title: Regulation of PD-1, PD-L1, and PD-L2 expression during normal and autoimmune responses.
abstract: Newer members of the B7-CD28 superfamily include the receptor PD-1 and its two ligands, PD-L1 and PD-L2. Here, we characterize the expression of PD-1, PD-L1, and PD-L2 in tissues of naive miceand in target organs from two models of autoimmunity, the pancreas from non-obese diabetic (NOD) mice and brain from mice with experimental autoimmune encephalomyelitis (EAE). In naive mice, proteiexpression of PD-1, PD-L1, and PD-L2 was detected in the thymus, while PD-1 and PD-L1 were detected in the spleen. PD-L1, but not PD-L2, was also detected at low levels on cardiac endothelium, pancreatic islets, and syncyciotrophoblasts in the placenta. In pre-diabetic NOD mice, PD-1 and PD-L1 were expressed on infiltrating cells in the pancreatic islets. Furthermore, PD-L1 was markedly up-regulated on islet cells. In brains from mice with EAE, PD-1, PD-L1, and PD-L2 were expressed on infiltrating inflammatory cells, and PD-L1 was up-regulated on endothelium within EAE brain. The distinct expression patterns of PD-L1 and PD-L2 led us to compare their transcriptional regulation in STAT4(-/-), STAT6(-/-), or NF-kappaB p50(-/-)p65(+/-) dendritic cells (DC).PD-L2, but not PD-L1, expression was dramatically reduced in p50(-/-)p65(+/-) DC. Thus, PD-L1 and PD-L2 exhibit distinct expression patterns and are differentially regulated on the transcriptional level.
mesh_terms: D000818:Animals; D000954:Antigens, Surface / Q000032:analysis*; D051017:Apoptosis Regulatory Proteins; D001327:Autoimmune Diseases / Q000378:metabolism*; D018122:B7-1 Antigen; D060890:B7-H1 Antigen; D001798:Blood Proteins / Q000032:analysis*; D016466:CHO Cells; D006224:Cricetinae; D004681:Encephalomyelitis, Autoimmune, Experimental / Q000378:metabolism; D018858:Germinal Center / Q000737:chemistry; D008562:Membrane Glycoproteins; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D016688:Mice, Inbred NOD; D016328:NF-kappa B / Q000502:physiology; D010455:Peptides / Q000032:analysis*; D061027:Programmed Cell Death 1 Ligand 2 Protein; D061026:Programmed Cell Death 1 Receptor; D050800:STAT6 Transcription Factor; D013154:Spleen / Q000737:chemistry; D013950:Thymus Gland / Q000737:chemistry; D015534:Trans-Activators / Q000502:physiology; D014162:Transfection; D015854:Up-Regulation
chemical_list: D000954:Antigens, Surface; D051017:Apoptosis Regulatory Proteins; D018122:B7-1 Antigen; D060890:B7-H1 Antigen; D001798:Blood Proteins; C498919:Cd274 protein, mouse; D008562:Membrane Glycoproteins; D016328:NF-kappa B; C491383:Pdcd1 protein, mouse; C556978:Pdcd1lg2 protein, mouse; D010455:Peptides; D061027:Programmed Cell Death 1 Ligand 2 Protein; D061026:Programmed Cell Death 1 Receptor; D050800:STAT6 Transcription Factor; C494100:Stat6 protein, mouse; D015534:Trans-Activators