Abstract
BACKGROUND: A difference of the interleukin-18 (IL-18) mRNA expression among several proinflammatory genes was previously observed between large plaque (LP) psoriasis patients (more than 5 cm lesions are typical) and small plaque (SP) psoriasis patients (1~2 cm lesions are typical). Therefore, it is necessary to test whether there is any difference in the expression of the genes that activate IL-18 or the expression of genes that are induced by IL-18. OBJECTIVE: To test the differential mRNA expressions of caspase-1, STAT-6, MMP-1, MMP-2, MMP-9 and TIMP-1 according to the clinical types of psoriasis vulgaris lesions in Korean patients, we have analyzed the skin samples of psoriasis vulgaris patients. METHODS: The total cellular RNA of skin samples from groups of patient with LP and SP psoriasis was analyzed by performing real-time PCR (the Taqman method) to compare the differences in the mRNA expressions. RESULTS: The caspase-1 and STAT-6 mRNA expression levels from the SP lesional skin of the patients were increased compared with the caspase-1 and STAT-6 mRNA expression levels from SP non-lesional skin or normal skin, but these expression levels from the SP non-lesional skin were not significantly different from those of the LP non-lesional skin. Among MMP-1, MMP-2, MMP-9 and TIMP-1, the expressions of MMP-1, MMP-2 and MMP-9 mRNA were increased in the SP lesional skin compared with those of the SP non-lesional skin. The MMP-1 mRNA expressions in both the LP and SP lesional skin were increased compared with those in the normal skin (p=0.028 and p=0.007 respectively). The MMP-9 mRNA expression in the LP non-lesional skin was elevated compared with the MMP-9 mRNA expression in the SP non-lesional skin (p=0.047). The TIMP-1 mRNA expression levels from the non-lesional skin and the lesional skin of the psoriasis patients and the normal skin samples were not significantly different. CONCLUSION: The increased expression of MMP-9 mRNA in the LP non-lesional skin compared to that of the SP non-lesional skin in the psoriatic skin suggests that the increased MMP-9 mRNA expression is related to the large size type of lesion.