Effects of major histocompatibility complex class II knockout on mouse bone mechanical properties during development

Area of Science:

• Immunology
• Skeletal Biology
• Biomedical Science

Background:

• Major histocompatibility complex (MHC) class II molecules are crucial for adaptive immune responses.
• The role of MHC class II in skeletal development is not fully understood.
• Investigating MHC II's impact on bone development can reveal novel biological pathways.

Purpose of the Study:

• To determine the effect of MHC class II knockout on peripheral skeletal development in mice.
• To compare skeletal parameters between MHC II knockout mice (C2D) and wild-type controls (B6).
• To assess the impact of MHC II deficiency on bone mechanical properties, geometry, and composition.

Main Methods:

• Utilized C2D mice (MHC II knockout) and wild-type C57BL/6J (B6) male mice.
• Evaluated skeletal development at 8, 12, and 16 weeks of age.
• Performed mechanical, geometric, and compositional analyses on femurs.

Main Results:

• C2D mice exhibited significantly reduced skeletal development compared to B6 mice at all tested ages.
• Femur stiffness, peak force, and mineral mass in C2D mice were consistently lower than in B6 mice.
• At 8 weeks, C2D femur stiffness, peak force, and mineral mass were 74%, 64%, and 66% of B6 values, respectively, with similar reductions observed at 12 and 16 weeks.

Conclusions:

• MHC class II knockout delays the development of adult bone properties in mice.
• Reduced skeletal development in MHC II knockout mice is associated with lower body mass.
• These findings highlight a significant role for MHC class II in regulating skeletal maturation.