Abstract 123: The Immunoproteasome Does Not Influence Macrophage Differentiation but Survival of Differentiated Macrophages
Background: Atherosclerosis is an inflammatory disease with T cells and macrophages as the leading plaque cell populations. The immunoproteasome (IP) influences T cell survival and differentiation but its impact on macrophage survival and differentiation remains unknown, which was the objective of this study.
Methods: Murine monocyte/macrophage Raw264.7 cells were stimulated by IFN-gamma (20 ng/mL) plus LPS (10pg/mL) or IL-4 (20 ng/mL) for 18 hours to induce M1 and M2 macrophages, and these differentiated macrophages were then re-exposed to IFN- gamma and IL-4 for another 24 hours, without and with IP subunit beta 5i inhibition by siRNA or Onx0914. Nitric oxide synthase and arginase activity served as differentiation markers (analyzed by enzymatic assays) as did the cytokine/chemokine profile (analyzed by antibody arrays). Cell viability was tested by an XTT assay and apoptosis by TUNEL FACS.
Results: IP beta5i knockout/inhibition did not influence M1 and M2 macrophage differentiation. Also, no significant differences in apoptosis were observed between RAW264.7 cells treated with and without beta 5i inhibitor during macrophage differentiation. With re-exposure to IFN- gamma and IL-4, however, there was more apoptosis and less survival of differentiated M1 macrophages with beta5i inhibition. Conversely, beta 5i inhibition achieved less apoptosis and more survival of differentiated M2 macrophages when switching IL-4- to IFN-gamma-stimulating conditions.
Conclusions: IP inhibition does not influence macrophage differentiation but survival of differentiated macrophages of potential significance for the atherosclerotic disease process.
Author Disclosures: F. Wang: None. L. Nesbitt: None. A. Lerman: None. J. Herrmann: None.
- © 2015 by American Heart Association, Inc.