A Study Of Arachidonic Acid Metabolites In Psoriasis And Eczema Patients

Background:1. Arachidonic acid (AA)is one of the essential fatty acids in human body, in recent years, reseachers began to pay more and more attention to the important roles of AA and its metabolites in the pathogenesis of various diseases. AA metabolize mainly by enzymes of Cycloxygenase(COX) and Lipoxygenase (LO), Leukotrienes(LTs) is 5-lipoxygenase way metabolites of AA, which is a variety of inflammatory mediators, participate inflammatory reactions in many diseases. Psoriasis is a commom disease in dermatology, the cause of which is complex, and the pathogenesis of which has been and still will be the research focus in dermatology field. Normal skin local injection of LTB4 can produce psoriasis-like skin lesions, the expression of LTs and it's receptors are enhanced, these studies indicate that LTs be metabolized abnormally in the patients with psoriasis. But how the LTs to participate in the pathogenesis of psoriasis, and whether LTs play important role in psoriasis inflammatory reaction need further study.2. In literature searching and reading we find that, although there are metabolic abnormalities of AA in both the patients with psoriasis and eczema, in clinical research, leukotriene resistant drugs and prostaglandins synthetic inhibitors are effective in treatment of eczema patients, Therapeutic effect of leukotriene resistant drugs in treatment of patients with psoriasis is not clear, even there are reports that prostaglandins synthetic inhibitors can worsen lesions of patients with psoriasis Zhong hua's research shows that expression of cysteinyl leukotriene receptors (CysLTRs) in both patients with psoriasis and eczema are enhanced,but the expression in psoriasis patients is more strengthen than in eczema patients. All of these indicate that character of AA metabolism may be different from eczema, and which need us to make further reseach.Objective:1. To explore the correlation between LTs and inflammation and investigate the significant role of LTs in the pathogenesis of psoriasis。2. To compare the similarities and differences of AA metabolic characteristics in skin lesions of psoriasis and eczema patients.Methods:1. Enzyme-Linked Immunosorbent Assay (ELISA) method was adopted to detect the serum, urine and rash levels of LTB4,LTE4 and the serum and rash levels of IL-8,TNF-a in 32 psoriasis patients, compared with 20 healthy controllers.2.10 progressive stage Ps patients,10 stable stage Ps patients,10 regressive stage Ps patients and 10 acute Ec patients,10 subacute Ec patients,10 chronic Ec patients and 10 controllers were involved in this study. ELIS A method was used to detect levels of LTB4, LTE4, TXB2,6-k-PGF1αand PGE2 in skin lesions of the patients and the normal skin of the controllers.Results:1. Levels of serum and rash IL-8,TNF-a and serum, urine and rash LTE4 in psoriasis patients were obviously higher (P<0.01, respectively) than that in the healthy volunteers, levels of rash LTB4 was obviously increased(P<0.01), but LTB4 levels in serum and urine were not significantly increased(P>0.05, respectively). We saw significant positive correlations both between rash LTB4,LTE4,IL-8 and PASI and between rash IL-8,TNF-a and LTB4.2. In psoriasis patients,the descending order of levels of LTB4 and LTE4 was progressive stage group> stable stage group> regressive stage group> control group.Level of TXB2 was slightly increased (P<0.05)in progressive stage group.In Ec patients, the descending order of levels of LTE4 and PGE2 was acute group> subacute group> chronic group> control group. Levels of LTB4, TXB2,6-k-PGF1αin acute and subacute Ec patients were obviously higher than in the control group. Levels of LTB4, TXB2,6-k-PGF1αin chronic Ec patients were not obviously increased.Conclusion:1. LTs play important role in the pathogenesis of psoriasis by participating local inflammatory reactions.2. The enhanced 5-Lipoxygenase (5-LO) metablic pathway is the main imbalance of AA metabolism in psoriasis patients. But in eczema patients,both the 5-Lipoxygenase and Cycloxygenase(COX) metablic pathways of AA metabolism are enhanced.