Thrombin may modulate dendritic cell activation in kidney transplant recipients with delayed graft function

Area of Science:

• Immunology
• Nephrology
• Transplantation

Background:

• Coagulation and complement activation are key in ischemia-reperfusion injury causing delayed graft function (DGF).
• The influence of coagulation on acquired immunity in DGF remains unclear.
• This study investigates protease-activated receptor 1 (PAR-1) on dendritic cells (DCs) and thrombin's effect on DC complement production and T-cell response.

Purpose of the Study:

• To investigate PAR-1 expression on graft-infiltrating DCs.
• To evaluate thrombin's impact on DC complement production.
• To assess thrombin's influence on DC-mediated T-cell responses.

Main Methods:

• Confocal microscopy for protein expression (PAR-1, fibrin, complement components).
• Flow cytometry for PAR-1 on cultured DCs.
• Quantitative PCR (qPCR) for complement receptor and cytokine gene expression.
• ELISPOT and ELISA for T-cell responses and interferon-gamma (IFN-g) production.

Main Results:

• PAR-1 expressed by myeloid DCs in DGF grafts, co-localizing with fibrin and complement deposits.
• PAR-1 expression increased on both immature and mature DCs in vitro.
• Thrombin stimulation upregulated complement production and induced a pro-inflammatory DC cytokine profile (IL-12/IL-17), while reducing IL-10.
• Activated DCs promoted IFN-g production by T cells, indicating a T helper 1 (Th1) bias.

Conclusions:

• PAR-1 is expressed by DCs in DGF grafts.
• PAR-1 activation by thrombin may drive complement production and a Th1 immune response.
• This suggests a link between DGF, coagulation, and detrimental acquired allo-responses contributing to graft damage.