Theophylline exerts complex anti‐ageing and anti‐cytotoxicity effects in human skin ex vivo

Abstract Objective Theophylline is a phosphodiesterase inhibitor that is being used clinically for asthma therapy. In addition, it is recognized as a cosmetic agent with possible anti‐ageing and anti‐oxidative properties. Nevertheless, how it affects human skin is still poorly examined. Methods Theophylline (10 or 100 µM) was administered to the culture medium of full‐thickness human skin ex vivo for 24 or 72 h. Results Theophylline stimulated protein expression of the anti‐oxidant metallothionein‐1 and mRNA levels of collagen I and III. Assessment of fibrillin‐1 immunohistology revealed enhanced structural stability of dermal microfibrils. Theophylline also exerted extracellular matrix‐protective effects by decreasing MMP‐2 and MMP‐9 mRNA levels, partially antagonizing the effects of menadione, the potent, toxic ROS donor. In addition, it decreased menadione‐stimulated epidermal keratinocytes apoptosis. Interestingly, theophylline also increased the level of intracutaneously produced melatonin, that is the most potent ROS‐protective and DNA damage repair neuromediator, and tendentially increased protein expression of MT1, the melatonin receptor. Theophylline also increased the expression of keratin 15, the stem cell marker, in the epidermal basal layer but did not change mitochondrial activity or epidermal pigmentation. Conclusion This ex vivo pilot study in human skin shows that theophylline possesses several interesting complex skin‐protective properties. It encourages further examination of theophylline as a topical candidate for anti‐ageing treatment.