To identify specific antigens against AECA, biotinylated Rapamycin molecular weight CSPs were incubated with sera from LN patients with high titers of IgG-AECA, immunoprecipitated with immobilized protein G followed by immobilized avidin, and blotted with NeutrAvidin. A 150-kDa protein band that shifted to a 55-kDa protein band under reducing conditions was detected in
patients with LN, but not in HC. Conclusion: IgA-AECA was observed to be associated with pathological activity in LN. These EC membrane components recognized by AECA may be linked with the pathogenesis of LN. NAKAZAWA DAIGO1, SHIDA HARUKI1, TOMARU UTANO2, YOSHIDA MASAHARU3, NISHIO SAORI1, ATSUMI TATSUYA1, ISHIZU AKIHIRO4 1Department of Internal Medicine II, Hokkaido University Graduate School of Medicine; 2Department of Pathology, Hokkaido University Graduate School of Medicine; 3Renal Unit of Internal Medicine, Hachioji Medical Center, Tokyo Medical University; 4Faculty of Health Sciences, Hokkaido University Introduction: MPO-ANCA-associated vasculitis (MPO-AAV) is closely related to neutrophil extracellular traps (NETs). The aim of this study is to elucidate the enhanced formation and disordered regulation of NETs in patients with MPO-AAV.
Methods: Patients enrolled in this study included 38 MPO-AAV and 23 SLE patients diagnosed and MK 2206 treated in Hokkaido University Hospital. NETs induction rate was evaluated by reaction of patient-IgG with healthy neutrophils primed by TNF-α. Furthermore, to analyze the mechanism of NETs induction by patient-IgG, ANCA
affinity was determined by the competitive inhibitory ELISA method. DNase I and NETs degradation abilities were evaluated by ELISA and the incubation of patients’ serum with phorbol CYTH4 myristate acetate-induced NETs, respectively. Results: MPO-AAV patient-IgG induced NETs. The induction rate was 16.6 ± 9.7% and significantly higher than those of SLE patients (7.0 ± 3.5%) and healthy controls (3.2 ± 1.4%). Moreover, the NETs induction rate was correlated with vasculitis activity and ANCA affinity. On the other hand, activity of DNase I, the important regulator of NETs in the serum, was generally low in MPO-AAV patients and majority of them showed impaired degradation of NETs. Furthermore, the impaired degradation of NETs in some MPO-AAV patients was improved by removal of IgG and the presence of anti-NETs antibodies, which could interfere with the degradation of NETs by DNase I, were demonstrated. Conclusion: These findings clearly demonstrated that the feature of MPO-AAV serum could cause the excessive formation and persistence of NETs. Since such dysregulation of NETs could induce NETs producers, including MPO-ANCA, and NETs degradation inhibitors, including anti-NETs antibodies, it is considered that a vicious cycle through NETs and MPO-ANCA, namely “NETs-ANCA vicious cycle,” is critically involved in the pathogenesis of MPO-AAV.