Nrf2 attenuates the innate immune response after experimental myocardial infarction

There is compelling evidence implicating dysregulated inflammation in the mechanism of ventricular remodeling and heart failure (HF) after MI. The transcription factor nuclear factor erythroid-derived 2-like 2 (Nrf2, encoded by Nfe2l2) is a promising target in this context since it impedes transcriptional upregulation of pro-inflammatory cytokines and is anti-inflammatory in various murine models.

We aimed to investigate the contribution of Nrf2 to the inflammatory response after experimental myocardial infarction (MI).

We subjected Nrf2^-/- mice and wild type (WT) controls to permanent left coronary artery (LCA) ligation. The inflammatory response was investigated with fluorescence-activated cell sorting (FACS) analysis of peripheral blood and heart cell suspensions, together with qRT-PCR of infarcted tissue for chemokines and their receptors. To investigate whether Nrf2-mediated transcription is a dedicated function of leukocytes, we interrogated publicly available RNA-sequencing (RNA-seq) data from mouse hearts after permanent LCA ligation for Nrf2-regulated gene (NRG) expression.

FACS analysis demonstrated a profoundly inflamed phenotype in the hearts of global Nrf2^-/- mice as compared to WT mice after MI. Moreover, infarcted tissue from Nrf2^-/- mice displayed higher expression of mRNA coding for inflammatory cytokines, chemokines, and their receptors, including IL-6, Ccl2, and Cxcr4. RNA-seq analysis showed upregulated NRG expression in WT mice after MI compared to naive mice, which was significantly higher in bioinformatically isolated CCR2⁺ cells.

Taken together, the results suggest that Nrf2 signalling in leukocytes, and possibly CCR2⁺ monocytes and monocyte-derived cardiac resident macrophages, may be potential targets to prevent post-MI ventricular remodeling.