TY - JOUR
T1 - Synthetic Oligodeoxynucleotide CpG Motifs Activate Human Complement through Their Backbone Structure and Induce Complement-Dependent Cytokine Release
AU - de Boer, Eline
AU - Sokolova, Marina
AU - Quach, Huy Q
AU - McAdam, Karin E
AU - Götz, Maximilian P
AU - Chaban, Viktoriia
AU - Vaage, Jarle
AU - Fageräng, Beatrice
AU - Woodruff, Trent M
AU - Garred, Peter
AU - Nilsson, Per H
AU - Mollnes, Tom E
AU - Pischke, Søren E
N1 - Copyright © 2022 by The American Association of Immunologists, Inc.
PY - 2022/11/1
Y1 - 2022/11/1
N2 - Bacterial and mitochondrial DNA, sharing an evolutionary origin, act as danger-associated molecular patterns in infectious and sterile inflammation. They both contain immunomodulatory CpG motifs. Interactions between CpG motifs and the complement system are sparsely described, and mechanisms of complement activation by CpG remain unclear. Lepirudin-anticoagulated human whole blood and plasma were incubated with increasing concentrations of three classes of synthetic CpGs: CpG-A, -B, and -C oligodeoxynucleotides and their GpC sequence controls. Complement activation products were analyzed by immunoassays. Cytokine levels were determined via 27-plex beads-based immunoassay, and CpG interactions with individual complement proteins were evaluated using magnetic beads coated with CpG-B. In whole blood and plasma, CpG-B and CpG-C (p < 0.05 for both), but not CpG-A (p > 0.8 for all), led to time- and dose-dependent increase of soluble C5b-9, the alternative complement convertase C3bBbP, and the C3 cleavage product C3bc. GpC-A, -B, and -C changed soluble fluid-phase C5b-9, C3bBbP, and C3bc to the same extent as CpG-A, -B, and -C, indicating a DNA backbone-dependent effect. Dose-dependent CpG-B binding was found to C1q (r = 0.83; p = 0.006) and factor H (r = 0.93; p < 0.001). The stimulatory complement effect was partly preserved in C2-deficient plasma and completely preserved in MASP-2-deficient serum. CpG-B increased levels of IL-1β, IL-2, IL-6, IL-8, MCP-1, and TNF in whole blood, which were completely abolished by inhibition of C5 and C5aR1 (p < 0.05 for all). In conclusion, synthetic analogs of bacterial and mitochondrial DNA activate the complement system via the DNA backbone. We suggest that CpG-B interacts directly with classical and alternative pathway components, resulting in complement-C5aR1-dependent cytokine release.
AB - Bacterial and mitochondrial DNA, sharing an evolutionary origin, act as danger-associated molecular patterns in infectious and sterile inflammation. They both contain immunomodulatory CpG motifs. Interactions between CpG motifs and the complement system are sparsely described, and mechanisms of complement activation by CpG remain unclear. Lepirudin-anticoagulated human whole blood and plasma were incubated with increasing concentrations of three classes of synthetic CpGs: CpG-A, -B, and -C oligodeoxynucleotides and their GpC sequence controls. Complement activation products were analyzed by immunoassays. Cytokine levels were determined via 27-plex beads-based immunoassay, and CpG interactions with individual complement proteins were evaluated using magnetic beads coated with CpG-B. In whole blood and plasma, CpG-B and CpG-C (p < 0.05 for both), but not CpG-A (p > 0.8 for all), led to time- and dose-dependent increase of soluble C5b-9, the alternative complement convertase C3bBbP, and the C3 cleavage product C3bc. GpC-A, -B, and -C changed soluble fluid-phase C5b-9, C3bBbP, and C3bc to the same extent as CpG-A, -B, and -C, indicating a DNA backbone-dependent effect. Dose-dependent CpG-B binding was found to C1q (r = 0.83; p = 0.006) and factor H (r = 0.93; p < 0.001). The stimulatory complement effect was partly preserved in C2-deficient plasma and completely preserved in MASP-2-deficient serum. CpG-B increased levels of IL-1β, IL-2, IL-6, IL-8, MCP-1, and TNF in whole blood, which were completely abolished by inhibition of C5 and C5aR1 (p < 0.05 for all). In conclusion, synthetic analogs of bacterial and mitochondrial DNA activate the complement system via the DNA backbone. We suggest that CpG-B interacts directly with classical and alternative pathway components, resulting in complement-C5aR1-dependent cytokine release.
KW - Humans
KW - Complement Activation
KW - Complement C1q
KW - Complement Factor H
KW - Complement Membrane Attack Complex/pharmacology
KW - Complement System Proteins/metabolism
KW - Cytokines/metabolism
KW - DNA, Mitochondrial
KW - Interleukin-2/pharmacology
KW - Interleukin-6/pharmacology
KW - Interleukin-8
KW - Mannose-Binding Protein-Associated Serine Proteases
KW - Oligodeoxyribonucleotides/pharmacology
KW - CpG Islands
UR - http://www.scopus.com/inward/record.url?scp=85140275286&partnerID=8YFLogxK
U2 - 10.4049/jimmunol.2101191
DO - 10.4049/jimmunol.2101191
M3 - Journal article
C2 - 36104112
VL - 209
SP - 1760
EP - 1767
JO - Journal of Immunology
JF - Journal of Immunology
SN - 0022-1767
IS - 9
ER -