Silencing of CD40 in vivo reduces progression of experimental atherogenesis through an NF-κB/miR-125b axis and reveals new potential mediators in the pathogenesis of atherosclerosis.

Background And Aims: CD40/CD40L signaling exerts a critical role in the development of atherosclerosis, and microRNAs (miRNAs) are key regulators in vascular inflammation and plaque formation. In this work, we investigated mRNA/miRNA expression during progression of atherosclerotic lesions through CD40 silencing.

Methods: We silenced CD40 with a specific siRNA in ApoE mice and compared expression of mRNA/miRNA in ascending aorta with scrambled treated mice.

Results: siRNA-CD40 treated mice significantly reduced the extension and severity of atherosclerotic lesions, as well as the number of F4/80, galectin-3 macrophages and NF-κB cells in the intima. Genome-wide mRNA/miRNA profiling allowed the identification of transcripts, which were significantly upregulated during atherosclerosis; among them, miR-125b and miR-30a, Xpr1, a regulator of macrophage differentiation, Taf3, a core transcription factor and the NF-κB activator Ikkβ, whereas, the NF-κB inhibitor Ikbα was downregulated during disease progression. All those changes were reversed upon CD40 silencing. Interestingly, TAF3, XPR1 and miR-125b were also overexpressed in human atherosclerotic plaques. Murine Taf3 and Xpr1 were detected in the perivascular adipose tissue (PVAT), and Taf3 also in intimal foam cells. Finally, expression of miR-125b was regulated by the CD40-NF-κB signaling axis in RAW264.7 macrophages.

Conclusions: CD40 silencing with a specific siRNA ameliorates progression of experimental atherosclerosis in ApoE mice, and evidences a role for NF-κB, Taf3, Xpr1, and miR-125b in the pathogenesis of atherosclerosis.