Fucosylation deficiency enhances imiquimod-induced psoriasis-like skin inflammation by promoting CXCL1 expression.

Psoriasis is a multifaceted chronic inflammatory skin disease; however, its underlying molecular mechanisms remain unclear. In this study, we explored the role of fucosylation in psoriasis using an imiquimod-induced psoriasis-like mouse model. ABH antigen and fucosyltransferase 1 (Fut1) expression was reduced in the granular layer of lesional skin of patients with psoriasis. In particular, the blood group H antigen type 2 (H2 antigen)-a precursor of blood group A and B antigens-and FUT1 were highly expressed throughout the spinous layer in both patients with psoriasis and the skin of imiquimod-treated mice. Upon the application of imiquimod, Fut1-deficient mice, which lacked the H2 antigen, exhibited higher clinical scores based on erythema, induration, and scaling than those of wild-type mice. Imiquimod-treated Fut1-deficient mice displayed increased skin thickness, trans-epidermal water loss, and Gr-1+ cell infiltration compared with wild-type mice. Notably, the levels of CXCL1 protein and mRNA were significantly higher in Fut1-deficient mice than those in wild-type mice; however, there were no significant differences in other psoriasis-related markers, such as IL-1ß, IL-6, IL-17A, and IL-23. Fut1-deficient primary keratinocytes treated with IL-17A also showed a significant increase in both mRNA and protein levels of CXCL1 compared with IL-17A-treated wild-type primary keratinocytes. Further mechanistic studies revealed that this increased Cxcl1 mRNA in Fut1-deficient keratinocytes was caused by enhanced Cxcl1 mRNA stabilization. In summary, our findings indicated that fucosylation, which is essential for ABH antigen synthesis in humans, plays a protective role in psoriasis-like skin inflammation and is a potential therapeutic target for psoriasis.

Thymic epithelial cell abnormalities in (NZB x H-2u)F1 mice.

Thymic maturation processes including MHC restriction and self-recognition require intimate association of thymocytes and stromal cells. Compared to the thymic architecture of various "normal" control strains of mice, defects in the thymic microenvironment have been demonstrated in New Zealand black (NZB) mice. Moreover, it is well known that NZB(H-dd) mice, when crossed with NZW(H-2u) mice, (NZB x NZW)F1, display a unique spectrum of autoimmune disease manifestations, including murine SLE. Using an extensive panel of monoclonal antibodies that define the thymic microenvironment, we examined two additional strains of (NZB x H-2u)F1 mice: (NZB x C57BL/10.PL)F1 and (NZB x PL/J)F1 mice to investigate the contributions of the H-2 and non-H-2 loci to the thymic abnormalities previously documented to occur in murine lupus. NZB, NZW, and (NZB x NZW)F1 mice were studied concurrently as were two additional control strains C57BL/6 and C57BL/10Sn. NZW mice had a normal thymic architecture as did the other H-2u mice and the control strains. In contrast, (NZB x NZW)F1 mice had a significantly altered thymic microenvironment; mild thymic abnormalities were also found in (NZB x PL/J)F1 but not in (NZB x C57BL/10.PL)F1. As expected, (NZB x NZW)F1 mice developed elevated titers of autoantibodies to DNA, proteinuria, and decreased life span. Interestingly, only (NZB x PL/J)F1 mice had increased levels of IgM antibodies to dsDNA, but did not manifest IgG anti-DNA or reduced survival. Defects in thymic stromal cells are associated directly to autoimmunity and their origin appears to be determined by non-H-2 loci.

T-cell subsets, IFN-gamma production and efferent specificity in anti-parental tumor immunity induced by mouse sensitization with xenogenized variant cells.

In addition to previous evidence for a role of L3T4+ T cells in the protective anti-parental tumor immunity induced by xenogenized variant cells of a murine lymphoma (L5178Y/DTIC), we have investigated the possible participation in this effect of L5178Y tumor-specific lymphocytes of the Lyt-2+ T cell subset. Spleen cells from L5178Y/DTIC tumor-immunized mice produced high levels of IFN-gamma in vitro in response to parental antigens, and this activity was only abolished by treating the responder population with anti-Thy-1.2 antibody or a combination of anti-L3T4 and anti-Lyt-2.2 monoclonal antibodies (MAbs) plus complement. Positively selected L3T4+ and Lyt-2+ cells also produced IFN-gamma in vitro, provided accessory cells (plastic-adherent and Thy-1- Ia- splenocytes, respectively) were added to the lymphocyte-tumor cell cocultures. The production of IFN-gamma by purified L3T4+ and Lyt-2+ cells was inhibited by addition of the respective anti-class-II and anti-class-I H-2 antibody to the cultures. Administration of anti-IFN-gamma MAb in vivo significantly impaired the resistance of L5178Y/DTIC-immune mice to challenge with parental cells, as manifested by survival criteria and increased tumor-cell proliferation in the spleens of antibody-treated mice. Although anti-parental tumor protection in vivo and T-cell activation in vitro for IFN-gamma production were strictly antigen-specific, bystander tumor inhibition was observed when antigenically irrelevant cells were inoculated with the L5178Y lymphoma. These results suggest that both L3T4+ and Lyt-2+ T cells play a role in the protective anti-parental tumor immunity induced by xenogenized cells, and that their activity may involve IFN-gamma-mediated stimulation of non-specific tumoricidal mechanisms.