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Objective:To investigate the expression and clinical significance of neutrophil myeloperoxidase (MPO) in patients with MPO-antibody associated vasculitis (AAV).Methods:Thirty-six newly diagnosed MPO-AAV patients who were hospitalized in the First Affiliated Hospital, Anhui Medical University from July 2018 to June 2021 were enrolled,and 36 age and sex matched healthy subjects were selected as controls. Neutrophil MPO level was detected by flow cytometry (FCM) and MPO mRNA was tested by real time quantitative polymerase chain reaction (RT-qPCR) in all subjects. Serum complement fragment C5 (C5a) and MPO in both groups and serum MPO-anti-antineutrophilic cytoplasmic antibody(ANCA) in MPO-AAV group were measured by enzyme linked immunosorbent assay (ELISA), while the disease activity was evaluated by Birmingham vasculitis activity score-V3 (BVAS-V3).Results:Compared with the heathy control group, the expression of MPO mRNA in neutrophils, serum MPO and complement C5a in MPO-AAV group were significantly higher[MPO mRNA:30.2±11.5 vs. 1.9±0.6, P<0.001;MPO:(112.0±68.7) IU/L vs. (87.4±22.9) IU/L, P=0.01; C5a:(187.3±90.3) ng/ml vs. (107.3±31.1) ng/ml, P<0.001; respectively], while the mean fluorescence intensity (MFI) of MPO in neutrophils were significantly lower [ 1 343.3±723.4 vs. 2 868.0±1 136.5, P<0.001]. In MPO-AAV group, the expression of neutrophil MPO mRNA was positively correlated with serum MPO-ANCA and MPO levels ( r=0.537, P=0.001 and r=0.358, P=0.032; respectively). Multiple regression analysis suggested that neutrophil MPO mRNA expression was positively correlated with serum MPO-ANCA level ( β=0.695, P=0.006); neutrophil MPO level was negatively correlated with serum MPO-ANCA, MPO and complement C5a levels ( r=-0.335, P=0.046; r=-0.372, P=0.026; r=-0.577, P<0.001; respectively). Further, neutrophil MPO level was negatively correlated with serum complement C5a level ( β=-0.374, P=0.043). BVAS-V3 was positively correlated with MPO mRNA expression in neutrophils, serum MPO-ANCA, MPO and complement C5a ( r=0.598, P<0.001; r=0.599, P<0.001; r=0.537, P=0.001; r=0.415, P=0.012; respectively) and negatively correlated with MPO level in neutrophils ( r=-0.342, P=0.041). In multiple regression analysis it suggested that BVAS-V3 was positively correlated with MPO mRNA expression in neutrophils ( β=0.511, P=0.002). Conclusion:In MPO-AAV patients, MPO synthesis and release in neutrophils are both significantly increased, which might be influenced by serum MPO-ANCA and C5a, respectively. Furthermore, MPO synthesis activity in neutrophils is an independent factor related to disease activity.
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Objective To investigate the change of circulating follicular helper T cells (cTfh) in patients with anti-neutrophil cytoplasmic myeloperoxidase antibody-associated vasculitis (MPO-AAV), and to analyze the relationship between cTfh and disease activity. Methods Thirty-eight untreated MPO-AAV patients (patient group) and thirty-eight healthy volunteers (control group) were enrolled in this study. cTfh and membrane expression of inducible co-stimulator(ICOS)and programmed cell death protein 1(PD-1) were detected by flow cytometry (FCM). Serum anti-neutrophil cytoplasmic myeloperoxidase antibody (MPO-ANCA) was measured by ELISA. Disease activity was evaluated by Birmingham vasculitis activity score (BVAS). Results Compared with those in control group, the proportions of cTfh, ICOS+Tfh and PD-1+Tfh cells in patient group were significantly higher [(25.9±3.8)％vs. (21.0±5.3)％, P<0.001;(1.8±0.8)％vs. (0.8±0.5)％, P<0.001 and (10.2±2.8)％vs. (8.2±2.2)％, P=0.001, respectively]. Meanwhile, the expression of ICOS and PD-1 on cTfh in patient group was markedly more intensive (59.6±10.0 vs.49.2±6.9, P<0.001 and 532.6±104.2 vs. 485.1±73.4, P=0.025, respectively). In patient group, the proportion of cTfh was positively correlated with the ratio of ICOS+Tfh, the expression of ICOS, the level of MPO-ANCA and BVAS (r=0.407, P=0.011; r=0.705, P<0.001; r=0.737, P<0.001 and r=0.663, P<0.001, respectively). The expression intensity of ICOS on cTfh was positively associated with ICOS+Tfh ratio, serum MPO-ANCA and BVAS (r=0.388, P=0.016; r=0.645, P<0.001 and r=0.653, P<0.001, respectively). Nevertheless, the expression of PD-1 on cTfh was only positively correlated with the ratio of PD-1+Tfh (r=0.473, P=0.003). Conclusions Enhanced cTfh in patients with MPO-AAV might produce MPO-ANCA, which is related to the aggravation of MPO-AAV. Thus, cTfh and its ICOS could be potentially targeted for the treatment of MPO-AAV.
