Synthetic Oligodeoxynucleotide CpG Motifs Activate Human Complement through Their Backbone Structure and Induce Complement-Dependent Cytokine Release

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.

Abstract sourced from PubMed (NCBI) for the cited record. See the original publication for the authoritative version.

Bacterial and mitochondrial DNA, sharing an evolutionary origin, act as danger-associated molecular patterns in infectious and sterile inflammation.

Leech-derived molecules this paper discusses, each with a full profile in the ASH compound registry:

Узнайте, как это исследование связано с клинической практикой

More peer-reviewed studies in Разработка лекарственных препаратов.

• Novel Leech Antimicrobial Peptides — Hirunipins — Kumar et al. (2025)
• Medicinal Leech Genome Assembly — Anticoagulant Gene Catalog — Kvist et al. (2020)
• Effects of hirudotherapy on liver functions, lipid profile, and insulin sensitivity in rats with metabolic syndrome — Bilden A et al. (2026)
• HIRUDOTHERAPY IN PRESBYACUZIS PRAECOX IN CLEAN-UP WORKERS AFTER THE CHORNOBYL ACCIDENT DURING THE POST-CATASTROPHE YEARS — Zabolotnyi D, Mishchanchuk N (2019)
• [Hirudo medicinalis-leech applications in plastic and reconstructive microsurgery--a literature review] — Knobloch K et al. (2007)
• Recombinant hirudin in clinical practice: focus on lepirudin — Greinacher A, Lubenow N (2001)
• In-vitro antileishmanial potential of peptide drug hirudin — Khan H et al. (2017)
• Parenteral anticoagulants: Antithrombotic Therapy and Prevention of Thrombosis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines — Garcia DA, Baglin TP, Weitz JI, Samama MM (2012)
• Direct thrombin inhibitors — Lee CJ, Ansell JE (2011)
• Updates on Use and Monitoring of Direct Thrombin Inhibitors — Navaei A et al. (2026)

Browse all ASH-analysed research →