| Objective To investigate the changes of synthesis,expression,and release of neutrophil myeloperoxidase(MPO)in the pathogenesis of MPO-antineutrophil cytoplasmic antibody(MPO-ANCA)associated vesculitis(MPO-AAV),and to analyze the clinical significance of the changes.Methods A total of 50 untreated first-onset patients with active MPO-AAV were involved in this study as the disease group and their clinical documens including age,disease duration,organ damage and Birmingham vasculitis activity score(BVAS)were also recorded.50 healthy patients with age and gender matching with patients were randomly selected in the same period from the health check center of our hospital as the control group.Enzyme linked immunosorbent assay(ELISA)was used to detect the levels of MPO-ANCA,Complement C5 a fragment(C5a)and MPO in their peripheral blood.20 patients and 20 healthy controls were randomly selected from the disease and control group,respectively,and the level of MPO-m RNA and expression of MPO in their neutrophils was detected by RT-q PCR and FCM,respectively.All the indexes detected were compared between the disease group and the healthy control group,and the relationships between the indexes and either the disease activity and clinical damages were analyzed in disease group.Results1.In the 50 selected patients with MPO-AAV(disease group),45 patients were diagnosed as MPA and the rest 5 as GPA.They were composed of 22 males and 28 females,and their ages ranged from 36 to 90(64.46 ± 12.84)years old.Disease duration ranged from 0.6 to 120[3(0.71,113.40)] months.Among the main clinical organs damaged in the patients,the lung and kidney were the most damaged,with 42% of the lung damaged(21/50)and 96% of the kidney damaged(48/50).BVAS scores ranged from 6 to 33(17.04±5.11).In the control group,there were 23 males and 27 females,and their average age was(63.50±15.82)years old.Neither the gender ratio nor the age difference between the disease and healthy group was statistically significant(c2=0.04,P=0.841;t=-1.190,P=0.239,respectively).Twenty patients composed of 9 males and 11 females,were randomly selected from 50 patients.Their age,disease duration and BVAS scores was(58.3±12.1)years old,3(1,100)months and(16.11±4.96),respectively.There were no statistical differences between the 2 disease groups concerning age,gender ratio,disease course and BVAS score(t=-0.945,P=0.348;c2=0.006,P=0.939;Z=-0.502,P=0.615 and t=-0.753,P=0.418,respectively).Twenty healthy patients were also randomly selected from the healthy control group,in which there were 7 males and 13 females,with an average age of(60.75±16.20)years.Both the gender ratio and ages between the two healthy control groups were not significantly different(c2=0.418,P=0.518;t=-0.392,P=0.698,respectively).2.ELISA results showed,the levels of MPO,MPO-ANCA and C5 a in the disease group were significantly higher than that in the control group(572.13±386.87 vs 294.87±80.05,t=3.139,P=0.003;0.53±0.12 vs 0.24±0.082,t=10.591,P<0.001 and 398.37±71.5 vs 281.78±45.70,t=7.519,P<0.001 restpectivly).RT-q PCR results indicated that the level of MPO-m RNA in neutrophils of the disease group was significantly higher than that in the control group(22.60±7.78 vs 1.40±1.23,t=12.028,P<0.001).FCM results showed that,compared with the control group,the expression of MPO in neutrophils of disease group was significantly decreased(421.71±320.34 vs3249.80±976.83,t=-12.303,P<0.001).3.In the disease group,MPO-m RNA synthesis in neutrophils was positively correlated with the level of serum MPO and MPO-ANCA(r=0.558,P=0.013 and r=0.473,P=0.024 respectively).The extracellular MPO level was negatively correlated with intracellular MPO level(r=-0.546,P=0.016),while the extracellular MPO level was positively correlated with MPO-ANCA and C5 a levels(r=0.316,P=0.005;r=0.308,P=0.034,respectively),and there was no statistically significantly relationship between MPO-ANCA and C5 a level in peripheral blood(r=1.95,P=0.328).4.In the disease group,the levels of MPO-m RNA,MPO-ANCA and extracellular MPO were positively correlated with BVAS,respectively(r=0.455,P=0.011;r=0.361,P=0.037;r=0.326,P=0.034,respectively)and C5 a had no significant relations with BVAS(r= 0.09,P=0.971).5.In the disease group,MPO-m RNA level in neutrophils was positively correlated with ESR,CRP and neutrophils counts(r=0.271,P<0.001;r=0.342,P=0.026;r=0.314,P<0.001,respectively),and had no remarkble relationship with age and disease course(r=1.12,P=0.136;r=0.361,P=0.067,respectively).Conclusion 1.Elevated MPO levels in peripheral blood of patients with MPO-AAV indicatd MPO released from neutrophils was increased.2.Compared to control group,MPO expression in neutrophil of MPO-AAV patie nts was significantly decreased,while MPO-m RNA synthesis and MPO level in peripheral blood were obviously increased,suggesting that MPO continuously syn thesized in and released from neutrophil by degranulation might play a very imp ortant role in the pathogenesis of MPO-AAV.3.MPO-ANCA might activate alternative complement pathway to produced mor e C5 a by promoting neutrophil to excrete azurophilic granules containing MPO,which then induced a vicious circle to activate more neutrophil to take part in MPO-AAV pathogenesis.4.MPO-ANCA might lead to clinical damage in MPO-AAV patients by promot ing the synthesis and release of MPO from peripheral neutrophils. |
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