Glucocorticoids augment the chemically induced production and gene expression of interleukin-1alpha through NF-kappaB and AP-1 activation in murine epidermal cells.

To clarify the mechanism of the glucocorticoid-induced augmentation of skin response, we attempted to demonstrate the modulatory effect of glucocorticoids on the regulation of cytokines produced by keratinocytes stimulated with various chemicals in vitro. Haptens, irritants, and a superantigen (staphylococcal enterotoxin B) induced a significant release of interleukin-1alpha and tumor necrosis factor alpha, but not interleukin-10, from a murine keratinocyte cell line, Pam 212 cells. Glucocorticoids (10(-6)-10(-12) M) significantly augmented the production of interleukin-1alpha by Pam 212 cells at both the protein and mRNA levels when stimulated by either haptens or irritants, but not by staphylococcal enterotoxin B, whereas glucocorticoids alone had no effect. In contrast, glucocorticoids had no effect on the production of tumor necrosis factor alpha and interleukin-10 by chemically stimulated Pam 212 cells. Electrophoretic mobility shift assays revealed that chemical stimulation induced NF-kappaB activation in Pam 212 cells; however, augmented NF-kappaB activation by 10(-6)-10(-8) M of glucocorticoids was observed in Pam 212 cells stimulated by both haptens and irritants, but not by staphylococcal enterotoxin B. Furthermore, pyrrolidine dithiocarbamate inhibited the hapten-induced interleukin-1alpha production and NF-kappaB expression by Pam 212 cells. Pyrrolidine dithiocarbamate did not completely abrogate the hapten-induced interleukin-1alpha production augmented by glucocorticoids, however. To determine the effect on transcription factors other than NF-kappaB, AP-1 activity was examined by electrophoretic mobility shift assays. Hapten was founded to induce AP-1 activation in Pam 212 cells. In addition, AP-1 activation was augmented in the hapten-stimulated Pam 212 cells in the presence of 10(-8)-10(-10) M of glucocorticoids. The augmented inflammatory reaction by glucocorticoids may therefore reflect the augmentation of interleukin-1alpha production by keratinocytes mediated through the NF-kappaB and AP-1 pathway.

Topical glucocorticoid augments IgE-mediated passive cutaneous anaphylaxis in Balb/C mice and mast cell deficient WBB6F1 v/v mice.

BACKGROUND: In a last decade, new types of skin manifestations have been recognized in atopic dermatitis especially in Japan. They are frequently observed in adult patients with atopic dermatitis after a long-standing steroid ointment and termed adult type-atopic dermatitis. OBJECTIVE: To clarify whether topical glucocorticoid (GC) modulates cutaneous inflammatory reactions in addition to known anti-inflammatory effect, we have examined the effect of long-term application of topical GC on IgE-mediated murine cutaneous reactions. METHODS: Fifty microlitres of diflucortolone valerate (1 mg/mL), prednisolone valerateacetate (3 mg/mL), or triamcinolone acetonide (1 mg/mL) were applied seven times on alternate day, to the flank skin of mice. On day 12 when mice received the seventh application of GC, each mouse was given an intravenous application of IgE anti-DNP antibody (PCA titre > x 2560) 1 h before the skin test with 0.15% DNFB in acetone:olive oil (4:1) on the right pinna. The left pinna was painted with a vehicle as a control. Increased ear thickness was measured at 1, 4, 24, 48 and 72 h to assess the augmentry effect of GC. RESULTS: Topical application of GC (50 microg diflucortolone valerate in ethanol) on the flank skin seven times on alternate days, augmented expression of passive cutaneous anaphylaxis reaction on the ear skin induced by intravenous applications of monoclonal IgE anti-DNP antibody and following the challenge test. In contrast, topical application of GC inhibited the reactions when applied on the challenged sites. Several types of GC, but not vitamin D3, augmented the skin reactions and these augmented reactions persisted for 72 h when control skin reactions subsided. GC induced a late phase but not an early phase cutaneous reaction in mast cell deficient WBB6F1 v/v mice by IgE anti-DNP antibody. CONCLUSION: Long-term application of topical GC might modulate local cutaneous immune response and augment IgE-mediated cutaneous reactions. Fc epsilon R(+) cells other than mast cell might be involved in the IgE-mediated late-phase reaction.

Topical vitamin D3 downregulates IgE-mediated murine biphasic cutaneous reactions.

Hapten-specific and mast-cell-dependent biphasic (immediate and delayed-onset) cutaneous reactions were induced in a murine model by intravenous injection of anti-DNP IgE antibodies followed by a skin test. Four daily applications of topical 1 alpha,24(OH)2D3 ointment significantly inhibited both the immediate and the delayed-onset cutaneous reactions in a dose-dependent fashion, as well as the croton-oil-induced cutaneous reaction and DNFB contact sensitivity reaction. 1 alpha,24(OH)2D3 itself did not show any sensitizing or irritant potential. The inhibitory effect of 1 alpha,24(OH)2D3 on these reactions was limited to the application site and no systemic effect was observed. Another vitamin D3 analog 1 alpha,25(OH)2D3, also showed an inhibitory effect on IgE-mediated cutaneous reactions. These results suggest that topically applied 1 alpha,24(OH)2D3 might modulate IgE-mediated cutaneous reactions and could thus be useful in the treatment of certain human cutaneous disorders other than psoriasis and related keratinizing disorders.

Topical glucocorticoids application induced an augmentation in the expression of IL-1alpha while inhibiting the expression of IL-10 in the epidermis in murine contact hypersensitivity.

The repeated application of glucocorticoids (GC) on the skin augmented the inflammatory response of both allergic and irritant contact dermatitis in our studies. In order to further clarify the mechanism of such an augmentation of contact hypersensitivity (CHS), we investigated the modulatory effects of cytokines in the epidermis after the administration of GC at challenged sites in CHS. Diflucortolone valerate was applied to BALB/c mice on alternate days for a total of nine times. On day 12, they were contact sensitized with dinitrofluorobenzene (DNFB). Next, on day 17, one day after the last application of GC, they were challenged with DNFB on the ear. The whole challenged ear lobes were removed after a hapten challenge and then were analysed by the RT-PCR method or underwent an immunohistochemical analysis. To clarify the modulatory effects of cytokines in vivo, DNFB sensitized mice pre-treated with GC were injected with rIL-10, IL-1 receptor antagonist (ra) and anti-IL-1alpha monoclonal antibody (mAb) and thereafter were challenged with DNFB. A RT-PCR analysis has demonstrated IL-10 mRNA to be detected in the challenged skin of non-GC-pretreated mice but not in that of GC-pre-treated mice after challenge. On the other hand, the expression of IL-1alpha mRNA in the challenged skin of mice pretreated with GC was more strongly detected that that in mice without GC-pretreatment. Furthermore, an immuno-histochemical analysis in the challenge showed the expression of IL-10 in the skin showed the expression of IL-10 in the challenged epidermis of the non-GC-pretreated mice but not in the GC-pretreated mice and IL-1alpha was also strongly expressed in the epidermis of the GC-pretreated mice. A subcutaneous injection of anti-IL-1alpha mAb or IL-1 ra inhibited the augmented CHS reaction in the GC-pretreated mice. A subcutaneous injection of rIL-10 also inhibited the augmentation of the CHS reaction in the GC-pretreated mice; however, no such inhibition was observed in the non-GC-pretreated mice. These results indicated that both an up-regulation of IL-1alpha production and the inhibition of the IL-10 production in the epidermis at the challenged skin sites in the GC-pretreated mice appear to play a critical role in the GC-induced augmentation of murine CHS.