CD28 Superagonistic Antibody Membrane-Proximal Binding
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Solution Overview
Problem
Current methods for modulating CD28 signaling are limited as they require additional signals from the T cell receptor, and existing antibodies activate CD28 inefficiently by binding at non-optimal locations, leading to suboptimal immune system modulation.
Innovation Solution
The development of a method to crystallize the CD28/Fab fragment complex, derive structural coordinates, and use these to identify modulators that bind to CD28, creating superagonistic antibodies and chimeric proteins that preferentially exclude phosphatases, thereby enhancing CD28 signaling by binding at membrane-proximal regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional antibodies are used to activate CD28, then CD28 can be activated, but additional signals from the T cell receptor are required and activation efficiency is low
Solution Approach 1:
The patent uses a crystallized CD28 structure as an intermediary to identify and design superagonistic antibodies. The crystal structure serves as a mediator between the desired activation effect and the antibody design process, enabling rational drug design that directly targets CD28's phosphatase exclusion mechanism without requiring additional T cell receptor signals.
Solution Approach 2:
The invention changes the binding location parameter of antibodies from non-optimal sites to membrane-proximal regions of CD28. This parameter change in binding location enables the antibody to preferentially exclude phosphatases while favoring kinase access, thereby achieving efficient CD28 activation as a standalone signal without requiring additional T cell receptor signals.
2Reliability
If antibodies bind at non-optimal locations on CD28, then CD28 can be activated, but phosphatases are not effectively excluded leading to suboptimal signaling
Solution Approach 1:
The patent applies parameter changes by precisely controlling the binding location of antibodies to membrane-proximal regions of CD28. This location parameter optimization enables the antibody to sterically hinder phosphatase access while maintaining kinase access, achieving preferential phosphatase exclusion and efficient signal transduction.
Solution Approach 2:
The invention applies local quality by creating different microenvironments at different locations on CD28. The membrane-proximal binding region creates a localized steric environment that selectively excludes phosphatases while allowing kinases to function, thereby achieving spatially differentiated enzyme access and optimized signaling.
3Reliability
If superagonistic antibodies bind at membrane-proximal regions, then phosphatases are preferentially excluded enhancing CD28 signaling, but the structural complexity of identifying such modulators increases
Solution Approach 1:
The patent applies preliminary action by crystallizing the CD28 structure beforehand to obtain accurate structural coordinates. This pre-established structural model serves as a foundation for identifying superagonistic antibodies, simplifying the subsequent drug design process despite the complexity of achieving membrane-proximal binding and phosphatase exclusion.
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 potent and efficient modulation of CD28 signaling, enabling more effective immune system activation or inhibition by favoring phosphorylation over de-phosphorylation, leading to enhanced receptor triggering and immune response control.
Implementation Method 1
This was done by crystallizing a CD28/Fab fragment complex, subjecting it to X-ray diffraction and deriving the structural coordinates from the diffraction measurements.
Implementation Method 2
This was done by crystallizing a CD28/Fab fragment complex
Implementation Method 3
antibodies that activate CD28 by a mechanism that involves preferential exclusion of phosphatases (as opposed to kinases) from the vicinity of the receptor
Implementation Method 4
CD28 activation is dependent on phosphorylation of its cytoplasmic domain
Implementation Method 5
favoring phosphorylation over de-phosphorylation
Data Source
AI summary
Method of identifying a modulator of CD28 comprising comparing a structural model of a candidate modulator with a structural model of CD28 to thereby determine whether the modulator will bind to CD28, wherein the structural model is derived from, or comprises, structural coordinates of a crystal of: (i) CD28, (ii) a fragment of CD28, or (iii) a homolog of (i) or (ii). The crystal of CD28 in a soluble form complexed with the Fab fragment of a mitogenic (superagonistic) antibody has been obtained and used for the determination of the 3D-structure of the receptor. The application also relates to modulators of superagonistic signalling for any receptor of the CD28 family, i.e. to superagonistic antibodies and chimeric proteins thereof, and to the screening of the superagonistic modulators. In the methods of screening, the binding of the candidate modulators to a portion of the receptor proximal to the cell membrane is investigated.