Evaluation of Indoleamine 2, 3-Dioxygenase Gene Expression and Activation in Chronic Spontaneous Urticaria

Chronic spontaneous urticaria (CSU) is a common skin disorder characterized by the emergence of hives for at least six weeks without any known etiologic agent. Indoleamine 2,3-dioxygenase (IDO) which catalyzes tryptophan (Trp) to kynorenin (KYN) is an immunomedulatory enzyme and complicated in immunological diseases. In this study, Trp, KYN and IDO gene expression in CSU patients were analyzed. We studied 20 CSU patients (mean age: 28 +/- 6 years, mean duration: 27 +/- 4 months) and 20 healthy individuals (mean age: 28 +/- 9 years). Peripheral blood mononuclear cells (PBMCs) were isolated from both patients and healthy control and stimulated by phytohemmaglutinin (PHA). Real-time PCR was applied to quantify IDO gene expression and its activity was estimated by KYN/Trp ratio in supernatant of PBMCs by HPLC. Our study results showed that the gene expression of IDO was higher in CSU patients (0.33 +/- 0.27) compare to healthy individuals (0.31 +/- 0.6, p=0.02). Amazing, the activity of IDO (KYN/Trp) was decreased in CSU patients (322.5 +/- 432.3) contrast of healthy ones (685.9 +/- 531.7, p=0.02). Previous studies documented the impaired of IDO gene expression in CSU patients, however in the present study we observed a decrease activity of IDO in CSU patients which might suggest the function of this factor is impaired in CSU patients