PD-L1 regulates inflammatory programs of macrophages from human pluripotent stem cells

Abstract

<p>Programmed death ligand 1 (PD-L1) serves as a pivotal immune checkpoint in both the innate and adaptive immune systems. PD-L1 is expressed in macrophages in response to IFNγ. We examined whether PD-L1 might regulate macrophage development. We established PD-L1 KO (<em>CD274</em>^<em>-/-</em>) human pluripotent stem cells and differentiated them into macrophages and observed a 60% reduction in CD11B⁺CD45⁺ macrophages in <em>CD274</em>^<em>-/-</em>; this was orthogonally verified, with the PD-L1 inhibitor BMS-1166 reducing macrophages to the same fold. Single-cell RNA sequencing further confirmed the down-regulation of the macrophage-defining transcription factors <em>SPI1</em> and <em>MAFB</em>. Furthermore, <em>CD274</em>^<em>-/-</em> macrophages reduced the level of inflammatory signals such as NF-κB and TNF, and chemokine secretion of the CXCL and CCL families. Anti-inflammatory TGF-β was up-regulated. Finally, we identified that <em>CD274</em>^<em>-/-</em> macrophages significantly down-regulated interferon-stimulated genes despite the presence of IFNγ in the differentiation media. These data suggest that PD-L1 regulates inflammatory programs of macrophages from human pluripotent stem cells.</p>