Magnetic bead based assays for complement component C5

Area of Science:

• Biochemistry
• Immunology
• Assay Development

Background:

• The complement system is crucial for innate immunity.
• Understanding complement component C5 interactions is vital for therapeutic targeting.
• Existing methods for studying C5 interactions have limitations.

Purpose of the Study:

• To develop novel magnetic agarose bead-based assays for measuring complement component C5 interactions.
• To assess the inhibitory effects of natural products on C5 interactions with C3b and C7 Factor I Modules (FIMs).

Main Methods:

• Coupling C3b to magnetic agarose beads via the alternative pathway C3 convertase, forming a covalent ester bond.
• Utilizing nickel ion-charged magnetic agarose to capture recombinant C7 FIMs with an oligo-histidine linker.
• Detecting interactions using peroxidase-coupled C5.
• Screening natural products for inhibitory activity against C5 interactions.

Main Results:

• Developed two robust magnetic bead assays suitable for screening.
• Fucoidan, beta-glucans, and dextran sulfate inhibited C3b-C5 interaction.
• Rosmarinic acid showed no measurable effect on C3b-C5 interaction.
• Only beta-glucans from specific macrofungi interfered with C5-C7 FIMs interaction.

Conclusions:

• The novel assays provide a reliable platform for studying complement C5 interactions.
• Natural products, particularly beta-glucans, exhibit inhibitory potential against specific complement pathways.
• These findings contribute to the development of complement-modulating therapeutics.