17β-Estradiol enhances contact hypersensitivity and IFN-γ expression in inflamed skin of BALB/c mice

Oestrogen inhibits psoriasis-like dermatitis induced by imiquimod in mice in relation to increased IL-10 producing cells despite elevated expression of IL-22, IL-23, IL-17 mRNA

Sex hormones influence the development and natural course of psoriasis. Here, we examined the effects of female sex hormones, particularly oestrogen, on psoriasis-like dermatitis induced using topical imiquimod in mice that underwent either sham operation (Sham) or ovariectomy (OVX), with (hormone replacement treatment: HRT) or without 17β-oestradiol targeting the maximum physiological levels. The number of neutrophils in the skin was higher in the order of OVX-, Sham-, and HRT-treated mice. However, no significant difference was detected in the clinical scores among the three groups due to severe erythema and scale in a few mice out of HRT-treated mice in a set of experiments. OVX- and HRT-treated mice showed increased mRNA levels of interleukin (IL)-22 and IL-23 compared with Sham-treated mice; increased IL-10 mRNA levels were found in HRT-treated mice, possibly due to an increased proportion of forkhead box P3 (Foxp3)- and IL-10 positive large cells (possibly macrophages). In addition, HRT-treated mice had a more compact stratum corneum with higher expression of loricrin and involucrin than OVX- and Sham-treated mice. This study suggests that oestrogen has a dual potential in the pathogenesis of psoriasis: suppression of inflammation by enhancing IL-10 production and enhancement of inflammation by induction of IL-22 and IL-23 expression.

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.

17beta-Estradiol increases the number of effector memory CD8+ lymphocytes in mice with contact hypersensitivity and among cultured splenocytes

To determine how estrogen exacerbates allergies, the effects of 17beta-estradiol (E2) on lymphocyte proliferation were investigated. BALB/c mice were ovariectomized, administered 3.2 microg E2, and sensitized with 50 microL 4-ethoxymethylene-2-phenyl-2-oxazolin-5-one. After 7 days, their spleens were excised and flow cytometrically analyzed. The CD8(+)CD45RA(-)CCR7(-) cell-to-CD8(+) cell ratio in the spleen was greater in the E2-administered mice than in the controls. Splenocytes were cultured under concanavalin A stimulation, with or without E2. After 4 days, the above ratio was greater in the case of E2-treated splenocytes. E2 increases the number of effector memory CD8(+) lymphocytes during sensitization in contact hypersensitivity.