Obesity induces pro-inflammatory B cells and impairs B cell function in old mice

Area of Science:

• Immunology
• Aging Research
• Adipose Tissue Biology

Background:

• Age-related changes in B cells are observed, but their role in visceral adipose tissue (VAT) remains unclear.
• VAT is increasingly recognized for its role in systemic inflammation and metabolic dysfunction.

Purpose of the Study:

• To investigate the characteristics and function of B cells within VAT in aged mice.
• To determine the influence of adipocytes on B cell phenotype and function.

Main Methods:

• Comparative analysis of B cells from VAT and spleen of young and old mice.
• Assessment of B cell surface markers, gene expression (NF-kB), and antibody secretion (IgG2c).
• In vitro co-culture experiments using adipocyte-conditioned medium to study B cell differentiation.

Main Results:

• VAT exhibited higher proportions of pro-inflammatory age-associated B cells (ABC) and lower Follicular (FO) B cells compared to spleen.
• VAT B cells expressed elevated pro-adipogenic and inflammatory markers, including NF-kB, and secreted IgG2c antibodies.
• Adipocyte-conditioned medium induced differentiation of FO B cells into ABC.
• Adipocytes produced pro-inflammatory chemokines, suggesting a mechanism for B cell recruitment to VAT.

Conclusions:

• Adipocytes directly influence the generation of pro-inflammatory B cells within VAT.
• These findings reveal a novel mechanism linking adipose tissue and age-related immune dysregulation.