25KDa branched polyethylenimine increases interferon-γ production in natural killer cells via improving translation efficiency

Boosting tumor homing of endogenous natural killer cells via therapeutic secretomes of chemically primed natural killer cells

BACKGROUND

Natural killer (NK) cells play a critical role in modulating immune responses by secreting soluble factors, including chemotactic cytokines. Our previous study demonstrated the potent antitumor activity of Chem_NK, referring to NK cells chemically primed with 25 kDa branched polyethyleneimine. However, the potential of Chem_NK secretomes to educate other NK cells and enhance their tumor-homing ability remains unexplored.

METHODS

The effects of Chem_NK conditioned media (Chem CM) on NK cells were evaluated in vitro by examining chemokine receptor expression and migration toward cancer cells. In vivo, the impact of Chem_NK and Chem CM on endogenous NK cell populations was assessed using xenograft and syngeneic mouse tumor models. Cytokine array and signaling analyses were performed to identify factors secreted by Chem_NK and their role in activating recipient NK cells.

RESULTS

Chem CM effectively educated NK cells in vitro, enhancing chemokine receptor expression and improving their migration toward cancer cells. In vivo, adoptively transferred Chem_NK increased endogenous NK cell populations within xenograft tumors. Furthermore, direct injection of Chem CM into a syngeneic mouse tumor model significantly promoted endogenous NK cell infiltration into tumors and suppressed lung metastasis. Cytokine analysis revealed that Chem_NK secreted high levels of cytokines, which activated ERK1/2 signaling in recipient NK cells, leading to upregulation of chemokine receptors.

CONCLUSIONS

Chem_NK secretomes effectively enhance the tumor-homing ability of NK cells and amplify antitumor efficacy by educating other NK cells. These findings offer novel insights into activated NK cell-mediated immune communication and highlight the therapeutic potential of NK cell-derived secretomes in cancer therapy.

Engineering the physical characteristics of biomaterials for innate immune-mediated cancer immunotherapy

It has recently been recognized that the physical characteristics of biomaterials - such as size, structure, shape, charge, mechanical strength, hydrophobicity, and multivalency - regulate immunological functions in innate immune cells. In immuno-oncology applications, biomaterials are engineered with distinct physical properties to achieve desired innate immune responses. In this review, we discuss how physical characteristics influence effector functions and innate immune signaling pathways in distinct innate immune cell subtypes. We highlight how physical properties of biomaterials impact phagocytosis regulation, biodistribution, and innate immune cell targeting. We outline the recent advances in physical engineering of biomaterials that directly or indirectly induce desired innate immune responses for cancer immunotherapy. Lastly, we discuss the challenges in current biomaterial approaches that need to be addressed to improve clinical applicability.

Nano-chemical priming strategy to enhance TGF-β resistance and anti-tumor activity of natural killer cells

Immunotherapy based on adoptive transfer of natural killer (NK) cells is a promising strategy for circumventing the limitations of cancer treatments. However, components of the immunosuppressive tumor microenvironment (TME), such as transforming growth factor-beta (TGF-β), compromise the therapeutic efficacy of NK cells significantly. To address these limitations, we developed a novel method of engineering NK cells for adaptive transfer. The method is based on nanogels that serve two functions: (1) they overcome the TGF-β-mediated stress environment of the TME, and (2) they enhance the direct anti-tumor activity of NK cells. Previously, we demonstrated that cationic compounds such as 25 K branched polyethylenimine (25 K bPEI) prime NK cells, putting them in a 'ready-to-fight' state. Based on these findings, we designed nanogels that have two primary characteristics: (1) they encapsulate galunisertib (Gal), which is used clinically to inhibit TGF-β receptor activity, thereby blocking TGF-β signaling; and (2) they provide cells with a surface coating of 25 K bPEI. When grown in culture medium containing TGF-β, nanogel-treated NK cells demonstrated greater migration ability, degranulation activity, and cytotoxicity towards cancer cells than untreated NK cells. Additionally, the in vivo efficacy of nanogel-treated NK cells against PC-3 xenografts was significantly greater than that of Chem_NK cells primed by 25 K bPEI alone. These findings suggest that Gal-loaded 25 K bPEI-coated nanogels exert anti-tumor effects via chemical priming, as well suppressing the effects of TGF-β on NK cells. We also expect 25 K bPEI-based nanogels to have great potential to overcome the suppressive effects of the TME through their NK cell-priming activity and delivery of the desired chemicals.