Severe Traumatic Injury Induces Phenotypic and Functional Changes of Neutrophils and Monocytes

Abstract

Background: Severe traumatic injury has been associated with high susceptibility for the development of secondary complications caused by dysbalanced immune response. As the first line of the cellular immune response, neutrophils and monocytes recruited to the site of tissue damage and/or infection, are divided into three different subsets according to their CD16/CD62L and CD16/CD14 expression, respectively. Their differential functions have not yet been clearly understood. Thus, we evaluated the phenotypic changes of neutrophil and monocyte subsets among their functionality regarding oxidative burst and the phagocytic capacity in severely traumatized patients. Methods: Peripheral blood was withdrawn from severely injured trauma patients (TP; n = 15, ISS ≥ 16) within the first 12 h post-trauma and from healthy volunteers (HV; n = 15) and stimulated with fMLP and PMA. CD16dimCD62Lbright (immature), CD16brightCD62Lbright (mature) and CD16brightCD62Ldim (CD62Llow) neutrophil subsets and CD14brightCD16− (classical), CD14brightCD16+ (intermediate) and CD14dimCD16+ (non-classical) monocyte subsets of HV and TP were either directly analyzed by flow cytometry or the examined subsets of HV were sorted first by fluorescence-activated cell sorting and subsequently analyzed. Subset-specific generation of reactive oxygen species (ROS) and of E. coli bioparticle phagocytosis were evaluated. Results: In TP, the counts of immature neutrophils were significantly increased vs. HV. The numbers of mature and CD62Ldim neutrophils remained unchanged but the production of ROS was significantly enhanced in TP vs. HV and the stimulation with fMLP significantly increased the generation of ROS in the mature and CD62Ldim neutrophils of HV. The counts of phagocyting neutrophils did not change but the mean phagocytic capacity showed an increasing trend in TP. In TP, the monocytes shifted toward the intermediate phenotype, whereas the classical and non-classical monocytes became less abundant. ROS generation was significantly increased in all monocyte subsets in TP vs. HV and PMA stimulation significantly increased those level in both, HV and TP. However, the PMA-induced mean ROS generation was significantly lower in intermediate monocytes of TP vs. HV. Sorting of monocyte and neutrophil subsets revealed a significant increase of ROS and decrease of phagocytic capacity vs. whole blood analysis. Conclusions: Neutrophils and monocytes display a phenotypic shift following severe injury. The increased functional abnormalities of certain subsets may contribute to the dysbalanced immune response and attenuate the antimicrobial function and thus, may represent a potential therapeutic target. Further studies on isolated subsets are necessary for evaluation of their physiological role after severe traumatic injury.

Systemic immune response in young and elderly patients after traumatic brain injury

“…In contrast with Janicova's study [73], we did not detect changes in either the intermediate CD14 + CD16 + or classical CD14 hi CD16-monocyte populations. The different type of sample (fresh whole blood vs thawed PBMC), and the different score of injury (severe TBI vs severe, moderate, and mild TBI), could account for the differences observed between the study performed by Janicova and colleagues [73] and our investigation. Also, the different sample timing (within the rst 12 h post-injury vs a media of 21h) was shown to be a fundamental aspect when considering immune trauma-induced changes [18].…”

The peripheral and decidual immune cell profiles in women with recurrent pregnancy loss

“…CD45 + cells were further differentiated into neutrophilic and eosinophilic granulocytes (SSC hi ) and PBMC (SSC lo ). Peripheral blood neutrophils were homogeneous and express FcγRIII (CD16) and L-selectin (CD62L) within a narrow range, typically characterized as CD16 bright CD62L bright (mature), CD16 dim CD62L bright (immature), CD16 dim CD62L dim (apoptotic) neutrophils ( 22 ). L-selectin(CD62L) can account for impaired rolling and migration ability of leukocytes ( 23 ).…”

Burn-Induced Local and Systemic Immune Response: Systematic Review and Meta-Analysis of Animal Studies

“…Although monocyte or macrophage subtypes could not be investigated, we found that total wound macrophage numbers were increased and that the production of inflammatory mediators by macrophages was enhanced. Activity of neutrophils is altered after severe trauma in animals (Baskaran et al 2000;Janicova et al 2021;Leliefeld et al 2016;Mortaz et al 2018), but it remains unclear whether trauma in general enhances or weakens neutrophil activity (Figure 5). Presumably, the emergency-release of neutrophils into the circulation is responsible for reduced chemotactic activity due to inflexibility of the banded nucleus of immature neutrophils (Drifte et al 2013), while rapid activation can lead to impaired antibacterial activity (Leliefeld et al 2016).…”