Solar ultraviolet B (UVB) radiation induces cutaneous ornithine decarboxylase (ODC), the first enzyme in the polyamine-biosynthesis pathway, which drives continued proliferation and clonal expansion of initiated (mutated) cells, leading to tumorigenesis. Therefore ODC is a potentially important target for chemoprevention of basal cell carcinomas (BCCs), the majority of which have mutations in the tumor-suppressor gene known as patched (PTCH). To assess this possibility, we first overexpressed ODC in the skin of Ptch1+/– mice using a keratin 6 (K6) promoter that directs constitutive ODC expression in the outer root sheath of the hair follicle. UVB irradiation of these mice accelerated induction of BCCs as compared with their Ptch1+/– littermates. To further verify the role of ODC in BCC tumorigenesis, we used an antizyme (AZ) approach to inhibit ODC activity in the Ptch1+/– mice. Ptch1+/– mice with AZ overexpression driven by the K6 promoter were resistant to the induction of BCCs by UVB. Furthermore, oral administration of the suicidal ODC inhibitor α-difluoromethylornithine reduced UVB-induced BCCs in Ptch1+/– mice. These results demonstrate the crucial importance of ODC for the induction of BCCs and indicate that chemopreventive strategies directed at inhibiting this enzyme may be useful in reducing BCCs in human populations.
Xiuwei Tang, Arianna L. Kim, David J. Feith, Anthony E. Pegg, Justin Russo, Hong Zhang, Michelle Aszterbaum, Levy Kopelovich, Ervin H. Epstein Jr., David R. Bickers, Mohammad Athar
Langerhans cells (LCs) constitute a subset of DCs that initiate immune responses in skin. Using leprosy as a model, we investigated whether expression of CD1a and langerin, an LC-specific C-type lectin, imparts a specific functional role to LCs. LC-like DCs and freshly isolated epidermal LCs presented nonpeptide antigens of Mycobacterium leprae to T cell clones derived from a leprosy patient in a CD1a-restricted and langerin-dependent manner. LC-like DCs were more efficient at CD1a-restricted antigen presentation than monocyte-derived DCs. LCs in leprosy lesions coexpress CD1a and langerin, placing LCs in position to efficiently present a subset of antigens to T cells as part of the host response to human infectious disease.
Robert E. Hunger, Peter A. Sieling, Maria Teresa Ochoa, Makoto Sugaya, Anne E. Burdick, Thomas H. Rea, Patrick J. Brennan, John T. Belisle, Andrew Blauvelt, Steven A. Porcelli, Robert L. Modlin
We found that mechanical injury to mouse skin, which can be caused by tape stripping, results in rapid induction of IL-10 mRNA. IL-10–/– mice were used to examine the role of IL-10 in a mouse model of allergic dermatitis induced by epicutaneous (EC) sensitization with OVA on tape-stripped skin. Skin infiltration by eosinophils and expression of eotaxin, IL-4, and IL-5 mRNA in OVA-sensitized skin sites were severely diminished in IL-10–/– mice. Following in vitro stimulation with OVA, splenocytes from EC-sensitized IL-10–/– mice secreted significantly less IL-4, but significantly more IFN-γ, than splenocytes from WT controls. A similar skewing in cytokine secretion profile was observed in the splenocytes of IL-10–/– mice immunized intraperitoneally with OVA. IL-10–/– APCs skewed the in vitro response of OVA T cell receptor (TCR) transgenic T cells towards Th1. Examination of the Th response of WT and IL-10–/– mice immunized with OVA-pulsed WT or IL-10–/– DCs revealed that both DCs and T cells participate in IL-10 skewing of the Th2 response in vivo. These results suggest that IL-10 plays an important role in the Th2 response to antigen and in the development of skin eosinophilia in a murine model of allergic dermatitis.
Dhafer Laouini, Harri Alenius, Paul Bryce, Hans Oettgen, Erdyni Tsitsikov, Raif S. Geha
E-selectin and P-selectin on dermal postcapillary venules play critical roles in the migration of effector T cells into inflamed skin. P-selectin glycoprotein ligand-1 (PSGL-1) modified by α1,3-fucosyltransferase is the principal selectin ligand on skin-homing T cells and is required for effector T cell entry into inflamed skin. We have previously shown that a fluorinated analog of N-acetylglucosamine peracetylated-4-fluorinated-D-glucosamine (4-F-GlcNAc), inhibits selectin ligand expression on human T cell PSGL-1. To analyze 4-F-GlcNAc efficacy in dampening effector T cell migration to inflamed skin, we elicited allergic contact hypersensitivity (CHS) reactions in mice treated with 4-F-GlcNAc. We also investigated 4-F-GlcNAc efficacy on lymphocyte E-selectin ligand expression in LNs draining antigen-sensitized skin and on other immunological processes requisite for CHS responses. Our results showed that 4-F-GlcNAc treatment attenuated lymphocyte E-selectin ligand expression in skin-draining LNs and prevented CHS reactions. Significant reductions in inflammatory lymphocytic infiltrate were observed, while pathways related to antigenic processing and presentation and naive T cell recognition within skin-draining LNs were unaffected. These data indicate that 4-F-GlcNAc prevents CHS by inhibiting selectin ligand activity and the capacity of effector T cells to enter antigen-challenged skin without affecting the afferent phase of CHS.
Charles J. Dimitroff, Thomas S. Kupper, Robert Sackstein
Current therapeutic strategies for genetic skin disorders rely on the complex process of grafting genetically engineered tissue to recipient wound beds. Because fibroblasts synthesize and secrete extracellular matrix, we explored their utility in recessive dystrophic epidermolysis bullosa (RDEB), a blistering disease due to defective extracellular type VII collagen. Intradermal injection of RDEB fibroblasts overexpressing type VII collagen into intact RDEB skin stably restored correctly localized type VII collagen expression in vivo and normalized hallmark RDEB disease features, including subepidermal blistering and anchoring fibril defects.
Susana Ortiz-Urda, Qun Lin, Cheryl L. Green, Douglas R. Keene, M. Peter Marinkovich, Paul A. Khavari