Humanized MHC Mouse Models for Peptide Identification
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Solution Overview
Problem
Current systems lack effective in vivo and in vitro methods to identify and select peptides that provoke a suitable immune response, particularly for clinically significant antigens like those associated with cancer, due to the need for biological systems that mimic aspects of the human immune system.
Innovation Solution
Genetically modified non-human animals, such as mice, are engineered to express humanized Major Histocompatibility Complex (MHC) class I and class II proteins, allowing for the identification and evaluation of peptides in the context of a humanized cellular immune system, using techniques like homologous recombination in ES cells to introduce chimeric human/non-human MHC loci.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional mouse MHC molecules are used for peptide identification, then the system is simple and well-established, but it fails to mimic human immune responses and identify clinically significant human antigens
Solution Approach 1:
The patent changes the fundamental parameter of MHC molecule type from murine to human by replacing the mouse MHC class I and class II genes with human HLA genes in the mouse genome. This parameter change enables the mouse immune system to present human peptides to human T cells, thereby identifying clinically significant human antigens that would not be detectable using conventional mouse MHC molecules.
Solution Approach 2:
The patent uses humanized MHC molecules as an intermediary system that bridges the gap between mouse model simplicity and human immune response accuracy. The humanized mice serve as an intermediate model organism that expresses human MHC molecules, allowing researchers to study human antigen presentation and T cell responses in a controlled in vivo system without requiring human subjects.
2Adaptability or versatility
If humanized MHC molecules are introduced into mice, then human immune response mimicry is achieved, but the genetic modification process becomes highly complex requiring homologous recombination in ES cells
Solution Approach 1:
The patent performs genetic modification in advance by introducing human MHC genes into mouse embryonic stem (ES) cells before generating live animals. This preliminary action in ES cells allows for proper germline transmission of the humanized MHC genes, ensuring that all offspring inherit the human MHC molecules and express them on their cell surfaces, thereby establishing a stable humanized mouse line.
Solution Approach 2:
The patent employs a nested approach where human HLA gene sequences are inserted into the mouse genome at specific MHC loci through homologous recombination. The human gene sequences are nested within the mouse genomic framework, utilizing mouse regulatory elements and genomic structure to ensure proper expression of the human MHC molecules in the context of the mouse immune system.
3Productivity
If both human MHC class I and class II proteins are expressed, then comprehensive T cell response evaluation is enabled, but the genetic engineering requires modification of multiple MHC loci
Solution Approach 1:
The patent creates a universal humanized mouse model that simultaneously expresses both human MHC class I and class II molecules, enabling comprehensive evaluation of both CD8+ cytotoxic T cell responses (via class I) and CD4+ helper T cell responses (via class II). This multi-functional system allows researchers to screen for peptides that can activate different types of T cells using a single animal model rather than requiring separate models for each MHC class.
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
These genetically modified animals provide a biological system for generating and identifying peptides that associate with human MHC proteins, enabling the activation of CD8+ and CD4+ T cells, thus mimicking human immune responses and aiding in the identification of clinically significant antigens.
Implementation Method 1
using techniques like homologous recombination in ES cells to introduce chimeric human/non-human MHC loci
Data Source
AI summary
The invention provides genetically modified non-human animals that express chimeric human/non-human MHC I and MHC II polypeptides and/or human or humanized β2 microglobulin polypeptide, as well as embryos, cells, and tissues comprising the same. Also provided are constructs for making said genetically modified animals and methods of making the same. Methods of using the genetically modified animals to study various aspects of human immune system are provided.