JOINT BASE SAN ANTONIO, Texas —
Traumatic injury is a leading cause of mortality in the military and civilian population. The loss of blood, combined with tissue damage, initiates a physiologic response that can promote both reparative wound healing and deleterious inflammation, depending on the predisposition of the affected individual’s immune system.
The Department of Combat Casualty Care at the Naval Medical Research Unit San Antonio, or NAMRU-SA, at Joint Base San Antonio-Fort Sam Houston works towards understanding both the physiologic and molecular changes which occur in response to traumatic injury. One of the unit’s primary focus areas is the identification of the mechanisms the immune system exploits to respond to injury, specifically hemorrhage and poly-trauma.
Like most other things, humans have widely varying immune systems due to a variety of factors including genetic makeup, gender, age, lifestyle and previous antigen exposure. Collectively, each of these factors contributes to an individual’s immune system’s response to insult.
NAMRU-SA research employs models that closely replicate militarily relevant injuries in order to translate findings from the laboratory to the clinical setting. Finding solutions to diagnose and treat injuries warfighters sustain on the battlefield is the ultimate goal.
One of the tools used to monitor the status of the immune system in conditions such as traumatic hemorrhage is immune-phenotyping. This involves uncovering the contributions of different immune cell populations in terms of both their occurrence over time (kinetics) and expression of inflammatory factors (functionality).
Researchers use a sophisticated technique, termed flow cytometry, which allows them to perform exhaustive characterization of the immune response with cellular resolution required only a few microliters of sample.
Flow cytometry utilizes the power of fluidics to pass cells in suspension through a laser beam. Physical properties of cells and particles are then captured and converted to quantifiable outputs to measure cell size and granular content. Fluorescently labeled antibodies can be employed to tag specific proteins, such as surface receptors or intracellular molecules, permitting a nuanced and in-depth cellular analysis.
Flow cytometry is utilized to determine the contributions of various white blood cells to the inflammatory milieu in trauma. Researchers can discern what molecules are being produced by each cell type and compile an extensive inflammatory profile for that particular sample.
Through immunophenotyping, NAMRU-SA researchers can accomplish three critical goals: uncover key cells and cell products required for orchestrating immunologic reactions to injury; foster a more complete understanding of the signaling pathways that become deranged in trauma patients; and determine which, if any, of these molecules can be exploited as therapeutic targets or opportunities for clinical intervention.
These studies continue to provide vital knowledge for both research efforts and clinical decision-making within the trauma and critical care fields.