Apremilast downregulates interleukin-17 production and induces splenic regulatory B cells and regulatory T cells in imiquimod-induced psoriasiform dermatitis.

Apremilast, a selective inhibitor of the enzyme phosphodiesterase 4, is efficacious for psoriasis. However, detailed in vivo effects of apremilast on psoriasis remain to be elucidated. To examine the in vivo effects of apremilast on psoriasis. Psoriasiform dermatitis was induced by applying imiquimod (IMQ) on the murine shaved back skin for six days. Mice were treated with apremilast or vehicle intraperitoneally daily. Apremilast alleviated IMQ-induced psoriasiform dermatitis clinically and pathologically on days 3-6 by reducing infiltration of antigen-presenting cells and interleukin (IL)-17A-positive cells and increasing infiltration of Foxp3-postive cells into the skin on day 6, although a significant increase in IL-10 mRNA level was not observed on day 2. In addition, mRNA expression of IL-17A, IL-17F, and IL-22 was lower in the skin of IMQ-applied mice treated with apremilast than in those without apremilast on day 2, and apremilast inhibited infiltration of IL-17A-producing γδ T cells into the dermis on day 6. Furthermore, apremilast induced regulatory T cells and regulatory B cells in the spleen but not in the draining lymph nodes. Apremilast downregulated IL-17 production and induced splenic regulatory B cells and regulatory T cells in an IMQ-induced psoriasiform dermatitis mouse model.

Uchida H ，Kamata M ，Shimizu T ，Egawa S ，Ito M ，Takeshima R ，Mizukawa I ，Watanabe A ，Tada Y ... -  《-》

Fingolimod ameliorates imiquimod-induced psoriasiform dermatitis by sequestrating interleukin-17-producing ?d T cells in secondary lymph nodes.

Psoriasis is a chronic inflammatory skin disease. Interleukin (IL)-17A plays a key role in the pathogenesis of psoriasis. Fingolimod, which is available for the treatment of multiple sclerosis, exerts anti-inflammatory effects by sequestrating inflammatory lymphocytes in secondary lymphoid tissues and the thymus. The effect of fingolimod on psoriasis has not been reported yet. Our objectives were to investigate the effect of fingolimod on psoriasis utilizing mice with imiquimod (IMQ)-induced psoriasiform dermatitis, and explore the possibility of fingolimod as a therapeutic agent for psoriasis. Psoriasiform dermatitis was induced by imiquimod application on murine shaved back skin for six days. Fingolimod prepared in phosphate-buffered saline (PBS), or PBS alone as a control, was administered intraperitoneally daily from days 0 to 5. Fingolimod ameliorated IMQ-induced psoriasis dermatitis clinically and histologically. On day 6, the mRNA expression level of IL-17A was lower in the skin of fingolimod-treated mice than in that of PBS-treated mice, whereas it was higher in the inguinal lymph nodes of fingolimod-treated mice than in those of PBS-treated mice. Flow cytometric analyses revealed that fingolimod reduced IL-17A-producing ?d T cells infiltrating into the skin, whereas it increased these cells in the inguinal lymph nodes. Fingolimod inhibited egress of Langerhans cells from the skin to lymph nodes. Our results demonstrated that fingolimod showed effectiveness for IMQ-induced psoriasiform dermatitis by hindering the emigration of IL-17A-producing ?d T cells from the lymph nodes to the skin, and suggest that fingolimod is a promising candidate for the treatment of psoriasis.

Okura I ，Kamata M ，Asano Y ，Mitsui A ，Shimizu T ，Sato S ，Tada Y ... -  《-》

Anti-IL-17A and IL-23p19 antibodies but not anti-TNFα antibody induce expansion of regulatory T cells and restoration of their suppressive function in imiquimod-induced psoriasiform dermatitis.

