Affected and unaffected skin of 4 psoriatic patients and normal skin of 3 psoriasis free individuals

Gene expression profiling was performed on biopsies of affected and unaffected psoriatic skin and normal skin from seven Japanese patients to obtain insights into the pathways that control this disease. U95A Affymetrix DNA chips that contain oligonucleotide arrays of approximately 12,000 well-characterized human genes were used in the study. The statistical analysis of the Affymetrix data, based on the ranking of the Student-test statistic, revealed a complex regulation of molecular stress and immune gene responses. The majority of the 266 induced-genes in affected and unaffected psoriatic skin were involved with interferon mediation, immunity, cell-adhesion, cytoskeleton restructuring, protein trafficking and degradation, RNA regulation and degradation, signaling transduction, apoptosis and atypical epidermal cellular proliferation and differentiation. The disturbances in the normal protein degradation equilibrium of skin were reflected by the significant increase in the gene expression of various protease inhibitors and proteinases including the induced components of the ATP/ubiquitin-dependent non-lysosomal proteolytic pathway that is involved with peptide processing and presentation to T-cells. Some of the upregulated genes, such as TGM1, IVL, CSTA, FABP5 and SPRR, are well known psoriatic markers involved in atypical epidermal cellular organization and differentiation. In the comparison between the affected and unaffected psoriatic skin, the transcription factor JUNB was found at the top of the statistical rankings for the 51 significantly upregulated genes in affected skin, suggesting that it has an important but as yet undefined role in psoriasis. Our gene expression data and analysis suggest that psoriasis is a chronic IFN and T-cell-mediated immune disease of the skin where the imbalance in epidermal cellular structure, growth and differentiation arises from the molecular antiviral stress signals initiating inappropriate immune responses.

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Kulski JK, Kenworthy W, Bellgard M, Taplin R, Okamoto K, Oka A, Mabuchi T, Ozawa A, Tamiya G, Inoko H