TLR9 agonism differentially impacts human NK cell-mediated direct killing and antibody-dependent cell-mediated cytotoxicity

TY - JOUR

T1 - TLR9 agonism differentially impacts human NK cell-mediated direct killing and antibody-dependent cell-mediated cytotoxicity

AU - Mahr, Anna R.

AU - Bennett-Boehm, Maia M.C.

AU - Rothemejer, Frederik H.

AU - Weber, Isabelle S.

AU - Regan, Alexander K.

AU - Franzen, Josh Q.

AU - Bisson, Cami R.

AU - Truong, Angela N.

AU - Olesen, Rikke

AU - Schleimann, Mariane H.

AU - Rauter, Claudia M.

AU - Smith, Audrey L.

AU - El-Gamal, Dalia

AU - Søgaard, Ole S.

AU - Tolstrup, Martin

AU - Denton, Paul W.

N1 - Publisher Copyright: © The Author(s) 2024.

PY - 2024/7

Y1 - 2024/7

N2 - There are two known mechanisms by which natural killer (NK) cells recognize and kill diseased targets: (i) direct killing and (ii) antibody-dependent cell-mediated cytotoxicity (ADCC). We investigated an indirect NK cell activation strategy for the enhancement of human NK cell killing function. We did this by leveraging the fact that toll-like receptor 9 (TLR9) agonism within pools of human peripheral blood mononuclear cells (PBMCs) results in a robust interferon signaling cascade that leads to NK cell activation. After TLR9 agonist stimulation, NK cells were enriched and incorporated into assays to assess their ability to kill tumor cell line targets. Notably, differential impacts of TLR9 agonism were observed—direct killing was enhanced while ADCC was not increased. To ensure that the observed differential effects were not attributable to differences between human donors, we recapitulated the observation using our Natural Killer—Simultaneous ADCC and Direct Killing Assay (NK-SADKA) that controls for human-to-human differences. Next, we observed a treatment-induced decrease in NK cell surface CD16—known to be shed by NK cells post-activation. Given the essential role of CD16 in ADCC, such shedding could account for the observed differential impact of TLR9 agonism on NK cell-mediated killing capacity.

AB - There are two known mechanisms by which natural killer (NK) cells recognize and kill diseased targets: (i) direct killing and (ii) antibody-dependent cell-mediated cytotoxicity (ADCC). We investigated an indirect NK cell activation strategy for the enhancement of human NK cell killing function. We did this by leveraging the fact that toll-like receptor 9 (TLR9) agonism within pools of human peripheral blood mononuclear cells (PBMCs) results in a robust interferon signaling cascade that leads to NK cell activation. After TLR9 agonist stimulation, NK cells were enriched and incorporated into assays to assess their ability to kill tumor cell line targets. Notably, differential impacts of TLR9 agonism were observed—direct killing was enhanced while ADCC was not increased. To ensure that the observed differential effects were not attributable to differences between human donors, we recapitulated the observation using our Natural Killer—Simultaneous ADCC and Direct Killing Assay (NK-SADKA) that controls for human-to-human differences. Next, we observed a treatment-induced decrease in NK cell surface CD16—known to be shed by NK cells post-activation. Given the essential role of CD16 in ADCC, such shedding could account for the observed differential impact of TLR9 agonism on NK cell-mediated killing capacity.

KW - ADCC

KW - Direct killing

KW - Human NK cells

KW - Immunophenotyping

KW - TLR9 agonist

UR - http://www.scopus.com/inward/record.url?scp=85196794756&partnerID=8YFLogxK

U2 - 10.1038/s41598-024-65576-2

DO - 10.1038/s41598-024-65576-2

M3 - Journal article

C2 - 38918496

AN - SCOPUS:85196794756

SN - 2045-2322

VL - 14

JO - Scientific Reports

JF - Scientific Reports

IS - 1

M1 - 14595

ER -