Sulfated Dendritic Polyglycerol Is a Potent Complement Inhibitor.

Area of Science:

• Immunology
• Polymer Chemistry
• Biochemistry

Background:

• The complement system is crucial for innate immunity but its dysregulation causes disease.
• Heparin regulates complement but has limiting anticoagulative side effects.
• Dendritic polyglycerol sulfate (dPGS) is a synthetic heparin analogue.

Purpose of the Study:

• To comprehensively analyze dPGS effects on all three complement pathways (classical, alternative, lectin).
• To investigate dPGS interactions at different proteolytic cascade levels.
• To identify specific complement targets of dPGS.

Main Methods:

• Enzyme-linked immunosorbent assay (ELISA) to measure C3a and C5a levels.
• Surface plasmon resonance (SPR) to determine binding affinities.
• Determination of half-maximal inhibitory concentration (IC50) values for complement pathways.

Main Results:

• dPGS demonstrated varying IC50 values across pathways: lectin (60 nM) < classical (300 nM) < alternative (900 nM).
• dPGS dose-dependently reduced C3a and C5a generation.
• dPGS bound C1q, C3a, and C5a with nanomolar affinities, identifying novel targets.

Conclusions:

• dPGS effectively inhibits all three complement pathways.
• dPGS targets key complement components including C1q, C3a, and C5a.
• dPGS is a promising synthetic therapeutic candidate for complement-mediated diseases.