Proteomic analysis of skin irritation reveals the induction of HSP27 by sodium lauryl sulphate in human skin

Summary Background There is an increasing need for screening of mild irritants in vitro to reduce animal testing. Objectives Proteomics were used to search for new markers of which the expression changes after mild irritation. Methods Sodium lauryl sulphate (SLS) was applied topically on excised human skin. Epidermal proteins were isolated from SLS‐treated skin specimens that showed hardly any morphological changes. The proteins were analysed by two‐dimensional polyacrylamide gel electrophoresis (2D‐PAGE) and proteins that significantly increased or decreased after SLS treatment in a dose‐dependent way were characterized by mass spectrometry. Subsequently, immunohistochemistry was performed on skin samples treated with SLS in vivo and nonanoic acid (NAA) or benzalkonium chloride (BC) in vitro to evaluate one of the identified proteins for its predictive value. Results We identified seven proteins as potentially new epidermal markers for skin irritation. Among these seven proteins, the 27 kDa heat shock protein (HSP27) was identified as the most prominently upregulated protein. A strong nuclear HSP27 staining was seen in the SLS‐treated skin, whereas in the vehicle controls only cytoplasmic staining was observed. Moreover, nuclear staining was also observed after topical application of SLS in vivo and after exposure to NAA and BC in vitro. Conclusions Our findings suggest that HSP27 may serve as a sensitive marker of skin irritation and eventually as a novel tool in clinics for testing the sensitivity of the patient for a panel of irritants.