Artikel
Porcine neutrophil activation and phenotypes in blood and bone marrow in a model of trauma surgery
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Veröffentlicht: | 5. Oktober 2015 |
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Objectives: Activation and migration of polymorphonuclear neutrophils (PMNs) are key mechanisms in the development of ARDS and MODS. The bone marrow (BM) plays an important role in these processes by the mobilization of young neutrophils in response to tissue damage. We recently identified three PMN subsets with different function capacities in trauma patients. These subsets were identified by the differences in the membrane expression of CD16 (FcyRIII) and CD62L (L-selectin). We further identified important similarities in human and porcine PMN subsets.
Therefore we aimed to test the feasability of a porcine model to perform proof-of principle studies for novel immunomodulatory interventions for trauma patients. To do so the goal of this study was to describe the early neutrophil response to trauma surgery in both the bone marrow and peripheral blood of pigs.
Methods: Large male pigs were subjected to extensive trauma surgery for the duration of 3 hours. Blood and bone marrow samples were collected at baseline and after 3 hours of trauma surgery. The receptor expression of CD11b (Mac-1), CD16 (FcyRIII), CD32 (FcyRII), CD62L (L-selectin), CD49D (VLA-4) and CD184 (CXCR4) was measured by flowcytometry. Neutrophils were identified according their forward/sideward scatter characteristics, as well as the expression of specific Swine Workshop Cluster-antibodies 1,3 and 8. Neutrophil phenotypes were identfied by the receptor expression of CD16 and CD62L. We compared the activation status as well as the presence of neutrophil subsets between baseline and after surgery in both blood and bone marrow PMN populations.
Results and Conclusion: All experimental animals survived three hours of surgery. Absolute leucocyte count dropped significantly over time. Flowcytometry revealed a significant increase of CD11b expression and a decrease of CD62L expression of the neutrophil population in blood over time. Furthermore, in line with the human situation, the percentage of neutrophil subsets (identified by CD16/CD62L expression profiles) increased significantly during the three hours of trauma surgery. Cell sorting of the PMN subsets showed comparable morphological characteristics as human PMN subsets and also the co-expression of activation markers was comparable. Moreover, a profound bone marrow response was observed.
Therefore in line with the human situation, extensive trauma surgery in pigs results in transient activation of neutrophils in peripheral blood. Furthermore, we were the first to identify different neutrophil phenotypes in peripheral blood of pigs in response to extensive trauma surgery. These porcine PMN subsets have similar morphological characteristics, activation profiles and kinetics of mobilization in peripheral blood as their human counterparts. Besides the neutrophil changes in peripheral blood, also comparable changes in BM-PMNs were encountered. This makes the porcine model of trauma surgery very suitable for proof-of-principle interventions with novel therapeutic strategies for trauma