Blocking programmed death-1 ligand-PD-1 interactions by local gene therapy results in enhancement of antitumor effect of secondary lymphoid tissue chemokine.
The negative signal provided by interactions of programmed death-1 (PD-1) and its ligands, costimulatory molecules PD-L1 (also B7-H1) and PD-L2 (also B7-DC), is involved in the mechanisms of tumor immune evasion. In this study, we found that this negative signal was also involved in immune evasion in tumor immunotherapy. When we used different doses of a constructed eukaryotic expression plasmid, pSLC, which expresses functional murine secondary lymphoid tissue chemokine (SLC, CCL21), to treat BALB/c mice inoculated with H22 murine hepatoma cells, the inhibitory effect was enhanced along with the increase of pSLC dosage. Unexpectedly, however, the best complete inhibition rate of tumor was reached when pSLC was used at the dosage of 50 microg but not 100 or 200 microg. RT-PCR and real-time PCR revealed that both PD-L1 and PD-L2 genes were expressed in tumor and vicinal muscle tissues of tumor-bearing mice and the expression level was significantly increased if a higher dosage of pSLC was administered. We then constructed a eukaryotic expression plasmid (pPD-1A) that expresses the extracellular domain of murine PD-1 (sPD-1). sPD-1 could bind PD-1 ligands, block PD-Ls-PD-1 interactions, and enhance the cytotoxicity of tumor-specific CTL. Local gene transfer by injection of pPD-1A mediated antitumor effect and improved SLC-mediated antitumor immunity. The combined gene therapy with SLC plus sPD-1 did not induce remarkable autoimmune manifestations. Our findings provide a potent method of improving the antitumor effects of SLC and possibly other immunotherapeutic methods by local blockade of negative costimulatory molecules.
Department of Biochemistry and Molecular Biology, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, The People's Republic of China.
Yu-Fei
YF
He
Gui-Mei
GM
Zhang
Xiao-Hong
XH
Wang
Hui
H
Zhang
Ye
Y
Yuan
Dong
D
Li
Zuo-Hua
ZH
Feng
D000818:Animals; D000954:Antigens, Surface / Q000235:genetics* / Q000378:metabolism; D051017:Apoptosis Regulatory Proteins; D018122:B7-1 Antigen / Q000235:genetics* / Q000378:metabolism; D060890:B7-H1 Antigen; D001798:Blood Proteins / Q000235:genetics* / Q000378:metabolism; D002460:Cell Line; D054421:Chemokine CCL21; D019742:Chemokines, CC / Q000235:genetics*; D005260:Female; D015316:Genetic Therapy; D018840:HSP70 Heat-Shock Proteins / Q000494:pharmacology; D008114:Liver Neoplasms, Experimental / Q000628:therapy*; D008562:Membrane Glycoproteins; D051379:Mice; D008807:Mice, Inbred BALB C; D010455:Peptides / Q000235:genetics* / Q000378:metabolism; D061027:Programmed Cell Death 1 Ligand 2 Protein; D061026:Programmed Cell Death 1 Receptor; D014162:Transfection
D000954:Antigens, Surface; D051017:Apoptosis Regulatory Proteins; D018122:B7-1 Antigen; D060890:B7-H1 Antigen; D001798:Blood Proteins; C515479:Ccl21c protein, mouse; C498919:Cd274 protein, mouse; D054421:Chemokine CCL21; D019742:Chemokines, CC; D018840:HSP70 Heat-Shock Proteins; D008562:Membrane Glycoproteins; C491383:Pdcd1 protein, mouse; C556978:Pdcd1lg2 protein, mouse; D010455:Peptides; D061027:Programmed Cell Death 1 Ligand 2 Protein; D061026:Programmed Cell Death 1 Receptor