Biology subjects

Wiiger, M. T.

Publications and source records attributed to Wiiger, M. T..

3 recordsLinked to original sources

bioRxiv2025

Toggling of NKG2A expression drives functional specialization of iPSC-derived CAR NK cells

Induced pluripotent stem cell (iPSC)-derived natural killer (iNK) cells offer a promising platform for off-the-shelf immunotherapy against hematological malignancies. NK cell function is dynamically regulated through education driven by inhibitory receptors, including CD94/NKG2A and killer cell immunoglobulin-like receptors (KIR). However, the acquisition of inhibitory receptors in iNK cells and their role during differentiation and education remains poorly defined. In this study, we monitored receptor repertoires, transcriptional states, and functional responses in a range of genetically engineered iNK cell lines. Transcriptional reference mapping placed iNK cells close to cytokine-activated NKG2A+ CD56dim peripheral blood (PB) NK cells. Despite their early differentiation stage, iNK cells displayed a well-developed cytotoxic effector program, which was also reflected in high protein expression of Eomes, granzyme B, and activating receptors DNAM-1 and NKG2D. Acquisition of NKG2A by iNK cells was associated with a more differentiated transcriptional state and superior functional responses against a broad range of targets, including those expressing low to moderate levels of HLA-E, suggesting attenuated inhibitory signaling through NKG2A in iNKs. CRISPR knockout of {beta}2-microglobulin (B2) in iNK cells revealed that the functional potency of NKG2A+ iNK cells was independent of educating interactions with HLA-E in cis or trans. Finally, CRISPR-mediated ablation of NKG2A led to a spontaneous compensatory surface expression of CD94/NKG2C heterodimers, associated with enhanced IFN-{gamma} production and cytotoxic activity against target cells with forced high expression of single-chain {beta}2m-HLA-E-peptide trimers. Our results indicate an education-independent functional maturation of iNK cells, characterized by potent effector programs coupled with a favorable early-stage transcriptional profile.

immunology↗

bioRxiv2018

Induction of the BIMS Splice Variant Sensitizes Proliferating NK Cells to IL-15 Withdrawal

Adoptive transfer of allogeneic NK cells holds great promise for cancer immunotherapy. There is a variety of protocols to expand NK cells in vitro, most of which are based on stimulation with cytokines alone or in combination with feeder cells. Although IL-15 is essential for NK cell homeostasis in vivo, it is commonly used at supra-physiological levels to induce NK cell proliferation in vitro. As a result, adoptive transfer of such IL-15 addicted NK cells is associated with cellular stress due to sudden cytokine withdrawal. Here, we describe a dose-dependent addiction to IL-15 during in vitro expansion, leading to caspase-3 activation and profound cell death upon IL-15 withdrawal. NK cell addiction to IL-15 was tightly linked to the BCL-2/BIM ratio, which rapidly dropped during IL-15 withdrawal. Furthermore, we observed a proliferation-dependent induction of BIM short (BIM S), a highly pro-apoptotic splice variant of BIM, in IL-15 activated NK cells. These findings shed new light on the molecular mechanisms involved in NK cell apoptosis following cytokine withdrawal and may guide future NK cell priming strategies in a cell therapy setting.

immunology↗

bioRxiv2018

TRPML1-mediated Modulation of Dense-core Granules Tunes Functional Potential in NK Cells

Inhibitory signaling during natural killer (NK) cell education translates into increased responsiveness to activation; however the intracellular mechanism for functional tuning by inhibitory receptors remains unclear. We found that educated NK cells expressing self-MHC specific inhibitory killer cell immunoglobulin-like receptors (KIR) show accumulation of granzyme B, localized in dense-core secretory lysosomes, converged close to the centrosome. This discrete morphological phenotype persists in self-KIR+ NK cells independently of transcriptional programs that regulate effector function, metabolism and lysosomal biogenesis. The granzymeB dense, large secretory lysosomes in self-KIR+ NK cells were efficiently released upon target cell recognition, contributing to their enhanced cytotoxic capacity. Secretory lysosomes are part of the acidic lysosomal compartment, which has been shown to channel calcium and mediate intracellular signalling in several cell types. Interference of signaling from acidic Ca2+ stores in primary NK cells reduced both target-specific Ca2+-flux, degranulation and cytokine production. Furthermore, inhibition of PI(3,5)P2 synthesis or genetic silencing of the PI(3,5)P2-regulated lysosomal Ca2+-channel TRPML1 led to increased levels of granzyme B and enhanced functional potential. These results indicate an intrinsic role for lysosomal homeostasis in NK cell education.

immunology↗