The transcriptional PPARβ/δ network in human macrophages defines a unique agonist-induced activation state

T Adhikary, A Wortmann, T Schumann… - Nucleic acids …, 2015 - academic.oup.com
T Adhikary, A Wortmann, T Schumann, F Finkernagel, S Lieber, K Roth, PM Toth…
Nucleic acids research, 2015academic.oup.com
Peroxisome proliferator-activated receptor β/δ (PPARβ/δ) is a lipid ligand-inducible
transcription factor with established metabolic functions, whereas its anti-inflammatory
function is poorly understood. To address this issue, we determined the global PPARβ/δ-
regulated signaling network in human monocyte-derived macrophages. Besides cell type-
independent, canonical target genes with metabolic and immune regulatory functions we
identified a large number of inflammation-associated NFκB and STAT1 target genes that are …
Abstract
Peroxisome proliferator-activated receptor β/δ (PPARβ/δ) is a lipid ligand-inducible transcription factor with established metabolic functions, whereas its anti-inflammatory function is poorly understood. To address this issue, we determined the global PPARβ/δ-regulated signaling network in human monocyte-derived macrophages. Besides cell type-independent, canonical target genes with metabolic and immune regulatory functions we identified a large number of inflammation-associated NFκB and STAT1 target genes that are repressed by agonists. Accordingly, PPARβ/δ agonists inhibited the expression of multiple pro-inflammatory mediators and induced an anti-inflammatory, IL-4-like morphological phenotype. Surprisingly, bioinformatic analyses also identified immune stimulatory effects. Consistent with this prediction, PPARβ/δ agonists enhanced macrophage survival under hypoxic stress and stimulated CD8+ T cell activation, concomitantly with the repression of immune suppressive target genes and their encoded products CD274 (PD-1 ligand), CD32B (inhibitory Fcγ receptor IIB) and indoleamine 2,3-dioxygenase 1 (IDO-1), as well as a diminished release of the immune suppressive IDO-1 metabolite kynurenine. Comparison with published data revealed a significant overlap of the PPARβ/δ transcriptome with coexpression modules characteristic of both anti-inflammatory and pro-inflammatory cytokines. Our findings indicate that PPARβ/δ agonists induce a unique macrophage activation state with strong anti-inflammatory but also specific immune stimulatory components, pointing to a context-dependent function of PPARβ/δ in immune regulation.
Oxford University Press