SREBP signaling is essential for effective B cell responses

Area of Science:

• Immunology
• Molecular Biology
• Metabolic pathways

Background:

• Previous systems vaccinology studies linked the sterol regulatory binding protein (SREBP) pathway to human humoral immune responses.
• SREBP signaling regulates cholesterol homeostasis and cellular metabolism, processes potentially influencing immune cell function.

Purpose of the Study:

• To investigate the role of SREBP signaling in B cells and antigen-presenting cells (APCs) on immune responses.
• To elucidate the mechanisms by which SREBP signaling impacts B cell function and humoral immunity.

Main Methods:

• Generated mice with B cell-specific or CD11c+ APC-specific deletion of SCAP, a key regulator of SREBP signaling.
• Assessed immune responses, including antibody production, germinal center formation, memory B cell generation, and B cell metabolism.
• Utilized AID-Cre to delete SCAP in germinal center B cells to study its role in specific B cell subsets.

Main Results:

• B cell-specific ablation of SCAP impaired antibody responses, germinal center formation, memory B cell generation, and bone marrow plasma cell populations.
• SCAP deletion in B cells prevented metabolic reprogramming upon activation, leading to reduced proliferation and lipid raft content.
• Deletion of SCAP in germinal center B cells decreased lipid raft content and impaired cell cycle progression.

Conclusions:

• SREBP signaling within B cells is essential for effective humoral immunity, including antibody production and the establishment of immunological memory.
• SREBP pathway regulates critical metabolic processes in activated B cells, supporting their proliferation, survival, and differentiation.
• These findings reveal a direct mechanistic link between sterol metabolism and the quality and longevity of the adaptive immune response.