Oxidation-specific epitopes are dominant targets of innate natural antibodies in mice and humans
Meng-Yun Chou, … , Joseph L. Witztum, Christoph J. Binder
Meng-Yun Chou, … , Joseph L. Witztum, Christoph J. Binder
Published April 13, 2009
Citation Information: J Clin Invest. 2009;119(5):1335-1349. https://doi.org/10.1172/JCI36800.
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Research Article Cardiology

Oxidation-specific epitopes are dominant targets of innate natural antibodies in mice and humans

Abstract

Atherosclerosis is a chronic inflammatory disease characterized by the accumulation of oxidized lipoproteins and apoptotic cells. Adaptive immune responses to various oxidation-specific epitopes play an important role in atherogenesis. However, accumulating evidence suggests that these epitopes are also recognized by innate receptors, such as scavenger receptors on macrophages, and plasma proteins, such as C-reactive protein (CRP). Here, we provide multiple lines of evidence that oxidation-specific epitopes constitute a dominant, previously unrecognized target of natural Abs (NAbs) in both mice and humans. Using reconstituted mice expressing solely IgM NAbs, we have shown that approximately 30% of all NAbs bound to model oxidation-specific epitopes, as well as to atherosclerotic lesions and apoptotic cells. Because oxidative processes are ubiquitous, we hypothesized that these epitopes exert selective pressure to expand NAbs, which in turn play an important role in mediating homeostatic functions consequent to inflammation and cell death, as demonstrated by their ability to facilitate apoptotic cell clearance. These findings provide novel insights into the functions of NAbs in mediating host homeostasis and into their roles in health and diseases, such as chronic inflammatory diseases and atherosclerosis.

Authors

Meng-Yun Chou, Linda Fogelstrand, Karsten Hartvigsen, Lotte F. Hansen, Douglas Woelkers, Peter X. Shaw, Jeomil Choi, Thomas Perkmann, Fredrik Bäckhed, Yury I. Miller, Sohvi Hörkkö, Maripat Corr, Joseph L. Witztum, Christoph J. Binder

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Figure 2

In vitro stimulation of B-1 cells induces increased natural IgM Ab titers to oxidation-specific antigens.

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In vitro stimulation of B-1 cells induces increased natural IgM Ab titer...
(A) Purified B-1 cells were cultured in 24-well plates in triplicate at a cell density of 1 × 106 cells per well in 500 μl culture medium. Cells were stimulated with IL-5 (50 ng/ml), KdO2-Lipid A (100 ng/ml), or TLR2 agonists (a combination of Pam3CSK4 [300 ng/ml] and FSL-1 [1 μg/ml]) and incubated at 37°C for 7 days. Control B-1 cells were cultured in medium alone. Cell culture supernatants were harvested after 7 days and IgM Ab titers analyzed by ELISA at 1:45 dilution. Results were normalized to cell number recovered after 7 days. Values are mean and SEM. Data are from 1 experiment representative of 3. *P < 0.05, **P < 0.01, ***P < 0.002 compared with α1,3-dextran (repeated-measures ANOVA with Tukey-Kramer multiple comparison test). (B) Natural IgM Abs produced in vitro show specificity to MDA-LDL and CuOx-LDL. For competition immunoassay, supernatants from purified B-1 cell cultures stimulated with KdO2-Lipid A (100 ng/ml) or IL-5 (50 ng/ml) were diluted to 1:20 and incubated in the presence of the indicated concentrations of competitors (Competitor conc.) overnight. After incubation, IgM binding to MDA-LDL and CuOx-LDL was tested by ELISA. Data are the mean of triplicate determinations, expressed as ratio of IgM binding to MDA-LDL or CuOx-LDL in the presence or absence of competitor (B/B0). Data are from 1 experiment representative of 3.