Expression of sPD-L1 levels in an ex vivo liver perfusion model

• Published in: Clinical and experimental immunology Vol. 219; no. 1
• Main Authors: Irsara, Christian, Weissenbacher, Annemarie, Krendl, Felix Julius, Anliker, Markus, Hofmann, Julia, Hautz, Theresa, Schneeberger, Stefan, Griesmacher, Andrea, Loacker, Lorin
• Format: Journal Article
• Language: English
• Published: England 21.01.2025
• Subjects: Adult; Aged; B7-H1 Antigen - metabolism; Biomarkers - metabolism; Female; Humans; Liver - metabolism; Liver - pathology; Liver Transplantation; Male; Middle Aged; Perfusion - methods; Reperfusion Injury - metabolism; cell surface molecules; transplantation; immune checkpoints
• ISSN: 0009-9104; 1365-2249; 1365-2249
• DOI: 10.1093/cei/uxae094

The programmed cell death protein 1 (PD-1) acts as a central inhibitory immune checkpoint receptor. The soluble form of its primary ligand, sPD-L1, was found to be elevated in the serum of patients with cancer, infectious diseases, and chronic inflammation. So far, the hepatic origin of sPD-L1 has received relatively little attention and is therefore the subject of this study in the context of normothermic machine perfusion (NMP) of liver grafts. sPD-L1 concentrations as well as several well-established clinically relevant laboratory parameters were determined in the perfusate of 16 donor liver grafts undergoing NMP up to 30 hours. sPD-L1 levels continuously increased during NMP and significantly correlated with markers of hepatic synthesis (cholinesterase), acute-phase proteins (von Willebrand factor, procalcitonin, antithrombin, interleukin-6, fibrinogen), and liver decay markers (gamma-glutamyltransferase, alanine aminotransferase, aspartate aminotransferase, lactate dehydrogenase). Perfusate leukocytes were in the lower reference range and decreased after 12 hours. Mean sPD-L1 levels in the perfusate correlated with donor levels of gamma-glutamyltransferase, alanine aminotransferase, creatinine, and blood urea nitrogen. Our study reveals a significant increase in the concentration of sPD-L1 following ischemia-reperfusion injury in a hepatic ex vivo model. sPD-L1 concentrations during NMP correlate with established acute-phase proteins and liver cell decay markers, suggesting that hepatic sPD-L1 synthesis or shedding increases during the acute phase and cell decay. Furthermore, sPD-L1 correlates with established liver function and synthesis parameters as well as with donor laboratory values and might therefore be a potential biomarker for the hepatic function of liver grafts.