Transcriptional regulation of macrophage arginase 1 expression and its role in atherosclerosis.

Atherosclerosis results from a metabolic imbalance and chronic arterial inflammation and macrophages are key during the initiation and progression of atherosclerotic lesions. A number of macrophage subsets have been identified in atherosclerotic plaques. Arginase 1 (Arg1), a marker for the M2 anti-inflammatory subset, hydrolyzes l-arginine into urea and ornithine, a precursor to l-proline and polyamines, which are implicated in tissue repair and wound healing. Additionally, Arg1 inhibits nitric oxide-mediated inflammatory pathways by competing with iNOS for the same substrate, l-arginine. Therefore, changes in Arg1 expression in macrophages may affect the development of atherosclerosis. Here, we present an overview of the transcriptional regulation of macrophage Arg1, focusing on the nuclear receptor family of ligand-activated transcription factors, and the relevance of this regulation to atherosclerosis.