AUTHOR=Vollrath Jan Tilmann , Klingebiel Felix , Bläsius Felix Marius , Greven Johannes , Bolierakis Eftychios , Janicova Andrea , Dunay Ildiko Rita , Hildebrand Frank , Marzi Ingo , Relja Borna 

TITLE=Alterations of Phagocytic Activity and Capacity in Granulocytes and Monocytes Depend on the Pathogen Strain in Porcine Polytrauma

JOURNAL=Frontiers in Medicine

VOLUME=8

YEAR=2021

URL=https://www.frontiersin.org/journals/medicine/articles/10.3389/fmed.2021.645589

DOI=10.3389/fmed.2021.645589

ISSN=2296-858X

ABSTRACT=<p><bold>Background:</bold> Polytraumatized patients undergo a strong immunological stress upon insult. Phagocytes (granulocytes and monocytes) play a substantial role in immunological defense against bacteria, fungi and yeast, and in the clearance of cellular debris after tissue injury. We have reported a reduced monocytes phagocytic activity early after porcine polytrauma before. However, it is unknown if both phagocyte types undergo those functional alterations, and if there is a pathogen-specific phagocytic behavior. We characterized the phagocytic activity and capacity of granulocytes and monocytes after polytrauma.</p><p><bold>Methods:</bold> Eight pigs (<italic>Sus scrofa</italic>) underwent polytrauma consisting of lung contusion, liver laceration, tibial fracture and hemorrhagic shock with fluid resuscitation and fracture fixation with external fixator. Intensive care treatment including mechanical ventilation for 72 h followed. Phagocytic activity and capacity were investigated using an <italic>in vitro ex vivo</italic> whole blood stimulation phagocytosis assays before trauma, after surgery, 24, 48, and 72 h after trauma. Blood samples were stimulated with Phorbol-12-myristate-13-acetate and incubated with FITC-labeled <italic>E. coli, S. aureus</italic> or <italic>S. cerevisiae</italic> for phagocytosis assessment by flow cytometry.</p><p><bold>Results:</bold> Early polytrauma-induced significant increase of granulocytes and monocytes declined to baseline values within 24 h. Percentage of <italic>E. coli</italic>-phagocytizing granulocytes significantly decreased after polytrauma and during further intensive care treatment, while their capacity significantly increased. Interestingly, both granulocytic phagocytic activity and capacity of <italic>S. aureus</italic> significantly decreased after trauma, although a recovery was observed after 24 h and yet was followed by another decrease. The percentage of <italic>S. cerevisiae</italic>-phagocytizing granulocytes significantly increased after 24 h, while their impaired capacity after surgery and 72 h later was detected. Monocytic <italic>E. coli</italic>-phagocytizing percentage did not change, while their capacity increased after 24–72 h. After a significant decrease in <italic>S. aureus</italic>-phagocytizing monocytes after surgery, a significant increase after 24 and 48 h was observed without capacity alterations. No significant changes in <italic>S. cerevisiae</italic>-phagocytizing monocytes occurred, but their capacity dropped 48 and 72 h.</p><p><bold>Conclusion:</bold> Phagocytic activity and capacity of granulocytes and monocytes follow a different pattern and significantly change within 72 h after polytrauma. Both phagocytic activity and capacity show significantly different alterations depending on the pathogen strain, thus potentially indicating at certain and possibly more relevant infection causes after polytrauma.</p>