The STATus of PD-L1 (B7-H1) on tolerogenic APCs.
Expression by DCs of co-inhibitory molecules such as programmed death ligand-1 (PD-L1/B7-H1/CD274), a member of the B7 superfamily, is crucial for the downregulation of T-cell responses and the maintenance of immune homeostasis. Exposure of immature DCs to danger-associated molecular patterns (DAMPS) or pathogen-associated molecular patterns (PAMPs) generally results in their maturation and acquisition of immunostimulatory function. However, exposure of DCs to TLR ligands early during their differentiation can inhibit further differentiation and confer tolerogenic properties on these APCs. A report in this issue of The European Journal of Immunology reveals that early inhibition of human DC differentiation from blood monocytes by TLR agonists is associated with a tolerogenic phenotype and Treg generation. The tolerogenic function of these APCs is dependent on MAPK-induced IL-6 and IL-10 production, which drives STAT-3-mediated PD-L1 expression. These observations link IL-10 and IL-6 to PD-L1 expression, providing a new dimension to the anti-inflammatory properties of these cytokines. These findings also have implications for understanding the inherent function of DCs in non-lymphoid tissues such as the liver and lung, where they are exposed to PAMPs that are found constitutively in the local microenvironment.
Department of Dermatology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA.
Tina L
TL
Sumpter
Angus W
AW
Thomson
D000938:Antigen-Presenting Cells / Q000166:cytology / Q000276:immunology* / Q000378:metabolism*; D015703:Antigens, CD / Q000502:physiology*; D051017:Apoptosis Regulatory Proteins / Q000502:physiology; D060890:B7-H1 Antigen; D002454:Cell Differentiation / Q000187:drug effects / Q000276:immunology; D003713:Dendritic Cells / Q000166:cytology / Q000276:immunology; D005786:Gene Expression Regulation / Q000276:immunology*; D006801:Humans; D007108:Immune Tolerance / Q000502:physiology*; D016753:Interleukin-10 / Q000378:metabolism; D015850:Interleukin-6 / Q000378:metabolism; D018950:Lipopolysaccharide Receptors / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D018448:Models, Immunological; D009000:Monocytes / Q000166:cytology / Q000276:immunology; D061026:Programmed Cell Death 1 Receptor; D050796:STAT3 Transcription Factor / Q000378:metabolism*; D015398:Signal Transduction / Q000276:immunology*; D016176:T-Lymphocyte Subsets / Q000276:immunology; D050378:T-Lymphocytes, Regulatory / Q000276:immunology; D051193:Toll-Like Receptors / Q000819:agonists
D015703:Antigens, CD; D051017:Apoptosis Regulatory Proteins; D060890:B7-H1 Antigen; C423236:CD274 protein, human; C508609:IL10 protein, human; C508600:IL6 protein, human; D015850:Interleukin-6; D018950:Lipopolysaccharide Receptors; C105992:PDCD1 protein, human; D061026:Programmed Cell Death 1 Receptor; D050796:STAT3 Transcription Factor; C494086:STAT3 protein, human; D051193:Toll-Like Receptors; D016753:Interleukin-10; D020928:Mitogen-Activated Protein Kinases