siRNA knockdown of PD-L1 and PD-L2 in monocyte-derived dendritic cells only modestly improves proliferative responses to Gag by CD8(+) T cells from HIV-1-infected individuals.
BACKGROUND
Due to their capacity to elicit and regulate immunity, dendritic cells (DCs) are important targets to improve vaccination. Knowing that programmed death-1 (PD-1) high virus-specific T cells become functionally exhausted during chronic exposure to human immunodeficiency virus-1 (HIV-1), the development of a therapeutic DC-based HIV-1 vaccine might include strategies that downregulate PD-L1 and PD-L2 counter-receptors.


METHODS
After showing that monocyte-derived DCs rapidly upregulated PD-L1 and PD-L2 expression upon maturation with a variety of stimuli, e.g., Toll-like receptor ligands and cytokines, we determined that PD-L1 and PD-L2 expression could be knocked down by electroporation of a single small interfering RNA (siRNA) sequence twice at the monocyte and immature stages of DC development. This knockdown approached completion and was specific and lasting for several days.


RESULTS
We then added the PD-L1 and PD-L2 silenced monocyte-derived DCs to peripheral blood mononuclear cells from HIV-1-infected individuals along with pools of 15-mer HIV-1 Gag p24 peptides. However, in cultures from six patients, there was only a modest enhancing effect of PD-L1 and PD-L2 silencing on CD8(+) T cell proliferative responses to the DCs.


CONCLUSIONS
These findings suggest that, in monocyte-derived DCs, additional strategies than PD-L1 or PD-L2 blockade will be needed to improve the function of PD-1 high T cells.
Breton
Gaëlle
G
Laboratory of Cellular Physiology and Immunology, Chris Browne Center for Immunology and Immune Diseases, The Rockefeller University, New York, NY 10065, USA.
Yassine-Diab
Bader
B
Cohn
Lillian
L
Boulassel
Mohamed-Rachid
MR
Routy
Jean-Pierre
JP
Sékaly
Rafick-Pierre
RP
Steinman
Ralph M
RM
D015703:Antigens, CD / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D060890:B7-H1 Antigen; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology / Q000378:metabolism / Q000473:pathology; D049109:Cell Proliferation; D018920:Coculture Techniques; D003713:Dendritic Cells / Q000276:immunology / Q000378:metabolism* / Q000473:pathology / Q000821:virology; D016655:HIV Core Protein p24 / Q000737:chemistry / Q000276:immunology / Q000378:metabolism; D015658:HIV Infections / Q000235:genetics / Q000276:immunology* / Q000378:metabolism / Q000473:pathology; D015497:HIV-1 / Q000276:immunology* / Q000472:pathogenicity; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D008213:Lymphocyte Activation / Q000235:genetics; D009000:Monocytes / Q000473:pathology / Q000821:virology; D010446:Peptide Fragments / Q000737:chemistry / Q000276:immunology / Q000378:metabolism; D019151:Peptide Library; D061027:Programmed Cell Death 1 Ligand 2 Protein; D034741:RNA, Small Interfering / Q000235:genetics
D015703:Antigens, CD; D060890:B7-H1 Antigen; C423236:CD274 protein, human; D016655:HIV Core Protein p24; D036341:Intercellular Signaling Peptides and Proteins; C556977:PDCD1LG2 protein, human; D010446:Peptide Fragments; D019151:Peptide Library; D061027:Programmed Cell Death 1 Ligand 2 Protein; D034741:RNA, Small Interfering