The Expression Of IL-18/IL-18BP In Lupus Nephritis Patients

Objective:To investigate the role of IL-18 and IL-18BP balance in lupus nephritis and effects of immunosuppressors to the balance.Methods:25 hospitalized patients with lupus nephritis were selected in Nephrology department from March 2005 to April 2007.All patients had not accepted immunosupresssive treatment(CTX or prednisolone)at least in the past 1 month and had no urinary infection when they were samplinged.All patients accorded to the LN pathology typeⅣorⅤrecommended by ISN/RPS in 2003.Patients accepted CTX and prednisolone treatment in hospital and gaind clinical catabaty after the theropy(ESR and serum complements coming to natural level,24h urinary protein quantity＜0.5g.25 subjects whose gender and age matched with LN patients as control were from the health examination center of our hospital.Serum IL-18 and IL-18BP levels were measured using ELISA,while mRNA levels of IL-18 and IL-18BP in peripheral blood mononuclear cells were derected using reverse transcription polymerase chain reaction(RT-PCR).Furthermore,the effects of combined immunosupresssive treatment(CTX and prednisolone)on such items were also investigated.Caculated serum dissociative IL-18 level according to totle serum IL-18 and IL-18BP,then analyse the relativity between serum dissociative IL-18 level and several clinical data such as serum alexin,24hUPQ,ESR and GFR. Caculated the kidney pathology acute index(AI),systemic lupus erythematosus disease activity index(SLEDAI)and glomerulus filtration rate(GFR)with the formula from MDRD study,General clinical information,such as serum alexin,24hUPQ,ESR were measured as while. Results:1.Serum totle IL-18,IL-18BP and serum free IL-18 were higher in active lupus nephritis patients than those in controls(P＜0.01),Serum totle IL-18 level declined after immunosupresssive treatment(P＜0.01),as while as the serum IL-18BP level(P＜0.05),Serum totle IL-18 level of after treatment group were still higher than that of controls(P＜0.05),There in no difference of IL-18BP level between after treatment group and controls,Serum free IL-18 level dropped evidently after immunosupresssive treatment(P＜0.01),and the difference between after treatment group and controls has no statistically significance(P＞0.05).2.IL-18 and IL-18BP mRNA expression in PBMC also increased in lupus patients significance than in controls(P＜0.05),and both declined after immunosupresssive treatment(P＜0.05),There was no difference of IL-18 and IL-18BP mRNA between controls and after treatment group(P＞0.05).3.Serum free IL-18 level were positively correlated with activity index of LN(AI), SLEDAI,24 hour urinary protein quantity(24h UPQ),ESR and GFR(P＜0.05), negatively correlated with serum complement C3 levels.Conclusions:1.Serum totle IL-18,IL-18BP and IL-18,IL-18BP mRNA expression in PBMC of active LN patients all elevated than that in controls,while the increase extent were different between IL-18 and IL-18BP,The IL-18/IL-18BP balance was destroyed and active serum free IL-18 level elevated remarkably.2.Serum free IL-18 level was positively correlated with AI of LN patients,SLEDAI, 24hUPQ,ESR and GFR,negatively correlated with serum complement C3 levels.That indicated serum dissociative IL-18 participating in the LN occuring and evolving and also correlated with activity of disease.Serum free IL-18 level could be a denotation of pathologic and clinical activity in LN patients.3.Immunosupresssive treatment(including CTX and prednisolone)can signifcantly decrease serum totle and serum free IL-18 in LN patients,abate the IL-18/IL-18BP inbalance which aggravated the LN.