Soluble C3b-Binding Polypeptides for Bruch’s Membrane Penetration
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Solution Overview
Problem
Current treatments for complement-related diseases, particularly age-related macular degeneration (AMD), are ineffective as they cannot reach the target areas within the eye, such as Bruch's membrane and the choriocapillaris, due to the inability of complement regulating antibodies to traverse these structures effectively.
Innovation Solution
Development of soluble, truncated polypeptides derived from the FI cofactor CR1 that can bind to C3b, allowing for efficient FI-mediated C3b cleavage and complement regulation, capable of passing through Bruch's membrane to target areas of complement over-activation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If complement regulating antibodies are used to treat AMD, then complement regulation is improved, but the ability to reach target areas (Bruch's membrane and choriocapillaris) deteriorates
Solution Approach 1:
The invention segments the CR1 protein into smaller soluble polypeptide fragments (such as CCP domains 8-10 and 15-17) that retain C3b binding capability. These smaller fragments can traverse Bruch's membrane and reach the choriocapillaris effectively, unlike full-length antibodies, while still providing complement regulation function.
Solution Approach 2:
The invention extracts the essential C3b binding domains (CCP domains) from the full-length CR1 protein. These extracted domains are sufficient for binding C3b and regulating complement activation, eliminating the need for large antibody molecules that cannot reach the target tissue.
2Reliability
If full-length CR1 or antibodies are used, then complement regulation function is improved, but penetration through Bruch's membrane deteriorates
Solution Approach 1:
The CR1 protein is divided into functional segments (CCP domains) that can independently bind C3b. The invention uses specific combinations of these segments (e.g., domains 8-10 and 15-17) to create molecules small enough to penetrate Bruch's membrane while retaining full regulatory function.
Solution Approach 2:
The invention changes the size parameter of the therapeutic molecule by using truncated CR1 polypeptides with molecular weights significantly lower than full-length CR1 or antibodies. This size reduction enables penetration through the physical barrier of BrM while maintaining the biochemical function of complement regulation.
3Ease of operation
If small polypeptide fragments are used to improve penetration, then ability to reach target areas is improved, but complement regulation effectiveness may deteriorate
Solution Approach 1:
The invention places C3b binding domains (CCP domains) at specific locations within the polypeptide structure. These localized functional domains ensure high-affinity C3b binding and effective complement regulation, while the overall polypeptide size remains small for penetration. The local concentration of regulatory function is optimized rather than diluted.
Solution Approach 2:
The invention creates composite polypeptide structures combining multiple CCP domains (e.g., domains 8-10 and 15-17 from different LHR regions) into a single functional unit. This composite structure enhances C3b binding capability and complement regulation effectiveness while maintaining a size suitable for penetrating Bruch's membrane.
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
The polypeptides provide targeted therapy to areas affected by complement over-activation, supplementing the complement regulation system without disrupting existing regulation, offering potential treatment or prevention of AMD and other complement-related diseases.
Implementation Method 1
a polypeptide which is capable of binding C3b
Data Source
AI summary
Polypeptides comprising a C3b binding region are disclosed, as well as nucleic acids and vectors encoding such polypeptides, and cells and compositions comprising such polypeptides. Also disclosed are uses and methods using the polypeptides for treating and preventing diseases and conditions.