FcRn–Antigen Conjugates for Selective Lysosomal Antibody Clearance
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Solution Overview
Problem
Existing strategies for reducing IgG levels in the serum are not specific to particular antibodies, leading to potential immunodeficiency by depleting protective antibodies along with pathogenic ones.
Innovation Solution
A class of molecules comprising an extracellular part of the human neonatal Fc receptor (FcRn) and beta-2 microglobulin, covalently linked to a specific antigen, binds targeted antibodies in the lysosome to prevent recycling, thereby selectively depleting antigen-specific antibodies without affecting other IgGs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If existing strategies (anti-FcRn antibodies, Fc fragments, Seldegs) are used to reduce IgG levels, then IgG clearance is improved, but specificity is worsened leading to immunodeficiency
Solution Approach 1:
The invention segments the FcRn receptor into its essential functional components (FcRn extracellular domain and beta-2 microglobulin) and combines them with a specific antigen moiety. This segmentation allows the creation of a chimeric molecule that specifically targets only antigen-specific antibodies through the antigen component while the FcRn components enable Fc region binding and degradation, thereby achieving specific antibody depletion without affecting protective antibodies.
Solution Approach 2:
The antigen-specific antibody serves as an intermediary that bridges the antigen moiety and the FcRn components. The antigen moiety binds to the antigen-specific antibody's variable region, while the FcRn extracellular domain and beta-2 microglobulin bind to the antibody's Fc region, forming a ternary complex that directs the antibody to lysosomal degradation. This intermediary mechanism ensures selective clearance of only antigen-specific antibodies.
2Duration of action of stationary object
If FcRn binding affinity is increased to enhance IgG recycling protection, then IgG half-life is improved, but pH dependence is worsened
Solution Approach 1:
The invention applies local quality by using the natural pH-dependent binding characteristics of the FcRn extracellular domain and beta-2 microglobulin in the specific cellular compartment (endosome/lysosome) where pH is acidic (pH 5.0-6.0). At this acidic pH, the FcRn components maintain strong binding to the Fc region, ensuring efficient uptake and degradation of antigen-specific antibodies. In contrast, at physiological pH (7.4), binding is weak, preventing interference with normal IgG recycling. This spatially-dependent binding behavior resolves the contradiction between binding affinity and pH adaptability.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach allows for the specific clearance of targeted antibodies without interfering with the recycling of other IgGs, reducing the risk of immunodeficiency and maintaining protective antibody levels.
Implementation Method 1
the IgG/FcRn interaction is stronger at acidic endosomal pH than at extracellular physiological pH
Data Source
AI summary
The present invention relates to a new class of molecules for selective clearance of antibodies and the uses thereof for treating antibody-mediated diseases and disorders.