Estrogen receptor α activation aggravates imiquimod-induced psoriasis-like dermatitis in mice by enhancing dendritic cell interleukin-23 secretion.

Our recent study has reported that estrogen receptors (ERs) are involved in several types of allergy development. This study aims to investigate the possible relationship between ER activation and development of imiquimod-induced psoriasis-like dermatitis. A mouse model of imiquimod-induced psoriasis-like dermatitis was generated by 5 days of topical application of 5% of imiquimod cream on the back of the ear and the shaved back skin of male BALB/c mice. From the second day of applying 5% imiquimod cream, either ERα selective agonist (propylpyrazoletriol [PPT] 2.5 mg/kg) or ERβ selective agonist (diarylpropionitrile, DPN; 2.5 mg/kg) was administered orally for four consecutive days. Immediately after the final imiquimod cream application, scratching behavior was video monitored for 2 hours. The ear-swelling response was determined by comparing ear thickness before and after the final application of imiquimod cream. Twenty-four hours after the final imiquimod application, back skin tissue and auricular lymph nodes were isolated under isoflurane anesthesia. Oral administration of PPT significantly induced itch behavior and proinflammatory responses, including the levels of interleukin (IL)-17 and IL-22, whereas DPN treatment did not influence either pruritic or proinflammatory responses. In addition, IL-23 contribution by dendritic cells was identified using ER agonists on pretreated lipopolysaccharide (LPS)-stimulated murine bone marrow derived dendritic cells (BMDCs). PPT also significantly enhanced IL-23 secretion by LPS-stimulated BMDCs. Our findings indicate that the activation of ERα, but not ERβ, is directly associated with inflammatory and pruritic responses in a mouse model of the imiquimod-induced psoriasis by enhancing the secretion of IL-23 by dendritic cells.