HLA-E Chimeric Molecule Enhances NK Cell Resistance
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Solution Overview
Problem
Current xenotransplantation methods face challenges with acute vascular rejection due to the lack of resistance in nonhuman mammal cells to human NK cell cytotoxicity, particularly as nonhuman mammal cells do not express HLA class I molecules, making them susceptible to damage by human NK cells.
Innovation Solution
Development of HLA-E chimeric molecules by replacing or modifying domains of the HLA-E molecule with corresponding domains from HLA-G1, along with reforming the signal peptide, to increase expression levels and enhance resistance to human NK cell cytotoxicity in nonhuman mammal cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If HLA-G is used to transform nonhuman mammal cells, then it is relatively easy to express on cell surface, but suppression of cytotoxicity by human NK cell is low
Solution Approach 1:
The patent creates a composite HLA-E chimeric molecule by combining the signal peptide and α1 domain from HLA-E with the α2 domain from HLA-G. This composite structure leverages the high cytotoxicity suppression capability of HLA-E's binding site while incorporating HLA-G's favorable expression characteristics, achieving both high NK cell resistance and easy expression on nonhuman mammal cells.
2Reliability
If HLA-E base sequence is used to transform nonhuman mammal cells, then suppression of cytotoxicity by human NK cell is high, but it is not easy to express on cell surface
Solution Approach 1:
The patent applies local quality by selectively incorporating only the critical functional domains from HLA-E (signal peptide and α1 domain that bind NK cell receptors) while replacing the difficult-to-express α2 domain with HLA-G's sequence. This localized optimization maintains high cytotoxicity suppression where needed while improving overall expression efficiency.
3Reliability
If HLA-A, HLA-B, or HLA-C genes are used to transform nonhuman mammal cells, then cell damage by human NK cell is avoided, but these molecules are polymorphic making it impractical to prepare cells applicable to each HLA
Solution Approach 1:
The patent uses HLA-E and HLA-G, both of which are non-polymorphic MHC class I molecules, to create a universal solution that can protect nonhuman mammal cells from human NK cell cytotoxicity regardless of the recipient's specific HLA genotype. This eliminates the need to prepare different cell lines for each HLA type, significantly reducing preparation complexity while maintaining broad protective efficacy.
Data Source
AI summary
HLA-E chimeric molecules for providing nonhuman mammalian cells resistant to cytotoxic human NK cells, nucleotide sequences encoding these chimeric molecules, and nonhuman mammalian cells and nonhuman mammals transformed with such nucleotide sequences are disclosed herein. The HLA-E chimeric molecules of the invention contain a peptide that reforms all or part of the signal peptide region, α1 domain and/or α2 domain of HLA-E, and a nucleotide sequence of the invention encodes a HLA-E chimeric molecule. A transformant incorporating a nucleotide sequence of the invention expresses HLA-E efficiently.