Kruppel-like factor 2-mediated suppression of microRNA-155 reduces the proinflammatory activation of macrophages

Abstract

Objective Recent evidence indicates that significant interactions exist between Kruppel-like factor 2 (KLF2) and microRNAs (miRNAs) in endothelial cells. Because KLF2 is known to exert antiinflammatory effects and inhibit the pro-inflammatory activation of monocytes, we sought to identify how inflammation-associated miR-155 is regulated by KLF2 in macrophages. Approach and Results Peritoneal macrophages fromwild-type (WT) C57Bl/6 mice were transfected with either recombinant adenovirus vector expressing KLF2 (Ad-KLF2) or siRNA targeting KLF2 (KLF2- siRNA) for 24 h-48 h, then stimulated with oxidized low-density lipoproteins (ox-LDL, 50 ìg/mL) for 24 h. Quantitative real-time polymerase chain reaction showed that KLF2markedly reduced the expression ofmiR-155 in quiescent/ox-LDL-stimulatedmacrophages.We also found that the increased expression of miR-155, monocyte chemoattractant protein (MCP-1) and interleukin (IL)-6 and the decreased expression of the suppressor of cytokine signaling (SOCS)-1 and IL-10 in ox-LDL-treated macrophages were significantly suppressed by KLF2.Most importantly, over-expression ofmiR-155 could partly reverse the suppressive effects of KLF2 on the inflammatory response ofmacrophages. Conversely, the suppression of miR-155 in KLF2 knockdown macrophages significantly overcame the pro-inflammatory properties associated with KLF2 knockdown. Finally, Ad-KLF2 significantly attenuated the diet-induced formation of atherosclerotic lesions in apolipoprotein E-deficient (apoE-/-) mice, which was associated with a significantly reduced expression ofmiR-155 and its relative inflammatory cytokine genes in the aortic arch and inmacrophages. Conclusion KLF2-mediated suppression of miR-155 reduced the inflammatory response of macrophages. Copyright: