ClinOleic Impairs ROS Production and Phagocytosis in M1 Macrophages Without Affecting M1 Differentiation

Lipid emulsions are the primary source of calories and fatty acids that are used to provide essential energy and nutrients to patients suffering from severe intestinal failure and critical illness. However, their use has been linked to adverse effects on patient outcomes, notably affecting immune defenses and inflammatory responses. ClinOleic is a lipid emulsion containing a mixture of olive oil and soybean oil (80:20). The effect of ClinOleic on the differentiation of M1 macrophages remains unclear. In this study, we isolated human monocytes and added ClinOleic to differentiation culture media to investigate whether it affects monocyte polarization into M1 macrophages and macrophage functions, such as reactive oxygen species (ROS) production and phagocytosis. ROS production was stimulated by live S. aureus and detected with L-012, a chemiluminescence emission agent. Phagocytic capacity was assayed using pHrodo™ Green S. aureus Bioparticles^® Conjugate. We found that M1 cell morphology, surface markers (CD80 and CD86), and M1-associated cytokines (TNF-α and IL-6) did not significantly change upon incubation with ClinOleic during M1 polarization. However, S. aureus-triggered ROS production was significantly lower in M1 macrophages differentiated with ClinOleic than in those not treated with ClinOleic. The inhibitory effect of ClinOleic on macrophage function also appeared in the phagocytosis assay. Taken together, these findings reveal that ClinOleic has a limited impact on the M1 differentiation phenotype but obviously reduces ROS production and phagocytosis.