Marcos J. Ramos-Benitez, PhD,
Postdoctoral Fellow
National Institutes of Health
Bethesda, MD
Disclosure information not submitted.
Mark Connelly, MD
Physician
Children's National Medical Center, United States
Disclosure information not submitted.
Jeffrey Strich, MD, MHS
National Institutes of Health Clinical Center
Bethesda, MD
Disclosure information not submitted.
Joanna Swerczek, CMAR
Non-human Primates Project Manager
NIH, United States
Disclosure information not submitted.
Ian Moore, DVM, PhD, DACVP
Chief, Infectious Disease Pathogenesis Section (IDPS)
NIH, United States
Disclosure information not submitted.
Daniel Chertow, MD, FCCM
Tenure Track Investigator
National Institutes of Health Clinical Center, United States
Disclosure information not submitted.
Title: Novel Preclinical Intensive Care Unit Model to Characterize Bacterial Sepsis Progression
Introduction: Sepsis is a systemic inflammatory response to infection that can lead to shock and multiorgan failure. Despite decades of research, sepsis accounts for approximately 20% of all global deaths. The translational impact of studies in non-human primates (NHPs) has been limited by non-standardized delivery of supportive care. We developed a highly translatable intensive care unit (ICU) model in NHPs that provides a comprehensive framework for preclinical studies of pathophysiology, molecular pathogenesis, and treatment of sepsis.
Methods: Four rhesus macaques were continuously sedated and provided supportive care consistent with care in modern human ICUs. Arterial and pulmonary artery catheters were placed for continuous physiologic monitoring and longitudinal matched blood samples were collected. Three animals were intravenously infused with 1 x 109 CFU/kg of Escherichia coli. Bacterial load and endotoxin level were serially measured. To evaluate neutrophil and endothelial biology, we measured levels of Syndecan-1, Angiopoietin-2, Tissue Factor and Neutrophil Extracellular Traps (NETs).
Results: Bacteremia was detected until antibiotics were given approximately three hours post-infusion (p.i), while endotoxemia persisted for > 10hrs p.i. in two of three infected animals. Within the first three hours p.i., infected animals had a ~30% increase in heart rate. Animals initially maintained adequate mean arterial pressures (MAPs) >65mmHg but eventually developed sustained hypotension that ultimately became refractory to vasopressor therapy. Increase in transaminases and creatinine levels indicated acute kidney and liver injury, supported by histopathological analysis. We described an initial significant increase in plasma levels of Syndecan-1 (~30min p.i.), followed by Angiopoeitin-2 and Tissue Factor (~2.5hrsp.i.), proposing an early glycocalyx deterioration and progressive endothelial injury. Mounting levels of NETs in plasma in the presence of neutropenia hinted an active suicidal NETosis.
Conclusions: We present an NHP septic shock model that simultaneously characterizes pathophysiology and molecular pathogenesis in an environment that closely emulates the human ICU. This platform represents a novel tool with an unprecedented resolution for pre-clinical evaluation and treatment of bacterial sepsis.