Anti-myeloperoxidase antibodies attenuate the monocyte response to LPS and shape macrophage development
Reena J. Popat, … , Claudia Kemper, Michael G. Robson
Reena J. Popat, … , Claudia Kemper, Michael G. Robson
Published January 26, 2017
Citation Information: JCI Insight. ;2(2):e87379. https://doi.org/10.1172/jci.insight.87379.
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Research Article Inflammation

Anti-myeloperoxidase antibodies attenuate the monocyte response to LPS and shape macrophage development

Abstract

Anti-neutrophil cytoplasmic antibody (ANCA) vasculitis is characterized by the presence of autoantibodies to myeloperoxidase and proteinase-3, which bind monocytes in addition to neutrophils. While a pathological effect on neutrophils is acknowledged, the impact of ANCA on monocyte function is less well understood. Using IgG from patients we investigated the effect of these autoantibodies on monocytes and found that anti-myeloperoxidase antibodies (MPO-ANCA) reduced both IL-10 and IL-6 secretion in response to LPS. This reduction in IL-10 and IL-6 depended on Fc receptors and enzymatic myeloperoxidase and was accompanied by a significant reduction in TLR-driven signaling pathways. Aligning with changes in TLR signals, oxidized phospholipids, which function as TLR4 antagonists, were increased in monocytes in the presence of MPO-ANCA. We further observed that MPO-ANCA increased monocyte survival and differentiation to macrophages by stimulating CSF-1 production. However, this was independent of myeloperoxidase enzymatic activity and TLR signaling. Macrophages differentiated in the presence of MPO-ANCA secreted more TGF-β and further promoted the development of IL-10– and TGF-β–secreting CD4+ T cells. Thus, MPO-ANCA may promote inflammation by reducing the secretion of antiinflammatory IL-10 from monocytes, and MPO-ANCA can alter the development of macrophages and T cells to potentially promote fibrosis.

Authors

Reena J. Popat, Seran Hakki, Alpesh Thakker, Alice M. Coughlan, Julie Watson, Mark A. Little, Corinne M. Spickett, Paul Lavender, Behdad Afzali, Claudia Kemper, Michael G. Robson

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Figure 7

Macrophages differentiated in the presence of MPO-ANCA express increased CD206, secrete TGF-β, and promote CD4+ T cell production of IL-10 and TGF-β.

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Macrophages differentiated in the presence of MPO-ANCA express increased...
(A) TGF-β in the supernatants of macrophages that developed from monocytes after 6 days in culture with 10% human type AB serum and anti-myeloperoxidase antibodies (MPO-ANCA) (n = 3) or control IgG (n = 3). Experiments were performed with monocytes from 2 donors. (B) Expression of CD206 and CD80 on macrophages that developed after 6 days in culture with 10% AB serum with control IgG (n = 2) or MPO-ANCA (n = 2). Experiments were performed with monocytes from 2 healthy donors with histograms shown for 1 donor. CD206 median fluorescence intensities (MFIs) for donor 1 were 3,182 and 3,227 (MPO-ANCA) and 2,202 and 2,624 (Control IgG). CD206 MFIs for donor 2 were 33,466 and 33,287 (MPO-ANCA) and 20,565 and 8,357 (Control IgG). CD80 MFIs for donor 1 were 222 and 228 (MPO-ANCA) and 419 and 465 (Control IgG). CD80 MFIs for donor 2 were 1,113 and 1,213 (MPO-ANCA) and 2,413 and 3,806 (Control IgG). (C) Peripheral blood CD4+ T cells were stimulated for 3 and 5 days with anti-CD3 and anti-CD28 in the presence or absence of added supernatant from monocyte/macrophages cultured with no added IgG (n = 1), control IgG (n = 3), or MPO-ANCA (n = 3). The ratio of IL-10 to IFN-γ is indicated, with TGF-β concentrations. Concentrations of IL-10, IFN-γ, and IL-17A are shown in Supplemental Figure 8. Experiments were performed with CD4+ T cells from 2 donors, each using macrophage supernatants from different experiments. *P < 0.05, **P < 0.01, ***P < 0.001 by 2-tailed Student’s t test. Error bars represent mean ± SEM. For a given monocyte donor, n is the number of IgG preparations from different individuals. They are not technical replicates or repeated measures of the same IgG samples. SN, supernatant.