Korean J Transplant.  2023 Nov;37(Suppl 1):S209. 10.4285/ATW2023.F-7989.

Immune cells in brown adipose tissue are involved in allogeneic immune responses

• Yi Y
• Kang Y
• Tran PH
• Hwang S
• Jung DH
• Kim N

• KMID: 2551829
• DOI: http://doi.org/10.4285/ATW2023.F-7989

Abstract

Background
Adipose tissues are associated with metabolic processes and immune functions. Brown adipose tissue is known for its involvement in energy expenditure and thermogenesis, particularly in infants and hibernating animals. The functions of the brown adipose tissue in immune response and transplantation are less investigated.
Methods
A mouse skin graft model was utilized, where BALB/C mice were employed as recipients and C57BL/6 mice as allogeneic donors. The recipients received tail skin grafts from C57BL/6 mice on the upper right back. The mice were sacrificed after 7 days. Flow cytometry was used to analyze immune cells from the brown fat and the draining lymph node. Glycerol and adenosine triphosphate (ATP) assays were performed using brown adipose tissue. A quantitative real-time polymerase chain reaction (qPCR) was conducted to assess the expressions of the genes in the brown adipose tissue.
Results
The weight of the brown adipose tissue from allogeneic skin graft mice exhibited a significant decrease, compared with that of syngeneic skin graft mice. The concentrations of glycerol and ATP were notably elevated in the brown adipose tissues of allogeneic skin graft mice than those of syngeneic skin graft mice. qPCR data revealed a downregulation of Pparg expression, while Leptin expression was upregulated in the brown adipose tissues of allogeneic skin graft mice. The frequencies of CD8⁺, CD44⁺ CD62L^– memory CD8⁺ T cells in brown adipose tissue were higher in allogeneic skin graft mice than in syngeneic ones.
Conclusions
This study suggests that the immune cells within the brown adipose tissue are involved in allogeneic immune responses while lipid metabolism in the brown adipose tissue is changed by allogeneic immune responses as well.