SCCA2 a potential marker of disease activity, treatment efficacy in atopic dermatitis
Serum levels of squamous cell carcinoma antigen 2 (SCCA2) are indicative of disease severity and clinical type of atopic dermatitis (AD), according to a recent study, suggesting that SCCA2 may be a novel and useful marker for evaluating disease activity and treatment efficacy in AD.
The study included 240 adult patients with AD and 25 healthy controls. Serum SCCA2 levels were measured using an enzyme-linked immunosorbent assay. SCCA2 was analysed in relation to clinical characteristics and laboratory parameters including thymus and activation-regulated chemokine (TARC), lactate dehydrogenase (LDH), blood eosinophils, total IgE, and specific IgE (eg, Japanese cedar pollen, Dermatophagoides farina, Candida, malassezia, Staphylococcal enterotoxin B).
Other assessments included the expression of SCCA2 in AD eruption and the effect of treatment on serum SCCA2.
Serum SCCA2 levels were positively associated with disease severity, levels of TARC, LDH, eosinophil counts and IgE levels. Robust SCCA2 expression was identified in the supra basal keratinocytes in the epidermis of AD patients.
When SCCA2 was analysed by clinical types of AD, serum levels were significantly higher in patients with erythroderma type vs other types. In patients whose lesions were not widely distributed, such as those with limb type, SCCA2 levels were lower. No association was noted between the severity of prurigo type AD and serum levels of SCCA2.
Aside from reflecting the extent of lesional skin, SCCA2 levels were also likely to better indicate the extent of chronic inflammation.
Overall, SCCA2 levels decreased after treatment for AD.
Known as a tumour biomarker for various squamous cell tumours, SCCA comprises two nearly identical proteins, SCCA1 and SCCA2. Both proteins belong to the ovalbumin-serpin proteinase inhibitor family and have shown activity against different proteases. [Clinic Rev Allergy Immunol 2013;45:267–280]