA used AZA 15% gel twice daily for 6 months, with monthly follow-ups. Skin biopsies from lesional and healthy facial areas were collected at baseline and at treatment completion to assess IL-6 and IL-8 by immunohistochemistry and to score inflammation. Clinical evaluation, including Visia® imaging, Investigator Global Assessment and the Erythema Assessment Scale, was performed before and after treatment. Results There was significant overexpression of IL-6 and IL-8 in acne lesions compared with healthy skin, P < 0.05. Following treatment, a significant reduction in IL-6 (P < 0.0001) and IL-8 (P < 0.05) expression was observed. Skin with acne lesions exhibited intense inflammatory infiltrate and a significant reduction post-treatment. Treatment with AZA resulted in highly significant clinical improvement of acne severity and erythema (P < 0.0001). Conclusions IL-6 and IL-8 expressions are increased in AFA, contributing to its inflammatory process. Therapies that reduce these proinflammatory cytokines, such as AZA, are beneficial. Our findings are consistent with a potential anti-inflammatory effect of AZA, given the observed decrease in IL-6 and IL-8.