Damage-associated molecular patterns induce macrophage polarization toward an M1 pro-inflammatory phenotype

Dying cells release Damage-Associated Molecular Patterns (DAMPs) that can initiate and perpetuate sterile inflammatory responses. However, the effect of DAMPs on macrophages biology remains unclear. We therefore studied the effect of DAMPs on primary peritoneal macrophages (PPM) in vitro. We first performed unbiased transcriptomic profiling with RNA-seq of PPMs cultured for up to 72 hours in the presence and absence of: 1) liposaccharide (LPS), which is known to provoke an “M1” phenotype, 2) IL-4, which is known to provoke an “M2” phenotype, or 3) cytosolic extracts (CEs) from necrotic H9C2 cells to mimic the release of cardiomyocyte DAMPs. We found that the transcriptional profile of PPMs stimulated with CEs resembled the transcriptional profile of PPMs stimulated with LPS. All primary peritoneal macrophages were derived from the same initial isolate (pooled from multiple mice). Three to four replicates of each timepoint and condition were used for RNA extraction, RNAseq library preparation with Diagenode CATS procedures, and single-end 50 bp Illumina sequencing.