PB0727 - The role of thrombin and thrombin signaling in chronic LCMV infection

Monday, June 26, 2023

18:30 – 19:30 ET

Room: Exhibition

Presenting Author(s)

Rachel L. Cantrell

Doctoral Candidate
Immunology Graduate Program, University of Cincinnati College of Medicine, Cincinnati, Ohio
Cincinnati, Ohio, United States

Co-Author(s)

HF

H. Alex Feldman

Doctoral Candidate
Immunology Graduate Program, University of Cincinnati College of Medicine, Cincinnati, Ohio
Cincinnati, Ohio, United States
LR

Leah Rosenfeldt

Research Assistant IV
Cancer and Blood Diseases Institute, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio
Cincinnati, Ohio, United States
AA

Ayad Ali

MD/PhD Student
Medical Science Training Program, University of Cincinnati College of Medicine, Cincinnati, Ohio
Cincinnati, Ohio, United States
Bal Krishan Sharma, MSc, Mphil, PhD (he/him/his)

Research Associate
Cancer and Blood Diseases Institute, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio
Cincinnati, Ohio, United States
AR

Alexey Revenko

Executive Director
Ionis Pharmaceuticals, Carlsbad, California
Carlsbad, California, United States
BM

Brett Monia

Chief Executive Officer
Ionis Pharmaceuticals, Carlsbad, California
Carlsbad, California, United States
SW

Stephen Waggoner

Associate Professor
Center for Autoimmune Genomics and Etiology, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio
Cincinnati, Ohio, United States
Joseph S. Palumbo, MD (he/him/his)

Professor of Pediatrics
University of Cincinnati and the Cincinnati Children's Hospital Medical Center
Cincinnati, Ohio, United States

Background: We showed that thrombin enhances the survival, proliferation and cytokine production of murine and human CD8+ T cells. We hypothesized that thrombin may influence antiviral T cell functionality during chronic virus infections.

Aims: Investigate the role of thrombin in sustaining an adaptive immune response to chronic LCMV infection.

Methods: We ASO depleted circulating prothrombin to 10% of normal in mice prior to infection with high dose clone 13 lymphocytic choriomeningitis virus (LCMV). LCMV is non-cytolytic, so any pathologies are consequences of antiviral T cell activity. We monitored body weight, and survival of infected mice. In separate experiments, we sacrificed the mice at day 8 to analyze histology, complete blood counts (CBC), and T cell antiviral responses. Similar experiments were conducted in PAR-1 deficient mice.

Results: Lowering prothrombin levels resulted in 100% mortality following infection with this normally non-lethal dose of LCMV. Depletion of CD8+ T cells completely prevented mortality. We also did not observe any significant prothrombin-dependent differences in inflammatory cytokines generated by antiviral-specific CD8+ T cell, plasma cytokines, insulin, or cortisol. CBC analysis revealed a significant reduction in hemoglobin and platelet counts. Histological analysis of the lung, heart, liver, kidney, and brain did not reveal any clear cause of the prothrombin-dependent mortality. Histologic analysis of the spleen demonstrated diminished extramedullary hematopoiesis in mice with low prothrombin. Analyses of LCMV infection in PAR-1-deficient mice revealed that loss of this thrombin receptor resulted in significantly increased weight loss compared to control mice, but the PAR-1-deficient animals ultimately recovered.

Conclusion(s): Thrombin is critical for the survival of LCMV infected mice. We suspect that this mortality is a result of severe anemia in combination with a failure of stress hematopoiesis in response to CD8+ T cell-driven bone marrow injury.