The Role And Significant Of Interleukin-18 And Neutrophil To Lymphocyte Ratio In ANCA-associated Vasculitis

Part 1 The serum level and significance of interleukin-18 in patients with ANCA-associated vasculitisBackgroundAnti-neutrophil cytoplasmic antibody(ANCA)-associated vasculitis(AAV)is a multisystem autoimmune syndrome characterized by vasculitis predominantly affecting microscopic vessels and few pauci-immune.Kidney is often involved and the major pathological changes are pauci-immune crescentic glomerulonephritis and capillary tuft fibrinoid necrosis.AAV progresses quickly and can develop to end-stage renal desease without treated in time.ANCA includes cytoplasmic-ANCA(PR3-ANCA)and perinuclear-ANCA(MPO-ANCA)and lysosomal membrane protein-2(LAMP-2).It is the major serological marker to disease of AAV.However,ANCA couldn’t reflect the activity of AAV timely and accurately in AAV.It is important to explore the new biomarker to reflect the activity of AAV.Interleukin 18(IL-18)is a newly discovered pleiotropic pro-inflammatory cytokine.It is originally identified as an IFN-γ inducing factor because it can stimulate T helper 1 cells and natural killer cells to produce IFN-γ.The level of IL-18 increased in many kinds of autoimmune diseases such as type-1 diabetes,multiple sclerosis,myasthenia gravis,rheumatoid arthritis,psoriasis and systematic lupus erythematosus.It should be noted that IL-18 is important to reflect early renal injury.IL-18 is highly expressed in renal biopsies(especially in podocytes)from AAV patients.It could activate neutrophils through P38-MAPK pathway leading to hydrolase and superoxide releasing by neutrophils to damage the kidney.The serum concentration of IL-18 in active AAV patients was higher than that in inactive AAV and no significant difference exists between inactive AAV and healthy controls.However,the level of IL-18 may be different between other race and Chinese population.So we investigated the significance of serum level of IL-18 in Han race in Chinese patients with AAV.MethodsSera and clinical data were obtained from patients with AAV,mesangial proliferative glomerulonephritis(mild-Ms PGN)and healthy control(HC).The concentrations of IL-18 were measured by enzyme linked immunosorbent assay(ELISA).The correlation between the levels of serum IL-18 and the AAV activity indexs birmingham vasculitis active scoring system(BVAS),C-reaction protein(CRP),erythrocyte sedimentation rate(ESR),estimated glomerular filtration rate(e-GFR),serum creatinine(SCr)levels and 24-hour urinary protein quantity(24h-UPQ)were analyzed by pearson correlation analysis.Receiver operating characteristic curves(ROC)were conducted with the serum level of IL-18,CRP,ESR.All statistical analyses were performed using SPSS 16.0 and P< 0.05 was considered significant.Results1.27 AAV patients(male/female=19/8)were collected,the average age of which was 57.9±15.2.AAV patients were divided into two groups(active AAV group and inactive AAV group)according to the BVAS score.The level of serum creatinine,erythrocyte sedimentation rate,CRP,β2-MG,parathyroid homone(PTH)was higher in active AAV group.The level of e GFR,hemoglobin,complement C3 was lower in active AAV group.There were no difference between two groups as to other clinical datas such as sex,disease duration,urea nitrogen,uric acid and so on.2.The levels of serum IL-18 in patients with active AAV group [(183.85 ± 57.0)pg/ml] were increased significantly compared with inactive AAV group [(92.0±34.29)pg/ml,P<0.05];mild-Ms PGN group [(63.0±17.7)pg/ml,P<0.01] and HC group [(39.2±6.3)pg/ml,P<0.01].3.There were positive correlation between the serum levels of IL-18 and the index of BVAS(r=0.572,P<0.01)and ESR levels(r =0.394,P<0.05),respectively.However,there were no correlation between the levels of serum IL-18 and the levels of CRP,e-GFR,SCr and 24 h-UPQ(r=0.117,-0.25,0.29,0.20,respectively,P>0.05).4.ROC revealed that the level of serum IL-18 was superior to the level of CRP or ESR to distinguish active and inactive AAV.The area of ROC curve was 0.932(P<0.01)and the sensitivity and specificity were 90.91% and 87.5% when the cut-off point of IL-18 was 135.18 pg/ml.Conclusions1.The levels of IL-18 were elevated significantly in active AAV patients,suggesting IL-18 may be involved the pathophysiology of AAV.2.The sensitivity and specificity was high when use IL-18 to distinguish the active AAV with inactive AAV and IL-18 may become one of the new biomarker to evaluate the activity of AAV.3.The levels of IL-18 maybe as a better biomarker to reflect the activity of AAV compare with the levels of ESR and CRP.Part 2 The correlation between neutrophil to lymphocyte ratio and clinicopathologial characteristics and prognosis in ANCA-associated vasculitisBackgroundBoth neutrophils and lymphocytes play important roles in the pathogenesis