[A preliminary study of the significance of autoantibodies against light chain of myeloperoxidase on pulmonary damages in myeloperoxidase-antineutrophil cytoplasmic antibody associated vasculitis].

Zhonghua nei ke za zhi [Chinese journal of internal medicine]

PubMedID: 26359012

Zhang L, Shuai Z, Hu Z, Zhang M, Chen S. [A preliminary study of the significance of autoantibodies against light chain of myeloperoxidase on pulmonary damages in myeloperoxidase-antineutrophil cytoplasmic antibody associated vasculitis]. Zhonghua Nei Ke Za Zhi. 2015;54(6):511-6.
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 immunofluorescence 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%; ?(2)=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.