A preliminary study of the significance of autoantibodies against light chain of myeloperoxidase on pulmonary damages in myeloperoxidase-antineutrophil cytoplasmic antibody associated vasculitis / 中华内科杂志

ABSTRACT

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.