Trafficking of QD‐Conjugated MPO‐ANCA in Murine Systemic Vasculitis and Glomerulonephritis Model Mice

Abstract

In systemic vasculitis, the serum level of myeloperoxidase (MPO)‐specific anti‐neutrophil cytoplasmic autoantibodies (MPO‐ANCA) is significantly elevated with the progression of disease. We have established a model of murine systemic vasculitis by administration of MPO‐ANCA and fungal mannoprotein to C57BL/6 mice. We examined the role of MPO and MPO‐ANCA in the pathogenesis of glomerulonephritis and systemic vasculitis in this model using quantum dots (QDs). We demonstrated that QD‐conjugated MPO‐ANCA (ANCA‐QD) visualized the translocation of MPO on the neutrophil membrane surface after stimulation with proinflammatory cytokines. We also observed that MPO translocation on neutrophils in both patients with rapid progressive glomerulonephritis and these model mice without any stimulation, suggesting that MPO translocation is certain to contribute to the development of glomerular lesion. In addition, blood flow on the kidney surface vessel was significantly decelerated in both SCG/Kj mice and this model, suggesting that ANCA induces the damage of blood vessel. These results indicate that MPO‐ANCA and surface‐translocated MPO on the activated neutrophils coordinately plays essential roles in the initial steps of the glomerulonephritis.

MPO-ANCA induces IL-17 production by activated neutrophils in vitro via its Fc region- and complement-dependent manner

“…According to our established murine vasculitis model mice [14], activated neutrophils contribute to renal lesions as they do in the spontaneous crescentic glomerulonephritis-forming Kinjoh mouse (SCG/Kj mouse) [15,16]. The fact that the enhanced release of MPO from neutrophils was observed in the early phase of glomerulonephritis, indicates that activated neutrophils contribute to the development of active crescentic lesions in our model mice [14].…”

Antimyeloperoxidase antibodies rapidly induce α4-integrin–dependent glomerular neutrophil adhesion

“…Hoshino et al examined in vivo accumulation of quantum dotconjugated anti-MPO in mice undergoing a model of vasculitis. 22 They found substantial tissue deposition of anti-MPO, although much of the anti-MPO was not cell associated, presumably representing MPO released as a result of neutrophil degranulation. MPO is also present in the serum of mice and humans, with increased levels of serum MPO associated with inflammatory conditions.…”

“…However, there is little in vivo evidence of MPO externalization in response to inflammatory mediators, and under some circumstances, anti-MPO has been shown to promote adhesion in otherwise noninflamed animals. 9,13,22 Therefore the aims of the present study were to use in vivo imaging to investigate the mechanisms whereby anti-MPO induces glomerular leukocyte adhesion, both in the presence and absence of an infection-related stimulus (ie, LPS) and to examine the effect of LPS stimulation in promoting binding of anti-MPO to neutrophils. The findings indicate that even in nonstimulated mice, anti-MPO binds to a substantial proportion of circulating neutrophils, and induces their adhesion in glomerular capillaries.…”

Mechanisms of ANCA-Mediated Leukocyte-Endothelial Cell Interactions In Vivo

“…[3][4][5] In response to cytokines such as TNF-␣, these target antigens translocate to the neutrophil surface, thereby increasing their accessibility for binding by circulating autoantibodies. 6,7 Direct evidence for ANCA pathogenicity was recently provided using a novel murine model. 8 MPO-deficient mice immunized with murine MPO generated anti-MPO IgG, which was purified and transferred into naïve wild-type mice whose leukocytes expressed MPO.…”