Osteoclast-expanded supercharged NK cells perform superior antitumour effector functions.

Objective: Natural killer (NK) cells are the largest innate lymphocyte subset with potent antitumour and antiviral functions. However, clinical utilisation of human NK cells is hampered due to a lack of reliable methods to augment their antitumour potential. We demonstrated technology in which human NK cells were cocultured with osteoclasts in the presence of probiotic bacteria. This approach significantly augmented the antitumour cytotoxicity and polyfunctionality of human NK cells, resulting in the generation of supercharged NK (sNK) cells. Methods and analysis: We explored the proteomic, transcriptomic and functional characterisation of sNK cells using cell imaging, flow cytometric analysis, 51-chromium release cytotoxicity assay, ELISA, ELIspot, IsoPLexis single-cell secretome analysis, proteomic analysis, RNA analysis, western blot and enzyme kinetics. Results: We found that sNK cells were less susceptible to split anergy and tumour-induced exhaustion. Proteomic analyses revealed that sNK cells significantly increased their cell motility and proliferation. Single-cell transcriptomes uncovered sNK cells undertaking a unique differentiation trajectory and turning on STAT1, JUN, BHLHE40, ELF1, MAX and MYC regulons essential for augmenting antitumour effector functions and proliferation, respectively. Both proteomic and single-cell transcriptomes revealed that an increase in Cathepsin C helped to augment the quantity and function of Granzyme B. Conclusions: These results support that this unique method produces potent NK cells for clinical utilisation and delineate the molecular mechanisms associated with this process.