Comparative analysis of cyclin-dependent kinase 2 density by immunohistochemistry in lesional versus nonlesional psoriatic skin

Abstract

Background Psoriasis is a noninfectious, inflammatory, and hyperproliferative skin disorder. Cyclin-dependent kinase 2 (CDK2) is a serine-threonine protein kinase that plays a role in the transition of G1/S, the initiation of DNA synthesis, and the regulation of the S phase exit in the cell cycle. CDK2 is uniformly expressed in healthy human epidermis being located mainly in the cytoplasm and nuclei of basal keratinocytes. Objective To compare the CDK2 density by immunohistochemistry in lesional versus nonlesional psoriatic skin and normal control and to correlate its expression with disease severity. Patients and methods This study was conducted on 30 patients with plaque psoriasis and 20 age-matched and sex-matched controls. Biopsies were obtained from the active plaque (lesional) and nonlesional skin of the patients and normal controls. CDK2 density was assessed by counting immunohistochemically positive nuclei in 1000 suprabasal keratinocytes at ×400 power fields. Results CDK2 was negative in normal control skin (no positive nuclear staining was seen in suprabasal keratinocytes). Meanwhile, the psoriatic group showed diffuse nuclear positivity in suprabasal cells. The density was significantly higher in lesional versus nonlesional skin. CDK2 density in lesional and nonlesional skin showed a statistically significant correlation with Psoriasis Area and Severity Index score (r=0.820 and 0.683, P<0.001 and <0.001, respectively). Conclusion CDK2 density is high in plaque psoriatic epidermis more than in nonlesional and control skin, and this was positively correlated with disease severity. It indicates that it may play a role in the development of psoriasis and may be a potential therapeutic target.