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Objective To investigate the expression of CD55 and myeloperoxidase (MPO) on neutrophils in patients with MPO-specific anti-neutrophil cytoplasmic antibody associated vasculitis(MPO-AAV), and analyze the relationship between the expression and clinical manifestation.Methods Forty untreated patients with active MPO-AAV (patient group) and 30 healthy volunteers (control group) were enrolled in this study.The CD55 on neutrophils and both membrane and cytoplasmic MPO were detected by flow cytometry.Serum fragment-from the activated complement factor B(Ba) and MPO were measured by ELISA.The clinical activity of vasculitis was valued by Birmingham vasculitis activity score-version 3(BVAS-V3).The significance of laboratory data was evaluated by Spearman correlation test and multivariate linear regression analysis.Results (1)The mean fluorescence intensity(MFI) of CD55 expressed on neutrophils was significantly higher than that in control group[4 068.6±2 306.0 vs 2 999.5±1 504.9,P=0.033].Similar results of serum MPO and Ba in patient group were found compared to controls [500.0(381.0, 612.7) IU/L vs 286.9(225.5, 329.1) IU/L,P<0.001;35.2(25.2, 79.5) ng/L vs 18.0(15.0, 28.0) ng/L,P<0.001], respectively.However, MIF of cytoplasmic MPO in patients was significantly lower than that of control group(1 577.1±1 175.9 vs 3 105.3±2 323.0,P=0.003).(2) In patient group, cytoplasmic intensity of MPO was negatively associated with the serum levels of MPO(r=-0.710,P<0.001) and Ba (r=-0.589,P=0.001).Moreover, serum MPO was positively associated with serum Ba(r=0.691,P<0.001).Membrane intensity of CD55 on neutrophils was positively correlated with patient age (r=0.514, P=0.001), C reactive protein (r=0.376, P=0.018), peripheral neutrophils count (r=0.485, P=0.001) and BVAS-V3 (r=0.484, P=0.002), whereas negative correlation between membrane CD55 and disease duration was seen (r=-0.403,P=0.01).(3) The result of multiple linear regression analysis showed there was statistically significant positive correlation between MFI of CD55 expressed on neutrophils and BVAS-V3 (β=0.001,P=0.027).Conclusions In MPO-AAV,CD55 expression on neutrophils is markedly enhanced, which is one of the independent risk factors related to disease activity.It might protect neutrophils from attacking AAV, CD55 expression on neutrophils is markedly enhanced, which is one of the independent risk factors related to disease activity.It might protect neutrophils from attacking by complement alternative pathway.Activated neutrophils release more MPO and lysosome to intensify the inflammation reaction and aggravate the disease.Thus CD55 might become a new potential target for the treatment of this disease in the future.
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Objective To investigate the clinical characteristics of myeloperoxidase (MPO)-antineutrophil cytoplasmic antibody (ANCA) associated vasculitis (MPO-AAV) with pulmonary injury and the relationship between pulmonary injury and ANCA against light chain of MPO (LCMPO-ANCA).Methods A total of 195 patients with newly diagnosed primary active MPO-AAV were recruited in this prospective study.Indirect immunofiuorescence assay was used to detect peri-nuclear ANCA (p-ANCA).Immunoblotting and ELISA were used to detect myeloperoxidase-antineutrophil cytoplasmic antibody (MPO-ANCA).Clinical features of patients with both positive p-ANCA and MPO-ANCA were collected.Disease activity was evaluated by Birmingham Vasculitis Activity Score-version 3 (BVAS-V3) Recombinant light chain of MPO was used to coat substrate of LCMPO-ANCA by ELISA.The clinical characteristics of pulmonary injury and its correlation with serum levels of p-ANCA,MPO-ANCA and LCMPO-ANCA were explored.Results All 195 patients (64 male and 131 female),consisted of 191 patients (98.0％) with microscopic polyangiitis,3 patients (1.5％) with granulomatosis with polyangiitis,and 1 (0.5％) with eosinophilic granulomatosis with polyangiitis including 64 men and 131 women.Their mean age was (63.2 ±13.5) years old.The level of MPO-ANCA had a positive correlation with general BVAS-V3 (r =0.193,P =0.007) in all patients,and the level of LCMPO-ANCA was positively related with the pulmonary BVAS-V3 (r =0.228,P =0.001).As for multiple systemic damages,the incidence of lung involvement was 60.51％(118/195),which ranked second to renal involvement (71.80％,140/195).The most common pulmonary injuries represented as pulmonary infiltration of 80.51％ (95/118),pleural effusion / pleurisy of 41.53％(49/118),pulmonary nodule or cavity of 22.03％ (26/118).Compared with those without lung involvement,the patients with pulmonary injuries were older [(66.39 ± 10.70) years old vs (58.30 ±15.72) years old;t =4.277,P =0.001],had a shorter course of disease [2.00(1.00,10.50) months vs 3.00(1.00,3.50) months;t =-2.283,P=0.024],and higher scores of general BVAS-V3 (18.21 ±6.08 vs 15.18 ± 5.64;t =3.501,P =0.001).Also,in the patients with pulmonary lesions,the positive rate of LCMPO-ANCA was significantly higher (35.59％ vs 6.49％;x2 =21.569,P ＜ 0.001),and the level of LCMPO-ANCA was significantly higher (0.377 ±0.229 vs 0.285 ±0.079;t =3.399,P =0.001)than those without lung involvement.The pulmonary BVAS-V3 in the patients with LCMPO-ANCA was significantly higher than that in the patients without LCMPO-ANCA (4.34 ± 2.10 vs 2.59 ± 2.52;t =4.301,P ＜ 0.001),whereas the pulmonary BVAS-V3 was not correlated with LCMPO-ANCA (r =0.035,P =0.708) in patients with lung injuries.Conclusion Pulmonary injury was relatively common and insidious in patients with MPO-AAV.To monitor ANCA level is necessary in patients with pulmonary injury.LCMPO-ANCA might play an important role in the pathogenesis of pulmonary lesions in AAV.