Extracellular vesicles of patients with liver cirrhosis & acute-on-chronic liver failure have immunomodulatory functions

Background and Aims Patients with liver cirrhosis (LC) and acute-on-chronic liver failure (ACLF) show distinct changes regarding the cellular structure of the liver and the immune system. Cell-cell communication and interactions of different liver cell subtypes and immune cells play an important role during disease progression and complications (e.g. infections). Within the last years, the role of extracellular vesicles (EVs) as communicators between cells is raising more and more attention. We therefore aimed to characterize phenotype and function of EVs derived from the blood of LC and ACLF patients.

Method Healthy donor blood from discarded buffy coat bags was provided by the blood donation center at the University hospital Essen. Patients with compensated or decompensated LC and ACLF were recruited from a prospective cohort study. EVs were isolated from EDTA blood by precipitation and characterized regarding particle size and concentration by Nanoparticle Tracking Analysis (NTA). Surface marker were investigated using flow cytometry and protein content was analyzed using Western Blot and Mass Spectrometry. For functional analysis, 20 µg blood-derived EVs were used to stimulate either healthy donor peripheral blood mononuclear cells (PBMCs) or magnetic bead-isolated monocytes for 24h, which were then analyzed by flow cytometry or qPCR.

Results EVs of LC and ACLF patients show lower expressions of exosome-specific marker (e.g. CD9, CD63, CD81) and liver cell-specific marker (e.g. ASGPR1, CD163) compared to healthy donor EVs. Particle concentration in blood of patients decreases, whereas the average size increases with the severity of the disease. In functional assays with PBMCs, blood-derived EVs of LC and – to a stronger extend – of ACLF patients lead to changes in the composition of immune cell populations, e.g. by downregulation of CD197 (lymph node-homing receptor) on T cells or increased expression of activation markers on B cells (CD38, HLA-DR).

Conclusion LC and ACLF patients have less differentiated EVs than healthy donors. The vesicles show immunomodulatory functions for example by leading to an increased amount of CD4⁺ and CD8⁺ effector memory T cells.

Publication History

Article published online:
04 January 2021