Improved Murine MHC-Deficient HLA Transgenic NOD Mouse Models for Type 1 Diabetes Therapy Development.

Area of Science:

• Immunology
• Genetics
• Endocrinology

Background:

• Type 1 diabetes (T1D) mouse models are essential for therapy development.
• Existing NOD.β2m-/- mice expressing human HLA class I molecules have limitations, including lack of FcRn, impacting certain therapies.
• There is a need for improved mouse models that better recapitulate human T1D pathogenesis and therapeutic responses.

Purpose of the Study:

• To develop next-generation, HLA-humanized NOD mouse models for type 1 diabetes (T1D) research.
• To create NOD mice lacking all classical murine MHC class I and II molecules while retaining nonclassical MHC I expression.
• To validate the utility of these new models for studying T1D pathogenesis and testing therapies.

Main Methods:

• Utilized CRISPR/Cas9 gene editing to ablate NOD H2-K d and H2-D b classical class I variants (cMHCI-/-).
• Further ablated the H2-A g7 class II variant to create NOD mice lacking all classical murine MHC (cMHCI/II-/-).
• Introduced transgenes for human HLA-A2 or HLA-B39 into the cMHCI-/- background and assessed T1D susceptibility and CD8+ T-cell responses.

Main Results:

• NOD-cMHCI-/- mice retained nonclassical MHC I molecule expression and FcRn activity, unlike previous models.
• Transgenic expression of HLA-A2 or HLA-B39 in NOD-cMHCI-/- mice restored pathogenic CD8+ T-cell development.
• These humanized NOD mice exhibited restored T1D susceptibility, mediated by human HLA class I-restricted CD8+ T cells.

Conclusions:

• Next-generation NOD mice lacking classical murine MHC but expressing human HLA variants provide a superior platform for T1D research.
• These models overcome limitations of previous mouse models, enabling the study of therapies dependent on FcRn and other nonclassical MHC molecules.
• The developed HLA-humanized NOD models are valuable tools for advancing type 1 diabetes therapy development.