Article
Peripheral blood monocyte aquire distinct polarisation and activation states in response to aneurysmal subarachnoid haemorrhage
Periphere Blutmonozyten polarisieren zu bestimmten Polarisations- und Aktivierungszustände nach einer aneurysmatischer Subarachnoidalblutung
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Authors
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Sajjad Muhammad
- University of Helsinki and Helsinki University Hospital, Helsinki, Finland; Universitätsklinikum Bonn, Neurosurgery, Bonn, Deutschland
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Thomas M. Kinfe
- Universitätsklinikum Bonn, Neurochirurgie, Bonn, Deutschland
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Alf Lamprecht
- Universität Bonn, Pharmazeutisches Institut, Bonn, Deutschland
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Shafqat Rasul Chaudhry
- Universitätsklinikum Bonn, Neurosurgery, Bonn, Deutschland; University of Bonn, Department of Pharmaceutics, Bonn, Deutschland
| Published: | May 8, 2019 |
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Outline
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Objective: Despite medical and surgical advancement, aneurysmal subarachnoid hemorrhage (aSAH) is still associated with high mortality and morbidity. Recent investigations reveal a critical role of inflammation during the phase of early and delayed brain injury after aSAH. Monocytes are important players to drive or inhibit inflammation that in turn depends on their polarization status. However, monocyte polarization and their activation states after aSAH have not been investigated in detail. Here, we investigate monocyte subsets such as classical (CD14++CD16-), intermediate (CD14+CD16+) and non-classical (CD14+CD16++) along with their activation markers such as CX3CRI, CCR2 and HLA-DR.
Methods: Peripheral venous blood anticoagulated with EDTA was collected from 15 aSAH patients at day 1 and day 7, and once from healthy controls. After erythrocyte lysis and 1 million leukocytes in 100 µL of FACS buffer were stained with specific anti-human mouse monoclonal antibodies for 20 mins at 4 C. Cells were washed and final volume was adjusted to 500 µL. Cells were then acquired on LSR Fortessa (BD Biosciences, CA, USA). Monocytes were gated based on their intermediate side scatter and CD45 expression. Monocyte subsets were characterized based on differential CD14 and CD16 expression, and then were further quantified for specific activation markers.
Results: Non-classical monocytes were significantly decreased in patients after aSAH as compared to healthy controls at day 1. On the other hand intermediate monocytes were significantly elevated at post-SAH day 1 compared to day 7. The CX3CR1+ intermediate and non-classical monocytes showed the similar significant differences as that of their parent populations. Intriguingly, classical CCR2+ monocytes significantly were elevated on post-SAH day 1 as compared to controls and intermediate CCR2+ monocytes compared to post-SAH day 7. Finally, HLA-DR+ classical monocytes were significantly reduced after aSAH at both day 1 and day 7 compared to controls, while intermediate and non-classical HLA-DR+ monocytes showed significant differences as that of their parent populations
Conclusion: Different monocyte subsets are differently polarized during early and delayed brain injury after aSAH with distinct profiles of their activation markers. Specific sub-sets of monocytes can influence the occurence of post SAH complications and clinical outcome.
