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Inadequate cytoplasmatic calcium signals in alveolar macrophages after cardiac surgery
Katharina Berger1, Michael Sander, Anke Kohlar
1Department of Anesthesiology and Intensive Care Medicine, Charité-Universitätsmedizin Berlin, Berlin, Germany.
Objective And Design:
Patients undergoing cardiac surgery have an elevated risk for pulmonary complications. A dysfunction of alveolar macrophages (AM) might promote postoperative infections. Therefore intracellular calcium [Ca(2+)](i) as an important second messenger in cellular signaling was assessed in AM.
Materials And Methods:
Twelve patients undergoing elective coronary artery bypass graft surgery (CABG) were enrolled in this clinical trial. After anesthesia induction and 2 h after cardiopulomary bypass (CPB) declamping, the bronchoalveolar lavage (BAL) fluid was collected preoperatively from the right middle lobe and postoperatively from the left lingula of the lung. Cell subpopulations and [Ca(2+)](i) signals were assessed via flow cytometry. To express the changes of [Ca(2+)](i) signals the Fluo4/FuraRed-Ratio was used.
Results:
After surgery the [Ca(2+)](i) baseline in unstimulated AMs were significantly reduced (p < 0.001). A significant signal reduction after fMLP (p = 0.021) and C5a (p = 0.028) stimulation was found in FSC high AMs after surgery, even though all populations showed a trend of less responsiveness.
Conclusion:
We suggest that the reduced [Ca(2+)](i) signaling in postoperative AMs is caused by a reduced coupling to membrane channels. These preliminary data suggest an inadequate [Ca(2+)](i) signal of AM after surgery, which may contribute to a local immune dysfunction in the lung.
Insights
Cardiac surgery impairs alveolar macrophage function by reducing intracellular calcium signaling, potentially increasing postoperative lung infection risk. This study assessed calcium signals in macrophages before and after surgery.
Area of Science:
- Immunology
- Cellular Biology
- Cardiothoracic Surgery
Background:
- Patients undergoing cardiac surgery face heightened risks of pulmonary complications.
- Alveolar macrophage (AM) dysfunction may contribute to postoperative infections.
- Intracellular calcium ([Ca(2+)](i)) is a critical second messenger in cellular signaling.
Purpose of the Study:
- To assess intracellular calcium ([Ca(2+)](i)) signaling in alveolar macrophages (AMs) from patients before and after cardiac surgery.
- To investigate the potential link between AM dysfunction and postoperative pulmonary complications.
Main Methods:
- Clinical trial involving 12 patients undergoing coronary artery bypass graft (CABG) surgery.
- Bronchoalveolar lavage (BAL) fluid collected preoperatively and postoperatively.
- Flow cytometry used to assess AM subpopulations and [Ca(2+)](i) signals via the Fluo4/FuraRed-Ratio.
Main Results:
- A significant reduction in baseline [Ca(2+)](i) in unstimulated AMs was observed post-surgery (p < 0.001).
- AMs showed significantly reduced signal responses to fMLP (p = 0.021) and C5a (p = 0.028) stimulation after surgery.
- A trend towards reduced responsiveness was noted across all AM populations post-surgery.
Conclusions:
- Reduced [Ca(2+)](i) signaling in postoperative AMs may stem from impaired coupling to membrane channels.
- Preliminary findings suggest inadequate AM [Ca(2+)](i) signaling post-surgery, potentially leading to local immune dysfunction in the lungs.
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