Aggregation-prone motifs in human immunoglobulin G

Area of Science:

• Biochemistry
• Immunology
• Structural Biology

Background:

• Therapeutic antibodies, including IgG subclasses, are crucial for treating diseases like cancer and arthritis.
• High-concentration, long-term storage of these antibodies leads to aggregation, reducing efficacy and potentially causing adverse immune responses.
• Identifying and mitigating antibody aggregation is critical for developing stable and safe biologic drugs.

Purpose of the Study:

• To identify aggregation-prone motifs within the constant regions of IgG antibodies.
• To engineer mutations in these motifs to enhance antibody stability.
• To determine the conservation of these motifs across different antibody subclasses and classes.

Main Methods:

• Utilized Spatial Aggregation Propensity (SAP) technology, a molecular simulation-based approach.
• Analyzed the constant regions of IgG1 antibodies to pinpoint aggregation-prone sequences.
• Introduced mutations in identified motifs and assessed the resulting antibody stability.

Main Results:

• Identified fourteen aggregation-prone motifs in IgG1 antibodies, ranging from one to seven residues.
• Some motifs involved adjacent amino acids, while others included residues distant in primary sequence but close in tertiary structure.
• Engineered mutations in these motifs significantly enhanced antibody stability.
• These aggregation-prone motifs are conserved across IgG subclasses (IgG1-IgG4) but differ in other antibody classes (IgA, IgD, IgE, IgM).

Conclusions:

• The identified aggregation-prone motifs are common to all IgG subclasses and located in the constant regions.
• Modifying these motifs offers a universal strategy to improve the stability of all IgG-based therapeutics, irrespective of their variable regions.
• This finding has significant implications for the development of more stable and effective antibody-based therapies.