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Medical AI Inquiry: You was designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.  Labels: BACKGROUND, OBJECTIVE, RESULTS. Meshes: Anti-Inflammatory Agents, Atherosclerosis, Cholesterol, Culture Media, Serum-Free, Foam Cells, Gene Expression Regulation, Humans, Inflammation, Interferon-gamma, Interleukin-1beta, Interleukin-4, Lipopolysaccharides, Macrophage Colony-Stimulating Factor, Macrophages, NF-kappa B, Phenotype, Up-Regulation.
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Does conversion of human M-CSF macrophages into foam cells reduce their proinflammatory responses to classical M1-polarizing activation? Context: In atherosclerotic lesions, cholesterol-laden macrophage foam cells are formed and exposed to M1- and M2-polarizing factors. However, the effects of the polarizing factors on the proinflammatory and the anti-inflammatory potential of foam cells are not known. To investigate the effects of M1- and M2-polarizing factors on the expression of pro- and anti-inflammatory genes in cultured human macrophage foam cells. Human monocytes were differentiated into macrophages in the presence of M-CSF, and then converted into cholesterol-loaded foam cells by incubation with acetylated LDL. The generated macrophages and foam cells were polarized into the M1 phenotype by classical activation with LPS and IFN-γ, or into the M2 phenotype by alternative activation with IL-4. When subjected to the M1-polarizing factors, the macrophages responded by typical upregulation of several key proinflammatory genes (TNFA, IL1B, CXCL8, CCL19, and COX2), while the anti-inflammatory genes (MRC1, CCL17, and IL10) displayed variable responses. The foam cells, again, showed a weaker response to the M1-polarizing factors, as indicated by reduced upregulation of the proinflammatory genes, reduced secretion of TNF-α, and a trend towards lower NF-κB activity. When subjected to alternative M2 polarization, both macrophages and foam cells responded by a typical upregulation of the anti-inflammatory genes, which was of equal magnitude in both cell types.
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Conversion of cultured human macrophages into foam cells suppresses their proinflammatory responses to M1-polarizing factors. Thus, in M1-polarizing microenvironments of atherosclerotic lesions, foam cell formation may locally weaken the macrophage-dependent inflammatory component of atherogenesis. Final Decision: yes