Decreased circulating CD39+ regulatory T cell frequencies following non-traumatic brain death.

Abstract

Background and purpose: Regulatory T cells (Tregs) are thought to modulate immune responses during Brain death (BD), However findings on their role remain controversial. This study aimed to assess the frequency of circulating Tregs in the peripheral blood of non-traumatic BD cases, specifically focusing on CD4⁺CD25⁺CD127^low/-CD39⁺ Tregs and the levels of inflammatory cytokine mRNA in BD individuals.

Methods: The percentage of CD4⁺CD25⁺CD127^low/-CD39⁺ Tregs was measured using flow cytometry in BD patients upon admission and in control subjects. Additionally, mRNA expression levels of interleukin (IL)-1β, IL-6, IL-8, IL-17, tumor necrosis factor (TNF)-α and Interferon (IFN)-γ were quantified in peripheral blood mononuclear cells (PBMCs) from 28 BD individuals and 28 controls using real-time polymerase chain reaction.

Results: CD39⁺ Tregs were significantly reduced in non-traumatic BD cases compared with control group (P < 0.0001). Moreover, the expression levels of IL-1β, IL-6, IL-8, IL-17a, IFN-ɣ, and TNF-α were significantly elevated in non-traumatic BD cases compared to the control group (P < 0.01, P < 0.05, P < 0.01, P < 0.0001, P < 0.0001, P < 0.001 respectively).

Conclusion: This study provides novel evidence of reduced CD39⁺ Tregs in the peripheral blood of non-traumatic BD patients, accompanied by increased inflammatory cytokine gene expression. Further investigations are needed to explore the underlying mechanisms and potential therapeutic implications.