Key result
At 3 months after cardiopulmonary bypass, monocytes continued to express a macrophage-like milieu associated with persistent activation of the PU.1/M-CSF pathway and decreased methylation of the PU.1 promoter region.
Why the study?
Does cardiopulmonary bypass surgery induce persistent macrophage-like characteristics and epigenetic changes in circulating monocytes in patients undergoing non-emergency heart surgery?
Observational (n=20)
No
Does cardiopulmonary bypass surgery induce persistent macrophage-like characteristics and epigenetic changes in circulating monocytes in patients undergoing non-emergency heart surgery?
Cardiopulmonary bypass induces a persistent, acquired immunological imbalance in monocytes lasting at least 3 months, driven by epigenetic over-activation of the PU.1/M-CSF pathway.
Monocyte macrophage-like traits may persist 3 months post-bypass; leaves open clinical relevance and need for larger prospective studies.
BACKGROUND: It has been shown that severe insult to the immune system may trigger prolonged macrophage characteristics associated with excessive release of monocyte colony stimulating factor (M-CSF). However, it is unclear how persistent is the macrophage-like characteristics in circulating monocytes (MO). In this study, 20 patients who underwent non-emergent cardiopulmonary bypass had their monocytes characterized before surgery and 3 months after surgery. METHODS: We assessed the macrophage characteristics of MO using cytokine production, surface marker expression, an ability to stimulate T cells, and methylation of the promoter region of the gene encoding PU.1, a critical component to M-CSF production. MO function as well as activation and differentiation potential were longitudinally assessed. RESULTS: At 3 months after cardiopulmonary bypass, monocytes exhibited increased expression of MRP8, transforming growth factor-β/latency-associated peptide, suppressor of cytokine signaling 3 while phagocytic properties were increased. Concomitantly, we observed a decreased expression of CD86, a decreased ability to form regulatory dendritic cells, and a diminished ability to stimulate T cells. These characteristics were accompanied by a persistent increase in the secretion of M-CSF, over-activation of PU.1, and decreased methylation of the PU.1 promoter region. Serum levels of C-reactive protein and anti-cytomegalovirus IgG antibody titers were also elevated in some patients at 3 months after surgery. CONCLUSIONS: We concluded that at 3 months after cardiopulmonary bypass, monocytes continued to express a new macrophage-like milieu that was associated with the persistent activation of the PU.1/M-CSF pathway.
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Laudański et al. (2018) conducted an observational in Patients undergoing non-emergent heart surgery with cardiopulmonary bypass (n=20). Cardiopulmonary bypass (CPB) surgery vs. Pre-surgery baseline was evaluated on Macrophage characteristics of monocytes (MO) including PU.1/M-CSF pathway activation and SPI1 methylation at 3 months post-surgery. At 3 months after cardiopulmonary bypass, monocytes continued to express a macrophage-like milieu associated with persistent activation of the PU.1/M-CSF pathway and decreased methylation of the PU.1 promoter region.
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