OC 38.1 - Altered platelet and megakaryocyte phenotype and enhanced platelet-macrophage interactions in liver fibrosis

Monday, June 24, 2024

09:30 – 09:45 ICT

Room: 211 A-D

Presenting Author(s)

Martina Casari, Master´s degree

PhD Candidate
Center for Thrombosis and Hemostasis, University Medical Center of the Johannes Gutenberg-University, Mainz, Germany
Mainz, Rheinland-Pfalz, Germany

Co-Author(s)

BM

Bettina Mros

Technical assistant
Center for Thrombosis and Hemostasis, University Medical Center of the Johannes Gutenberg-University, Mainz, Germany
Mainz, Rheinland-Pfalz, Germany
OA

Olga An

PhD Candidate
Center for Thrombosis and Hemostasis, University Medical Center of the Johannes Gutenberg-University, Mainz, Germany
Mainz, Rheinland-Pfalz, Germany
DS

Dominik Siegl

PhD Candidate
Institute of Translational Immunology, University Medical Center of the Johannes Gutenberg University
Mainz, Rheinland-Pfalz, Germany
LA

Lama Al Jurdi

Master Student
Center for Thrombosis and Hemostasis, University Medical Center of the Johannes Gutenberg-University, Mainz, Germany
Mainz, Rheinland-Pfalz, Germany
KM

Kristina Mott

Postdoc
University Hospital Würzburg, Department of Experimental Biomedicine I, Würzburg, Germany
Würzburg, Bayern, Germany
HS

Harald Schulze

Professor
University Hospital Würzburg, Department of Experimental Biomedicine I, Würzburg, Germany
Würzburg, Bayern, Germany
DS

Detlef Schuppan

Professor
Institute of Translational Immunology, University Medical Center of the Johannes Gutenberg University
Mainz, Rheinland-Pfalz, Germany
Carsten Deppermann, PhD

Assistant Professor
Center for Thrombosis and Hemostasis (CTH), University Medical Center Mainz, Germany

Background: Liver fibrosis - the accumulation of extracellular matrix proteins like collagen - during chronic liver disease can compromise liver functionality and result in hepatocellular carcinoma (HCC). Liver macrophages contribute to liver disease progression. Besides their role in hemostasis, platelets and megakaryocytes play a role in immune responses. However, their function and interaction with macrophages in liver fibrosis and HCC remains incompletely understood.

Aims: To investigate alterations in platelet and megakaryocyte function in liver fibrosis.

Methods: We analyzed Mdr2-/- mice which lack the phospholipid flippase Mdr2 causing bile to leak into the portal tracts leading to periductal inflammation, fibrosis and cholestasis resembling human primary sclerosing cholangitis. Platelet activation, receptor expression, phosphatidylserine (PS) exposure and platelet-leukocyte aggregate (PLA) formation were measured by flow cytometry using whole blood. Bone marrow (BM), spleen and liver tissue were analyzed by immunofluorescence staining and flow cytometry to characterize immune cells, platelets and megakaryocytes. BM-derived macrophages were co-cultured with platelets and their phenotypic changes analyzed using qPCR.

Results: Mdr2-/- mice revealed significantly increased platelet count and size, number of young platelets and reduced expression of platelet collagen receptor GPVI. Moreover, Mdr2-/- platelets exhibited reduced activation, PS exposure and PLA formation upon stimulation with collagen-related peptide. Spleen and BM exhibited increased number and ploidy of megakaryocytes in Mdr2-/-. Infiltration of monocyte-derived macrophages (MDMs) and immune cells was observed in Mdr2-/- livers. Intrahepatic platelet accumulation and enhanced colocalization between platelets and MDMs and Kupffer cells was found. Coculture of BM-derived macrophages with platelets led to an altered macrophage Arg1 expression.

Conclusion(s): In a mouse model of liver fibrosis, we observe altered platelet and megakaryocyte function as well as increased platelet-macrophage interactions suggesting platelets might contribute to liver fibrosis progression, potentially through modulating macrophage phenotypes. Platelets and megakaryocytes might thus be a potential therapeutic target in cholestatic liver disease.