Psoriasis is a chronic inflammatory skin disease. Anti-TNFα, IL-17A and IL-23p19 antibodies are effective for psoriasis. However, the contribution of regulatory T cells (Treg) in their effectiveness remains to be elucidated. We investigated the effects of TNFα, IL-17A and IL-23p19 inhibition on Tregs in imiquimod-induced psoriasiform dermatitis. Psoriasiform dermatitis was induced by imiquimod application on murine shaved back skin for six days. Mice were treated with anti-TNFα, IL-17A or IL-23p19 monoclonal antibodies every other day from one day before imiquimod application. Administration of anti-TNFα, IL-17A or IL-23p19 antibodies improved the clinical score and downregulated Th17-related cytokines and chemokines, while IL-23p19 antibodies upregulated IL-10 mRNA expression. Anti-IL-17A or IL-23p19 antibody-treated imiquimod-applied mice showed a significant increase in the number of Foxp3+ IL-10+ Tregs. Recipient mice adoptively transferred with Tregs derived from donor mice treated with antibodies demonstrated clinical and pathological improvement in imiquimod-induced psoriasiform dermatitis. Anti-IL-17A or IL-23p19 antibody-induced Tregs significantly increased the number of Foxp3+ cells and IL-10 expression in imiquimod-induced psoriasiform dermatitis in recipient mice but anti-TNFα antibody-induced Tregs did not. Anti-IL-17A or IL-23p19 antibody inhibits the IL-17/IL-23 signaling pathway, and induces expansion of Tregs and their suppressive capacity in imiquimod-induced psoriasiform dermatitis.

Shimizu T ，Kamata M ，Fukaya S ，Hayashi K ，Fukuyasu A ，Tanaka T ，Ishikawa T ，Ohnishi T ，Tada Y ... -  《-》

The vitamin D(3) analog, maxacalcitol, reduces psoriasiform skin inflammation by inducing regulatory T cells and downregulating IL-23 and IL-17 production.

Psoriasis is a Th1/Th17-mediated inflammatory dermatosis treated with topical corticosteroids and vitamin D3 analogs (VD3 As). To compare the effects of a VD3 A maxacalcitol and betamethasone valerate (BV) steroid lotion on topical imiquimod (IMQ)-induced psoriasiform skin inflammation. Female BALB/c mice were treated with vehicle, maxacalcitol or BV lotion on the skin for 3 days, and IMQ cream for 6 days. q-PCR, H&E, immunohistochemistry and immunofluorescence studies were performed on skin samples. Additionally, mice were treated with vehicle, maxacalcitol or BV lotion for 3 days and CD4+CD25+ regulatory T cells (Tregs) and CD4+CD25- cells from each group were isolated from lymph nodes. Adoptive transfer of the cells was performed on recipient mice which were treated with IMQ cream for 6 days, and skin samples were obtained for q-PCR and H&E staining. Maxacalcitol and BV were comparable in regards clinical improvement, although maxacalcitol reduced the MHC Class II+ inflammatory cell infiltration more than BV in IMQ skin. While both treatments downregulated IL-17 A, IL-17 F, IL-22, IL-12p40, TNF-α and IL-6 mRNA expression levels, only maxacalcitol downregulated IL-23p19 expression. Significantly increased Foxp3+ cell infiltrations and IL-10 expression were noted in maxacalcitol-treated IMQ skin. Adoptive transfer of Treg cells from maxacalcitol-treated donor mice improved IMQ-induced inflammation clinically and histopathologically more than the recipients of Treg cells from BV-treated donor groups, showing reduced levels of inflammatory cytokines and increased IL-10 expression. These results indicate that maxacalcitol reduces psoriasiform skin inflammation by inducing Treg cells as well as downregulating IL-23 and IL-17 production.

Hau CS ，Shimizu T ，Tada Y ，Kamata M ，Takeoka S ，Shibata S ，Mitsui A ，Asano Y ，Sugaya M ，Kadono T ，Sato S ，Watanabe S ... -  《-》

5-hydroxytryptophan attenuates imiquimod-induced psoriasiform dermatitis probably through inhibition of IL-17A production and keratinocyte activation.

Psoriasis is a chronic autoimmune disease with keratinocyte activation and lymphocyte infiltration in the skin. Our previous study found that 5-hydroxytryptophan (5(OH)Trp), a tryptophan metabolite, alleviated collagen-induced arthritis and suppressed cytokine production. In this study, we evaluated the effects of 5(OH)Trp in a mouse model for psoriasiform dermatitis, induced by imiquimod (IMQ). We showed that 5(OH)Trp significantly reduced the cumulative scores, epidermal thickness and ki-67 expression in the skin. In addition, 5(OH)Trp decreased local and systemic inflammation. Moreover, 5(OH)Trp significantly inhibited keratinocyte activation with decrease in IL-6 production and p-Erk1/2 and p-STAT3 expression. 5(OH)Trp also inhibited the differentiation of IFN-γ- and IL-17A-expressing CD4+ T cells and related cytokine production (TNF-α, IL-6, IL-17A and IFN-γ) in splenocytes. In conclusion, 5(OH)Trp can inhibit imiquimod-induced psoriasiform dermatitis in mice and inhibit activation in keratinocytes and splenocytes.

Hsu PY ，Yang HJ ，Yang TH ，Su CC ... -  《-》