of AAV.The binding of ANCA to neutrophils results in damage of endothelium and adjacent tissue through increasing the adhesion and penetration of neutrophils to the vessel wall,respiratory burst of neutrophils,releasing a large number of reactive oxygen species and enzymes by neutrophils,neutrophils extracellular traps(NETs)and the alternative complement pathway.Infiltrating T cells and B cells were detected in the kidney from AAV.It was reported that most T cells in AAV are persistently present.For example,na?ve T cells decreased and memory T cells amplicated.B cells may also play an important role in AAV pathogenesis by generating ANCA and regulating the ANCA associated immune response.Thus,neutrophils and lymphocytes play vital roles in the pathogenesis of AAV.Neutrophil to lymphocyte ratio(NLR),combining both neutrophils and lymphocytes,is a good indicator to reflect systemic inflammatory status.The higher the NLR rat io is most reflected the the heavy in inflammation.In recent years,it is demonstrated that NLR has a close relation to cardiovascular disease,cancer,diabetes,hypertension and has been proved to be an independent survival predictor of a variety of mali gnant tumors and coronary heart disease.What’s more,NLR also play an important role in autoimmune diseases such as sjogren’s syndrome,rheumatoid arthritis and systemic lupus erythematosus and multiple sclerosis.As a kind of autoimmune disease,AAV often damages kidney which is called ANCA-associated glomerulonephritis(AGN).The histopathologic classification of AAV includes four types: focal,crescentic,mixed,and sclerotic.Patients classified as focal had best survival,while patients classified as sclerotic had worst survival.However,the level of NLR in AGN patients and whether NLR is associated with AGN histopathologic classification and whether NLR affects the survival of AGN are still unknown.Our aim is to explore the level of NLR in AAV patients and whether NLR affects the survival of AAV.MethodsA total of 46 patients with AGN,from January 2010 to December 2015,confirmed by renal biopsy in xinqiao hospital and 29 gender,age matched healthy controls from health management center of Xinqiao hospital were enrolled.Clinical datas of AGN patients and healthy controls were collected and the level of NLR was compared between AAV patients and healthy controls.AAV patients was devided into low NLR group(NLR < 3.71)and high NLR group(NLR> 3.71)according to the cut-off point(median)of NLR.Then we the influence of NLR on prognosis of AGN patients and compared the differences of clinical data,laboratory data and pathological data between low NLR group and high NLR group.Results1 The level of NLR in the AGN group were significantly higher than those in healthy controls(6.284+0.881 vs.1.798+0.129,P<0.001).2.The incidence of fever,dyspnea,rapidly progressive GN was significant higher in high NLR group than that in low NLR group(P=0.014,0.007,0.032 respectively).While the incidence of Nephritic syndrome was higher in low NLR group(P=0.032).There were no significant differences in other clinical features.3.The level of e GFR appeared much lower in high NLR group than that in low NLR group(72.19 m L/min/1.73m2 vs 14.67 m L/min/1.73m2,P=0.044).While the level of leukocyte,monocyte,neutrophil,PLR and c-reactive protein was higher in higher than that in low NLR group(P=0.000,0.019,0.000,0.000,0.004 respectively).There was no significant difference about the other laboratory parameters between the two groups.4.As to the renal pathology,the percentage of normal glomerular was higher in low NLR group than that in high NLR group(P=0.034).We observed that the degree of renal interstitial infiltrating was more severe in high NLR group than that in low NLR group.There was no significant difference on other pathological parameters between two groups.We also observed the distributions of Berden classifications were similar in the two gro ups.5.The cumulative renal survival rate in high NLR group was significantly lower than that in low NLR group(41.25% vs.67.18%,Log-Rank=6.585,P=0.031)6.Cox regression analysis showed that e GFR [hazard ratio(HR)=1.109,P=0.025] and NLR(HR=0.901,P=0.028)were independent risk factors of AAV renal survival.Conclusions1.The level of NLR was higher in high NLR group than that in low NLR group.2.High level of NLR reflects the severity of AGN,and closely relates with clinical pathological characteristics.3.The cumulative renal survival rate in high NLR group were significantly lower than that in low NLR group,Through the multivariate Cox regression analysis,our data had shown that the e GFR and NLR were independent risk factors of renal survival in AGN.4.As an economic,practical,efficient,minimally invasive,repeatable inflammation marker,NLR may be as an ideal indicator to predict the prognosis of AGN patients.